• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 525
  • 135
  • 119
  • 74
  • 28
  • 22
  • 18
  • 11
  • 9
  • 7
  • 6
  • 5
  • 4
  • 2
  • 2
  • Tagged with
  • 1144
  • 262
  • 185
  • 149
  • 118
  • 115
  • 111
  • 97
  • 93
  • 85
  • 84
  • 82
  • 79
  • 76
  • 75
  • 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.
171

O espaço vertiginoso / O espaço vertiginoso

Alexander Sergio Evaso 08 March 2007 (has links)
A presente dissertação visa estabelecer que a Internet, enquanto técnica participa da constituição territorial, nesse sentido, colabora na regulação da vida humana. Busca-se, neste projeto, compreender as relações entre o desenvolvimento da Internet e seus impactos na organização e ordenação territorial. / This dissertation seeks to establish that the Internet, as a technique, takes part in the territorial constitution, in this sense, collaborating on the regulation of human life. This project will pursue the comprehension of the relationship between the development of the Internet and its impacts on the organization and arrangement of the territory.
172

Seagrass meadows as seascape nurseries for rockfish (Sebastes spp.)

Olson, Angeleen 24 April 2017 (has links)
Nearshore marine habitats provide critical nursery grounds for juvenile fishes, but their functional role requires the consideration of the impacts of spatial connectivity. This thesis examines nursery function in seagrass habitats through a marine landscape (“seascape”) lens, focusing on the spatial interactions between habitats, and their effects on population and trophic dynamics associated with nursery function to rockfish (Sebastes spp.). In the temperate Pacific Ocean, rockfish depend on nearshore habitats after an open-ocean, pelagic larval period. I investigate the role of two important spatial attributes, habitat adjacency and complexity, on rockfish recruitment to seagrass meadows, and the provision of subsidies to rockfish food webs. To test for these effects, underwater visual surveys and collections of young-of-the-year (YOY) Copper Rockfish recruitment (summer 2015) were compared across adjacent seagrass, kelp forest, and sand habitats within a nearshore seascape on the Central Coast of British Columbia. Recruitment was positively influenced by the structural complexity of seagrass and adjacency to kelp forest sites, however a negative interaction between seagrass complexity and kelp forest adjacency suggests that predation modifies Copper Rockfish recruitment densities. In addition, using δ13C and δ15N isotopes to determine the basal contributions to seagrass food webs, kelp-derived nutrients were on average 47% ± 0.4 of YOY Copper Rockfish diets, which was 3x and 67x greater than the contribution of autochthonous seagrass production (seagrass epiphyte and seagrass blades, respectively). YOY Copper Rockfish diets in seagrass adjacent to sand habitats had the greatest amounts of kelp-derived nutrients and harpacticoid copepods, and concurrently had lower body condition compared to rockfish in the seagrass kelp edges and interior, feeding predominantly on seagrass epiphytes and calanoid copepods. This thesis provides further evidence that temperate seagrasses are nurseries for rockfish and that spatial elements of seascapes, including connectivity via habitat adjacency and variability in habitat structure, alter the recruitment and diets of rockfish in seagrass habitats. These seascape nursery effects are important considerations for marine planning, especially given the global decline of nearshore habitats. / Graduate
173

Understanding and sampling spatial ecological process for biodiversity conservation in heterogeneous landscapes

Stewart, Frances Elizabeth Cameron 01 May 2018 (has links)
Landscape change and biodiversity decline is a global problem and has sparked world-wide initiatives promoting biological conservation techniques such as reintroductions, protected area networks, and both preservation and restoration of landscape connectivity. Despite the increasing abundance of such working landscapes (i.e. “human-modified” landscapes), we know relatively little about their ecological mechanics; these landscapes can be vast, encompassing areas too large to obtain high resolution ecological data to test ecological process. To investigate the ecological mechanics of working landscapes, I use a small, tractable, landscape mesocosm situated in east-central Alberta, Canada, The Cooking Lake Moraine (a.k.a. the Beaver Hills Biosphere). The chapters within this dissertation quantify biodiversity across a hierarchy of measurements (from genes to communities) and investigate consistencies in ecological processes generating patterns in these biodiversity measurements across spatial scales. As a result, I investigate both a depth, and breadth, of spatial ecological processes underlying the efficacy of biodiversity conservation techniques in heterogeneous working landscapes. In Chapter I, I explore between-landscape functional connectivity by investigating the genetic contribution of reintroduced individuals to an ostensibly successfully reintroduced population within the mesocosm. I find that contemporary animals are the result of recolonization from adjacent sources rather than putative reintroduction founding individuals, indicating greater mesocosm functional connectivity to adjacent landscapes than previously thought. In Chapter II, I probe within-landscape functional connectivity by quantifying the contribution of protected areas, natural, and anthropogenic landscape features to animal movement across the mesocosm. I find that natural features had the largest effect on animal movements, despite the presence of protected areas. Chapter III investigates protected area network efficacy on biodiversity conservation by quantifying the contribution of protected areas, natural, and anthropogenic landscape features to mammalian functional diversity across multiple spatial scales within the mesocosm. I find that protected areas rarely predict functional diversity across spatial scales; instead natural features positively predict functional diversity at small spatial scales while anthropogenic features are negatively associated with biodiversity at large spatial scales. Finally, Chapter IV ties the previous three chapters together by testing implicit assumptions of the species occurrence data collected in each. I compare GPS collar data (Chapter II) to species occurrence data collected on wildlife cameras (Chapter III) to demonstrate that the magnitude of animal movements better predict species occurrence than the commonly assumed proximity of animal space use. Across chapters, two central themes emerge from this dissertation. First, the importance of natural features at small spatial scales, and anthropogenic features at large spatial scales, within the landscape matrix is predominant in predicting multiple measures of biodiversity. And second, we cannot assume predictable efficacy of conservation strategies or even the ecological process inferred from the data collected to test these strategies. / Graduate
174

Influence of local and landscape factors on distributional dynamics: a species-centred, fitness-based approach

Flesch, Aaron D. 05 July 2017 (has links)
In spatially structured populations, distributional dynamics are driven by the quantity, connectivity and quality of habitat. Because these drivers are rarely measured directly and simultaneously at relevant scales, information on their relative importance remains unclear. I assessed the influence of both direct and indirect measures of local habitat quality, and of landscape habitat amount and connectivity on long-term territory occupancy dynamics of non-migratory pygmy owls. Direct measures of local habitat quality based on territory-specific reproductive output had greater effects on distribution than landscape factors, but only when spatio-temporal fluxes in performance linked to environmental stochasticity and intraspecific competition were considered. When habitat quality was measured indirectly based on habitat structure, however, landscape factors had greater effects. Although all landscape factors were important, measures of landscape connectivity that were uncorrelated with habitat amount and based on attributes of matrix structure and habitat configuration that influence dispersal movements had greater effects than habitat effective area (amount weighted by quality). Moreover, the influence of connectivity (but not habitat effective area) depended on local habitat quality. Such results suggest the relative importance of local habitat quality in driving distribution has been underestimated and that conservation strategies should vary spatially depending on both local and landscape contexts.
175

Characterization of 32 microsatellite loci for the Pacific red snapper, Lutjanus peru, through next generation sequencing

Paz-García, David A., Munguía-Vega, Adrián, Plomozo-Lugo, Tomas, Weaver, Amy Hudson 27 April 2017 (has links)
We developed a set of hypervariable microsatellite markers for the Pacific red snapper (Lutjanus peru), an economically important marine fish for small-scale fisheries in the west coast of Mexico. We performed shotgun genome sequencing with the 454 XL titanium chemistry and used bioinformatic tools to search for perfect microsatellite loci. We selected 66 primer pairs that were synthesized and genotyped in an ABI PRISM 3730XL DNA sequencer in 32 individuals from the Gulf of California. We estimated levels of genetic diversity, deviations from linkage and Hardy-Weinberg equilibrium, estimated the frequency of null alleles and the probability of individual identity for the new markers. We reanalyzed 16 loci in 16 individuals to estimate genotyping error rates. Eighteen loci failed to amplify, 16 loci were discarded due to unspecific amplifications and 32 loci (14 tetranucleotide and 18 dinucleotide) were successfully scored. The average number of alleles per locus was 21 (+/- 6.87, SD) and ranged from 8 to 34. The average observed and expected heterozygosities were 0.787 (+/- 0.144 SD, range 0.250-0.935) and 0.909 (+/- 0.122 SD, range 0.381-0.965), respectively. No significant linkage was detected. Eight loci showed deviations from Hardy-Weinberg equilibrium, and from these, four loci showed moderate null allele frequencies (0.104-0.220). The probability of individual identity for the new loci was 1.46(-62). Genotyping error rates averaged 9.58%. The new markers will be useful to investigate patterns of larval dispersal, metapopulation dynamics, fine-scale genetic structure and diversity aimed to inform the implementation of spatially explicit fisheries management strategies in the Gulf of California.
176

Rozložitelnost grafů na souvislé podgrafy / Decompositions of graphs into connected subgraphs

Musílek, Jan January 2015 (has links)
In 2003 at Eurocomb conference J. Barát and C. Thomassen presented definition and basic results in edge partitioning of graphs. Edge partitioning is basically possibility to cover edges of the graph using connected subgraphs of prescribed size. Graph has edge partitioning property if and only if it can be covered for all prescribed subgraphs sizes. Our work is focused on edge partitioning, in which there are less results known, compared to vertex partitioning. We proof, that edge partitioning is implied by existence of open dominating trail and therefore with edge 4-connectivity. We also define limited version of edge partitioning, spectrum of partitioning and we proof some claims that are true for all graphs. We also explore limited partitioning on some specific classes of graphs.
177

Souvislost a resilience grafů / Souvislost a resilience grafů

Novotná, Jitka January 2015 (has links)
A graph is k-resilient if it is possible to construct local routing tables for each vertex such that we can reach a specified destination vertex from anywhere in the graph. There is a conjecture that k-resilience is equivalent to (k+1)-connectivity. We prove this for 3-edge-connected graphs and 4-edge-connected planar triangulations. In the proof we use independent directed spanning trees. Two spanning trees are independent if they share no common edge with the same direction. For k=3,4 we show that a graph has k independent spanning trees if and only if it is k-edge-connected. We search for the spanning trees constructively through reductions of parts of the graph. Some of these reductions can also be used in a general k- connected case. Powered by TCPDF (www.tcpdf.org)
178

Commuting graphs for elements of order three in finite groups

Nawawi, Athirah Binti January 2013 (has links)
Let G be a finite group and X a subset of G. The commuting graph C(G,X) is the graph whose vertex set is X with two distinct elements of X joined by an edge whenever they commute in the group G. This thesis studies the structure of commuting graphs C(G,X) when G is either a symmetric group Sym(n) or a sporadic group McL, and X a conjugacy class for elements of order three. We describe how this graph can be useful in understanding various aspects of the structure of the group with a particular emphasis on the connectivity of the graph, the properties of the discs around some fixed vertex and the diameter of the graph.
179

Emotional intelligence is associated with connectivity within and between resting state networks

Killgore, William D S, Smith, Ryan, Olson, Elizabeth A, Weber, Mareen, Rauch, Scott L, Nickerson, Lisa D 10 1900 (has links)
Emotional intelligence (EI) is defined as an individual's capacity to accurately perceive, understand, reason about, and regulate emotions, and to apply that information to facilitate thought and achieve goals. Although EI plays an important role in mental health and success in academic, professional and social realms, the neurocircuitry underlying this capacity remains poorly characterized, and no study to date has yet examined the relationship between EI and intrinsic neural network function. Here, in a sample of 54 healthy individuals (28 women, 26 men), we apply independent components analysis (ICA) with dual regression to functional magnetic resonance imaging (fMRI) data acquired while subjects were resting in the scanner to investigate brain circuits (intrinsic resting state networks) whose activity is associated with greater self-reported (i.e. Trait) and objectively measured (i.e. Ability) EI. We show that higher Ability EI, but not Trait EI, is associated with stronger negatively correlated spontaneous fMRI signals between the basal ganglia/limbic network (BGN) and posterior default mode network (DMN), and regions involved in emotional processing and regulation. Importantly, these findings suggest that the functional connectivity within and between intrinsic networks associated with mentation, affective regulation, emotion processing, and reward are strongly related to ability EI.
180

Intracranial Volume Estimation and Graph Theoretical Analysis of Brain Functional Connectivity Networks

Sargolzaei, Saman 25 March 2015 (has links)
Understanding pathways of neurological disorders requires extensive research on both functional and structural characteristics of the brain. This dissertation introduced two interrelated research endeavors, describing (1) a novel integrated approach for constructing functional connectivity networks (FCNs) of brain using non-invasive scalp EEG recordings; and (2) a decision aid for estimating intracranial volume (ICV). The approach in (1) was developed to study the alterations of networks in patients with pediatric epilepsy. Results demonstrated the existence of statistically significant (p

Page generated in 0.0584 seconds