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  • 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.
141

Biomassa arbórea nas florestas alagadas ao longo do Rio Branco, Roraima

Hugo Leonardo Sousa Farias 22 August 2014 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / As florestas tropicais amazônicas são um importante reservatório de carbono acima e abaixo do solo. Elas desempenham uma importante função tanto no sequestro do carbono atmosférico quanto no armazenamento desse carbono em forma de biomassa. O objetivo desse trabalho foi quantificar a variação espacial da biomassa arbórea viva e avaliar o efeito de variáveis climáticas e ambientais ao longo de cerca de 400 km de florestas alagadas no médio e baixo rio Branco. Especificamente, foi avaliado o efeito (i) da duração da inundação, (ii) do comprimento da estação seca e (iii) da textura e fertilidade do solo no estoque de biomassa acima do solo. Foram amostrados 2.432 indivíduos com Diâmetro à altura do Peito (DAP) ≥ 10 cm, distribuídos em 54 parcelas compridas (250 metros) e estreitas (4 metros) de 0,1 ha. Para cada indivíduo amostrado, além do DAP, foram determinadas a altura total e a densidade da madeira. A biomassa viva acima do solo das árvores foi estimada através da média de três modelos alométricos que consideram DAP, densidade da madeira e altura das árvores. A biomassa de palmeiras foi estimada com base em um único modelo que considera apenas a altura dos indivíduos. A biomassa variou de 21,5 a 245,15 Mg/ha. Não foi observada relação entre a biomassa e as variáveis climáticas (precipitação média anual e comprimento da estação seca). As variáveis ambientais: solo (% de argila) e a duração da inundação também não explicaram a variação da biomassa arbórea viva acima do solo nas florestas alagadas do rio Branco. Estes resultados representam as primeiras estimativas de biomassa arbórea para as florestas alagadas do rio Branco. A grande variação observada entre as parcelas sugere que eventos estocásticos locais, a estrutura da floresta e a composição florística podem ser mais importantes para explicar a variação da biomassa do que fatores climáticos e características do solo. / Amazonian forests are an important above and belowground carbon reservoir. They play an important role in both the sequestration of atmospheric carbon and storage of carbon as biomass. The aim of this study was to quantify the spatial variation of above ground tree live biomass and evaluate the effects of climatic and environmental predictors along ~400km of flooded forests in the middle and lower rio Branco (Roraima). Specifically, I related plot-based biomass estimates with (i) duration of flooding, (ii) length of the dry season, and (iii) texture and fertility of the soil. A total of 2.432 individuals with diameter at breast height (DBH) ≥ 10 cm where sampled in 54 long (250 meters) and narrow (4 meters) plots of 0.1 hectare. For each individual sampled, were also determined: total tree height and wood density. The above ground live biomass of trees was estimated by the average of three allometric models that consider DBH, wood density, and tree height. Palm biomass was estimated based on a single model that considers only the height of individuals. Biomass estimates presented a 10-fold variation, ranging from 21.5 to 245.15 Mg/ha. No relationship between biomass and climatic variables (mean annual rainfall and length of dry season) were observed. Environmental variables: soil (% clay) and the duration of the flood also did not explain the variation in tree biomass in the flooded forests of the rio Branco. These represent the first tree biomass estimates for the flooded forests of the rio Branco, and the large biomass variation observed in the plots suggest that local stochastic events, forest structure and floristic composition may be more important in explaining biomass variation than climatic and soil factors.
142

Comportamento de nidificação em Polybia platycephala Richards, 1978: dinâmica de temperatura e luminosidade

Detoni, Mateus Fajardo de Freitas Salviato January 2017 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-04-17T18:05:35Z No. of bitstreams: 1 mateusfajardodefreitassalviatodetoni.pdf: 1310680 bytes, checksum: 07d34f3c206819ff6b208c6ab33be11a (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-04-18T13:50:54Z (GMT) No. of bitstreams: 1 mateusfajardodefreitassalviatodetoni.pdf: 1310680 bytes, checksum: 07d34f3c206819ff6b208c6ab33be11a (MD5) / Made available in DSpace on 2017-04-18T13:50:54Z (GMT). No. of bitstreams: 1 mateusfajardodefreitassalviatodetoni.pdf: 1310680 bytes, checksum: 07d34f3c206819ff6b208c6ab33be11a (MD5) Previous issue date: 2017 / Os ninhos de insetos sociais funcionam como a interface entre as colônias e o ambiente, e estudar como os fatores ambientais se relacionam com o comportamento de nidificação é essencial para compreender o sucesso desses animais em colonizar e sobreviver na área urbana. Dessa forma, este trabalho teve como objetivo estudar a relação entre a orientação dos ninhos da vespa social Polybia platycephala em áreas urbanas e a incidência de luz ambiental sobre os mesmos, além de descrever sua dinâmica de temperatura em relação ao microambiente em que estão localizados. Para a orientação e a incidência de luz, 11 ninhos foram selecionados em 2016 na cidade de Juiz de Fora, MG, sendo 11 na estação chuvosa e 11 na seca (n= 22). A orientação dos ninhos foi constatada e a incidência de luz de cada ninho foi verificada ao longo do dia (06:00h – 18:00h). Adicionalmente, seis ninhos tiveram sua orientação experimentalmente invertida e a luminosidade foi acompanhada antes e depois da inversão de forma a verificar o efeito da orientação natural sobre a exposição dos ninhos à luz. Para a dinâmica de temperatura utilizaram-se os mesmos 22 ninhos, e a temperatura dos ninhos e do ambiente foram medidas paralelamente à luminosidade. Para verificar o efeito da atividade das vespas sobre a temperatura da colônia, um ninho abandonado e uma colônia ativa foram acompanhados por 24 horas. Os resultados permitiram-nos concluir que P. platycephala apresenta uma orientação de ninhos fortemente enviesada para leste, aumentando a exposição à luz ambiental no período da manhã; são, no entanto, capazes de modificar esse comportamento para adaptar-se ao seu microambiente para otimizar essa exposição. A temperatura dos ninhos é muito relacionada à ambiente, flutuando paralelamente a esta, o que indica uma grande dependência das colônias do mesmo para sua sobrevivência. De forma geral, constatou-se que P. platycephala possui uma íntima relação com o seu microambiente, o que pode ajudar a explicar seu sucesso em colonizar áreas urbanas, mas também a torna sensível a alterações ambientais e climáticas nas mesmas. / Nests of social insects function as the interface between colonies and the environment, and studying how environmental factors relate to the nesting behavior is essential in order to understand these organisms’ success in settling and surviving in the urban area. On this sense, our work aimed to study the relation between the social wasp Polybia platycephala nest orientation and the incidence of environmental light, aside from describing its temperature dynamics regarding the microenvironment where it is set. In order to study nest orientation and light incidence, 22 nests were chosen in 2016 in the city of Juiz de Fora, MG, being 11 in the rainy season and 11 in the dry (n= 22). Nest orientation was verified and light incidence on each nest was assessed through the day (06:00h - 18:00h). Additionally, six nests had their orientation experimentally inverted and luminosity was assessed before and after the inversion in order to verify the effect of nest orientation on exposure to light. In order to study temperature dynamics, the same 22 nests were used, and the nest and ambient temperatures were assessed in parallel with the luminosity. In order to verify the effect of the wasp activity on colony temperatures, an abandoned nest and an active colony were observed for 24 hours. The results allowed us to conclude that P. platycephala shows nest orientation strongly biased towards east, increasing exposure to light during the morning; colonies are, however, able to perform modifications on this behavior in order to adapt themselves to their microenvironment and optimize this exposure. Nest temperatures are intensely related to the ambient, fluctuating in parallel with it, which indicates a great dependence of the colonies on the environment to assure their survival. Overall, we found that P. platycephala has an intimate relation with its microenvironment, which may help explain its success in settling urban areas, but also makes it sensible to environmental and climatic changes in them.
143

Recent spatiotemporal changes and main determinants of aquatic macrophyte vegetation in large lakes in Finland

Partanen, S. (Sari) 23 October 2007 (has links)
Abstract During the past half century several large lakes in Finland have experienced notable changes in their ecological condition, induced mainly by water level regulation, eutrophication and land use transformation. The objective of this thesis was the quantification of the spatiotemporal changes of aquatic macrophytes in Finland during the second half of the 1900s. Mapped aquatic macrophyte cover from historic (1947–1963) and present day (1996–2000) aerial photographs, additional macrophyte data and several environmental variables were used to identify the main determinants of aquatic macrophyte distribution, abundance and change. Furthermore, factors influencing the littoral paludification process were identified. The study was conducted in 24 boreal lakes (41–1116 km2) with multisource vegetation data. Selected environmental variables of water level regulation, eutrophication and geomorphology were collected and analyzed. More than 402 km of littoral shoreline in historic and present day aerial photographs was analyzed with stereoscopic visual interpretation. A total of 474 habitat level study sites were used to examine the determining environmental factors of occurrence, abundance and change of emergent vegetation. Finally, 289 vegetation transects were performed in order to study the occurrence, types and main determinants of littoral paludification. Water level regulation was found to be the primary factor behind aquatic macrophyte vegetation development at the whole lake level. The major vegetation changes were determined by the mean water level rise or reduction, decreased fluctuation range and reduced spring flood. The vegetation response was less pronounced in a lake with water level regulation similar to natural fluctuation. Eutrophication influenced aquatic macrophytes at the site level. Land use variables of tributary and agriculture, indicating nutrient increment, corresponded positively with vegetation occurrence and abundance. Geomorphology explained vegetation development at the habitat level. Clay and related deposits and the shore slope specified the vegetation occurrence and affected the abundance of vegetation. Water level regulation, eutrophication, clay and shallowness were found to influence paludification. Helophyte species, common reed (Phragmites australis) and water horsetail (Equisetum fluviatile), dominated the emergent vegetation in the studied lakes. / Tiivistelmä Viimeisen puolen vuosisadan aikana suomalaisiin suurjärviin on kohdistunut lukuisia muutoksia, jotka ovat vaikuttaneet järvien ekologiseen tilaan. Muutoksia ovat aiheuttaneet pääasiallisesti vesistöjen säännöstely, rehevöityminen sekä maankäytön muuttuminen. Tämän väitöskirjan tarkoituksena on analysoida noin viimeisten 50 vuoden aikana suomalaisissa suurjärvissä tapahtunutta ranta- ja vesikasvillisuuden pitkäaikaismuutosta. Historiallisilla (1947–1963) ja nykyisillä (1996–2000) ilmakuvilla, muilla kasvillisuusaineistoilla sekä useilla ympäristömuuttujilla tunnistettiin keskeisiä tekijöitä, jotka vaikuttivat kasvillisuuden esiintymiseen, runsauteen ja muutokseen. Tämän lisäksi tutkittiin rantojen pysyvän umpeenkasvun kehitysprosessia. Tutkimusta varten kasvillisuudesta kerättiin monilähdeaineistoa kaikilta Suomen päävaluma-alueilta yhteensä 24 eri järveltä, joiden koko vaihteli 41–1116 km2:n välillä. Tämän lisäksi useita vesistöjen säännöstelyn, rehevöitymisen ja geomorfologian ympäristömuuttujia kerättiin ja analysoitiin. Stereoskooppisella visuaalisella ilmakuvatulkinnalla tutkittiin yli 402 kilometriä rantaviivaa historiallisista ja nykyisistä ilmakuvista. Ilmaversoisen ranta- ja vesikasvillisuuden esiintymistä, runsautta ja historiallista muutosta analysoitiin 474 habitaattitason tutkimuspisteellä. Rantojen pysyvän umpeenkasvun esiintymistä, umpeenkasvun eri tyyppejä ja sitä määrittäviä tekijöitä tutkittiin 289 kasvilinjalla. Tutkimuksen tuloksena havaittiin, että järvitasolla vesistöjen säännöstely oli tärkein kasvillisuuden historialliseen kehitykseen vaikuttava tekijä. Huomattavimmat kasvillisuusmuutokset määräytyivät keskiveden noston, pienentyneen säännöstelyvälin, vähentyneen kevättulvan ja lasketun keskiveden tason seurauksena. Kasvillisuusmuutokset eivät olleet niin selviä, jos säännöstely muistutti luonnontilaista säännöstelyä. Rehevöityminen vaikutti ranta- ja vesikasvillisuuteen paikallisesti. Ravinteisuutta ilmentävät maankäytön muuttujat, ojat sekä maanviljelys, lisäsivät kasvillisuuden esiintymistä ja runsautta. Geomorfologiset tekijät selittivät kasvillisuuden kehitystä habitaattitasolla. Savinen maaperä sekä rannan mataluus lisäsivät vesi- ja rantakasvillisuuden esiintymistä sekä kasvillisuuden runsautta. Vesistöjen säännöstely, rehevöityminen, savinen maaperä sekä rannan mataluus lisäsivät rantojen pysyvää umpeenkasvua. Ilmaversoiset kasvilajit, järviruoko (Phragmites australis) ja järvikorte (Equisetum fluviatile), hallitsivat kasvillisuutta tutkituissa järvissä.
144

Industrial Hygiene Exposure Estimation Accuracy: An Investigation of Micro-Environmental Factors Impacting Exposure

Eturki, Mohamed 01 October 2019 (has links)
No description available.
145

Correlates of Asthma among the Minority Population in South Bronx,New York

Uwanaka, Veronica Chibumma 01 January 2014 (has links)
Asthma among children has become an inherent problem in many communities in the United States, especially among the minority population. The South Bronx has a large minority population and a high prevalence of asthma. However, no study to date has explored the factors associated with this high prevalence rates in this population. Drawing from theories of social ecology and environmental health, the objective of this quantitative cross-sectional study is to investigate the correlates of asthma among children in the South Bronx by studying the sociodemographic and environmental risk factors, including parental occupation; neighborhood and housing characteristics, air quality, and poverty. Study participants included parents of 400 children, aged between 4 and 16 years residing in Districts 9 and 10 in the South Bronx. Descriptive, Chi-square statistics, and logistic regression analysis were used to determine the association between exposure constructs and asthma in children. Hypotheses 2 and 3 examined environmental conditions both inside and outside the homes of study participants and determined one factor, the structure of the home to be significantly associated with asthma, while absence of extractor fan when cooking, showed a strong association. This result suggests that only some of the factors indicating conditions inside the homes have a positive association to asthma. This suggests that asthma is not a combined action of both socioeconomic and environmental factors but a result of conditions in the homes. The implication here is that any intervention to asthma has to start in the homes since most children spend their time indoors. This includes creating awareness to risk factors to help develop community based intervention programs that will help reduce occurrence of asthma.
146

Från ett hem till ett annat : En litteraturöversikt om bakomliggande faktorer till anknytningsproblem hos familjehemsplacerade barn / From one home to another : Underlaying factors to issues in attachment in foster children: A literature review

Bergström, Emelie, Nordmark, Linda January 2023 (has links)
Många svenska barn lever idag i ogynnsamma hemförhållanden. I vissa fall är det bästa för barnet att placeras utanför sin hemmiljö, även om det innebär att barnet separeras från en person de knutit an till. Att separeras från en anknytningsperson kan ge negativa konsekvenser för barnet, det kan till exempel leda till anknytningsproblem. Det har i forskning visat sig att familjehemsplacerade barn i större utsträckning har anknytningsproblem än barn som bor med sina föräldrar. Syftet med denna studie har varit att undersöka vilka faktorer som kan bidra till att familjehemsplacerade barn utvecklar anknytningsproblem. Detta har genomförts som en litteraturöversikt med en innehållsanalys av 15 artiklar som presenterar studier om faktorer som relateras till anknytningsproblem hos familjehemsplacerade barn. Resultatet visar att individrelaterade faktorer så väl som miljörelaterade faktorer kan bidra till att det familjehemsplacerade barnet utvecklar anknytningsproblem. Slutsatsen dras att faktorer hos barnet och faktorer i barnets omgivande miljö är avgörande för att barnet utvecklar anknytningsproblem. / Many children in Sweden are today living in a dysfunctional home environment. In some cases, it is for the child's best interest to be placed out of their home, even if that means to be separated from a person, they have an attachment to. Being separated from an attachment figure can have negative consequences for the child. Research has shown that children placed in foster home, seem to have greater issue in attachment when it compares to that of children who live with their parents. The purpose of this study was to examine factors that can lead to attachment issues in foster children. The chosen method was a literature review including 15 articles that has been analysed through a content analysis. The result of this study shows that individual as well as environmental factors can cause issues in attachmentin foster children.
147

Ammonia as the driving factor for aerobic ammonia oxidizers

Ghimire, Sabita 20 July 2023 (has links)
No description available.
148

INTEGRATED ASSESSMENT OF FREE DRAINING BASE AND SUBBASE MATERIALS UNDER FLEXIBLE PAVEMENT

Rabab'ah, Samer Rateb January 2007 (has links)
No description available.
149

Effects of Environmental Factors on Bighead Carp (Hypophthalmichthys nobilis) Juveniles

Alam, Mohammad Ashraful 01 June 2018 (has links)
No description available.
150

Uncovering the obstacles: creating a typology of contextual factors that affect participation

Kirschner, Leon 17 May 2020 (has links)
Increasingly, disability related literature recognizes the environment as an important factor in the participation in roles and in engagement in activities for individuals with disabilities; which would naturally make the environment an important concern for occupational therapists (Hammel et al., 2015). The language and methods to describe and analyze the characteristics of the environment that support or limit client participation in occupations are not as well developed in occupational therapy (Whiteneck & Djickers, 2009). This is an important gap in our practice that must be addressed. Guided by Person-Environment-Occupation Theory (Baptiste, 2017), this project attempted to address this need by developing a typology of terms for contextual factors that affect participation. It was completed with the belief that providing the terminology will increase the attention provided to these factors in practice. Environmental interventions can be more universal, are often less expensive, and change the focus from the individual’s deficits to how society can be more just and inclusive. We created the typology using a scoping review methodology to identify source literature and by searching through the selected literature for the environmental and contextual terms describing factors that impact participation. The resulting typology is divided into four areas with twelve categories of terms and 54 total terms. It aligns with the International Classification of Function (WHO, 2001) and the performance factors in the Occupational Therapy Practice Framework (AOTA, 2014). The typology is designed and meant for use across OT practice areas, in OT education, research and scholarship. This will require wide spread dissemination. A dissemination plan based on Diffusion of Innovations Theory (Rogers ,2010) starts by refining the typology with the guidance of assessment from stakeholders. After this refinement process, the typology will be introduced via outreach to occupational therapy programs, publications, and conference presentations. Widely used, this typology has the potential to expand the scope of occupational therapy and to make our interventions more effective in improving and increasing participation for more people.

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