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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.
61

Axon morphology in the uncinate fasciculus: a post-mortem analysis of white matter microstructure

Stackpole, Melinda Camryn 06 June 2024 (has links)
The Uncinate Fasciculus (UF) is a white matter association tract responsible for connecting the frontal and temporal lobes of the brain. Its location, general shape, and estimated projections have been visualized and analyzed at low-resolution via diffusion tensor imaging (DTI) in many studies, allowing for a basic understanding of the pathway and its potential functions. Despite this, the microstructural properties of this white matter highway are still relatively unknown as we can estimate characteristics such as myelination and pathway density from low-resolution imaging, but we cannot gain a deeper understanding of the fine characteristics that allow the pathway to function in health and how those features are disrupted in disease. To address this gap, we examined six post-mortem tissue samples, featuring approximately 12,000 axons of the temporal segment of the UF (adjacent to the amygdala and hippocampus) from neurotypical controls. We used high-resolution microscopy to systematically sample and study the microstructure of myelinated axons to characterize the UF for future comparisons to disease states, like Autism Spectrum Disorder (ASD). We provide novel characterization of the microstructure of the UF in both hemispheres, examining density, size, myelination, and trajectories of axons in healthy adult tissue. Our data revealed hemispheric trends of axon characteristics that align with previous imaging studies, including slight left hemispheric asymmetry in regard to density and myelination and a small increase in trajectory variability in the right hemisphere. In addition, like values found previously in the Corpus Callosum, the distribution of thin and medium axons was much higher than thick axons. Our findings provide a more in-depth understanding of the microstructural characteristics of the UF at the level of single axons, providing context for white matter anisotropy and diffusivity estimates from previous DTI studies through values such as myelin thickness, area fraction, and axon trajectory. This structural framework of this pathway can be used to compare with results from in vivo imaging studies, and to provide a basis for comparison with pathological states in the future. / 2026-06-06T00:00:00Z
62

Investigating Various Modal Analysis Extraction Techniques to Estimate Damping Ratio

Iglesias, Angel Moises 02 December 2000 (has links)
Many researchers have devoted their work to the development of modal analysis extraction techniques in order to obtain more reliable identification of the modal parameters. Also, as a consequence of all this work, there are some other works devoted to the evaluation and comparison of these methods in order to find which one is the most reliable method with respect to certain characteristics. In this thesis the Rational Fraction Polynomial (RFP) Method, the Prony or Complex Exponential Method (CEM), the Ibrahim Time Domain (ITD) Method, and Hilbert Envelope Method are used to evaluate how the accuracy of the damping ratio is affected with respect to various parameters and conditions. The investigation focuses in the estimation of damping ratio because among the modal parameters, it is the most difficult to model. Each method is evaluated individually in order to understand how the damping ratio estimation is affected with respect to each method when the characteristics of the FRF are changed. Also, they are compared to show that, in general, the Rational Fraction Polynomial Method is a more reliable method than the other methods. To investigate this, a simulated analytical data and an experimental data are processed to estimate the modal parameters, but focusing in the damping ratio. For the simulated analytical data the damping ratio's percent of error were calculated. The highest damping ratio's percent of error of the RFP was 0.0073501%. In the other hand, for the CEM, ITD, and Hilbert Envelope Method their highest damping ratio's percent of error were 83.02%, 99.82%, and 4.077%, respectively. / Master of Science
63

It Is Better to Be Upside Than Sharpe!

DApuzzo, Daniele 01 April 2017 (has links)
Based on the assumption that returns in Commercial Real Estate are normally distributed, the Sharpe Ratio has been the standard risk-adjusted performance measure for the past several years. Research has questioned whether this assumption can be reasonably made. The Upside Potential Ratio as a risk-adjusted performance measure is an alternative to measure performance on a risk-adjusted basis but its values differ from the Sharpe Ratio's only in the assumption of skewed returns. We will provide reasonable evidence that CRE returns should not be fitted with a normal distribution and present the Gaussian Mixture Model as our choice of distribution to fit skewness. We will then use a GMM distribution to measure performance of CRE domestic markets via UPR. Additional insights will be presented by introducing an alternative risk-adjusted perfomance measure that we will call D-ratio. We will show how the UPR and the D-ratio can provide a tool-box that can be added to any existing investment strategy when identifying markets' past performance and timing of entrance. The intent of this thesis is not to provide a comprehensive framework for CRE investment decisions but to introduce statistical and mathematical tools that can serve any portfolio manager in augmenting any investment strategy already in place.
64

Hodnocení finanční situace podniku a návrhy na její zlepšení / Evaluation of the Financial Situation in the Firm and Proposals to its Improvement

Balkovič, Miroslav January 2010 (has links)
The thesis assesses the financial and economic situation of the company Balky, s. r.o. based on selected methods of financial analysis. For financial analysis, business data is used from the period 2007 - 2009. It includes proposals of solutions to improve the current financial situation.
65

Multi-Ratio Fusion Change Detection Framework with Adaptive Statistical Thresholding

Hytla, Patrick C. 18 May 2016 (has links)
No description available.
66

Survival Instantaneous Log-Odds Ratio From Empirical Functions

Jung, Jung Ah, Drane, J. Wanzer 01 January 2007 (has links)
The objective of this work is to introduce a new method called the Survivorship Instantaneous Log-odds Ratios (SILOR); to illustrate the creation of SILOR from empirical bivariate survival functions; to also derive standard errors of estimation; to compare results with those derived from logistic regression. Hip fracture, AGE and BMI from the Third National Health and Nutritional Examination Survey (NHANES III) were used to calculate empirical survival functions for the adverse health outcome (AHO) and non-AHO. A stable copula was used to create a parametric bivariate survival function, that was fitted to the empirical bivariate survival function. The bivariate survival function had SILOR contours which are not constant. The proposed method has better advantages than logistic regression by following two reasons. The comparison deals with (i) the shapes of the survival surfaces, S(X1, X2), and (ii) the isobols of the log-odds ratios. When using logistic regression the survival surface is either a hyper plane or at most a conic section. Our approach preserves the shape of the survival surface in two dimensions, and the isobols are observed in every detail instead of being overly smoothed by a regression with no more than a second degree polynomial. The present method is straightforward, and it captures all but random variability of the data.
67

THE CAPITAL REQUIREMENT DIRECTIVE IV : A study of national divergences in Sweden, Denmark and Germany´s financial markets and the ability to implement the CRD IV

Larsson Nyheim, Robin, Larsson Nyheim, Kim January 2012 (has links)
The global financial market has been under a lot of stress in the past years. With the financial crisis that started in 2008, in the US and spread around the world, it created awareness that the world’s financial market requires more regulation to withstand such a crisis. Therefore a new recommended framework for the global financial market was developed by the Basel Committee on Banking Supervision; Basel III. Basel III presented a new era with stricter supervision of banks and tighter regulations. As the European Union is one of the world’s most integrated regions, it strives to be the first to implement the Basel III framework. In order to achieve this, the European Union created its own legislative package, the Capital Requirement Directive IV.The research purpose of this dissertation is to examine how divergences in Sweden, Denmark and Germany’s national financial markets will affect their ability to implement the new CRD IV regulations. Based on the research the conclusion is that our Swedish respondent is most prepared in meeting the new regulations of our three respondents; the characteristics of the Swedish financial market seem well fit to meet the new requirements. Both Germany and Denmark seems to be experiencing problems; the characteristics of their financial markets create obstacles when implementing the new regulations. Denmark has difficulties with their mortgage lending market due to their unique mortgage model. Germany will have problems with the leverage ratio and their inflexible three pillar banking system. Germany’s government has been skeptical to the new CRD IV regulations and this might also have affected our German respondent in a negative way. With the implementation of the regulations the European Commission aims to improve the banking sector in the member states, so that they will be able to endure stress periods better and help to prevent another financial crisis. However, the implementation of the new regulations puts a lot of pressure on the banks and how well they can perform during the implementation process. With this research a questionnaire is created that will help understand how three major banks in Sweden, Denmark and Germany will be affected by the new regulations and if the characteristics of their national financial markets will give them advantages or disadvantages when implementing them. The answers also give us a conclusion to which of the new regulations each respondent will have the most difficulty of implementing. Future research is suggested to be done into the Danish mortgage lending market and their unique mortgage model, to see if it can co-exist with the new CRD IV regulations. Also an in-depth research into the German three pillar banking system can be interesting, to find out if they are able to maintain it or if they have to restructure it.
68

Influences of Sea-land Breezes and Northeastern Monsoon on the Transportation and Dispersion of Air Pollutants over Coastal Region in Southern Taiwan

Tsai, Hsieh-Hung 11 August 2010 (has links)
This study investigated the influences of sea-land breezes (SLBs) and northeastern monsoon (NEM) on the transportation and dispersion of air pollutants over coastal region in southern Taiwan. The physicochemical properties of particulate matter (PM) was simultaneously sampled and analyzed at both inland and offshore sites during eight intensive sampling periods. This study further used a SURFER 2-D plotting software, a backward trajectory model, a 3-D meteorological model (MM5), and a comprehensive air quality model (CAMx) to simulate surface wind fields and spatial distribution of air pollutants over the coastal region during the intensive sampling periods of SLBs and NEM. According to the meteorological condition and the synoptic weather patterns of the observation data showed that the SLBs sampling periods commonly occurred the weather patterns were zone of low pressure, pacific high pressure, and west stretch of the pacific high pressure when the main prevailing wind direction were west wind and southwest wind. During the NEM sampling periods, the weather patterns were strong northeastern monsoon, standard northeastern monsoon, and outflow rebound with high pressure in southern Taiwan, and then the main prevailing wind direction were northwest wind and northeast wind. However, during the MIX sampling periods, the weather patterns were outflow circulation of typhoon, weak northeastern monsoon, and outflow rebound with high pressure, while the wind directions didn¡¦t change regular. Thus, at coastal sites, the sea-land breezes induce an inland transport of air pollutants during the daytime and a seaward return of air pollutants at nighttime, causing a recirculation of air pollutants back to inland regions each day during the SLBs sampling periods. During the NEM sampling period was mainly brought from the northeastern wind which transported air pollutants from the northern region to Kaohsiung metropolitan area. The results of PM concentration and size distribution indicated that the inland sites had a higher fraction of fine particles (PM2.5), whereas the offshore sites had a higher fraction of coarse particles (PM2.5-10). These phenomena were attributed to the fact that marine aerosols are generally abundant in the coarse particles. PM concentration is relatively higher during the NEM sampling periods than during the SLBs and MIX sampling periods. For PM concentration, the order of secondary inorganic aerosols (SIA) was NEM > MIX > SLBs, while the SIA/Ions ratio of PM2.5 were approximately 50% during sampling periods. The [NO3-]/[SO42-] ratios of PM2.5 and PM2.5-10 during the SLBs sampling periods were always lowest than those during the NEM and MIX sampling periods. It is suggested that the PM concentrations during the SLBs sampling periods were highly influenced by stationary sources emissions. The crustal elements indicated that the Al, Ca, Fe, and K contributed major composition of particles. Artificial metals, such as Mg, Pb, V, and Zn were also enriched in the atmospheric PM during the NEM sampling periods. In addition, the higher concentration of Fe was attributed to local anthropogenic emission and weak northeastern monsoon during the MIX sampling periods. Regardless of inland or offshore sites, a high concentration of secondary organic carbon (SOC) during the NEM and MIX sampling periods was consistent with OC/EC ratio higher than 2.2 indicates the potential formation of secondary aerosols. Chloride deficit of PM at inland sites were lost easily for approximately 40.28% during the NEM sampling periods. Moreover, the lowest [Cl-]/[Na+] ratio occurred during the sampling periods when the chloride deficit was relative high at inland sites. According to the results of neutralization ratio (NR), regardless of the periods (SLBs, NEM, and MIX), the particulates of inland and offshore sites were both acid. During the NEM and MIX sampling periods, sulphur oxidation ratio (SOR) of PM2.5 over coastal region in southern Taiwan were above 0.25. It is suggested that the results of SOR during those sampling periods were highly influenced by long transportation. In addition, the nitrogen oxidation ratio was lower influenced than SOR over coastal region in southern Taiwan. It is suggested that air quality of Kaohsiung metropolitan area were influenced by the industrial source emissions. During the SLBs sampling period, sea breezes blown in the morning transported the offshore PM10 back to the inland sites in the Kaohsiung metropolitan area. In contrast, the air mass observed during the NEM sampling period was brought to the Kaohsiung metropolitan area mainly by a northerly wind which transported air mass originating in the northern region (i.e. Chiayi counties). The backward trajectory modeling of the MIX sampling periods suggested that the winds were dominated by the Northeastern Monsoon, and as such, likely inhibited the influences of sea-land breezes. Local surface air mass circulation over southern Taiwan obtained from MM5 model influenced by the southwestern monsoon during the SLBs sampling period. The weather in southern Taiwan during the NEM intensive sampling period was occasionally influenced by the Northeastern Monsoon as well as by complex terrain. During the MIX sampling periods, air mass recirculation was frequently observed in the coastal region of southern Taiwan. The results of CAMx model showed that air pollutions were occurred apparent sea breezes in the afternoon and land breezes at night during the SLBs sampling period. During the NEM sampling period, a strong Northeastern Monsoon blew air pollutions from the north to the southern region. We have compared the model simulation with field measured O3 and PM10 concentrations for inland and offshore regions. The order of correlation coefficients of ¬the model simulation and the measurement for O3¬ and PM10 in sampling periods is SLBs>MIX>NEM and NEM>MIX>SLBs, respectively. Overall, the correlation coefficients of the model simulation and the measurement were middle and high correlation.
69

Toxicology of high aspect ratio nanomaterials : how shape determines the biologically effective dose

Schinwald, Anja January 2013 (has links)
Nanotechnologies are the fastest growing industry sector ever recorded. The US budget for nanotechnology is predicted to reach the 1 trillion dollar threshold in 2015, meaning that nanotechnologies will indeed be larger than all other technologies combined. High aspect ratio nanomaterials (HARN) become increasingly important in the nanotechnology industries, and show great promise, offering many advantages and improvements to a significant range of products. The main feature of HARN is the ratio of the width of a nanomaterial to its height which can be up to 1000, making the material fibre or platelet- shaped. However, this feature leads to comparison between HARN and other high aspect ratio materials including fibre shaped materials, such as asbestos fibres. Due to the structural similarities between fibrous HARN and asbestos the question arises- do HARN pose the same risk as asbestos? This project aimed to assess the potential of a range of HARN to cause similar pathological effects as asbestos fibres. In order to address this aim a panel of HARN was tested against the fibre pathogenicity paradigm in vivo by examining the pulmonary and pleural responses as well as in vitro to reveal the mechanism of cell/HARN interaction. The first part of the study focused on fibre-shaped HARN, including a panel of distinct length classes of silver nanowires (AgNW) which were injected directly into the pleural space, a target tissue for asbestos related diseases. Injection of high aspect ratio AgNW into the pleural space of mice revealed a length dependent inflammatory response in line with the fibre pathogenicity paradigm which explains fibre pathogenicity. AgNW from 5 μm in length and above led to a significant increase in granulocytes in the pleural space which is similar to that seen after treatment with long amosite asbestos. The use of additional HARN with different compositions allowed us to identify a threshold length for fibre-induced pleural inflammation, which is 5 μm. Frustrated phagocytosis has been stated as an important factor in the initiation of an inflammatory response after fibre exposure. A novel technique, backscatter scanning electron microscopy (BSEM), was used to study frustrated phagocytosis since it provides high-contrast detection of nanowires, allowing clear discrimination between the nanofibres and other cellular features. Using this technique we showed that the onset of inflammation does not correlate with the onset of frustrated phagocytosis, with a fibre length of ≥5 μm and ≥10 μm, respectively, leading to the conclusion that intermediate length fibres fully enclosed within macrophages as well as frustrated phagocytosis are associated with a proinflammatory state in the pleural space. We further showed that fibres compartmentalise in the mesothelial cells at the parietal pleura as well as in inflammatory cells in the pleural space. To investigate the mechanism of the lengthdependent inflammation caused by AgNW, the NALP3 inflammasome activation pathway was studied in vitro, however no clear correlation could be identified. We further aimed to investigate the threshold length of fibre-induced inflammation in the lung and the effect of fibre length on macrophage locomotion in an in vitro macrophage migration assay. Pharyngeal aspiration of AgNW resulted in a length dependent inflammatory response in the lungs with threshold at a fibre length of 14 μm. Shorter fibres including 3, 5 and 10 μm elicited no significant inflammation. This identified threshold length differs from that in the pleural space which may be explained by differences in clearance mechanism of deposited fibres from the airspaces compared to the pleural space. Particle clearance from the lung is partly performed by migration of particle-laden macrophages to the mucociliary escalator. We investigated if uptake of longer fibres leads to restricted mobility and showed that exposure to AgNW in the length of ≥ 5 μm resulted in impaired motility of macrophages in the wound closure assay. The second part of the study focused on HARN in the form of nanoplatelet-shaped particles since nanoplatelets may pose an unusual risk to the lungs and the pleural space because of their aerodynamic properties. We first derived the respirability of graphene nanoplatelets (GP) from the basic principles of the aerodynamic behaviour of plate-shaped particles which allowed us to calculate their aerodynamic diameter. This showed that the nanoplatelets, which were up to 25 μm in diameter, were respirable and so would deposit beyond the ciliated airways following inhalation. We therefore utilized models of pharyngeal aspiration and direct intrapleural installation of GP, as well as an in vitro model, to assess their inflammatory potential. These large but respirable GP were inflammogenic in both the lung and the pleural space at an acute timepoint although they decreased in their inflammatory potential over a 6 weeks period. Oxidation of GP in the lung tissue was investigated in order to identify if GP degraded over the 6 week period in the lung tissue and therefore showed reduced inflammogenicity. Raman spectroscopy was used to measure the oxidation state and revealed that no change occurred over the observed timeframe. The mechanism underlying acute GP inflammation was studied in THP-1 macrophages exposed to GP. These investigations showed that GP exposure led to significant expression of IL-1β, which could be blocked via a number of inhibitors related to the NALP3 inflammasome activation. This study highlights the importance of shape/length of HARN as a driver for in vivo and in vitro inflammogenicity by virtue of their respirable aerodynamic diameter, despite a considerable 2-dimensional size which leads to an inflammatory response when deposited in the distal lungs and the pleural space. The identification of the threshold length for nanofibre-induced pathogenicity in the pleura and the lung has important implications for the understanding of the structure–toxicity relationship for asbestos-induced mesothelioma. It also contributes to risk assessment by offering a template for production of safer synthetic nanofibres by the adoption of a benign-bydesign approach. The results of this work highlight the importance of testing new HARN to protect workers in nanotechnology industries and the public.
70

Trauma resuscitation requiring massive transfusion: a descriptive analysis of the role of ratio and time

Peralta, Ruben, Vijay, Adarsh, El-Menyar, Ayman, Consunji, Rafael, Abdelrahman, Husham, Parchani, Ashok, Afifi, Ibrahim, Zarour, Ahmad, Al-Thani, Hassan, Latifi, Rifat January 2015 (has links)
OBJECTIVE: We aimed to evaluate whether early administration of high plasma to red blood cells ratios influences outcomes in injured patients who received massive transfusion protocol (MTP). METHODS: A retrospective analysis was conducted at the only level 1 national trauma center in Qatar for all adult patients(≥18 years old) who received MTP (≥10 units) of packed red blood cell (PRBC) during the initial 24 h post traumatic injury. Data were analyzed with respect to FFB:PRBC ratio [(high ≥ 1:1.5) (HMTP) vs. (low < 1:1.5) (LMTP)] given at the first 4 h post-injury and also between (>4 and 24 h). Mortality, multiorgan failure (MOF) and infectious complications were studied as well. RESULTS: During the study period, a total of 4864 trauma patients were admitted to the hospital, 1.6 % (n = 77) of them met the inclusion criteria. Both groups were comparable with respect to initial pH, international normalized ratio, injury severity score, revised trauma score and development of infectious complications. However, HMTP was associated with lower crude mortality (41.9 vs. 78.3 %, p = 0.001) and lower rate of MOF (48.4 vs. 87.0 %, p = 0.001). The number of deaths was 3 times higher in LMTP in comparison to HMTP within the first 30 days (36 vs. 13 cases). The majority of deaths occurred within the first 24 h (80.5 % in LMTP and 69 % in HMTP) and particularly within the first 6 h (55 vs. 46 %). CONCLUSIONS: Aggressive attainment of high FFP/PRBC ratios as early as 4 h post-injury can substantially improve outcomes in trauma patients.

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