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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.
11

Mean curvature flow for Lagrangian submanifolds with convex potentials

Zhang, Xiangwen, 1984- January 2008 (has links)
No description available.
12

Gauged Linear Sigma Model and Mirror Symmetry

Gu, Wei 02 July 2019 (has links)
This thesis is devoted to the study of gauged linear sigma models (GLSMs) and mirror symmetry. The first chapter of this thesis aims to introduce some basics of GLSMs and mirror symmetry. The second chapter contains the author's contributions to new exact results for GLSMs obtained by applying supersymmetric localization. The first part of that chapter concerns supermanifolds. We use supersymmetric localization to show that A-twisted GLSM correlation functions for certain supermanifolds are equivalent to corresponding Atwisted GLSM correlation functions for hypersurfaces. The second part of that chapter defines associated Cartan theories for non-abelian GLSMs by studying partition functions as well as elliptic genera. The third part of that chapter focuses on N=(0,2) GLSMs. For those deformed from N=(2,2) GLSMs, we consider A/2-twisted theories and formulate the genuszero correlation functions in terms of Jeffrey-Kirwan-Grothendieck residues on Coulomb branches, which generalize the Jeffrey-Kirwan residue prescription relevant for the N=(2,2) locus. We reproduce known results for abelian GLSMs, and can systematically calculate more examples with new formulas that render the quantum sheaf cohomology relations and other properties manifest. We also include unpublished results for counting deformation parameters. The third chapter is about mirror symmetry. In the first part of the third chapter, we propose an extension of the Hori-Vafa mirrror construction [25] from abelian (2,2) GLSMs they considered to non-abelian (2,2) GLSMs with connected gauge groups, a potential solution to an old problem. We formally show that topological correlation functions of B-twisted mirror LGs match those of A-twisted gauge theories. In this thesis, we study two examples, Grassmannians and two-step flag manifolds, verifying in each case that the mirror correctly reproduces details ranging from the number of vacua and correlations functions to quantum cohomology relations. In the last part of the third chapter, we propose an extension of the Hori-Vafa construction [25] of (2,2) GLSM mirrors to (0,2) theories obtained from (2,2) theories by special tangent bundle deformations. Our ansatz can systematically produce the (0,2) mirrors of toric varieties and the results are consistent with existing examples which were produced by laborious guesswork. The last chapter briefly discusses some directions that the author would like to pursue in the future. / Doctor of Philosophy / In this thesis, I summarize my work on gauged linear sigma models (GLSMs) and mirror symmetry. We begin by using supersymmetric localization to show that A-twisted GLSM correlation functions for certain supermanifolds are equivalent to corresponding A-twisted GLSM correlation functions for hypersurfaces. We also define associated Cartan theories for non-abelian GLSMs. We then consider N =(0,2) GLSMs. For those deformed from N =(2,2) GLSMs, we consider A/2-twisted theories and formulate the genus-zero correlation functions on Coulomb branches. We reproduce known results for abelian GLSMs, and can systematically compute more examples with new formulas that render the quantum sheaf cohomology relations and other properties are manifest. We also include unpublished results for counting deformation parameters. We then turn to mirror symmetry, a duality between seemingly-different two-dimensional quantum field theories. We propose an extension of the Hori-Vafa mirror construction [25] from abelian (2,2) GLSMs to non-abelian (2,2) GLSMs with connected gauge groups, a potential solution to an old problem. In this thesis, we study two examples, Grassmannians and two-step flag manifolds, verifying in each case that the mirror correctly reproduces details ranging from the number of vacua and correlations functions to quantum cohomology relations. We then propose an extension of the HoriVafa construction [25] of (2,2) GLSM mirrors to (0,2) theories obtained from (2,2) theories by special tangent bundle deformations. Our ansatz can systematically produce the (0,2) mirrors of toric varieties and the results are consistent with existing examples. We conclude with a discussion of directions that we would like to pursue in the future.
13

How do healthy individuals adapt to reversed vision generated when using mirror specs? : an investigation into mirror devices, adaptation to body schema and imagery ability in healthy participants

Walker, Joanna Louise January 2010 (has links)
Introduction: This study investigates a new form of Mirror Therapy (MT), the Mirror Specs. Evidence suggests that MT is a non-invasive, cost effective method of reducing pain and increasing functioning in some chronic pain conditions. There is no clear explanation for the underlying mechanisms of MT, however, a plausible hypothesis suggests that adaptation to the Body Schema is an integral component. Aims and Hypotheses: The current study examined Body Schema adaptation in healthy participants when performing a Finger Tapping Task with both Mirror Specs and a Mirror Box. It was hypothesised that adaptation would be indicated by increases in Reaction Times (RTs) and Error Rates when comparing unimanual phases of a Finger Tapping Task, following a bimanual „adaptation‟ phase. It was hypothesised that there would be no difference between participants‟ ability to adapt to each device. Finally, the study proposed that there would be a relationship between the adaptation observed on the Finger Tapping Task and participants individual imagery abilities. Method: Participants performed 4 phases of a Finger Tapping Task with alternate bimanual and unimanual phases when using both the Mirror Specs and Mirror Box. Imagery abilities were measured using self-report questionnaires and a Motor Imagery computer task. Results and Discussion: Repeated Measures ANOVAs revealed reductions in RTs and Error Rates in Phase 3 compared to Phase 1 on the Finger Tapping Task. There were no differences between RTs and Error Rates when using the Mirror Specs and Mirror Box. These findings suggest that healthy participants were able to use each Mirror Device effectively and this provide impetus for the proposal that Mirror Specs could provide a practical, cost effective addition to rehabilitation services. Finally, there were no clinically significant relationships between use of the Mirror Devices and imagery abilities, thereby indicating imagery abilities did not influence how participants adapted to using the Mirror Devices.
14

The Mirror Neuron System and Its Role in Autism Spectrum Disorder

Westlund, Kristina January 2009 (has links)
The discovery of mirror neurons and the mirror neuron system is one of the most interesting breakthroughs in the field of neuroscience in recent years. The topic stretches over a wide spectrum of research fields but one of the more prominent areas is concerned with the role of mirror neurons in autism spectrum disorder. It is hypothesized that an impaired mirror neuron system may be one of the main causes underlying the deficits seen in autistic individuals. Parallel to the broken mirror theory of autism there are critical voices claiming there is not enough empirical evidence to support such a theory. Research carried out in the area seems to offer support for both contradictory approaches making it hard to conclude the definite role of mirror neurons in this developmental disorder. Future research may offer conclusive answers concerning the role of the mirror neuron system in autism spectrum disorder as well as other important questions regarding the functional properties of the brain areas under question.
15

The Mirror Neuron System and Its Role in Autism Spectrum Disorder

Westlund, Kristina January 2009 (has links)
<p>The discovery of mirror neurons and the mirror neuron system is one of the most interesting breakthroughs in the field of neuroscience in recent years. The topic stretches over a wide spectrum of research fields but one of the more prominent areas is concerned with the role of mirror neurons in autism spectrum disorder. It is hypothesized that an impaired mirror neuron system may be one of the main causes underlying the deficits seen in autistic individuals. Parallel to the broken mirror theory of autism there are critical voices claiming there is not enough empirical evidence to support such a theory. Research carried out in the area seems to offer support for both contradictory approaches making it hard to conclude the definite role of mirror neurons in this developmental disorder. Future research may offer conclusive answers concerning the role of the mirror neuron system in autism spectrum disorder as well as other important questions regarding the functional properties of the brain areas under question.</p>
16

Coil Design and Related Studies for the Fusion-Fission Reactor Concept SFLM Hybrid

Hagnestål, Anders January 2012 (has links)
A fusion-fission (hybrid) reactor is a combination of a fusion device and a subcritical fission reactor, where the fusion device acts as a neutron source and the power is mainly produced in the fission core. Hybrid reactors may be suitable for transmutation of transuranic isotopes in the spent nuclear fuel, due to the safety margin on criticality imposed by the subcritical fission core. The SFLM Hybrid project is a theoretical project that aims to point out the possibilities with steady-state mirror-based hybrid reactors. The quadrupolar magnetic mirror vacuum field is based on the Straight Field Line Mirror field and the central cell is 25 m long. A fission mantle surrounds the mirror cell. The fission to fusion power ratio is about 150 with keff = 0.97, implying that almost all the produced energy comes from fission. Beyond each mirror end magnetic expanders are located, which increase the plasma receiving “divertor” area and provide tolerable heat load on wall materials. The plasma is heated with ion cyclotron radio frequency heating and the fission mantle is cooled using a liquid lead-bismuth eutectic. The device is self-sufficient in tritium, and does not seem to suffer from severe material problems. A remaining issue may be the plasma electron temperature, which need to reach about 500 eV for efficient power production.  In this doctoral thesis, theoretical work has been done with the magnetic coil system of such a device and also with the overall concept. A new coil type, the fishbone coil, suitable for single cell quadrupolar mirrors, has been invented. Two vacuum field coil sets with satisfying properties have been found, where the most recent coil set consists of fishbone coils. Finite ß effects on the magnetic field have been investigated, showing that the flux tube ellipticity increases with ß. The ellipticity of the vacuum field increases slightly with radius, but with finite ß it decreases with radius. The maximum flux surface radial extensions decrease with ß, which is an unexpected and beneficial result. A radial invariant has also been identified, and particle simulations have been made to emphasize that quadrupolar mirrors must be symmetric or confinement may be lost.
17

FRAMES OF REFERENCE, THE PERCEPTION OF SYMMETRY AND THE MIRROR ILLUSION (ENANTIOMORPHS).

MAGID, DIANE ALEXIS. January 1986 (has links)
The relationship between symmetry and apparent reversals of enantiomorphic (mirror-reflected) objects was investigated. Subjects were presented with a series of standard and enantiomorphic books with various structural symmetries. The object directions (top-front-right) assigned to standard books were compared with the directions assigned to their enantiomorphs and the axes of apparent reversal determined. The primary finding was that apparent reversals were not limited to the left-right dimension. Reversals of top-bottom and front-back were also obtained. In most cases, apparent reversals occurred along the axis of structural (geometric) symmetry. However, symmetry defined in structural terms did not always predict apparent reversals. In certain cases, subjects perceived reversals most often along the left-right axis, even though (depending on the book) reversals of top-bottom or front-back were equally possible. The concept of perceived symmetry, which includes but is not limited to structural symmetry, is developed. Also, the influence of perceived symmetry on frames of reference is discussed.
18

Atmospheric pressure chemical vapour deposition of titanium nitride from titanium tetrachloride and ammonia

Johnson, Saccha Ellen January 1996 (has links)
No description available.
19

Implementation and customization of a smart mirror through a facial recognition authentication and a personalized news recommendation algorithm

Garcia, Ivette Cristina Araujo, Salmon, Eduardo Rodrigo Linares, Riega, Rosario Villalta, Padilla, Alfredo Barrientos 09 April 2018 (has links)
El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / In recent years the advancement of technologies of information and communication (technology ICTs) have helped to improve the quality of people's lives. The paradigm of internet of things (IoT, Internet of things) presents innovative solutions that are changing the style of life of the people. Because of this proposes the implementation of a smart mirror as part of a system of home automation, with which we intend to optimize the time of people as they prepare to start their day. This device is constructed from a reflective glass, LCD monitor, a Raspberry Pi 3, a camera and a platform IoT oriented cloud computing, where the information is obtained to show in the mirror, through the consumption of web services. The information is customizable thanks to a mobile application, which in turn allows the user photos to access the mirror, using authentication with facial recognition and user information to predict the news to show according to your profile. In addition, as part of the idea of providing the user a personalized experience, the Smart Mirror incorporates a news recommendation algorithm, implemented using a predictive model, which uses the algorithm, naive bayes. / Revisión por pares
20

A Study of The Mirror

Heaberlin, Dick M. 08 1900 (has links)
Because of the lack of authoritative secondary material on the Mirror, the need for deeper study into the content of the Mirror appears necessary. In order to fill this need, this study has been undertaken to provide basic information about the Mirror's subject matter and the attitudes of its contributors.

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