From Pre-Historic to Post-Modern Symbolic Model Checking

Symbolic model checking, which enables the automatic verification of large systems, proceeds by calculating expressions that represent state sets. Traditionally, symbolic model-checking tools are based on backward state traversal; their basic operation is the function pre, which, given a set of states, returns the set of all predecessor states. This is because specifiers usually employ formalisms with future-time modalities, which are naturally evaluated by iterating applications of pre. It has been shown experimentally that symbolic model checking can perform significantly better if it is based, instead, on forward state traversal; in this case, the basic operation is the function post, which, given a set of states, returns the set of all successor states. This is because forward state traversal can ensure that only parts of the state space that are reachable from an initial state and relevant for the satisfaction or violation of the specification are explored; that is, errors can be detected as soon as possible.In this paper, we investigate which specifications can be checked by symbolic forward state traversal. We formulate the problems of symbolic backward and forward model checking by means of two h2856/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">-calculi. The pre-h2856/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0"> calculus is based on the pre operation, and the post-h2856/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0"> calculus is based on the post operation. These two h2856/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">-calculi induce query logics, which augment fixpoint expressions with a boolean emptiness query. Using query logics, we are able to relate and compare the symbolic backward and forward approaches. In particular, we prove that all h2856/xxlarge969.gif" alt="ohgr" align="BASELINE" BORDER="0">-regular (linear-time) specifications can be expressed as post-h2856/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0"> queries, and therefore checked using symbolic forward state traversal. On the other hand, we show that there are simple branching-time specifications that cannot be checked in this way.     

Texture analysis of poly-adenylated mRNA staining following global brain ischemia and reperfusion

Texture analysis provides a means to quantify complex changes in microscope images. We previously showed that cytoplasmic poly-adenylated mRNAs form mRNA granules in post-ischemic neurons and that these granules correlated with protein synthesis inhibition and hence cell death. Here we utilized the texture analysis software MaZda to quantify mRNA granules in photomicrographs of the pyramidal cell layer of rat hippocampal region CA3 around 1 h of reperfusion after 10 min of normothermic global cerebral ischemia. At 1 h reperfusion, we observed variations in the texture of mRNA granules amongst samples that were readily quantified by texture analysis. Individual sample variation was consistent with the interpretation that animal-to-animal variations in mRNA granules reflected the time-course of mRNA granule formation. We also used texture analysis to quantify the effect of cycloheximide, given either before or after brain ischemia, on mRNA granules. If administered before ischemia, cycloheximide inhibited mRNA granule formation, but if administered after ischemia did not prevent mRNA granulation, indicating mRNA granule formation is dependent on dissociation of polysomes. We conclude that texture analysis is an effective means for quantifying the complex morphological changes induced in neurons by brain ischemia and reperfusion.     

GM(n,h)模型建模序列数据数乘变换特性研究

基于数乘变换是灰色系统建模过程中数据处理的基础,讨论了ＧＭ（n,h）模型与其他几类灰色模型的内在联系．将各类灰色模型统一于共同的分析体系,并在此基础上研究了数乘变换对ＧＭ（n,h）模型参数取值的影响．指出了模型的模拟和预测值只与因变量的数乘变换有关,而与自变量的变换无关．最后分析了几个特殊灰色模型的数乘变换性质,该结果对研究系列灰色模型参数特征有重要意义．     

Line-by-line spectroscopic simulations on graphics processing units

We report here on software that performs line-by-line spectroscopic simulations on gases. Elaborate models (such as narrow band and correlated-K) are accurate and efficient for bands where various components are not simultaneously and significantly active. Line-by-line is probably the most accurate model in the infrared for blends of gases that contain high proportions of H₂O and CO₂ as this was the case for our prototype simulation. Our implementation on graphics processing units sustains a speedup close to 330 on computation-intensive tasks and 12 on memory intensive tasks compared to implementations on one core of high-end processors. This speedup is due to data parallelism, efficient memory access for specific patterns and some dedicated hardware operators only available in graphics processing units. It is obtained leaving most of processor resources available and it would scale linearly with the number of graphics processing units in parallel machines. Line-by-line simulation coupled with simulation of fluid dynamics was long believed to be economically intractable but our work shows that it could be done with some affordable additional resources compared to what is necessary to perform simulations on fluid dynamics alone.<h4 id="absSec_N1af24720N1e664e40">Program summaryh4>Program title: GPU4RECatalogue identifier: ADZY_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADZY_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 62&thinsp;776No. of bytes in distributed program, including test data, etc.: 1&thinsp;513&thinsp;247Distribution format: tar.gzProgramming language: C++Computer: x86 PCOperating system: Linux, Microsoft Windows. Compilation requires either gcc/g++ under Linux or Visual C++ 2003/2005 and Cygwin under Windows. It has been tested using gcc 4.1.2 under Ubuntu Linux 7.04 and using Visual C++ 2005 with Cygwin 1.5.24 under Windows XP.RAM: 1 gigabyteClassification: 21.2External routines: OpenGL (http://www.opengl.org)Nature of problem: Simulating radiative transfer on high-temperature high-pressure gases.Solution method: Line-by-line Monte-Carlo ray-tracing.Unusual features: Parallel computations are moved to the GPU.Additional comments: nVidia GeForce 7000 or ATI Radeon X1000 series graphics processing unit is required.Running time: A few minutes.     

The historical workstation project

Since 1978 research in the development of software dedicated to the specific problems of historical research has been undertaken at the Max-Planck-Institute für Geschichte in Göttingen. From a background of practical experiences during these years, a concept of what an appropriate h8q821/xxlarge8216.gif" alt="lsquo" align="BASELINE" BORDER="0">workstationh8q821/xxlarge8221.gif" alt="rdquo" align="MIDDLE" BORDER="0"> for an historian would be has been derived. It stresses the necessity of three components: (a) software, derived from a detailed analysis of what differentiates information contained in historical sources from such present in current material, (b) databases which are as easily available as printed books and (c) knowledge bases which allow software and data bases to draw upon the information contained in historical reference works. A loose network of European research projects, dedicated to the realization of such a setup, is described.Manfred Thaller has a Ph.D. (1975) in Modern and Medieval History and held a post-doctoral fellowship in sociology at the Institute for Advanced Studies (Vienna). Since 1978 he has been at the Max-Planck-Institute for History, where he is a research fellow for Historical Information Science.     

Gas phase chemical studies of superheavy elements using the Dubna gas-filled recoil separator - Stopping range determination

Currently, gas phase chemistry experiments with heaviest elements are usually performed with the gas-jet technique with the disadvantage that all reaction products are collected in a gas-filled thermalisation chamber adjacent to the target. The incorporation of a physical preseparation device between target and collection chamber opens up the perspective to perform new chemical studies. But this approach requires detailed knowledge of the stopping force (STF) of the heaviest elements in various materials. Measurements of the energy loss of mercury (Hg), radon (Rn), and nobelium (No) in Mylar and argon (Ar) were performed at low kinetic energies of around (40-270) keV per nucleon. The experimentally obtained values were compared with STF calculations of the commonly used program for calculating stopping and ranges of ions in matter (SRIM). Using the obtained data points an extrapolation of the STF up to element 114, eka-lead, in the same stopping media was carried out. These estimations were applied to design and to perform a first chemical experiment with a superheavy element behind a physical preseparator using the nuclear fusion reaction ²⁴⁴Pu(⁴⁸Ca; 3n)²⁸⁹114. One decay chain assigned to an atom of ²⁸⁵112, the α-decay product of ²⁸⁹114, was observed.     

A thin-layer reference material for hydrogen analysis

In many areas of material sciences, hydrogen analysis is of particular importance. For example, hydrogen is most abundant as impurity in thin film materials - depending on the deposition process - and has great influence on the chemical, physical and electrical properties of many materials. Existing bulk reference materials (RMs) are not suited for surface sensitive analytical methods like elastic recoil detection analysis (ERDA) or nuclear reaction analysis (NRA). To overcome this serious lack of (certified) thin-layer reference materials for the determination of hydrogen in the near-surface region (1-2 μm depth), we produced stable, homogeneous amorphous silicon layers on Si-wafers (aSi:H-Si) by means of chemical vapour deposition (CVD), while about 10% of hydrogen was incorporated in the Si-layer. Homogeneity and stability were proved by NRA whereas traceability of reference values has been assured by an international interlaboratory comparison.     

Monte Carlo simulation study of the positron contribution to displacements per atom production in YBCO superconductors

The contribution from positrons to the displacements per atom (dpa) distribution induced by the gamma irradiation on YBCO superconducting slabs is presented. The procedure implemented previously by the authors was adapted to take into account the contribution from positrons to dpa induced by the gamma radiation. The results show that, when positrons are considered in the atom displacement process, the total dpa almost doubles at 10 MeV of incident gamma radiation. At that energy positrons contribute 7% more to the total dpa than electrons, although electrons maintain having the highest contribution up to about 8 MeV.     

Selection of water-dispersible carbon black for fabrication of uranium oxicarbide microspheres

Fabrication of uranium oxicarbide microspheres, a component of TRISO fuel particles for high temperature nuclear power systems, is based on the internal gelation of uranium salts in the presence of carbon black. In order to obtain a high quality product, carbon black should remain dispersed during all phases of the gelation process. In this study, the surface and structural properties of several commercial carbon black materials, and the use of dispersing agents was examined with the goal of finding optimal conditions for stabilizing submicron-sized carbon black dispersions. Traditional methods for stabilizing dispersions, based on the use of dispersing agents, failed to stabilize carbon dispersions against large pH variations, typical for the internal gelation process. An alternate dispersing method was proposed, based on using surface-modified carbons functionalized with strongly ionized surface groups (sodium sulfonate). With a proper choice of surface modifiers, these advanced carbons disperse easily to particles in the range of 0.15-0.20 μm and the dispersions remain stable during the conditions of internal gelation.     

一个2000t／h破碎系统简介

说明了目前国内破碎站的现状，介绍了2000t／h破碎系统的结构，包含粗碎破碎站及细碎破碎机的工作原理、构成及在现场使用的情况。