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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.
51

Computer model of a focal plane array

Thvedt, Tom Arnold, 1956- January 1988 (has links)
The background and operation of charge transfer devices is reviewed, and a computer model simulation of focal plane arrays is presented. The model provides an option to predict the performance of a focal plane. With this program, any of the allowed materials, detectors, readout structures, or preamplifiers that make up a focal plane, may be selected to create new designs for analysis. Only surface channel devices are considered, and only references to the spectral dependence are presented. The computer model's operation and validity is supported by over 70 equations and more than 50 figures, including actual computer screen printouts. Standard equations followed by brief discussions are used to support the menu driven program. The structure and operation of the computer model is presented, but not the actual software source code.
52

EVALUATION OF A SCHOTTKY BARRIER INFRARED CHARGE-COUPLED DEVICE.

Hudson, Leland Ray. January 1982 (has links)
No description available.
53

Improved designs for future thermal imagers

Ibrahim, Hassan January 2000 (has links)
No description available.
54

Qualitative Assessment of Activated Microglia and Astrocytes in Focal Cortical Dysplasia: Case Series of Pediatric Patients

Yee, Nicole 22 May 2017 (has links)
A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine. / Epilepsy is the most common neurologic condition seen in children. Focal cortical dysplasia (FCD), a seizure disorder characterized by abnormal cortical laminar development, comprises approximately 75% of medically intractable epilepsies in the pediatric population. A greater appreciation of the pathology and intrinsic properties of the epileptogenic zone may help in understanding why FCD lesions are drug‐resistant, and could potentially lead to more effective treatments in the pediatric population. Neuronal support cells such as microglia and astrocytes have shown to have a role in FCD pathology. These cells are also activated during aging and traumatic brain injury as evidence by morphological change. This study aims to characterize the spatial distribution of microglia and astrocytes using immunohistochemistry in dysplastic tissue of eight male pediatric patients diagnosed with FCD. Cortical specimens from patients who underwent surgical resection of focally dysplastic cortex at Phoenix Children’s Hospital between 2008 and 2014 were examined using immunohistochemistry. Primary antibodies against GFAP and Iba1, as well as structural staining using hematoxylin and eosin (H&E), were incubated on sections and further analyzed using bright‐field microscopy. A pattern of perivascular activated microglia was observed in five patients around at least one blood vessel, while a pattern of non‐localized ramified microglia was observed in the other three patients. No identifiable pattern of astrocytic distribution was found. Thus, distinct patterns of microglia, rather than astrocytes, suggest dual underlying mechanisms of epileptogenesis.
55

Characterizing octagonal and rectangular fibers for MAROON-X

Sutherland, Adam P., Stuermer, Julian, Miller, Katrina R., Seifahrt, Andreas, Bean, Jacob L. 22 July 2016 (has links)
We report on the scrambling performance and focal-ratio-degradation (FRD) of various octagonal and rectangular fibers considered for MAROON-X. Our measurements demonstrate the detrimental effect of thin claddings on the FRD of octagonal and rectangular fibers and that stress induced at the connectors can further increase the FRD. We find that fibers with a thick, round cladding show low FRD. We further demonstrate that the scrambling behavior of non-circular fibers is often complex and introduce a new metric to fully capture non-linear scrambling performance, leading to much lower scrambling gain values than are typically reported in the literature (<1000 compared to 10,000 or more). We find that scrambling gain measurements for small-core, non-circular fibers are often speckle dominated if the fiber is not agitated.
56

Applications of focal-series data in scanning-transmission electron microscopy

Jones, Lewys January 2013 (has links)
Since its development, the scanning transmission electron microscope has rapidly found uses right across the material sciences. Its use of a finely focussed electron probe rastered across samples offers the microscopist a variety of imaging and spectroscopy signals in parallel. These signals are individually intuitive to interpret, and collectively immensely powerful as a research tool. Unsurprisingly then, much attention is concentrated on the optical quality of the electron probes used. The introduction of multi-pole hardware to correct optical distortions has yielded a step-change in imaging performance; now with spherical and other remnant aberrations greatly reduced, larger probe forming apertures are suddenly available. Probes formed by such apertures exhibit a much improved and routinely sub-Angstrom diffraction-limited resolution, as well as a greatly increased probe current for spectroscopic work. The superb fineness of the electron beams and enormous magnifications now achievable make the STEM instrument one of the most sensitive scientific instruments developed by man, and this thesis will deal with two core issues that suddenly become important in this new aberration-corrected era. With this new found sensitivity comes the risk of imaging-distortion from outside influences such as acoustic or mechanical vibrations. These can corrupt the data in an unsatisfactory manner and counter the natural interpretability of the technique. Methods to identify and diagnose this distortion will be discussed, and a new technique developed to restore the corrupted data presented. Secondly, the subtleties of probe-shape in the multi-pole corrected STEM are extensively evaluated via simulation, with the contrast-transfer capabilities across defocus explored in detail. From this investigation a new technique of STEM focal-series reconstruction (FSR) is developed to compensate for the small remnant aberrations that still persist – recovering the sample object function free from any optical distortion. In both cases the methodologies were developed into automated computer codes and example restorations from the two techniques are shown (separately, although in principal the scan-corrected output is compatible with FSR). The performance of these results has been quantified with respect to several factors including; image resolution, signal-noise ratio, sample-drift, low frequency instability, and quantitative image intensity. The techniques developed are offered as practical tools for the microscopist wishing to push the performance of their instrument just that little bit further.
57

Úloha proteinu p130CAS v integrinové signalizaci / The role of p130CAS in integrin signaling

Janoštiak, Radoslav January 2014 (has links)
Focal adhesions are important subcellular structures that are composed of many signaling and scaffolding proteins. They serve not only for anchoring the cell to the substratum but they are also important signaling centers that regulate various cellular behavior such as migration, invasiveness, proliferation and survival. Focal adhesion signaling needs to be strictly regulated because alteration in activity or expression of many focal adhesion proteins leads to tumorogenesis and metastasis formation. One of the most important scaffolding protein associated with focal adhesion is p130Cas. The importance of p130Cas in regulation of cell migration and invasiveness has been well established. P130Cas also plays important role in regulation of cell survival and proliferation. Moreover, high protein levels of human ortholog of p130Cas - BCAR1, has been linked to more aggressive breast tumors and poor prognosis. During my doctoral studies, I focused on the role of p130Cas in integrin signaling. At the beginning we characterized the role of tyrosine 12 phosphorylation within its SH3 domain. We confirmed that this phosphorylation is increased in Src527F transformed mouse embryonic fibroblasts compared to non-transformed counterparts and also in some human cancer cell lines. We showed that this phosphorylation...
58

Likhet inför lagen? : Undermedveten strukturell diskriminering av etniska minoriteter

Kihlberg, Andreas, Myrin, Nicklas January 2016 (has links)
Inledning: Den skapade bilden av att invandrare skulle vara farligare än den infödda populationen i landet riskerar leda till en undermedveten strukturell diskriminering som genomsyrar det västerländska samhället och således även rättssystemet. Tidigare forskning har visat att etniska minoriteter utsatts för negativ särbehandling vid såväl polisens ingripande som vid domstolens beslut. Denna särbehandling kan tänkas leda till en förlust av rättssystemets legitimitet och därmed till en ökad brottslighet i samhället. Som teoretiskt ramverk för problemet användes social conditioning theory och focal concerns theory. Syfte: Att undersöka huruvida det bland svenska juriststudenter förekommer negativ särbehandling av etniska minoriteter. Metod: En enkätstudie genomfördes på totalt 210 juriststudenter från fyra universitet i Sverige. Enkäten bestod av två fallbeskrivningar med åtta frågor till respektive fallbeskrivning. Av urvalet fick 104 studenter läsa om gärningsmän med typiskt skandinaviska namn och 106 studenter fick läsa om gärningsmän med typiskt arabiska namn. Mann Whitney-U test genomfördes mellan respondenterna som läst om skandinaviska respektive arabiska gärningsmän. Därtill undersöktes Spearmans rangkorrelation mellan respondenternas attityder till våldsbrott. Resultat: Vid grov misshandel uppfattades gärningsmannen med arabiskt namn vara farligare för samhället än gärningsmannen med skandinaviskt namn. Vidare fanns tendenser till att respondenterna undermedvetet uppfattade gärningsmannen med arabiskt namn som mer förekommande vid rån än gärningsmannen med skandinaviskt namn. Diskussion: Respondenterna visade tendenser till undermedvetna fördomar om etniska minoriteter, men lät inte dessa fördomar påverka det valda straffet. Resultatet visar att stereotypa fördomar kan finnas på ett undermedvetet plan, vilket torde kunna leda till negativ särbehandling i vissa situationer när det kommer till domstolsfrågor. Resultaten är i linje med tidigare forskning och studiens teoretiska ramverk, men påvisar samtidigt den komplexitet som ligger bakom problemet. / <p>2016-06-01</p>
59

Development of an automated system for the measurement of focal ratio degradation of high numerical aperture fibres

Lee, Jooyoung 07 August 2019 (has links)
The thesis presents the development and testing of an automated fibre optic test system for the measurement of focal ratio degradation (FRD) in high numerical aperture fibres. In particular, the fibres under examination are being proposed for use in the Maunakea Spectroscopic Explorer (MSE), a new telescope currently being designed for wide-field surveys of the night sky. A critical subsystem of the MSE is the Fiber Transmission System (FiTS) that connects the focal plane to the telescope’s spectrographs. In preparation for MSE-FiTS, a method of characterizing the focal ratio degradation (FRD), between the input and output of every fibre, of candidate multi-mode fibres is highly important. The ultimate goal is the testing of all 4,332 fibres after assembly and prior to installation on MSE. An optical bench has been constructed to test the performance of an automated characterization system; a variation on the collimated beam test. Herein we present the underlying analysis FRD measurement method, the optical design of the test bench, the motion control system and the software for measuring FRD, and controlling the automated test system. The open-source automation software is also introduced; the Big FiTS Fibre Wrapper (Big FFW). The results of tests performed using the Big FFW on samples of candidate fibres are presented and compared with the results in the literature using manual methods. The results suggest that the candidate MSE fibre meets the science requirement of less than 5% focal ratio degradation for an f/2 input beam measured at the fibre output. There is less than 1% disagreement between the automated measurement method and manual methods reported in the literature. The fully automated system can measure the FRD of up to 10 fibres in a typical MSE fibre bundle configuration. / Graduate
60

Simulação computacional da nitidez de imagens radiológicas para controle de qualidade / not available

Oliveira, Henrique Jesus Quintino de 24 March 1995 (has links)
O Trabalho de pesquisa consiste em desenvolver um sistema de avaliação de qualidade de imagens radiológicas que não apresente os problemas dos métodos atualmente disponíveis e principalmente ofereça para o radiologista urna relação entre as características do seu sistema e a nitidez da imagem. Os fatores que mais influenciam a qualidade da imagem são a característica de campo e o tamanho do ponto focal. Estes assuntos foram, portanto, principalmente estudados na revisão bibliográfica, atualmente utilizados imagem junto com os principais métodos para avaliação da qualidade da imagem. O novo método, desenvolvido utilizando simulação computacional, apresenta a imagem do ponto focal e do objeto radiografado, de qualquer forma e qualquer tamanho, para qualquer posição do campo de raios-X. A imagem do objeto é dada com os contornos em tons de cinza que representam bem a nitidez da imagem real. / The aim of this work is the development of a system to evaluate radiologic images quality, without the constraints of the current available methods. Furthermore, the new proposed technique should present to the radiologist a relationship between the radiologic system characteristics and its image sharpness. The main parameters which affect the radiologic image quality are the field characteristic and the focal spot size. Therefore, both issues were studied and presented in the text, beside the main methods currently used to evaluate the image quality. The new method, which uses computational simulation, shows the images of focal spot and of the radiographed object, taking into account objects of any shape and size, and for any X-ray field location. The image is shown with grey scale boundaries which are a good representation of the actual image.

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