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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.
41

Développement d'un microscope super-résolution pour l'imagerie de l'activité neuronale

Deschênes, Andréanne 01 February 2021 (has links)
L’étude de la neurotransmission et de la plasticité synaptique à l’échelle biomoléculaire dans des cellules vivantes nécessite des outils qui permettent la visualisation et la localisation d’une grande variété de protéines synaptiques ainsi que d’autres composantes. La transparence des neurones, la taille nanométrique des structures d’intérêt et leur compacité motivent le choix des modalités d’imagerie pouvant servir à étudier ces phénomènes. La microscopie à super-résolution en fluorescence produit des images ayant une résolution de localisation de l’ordre du nanomètre d’échantillons marqués. Toutefois, cette technique ne permet d’observer que les structures ayant été marquées. C’est pourquoi nous voulons la combiner à une technique ne nécessitant aucun marquage afin d’obtenir le plus d’information possible au sujet de la structure des échantillons. L’imagerie de phase quantitative est une technique sans-marquage qui utilise l’indice de réfraction comme agent de contraste intrinsèque pour cartographier en 3D le contenu cellulaire. Le but principal de ce projet est de concevoir et construire un montage de microscopie de phase quantitative et de l’intégrer à un microscope STED existant de façon à créer un nouveau système d’imagerie multimodale. La performance de ce système sera ensuite caractérisée et sa capacité à produire des images multimodales de synapses de cellules vivantes sera évaluée. Ce projet est un premier pas vers la création d’un outil qui pourrait permettre de simultanément mesurer de façon très précise la position de structures marquées en 2D et 3D et cartographier l’indice de réfraction des cellules en 3D afin de situer les structures marquées dans leur environnement. / The study of neurotransmission at the biomolecular level in live cells requires tools that allow the simultaneous visualisation and localization of a variety of neuronal proteins at their scale: the nanometric scale. In order to do so, an imaging approach offering high spatial and temporal resolution combined to low invasiveness is required. STED microscopy is an optical super-resolution fluorescence microscopy technique that produces images of labelled samples with a spatial resolution below 50 nm in living cells. However, since it is based on the detection of fluorescent molecules, labeling of the structures of interestis necessary and non-labeled structures are invisible for this type of microscope. Therefore, we want to combine it to a label-free optical microscopy technique to maximize the information that can be obtained about the global structure of the samples of interest: optical diffraction tomography (ODT). This approach uses refractive index as an intrinsic contrast agent to produce 3D maps of the cell’s internal contents.The main goal of this project is to design and build a quantitative phase imaging system and to integrate it onto an existing STED microscope to create a novel multimodal super-resolution imaging system. The performance of the microscope will then be characterized. This project is a first step towards the creation of a tool that could eventually allow simultaneous precise2D and 3D mapping of labelled structures and label-free 3D mapping of the sample’s refractive index to situate marked structures in their surroundings.
42

Use of scanning electron microscopy to evaluate cereal grains and their mill fractions

Cashman, William Elliot January 2011 (has links)
Digitized by Kansas Correctional Industries
43

A programmable image processor

Atkin, Philip January 1989 (has links)
No description available.
44

Transport imaging for the study of quantum scattering phenomena in next generation semiconductor devices

Bradley, Frank Mitchell 12 1900 (has links)
Approved for public release; distribution is unlimited / The minority carrier diffusion length is a critical parameter in the development of next generation Heterostructure Bipolar Transistors (HBT) and highly efficient solar cells. A novel technique has been developed utilizing direct imaging of electron/hole recombination via an optical microscope and a high sensitivity charge coupled device coupled to a scanning electron microscope to capture spatial information about the transport behavior (diffusion lengths/drift lengths) in luminescent solid state materials. In this work, a numerical model was developed to do a multi-parameter least squares analysis of transport images. Results were applied to the study of transport in materials at the forefront of device technology that are affected by quantum scattering effects, where few reliable experimental measurements exist. The technique allows for easy localization of the measurement site, broad application to a range of materials and potential industrial automation to aid electronics for terahertz devices. / Outstanding Thesis
45

Analysis of the failure of a vacuum spin-pit drive turbine spindle shaft

Pettitt, Jason M. 09 1900 (has links)
The Naval Postgraduate School's Rotor Spin Research Facility experienced a failure in the Spring of 2005 in which the rotor dropped from the drive turbine and caused extensive damage. A failure analysis of the drive turbine spindle shaft was conducted in order to determine the cause of failure: whether due to a material or design flaw. Also, a dynamic analysis was conducted in order to determine the natural modes present in the system and the associated frequencies that could have contributed to the failure of the shaft. It was concluded that the failure was due to low cycle fatigue, a possible stress concentration was identified, and a torsional mode was found near the speed at which failure occurred.
46

A COMPARISON OF THE SQUARE WAVE RESPONSE OF THREE MICROSCOPES COMMONLY USED IN PHOTOINTERPRETATION

Hooker, R. Brian 15 May 1970 (has links)
QC 351 A7 no. 53 / The optical performance of three stereomicroscopes commonly used for photo - interpretation is described in terms of magnification, field of view, and square wave response (SqWR). For a given field size, the SqWR can be used to compare the amount of information in the image of each microscope. The SqWR was determined by scanning a square wave test target at four field positions for each of four field sizes (corresponding to magnifications of 6, 12, 25, and 50X). The measured SqWR was used to evaluate the relative ability of each microscope to perform two typical photointerpretation tasks: (1) detailed viewing of a target, and (2) scanning or searching for a target. For these tasks the Wild M -5 stereomicroscope was found to be somewhat better than the Bausch and Lomb 240 stereomicroscope, and both were found to be superior to the Olympus SZ III stereomicroscope. The SqWR curves are included and can be used to compare the stereo - microscopes for various photointerpretation tasks.
47

Finding the minimum test set with the optimum number of internal probe points.

January 1996 (has links)
by Kwan Wai Wing Eric. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references. / ABSTRACT / ACKNOWLEDGMENT / LIST OF FIGURES / LIST OF TABLES / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Background --- p.1-1 / Chapter 1.2 --- E-Beam testing and test generation algorithm --- p.1-2 / Chapter 1.3 --- Motivation of this research --- p.1-4 / Chapter 1.4 --- Out-of-kilter Algorithm --- p.1-6 / Chapter 1.5 --- Outline of the remaining chapter --- p.1-7 / Chapter Chapter 2 --- Electron Beam Testing / Chapter 2.1 --- Background and Theory --- p.2-1 / Chapter 2.2 --- Principles and Instrumentation --- p.2-4 / Chapter 2.3 --- Implication of internal IC testing --- p.2-6 / Chapter 2.4 --- Advantage of Electron Beam Testing --- p.2-7 / Chapter Chapter 3 --- An exhaustive method to minimize test sets / Chapter 3.1 --- Basic Principles --- p.3-1 / Chapter 3.1.1 --- Controllability and Observability --- p.3-1 / Chapter 3.1.2 --- Single Stuck at Fault Model --- p.3-2 / Chapter 3.2 --- Fault Dictionary --- p.3-4 / Chapter 3.2.1 --- Input Format --- p.3-4 / Chapter 3.2.2 --- Critical Path Generation --- p.3-6 / Chapter 3.2.3 --- Probe point insertion --- p.3-8 / Chapter 3.2.4 --- Formation of Fault Dictionary --- p.3-9 / Chapter Chapter 4 --- Mathematical Model - Out-of-kilter algorithm / Chapter 4.1 --- Network Model --- p.4-1 / Chapter 4.2 --- Linear programming model --- p.4-3 / Chapter 4.3 --- Kilter states --- p.4-5 / Chapter 4.4 --- Flow change --- p.4-7 / Chapter 4.5 --- Potential change --- p.4-9 / Chapter 4.6 --- Summary and Conclusion --- p.4-10 / Chapter Chapter 5 --- Apply Mathematical Method to minimize test sets / Chapter 5.1 --- Implementation of OKA to the Fault Dictionary --- p.5-1 / Chapter 5.2 --- Minimize test set and optimize internal probings / probe points --- p.5-5 / Chapter 5.2.1 --- Minimize the number of test vectors --- p.5-5 / Chapter 5.2.2 --- Find the optimum number of internal probings --- p.5-8 / Chapter 5.2.3 --- Find the optimum number of internal probe points --- p.5-11 / Chapter 5.3 --- Fixed number of internal probings/probe points --- p.5-12 / Chapter 5.4 --- True minimum test set and optimum probing/ probe point --- p.5-14 / Chapter Chapter 6 --- Implementation and work examples / Chapter 6.1 --- Generation of Fault Dictionary --- p.6-1 / Chapter 6.2 --- Finding the minimum test set without internal probe point --- p.6-5 / Chapter 6.3.1 --- Finding the minimum test set with optimum internal probing --- p.6-10 / Chapter 6.3.2 --- Finding the minimum test set with optimum internal probe point --- p.6-24 / Chapter 6.4 --- Finding the minimum test set by fixing the number of internal probings at 2 --- p.6-26 / Chapter 6.5 --- Program Description --- p.6-35 / Chapter Chapter 7 --- Realistic approach to find the minimum solution / Chapter 7.1 --- Problem arising in exhaustive method --- p.7-1 / Chapter 7.2 --- Improvement work on existing test generation algorithm --- p.7-2 / Chapter 7.3 --- Reduce the search set --- p.7-5 / Chapter 7.3.1 --- Making the Fault Dictionary from existing test generation algorithm --- p.7-5 / Chapter 7.3.2 --- Making the Fault Dictionary by random generation --- p.7-9 / Chapter Chapter 8 --- Conclusions / Chapter 8.1 --- Summary of Results --- p.8-1 / Chapter 8.2 --- Further Research --- p.8-5 / REFERENCES --- p.R-1 / Chapter Appendix A --- Fault Dictionary of circuit SC1 --- p.A-1 / Chapter Appendix B --- Fault Dictionary of circuit SC7 --- p.B-1 / Chapter Appendix C --- Simple Circuits Layout --- p.C-1
48

An assessment of the transmission electron microscope for the study of aerosol-gas interactions : direct observations of sodium chloride hydration phenomena

Clarke, Antony David 01 January 1978 (has links)
An experimental study of solid-gas interactions was made for sodium chloride particles, using a specially fabricated environmental chamber in a transmission electron microscope. It was found that under suitable conditions the hydration and dehydration of these particles could be directly observed and quantitatively measured. Measurements of growth were obtained with a time resolution of one-thirtieth of a second for particles having diameters ranging from 0.02 μm to 1.0 μm.
49

Toward the standardization of use-wear studies: constructing an analogue to prehistoric hide work

Wiederhold, James Edward 30 September 2004 (has links)
This thesis is a use-wear study that deals with microwear on stone endscrapers used on one worked material: animal skins. The first part of the study defines and describes the process of rendering freshly skinned pelts into functional leather or rawhide products, addressing confusing terminology found in the literature as well. Problems with past use-wear experiments dealing with animal skins are also confronted and explained. The second part of the study examines endscrapers used to flesh and dehair bison hides and compares the use-wear traces left on the tool edge by each activity. This suite of characteristics is then compared to those found on an assemblage of Clovis-age scrapers from the Gault site in central Texas.
50

Some applications of electron beam deposition to biophysical analysis

Everts, James Mitchell, 1940- January 1967 (has links)
No description available.

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