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1
Dhervillez, Catherine. "Contribution à l'étude des mécanismes des variations respiratoires du rythme cardiaque chez le rat." Lille 1, 1987. http://www.theses.fr/1987LIL10092.
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Il existerait trois types de mécanismes : un mécanisme central consistant en une irradiation des centres respiratoires sur les centres cardio-régulateurs ; un mécanisme réflexe ayant son origine au niveau soit du cœur, des poumons, du thorax, soit au niveau vasculaire ; un mécanisme ayant plusieurs origines
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Mavrogiannis, Apostolos. "Variations in the ventilatory and lactate thresholds with prolonged aerobic exercise." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25127.
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The purpose of this study was to examine the changes in the ventilatory (VT) and lactate (LT) thresholds and VO₂max following prolonged aerobic exercise. Six well-trained distance runners (T:age=25.2 yrs, Ht=170.0 cm, Wt=65.0 kg, VO₂max=59.6 ml •kg⁻¹•min⁻¹) and six untrained (UT:age=25.3 yrs, Ht=180.3 cm, Wt=79.2 kg, VO₂max=46.8 ml•kg⁻¹•min⁻¹) males were studied on two occasions seven days apart. The initial evaluation involved a continuous horizontal treadmill test with a starting velocity of 2.22 m•s⁻¹, which was increased by 0.22 m•s⁻¹ each minute until fatigue. Expired gases were continuously sampled and analyzed by a Beckman Metabolic Measurement Cart. Measurements were processed by a data acquisition system (HP 3052A), which determined respiratory gas exchange variables every 15 seconds. Blood lactate measurements were taken via an indwelling catheter during the last 10 sec of each minute of work. VT and LT were determined by visual inspection of the excess CO₂ elimination and lactate curves, respectively. Seven days later the subjects repeated the treadmill test preceded by a 60 minute treadmill run at a heart rate corresponding
to their LT. The physiological measurements recorded during the first session were repeated. There were significant (p<0.10) reductions in VO₂max, LT, VT, and total treadmill time on the VO₂max test (TTT) in the T group (59.6 to 56.9 ml •kg⁻¹•min⁻¹, 9.6 to 9.3 mph , 8.9 to 8.2 mph , and 925.0 to 882.5 sec, respectively). VO₂max, LT, VT, and TTT were reduced in the UT group (46.8 to 45.0 ml•kg⁻¹•min⁻¹ 7.7 to 7.6 mph, 8.0 to 7.2 mph, and 730.0 to 652.5 sec, respectively), however, only VT and TTT were reduced significantly (p<0.10). Although the groups were significantly different (p<0.05) in the initial physiological measures due to training status, there was no change in the rate of decline in VO₂max, LT, VT, or TTT when the UT group was compared to T. As LT and VT are affected by prolonged aerobic exercise it is questionable whether these thresholds can be used with confidence to predict endurance performance in events up to 60 min duration for well-trained and recreational athletes.Education, Faculty of
Curriculum and Pedagogy (EDCP), Department of
Graduate
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Comstedt, Daniel. "Explaining temporal variations in soil respiration rates and delta13C in coniferous forest ecosystems." Doctoral thesis, Örebro universitet, Institutionen för naturvetenskap, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-2055.
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Soils of Northern Hemisphere forests contain a large part of the global terrestrial carbon (C) pool. Even small changes in this pool can have large impact on atmospheric [CO2] and the global climate. Soil respiration is the largest terrestrial C flux to the atmosphere and can be divided into autotrophic (from roots, mycorrhizal hyphae and associated microbes) and heterotrophic (from decomposers of organic material) respiration. It is therefore crucial to establish how the two components will respond to changing environmental factors. In this thesis I studied the effect of elevated atmospheric [CO2] (+340 ppm, 13C-depleted) and elevated air temperature (2.8-3.5 oC) on soil respiration in a whole-tree chamber (WTC) experiment conducted in a boreal Norway spruce forest. In another spruce forest I used multivariate modelling to establish the link between day-to-day variations in soil respiration rates and its δ13C, and above and below ground abiotic conditions. In both forests, variation in δ13C was used as a marker for autotrophic respiration. A trenching experiment was conducted in the latter forest in order to separate the two components of soil respiration. The potential problems associated with the trenching, increased root decomposition and changed soil moisture conditions were handled by empirical modelling. The WTC experiment showed that elevated [CO2] but not temperature resulted in 48 to 62% increased soil respiration rates. The CO2-induced increase was in absolute numbers relatively insensitive to seasonal changes in soil temperature and data on δ13C suggest it mostly resulted from increased autotrophic respiration. From the multivariate modelling we observed a strong link between weather (air temperature and vapour pressure deficit) and the day-to-day variation of soil respiration rate and its δ13C. However, the tightness of the link was dependent on good weather for up to a week before the respiration sampling. Changes in soil respiration rates showed a lag to weather conditions of 2-4 days, which was 1-3 days shorter than for the δ13C signal. We hypothesised to be due to pressure concentration waves moving in the phloem at higher rates than the solute itself (i.e., the δ13C–label). Results from the empirical modelling in the trenching experiment show that autotrophic respiration contributed to about 50% of total soil respiration, had a great day-to-day variation and was correlated to total soil respiration while not to soil temperature or soil moisture. Over the first five months after the trenching, an estimated 45% of respiration from the trenched plots was an artefact of the treatment. Of this, 29% was a water difference effect and 16% resulted from root decomposition. In conclusion, elevated [CO2] caused an increased C flux to the roots but this C was rapidly respired and has probably not caused changes in the C stored in root biomass or in soil organic matter in this N-limited forest. Autotrophic respiration seems to be strongly influenced by the availability of newly produced substrates and rather insensitive to changes in soil temperature. Root trenching artefacts can be compensated for by empirical modelling, an alternative to the sequential root harvesting technique.
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Ceschia, Eric. "Environmental effects on spatial and seasonal variations of stem respiration in European beech and Norway spruce /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2001. http://epsilon.slu.se/avh/2001/91-576-6303-3.pdf.
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Ceschia, Eric. "Effets environnementaux sur les variations spatiales et saisonnières de la respiration ligneuse chez le hêtre et l'épicéa." Paris 11, 2001. http://www.theses.fr/2001PA112349.
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Cette thèse discute des facteurs environnementaux et biologiques contrôlant la respiration ligneuse chez le Hêtre et l'Epicéa. Les résultats sont issus de mesures sur le terrain en France et en Suède entre 1997-2000. Les effets de la fertilisation et des fortes [CO2] sur la croissance et la respiration des tiges furent étudiés. La respiration ligneuse variait avec les changements saisonniers de température et de croissance secondaire. Les variations spatiales de la respiration étaient dues à des gradients de température, distributions inégales de cellules vivantes, différences de croissance radiale, et différences de vitalité le long des axes. Les plus forts taux de respiration étaient enregistrés au sommet des troncs ou dans la couronne. Négliger ces variations spatiales de respiration causeraient des erreurs de 30-110% dans l'estimation de la respiration annuelle des parties ligneuses aériennes (Rag). Rag représentait près de 30% de la respiration totale annuelle pour la forêt de Hêtre. Rag était de 245-289 g C m-2 a-1 pour le Hêtre et de 64 et 134 g C m-2 a-1 pour les couverts d'Epicéa non-traités et fertilisés, respectivement. L'efficience d'utilisation du carbone était de 0. 58, 0. 71, et 0. 72 pour le Hêtre et les Epicéas non-traités et fertilisés, respectivement. La respiration de croissance représentait près de 40% de la respiration totale. Le coût moyen de construction du bois (rG) était de 0. 2 et 0. 16 g C respiré g-1 C fixé dans le nouveau cerne pour le Hêtre et l'Epicéa mais rG augmentait dans la couronne par rapport à la base du tronc. La fertilisation accroissait rG pour l'Epicéa mais la respiration d'entretient (R_M) n'était pas affectée. En forte [CO2], rG augmentait légèrement pour l'Epicéa mais pas pour le Hêtre. RM n'était pas affecté par les [CO2] pour les arbres fertilisés, mais en absence de fertilisation, Rm augmentait d'un facteur 2. 5 pour l'Epicéa. Des changements de composition du bois pourraient expliquer les augmentations de rG et RmThis thesis discusses the environmental and biological factors controlling stem respiration in beech and Norway spruce trees. The results are based on field experiments in France and Sweden in 1997-2000. Effects of fertilization and high atmospheric [CO2] on stem growth and respiration were studied. Woody respiration varied with seasonal changes in temperature and secondary growth. Spatial variation in respiration was explained by temperature gradients, uneven distribution of living cells, differences in diameter increment along the axis and variations in tissue vitality. Higher respiration rates usually were found in the upper stem or in the crown. Neglect of spatial variation in respiration led to errors in estimating annual aboveground woody respiration (Rag) of 30-110%. Rag represented 30% of annual respiration in the beech forest. Rag was 245-289 g C m-2a-1 in beech, 64 and 134 g C m-2 a-1 in control and fertilized stands of Norway spruce, respectively. Carbon use efficiency was 0. 58, 0. 71, and 0. 72 for beech trees, control and fertilized spruce trees, respectively. Growth respiration represented ca. 40% of total stem respiration. The wood construction cost (rG) was on average 0. 2 and 0. 16 g C respired g-1 C fixed in the new wood of beech and spruce trees. For both species, rG was higher in the crown than at breast height. Fertilization increased rG in spruce, but maintenance respiration (RM) was not affected. High [CO2] had little effect on rG in spruce and none in beech. [CO2] had no effect on Rm when fertilization was applied but Rm increased by a factor of 2. 5 for spruce in absence of fertilization. A change in wood composition of trees grown in high [CO2] without fertilization, apparently caused the increase in rG and Rm. In perspective of global warming, Rag would increase by 25% and 14% in young beech and Norway spruce forests, respectively, and the combined effect of high [C02] and global, warming would increase Rag by a factor of 2. 3 in spruce stands
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Comstedt, Daniel. "Explaining temporal variations in soil respiration rates and delta13C in coniferous forest ecosystems." Doctoral thesis, Örebro University, Institutionen för naturvetenskap Department of Natural Sciences, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-2055.
Full textAbstract:
Soils of Northern Hemisphere forests contain a large part of the global terrestrial carbon (C) pool. Even small changes in this pool can have large impact on atmospheric [CO2] and the global climate. Soil respiration is the largest terrestrial C flux to the atmosphere and can be divided into autotrophic (from roots, mycorrhizal hyphae and associated microbes) and heterotrophic (from decomposers of organic material) respiration. It is therefore crucial to establish how the two components will respond to changing environmental factors. In this thesis I studied the effect of elevated atmospheric [CO2] (+340 ppm, 13C-depleted) and elevated air temperature (2.8-3.5 oC) on soil respiration in a whole-tree chamber (WTC) experiment conducted in a boreal Norway spruce forest. In another spruce forest I used multivariate modelling to establish the link between day-to-day variations in soil respiration rates and its δ13C, and above and below ground abiotic conditions. In both forests, variation in δ13C was used as a marker for autotrophic respiration. A trenching experiment was conducted in the latter forest in order to separate the two components of soil respiration. The potential problems associated with the trenching, increased root decomposition and changed soil moisture conditions were handled by empirical modelling. The WTC experiment showed that elevated [CO2] but not temperature resulted in 48 to 62% increased soil respiration rates. The CO2-induced increase was in absolute numbers relatively insensitive to seasonal changes in soil temperature and data on δ13C suggest it mostly resulted from increased autotrophic respiration. From the multivariate modelling we observed a strong link between weather (air temperature and vapour pressure deficit) and the day-to-day variation of soil respiration rate and its δ13C. However, the tightness of the link was dependent on good weather for up to a week before the respiration sampling. Changes in soil respiration rates showed a lag to weather conditions of 2-4 days, which was 1-3 days shorter than for the δ13C signal. We hypothesised to be due to pressure concentration waves moving in the phloem at higher rates than the solute itself (i.e., the δ13C–label). Results from the empirical modelling in the trenching experiment show that autotrophic respiration contributed to about 50% of total soil respiration, had a great day-to-day variation and was correlated to total soil respiration while not to soil temperature or soil moisture. Over the first five months after the trenching, an estimated 45% of respiration from the trenched plots was an artefact of the treatment. Of this, 29% was a water difference effect and 16% resulted from root decomposition. In conclusion, elevated [CO2] caused an increased C flux to the roots but this C was rapidly respired and has probably not caused changes in the C stored in root biomass or in soil organic matter in this N-limited forest. Autotrophic respiration seems to be strongly influenced by the availability of newly produced substrates and rather insensitive to changes in soil temperature. Root trenching artefacts can be compensated for by empirical modelling, an alternative to the sequential root harvesting technique.
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Thomachot, Laurent. "Effet des variations de température et d'humidification des gaz inspires sur la mécanique pulmonaire chez le sujet en ventilation contrôlée." Aix-Marseille 2, 1992. http://www.theses.fr/1992AIX20844.
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Maxime, Valérie. "Contribution à l'étude de la physiologie respiratoire du saumon atlantique (Salmo salar L. ) aux différentes étapes critiques de son cycle biologique : influence des variations de salinité ambiante." Brest, 1990. http://www.theses.fr/1990BRES2013.
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Le metabolisme energetique a ete etudie chez les juveniles de saumon atlantique (parrs et smolts), simultanement en conditions de metabolisme standard et de routine. Les modifications qui surviennent au cours de la smoltification ont ete interpretees en fonction des variations du facteur thermique (isoenzymes) et des facteurs endocriniens qui sous-tendent ce processus. L'action stimulante majeure du metabolisme energetique apparait resulter d'une potentialisation de l'effet de l'hormone de croissance par la triiodothyronine. Il a pu etre etabli que les modifications du metabolisme standard, consecutives a des transferts d'eau douce en eau de mer, etaient differentes selon le niveau d'adaptation au milieu marin acquis par les smolts: diminution chez les presmolts, amplification au terme de la smoltification. Ces effets resultent essentiellement des modifications du metabolisme intermediaire induites par l'augmentation de salinite ambiante. De plus, le surcout energetique de l'osmoregulation serait plus faible que ce qui etait admis jusqu'alors. Parallelement, a ete mise en evidence une diminution du metabolisme de routine, interpretable comme une adaptation comportementale a une limitation des possibilites d'approvisionnement tissulaire en oxygene. Chez le saumon adulte, le transfert inverse d'eau de mer en eau douce induit une diminution du metabolisme energetique, une augmentation de la capacite de diffusion gazeuse des branchies, ainsi que des modifications des concentrations ioniques plasmatiques entrainant une alcalose du compartiment extracellulaire et une augmentation de l'affinite de l'hemoglobine pour l'oxygene. Ces effets pourraient constituer des processus adaptatifs pour la migration anadrome
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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." Phd thesis, Université Claude Bernard - Lyon I, 2012. http://tel.archives-ouvertes.fr/tel-01070877.
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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.
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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.
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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-motriceIn 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
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Cara, Hervé. "Conception d'un dispositif pour la détection automatique des premières variations du niveau de vigilance du conducteur au volant de son véhicule : capteur non-contraignant et électronique associée." Vandoeuvre-les-Nancy, INPL, 1992. http://www.theses.fr/1992INPL010N.
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Actuellement, il n'existe pas de moyen non-contraignant et suffisamment fiable pour détecter automatiquement les premières variations du niveau de vigilance d'un conducteur au volant de son véhicule. Cette étude est centrée sur la détermination d'un paramètre physiologique "la régularité du rythme respiratoire" pour prédire l'assoupissement dans la ou les deux minutes qui le précèdent. Les tests en laboratoire de sommeil ont permis de constater que l'activité électro¬encéphalographique spécifique de l'endormissement est précédée de la régularisation de la fréquence respiratoire. Outre les tests d'expérimentations médicales, ce mémoire présente l'lectronique inhérente à la chaîne d'acquisition et de traitement du signal représentatif des variations de l'impédance thoracique: capteur, signal utile et critères de détection. Ensuite, ce mémoire expose. Les résultats des tests de validation du dispositif de détection et les tests en situation réelle de conduite automobileAt the present time, there is no strainless and reliable mean to automatically detect the first variations of vigilance- state of a vehicule driver. This study is based upon the determination of the physiological parameter (breathing rhythm regularity) to predict sleeping one or two minutes before it occurs. Tests in a leepinglaboratory have pointed out that the EEG activity, during the early sleeping phase is characterized by a breathing rhythm regularization. Besides, this study deals with aH associated electronics of the data acquisition and processing device to seize the signal of thoracic impedance criterions : sens or, useful signal and detection criterions. After that, this report presents the results of the validation tests of detection device and the tests in real condition
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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.
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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 hydriquesThe 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
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Cannavo, Patrice. "Variations saisonnières des activités respiratoire aérobie et dénitrifiante dans la zone non saturée du sol : expérimentation sur une parcelle agricole du Comtat Venaissin et modélisation." Avignon, 2003. http://www.theses.fr/2003AVIG0030.
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La contamination des nappes par le nitrate (NO3-), ainsi que les émissions de gaz à effet de serre tels que le dioxyde de carbone (CO2) et l'oxyde nitreux (N2O) sont des problèmes environnementaux et agronomiques cruciaux pour un développement durable. L'objectif de ce travail était de caractériser durant 7 mois la dynamique des éléments carbone et azote couplée aux activités microbiennes dans la zone non saturée du sol et de souligner, entre autre, l'intérêt de ne pas négliger les processus biologiques existants dans la zone non saturée profonde. Pour cela, un profil de sol situé dans une parcelle agricole du Comtat Venaissin (Velleron, 84) a été étudié. La zone non saturée du sol (environ 2. 50 m d'épaisseur) a été instrumentée pour le suivi des flux hydrique, de gaz, de chaleur et de soluté durant la période inter-culturale, après récolte du mai͏̈s et enfouissement des résidus (fin octobre 2001) jusqu'au semis suivant (début mai 2002). Des analyses microbiologiques ont permis d'une part de suivre les activités respiratoire aérobie et dénitrifiante potentielles, et d'autre part de dénombrer les bactéries hétérotrophes et dénitrifiantes. Les résultats ont souligné la forte dépendance des activités microbiennes aux facteurs environnementaux tels que les précipitations, la température du sol, la teneur en NO3-, et la qualité du carbone organique dissous (COD). Dans la zone non saturée profonde, la teneur en NO3- a été le facteur limitant de l'activité dénitrifiante, et la qualité du COD était en partie responsable des variations saisonnières de l'activité respiratoire aérobie. La modélisation avec le modèle PASTIS des processus biogéochimiques qui se sont produits lors de l'expérimentation a permis de simuler de façon satisfaisante les différents mécanismes. L'ajout d'un module de transport des gaz basé sur la loi de gaz poussières a permis d'estimer correctement les concentrations de CO2 et de N2O dans le sol. La modélisation a souligné l'importance de prendre en compte les activités microbiennes non négligeables dans la zone non saturée profonde. La comparaison modèle-expérience suggère de regarder les points suivants : (1) prendre en compte l'analyse structurale du sol et travailler à l'échelle de l'agrégat, (2) étudier l'effet du gel du sol sur le devenir de la biomasse zymogène, et (3) prendre en compte l'activité enzymatique, dont celle de la N2O réductase. Ces différents points sont primordiaux dans le but d'améliorer les prédictions des quantités de C et N pouvant atteindre la nappeNitrate (NO3-) groundwater contamination, in addition to greenhouse gases emissions such as carbon dioxide (CO2) and nitrous oxide (N2O) are crucial environmental and agronomic problems. The goal of this work was to characterize during a 7-months period C and N dynamics coupled to microbial activities in the vadose zone, emphasizing notably the interest in taking into account the existing biological processes in the deep vadose zone. Thus, a soil profile situated in an arable field in the Comtat Venaissin (Velleron, 84) was studied. The vadose zone (almost 2. 5 m thick) was equipped for water, heat, solute and gas fluxes measurements, during an inter-cropping period, from corn harvesting and tillage with incorporation of maize residues (end of October 2001), to the next sowing (beginning of May 2002). Microbial analysis were performed in order to follow (1) the aerobic respiratory and denitrifying potential activities, and (2) heterotrophic and denitrifying micro-organisms. Results showed the strong environmental factors influence (rainfall, soil temperature, NO3- content, and dissolved organic carbon (DOC) quality) on microbial activities. In the deep vadose zone, the NO3- content was a limiting factor for the denitrifying activity, and the DOC quality was in part responsible of the aerobic respiratory activity seasonal variations. The biogeochemical processes, which occurred during the field experiment, were satisfactorily simulated by the PASTIS model. The addition of a new module for gas transport using the dusty gas theory allowed us to estimate correctly CO2 and N2O concentrations in the soil. The comparison model-experiment suggests to study the following elements: (1) to take into account the soil structure and to work at the aggregate scale, (2) to study the soil freezing effect on zymogenous biomass behaviour, and (3) to take into account the enzymatic activity, notably the N2O reductase enzymatic activity. These elements are really important in order to perform C and N amounts reaching the groundwater
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Emeriaud, Guillaume. "Variations de la capacité résiduelle fonctionnelle chez le prématuré. Interactions avec la ventilation assistée." Phd thesis, Université Joseph Fourier (Grenoble), 2008. http://tel.archives-ouvertes.fr/tel-00338412.
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La capacité résiduelle fonctionnelle (CRF), volume pulmonaire en fin d'expiration normale, est un paramètre essentiel des échanges gazeux. Chez le nourrisson, le maintien du niveau de CRF dépend de l'interaction de différents mécanismes, contrairement à l'équilibre passif observé chez l'adulte. Nous avons essayé d'améliorer la compréhension de ces mécanismes. Dans un premier temps, nous avons confirmé la persistance d'une activité tonique du diaphragme jusqu'en fin d'expiration chez des nourrissons intubés. Cette activité augmente en l'absence de pression expiratoire positive, renforçant l'hypothèse de son implication dans le maintien de la CRF. Nous avons ensuite adapté une méthode de pléthysmographie par inductance pour une utilisation chez le prématuré, y compris en présence d'asynchronisme thoraco-abdominal ou d'assistance ventilatoire. Cette méthode a permis de montrer que chez les prématurés, la variabilité de la CRF est élevée, n'est pas purement aléatoire, et contient une part significative d'autocorrélation. En cas de pathologie respiratoire, le profil de variabilité est différent, avec une autocorrélation plus importante. Cela suggère des retours à l'état antérieur plus lents après perturbation du niveau de CRF. Chez les nourrissons sous assistance respiratoire, l'autocorrélation est encore plus élevée. La caractérisation de la variabilité de la CRF, reflet du degré de liberté du système de contrôle, et la mesure de l'activité tonique du diaphragme, reflet des efforts du nourrisson pour augmenter la CRF, devraient permettre d'améliorer encore la compréhension de la régulation de la CRF, et d'améliorer la prise en charge ventilatoire de ces patients.
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Jian, Jinshi. "Global soil respiration: interaction with macroscale environmental variables and response to climate change." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/92195.
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The response of global soil respiration (Rs) to climate change determines how long the land can continue acting as a carbon sink in the future. This dissertation research identifies how temporal and spatial variation in environmental factors affects global scale Rs modeling and predictions of future Rs under global warming. Chapter 1 describes the recommend time range for measuring Rs across differing climates, biomes, and seasons and found that the best time for measuring the daily mean Rs is 10:00 am in almost all climates and biomes. Chapter 2 describes commonly used surrogates in Rs modeling and shows that air temperature and soil temperature are highly correlated and that they explain similar amounts of Rs variation; however, average monthly precipitation between 1961 and 2014, rather than monthly precipitation for a specific year, is a better predictor in global Rs modeling. Chapter 3 quantifies the uncertainty generated by four different assumptions of global Rs models. Results demonstrate that the time-scale of the data, among other sources, creates a substantial difference in global estimates, where the estimate of global annual Rs based on monthly Rs data (70.85 to 80.99 Pg C yr-1) is substantially lower than the current benchmark for land models (98 Pg C yr-1). Chapter 4 simulates future global Rs rates based on two temperature scenarios and demonstrates that temperature sensitivity of Rs will decline in warm climates where the level of global warming will reach 3°C by 2100 relative to current air temperature; however, these regional decelerations will be offset by large Rs accelerations in the boreal and polar regions. Chapter 5 compares CO2 fluxes from turfgrass and wooded areas of five parks in Blacksburg, VA and tests the ability of the Denitrification-Decomposition model to estimate soil temperature, moisture and CO2 flux across the seasons.
Cumulatively, this work provides new insights into the current and future spatial and temporal heterogeneity of Rs and its relationship with environmental factors, as well as key insights in upscaling methodology that will help to constrain global Rs estimates and predict how global Rs will respond to global warming in the future.Ph. D.
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Hart, Adam Michael. "Seasonal Variation in Whole Stream Metabolism across Varying Land Use Types." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/23256.
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Historically, whole stream open channel metabolism has been measured over short periods in conjunction with nutrient injections to assess nutrient dynamics within streams. The purpose of my study was to understand the seasonal changes in metabolism within and among streams as well as the impacts of different land use. This was addressed by monitoring nine different watersheds in the Little Tennessee River watershed in southwestern North Carolina. The nine study watersheds were selected to represent a gradient of forested, agricultural, and developed land use / land cover types. Data loggers were deployed to collect continuous oxygen, temperature, conductivity, and stage height data from 2010-2011. I used these data to estimate gross primary production (GPP) and ecosystem respiration (ER). GPP and ER were compared to stream chemistry, light, land cover, and storms. I found that there is greater influence of local riparian land cover than watershed land cover on GPP and ER. Streams had varying annual GPP, but generally the peak in GPP occurred in late winter- early spring with lows in fall. GPP was most strongly influenced by the amount of available light, which is directly related to the amount of canopy cover. ER was much more variable than GPP within and among streams but generally peaked in summer and was lowest in the winter. ER was most strongly related to the proportion of agricultural land cover in the local riparian area. My results suggest that local riparian vegetation may have a greater impact on metabolism than mountainside development.Master of Science
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Searle, Stephanie Yoke-Ying. "The temperature dependence of plant alternative oxidase and its impact on respiration rates in nature." Thesis, University of Canterbury. School of Biological Sciences, 2010. http://hdl.handle.net/10092/5930.
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The physiological function of the plant enzyme alternative oxidase has long been a topic of debate. The cyanide-resistant alternative oxidase (AOX), along with the cytochrome c oxidase (COX), catalyzes the reduction of oxygen to water in the electron transport chain of mitochondrial respiration. Although respiration via the alternative pathway (AP) results in approximately one third of the ATP production as respiration via the cytochrome pathway (CP), the AP is utilized by all plants and some fungi and animals. This “energy wasteful” pathway has been proposed to reduce oxidative stress in plant cells under a variety of stressful conditions. Virtually all previous work on the AP has been performed on laboratory-grown plants in controlled environment conditions; thus, there is little knowledge of how the AP responds to unstable conditions and multiple environmental stresses in the field. This thesis presents new methodology for studying AP respiration and the AOX protein in field-grown plants, and investigates how the AP responds to natural changes in environmental conditions in the field in several plant species grown in diverse ecosystem types. The experimental work presented here also investigates how AP activity is related to changes in total rates of respiration, and questions whether abundance of the AOX protein determines electron partitioning to the AP.
AP partitioning (or relative changes in AP partitioning) varied over seasonal timescales in each of the experimental studies. Chapter 3 reports on two species of Chionochloa, a native New Zealand tussock grass growing along an altitudinal gradient. In Chapter 4, seasonal variation was studied in two tree types: Populus x canadensis, a deciduous angiosperm, and Pinus radiata, an evergreen gymnosperm. Quercus rubra trees were studied along an urban-rural gradient originating in New York City in Chapter 5. In a highly exposed and variable environment, relative changes in AP partitioning in two species of Chionochloa were correlated with the previous day’s integrated light. In Quercus rubra, the AP was instead related to temperature changes: relative AP partitioning increased in response to seasonally low temperature in trees grown at colder, more rural field sites, while at the warmer, urban sites, it increased in response to high summer temperatures. Each of these environmental conditions that were related to increases in the AP (high light, low temperatures, and heat) are potentially stressful to plants. Thus, it is possible that the increases in AP respiration observed in these studies served to oxidize excess reducing equivalents generated through stressful conditions. In Chapter 4, although AP partitioning in Populus x canadensis and Pinus radiata varied seasonally, these changes were not directly related to environmental parameters. However, AP partitioning in Populus x canadensis was clearly shown to be dependent on measurement temperature.
In each of the studies presented here, changes in the AP were not related to abundance of the AOX protein. AOX protein abundance showed consistent seasonal patterns in the two deciduous angiosperms, Populus sp. and Quercus sp, and was correlated with seasonal changes in temperature in Chionochloa spp. However, the lack of correlation between protein abundance and AP partitioning indicates that the AP is subject to post-translational control and likely varies more rapidly than protein levels. In each of Chapters 3 – 5, there was no clear impact of changes in AP partitioning on rates of total respiration. As the AP produces less ATP than the CP, I hypothesized that increases in AP activity would lead to higher respiration rates in order to meet a plant’s energy demands. However, in Populus x canadensis and Quercus rubra, respiration rates remained stable during sharp increases in AP partitioning, indicating that, at least under certain conditions, increases in AP activity are accompanied by a decrease in the CP.
In some of the first research studying AP partitioning in field-grown plants, this thesis illuminates possible mechanisms, functions, and implications of the AP. Over a range of plant taxa and environmental settings, this work shows that the AP does respond to stressful conditions in the wild, but that this does not result in increased respiration. Lastly, the methods presented here to study AP activity and AOX proteins in the field enable future studies to further probe the specific responses of AOX to natural stresses.
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Marino, Polly. "Studies on assembly and genetic variation in mitochondrial respiratory complex I." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/289386.
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Complex I (NADH:ubiquinone oxidoreductase) couples electron transfer to proton translocation across the inner mitochondrial membrane, to drive the synthesis of ATP. Its distinctive L-shaped structure comprises 45 subunits, encoded by both the mitochondrial and nuclear genomes, which are assembled by a complicated modular pathway. Complex I genetic defects are the most common cause of mitochondrial disorders and often present in early childhood, with high mortality rates. Recent high-resolution electron cryo-microscopy structures of mammalian complex I provide a foundation for both interpreting biochemical and biomedical data and understanding the catalytic mechanism. First, this thesis explores how the flavin cofactor is inserted into the NADH-binding (N-) domain of complex I. Genetic manipulation of cultured human cells, to starve them of flavin, revealed a hierarchal impact on the mitochondrial flavoproteome. High riboflavin content in the growth media ameliorated observed phenotypes, requiring cell conditioning in low riboflavin conditions. CRISPR knockout of the putative mitochondrial flavin transporter SLC25A32 demonstrated the severe impact of decreased flavin on complexes I and II, and mass spectrometry 'complexome' analyses suggest that the N-domain is still assembled onto complex I in the absence of the flavin. Second, the model organism Yarrowia lipolytica was used to assess the importance of residues in the quinone-binding site of complex I. Three residues with proposed roles in binding the quinone head-group were targeted. One variant was catalytically inactive, while two retained some activity. They showed decreased ability to reduce physiologically-relevant, long chain quinones, but their ability to reduce short-chain analogues was affected less severely. The results suggest a complicated picture in which interactions between the protein and both the hydrophilic quinone head-group and hydrophobic isoprenoid chain contribute to quinone-binding affinity and catalysis. Finally, a model for human complex I, generated from a recent high-resolution structure of mouse complex I, was used to investigate whether the pathogenicity of human variants could be predicted. Structural information on variant residues, including their secondary structure, proximity to key features and surface exposure, was collated and the power of each property to predict pathogenicity investigated. The analysis was then extended to the whole structure, to identify potential pathogenic hotspots in the enzyme, inform future studies of functionally important regions in complex I, and aid the diagnosis of clinically relevant pathogenic variants.
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Dennis, Wilson Dennis. "Estimation of Carbon Dioxide emissions from forest soils based on CO2 concentrations." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-33240.
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Forest soil is an important source of atmospheric CO2. Emission of CO2 from soil is the result of respiration of plant roots and soil organisms (Autotrophic and Heterotrophic respiration). This soil CO2 emission has a variation throughout the year with maximum emissions being in the summer. However, the seasonal variation affected by the external factors is not fully known. The aim of this thesis is to analyze a relationship between concentration of CO2 in the soil-atmosphere and CO2 emissions to the aboveground atmosphere. When knowing the relationship between CO2 concentration in the soil-atmosphere and the emission of CO2 from the soil atmosphere, a function (equation) can be established. Usually, the best fit is considered to establish the relationship. With the equations obtained, it is possible to calculate CO2 emissions using data different projects, where only soil-atmosphere CO2 concentrations were determined. Using the relationships, emissions rates in different soil types and in forest transect have been analyzed for a large number of samples. The effect of nitrogen deposition on CO2 emissions and seasonal variation of CO2 emission has also been studied. The sampled sites chosen for this study were located in different parts of Southern Scandinavia and Germany. A closed chamber was used to measure CO2 emission from soil. Soil CO2 concentrations were measured at every station and the equations were established. Finally, these relationships were used for analyses and comparison of the sites. An equation (best fit) obtained was used to calculate the emission values of CO2. The soil texture had a great influence on the CO2 from the soil besides the atmospheric pressure and temperature variations during the seasons. It is concluded that, therefore the soil texture and had a great influence on the CO2 emission from the soil besides the atmospheric pressure and temperature variations during the season. When knowing the equation between CO2 concentration and emission for a special type of soil, it is possible to estimate emissions based on CO2 concentrations. Therefore large scale sampling of CO2 concentrations could be done and this will facilitate the inventories carried out in e.g. global change studies.
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Ataka, Mioko. "Effect of the moisture heterogeneity of leaf litter layer on temporal and spatial variation in the litter heterotrophic respiration in a warm-temperate forest." Kyoto University, 2015. http://hdl.handle.net/2433/199356.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第19032号
農博第2110号
新制||農||1031(附属図書館)
学位論文||H27||N4914(農学部図書室)
31983
京都大学大学院農学研究科地域環境科学専攻
(主査)教授 谷 誠, 教授 北山 兼弘, 教授 本田 与一
学位規則第4条第1項該当
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Dann, Jeremiah. "Interindividual variation in the embryonic and larval respiration rates of the polar marine invertebrate Sterechinus neumayeri and Odontaster validus and the poecilogenous spionidid Streblospio benedicti." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 71 p, 2009. http://proquest.umi.com/pqdweb?did=1654488301&sid=5&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Mariappan, Sankar. "Soil redistribution impacts on the spatial variation of nutrients, net carbon exchange with the atmosphere and soil respiration rates in highly eroding agricultural fields from the foothills of the Indian Himalaya." Thesis, University of Exeter, 2016. http://hdl.handle.net/10871/23757.
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Using the tracer caesium-137 (137Cs) and experimental approaches this study quantified soil redistribution induced spatial variation of nutrients and soil organic carbon (SOC), net C flux between soil and atmosphere and soil respiration rate at various landscapes positions (eroding to deposition) within agricultural fields from the foot hills of Indian Himalaya. The depth distributions of 137Cs and the spatial patterns of 137Cs inventories were consistent with previous applications of the approach in that low inventories were associated with low concentrations in the cultivation layer and high inventories were reflected in deeper 137Cs profiles indicative of accumulation of labelled soil. This supports the contention that 137Cs is a suitable tracer for use in this environment. The study found that soil redistribution within fields altered the spatial variation of nutrients and SOC; with significantly lower concentrations of nutrients in the most eroded part of fields (upslope) and significantly higher concentrations of nutrients and SOC in the depositional part of field (downslope). The spatial pattern of nutrients and SOC is reflected in differences in depth distributions between eroded and depositional areas. The 137Cs and SOC inventory and depth distribution data were used to derive retrospective assessments of net C exchange between soil and atmosphere. The C flux quantification model was used to estimate lateral and vertical soil and SOC redistribution under an assumption of equilibrium conditions and the net exchange of C between soil and atmosphere was derived from the difference between measured and ‘equilibrium’ SOC inventories. Fluxes were derived for each landscape position within the agricultural fields studies and calculated at field and site scale. High rates of soil loss were measured and the results showed that the majority of eroded sediment and SOC was exported from field with only a small fraction redeposited within the field. The effect of soil and SOC redistribution was to create disequilibrium in SOC dynamics at eroding and deposition positions and this supported the formation of a field scale C sink. The sink strength is highest in the most eroded parts of the fields due to dynamic replacement of eroded C. This is assumed to be due to the high rate of incorporation of SOC-poor subsoil, with a large C-unsaturated surface area, into the cultivation layer. The C sink is smaller that those reported from high nutrient-input mechanised farm lands. Irrespective of the fate of exported SOC, the SOC stocks in the fields appear to be in dynamic equilibrium and, therefore, there is no evidence of a C source to the atmosphere due to erosion. Also the rate of SOC export from the fields is very high, especially when compared with mechanised fields and, if it is assumed that some portion of exported C is stored in some part of low lying area, the C sink strength would be comparable to mechanised farm lands. The soil redistribution and C flux study confirmed the existence of spatial variation in C flux at various landscapes position and was consistent with an important role for vertical mixing of soil and SOC in determining net C exchange with the atmosphere. This informed the design of the final element of the research that examined soil respiration differences in soil from shallow and deep layers in eroding and aggrading landscapes position. Respiration was measured over a one year period in samples derived from separate depth layers and in mixtures of soil from different depths at each landscape position. No significant difference was found in C release rate (per unit mass of C) from topsoil of eroding and deposition position but the subsoil of eroding pits exhibited significantly higher C release than the subsoil from deposition positions. This result suggests that topsoil in both locations has almost equal and similar C origin. The relatively high rate of respiration in sub soils from eroding pits may be due to the presence of a larger proportion of SOC formed from recently incorporated plant material (crop roots) at these locations. In buried and deposition locations the reduced mineralisation is consistent with the proposition that burial of top soil can contribute to formation of a C sink. In the samples containing mixed topsoil and subsoil, evidence for priming was seen where the respiration rate in the mixed sample was significantly higher than the expected rate based on the respiration rate seen in the separate depth samples. No priming was evident in mixed soils from eroding locations, suggesting that mixing of subsoil and surface soil does not accelerate loss of old SOC from the subsoil. In contrast, significant priming action was evident in mixed soils from aggrading locations suggesting that buried SOC at depositional locations may be subject to accelerated respiration as long as it is exposed to fresh plant input (as found in surface soils). In conclusion, despite the low input and low productivity of the farmlands in the Indian Himalaya region studied here, there is consistent evidence that high rates of soil erosion and soil redistribution have induced spatial variation of nutrients and SOC, net C flux and soil respiration rates that combine to create a pattern of SOC stocks that are close to equilibrium and, if some of the exported C is sequestered, to create a net C sink. This result again confirms that erosion induced redistribution of C does not directly cause a net release of C to the atmosphere. The consistency of these results with previous studies suggests that there is both scope and need for soil erosion induced carbon fluxes to be incorporated into carbon budgets, research frameworks, land management and climate change mitigation strategies at policy-relevant scales.
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Calabrese, Pascale. "Recherche d'une méthode de mesure non-invasive des résistances respiratoires : effets ventilatoires et cardiaques de charges résistives." Université Joseph Fourier (Grenoble), 1998. http://www.theses.fr/1998GRE19013.
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Brito, Liziane de Figueiredo. "Emissão do CO2 do solo em diferentes posições topográficas em área sob cultivo de cana-de-açúcar /." Jaboticabal : [s.n.], 2008. http://hdl.handle.net/11449/105188.
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Resumo: A variação espacial e temporal da emissão de CO2 do solo é influenciada por atributos do solo relacionados à produção e ao transporte do gás soloatmosfera. Entretanto, ainda são escassos estudos visando compreender o efeito da topografia sobre a variabilidade da emissão de CO2 do solo, especialmente em área de conversão para o sistema de colheita da cana-de-açúcar mecanizada sem queima. Este trabalho tem como objetivo estudar as variações da emissão de CO2 do solo, em área cultivada com cana-de-açúcar, com histórico de colheita mecanizada sem queima, sob diferentes formas do relevo e posições na encosta. Foram selecionadas uma área situada numa superfície côncava (CONC) e outras duas em posições contrastantes numa superfície linear (encosta superior - ESUP e encosta inferior - EINF). Foram conduzidas avaliações da emissão de CO2 e de atributos do solo, nas três áreas, em duas situações distintas: (1) em 2004, um mês após plantio da cana-de-açúcar, foram conduzidas avaliações em pontos aleatórios em cada uma das três áreas, num mesmo dia, sendo a emissão de CO2, temperatura e umidade do solo avaliados ao longo de 7 meses e, (2) em 2005, um mês após o corte mecanizado da cana-de-açúcar crua, foi caracterizada a variabilidade espacial da emissão de CO2 e demais atributos do solo, por meio da semivariância, nas mesmas posições topográficas. A emissão total de CO2 no período de 7 meses de estudo em 2004 foi 19,26, 23,03 e 22,29 Mg CO2 ha-1 nas áreas CONC, ESUP e EINF, respectivamente. A variação temporal da emissão foi explicada por uma relação exponencial com temperatura, e uma relação linear com umidade do solo. O valor de 10 Q , calculado para as posições CONC, ESUP e EINF, foi de 1,98 (±0,34), 1,81 (±0,49) e 1,71 (±0,31). O efeito da forma do relevo e da posição topográfica sobre a variação da emissão de CO2 do ...(Resumo completo, clicar acesso eletrônico abaixo)Abstract: The spatial and temporal variation of soil CO2 emission is influenced by several soil attributes related to CO2 production and gas transport from soil to atmosphere. However, few studies aiming to understand the effect of topography on the variability of CO2 emissions exist, especially on the sugarcane harvest system without prior burning. The objective of this work was to study the spatial and temporal changes of the soil CO2 emission in an area cultivated with sugar cane, having a mechanized crop system, under different relief forms and slope positions. In a landscape it was selected one area located in a concave form (CONC) and two others located at superior (ESUP) and inferior (EINF) positions in a linear form. It was conducted measurements of soil CO2 emission and soil attributes at the three different locations in two different situations: (1) in 2004, one month after sugarcane plantation, measurements were conducted with randomized repetitions for each area in each sampling day, and soil CO2 emission, soil temperature and soil moisture were also monitored during a period of 7 months, and (2) in 2005, one month after sugarcane harvesting without burning, the spatial variability of soil CO2 emission and soil attributes were characterized by the semivariance in the same topographic positions. Total soil CO2 emission during this period was 19,26, 23,03 e 22,29 Mg CO2 ha-1 for CONC, ESUP e EINF areas, respectively. Temporal variability of soil CO2 emission was explained by an exponential function with soil temperature and a linear function with soil moisture. The 10 Q values were 1.98 (±0.34), 1.81 (±0.49) and 1.71 (±0.31) for CONC, ESUP and EINF, respectively. The effect of relief form and topographic position on soil CO2 emission variation was dependent on the time of measurement. Bulk density, macroporosity, penetration resistance, aggregation and oxidizable organic ...(Comlete abstract, click electronic access below)
Orientador: Newton La Scala Júnior
Coorientador: José Marques Júnior
Banca: Carlos Eduardo Pellegrino Cerri
Banca: Zigomar Menezes de Souza
Banca: Gener Tadeu Pereira
Banca: Wanderley José de Melo
Doutor
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El, haïkali Bouazza. "Estimations des productions organique et inorganique de quelques espèces macrophytobenthiques méditerranéennes calcifiées : interactions avec les conditions naturelles du milieu et rôle dans la variabilité circadienne de certaines caractéristiques physico-chimiques des eaux cotières." Aix-Marseille 2, 2009. http://www.theses.fr/2004AIX22105.
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Certaines espèces macro-phytobenthiques calcifiées forment des bioconcrétionnements caractéristiques des écosytèmes méditerranéens côtiers (trottoirs, coralligène, bourrelets), d'autres définissent des communautés par leur abondance (ex. Communauté à Corallina elongata). Cependant, à la différence des récifs coralliens, peu de choses sont connues sur leur écophysiologie, sur leurs taux de productions organique (photosynthèse-respiration) et inorganique (calcification-décalcification) et sur le rôle de celles-ci dans la variabilité circadienne des paramètres physico-chimiques de l'eau environnante dans ces écosystèmes. Pour contribuer à combler ce manque, nous avons mesuré l'activité photosynthétique et calcifiante chez huit espèces de macrophytes dont la plupart sont calcifiées (Amphiroa rubra, Carollina elongata, Jania corniculata, Lithophyllum lichenoides, Mesophyllum alternans, Peyssonnelia sp. 1, Peyssonellia sp. 2) et chez une espèce non-calcifiée (Ulva rigida). La mesure de ces activités s'est faire au moyen de paramètres (oxygène dissous-O2, pH et alcalinité totale-AT) mesurés lors d'expérimentations, soit par mesures discrètes en début et en fin d'incubations classiques, soit en semi continu toutes les 30 min et sur des cycles de 24h, dans un incubateur automatique (MIA) muni de deux électrodes (O2 et pH). Ces expériences d'incubations ont été menées dans le site de l'anse des Cuivres où une série continue de mesures semi-horaires, conduite depuis 1995 dans l'eau de mer montrait des cycles très amples de variations du pH et de l'O2, sans doute sous l'influence de l'activité des macrophytes.
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Brito, Liziane de Figueiredo [UNESP]. "Emissão do CO2 do solo em diferentes posições topográficas em área sob cultivo de cana-de-açúcar." Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/105188.
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A variação espacial e temporal da emissão de CO2 do solo é influenciada por atributos do solo relacionados à produção e ao transporte do gás soloatmosfera. Entretanto, ainda são escassos estudos visando compreender o efeito da topografia sobre a variabilidade da emissão de CO2 do solo, especialmente em área de conversão para o sistema de colheita da cana-de-açúcar mecanizada sem queima. Este trabalho tem como objetivo estudar as variações da emissão de CO2 do solo, em área cultivada com cana-de-açúcar, com histórico de colheita mecanizada sem queima, sob diferentes formas do relevo e posições na encosta. Foram selecionadas uma área situada numa superfície côncava (CONC) e outras duas em posições contrastantes numa superfície linear (encosta superior – ESUP e encosta inferior – EINF). Foram conduzidas avaliações da emissão de CO2 e de atributos do solo, nas três áreas, em duas situações distintas: (1) em 2004, um mês após plantio da cana-de-açúcar, foram conduzidas avaliações em pontos aleatórios em cada uma das três áreas, num mesmo dia, sendo a emissão de CO2, temperatura e umidade do solo avaliados ao longo de 7 meses e, (2) em 2005, um mês após o corte mecanizado da cana-de-açúcar crua, foi caracterizada a variabilidade espacial da emissão de CO2 e demais atributos do solo, por meio da semivariância, nas mesmas posições topográficas. A emissão total de CO2 no período de 7 meses de estudo em 2004 foi 19,26, 23,03 e 22,29 Mg CO2 ha-1 nas áreas CONC, ESUP e EINF, respectivamente. A variação temporal da emissão foi explicada por uma relação exponencial com temperatura, e uma relação linear com umidade do solo. O valor de 10 Q , calculado para as posições CONC, ESUP e EINF, foi de 1,98 (±0,34), 1,81 (±0,49) e 1,71 (±0,31). O efeito da forma do relevo e da posição topográfica sobre a variação da emissão de CO2 do...
The spatial and temporal variation of soil CO2 emission is influenced by several soil attributes related to CO2 production and gas transport from soil to atmosphere. However, few studies aiming to understand the effect of topography on the variability of CO2 emissions exist, especially on the sugarcane harvest system without prior burning. The objective of this work was to study the spatial and temporal changes of the soil CO2 emission in an area cultivated with sugar cane, having a mechanized crop system, under different relief forms and slope positions. In a landscape it was selected one area located in a concave form (CONC) and two others located at superior (ESUP) and inferior (EINF) positions in a linear form. It was conducted measurements of soil CO2 emission and soil attributes at the three different locations in two different situations: (1) in 2004, one month after sugarcane plantation, measurements were conducted with randomized repetitions for each area in each sampling day, and soil CO2 emission, soil temperature and soil moisture were also monitored during a period of 7 months, and (2) in 2005, one month after sugarcane harvesting without burning, the spatial variability of soil CO2 emission and soil attributes were characterized by the semivariance in the same topographic positions. Total soil CO2 emission during this period was 19,26, 23,03 e 22,29 Mg CO2 ha-1 for CONC, ESUP e EINF areas, respectively. Temporal variability of soil CO2 emission was explained by an exponential function with soil temperature and a linear function with soil moisture. The 10 Q values were 1.98 (±0.34), 1.81 (±0.49) and 1.71 (±0.31) for CONC, ESUP and EINF, respectively. The effect of relief form and topographic position on soil CO2 emission variation was dependent on the time of measurement. Bulk density, macroporosity, penetration resistance, aggregation and oxidizable organic ...(Comlete abstract, click electronic access below)
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Zukurov, Jean Paulo Lopes. "Caracterização molecular de Vírus Respiratório Sincicial Humano (HRSV) isolados na cidade de São Paulo no período de 2007 a 2008." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/87/87131/tde-17082010-131036/.
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O Vírus Respiratório Sincicial Humano (HRSV) é considerado o principal causador de doenças agudas do trato respiratório inferior durante a infância, sendo o principal responsável por um elevado índice de hospitalização de crianças com até cinco anos de idade. Possui distribuição mundial, podendo acometer todas as faixas etárias, entretanto as crianças de 6 semanas a 9 meses são as que desenvolvem problemas mais sérios, como pneumonia e bronquiolite. A epidemia de HRSV apresenta uma sazonalidade bem clara, ocorrendo anualmente no período de outono tardio, inverno ou início da primavera, mas não durante o verão. No presente estudo foi realizada a análise da região G2 da glicoproteína G do HRSV. Um total de 44 amostras positivas para o HRSV do Hospital Universitário (HU) da Universidade de São Paulo (USP), nos anos de 2007-2008, foram seqüenciadas e posteriormente analisadas, sendo então comparadas com seqüências obtidas do NCBI/GeneBank. A análise filogenética mostrou que os genótipos GA2 e GA5, do grupo A, foram os predominantes nos anos de 2007 e 2008, alternando o padrão verificado nos anos anteriores, onde os genótipos do grupo B foram altamente predominantes. A comparação das mutações sinônimas e não sinônimas mostrou uma grande evidência de seleção positiva nos genótipos GA2 e GA5 do grupo A.Human Respiratory Syncytial Virus (HRSV) is considered the most common cause of lower respiratory tract disease in infants and young children and are the main guilty for the elevated children hospitalizations rate under 5 years of age. The HRSV has a world-wide distribution, being able to attack all the ages however the 6 weeks to 9 months children of are the ones that develop more serious problems as pneumonia and bronquiolite. The HRSV outbreak presents a well defined season, occurring annually in the delayed falls period, winter or springs beginning, but not during the summer. In the present study, we performed a phylogenetic analysis from G2 region of HRSV G glycoprotein. Forty four samples positive for HRSV from University Hospital (UH) of University of Sao Paulo (USP) in 2007-2008, were submitted to sequencing by PCR and compared with GenBank sequences. Phylogenetic analysis revealed that HRSV group A genotypes GA2 and GA5 was the predominant in 2007-2008, alternating the standard verified in the previous years, where the group B genotypes had been highly predominant. Comparison of the synonymous/nonsynonymous mutation ratios showed greater evidence for positive selection pressure for group A genotypes GA2 and GA5.
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Chang, Che-Chi, and 張哲誌. "Spatial and Temporal Variations of Plankton Community Respiration in Dongsha Atoll." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/42242960537337202997.
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碩士國立臺灣師範大學
生命科學研究所
102
This study was designed to explore spatio-temporal variations of plankton community respiration (CR) and organic carbon cycle in Dongsha Atoll. Four curises were performed in different seasons. Results showed that the ragne of CR in spring (May), summer (July), autumn (September), and winter (February) were 41.1~279.2, 9.0~116.0, 41.9~113.9 and 0.0~69.8 mg C m-3 d-1, respectively. The lowest rate was observed in winter. Further analyses suggest that the CR was mostly related to biomass and production of plankton communities, especially phytoplankton and bacterioplankton. This assumption can be verified by significant relationships between mean values (per m3) over water depth of CR vs. chlorophyll a (Chl a), heterotrophic bacterial biomass (BB) or production (BP; all p<0.05). Seasonally, the rate of CR might mostly attribute to phytoplankton, particularly diatom, in spring. This assumption could be validated by significant regressions between CR and Chl a or silicate. In summer, the CR was not related to any observed variables. Even though the estimated bacterial respiration accounting for 24.2% of CR, it can not explain the variation of CR rate. In autumn, CR was significantly related to BB (p<0.05), and it suggests that the CR was dominated by bacterioplankton. As state above, the lowest CR was observed in winter, and it might be due to low plankton biomass. Moreover, the mean ratio of primary production to community respiration was close to or higher than 1, and it indicates that the ecosystem of Dongsha Atoll was either carbon balance or autotrophic. It also suggests that there was residual organic carbon deposited to the bottom of Dongsha Atoll or exported to nearby ecosystems.
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Zhong, Min-Hua, and 鐘敏華. "Inter-annual Variations in Soil Respiration in a Moso Bamboo Forest, Central Taiwan." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/r3ta7d.
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Chang, Yi-Pei, and 張怡佩. "Seasonal Variations of Soil Respiration at Natural Hardwoods and China-fir Plantation in Hui-Sun Experiment Forest." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/71020407026830176579.
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碩士國立中興大學
森林學系所
97
From August 2006 to December 2007, we used Continue-Open-Flow-Chamber method to measure soil respiration at natural hardwoods (NH) and China-fir plantation (CFP) in Hui-Sun Experiment Forest. There were two treatments in each forest type—“with litter fall” and “without litter fall”. In NH the soil respiration rates were 28.20 ± 3.48 ~ 136.39 ± 3.65 and 19.06 ± 2.88 ~ 88.91 ± 10.37 CO2 kg ha-1 day-1 in treatments with and without litter fall respectively. In CFP the soil respiration rates were 24.84 ± 7.29 ~ 135.10 ± 18.31 and 18.01 ± 1.78 ~ 75.27 ± 5.84 CO2 kg ha-1 day-1 in treatments with and without litter fall respectively. In all treatments, the soil respiration was lower in December and higher in June or July. The annual and monthly rates of soil respiration were both higher in NH than in CFP. The difference between NH and CFP was particularly great in summer. In both forest types, the soil respiration rates were higher in the treatments with litter fall than those without litter fall. However, the Q10 value was lower in treatments with litter fall than those without litter fall, suggesting that the removal of litter fall would increase the temperature sensitivity of soil respirations. In this study, temperature was the most important environmental factor of soil respiration. There was a significantly positive correlation between temperature and soil respiration. Due to high soil moisture in both NH and CFP, the soil moisture had no effects on soil respiration. Microbial biomass N showed the seasonal fluctuation and had a positive correlation with soil respiration, but was not significantly different between NH and CFP. Soil fungal colonies were greater in NH than in CFP, probably resulting in greater litter decomposition rate in NH. In NH the litter amount varied with the seasons, and had a positive correlation with soil respiration. By contrast, the litter of CFP was difficult to decompose, and thus accumulated in a large amount on forest floor. Different forest stands and vegetation types had different litter quality as well as different soil micro-organisms status. The differences in soil respiration between NH and CFP may be caused by different litter fall decomposition rate. And the soil respiration rates would affect the CO2 concentrations in the canopy of forest, and furthermore affect the CO2 concentrations in the atmosphere.
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Khoury, Samar. "Étude des variations respiratoires associées à une activité rythmique des muscles de la mastication durant le bruxisme du sommeil." Thèse, 2007. http://hdl.handle.net/1866/8012.
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Lai, Chao-Chen, and 賴昭成. "Seasonal variation of bacterial respiration and community respiration in a subtropical coastal system." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/55284915495349931690.
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Wu, Tsung-Han, and 吳宗翰. "Seasona l variation of community respiration in a coastal system with high DOM supply." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/67952126478535554225.
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碩士國立臺灣大學
海洋研究所
91
Through field studies, this study measured the community respiration rate (CR) at the North Coastal Water in Taiwan weekly between 2001/10 to 2002/8. We measured the other auxiliary parameters simultaneously like water temperature﹑nutrient (NO3 and PO4)﹑particular organic carbon (POC)﹑dissolved organic carbon (DOC)﹑chlorophyll-a concentration (chl-a)﹑primary production (PP) and hetertrophic bacterial production (BP) and try to explore the mechanisms which control the time pattern of CR in this coastal water and role of CR play in carbon cycle. The mean of water’s DOC concentration is 2475μM (1537μM ~ 3056μM, n=41), and it is not distinct seasonal variation, but we found the water’s DOC was high 10 times to general coastal water (200μM). The range of CR is 0μM O2/d ~ 19.65μM O2/d and mean is 3.18 ± 3.2μM O2/d (n=43). The highest value of CR in summer was high to 20 times between the lowest value in winter. The data of analysis exhibited the CR to chl-a (R2=0.54 ; n=42 ; P<0.05 )、POC (R2=0.49 ; n=43 ; P<0.05)、water temperature (R2=0.27 ; n=42 ; P<0.05)’ BP (R2=0.27 ; n=37 ; P<0.05) and BR (R2=0.24 ; n=38 ; P<0.05) has the distinct correct correlation. The result of regression between PP to CR shows that this coastal waters in this area is a heterotrophic ecosystem (P/R=0.47). In this heterotrophic ecosystem, we found that the ratio for BP/PP is high to 1.8 (n=30). As a whole, there is an allochthonus organic carbon source supplying this coastal waters, and it made the DOC which was higher 10 times to normal coastal waters. CR and BP (include BR) had distinct seasonal variation and they had distinct correct correlation with water temperature. It meant that the planktonic organic carbon demand was influenced by organic carbon supply. The result of the controlling temperature CR experiment was support the statement. It is a reasonable phenomenon in the system which had a allochthonus high dissolved organic carbon supply. In coastal waters that is interfered easily by human , the P/R<1 was just determined that the system is the inorganic carbon source in its biota function and heterophic . The P/R ratio in reflecting the organic carbon export is not more effect. In so high DOC system, the functional role of microbial loop may be more important than traditional grazing food chain in organic carbon cycling.
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Wilcox, Marianne. "A model of the effects of fluid variation due to body position on Cheyne-Stokes respiration." Thesis, 2013. http://hdl.handle.net/10214/5341.
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Cheyne-Stokes respiration is a distinct breathing pattern consisting of periods of hyperpnea followed by apneas, with unknown etiology. One in two patients with congestive heart failure suffer from this condition. Researchers hypothesize that key factors in CSR are the fluid shift from the standing to supine position and the differences between genders. A mathematical model of the cardio-respiratory system was constructed using parameter values from real data. Hopf bifurcation analysis was used to determine regions of stable versus oscillatory breathing patterns. In the model, Cheyne-Stokes respiration is more likely to occur while in the supine position and males are more likely to develop Cheyne-Stokes than females. These findings, which are in agreement with clinical experience, suggest that both gender and fluid shift contribute to the pathogenesis of Cheyne-Stokes respiration, and that physical quantities such as blood volumes and neural feedback may be sufficient to explain the observations of CSR.Department of Mathematics and Statistics
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Doff, Sotta Eleneide. "Soil Carbon Dioxide dynamics and Nitrogen cycling in an Eastern Amazonian Rainforest, Caxiuana, Brazil." Doctoral thesis, 2006. http://hdl.handle.net/11858/00-1735-0000-0006-B197-C.
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