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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.
71

Uso de macroinvertebrados bentônicos na avaliação do impacto antropogênico às nascentes do Parque Estadual do Jaraguá, São Paulo, SP / The use of benthic macroinvertebrates for the assessment of anthropogenic impact on streams of Jaraguá State Park, São Paulo, SP

Rinaldi, Silvana Aparecida 14 December 2007 (has links)
Devido à importância dos macroinvertebrados bentônicos como bioindicadores da qualidade ambiental e às vantagens de seu emprego como tal, estes organismos foram utilizados para avaliar a possível existência de impacto antropogênico às nascentes localizadas no Parque Estadual do Jaraguá (São Paulo, SP). Para isso, selecionaram-se quatro nascentes, em cada uma das quais foram nas quais foram coletadas amostras de água em cada nascente para a análise de coliformes fecais e das concentrações de nitrogênio e fósforo totais. A coleta de macroinvertebrados bentônicos foi realizada, com o auxílio de um delimitador Surber (área de 0,04m2, malha de 500 ?m), em poções e corredeiras da cada nascente. Este trabalho divide-se em dois capítulos. O primeiro capítulo trata da estrutura da comunidade de invertebrados bentônicos nas nascentes do Parque Estadual do Jaraguá e mostra uma diferenciação entre poções e corredeiras, sendo que as famílias Cyclopidae, Talitridae, Leptoceridae, Psychodidae e Stratiomyidae foram exclusivas de poções, enquanto Perlidae e Simuliidae foram exclusivas de corredeiras, sendo que abundância relativa de Chironomidae foi elevada em ambos os habitats. No segundo capítulo, foram testadas onze métricas para a análise da qualidade ambiental das nascentes do Parque Estadual do Jaraguá (São Paulo, SP), das quais apenas quatro (diversidade de Shannon-Wiener, dominância, EPT/Total e IBFM) mostraram-se úteis para a diferenciação das nascentes não impactadas e impactadas. / Due to the importance of benthic macroinvertebrates to assess water quality and the advantages of their utilization as bioindicators, these organisms were employed to assess the possible antropogenic impact in four streams located in Jaraguá State Park (São Paulo, SP). In each stream the benthic macroinvertebrates were collected in 5 pools and 5 riffles with a Surber sampler (0,04m2, 500 ?m mesh size). This study is divided in two chapters. The first compares the benthic macroinvertebrate community structure between pools and riffles. The families Cyclopidae, Talitridae, Leptoceridae, Psychodidae and Stratiomyidae were present exclusively in pools, while Perlidae and Simuliidae were exclusive of riffles. In both habitats, Chironomidae relative abundance was high. In the second chapter, eleven metrics were tested for the analysis of environmental quality of streams. Four of them (Shannon-Wiener diversity, dominance, EPT/Total, and IBMF) showed differences related to the degree of impact anthropogenic on streams and were used to compose a multimetric index
72

Iniciação de tempestades convectivas em um ambiente tropical úmido /

Lima, Maria Andrea, 1952- January 2008 (has links)
Resumo: Para determinar como se inicia a convecção na região sudoeste da Amazônia, foram analisados dados do TRMM/LBA (Tropical Rainfall Measuring Mission / Large-scale Biosphere Atmosphere). A base para determinar onde e quando a convecção iniciou foi o radar banda-S, com polarização dual (S-Pol), do National Center for Atmospheric Research (NCAR). Utilizaram-se, adicionalmente, dados do canal visível do satélite GOES-8 para identificar piscinas frias produzidas pela precipitação convectiva. Essas informações, em conjunto com dados topográficos de alta resolução, foram utilizadas na determinação dos mecanismos possíveis de disparos da convecção. A elevação do terreno na área de estudo varia de 100 a 600m. Este estudo apresenta os resultados de 5 de fevereiro de 1999. Um total de 315 tempestades iniciou-se dentro do raio de 130km do radar S-Pol. Nesse dia, classificado como de fraco regime de monção, a convecção desenvolveu-se em resposta ao ciclo diurno do aquecimento solar. Cúmulos rasos espalhados durante a manhã desenvolveram-se em convecção profunda no início da tarde. As tempestades tiveram início após as 11h, com um pico de iniciação entre 15 e 16h. As causas de início de tempestades foram classificadas em 4 categorias. O modo mais comum de iniciação foi o levantamento forçado por frente de rajada (36%). A categoria, que inclui forçantes topográficas (>300m), sem a influência de nenhum outro mecanismo, é responsável por 21% das iniciações e a colisão de frentes de rajada por 16%. Nos 27% restantes, não foi possível a identificação de nenhum mecanismo. O exame de todos os dias do experimento TRMM/LBA mostrou que o dia estudado em detalhe foi representativo de muitos outros dias. Um modelo conceitual para o início e a evolução de tempestades é apresentado. Esses resultados, que devem ter implicações para outros... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract : Radar and satellite data from the Tropical Rainfall Measuring Mission / Large-scale Biosphere Atmosphere (TRMM/LBA) project have been examined to determine causes for convective storm initiation in the southwest Amazon region. The locations and times of storm initiation were based on the National Center for Atmospheric Research (NCAR) S-band dual-polarization Doppler radar (S-Pol). Both the radar and GOES-8 visible data were used to identify cold pools produced by convective precipitation. This data along with high-resolution topographic data were used to determine possible convective storm triggering mechanisms. The terrain elevation varied from 100 - 600 m. Tropical forests cover the area with numerous clear cut areas used for cattle grazing and farming. This study presents the results from 5 February 1999. A total of 315 storms initiated within 130 km of the S-Pol radar. This day was classified as a weak monsoon regime where convection developed in response to the diurnal cycle of solar heating. Scattered shallow cumulus during the morning developed into deep convection by early afternoon. Storm initiation began about 1100 LST and peaked around 1500-1600 LST. The causes of storm initiation were classified into 4 categories. The most common initiation mechanism was caused by forced lifting by a gust front (36%). Forcing by terrain (>300 m) without any other triggering mechanism accounted for 21% of the initiations and colliding gust fronts 16%. For the remaining 27% a triggering mechanism was not identified. Examination of all days during TRMM/LBA showed that this one detailed study day was representative of many days. A conceptual model of storm initiation and evolution is presented. The results of this study should have implications for other locations when synoptic scale forcing mechanisms are at a minimum... (Complete abstract click electronic access below) / Orientador: João Francisco Escobedo / Coorientador: Maria Assunção Faus da Silva Dias / Banca: Nelson de Jesus Ferreira / Banca: Roberto Vicente Calheiros / Banca: Oswaldo Massambani / Banca: Jonas Teixeira Nery / Doutor
73

Mécanismes de coordination autour des projets de standardisation ICT : quatre articles économétriques sur les patent pools et les consortiums technologiques

Delcamp, Henry 04 November 2011 (has links) (PDF)
Cette thèse s'intéresse à l'impact des mécanismes de coordination créés autour des projets de standardisation technologique sur l'innovation. Nous nous intéressons plus particulièrement aux standards technologiques développés dans les secteurs des technologies de l'information et de la communication (3G...) et à deux types de mécanismes de coordination particuliers que sont les patents pools et les consortiums technologiques. Cette thèse est constituée de quatre articles économétriques analysant l'impact des pools et consortiums sur les incitations à innover et les stratégies d'innovation des entreprises participantes.
74

Ribonucleotide reductase and DNA damage

Håkansson, Pelle January 2006 (has links)
A prerequisite for a multicellular organism to survive is the ability to correctly replicate and repair DNA while minimizing the number of heritable mutations. To achieve this, cells need a balanced supply of deoxyribonucleoside triphosphates (dNTPs), the precursors for DNA synthesis. The rate-limiting step in de novo biosynthesis of dNTPs is catalyzed by the enzyme ribonucleotide reductase (RNR). The classic eukaryotic RNR enzyme consists of a large and a small subunit. Together, these subunits form a heterotetrameric RNR complex. The larger subunit harbours active sites whereas the smaller subunit contains a stable tyrosyl free radical. Both subunits are required for RNR activity. Since failure to correctly regulate de novo dNTP biosynthesis can lead to misincorporation of nucleotides into DNA, genetic abnormalities and cell death, RNR activity is tightly regulated. The regulation of RNR activity involves cell cycle-specific expression and degradation of the RNR proteins, as well as binding of allosteric effectors to the large RNR subunit. In this thesis, in vitro assays based on purified recombinant RNR proteins, in combination with in vivo assays, have been used successfully to study the regulation of RNR activity in response to DNA damage. I present new findings regarding the function of an alternative mammalian RNR small subunit, and on the role of a small RNR inhibitor protein of fission yeast, during normal growth and after DNA damage. I also show conclusively that there are fundamental differences in the regulation of dNTP biosynthesis between the cells of higher and lower eukaryotes after DNA damage.
75

GLOBAL TALENT MANAGEMENT UR EN SVENSK SYNVINKEL : – Med potential och transparens i periferin. Andersson, Tran Le

Andersson, Helene, Tran Le, Linh Chi January 2013 (has links)
Företag blir alltmer multinationella och detta har gjort dem beroende av en mer globaliserad syn på företagsstyrning. Därför fokuserar företag idag på att hitta förmågor och talanger som kan leda under globala förhållanden. Denna studie behandlar ämnet Global Talent Management (GTM), en personalplaneringsprocess som syftar till att skapa en grupp medarbetare med särskild god prestationsförmåga och hög potential, för att vidare utveckla dessa till att förverkliga företagets strategier. Prestationsmätning har använts sedan länge av företag men när det kommer till potential finns svårigheter i att kvantifiera detta då det är något som lätt blir subjektivt. Otydligheten som detta problem ger speglar sig även i hur transparenta företagen är med processerna av GTM i organisationen.Syftet med denna studie blir därför att kartlägga hur svenska företag använder GTM med särskilt fokus på variabeln potential och hur transparenta de är med sitt arbete i organisationen Syftet hoppas infrias genom att studera fyra multinationella företag med rötter inom den svenska servicesektorn. Detta har gjorts genom personintervjuer med medarbetare på respektive HR-avdelning. Studien har även gått djupare inom två av företagen då författarna intervjuat en mellanchef som plockat ut en talang samt talangen själv.Resultatet som fanns var att GTM är en process som skiljer sig från företag till företag men vad som gör det framgångsrikt är en tydlighet i arbete med processerna både angående potential och transparens. Då detta leder till en tydligare koppling till företagets strategier.
76

Innovation et coordination dans les standards NTIC : le rôle des brevets essentiels

Baron, Justus 24 September 2012 (has links) (PDF)
Cette thèse étudie le rôle des brevets essentiels pour la coordination de l'innovation dans les standards des Nouvelles Technologies d'Information et de Communication (NTIC). Les firmes actives dans la standardisation ont réagi au défi de la marée de brevets essentiels en créant des mécanismes innovateurs de coordination, et notamment des consortia informels de standardisation et des pools de brevets. La thèse met en lumière le mécanisme d'appropriation original que représentent les brevets essentiels. Ce mécanisme peut cependant générer des incitations à recourir à des stratégies opportunistes. Les pools de brevets peuvent exacerber ces incitations, mais induisent également une augmentation du nombre de brevets déposés autour des standards technologiques. Les consortia informels ont un effet positif sur le nombre de brevets liés aux standards si les incitations à innover sont insuffisantes. L'effet des consortia est plus faible, voire négatif, si les incitations à innover sont excessives. Les brevets essentiels influencent le progrès technologique des standards, notamment en donnant lieu à un progrès plus continu, consistant dans de nombreuses mises à jour et évitant les remplacements de standards.
77

The demand for gambling: Empirical evidence from state-operated lotteries and football pools in Spain

Pérez Carcedo, Leví 13 January 2010 (has links)
There are several arguments why the economic analysis of gambling seems to be very interesting. Gambling is a very important economic industry from which either local or national governments obtain resources due to some sort of fiscal imposition on gambling participation. On the other hand, the consumption of gambling seems to violate the premises of economic theory (risk aversion, maximizing and rational conduct). The empirical literature on this field has tried to answer several questions that might be summarized as follows: Who does gamble? Why do people gamble? And, how do game features, such as the rules or the prize structure, affect the demand for gambling? This thesis tries to shed more light on the questions identified above, focusing on the particular case of state-operated lotteries and football pools in Spain. Specifically, we are interested in examining what aspects drive gamblers' participation in Spanish lottery markets and spending on lotteries, focusing on network externalities in consumer spending on closely related lottery goods. Next, we study the demand for a particular game, paying attention to the factors that explain why individuals bet, especially, those that refer to the design of the game and the structure of prizes. Finally, the analysis of the main economic determinants of demand for gambling is extended to football pools as a particular form of sports gambling. In addition to these empirical exercises, this study contributes to the economics of gambling by briefly reviewing the theoretical work and empirical highlights from the previous analysis of the demand for lottery.
78

The macroinvertebrate community of vernal pools in southwestern Québec /

Doran, Bruce R. January 1999 (has links)
Temporary snowmelt pool ecosystems in southwestern Quebec were examined with special emphasis on identifying the macrofauna and determining their spatial distribution, as well as ascertaining temporal changes in community composition. 68 taxa were collected from ten snowmelt pools. Major taxa represented were Diptera, Coleoptera, Hemiptera, Trichoptera, Odonata, Ephemeroptera, Anostraca, Isopoda, Amphipoda, Gastropoda and Bivalvia; the insects dominated the communities and the Culicidae (Diptera) was the most abundant taxon collected. The fauna were unevenly distributed both spatially and temporally amongst the pools. The occurrence of taxa was similar in pools in the same geographic location. The habitat characteristics of each pool, coupled with their proximity to a permanent waterbody and their accessibility to organisms, perhaps influenced the distribution of the various taxa. A successional pattern was observed in which filter-feeders and detritivores appeared first, followed by predators. After drought, a similar pattern was seen in pools that were replenished by summer rains, but taxon diversity was lower. In addition, pools with longer hydroperiods harboured more taxa than shorter-lived pools.
79

Diatom communities in New Zealand subalpine mire pools: distribution, ecology and taxonomy of endemic and cosmopolitan taxa

Kilroy, Catherine January 2007 (has links)
Mire pools – shallow water-bodies in peat-forming wetlands – are a characteristic feature of New Zealand’s subalpine and alpine landscapes (>1000 m a.s.l.), yet have been the subject of few biological studies to date, particularly of their algal communities. This research focuses on these subalpine systems, and on their diatom communities. Despite the established paradigm of ubiquitous dispersal in micro-organisms, recent taxonomic studies have confirmed a distinctive endemic component in the freshwater diatom flora of the New Zealand / Tasmania / East Australian region. In this study, I examined benthic diatom communities from >320 freshwater sites throughout New Zealand and showed that over 20% of species may be confined to this region. The endemic diatom species had highest densities in stable, unproductive environments, particularly in high-altitude mire pools and tarns. In most cases, non-endemic taxa coexisted with endemic species. This raised questions about (1) the special characteristics of mire pools and tarns (since endemism might be expected in areas that have unique environmental characteristics), and (2) the mechanisms that have allowed existing endemic taxa to withstand displacement by common cosmopolitan taxa, which, by definition, are successful colonisers. I addressed these questions using two years of data from four subalpine mire pools (Bealey Spur wetland, near Arthur’s Pass, South Island). Physico-chemical data showed that water chemistry of these pools may differ from that of many Northern Hemisphere mire systems with respect to the relationship between pH and dissolved ions (especially calcium). This may be due to a combination of high pH rainfall, high rainfall quantities that limit the acidification effects of humic substances, and possibly vegetation differences. Therefore, some endemic taxa may be confined to these habitats because of the characteristic properties of the pools. I investigated the effects of disturbances in these stable environments. In the largest pool endemic species were shown to decline as wind-induced substrate disturbance increased. Endemic species also declined in two pools following small-scale experimental substrate disturbances. In all cases, non-endemic species remained unchanged. The distinctive species Eunophora cf. oberonica was responsible for much of the observed decline in endemic species abundances, which was evidently due to destruction of their specialised habitat within the cyanobacterial mats that made up the pool substrates. I explained pool-specific responses of diatom communities to disturbances by drawing on recent theory of invasibility as an intrinsic environmental property. I further investigated species coexistence by examining several general patterns of interspecific coexistence described for macroscopic organisms (e.g., abundance – occupancy, abundance – persistence). Patterns in mire-pool diatom communities were generally similar to those in larger organisms, and did not differ with respect to geographical range size (endemics vs. non-endemics), except at the scale of single pools. At this scale, endemic taxa, in particular E. cf. oberonica, can persist as dominant species. All the community analyses were underpinned by detailed taxonomic studies, from which I assessed over 40% of the more common species in the pools to be either endemic or likely to be endemic. Two species occurring in the study area are formally described as new species. Overall, this work highlights the vulnerability of this hidden component of New Zealand’s biodiversity to disturbances and environmental changes.
80

DNA precursor asymmetries, Mismatch Repair and their effect on mutation specificity

Buckland, Robert January 2015 (has links)
In order to build any structure, a good supply of materials, accurate workers and quality control are needed. This is even the case when constructing DNA, the so-called “Code of Life.” For a species to continue to exist, this DNA code must be copied with incredibly high accuracy when each and every cell replicates. In fact, just one mistake in the 12 million bases that comprise the genome of budding yeast, Saccharomyces cerevisiae, can be fatal. DNA is composed of a double strand helix made up of just four different bases repeated millions of times. The building blocks of DNA are the deoxyribonucleotides (dNTPs); dCTP, dTTP, dATP and dGTP. Their production and balance are carefully controlled within each cell, largely by the key enzyme Ribonucleotide Reductase (RNR). Here, we studied how the enzymes that copy DNA, the replicative polymerases α, δ and ε, cope with the effects of an altered dNTP pool balance. An introduced mutation in the allosteric specificity site of RNR in a strain of S. cerevisiae, rnr1-Y285A, leads to elevated dCTP and dTTP levels and has been shown to have a 14-fold increase in mutation rate compared to wild type. To ascertain the full effects of the dNTP pool imbalance upon the replicative polymerases, we disabled one of the major quality control systems in a cell that corrects replication errors, the post-replicative Mismatch Repair system. Using both the CAN1 reporter assay and whole genome sequencing, we found that, despite inherent differences between the polymerases, their replication fidelity was affected very similarly by this dNTP pool imbalance. Hence, the high dCTP and dTTP forced Pol ε and Pol α/δ to make the same mistakes. In addition, the mismatch repair machinery was found to correct replication errors driven by this dNTP pool imbalance with highly variable efficiencies. Another mechanism to protect cells from DNA damage during replication is a checkpoint that can be activated to delay the cell cycle and activate repair mechanisms. In yeast, Mec1 and Rad53 (human ATR and Chk1/Chk2) are two key S-phase checkpoint proteins. They are essential as they are also required for normal DNA replication and dNTP pool regulation. However the reason why they are essential is not well understood. We investigated this by mutating RAD53 and analyzing dNTP pools and gene interactions. We show that Rad53 is essential in S-phase due to its role in regulating basal dNTP levels by action in the Dun1 pathway that regulates RNR and Rad53’s compensatory kinase function if dNTP levels are perturbed. In conclusion we present further evidence of the importance of dNTP pools in the maintenance of genome integrity and shed more light on the complex regulation of dNTP levels.

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