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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.
151

A Study of the Competencies Needed of Entry-level Academic Health Sciences Librarians

Philbrick, Jodi Lynn 05 1900 (has links)
The purpose of this study was to identify the professional and personal competencies that entry-level academic health sciences librarians should possess from the perspectives of academic health sciences library directors, library and information sciences (LIS) educators who specialize in educating health sciences librarians, and individuals who serve as both LIS adjunct faculty and practitioners in the field of health sciences librarianship. the first six research questions focused on the identification of professional and personal competencies, and the last two research questions focused on comparing and contrasting the three perspectives on the professional and personal competencies. the eight research questions were addressed through four rounds of the Delphi method. Three panels of experts, initially composed of 13 academic health sciences library directors, 8 LIS educators, and 8 LIS adjunct faculty adjunct faculty/health sciences librarianship practitioners, participated in the study, and most participants were female, white, in the age range of 45-64, had less than 20 years of experience in their respective careers, and were members of the Medical Library Association. the data collected from the rounds of the Delphi method were analyzed using descriptive statistics, including measures of central tendency, and non-parametric statistics, including the Kruskal-Wallis and Mann-Whitney U tests. Two major conclusions that can be drawn from the findings of the study are: (1) personal competencies are as important as professional competencies and (2) the professional and personal competencies developed by the LIS educators who specialize in health sciences librarianship education were preferred over the ones developed by the academic health sciences library directors and LIS adjunct faculty/health sciences librarianship practitioners. Experts in the field of health sciences librarianship have created a comprehensive inventory of both professional (knowledge and skill) competencies and personal (self-concept, trait, and motive) competencies that can be used in professional practice as well as educational planning.
152

Some Problems in the Mathematics of Fracture: Paths From Front Kinetics and a Level Set Method

Richardson, Casey Lyndale 25 April 2008 (has links)
This dissertation presents results for two separate problems, both in the context of variational fracture models. The first problem involved developing and analyzing models of fracture in which we modeled the energy dissipated by crack growth as concentrated on the front of the crack. While many engineering models of fracture are based on a notion of crack front, there had not been a rigorous definition. We present the first work in this area, which includes a natural weak definition of crack front and front speed, a model of fracture whose evolution is described at the crack front, and a relaxation result that shows that these front based dissipations are all effectively equivalent to a Griffith-type dissipation. The second problem involved the computation of stationary points for Mumford-Shah and fracture using a level set method. Our method improves on existing techniques in that it can handle tips in the singular set and can find minimizers that previous techniques are unable to resolve.
153

Morphodynamic responses of salt marshes to sea-level rise: upland expansion, drainage evolution, and biological feedbacks

Farron, Sarah Jean 11 December 2018 (has links)
Accelerating sea-level rise (SLR) poses an imminent threat to salt marshes, which sit within meters of mean sea level. In order to assess marsh vulnerability to SLR, we must first understand the fundamental processes governing marsh response to SLR. The objective of this dissertation work is to examine how marsh sedimentation and erosion affect the morphological development of marshes as sea level rises, over a broad range of spatial and temporal scales. At the smallest scale, the effects of bioturbation by Sesarma reticulatum crabs on sediment erodibility are examined using a laboratory flume. Measurements of surface elevation, erosion, and turbidity show that S. reticulatum bioturbation repackages formerly compacted sediment and deposits it above the surface, decreasing the threshold velocity for erosion and increasing eroded volume. S. reticulatum-induced sediment erosion can have broader impacts on creek development and marsh morphology. S. reticulatum has facilitated drainage network expansion in salt marshes at Sapelo Island, GA and Cape Romain, SC in response to local SLR. Burrowing by this crab directly adjacent to tidal creeks at these locations leads to rapid headward growth. The effects of site-specific conditions on creek expansion are examined through comparison of sediment properties, surface elevations, and historical rates of creek growth at each site. Results suggest that while similar processes are occurring at both locations, the higher elevation of the marsh in GA leads to greater shear strength and a larger volume of material to be eroded by creeks. These combined effects have led to slower creek growth compared to SC. At the largest spatial scale, and projecting forward over a 100-year period, a model for marsh response to SLR at the Great Marsh in Massachusetts is developed. This model takes into account limitations imposed by both low sediment availability and steep topography in the surrounding uplands. Results indicate that while the marsh may persist for several decades, it undergoes a dramatic shift in ecology and hydrology. As the rate of SLR accelerates, marsh loss increases due to the lack of sediment available for accretion and the physical barriers to migration presented by surrounding topography.
154

Level set method for image segmentation and manga stylization. / CUHK electronic theses & dissertations collection

January 2007 (has links)
Our method can be naturally applied in the application of manga stylization rendering. We propose a novel colorization technique that propagates color over manga regions exhibiting pattern-continuity as well as intensity-continuity. The proposed method works effectively on colorizing black-and-white manga which contains intensive amount of strokes, hatching, halftoning and screening. Once the user scribbles on the drawing, a local, statistical based pattern feature obtained with Gabor wavelet filters is applied to measure the pattern-continuity. The boundary is then propagated by the level set method that monitors the pattern-continuity. Regions with open boundaries or multiple disjointed regions with similar patterns can be sensibly segmented by a single scribble. With the segmented regions, various colorization techniques can be applied to replace colors, colorize with stroke preservation, or even convert pattern to shading. Based on the observation of the manga features, we then propose a framework to generate manga-style backgrounds from real photographs. It frees manga artists from the tedious and time-consuming background production. To mimic how manga artists produce the tidy background, it composes of two major steps, the line drawing and the screen laying. A line importance model is proposed to simplify and embolden lines in a stylish way. During the screen laying, texture analysis is utilized to automatically match the regions in photographs with screens in the database. Two types of screening mechanisms are proposed for matching shading & texture as well as the high-level structures. / Segmentation has always been a crucial and challenging topic in various computer vision and graphics applications. Information from image features can be incorporated into image segmentation techniques to make the process more accurate and robust. This dissertation focuses on encoding these feature information into the image processing procedures, including image segmentation and manga stylization rendering. / The fundamental part of this dissertation includes the discussion on the construction of the speed function, which is important in applying the curve-evolution based image segmentation. We firstly investigate the curvature term in the speed function, and then show how to transform the image segmentation problem into an interface propagating problem. We propose two formulations to enhance the speed function in level set methods, in order to tackle the segmentation problem of tagged MR images. First, a relaxation factor is introduced, aiming at relaxing the boundary condition when the boundary is unclear or blurry. Second, in order to incorporate human visual sensitive information from the image, a simple and general model is introduced to incorporate shape, texture and color features. By further extending this model, we present a unified approach for segmenting and tracking of the high-resolution color anatomical Chinese Visible Human (CVH) data. The underlying relationship of these two applications relies on the proposed variational framework for the speed function. Our proposed method can be used to segment the first slice of the volume data. Then based on the extracted boundary on the first slice, our method can also be adapted to track the boundary of the homogeneous organs among the subsequent serial images. In addition to the promising segmentation results, the tracking procedure requires only a small amount of user intervention. / Qu Yingge. / "July 2007." / Advisers: Heng Pheng Ann; Wong Tien Tsin. / Source: Dissertation Abstracts International, Volume: 69-01, Section: B, page: 0433. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 107-120). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.
155

The changing coastal landscapes of Sicily : sea-level change, natural catastrophe and geomorphological modification of the Sicilian coastline : their impact on the visibility of archaeological evidence for human occupation

Ritchie, Graham January 2016 (has links)
Deteriorating climate in the period leading up to the Last Glacial Maximum (LGM) 20,000 years ago caused global sea levels to fall to a lowstand of 125m below modern levels. This resulted in the recession of the Sicilian palaeoshoreline by up to 150km and the emergence of vast tracts of coastal lowland. Following climate amelioration and deglaciation, rising sea levels inundated these formerly exposed areas. The earliest indication of a modern human presence on Sicily comes from Fontana Nuova, in the southeast of the island. The timing of this occupation, on the basis of cross-dating of Aurignacian lithic typology, is about 37,000 BP – a time when sea levels around the Sicilian coastline were some 40-80m lower than at present. The oldest scientifically-dated human remains come from Addaura Caprara, dated to 15,643–15,177 cal BP. Some archaeologists interpret the evidence as suggesting a brief, solitary visit to the island at around 37,000 BP followed by a gap of some 20,000 years before the establishment of a permanent presence during the 16th millennium BP. Others dismiss the veracity of the evidence from Fontana Nuova and hold that Sicily was never settled until some considerable time after the LGM. Until late 20th-century studies demonstrated the attractions of coastal ecotones, absence of evidence was sometimes interpreted as a rejection of coastal landscapes by Upper Palaeolithic and Mesolithic hunter-gatherers. My thesis will argue that Sicily was not uninhabited for 20,000 years or more but that any evidence for human coastal presence throughout prehistory is potentially submerged. I consider the attractions of coastlands for early modern humans. I discuss the physical background to glaciation and deglaciation resulting in sea-level change. By combining data on absolute sea-level change with evidence for terrestrial displacement resulting from tectonic forces, I have determined relative sea-level change affecting the coastlines of Sicily from 37,000 BP until the Iron Age (ending c750 BC). The results have been combined with digital bathymetric data within an ESRI ArcMap GIS program to produce a series of maps at archaeologically-significant dates. The very areas that are now recognised as being attractive to modern humans will be shown to be submerged today. With reference to modern scientific techniques and their application by specialists in a variety of locations, I shall demonstrate that the successful recovery of submerged archaeological evidence is achievable. I shall also consider a number of phenomena revealed by my field observations that have conspired to conceal or destroy the coastal archaeological record, the absence of such evidence being used illegitimately to support claims for an unpopulated island. These phenomena include natural catastrophes such as earthquakes and related tsunamis, volcanic activity and landslides. Additionally, coastline modification resulting from river estuary migration, and anthropogenic impacts will be considered.
156

On the viscoelastic deformation of the Earth

Crawford, Ophelia January 2019 (has links)
Post-seismic deformation and glacial isostatic adjustment are two processes by which the Earth deforms viscoelastically. In both cases, the details of the deformation depend on the rheological structure of the Earth as well as the forcing, which is the earthquake and further movement on the fault in the case of post-seismic deformation, and the change in load on the surface of the Earth due to the redistribution of water and ice mass in the case of glacial isostatic adjustment. It is therefore possible to learn about the Earth's rheological structure and the processes' respective forcings from measurements of the deformation. In order to use measurements in this way, it is first necessary to have a method of forward modelling the processes, that is, calculating the deformation due to a given forcing and in an earth model with a given structure. Given this, a way of calculating derivatives of measurements of the deformation with respect to the parameters of interest is then desirable. In this dissertation, the adjoint method is used. This, for the first time, enables efficient calculation of continuous derivatives, which have many potential applications. Firstly, they can be used within a gradient-based optimisation method to find a model which minimises some data misfit function. The derivatives can also be used to quantify the uncertainty in such a model and hence to provide understanding of which parts of the model are well constrained. Finally, they enable construction of measurements which provide sensitivity to a particular part of the model space. In this dissertation, new methods for forward modelling both post-seismic deformation and glacial isostatic adjustment are presented. The adjoint method is also applied to both problems. Numerical examples are presented in spherically symmetric earth models and, in the case of glacial isostatic adjustment, models with laterally varying rheological structure. Such examples are used to illustrate the potential applications of the developments made within this dissertation.
157

Risk factors and outcomes associated with generalised anxiety disorder : findings from a large population study

Remes, Roxana-Olivia January 2019 (has links)
Scientific interest in the clinical implications, public health importance, and risk factors of anxiety disorders has grown substantially in the past two decades. Despite this, the evidence base on anxiety is insufficient to inform health care planning and policy-making. Further research on the outcomes and risk factors associated with anxiety disorders, and ways of mitigating these risks is needed. One of the aims of this thesis was to provide an overview of the existing literature on the prevalence of anxiety in adults living in countries across the globe, and to describe the prevalence in the context of various health states and life stages. Because generalised anxiety disorder is one of the most common psychiatric conditions in the population, the remainder of the thesis focused on this disorder and aimed to explore its links with health service use and mortality. Risk for this condition was also explored and area deprivation was studied as a possible determinant. Since depression is commonly studied alongside anxiety, the relationship between the residential environment and major depressive disorder was also assessed. Finally, to provide insight into the mitigation of risks of generalised anxiety disorder, a study of coping mechanisms was undertaken. Primary study findings from this thesis are based on the European Prospective Investigation of Cancer in Norfolk, a large, population study of British people over the age of 40. Results from the systematic review showed that anxiety is common in population sub-groups around the world, with women, younger people, and those suffering from chronic physical conditions, such as cancer and cardiovascular disease being particularly affected. Results from the primary studies of the thesis showed that generalised anxiety disorder is associated with increased risk for deaths, though it is not significantly associated with non-psychiatric hospital admissions. Results from the risk factor analyses showed that living in a deprived area is associated with generalised anxiety disorder in women and major depressive disorder in men. The risk mitigation analysis indicated that sense of coherence is an important coping mechanism that can protect against generalised anxiety disorder among women living in disadvantaged circumstances. My work has shown novel associations and attempted to provide a more complete picture of one of the most common psychiatric conditions in the population by focusing on several angles: health outcomes, risk factors, and ways of mitigating risks.
158

Simulations of a novel accelerator of intense ion beams for high energy density physics studies. / 作高能量密度物理研究的一種新型強離子束加速器的模擬 / Simulations of a novel accelerator of intense ion beams for high energy density physics studies. / Zuo gao neng liang mi du wu li yan jiu de yi zhong xin xing qiang li zi shu jia su qi de mo ni

January 2009 (has links)
Ling, Chi Yeung = 作高能量密度物理研究的一種新型強離子束加速器的模擬 / 凌子陽. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (p. 111-114). / Abstracts in English and Chinese. / Ling, Chi Yeung = Zuo gao neng liang mi du wu li yan jiu de yi zhong xin xing qiang li zi shu jia su qi de mo ni / Ling Ziyang. / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Background --- p.7 / Chapter 2.1 --- High Energy Density Physics and Warm Dense Matter --- p.7 / Chapter 2.1.1 --- Definition of HEDP and WDM --- p.7 / Chapter 2.1.2 --- The physics of WDM --- p.9 / Chapter 2.1.3 --- Advantages of the ion beam approach --- p.10 / Chapter 2.2 --- Intense low energy ion beam machines requirements for NDCX-II --- p.12 / Chapter 2.3 --- Neutralized Drift Compression Experiment (NDCX) --- p.14 / Chapter 2.3.1 --- Neutralized Transport Experiment (NTX) --- p.15 / Chapter 2.3.2 --- The first NDCX --- p.18 / Chapter 2.4 --- Accelerator architectures proposed for NDCX-II --- p.20 / Chapter 2.4.1 --- Radio Frequency Linear Accelerator (RF Linac) --- p.20 / Chapter 2.4.2 --- Electrostatic accelerator --- p.23 / Chapter 2.4.3 --- Drift Tube Linac (DTL) --- p.23 / Chapter 2.4.4 --- Linear Induction Accelerator (induction linac) --- p.24 / Chapter 2.5 --- Pulse Line Ion Accelerator --- p.25 / Chapter 2.6 --- Review on tests of Pulse Line Ion Accelerator --- p.30 / Chapter 2.7 --- Simulation codes --- p.32 / Chapter 2.7.1 --- 3-D Electromagnetic code MAFIA --- p.33 / Chapter 2.7.2 --- Particle-in-cell code WARP --- p.35 / Chapter 2.8 --- Envelope equation of ion beam and beam diagnostics --- p.37 / Chapter 3 --- Investigations on insulator breakdown in the PLIA --- p.40 / Chapter 3.1 --- Modeling in MAFIA --- p.40 / Chapter 3.2 --- Scaling Law --- p.42 / Chapter 3.3 --- Investigation of different frequency modes near insulator surface --- p.46 / Chapter 3.4 --- Standing wave effect in PLIA --- p.50 / Chapter 3.5 --- Conclusion --- p.52 / Chapter 4 --- PLIA based design for the second Neutralized Drift Compression Experiment --- p.55 / Chapter 4.1 --- The injector --- p.56 / Chapter 4.2 --- Pulse Line Ion Accelerator sections --- p.60 / Chapter 4.2.1 --- Basic design strategy --- p.60 / Chapter 4.2.2 --- Simulation results of PLIA sections --- p.69 / Chapter 4.3 --- Neutralized Drift Compression Section --- p.77 / Chapter 4.3.1 --- Drift length --- p.78 / Chapter 4.3.2 --- First focusing solenoid --- p.80 / Chapter 4.3.3 --- Plasma-filled region --- p.84 / Chapter 4.3.4 --- Final focusing solenoid and the best focal point --- p.88 / Chapter 4.3.5 --- Sensitivity to drift length and focusing strength --- p.91 / Chapter 4.4 --- Conclusion --- p.92 / Chapter 5 --- Other Pulse Power Options --- p.94 / Chapter 5.1 --- The injector and the beamline --- p.95 / Chapter 5.2 --- 3-meter electrostatic column --- p.97 / Chapter 5.3 --- Induction linac --- p.100 / Chapter 5.4 --- Hybrid of induction linac and Pulse Line Ion Accelerator --- p.104 / Chapter 5.5 --- Conclusion --- p.107 / Chapter 6 --- Discussions --- p.108 / Chapter 6.0.1 --- Future development of PLIA --- p.110 / Bibliography --- p.111
159

The Effects of Increment and Decrement Manipulations on Titration Level under Interlocking Progressive- Ratio Schedules of Reinforcement

Nunes, Dennis Lorbin 01 May 1975 (has links)
Generally human titration performance under schedules of reinforcement has not been investigated. In an attempt to examine the variables which control titration, an interlocking progressive-ratio schedule was devised. Under an interlocking progressive-ratio schedule, the number of responses required for reinforcement increases by a constant (the increment value) after every ratio, but during each ratio the response requirement can be lowered (the decrement value) by emitting pauses of a specified duration (the stepdown duration). The first experiment sought to determine if children would titrate when exposed to interlocking progressive-ratio schedules. Although three of the four subjects did not show evidence of titration initially, through a series of manipulations all came under schedule control. Experiment 2 was conducted to determine the effects of a series of increment value manipulations on the level of titration. The series of increment values was tested under large and small decrement conditions. The results showed that increment value was an important determiner of titration level only when the decrement value was small. When the decrement value was large, changes in increment value had no effect upon titration. In Experiment 3 the effects of a series of decrement manipulations on titration level were examined. The decrement manipulations were investigated under two increment values. The results indicated that as the decrement value was decreased the titration level tended to increase under both increment conditions. In all of the experiments, rate of responding, pausing, titration variability, and patterns of responding were examined. Generally rate of responding, pausing, and response patterning were found to be related to changes in increment and decrement values. Titration variability showed no systematic changes across manipulations. Analysis of subjects' behavior in terms of preference indicated that the subjects tended to minimize number of responses rather than maximize reinforcement frequency. Subjects would pause to bring down the response requirement, and thus increase the time between reinforcements, rather than emit responses on a lever, which would have resulted in more reinforcements per unit of time.
160

Scaling the Response of Deltas to Relative Sea-level Cycles by Autogenic Space and Time Scales: a Laboratory Study

January 2017 (has links)
acase@tulane.edu / Relative Sea-Level (RSL) change influences surface processes and stratigraphic architecture of deltaic systems and has been studied extensively for decades. However, we still lack a quantitative framework to define what constitutes a small vs. large or short vs. long RSL cycle. We explore these questions with a suite of physical experiments that shared identical forcing conditions with the exception of sea-level. We utilize two non-dimensional numbers that characterize the magnitude and period of RSL cycles. Magnitude is defined with respect to the maximum autogenic channel depth, while the periodicity is defined with respect to the time required to deposit one channel depth of sediment, on average, everywhere in the basin. The experiments include: 1) a control experiment lacking RSL cycles, used to define autogenic scales, 2) a low magnitude, long period (LMLP) stage, and 3) a high magnitude, short period (HMSP) stage. We observe clear differences in the response of deltas to the forcing in each experiment. The RSL cycles in the HMSP stage induce allogenic surface processes and stratigraphic products with scales that exceed the stochastic variability found in the control stage. These include the generation of rough shorelines and large temporal gaps in the stratigraphy. In contrast, the imprint of LMLP cycles on surface processes and stratigraphy is found in properties that define the mean state of a system. These include the mean shoreline location and extraction of sediment inbound of the mean shoreline. This work demonstrates the effectiveness of defining RSL cycle magnitude and period through autogenic scales and provides insights for generation of forward stratigraphic models influenced by RSL change. / 1 / Lizhu Yu

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