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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.
820121

Does Additional Habitat Protection Facilitate the Recovery of Species Protected by the Endangered Species Act?

So, Rachel I. 16 April 2014 (has links)
Earlier studies have found that endangered species recovery is only weakly associated with the tools enabled by the U.S. Endangered Species Act (ESA). With habitat loss often cited as a leading cause of species declines, we tested whether the recovery of ESA-listed species is instead associated with the protection of critical habitat (CH) by protected areas. We tested the relationship for 299 species using recovery indices derived from the biennial status reports to Congress (1990-2010), as well as NatureServe and IUCN population status data. We found no overall relationship between recovery and the extent to which CH is protected. However, restricting the analysis to recovering species, listed species with larger areas of protected (R2 = 0.158) or strictly protected (R2 = 0.194) CH fared better than species with less protected or strictly protected CH areas. Declining species (199 of 273 species studied) fared no better with more protected habitat. We conclude that the abatement of habitat loss alone does not necessarily facilitate recoveries for the majority of ESA-listed species. We also note that the weak relationships we observed in this study may be reflective of poor recovery status estimates.
820122

A Novel Photo-labile Caged Peptide for the Repairment of Spinal Cord Injuries

Lu, Chunyu 16 April 2014 (has links)
Spinal cord injuries (SCI) are characterized by the inability of mature neurons to regenerate or repair by themselves. In an attempt to overcome the SCI, a novel photo-sensitive cyclic Arg-Gly-Asp-Ser (RGDS) peptide was synthesized using solid phase peptide synthesis (SPSS) to control 3T3 fibroblast cell attachment on hyaluronic acid (HA) hydrogel. The circular RGDS peptide was designed using RGDS sequence labeled with Anp group (3-Na-fmoc-amino-3-(2-nitrophenyl) propionic acid) at the N terminus. The peptide was photo-labile cyclic caged to shelter its bioactivity and UV light was used to make the peptide uncaged. Accuracy of the cyclic caged RGDS peptide was confirmed by high-performance liquid chromatography (HPLC) and mass spectrum (MS). The molecular weight of cyclic caged RGDS peptide was confirmed as 881 by matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI) mass spectrum. Stability of the cyclic caged RGDS peptide under various pH conditions was verified by circular dichroism spectroscopy. The bioactivity of cyclic caged and uncaged RGDS peptide was tested by photo-controllable directing cell growth based on cell attachment study, cell counting study, and cell morphology study. Three dimensional model structures of cyclic caged and uncaged RGDS peptides were computed by Hyperchem program. The first order reaction theory of Anp uncaging reaction was confirmed by kinetic study. Bioactivity caging and uncaging property of the peptide was also fully confirmed by cell attachment study. This cyclic caged RGDS peptide would be a promising tool in cell patterning for repairing of SCI.
820123

Calculation and Visualization of Range of Motion of Hip Joint from MRI

Aghayan, Sahar 16 April 2014 (has links)
Femoro-Acetabular Impingement (FAI) is a hip joint disease which affects and impairs the range of hip motion during performing activities of daily living, jogging, walking, or climbing stairs due to the bony abnormalities of the joint. Ballet dancers and athletes (e.g. gymnasts and hockey players) put their hips at the risk of FAI by extremely moving the hip mainly by excessively rotating the joint. In this research, we introduce a visualization system which helps surgeons to analyze the range of hip motions as well as to have a better communication with patients. These goals are achieved by presenting three dimensional (3D) visualizations of motion envelope by examining the maximum possible rotation of the digital hip bones. Our computer simulation system estimates, analyzes and visualizes the maximum hip range of motion (ROM) for the constructed 3D bone models that are extracted from Magnetic Resonance Images (MRI) after segmenting the bones. These tasks are accomplished by first calculating Hip Joint Center (HJC) which is center of rotation of femoral head on the 3D segmented MRI models followed by simulating hip motions with examining impingement between the femur and the acetabulum using our collision detection system. In our collision detection system, surfaces of femoral head and acetabulum bones are sampled in the spherical coordinates based on rasterization and interpolation. Then, the distance between the femoral head and acetabulum are computed to prevent impingement between them. The maximum motion degree of femur bone within depression of acetabulum in every direction during the digital simulation shows the ROMs of the inputted MRI of the hip joint. Six primary plane motions (flexion/extension, abduction/adduction and internal/external rotation) as well as various combinations of these motions (maximum rotation of the hip between every two rotational movements) and successive movements (maximum rotational movement of the hip per another rotational movement) are simulated and analyzed along with 3D visualization of estimated range of these motions. Generally, the ROM differs by some factors such as age, gender, ethnicity, and geographic location. For instance, newborns up to age two have considerably greater motion in hip flexion and hip abduction than adults. Our system by 3D visualization of motion envelope will provide a platform to understand quicker and better the effect of bony morphology of the hip joint on the possible ROM. We also examine the long-standing question about moving center of rotation related to ROM. We found out the ROM becomes bigger especially when the center moves outward to the direction of acetabulum axis. This thesis does not consider the effect of muscle and other surrounding connective tissue on the hip ROM since they can be altered significantly by physical training to show the potential of maximum ROM. For example a ballerina has a bigger ROM leading a bigger motion envelope compared with non-dancers. Hence we visualize the range of joint motions and their envelopes that are obtained from the osseous anatomy of the hip joint. The osseous anatomy of the joint is the most fundamental and permanent factor of ROM which indicates the maximum motion that the joint can achieve if the muscle and other connective tissues are perfectly trained.
820124

A Resource-Constrained Coverage Protocol Over Urban VANETs

Cheng, Huang 16 April 2014 (has links)
Vehicular ad hoc networks have emerged as a promising area of research in academic fields. However, it presents a challenge to design a realistic coverage protocol for ve- hicular networks, due to the service requirements, assorted mobility patterns, resource constraints and irregularity of the service area. It is also a challenge to meet a high quality of coverage with a tight deployment budget. In order to resolve these problems, this thesis proposes a resource-constrained coverage protocol with statistical analysis, which aims to consider the application demands, mobility patterns of vehicles, resource limitations, and geometrical attributes of road networks. We study two types of resource-constrained coverage: the continuous coverage model and the sparse coverage model. We then reduce each model to a Knapsack Constrained Steiner Tree problem and a Maximum Coverage Problem, respectively. Since the two reduced problems are NP-hard, we resolve each of them with the Lagrangian Decompo- sition approach and greedy algorithm. By taking the dimensions of road segments into account, our coverage protocol provides a buffering operation scheme to suit different types of road topology. By discovering hotspots from the historical trace files, the pro- posed protocol is able to depict the mobility patterns and to discover the most valuable regions of a road system. To solve the problems of resource constraint, we provide two variants of continuous coverage and sparse coverage by taking budget constraint and quality constraint into consideration. The comparison with other mature algorithms verifies that our coverage protocol is reliable, and suitable for urban vehicular networks.
820125

Reconstruction of Complete Head Models with Consistent Parameterization

Niloofar, Aghayan 16 April 2014 (has links)
This thesis introduces an efficient and robust approach for 3D reconstruction of complete head models with consistent parameterization and personalized shapes from several possible inputs. The system input consists of Cyberware laser-scanned data where we perform scanning task as well as publically available face data where (i) facial expression may or may not exist and (ii) only partial information of head may exist, for instance only front face part without back part of the head. Our method starts with a surface reconstruction approach to either transfer point clouds to a mesh structure or to fill missing points on a triangular mesh. Then, it is followed by a registration process which unifies the representation of all meshes. Afterward, a photo-cloning method is used to extract an adequate set of features in a semi-automatic way on snapshots taken from front and left views of provided range data. We modify Radial Basis Functions (RBFs) deformation so that it would be based on not only distance, but also regional information. Using feature point sets and modified RBFs deformation, a generic mesh can be manipulated in a way that closed eyes and mouth movements like separating upper lip and lower lip can be properly handled. In other word, such mesh modification method makes construction of various facial expressions possible. Moreover, new functions are added where a generic model can be manipulated based on feature point sets to consequently recover missing parts such as ears, back of the head and neck in the input face. After feature-based deformation using modified radial basis functions, a fine mesh modification method based on model points follows to extract the fine details from the available range data. Then, some post refinement procedures employing RBFs deformation and averaging neighboring points are carried out to make the surface of reconstructed 3D head smoother and uniform. Due to existence of flaws and defects on the mesh surface such as flipped triangles, self-intersections or degenerate faces, an automatic repairing approach is leveraged to clean up the entire surface of the mesh. The experiments which are performed on various models show that our method is robust and efficient in terms of accurate full head reconstruction from input data and execution time, respectively. In our method, it is also aimed to use minimum user interaction as much as possible.
820126

Management of City Traffic, Using Wireless Sensor Networks with Dynamic Model

Rahman, Mustazibur 16 April 2014 (has links)
Road network of a region is of a paramount importance in the overall development. Management of road traffic is a key factor for the city authority and reducing the road traffic congestion is a significant challenge in this perspective. In this thesis, a Wireless Sensor Network (WSN) based road-traffic monitoring scheme with dynamic mathematical traffic model is presented that will not necessarily include all adjacent intersections of a block; rather the important major intersections of a city. The objective of this scheme is to reduce the congestion by re-routing the vehicles to better performing road-segments by informing the down-stream drivers through broadcasting the congestion information in a dedicated radio channel. The dynamic model can provide with the instantaneous status of the traffic of the road-network. The scheme is a WSN based multi-hop relay network with hierarchical architecture and composed of ordinary nodes, Cluster-Head nodes, Base Stations, Gateway nodes and Monitoring and Control Centers (MCC) etc. Through collecting the traffic information, MCC will check the congestion status and in defining the congestion, threshold factors have been used in this model. For the congested situation of a road-segment, a cost function has been defined as a performance indicator and estimated using the weight factors (importance) of these selected intersections. This thesis considered a traffic network with twelve major intersections of a city with four major directions. Traffic arrivals in these intersections are assumed to follow Poisson distribution. Model was simulated in Matlab with traffic generated through Poisson Random Number Generator and cost function was estimated for the congestion status of the road-segments over a simulation period of 1440 minutes starting from midnight. For optimization purpose we adopted two different approaches; in the first approach, performance of the scheme was evaluated for all threshold factor values iteratively one at a time, applying a threshold factor value to define threshold capacities of all the road segments; traffic was generated and relative cost has been estimated following the model specifications with the purpose of congestion avoidance. In the second approach, different values of threshold factor have been used for different road segments for determining the optimum set-up, and exhaustive search technique has been applied with a smaller configuration in order to keep computations reachable. Simulation results show the capacity of this scheme to improve the traffic performance by reducing the congestion level with low congestion costs.
820127

Behavioural Studies and Computational Models Exploring Visual Properties that Lead to the First Floral Contact by Bumblebees

Orbán, Levente L. 16 April 2014 (has links)
This dissertation explored the way in which bumblebees' visual system helps them discover their first flower. Previous studies found bees have unlearned preferences for parts of a flower, such as its colour and shape. The first study pitted two variables against each other: pattern type: sunburst or bull's eye, versus the location of the pattern: shapes appeared peripherally or centrally. We observed free-flying bees in a flight cage using Radio-Frequency Identification (RFID) tracking. The results show two distinct behavioural preferences: Pattern type predicts landing: bees prefer radial over concentric patterns, regardless of whether the radial pattern is on the perimeter or near the centre of the flower. Pattern location predicts exploration: bees were more likely to explore the inside of artificial flowers if the shapes were displayed near the centre of the flower, regardless of whether the pattern was radial or concentric. As part of the second component, we implemented a mathematical model aimed at explaining how bees come to prefer radial patterns, leafy backgrounds and symmetry. The model was based on unsupervised neural networks used to describe cognitive mechanisms. The results captured with the results of multiple behavioural experiments. The model suggests that bees choose computationally "cheaper" stimuli, those that contain less information. The third study tested the computational load hypothesis generated by the artificial neural networks. Visual properties of symmetry, and spatial frequency were tested. Studying free-flying bees in a flight cage using motion-sensitive video recordings, we found that bees preferred 4-axis symmetrical patterns in both low and high frequency displays.
820128

Geochemical Surface Expression of the Phoenix and Millennium Uranium Deposits, Athabasca Basin, Saskatchewan

Power, Michael James 16 April 2014 (has links)
The geochemistry of surface media above two known U deposits were examined to observe any possible dispersion products could be detected from them, and based on these findings, improved geochemical exploration techniques are proposed to reduce cost of finding undiscovered U resources. This study examined the materials overlying the Phoenix deposits, which have indicated resources of approximately 58.2 million lbs U3O8 grading 15 wt% that lie at 400 m depth below surface at the unconformity between the overlying Athabasca sandstones and Paleoproterozoic basement rocks. Aqua regia digestion, ammonium acetate at pH 5 and hydroxylamine leaches revealed U, Pb, Co, Ni, Mo, and W anomalies in humus and U, W and As anomalies in B-horizon soils above the ore zones and the basement location of a deposit-hosting, northeast-trending “WS Hanging Wall” shear zone over a three year period. These metal signatures suggest likely upward transport of metals from the deposits to overlying sandstones, and subsequently into the overlying till and soils. This study also looked at materials above the Millennium U deposit, which has indicated resources of 68.2 million lbs U3O8 grading 4 wt% at ~750 m depth that occurs along a major fault in granites & metamorphosed pelites of Paleoproterozoic age below the Athabasca sandstones. Soil samples taken over the surface projections of an ore-hosting fault and the ore zone yielded anomalous values in U, Ni, Cu and Pb in aqua regia digestion of humus and U, Cu and Pb values in ammonium acetate leach of pH 5 of B-horizon soils. Hydroxylamine leach did not yield as many anomalies as ammonium acetate leach. Measured 4He/36Ar ratios of gas dissolved in water-filled drill holes were observed to be up to about 700 times the atmosphere value for air-saturated water, revealing the presence of radiogenic 4He that was likely produced from decaying U and released in the groundwater above the deposit. Our results suggest upward migration of metals to surface through porous sandstone and fault systems at Phoenix, and upward migration of metals along faults and He gas at Millennium. Both studies indicate the importance of the traverse method of sampling over targets perpendicular to the last major ice-flow event to discern U deposits that are defined by other means.
820129

Effect of Crude Glycerol from Biodiesel Production on the Performance and Anaerobic Metabolism of Catalysts in a Glycerol Oxidizing Microbial Fuel Cell

Sivell, Jamie-lynn 16 April 2014 (has links)
Use of waste glycerol as fuel in microbial fuel cells (MFCs) would result in the production of valuable metabolites and electricity, to the benefit of biodiesel operations. In this research, the effect of salt and other compounds found in waste glycerol from biodiesel production on the metabolism and performance of three cultures (Escherichia coli W3110, Propionibacterium freudenreichii ssp. shermanii and mixed culture AR2), used as anodic catalysts in an MFC was studied. MFC experiments were performed in parallel with serum bottle fermentations to allow for comparison of glycerol consumption and metabolite yield. The effect of salt content on the performance of all three cultures was positive in most cases and negligible in others. Using waste glycerol with an increased concentration of other compounds (other than salt) only reduced the performance of AR2, however an inhibitory effect on the rate of glycerol consumption was observed with both AR2 and P. freudenreichii ssp. shermanii. For all strains, the rate of glycerol consumption was slower in MFCs than in fermentations as a result of the electrochemical environment; the yield of various metabolites also differed.
820130

Identifying Early Indicators of Subjective Memory Concerns in Seniors

Lloyd, Brittany K. 16 April 2014 (has links)
Background: Subjective Memory Concerns (SMC) in seniors can be one of the earliest indicators of future dementia. There is a lack of research into the nature of these concerns and functional impairments. Methods: This retrospective secondary analysis gathered data from 67 healthy seniors aged 65+ using neuropsychological tests, memory concern questionnaires and daily functioning scales. Informants corroborated memory concerns and daily functioning. Participants comprised two groups: SMC if worried about their memory and Not Concerned about Memory if not. Results: People with SMC report more difficulty with word finding, remembering appointments, learning to use new equipment, and remembering details of social and personal events. Informants perceive word finding difficulties and minor problems with vocational abilities and bowel/bladder control in SMC participants. Conclusions: The SMC group primarily reports social difficulties. Further research is required to create a comprehensive list of cognitive concerns, which will ultimately improve care of the SMC population. Contexte: Les préoccupations subjectives de mémoire (PSM) chez les aînés peuvent être indicatives d’une démence future, bien qu’il existe un manque d’information sur les préoccupations et l’effet fonctionnel. Méthodes: Une analyse rétrospective secondaire de questionnaires de mémoire, de tests neuropsychologiques, et d’échelles fonctionnelles a été entreprise auprès de 67 personnes, en bonne santé, âgées de 65 ans et plus. Les aidants naturels ont pu appuyer les préoccupations cognitives et le niveau de fonctionnement chez deux groupes de participants: ceux avec préoccupations ou non. Résultats: Les participants PSM relèvent des difficultés de manque du mot, de rappel (rendez-vous, événements sociaux), et d’utilisation de nouveaux équipements. Les aidants naturels ont aussi trouvé de légères difficultés au travail et au niveau du contrôle intestinal et urinaire. Conclusions: Les PSM identifient principalement des lacunes au niveau social. Les recherches devront viser l’identification d’une liste exhaustive des préoccupations afin de pouvoir octroyer de meilleurs soins.

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