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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

Gefahrenkarten - ein Instrument zur Risikoabschätzung infolge eines hypothetischen Talsperrenbruches

Bornschein, Antje 05 March 2007 (has links) (PDF)
Dam failures and the following emptying of the reservoir are very seldom. But such catastrophes caused significant damages in the past. The related risk has to consider as high despite the high return period. The paper describes the development of hazard maps showing the dimension of inundation in the downstream region of the dam due to a potential failure. The needed data and possible used software for the dam break flood simulation were discussed. A dam break occurred in the catchment area of the Müglitz river in the Ore mountains during the flood 2002 is described. / Das Versagen einer Talsperre mit einer sich anschließenden Entleerung des Stauraumes ist sehr selten. Jedoch zogen solche Ereignisse in der Vergangenheit immer große Schäden nach sich, so dass trotz der geringen Eintrittswahrscheinlichkeit das Risiko als hoch einzuschätzen ist. Der Beitrag behandelt die Erstellung von Gefahrenkarten, die Auskunft darüber geben, wie groß die zu erwartende Überflutung infolge eines Bruches eines Absperrbauwerkes sein könnte. Dabei soll auf die zu ermittelnden Ausgangsdaten ebenso wie auf die zur Verfügung stehende Software zur Simulation der Ausbreitung von Talsperrenbruchwellen eingegangen werden. Als Fallbeispiel wird auf einen Dammbruch während des Hochwassers 2002 im Einzugsgebiet der Müglitz im Erzgebirge eingegangen.
152

UEFA Financial Fair Play - "break-even"-kraven : en konkurrensrättslig analys / UEFA Financial Fair Play - the "Break-even"-Requirements : A Competition Law Analysis

Svedjeholm, Christoffer, Rödin, Mikael January 2015 (has links)
2009 beslutade det europeiska fotbollsförbundet UEFA att införa regelverket Financial Fair Play Regulations, för att förbättra fotbollens ekonomiska hälsa. Detta som en följd av en allt mer ansvarslös och irrationell pengahantering bland europeiska fotbollsklubbar, med stora underskott och försenade betalningar som konsekvens. Ett avsnitt i regelverket berör de så kallade ”break-even”-kraven, som sätter begränsningar för hur stora underskott klubbar får visa upp.   I vår uppsats har syftet varit att utreda huruvida ”break-even”-kraven är att anse som förenliga med EU-rättsliga konkurrensregler, specifikt art. 101.1 FEUF. Detta då kraven, enligt vår uppfattning, kan anses ha en konkurrenshämmande verkan i form av investeringsbegränsningar och en asymmetrisk effekt på transfermarknaden.   För att kunna utreda den rättsliga giltigheten, har vi använt oss av relevant praxis på EU-nivå inom områdena konkurrensrätt och idrott. Eftersom regelverket är så pass nyutkommet, har det ännu inte hunnit prövas rättsligt på EU-nivå. I och med detta, har det för oss funnits stort utrymme för diskussion och hypotetiska scenarion. Vår studie av praxis har visat att bestämmelserna kan bedömas vara förenliga med EU-rätten, trots en konkurrensbegränsande verkan. I vår analys har vi därför, utifrån befintliga förutsättningar, diskuterat huruvida vi anser att ”break-even”-kraven ska bedömas vara förenliga med art. 101.1 FEUF, även om de kan anses ha en konkurrenshämmande effekt. Vi har vägt in både ekonomiska och sportsliga faktorer i vår analys, och har även diskuterat möjligheten till alternativa tillvägagångssätt.
153

CHK2 is Negatively Regulated by Protein Phosphatase 2A

Freeman, Alyson 31 May 2010 (has links)
Checkpoint kinase 2 (CHK2) is an effector kinase of the DNA damage response pathway and although its mechanism of activation has been well studied, the attenuation of its activity following DNA damage has not been explored. Here, we identify the B'α subunit of protein phosphatase 2A (PP2A), a major protein serine/threonine phosphatase of the cell, as a CHK2 binding partner and show that their interaction is modulated by DNA damage. B'α binds to the SQ/TQ cluster domain of CHK2, which is a target of ATM phosphorylation. CHK2 is able to bind to many B' subunits as well as the PP2A C subunit, indicating that it can bind to the active PP2A enzyme. The induction of DNA double-strand breaks by ionizing radiation (IR) as well as treatment with doxorubicin causes dissociation of the B'α and CHK2 proteins, however, it does not have an effect on the binding of B'α to CHK1. IR-induced dissociation is an early event and occurs in a dose-dependent manner. CHK2 and B'α can re-associate hours after DNA damage and this is not dependent upon the repair of the DNA. Dissociation is dependent on ATM activity and correlates with an increase in the ATM-dependent phosphorylation of CHK2 at serines 33 and 35 in the SQ/TQ region. Indeed, mutating these sites to mimic phosphorylation increases the dissociation after IR. CHK2 is able to phosphorylate B'α in vitro; however, in vivo, irradiation has no effect on PP2A activity or localization. Alternatively, PP2A negatively regulates CHK2 phosphorylation at multiple sites, as well as its kinase activity and protein stability. These data reveal a novel mechanism for PP2A to keep CHK2 inactive under normal conditions while also allowing for a rapid release from this regulation immediately following DNA damage. This is followed by a subsequent reconstitution of the PP2A/CHK2 complex in later time points after damage, which may help to attenuate the signal. This mechanism of CHK2 negative regulation by PP2A joins a growing list of negative regulations of DNA damage response proteins by protein serine/threonine phosphatases.
154

Uncertainty quantification for risk assessment of loss-of-coolant accident frequencies in nuclear power plants

Pan, Ying-An 02 December 2013 (has links)
This research presents the methodologies used to resolve the Nuclear Regulatory Commission Generic Safety Issue 191. The presented results are specific to South Texas Project Nuclear Operating Company (STPNOC). However, the proposed methodologies may be applicable to other nuclear power plants given the appropriate plant-specific frequencies. This research provides important inputs to CASA Grande, a computer program used to model physical phenomena and quantify uncertainties to obtain estimates of failure probabilities for post-loss-of-coolant accident events at the STPNOC containment. We provide modeling and sampling methods for loss-of-coolant accident (LOCA) frequencies and break sizes. We focus on a study known as NUREG-1829 (Tregoning et al., 2008), which includes an expert elicitation of quantiles governing the (annual) frequency of a LOCA in boiling water reactors and pressurized water reactors. We propose to model LOCA frequencies with bounded Johnson distributions and to sample break sizes using uniform distributions. We then develop a new method to distribute LOCA frequencies to different locations within a plant to account for the location-dependent differences while preserving the NUREG-1829 frequencies. We also propose to linearly interpolate the NUREG-1829 LOCA frequencies to obtain the frequencies for any break sizes other than those from NUREG-1829. In addition, we present a method to obtain the distribution of LOCA frequency within a break-size interval providing important inputs to the probabilistic risk assessment quantification for STPNOC. We review methods of combining the probability distributions of multiple experts to obtain a single probability distribution. More specifically, we describe the relative merits of the arithmetic mean (AM) and geometric mean (GM) as ways of performing this aggregation in the context of probabilities associated with rare events. Examining a set of pressurized water reactor results from NUREG-1829, we conclude that the GM represents a consistently sensible notion of the middle of the opinions expressed by nine experts. We further conclude that the AM is inappropriate for representing the center of the group's opinion for large effective break sizes. Instead, as the break size grows large a single expert's opinion dominates the combination produced by the AM. / text
155

Evaluation of input-intensive soybean management systems and the effect of lactofen application on soybean physiology

Orlowski, John M. 01 January 2015 (has links)
In an effort to maximize yields, many soybean growers have begun moving to intensive, input-based soybean management systems. However, limited reliable information exists about the effect of these inputs on soybean yield. The purpose of this study was to evaluate the effect of individual inputs and combinations of inputs as part of high-yield management systems on soybean seed yield and to determine the effect of one of these inputs, lactofen, on soybean physiology. Small plot studies were established in nine states across the Midwest. A number of commercially available soybean inputs were evaluated individually and in combination to determine their effect on soybean yield and quality. Lactofen and comparison treatments were applied to soybeans at multiple growth stages and yield and yield components were determined. When examined across environments, input-intensive combination treatments increased soybean yields from 3.9 to 8.1 %. However, break-even economic analysis indicated that the combination (SOYA) treatments evaluated had 0% probability of breaking across a wide range of yield levels and soybean prices, due to the high input costs. The foliar insecticide showed the highest probability of breaking even across a range of yield levels and crop prices (40% to 99%). Yield increases and breakeven probabilities were generally greatest in the northern states (Minnesota, Wisconsin, Michigan) and similar in the central and southern states. Lactofen application did not kill the apical meristem and had minimal effect on yield components compared to untreated soybeans at any growth stage. Meristem removal increased node m-2 in some environments, but did not increase pods m-2 and seeds m-2 or seed yield.
156

Mapping of UV-Induced Mitotic Recombination in Yeast

Yin, Yi January 2015 (has links)
<p>In diploid yeast cells, mitotic recombination is very important for repairing double-strand breaks (DSB). When repair of a DSB results in crossovers, it may cause loss of heterozygosity (LOH) of markers centromere-distal to the DSB in both daughter cells. Gene conversion events unassociated with crossovers cause LOH for an interstitial section of a chromosome. Alternatively, DSBs can initiate break-induced replication (BIR), causing LOH in only one of the daughter cells. Mapping mitotic LOH contributes to understanding of mechanisms for repairing DSBs and distribution of these recombinogenic lesions. Methods for selecting mitotic crossovers and mapping the positions of crossovers have recently been developed in our lab. Our current approach uses a diploid yeast strain that is heterozygous for about 55,000 SNPs, and employs SNP-Microarrays to map LOH events throughout the genome. These methods allow us to examine selected crossovers on chromosome V and unselected mitotic recombination events (crossovers, gene conversion events unassociated with crossovers, and BIR events) at about 1 kb resolution across the genome.</p><p>Mitotic recombination can be greatly induced by UV radiation. However, prior to my research, the nature of the recombinogenic lesions and the distribution of UV-induced recombination events were relatively uncharacterized. Using SNP microarrays, we constructed maps of UV-induced LOH events in G1-synchronized cells. Mitotic crossovers were stimulated 1500-fold and 8500-fold by UV doses of 1 J/m2 and 15 J/m2, respectively, compared to spontaneous events. Additionally, cells treated with 15 J/m2 have about eight unselected LOH events per pair of sectors, including gene conversions associated and unassociated with crossovers as well as BIR events. These unselected LOH events are distributed randomly throughout the genome with no particular hotspots; however, the rDNA cluster was under-represented for the initiation of crossover and BIR events. Interestingly, we found that a high fraction of recombination events in cells treated with 15 J/m2 reflected repair of two sister chromatids broken at roughly the same position. In cells treated with 1 J/m2, most events reflect repair of a single broken sister chromatid (Chapter 2). </p><p>The primary pathway to remove pyrimidine dimers introduced by UV is the nucleotide excision repair (NER) pathway. In NER, the dimer is excised to generate a 30-nucleotide gap that can be replicated to form DSBs if not filled in before DNA replication. The NER gap can also be expanded by Exo1p to form single stranded gaps greater than one kilobase. Alternatively, in the absence of NER, unexcised dimers could result in blocks of DNA replication forks. Resolving the stalled replication fork could lead to recombinogenic breaks. In Chapter 3 and Chapter 4, we analyzed recombination events in strains defective in various steps of processing of UV-induced DNA damage, including exo1 and rad14 mutants. </p><p>In Chapter 3, I show that Exo1p-expanded NER gaps contribute to UV-induced recombination events. Interestingly, I also found that Exo1p is also required for the hotspot activity of a spontaneous crossover hotspot involving a pair of inverted Ty repeats. In addition to its role of expanding a nick to a long single-stranded gap, Exo1p is also a major player in DSB end resection. Therefore, I examined the gene conversion tract lengths in strains deleted for EXO1. I found that, although crossover-associated gene conversion tracts become shorter in the exo1 mutant as expected, noncrossover tract lengths remained unaffected. As a result, noncrossover tracts are longer than crossover tracts in the exo1 mutant while the opposite result was observed in the wild-type strains. I proposed models to rationalize this observation.</p><p>In Chapter 4, to investigate whether the substantial recombinogenic effect in UV in G1-synchronized cells requires NER, we mapped UV-induced LOH events in NER-deficient rad14 diploids treated with 1 J/m2. Mitotic recombination between homologs was greatly stimulated, which suggests that dimers themselves can also cause recombination without processing by NER. We further show that UV-induced inter-homolog recombination events (noncrossover, crossover and BIR) depend on the resolvase Mus81p, and are suppressed by Mms2p-mediated error-free post-replication repair pathway. </p><p>The research described in Chapters, 2, 3, and 4 are in the publications Yin and Petes (2013), Yin and Petes (2014), and Yin and Petes (2015), respectively.</p> / Dissertation
157

Design of a Mechanically Controllable Break Junction to Measure Quantum Conductance of Gold

Saaty, Kara January 2013 (has links)
A mechanically controllable break junction setup was designed, constructed and characterized. The mechanically controllable break junction technique is commonly used for measurement of quantum conductance of metals and single molecule conductance. The technique relies on resistance to external vibrations disrupting the atomic or molecular junctions formed and should be in a low electronic noise environment. Through a series of experiments the setup was found to have high mechanical stability and low electronic noise. The quantum conductance of gold was measured repeatedly and a histogram was plotted showing good agreement with the literature. The results indicate that with modifications, the setup can be used to measure the conductance of single molecule junctions and single molecule thermoelectric properties.
158

Screening Web Breaks in a Pressroom by Soft Computing

Ahmad, Alzghoul January 2008 (has links)
Web breaks are considered as one of the most significant runnability problems in a pressroom. This work concerns the analysis of relation between various parameters (variables) characterizing the paper, printing press, the printing process and the web break occurrence. A large number of variables, 61 in total, obtained off-line as well as measured online during the printing process are used in the investigation. Each paper reel is characterized by a vector x of 61 components. Two main approaches are explored. The first one treats the problem as a data classification task into "break" and "non break" classes. The procedures of classifier training, the selection of relevant input variables and the selection of hyper-parameters of the classifier are aggregated into one process based on genetic search. The second approach combines procedures of genetic search based variable selection and data mapping into a low dimensional space. The genetic search process results into a variable set providing the best mapping according to some quality function. The empirical study was performed using data collected at a pressroom in Sweden. The total number of data points available for the experiments was equal to 309. Amongst those, only 37 data points represent the web break cases. The results of the investigations have shown that the linear relations between the independent variables and the web break frequency are not strong. Three important groups of variables were identified, namely Lab data (variables characterizing paper properties and measured off-line in a paper mill lab), Ink registry (variables characterizing operator actions aimed to adjust ink registry) and Web tension. We found that the most important variables are: Ink registry Y LS MD (adjustments of yellow ink registry in machine direction on the lower paper side), Air permeability (character- izes paper porosity), Paper grammage, Elongation MD, and four variables characterizing web tension: Moment mean, Min sliding Mean, Web tension variance, and Web tension mean. The proposed methods were helpful in finding the variables influencing the occurrence of web breaks and can also be used for solving other industrial problems.
159

The Frequency of Supernovae in the Early Universe

Melinder, Jens January 2011 (has links)
Supernovae are cosmic explosions of cataclysmic proportion that signify the death of a star. While being interesting phenomena in their own right, their brightness also make them excellent probes of the early universe. Depending on the type of the progenitor star and the origin of the explosion different subjects can be investigated. In this dissertation the work I have done on the detection, characterisation and rate measurements of supernovae in the Stockholm VIMOS Supernova Search is presented. We have discovered 16 supernovae that exploded billions of years ago (or, equivalently, at high redshift, z). The observed brightness and colour evolution have been used to classify the supernovae into either thermonuclear (type Ia) or core collapse (type II) supernovae. The accuracy of the classification code is high, only about 5% of the supernovae are mistyped, similar to other codes of the same kind. By comparing the observed frequency of supernovae to simulations the underlying supernova rate at these high redshifts have been measured. The main result reported in this thesis is that the core collapse supernova rate at high redshift matches the rates estimated from looking at the star formation history of the universe, and agree well with previous studies. The rate of Ia supernovae at high redshift have been investigated by several projects, our results show a somewhat higher rate of Ia supernovae than expected. Proper estimates of the systematic errors of rate measurements are found to be very important. Furthermore, by using novel techniques for reducing and stacking images, we have obtained a galaxy sample containing approximately 50,000 galaxies. Photometric redshifts have been obtained for most of the galaxies, the resulting accuracy below z=1 is on the order of 10%. The galaxy sample has also been used to find high redshift sources, so called Lyman Break Galaxies, at z=3-5. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 3: Manuscript. Paper 4: Manuscript.
160

Application of Block Sieve Bootstrap to Change-Point detection in time series

Zaman, Saad 30 August 2010 (has links)
Since the introduction of CUSUM statistic by E.S. Page (1951), detection of change or a structural break in time series has gained significant interest as its applications span across various disciplines including economics, industrial applications, and environmental data sets. However, many of the early suggested statistics, such as CUSUM or MOSUM, lose their effectiveness when applied to time series data. Either the size or power of the test statistic gets distorted, especially for higher order autoregressive moving average processes. We use the test statistic from Gombay and Serban (2009) for detecting change in the mean of an autoregressive process and show how the application of sieve bootstrap to the time series data can improve the performance of our test to detect change. The effectiveness of the proposed method is illustrated by applying it to economic data sets.

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