• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 537
  • 403
  • 276
  • 39
  • 33
  • 21
  • 20
  • 20
  • 8
  • 7
  • 6
  • 6
  • 6
  • 5
  • 4
  • Tagged with
  • 1578
  • 303
  • 244
  • 206
  • 156
  • 141
  • 140
  • 125
  • 97
  • 90
  • 89
  • 81
  • 79
  • 74
  • 67
  • 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.
701

Examining the Relationship between Avifauna and Green Roofs in Mississippi's Humid-Subtropical Climate

Lamb, Sara Katherine 14 August 2015 (has links)
Human settlement displaces and fragments natural habitats. Design choices in the landscape directly affect both local diversity and extinction rates. This study seeks to understand how avifauna are responding to this new technology in Mississippi.
702

Predicting the Spatial Distribution of Forest Harvests in Mississippi from Landsat TM Data: Accuracy and Characterization

Jackson, Michael Bryan 30 April 2011 (has links)
Methods are needed to predict the spatial distribution pattern(s) of forest harvests to improve large-scale timber inventories through the incorporation of spatial distribution information. In this study, land cover type change detection methods were carried out using information from 1972 thru 2005 east-central Mississippi Landsat TM data to detect the spatial distribution of clearcut forest harvests. A random pattern was observed for clearcut harvests and this and other statistical data gathered in the study will be integrated into an existing forest inventory and transportation network database. The resulting harvested and forested area predictions generated by the database will assist with determining the sustainability and availability of forest resources for existing and future forest product mills and the creation of transportation networks needed to supply raw materials and distribute end products. Other implications include assessment of the quality and spatial components of wildlife habitat and a tool for forest certification programs.
703

Aquatic Barrier Prioritization in New England Under Climate Change Scenarios Using Fish Habitat Quantity, Thermal Habitat Quality, Aquatic Organism Passage, and Infrastructure Sustainability

Jospe, Alexandra C 01 January 2013 (has links) (PDF)
Improperly designed road-stream crossings can fragment stream networks by restricting or preventing aquatic organism passage. These crossings may also be more vulnerable to high flow events, putting critical human infrastructure at risk. Climate change, which will require access to suitable habitat for species persistence, and is also predicted to increase the frequency and magnitude of extreme floods, underscores the importance of maintaining stream connectivity and resilient infrastructure. Given the large number of road-stream crossings and the expense of replacement, it is increasingly important to prioritize removals and account for the multiple benefits of these management actions. I developed an aquatic barrier prioritization scheme that combines potential habitat gain, stream thermal resilience, aquatic organism passage, and culvert risk of failure. To assess relative thermal resilience, I deployed paired air-water thermographs in several New England watersheds and analyzed relative thermal sensitivity (relationship of water to air temperature) and exposure (duration, frequency, and magnitude of warm stream temperature episodes) among streams. These were combined into a single metric of thermal resilience corresponding with the distance of that stream’s sensitivity and exposure from the watershed median. To test the relationship between risk of failure, culvert dimensions, and stream connectivity, I developed a logistic regression to predict risk of failure using data from two watersheds that experienced extreme flooding from Hurricane Irene (2011). Finally, I applied the resultant prioritization scheme to 66 road-stream crossings in the Westfield River watershed (MA). Thermal habitat quality varied considerably within and among watersheds. Stream sensitivity was generally lower than the widely accepted 0.8 ̊C increase in stream temperature for every 1 ̊C increase in air temperature (Westfield median sensitivity = 0.44), with substantial differences among streams. Exposure also varied widely among streams, indicating that some headwater streams in New England are more thermally resilient than previously thought. Risk of infrastructure failure was predicted with a logistic regression using culvert constriction ratio and predicted aquatic organism passage as predictors (Likelihood ratio test, X2=59.1, df=3, p- value=9.2e-13), indicating that underdesigned culverts were more likely to be barriers to passage and more likely to fail in extreme flow events. To prioritize culverts, this study ultimately used a piecewise approach that identified culverts opening the longest reaches of thermally resilient habitat, and then ranked those culverts by infrastructure replacement need. In the Westfield River, the prioritization clearly identified crossing replacements most likely to yield multiple benefits. The scheme I developed can accommodate changes in the relative weights of the different criteria, which will reflect differences in management and conservation concerns in the confidence of inputs. In conclusion, increasing connectivity by removing barriers may be one of the most effective ways to mitigate the effects of climate change on aquatic systems, but it is important to remove the right barriers.
704

Poly(ADP-ribose) Synthesis as a Function of Growth and DNA Fragmentation

Levi, Viktorya 12 1900 (has links)
This work examines the synthesis of poly(ADP-ribose) in normal and SV40-transformed monolayer cultures of 3T3 cells as a function of growth and DNA fragmentation. A review of the relevant literature is given in the introduction of this work. Poly(ADP-ribose) synthesis has been implicated in transcription, replication, repair, differentiation and regulation of cell growth. The results of this study suggest that poly(ADP-ribose) synthesis is involved in some aspect of cell-growth control and DNA repair.
705

Satellite Dispersion in Narrow Spaces: A New Urban Campus Diagram

Moon, Jiyoung 14 October 2013 (has links)
No description available.
706

Synthesis and Characterization of Arborescent (Dendritic) Polystyrenes Prepared by Raft Polymerization

Heidenreich, Andrew J. 10 August 2011 (has links)
No description available.
707

Novel Strategy for the Synthesis of Allenes.

Kamga, Mark-Henry Mbahmi 19 August 2009 (has links) (PDF)
Allenes are very important chemical reagents in organic synthesis. Due to their high reactivity, they have been extensively used to carry out a variety of unique and effective chemical transformations including but not limited to ionic and free radical additions and transition metal catalyzed cyclizations. As the chemistry of this group of compounds is explored further and their applications expanded there is a need to develop alternative and cost effective methods for their synthesis. Our approach involves the synthesis of allenes from oxa-bicyclo-alkan-2-ones by methyllithium induced Eschenmoser fragmentation of the bicyclotosylhydrazone derivatives.
708

Bioinformatic Solutions to Complex Problems in Mass Spectrometry Based Analysis of Biomolecules

Taylor, Ryan M 01 July 2014 (has links) (PDF)
Biological research has benefitted greatly from the advent of omic methods. For many biomolecules, mass spectrometry (MS) methods are most widely employed due to the sensitivity which allows low quantities of sample and the speed which allows analysis of complex samples. Improvements in instrument and sample preparation techniques create opportunities for large scale experimentation. The complexity and volume of data produced by modern MS-omic instrumentation challenges biological interpretation, while the complexity of the instrumentation, sample noise, and complexity of data analysis present difficulties in maintaining and ensuring data quality, validity, and relevance. We present a corpus of tools which improves quality assurance capabilities of instruments, provides comparison abilities for evaluating data analysis tool performance, distills ideas pertinent in MS analysis into a consistent nomenclature, enhances all lipid analysis by automatic structural classification, implements a rigorous and chemically derived lipid fragmentation prediction tool, introduces custom structural analysis approaches and validation techniques, simplifies protein analysis form SDS-PAGE sample excisions, and implements a robust peak detection algorithm. These contributions provide improved identification of biomolecules, improved quantitation, and improve data quality and algorithm clarity to the MS-omic field.
709

The Role of the Architect: Changes of the Past, Practices of the Present, and Indications of the Future

Jones, Chad B. 19 March 2006 (has links) (PDF)
For centuries the architect was the master builder; the one who was responsible for both the design and the construction of a project with sufficient construction expertise to oversee the project from inception to completion. Eventually, complexity of projects required a higher level of specialization leading to the separation of the designer and the builder. Since that separation, the role of the designer, or architect, has continued to shift and evolve. In recent history, the architect has been the one selected by a building owner, at the inception of the project, as the professional who is able to assist and represent the owner throughout the duration of the project. Today however, the role of the architect is once again shifting and leading the architect in a different direction. Building owners are beginning to approach the builder through a design-build or construction manager delivery method first and relying upon them for the overall project and construction expertise instead of the architect. The architect will continue to carry the responsibility of creating the building's design and producing the construction documents. It is very unlikely that this role will change. Any of its other construction related roles, however, are being assumed by the build team. If the architect remains on its current path, it will continue to become more specialized with design and production and carry less responsibility. While the exact role of the architect of today is unclear and heading in a negative direction, the entire construction process continues to evolve and provide new opportunities. The successful architect to come is going to be the one who looks at ways to reclaim its lost responsibilities, explore new alternative services, and promote a higher level of collaboration with the build team.
710

Habitat Selection and Response to Disturbance by Pygmy Rabbits in Utah

Edgel, Robert John 18 March 2013 (has links) (PDF)
The pygmy rabbit (Brachylagus idahoensis) is a sagebrush (Artemisia sp.) obligate that depends on sagebrush habitats for food and cover throughout its life cycle. Invasive species, frequent fires, overgrazing, conversion of land to agriculture, energy development, and many other factors have contributed to recent declines in both quantity and quality of sagebrush-steppe habitats required by pygmy rabbits. Because of the many threats to these habitats and the believed decline of pygmy rabbit populations, there is a need to further understand habitat requirements for this species and how they respond to disturbance. This study evaluated habitat selection by pygmy rabbits in Utah and assessed response of this small lagomorph to construction of a large-scale pipeline (i.e. Ruby pipeline) in Utah. We collected habitat data across Utah at occupied sites (pygmy rabbit occupied burrows) and compared these data to similar measurements at unoccupied sites (random locations within sagebrush habitat where pygmy rabbits were not observed). Variables such as horizontal obscurity, elevation, percent understory composed of sagebrush and other shrubs, and sagebrush decadence best described between occupied (active burrow) and unoccupied (randomly selected) sites. Occupied sites had greater amounts of horizontal obscurity, were located at higher elevations, had greater percentage of understory comprised of sagebrush and shrubs, and had less decadent sagebrush. When considering habitat alterations or management these variables should be considered to enhance and protect existing habitat for pygmy rabbits. The Ruby pipeline was a large-scale pipeline project that required the removal of vegetation and the excavation of soil in a continuous linear path for the length of the pipeline. The area that was disturbed is referred to as the right of way (ROW). From our assessment of pygmy rabbit response to construction of the Ruby pipeline, we found evidence for habitat loss and fragmentation as a result of this disturbance. The size of pygmy rabbit space-use areas and home ranges decreased post construction, rabbits shifted core-use areas away from the ROW, and there were fewer movements of collared rabbits across the ROW. Mitigation efforts should consider any action which may reduce restoration time and facilitate movements of rabbits across disturbed areas.

Page generated in 0.3498 seconds