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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.
391

On Perceived Exertion and its Measurement

Borg, Elisabet January 2007 (has links)
<p>The general aim of the thesis is to answer questions on general and differential aspects of perceived exertion and on the measurement of its intensity variation. Overall perceived exertion is commonly treated as a unidemensional construct. This thesis also explores its multidimensional character. Four empirical studies are summarized (Study I-IV). Psychophysical power functions of perceived exertion obtained with the new improved Borg CR100 (centiMax) scale were found to be consistent with results obtained with absolute magnitude estimation, and with the classical Borg CR10 and RPE scales. Women gave significantly higher perceived exertion scale values than men for the same levels of workload on a bicycle ergometer. This agrees with the fact that they were physically less strong than men. With regard to the measurement of “absolute” levels of intensity, RPE- and CR-scale values were validated by physiological measurements of heart rate and blood lactate. Predicted values of maximal individual performance obtained from psychophysical functions agreed well with actual maximal performance on the bicycle ergometer. This confirms the validity of the RPE and CR scales for measuring perceptual intensity and their value for interindividual comparisons. To study the multidimensional character of perceived exertion, 18 symptoms were measured with a CR scale: in a questionnaire, and in bicycle ergometer work tests. Five factors were extracted for the questionnaire: (1) Muscles and joints; (2) Perceived exertion; (3) Annoyance/lack of motivation; (4) Head/stomach symptoms; and (5) Cardiopulmonary symptoms. Four factors were extracted for the bicycle max test: (1) Physical distress; (2) Central perceived exertion; (3) Annoyance/lack of motivation; (4) Local perceived exertion. The questionnaire is suggested for clinical use to let patients express a variety of symptoms. The thesis also resulted in improvements of the Borg CR100 scale. An extended use of the scale is recommended.</p>
392

Sur la théorie des excursions pour des processus de Lévy symétriques stables d'indice α ϵ ]1,2] et quelques applications

Cordero, Fernando 22 September 2010 (has links) (PDF)
Cette thèse est constituée de 5 chapitres. Le chapitre 1 est divisé en deux parties; la première autour des généralités sur les processus de Lévy et la deuxième sur le cas particulier des processus symétriques stables. Le chapitre 2 porte sur la théorie des fluctuations dans le cas stable et concentre la plupart des résultats originaux de cette thèse. Dans ce chapitre, on s'intéresse premièrement à la loi conjointe du premier temps de passage au-dessus d'une barrière et de la position du processus en cet instant ainsi qu'à des questions autour de l'absolue continuité de la loi du supremum. Dans un deuxième temps, dans le cas stable, on s'intéresse à la loi conjointe du processus au temps t, de son supremum avant t et du dernier temps d'atteinte du supremum avant t. Le chapitre 3 est aussi constitué des deux parties, une partie sur les temps locaux et une autre partie sur la théorie des excursions. Les deux parties sont traitées dans le cas des processus symétriques stables d'indice supérieur à 1. Concernant les temps locaux, on rappelle leur définition et leurs principales propriétés. Concernant la théorie des excursions, on présente la théorie de façon semblable aux cas classiques en passant entre autres par les définitions d'excursion normalisée et de méandre, et en donnant des constructions simples pour ces objets. On présente aussi quelques développements récents de la théorie dus à K.Yano, Y. Yano et M. Yor. Les chapitres 4 et 5 portent sur des applications (dans le cas symétrique stable) de la théorie des excursions à l'étude respectif des temps passés positif et négatif et des valeurs principales généralisées.
393

Evaluation of different CMOS processes using a circuit optimization tool

Johansson, Anders January 2009 (has links)
<p>The geometry of CMOS processes has decreased in a steady pace over the years at the same time as the complexity has increased. Even if there are more requirements on the designer today, the main goal is still the same: to minimize the occupied area and power dissipation. This thesis investigates if a prediction of the costs in future CMOS processes can be made. By implementing several processes on a test circuit we can see a pattern in area and power dissipation when we change to smaller processes.</p><p>This is done by optimizing a two-stage operational transconductance amplifier on basis of a given specification. A circuit optimization tool evaluates the performance measures and costs. The optimization results from the area and power dissipation is used to present a diagram that shows the decreasing costs with smaller processes and also a prediction of how small the costs will be for future processes. This thesis also presents different optimization tools and a design hexagon that can be used when we struggle with optimization trade-offs.</p>
394

Variable selection and neural networks for high-dimensional data analysis: application in infrared spectroscopy and chemometrics

Benoudjit, Nabil 24 November 2003 (has links)
This thesis focuses particularly on the application of chemometrics in the field of analytical chemistry. Chemometrics (or multivariate analysis) consists in finding a relationship between two groups of variables, often called dependent and independent variables. In infrared spectroscopy for instance, chemometrics consists in the prediction of a quantitative variable (the obtention of which is delicate, requiring a chemical analysis and a qualified operator), such as the concentration of a component present in the studied product from spectral data measured on various wavelengths or wavenumbers (several hundreds, even several thousands). In this research we propose a methodology in the field of chemometrics to handle the chemical data (spectrophotometric data) which are often in high dimension. To handle these data, we first propose a new incremental method (step-by-step) for the selection of spectral data using linear and non-linear regression based on the combination of three principles: linear or non-linear regression, incremental procedure for the variable selection, and use of a validation set. This procedure allows on one hand to benefit from the advantages of non-linear methods to predict chemical data (there is often a non-linear relationship between dependent and independent variables), and on the other hand to avoid the overfitting phenomenon, one of the most crucial problems encountered with non-linear models. Secondly, we propose to improve the previous method by a judicious choice of the first selected variable, which has a very important influence on the final performances of the prediction. The idea is to use a measure of the mutual information between the independent and dependent variables to select the first one; then the previous incremental method (step-by-step) is used to select the next variables. The variable selected by mutual information can have a good interpretation from the spectrochemical point of view, and does not depend on the data distribution in the training and validation sets. On the contrary, the traditional chemometric linear methods such as PCR or PLSR produce new variables which do not have any interpretation from the spectrochemical point of view. Four real-life datasets (wine, orange juice, milk powder and apples) are presented in order to show the efficiency and advantages of both proposed procedures compared to the traditional chemometric linear methods often used, such as MLR, PCR and PLSR.
395

Design and Optimization of Complex Systems

Willcox, Karen E. 01 1900 (has links)
Truely optimal solutions to system design can only be obtained if the entire system is considered. In this research we consider design of commercial aircraft, but we expand the system to include a family of planes. A multidisciplinary design optimization framework is developed in which multiple aircraft, each with different missions, can be optimized simultaneously. Results are presented for a two-member family whose individual missions differ significantly. We show that both missions can be satisfied with common designs, and that by optimizing both planes simultaneously rather than following the traditional baseline plus derivative approach, the common solution is vastly improved. The new framework is also used to gain insight to the effect of design variable scaling on the optimization algorithm. / Singapore-MIT Alliance (SMA)
396

EVALUATION OF GEOMETRIC SCALE EFFECTS FOR SCRAMJET ISOLATORS

Perez, Jaime Enrique 01 August 2010 (has links)
A numerical analysis was conducted to study the effects of geometrically scaling scramjet inlet-combustor isolators. Three-dimensional fully viscous numerical simulation of the flow inside constant area rectangular ducts, with a downstream back pressure condition, was analyzed using the SolidWorks Flow Simulation software. The baseline, or 1X, isolator configuration has a 1” x 2.67” cross section and 20” length. This baseline configuration was scaled up based on the 1X configuration mass flow to 10X and 100X configurations, with ten and one hundred times the mass flow rate, respectively. The isolator aspect ratio of 2.67 was held constant for all configurations. To provide for code validation, the Flow Simulation program was first used to analyze a converging-diverging channel and a wind tunnel nozzle. The channel case was compared with analytical theory and showed good agreement. The nozzle case was compared with AFRL experimental data and showed good agreement with the entrance and exit conditions (Pi0= 40 psia, Ti0= 530ºR, Pe= 18.86 psia, Te= 456ºR, respectively). While the boundary layer thickness remained constant, the boundary layer thickness with respect to the isolator height decreased as the scale increased. For all the isolator simulations, a shock train was expected to form inside the duct. However, the flow simulation failed to generate this flow pattern, due to improper sizing of the isolator and combustor for a 3-D model or having a low pressure ratio of 2.38. Instead, a single normal shock wave was established at the same relative location within the length of each duct, approximately 80% of the duct length from the isolator entrance. The shape of the shock changed as the scale increased from a normal shock wave, to a bifurcated shock wave, and to a normal shock train, respectively for the 1X, 10X, and 100X models.
397

Sequence alignment

Chia, Nicholas Lee-Ping, January 2006 (has links)
Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 80-87).
398

Peatland Bryophytes in a Changing Environment : Ecophysiological Traits and Ecosystem Function

Granath, Gustaf January 2012 (has links)
Peatlands are peat forming ecosystems in which not fully decomposed plant material builds up the soil. The sequestration of carbon into peat is mainly associated with the bryophyte genus Sphagnum (peat mosses), which dominate and literally form most peatlands. The responses of Sphagnum to environmental change help us to understand peatland development and function and to predict future changes in a rapidly changing world. In this thesis, the overarching aim was to use ecophysiological traits to investigate mechanisms behind the response of Sphagnum to elevated N deposition, and, processes connected to ecosystem shift and ecosystem function of peatlands. Regarding elevated N deposition, three experiments were performed at different scales (country-wide to greenhouse). Independent of scale and species, apical tissue N concentration increased with increasing N input until N saturation was reached. Maximum photosynthetic rate, a trait evaluating photosynthetic capacity, increased with N input and could be well predicted by tissue N concentration. Thus, the physiological responses of Sphagnum to N deposition are often positive and I found no evidence of toxic effects. Production did, however, not increase with N input, and results of the N:P ratio suggested that P limitation, and possibly other elements, might hamper growth under high N input. The effect of P limitation was, in contrast to current view, most pronounced in fast growing species indicating species specific responses to nutrient imbalance. I explored the puzzling, but historically frequently occurring, rich fen to bog ecosystem shift; a shift from a species-rich ecosystem dominated by brown mosses, to a species-poor one with greater carbon storage that is Sphagnum-dominated. The bog-dwelling species of Sphagnum grew well, to our surprise, when in contact with rich fen water but was not a strong competitor compared to rich fen Sphagnum species. If submerged under rich fen water (high pH), the bog Sphagnum species died while rich fen species of Sphagnum were unaffected. These results show that differences in two physiological traits (growth rate and tolerance to flooding) among species, can explain when a peatland ecosystem shift might occur. In the last study, the function of peatlands was related to trade-offs between traits and allometric scaling in Sphagnum. Results suggested that growth strategies are determined by the distribution of Sphagnum relative to the water table in order to minimize periods with suboptimal hydration. Allometric analyses stressed the importance of resource allocation among and within shoots (apical part vs. stem), although the allocation patterns in Sphagnum were not always consistent with those of vascular plants. Interestingly, data indicated a trade-off between photosynthetic rate and decomposition rate among Sphagnum species.
399

勞工職位特質分析-多元尺度法於大資料分析之應用 / The occupational characteristics analysis -the application of large data multidimensional scaling method

陳烽威, Chen, Fong Wei Unknown Date (has links)
本文自美國人口普查局 (United States Census Bureau) 取得多達十萬筆的勞工資料,然而在如此大量的勞工資料中因維度的詛咒,所以我們無法使用傳統的資料探勘的方法分析資料,而且傳統的序述統計也無法提供一個好的分析方向,因此我們藉由 Tzeng et al (2008) 所提出的分解與結合多元尺度法 (Split-and-combine Multidimensional Scaling, SC-MDS) 為分析方法來剖析此資料。多元尺度法主要的目的有二:第一,使資料展現在空間中,並以資料點與點之間的距離表示其相關性;第二,降低資料維度避免維度的詛咒。SC-MDS 提供我們在分析此大資料相關聯性時的優先順序為年齡、學歷、性別;並結合職位資訊聯合資料庫 (Occupational Information Network)分析在此架構下不同分類的勞工在其就業的職位特質上的差異。我們發現了教育程度會影響性別間在勞工職位特質上的差異,且這些差異的數量又會隨年齡的增加而增加;教育程度在各個年齡層都對勞工職位特質產生很大的差異;最後,青年與壯年的勞工在職位特質上相較於壯年與中年勞工相似,並對以上產生相似或差異的原因提出解釋。 / A big labor data from United States Census Bureau will occur two problems. First, since the big data issue, we can not use the traditional method of data mining. Second, the descriptive statistics can not offer an explicit analysis, so we use Split-and-combine Multidimensional Scaling (SC-MDS), which is proposed by Tzeng et al (2008) to mining this labor data. MDS has two main purposes: First, Express data similarity by the distance between each pair points in spatial configuration. Second, Reducing data dimension to aviod the curse of dimension. After SC-MDS, the big labor data can be analysed by age, education and sex. We combine this order and the Occupational Information Network data base to develope the differences in occupational characteristics. We find the following phenomenon: first, differences are increasing with ages. Second, eduction do impact labors' characteristics in every ages. Third, the youth labors are more similar in occupational characteristics than olders. Finally, we try to explain the results above.
400

Celluar and Molecular Mechanisms Underlying Regulation of Skeletal Muscle Contraction in Health and Disease

Li, Mingxin January 2010 (has links)
Morphological changes, genetic modifications, and cell functional alterations are not always parallel. Therefore, assessment of skeletal muscle function is an integral part of the etiological approach. The general objective of this thesis was to look into the cellular and molecular events occurring in skeletal muscle contraction in healthy and diseased condition, using a single fiber preparation and a single fiber in vitro motility assay, in an attempt to approach the underlying mechanisms from different physiological angles. In a body size related muscle contractility study, scaling of actin filament sliding speed and its temperature sensitivity has been investigated in mammals covering a 5,500-fold difference in body mass. A profound temperature dependence of actin filament sliding speed over myosin head was demonstrated irrespective of MyHC isoform expression and species. However, the expected body size related scaling within orthologus myosin isoforms between species failed to be maintained at any temperature over 5,500-fold range in body mass, with the larger species frequently having faster in vitro motility speeds than the smaller species. This suggest that apart from the MyHC iso-form expression, other factors such as thin filament proteins and myofilament lattice spacing, may contribute to the scaling related regulation of skeletal muscle contractility. A study of a novel R133W β-tropomyosin mutation on regulation of skeletal muscle contraction in the skinned single fiber prepration and single fiber in vitro motility assay suggested that the mutation induced alteration in myosin-actin kinetics causing a reduced number of myosin molecules in the strong actin binding state, resulting in overall muscle weakness in the absence of muscle wasting. A study on a type IIa MyHC isoform missense mutation at the motor protein level demonstrated a significant negative effect on the function of the IIa MyHC isoform while other myosin isoforms had normal function. This provides evidence that the pathogenesis of the MyHC IIa E706K myopathy involves defective function of the mutated myosin as well as alterations in the structural integrity of all muscle irrespective of MyHC isoform expression.

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