On the approximation of the transport equation by the method of weighted residuals

A general class of approximate models for the transport equation is derived by the Weighted Residual Method using polynomial trial and test spaces. For two, particularly relevant, of such models a closed form of the approximate solution is given in the Laplace-transform domain. A strict connection is established between the approximate transfer function and the Padé approximants to exp(-sx). Furthermore it is shown that Galerkin model minimizes in the considered class a measure of the initial state approximation error. Finally an application to the solution of systems of first order hyperbolic equations is reported.     

Romberg extrapolations for numerical schemes solving stochastic differential equations

Let (X_t) be the solution of a stochastic differential system. We consider the following situations: computation of Eƒ(X_t) by a Monte-Carlo method (for example, computation of moments of the solution); integration of ƒ(·) with respect to the invariant probability law of (X_t) (when this process is ergodic); or of the upper Lyapunov exponent, by simulating a single trajectory.

We propose to perform an extrapolation between approximate values due to first-order schemes; we show that this algorithm (simpler to implement than second-order schemes) provides a second-order accuracy, and we give results of numerical tests.     

An intelligent controller for data acquisition from streamer tube calorimeters

We have built an intelligent controller for acquisition and pre-elaboration of data coming from the read-out electronics of streamer tube calorimeters. Its main features are very short acquisition time and low costs.     

The experimental accelerator driven system (XADS) designs in the EURATOM 5th framework programme

The Accelerator-Driven System has the potential to safely fission Minor Actinides and transmute, on industrial scale, selected long-lived fission products into isotopes of lesser concern. European leading nuclear Industrial Companies and Research Centers,within the EURATOM 5th Framework Programme, have studied three solutions of eXperimental Accelerator Driven Systems (XADS), different for the power (80 and 50 MW) or the primary coolant (Lead Bismuth Eutectic and Gas). Two main concepts of Target Unit are envisaged: the Window Target Unit which features a thin metallic sheet as a barrier between the LBE target and the Proton Beam Pipe and the Windowless Target Unit in which the proton beam impinges directly on the free surface of the liquid LBE target. These designs are under study in order to assess and compare them on a common basis, and to outline the main R&D needs.     

Involvement of Fas-mediated apoptosis in the inhibitory effects of interferon-alpha in chronic myelogenous leukemia

Interferon-alpha (IFN-alpha) is an established treatment for chronic myelogenous leukemia (CML) in chronic phase, but the mechanism of its antileukemic activity is not clear. One possible mechanism of action might include the induction of apoptosis, and especially Fas-mediated cell killing may play an important role in the elimination of malignant cells. We investigated Fas receptor (Fas-R) expression and the consequences of Fas-R triggering in CML patients. Using two-color flow cytometry, we found a significantly higher number of Fas-R-expressing CD34+ cells in the bone marrow (BM) of CML patients compared with normal subjects. We have previously shown that IFN-gamma induces Fas-R expression on CD34+ cells; in this study, we investigated whether IFN-alpha induces Fas-R expression on CML progenitor cells. Dose-dependent induction of Fas-R expression was observed after IFN-alpha stimulation of CD34+ cells from CML BM. In methylcellulose culture, IFN-alpha alone at a therapeutic concentration showed only marginal antiproliferative effects on both normal and CML BM progenitors. In contrast, a Fas-R agonist, the anti-CD95 monoclonal antibody CH11, inhibited colony formation from normal progenitors, and the inhibition was even stronger on CML progenitors. When CML BM cells were cultured in the presence of IFN-alpha, Fas-R-mediated inhibition of colony growth was potentiated in a dose-dependent fashion, consistent with IFN-alpha induction of Fas-R expression. This functional effect did not require the presence of accessory cells, since similar results were obtained with purified CD34+ cells. In suspension cultures, we demonstrated that suppression of CML hematopoiesis by IFN-alpha and Fas-R agonist was exerted through Fas-R-mediated induction of apoptosis. Our findings suggest that the Fas-R/Fas-ligand system might be involved in the immunologic regulation of CML progenitor growth and that its effect can be amplified by IFN-alpha.     

Language use in intergroup contexts: The linguistic intergroup bias.

Three experiments examine how the type of language used to describe in-group and out-group behaviors contributes to the transmission and persistence of social stereotypes. Two experiments tested the hypothesis that people encode and communicate desirable in-group and undesirable out-group behaviors more abstractly than undesirable in-group and desirable out-group behaviors. Experiment 1 provided strong support for this hypothesis using a fixed-response scale format controlling for the level of abstractness developed from G. R. Semin and K. Fiedler's (see record 1988-20078-001) linguistic category model. Experiment 2 yielded the same results with a free-response format. Experiment 3 demonstrated the important role that abstract versus concrete communication plays in the perpetuation of stereotypes. The implications of these findings and the use of the linguistic category model are discussed for the examination of the self-perpetuating cycle of stereotypes in communication processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An Introduction to Software Testing

The development of large software systems is a complex and error prone process. Faults might occur at any development stage and they must be identified and removed as early as possible to stop their propagation and reduce verification costs. Quality engineers must be involved in the development process since the very early phases to identify required qualities and estimate their impact on the development process. Their tasks span over the whole development cycle and go beyond the product deployment through maintenance and post mortem analysis. Developing and enacting an effective quality process is not a simple task, but it requires that we integrate many quality-related activities with product characteristics, process organization, available resources and skills, and budget constraints.This paper discusses the main characteristics of a good quality process, then surveys the key testing phases and presents modern functional and model-based testing approaches.     

Σynergos—Synergetic Vision Research

This paper reports the development of a powerful andversatile laboratory for vision research, namely ynergos,which has been developed and implemented under Delphi/Windowsin a distributed systems of microcomputers. The main paradigmunderlying the whole approach consists in integrating severalconcepts and techniques into a single computing environment,i.e. ynergos, in such a way that the requisitesand possibilities of each of the constituent components complementone another and the thus obtained result becomes greater thanthe sum of its parts. The components of ynergosinclude distributed system capabilities and a number of librariescontaining algorithms for: computer vision, modeling and simulationof biological visual systems, data and classification analysis,software validation and comparative evaluation, Internet, off-the-shelfapplication, image databases, artificial intelligence, data mining,and visualization resources. In this paper special emphasis isplaced upon the Internet, distributed implementation and biologicalvision. After outlining the principal requisites and potentialsunderlying each of such components, some specific situationsof interest arising from the integration of two or more of suchelements are described and discussed. Details concerning theintegration with Internet and the implementation of the laboratoryas a distributed system are provided, and a complete case-exampleis presented. This applications regards the implementation ofa psychophysical experiment aimed at investigating human perceptionof pictorial complexity, including the derivation of a mathematic-computationalframework modeling such a perception as well as the use of theInternet as a source of stimuli and for reporting the obtainedresults. In addition, the mathematic-computational model is derivedby using a parallel version of the genetic algorithm runningon the distributed system of PCs. The obtained encouraging resultssubstantiate the potential of this vision laboratory for multidisciplinaryvision research.