Tesis: "Variations in flood activity"

1

Legrand, Caroline. "Simulation des variations de débits et de l’activité de crue du Rhône amont à partir de l’information atmosphérique de grande échelle sur le dernier siècle et le dernier millénaire". Electronic Thesis or Diss., Université Grenoble Alpes, 2024. http://www.theses.fr/2024GRALU011.

Texto completo

Resumen

Les crues sont des aléas naturels extrêmement destructeurs qui peuvent avoir des répercussionsconsidérables sur les écosystèmes et les sociétés. L’activité et l’intensité des crues pourraient êtreamplifiées par le changement climatique en cours. Quantifier les évolutions possibles pour les décenniesà venir est cependant difficile. L’approche classique consiste à estimer ces évolutions à partir deprojections hydrologiques obtenues par simulation à partir des scénarios météorologiques produitspour différents scénarios climatiques futurs. Ces scénarios météorologiques, qui doivent, entre autreschoses, être adaptés aux échelles spatiales et temporelles des bassins considérés, sont typiquementproduits avec des modèles de descente d’échelle à partir des conditions atmosphériques de grandeéchelle simulées par des modèles climatiques. Ces modèles de descente d’échelle sont soit dynamiquessoit statistiques. La possibilité de produire, avec ce type de modèles, des scénarios météorologiquespertinents est supposée acquise mais est rarement évaluée.Dans cette étude, nous avons évalué la capacité de deux chaînes de modélisation à reproduire,au cours du dernier siècle (1902-2009) et à partir de l’information atmosphérique de grande échelleuniquement, les variations temporelles observées des débits et des événements de crue du bassinversant du Rhône amont (10 900 km2). Les chaînes de modélisation sont constituées (i) de la réanalyseatmosphérique ERA-20C, (ii) soit du modèle de descente d’échelle statistique SCAMP, soit du modèlede descente d’échelle dynamique MAR et (iii) du modèle glacio-hydrologique GSM-SOCONT.Les évaluations sur les températures et les précipitations de bassin journalières soulignent la néces-sité d’une correction de biais pour les deux modèles de descente d’échelle. Pour éviter des simulationsnon pertinentes de la dynamique du manteau neigeux, en particulier pour les hautes altitudes, la cor-rection des biais est nécessaire non seulement pour les scénarios de précipitations et de températuresmais aussi pour les scénarios de gradients altimétriques de température pour la chaîne de descented’échelle dynamique.Les évaluations sur l’hydrologie des bassins montrent que les variations multi-échelles (journa-lières, saisonnières et interannuelles) observées des débits et les situations hydrologiques de bassefréquence (séquences d’étiage et événements de crue) sont globalement bien reproduites pour la pé-riode 1961-2009. Pour la première moitié du siècle, l’accord avec les débits de référence est plus faible,probablement en raison de la moindre qualité des données (données ERA-20C et de débits) et/ou decertaines hypothèses et choix de modélisation (e.g. calibration basée sur des signatures hydrologiques,hypothèse de stationnarité). Ces résultats ainsi que ceux sur les variations de l’activité de crue ob-tenus sur le siècle dernier permettent d’envisager l’utilisation des chaînes de modélisation pour descontextes climatiques différents.Dans une dernière partie, nous avons simulé les variations de l’activité de crue sur l’ensemble dudernier millénaire en utilisant les sorties d’un modèle climatique rendues disponibles par le projetPMIP (Paleoclimate Modelling Intercomparison Project). Les sorties du modèle climatique CESMLast Millennium Ensemble, composé de 12 membres, ont été statistiquement descendues en échelleau pas de temps journalier sur la période 850-2004 avec le modèle SCAMP (pour des raisons de coûtsde calcul) et utilisées comme forçages dans le modèle GSM-SOCONT.Les variations de l’activité de crue du Rhône amont simulées sur le dernier millénaire ont étécomparées à celles reconstituées à partir d’archives sédimentaires du lac du Bourget. Les résultatsobtenus suggèrent que les variations de l’activité de crue reconstituées sur cette période pourraientêtre liées à la variabilité interne du climat et non pas à un quelconque forçage atmosphérique degrande échelle
Floods are often destructive natural hazards that can have considerable implications on ecosystemsand societies. In many regions of the world, flood activity and intensity are expected to be amplifiedby the ongoing climate change. However, quantifying possible changes over the coming decades isdifficult. The classical approach is to estimate possible changes from hydrological projections obtainedby simulation using meteorological scenarios produced for different future climate scenarios. Amongother things, these meteorological scenarios have to be adapted to the spatial and temporal scalesof the considered basins. They are typically produced with downscaling models from the large-scaleatmospheric conditions simulated by climate models. Downscaling models are either dynamical orstatistical. The possibility of producing relevant meteorological scenarios with downscaling models istaken for granted, but is rarely assessed.In this study, we assessed the ability of two modelling chains to reproduce, over the last century(1902-2009) and from large-scale atmospheric information only, the observed temporal variations inflows and flood events in the Upper Rhône River catchment (10,900 km2). The modelling chains aremade up of (i) the ERA-20C atmospheric reanalysis, (ii) either the statistical downscaling modelSCAMP or the dynamical downscaling model MAR, and (iii) the glacio-hydrological model GSM-SOCONT.When compared to observations, the downscaled scenarios of daily temperatures and precipitationshighlight the need for a bias correction. This is the case for both downscaling models. For thedynamical downscaling chain, bias correction is additionally necessary for the temperature lapse ratescenarios to avoid irrelevant simulations of snowpack dynamics, particularly for high elevations.The observed multi-scale variations (daily, seasonal and interannual) in flows and low frequencyhydrological situations (low flow sequences and flood events) are generally well reproduced for theperiod 1961-2009. For the first half of the century, the agreement with the reference flows is wea-ker, probably due to lower data quality (ERA-20C and flow data) and/or certain assumptions andmodelling choices (e.g. calibration based on hydrological signatures, stationarity assumption). Theseresults, and those obtained over the last century on variations in flood activity, suggest that themodelling chains can be used in other climatic contexts.In the last part, we simulated variations in flood activity over the last millennium using cli-mate model outputs made available by the Paleoclimate Modelling Intercomparison Project (PMIP).Outputs from the climate model CESM Last Millennium Ensemble, made up of 12 members, werestatistically downscaled at the daily time step over the period 850-2004 with SCAMP (for reasons ofcomputational cost) and used as input to the GSM-SOCONT model.The simulated variations in flood activity in the Upper Rhône River over the last millennium werecompared with those reconstructed from the sediments cores of Lake Bourget. The results suggestthat the variations in flood activity reconstructed over this period could only be due to internalclimate variability and not to any large-scale atmospheric forcing

Los estilos APA, Harvard, Vancouver, ISO, etc.

2

Vye, Charlotte. "Flow Field Formation and Compositional Variations of Flood Basalt Eruptions". Thesis, Open University, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.518169.

Texto completo

Resumen

Characterisation of three lava flow fields from the Columbia River Basalt Group (CRBG), USA, reveals compositional heterogeneity on all scales, from adjacent lava lobes to the intra-crystal scale. Simple flow fields can be traced from vent areas to distal reaches, but those with multiple-layered lobes present a degree of complexity that make lava pathways and eruption sequences difficult to identify. A 3-D model based on field investigation of a single flow field establishes a volcanological context for geochemical sampling. Compositional v.ariation within each flow field suggests that small-scale geochemical heterogeneity is common within and between lobes of these flood basalt lavas. Lobe cores emplaced during the latter stages of an eruption have less evolved compositions and more enriched incompatible elements, suggesting progressive variation of magma composition caused by either recharge or sequential tapping of compositionally zoned magma. Progressive crustal contamination of magma during a single eruption is indicated by Re-Os isotope ratios. Initial 1870s/1880s ratios range from 1.405 in the earlier emplaced lava crust to 0.128 in the latter emplaced lava core. These values are more radiogenic than any known enriched sources (normative mantle -0.127, HIMU -0.15) consistent with previous data that indicate that neither an enriched source nor sub-continental lithospheric mantle can be the source of CRBG magma. Os isotope signatures can be explained by different degrees' of contamination of two isotopically distinct lithologies represented by the North American craton and Jurassic accreted terranes underlying the province. Intra-crystal Sr isotope analyses within a flow field record variable histories in an open magmatic system. Results suggest crystal residences in an increasingly contaminated melt within the crust with several recharge events of less-contaminated more primitive basaltic melt. Assembly of melt and crystal cargo occurred immediately prior to eruption without significant residence times in the final host magma. The combined compositional evidence suggests that an extensive shallow-crustal network of dykes and sills supplied magma to the CRBG eruptions.

Los estilos APA, Harvard, Vancouver, ISO, etc.

3

Eriksson, Tobias. "Variations in bioavailability of dissolved organic matter during a spring flood episode in northern Sweden /". Umeå : Swedish Univ. of Agricultural Sciences, 2004. http://epsilon.slu.se/9658927.pdf.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

4

Evans, S. T. "Variations in activity and psychological well-being in unemployed young adults". Thesis, University of Manchester, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377464.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

5

Bourne, Geoffrey S. "Actinide and fission product activity variations in inter-tidal marine macrophytes". Thesis, Cardiff Metropolitan University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306854.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

6

Lachowycz, Stefan M. "Records of, and controls on, temporal variations in activity at arc volcanoes". Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:152a237e-76d1-409e-ba6d-fbb50da87b85.

Texto completo

Resumen

Many attributes of volcanic activity, whether physical, geochemical/petrological, or geophysical, change over timescales from minutes to millions of years. Understanding the nature of these variations and their controls is essential both for hazard assessment and to understand volcanic and magmatic processes. Arc volcanism entails a relatively broad range of eruption styles and magma compositions, and thus wide-ranging hazards and a variety of eruption records. Despite their significance, records of activity for many arc volcanoes are inadequately characterised, so any temporal variability is poorly constrained. In this thesis, I investigate temporal variations in different styles of activity (dome-forming, Plinian-style, and effusive/glaciovolcanic) on a range of timescales (days-years, millennia, and hundreds of ky, respectively), from diverse records (seismicity, tephra deposits, and effusive eruption products), at four arc volcanoes. I analyse seismic time-series from Soufrière Hills Volcano (Montserrat) and Volcán de Colima (Mexico) using two statistical techniques, identifying temporal variation in the extent of long-range correlations and randomness in these data, which has potential to inform real-time monitoring and constrain eruptive processes. I also present new composition data for and review previous studies of tephra deposits from Volcán Hudson (Chile), revising its explosive eruption history and finding previously unrecognised shifts in the magma composition erupted through the Holocene. I also describe and analyse sequences of lithofacies from effusive eruptions of a range of magma compositions from Volcán Sollipulli (Chile), inferring varying extents of interaction with ice during their emplacement, and so changes in eruption style through time. These case studies highlight the importance of detailed characterisation of temporally varying records of volcanic activity, and some of the limitations of and uncertainties in these records and their interpretation.

Los estilos APA, Harvard, Vancouver, ISO, etc.

7

Byrdina, Svetlana. "Anomalous Self-Potential variations related to activity of Merapi volcano (Central Java)". Paris, Institut de physique du globe, 2004. http://www.theses.fr/2004GLOB0006.

Texto completo

Resumen

La thèse est consacrée à l'analyse des données d'une surveillance continue du Potentiel Spontané (PS), obtenues sur le volcan Merapi, dans le but d'identifier les signaux de PS liées à l'activité volcanique. La comparaison dePS avec la météorologie montre que les propriétés les plus manifestes dans les données de PS sont produites par des variations d'infiltration d'eau de pluie et de pression atmosphérique. Les techniques spéciales de traitement des données ont été developpé pour reduire les effets météorologiquies. Pour identifier les signaux associés à l'activité volcanique, les séries temporelles de PS ont été comparées aux données de sismicité large bande. Un rapport statistiquement stable a été trouvé entre les signaux anormaux de PS et la sismicité de periode ultra-longue (ULP). L'occurrence des anomalies de PS liées à la sismicité ULP pourrait être provoquée par l'effet électro-cinétique du flux de fluide dans la proximité du dôme de lave
The thesis is devoted to the analysis of the continuous Self-Potential (SP) monitoring date registered on Merapi volcano, with the purpose to identify related to volcanic activity SP signals. The comparison between SP and meteorolopical parameters shows that the most prominent features in the SP data are produced by rain water infiltration and air pressure. Special techniques of data processing were developed to reduce the meteorological influence on the SP. To identify the signals associated with volcanic activity, the SP time series were compared to broadband seismicity. A statistically stable relationship was found between anomalous SP signals and ultra-long-period (ULP) seismicity with dominant periods <100s. In contrast, the anomalies were not present in ground temperature data nor in SP data recorded 1km from the summit. The occurrence of SP anomalies associated with ULP-seismicity might be caused by the electro-kinetic effect of fluid flow in subsurface near the lava dome

Los estilos APA, Harvard, Vancouver, ISO, etc.

8

Sahlén, Adam. "Muscle activity in m.pectoralis major during bench press variations in healthy young males". Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-29361.

Texto completo

Resumen

Background. The bench press is a commonly used resistance training exercise for targeting the chest musculature. During hypertrophy training, different variations of bench press are often used to isolate different segments (pars clavicularis, pars sternocostalis and pars abdominals) of the chest muscle m.pectoralis major. Commonly used variations of the bench press are decline bench press (less than 0° from horizontal) and incline bench press (more than 0° from horizontal). Some research has been done into these variations of bench angle and their effect on muscle activation; however other commonly used bench angles is yet to be investigated. Aim. The aim of this study was to examine if there were any difference in muscle activity in the three segments of m.pectoralis majors while performing three different barbell bench press variations with different bench angles to obtain a greater understanding of m.pectoralis major activation and possibly optimize hypertrophy training in above mentioned muscles segments. Method. 13 healthy male (age: 23± 3.8 year and BMI: 24.3 ±1.8 kg/m2) participated in this single group study. EMG was used to measure muscle activity in m.pectoralis major's three segments. Test subjects performed 1 set of 6 repetitions on each bench press variation at a relative load of 6RM. An maximal voluntary isometric contraction (MVIC) test was performed and set as 100 percent reference value for comparison muscle activity in various angles. Results. While performing the decline bench press and the incline bench press, the muscle activity in pars clavicularis displayed a strong trend of a lower muscle activity (decline: p= 0.055 and incline: p=0.052) in comparison to the flat bench press. Muscle activity in pars sternocostalis while performing the incline bench press was significantly lower in comparison to the flat bench press (flat: p<0.001 and decline: p<0.001). Muscle activity in pars abdominals while performing the decline bench press was significantly higher (p=0.013) in comparison to the flat bench press. Muscle activity in pars abdominals while performing the incline bench press were significantly lower than both the flat and decline bench press (incline: p<0.001 and decline: p<0.001). Conclusion. For a better isolation of the pars abdominals segment, the decline bench press should be used. Muscle activity in pars sternocostalis did not show any significant difference between flat and decline bench press and could be isolated with either of these two exercises. The muscle activity in pars clavicularis showed a strong trend of higher activity while performing the flat bench press compared to the decline and incline bench press, however findings regarding the pars clavicularis differs between studies.

Los estilos APA, Harvard, Vancouver, ISO, etc.

9

Gäddnäs, Helena. "Long-term oral nicotine treatment and daily variations in brain monoamines and motor activity". Helsinki : University of Helsinki, 2002. http://ethesis.helsinki.fi/julkaisut/mat/farma/vk/gaddnas/.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

10

Harrington, Debra J. "Effect of river stage variations and flood events on trace metal mobilization and transport in the Apalachicola River Basin, NW Florida". Tallahassee, Fla. : Florida State University, 2001. http://purl.fcla.edu/fsu/lib/digcoll/etd/1191553.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

11

O'Connell, Sophie. "Seasonal variations in lifestyle behaviours and their relationship with indicators for poor health". Thesis, Loughborough University, 2013. https://dspace.lboro.ac.uk/2134/11716.

Texto completo

Resumen

The increasing evidence of associations between physical activity, sedentary behaviour, sleep duration and diet and both immediate and long term health implications is of public health concern. There is a need to further our understanding of the patterns of these behaviours and how they affect poor health indicators individually and simultaneously. This thesis aims to advance the current literature by investigating associations between multiple lifestyle behaviours and indicators for poor health and identifying patterns of physical activity, sedentary behaviour, sleep duration and dietary intake. Anthropometric measurements and bioelectrical impedance analysis were collected from 72 UK adults. These participants were asked to wear an ActiGraph GT1M accelerometer to objectively measure their physical activity and sedentary behaviour across 7 consecutive days. Over these 7 days, participants also completed a self-report daily sleep diary and a food frequency questionnaire. Participants were asked to complete these measurements at 4 different time points across the year in order to capture these behaviours over each season; 46 participants completed all 4 seasons. Using the data collected from the 72 participants who completed at least 1 season, regression analyses were conducted to identify associations between lifestyle behaviours and indicators for poor health. Repeated measures ANOVAs were conducted on data from 52 participants who provided the full 7 days of data during their initial measurement period to assess day of the week variations in physical activity, sedentary behaviour and sleep patterns. Repeated measures ANOVAs were also conducted on physical activity, sedentary behaviour, sleep and dietary intake data provided by the 46 participants who provided 4 seasons of data to assess seasonal variation. This thesis demonstrated that in a sample of relatively active, UK adults, time spent in moderate-vigorous physical activity and sedentary behaviour had a negative association with BMI and body fat percentage, increased time spent in moderate-vigorous physical activity was also associated with decreases in waist circumference. Light intensity physical activity had a positive association with BMI, body fat percentage and diastolic blood pressure. There were significant day of the week variations in light intensity physical activity, sedentary behaviour and time spent in bed, with light intensity physical activity and time in bed being significantly higher on a Sunday, whilst sedentary behaviour was significantly lower on a Sunday in this sample of UK adults. In addition to day of the week variations, there were seasonal variations in light intensity physical activity, sedentary behaviour and time spent in bed and sleep durations (weekdays only). Over the winter months, light intensity physical activity was significantly lower, whilst sedentary behaviour, time in bed and total sleep time was significantly higher. No seasonal variations in time spent in moderate-vigorous intensity physical activity or diet were observed in the present sample. This thesis demonstrates that lifestyle behaviours that have been found to affect health do vary over the week and across different seasons. This research has implications for surveillance studies which estimate these behaviours at one time point throughout the year, and also for interventions aimed at improving these behaviours which are implemented at just one time period of the year. Strategies for overcoming barriers to PA under unfavourable environmental conditions will be needed for this to be achieved, in addition to interventions reducing SB, even in the winter months.

Los estilos APA, Harvard, Vancouver, ISO, etc.

12

Bastien, Fabienne Anne. "Empirically Interrelating Stellar Chromospheric Activity, Photometric Variability and Radial Velocity Variations to Enhance Planet Discovery". Thesis, Vanderbilt University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3584409.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

13

Jarzebowski, Léonard. "Unraveling variations in ribosome biogenesis activity in the mouse hematopoietic system at homeostasis in vivo". Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066402/document.

Texto completo

Resumen

Les cellules souches (CS) se démarquent des progéniteurs et cellules différenciées à de nombreux égards. Notamment, les CS présentent des caractéristiques particulières dans des processus cellulaires fondamentaux, et il a été récemment proposé que la biogenèse des ribosomes (BiRi) participe à la régulation des CS. Pendant ma thèse, j’ai utilisé diverses approches pour étudier le rôle et la régulation de la BiRi dans des populations de CS, in vivo et ex vivo dans des modèles murins.Grâce à un modèle d’inactivation génétique du facteur de BiRi Notchless (Nle), j’ai participé à l’étude de son rôle dans le lignage hématopoïétique et l’épithélium intestinal adultes, et cours du développement embryonnaire précoce. In vivo, la perte constitutive de Nle entraîne une létalité embryonnaire, et j’ai montré ex vivo que l’inactivation de Nle dans des CS embryonnaires induit une réponse au stress ribosomique médiée par le suppresseur de tumeur p53, et des défauts de prolifération/survie. L’induction de la perte de Nle chez l’adulte active également p53 dans les CS hématopoïétiques et intestinale, entraînant leur rapide élimination.En parallèle, j’ai utilisé plusieurs méthodes pour mesurer l’activité de BiRi des progéniteurs immatures et CS hématopoïétiques (CSH) à l’homéostasie, in vivo chez la souris adulte. J’ai ainsi mis en évidence des variations de l’activité de BiRi dans ces populations, révélant notamment une activité de BiRi des CSH jusqu’ici insoupçonnée du fait de leur quiescence.Dans l’ensemble, mon travail renforce l’idée d’un rôle de la BiRi dans la régulation des CS, et apporte une meilleure compréhension de la régulation de ce processus dans le lignage hématopoïétique
Stem cells (SCs) differ from progenitors and differentiated cells on many aspects. Notably, SCs display particular characteristics in fundamental cellular processes, and ribosome biogenesis (RiBi) has recently been proposed to play an important role in the regulation of SCs. During my thesis, I have used various approaches to study the role and regulation of RiBi in SC populations, using in vivo and ex vivo mouse models.Using genetic inactivation of the RiBi factor Notchless (Nle), I have participated to the analysis of its role in the adult hematopoietic system and intestinal epithelium, and in the establishment of the first cell lineages during early embryogenesis. In vivo, constitutive Nle deficiency causes early embryonic lethality, and I showed ex vivo that Nle inactivation in embryonic SCs induces a ribosomal stress response mediated by the tumor suppressor p53, and proliferation/survival defects. Conditional Nle inactivation in the adult mouse also induces activation of p53 in hematopoietic and intestinal SCs in vivo, leading to their rapid elimination.In parallel, I have used different methods to analyze the RiBi activity of hematopoietic SCs (HSCs) and immature progenitors at homeostasis, in vivo in the adult mouse. Thus, I have unraveled variations in the RiBi activity of these populations, and notably uncovered previously unsuspected RiBi activity in HSCs despite their quiescent state.Altogether, my work supports the hypothesis of a role for RiBi in the regulation of SCs and provides better understanding of the activity of this process during hematopoietic differentiation

Los estilos APA, Harvard, Vancouver, ISO, etc.

14

Jarzebowski, Léonard. "Unraveling variations in ribosome biogenesis activity in the mouse hematopoietic system at homeostasis in vivo". Electronic Thesis or Diss., Paris 6, 2016. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2016PA066402.pdf.

Texto completo

Resumen

Les cellules souches (CS) se démarquent des progéniteurs et cellules différenciées à de nombreux égards. Notamment, les CS présentent des caractéristiques particulières dans des processus cellulaires fondamentaux, et il a été récemment proposé que la biogenèse des ribosomes (BiRi) participe à la régulation des CS. Pendant ma thèse, j’ai utilisé diverses approches pour étudier le rôle et la régulation de la BiRi dans des populations de CS, in vivo et ex vivo dans des modèles murins.Grâce à un modèle d’inactivation génétique du facteur de BiRi Notchless (Nle), j’ai participé à l’étude de son rôle dans le lignage hématopoïétique et l’épithélium intestinal adultes, et cours du développement embryonnaire précoce. In vivo, la perte constitutive de Nle entraîne une létalité embryonnaire, et j’ai montré ex vivo que l’inactivation de Nle dans des CS embryonnaires induit une réponse au stress ribosomique médiée par le suppresseur de tumeur p53, et des défauts de prolifération/survie. L’induction de la perte de Nle chez l’adulte active également p53 dans les CS hématopoïétiques et intestinale, entraînant leur rapide élimination.En parallèle, j’ai utilisé plusieurs méthodes pour mesurer l’activité de BiRi des progéniteurs immatures et CS hématopoïétiques (CSH) à l’homéostasie, in vivo chez la souris adulte. J’ai ainsi mis en évidence des variations de l’activité de BiRi dans ces populations, révélant notamment une activité de BiRi des CSH jusqu’ici insoupçonnée du fait de leur quiescence.Dans l’ensemble, mon travail renforce l’idée d’un rôle de la BiRi dans la régulation des CS, et apporte une meilleure compréhension de la régulation de ce processus dans le lignage hématopoïétique
Stem cells (SCs) differ from progenitors and differentiated cells on many aspects. Notably, SCs display particular characteristics in fundamental cellular processes, and ribosome biogenesis (RiBi) has recently been proposed to play an important role in the regulation of SCs. During my thesis, I have used various approaches to study the role and regulation of RiBi in SC populations, using in vivo and ex vivo mouse models.Using genetic inactivation of the RiBi factor Notchless (Nle), I have participated to the analysis of its role in the adult hematopoietic system and intestinal epithelium, and in the establishment of the first cell lineages during early embryogenesis. In vivo, constitutive Nle deficiency causes early embryonic lethality, and I showed ex vivo that Nle inactivation in embryonic SCs induces a ribosomal stress response mediated by the tumor suppressor p53, and proliferation/survival defects. Conditional Nle inactivation in the adult mouse also induces activation of p53 in hematopoietic and intestinal SCs in vivo, leading to their rapid elimination.In parallel, I have used different methods to analyze the RiBi activity of hematopoietic SCs (HSCs) and immature progenitors at homeostasis, in vivo in the adult mouse. Thus, I have unraveled variations in the RiBi activity of these populations, and notably uncovered previously unsuspected RiBi activity in HSCs despite their quiescent state.Altogether, my work supports the hypothesis of a role for RiBi in the regulation of SCs and provides better understanding of the activity of this process during hematopoietic differentiation

Los estilos APA, Harvard, Vancouver, ISO, etc.

15

Mbao, Chabala. "An analysis of flood activity over the past century based on the sedimentary deposits in the Mfolozi floodplain". Thesis, Rhodes University, 2017. http://hdl.handle.net/10962/53711.

Texto completo

Resumen

Floods are natural phenomena that are of widespread interest to the scientific community, particularly in the context of understanding the impact of climate change as well as changing land use patterns and the security of infrastructure such as towns and roads. In northern KwaZulu-Natal, large flood events have been a reoccurring feature over the past century. The geographical position and extent of the region means that is affected by both inland and coastal weather phenomena, each with the potential to cause large flood events. While information pertaining to large floods in the region in the form of flow data is readily available, flow data is often incomplete and limited in terms of how far back in time the records extend. The Mfolozi River floodplain itself also houses a record of flood activity in the region in the form of sedimentary deposits, which have the potential to reveal flood activity over a much longer timescale, even when monitoring of flood activity in the region was not present. Establishing a link between the hydrological and sedimentary features of floods may be useful in establishing a record of flood activity extending beyond the limits of historical records. The aim of this project was to construct a record of major flood events on the Mfolozi River floodplain over the last century and determine their source. The first objective involved establishing the history of flood events in the Mfolozi River catchment utilising hydrological data recorded throughout the catchment. Thirty nine different large floods (defined as being over 800 m3.s-1) were recorded on the floodplain over the past century. The data also highlighted differences in the extent of known coastal and inland systems (tropical cyclones and cut-off lows respectively), allowing for inferences to be made about the area of the catchment most likely affected by each event; some flood events were identified as having mostly affected the upper reaches of the catchment, while others mostly affected the lower reaches, closer to the coast. The second objective was to identify the various physical, mineralogical and geochemical features of the sediment deposited on the Mfolozi floodplain. Multiple individual flood deposits were identified in the sedimentary record, with sediment tracing analysis providing insight into the source of the deposits within the catchment; no traces of igneous or metamorphic material could be found within the sediment. The source rocks were identified as mostly quartzite, with minor shale and sandstone deposits as well. This put the source of the sediment in the upper to middle reaches of the catchment. The sedimentary analysis was combined with the hydrological records to establish a chronology of flood events extending back to the 1960's. Unfortunately, this record could not be extended further due to the limited amount of sediment collected as well the limits of readily available analytical techniques; radionuclide dating methods were unsuccessful due to the low amounts of fallout radionuclides present in the sediment. The study has however successfully established a history of flood events in the region, as well as providing a link between the hydrological and sedimentary features of flood events that could potentially be useful for current and future research.

Los estilos APA, Harvard, Vancouver, ISO, etc.

16

Towers, Christopher Michael. "The detection of conductivity variations within the human head using induced current electrical impedance tomography techniques". Thesis, University of Sheffield, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286870.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

17

Cripps, Jennifer Ann. "Environmental impact of Deccan Trap flood basalt volcanism : assessment of regional floral responses to late Cretaceous-early Tertiary activity". Thesis, Open University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272896.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

18

Younes, Rabih Halim. "Toward Practical, In-The-Wild, and Reusable Wearable Activity Classification". Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/83503.

Texto completo

Resumen

Wearable activity classifiers, so far, have been able to perform well with simple activities, strictly-scripted activities, and application-specific activities. In addition, current classification systems suffer from using impractical tight-fitting sensor networks, or only use one loose-fitting sensor node that cannot capture much movement information (e.g., smartphone sensors and wrist-worn sensors). These classifiers either do not address the bigger picture of making activity recognition more practical and being able to recognize more complex and naturalistic activities, or try to address this issue but still perform poorly on many fronts. This dissertation works toward having practical, in-the-wild, and reusable wearable activity classifiers by taking several steps that include the four following main contributions. The dissertation starts by quantifying users' needs and expectations from wearable activity classifiers to set a framework for designing ideal wearable activity classifiers. Data collected from user studies and interviews is gathered and analyzed, then several conclusions are made to set a framework of essential characteristics that ideal wearable activity classification systems should have. Afterwards, this dissertation introduces a group of datasets that can be used to benchmark different types of activity classifiers and can accommodate for a variety of goals. These datasets help comparing different algorithms in activity classification to assess their performance under various circumstances and with different types of activities. The third main contribution consists of developing a technique that can classify complex activities with wide variations. Testing this technique shows that it is able to accurately classify eight complex daily-life activities with wide variations at an accuracy rate of 93.33%, significantly outperforming the state-of-the-art. This technique is a step forward toward classifying real-life natural activities performed in an environment that allows for wide variations within the activity. Finally, this dissertation introduces a method that can be used on top of any activity classifier that allows access to its matching scores in order to improve its classification accuracy. Testing this method shows that it improves classification results by 11.86% and outperforms the state-of-the-art, therefore taking a step forward toward having reusable activity classification techniques that can be used across users, sensor domains, garments, and applications.
Ph. D.

Los estilos APA, Harvard, Vancouver, ISO, etc.

19

Chénier, Martin. "Impact of seasonal variations, nutrients, pollutants and dissolved oxygen on the microbial composition and activity of river biofilms". Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=85144.

Texto completo

Resumen

Biofilm communities were cultivated in rotating annular bioreactors using water from the South Saskatchewan River. The impacts of seasonal variations, nutrients, pollutants and dissolved oxygen on the activity and composition of the biofilms were assessed by using a combination of microcosm assays and molecular biology techniques.
The seasonal pattern in nitrification, denitrification and hexadecane mineralization, and in the occurrence of nirK in the South Saskatchewan River biofilms was: fall greater than winter, which was equivalent to spring. Hexadecane mineralization was higher in fall 1999 than in fall 2001, denitrification was similar in these two years, and no seasonal pattern of nitrification was observed.
The addition of combined nutrients (C, N, and P) resulted in significant increases in the measured bacterial activities and in the predominance of alkB, nirS and nirK in all seasons and years. The addition of individual nutrients did not stimulate hexadecane mineralization, denitrification, and the PCR amplification of nirS and nirK. In fall 1999, CNP and, to a lesser extent P, stimulated nitrification, whereas in fall 2001, no pattern was observed. The results showed that nutrients, especially P, were limiting for bacterial activities, and that the biofilm activities and composition varied with nutrient availability and time of year.
At the concentration assessed (1 ppb), hexadecane partially inhibited denitrification to similar extents in both years, had a negative impact on nitrification and hexadecane mineralization in fall 1999, and a positive impact on these two latter activities in fall 2001. Nickel (0.5 mg liter-1 ) negatively affected denitrification but had no effect on hexadecane mineralization. The alkB and nirS genes were less predominant and absent, respectively, in biofilms grown in the presence of nickel. DGGE analyses indicated that nickel reduced the biofilm bacterial diversity.
The results presented herein provide much needed information on the microbial ecology of river biofilms, and on the impact and interactive effects of pollutant and nutrient inputs on these biofilms. These results and the techniques used in this project can be applied to monitor environmental effects of anthropogenic activities on aquatic biofilms, and can contribute to establish or revise environmental regulations.

Los estilos APA, Harvard, Vancouver, ISO, etc.

20

Humann, Michael. "Deliberation and implementation activity in forced-choice decision making environments : variations in information processing within a neurocognitive framework". Thesis, University of Liverpool, 2011. http://livrepository.liverpool.ac.uk/5653/.

Texto completo

Resumen

This thesis examined decision making in the context of forced-choice situations, as characterised by high-risk consequences and time-limited conditions, within an experimental decision paradigm. By mapping onto basic decision-making stages relating to evaluation, deliberation and implementation of a choice, this research looks at how environmental conditions (emotion) and information (advice) affect cognitive processing in forced-choice or “do or don’t” scenarios. In order to identify these variations on a more fundamental level, a methodological framework was developed, which incorporates neurocognitive, behavioural and qualitative measures. Results identified the distinct sequence of cognitive processes as predicted from basic decision-making models. When individuals lacked any meaningful information to assist in solving the tasks, their responses varied based on the consequential conditions they faced, leading to an accelerated engagement with the decision and faster response, the riskier the outcome. On the other hand, when information was available during the task, differences in responses followed predictions about information processing and cognitive effort required for the different levels of clarity. Here, the consequential conditions did not affect performance, as individuals prioritised the information available. Further, when solving a task lacking any meaningful information on which to base their choice, individuals still engaged in redundant deliberation. Taken together, the research suggests that outcome uncertainty and task ambiguity have a demonstrable effect on the decision-making process. This research, incorporating neurocognitive measures, showed a robust framework to advance current understanding about the interplay of affecting factors and basic decision-making processes. Providing an additional reference, this approach contributes to a more in-depth picture of underlying processes.

Los estilos APA, Harvard, Vancouver, ISO, etc.

21

Bompy, Félix. "Approche écologique et écophysiologique de l’effet des variations saisonnières sur la croissance des arbres dans les forêts côtières inondables des Antilles". Thesis, Antilles-Guyane, 2013. http://www.theses.fr/2013AGUY0674/document.

Texto completo

Resumen

Les forêts côtières inondables (FCI) des régions tropicales et subtropicales remplissent des fonctions écologiques nécessaires aux écosystèmes marins côtiers situés en aval et aux populations humaines vivant à proximité Aux Antilles, les mangroves et les forêts marécageuses à Pterocarpus officinalis sont structurés par des espèces ligneuses qui ont développé des adaptations particulières à la salinité, à l’inondation et aux substrats meubles sur lesquels elles reposent. Dans des contextes climatiques à forte saisonnalité, les saisons sèches prolongées entraînent de fortes variations de la salinité et du niveau de la nappe, que le changement climatique devrait amplifier. Les modèles climatiques de la région Caraïbe prévoient des saisons sèches plus sèches liées à une baisse des précipitations de 20 à 50 %. Or, la question des capacités de résistance et d’acclimatation des espèces ligneuses des FCI à des variations saisonnières marquées de leur environnement édaphique a été peu traitée dans la littérature scientifique.L’objectif de ce travail de thèse a été double. Il s’est agi, d'une part, de caractériser la structure et la croissance de faciès de végétation représentatifs des FCI antillaises et de mettre en évidence leurs déterminants. A cet effet, des individus adultes, des espèces ligneuses dominantes des FCI, (Avicennia germinans, Laguncularia racemosa, Pterocarpus officinalis, Rhizophora mangle), dans cinq faciès de végétation sur le gradient terre-mer, ont été suivis sur l'île de Grande-Terre (Guadeloupe). D’autre part, les effets de variations salines extrêmes sur la croissance et l’écophysiologie de ces quatre espèces ont été évalués au stade plantule par une expérience en conditions contrôlées.A travers cette étude, il a été montré que les différences de salinité et de fertilité entre les stationspermettent d’expliquer la composition et la structure des peuplements de FCI. Cette étude a égalementmontré que P. officinalis peut se maintenir dans une gamme de salinité plus large que ne l'indiquait lalittérature.Dans le contexte des Antilles où les marnages sont faibles, la saisonnalité du climat entraine des variations saisonnières importantes d’un ensemble de descripteurs édaphiques tels que le niveau de la nappe, la salinité du sol, le pH et le potentiel RedOx. L’inondation et la salinité des sols sont fortement corrélées aux variations mensuelles des précipitations. Les périodes sèches sont accompagnées de salinités élevées et d’une baisse du niveau de la nappe allant jusqu’à l’exondation des sols dans toutes les stations suivies. Les stress environnementaux liés à la saisonnalité entrainent une baisse de la production primaire. L’accroissement cambial mensuel des individus est fortement corrélé avec les précipitations et l’intensité du vent. Dans les stations de mangrove, la sècheresse édaphique régule la production primaire des palétuviers. En forêt marécageuse, la part de la sècheresse atmosphérique semble plus importante pour expliquer la production de P. officinalis. Aussi, les sècheresses édaphique et atmosphérique doivent être prises en compte toutes deux pour modéliser efficacement la croissance des peuplements des FCI.Lors de la saison sèche, le stress le plus important est le stress hydrique, lié à la diminution de la teneur en eau du sol et à l’augmentation de la salinité, qui entraine des contraintes physiologiques sur les palétuviers (ajustements stomatiques, pertes de surface foliaire et de conductivité hydraulique). Le stress ionique, lié à la toxicité des ions Na+ et Cl-, permet aussi d’expliquer une partie de la contrainte sur l’assimilation en carbone. En saison sèche, l’aération des sols ne se traduit pas par une amélioration des performances de croissance chez toutes les espèces. Aussi, la croissance cambiale maximale de toutes les espèces de FCI est réalisée en saison des pluies lorsque la salinité est faible et les niveaux d’inondation élevés
In tropical and subtropical regions, flooded coastal forests provide essentials goods and services to local communities. In the Antilles, mangrove forests and the Pterocarpus officinalis swamp forest host tree species that are adapted to salinity, flooding and loose substrates. In areas were climatic seasonality is strong, dry seasons lead to strong fluctuations of soil salinity and water table level ; that climate change is likely to make stronger again. Climate model for the Caribbean project drier dry seasons with a decease of 20 to 50 % in annual rainfall amounts. However, resistance and acclimation ability of flooded coastal forest’s species to strong environmental fluctuations still remain poorly studied.This thesis aims two objectives. On the one hand, it aims to characterize the forest structure and monthly growth of vegetation structures representative of the Antillean flooded coastal forests and to highlight their determinants. In this respect, adult trees of the four dominant species of local flooded coastal forest (Avicennia germinans, Laguncularia racemosa, Pterocarpus officinalis, Rhizophora mangle), in five stations along a sea – land gradient were monitored on the Grande-Terre island (Guadeloupe). On the other hand, the effects of salinity variation patterns and salinity levels on growth performances and physiology of seedlings from the four same species were investigated through a greenhouse experiment.This study shows that differences among average salinity and soil fertility explain the vegetation structure of flooded coastal forest. It also extents, in the literature, the range of salinity in which P. officinalis can stand at the tree stage.In the Antilles were tidal range is small, climate seasonality lead to strong edaphic seasonal variations in water table level, soil salinity, pH and RedOx potential. Flooding and soil salinity are strongly correlated to monthly rainfall amounts: dry periods lead to high salinity and to a decrease in water table level under the soil surface. Seasonal environmental stresses lead to a decrease of primary production. Cambial growth was strongly correlated to monthly precipitation and average wind speed. In mangrove stations, edaphic drought determines primary production of mangrove trees, when, in swamp forest stations, atmospheric drought determines an important part of P. officinalis’ primary production.During the dry season, water stress is the more important environmental stress, both by the decrease in soil humidity and the increase in soil salinity, and leads to physiological strains (stomatal adjustment, loss of leaf area and hydraulic conductivity) for mangrove trees. Ionic toxicity of ions Na+ and Cl- also explains a part of the strain on carbon assimilation. During the dry season, re oxygenation of soils via low water table level does not lead to an increase of physiological traits. Thus, maximum cambial growth of all species is observed during the rainy season, when salinity is low and water table level is high.Flooded coastal forest’s species do not have the same ability to recover after a dry episode. In all the studied stations, A. germinans’ cambial growth rises back as soon as the rainy season starts, when, for one station, cambial growth of L. racemosa and R. mangle stay null during the three first month of the rainy season. This low ability to recover after a dry episode is correlated to a stronger impact of the dry season on the physiological traits of these two species.The greenhouse experiment shows that salinity variation patterns are to be taken into consideration for explaining seedlings’ growth and salinity tolerance. A stronger salinity increase impacts the growth of all the studied species; a punctual drop of salinity highlights that flooded coastal forest’s species differ in ability to take advantage of a low salinity episode. These results are coherent with field observations as cambial growth was fairly explained by monthly precipitation

Los estilos APA, Harvard, Vancouver, ISO, etc.

22

Venkat, Ratnam Madineni y Christoph Jacobi. "Study on stratospheric gravity wave activity: global and seasonal variations deduced from the CHAllenging Minisatellite Payload (CHAMP)-GPS Satellite". Wissenschaftliche Mitteilungen des Leipziger Instituts für Meteorologie ; 30 = Meteorologische Arbeiten aus Leipzig ; 8 (2003), S. 136-148, 2003. https://ul.qucosa.de/id/qucosa%3A15246.

Texto completo

Resumen

Global analyses of gravity wave activity in the stratosphere are presented for the first time using German Low Earth Orbit (LEO) satellite CHAMP. Temperature profiles obtained from CHAMP/GPS radio occultations are first compared with ground based instruments. In general, good agreement is found between these different techniques. Monthly mean Ep values of potential energy, Ep values, being a measure of gravity wave activity, which is estimated with radiosonde observations are compared with CHAMP/GPS data and found that radiosonde observed Ep values are higher than those estimated with radio occultations. There exists a strong diurnal variation of gravity wave activity. From the global morphology of gravity wave activity, large values Ep are noticed even at mid latitudes during winter months besides the tropical latitudes but not during equinoxes suggesting that wave activity, especially at stratospheric heights, is not only modulated due to orography (mountain/lee waves) but mainly depends on seasonal variations at respective latitudes. Latitudinal and vertical variation of gravity wave activity reveals the existence of large Ep values below 25 km and low values in between 25 and 30 km in all the seasons near equator. During southern hemisphere winter, large values are noticed. During equinoxes, these values are nearly same between northern and southern hemispheres (NH and SH) at mid-latitudes. During the months of solstices, Ep distribution involves a larger hemispheric asymmetry at middle and higher latitudes. Large values of Ep are noticed at SH polar latitudes during Sep-Oct months and the latitude range is wider (±300° latitude in both the hemispheres) with large Ep values in all the seasons except winter.
Zum ersten Mal werden globale Analysen der Schwerewellenaktivität, bestimmt unter Verwendung des CHAMP LEO-Satelliten, vorgestellt. Temperaturprofile der CHAMP/RO-Okkultationen werden zunächst mit bodengestützten Messungen verglichen. Generell ist die Übereinstimmung gut. Monatliche Mittelwerte der potentiellen Energie Ep, die als Maß für Schwerewellenaktivität gilt, wurden aus Radisonden- und CHAMP-Messungen bestimmt, wobei die CHAMP-Daten höhere Werte lieferten. Es existiert eine deutlicher Tagesgang von Ep. Die globale Morphologie der Schwerewellenaktivität zeigt hohe Werte nicht nur am Äquator, sondern auch in mittleren Breiten, dies aber nicht während der Äquinoktien. Dies weist darauf hin, dass Schwerewelleaktivität nicht nur orographisch angetrieben ist, sondern in verschiedenen Breiten vom Jahresgang abhängt. Die Breiten- und Höhenabhängigkeit der Schwerewellenaktivität zeigt zwischen 25 und 30 km niedrige, unterhalb von 25 km hohe Werte von Ep am Äquator. Während des Winters in der Südhemisphäre sind die Werte hoch, während zu den Äquinoktien hohe Werte in mittleren Breiten beider Hemisphären zu finden sind. Während der Solstitien zeigt die Ep-Verteilung stärkere hemisphärische Asymmetrie. Hohe Werte von Ep werden während des südpolaren Frühjahrs gemessen. Der äquatoriale Bereich hoher Varianz ist in allen Jahreszeiten außer im Winter breit (±300°).

Los estilos APA, Harvard, Vancouver, ISO, etc.

23

Rawat, Rashmi. "Geomagnetic storm phenomenon as inferred from the low-latitude geomagnetic field variations and interplanetary parameters". Thesis, Indian Institute of Geomagnetism, Mumbai, 2008. http://localhost:8080/xmlui/handle/123456789/219.

Texto completo

Resumen

A thesis submitted to the University of Mumbai for the Ph.D. in Physics, under the guidance of Prof. Shobhana Alex.
Part of Conclusion : The thesis compiles the extensive analysis work done with large data set from low latitude geomagnetic observatories Alibag (Geog. Lat. 18.63◦N, long. 72.87◦E; Ge omag. Lat. 10.03◦N, Long. 145.97) and Tirunelvelli (Geog. Lat. 8.42◦N, long. 77.48◦E; Geomag. Lat. 0.57◦S, Long. 149.42) along with solar wind and interplane tary parameters, covering the solar cycle-23. Investigations are carried out on diverse modulations exhibited by the meridional (Bz) and zonal (By) components of the in terplanetary magnetic field (IMF) and their significant guiding roles for producing different patterns of geomagnetic field variations and good results are obtained. As sociation of dawn-dusk electric field responsible for magnetospheric convection with low-latitude H and D components of geomagnetic field is examined. From the data set, we have identified various types of storms, which include: Initial phase storms, Sharp and intense main phase storms, Two-step main phase storms, Double-dip (DD) storms and magnetic cloud driven storms. Currently, the differen tiation is primarily explained on the basis of meridional (Bz) and zonal (By) compo nents of IMF and total energy influx into the magnetosphere. However, many more parameters need to be looked into for their distinct contribution for producing varied geomagnetic storm patterns. A study topic to be dealt in is the investigation of the long term variability of solar wind velocity (Vsw) and intensity of interplanetary magnetic field (|B|). The corre spondence between the long term variability of Vsw and |B| and the geomagnetic storm events may also be attempted. My present dissertation deals with solar cycle 23, the work may be extended for more solar cycles for examining the long term variability of certain parameters. The product of Bz and square of solar wind speed (Vsw) correlates well with activity on time scales between hours and years. In order to determine the crossover point where the southward component of the IMF and the square of the solar wind speed correlate equally well with geomagnetic activity, a possible way would be to compare appropriately normalized power spectra of each parameter based on the span of data over the entire solar cycle. At high frequencies (periods of the order of hours) the power is expected to be greater in Bz fluctuations than in Vsw 2 fluctuations; at low frequencies (periods of the order of days) the reverse is expected. Although long term spectra of Vsw 2 and Bz are not available, the crossover point could be estimated from spectra based on yearly data spans and their variation throughout the solar cycle. An in-depth analysis will be carried out with respect to the other solar wind plasma parameters like solar wind dynamic pressure, thermal pressure. Quantitative aspects of energy inputs from the contribution of different current systems in the magnetopause, ring current region, magnetotail is to be explored. Determination of occurrence of electrons and different ions during the storm phenomenon will be in teresting to differentiate between phases of storm. Advanced analysis techniques like modelling and simulations are to be used for understanding finer aspects involved in the storm dynamics. Comprehensive work with larger data set will certainly provide better understanding of the complex coupling between the solar wind-magnetosphere and ionosphere.

Los estilos APA, Harvard, Vancouver, ISO, etc.

24

Alapini, Odunlade Aude Ekundayo Pauline. "Transiting exoplanets : characterisation in the presence of stellar activity". Thesis, University of Exeter, 2010. http://hdl.handle.net/10036/104834.

Texto completo

Resumen

The combined observations of a planet’s transits and the radial velocity variations of its host star allow the determination of the planet’s orbital parameters, and most inter- estingly of its radius and mass, and hence its mean density. Observed densities provide important constraints to planet structure and evolution models. The uncertainties on the parameters of large exoplanets mainly arise from those on stellar masses and radii. For small exoplanets, the treatment of stellar variability limits the accuracy on the de- rived parameters. The goal of this PhD thesis was to reduce these sources of uncertainty by developing new techniques for stellar variability filtering and for the determination of stellar temperatures, and by robustly fitting the transits taking into account external constraints on the planet’s host star. To this end, I developed the Iterative Reconstruction Filter (IRF), a new post-detection stellar variability filter. By exploiting the prior knowledge of the planet’s orbital period, it simultaneously estimates the transit signal and the stellar variability signal, using a com- bination of moving average and median filters. The IRF was tested on simulated CoRoT light curves, where it significantly improved the estimate of the transit signal, particu- lary in the case of light curves with strong stellar variability. It was then applied to the light curves of the first seven planets discovered by CoRoT, a space mission designed to search for planetary transits, to obtain refined estimates of their parameters. As the IRF preserves all signal at the planet’s orbital period, t can also be used to search for secondary eclipses and orbital phase variations for the most promising cases. This en- abled the detection of the secondary eclipses of CoRoT-1b and CoRoT-2b in the white (300–1000 nm) CoRoT bandpass, as well as a marginal detection of CoRoT-1b’s orbital phase variations. The wide optical bandpass of CoRoT limits the distinction between thermal emission and reflected light contributions to the secondary eclipse. I developed a method to derive precise stellar relative temperatures using equiv- alent width ratios and applied it to the host stars of the first eight CoRoT planets. For stars with temperature within the calibrated range, the derived temperatures are con- sistent with the literature, but have smaller formal uncertainties. I then used a Markov Chain Monte Carlo technique to explore the correlations between planet parameters derived from transits, and the impact of external constraints (e.g. the spectroscopically derived stellar temperature, which is linked to the stellar density). Globally, this PhD thesis highlights, and in part addresses, the complexity of perform- ing detailed characterisation of transit light curves. Many low amplitude effects must be taken into account: residual stellar activity and systematics, stellar limb darkening, and the interplay of all available constraints on transit fitting. Several promising areas for further improvements and applications were identified. Current and future high precision photometry missions will discover increasing numbers of small planets around relatively active stars, and the IRF is expected to be useful in characterising them.

Los estilos APA, Harvard, Vancouver, ISO, etc.

25

Costa, Ana Sofia Vicente. "Seasonal variations in the effect of structural complexity of olive productions systems on bat activity: implications for natural pest control services". Master's thesis, Universidade de Évora, 2018. http://hdl.handle.net/10174/24445.

Texto completo

Resumen

Agricultural landscapes have suffered drastic changes as a consequence of management intensification, leading to a decline in biodiversity, specially in Mediterranean olive farms. Among others, homogenization affects the activity levels of bats, an important component of agricultural ecosystems by acting as biocontrol agents against olive pests. To understand how seasonal variations affects bat occurrence and the biocontrol services they provide, we sampled olive groves with different structural complexities over three seasons, coinciding with the peak activity of Prays oleae, one of the major pests of olive production systems. We found strong differences in the response of bats to the structural complexity of olive production systems, being these species-specific and strongly season-dependent. Thus, our results suggest that habitat heterogeneity is of great importance for bat activity, implying that structurally-complex agricultural landscapes could promote higher natural pest control services provided by bats; Variações sazonais no efeito da complexidade estrutural em olivais com diferentes sistemas de produção na atividade de morcegos: implicações para os serviços de controlo natural de pragas Resumo: As paisagens agrícolas sofreram drásticas mudanças por consequência da intensificação da gestão, levando ao declínio da biodiversidade, especialmente em olivais mediterrânicos. Entre outros, a homogeneização afeta os níveis de atividade dos morcegos, os quais apresentam elevada importância nos ecossistemas agrícolas pela sua capacidade de controlo natural de pragas. Para compreender como as variações sazonais afetam a ocorrência destes nos olivais, amostrámos olivais com diferentes complexidades estruturais em três estações, coincidindo com o pico de atividade de Prays oleae, uma das principais pragas dos olivais, para investigar se morcegos poderão atuar no seu controlo. Foram encontradas diferenças nas respostas dos morcegos em relação à complexidade estrutural dos olivais, sendo estas dependentes de cada espécie e da estação. Assim, os resultados sugerem que a heterogeneidade do habitat apresenta grande importância na atividade dos morcegos, implicando que paisagens agrícolas estruturalmente complexas poderão promover serviços de controlo natural de pragas fornecidos pelos morcegos.

Los estilos APA, Harvard, Vancouver, ISO, etc.

26

Beraud, Hélène. "Initier la résilience du service de gestion des déchets aux catastrophes naturelles : le cas des territoires urbains et de l'inondation". Thesis, Paris Est, 2013. http://www.theses.fr/2013PEST1046/document.

Texto completo

Resumen

Les stratégies d'amélioration de la résilience des territoires à risque ont pris une place prépondérante dans les politiques de gestion des inondations. Raisonner en terme de résilience, c'est-à-dire de capacité pour un système à se maintenir et à retrouver un fonctionnement acceptable après la catastrophe, permet de penser différemment et d'anticiper la longue période qui suit un événement catastrophique. Le rôle du service de gestion des déchets dans la résilience des territoires urbains a été peu étudié. Or, lors d'une inondation, l'eau dégrade tout ce qu'elle touche, générant par là même des déchets en quantité très importante. Infrastructures bloquées, réintégration dans les habitations et les entreprises retardée, atteintes à la santé et à l'environnement, impacts psychologiques sont autant d'exemples des conséquences de la présence de ces amas de déchets sur le territoire. Loin d'être anecdotique, la gestion de ces déchets est donc un enjeu de la post inondation. Le maintien d'un service de gestion des déchets est donc stratégique pour la résilience des territoires face aux catastrophes. Il est donc nécessaire de travailler à sa résilience. Pour cela, cette thèse propose une démarche permettant de diagnostiquer la résilience d'un service de gestion des déchets qui se base sur trois leviers d'actions :1) analyse de la capacité du service à connaître les sollicitations du système urbain en matière de gestion des déchets qui s'appuie sur la construction d'une méthode d'estimation et de caractérisation du gisement potentiel de déchets post inondation ; 2) analyse de la capacité du service à maintenir un fonctionnement acceptable pour le système urbain qui s'appuie sur l'utilisation de méthodes de diagnostic de la vulnérabilité et d'analyse de la sûreté de fonctionnement ; 3) analyse de la capacité du service à solliciter un territoire plus vaste pour parer à ses défaillances. Cette démarche de diagnostic a été mise en pratique sur un territoire d'étude
Improving the resilience of urban areas against flooding is one of the main principles for flood prevention. Thinking in terms of resilience, i.e. enabling for the system to maintain or recover acceptable operating levels after disaster, allows to think differently and to anticipate post disaster period. The role of waste management system in resilience of urban territories has been little studied. However, during flooding, water degrades everything it touches, thereby producing very important quantities of waste. Blocked infrastructures, attacks on health and environment, psychological impacts, and deterioration in the area's image are the impacts made by poor management of this new waste. Therefore, adapting waste management system and anticipating flooding contributes to improving urban areas' resilience. That's why, this thesis suggests an approach allowing to assess resilience of waste management system. This approach proposes three steps : 1) study of capacity of waste management system to know waste management needs of the urban system. For this, a method allowing to quantify and to describe the waste that could be generated by flood was developed ; 2) study of capacity of waste management system to maintain an acceptable operating level compared with the urban system solicitations. For this, vulnerability assessment methods and reliability assessment methods were applied ; 3) study of capacity of waste management system to mobilize others waste management infrastructures in the larger scale, if it is unable to adapt itself to perturbation. This approach was applied to a concrete case

Los estilos APA, Harvard, Vancouver, ISO, etc.

27

Kong, Heng. "Variations spatio-temporelles de la structure taxonomique et la compétition alimentaire des poissons du lac Tonlé Sap, Cambodge". Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30122/document.

Texto completo

Resumen

Le lac de Tonlé Sap (TSL), Cambodge, est un écosystème lac-rivière de forêt alluviale au régime d'écoulement alternatif. Le lac est un déversoir lors de l'inondation saisonnière du Mékong et sert de réservoir en période de basses eaux. La superficie du lac pendant la saison sèche (février à mai), est d'environ 2 700 km2 pour une profondeur d'environ 1 mètre. Cette superficie est pratiquement multipliée par six quand arrive la saison des pluies, pour atteindre près de 16 000 km2 et une profondeur de 9 mètres, noyant rizières et forêts. C'est le plus grand lac d'eau douce d'Asie du Sud-Est. C'est aussi l'une des zones de pêche d'eau douce les plus importantes et productives du monde avec près de 75% du volume annuel de pêche en eau douce du Cambodge, ce qui permet la survie de près de 2,5 millions de personnes. Les changements saisonniers du cycle hydrologique ont une influence sur la structuration des communautés de poissons à l'échelle temporelle et spatiale, mais aussi sur les comportements trophiques des principales espèces qui n'exploitent alors pas les mêmes habitats. Toutefois, le bassin versant du Mékong est en changement constant avec un développement important des infrastructures en lien avec l'eau : production d'hydro-électricité, besoins important en irrigation, maitrise des inondations, eau potable, ... Les changements climatiques accélèrent les modifications du cycle hydrologique annuel. Il est alors supposé que ces modifications ont des effets forts sur les habitats et les proies disponibles et finalement sur la biodiversité, notamment de l'ichtyofaune et sur l'abondance des poissons disponibles pour les pêcheries.Dans un premier temps, nous avons caractérisé les variations spatio-temporelles de la composition taxonomique des poissons et mis en lumière quels sont les déterminants de ces variations. À cette fin, nous avons estimé la diversité bêta comme la variance totale de la matrice site par communauté d'espèce et l'avons divisée en contribution locale à la diversité bêta (LCBD) et contribution des espèces à la diversité bêta (SCBD). Nous avons ensuite effectué plusieurs régressions linéaires pour déterminer si la richesse taxonomique, l'abondance des espèces et le niveau de l'eau expliquaient la variation temporelle de la contribution du site et de l'espèce à la diversité bêta. Nos résultats indiquent une forte variation temporelle de la diversité bêta due aux contributions différentielles des sites et des espèces à la variation spatiale de la composition taxonomique des poissons. Nous avons également constaté que la direction, la forme et l'effet relatif de la richesse spécifique, de l'abondance et du niveau de l'eau sur la variation temporelle des valeurs LCBD et SCBD varient grandement selon les sites. Ces résultats suggèrent ainsi une variation spatiale des processus conduisant à une variation temporelle de la composition de la communauté. Dans l'ensemble, nos résultats suggèrent que la composition taxonomique des poissons n'est pas distribuée de manière homogène dans l'espace et dans le temps et risque d'être affectée à l'avenir si la dynamique saisonnière d'écoulement du système est altérée par les activités humaines et/ou les changements climatiques. Dans un second temps, nous avons cherché à étudier le modèle d'évolution temporel des principales espèces en terme d'occurrence et d'abondance à travers le cycle saisonnier hydrologique
The Tonle Sap Lake (TSL), Cambodia, is a flood-pulse system. It is the largest natural lake in South- East Asia and constitutes one of the largest fisheries over the world, supporting the livelihood 2.5 million peoples. Seasonal change in annual hydrological cycle appears to have influence on fish community structure, both spatial and temporal variation, particularly on feeding behavior of TSL's fishes. Nonetheless, the Mekong River Basin is changing rapidly due to accelerating water infrastructure development (hydropower, irrigation, flood control, and water supply) and climate change, bringing considerable modifications to the annual flood-pulse of the TSL. Such modifications are expected to have strong impacts on fish biodiversity, abundance, reduced habitat and food availability within the lake. To invest how TSL's fish community structure responds to the seasonal change, how they shift their diet across hydrological cycles and feeding competing for food resource: First, we aim to characterize the spatio-temporal variations of fish taxonomic composition and to highlights the underlying determinants of these variations. For this purpose, we estimated beta diversity as the total variance of the site-by-species community matrix and partitioned it into Local Contribution to Beta Diversity (LCBD) and Species Contribution to Beta Diversity (SCBD). We then performed multiple linear regressions to determine whether species richness, species abundances and water level explained the temporal variation in the contribution of site and species to beta diversity. Our results indicate strong temporal variation of beta diversity due to differential contributions of sites and species to the spatial variation of fish taxonomic composition. We further found that the direction, the shape and the relative effect of species richness, abundances and water level on temporal variation in LCBD and SCBD values greatly varied among sites, thus suggesting spatial variation in the processes leading to temporal variation in community composition. Overall, our results suggest that fish taxonomic composition is not homogeneously distributed over space and time and is likely to be impacted in the future if the flood-pulse dynamic of the system is altered by human activities. Second, we aim to investigate the temporal pattern of the most occurrence and abundance species and how their co-occurrence pattern across hydrological cycles. We found that occurrence and abundance patterns were temporally varied at all water level seasons. Strong temporal variation in species occurrence was occurred with visiting species such as Labiobarbus leptocheilus and Poropuntius deauratus while water level starts to fill into the TSL. We further observed that the abundance of 17 species was strongly varied while other 22 species (mainly TSL's residential species) were stable within the year. Positive species co-occurrence pattern was generally higher than negative species co-occurrence at all water level seasons. Highest positive co-occurrence patterns were found during the period of decrease and low water level seasons while fishes are migrating from flooded areas, competing for resource and habitats during low water season. Study on temporal distribution and species co-occurrence of fish and how community responds to the seasonal change in hydrological cycles provides critical information for fisheries management and conservation in the Tonle Sap Lake (TSL) as well as maintaining fish biodiversity in the Mekong system. Third, the implications of seasonality on food web structure have been notoriously understudied in empirical ecology, particularly in TSL's system. The current study, we focus on seasonal changes in one key attribute of a food web, vertical trophic position of consumers

Los estilos APA, Harvard, Vancouver, ISO, etc.

28

Santoso, Sugeng. "EXPERIMENTAL STUDIES ON THE DENSITY-DEPENDENT VARIATIONS IN BODY COLOR AND DISPERSAL ACTIVITY OF THE THREE RICE LEAFHOPPERS, NEPHOTETTIX CINCTICEPS, N.NIGROPICTUS AND N.VIRESCENS (HOMOPTERA : CICADELLIDAE)". Kyoto University, 1999. http://hdl.handle.net/2433/181396.

Texto completo

Resumen

Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第8033号
農博第1083号
新制||農||790(附属図書館)
学位論文||H11||N3328(農学部図書室)
UT51-99-T744
京都大学大学院農学研究科応用生物科学専攻
(主査)教授久野英二, 教授西岡孝明, 教授高藤晃雄
学位規則第4条第1項該当

Los estilos APA, Harvard, Vancouver, ISO, etc.

29

Ulaganathan, Sekar. "The influence of light exposure and seasonal changes on short-term and longer-term changes in axial length of the human eye". Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/115840/1/Sekar_Ulaganathan_Thesis.pdf.

Texto completo

Resumen

Myopia (short-sightedness) is a common eye condition that is increasing in prevalence in the population. This research involved a longitudinal study examining the potential role of outdoor light exposure (and its seasonal variations) in the increased eye growth underlying myopia in young adults. Individuals spending less time in bright outdoor light were found to exhibit higher magnitude short-term daily fluctuations in eye length, as well as more rapid eye growth over 12-months. Seasonal variations in light exposure also appeared to impact upon eye growth. This research supports an important role for outdoor light exposure in myopia development in young adults.

Los estilos APA, Harvard, Vancouver, ISO, etc.

30

Mendella, Paul David Carleton University Dissertation Psychology. "Intraventricular administration of [D-Pen2,D-Pen5]-Enkephalin in the CD-1 mouse; variations of activity, exploration and intracranial self-stimulation from the Dorsal A10 region following uncontrollable footshock". Ottawa, 1994.

Buscar texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

31

Courtiol, Emmanuelle. "L’inextricable relation olfaction-respiration chez le rat : études de l’impact des variations de flairages sur l’activité du bulbe olfactif et sur la discrimination des odeurs". Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10309/document.

Texto completo

Resumen

Chez les mamifères terrestres, l’échantillonnage des odeurs (flairage) est inextricablement lié à la respiration. Le flairage contraint à la fois le décours temporel et l’intensité de l’input olfactif. Or le flaireage est un acte dynamique, il peut varier aussi bien en fréquence qu’en débit. Dans une 1ère partie de mon travail de thèse, nous avoins souhaité caractériser l’impact des variations de fréquence et de débit respiratiore sur l’activité du bulbe olfactif. Pour cela, nous avons mis au point une méthode de double trachéotomie chez le rat anesthésié nous permettant de contrôler précisément les flux d’air ans la cavité nasale. En paralèlle, nous avons enregistrer l’acitivité unitaire et de réseau du bulbe olfactif. Nous montrons que les variations de flairage modulent la représentation neuronale bulbaire des odeurs en modifiant à la fois l’activité de décharge des cellules principales et l’occurence des oscillaations du potentiel de champ local. Dans une 2e partie de ma thèse, nous avons souhaitécomprendre quel pouvait être le rôle du flairage chez un animal qui se comporte. Nous avons posé l’hypothèse qu’un animal pouvait adapter sa façon de flaireer en fonction de la qualité des molécules odorantes. Pour tester cette hypothèse, nous avons mis au point un système d’enregeistrement non invasif de la respiration couplé à une tâche de discrimination olfactive chez le rat. Nous montrons non seulement que les animaux peuvent adapter leur flairage en fonction des molécules odorantes masi également en focntion du contexte dans lequel l’odeur est présentée. L’ensemble de ces résultats s’intègre donc dans la problématique plus générale de l’intégration sensori-motrice
In terrestrial mammals, an inextricable link between olfaction and respiration exists due to the periodic sampling of odorant molecules by inhalation. The features of sniffing (or breathing) constrain both the timing and the intensity of the input to the olfactory structures. But rather than being fixed, sniffing in the bahavingrodent is highly dynamic and varies both in frequency and flow rate. During the firs stage of my PhD, I asked to what extent sniffing parameters (frequency and flow rate) variations could affect the olfactory bulb activity. To address this question, I developped a double tracheotomy protocol in anesthetized rats to precisely control and modify the nasal airflow. In parallel, I recorded oldfactory bulbactivities, single-unit activity and local field potentials. We showed that, at the olfactory bulb level, the neutral representation of an odor is highly modified by sampling variations. In fact both the mitral/tufted cell discharge patterns and local field potentials oscilliations were affected by sniffing variations. In the second stage, we wanted to understand the role of sniffing variations in behaving animals. We hypothesized tha t an animal could adapt its sniffing strategy relative to the quality of the odorant molecules. To test this hypothesis, we developped a tool to record sniffing in a non invasive way, and combined it to an olfactory discrimination task in the rat. We showed that animals not only adapted their sniffing relative to the odorant quality but also to the odorant context. Taken together, these results fit into the broader context of sensory-motor integration

Los estilos APA, Harvard, Vancouver, ISO, etc.

32

Stahl, Clément. "Variations saisonnières des flux de CO2 et H2O au niveau des feuilles et des troncs des arbres de la canopée en forêt tropicale humide guyanaise". Thesis, Nancy 1, 2010. http://www.theses.fr/2010NAN10049/document.

Texto completo

Resumen

L’objectif de ce travail était de caractériser la variabilité saisonnière des échanges gazeux des arbres de la canopée en forêt tropicale humide guyanaise confrontés à des saisons sèches.L’étude s’est orientée sur la mesure des flux de carbone et d’eau au cours des saisons sèches dans deux habitats contrastés du point de vue hydrique, afin de préciser leur sensibilité et réponse à la sècheresse. Nos résultats montrent qu’une proportion non négligeable d’arbres ne subit pas de sécheresse marquée en saison sèche, malgré la forte diminution de la teneur en eau du sol en surface. Nous faisons l’hypothèse que ces arbres possèdent alors des racines en profondeur qui leur permettent d’accéder aux horizons qui restent humides malgré la faible pluviométrie. Durant les longues saisons sèches, nous observons une diminution de l’assimilation nette de CO2 foliaire, de l’efflux de CO2 des troncs ou de la densité de flux de sève, et dans une moindre mesure de la respiration foliaire. Cette diminution concerne un nombre plus important d’arbres, quand l’intensité de la sécheresse est plus forte (2008 par rapport à 2007). Néanmoins, de grandes différences de réponse à la sècheresse du sol ont été observées, suggérant des sensibilités et des mécanismes de réponse différents entre ces arbres. En habitat de bas-fond, nous montrons une plus faible diminution des flux carbonés et hydriques en saison sèche, suggérant un accès pour ces arbres aux horizons humides, proches de la nappe phréatique. Par ailleurs, nos résultats suggèrent pour certains arbres un effet négatif des conditions d’anoxie sur ces flux en saison des pluies.Si l’accentuation de l’intensité des saisons sèches en forêt tropicale humide Amazonienne se confirme, comme suggérée par les modèles climatiques, ce travail suggère des modifications rapides de la composition spécifique des forêts, au profit des espèces plus résistantes aux contraintes hydriques
The aim of this work was to characterize the seasonal variations in leaf and trunk gas exchange of tropical rainforest canopy trees exposed to dry seasons. This study focused on measuring gas exchange (CO2 and H2O) at the leaf and trunk level during dry seasons in a Terra firme forest and in a seasonally flooded forest in order to specify their sensitivity and response to drought.Our results showed that part of the studied trees do not encounter a large reduction in soil water content during dry seasons, suggesting that they display deep rooting systems.During long dry periods, we recorded a decrease in leaf photosynthesis, trunk CO2 efflux or sap flow density, and foliar respiration to a lesser extent, for a majority of the trees. Nevertheless, large differences among trees in their response to these conditions were observed, suggesting distinct sensitivities and response to soil drought among trees. Furthermore, these variations were greatest when soil drought was highest (2008 as compared to 2007).In seasonally flooded forest, the decrease in gas exchange was less, suggesting that these trees do have access to wet layers during the dry season, close to the groundwater. However, during wet seasons, we observed a negative effect of anoxia for some trees, whereas others did not display any response, suggesting large differences in tolerance to anoxia among trees abundant in these seasonally flooded forests.We conclude that would seasonal soil droughts increase over the next decades, large vegetation changes might occur because of the large differences among trees in their functional response to soil drought conditions

Los estilos APA, Harvard, Vancouver, ISO, etc.

33

Bovalo, Christophe. "Activité électrique et variations d’intensité des systèmes convectifs tropicaux dans le sud-ouest de l’océan Indien : observations et modélisation". Thesis, La Réunion, 2013. http://www.theses.fr/2013LARE0001/document.

Texto completo

Resumen

Depuis une vingtaine d'années, la qualité de la prévision de la trajectoire des cyclones tropicaux a fortement progressé mais peu d'améliorations ont été apportées à la prévision de l'intensité. Cette thèse s'intéresse aux changements d'intensité des cyclones tropicaux du sud-ouest de l'océan Indien sous l'angle original de l'activité électrique.Une première étude climatologique s'appuyant sur les données du réseau de détection d'éclairs World Wide Lightning Location Network (WWLLN) a permis de valider la qualité de ces données et de montrer que les cyclones tropicaux pouvaient être une source importante de production d'éclairs à l'échelle du bassin. À partir de ce résultat, une étude ciblée a été menée en considérant la spécificité du bassin et trois régions ont été définis (océan ouvert, région à proximité de la côte est de Madagascar et Canal du Mozambique). L'activité électrique des cyclones tropicaux dépend de la région où ils se trouvent ainsi que de leur stade d'intensité. Les éclairs semblent être un marqueur des phases d'intensification et d'affaiblissement dans certains situations. La troisième étape de cette thèse a consisté à simuler de manière idéalisée un cyclone tropical mature et a tenté d'expliquer les processus physiques à l'origine de l'activité électrique. Le modèle reproduit bien le comportement sporadique des éclairs habituellement observé. Des bilans montrent que ce cyclone présente trois phases caractéristiques, chacune associée à un comportement dynamique, microphysique et électrique différent. Enfin, une deuxième étude purement numérique a tenté d'identifier des estimateurs de l'activité électrique. Pourcelà deux approches ont été adoptées : une étude globale et une étude par cellule. Dans les deux cas, les meilleurs estimateurs sont la masse totale de graupel, le volume d'updraft et le produit des flux des masses de glace précipitante et non précipitante
Tropical cyclone track forecast has improved over the past two decades but little improvement have been done in intensity changes forecast. This thesis focuses on the intensity changes of tropical cyclones in the southwest Indian ocean through the original aspect of lightning activity. A climatology of lightning activity in the southwest Indian ocean using data from the World Wide Lightning Location Network (WWLLN) is first proposed. Results showed that the WWLLN was able to locate and capture the lightning activity in the basin and that tropical cyclones can be considered as a major source of lightning flashes in some oceanic parts of this region. From this result, study of lightning activity in tropical cyclones of the southwest Indian ocean has been done considering the basin configuration. Thus, three regions were defined: open ocean, region near the eastern coast of Madagascar and the Mozambique Channel. The location and intensity of lightning activity depend on the region and the intensity stage. Lightning flashes seem to be a proxy of intensification or weakening under some conditions. The third step of this thesis was to simulate in an idealized framework a mature tropical cyclone. The model was first able to reproduce the sporadic behavior of lightning activity as observed. Budgets have shown that the presence of three distinctive phases characterized by different dynamical, microphysical and electrical behaviors. Finally, another purely numerical work tried to identify some proxies of lightning activity according two approaches : a global analysis anda per-cell analysis. In both cases, the best proxies are the total graupel mass, the updraft volume and the product of precipitating and non-precipitating ice mass fluxes

Los estilos APA, Harvard, Vancouver, ISO, etc.

34

Vigne, Grégory. "Détermination et variation du profil physique du footballeur de très haut niveau : référence spéciale aux performances athlétiques selon les différents postes de jeu orientant sur la validation d’un test d’agilité". Thesis, Lyon 1, 2011. http://www.theses.fr/2011LYO10343/document.

Texto completo

Resumen

Cette thèse s’adresse aussi bien aux scientifiques, aux entraîneurs, aux préparateurs physiques et aux sportifs souhaitant approfondir leurs connaissances de l’activité football. Les aspects scientifiques abordés ainsi que leur transposition en outils de terrain pourront être utilisés comme moyen d’évaluation et d’orientation des séances d’entraînement. Ainsi, au travers de ce travail, nous avons abordé le ratio entre le temps de travail et le temps de récupération réalisés en matches de très haut niveau dans le Championnat de Première Division Italienne au cours de la saison 2004/2005. Ce ratio moyen de compétition est de 1/8, à savoir 2.2 secondes d’effort et 18 secondes de récupération. La deuxième partie de ce travail consistait à analyser l’évolution du profil d’effort et la possession de balle collective de footballeurs de très haut niveau au cours de trois saisons consécutives avec un effectif et un staff technique stables. L’étude a permis de mettre en avant une diminution de la quantité d’effort produite par les joueurs de l’ordre de 5% sans altération de la performance ainsi que l’augmentation de la possession de balle collective. La troisième et dernière partie a été de créer et d’analyser un test d’agilité spécifique à l’activité football. Après, une analyse complète des différents éléments liés à la reproductibilité et à la validité du test, il s’avère que ce test semble rendre compte de l’activité motrice du footballeur. De plus, les mesures réalisées dans le cadre de ce travail ont permis de fournir les premières normes de performance qui peuvent être attendues en fonction de l’âge du joueur et de son niveau de jeu. Au terme de notre travail, nous pouvons conclure que cette thèse a apporté des résultats spécifiques pour orienter l’entraînement athlétique du footballeur moderne et à proposer un nouvel outil de détection des jeunes footballeurs
This work is dedicated to scientists, coaches and physical trainers as well as athletes involved in elite soccer activity. The scientific results and their practical applications could be used as a basis for the work of scientists as well as football professionals. The first part of this thesis showed that playing positions significantly influence activity profile. Moreover, this study demonstrated that the work/rest ratio observed in elite soccer Italian Serie A championship attained 1/8 and represented a mean work time of 2.2 seconds for an averaged recovery time of 18 seconds. The second part of this thesis, explored the evolution of activity profile and total ball possession during 3 consecutive seasons in the same elite team. This study has showed how for three consecutive seasons the players of successful Serie-A team reduced their distances performed at submaximal speeds, and increased ball possession while maintaining the distances covered at high/maximal speeds. It is suggested that this is due to a better understanding of tactical roles and team organization. The third part of the thesis tended to develop and to valid a specific agility soccer test composed with fundamental soccer tasks which has to be performed as quickly as possible. The validity and repeatability of the test has been demonstrated and it has been applied on a large population of different ages, positions and levels. As a conclusion, this thesis provided new specific results and perspectives that would influence professional soccer athletic conditioning and that provided a new specific test to detect young soccer players

Los estilos APA, Harvard, Vancouver, ISO, etc.

35

Benslimane, Saloua. "Variations de l'activité de la plasmine et du plasminogène dans les laits de vache Montbéliarde et dans les fromages de type Comté". Besançon, 1986. http://www.theses.fr/1986BESA2001.

Texto completo

Resumen

La plasmine, protéase native endogène, existe dans le lait de vache avec son zymogène inactif : le plasminogène. Dans les laits de vaches montbéliarde, l'activité de la plasmine et du plasminogène varie essentiellement en fonction des saisons et des stades de lactation : cette activité est minimale a l'automne et maximale en été ; elle est faible en début de lactation et élevée en fin de lactation. Dans les fromages de type comte, l'activité diminue progressivement au cours de la fabrication en été et en hiver. La protéolyse induite par la plasmine dans les laits est plus importante l'été que l'hiver. Dans les fromages, la dégradation de la caséine-béta est plus importante l'été que l'hiver aux premiers stades de la fabrication ; a la coupe elle est identique en été et en hiver. La présence de lainure dans les fromages suit la même évolution que l'activité de la plasmine et du plasminogène : maximum en été et minimum en hiver ; la plasmine pourrait jouer un rôle dans l'apparition de ce défaut

Los estilos APA, Harvard, Vancouver, ISO, etc.

36

Michelot, Candice. "Le manchot Adélie, sentinelle de la glace de mer : étude du comportement de recherche alimentaire en réponse aux variations environnementales en période de reproduction". Thesis, La Rochelle, 2020. http://www.theses.fr/2020LAROS009.

Texto completo

Resumen

Une question centrale en écologie est la compréhension des effets des changements environnementaux sur les organismes et sur le fonctionnement des écosystèmes. L’Arctique et l’Antarctique se réchauffent plus rapidement que n’importe quelle autre région sur la planète, ce qui a des conséquences sur l’état de la glace de mer et par extension sur les espèces polaires qui en dépendent pour leur activité d’alimentation et de reproduction. L’objectif principal de cette thèse est de déterminer les réponses comportementales d’une espèce bio-indicatrice, le manchot Adélie, lors de son activité de recherche alimentaire face à des conditions de glace de mer variables, à différentes échelles de l’espèce : individuelle, populationnelle, inter-populationnelle. Nous nous basons sur un jeu de données d’activité d’alimentation (GPS, régime alimentaire) des manchots Adélie collectées chaque année depuis 2010 en Terre Adélie (Antarctique de l’Est), à chaque saison de reproduction dans plusieurs colonies. Nous avons mis en évidence des variations dans le comportement alimentaire de cette espèce en fonction des conditions et de la dynamique de la glace de mer, mais des réponses similaires entre individus et entre colonies faisant face à des conditions environnementales comparables. Nos résultats soulignent l’importance de certains habitats et de certaines conditions de glace pour une activité alimentaire optimale. Nous discutons des facteurs intrinsèques et extrinsèques à l’origine des variations observées, et de l’implication de telles variations sur le comportement reproducteur des manchots Adélie. Les résultats de cette thèse sont replacés dans un contexte de conservation des écosystèmes par la mise en place de mesures de protection efficaces basées sur l’écologie d’espèces sentinelles
A central question in ecology is the understanding of the environmental change effects on organisms and on the ecosystem functioning. The Arctic and Antarctic warm faster than any other region on Earth, which has consequences on the sea-ice state and by extent on polar species which depend on it for their breeding and feeding activities. The main objective of my PhD was to determine the behavioural responses of a bio-indicator species, the Adélie penguin, during its foraging activity facing variable sea-ice conditions, at different species levels : individual, population, inter-population. We use a foraging activity dataset (GPS data, diet) on Adélie penguins obtained collected each year since 2010 in Terre Adélie (East Antarctica), at each breeding season in several colonies. We highlight foraging behavioural variations in that species related to sea-ice conditions and dynamics, but similar responses between individuals and between colonies facing comparable environmental conditions. Our results highlight the importance of specific habitats and sea-ice conditions for an optimal foraging activity. We discuss about intrinsic and extrinsic factors at the origin of the observed variations, and of the implication of such variations on the reproductive behaviour of Adélie penguins. Those PhD results are replaced in a context of ecosystem conservation for the implementation of efficient protection measures based on the ecology of sentinel species

Los estilos APA, Harvard, Vancouver, ISO, etc.

37

Alzubik, Belkair Sadeq. "Lutte biologique par conversation dans les vergers de pommiers : peut-on manipuler les communautés d'araignées pour augmenter leur efficacité contre certains ravageurs". Thesis, Avignon, 2018. http://www.theses.fr/2018AVIG0348/document.

Texto completo

Resumen

Dans le contexte des plans Ecophyto, il est primordial de trouver des alternatives aux traitements phytosanitaires. La lutte biologique par conservation fait partie de ces alternatives et, dans ce cadre, nous nous sommes intéressés à déterminer les rôles possibles des araignées en tant que prédateurs généralistes dans les vergers de pommiers. Pour cela, trois axes de travail ont été définis : (i) d’abord étudier les facteurs locaux (protection phytosanitaire et environnement des vergers) expliquant l’abondance et la diversité des communautés d’araignées; (ii) ensuite déterminer si les araignées sont actives en hiver dans les vergers dans le but d’estimer leur rôle sur les stades hivernants de ravageurs; (iii) et enfin étudier la faisabilité et l’efficacité d’un lâcher d’araignées contre le carpocapse des pommes. Dans le premier axe, nous avons mis en évidence des effets significatifs (abondance, diversité, composition) entre les communautés d’araignées issues des vergers en AB et celles issues des vergers PFI, par contre les effets de l’environnement proche des vergers (haies et parcelles alentour) ne semblent pas prépondérants. Dans le second axe, nous avons démontré que dans les vergers du Sud-est de la France, on trouve des araignées actives même au cœur de l’hiver, les plus abondantes furent les Philodromus sp, les Trachelas sp. et les Clubiona sp. Enfin dans le dernier axe, nous avons montré qu’il était possible de transférer et lâcher des araignées d’intérêt (C. mildei et C. leucapsis) et que l’abondance du carpocapse diminuait quand celle de C. mildei augmentait à l’échelle de l’arbre, au moins la première année après le lâcher. L’ensemble de ces résultats permet de poser les bases d’une gestion active des communautés d’araignée en vue d’augmenter leur contribution à la lutte biologique en verger
It is now crucial to develop new control tools to replace the use of pesticides. Biological control is one of this tool and we thus studied the possible roles of spiders as generalist predators in apple orchards. Three studies were carried out: the first one to determine which local factors (protection management and characteristics of the surroundings) govern spider communities (abundance, diversity) in apple orchards; the second to determine which spiders remain active in winter to control resting stages of some pests; and the last to assess the feasibility of a transfer and release of some spider species into an orchard. We first showed that organic and IPM orchards hosted very different spider community and that, in contrast, local characteristics (hedges and percentage of orchards in the vicinity) had only minor effects. We further demonstrated that some spiders were active winter-long in apple orchards in South-east of France with high abundances for some genus like Philodromus, Trachelas and Clubiona. Lastly we showed that transferring and releasing some spider species of interest (C. mildei and C. leucapsis) is possible and greatly increased the abundance of the released species for one year in the target orchard. We moreover observed a significantly negative relationship between C. mildei and codling moth abundance at the tree scale. These results proved that spider populations can be managed to increase their role in the biological control of important pests in pomefruit orchards

Los estilos APA, Harvard, Vancouver, ISO, etc.

38

Heroudek, Jiří. "Řízení nákladů v podniku". Master's thesis, Vysoké učení technické v Brně. Fakulta podnikatelská, 2011. http://www.nusl.cz/ntk/nusl-222907.

Texto completo

Resumen

This Master‘s thesis is focused on cost analyses and cost management in FEI Company. Theoretical part describes basic and advanced cost model and their usage for efficient cost management. Practical part deals with analyses of calculation method for standard costing and life cycle costing. As a part of these analyses, some recommendations are provided to make cost calculations more accurate.

Los estilos APA, Harvard, Vancouver, ISO, etc.

39

Erdelyi, Maria Carolina. "Contribuição à farmacognosia de Annona squamosa L. (Annonaceae) - Acompanhamento da variação sazonal de constituintes, aspectos botânicos e avaliação da atividade antileishmania in vitro". Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/9/9138/tde-14092017-114936/.

Texto completo

Resumen

As doenças tropicais endêmicas representam um grave problema sócio-econômico, no Brasil e no mundo. A leishmaniose insere-se neste quadro. Considerando o surgimento da resistência dos parasitas e a séria toxicidade da terapêutica convencional, a busca de novas alternativas é urgente. A família Annonaceae tem mostrado ser rica fonte de compostos com atividade antiprotozoária. Neste contexto, Annona squamosa L. foi selecionada. Sendo mais conhecida como \"fruta-do-conde\", apresenta uso na medicinal popular, como: antihelmíntica e no combate aos ectoparasitas. Entre os principais metabólitos secundários da espécie, citam-se: alcalóides isoquinolínicos, acetogeninas, flavonóides e óleo volátil. A atividade biológica de A. squamosa tem sido investigada, entretanto, aquela referente à ação antileishmania permaneceu inexplorada, até o presente trabalho, no qual foram avaliadas amostras referentes aos alcalóides totais, ao extrato hidroetanólico, aos infusos e frações orgânicas dos extratos obtidos, a partir de: folhas, pericarpos, sementes e arilos, coletados em quatro fases anuais. Os ensaios in vitro foram realizados frente às formas promastigotas de Leishmania amazonensis, tendo-se realizado, em paralelo, avaliação da citotoxicidade in vitro frente a células epiteliais humanas. Os mesmos extratos foram submetidos ao estudo químico para acompanhamento da variação sazonal qualitativa e quantitativa de classes de componentes e seus marcadores, selecionados por sua ação antileishmania potencial. As análises abrangeram alcalóides, flavonóides, polifenóis totais e taninos, tendo-se empregado as técnicas cromatográficas (CLAE, CCD) e a espectrofotométrica. Em complementação, efetuou-se o estudo morfoanatômico de folha. Os resultados serviram de estímulo para a continuidade do estudo visando ao isolamento de compostos bioativos.
Leishmaniasis, as well as other protozoal tropical endemic diseases, remains a serious Public Health problem all over the world. New altematives for their treatment are urgently needed, since the parasite resistance is increasing and the high toxicity of the conventional medicines reduces its patient adherence. In last decades, several vegetal species from the Annonaceae family showed to be a rich source of potential antiprotozoal metabolites. Therefore, Annona squamosa L. was selected. Although is largely known for its fleshy and flavorous fruits called \"pinhas\" and \"fruta do conde\", some medicinal properties have been attributed to different plant parts including the antihelminthic and against ectoparasites. The main secondary metabolites found in the species were: isoquinoline alkaloids, acetogenins, flavonoids and volatil oil. In this work, the in vitro antileishmanial activity was investigated for the total alkaloid and hidroalcoholic extracts, infuses and organic fractions from leaves, fruits, seeds and arils of A.squamosa collected in the four anuual phases. In vitro tests were also performed to evaluate the cytotoxic activity of extracts. Qualitative or quantitative analyses of alkaloids, total phenolics, total flavonoids and tannins were done by HPLC, spectrophotometric and TLC methods. The morphoanatomical study of leaves was also presented and illustrated by photos and photomicrographies. The results have encouraged deeper researches and further isolation of bioactive compounds.

Los estilos APA, Harvard, Vancouver, ISO, etc.

40

Thomas, Aline. "Identités funéraires, variants biologiques et facteurs chronologiques : une nouvelle perception du contexte culturel et social du Cerny (Bassin parisien, 4700-4300 avant J.-C.)". Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14401/document.

Texto completo

Resumen

Au cours du Ve millénaire avant notre ère, le Bassin parisien voit l’émergence des premières nécropoles et du monumentalisme funéraire. Associé à la culture de Cerny, ces vestiges offrent un observatoire privilégié des mutations sociales que connaissent les communautés du Néolithique moyen en France. À partir d’une approche archéo-anthropologique, nous livrons ici un bilan complet de la population Cerny, au niveau général, à l’échelle des trois types de site (à structure de type Passy, plats et à sépulture sous dalle), et au niveau de chaque nécropole. Les sites de Passy, Balloy, Gron, Escolives-Sainte-Camille, Vignely (La Noue Fenard et La Porte aux Bergers), Chichery, Orville, Malesherbes (Les Marsaules et La Chaise), qui réunissent l’essentiel des squelettes Cerny mis au jour (n=160), font l’objet de cette étude. Quel que soit le niveau scalaire, le croisement des paramètres biologiques et archéologiques est systématisé et soumis à la décision statistique. Les résultats s’inscrivent dans un cadre interprétatif fiable grâce à de nouvelles datations 14C. Les analyses intra-sites révèlent différentes modalités sélectives des défunts et, parfois, le rassemblement codifié de sépultures en différents loci. Le statut des inhumés et leur fonction sociale jouent un rôle prépondérant dans la structuration des sites. Deux modèles organisationnels, dont un, répété de nécropole en nécropole, illustre une hiérarchisation des statuts à l’intérieur des structures monumentales. La correspondance de ces mêmes statuts en nécropoles plates suggère que l’identité sociale des défunts n’est pas la seule raison d’être du monumentalisme funéraire. Enfin, la dualité du Cerny, traditionnellement rattachée à deux manifestations diachroniques de la culture, doit être reconsidérée. La différenciation typologique évidente entre les longs couloirs de type Passy et les sépultures sous dalles de type Malesherbes, est ici soutenue par une distinction d’ordres funéraire et biologique, indépendamment du facteur chronologique, remettant en question l’unité culturelle du Cerny
During the 5th millennium B.C., the Paris Basin sees the emergence of the first necropoles and funerary monumentality. Associated with the Cerny culture, these vestiges offer a privileged insight into the social transformations of Middle Neolithic communities in France. Following an archaeo-anthropological approach, we present a full assessment of the Cerny population as a whole, according to the three types of sites (Passy type structures, extended flat sites and slab graves) and with regard to each necropolis. The sites of Passy, Balloy, Gron, Escolives-Sainte-Camille, Vignely (La Noue Fenard and La Porte aux Bergers), Chichery, Orville, Malesherbes (Les Marsaules and La Chaise), which comprise the bulk of Cerny skeletons uncovered (n=160), constitute the object of this study. The cross-referencing of biological and archaeological parameters is systematized and subjected to statistical reasoning, regardless of the scalar value. These results, combined with new 14C dates, provide a reliable interpretive framework. Intrasite analyses reveal different modes of selection of the deceased and, occasionally, codified grouping of burials into separate loci. The rank of the dead and their social status play a predominant role in the structuring of the sites. Two models of organisation, one of which is repeated in every necropolis, illustrate the social stratification operating within monumental structures. The presence of individuals of similar status in flat necropoles suggests that the social identity of individuals is not the raison d'être of monumental graves. Moreover, the duality of the Cerny culture, traditionally seen as two diachronic manifestations of this culture, must now be reconsidered. The clear typological distinction between the long passage tombs of the Passy type and the slab graves of the Malesherbes type is herein upheld on both funerary and biological levels, regardless of chronology, thus calling the Cerny cultural unity into question

Los estilos APA, Harvard, Vancouver, ISO, etc.

41

Ho, Wan-chien y 何萬謙. "Variations of ionospheric neutral densities in response to solar activity". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/71310393180035983666.

Texto completo

Resumen

碩士
國立中央大學
太空科學研究所
102
This thesis focuses on the studies of variations of neutral densities at a height of 410 Km in response to solar activity. It use solar radiation indices F10.7 and EUV to linearly fit neutral density measured by the Challenging Minisatellite Payload (CHAMP) satelliteduring the period 2003 - 2008. Aclearly phase delay in solar radiation and neutral density have been found when we were doing data analysis. It's also pointed out that neutral density variation has a time delay with solar radiation in the previous papers. In this study, we could get a conclusion that the time delay is one day during 2003 to 2008. In doing the linear regression,the result from multiple parameters is almost the same as that from single parameter. And, because of the more completeness of the observations of F10.7 than EUV, we decide to use F10.7 index to be the main parameter in the following studies. To compare original data of neutral density with the fitted data has a significant difference in the period of low solar activity. The difference has high relation with Kp index. Additional linear regression is required for these differences with Kp index.The results indicate that solar radiation is a dominate factor in the variations of neutral densities in the period of high solar activity, and geomagnetic activity produced by the solar wind becomes important in the low solar activity. The difference between original data of neutral density with the fitted data has a period of 130 days, which can be attributed to the satellite orbit.Removement of this component can increase the correlation coefficient of the original data the fitted data up to 0.95. But this effect is only important in the period near solar minimum.

Los estilos APA, Harvard, Vancouver, ISO, etc.

42

Liu, Shao-Hua y 劉少華. "A system dynamics study for city developmet and activity of controlling Hsichin flood". Thesis, 2003. http://ndltd.ncl.edu.tw/handle/29353246528056923535.

Texto completo

Resumen

碩士
國立中山大學
公共事務管理研究所
91
From the beginning of 1980s, Hsichin has become a dreaming heaven of emigrants who move to the urban area of Taipei because the fever of housing market and the policy of government. As the high density development of slope land, the runoff capacity will be increased. On the other hand, river land will be decreased by city growth. Impacting by the above two reason, Hsichin is called as the flown city by the mass media. The goal of this research is discussing the reaction between the city development of Hsichin, the flood event, and the flood prevention activities. This research uses “System Dynamics” as a research method, simulating with “iThink” computer software, building a model of Hsichin city growth and flood event, using this model to precede the policy test to find out which policy will be the economic benefit. The research conclusion is: 1. The aspect of engineering activities: We adopt three policies including Yuansantze activity, dike building activity, and dredging activity. Under the same cost, we’ll find out Yuansantze activity is the most benefit one. When mixing all policies, the most benefit one is putting the fund as 25% in dike building and 75% in dredging. These activities are focused on lowering flood damage directly. In the short term, the outcome is very obvious. However, in the long term, combining city growth management will be the only solution to solve problems of not only city overgrowth but also land development disequilibrium. 2. The aspect of city growth management: We adopt three policies including slope land conservation, converting land to flood storage area, and limiting of population and business. By this research, we’ll find out limiting of population and business is the most efficient method focused on controlling population scale and lowering land development. This research provides an alternative way which is combining limiting high density development and slope land conservation to solve the situation of land development disequilibrium. In my opinion, the authority government cannot take engineering activities as the only way to control flood damage, however, the government should combine two aspects of controlling flood activities to solve Hsichin flood problem.

Los estilos APA, Harvard, Vancouver, ISO, etc.

43

Davidson, Daniel. "A Rock Physics Based Investigation of Pore Structure Variations Associated with a CO2 Flood in a Clastic Reservoir, Delhi, LA". Thesis, 2013. http://hdl.handle.net/1969.1/151283.

Texto completo

Resumen

The permeability in siliclastic rocks can vary due to different pore geometries. The pore properties of a formation can also have significant effects on reflection coefficient. The pore structure of clastic rock may be predicted from a wave reflection using mathematical models. Biot-Gassmann and Sun’s equations are examples of two models which were used in this research to quantify the pore property. The purpose of this thesis is to measure variations in porosity and permeability using 3-D time lapsed seismic during a CO_(2) flood. CO_(2) sequestration EOR will most likely cause permanent diagenetic effects that will alter pore geometry and permeability. This research shows compelling evidence that the pore structure changes in an active CO_(2) flood at the Delhi Holt-Bryant reservoir can be measured with acoustic data. The pore property change is measured by using the Baechle ratio, the Gassmann model, and the Sun framework flexibility factor. The change in the pore properties of the formation also indicates a increase in the permeability of the reservoir as a result of CO_(2) interaction.

Los estilos APA, Harvard, Vancouver, ISO, etc.

44

Wu, Bo-Shen y 於柏伸. "Antioxidative activity in extracts of oyster and the variations in season and cultured area". Thesis, 2005. http://ndltd.ncl.edu.tw/handle/83643803039612858507.

Texto completo

Resumen

碩士
國立臺灣海洋大學
食品科學系
93
This study investigates the antioxidative activity in oyster (Crassostrea gigas) meat in relation to the effects of extraction condition, enzymatic treatment, fractionation, and variation in season and cultured area. The specimens were cooked in boiling water, homogenized, and freeze-dired in vacuum to obtain a lyophilized meat powder as the sample for experiments. The extraction conditions including hot water (HW), HW-ether, HW-80% ethanol, 80% ethanol, and 80% ethanol-ether were used to prepare extracts from the meat sample. The extracts were then compared for the inhibition on hemoglobin-induced linoleic acid (C18:2) peroxidation, scavenging α,α-diphenyl-β-picrylhydrazyl (DPPH) radical, reducing power, and Fe2+-chelating effect. Among the five extracts, the HW extract exhibited a higher inhibition on C18:2 peroxidation, scavenging DPPH effect, and Fe2+-chelating effect. However, there was no significant difference in reducing power. The data showed that the high-molecular-weight substances in oyster meat extract also contributed to antioxidative activity. To oyster meat powder, the digestive enzymes (pepsin and trypsin) and proteases from commercial sources (Prozyme 6, Protease A, Protease N, Flavourzyme, papain, Alcalase, and Protamex) were added and hydrolyzed at 37℃ or 50℃ for 6 and 12 hours. Among the enzymes used, the Prozyme 6, Protease A, and Protease N hydrolysates were relatively high in antioxidative activity. The effect of hydrolysis time (0-12 hours) by Prozyme 6, Protease A, and Protease N was examined further. The data showed that the hydrolysis is for 9 hours was a better condition.. Accordingly, the 9-hour hydrolysates of Prozyme 6, Protease A, and Protease N together with their low-molecule-weight fractions (LMW-I and LMW-II) separated by 80% ethanol extraction wereprepared and lyophilized to measure in antioxidative activity at different concentrations. In comparison, the hydrolysates were the highest in the inhibition on C18:2 peroxidation IC50 0.40~0.68 mg/mL and Fe2+-chelating effect IC50 0.37~0.71 mg/mL, LMW-IIs were the highest in scavenging DPPH effect IC50 0.97~1.34 mg/mL, and LMW-Is were the highest in reducing power IC50 0.37~0.71 mg/mL. The IC50 values of scavenging DPPH radical determined by HPLC method decreased by 20~31% as compared with that by photometric method. The difference might be due to a reaction product of DPPH radical after being scavened is absorbance at 517 nm , it maybe caused error on photometric method. The oyster specimens collected from different seasons and cultured areas were also measured for antioxidative activity using their HW extracts. The antioxidative activities varied largely, Especially the inhibition on C18:2 peroxidation in Chang-Hua samples ranged from the highest in Jul. (99.5%) to the lowest in Jan. (2.2%). On the whole, the Chang-Hua sample than Chia-Yi sample, the sample in spring and summer than other seasons tended to be high in antioxidative activity.

Los estilos APA, Harvard, Vancouver, ISO, etc.

45

Shepherd, Simon J., S. I. Zharkov y Valentina V. Zharkova. "Prediction of Solar Activity from Solar Background Magnetic Field Variations in Cycles 21-23". Thesis, 2014. http://hdl.handle.net/10454/10790.

Texto completo

Resumen

yes
A comprehensive spectral analysis of both the solar background magnetic field (SBMF) in cycles 21-23 and the sunspot magnetic field in cycle 23 reported in our recent paper showed the presence of two principal components (PCs) of SBMF having opposite polarity, e. g., originating in the northern and southern hemispheres, respectively. Over a duration of one solar cycle, both waves are found to travel with an increasing phase shift toward the northern hemisphere in odd cycles 21 and 23 and to the southern hemisphere in even cycle 22. These waves were linked to solar dynamo waves assumed to form in different layers of the solar interior. In this paper, for the first time, the PCs of SBMF in cycles 21-23 are analyzed with the symbolic regression technique using Hamiltonian principles, allowing us to uncover the underlying mathematical laws governing these complex waves in the SBMF presented by PCs and to extrapolate these PCs to cycles 24-26. The PCs predicted for cycle 24 very closely fit (with an accuracy better than 98%) the PCs derived from the SBMF observations in this cycle. This approach also predicts a strong reduction of the SBMF in cycles 25 and 26 and, thus, a reduction of the resulting solar activity. This decrease is accompanied by an increasing phase shift between the two predicted PCs (magnetic waves) in cycle 25 leading to their full separation into the opposite hemispheres in cycle 26. The variations of the modulus summary of the two PCs in SBMF reveals a remarkable resemblance to the average number of sunspots in cycles 21-24 and to predictions of reduced sunspot numbers compared to cycle 24: 80% in cycle 25 and 40% in cycle 26.

Los estilos APA, Harvard, Vancouver, ISO, etc.

46

Martin, Barton Sawyer. "Geochemical variations within the Roza Member, Wanapum Basalt, Columbia River Basalt Group: Implications for the magmatic processes affecting continental flood basalts". 1991. https://scholarworks.umass.edu/dissertations/AAI9120914.

Texto completo

Resumen

Plagioclase phyric lavas of the Roza Member cover approximately 40,000 km$\sp2$ in Oregon and Washington. Field relationships in 85 stratigraphic sections and geochemical analysis of 765 samples indicate that the Roza Member consists of 1 to 4 flow units. Systematic variations in Cr, Nb, Zr, P$\sb2$O$\sb5$, and TiO$\sb2$ allow these flow units to be divided into 6 chemically distinct subtypes. Incompatible element abundances decrease while the Cr concentration and plagioclase phenocryst population increase upward through the Roza succession. Most other elements display only minor variations. Stratigraphic relations between the 6 Roza subtypes are complex. The areal distribution of each subtype reflects the interaction of the constructional topography of older Columbia River basalts, regional structure, geomorphology, and location and timing of activity along the 175-km long linear Roza vent system. The distribution of the chemically defined subtypes within the dikes and vents indicate that only short segments of the vent system were active at any given time. Calculations (assuming a conductive cooling regime--an assumption supported by primary intraflow features and cooling-joint measurements), indicate that decades elapsed between successive Roza eruptions. These temporal constraints are supported by a lack of saprolite horizons between Roza cooling units and an absence of large-scale geochemical variation due to magma reservoir processes, and are consistent with estimates of Columbia River basalt recharge rates. The earliest Wanapum eruptions (the Robinette Mountain and Dodge Basalts, Eckler Mountain Member) were distinctly more mafic than the subsequent "main" Wanapum Frenchman Springs-Roza-Priest Rapids sequence (e.g., Rob. Mtn.: Mg' $\approx$ 61, Nb $\approx$ 4ppm, Cr $\approx$ 137ppm; versus Roza: Mg' $\approx$ 39, Nb $\approx$ 15ppm, Cr $\approx$ 33ppm). The main Wanapum succession is enriched in both the large ion lithophile elements (K, Rb, Ba, Th) and radiogenic isotopes relative to the Eckler Mountain lavas. However, similar incompatible element rations for the Wanapum basalts imply lava derivation from comparable mantle sources. Major and trace element modelling suggest that coupling fractional crystallization of OL + PL + CPX + TiMT ($\approx$5:60:34:1) with periodic eruption of $\approx$10 volume percent of a steady state reservoir, minor ($\approx$3%) assimilation of crust similar to the Wallowa Batholith, and recharge by a Robinette Mountain-like parental magma can generate lavas compositionally similar to the Frenchman Springs-Roza-Priest Rapids sequence.

Los estilos APA, Harvard, Vancouver, ISO, etc.

47

Liou, I.-Ching y 劉怡青. "Antioxidative activity in extracts of hard clam and the variations in season and cultured area". Thesis, 2004. http://ndltd.ncl.edu.tw/handle/91584792922590349418.

Texto completo

Resumen

碩士
國立臺灣海洋大學
食品科學系
92
Abstract This study investigates the antioxidative activity in extracts of hard clam in relation to enzymatic treatment, fractionation, season, and cultured area. The hard clam specimens were cooked, homogenized, and freeze-dried in vacuum to become lyophilized meat powder as sample for the experiments. To meat sample, different enzymes including digestive enzymes ( pepsin, trypsin, α-amylase and α-glucosidase) and proteases form commercial sources (Protease A, Protease N, Prozyme 6, papain, Flavourzyme, Alcalase and Protamex) were added and kept at 37℃ or 50℃ for 12 hours. The hydrolysates were then measured for inhibition on hemoglobin-induced linoleic acid peroxidation, scavenging α,α-diphenyl-β-picrylhydrazyl (DPPH) radical, and reducing power. Among the enzymes used, the Protamex, Alcalase and Prozyme 6 extracts were relatively high in antioxidative activities. The hydrolysis by the 3 enzymes for 0-12 hours was examined further. Results showed that their antioxidative activities became higher with the increase of hydrolysis time. Accordingly, the 12-hour hydrolysates of Protamex, Alcalase, and Prozyme 6 along with their low-molecule-weight fractions (LMW-І and LMW-ІІ) were lyophilized and measured for their dose-dependent changes in antioxidative activity. LMW-І was prepared from the hydrolysate by adding ethanol to a final concentration of 80% ethanol to precipitate large molecules. LMW-ІІ was prepared by the same manner except that after hydrolysis, the whole reaction mixture was used. It was found that the antioxidative activity in hard clam mainly derived from the contribution of low-molecule-weight substances. In comparison with LMW-І, the IC50 values from LMW-ІІ were small, ranging between 3.68-3.92 mg/mL for inhibition on hemoglobin-induced linoleic acid peroxidation, 1.17~2.19 mg/mL for scavenging DPPH radical, and 4.08~16.23 mg/mL for reducing power, respectively. Also, the IC50 values of scavenging DPPH radical as determined by HPLC method showed a decrease of 6.0-58.5% as compared with that of photometric method. On the other hand, antioxidative activity of the lyophilized samples at the concentrations of IC50 changed considerably after being digested by α-amylase and α-glucosidase. The hard clam specimens from different season and cultured areas were also collected to obtain a lyophilized meat sample. Their 80% ethanolic extract was then to prepared measure antioxidative activity. On the whole, samples from spring and autumn seasons tended to be high in antioxidative activities. In addition, considerable variations in inhibition on hemoglobin-induced linoleic acid peroxidation, scavenging DPPH radical, and reducing power were also observed between samples collected from different cultured areas.

Los estilos APA, Harvard, Vancouver, ISO, etc.

48

Lin, Guo-Tai y 林國泰. "Antioxidative activity in extracts of freshwater clam and the variations in season and cultured area". Thesis, 2005. http://ndltd.ncl.edu.tw/handle/56899647219979181315.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

49

Penm, Jammie H. "An econometric time-series analysis of Australian housing activity from a macroeconomic perspective". Phd thesis, 1993. http://hdl.handle.net/1885/131967.

Texto completo

Resumen

The significant fluctuations in housing activity over time can be regarded as "interesting" and "special". The persistence of such cyclical behaviour of housing activity through periods of different economic and demographic conditions has attracted significant research efforts to investigate the underlying influences and the implications for the economy as a whole. In this thesis, the factors which contribute to cyclical fluctuations in housing activity are examined using econometric time-series techniques. While the commonly used indicators of housing activity are stationary over the sample period investigated, most important economic and financial variables which significantly influence housing activity can be characterised as co-integrated of order (1, 1). A new procedure is therefore developed and utilised widely for examination of such systems which contain both co-integrated and stationary series. This procedure is an innovative way of analysing housing activity as the "error-correction" like processes generated from the co-integrated economic and financial variables form an important part of the system in explaining the cyclical fluctuations in housing activity. In this thesis, it is shown that the fluctuations in housing activity are related to the policy instruments used by the Government for stabilising the macroeconomy. In particular, housing activity is found to respond significantly to changes in short term interest rates and real income, or general economic activity, although the effects resulting from changes in the money supply and general price level are much less substantial. While the response of housing activity to a change in short term interest rates is prolonged, the effect of innovations in real income, or general economic conditions, on housing activity only persists for a much shorter period. In addition, policy on immigration is also an important element influencing the level of housing activity. However, over the short to medium terms, changes in economic and financial variables produce more significant effects on housing activity than that generated by net migration or increases in population. Interestingly, housing activity also feeds back on the level of short term interest rates, which suggest that housing activity may be an important determinant in the decision-making processes of the monetary authorities. In contrast to previous testing for Australia, housing activity is found to "Granger cause" general economic growth in a number of modelling exercises. These results consistently affirm that housing activity contains leading information for changes in general economic conditions and, therefore, can be used as a "leading indicator" of general economic activity.

Los estilos APA, Harvard, Vancouver, ISO, etc.

50

Sehlakgwe, Phophi Freda. "Developing propagation methodology and determining seasonal variation and antibacterial activity for a cosmeceutical species, Leucosidea sericea". Diss., 2018. http://hdl.handle.net/10500/23598.

Texto completo

Resumen

The aim of this study was to determine propagation methodology of L. sericea taking into consideration the effect of season and storage. The response of tip and basal cuttings of L. sericea to three hormonal treatments and three growth media was investigated. Seed germination response to five constant temperatures and four pre-sowing treatments was also investigated. Using NMR spectroscopy, the effects of season and storage on metabolites in leaves of L. sericea were investigated. All treatments did not initiate or improve rooting of L sericea cuttings. Seed germination percentage was significantly affected by temperature and pre-sowing treatment compared to control. The optimum seed germination percentage was obtained at 15°C (53%) when treated with smoke water. Seasonal variation affected leaf metabolite profiles. Storage did not affect the antibacterial activity of L. sericea leaves and those harvested in winter showed an MIC value of ≤3.90μg/mL when tested on Propionibacterium acnes
Agriculture, Animal Health and Human Ecology
M. Sc. (Agriculture)

Los estilos APA, Harvard, Vancouver, ISO, etc.

Tesis sobre el tema "Variations in flood activity"

Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros