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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.
521

Fundamental momentum as an investment timing indicator for value portfolios

Yates, Marinus 09 March 2013 (has links)
The problem associated with value shares is that they may remain undervalued for an extended period of time. Therefore, determining when to buy value shares has been the focus of many investors and academics. Studies have determined fundamentals provide valuable information when selecting shares while price momentum provides a decent timing indicator. This research examines a novel share selection approach which seeks to combine fundamentals with momentum to obtain a leading timing indicator.This research seeks to determine if the fundamental momentum indicator can successfully and consistently separate value winners from value losers. The value portfolios were formed using a composite valuation measure made of three separate indicators. The Value portfolio was then ranked based on the strength of the fundamental momentum indicator.This research identified that Leverage Factor and Current Ratio momentum was able to separate value winners from losers in a consistent manner. However, only Current Ratio momentum was capable of creating portfolios which could consistently outperform the market. Therefore, this research identified that fundamental momentum could be used as a timing indicator when acquiring value shares. / Dissertation (MBA)--University of Pretoria, 2012. / Gordon Institute of Business Science (GIBS) / unrestricted
522

Temporal Dietary and Physical Activity Patterns are Associated with Obesity

Marah M Aqeel (8790059) 02 May 2020 (has links)
<p>Obesity is a major public health problem globally and in the United States (U.S.). Amongst adults in the U.S., prevalence estimates of obesity reached 42.4% in 2017-2018 [1]. Obesity is both a contributor and outcome of chronic disease development including type 2 diabetes and metabolic syndrome [2,3]. Underlying modifiable risk factors for these chronic conditions include lifestyle habits such as dietary intake and physical activity. </p><p>Much of nutrition research investigating the relationship of dietary intake to health outcomes has taken a reductionist approach with a focus on single nutrients and food groups; however, the complexity of the overall diet with all its constituents is being increasingly recognized. Dietary patterns examine the quantities, frequencies, and combinations of food and beverages consumed allowing a more comprehensive investigation of the diet-health relationship [4], yet, the concept and creation of patterns have not considered elements beyond nutrients and food, such as time of eating, which could be an important aspect of dietary patterns. Moreover, most physical activity research has focused on the effect of intensity or counts of activity on health [5–8], while studies investigating daily physical activity patterns have focused on distinct time periods i.e., type of day (weekday vs. weekend) or seasonality [9,10]. Nevertheless, connecting these patterns to health outcomes through the integration of time across an entire day has received little attention.</p><p>Studies that have incorporated time to the concept of dietary patterns focus on behaviors such as breakfast skipping and late meal consumption and show associations with health [11–14]. For instance, compared to early lunch eaters, late lunch eaters lost less weight and had reduced glucose tolerance [15,16]. In contrast, studies that have investigated timing of exercise focused on early vs. evening exercise [17–19]. For example, exercise performed in the morning vs. evening has been associated with a greater reduction in weight and odds of obesity [17,18]. Furthermore, several studies have investigated links between timing of exercise relative to a single meal or over a single day with health [20–24] and revealed a potential benefit to modulating time of these behaviors on postprandial metabolic response. Together, these studies establish the importance of timing of these behaviors in terms of links to health; however, studies are limited by a focus on single time spans or blocks of time in a day. Consideration of the patterns of dietary intake and activity throughout a day, or “temporal dietary and physical activity patterns”, are a novel concept that may provide insight to the behavioral patterns related to health outcomes. Notably, one of the challenges in this work is utilizing methods that will characterize dietary and physical activity patterns as an exposure by integrating timing and other characteristics of these patterns in relation to health. </p> To our knowledge, there are no published reviews that have emphasized joint consideration of the time of eating and exercise, with a focus on the time of day of these events and association with health outcomes. Therefore, Chapter 1 focuses on summarizing current literature that has integrated both of these concepts by answering the question, how does the timing of exercise relative to eating throughout the day effect postprandial response in adults? Moreover, Chapters 2 and 3, include primary research in which a novel distance measure, based on dynamic time warping, is used to develop independent temporal dietary and physical activity patterns over a 24-hour period using data from the National Health and Nutrition Examination Survey and examine their association with short- and long-term health outcomes.
523

Messung des lateralen Profils und der Zeitstruktur von Protonenstrahlen im Experimentierraum der Universitäts Protonen Therapie Dresden

Schmidt, Maximilian 31 January 2020 (has links)
Die Reichweiteverifikation von Protonen ist ein wichtiger Schritt zur Erhöhung der Präzision der Protonentherapie. Eine neue Methode ist das Prompt -Ray Timing, bei dem Reichweiteinformation aus der Zeitverteilung detektierter Gammaquanten gewonnen wird. Für eine genaue Reichweitebestimmung wird jedoch eine präzise und konstante Zeitreferenz benötigt. Um entdeckte Phasenverschiebungen zwischen Protonbunch und der als Zeitreferenz genutzten Hochfrequenz des Zyklotrons korrigieren zu können, werden Proton- Bunch-Monitore eingesetzt. Diese Arbeit soll abschätzen, ob und wo Proton-Bunch-Monitore im Protonenstrahl eingesetzt werden können. Nach ersten Abschätzungen mit dem Lynx von IBA Dosimetry wurden zwei Monitore auf Basis einer szintillierenden Faser und dem U100-Spektrometer von Target in die äußeren lateralen Bereiche von Protonenstrahlen verschiedener Energien bei niedrigen Strahlströmen (0,01 nA bis 0,1 nA) gebracht. Es zeigt sich eine systematische Abhängigkeit der Relativzeit und der horizontalen Position im Strahl, welche auf die Strahlumlenkung zurückzuführen ist. Diese resultiert in einer systematischen Abhängigkeit der mittleren Reichweite und der horizontalen Position. Durch Abschätzung der Protonenrate für einen klinischen Strom von 2 nA konnten potentielle Einsatzorte im Strahl-Halo identifiziert werden. Weitere Untersuchungen sind jedoch notwendig, um die Einsetzbarkeit zur Korrektur von Phasenverschiebungen unter klinischen Bedingungen zu erproben. / The range verification of protons is an important step towards increasing the precision of proton therapy. A new method is the prompt -ray timing, where range information is obtained from the time distribution of detected gamma quanta. However, the method requires a precise and constant time reference for accurate range determination. proton bunch monitors can be used to correct detected phase shifts between proton bunch and the cyclotron radio frequency used as a time reference. This work should estimate if and where proton bunch monitors can be used in the proton beam. According to initial estimates with the Lynx from IBA Dosimetry, two monitors based on scintillating fiber and Target’s U100 spectrometer were used in the outer lateral regions of proton beams of different energies at low beam currents (0.01 nA to 0.1 nA). It shows a systematic dependence of the relative time and the horizontal position in the beam, which is due to the beam deflection. This results in a systematic dependence of the mean range and the horizontal position. By estimating the proton rate for a clinical current of 2 nA, potential positions of application in the beam halo were identified. However, further investigations are needed to test the applicability for the correction of phase shifts under clinical conditions.
524

Metodologické aspekty úlohy aktivního vyhýbání se místu / Methodological aspects of active place avoidance task

Bahník, Štěpán January 2013 (has links)
The active place avoidance task represents one of the methods of the study of animal cognition. In this task, a subject is put on a rotating circular arena and avoids invisible sector that is stable with respect to the room. Rotation of the arena means that the subject's avoidance must be active, otherwise the subject would be moved in the punished sector by the rotation of the arena and a slight electric shock would be administered. The experiment described in the present work explored the effect of variable arena rotation speed on the ability to avoid the punished sector. Rats in a group with a variable arena rotation speed learned to avoid the punished sector with the same speed and attained the same ability to avoid the sector as rats in a group with a stable arena rotation speed. The only difference between the two groups was found in a preferred position within the room. No difference was found between the two groups in the dark phase, where the rats could not use orientation cues in the room. Only one rat was able to learn the avoidance of the punished sector in this phase. The results of the experiment suggest that idiothetic orientation and interval timing are not crucial for learning of the avoidance of the punished sector. However, idiothetic orientation is sufficient for the avoidance of the...
525

Vliv interakcí jednotlivých funkčních skupin herbivorů na čertkus luční. / Interactions of herbivore funtion gourps and Succisa pratensis

Šulcová, Hana January 2013 (has links)
Herbivory is one of most important factors which form meadow ecosystems. These ecological communities have one of the biggest variety of species in Central Europe and their research is important in terms of management of protected species as well. Localities which has a similar importance, is also a meadow ecosystem with occurrence of Succisa pratensis, the only host plant for rare butterfly Euphydryas aurinia. Research of Succisa and its other herbivores can improve a protection of this particular butterfly. Effects of herbivores of Succisa were examined by several experiments. The first one was a field cage experiment. Its aim was to detect what kinds of herbivores (rodents and invertebrates) are involved in herbivory of leaf rosettes of Succisa and what is their impact on the fitness of these plants. The intensity of herbivory of Succisa was measured for over two vegetation seasons on the month bases. In this experiment were also examined effects of surrounding vegetation on the studied plants of Succisa. The second experiment was performed in a garden. Its aim was to clarify the role of herbivores of leaf rosettes, stalks and their interactions on the fitness of Succisa. The third experiment was concerned to true bugs, which are pre-dispersal predators of seeds of Succisa. Their effects on...
526

Časová kalibrace a rozlišení hadronového kalorimetru Tilecal / Time calibration and resolution of the hadronic Tile Calorimeter

Krejčíková, Martina January 2016 (has links)
The thesis deals with Tilecal hadron calorimeter, which is part of the ATLAS detector at the LHC at CERN. Main area of interest is a time calibration of the detector, which is necessary to accurately determine the energy especially of jets produced as a result of precipitation collisions of protons. Based on obtained experimental data from 2011 thoroughly explored the relationships between the time of arrival of the particles into the cells of the detector and their energies, or the distance from the given objects. By describing the time calibration, one can correct originally obtained time constants. Description and resolution of time jumps in timing of channels are part of the thesis, corrections of identified examples are included. Powered by TCPDF (www.tcpdf.org)
527

Pohybový stereotyp abdukce v ramenním kloubu v počáteční fázi hodu u extraligových hráčů softballu. / The motion pattern of abduction in the shoulder joint in overhead throwing of softball Extraliga players

Hrdinová, Denisa January 2019 (has links)
Author: Bc. Denisa Hrdinová Title: The motion pattern of abduction in the shoulder joint in overhead throwing of softball Extraliga players Objectives:The aim of the thesis was to monitor and evaluate the difference in the sequence of tenses of muscle recruitment during the abduction in the shoulder joint between softball players and the general population, using surface electromyography (SEMG). A partial aim was to identify shortened muscle groups of the shoulder girdle and their influence on the timing of the abductors. Another partial aim was to evaluate the effect of shortened muscle groups on possible deficits in scapulohumeral rhythm of softball players. Methods: The experimental group (n=10) and the control group (n=10) with a total average age of 21.8 ± 1.81 (SD) participated in the kinesiological analysis with targeted examination of the shortened muscle groups and scapulohumeral rhythm. Followed by SEMG examination of muscle timing during abduction in the shoulder joint. Five muscles were monitored during 15 repetitions of motion at 70 bpm. The SEMG signal analysis was processed by rectification and smoothing in MyoResearch software by Noraxon v3.80 and statistical analysis performed in program Statistica 13.4. Results: 1. The difference in timing between the experimental and control...
528

A real-time hybrid method based on blade tip timing for diagnostics and prognostics of cracks in turbomachine rotor blades

Ellis, Brian January 2019 (has links)
This dissertation proposes hybrid models for (i) diagnosis and (ii) remaining useful life estimation of a single fatigue crack in a low-pressure turbine blade. The proposed hybrid methods consist of physics-based methods and data-driven methods. In this dissertation, blade tip timing is used to measure the relative tip displacement of a rotor blade. The natural frequency of the blade is determined by detecting the critical speeds of the blade using a newly derived least squares spectral analysis method. The method shares its origin from the Lomb-Scargle periodogram and can detect resonance frequencies in the blade’s displacement while the rotor is in operation. A Campbell diagram is then used to convert the critical speed into a natural frequency. Two kinds of shaft transients are considered, a run-up run-down crossing the same critical speed, is used to test the new method. This dissertation shows that the relative displacement of the blade tip is comparable to those simulated from an analytical single degree of freedom model. It is also shown that the newly proposed resonance detection method estimates the natural frequency of the blade to a high degree of accuracy when compared to the measurements from a modal impact hammer test. The natural frequency obtained from the real time measurement is then used in a pre-constructed hybrid diagnostics model. The diagnostics model provides a probability density function estimation of the surface crack length given the measured natural frequency. A Gaussian Process Regression model is trained on data collected during experiments and finite element simulations of a fatigue crack in the blade. The final part of this dissertation is a sequential inference model for improving the estimation of the crack length and the prediction of the crack growth. The suggested model uses an unscented Kalman filter that improves estimations of the crack length and the rate of crack growth from Paris’ Law coefficients. The model is updated each time a diagnosis is performed on the blade. The RUL of the blade is then determined from an integration of Paris’s Law given the uncertainty estimates of the current damage in the blade. The result of the algorithm is an estimation of the remaining number of cycles to failure. The algorithm is shown to improve the overall estimation of the RUL; however, it is suggested that future work looks at the convergence rate of the method. / Dissertation (MEng)--University of Pretoria, 2019. / Eskom Power Plant Engineering Institute (EPPEI) / Mechanical and Aeronautical Engineering / MEng / Unrestricted
529

Methods for Ionization Current Interpretation to be Used in Ignition Control

Eriksson, Lars January 1995 (has links)
It is desirable to measure engine performance for several reasons, e.g. when computing the spark advance setting in spark-ignited (SI) engines. There exists two methods, among others, of measuring the performance, such as measuring the pressure and the ionization current. Since the ionization current reflects the pressure, it is interesting to study if it is possible to extract information from the ionization current about the combustion and pressure. Three different algorithms for extracting information from the ionization current are studied. The first algorithm, ion peak, searches the \second peak" in the ionization signal. The second algorithm computes the centroid. In the third algorithm a model of the ionization signal structure is fitted to the ionization signal. The algorithms are tested in four operating conditions. The first algorithm uses the local information around the second peak and is sensitive to noise. The second algorithm uses a larger portion of the ionization signal, which is more stable. It provides promising results for engines with a clear post flame phase. The third algorithm, ion structure analysis, fits an ideal model to the ionization signal. The algorithm provides promising results, but the present implementation requires much computational effort.
530

Active Versus Passive Investing : A Comparative Analysis

Molander, Jonathan, van Loo, Lennart January 2020 (has links)
The increasing popularity of passive investment strategies causes the long-term feasibility of active investing to be questioned more often. Therefore, this research aimed to uncover whether active investors' influence on fund performance is positive and significant enough to offset the cost involved, thereby providing reasoning for active rather than passive investing. A comparative analysis of 211 actively managed funds and 191 market and industry-specific indices is performed. Security selection skills and market timing ability are captured through a model comprising of the Fama French three-factor and the Treynor and Mazuy market timing model. The sample is tested between 2005 and 2020, with 5-year sub-periods. Over the full period, active and passive returns are found to be nearly indistinguishable. However, active funds seem to excel during bearish periods, where passive funds excel in bullish periods. The standard deviation is higher overall for passive investing. This difference, however, disappears during bearish periods. The security selection skill is barely distinguishable from zero for either strategy. On the other hand, market timing ability is existent for active investors, indicating a positive effect in bearish markets and a negative effect in bullish markets. Additionally, for both investing strategies, more than 90% of the returns are explained by the movements of the general market. The most suitable investment strategy is truly determined by an investor's level of risk aversion. Nevertheless, this research found that, in general, the passive investing strategy is dominant under normal market conditions. Active investors can act on the macroeconomic developments that fuel crises. This advantage enables them to achieve returns superior to indices while preserving a lower standard deviation during bearish market conditions.

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