Dissertations / Theses on the topic 'Temporal trends'
To see the other types of publications on this topic, follow the link: Temporal trends.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Temporal trends.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Drevnick, Paul Elliott. "METHYLMERCURY IN FISH: ACCUMULATION, TOXICITY, AND TEMPORAL TRENDS." Miami University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=miami1180036291.
Full text
2
Wei, Donglai. "Discovering physics and design trends from visual temporal structures." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/117319.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 99-105).
Living in a constantly changing world, we cannot help but notice the temporal regularities of visual changes around us. These changes can be irreversible governed by physical laws, such as glass bottles broken into pieces, or influenced by design trends, such as web pages adopting templates with larger background images. In this dissertation, we build computational models to discover and apply the knowledge of the physics for arrow of time, and the design trends for web pages from image sequences. In the first part of the thesis, I train models to learn the visual cues that are indicative of the arrow of time from large real world video datasets. In the second part of the thesis, I investigate the evolution of visual cues and layout in web page design through screenshots over time. The knowledge of these visual temporal structures are not only of scientific interest by themselves, but also of practical uses demonstrated in this thesis.
by Donglai Wei.
Ph. D.
3
Boumphrey, Ruth Susan. "Polychlorinated biphenyls in the North Atlantic Gannet : temporal and spatial trends." Thesis, Lancaster University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246142.
Full text
4
Rehn, Lukas. "Temporal Trends in Dissolved Inorganic Carbon in a Swedish Boreal Catchment." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-435368.
Full textAbstract:
Inland waters are important systems for transforming, storing and transporting carbon along the aquatic continuum, but also by emitting carbon dioxide (CO2) and methane (CH4) to the atmosphere. In light of the last decades observed increase in dissolved organic carbon (DOC) in many inland waters across the northern hemisphere, a logical question arise whether other aquatic carbon species display similar trends. This study examined the measured concentrations of dissolved inorganic carbon (DIC) in a boreal catchment over a 14-year period. The objectives were to determine changes in DIC concentration over time and try to explain the causes for the observed changes. Data from 15 mostly forested sub-catchments were analyzed, both over the full time period, and grouped by season. Over the full 14-year period, only two of the sites exhibited significant trends in DIC concentration, both being negative. However, by seasonally grouping the data distinct patterns for the different seasons emerged. The autumn and winter data displayed no significant trends, whereas the spring flood data showed significant negative trends for almost all sites (14 out of 15). The summer data showed significant negative trends for seven sites, and positive for one site. The DIC concentration data were expectedly positively correlated with pH across most sites (13 out of 15). The correlation with DOC was negative for most sites (11 out of 15), possibly indicating different origins of the different carbon species. The DIC concentration was also negatively correlated with discharge for most sites (13 out of 15), suggesting a diluting effect with increased discharge. In conclusion, significant negative trends were observed during the spring flood and summer periods. Although the cause of these trends will require further investigation, the correlation analysis showed that the DIC concentration was closely related to the catchment hydrology. This suggests changes in terrestrial source areas where DIC is mobilized during spring and summer, and that these changes might continue during altered hydrometeorological conditions. The differences in DIC trends between sub-catchments further show the variability of the boreal landscape and highlight the need for local-scale process understanding when scaling to larger landscape units. We further conclude that trends in DIC concentration do not follow observed DOC changes over time, suggesting that DIC and DOC exports are mechanistically decoupled.
5
Sant, Eric D. "Identifying Temporal Trends in Treated Sagebrush Communities Using Remotely Sensed Imagery." DigitalCommons@USU, 2005. https://digitalcommons.usu.edu/etd/6612.
Full textAbstract:
The sagebrush shrub steppe ecosystem is of great concern to researchers, conservationists, and the general public because of the documented declines associated with it. Monitoring in the past has generally been point-based and lacking in long-term data. To overcome these deficiencies, an automated method of monitoring was developed using GIS and remote sensing.
Geospatial layers of vegetation, soils, fire history, roads, streams, and springs were acquired and processed to characterize selected monitoring locations. A temporal set of Landsat satellite imagery for the past 30 years was normalized to reduce the effects of sun angle, haze, and sensor change. After normalization, a Tasseled Cap Transformation was adapted with local coefficients to provide a landscape metric which was sensitive to actual ground conditions and meaningful at management level. The Tasseled Cap outputs of brightness and greenness are a relative measure of bare ground and plant productivity, respectively. When measured over time, brightness and greenness provided diagnostic trends and condition of treated big sagebrush communities
6
Jörundsdóttir, Hrönn. "Temporal and spatial trends of organohalogens in guillemot (Uria aalge) from North Western Europe." Doctoral thesis, Stockholms universitet, Institutionen för miljökemi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-8419.
Full textAbstract:
The Arctic and sub-Arctic region of the North Atlantic is a remote area, also in relations to environmental contaminants, such as POPs, BFRs and last but not least, PFCs. Both the BFRs and PFCs are considered emerging pollutants of significant environmental concern. The main objective of this thesis is to increase the knowledge and understanding of organohalogen compound distribution in the Nordic environment, their occurrence in biota and change over time. The temporal change of environmental contaminants in the Baltic Sea was monitored over the years 1971 to 2001, with emphasis on BCPS. Further, the pollution profile of the Nordic region was investigated by using common guillemot eggs. Further, to investigate a single remote site, Iceland, in more depth, eggs from seven marine bird species were collected and analysed. Both the organohalogen compounds mentioned above and their metabolites were investigated. The study focused also on an inter-species difference in the bird’s capability of metabolising xenobiotics. All environmental pollutants investigated in the Baltic Sea show decreasing levels over the time period investigated. BCPS showed a remarkably small change over time compared to other compounds. These results reinforce the previous findings, indicating the North Atlantic as remote where the concentrations of the organohalogens are lower compared to Europe in general. There are some exceptions however; the concentration of HCB is ubiquitously distributed across the study area. Further, the spatial trends of the PFCs are complicated and differ within the PFC group. When comparing bird species from Iceland, the concentration of organohalogens mainly depends on trophic level, while migration seems to contribute to a lesser extent. There are some similarities in the metabolism between the bird species investigated. However, the guillemot seems to distinguish itself from other marine birds, with a different composition of metabolites, indicating a different metabolic capacity. In conclusion, even human populations living in remote areas need to minimise the release of pollutants to the environment. Long term, well organised, and extensive governmental monitoring programs are highly recommended to follow the quality the environment and to detect any immediate and/or new threats of chemical pollutants.
7
Takano, Yohei. "Understanding the mechanisms of dissolved oxygen trends and variability in the ocean." Diss., Georgia Institute of Technology, 2016. http://hdl.handle.net/1853/54994.
Full textAbstract:
A widely observed tracer in the field of oceanography is dissolved oxygen (O2). A tracer crucial to ocean biogeochemical cycles, O2 plays an active role in chemical processes, marine life, and ecosystems. Recent advances in observation and numerical simulation have introduced opportunities for furthering our understanding of the variability and long-term changes in oceanic O2. This work examines the underlying mechanisms driving O2 variability and long-term changes. It focuses on two distinct time-scales: intra-seasonal variability (i.e., a time scale of less than a month) and centennial changes in O2. The first half of this work analyzes state-of-the-art observations from a profiling float in an investigation of the mechanisms driving the intra-seasonal variability of oceanic O2. Observations from the float show enhanced intra-seasonal variability (i.e., a time scale of about two weeks) that could be driven by isopycnal heaving resulting from internal waves or tidal processes. Observed signals could result from aliased signals from internal waves or tides and should be taken into account in analyses of the growing observational dataset. The methods proposed in this study may be useful for future analyses of high-frequency tracer variability associated with mesoscale and sub-mesoscale processes. Using outputs from state-of-the-art earth system models and a suite of sensitivity experiments based on a general circulation and biogeochemistry ocean model, the second half of this work focuses on investigating mechanisms regulating centennial changes in O2. It explores the aspect of anthropogenic climate change (e.g., changes in the sea surface temperature and wind stress fields) that significantly impacts oceanic O2, focusing specifically on tropical oxygen minimum zones. Results suggest that ocean heating induces a water mass shift, leads to decrease apparent oxygen utilization (AOU) in the tropical thermocline. The AOU decrease compensates the effect of decrease in oxygen saturation due to the ocean warming. Our sensitivity experiments show that both physically (i.e., age) and biologically (i.e., the oxygen utilization rate) driven AOU will contribute almost equally to controlling changes in oceanic O2 in the next century. However, additional sensitivity experiments indicate that physically and biologically driven AOU balance has regional characteristics. We need to address the unanswered question of how varying large-scale oceanic circulations regulate this balance and answer fundamental questions that lead to a more comprehensive understanding of the mechanisms that control the variability and the future evolution of oceanic O2.
8
Stewart, Carol. "Spatial and temporal trends in trace metal deposition in Canterbury, New Zealand." Thesis, University of Canterbury. Chemistry, 1989. http://hdl.handle.net/10092/8433.
Full textAbstract:
Spatial and temporal trends in the deposition of lead, zinc, copper, cadmium and manganese in Canterbury, New Zealand, have been studied. The two main aspects of
this study were an atmospheric deposition monitoring programme set up over the study area to assess present-day spatial trends; and an assessment of the ability of kahikatea tree ring wood to record historical trends in levels of heavy metals in the Christchurch atmosphere. The main instrumental technique used was atomic absorption spectrophotometry, with both flame and graphite furnace atomisation.
To study the dispersal of the metal-enriched aerosol from Christchurch, a network of deposition collectors was established over part of the Canterbury Plains. The main conclusions were that the rates of deposition of lead, zinc, copper and cadmium, but not manganese, showed an approximately exponential decay with distance away from Christchurch, and that the dispersion pattern was dependent upon the prevailing wind direction. It was also found that while rural deposition rates of zinc, copper and cadmium were lower than in other developed countries, the rates of lead deposition were similar to or higher than their overseas counterparts. Considerable seasonal variations in metal deposition rates tended to obscure an expected reduction in lead deposition fluxes following a reduction in the lead content of New Zealand premium grade petrol in July 1986.
Concentrations of lead, zinc, copper, manganese and cadmium were determined in the topsoils at the deposition collection sites, to assess the influence of atmospheric deposition on topsoil composition. Substantial differences, overriding the natural variability in soil composition, were found to exist between urban and rural soils. However, in rural sites, variations in metal deposition rates did not produce effects visible above natural variations, with the possible exception of lead.
To gain an historical perspective on the metal pollution history of Christchurch, the annual rings of kahikatea trees in Riccarton Bush, Christchurch, were analysed for lead, zinc, copper, manganese and cadmium. It was found that kahikatea trees appeared sensitive to environmental levels of these metals, showing accumulations of lead, zinc, copper and cadmium which appeared related to known historical emission trends.
However, manganese concentrations in the ring wood appeared to be controlled by soil factors. A background stand of kahikatea trees showed no trends of increasing metal concentrations.
The use of peat deposits for historical monitoring purposes was also investigated.
It was concluded that the only metals which appeared relatively immobile within the peat profile, hence indicating potential for recording historical trends in deposition fluxes, were copper and cadmium. The other metals appeared to have been mobilised by the severely anaerobic conditions in the bogs, as they were depleted below the permanent water table. However, deposition rates calculated in the surface peat were similar to fluxes measured by a conventional deposition collector at a similar site.
9
Reynolds, Patrisha. "Temporal trends in grave marker attributes an analysis of headstones in Florida." Honors in the Major Thesis, University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/607.
Full textAbstract:
Grave markers reflect a wealth of information and collectively epitomize society's historic, social, and economic patterns over time. Despite an abundance of cemetery research in other parts of the country, little research has been undertaken to evaluate grave marker attributes in Florida. The purpose of this research was to determine how grave marker attributes have changed over time in north-central, central, and southeast Florida. Data were collected from ten cemeteries in five counties in Florida, representing the grave markers of over 1,100 individuals. Data collection involved visiting each cemetery, photographing markers, and cataloging grave marker attributes. Attributes analyzed included marker type, marker material, epitaphs, iconographic images, memorial photographs, footstones, and kerbs. A number of important trends were noted. Marker material exhibited the clearest example of a temporal trend, shifting over time from 73% marble to 73% granite. Marker type varied greatly from upright and flat ground markers to a variety of customized markers and vaults. Cultural differences were also noted with in-ground vaults dominating traditionally black cemeteries. There were clear differences in marker style between affluent and less affluent cemeteries, with numerous hand-cast cement markers observed in less prosperous areas. Furthermore, beginning in the early 1980's there is an increase in customized laser engraved markers. Overall, Florida's cemeteries offer a rich history of the state's mortuary practices and further research should be conducted to preserve this history.B.S.
Bachelors
Sciences
Anthropology
10
Aragon, Jennifer M. "Spatial and temporal trends in water quality in the Alafia River watershed." [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0003163.
Full text
11
VanBuren, John Matthew. "Integrating independent spatio-temporal replications to assess population trends in disease spread." Diss., University of Iowa, 2016. https://ir.uiowa.edu/etd/5669.
Full textAbstract:
Our interest in spatio-temporal models focuses on how a disease spreads within a body region. We use independent replications across individuals to better understand population level dynamics of disease spread. Our Bayesian hierarchical model incorporates independent spatio-temporal datasets to estimate population level parameters. A dimension reduction propagator matrix is used to identify the most variable spatial regions, which are then related to a set of latent variables and covariates. Posterior estimates of parameters allow us to create a predicted estimate of the overall disease evolution process for each individual. In addition, individual level rates of deterioration can be estimated and predictions of future spread are made. The motivating example for this model stems from a study of visual loss in participants with glaucoma. Participants’ vision was recorded across a grid covering the central part of the eye at baseline plus eight follow-up visits every 6 months. We use these spatio-temporal replications of independent participants to determine how human characteristics and demographics collectively affect the spread and progression of glaucoma. Our introduced model is available in the DROIIDS R package. We account for missing data through our model with a Bayesian imputation method.
12
Pal, Shinjini. "Temporal and Spatial Trends in Toxic Cyanobacteria as Identified Through Lake Sediment DNA." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32196.
Full textAbstract:
Cyanobacterial and algal blooms can negatively affect water quality particularly when producing toxins that affect human health and wildlife. While reports of blooms are on the rise globally, their underlying causes remain unclear. The goal of this thesis was to determine temporal changes in cyanobacterial abundance and composition through sediment cores in relation to (1) altered land-use leading to cultural eutrophication and (2) warmer air temperatures that have been recorded in the past few decades. This involved evaluating the use of DNA extracted from lake sediments to quantify cyanobacterial abundance and composition.
Lake sediments preserved under appropriate storage conditions showed the potential to yield high quality DNA for downstream molecular applications. Cyanobacteria, quantified using the 16S rRNA gene, were found to have increased over the last three decades in comparison to historical averages (since the 1850s) both inside and outside a protected area in western Quebec, Canada, in concert with recent regional warming. Copy numbers of 16S rRNA genes specific to cyanobacteria largely correlated to temporal trends in cyanobacterial pigments. Larger percent increases were seen in cyanobacterial genes in recent times compared to changes in the eubacterial glutamine synthetase (glnA) gene. The mcyD gene was quantified as a proxy for microcystin production through sediment cores from two lakes of western Canada. Copy numbers of both mcyD and Microcystis 16S rRNA correlated with chemical analyses of microcystin through time in cores. Cyanobacteria in the more eutrophic of these lakes shifted toward less diverse assemblages and more toxigenic taxa in recent years. Lastly, temporal and spatial changes in cyanobacterial diversity were analyzed through pyrosequencing of cyanobacterial 16S rRNA along a latitudinal transect representative of northern Canada. Significant shifts towards less diverse assemblages were found, composed of potentially toxigenic strains, suggestive of climate warming in northern latitudes. These results support recent reports of increased abundance and geographic expansion of cyanobacteria and point to increases in cyanotoxins in some cases. Using DNA archived in sediments to determine the historical state of cyanobacterial abundance and diversity could help inform lake management policies.
13
Åkesson, Christoffer. "Temporal trends and socioeconomic differences in alcohol use and drunkenness among Swedish adolescents." Thesis, Stockholms universitet, Sociologiska institutionen, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-182633.
Full textAbstract:
This study examined temporal trends and socioeconomic differences in alcohol use and drunkenness among Swedish 15-year-old students between 2001/02 and 2017/18. Data were obtained from the Health Behaviour in School-aged Children (HBSC) study conducted in 2001/02, 2005/06, 2009/10, 2013/14 and 2017/18 (n ≈ 1500/year). Socioeconomic status (SES) was measured using two alternative indicators: educational aspirations and family affluence. Logistic regression models were used to investigate the relationships between drinking measures and SES indicators. The results showed a significant decline in alcohol use and drunkenness among Swedish 15-year-old students from 2001/02 to 2017/18. Educational aspirations almost consistently statistically negatively predicted regular alcohol use and drunkenness. Family affluence only had a weak effect on adolescent drinking behavior with a tendency for less affluent students reporting less alcohol use and drunkenness. Trend analyzes within the subgroups indicated that the downward trend was mirrored in all SES groups, but it was not equally steep in all groups. The decrease was generally weaker among students with lower educational aspirations but stronger among students from less affluent families. This study suggests that different aspects of SES may influence adolescent drinking in opposing directions. In future efforts aimed at reducing alcohol use and drunkenness among adolescents, students with lower educational aspirations should be the target population.
14
Holmström, Katrin. "Analysis of Perfluoroalkyl Acids in Swedish Biota : temporal trends, tissue distribution and toxicity /." Stockholm : Department of Applied Environmental Science (ITM), Stockholm University, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-34181.
Full textAbstract:
Diss. (sammanfattning) Stockholm : Stockholms universitet, 2010.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript. Härtill 4 uppsatser.
15
Burgener, Landon Kelly. "Temporal trends in West Antarctic accumulation rates: evidence from observed and simulated records." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3664.
Full textAbstract:
Reconstructed snow accumulation rate observations from five new firn cores show a statistically significant negative trend in accumulation rates over the past four decades across the central West Antarctic ice sheet. A negative temporal trend in accumulation is unexpected in light of rising surface temperatures and simulations run by GCMs. Both the magnitude of the mean accumulation rates and the range of interannual variability observed in the new records compares favorably to older records, suggesting that the new accumulation rate records may serve as a regional proxy for recent temporal trends in West Antarctic accumulation rates. The observed negative trend is likely the result of Southern Hemisphere high-latitude internal atmospheric dynamics, dominated by changes in the austral fall season. The well-documented positive trend in the Southern Annular Mode causes a low pressure center to form over the Amundsen Sea, which in turn produces lower accumulation rates across the western portion of the West Antarctic ice sheet. The new accumulation rate records are compared to several models/reanalyses to test the skill of simulated accumulation rate predictions. While the models/reanalyses and the new observations agree well in both mean and variability, the simulated records do not capture the full negative trend observed in the reconstructed records.
16
Kraus, Ludwig, Alexander Pabst, Daniela Piontek, Gerrit Gmel, Kevin D. Shield, Hannah Frick, and Jürgen Rehm. "Temporal Changes in Alcohol-Related Morbidity and Mortality in Germany." Karger, 2015. https://tud.qucosa.de/id/qucosa%3A70590.
Full textAbstract:
Aims: Trends in morbidity and mortality, fully or partially attributable to alcohol, for adults aged 18–64 were assessed for Germany. Methods: The underestimation of population exposure was corrected by triangulating survey data with per capita consumption. Alcohol-attributable fractions by sex and two age groups were estimated for major disease categories causally linked to alcohol. Absolute numbers, population rates and proportions relative to all hospitalizations and deaths were calculated. Results: Trends of 100% alcohol-attributable morbidity and mortality over thirteen and eighteen years, respectively, show an increase in rates of hospitalizations and a decrease in mortality rates. Comparisons of alcohol-attributable morbidity including diseases partially caused by alcohol revealed an increase in hospitalization rates between 2006 and 2012. The proportion of alcohol-attributable hospitalizations remained constant. Rates of alcohol-attributable mortality and the proportion among all deaths decreased. Conclusions: The increasing trend in mortality due to alcohol until the mid-1990s has reversed. The constant proportion of all hospitalizations that were attributable to alcohol indicates that factors such as improved treatment and easier health care access may have influenced the general increase in all-cause morbidity. To further reduce alcohol-related mortality, efforts in reducing consumption and increasing treatment utilization are needed.
17
Hammond, Matthew Lee. "Assessing trends and associated uncertainties in global ocean chlorophyll using Bayesian spatio-temporal techniques." Thesis, University of Southampton, 2018. https://eprints.soton.ac.uk/425804/.
Full textAbstract:
Climate change is predicted to affect oceanic phytoplankton abundance with impacts on fisheries and feedbacks on climate. The presence, magnitude, and even direction of long-term trends in phytoplankton abundance over the past few decades is still debated in the literature. The challenges affecting these studies include the low signal-to-noise ratio, the large degree of natural variability, and the shortness of the satellite ocean colour record, which is itself a composite of multiple shorter records. Previous work, however, has typically focused on using linear temporal models to determine the presence of trends in chlorophyll, where each grid cell is considered independently. To improve the assessment of trends a statistical model that explicitly models the relationship between neighbouring grid cells is used. A hierarchical Bayesian spatio-temporal model is fitted to global ocean colour data (1997 – 2013). This results in a notable improvement in accuracy in model fit, an order of magnitude smaller global trend, and larger uncertainty when compared to a model without spatial correlation. To help separate long-term trends from natural variability, trends from coupled physical-biogeochemical models are incorporated in to the model as Bayesian priors. The introduction of priors tends to reduce the magnitude and uncertainty of trend estimates, although the amount is deemed to be not statistically different from zero in any of the regions considered. Finally, the model is used to analyse the effect of taking into account discontinuities on estimated chlorophyll trends. The discontinuities considered are those relating to the launch and termination of individual ocean colour sensors. Considering discontinuities leads to statistically different trends in most regions, which can have a reversed sign as well as increased uncertainty. The improvement in trend estimate accuracy, and the more realistic representation of their uncertainty, emphasizes the solution that spatio-temporal modelling offers for studying global long-term change.
18
Golnick, Phoenix. "Spatial and Temporal Trends in Thermal Structure and Oxygen Depletion in Western Lake Erie." University of Toledo / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1449769244.
Full text
19
Langston, Marvin, Leslie Dennis, Charles Lynch, Denise Roe, and Heidi Brown. "Temporal Trends in Satellite-Derived Erythemal UVB and Implications for Ambient Sun Exposure Assessment." MDPI AG, 2017. http://hdl.handle.net/10150/623250.
Full textAbstract:
Ultraviolet radiation (UVR) has been associated with various health outcomes, including skin cancers, vitamin D insufficiency, and multiple sclerosis. Measurement of UVR has been difficult, traditionally relying on subject recall. We investigated trends in satellite-derived UVB from 1978 to 2014 within the continental United States (US) to inform UVR exposure assessment and determine the potential magnitude of misclassification bias created by ignoring these trends. Monthly UVB data remotely sensed from various NASA satellites were used to investigate changes over time in the United States using linear regression with a harmonic function. Linear regression models for local geographic areas were used to make inferences across the entire study area using a global field significance test. Temporal trends were investigated across all years and separately for each satellite type due to documented differences in UVB estimation. UVB increased from 1978 to 2014 in 48% of local tests. The largest UVB increase was found in Western Nevada (0.145 kJ/m(2) per five-year increment), a total 30-year increase of 0.87 kJ/m(2). This largest change only represented 17% of total ambient exposure for an average January and 2% of an average July in Western Nevada. The observed trends represent cumulative UVB changes of less than a month, which are not relevant when attempting to estimate human exposure. The observation of small trends should be interpreted with caution due to measurement of satellite parameter inputs (ozone and climatological factors) that may impact derived satellite UVR nearly 20% compared to ground level sources. If the observed trends hold, satellite-derived UVB data may reasonably estimate ambient UVB exposures even for outcomes with long latency phases that predate the satellite record.
20
Key, Heyward M. "Temporal and spatial trends in drilling predation on Crepidula in the U.S. coastal plain /." Electronic version (PDF), 2003. http://dl.uncw.edu/etd/2003/keyh/heywardkey.pdf.
Full text
21
Strong, William A. "Temporal water chemistry trends within individual springs and within a population of Florida springs." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0008963.
Full text
22
De, Jesus Alma Lorelei. "Urban ambient particles: Long-term spatio-temporal trends and impacts of different control measures." Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/207786/1/Alma%20Lorelei_De%20Jesus_Thesis.pdf.
Full textAbstract:
This thesis is a quantitative analysis of the spatial and temporal variability as well as trends of the particulate matter concentrations in the ambient urban air. The outcome provided a clear understanding on how the different metrics (particle number, particle mass and oxidative potential) were affected by mitigation measures and other important drivers such as emission sources and meteorological factors.
23
Stukins, Stephen. "Spatial and temporal palynological trends in marginal marine depositional system : Lajas Formation, Neuquén Basin, Argentina." Thesis, University of Aberdeen, 2011. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=167073.
Full textAbstract:
In order to better understand the relationship of tidally dominated depositional environments and their palynological assemblages, the Middle Jurassic sediments of the Lajas Formation, Neuquén Basin were examined. The ambition was to present models and trends which can be used for studies of other such deposits. In order to integrate the palynoassemblages with the environment of deposition, additional granulometric data and nutrient data from XRF analysis were used in combination with the palynology. A new method using correspondence analysis was used for understanding the palaeoecology and floral dynamics. An updated, dynamic model for the Middle Jurassic floral palaeoecology of the Neuquén Basin has been presented and the drivers of floral succession are interpreted as disturbance tolerance and substrate water content. Taphonomic expressions of seral groupings show that later seral stage community palynomorphs are preferentially deposited within or close to distributary systems, whereas earlier seral stage palynomorphs are preferentially deposited in environments of greater accommodation space, such as bayfills. Taphonomic signatures, using palaeoecological groupings provide trends in low (4th/5th) order cycles and lateral variations relating to tidal channels and surrounding bayfill mudstones. A model for 4th/5th order boundaries is also presented using new interpretations of the distribution of pinaceous pollen and microforaminiferal test linings. Using Canonical Correspondence Ananlysis (CCA), a model is presented of depositional environments incorporating palynological data and granulometric proxies for grain size and grain sorting. The relationship between sediment processes in a tidal flat dominated palaeoenvironment and the hydrodynamic properties of some palynomorphs is investigated and presented. The weathering and nutrient status of the substrates throughout the Lajas Formation is presented using XRF proxy data. The proxies are also used with CCA to create nutrient related floral groupings. When plotted stratigraphically, these show cycles of eutrophication and subsequent weathering of the substrates.
24
Hartnett, Justin Joseph. "Spatial and Temporal Trends of Snowfall in Central New York - A Lake Effect Dominated Region." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4502.
Full textAbstract:
Central New York is located in one of the snowiest regions in the United States, with the city of Syracuse, New York the snowiest metropolis in the nation. Snowfall in the region generally begins in mid-November and lasts until late-March. Snow accumulation occurs from a multitude of conditions: frontal systems, mid-latitude cyclones, Nor'easters, and most notably lake-effect storms. Lake effect snowfall (LES) is a difficult parameter to forecast due to the isolated and highly variable nature of the storm. Consequently, studies have attempted to determine changes in snowfall for lake-effect dominated regions. Annual snowfall patterns are of particular concern as seasonal snowfall totals are vital for water resources, winter businesses, agriculture, government and state agencies, and much more.
Through the use of snowfall, temperature, precipitation, and location data from the National Weather Service's Cooperative Observer Program (COOP), spatial and temporal changes in snowfall for Central New York were determined. In order to determine climatic changes in snowfall, statistical analyses were performed (i.e. least squares estimation, correlations, principal component analyses, etc.) and spatial maps analyzed. Once snowfall trends were determined, factors influencing the trends were examined. Long-term snowfall trends for CNY were positive for original stations (~0.46 +/- 0.20 in. yr-1) and homogenously filtered stations (0.23 +/- 0.20 in. yr-1). However, snowfall trends for shorter time-increments within the long-term period were not consistent, as positive, negative, and neutral trends were calculated.
Regional differences in snowfall trends were observed for CNY as typical lake-effect areas (northern counties, the Tug Hill Plateau and the Southern Hills) experienced larger snowfall trends than areas less dominated by LES. Typical lake-effect months (December - February) experienced the greatest snowfall trend in CNY compared to other winter months. The influence of teleconnections on seasonal snowfall in CNY was not pronounced; however, there was a slight significant (5%) correlation (< 0.35) with the Atlantic Multidecadal Oscillation. It was not clear if changes in air temperature or changes in precipitation were the cause of variations in snowfall trends. It was also inconclusive if the elevation or distance from Lake Ontario resulted in increased snowfall trends.
Results from this study will aid in seasonal snowfall forecasts in CNY, which can be used to predict future snowfall. Even though the study area is regionally specific, the methods may be applied to other lake effect dominated areas to determine temporal and spatial variations in snowfall. This study will enhance climatologists and operational forecasters' awareness and understanding of snowfall, especially lake effect snowfall in CNY.
25
Lawrence, Matthew S. "Spatial and Temporal Growth Trends of Poplar Trees Planted for the Purpose of Pah Remediation." Master's thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/37132.
Full textAbstract:
The objective of this study was to investigate the spatial and temporal trends of a phytoremediation system comprised of poplar trees designed to control groundwater flow and remove primarily polycyclic aromatic hydrocarbons (PAHs). Several lab and field studies have demonstrated the success of poplar trees in effectively decreasing concentrations of volatile hydrocarbons, but few have demonstrated effects on PAH concentrations. Thus, the focus of this report will be the response of the poplar trees in relation to hydrophobic, nonvolatile polycyclic aromatic hydrocarbons (acenapthene, acenapthylene, anthracene, chrysene, fluoranthene, naphthalene, phenanthrene, and pyrene) in a shallow, surficial aquifer. This field study was conducted on a 1.7-acre site in Oneida, Tennessee contaminated with creosote that was once used for railroad cross-tie treatment. Spatial analysis was used to divide the site into areas based on contaminant levels and a layer of coal that served as a layer of low permeability at an approximate depth of 2 feet. The semi-impermeable coal layer does have an adverse impact on tree growth, while the contamination does not appear to adversely affect tree growth. The rate of growth is also impacted by the age of the tree at planting where younger trees grow faster than the older trees. A steady decrease in PAH concentrations has occurred at the multi-level samplers surrounded by a root zone that has penetrated the contamination. PAH compounds present at relatively high concentrations in the soil and groundwater do not appear to affect tree growth to a greater or lesser extent than lower PAH concentrations. While further research is required to affirm the positive effects of poplar trees at this site, the tree stand has responded well to the high PAH levels.Master of Science
26
Wierda, Michael Ray. "Using bald eagles to track spatial and temporal trends of contaminants in Michigan's aquatic systems." Connect to this title online, 2009. http://etd.lib.clemson.edu/documents/1252949676/.
Full text
27
Biondi, Franco. "Spatial and temporal reconstruction of twentieth-century growth trends in a naturally-seeded pine forest." Diss., The University of Arizona, 1994. http://hdl.handle.net/10150/186783.
Full textAbstract:
This research uncovered growth trends from 1920 to 1990 in a stand of south-western ponderosa pine (Pinus ponderosa Dougl. ex Laws. var. scopulorum), and investigated the role of climate and competition in shaping the observed trends. I focused on a 800 x 400-m permanent plot maintained by the U.S. Forest Service since 1920 near Flagstaff, Arizona. Temporal growth trends were quantified by size class using a mixed linear model applied to forest inventories, repeated at 10-year intervals. Tree density and stand basal area increased from 1920 to 1990, but growth rates of individual trees declined regardless of size class. Growth of large pines, whose density increased slightly, declined more than that of small pines, whose density almost tripled. I argued that competition for resources reduced growth rates of large trees more than those of small trees. Geostatistical analyses showed that, from 1920 to 1990, stem size was spatially autocorrelated over distances no greater than 30 m, a measure of average patch diameter. Tree density increased by increasing the number of pine groups rather than their horizontal dimension. Increased tree crowding corresponded to lower average, variance, and spatial dependence of individual growth rates. Since growth variation was less related to inter-tree distance at higher tree densities, density-dependent limitation of tree growth did not necessarily correspond to distance-dependent growth rates. No significant trend from 1910 to 1990 was found in climatic variables computed from daily meteorological records. Dendroclimatic analyses showed that climate-tree growth relations had not significantly changed over the twentieth century. Annual growth of both large and small pines was positively related to winter snowfall and to July monsoon rainfall. Periodic basal area increment obtained from dendrochronological data revealed that forest inventories over-estimated growth rates, especially for small pines. On the other hand, tree-ring chronologies developed using different standardization options showed different temporal trends. Repeated forest inventories quantified growth of individual trees and of the entire stand, but integrated bark and wood increment. Dendrochronological data had superior temporal resolution and accuracy, but their limited spatial coverage hindered representation of growth trends for the entire stand.
28
Smith, Thomas Jess II. "Simulation of spatial and temporal trends in hydrodynamic conditions of Upper Mississippi River Pool 8." Thesis, University of Iowa, 2011. https://ir.uiowa.edu/etd/1179.
Full textAbstract:
The Upper Mississippi River is in interest to river managers and biologists' dues to its vast ecosystem and past anthropogenic impacts. In order to help restore the river to its once natural state, river managers and biologists need a strong understanding of the hydrodynamics of the system. A two-dimensional hydrodynamic model was developed in Pool 8 of the Upper Mississippi River and utilized for river management applications. The model was constructed using SMS 10.0 grid generation software and processed with SRH-2D software. SRH-2D used Manning's roughness coefficients to calibrate the model to observed water surface elevation data collected by the USGS. The model was validated to an observed water surface elevation profile and percent discharge through 17 transects within the model. The calibrated and validated model was used for river management and biological applications; hypothetical island, drawdown scenarios, residence time study, and habitat suitability assessment. The results showed that the two-dimensional hydrodynamic model could accurately represent a hypothetical island within the lower pool, simulate drawdown scenarios, develop stream traces for particle tracking and residence time calculation, and the creation of habitat suitability maps based on field data. The completion of these applications with the two-dimensional model shows the efficiently and accuracy of the model, and how two-dimensional numerical models are important tools in bridging the gap between engineers and scientists.
29
Martins, Diogo Miguel dos Santos. "Análise da variabilidade espacial e temporal da precipitação e seca em Portugal." Master's thesis, ISA/UTL, 2012. http://hdl.handle.net/10400.5/5282.
Full textAbstract:
Mestrado em Engenharia do Ambiente - Tecnologias Ambientais - Instituto Superior de AgronomiaThe spatial variability of precipitation and drought are investigated for Portugal using monthly precipitation from 74 stations and minimum and maximum temperature from 27 stations, covering the common period of 1941– 2006. Seasonal precipitation and the corresponding percentages in the year, as well as the precipitation concentration index (PCI), was computed for all 74 stations and then used as an input matrix for an R-mode principal component analysis to identify the precipitation patterns. The standardized precipitation index at 3 and 12 month time scales were computed for all stations, whereas the Palmer Drought Severity Index (PDSI) and the modified PDSI for Mediterranean conditions (MedPDSI) were computed for the stations with temperature data. The spatial patterns of drought over Portugal were identified by applying the S-mode principal component analysis coupled with varimax rotation to the drought indices matrices. The result revealed two distinct sub-regions in the country relative to both precipitation regimes and drought variability. The analysis of time variability of the PC scores of all drought indices allowed verifying that there is no linear trend indicating drought aggravation or decrease. In addition, the analysis shows that results for SPI-3, SPI-12, PDSI and MedPDSI are coherent among them.
30
Sosso-Kolle, Kethy. "Influences of geochemical features of the watershed on methylmercury export in streams: Spatial and temporal trends." Thesis, University of Ottawa (Canada), 2008. http://hdl.handle.net/10393/27732.
Full textAbstract:
Methylmercury (MeHg), the organic form of mercury (Hg), is a neurotoxin that bioaccumulates and magnifies through trophic transfer up the aquatic food chain, moving from the primary producers to the top predators and causing health problems in humans. The purpose of this study was to identify biogeochemical features of the watershed that lead to elevated levels of methyl mercury concentrations in the water in 10 stream sub-catchments. The % wetland, proximity of wetland to the stream and the slope of the sub-catchment, dissolved organic carbon, watercolor, conductivity, pH, sulfate and iron were shown to influence methyl mercury concentrations. Duplicate water samples (1L) were taken on a weekly basis between March 2005 and May 2007 and analyzed for MeHg using the GC-AFS for species detection. Many of these variables are covariables, where the slope of the river drainage basin is of critical importance. Shallow slopes are characterized by wetlands and waterlogged soils that result in watersheds with high DOC concentration, low pH and high iron concentration. In these soils, oxygen is low and iron is reduced to the more soluble form and binds to DOC, giving rise to color. MeHg production in these regions is also favored and MeHg binds to DOC and, thus, export from the watershed into the stream, especially during precipitation events.
31
Ness, Lindsay Anne. "Solute deposition to an upland catchment : spatial patterns, temporal trends and links to stream water chemistry." Thesis, University of East Anglia, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.429683.
Full text
32
Caruthers, Jennet C. "Butterfly community temporal trends and responses to resource availability along a hydrologic gradient of montane meadows." [Ames, Iowa : Iowa State University], 2008.
Find full text
33
梁懷彥 and Wai-yin Albert Leung. "Temporal trends in fish abundance and species composition on an open access artificial reef in Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B31244439.
Full text
34
Bray, Freddie Ian. "Temporal studies of cancer occurrence and applications of the age-period-cohort method to trends in Europe." Thesis, London School of Hygiene and Tropical Medicine (University of London), 2006. http://researchonline.lshtm.ac.uk/834550/.
Full textAbstract:
This thesis examines the utility of temporal studies of cancer in practice, particularly from the perspective of analyses of the three underlying time components, age, period of event and birth cohort. This enquiry encompasses a review of temporal studies and routine data sources, as well as a more critical appraisal of the strategies available for APC analysis and presentation. Specific methods are then applied to trends in cancer incidence and mortality in Europe. The central aims of the thesis are: 1) to comprehensively review the graphical and analytical approaches available, particularly in relation to APC modelling and their usage in current practice; 2) on the basis of 1), to provide broad but sensible guidelines for the analyses of time trends; 3) on the basis of 2), to practically demonstrate the utility of time trends and the APC model; 4) to consider the benefits and limitations of systematic approaches applied to time trend studies. The recommended strategies are used as guiding principles for a detailed analysis of trends in incidence and mortality rates of three cancers (cervix, endometrium and testis) in European populations. The analyses of these neoplasms - purposely selected given their differing temporal and aetiological profile as well as their means of prevention - provides a platform to demonstrate the utility of APC analyses and the specified recommendations in practice. This motivates a discussion of the difficulties inherent in such studies and the consequences of introducing systematic approaches to the analyses of cancer trends.
35
Buckwalter, Joseph Daniel. "Temporal trends in stream-fish distributions, and species traits as invasiveness drivers in New River (USA) tributaries." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/64773.
Full textAbstract:
Biological invasions represent both an urgent conservation problem and an opportunity to advance ecological theory. Development of pertinent research questions and proactive management strategies require knowledge of which introduced species are present and of spatiotemporal trends in the distribution of natives and invaders. In Chapter 2 we developed a quantitative framework to identify spreaders and decliners and estimate invasion chronologies based on a historical fish presence data set for upper and middle New River (UMNR) tributaries. Our framework accounts for spatiotemporal variability in sampling effort by aggregating presences by watershed and expressing range size as a function of the number of watersheds sampled per time period. The majority (55%) of fish species present in the study area were introduced, 51% of which were spreaders. Most spreaders (84%) appeared to be spreading exponentially. The rate of new introductions detected in the study area has slowed since the mid-20th century. Two natives, the mound-spawning bluehead chub Nocomis leptocephalus and its strong nest associate (reproductive mutualist), mountain redbelly dace Chrosomus oreas, were among the most rapid spreaders. Four natives showed evidence of decline. Our framework leverages historical presence data to reconstruct temporal trends in species distributions. It sets the stage for further study of factors driving stream fish invasions and declines in the Appalachian region, and is transferable to diverse taxonomic groups and geographic regions.
Species traits and human activities mediating stream-fish invasions remain poorly understood. In Chapter 3 we modeled the contribution of species traits to invasion success of UMNR tributary fishes during the colonization and spread stages. Biological traits accurately explained colonization and spread success, whereas ecological traits resulted in less accurate models. Colonization success was positively related to time since introduction, benthic feeding, an equilibrium life history, and nest spawning. Successful spread was positively related to winter air temperature in the native range and an equilibrium life history. Variables estimating human use and propagule pressure were non-informative. Traits that influenced invasion success were consistent with the hypothesis that human land-use practices have increased the invasibility of highland watersheds by creating novel conditions suited to lowland and equilibrium invaders.Master of Science
36
Campana, Dalton. "Spatial and Temporal Trends of Trace Elements in Tree Cores Along the Industrial Mahoning River, Northeast Ohio." Youngstown State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1578581272382014.
Full text
37
Dunn, William. "The Auroral Dynamic Duo : spatial, spectral and temporal trends of Jupiter's Northern and Southern X-ray aurorae." Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10049836/.
Full textAbstract:
Jupiter's soft X-ray aurora is concentrated into a bright and dynamic hot spot that is dominated by charge exchange from precipitating high charge-state ions (e.g. Gladstone et al. 2002; Cravens et al. 2003; Elsner et al. 2005). These highly energetic planetary emissions exhibit pulsations over timescales of 10s of minutes. In one observation these pulsations were found to have a very regular periodic pulsation timescale of 45 minutes (Gladstone et al. 2002), but in all subsequent observations the timescale for pulsations was found to be irregular (e.g. Elsner et al. 2005; Branduardi-Raymont et al. 2004). Surrounding this pulsating soft X-ray (< 2 keV) spot, there is a transient auroral oval of hard X-rays (> 2 keV) produced by precipitating electrons that also produce the co-located UV main oval (e.g. Branduardi-Raymont et al. 2007; 2008). The hot spot's magnetic field lines have been suggested to map beyond 30 Jupiter Radii (RJ) to Jupiter's outer magnetosphere and possibly to the Jovian cusp (Pallier et al. 2001). This led Bunce et al. (2004) to propose that Jupiter's X-ray aurora was produced by the influence of dayside reconnection on the current systems at the magnetopause and therefore by the interaction between the solar wind and Jupiter's magnetosphere. In this thesis, we analyse the spatial, spectral and temporal characteristics of Jupiter's X-ray aurora from Chandra and XMM-Newton observation campaigns during 2007, 2011 and 2016. By applying the latest magnetosphere model mapping (Vogt et al. 2011; 2015), we identify that Jupiter's X-ray hot spot may originate from regions along the pre-noon to dusk magnetopause and that the hard X-rays mostly map to the middle magnetosphere, with a slight dawn preference. Our mapping for the hot spot supports previous suggestions that one may expect a solar wind relationship to the emissions. Indeed, we find that during solar wind density enhancements and magnetic field rotations from Interplanetary Coronal Mass Ejections and Corotating Interaction Regions, the Jovian soft X-ray aurora brightens, expands, changes spectral populations and exhibits pulsations on quicker timescales. The hard X-ray aurora also brightens during solar wind compressions but behaves independently of the soft X-ray emissions. During 4 (of 5) observed solar wind compressions, Jupiter's X-ray aurora pulses with a characteristic regular period of 9-13 minute. During solar wind rarefactions, the aurora dims and exhibits longer time-scale pulsations. It is unlikely that the X-ray aurora exists in isolation from other well-studied Jovian auroral wavebands, so we compare the X-ray aurora with radio, IR and UV emissions. We find that non-Io decametric radio emission bursts associated with solar wind compressions (e.g. Hess et al. 2014) occur during X-ray brightening. We note connections between the IR methane layer hot spot and the co-located X-ray hot spot, which may suggest that deeply penetrating ions producing the near-instantaneous X-ray emissions subsequently heat the stratosphere (e.g. through secondary electrons or subsequent photon emissions). We find (for limited available UV comparisons) that when UV dusk polar arcs form, the X-ray hot spot also brightens in a similar region. The normally transient hard X-ray emissions are observed to brighten and occur co-located with UV dusk polar arcs and UV dawn storms. Perhaps our most surprising result is that during some observations the Northern and Southern X-ray hot spots appear to behave independently of one another. Brightening in each hot spot is not correlated and a regular 9-11 minute pulsation period in the South (observed by both Chandra and XMM-Newton) is not also observed in the North, which exhibits more complex irregular pulsations. The two hot spots both map to the noon-magnetopause, but the Northern hot spot also maps along the dusk flank. We propose a few possible explanations: 1. The North and South X-ray hot spots are produced by cusp processes in-line or slightly adapted (non-sub-solar or high-latitude reconnection) from Bunce et al. (2004). 2. In addition to the cusp, the Northern aurora also maps to the dusk sector, which may be associated with tail reconnection. The viewing geometry may prevent this from being observed in the South. The combination of cusp and tail pulsations would produce a more complex lightcurve for the North, while for the South the observed lightcurve would be more regular because it only consists of pulsed transits to the noon magnetopause. This would also exhibit a solar wind relationship. Large-scale tail reconnection can be triggered by magnetospheric compressions. Associated X-ray emissions would therefore 'switch on' with solar wind compressions, causing the observed X-ray brightening and 'expanded hot spot' (actually constituting two sources in the North: tail and cusp). 3. Kelvin Helmholtz Instabilities (KHI) that form in the pre-noon sector (e.g. Ma et al. 2015), and grow along the dusk flank, generate field line resonances. The characteristic period associated with these resonances depends on the field line length. For regions further from noon, this would produce increasingly long timescales, which would explain the more complex Northern lightcurve. This can also generate intermittent reconnection and uni-directional currents (through field line twisting) which may explain differing hemispheric brightnesses. The scales of the KHI depend on the magnetic field strength, density and velocity of the plasmas on either side of the magnetopause and thus vary with solar wind conditions. 4. Alternative wave-particle interactions that propagate to different altitudes for each pole might also be responsible. While deciphering between these mechanisms is beyond the scope of this thesis, we close by proposing future investigations that may identify the mechanism/s responsible for producing the high-energy precipitation that generates Jupiter's enigmatic X-ray aurora.
38
Marra, César Augusto Calembo. "Tendência temporal do índice de massa corporal em alistados do Brasil (1980-2005)." Universidade do Estado do Rio de Janeiro, 2011. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=3140.
Full textAbstract:
Apesar da crescente prevalência da obesidade em países desenvolvidos e em desenvolvimento, há pouca evidência da associação com fatores ambientais. Objetivos: Investigar a evolução temporal do IMC em jovens alistados do sexo masculino de 18 anos no Brasil entre 1980 e 2005; identificar pontos específicos de maior variância na série temporal e comparar pontos específicos no tempo, a evolução temporal do IMC com as mudanças socioeconômicas no Brasil. Métodos: O presente estudo explorou uma série temporal de 26 anos em homens brasileiros que se alistaram no período de 1980 a 2005. A amostra compreendeu cerca de 35-40% de todos os jovens brasileiros de 18 anos de idade. O peso corporal e a estatura foram obtidos no momento do exame médico durante o alistamento militar. Todas as mensurações antropométricas foram realizadas por pessoal especializado e treinado. As prevalências do sobrepeso e da obesidade foram calculadas com intervalos de confiança de 95%. Com a finalidade de testar a presença de heterocedasticidade na série do IMC, realizou-se o teste de Multiplicador de Lagrange (LM). Para os pontos no tempo, com oscilações acima da média do IMC, variáveis dummies foram testadas utilizando-se o modelo ARCH (Autoregressivo de Heterocedasticidade Condicionada), com um nível de significância de p <0,05. Para aqueles pontos no tempo com oscilações acima da média do IMC (anos de 1985, 1994 e 2000), variáveis dummy foram incluídos sob a hipótese foi de que a taxa de crescimento do IMC não fosse a mesma ao longo da série temporal. Para as possíveis explicações para os aumentos bruscos na curva do IMC, foram consideradas as alterações nos principais indicadores econômicos do Brasil (Instituto Brasileiro de Geografia e Estatística e Instituto de Pesquisa Econômica Aplicada). Os fatores econômicos analisados foram: taxa de inflação anual, produção de alimentos, pobreza (%), o consumo de refrigerantes e o rendimento médio anual. Resultados: A prevalência de sobrepeso também passou de 4,5%, em 1980, para 12,5%, em 2005, um aumento de 2,6 vezes, enquanto a prevalência de obesidade aumentou de 0,5%, em 1980, para 1,9%, em 2005, um aumento de quase 300%, mas por comparação internacional estão abaixo da média. Particularmente em 1985-6 e 1994-5, houve um aumento acentuado e significativo do IMC. Em 1985-6, a média do IMC aumentou de 21,4 kg/m2 para 21,5 kg/m2 e, em 1994-5, a média do IMC médio aumentou de 21,7 kg/m2 para 21,9 kg/m2. Nesses dois pontos (1985-1986 e 1994-1995) ocorreram logo após duas grandes mudanças políticas econômicas que aumentaram o poder de compra da população. Em 1985-6, as mudanças foram principalmente relacionadas a fatores econômicos, tais como: a redução do nível de desigualdade social; aumento da renda familiar; redução da pobreza; o controle da inflação; aumento do tempo assistindo televisão e aumento do consumo de alimentos. Em 1994-5, além das mudanças no poder de compra, houve uma modificação na atividade física obrigatória nas escolas. Conclusão: O presente estudo mostrou um aumento abrupto da obesidade na população de homens jovens no Brasil em duas ocasiões durante esta série temporal (anos de 1985-6 e 1994-5), quando uma possível redução no gasto calórico e aumento do consumo de alimentos da população foram observados.Background: Despite the increasing prevalence of obesity in developed and developing countries, there is little evidence for association between obesity and environmental factors. Objective: To investigate the temporal evolution of BMI in young enlisted men of 18 years in Brazil between 1980 and 2005 to identify specific points of greatest variance in time series and compare specific points in time, the temporal evolution of BMI with socioeconomic changes in Brazil. Methods: The present study explores a temporal series of twenty-six national surveys of Brazilian men who enlisted between 1980 and 2005. Each survey comprises a 35-40% of all Brazilian men aged 18 years at the time of examination. Body weight and height were obtained at the time of medical examination. All measurements were performed by previously trained examiners. Prevalence of overweight and obese men was calculated with 95% confidence intervals. Heteroscedasticity in BMI time series was tested using Engles Lagrange-multiplier (LM) test, and analyses were performed using the ARCH (1) model with a level of significance set at p < 0.05. For those points in time with higher oscillations of the mean of BMI (1985, 1994 and 2000), dummy variables were included under the assumption that the growth rate of mean BMI was not the same throughout the period. As possible explanations for these increases in mean BMI, changes in economic indicators were considered (Brazilian Institute of Geography and Statistics; and Institute of Applied Economic Research). The economics factors which have been analyzed were: annual inflation rate, food production, poverty (%), soft drinks consumption and average annual real income. Results: The prevalence of overweight men changed from 4.5% in 1980 to 12.5% in 2005 (2.6 times larger) and the prevalence of obesity increased from 0.5% in 1980 to 1.9% in 2005, an increase of almost 300% during the period, but by international comparison they are below average. Particularly in 1985-6 and 1994-5, there was a sharp and significant increase in BMI. In 1985-6, the BMI mean increased from21.4 kg/m2 to 21.5 kg/m2 and in 1994-5, the BMI mean increased from 21.7 kg/m2 to 21.9 kg/m2. These two points (1985-1986 and 1994-1995) occurred after two major economic policy changes that increased the purchasing power of the population. In 1985-6, the changes were mainly related to economic factors such as: reducing the level of social inequality, increased family income, poverty reduction, inflation control, increased time watching television and increased consumption of foods. In 1994-5, in addition to changes in purchasing power, there was a change in the physical activity mandatory in schools. Conclusion: The present study showed a sharp increase of obesity in the population of young men in Brazil on two occasions during this series (years 1985-6 and 1994-5), when a possible reduction in caloric expenditure and increased food consumption population were observed.
39
Hamblen, Jennifer M. "Spatial And Temporal Trends In Sediment Dynamics And Potential Aerobic Microbial Metabolism, Upper San Pedro River, Southeastern Arizona." Thesis, The University of Arizona, 2003. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_etd_hy0216_sip1_w.pdf&type=application/pdf.
Full text
40
Whelan, Martin Francis. "Temporal trends in exposure of the general population to lead and influences upon the body burden of lead." Thesis, University of Birmingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368429.
Full text
41
Ensor, Breanne Leigh. "Spatial and Temporal Trends in Greenhouse Gas Fluxes from a Temperate Floodplain along a Stream-Riparian-Upland Gradient." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/71424.
Full textAbstract:
Increased floodplain and wetland restoration activity has raised concerns about potential impacts on the release of greenhouse gases (GHGs) to the atmosphere due to restored connectivity between aquatic and terrestrial ecosystems. Research has shown GHG fluxes from hydrologically active landscapes such as floodplains and wetlands vary spatially and temporally in response to primary controls including soil moisture, soil temperature, and available nutrients. In this study, we performed a semimonthly sampling campaign measuring GHG (CO2, CH4, and N2O) fluxes from six locations within a third-order stream floodplain. Site locations were based on dominant landscape positions and hydrologic activity along a topographic gradient including a constructed inset floodplain at the stream margin, the natural levee, an active slough, the general vegetated floodplain, a convergence zone fed by groundwater, and the upland area. Flux measurements were compared to abiotic controls on GHG production to determine the most significant factors affecting GHG flux from the floodplain. We found correlations between CO2 flux and soil temperature, organic matter content, and soil moisture, CH4 flux and pH, bulk density, inundation period length, soil temperature, and organic matter content. But minimal correlations between N2O flux and the measured variables. Spatially, our results demonstrate that constructed inset floodplains have higher global warming potential in the form of CH4 than any other site and for all other GHGs, potentially offsetting the positive benefits incurred by enhanced connectivity. However, at the reach scale, total CO2 flux from the soil remains the greater influence on climate since the area covered by these inset floodplains is comparatively much smaller than the rest of the floodplain.Master of Science
42
Trippel, Nicholas A. "Temporal trends in juvenille Alosa spp. abundance and relation to predator diets at the St. Johns River, Florida." [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0014402.
Full text
43
Waldman, Alanna D. "Spatial and temporal trends in the Xestospongia muta (giant barrel sponge) population on the Southeast Florida Reef Tract." Thesis, NSUWorks, 2019. https://nsuworks.nova.edu/occ_stuetd/514.
Full textAbstract:
Xestospongia muta, the giant barrel sponge, is a key component of coral reef benthic communities in Southeast Florida and the Caribbean. Xestospongia muta increases habitat complexity and stability, and filters large volumes of water, enhancing water quality and facilitating nutrient cycling. Therefore, it is important to investigate trends in the X. muta population on Southeast Florida reefs in response to anthropogenic stressors, changing environmental conditions and acute disturbances and how these events affect its ecological role in the benthic community. This study identified trends in X. muta population density, volume, and size class distribution over time and across reef habitats on the Southeast Florida Reef Tract (SEFRT). Density and volume changes were also investigated following acute physical disturbance caused by Hurricane Irma in September of 2017. Images and demographic data collected at 41 permanent sites from two long-term monitoring projects, The Southeast Florida Coral Reef Evaluation and Monitoring Project (SECREMP) and the Broward County Biological Monitoring Project (BC BIO), were used to evaluate the X. muta population trends. My analysis of the data from 2003 to 2018 shows that Xestospongia muta densities and volume increased over time regionally on the SEFRT and increased on the nearshore, middle, and outer reefs of the SEFRT. Xestospongia muta was found to be more abundant on the SEFRT compared to other locations including the Bahamas, the Florida Keys, Colombia, Belize and Saba. Highest mean density on the SEFRT was 0.35 individuals m-2 ±0.04 SEM, which was higher than the mean densities between 0.21 and 0.29 individuals m-2 at the Caribbean sites previously mentioned. Xestospongia muta individuals were categorized into size classes by volume to investigate density distribution of size classes on the SEFRT. Greater abundances in the smallest of five size classes (≤143.13 cm3) drove the increasing density trends. Despite the increasing trends from 2003 to 2017 with a peak in density and volume in 2017, Hurricane Irma caused a region-wide decline in population density and volume as well as a loss of individuals within the largest size class by volume (>17383.97 cm3). These results indicate that the X. muta population is exhibiting increasing long-term trends on the SEFRT, but also demonstrate that acute physical disturbances have a significant impact on the demographics of the population. Because of this sponge’s multiple roles in the reef communities, these trends have implications for structural complexity, nutrient cycling, water filtration, as well as carbon sequestration on the SEFRT.
44
Hussian, Mohamed. "Monotonic and Semiparametric Regression for the Detection of Trends in Environmental Quality Data." Doctoral thesis, Linköping : Dept. of Mathematics, Univ, 2005. http://www.bibl.liu.se/liupubl/disp/disp2005/stat7s.pdf.
Full text
45
Capelle, David. "Temporal trends and biogeochemical controls on methane and nitrous-oxide distributions in coastal waters of the subarctic Pacific Ocean." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/58843.
Full textAbstract:
This PhD thesis examines the marine cycling of the greenhouse gases methane (CH₄) and nitrous-oxide (N₂O) in coastal British Columbia waters. The primary objectives of the work were to increase spatial and temporal data availability in an under-sampled coastal region, and to examine the processes responsible for CH₄ and N₂O distributions, and their sensitivity to changing environmental conditions (e.g. O₂-availability). Using a novel high-throughput analytical system, based on purge and trap gas chromatography-mass spectrometry (GC-MS), we measured a 6 year time-series of monthly water column CH₄ and N₂O profiles from Saanich Inlet, British Columbia, as well as three years of water column profiles and surface measurements along the West coast of Vancouver Island (WCVI). The physical and biological processes responsible for the observed CH₄ and N₂O distributions were investigated using relationships with ancillary physical data and biological data, including recently available meta-genomic information. The results presented in this thesis document a dominant role for O₂ concentrations in driving spatial and temporal variability in CH₄ and N₂O concentrations over a range of scales. In Saanich Inlet, the seasonal cycle of anoxia and deep water renewal exerts a primary control on water column N₂O and CH₄ accumulation, with additional likely contributions from sedimentary processes and in situ cycling of various nitrogen species and methylated compounds in the upper water column. In both Saanich Inlet and the WCVI, inter-annual variability and longer-term trends are associated with changes in upwelling intensity and El Nino events, and these changes are set against a background of declining O₂ concentrations across the Subarctic Pacific. Results from our work suggest that coastal CH₄ and N₂O concentrations may be responding significantly to these long-term declines in O₂ levels, with significant implications for regional sea-air fluxes of climate-active trace gases.Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate
46
Sanders, Gordon. "Long-term temporal trends of PCBs and PAHs in the environment and their fate and behaviour in lacustrine systems." Thesis, Lancaster University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385671.
Full text
47
Schuster, Jasmin. "Temporal and spatial trends of persistent organic pollutants in air and soil : implications for their sources and environmental cycling." Thesis, Lancaster University, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.618816.
Full textAbstract:
Persistent organic pollutants (POPs) are defined by their characteristic properties in the environment, such as adverse effects on humans and other organisms, a low degradation rate, a potential for bioaccumulation and long range-transport. These properties are the reason that POPs are monitored in remote regions, like the Polar Regions and open oceans, even though they were mostly used in populated areas (urban or rural). A group of POPs was banned under the Stockholm Convention on Persistent Organic Pollutants in 2001 by a number of countries and more chemicals have been added to the list subsequently. To assess the effect of international regulation more information about the long-term fate of these chemicals, the transport processes and the exchange between different environmental media is needed. The first part of this thesis describes long-term trends of POPs such as polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in the environmental compartment air. One study discusses the trends that were observed with passive air samplers in remote locations along a transect across the UK and Norway. The air• concentrations monitored from 1994 to 2008 at 11 sites showed a general decline. While the total air concentrations decreased with increasing latitude, the decline rates did not differ between sampling sites. A second study discusses the trends of PCBs in the UK atmosphere for urban and rural sites. As in the remote areas, a steady decline was observed following first order kinetics. The PCB concentrations at each sampling site were directly proportional to the population density of the area. It was therefore concluded that air concentrations of PCBs are currently still defined by the direct input from primary source emissions and the observed decline mirrors a decline in emission. In order to assess the fate of POPs in other environmental media soil cores were collected following the transect for the passive air data across the UK and Norway. The soil cores were collected at identical locations ten years earlier. A direct comparison of the data between the sampling years proved that the decline in soil is more variable than in air for most monitored POPs. While there were nearly no changes in soil concentrations of organochlorine pesticides, there was a slight decline for PCBs and a strong decline for PBDEs. Changes in the burden, of PCBs per unit soil organic matter between 1998 and 2008 indicate the approach of soil-air equilibrium for the monitored sites. However chiral data and atmospheric data from the regions indicate that the influence of re-volatilization contributed only a minor component of the air burden of PCBs in remote areas of northern Europe. Important tools in monitoring regional and temporal trends of POPs are passive air samplers, which can be deployed at low cost in remote areas. A new type of sampling medium. the sorbent-impregnated polyurethane foam (SIP) disk, was assessed for its applicability for long-term monitoring of PCBs, PBDEs and hexachlorobenzene. Long-term deployment is a necessity for areas with low concentrations. In order to estimate the most precise atmospheric concentrations from the chemicals sequestered on the sampling medium, it would be preferable if the sampler and atmosphere are not in equilibrium and the sampled air volume is therefore directly proportional to the deployment time. It was found that the SIP disk presents a valid alternative to other established passive air sampling media. The last part of the thesis discusses a group of emerging POPs, the perfluorinated compounds (PFCs). PFCs were monitored in a passive air sampling campaign in different Asian countries. Differences were observed in the PFC composition at different sampling sites. These were explained with different usage pattern and regulations in the different countries. Further research is required to gain deeper understanding the transfer mechanism between different environmental compartments for POPs. The application of a model is needed to assess the increasing influence of secondary sources, i.e. revolatilisation from soils on atmospheric concentrations. While long-term studies for emerging compounds already exist, it is necessary to establish similar monitoring campaigns for emerging chemicals.
48
Delnord, Marie. "Understanding geographic and temporal variations in preterm birth rates and trends : an international study in 34 high-income countries." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCB059/document.
Full textAbstract:
La prématurité, définie par une naissance avant 37 semaines d’aménorrhées (SA), est une cause majeur de mortalité et de morbidité infantile. Comparés aux enfants nés à terme, les prématurés font face à des risques importants de troubles moteurs et cognitifs durant l'enfance, ainsi que de maladies chroniques et décès prématurés à l’âge adulte. La prématurité constitue un enjeu important de santé publique et en Europe, les taux varient entre 5 et 10%. Notre objectif pour cette thèse était de mieux comprendre les sources d’hétérogénéité des taux à l’échelle des pays. Dans un premier temps, nous avons effectué une revue exhaustive de la littérature qui montre que les caractéristiques maternelles, les pratiques médicales, et les méthodes d'estimation de l'âge gestationnel ont un impact sur les taux de prématurité. Cependant, ces facteurs n'expliquent pas l’ampleur des différences observées entre les pays. Puis, en utilisant des données sur les femmes enceintes, les nouveau-nés et les mort-nés dans 34 pays à revenus élevés de 1996 à 2010, nous avons établi que: 1) les différences d'enregistrement des naissances dans les pays à revenus élevés ont un impact limité sur les taux, sauf pour les naissances à 22-23 SA, 2) les tendances de PTB dans les pays sont associées à des variations plus importantes dans la distribution des âges gestationnels 3) et enfin, en utilisant les données d'un échantillon représentatif des naissances en France en 2010, qu’il existe des facteurs de risques maternels prénatals et socio-démographiques communs aux naissances avant terme (<37SA) et proche du terme à 37-38 SA. Viser à réduire les facteurs de risques de la naissance proche du terme et de la prématurité dans une approche conjointe pourrait apporter un nouvel élan à la prévention de la prématurité. Comparés aux enfants prématurés, les enfants nés proche du terme sont individuellement moins à risque, mais à l’échelle des pays ces enfants représentent environ une naissance sur quatre et ils contribuent de manière importante au fardeau de morbi-mortalité néonatale et infantile. Au niveau national, élargir les efforts de prévention de la prématurité à cette nouvelle population-cible pourrait avoir un plus grand impact sur la santé publiquePreterm birth (PTB), defined as birth before 37 weeks, is a leading cause of infant mortality and morbidity. Compared to term infants, preterm infants face important risks of motor and cognitive impairments throughout childhood, as well as chronic diseases and premature death later in life. PTB represents a significant public health burden and in Europe, rates range between 5 and 10%. Such wide differences suggest that reductions may be possible, but there are few effective interventions, and these tend to target selected groups of high-risk pregnancies, based on clinical risk factors. Our aim for this thesis was to better appraise sources of population-level PTB rate variations and trends. First, we conducted an exhaustive review of the literature and found that maternal characteristics, reproductive policies, medical practices and methods of gestational age (GA) estimation affected PTB rates, but could not explain observed differences across countries. Next, using population-based data on pregnant women, newborns and stillbirths in 34 high-income countries from 1996 to 2010, we showed that: 1) reporting criteria for births and deaths affected PTB rates at early gestations and PTB rankings, but differences between countries with high and low rates are not just due to artefact 2) PTB trends were associated with broader shifts in countries’ gestational age GA distribution of births, and 3) using data from a representative sample of births in France in 2010, that there were shared maternal prenatal and socio-demographic risk factors for deliveries that did not reach full term, at 39 weeks GA. Our work confirms that recording differences in high-income countries have a limited impact on PTB rate variations. However, a broader focus on earlier delivery, including early term birth at 37-38 weeks, could shed light on the determinants of low PTB rates and provide a useful public health prevention paradigm
49
Bhuriwale, Ritesh K. "Analysis of Temporal Variance of Mercury Wet Deposition at a Rural Ohio River Valley Site." Ohio University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1257881070.
Full text
50
Barrantes, González Melisa. "Estudio prospectivo observacional del uso de tigeciclina: efectividad, factores de riesgo de mortalidad y evolución temporal de consumo y prescripción tras una serie de alertas de seguridad." Doctoral thesis, Universitat Autònoma de Barcelona, 2017. http://hdl.handle.net/10803/454835.
Full textAbstract:
Tigeciclina es el primero de una nueva clase de antibióticos de la familia de las tetraciclinas, denominada glicilciclinas. Posee un amplio espectro de acción que incluye bacterias grampositivas y gramnegativas, tanto aerobias como anaerobias y microorganismos atípicos. Así mismo, es activa frente a un gran número de patógenos multirresistentes.
En abril del año 2006 se aprobó su comercialización en España.
En febrero del 2007 fue incluida en la guía farmacoterapéutica de nuestro hospital.
Posteriormente al inicio de su comercialización, las agencias reguladoras americana (FDA) y europea (EMA) emitieron una serie de alertas de seguridad debido a que se observó un aumento del riesgo de mortalidad en los pacientes tratados con tigeciclina frente a aquéllos tratados con los antibióticos comparadores.
Como resultado se aprobó un nuevo recuadro con advertencia (black box) que se agregó a la ficha técnica de tigeciclina.
En junio de 2011 se implantó en nuestro hospital un PROA que se utiliza mayoritariamente para el seguimiento de los pacientes sometidos a tratamiento con antibióticos con elevado impacto ecológico hospitalario y los de coste elevado
Tigeciclina cuenta con la aprobación/indicación de la FDA para el tratamiento de infecciones de la piel y tejidos blandos complicadas, infecciones intraabdominales complicadas y neumonía adquirida en la comunidad. La EMA autorizó el uso de tigeciclina para el tratamiento de infecciones de piel y partes blandas e infección intraabdominal complicada.
Hipótesis:
En base a los dictámenes emitidos por las diferentes agencias reguladoras sobre el aumento del riesgo de mortalidad asociada a su utilización es de esperar una disminución en la utilización de tigeciclina en la práctica clínica. De ello se deriva la importancia de valorar la efectividad y seguridad de este antibiótico en este ámbito.
Objetivos:
1. Cuantificar la evolución temporal de consumo y prescripción de tigeciclina después de una serie de alertas de las agencias reguladoras y tras la implantación de un programa de optimización de uso de antimicrobianos.
2. Describir las características de los pacientes susceptibles de ser tratados con tigeciclina.
3. Analizar las posibles diferencias de los perfiles de los pacientes que reciben tratamiento con tigeciclina antes y después de la emisión de las alertas por parte de las agencias reguladoras y tras la implantación de un programa informático para la optimización de los tratamientos con antimicrobianos (PROA).
4. Valorar la efectividad de tigeciclina y determinar los factores de riesgo de mortalidad.
Material y método:
Estudio prospectivo observacional en un hospital universitario de tercer nivel, con 450 camas, durante los 6 años siguientes a su introducción en el hospital (1 de febrero del 2007 a 1 de febrero del 2013).
Pacientes incluidos: mayores de 18 años que recibieron al menos una dosis de tigeciclina.
Datos recogidos: variables demográficas, gravedad de los pacientes mediante la puntuación del SAPS II al ingreso en el hospital y al inicio de tigeciclina, tipo de paciente: críticos, quirúrgicos y médicos; características de la infección: foco de infección, comunitarias o nosocomiales; tratamiento con tigeciclina: cumplimiento de la pauta, tipo de tratamiento: empírico o dirigido, de primera elección o de rescate, cumplimiento de las indicaciones establecidas por la EMA, administración de antibióticos previos y concomitantes, aparición de flora emergente, evolución microbiológica y clínica; consumo de DDD/100estancias-día de tigeciclina y número de prescripciones.
Resultados y conclusión:
En la evolución temporal real de consumo de tigeciclina se observó un impacto importante en el consumo de tigeciclina tras las sucesivas alertas e implantación del PROA de manera que hubo una disminución en el consumo de DDD/100e-día de tigeciclina del 35,9% tras la primera alerta de la FDA, con tendencia a la significación estadística, y del 67,3% tras la instauración del PROA, estadísticamente significativo.Tigecycline is the first of a new class of antibiotics within the tetracycline family called glycylcyclines. It has a broad spectrum of action including gram-positive and gram-negative bacteria, both aerobic and anaerobic, and atypical microorganisms. It is also active against a large number of multiresistant pathogens. In April 2006 tigecycline was approved in Spain. In February 2007 it was included in the pharmacotherapeutic guide of our hospital. After its commercialization, the American (FDA) and European (EMA) regulatory agencies issued a series of safety alerts due to an increased risk of mortality in patients treated with tigecycline compared to those treated with antibiotics comparators. As a result, a new “black box” was approved, which was added to the tigecycline drug label. In June 2011, an antibiotic stewardship program (PROA) was implemented in our hospital, to monitor patients on antibiotic treatment with antibacterials with high hospital ecological impact and/or high cost. Tigecycline has the FDA approval / indication for the treatment of complicated skin and soft tissue infections, complicated intra-abdominal infections and community-acquired pneumonia. EMA authorized the use of tigecycline only for the treatment of skin and soft tissue infections and complicated intra-abdominal infection. Hypothesis: Based on the warnings of the different regulatory agencies about the increased risk of death with tigecycline, a decrease of prescriptions of this antibacterial in clinical practice is expected. This denotes the importance of evaluating the effectiveness and safety of this antibiotic in this area. Objectives: 1. Quantify the time course of consumption and prescription of tigecycline after the safety alerts from regulatory agencies and after the implementation of an antimicrobial stewardship program. 2. Describe the characteristics of patients treated with tigecycline. 3. Analyze possible differences in the profiles of patients receiving tigecycline before and after the alerts by regulatory agencies and after the implementation of a PROA. 4. Assess the effectiveness of tigecycline and determine risk factors for mortality. Material and method: An observational prospective study was performed in a 450-bed third-level university hospital during the 6 years following its introduction into the hospital (February 1, 2007 to February 1, 2013). Patients included: older than 18 years receiving at least one dose of tigecycline. Data collected: demographic variables, severity of illness measured by SAPS II score at hospital admission and at the beginning of tigecycline, type of patient: critical, surgical and medical; Infection characteristics: outbreak of infection, community or nosocomial; Treatment with tigecycline: accordance with the guideline, type of treatment: empirical or directed, first choice or rescue, compliance with the indications established by the EMA, administration of previous and concomitant antibiotics, appearance of emergent flora, microbiological and clinical evolution; Consumption of DDD / 100 times-day of tigecycline and number of prescriptions. Results: Time trends of tigecycline consumption assessment indicated a significant impact in the consumption of tigecycline after successive warnings and implantation of the PROA. There was a 35.9% reduction in the consumption of DDD / 100e-day of tigecycline after the first FDA alert, with a tendency to statistical significance, and 67.3% statistically significant decline after the PROA establishment.