Conformation analysis of a surface loop that controls active site access in the GH11 xylanase A from Bacillus subtilis

Xylanases (EC 3.2.1.8 endo-1,4-glycosyl hydrolase) catalyze the hydrolysis of xylan, an abundant hemicellulose of plant cell walls. Access to the catalytic site of GH11 xylanases is regulated by movement of a short beta-hairpin, the so-called thumb region, which can adopt open or closed conformations. A crystallographic study has shown that the D11F/R122D mutant of the GH11 xylanase A from Bacillus subtilis (BsXA) displays a stable "open" conformation, and here we report a molecular dynamics simulation study comparing this mutant with the native enzyme over a range of temperatures. The mutant open conformation was stable at 300 and 328 K, however it showed a transition to the closed state at 338 K. Analysis of dihedral angles identified thumb region residues Y113 and T123 as key hinge points which determine the open-closed transition at 338 K. Although the D11F/R122D mutations result in a reduction in local inter-intramolecular hydrogen bonding, the global energies of the open and closed conformations in the native enzyme are equivalent, suggesting that the two conformations are equally accessible. These results indicate that the thumb region shows a broader degree of energetically permissible conformations which regulate the access to the active site region. The R122D mutation contributes to the stability of the open conformation, but is not essential for thumb dynamics, i.e., the wild type enzyme can also adapt to the open conformation.

Fluoxetine exposure during pregnancy and lactation: effects on acute stress response and behavior in the novelty-suppressed feeding are age and gender-dependent in rats

Fluoxetine (FLX) is commonly used to treat anxiety and depressive disorders in pregnant women. Since FLX crosses the placenta and is excreted in milk, maternal treatment with this antidepressant may expose the fetus and neonate to increased levels of serotonin (5-HT). Long-term behavioral abnormalities have been reported in rodents exposed to higher levels of 5-HT during neurodevelopment. In this study we evaluated if maternal exposure to FLX during pregnancy and lactation would result in behavioral and/or stress response disruption in adolescent and adult rats. Our results indicate that exposure to FLX influenced restraint stress-induced Fos expression in the amygdala in a gender and age-specific manner. In male animals, a decreased expression was observed in the basolateral amygdala at adolescence and adulthood; whereas at adulthood, a decrease was also observed in the medial amygdala. A lack of FLX exposure effect was observed in females and also in the paraventricular nucleus of both genders. Regarding the behavioral evaluation, FLX exposure did not induce anhedonia in the sucrose preference test but decreased the latency to feed of both male and female adolescent rats evaluated in the novelty-suppressed feeding test. In conclusion, FLX exposure during pregnancy and lactation decreases acute amygdalar stress response to a psychological stressor in males (adolescents and adults) as well as influences the behavior of adolescents (males and females) in a model that evaluates anxiety and/or depressive-like behavior. Even though FLX seems to be a developmental neurotoxicant, the translation of these findings to human safe assessment remains to be determined since it is recognized that not treating a pregnant or lactating woman may also impact negatively the development of the descendants.

Chronic unpredictable mild stress alters an anxiety-related defensive response, Fos immunoreactivity and hippocampal adult neurogenesis

Previous results show that elevated T-maze (ETM) avoidance responses are facilitated by acute restraint. Escape, on the other hand, was unaltered. To examine if the magnitude of the stressor is an important factor influencing these results, we investigated the effects of unpredictable chronic mild stress (UCMS) on ETM avoidance and escape measurements. Analysis of Fos protein immunoreactivity (Fos-ir) was used to map areas activated by stress exposure in response to ETM avoidance and escape performance. Additionally, the effects of the UCMS protocol on the number of cells expressing the marker of migrating neuroblasts doublecortin (DCX) in the hippocampus were investigated. Corticosterone serum levels were also measured. Results showed that UCMS facilitates ETM avoidance, not altering escape. In unstressed animals, avoidance performance increases Fos-ir in the cingulate cortex, hippocampus (dentate gyrus) and basomedial amygdala, and escape increases Fos-ir in the dorsolateral periaqueductal gray and locus ceruleus. In stressed animals submitted to ETM avoidance, increases in Fos-ir were observed in the cingulate cortex, ventrolateral septum, hippocampus, hypothalamus, amygdala, dorsal and median raphe nuclei. In stressed animals submitted to ETM escape, increases in Fos-ir were observed in the cingulate cortex, periaqueductal gray and locus ceruleus. Also, UCMS exposure decreased the number of DCX-positive cells in the dorsal and ventral hippocampus and increased corticosterone serum levels. These data suggest that the anxiogenic effects of UCMS are related to the activation of specific neurobiological circuits that modulate anxiety and confirm that this stress protocol activates the hypothalamus-pituitary-adrenal axis and decreases hippocampal adult neurogenesis.

A Unified Framework for e-Commerce Systems Development : Business Process Pattern Perspective

In electronic commerce, systems development is based on two fundamental types of models, business models and process models. A business model is concerned with value exchanges among business partners, while a process model focuses on operational and procedural aspects of business communication. Thus, a business model defines the what in an e-commerce system, while a process model defines the how. Business process design can be facilitated and improved by a method for systematically moving from a business model to a process model. Such a method would provide support for traceability, evaluation of design alternatives, and seamless transition from analysis to realization. This work proposes a unified framework that can be used as a basis to analyze, to interpret and to understand different concepts associated at different stages in e-Commerce system development. In this thesis, we illustrate how UN/CEFACT’s recommended metamodels for business and process design can be analyzed, extended and then integrated for the final solutions based on the proposed unified framework. Also, as an application of the framework, we demonstrate how process-modeling tasks can be facilitated in e-Commerce system design. The proposed methodology, called BP3 stands for Business Process Patterns Perspective. The BP3 methodology uses a question-answer interface to capture different business requirements from the designers. It is based on pre-defined process patterns, and the final solution is generated by applying the captured business requirements by means of a set of production rules to complete the inter-process communication among these patterns.

Analisi sperimentale degli effetti di temperature elevate sul comportamento strutturale dei rinforzi in FRP

In questa tesi si è voluta porre l’attenzione sulla suscettibilità alle alte temperature delle resine che li compongono. Lo studio del comportamento alle alte temperature delle resine utilizzate per l’applicazione dei materiali compositi è risultato un campo di studio ancora non completamente sviluppato, nel quale c’è ancora necessità di ricerche per meglio chiarire alcuni aspetti del comportamento. L’analisi di questi materiali si sviluppa partendo dal contesto storico, e procedendo successivamente ad una accurata classificazione delle varie tipologie di materiali compositi soffermandosi sull’ utilizzo nel campo civile degli FRP (Fiber Reinforced Polymer) e mettendone in risalto le proprietà meccaniche. Considerata l’influenza che il comportamento delle resine riveste nel comportamento alle alte temperature dei materiali compositi si è, per questi elementi, eseguita una classificazione in base alle loro proprietà fisico-chimiche e ne sono state esaminate le principali proprietà meccaniche e termiche quali il modulo elastico, la tensione di rottura, la temperatura di transizione vetrosa e il fenomeno del creep. Sono state successivamente eseguite delle prove sperimentali, effettuate presso il Laboratorio Resistenza Materiali e presso il Laboratorio del Dipartimento di Chimica Applicata e Scienza dei Materiali, su dei provini confezionati con otto differenti resine epossidiche. Per valutarne il comportamento alle alte temperature, le indagini sperimentali hanno valutato dapprima le temperature di transizione vetrosa delle resine in questione e, in seguito, le loro caratteristiche meccaniche. Dalla correlazione dei dati rilevati si sono cercati possibili legami tra le caratteristiche meccaniche e le proprietà termiche delle resine. Si sono infine valutati gli aspetti dell’applicazione degli FRP che possano influire sul comportamento del materiale composito soggetto alle alte temperature valutando delle possibili precauzioni che possano essere considerate in fase progettuale.

Longitudinal bar buckling behavior

Reinforced concrete columns might fail because of buckling of the longitudinal reinforcing bar when exposed to earthquake motions. Depending on the hoop stiffness and the length-over-diameter ratio, the instability can be local (in between two subsequent hoops) or global (the buckling length comprises several hoop spacings). To get insight into the topic, an extensive literary research of 19 existing models has been carried out including different approaches and assumptions which yield different results. Finite element fiberanalysis was carried out to study the local buckling behavior with varying length-over-diameter and initial imperfection-over-diameter ratios. The comparison of the analytical results with some experimental results shows good agreement before the post buckling behavior undergoes large deformation. Furthermore, different global buckling analysis cases were run considering the influence of different parameters; for certain hoop stiffnesses and length-over-diameter ratios local buckling was encountered. A parametric study yields an adimensional critical stress in function of a stiffness ratio characterized by the reinforcement configuration. Colonne in cemento armato possono collassare per via dell’instabilità dell’armatura longitudinale se sottoposte all’azione di un sisma. In funzione della rigidezza dei ferri trasversali e del rapporto lunghezza d’inflessione-diametro, l’instabilità può essere locale (fra due staffe adiacenti) o globale (la lunghezza d’instabilità comprende alcune staffe). Per introdurre alla materia, è proposta un’esauriente ricerca bibliografica di 19 modelli esistenti che include approcci e ipotesi differenti che portano a risultati distinti. Tramite un’analisi a fibre e elementi finiti si è studiata l’instabilità locale con vari rapporti lunghezza d’inflessione-diametro e imperfezione iniziale-diametro. Il confronto dei risultati analitici con quelli sperimentali mostra una buona coincidenza fino al raggiungimento di grandi spostamenti. Inoltre, il caso d’instabilità globale è stato simulato valutando l’influenza di vari parametri; per certe configurazioni di rigidezza delle staffe e lunghezza d’inflessione-diametro si hanno ottenuto casi di instabilità locale. Uno studio parametrico ha permesso di ottenere un carico critico adimensionale in funzione del rapporto di rigidezza dato dalle caratteristiche dell’armatura.

Useful computer vision techniques for human-robot interaction

[ES]This paper describes some simple but useful computer vision techniques for human-robot interaction. First, an omnidirectional camera setting is described that can detect people in the surroundings of the robot, giving their angular positions and a rough estimate of the distance. The device can be easily built with inexpensive components. Second, we comment on a color-based face detection technique that can alleviate skin-color false positives. Third, a simple head nod and shake detector is described, suitable for detecting affirmative/negative, approval/dissaproval, understanding/disbelief head gestures.

COBAMOS: Endnutzerprogrammierung auf Basis nachrichtenbasierter Komponentenvernetzung

Die Aufgabenstellung, welche dieser Dissertation zugrunde liegt, lässt sich kurz als die Untersuchung von komponentenbasierten Konzepten zum Einsatz in der Softwareentwicklung durch Endanwender beschreiben. In den letzten 20 bis 30 Jahren hat sich das technische Umfeld, in dem ein Großteil der Arbeitnehmer seine täglichen Aufgaben verrichtet, grundlegend verändert. Der Computer, früher in Form eines Großrechners ausschließlich die Domäne von Spezialisten, ist nun ein selbstverständlicher Bestandteil der täglichen Arbeit. Der Umgang mit Anwendungsprogrammen, die dem Nutzer erlauben in einem gewissen Rahmen neue, eigene Funktionalität zu definieren, ist in vielen Bereichen so selbstverständlich, dass viele dieser Tätigkeiten nicht bewusst als Programmieren wahrgenommen werden. Da diese Nutzer nicht notwendigerweise in der Entwicklung von Software ausgebildet sind, benötigen sie entsprechende Unterstützung bei diesen Tätigkeiten. Dies macht deutlich, welche praktische Relevanz die Untersuchungen in diesem Bereich haben. Zur Erstellung eines Programmiersystems für Endanwender wird zunächst ein flexibler Anwendungsrahmen entwickelt, welcher sich als Basis zur Erstellung solcher Systeme eignet. In Softwareprojekten sind sich ändernde Anforderungen und daraus resultierende Notwendigkeiten ein wichtiger Aspekt. Dies wird im Entwurf des Frameworks durch Konzepte zur Bereitstellung von wieder verwendbarer Funktionalität durch das Framework und Möglichkeiten zur Anpassung und Erweiterung der vorhandenen Funktionalität berücksichtigt. Hier ist zum einen der Einsatz einer serviceorientierten Architektur innerhalb der Anwendung und zum anderen eine komponentenorientierte Variante des Kommando-Musters zu nennen. Zum anderen wird ein Konzept zur Kapselung von Endnutzerprogrammiermodellen in Komponenten erarbeitet. Dieser Ansatz ermöglicht es, unterschiedliche Modelle als Grundlage der entworfenen Entwicklungsumgebung zu verwenden. Im weiteren Verlauf der Arbeit wird ein Programmiermodell entworfen und unter Verwendung des zuvor genannten Frameworks implementiert. Damit dieses zur Nutzung durch Endanwender geeignet ist, ist eine Anhebung der zur Beschreibung eines Softwaresystems verwendeten Abstraktionsebene notwendig. Dies wird durch die Verwendung von Komponenten und einem nachrichtenbasierten Kompositionsmechanismus erreicht. Die vorgenommene Realisierung ist dabei noch nicht auf konkrete Anwendungsfamilien bezogen, diese Anpassungen erfolgen in einem weiteren Schritt für zwei unterschiedliche Anwendungsbereiche.

Web advertising. Le comunicazioni commerciali on-line.

La tesi ha ad oggetto lo studio e l’approfondimento delle forme di promozione commerciale presenti in Rete caratterizzate, più che da una normale evoluzione, da continue metamorfosi che ridefiniscono ogni giorno il concetto di pubblicità. L’intento è quello di analizzare il quadro giuridico applicabile alla pubblicità via Web, a fronte della varità di forme e di modalità che essa può assumere. Nel lavoro vengono passate in rassegna le caratteristiche che differenziano la pubblicità commerciale on-line rispetto a quella tradizionale; tra le quali, particolare rilievo assume la capacità d’istaurare una relazione – diretta e non mediata – tra impresa e consumatore. Nel prosieguo viene affrontato il problema dell’individuazione, stante il carattere a-territoriale della Rete, della legge applicabile al web advertising, per poi passare ad una ricognizione delle norme europee ed italiane in materia, senza trascurare quelle emanate in sede di autodisciplina. Ampio spazio è dedicato, infine, all’esame delle diverse e più recenti tecniche di promozione pubblicitaria, di cui sono messi in evidenza gli aspetti tecnico-informatici, imprescindibili ai fini di una corretta valutazione del tema giuridico. In particolare, vengono approfonditi il servizio di posizionamento a pagamento offerto dai principali motori di ricerca (keywords advertising) e gli strumenti di tracciamento dei “comportamenti” on-line degli utenti, che consentono la realizzazione di campagne pubblicitarie mirate (on-line behavioural advertising). Il Web, infatti, non offre più soltanto la possibilità di superare barriere spaziali, linguistiche o temporali e di ampliare la propria sfera di notorietà, ma anche di raggiungere l’utente “interessato” e, pertanto, potenziale acquirente. Di queste nuove realtà pubblicitarie vengono vagliati gli aspetti più critici ed esaminata la disciplina giuridica eventualmente applicabile anche alla luce delle principali decisioni giurisprudenziali nazionali ed europee in materia, nonché delle esperienze giuridiche nord-americane e di tipo autoregolamentare.

High precision swept volume approximation with conservative error bounds

In technical design processes in the automotive industry, digital prototypes rapidly gain importance, because they allow for a detection of design errors in early development stages. The technical design process includes the computation of swept volumes for maintainability analysis and clearance checks. The swept volume is very useful, for example, to identify problem areas where a safety distance might not be kept. With the explicit construction of the swept volume an engineer gets evidence on how the shape of components that come too close have to be modified.rnIn this thesis a concept for the approximation of the outer boundary of a swept volume is developed. For safety reasons, it is essential that the approximation is conservative, i.e., that the swept volume is completely enclosed by the approximation. On the other hand, one wishes to approximate the swept volume as precisely as possible. In this work, we will show, that the one-sided Hausdorff distance is the adequate measure for the error of the approximation, when the intended usage is clearance checks, continuous collision detection and maintainability analysis in CAD. We present two implementations that apply the concept and generate a manifold triangle mesh that approximates the outer boundary of a swept volume. Both algorithms are two-phased: a sweeping phase which generates a conservative voxelization of the swept volume, and the actual mesh generation which is based on restricted Delaunay refinement. This approach ensures a high precision of the approximation while respecting conservativeness.rnThe benchmarks for our test are amongst others real world scenarios that come from the automotive industry.rnFurther, we introduce a method to relate parts of an already computed swept volume boundary to those triangles of the generator, that come closest during the sweep. We use this to verify as well as to colorize meshes resulting from our implementations.

Software tools and efficient algorithms for the feature detection, feature tracking, event localization, and visualization of large sets of atmospheric data

Data sets describing the state of the earth's atmosphere are of great importance in the atmospheric sciences. Over the last decades, the quality and sheer amount of the available data increased significantly, resulting in a rising demand for new tools capable of handling and analysing these large, multidimensional sets of atmospheric data. The interdisciplinary work presented in this thesis covers the development and the application of practical software tools and efficient algorithms from the field of computer science, aiming at the goal of enabling atmospheric scientists to analyse and to gain new insights from these large data sets. For this purpose, our tools combine novel techniques with well-established methods from different areas such as scientific visualization and data segmentation. In this thesis, three practical tools are presented. Two of these tools are software systems (Insight and IWAL) for different types of processing and interactive visualization of data, the third tool is an efficient algorithm for data segmentation implemented as part of Insight.Insight is a toolkit for the interactive, three-dimensional visualization and processing of large sets of atmospheric data, originally developed as a testing environment for the novel segmentation algorithm. It provides a dynamic system for combining at runtime data from different sources, a variety of different data processing algorithms, and several visualization techniques. Its modular architecture and flexible scripting support led to additional applications of the software, from which two examples are presented: the usage of Insight as a WMS (web map service) server, and the automatic production of a sequence of images for the visualization of cyclone simulations. The core application of Insight is the provision of the novel segmentation algorithm for the efficient detection and tracking of 3D features in large sets of atmospheric data, as well as for the precise localization of the occurring genesis, lysis, merging and splitting events. Data segmentation usually leads to a significant reduction of the size of the considered data. This enables a practical visualization of the data, statistical analyses of the features and their events, and the manual or automatic detection of interesting situations for subsequent detailed investigation. The concepts of the novel algorithm, its technical realization, and several extensions for avoiding under- and over-segmentation are discussed. As example applications, this thesis covers the setup and the results of the segmentation of upper-tropospheric jet streams and cyclones as full 3D objects. Finally, IWAL is presented, which is a web application for providing an easy interactive access to meteorological data visualizations, primarily aimed at students. As a web application, the needs to retrieve all input data sets and to install and handle complex visualization tools on a local machine are avoided. The main challenge in the provision of customizable visualizations to large numbers of simultaneous users was to find an acceptable trade-off between the available visualization options and the performance of the application. Besides the implementational details, benchmarks and the results of a user survey are presented.

Experimental Comparison of Bluetooth and WiFi Signal Propagation for Indoor Localisation

Systems for indoor positioning using radio technologies are largely studied due to their convenience and the market opportunities they offer. The positioning algorithms typically derive geographic coordinates from observed radio signals and hence good understanding of the indoor radio channel is required. In this paper we investigate several factors that affect signal propagation indoors for both Bluetooth and WiFi. Our goal is to investigate which factors can be disregarded and which should be considered in the development of a positioning algorithm. Our results show that technical factors such as device characteristics have smaller impact on the signal than multipath propagation. Moreover, we show that propagation conditions differ in each direction. We also noticed that WiFi and Bluetooth, despite operating in the same radio band, do not at all times exhibit the same behaviour.