Analysis of explosives by nuclear magnetic resonance spectrometry

In order to evaluate the applicability of NMR to the analysis of explosives, the method was used to analyse explosives from actual cases. The results were then compared with results from other analytical methods, mainly TLC and GC/MS. For unexploded samples NMR was found to be a simple, fast and reliable method, often allowing the identification of mixtures without pre-separation. Some post-explosion samples were also successfully analysed by NMR. Although sensitivity problems still exist, NMR showed a surprisingly promising prospects for the difficult field of post-explosion analysis.     

The effect of microwave heating on the microstructure and the mechanical properties of reaction-bonded boron carbide

Reaction-bonded boron carbide composites were fabricated by both microwave (under Ar/10% H₂) and conventional heating (under vacuum or Ar/10% H₂). Silicon carbide (SiC) formation occurred in all cases and was slightly favored in the case of microwave heating under Ar/H₂. The resulting microstructures were influenced by the heating process and atmosphere; the SiC existed in the form of needles with conventional heating under vacuum. SiC small polygonal grains were present after microwave heating under Ar/H₂. Both the atmosphere and the electromagnetic field influence the SiC morphology. Despite this difference, the hardness and toughness of composites obtained by both heating techniques were similar.     

Post explosion analysis of explosives by mass spectrometric methods

The Analysis of trace amounts of explosives from post-explosion debris–one of the most difficult problems in forensic chemistry-is still carried out in many laboratories by chromatographic methods only. In recent years several new methods have been applied to the analysis of explosives. These include mass spectrometric methods (GC/MS, LC/MS and MS/MS) and NMR methods. The possible application of these methods to post-explosion analysis is discussed and various aspects of the techniques are reviewed and compared. The choice of capillary column GC/MS as a routine method in the Israel Police laboratory is explained and examples from actual cases are given.     

Capillary column gas chromatography/mass spectrometry of explosives

Gas chromatography/mass spectrometry (GC/MS) using a 15 m long capillary column has been employed in our laboratory for the analysis of explosives. The technique is suitable for most of the common military explosives. Nitroaromatic compounds like TNT were analysed easily and with high sensitivity and so were the volatile nitrate esters like glycerine trinitrate. Success was also achieved in the analysis of PETN and RDX, which had previously been reported to pose problems under GC conditions. Tetryl was shown to decompose during the analysis but its decomposition product was well defined and could serve as evidence to the presence of tetryl. The method was successfully applied to post-explosion debris from actual cases.     

An equilibrium pricing model for weather derivatives in a multi-commodity setting

Many industries are exposed to weather risk. Weather derivatives can play a key role in hedging and diversifying such risk because the uncertainty in a company's profit function can be correlated to weather condition which affects diverse industry sectors differently. Unfortunately the weather derivatives market is a classical example of an incomplete market that is not amenable to standard methodologies used for derivative pricing in complete markets. In this paper, we develop an equilibrium pricing model for weather derivatives in a multi-commodity setting. The model is constructed in the context of a stylized economy where agents optimize their hedging portfolios which include weather derivatives that are issued in a fixed quantity by a financial underwriter. The supply and demand resulting from hedging activities and the supply by the underwriter are combined in an equilibrium pricing model under the assumption that all agents maximize some risk averse utility function. We analyze the gains due to the inclusion of weather derivatives in hedging portfolios and examine the components of that gain attributable to hedging and to risk sharing.     

The effect of filmed versus personal after-event reviews on task performance: The mediating and moderating role of self-efficacy.

In the current study, we compared the effect of personal and filmed after-event reviews (AERs) on performance, and the role that self-efficacy plays in moderating and mediating the effects of these 2 types of AER on performance. The setting was one in which 49 men and 63 women participated twice in a simulated business decision-making task. In between, participants received a personal AER, watched a filmed AER, or had a break. We found that individuals who participated in an AER, whether personal or filmed, improved their performance significantly more than those who did not participate in a review. Furthermore, there was no significant difference in performance improvement between the personal and the filmed AER, which suggests that the 2 are quite similar in their effect. We also found that the differences in performance improvement between the personal AER group and the control group were somewhat greater than those found in the filmed AER group. Self-efficacy mediated the effect of AER on performance improvement in both types of AER. In addition, the effect of AER on performance improvement was moderated by initial self-efficacy in the personal but not in the filmed AER: The personal AER was more effective, the higher the initial self-efficacy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attenuation of the Photobaric-Photoacoustic Signal in Leaves by Oxygen-Consuming Processes

Charland et al. (Biochim. Biophys. Acta 1992 , 1098, 261–265) obtained photoacoustic data from sugar maple tree leaves, in which the photobaric part of the photoacoustic signal declined in time following a transition from high light to low light level, which they interpreted as indicating stromal and plasmal oxygen-consuming processes. Here, a simple mathematical model of oxygen diffusion, which includes a continuous distribution of oxygen-consuming sinks in the diffusion path from the photosynthetic membrane to the inner air phase, is presented. The model explains the main features of the dependence of the steady-state signal on the modulation frequency and the light intensity, although the numerical agreement between the data and the results of the model is only semi-quantitative, which is discussed. It turns out that at sufficiently high light intensity, or at a short time after a previous exposure to a high light level, the effect of oxygen consumption tends to zero because a high stromal oxygen concentration is built up which is saturating for the uptake process. Within this limitation, the merit of the photoacoustic signal as an indicator for photosynthetic oxygen evolution is preserved, answering recent doubts.     

四基色投影显示

我们采用多芯片HTPS屏结构,已开发出一种四基色前投式投影样机。这种投影机建立在对一种现行高端品牌产品的光学平台进行改进的基础之上。在KESHETTM芯片中,用ColorPeakTM算法,把标准720p输入信号转换成所需要的多基色输入信号,结果使色域和亮度都有了显著的提高。     

How to Implement a Safe Real-Time System:The OBSERV Implementation of the Production Cell Case Study

The Production Cell example was chosen by FZI (the Computer Science Research Center), in Karlsruhe. to examine the benefits of formal methods for industrial applications. This example was implemented in more than 30 formalisms. This paper describes the implementation of the Production Cell in OBSERV. The OBSERV methodology for software development is based on rapid construction of an executable specification, or prototype, of a system, which may be examined and modified repeatedly to achieve the desired functionality. The objectives of OBSERV also include facilitating a smooth transition to a target system, and providing means for reusing specification, design, and code of systems, particularly real-time reactive systems. In this paper we show how the methods used in the OBSERV implementation address the requirements imposed by reactive systems. We describe the OBSERV implementation of the Production cell, explain design decisions, with special emphasis on reusability and safety issues. We demonstrate how to take care of safety and liveness properties required for this example. These properties are checked by means of simulation and formally proved with a model checker.     

On the performance of Dijkstra’s third self-stabilizing algorithm for mutual exclusion and related algorithms

In Dijkstra (Commun ACM 17(11):643–644, 1974) introduced the notion of self-stabilizing algorithms and presented three such algorithms for the problem of mutual exclusion on a ring of n processors. The third algorithm is the most interesting of these three but is rather non intuitive. In Dijkstra (Distrib Comput 1:5–6, 1986) a proof of its correctness was presented, but the question of determining its worst case complexity—that is, providing an upper bound on the number of moves of this algorithm until it stabilizes—remained open. In this paper we solve this question and prove an upper bound of 3\frac1318 n² + O(n){3\frac{13}{18} n^2 + O(n)} for the complexity of this algorithm. We also show a lower bound of 1\frac56 n² - O(n){1\frac{5}{6} n^2 - O(n)} for the worst case complexity. For computing the upper bound, we use two techniques: potential functions and amortized analysis. We also present a new-three state self-stabilizing algorithm for mutual exclusion and show a tight bound of \frac56 n² + O(n){\frac{5}{6} n^2 + O(n)} for the worst case complexity of this algorithm. In Beauquier and Debas (Proceedings of the second workshop on self-stabilizing systems, pp 17.1–17.13, 1995) presented a similar three-state algorithm, with an upper bound of 5\frac34n²+O(n){5\frac{3}{4}n^2+O(n)} and a lower bound of \frac18n²-O(n){\frac{1}{8}n^2-O(n)} for its stabilization time. For this algorithm we prove an upper bound of 1\frac12n² + O(n){1\frac{1}{2}n^2 + O(n)} and show a lower bound of n ²−O(n). As far as the worst case performance is considered, the algorithm in Beauquier and Debas (Proceedings of the second workshop on self-stabilizing systems, pp 17.1–17.13, 1995) is better than the one in Dijkstra (Commun ACM 17(11):643–644, 1974) and our algorithm is better than both.