Chirurgische Eingriffe am Vormagen des Rindes

Die Ruminotomie hat etwas zu Unrecht in den Status einer Operation, die nur in Sonderfällen durchgeführt werden sollte, erhalten (15). Mit der Etablierung der Ultraschalluntersuchung (11) haben sich die diagnostischen Möglichkeiten bei Vormagenerkrankungen deutlich verbessert. Durch sie konnte auch nachgewiesen werden, dass sich Adhäsionen nach der Entfernung eines stechenden Fremdkörpers bei der Mehrzahl der betroffenen Patienten im Verlauf von mehreren Monaten wieder zurückbilden und die Haubenfunktion sich normalisieren kann (23). Abszesse im Haubenbereich, die zu Tympanien und Störungen des Ingestatransports führen, können mit beachtlicher Erfolgsquote in die Haube oder perkutan drainiert werden (7, 21). In der Praxis gibt es zudem zahlreiche Indikationen, vor allem die Tympanie bei Kalb und Jungrind, bei denen eine temporäre Pansenfistel die Heilung ermöglicht oder fördert (24, 29, 35). In der folgenden Übersicht sollen die Operationstechniken in Erinnerung gerufen, durch Fallbeispiele illustriert und praktisch relevante Aspekte hervorgehoben werden

The Trouble with Sliding Windows and the Selective Pressure in BRCA1

Sliding-window analysis has widely been used to uncover synonymous (silent, dS) and nonsynonymous (replacement, dN) rate variation along the protein sequence and to detect regions of a protein under selective constraint (indicated by dN<dS) or positive selection (indicated by dN>dS). The approach compares two or more protein-coding genes and plots estimates dˆS and dˆN from each sliding window along the sequence. Here we demonstrate that the approach produces artifactual trends of synonymous and nonsynonymous rate variation, with greater variation in dˆS than in dˆN. Such trends are generated even if the true dS and dN are constant along the whole protein and different codons are evolving independently. Many published tests of negative and positive selection using sliding windows that we have examined appear to be invalid because they fail to correct for multiple testing. Instead, likelihood ratio tests provide a more rigorous framework for detecting signals of natural selection affecting protein evolution. We demonstrate that a previous finding that a particular region of the BRCA1 gene experienced a synonymous rate reduction driven by purifying selection is likely an artifact of the sliding window analysis. We evaluate various sliding-window analyses in molecular evolution, population genetics, and comparative genomics, and argue that the approach is not generally valid if it is not known a priori that a trend exists and if no correction for multiple testing is applied

Improved haplotype-based detection of ongoing selective sweeps towards an application in Arabidopsis thaliana

<p>Abstract</p> <p>Background</p> <p>The increasing amount of genome information allows us to address various questions regarding the molecular evolution and population genetics of different species. Such genome-wide data sets including thousands of individuals genotyped at hundreds of thousands of markers require time-efficient and powerful analysis methods. Demography and sampling introduce a bias into present population genetic tests of natural selection, which may confound results. Thus, a modification of test statistics is necessary to introduce time-efficient and unbiased analysis methods.</p> <p>Results</p> <p>We present an improved haplotype-based test of selective sweeps in samples of unequally related individuals. For this purpose, we modified existing tests by weighting the contribution of each individual based on its uniqueness in the entire sample. In contrast to previous tests, this modified test is feasible even for large genome-wide data sets of multiple individuals. We utilize coalescent simulations to estimate the sensitivity of such haplotype-based test statistics to complex demographic scenarios, such as population structure, population growth and bottlenecks. The analysis of empirical data from humans reveals different results compared to previous tests. Additionally, we show that our statistic is applicable to empirical data from <it>Arabidopsis thaliana</it>. Overall, the modified test leads to a slight but significant increase of power to detect selective sweeps among all demographic scenarios.</p> <p>Conclusions</p> <p>The concept of this modification might be applied to other statistics in population genetics to reduce the intrinsic bias of demography and sampling. Additionally, the combination of different test statistics may further improve the performance of tests for natural selection.</p

Web-Frameworks bei der Entwicklung von Web-Applikationen anhand von Apache Struts und JavaServer Faces

Mit dem Internet hat sich eine Technologie etabliert, die Veränderungen in den unterschiedlichsten Bereichen nach sich gezogen hat. Sie ist im Rahmen der Globalisierung zu sehen und ist einer der Hauptakteure bei der Entstehung der Informationsgesellschaft. International und national agierende Unternehmen besitzen einen entscheiden Marktnachteil, wenn diese Technologie nicht gewinnbringend zur Unterstützung ihrer Geschäftsprozesse und deren globaler Vernetzung eingesetzt wird. Einhergehend mit der Entwicklung des Internets sind zahllose Technologien entstanden. Wo es anfänglich nur möglich war, Informationen als feststehende Inhalte zu präsentieren, können und müssen heutige Internetpräsenzen Informationen anbieten, die Zugriff auf verteilt liegende Informationsquellen besitzen, die sich täglich ändern. So sind Web-Applikationen entstanden, die die modernsten Technologien einsetzen, um Anwendern eine Zugangsmöglichkeit auf Informationsquellen über das Internet zu bieten. In Kapitel 2 werden die Anforderungen an Web-Applikationen und deren zugrunde liegende Architektur beleuchtet. Da zahllose Programmiersprachen für die Entwicklung von Web-Applikationen verfügbar sind, wird in Kapitel 3 eine Auswahl an verfügbaren Technologien vorgestellt. Um die Programmierung von Web-Applikationen zu vereinfachen sind im Laufe der letzten Jahre Web-Frameworks entstanden, die den Entwicklungsprozess stark beschleunigen und eine Art Bausatz anbieten, um die Programmierung zu vereinfachen. Der Schwerpunkt der vorliegenden Arbeit richtet sein Augenmerk auf 2 aktuelle Web-Frameworks, die jeweils theoretisch und praxisbezogen anhand einer Beispielapplikation beleuchtet werden. In Kapitel 4 wird JavaServer Faces als erstes Web-Framework vorgestellt. Ausgehend von einer theoretischen Betrachtung wird ein Web-Shop als Beispielapplikation entwickelt und die damit in Zusammenhang stehenden Entwicklungswerkzeuge betrachtet. Auf Struts, als zweites Web-Framework, wird in Kapitel 5 eingegangen und ähnlich wie in Kapitel 4 zu JavaServer Faces wird nach theoretischer Betrachtung des Web-9 Frameworks eine Benutzerverwaltung als Beispielapplikation entwickelt, die die wesentlichsten Aspekte des Web-Frameworks zeigt. Auch hier werden Entwicklungswerkzeuge vorgestellt, die den Umgang mit Struts unterstützen. Schließlich findet in Kapitel 6 ein Vergleich zwischen JavaServer Faces und Struts statt, der mögliche Vor- und Nachteile des jeweiligen Web-Frameworks aufzeigt

Supersonic Micro-Jets And Their Application to Few-Cycle Laser-Driven Electron Acceleration

This thesis covers the few-cycle laser-driven acceleration of electrons in a laser-generated plasma. The so-called \emph{laser wakefield acceleration} is a long-known concept that relies on strongly driven plasma waves for the generation of accelerating gradients in the range of several 100 GV/m. This value is approximately four orders of magnitude larger than the one attainably by classic accelerators, which is limited essentially by electrical breakdown in the accelerating structures to approximately 100 MV/m. Since the acceleration length necessary for obtaining a certain electron energy is inversely proportional to the accelerating field, this leads also to a drastic reduction of the size and of the price of the accelerator. Furthermore, the special properties of laser accelerated electron pulses, namely the ultrashort pulse duration, the high brilliance, and the high charge density, open up new possibilities in many applications of these electron beams. The laser system employed in this work is a new development based on optical parametric chirped pulse amplification and is the only multi-TW few-cycle laser in the world. It allows for the amplification of pulses with a duration of 8 fs up to a power of 6.5 TW. In the experiment, the laser beam is focused onto a supersonic helium gas jet which leads to the formation of a plasma channel. The laser pulse, having an intensity of 10^19 W/cm^2 propagates through the plasma with an electron density of 2x10^19 cm^(-3) and forms via a highly nonlinear interaction a strongly anharmonic plasma wave. The amplitude of the wave is so large that the wave breaks, thereby injecting electrons from the background plasma into the accelerating phase. The energy transfer from the laser pulse to the plasma is so strong that the maximum propagation distance is limited to the 0.1 mm range. Therefore, gas jets specifically tuned to these requirements have to be employed. The properties of microscopic supersonic gas jets are thoroughly analyzed in this work. Based on numeric flow simulation, this study encompasses several extensive parameter studies that illuminate all relevant features of supersonic flows in microscopic gas nozzles. This allowed the optimized design of de Laval nozzles with exit diameters ranging from 0.15 to 3 mm. The employment of these nozzles in the experiment greatly improved the electron beam quality. After these optimizations, the laser-driven electron accelerator now yields monoenergetic electron pulses with energies up to 50 MeV and charges between one and ten pC. The electron beam has a typical divergence of 5 mrad and comprises an energy spectrum that is virtually free from low energetic background. The electron pulse duration could not yet be determined experimentally but simulations point towards values in the range of 1 fs. The acceleration gradient is estimated from simulation and experiment to be approximately 0.5 TV/m. The electron accelerator is routinely operated at 10 Hz, which is a unique feature among laser based accelerators. The light amplification technique employed in the laser system in principle allows here improvements by several orders of magnitude

A comparison of Gap statistic definitions with and without logarithm function

The Gap statistic is a standard method for determining the number of clusters in a set of data. The Gap statistic standardizes the graph of $\log(W_{k})$, where $W_{k}$ is the within-cluster dispersion, by comparing it to its expectation under an appropriate null reference distribution of the data. We suggest to use $W_{k}$ instead of $\log(W_{k})$, and to compare it to the expectation of $W_{k}$ under a null reference distribution. In fact, whenever a number fulfills the original Gap statistic inequality, this number also fulfills the inequality of a Gap statistic using $W_{k}$, but not \textit{vice versa}. The two definitions of the Gap function are evaluated on several simulated data sets and on a real data of DCE-MR images

RAPID TRANSIT, A LAST CHANCE FOR DETROIT?

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Ueber eine einfache Bildungs- und Darstellungs-Weise von Halogenalkylen

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Parallel Rollout for Deterministic Optimal Control

We extend the parallel rollout algorithm for solving deterministic infinite horizon optimal control problems with nonnegative stage costs. Given the exact or approximate cost functions of several base policies, the proposed scheme can harness the presence of multiple computing units. We show that the proposed scheme permits a parallel implementation, and can be viewed as a decomposition method for solving challenging optimization problems that arise in model predictive control (MPC) or related approximation schemes. When applied to problems involving continuous state and control spaces, our method requires computing multiple copies of similar MPC problems with common dynamics and stage costs