Bayesian inference for latent factor copulas and application to financial risk forecasting

Factor modeling is a popular strategy to induce sparsity in multivariate models as they scale to higher dimensions. We develop Bayesian inference for a recently proposed latent factor copula model, which utilizes a pair copula construction to couple the variables with the latent factor. We use adaptive rejection Metropolis sampling (ARMS) within Gibbs sampling for posterior simulation: Gibbs sampling enables application to Bayesian problems, while ARMS is an adaptive strategy that replaces traditional Metropolis-Hastings updates, which typically require careful tuning. Our simulation study shows favorable performance of our proposed approach both in terms of sampling efficiency and accuracy. We provide an extensive application example using historical data on European financial stocks that forecasts portfolio Value at Risk (VaR) and Expected Shortfall (ES)

Left ventricular hypertrabeculation/noncompaction with epilepsy, other heart defects, minor facial anomalies and new copy number variants

BACKGROUND: Left ventricular hypertrabeculation/noncompaction (LVHT) is a cardiac abnormality of unknown etiology which has been described in children as well as in adults with and without chromosomal aberrations. LVHT has been reported in association with various cardiac and extracardiac abnormalities like epilepsy and facial dysmorphism. CASE PRESENTATION: A unique combination of LVHT, atrial septal defect, pulmonary valve stenosis, aortic stenosis, epilepsy and minor facial anomalies is presented in a 5.5 years old girl. Microarray-based genomic hybridization (array-CGH) detected six previously not described copy number variants (CNVs) inherited from a clinically unaffected father and minimally affected mother, thus, most likely, not clinically significant but rare benign variants. CONCLUSIONS: Despite this complex phenotype de novo microdeletions or microduplications were not detected by array CGH. Further investigations, such as whole exome sequencing, could reveal point mutations and small indels as the possible cause

Bayesian Model Selection of Regular Vine Copulas

Regular vine copulas are a flexible class of dependence models, but Bayesian methodology for model selection and inference is not yet fully developed. We propose sparsity-inducing but otherwise non-informative priors, and present novel proposals to enable reversible jump Markov chain Monte Carlo posterior simulation for Bayesian model selection and inference. Our method is the first to jointly estimate the posterior distribution of all trees of a regular vine copula. This represents a substantial improvement over existing frequentist and Bayesian strategies, which can only select one tree at a time and are known to induce bias. A simulation study demonstrates the feasibility of our strategy and shows that it combines superior selection and reduced computation time compared to Bayesian tree-by-tree selection. In a real data example, we forecast the daily expected tail loss of a portfolio of nine exchange-traded funds using a fully Bayesian multivariate dynamic model built around Bayesian regular vine copulas to illustrate our model’s viability for financial analysis and risk estimation

Western Blot of Stained Proteins from Dried Polyacrylamide Gels

Western blotting of proteins is customarily performed following their separation on polyacrylamide gels, either prior to staining (1) or, as recently reported, following staining (2). We describe here Western blotting with stained gels, which had been dried and some of which had been stored for years. This procedure permits immunological analysis of proteins, to which antisera may have become available only later, or where the application of newly developed sensitive detection methods is desired. Once rehydration of the gels is achieved, proteins can be-transferred to blotting membranes by any appropriate protocol. Proteins stained with Coomassie Blue have to be detected with a non-chromogenic method, such as the film-based enhanced chemiluminescence (ECL)2) procedure (3). Silver stained proteins, which transfer in the colorless form, may be visualized by any detection method, although, because of the usually very low amounts of proteins, detection by ECL is preferable. Blotting of stained proteins from rehydrated gels is as rapid and as quantitative as from freshly prepared gels, in contrast to blotting from wet stained gels, which requires extensive washing and results in low transfer efficiency (2). Together with a photographic record of the gel pattern, unambiguous identification of immunoreactive proteins from complex mixtures is possible. Some further applications of this work are discussed

Protein disulfide-isomerase interacts with a substrate protein at all stages along its folding pathway

In contrast to molecular chaperones that couple protein folding to ATP hydrolysis, protein disulfide-isomerase (PDI) catalyzes protein folding coupled to formation of disulfide bonds (oxidative folding). However, we do not know how PDI distinguishes folded, partly-folded and unfolded protein substrates. As a model intermediate in an oxidative folding pathway, we prepared a two-disulfide mutant of basic pancreatic trypsin inhibitor (BPTI) and showed by NMR that it is partly-folded and highly dynamic. NMR studies show that it binds to PDI at the same site that binds peptide ligands, with rapid binding and dissociation kinetics; surface plasmon resonance shows its interaction with PDI has a Kd of ca. 10−5 M. For comparison, we characterized the interactions of PDI with native BPTI and fully-unfolded BPTI. Interestingly, PDI does bind native BPTI, but binding is quantitatively weaker than with partly-folded and unfolded BPTI. Hence PDI recognizes and binds substrates via permanently or transiently unfolded regions. This is the first study of PDI's interaction with a partly-folded protein, and the first to analyze this folding catalyst's changing interactions with substrates along an oxidative folding pathway. We have identified key features that make PDI an effective catalyst of oxidative protein folding – differential affinity, rapid ligand exchange and conformational flexibility

Möbeldekor aus Elfenbein

Die Arbeit befaßt sich mit der Rekonstruktion von Elfenbeinen, die aus Ausgrabungen im Vorderen Orient stammen und als Möbelverzierung angesprochen werden. Anhand eines ikonographischen Vergleichs mit Denkmälern der entsprechenden Regionen, Assyrien, Nordsyrien/Südostkleinasien und Phönizien, und unter Einbeziehung von Originalmaterial wird versucht, theoretische Möglichkeiten einer Rekonstruktion zu erarbeiten. Besondere Aufmerksamkeit wird den technischen Merkmalen an den Elfenbeinen geschenkt, die Auskunft über Herstellung und Befestigung mit dem Trägermöbel geben. Ein Überblick über generelle Gestaltungsprinzipien in den altorientalischen Kulturen leitet konkrete Vorschläge für die Zusammenfügung der Elfenbeindekoration an verschiedenen Möbel ein

De Dinorá às mocinhas do Passeio : as guerras conjugais no universo boêmio de Dalton Trevisan

Orientadora: Profª Drª Regina Maria PrzybycienDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Humanas, Letras e Artes, Programa de Pós-Graduação em Letras. Defesa: Curitiba, 2007Inclui bibliografi

Exploring European Writing Cultures : Country Reports on Genres, Writing Practices and Languages Used in European Higher Education

At European universities, writing is a traditional way of learning, assessment, and independent study, but it is handled in an implicit, tradition-based way that has only recently been contrasted with and supported by a more explicit writing ped-agogy. Still, little systematic knowledge is available about the pedagogical ap-proaches to writing, writing practices, and genres across Europe and much of it is codified in the national languages without correlation to internationally accept-ed terminology and theories. This book explores the writing cultures of Europe, nation by nation, and reports the idiosyncrasies for each respective country. The reports are based on a 17-item topic list used by the authors to collect data be-fore synthesizing the results. Next to writing practices and genres, a high level of emphasis was placed on the structure of educational systems, the languages in use, and the kind of support provided for student writers. Note: This research project has been conducted within the framework of COST Action IS0703 “European Research Network on Learning to Write Effectively”, funded by the European Union. We are also thankful to Christiane Donahue, Eliza Kitis, Charles Bazerman, Helmut Gruber, and David Russell for their cooperation and support in this project.Wissenschaftliches Schreiben an europäischen Hochschulen ist eine herkömmliche Form des Lernens, Prüfens und autonomen Studierens, auch wenn es in einer impliziten, eher auf Tradition denn auf bewusster Didaktik beruhenden Weise eingesetzt wird. Wenig auf systematische Weise erhobenes vergleichendes Wissen gibt es bislang über Schreibpraktiken, Genres und schreibdidaktische Ansätze in Europa und das, was an Wissen existiert ist oft in den nationalen Sprachen verfasst, die nicht mit internationalen Terminologien und Theorien der Schreibwissenschaft verbunden sind. Der vorliegende Band untersucht Schreibkulturen in Europa Land für Land und berichtet was jeweils hervorsticht. Die Berichte basieren auf einer 17-Item Themenliste, nach der die Autorenteams Daten über ihr jeweiliges Land sammelten, bevor sie es zu einem Bericht synthetisierten. Neben Schreibpraktiken und Genres werden dabei die Struktur des jeweiligen Bildungssystems, die verwendeten Sprachen und die besondere Schreibdidaktik hervorgehoben. Anmerkung: Das Projekt wurde im Rahmen der COST Aktion IS0703 “European Research Network on Learning to Write Effectively” durchgeführt, das von der EU finanziert wird. Wir bedanken uns bei Christiane Donahue, Eliza Kitis, Charles Bazerman, Helmut Gruber und David Russell für ihre Unterstützung und Mitwirkung in diesem Projekt.At European universities, writing is a traditional way of learning, assessment, and independent study, but it is handled in an implicit, tradition-based way that has only recently been contrasted with and supported by a more explicit writing ped-agogy. Still, little systematic knowledge is available about the pedagogical ap-proaches to writing, writing practices, and genres across Europe and much of it is codified in the national languages without correlation to internationally accept-ed terminology and theories. This book explores the writing cultures of Europe, nation by nation, and reports the idiosyncrasies for each respective country. The reports are based on a 17-item topic list used by the authors to collect data be-fore synthesizing the results. Next to writing practices and genres, a high level of emphasis was placed on the structure of educational systems, the languages in use, and the kind of support provided for student writers. Note: This research project has been conducted within the framework of COST Action IS0703 “European Research Network on Learning to Write Effectively”, funded by the European Union. We are also thankful to Christiane Donahue, Eliza Kitis, Charles Bazerman, Helmut Gruber, and David Russell for their cooperation and support in this project