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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.
151

The Hierarchical Organization of Impulse Control: Implications for Decision Making

Coutlee, Christopher Gilbert January 2014 (has links)
<p>The research studies presented as this dissertation constitute a methodologically diverse and conceptually integrative approach to understanding impulsiveness in the context of cognitive control and decision making. Broadly, these findings address the validity of current conceptions of trait impulsiveness, relationships between those traits and brain or laboratory measures of cognitive control, and links between impulsive traits and economic decisions under conditions of delay or uncertainty. The findings presented in this thesis affirm the multidimensional nature of impulsiveness as a construct, and link individual differences in specific impulsive types to behavioral and neurobiological measures of control function. The nature of motor, attentional, and nonplanning impulsive types are contextualized by reference to evidence supporting a broad theory of behavioral control based on hierarchical organization of action, ranging from concrete acts to abstract plans and strategies. We provide evidence linking concrete forms of urgent/motor impulsiveness to behavior and brain activation during response-related control, and more abstract and future-oriented premedititative/nonplanning impulsiveness to strategic control signals in more rostral PFC. Finally, these findings are complemented by causal evidence from a neurostimulation study linking a contextual control network to risky decision making and attentional impulsiveness.</p> / Dissertation
152

Distributed Circuit Techniques for Equalization of Short Multimode Fiber Links

Ng, George Chung Fai 30 July 2008 (has links)
Electronic dispersion compensation (EDC) of intermodal dispersion on short multimode fiber (MMF) links operating at 40 Gb/s is investigated through system level simulations and the design of two analog integrated circuit (IC) equalizers. System simulations using worst-case MMF link models show the effectiveness of a 2-tap baud spaced finite impulse response (FIR) equalizer for 40-m links, and a second-order Tbaud/2 infinite impulse response (IIR) equalizer for 50-m links. An IIR filter topology suitable for IC implementation with double loops and multiple delay sections was developed. The 2-tap FIR and the IIR equalizer are implemented in UMC 0.13-um and STM 90-nm CMOS processes respectively. Measurements demonstrate the FIR and IIR equalizing 38-Gb/s and 30-Gb/s cable channels respectively. To the author's knowledge, the double-loop multi-delay IIR equalizer is the first integrated traveling-wave equalizer utilizing poles as a means of frequency boosting, contrasting the conventional FIR technique of utilizing zeros.
153

Distributed Circuit Techniques for Equalization of Short Multimode Fiber Links

Ng, George Chung Fai 30 July 2008 (has links)
Electronic dispersion compensation (EDC) of intermodal dispersion on short multimode fiber (MMF) links operating at 40 Gb/s is investigated through system level simulations and the design of two analog integrated circuit (IC) equalizers. System simulations using worst-case MMF link models show the effectiveness of a 2-tap baud spaced finite impulse response (FIR) equalizer for 40-m links, and a second-order Tbaud/2 infinite impulse response (IIR) equalizer for 50-m links. An IIR filter topology suitable for IC implementation with double loops and multiple delay sections was developed. The 2-tap FIR and the IIR equalizer are implemented in UMC 0.13-um and STM 90-nm CMOS processes respectively. Measurements demonstrate the FIR and IIR equalizing 38-Gb/s and 30-Gb/s cable channels respectively. To the author's knowledge, the double-loop multi-delay IIR equalizer is the first integrated traveling-wave equalizer utilizing poles as a means of frequency boosting, contrasting the conventional FIR technique of utilizing zeros.
154

Non-destructive evaluation of railway trackbed ballast

De Bold, Robert Paul January 2011 (has links)
The “green agenda” combined with highway congestion has accelerated the demand for increased freight and passenger travel on the world’s railways. These increases have driven demand for more efficient and rapid investigation of trackbed ballast. Network Rail and other rail infrastructure operators spend significant financial sums on inspecting, tamping, adjusting, cleaning, and replacing trackbed ballast. Such maintenance is often to the detriment of normal network operation. Industry requires a method of ballast evaluation that is non-intrusive, cheap, can appraise long stretches of track in a short period of time, and give a fingerprinting result from which time-to-maintenance can be calculated and planned. Thus, the aim was to develop evaluation methods using non-destructive testing techniques. A 10-year old full-scale trackbed composed of variously fouled ballast was re-visited and used for experimentation. The condition of the ballast was calculated using the Ionescu Fouling Index. Earlier research at the University of Edinburgh enabled researchers worldwide to characterise ballast using ground penetrating radar (GPR). This research was repeated, validated and taken forward in a series of GPR experiments on the trackbed using a range of antennas from 500MHz to 2.6GHz. New "scatter" metrics were developed to determine ballast condition from the GPR waveforms. These metrics were then used to predict the Ionescu Fouling Index with a correlation coefficient greater than 0.9. One of the current approaches to evaluating the stiffness of railway ballast is to use a Falling Weight Deflectometer (FWD). The viability of using a Prima 100 mini-FWD on railways to measure stiffness was determined and deemed to be ineffective on ballast. The applicability of the impulse response technique on railways was determined. An instrumented hammer was used to excite the ballast, with a geophone measuring the response. The Frequency Response Function of this was successfully correlated with the Ionescu Fouling Index with a correlation coefficient also greater than 0.9. Finally, using GPR data and measured stiffness data collected by Banverket, Sweden, a numerical model to successfully relate radar responses to stiffness was developed.
155

Determinants of Effort and Associated Cardiovascular Response to a Behavioral Restraint Challenge

Agtarap, Stephanie 12 1900 (has links)
This study directly tested implications of motivation intensity theory on effort to restrain against a behavioral urge or impulse (i.e. restraint intensity). Two factors were manipulated—magnitude of an urge and the importance of successfully resisting it—with cardiovascular (CV) responses related to active coping measured. Male and female undergraduate students were presented with a mildly- or strongly evocative film clip with instructions to refrain from showing any facial response. Success was made more or less important through coordinated manipulations of outcome expectancy, ego-involvement, and performance assessment. As expected, systolic blood pressure responses assessed during the performance period were proportional to the evocativeness of the clip when importance was high, but low regardless of evocativeness when importance was low. These findings support a new conceptual analysis concerned with the determinants and CV correlates of restraint intensity. Implications of the study and associations with current self-regulatory literature are discussed.
156

The creation of a binaural spatialization tool

Picinali, Lorenzo January 2011 (has links)
The main focus of the research presented within this thesis is, as the title suggests, binaural spatialization. Binaural technology and, especially, the binaural recording technique are not particu-larly recent. Nevertheless, the interest in this technology has lately become substantial due to the increase in the calculation power of personal computers, which started to allow the complete and accurate real-time simulation of three-dimensional sound-fields over headphones. The goals of this body of research have been determined in order to provide elements of novelty and of contribution to the state of the art in the field of binaural spatialization. A brief summary of these is found in the following list: • The development and implementation of a binaural spatialization technique with Distance Simulation, based on the individual simulation of the distance cues and Binaural Reverb, in turn based on the weighted mix between the signals convolved with the different HRIR and BRIR sets; • The development and implementation of a characterization process for modifying a BRIR set in order to simulate different environments with different characteristics in terms of frequency response and reverb time; • The creation of a real-time and offline binaural spatialization application, imple-menting the techniques cited in the previous points, and including a set of multichannel(and Ambisonics)-to-binaural conversion tools. • The performance of a perceptual evaluation stage to verify the effectiveness, realism, and quality of the techniques developed, and • The application and use of the developed tools within both scientific and artistic “case studies”. In the following chapters, sections, and subsections, the research performed between January 2006 and March 2010 will be described, outlining the different stages before, during, and after the development of the software platform, analysing the results of the perceptual evaluations and drawing conclusions that could, in the future, be considered the starting point for new and innovative research projects.
157

Violent and Nonviolent Juvenile Offenders: An Assessment of Differences in Impulse, Ego Structure, and Object Relations Using the Psychoanalytic Rorschach Profile

Callahan, Theresa A. (Theresa Ann) 08 1900 (has links)
The present study used the Psychoanalytic Rorschach Profile (PRP) to assess differences in personality organization in violent and nonviolent juvenile offenders.
158

Modelování indexu finančního stresu v České republice pomocí vektorové autoregrese / Modelling of Financial Stress Index in the Czech Republic using Vector Autoregression Analysis

Malega, Ján January 2015 (has links)
This study constructs a financial stress index with a specific focus on the case of the Czech Republic. The advantage of the index is primarily its ability to measure the current level of stress in the financial system incorporating information from various sectors of the economy and expressing it in a single-value statistic. Our index successfully recorded and evaluated critical periods of elevated financial stress especially during the recent financial crisis. Furthermore, we examine a systematic interaction between financial stress and the macroeconomics using vector autoregression analysis along with method of impulse responses. Based on our results we observe a significant and positive response of unemployment due to the shock in financial stress. Conversely, a negative effect was examined on inflation and interest rates. JEL Classification G17, G32 Keywords financial stress index, vector autoregression, impulse responses
159

Impulsköp : En studie om vilka faktorer som kan påverka när svenska kvinnor utför impulsköp

Andersson Weinez, Linnéa January 2017 (has links)
Detaljhandeln förmodas möta en stor utmaning de kommande åren. Detta då digitaliseringen växer i snabb takt och e-handeln konkurrerar allt mer mot de traditionella butikerna. På grund av den hårdnande konkurrensen är det viktigt att företag tänker nytt och är innovativa. För att bemöta utmaningen menar jag att impulsköp kan anses som en konkurrensfördel för detaljhandelsföretag. Denna studie har därför tagit sin utgångspunkt i detta och belyser just fenomenet impulsköp. Då kvinnan är den som tidigare påvisats utföra flest impulsköp valdes det i studien att fokusera på henne. Syftet var att bidra med en ökad kunskap gällande vilka faktorer som kan påverka när svenska kvinnor impulshandlar. Studiens insamling av empiri bestod av en gruppintervju samt tre enskilda intervjuer. Dessa grundades i en analysmodell som utvecklats från studiens litteraturgenomgång. Sammanfattningsvis var det tre faktorer ur studiens analysmodell som kunde påvisas vara påverkande vid impulsköp. Dessa var shoppingmiljö, erbjudande och sällskap. Även merförsäljning och ålder har påvisats kunna vara betydande för impulsköp. / Retail business is expected to face a major challenge in the coming years. This is because digitalization is growing rapidly, and e-commerce is increasingly competing against traditional stores. It requires innovative thinking of companies to be competitive. To meet the challenge, I mean that impulse purchases can be used as a competitive advantage for retail companies. This study has therefore taken its starting point in the phenomenon impulse purchases. The study focuses on a female perspective since women are more inclined to execute impulse purchases. The purpose was to contribute to increased knowledge of the factors that may be crucial when Swedish women do impulse purchases. The study's empirical gathering consisted of a group interview and three individual interviews. These interviews were based on an analysis model developed by the study's literature review. In summary, three factors from the study's analysis model that could be shown to be influential in impulse purchases . These are shopping environments, offers and companies while shopping. Even additional sale and age have been shown to be significant for impulse purchases.
160

Efeitos da taquipneia e hiperinsuflação dinâmica sobre a resistência do sistema respiratório em pacientes com bronquiectasias / Effects of respiratory rate and dynamic hyperinflation on respiratory system resistance in patients with bronchiectasis

Moroli, Ricardo Grassi 14 March 2019 (has links)
Introdução: Bronquiectasias (BQC) são caracterizadas pela dilatação patológica e irreversível dos brônquios. Nestas situações pode-se observar redução da capacidade de exercício e limitações ao esforço por dispneia, aumento da frequência respiratória e hiperinsuflação dinâmica. Objetivo: Avaliar os efeitos do aumento da demanda ventilatória sobre a mecânica do sistema respiratório, simulando o que acontece no exercício, em indivíduos com BQC e em indivíduos controles. Métodos: Foram avaliados 30 voluntários com BQC (49,47±15,31 anos) e 16 SDP (40,19±15,74 anos). A capacidade vital e inspiratória foram avaliadas pela ventilometria. A resistência a 5 e 20 Hz (R5 e R20) e subtração de R5-R20, reatância a 5 Hz (X5), frequência de ressonância (Fres) e área de reatância (Ax) foram avaliadas pelo sistema de oscilometria de impulso (IOS), com respirações ao volume corrente e frequência respiratória basal (Fb); com aumento da frequência respiratória (F) a 30 e 40 incursões respiratórias por minuto (irpm) (F30 e F40), e hiperinsuflado basal (Hb) e com aumento da F (H30 e H40). Resultados: No IOS, nas comparações entre os grupos, houve diferença (p<0,05) para R5, R5-20, X5, Fres e Ax, apenas R20 não apresentou diferença significativa (p>0,05). No grupo BCQ, quando comparadas as frequências (Fb, F30 e F40) houve diferença para R5, R5-20, X5, Fres e Ax, (p<0,05). Quando comparadas a hiperinsuflação voluntária com aumento de F (Hb, H30 e H40) houve diferença para R5, R5-20, X5 e Ax, (p<0,05). Entre as situações de aumento de F, e, aumento de volume, houve diferença para R5, R20, R5-20, X5, Fres e Ax, (p<0,05). No grupo controle, para a R20, houve diferença entre H30 e H40 com F40. A X5 apresentou diferença entre Hb e as frequencias (Fb, F30 e F40) e aumento volume (H30 e H40), p<0,05. Conclusão: A taquipneia aumentou a resistência total, central e periférica das vias aéreas em indivíduos com BQC e a resistência central no grupo controle. Por outro lado, a hiperinsuflação voluntária promoveu um efeito protetor sobre a resistência, aproximando-a dos valores basais, em ambos os grupos / Introduction: Bronchiectasis (NFCB) are characterized by pathological and irreversible bronchial dilation. Reduction of exercise capacity, dyspnea, increased respiratory rate, and dynamic hyperinflation can be observed in patients with this condition. Objective: To evaluate the effects of increased and ventilatory demand and increase of respiratory rate of the respiratory system, during simulation of physical exercise in individuals with NFCB and in control subjects. Methods: Thirty volunteers with NFCB (49.47±15.31 years old) and 16 control (40.19±15.74 years old) were evaluated. The vital and inspiratory capacity was evaluated by ventilometry. Resistance at 5 and 20 Hz (R5 and R20, respectively) and R5-R20, reactance at 5 Hz (X5), resonance frequency (Fres), and reactance area (Ax) were evaluated by impulse oscillometry system (IOS). Measurements included basal tidal volume (TV), basal TV and respiratory rate (R), 30 breaths (RR30) per min (bpm), basal TV and rate 40 (RR40) bpm, basal hyperinflation (bh), hyperinflation and r30 bpm (h30), and hyperinflation and r40bpm (h40). Results: In IOS, the comparisons between groups, there was difference (p<0.05) for R5, R5-20, X5, Fres and Ax, only R20 did not present significant difference (p>0.05). In the BCQ group, when comparing the frequencies (TV, RR30 and RR40) there was difference for R5, R5- 20, X5, Fres and Ax, p <0.05. When comparing the voluntary hyperinflation with increase of F (Hb, HRR30 and HRR40) there was difference for R5, R5-20, X5 and Ax, (p<0.05). Among the situations of increase of R, and increase of volume, there was difference for R5, R20, R5-20, X5, Fres and Ax, (p<0.05). In the control group, for R20, there was a difference between HRR30 and HRR40 with RR40. The X5 presented difference between Hb and the rate (TV, RR30 and RR40) and volume increase (HRR30 and HRR40), p <0.05.Conclusion: Tachypnea increased total, central and peripheral airway resistance in individuals with BQC and central resistance in the control group. And voluntary hyperinflation promoted a protective effect on resistance, approaching baseline values in both groups

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