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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

Is Speed a Magnitude? : Neurocognitive Estimations of Speed and its’ Connection to Time, Space and Numeric/Quantity Estimations / Är Hastighet en Magnitud? : Neurokogntiva Estimat av Hastighet och Dess Koppling till Estimat av Tid, Rymd, och Nummer/Kvanta

Alvinge, Björn January 2018 (has links)
Associations between space, time, numbers and quantities have suggested that there must be a shared representational format which underlies them. One of the more prominent theories of an underlying system of representation is that of ATOM, which suggests that the there exists a generalized system of magnitude which processes these dimensions. However, there has been no study that examines whether speed is also processed within such a system. This study investigates this by seeing if a SNARC or Problem-Size effect arise in two speed estimation tests. The fundamental task for the participants in both tests was to judge which of two stimuli was the fastest, with the stimuli moving towards a wall located in the center of a computer screen. Their correct discrimination and response time was recorded. The results found that there were no significant results for either effect. This might be due to low sample size, methodological difficulties, and low robustness. Future research might amend these difficulties by having a more consistent setup with more trials reflecting the effect being tested and fix some potential problems with the test environment.
62

The Effects of Reinforcement Magnitude and Temporal Contingencies on Pre-Ratio Pause Duration

Bonem, Marilyn K. 01 May 1988 (has links)
The present study was conducted to determine whether conjugate magnitude and temporal contingencies were effective in increasing the pre-ratio pause (PRP) duration and to determine the controlling variables that govern such contingencies. It has been reported in the literature that magnitude of reinforcement, if presented contingently, is effective in controlling performance and that inserting intervals of blackout (BO), during which responding does not lead to reinforcement, virtually always leads to control of responding, even though it has not been presented contingently. The conjugate schedules experimentally arranged reinforcement such that the longer the PRP, the longer was the duration of access to reinforcement and/or the shorter was the BO, located either after reinforcement or after the response. The results of this study demonstrated that the major independent variable which controlled mean PRP duration on the various conjugate reinforcement schedules studied was the delay between the response and reinforcement. The duration of the PRP was not reliably controlled by a contingency which equated PRP duration with reinforcement duration, nor by a contingency which, through imposition of a delay to trial onset, held the local delay to reinforcement constant. Additionally, cycle-to-cycle variation in reinforcement magnitude, whether presented contingently or noncontingently on PRP duration, had no reliable effect on PRP duration when compared to FR 1. The primary effect of variation in the duration of reinforcement was to reduce the variability, not the duration, of the PRP. The results of the study are briefly discussed in terms of a number of theories. These include: the maximization account (Logan, 1960); the matching law (Herrnstein, 1970); Harzem and Harzem's (1981) theory describing the unconditioned inhibitory stimulus function of reinforcement; behavioral contrast (Reynolds, 1961); and Dews' (1981) account of the importance of a response-reinforcer contiguity relation.
63

THE APPLICATION OF SPECTRAL AND CROSS-SPECTRAL ANALYSIS TO SOCIAL SCIENCES DATA

Vowels, Matthew James 01 January 2018 (has links)
The primary goal of this paper is to demonstrate the application of a relatively esoteric and interdisciplinary technique, called spectral analysis, to dyadic social sciences data. Spectral analysis is an analytical and statistical technique, commonly used in engineering, that allows times series data to be analyzed for the presence of significant regular/periodic fluctuations/oscillations. These periodic fluctuations are reflected in the frequency domain as amplitude or energy peaks at certain frequencies. Furthermore, a Magnitude Squared Coherence analysis may be used to interrogate more than one time series concurrently in order to establish the degree of frequency domain correlation between the two series, as well to establish the phase (lead/lag) relationship between the coherent frequency components. In order to demonstrate the application of spectral analysis, the current study utilizes a secondary dyadic dataset comprising 30 daily reports of perceived sexual desire for 65 couples. The secondary goal of this paper is to establish a) whether there is significant periodic fluctuation in perceived levels of sexual desire for men and/or women, and at which specific frequencies, and b) how much correlation or `cross-spectral coherence' there is between partners' sexual desire within the dyads, and c) what the phase lead-lag relationship is between the partners at any of the identified frequency components. Sexual desire was found to have significant periodic components for both men and women, with a fluctuation of once per month being the most common frequency component across the groups of individuals under analysis. Mathematical models are presented in order to describe and illustrate these principal fluctuations. Partners in couples, on average, were found to fluctuate together at a number of identified frequencies, and the phase lead/lag relationships of these frequencies are presented.
64

Evaluation of Synthetic Unit Hydrograph Techniques For Utah Probable Maximum Flood Determinations

Shammet, Ashraf Mohammed 01 May 1995 (has links)
Every dam must be capable of safely passing a predetermined flood magnitude. For high-hazard dams, it is a common practice to require that this flood be the Probable Maximum Flood (PMF). The determination of the PMF starts with the determination of the Probable Maximum Precipitation (PMP). We used the generalized estimates of the PMP as outlined in Hydrometeorological Report (HMR) 49. In this study we used the storm event model approach to convert the PMP into PMF. Different synthetic unit hydrograph (SUH) techniques were then used in the conversion process. The Soil Conservation Service (SCS) curve number method was used to estimate the losses, and the U.S. Bureau of Reclamation (USBR) lag time relationship was used as the basis for estimating the time parameters for the different (SUH) methods. The objectives of this study were 1) to evaluate the theoretical and empirical basis for the SUH methods that are commonly used for Utah PMF determinations; 2) to compare the PMF determinations for representative Utah watersheds based on alternative SUH methods using Geographic Information System (GIS) techniques, and to explore the effects of parameter uncertainty ; and 3) to make recommendations for the selection and use of SUH methods for Utah PMF determinations. An interactive PMF modeling system was formulated. The modeling system processes the different databases and estimates the parameters required for HEC 1 model input to produce the PMF hydrograph. Five SUHs were used, tbe SCS, Clark, Snyder, USBR, and the Corps of Engineers (COE) LA valley S-graph. Seven representative Utah high-hazard dam sites were selected and used in the evaluation of the five SUH techniques, focusing on their procedure, practice and applicability, and analytical and empirical evaluations. GIS procedures proved to be a very efficient and flexible means for obtaining rainfall-runoff model inputs. Deviation of the site-specific time-area curve from the default curve in HEC 1 leads to errors in the peak flow estimate. In the absence of suitable events for site-specific development of unit hydrographs, the USBR SUH technique is to be used, but careful consideration should be given to the appropriateness of the use of local storm K, values for Utah local storm PMFs.
65

A Study of Life Crisis Magnitude of Psychiatric Patients and a Non-Therapy Group

Morris, Helen B. 01 May 1968 (has links)
A group of hospitalized psychiatric patients and a randomly selected non-therapy group responded to the Schedule of Recent Experiences questionniare. In order to determine the magnitude of life change events for the two groups, Life Change Unit totals were derived for the years 1966 and 1967. To test the hypothesis that patients in psychiatric treatment have experienced a quantitatively significant greater amount of life change than a group of non-therapy subjects, an analysis of variance was used to determine whether there were significant differences between the scores for the two groups. For the year 1966, no significant difference was found between the therapy and non-therapy samples. For the year 1967, there was a significant difference between the mean Life Change Unit scores for the two groups. As a result of these findings, it is concluded that an accumulation of life change events may serve to precipitate mental health change, and that that probability of such health change occurring is significantly greater when there is a clustering of life change events during any given year than when such a clustering does not occur.
66

Short-Time Phase Spectrum in Human and Automatic Speech Recognition

Alsteris, Leigh, n/a January 2006 (has links)
Incorporating information from the short-time phase spectrum into a feature set for automatic speech recognition (ASR) may possibly serve to improve recognition accuracy. Currently, however, it is common practice to discard this information in favour of features that are derived purely from the short-time magnitude spectrum. There are two reasons for this: 1) the results of some well-known human listening experiments have indicated that the short-time phase spectrum conveys a negligible amount of intelligibility at the small window durations of 20-40 ms used for ASR spectral analysis, and 2) using the short-time phase spectrum directly for ASR has proven di?cult from a signal processing viewpoint, due to phase-wrapping and other problems. In this thesis, we explore the possibility of using short-time phase spectrum information for ASR by considering the two points mentioned above. To address the ?rst point, we conduct our own set of human listening experiments. Contrary to previous studies, our results indicate that the short-time phase spectrum can indeed contribute signi?cantly to speech intelligibility over small window durations of 20-40 ms. Also, the results of these listening experiments, in addition to some ASR experiments, indicate that at least part of this intelligibility may be supplementary to that provided by the short-time magnitude spectrum. To address the second point (i.e., the signal processing di?culties), it may be necessary to transform the short-time phase spectrum into a more physically meaningful representation from which useful features could possibly be extracted. Speci?cally, we investigate the frequency-derivative (or group delay function, GDF) and the time-derivative (or instantaneous frequency distribution, IFD) as potential candidates for this intermediate representation. We have performed various experiments which show that the GDF and IFD may be useful for ASR. We conduct several ASR experiments to test a feature set derived from the GDF. We ?nd that, in most cases, these features perform worse than the standard MFCC features. Therefore, we suggest that a short-time phase spectrum feature set may ultimately be derived from a concatenation of information from both the GDF and IFD representations. For best performance, the feature set may also need to be concatenated with short-time magnitude spectrum information. Further to addressing the two aforementioned points, we also discuss a number of other speech applications in which the short-time phase spectrum has proven to be very useful. We believe that an appreciation for how the short-time phase spectrum has been used for other tasks, in addition to the results of our research, will provoke fellow researchers to also investigate its potential for use in ASR.
67

Metamaterial : A field magnitude dependent and frequency independent model

Ardavan, Mehdi January 2008 (has links)
<p>In all attempts to analyze and realize Left-Handed materials, so far, most researchers have used the same idea of extracting only some or certain behaviors of Metamaterials from a set of unit cells gathered together in a designed order. Nevertheless meeting all criteria in order to consider a media as real double-negative material has never come true.</p><p>Starting with criticizing and arguing the validity of calling any set of unit cells as a medium of propagation, the work at hand will go further demonstrating analogies between a medium which could be assigned permittivity or permeability factors and the medium consisting a set of unit cells.</p><p>After presenting the critical analysis on previous studies in the field, here it is shown that it is impossible to build Metamaterials using any number of passive unit cells. A deep insight into the concept of phase and group velocities as well as Poynting’s vector will reveal weakness of the public perception of their relation with each other. Unlike the past and current trend in analyzing these two velocities in meta-materials, they will be proven to possess the same direction.</p><p>Moreover, in this work, a solid proof over violation of energy conservation in the intersection plane between a normal material and a Left Handed material is presented which requires us to believe and accept generation of energy at this plane. This view will consequently leave meaningless all attempts to build meta-materials by passive elements.</p><p>In present work a method is proposed at which a material with positive permittivity and permeability can behave like and yield all characteristics of Metamaterials only if the foregoing parameters, while remaining positive, can vary and be governed by the magnitude of the electromagnetic field. Independence of this method from frequency broadens the range of its application and also the interest it may attract.</p>
68

Metamaterial : A field magnitude dependent and frequency independent model

Ardavan, Mehdi January 2008 (has links)
In all attempts to analyze and realize Left-Handed materials, so far, most researchers have used the same idea of extracting only some or certain behaviors of Metamaterials from a set of unit cells gathered together in a designed order. Nevertheless meeting all criteria in order to consider a media as real double-negative material has never come true. Starting with criticizing and arguing the validity of calling any set of unit cells as a medium of propagation, the work at hand will go further demonstrating analogies between a medium which could be assigned permittivity or permeability factors and the medium consisting a set of unit cells. After presenting the critical analysis on previous studies in the field, here it is shown that it is impossible to build Metamaterials using any number of passive unit cells. A deep insight into the concept of phase and group velocities as well as Poynting’s vector will reveal weakness of the public perception of their relation with each other. Unlike the past and current trend in analyzing these two velocities in meta-materials, they will be proven to possess the same direction. Moreover, in this work, a solid proof over violation of energy conservation in the intersection plane between a normal material and a Left Handed material is presented which requires us to believe and accept generation of energy at this plane. This view will consequently leave meaningless all attempts to build meta-materials by passive elements. In present work a method is proposed at which a material with positive permittivity and permeability can behave like and yield all characteristics of Metamaterials only if the foregoing parameters, while remaining positive, can vary and be governed by the magnitude of the electromagnetic field. Independence of this method from frequency broadens the range of its application and also the interest it may attract.
69

The Design of Table-centric Interactive Spaces

Wigdor, Daniel 26 February 2009 (has links)
The Design of Table-Centric Interactive Spaces, by Daniel J. Wigdor A thesis submitted in partial conformity with the requirements for the degree of Doctor of Philosophy Graduate Department of Computer Science, University of Toronto © Copyright by Daniel J. Wigdor, 2008 Direct-touch tabletops offer compelling uses as direct, multi-touch, multi-user displays for face to face collaborative work. As task complexity and group size increase, the addition to the tabletop of multiple, vertical displays allows for more information content, while reducing the need to multiplex the tabletop display area. We dub such systems table-centric interactive spaces. Although compelling, these spaces offer unique challenges. In particular, the displays in such spaces are seen by the users at angles not typically found in combination in other environments. First, the viewing imagery shown on a horizontal display by seated participants means that that imagery is distorted, receding away from the users’ eyes. Second, the sharing of information by users sitting around a horizontal display necessitates that on-screen content be oriented at non-optimal angles for some subset of those users. Third, positioning vertical displays around the table means that some subset of the seated users will be looking at those displays at odd angles. In this thesis, we investigate the challenges associated with these viewing angles. We begin with a examination of related work, including tabletop technology and interaction techniques. Next, we report the results of controlled experiments measuring performance of reading, graphical perception, and ancillary display control under the angles we identified. Next, we present a set of design issues encountered in our work with table-centric spaces. We then review a series of interaction techniques built to address those issues. These techniques are evaluated through the construction and validation of an application scenario. Through these examinations, we hope to provide designers with insights as to how to enable users to take full advantage of ancillary displays, while maintaining the advantages and affordances of collocated table-centric work.
70

Cellular and Molecular Mechanism Underlying the Effect of Low-magnitude, High-frequency Vibration on Bone

Lau, Esther Yee Tak 27 July 2010 (has links)
An emerging non-pharmacological treatment for bone degenerative diseases is whole body vibration (WBV), a mechanical signal composed of low-magnitude, high-frequency (LMHF) vibrations that when applied to bone, have osteogenic and anti-resorptive effects. Currently, the cellular and molecular mechanism underlying the effect of WBV on bone is unclear. In this study, we investigated the response of osteocytes, the putative mechanosensor in bone, under LMHF vibration. As bone cells differentiate from mesenchymal stromal cells (MSCs), we also studied the osteogenic differentiation of rat MSCs in the presence of vibration loading. We found that vibrated osteocytes show gene and protein expression changes suggestive of an anti-osteoclastogenic response, and secrete soluble factors that inhibit osteoclast formation and activity. In contrast, rat MSCs showed moderate to no response to LMHF vibration during osteogenic differentiation. Our data suggest that in vivo effects of LMHF vibration are mediated through mechanosensing and biochemical responses by osteocytes.

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