The Snail1 transcriptional repressor is a key factor responsible in triggering epithelial to mesenchymal transition. Although Snail1 is widely expressed in early development, it is limited in adult animals to a subset of mesenchymal cells where it has a largely unknown function. In this project we have demonstrated that Snail1 is required to maintain mesenchymal stem cells (MSCs). This effect is associated to the responsiveness to TGF-[beta]1 which showed a strong Snail1 dependence. Snail1-depletion in conditional knock-out adult animals caused a significant decrease in the number of bone marrow-derived MSCs. In culture, Snail1-deficient MSCs prematurely differentiated to osteoblasts or adipocytes and, in contrast to controls, were resistant to the TGF-[beta]1-induced differentiation block. TGF-[beta]1 was unable to up-regulate most of its targets in Snail1 KO MSCs, an effect that was related, but not limited, to defective PTEN repression and Akt activation. Correspondingly, an analysis of human sarcomas also showed enhanced expression of Snail1 in undifferentiated tumors, which was strongly associated with high expression of TGF-[beta] and poor outcome. These results not only demonstrate a new role for Snail1 in TGF-[beta] response and MSC maintenance but also suggest the involvement of MSCs in sarcoma generation. / El repressor transcripcional Snail1 ha estat descrit principalment com el responsable de la inducció de la transició epiteli mesènquima. Encara que Snail1 s’expressa durant les etapes més primerenques del desenvolupament embrionari, la seva expressió en adults es veu limitada en un conjunt de cèl•lules mesenquimals sense saber-se la seva funció. En aquest projecte hem demostrat que Snail1 es requereix per mantenir el fenotip més indiferenciat de les cèl•lules mare del mesènquima. Aquesta funció la fa en part, per la capacitat de resposta de la citoquina TGF-[beta] la qual mostra una força dependència amb Snail1. Quan s’elimina Snail1 en ratolins adults provoca una clara disminució en el nombre de cèl•lules mare de la medul•la òssia. Aquestes cèl•lules en cultiu presenten una clara diferenciació prematura a osteoblasts i adipòcits. Pel contrari, tractaments amb TGF-[beta]1 aturen la diferenciació. El TGF-[beta]1 es incapaç de incrementar moltes dianes en cèl•lules mare del mesènquima aïllades del ratolí deficient per snail1, aquest efecte en part es degut a la repressió de PTEN i l’activació de AKT. L’anàlisi de sarcomes humans ens ha mostrat una alta expressió de Snail1, el qual també es troba associada amb una alta expressió de TGF-[beta] i baixa supervivència. Aquests resultats no només demostren una nova funció per Snail1 en resposta a TGF-[beta] i el manteniment de les MSC, sinó que també suggereix que Snail1 podria participar en la generació del sarcoma.

Syftet med denna rapport har varit att redogöra för och analysera gällande rätt på internationell nivå, EU-nivå och nationell nivå och att undersöka de styrmedel som verkar för att motverka överfiske. Uppsatsens utgångspunkt har varit att den biologiska mångfalden ska främjas i enlighet med CBD. Det övergripande syftet har varit att undersöka om det förekommer sådana brister som motverkar att konventionens mål uppfylls och att identifiera vilka styrmedel som saknas i dagsläget. En rättsvetenskaplig och jämförande metod har använts. Materialet har främst införskaffats från rättskällor såsom författningar, förarbeten, doktrin samt praxis när detta varit relevant, men även webbaserad information från relevanta myndigheter och organisationer. Havet är en unik resurs genom att dess tillgångar typiskt sett är allmänna, vilket kräver styrmedel som skapar incitament till att vårda havets resurser väl och därmed förhindra att allmänningarnas tragedi uppstår. Resultatet visade att förbättringar har skett sedan EU:s gemensamma fiskeripolitik reformerades 2014, men att det ännu finns förbättringsområden.

There exists a vast literature on nonuniform random variate generators. Most of these generators are especially designed for a particular distribution. However in pratice only a few of these are available to practioners. Moreover for problems as (e.g.) sampling from the truncated normal distribution or sampling from fairly uncommon distributions there are often no algorithms available. In the last decade so called universal methods have been developed for these cases. The resulting algorithms are fast and have properties that make them attractive even for standard distributions. In this contribution we describe the concept of Automatic random variate generation where these methods are used to produce a single piece of code in a high level programming language. Using a web-based front-end to such a program this is an easy-to-use source for researchers and programmers for high quality generators for a large class of distributions. Using our UNURAN library we have implemented such a system, which is accessable at <a href="http://statistik.wu-wien.ac.at/anuran" target="_blank">http://statistik.wu-wien.ac.at/anuran</a>. / Series: Preprint Series / Department of Applied Statistics and Data Processing

Eigenvectors of the Laplacian of a graph G have received increasing attention in the recent past. Here we investigate their so-called nodal domains, i.e., the connected components of the maximal induced subgraphs of G on which an eigenvector \psi does not change sign. An analogue of Courant's nodal domain theorem provides upper bounds on the number of nodal domains depending on the location of \psi in the spectrum. This bound, however, is not sharp in general. In this contribution we consider the problem of computing minimal and maximal numbers of nodal domains for a particular graph. The class of Boolean Hypercubes is discussed in detail. We find that, despite the simplicity of this graph class, for which complete spectral information is available, the computations are still non-trivial. Nevertheless, we obtained some new results and a number of conjectures. (author's abstract) / Series: Preprint Series / Department of Applied Statistics and Data Processing

A semiregular tree is a tree where all non-pendant vertices have the same degree. Among all semiregular trees with fixed order and degree, a graph with minimal (adjacency / Laplacian) spectral radius is a caterpillar. Counter examples show that the result cannot be generalized to the class of trees with a given (non-constant) degree sequence. / Series: Research Report Series / Department of Statistics and Mathematics

The Discrete Nodal Domain Theorem states that an eigenfunction of the k-th largest eigenvalue of a generalized graph Laplacian has at most k (weak) nodal domains. We show that the number of strong nodal domains cannot exceed the size of a maximal induced bipartite subgraph and that this bound is sharp for generalized graph Laplacians. Similarly, the number of weak nodal domains is bounded by the size of a maximal bipartite minor. (author's abstract) / Series: Preprint Series / Department of Applied Statistics and Data Processing

We investigate the structure of trees that have minimal algebraic connectivity among all trees with a given degree sequence. We show that such trees are caterpillars and that the vertex degrees are non-decreasing on every path on non-pendant vertices starting at the characteristic set of the Fiedler vector. (author´s abstract) / Series: Research Report Series / Department of Statistics and Mathematics

Made available in DSpace on 2014-06-12T15:51:19Z (GMT). No. of bitstreams: 1 license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2008 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Message Sequence Charts (MSC) é uma linguagem gráfica, usada na academia e na indústria, cujo objetivo é descrever o comportamento de componentes de sistemas e seus ambientes. A sintaxe e a semântica de um diagrama MSC padrão são definidos pelo International Telecommunication Union. A motivação para esse trabalho foi originada a partir de esforços para modelar cenários de aplicações de aparelhos móveis com o objetivo de automatizar a geração de testes, no contexto de uma colaboração entre Centro de Informática da Universidade Federal de Pernambuco (CIn- UFPE) e a Motorola, no contexto do projeto Brasil Test Center (BTC). Ao modelar algumas destas aplicações que envolvem múltipla sincronização utilizando como linguagem de modelagem, MSC padrão, constatou-se que os diagramas são de difícil entendimento ou com um comportamento diferente do desejado. É proposta neste trabalho uma extensão de MSC com o objetivo de permitir a descrição de mensagens síncronas, que permitem descrever eventos instantâneos (abstraindo-se a duração do tempo real para que a conexão seja estabelecida) e podendo envolver várias instâncias de MSC. Essa extensão é conservativa, no sentido que o comportamento das construções existentes não é afetado pela mesma; além disso, em um mesmo diagrama é possível conter mensagens síncronas e mensagens assíncronas. Foi desenvolvido um algoritmo de transformação, que a partir de um diagrama escrito na notação MSC estendido, gera um diagrama correspondente na notação de MSC padrão. Este algoritmo tem por objetivo permitir a transitividade entre as notações e demonstrar suas equivalências. Este algoritmo de transformação implementa mensagens síncronas como uma seqüência de mensagens assíncronas seguindo um algoritmo particular de handshake. A segunda contribuição desse trabalho é a definição de uma semântica para a notação padrão e estendida de MSC. Essa definição é dada em termos da álgebra de processos CSP (Communicating Sequential Processes). O formalismo introduzido na notação de Message Sequence Charts com CSP permite mostrar a equivalência entre um diagrama na notação de MSC estendido e seu correspondente descrito em MSC padrão, gerado a partir do algoritmo de transformação. Além disso, modelar MSC como um processo descrito na notação CSP permite uma análise sobre seus diagramas, usando um rico conjunto de leis algébricas de CSP, bem como o uso de ferramentas, como FDR2 e o Probe. Finalmente, para validar a estratégia proposta, desenvolveu-se um exemplo que ilustra a utilização da notação estendida de MSC, notação síncrona; a conversão desta notação para a notação padrão e a equivalência entre o MSC estendido e o padrão. Mostramos, ainda, o uso da ferramenta Power Tool Kit(PTK) para geração de casos de teste a partir de diagramas MSC

We reinvestigate the validity of mapping the problem of two onsite interacting particles in a random potential onto an effective random matrix model. To this end we first study numerically how the non-interacting basis is coupled by the interaction. Our results indicate that the typical coupling matrix element decreases significantly faster with increasing single-particle localization length than is assumed in the random matrix model. We further show that even for models where the dependency of the coupling matrix element on the single-particle localization length is correctly described by the corresponding random matrix model its predictions for the localization length can be qualitatively incorrect. These results indicate that the mapping of an interacting random system onto an effective random matrix model is potentially dangerous. We also discuss how Imry's block-scaling picture for two interacting particles is influenced by the above arguments.

Asynchronous iterations often converge under different conditions than their syn- chronous counterparts. In this paper we will study the global convergence of Jacobi- Newton-like methods for nonlinear equationsF x = 0. It is a known fact, that the synchronous algorithm converges monotonically, ifF is a convex M-function and the starting valuesx0 andy0 meet the conditionF x04 04F y0 . In the paper it will be shown, which modifications are necessary to guarantee a similar convergence behavior for an asynchronous computation.