• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 171
  • 79
  • 19
  • 15
  • 12
  • 7
  • 3
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 370
  • 370
  • 156
  • 145
  • 40
  • 37
  • 36
  • 32
  • 28
  • 26
  • 26
  • 24
  • 24
  • 21
  • 21
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Rumslig utbredning av tuberkulos : Stockholms kommun år 2002-2011

Stråth, Alexandra January 2012 (has links)
This bachelor thesis is written as a part of the geography program at Stockholm University, Sweden, and the study was conducted from April to June 2012. Tuberculosis (TB) is an airborne disease and one of the most widespread infectious diseases in the world with more than nine million new cases each year (SMI 2012, digital source). The disease is a major source of death and suffering in many places and the number of deaths remains high despite the availability of highly efficacious treatment. To control and prevent further spread of TB, the mapping of the disease spatial distribution is of essential importance. In this study, maps were produced that shows the spatial distribution of TB between the years 2002 to 2011 in the municipality of Stockholm. These maps allow an analysis of the spatial distribution at a local scale over time. The aim of this paper is to study how the spatial distribution of TB has looked like in the municipality of Stockholm the last 10 years and to analyze why the spatial distribution of the disease looked like it did. This study is based on the hypothesis “drift”. The hypothesis imply that individuals with certain conditions for a particular state of health or disease is passed (drift) to a certain location or become concentrated there through various social processes. The processes would therefore lead to fact that specific qualities or health attributes become more common in certain geographical places than others (Schæerström et al, 2011:110). The maps of the disease prevalence between the years 2002-2011 illustrates that TB was more concentrated in specific geographical areas of the municipality of Stockholm. The result of the analyzed factors in the different neighborhood areas in 2002, 2006 and 2010 reveals that there are individuals with certain socio-economic conditions which are largely concentrated in the areas mentioned above. The results provide a basis for an assumption that the cause of the spatial distribution of TB during the studied period largely depends on what the drift hypothesis implies. Drift is therefore a likely contributing factor to the fact that particular characteristics and health manifestations were more common in certain geographical places than others in the municipality of Stockholm between the years 2002-2011.
22

Ecohydrological Conditions Associated With The Distribution And Phenology Of The Pima Pineapple Cactus

Kidder, Amí Lynne January 2015 (has links)
Climate changes in temperature and precipitation are already occurring and are projected to further exhibit increasing temperature and precipitation extremes and increasing variation. Such increased temperature variation and decreased precipitation are likely to have a profound impact on vegetation communities, particularly in regions that are dominated by extreme temperatures and strongly seasonal precipitation events. Both temperature and precipitation are tightly linked to vegetation growth and distribution, and in regions such as the U.S. desert southwest, there are a number of rare and endangered species that have a particularly tight knit relationship with their environment. Here, I examine the relationship between these ecohydrological drivers and a specific, little- researched cactus: the Pima Pineapple Cactus (Coryphantha scheeri var. robustispina). C. scheeri is a small, hemispherical cactus that resides in the Santa Cruz and Altar Valleys of Southern Arizona, and very little is known about the conditions that promote C. scheeri distribution and growth. To provide information that may aide in managing this species, I investigate aspects of the distribution and the phenology of this species. With respect to distribution, I hypothesize that (H1) C. scheeri locations are associated with spatial physical and climatic data within its geographic limits. A framework describing the climatic associations of C. scheeri would enable species managers to take advantage of suitable habitat when opportunities arise. With respect to phenology, within established C. scheeri habitat we lack a clear understanding of the impact ecohydrological factors can have on reproduction and size. Therefore, I also hypothesize (H2) that C. scheeri flowering phenology is triggered by available moisture, which may be in the form of precipitation, humidity, or soil moisture. My results indicate that through the use of the classification tree, C. scheeri habitat is strongly associated with climatic and physical variables at a state-wide scale; these associations indicate large losses of suitable habitat under future projected climate scenarios. Additionally, I find that C. scheeri flowering phenology appears to be associated with precipitation and the resulting increase of soil moisture; the data are also suggestive that bud formation might be associated with water-year growing degree day. Because the results indicate a tight coupling with climatic variables, with most suitable habitat within the current range in Arizona projected to be lost under future climate, I suggest managers may be inclined to increase monitoring C. scheeri in an ecohydrological context relative to the variables identified here and to consider conditions and locations where supplemental watering or microclimate amelioration could be beneficial for the species.
23

Climate change and extension of the Ginkgo biloba L.growing season in Japan

Matsumoto, Kazuho, Ohta, Takeshi, Irasawa, Michiya, Nakamura, Tsutomu 11 1900 (has links)
The definitive version is available at www.blackwell-synergy.com
24

Spatial distribution modeling of Dermacentor variabilis ticks under current and future climate change scenarios

Boorgula, Gunavanthi Devi Yadav January 1900 (has links)
Master of Science / Department of Diagnostic Medicine and Pathobiology / Ram K. Raghavan / Dermacentor variabilis (Say) (Acari: Ixodidae), commonly known as the American dog tick is a medically important tick species in N. America, which has been implicated as a competent vector for several diseases, including tularemia, bovine anaplasmosis and canine tick paralysis. This tick is also the primary suspect for the transmission of Rickettsia rickettsii, the causative agent of Rocky Mountain spotted fever (RMSF). The spatial distribution and geographic extent of D. variabilis territory in N. America is suspected to have changed in the recent times due to natural and anthropogenic, non-stationary forces. A clear understanding of the spatial distribution and environmental factors contributing to the distribution has public health significance, allowing us to make informed management decisions and for setting robust future research goals aimed at understanding vector-biology and disease management. Additionally, ongoing climate-change is expected to alter species spatial distribution and abundance within distribution range. In this research, I studied the current and likely future spatial distribution of D. variabilis ticks in N. America based on two representative concentration pathways, RCP 4.5 and RCP 8.5, representing lower and higher emission scenarios, respectively, under several global circulation models (GCM). The spatial distribution models were constructed using MaxEnt program and BioClim data was used as environmental data for modeling. Best models were selected based on Partial ROC curves, AIC, and omission rates. Median prediction of these models indicate a wider spread of D. variabilis from its currently known extent, and much further spread as a result of climate change. Different environmental variables that significantly influenced current and future D. variabilis distribution included annual mean temperature, mean diurnal range, maximum temperature of the warmest month, annual precipitation, precipitation seasonality, and precipitation of the wettest quarter.
25

Una aproximación a la estructura de las desigualdades territoriales de la población en el Perú a escala provincial / Una aproximación a la estructura de las desigualdades territoriales de la población en el Perú a escala provincial

Paredes, Ana Vargas 10 April 2018 (has links)
The purpose of this paper is to provide an approximate description of the territorial differences of the Peruvian population from a social-demography perspective. The structure of inequalities is searched through factorial analysis, which would let us know a better description of the spatial distribution of these inequalities among provinces. / El propósito de esta investigación es proporcionar una descripción aproximada de las diferencias territoriales, desde una perspectiva sociodemográfica, de la población peruana sobre la base del Censo de Población y Vivienda de 1993. Utilizando el análisis factorial se busca encontrar una estructura subyacente que explique la desigualdad y por tanto conlleve a una mejor descripción de la distribución espacial de estas diferencias entre las provincias.
26

Distribuição georreferenciada da epilepsia em uma cidade de porte médio do interior paulista

Morais, Thiago Lopes Barbosa de January 2016 (has links)
Orientador: José Eduardo Corrente / Resumo: A epilepsia afeta milhares de pessoas mundialmente, se tornando um problema de saúde pública. Tem-se como objetivo deste estudo avaliar a distribuição espacial dos domicílios de pessoas com epilepsia no municipio de São José do Rio Preto, situado no Estado de São Paulo, Brasil, como também verificar sua distribuição de acordo com sexo, tipo de epilepsia, frequência das crises epilépticas e fatores socioeconômicos. Trata-se de um estudo epidemiológico transversal da epilepsia baseado em arquivos de atendimento primário e de registros computadorizados de ambulatório de hospital terceário, sendo a coleta de dados realizada a partir de 1/1/2003 até 31/12/2012. Foram rastreados um total de 136.512 receitas de fármacos antiepiléticos, com 2377 casos confirmados de pessoas com epilepsia. Foi constatado gênero feminino de maior predominância, em maioria adultos, com tipo de crise focal e esporádicas, referente as classes econômicas, as classes C e D concentram-se maior população acometida pela patologia. Foi verificado estatisticamente que a distribuição dos jovens não teve evidência de associação entre as regiões sociodemográficas estudadas, assim como o sexo, tipos, duração e frequência da crise; a evidência de associação foi encontrada entre as faixas etárias e as regiões sociodemográficas, com idosos predominando nas regiões Sul e Central, crianças e adultos na região Norte. Concluiu-se que este estudo foi capaz de evidenciar com clareza de imagens, a distribuição espacial de pe... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Epilepsy affects several thousand people worldwide, becoming a public health problem. This study aims to evaluate the spatial distribution of dwelling for people with epilepsy in São José do Rio Preto, São Paulo, Brazil, as well as verify their distribution according to sex, type of epilepsy, frequency of epileptic seizures and socioeconomic factors. This is an epidemiological study on epilepsy based on primary care and computerized records of a medical outpatient clinic of a tertiary referral hospital. The data collection was performed from January 1, 2003 to December 31, 2012. A total of 136,512 prescriptions of antiepileptic drugs were screened, with 2377 confirmed cases of people with epilepsy. The female gender was found to be the most prominent in most adults with focal and sporadic seizures concerning the economic classes, in which the classes C and D are responsible for the largest population affected by this condition. It was statistically found that the distribution of young people had no evidence of association between the sociodemographic regions studied, as well as sex, types, duration and frequency of the seizures; evidence of association was found between age groups and socio-demographic areas with the elderly predominating in the South and Central regions, children and adults in the North. It was concluded that this study was able to clearly show the spatial distribution of people with epilepsy, corroborating other researches. The findings may help in preventi... (Complete abstract click electronic access below) / Mestre
27

Gradients of fish distribution in reservoirs / Gradients of fish distribution in reservoirs

PRCHALOVÁ, Marie January 2008 (has links)
Patterns of fish spatial distribution were studied in two Czech canyon-shaped reservoirs and in three Dutch basin-shaped reservoirs. Effects of environmental variables like habitat depth, slope, distance from the shore and distance from the dam were evaluated using multivariate statistics. Gillnet selectivity was also studied as fish were sampled using gillnets.
28

AnÃlise espacial dos casos de histoplasmose disseminada associada a AIDS no municÃpio de Fortaleza / Spatial analysis of cases of disseminated histoplasmosis associated with AIDS in Fortaleza

Francisco Gustavo Silveira Correia 31 August 2012 (has links)
A histoplasmose à considerada a micose endÃmica mais comum em seres humanos, com distribuiÃÃo cosmopolita e significativa incidÃncia no Brasil. Nas Ãltimas dÃcadas, Histoplasma capsulatum tem surgido como patÃgeno oportunista em indivÃduos com distÃrbios da imunidade celular, como aqueles em corticoterapia prolongada, transplantados, imunodeprimidos e principalmente que desenvolveram a sÃndrome da imunideficiÃncia adquirida (aids). A literatura dispÃe de poucos inquÃritos sorolÃgicos sobre a prevalÃncia dessa doenÃa no Brasil, dificultando o conhecimento sobre sua distribuiÃÃo. Nesse contexto, o Estado do Cearà tem-se destacado como Ãrea de elevada notificaÃÃo de casos de Histoplasmose Disseminada (HD) associada a aids no paÃs. A utilizaÃÃo de Sistemas de InformaÃÃes GeogrÃficas (SIG) na SaÃde PÃblica tem auxiliado na compreensÃo do processo saÃde-doenÃa em diversas situaÃÃes, como o planejamento e avaliaÃÃo de aÃÃes de saÃde, definiÃÃo de Ãreas de risco para incidÃncia de doenÃas ou anÃlise de dispersÃo espacial de epidemias. O presente estudo propÃe avaliar a distribuiÃÃo espacial dos casos de HD associada a aids no municÃpio de Fortaleza, CearÃ, ocorridos de 1999 a 2007.Dados sÃciodemogrÃficos e clÃnicos foram coletados em questionÃrio semiestruturado a partir de informaÃÃs contidas no registro do ServiÃo de Arquivo MÃdico e EstatÃstica do Hospital SÃo Josà de DoenÃas Infecciosas (SAME/HSJ), efetuando-se em seguida o georreferenciamento e anÃlise estatÃstica espacial dos casos com auxÃlio do software Terraview 4.0.0, utilizando-se os bairros e regionais (divisÃo polÃtico-administrativa da cidade) como unidades de agregaÃÃo. Foram identificados 238 casos de HD/aids, sendo excluÃdos 86 indivÃduos procedentes de outros municÃpios que nÃo Fortaleza. A razÃo entre os sexos masculino e feminino foi de 1,43, a mÃdia de idade foi de 40,3  12,8 anos, o nÃvel de escolaridade mais freqÃente ficou na faixa entre 4 e 7 anos de estudo (34,9%) e a maioria (53,02%) recebia no mÃximo trÃs salÃrios mÃnimos. Houve predomÃnio de desempregados (13,16%, p= 0.003), com a maioria (38,71%) correspondendo a mulheres. Setenta e cinco (64,7%) dos 116 bairros que compreendem o municÃpio de Fortaleza foram citados pelos pacientes como logradouro atual. A relaÃÃo da nuvem de pontos com mapas de indicadores sÃcioambientais demonstrou associaÃÃo com mÃdia e baixa cobertura de esgotamento sanitÃrio e mÃdio e baixo Ãndice de desenvolvimento humano. O Ãndice de domicÃlios particulares permanentes demonstrou que os casos se agruparam em Ãreas com alta densidade de casas. O presente trabalho à o primeiro estudo associando HD/aids e SIG no municÃpio de Fortaleza, permitindo localizar geograficamente o perfil de morbimortalidade por HD/aids na cidade, indicando Ãreas onde investigaÃÃes e intervenÃÃes sobre essas doenÃas devam acontecer. / Histoplasmosis is considered the most common endemic mycosis in humans, with acosmopolitan distribution and significant impact in Brazil. In recent decades, Histoplasma capsulatum has emerged as an opportunistic pathogen in individuals with impaired cellular immunity such as patients on prolonged corticosteroid therapy, transplant recipients, and immune compromised patients who developed acquire dimunideficiÃncia syndrome (AIDS). The published literature has few serological surveys on the prevalence of this disease in Brazil and little is known about its distribution; in this context, the State of Cearà has been identified as an area of high prevalence of cases of disseminated histoplasmosis (DH) associated with AIDS in this country. The use of Geographic Information Systems (GIS) in Public Health has aimed to understand the health-disease process in many situations, such as planning and evaluation of health actions, definition of risk areas for disease incidence or analysis of spatial dispersion epidemics. The goal of this study was to evaluate the spatial distribution of DH associated with AIDS cases from 1999 to 2007 in Fortaleza, CearÃ. The spatial analysis of DH / AIDS cases was based on medical records information obtained from the Medical and Statistics File System of the SÃo Josà Hospital of Infectious Diseases (SAME / HSJ) . Demographic and clinical data were collected in semi-structured questionnaires to characterize the population studied, and in sequence the geo referencing and spatial statistical analysis of cases was performed through the software Terra view 4.0.0, utilizing the districts as the aggregation units. We identified 238 cases of HD / AIDS; 86 individuals were from other municipalities and excluded. The males/females ratio was 1.43, the mean age was 40.3  12.8 years, the education level was more frequent in the range of 4 to 7 years of study (34.9% ) and most (53.02%) received up to 3 minimum wages. There was a predominance of unemployed (13.16%, p = 0.003) and the majority of them (38.71%) was women. Seventy-five (64.7%) of the 116 districts that comprise the city of Fortaleza were cited as home address by the patients. The analysis of Kernel maps with the social-environmental indicators showed an association with a medium and low sanitation coverage and medium and low Human Developing Index. The cases were clustered in areas with high density of houses. This is the first study associating DH / AIDS and GIS in Fortaleza, allowing the geographic localization of morbidity and mortality profile of DH / AIDS in this city, indicating areas where specific investigations and interventions should be carried out.
29

Spatial distribution and abundance of microplastics particles in the bed sediment of Zeekoevlei Lake, Cape Town

Kennedy, Kyle January 2021 (has links)
Magister Philosophiae - MPhil / Microplastics (MPs) are an emerging micro-pollutant that pose a threat to the ecological integrity of freshwater rivers and wetlands. Most previous work on MPs pollution has focused on marine environments. This study aimed to investigate the spatial distribution and abundance of MPs particles in the bed sediment of a freshwater coastal lake in the Zeekoevlei Nature Reserve, Cape Town, which is fed by rivers and stormwater outlets draining a heavily urbanized environment. The first objective was to characterize the spatial distribution of MPs across the lakebed environment, in relation to possible point and non-point sources of contamination.
30

Ectotherm Thermoregulation at Fine Scales: Novel Methods Reveal a Link Between the Spatial Distribution of Temperature and Habitat Quality

Axsom, Ian 01 December 2022 (has links) (PDF)
Investigating ecological questions at the scale of individual organisms is necessary to understand and predict the biological consequences of environmental conditions. For small organisms this can be challenging because we need tools with the appropriate accuracy and resolution to record and quantify their ecological interactions. Unfortunately, many of our existing tools are only appropriate for medium to large organisms or those that are wide ranging, inhibiting our ability to investigate the ecology of small organisms at fine scales. In Chapter 1, I tested a novel workflow for recording animal movements at very fine spatial and temporal scales. The workflow combined direct observation and the mapping of locations onto high-resolution uncrewed aerial vehicle (UAV) imagery loaded on hand-held digital devices. Observers identified landscape features they recognized in the imagery and estimated positions relative to those features. I found this approach was approximately twice as accurate as consumer-grade GPS devices with a mean and median error of 0.75 m and 0.30 m, respectively. I also found that performance varied across landscape features, with accuracy highest in areas that had more visual landmarks for observers to use as reference points. In addition to sub-meter accuracy, this method was cost-effective and practical, requiring no bulky equipment and allowing observers to easily record locations away from their own location. While this workflow could be used to record locations in a variety of situations, it will be most cost-effective when also using high-resolution environmental data from a UAV. In Chapter 2, I used the workflow described in Chapter 1 to investigate blunt-nosed leopard lizard (Gambelia sila) thermoregulation at fine-scales. Recent research has suggested that the spatial distribution of temperatures is important to consider for ectotherm thermoregulation, but this work has been limited to simple artificial environments. My goal was to investigate this idea in a complex natural system for the first time. I tracked lizard movement and body temperatures at a desert site from May to July 2021. I used machine learning to combine high-resolution environmental data from a UAV with microclimate temperature data to create a model of the spatial distribution of environmental temperatures over time. I found that including information about the spatial distribution of temperatures improved the models of lizard thermoregulatory accuracy and movement rate. Because these response variables are important aspects of ectotherm energetics, this suggests that the spatial distribution of temperatures may be an important, but often overlooked, component of habitat quality. Going forward, identifying better methods to quantify the spatial distribution of temperatures would provide insights into the specific responses of ectotherms to different spatial distributions. In this work I used recent technological advances in UAVs to investigate ecological questions at the scale of a small organism. The methods developed here provide insights into the importance of the spatial distribution of temperatures for a small ectotherm. Further efforts to develop, test and utilize tools for fine-scale ecological research will advance our ability to understand species’ interactions with current conditions and predict their responses to future changes.

Page generated in 0.1117 seconds