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31.
We describe the apparatus used in experiment UA4 to study proton-antiproton elastic and inelastic interactions at the CERN SPS Collider. Elastically scattered particles, travelling at very small angles, are observed by detectors placed inside movable sections (“Roman pots”) of the SPS vacuum chamber. The deflection in the field of the machine quadrupoles allow the measurement of the particle momentum. Inelastic interactions are observed by a left-right symmetric system of trigger counter hodoscopes and drift-chamber telescopes. The apparatus reconstructs the interaction vertex and measures the pseudorapidity η of charged particles in the range 2.5 < 6η6 < 5.6.  相似文献   
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Laser processing of materials   总被引:1,自引:0,他引:1  
J. Dutta Majumdar  I. Manna 《Sadhana》2003,28(3-4):495-562
Light amplification by stimulated emission of radiation (laser) is a coherent and monochromatic beam of electromagnetic radiation that can propagate in a straight line with negligible divergence and occur in a wide range of wave-length, energy/power and beam-modes/configurations. As a result, lasers find wide applications in the mundane to the most sophisticated devices, in commercial to purely scientific purposes, and in life-saving as well as life-threatening causes. In the present contribution, we provide an overview of the application of lasers for material processing. The processes covered are broadly divided into four major categories; namely, laser-assisted forming, joining, machining and surface engineering. Apart from briefly introducing the fundamentals of these operations, we present an updated review of the relevant literature to highlight the recent advances and open questions. We begin our discussion with the general applications of lasers, fundamentals of laser-matter interaction and classification of laser material processing. A major part of the discussion focuses on laser surface engineering that has attracted a good deal of attention from the scientific community for its technological significance and scientific challenges. In this regard, a special mention is made about laser surface vitrification or amorphization that remains a very attractive but unaccomplished proposition. References in this paper have not been cited or prepared in journal format  相似文献   
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The diagnostic usefulness of measuring plasma D-dimers using the ELISA method and the latex agglutination test has been prospectively evaluated in 117 patients hospitalized for suspicion of acute venous thrombo-embolism (AVTE): pulmonary embolism was suspected in 80 patients and the remaining 37 had a suspicion of deep vein thrombosis of the lower limbs. The diagnosis of AVTE was confirmed in 50% of the patients, all of whom underwent gold standard invasive investigation i.e. pulmonary angiography and/or contrast venography. The sensitivity, specificity, negative predictive value and positive predictive value of a D-dimers plasma concentration exceeding 500 ng/ml for the diagnosis of AVTE were respectively 98, 58, 97 and 70% when using the ELISA method, and 86, 71, 84 and 75% when using the latex assay. In 47 patients whose lung scans yielded abnormalities of indeterminate probability of pulmonary embolism, the sensitivity of the ELISA method was very high (94%), but that of latex assay was low (67%). Our results demonstrate that measuring the plasma D-dimers by the latex assay should not be used in the diagnosis of AVTE. On the other hand, the ELISA method might be of great interest in the diagnostic strategy of AVTE, as a normal concentration of D-dimers rules out almost definitely the diagnosis of AVTE, and hence, spares from performing invasive investigations.  相似文献   
36.
In this Review, we describe the synthesis of high-quality colloidal nanoparticles in organic solvents, the mechanisms by which they can be transferred into aqueous solution, and some of their applications in biology. In particular, we will place emphasis on the creation of multifunctional nanoparticles or nanoparticle assemblies.  相似文献   
37.
The deductive approach is a formal program construction method in which the derivation of a program from a given specification is regarded as a theorem-proving task. To construct a program whose output satisfies the conditions of the specification, we prove a theorem stating the existence of such an output. The proof is restricted to be sufficiently constructive so that a program computing the desired output can be extracted directly from the proof. The program we obtain is applicative and may consist of several mutually recursive procedures. The proof constitutes a demonstration of the correctness of this program.To exhibit the full power of the deductive approach, we apply it to a nontrivial example—the synthesis of a unification algorithm. Unification is the process of finding a common instance of two expressions. Algorithms to perform unification have been central to many theorem-proving systems and to some programming-language processors.The task of deriving a unification algorithm automatically is beyond the power of existing program synthesis systems. In this paper,we use the deductive approach to derive an algorithm from a simple, high-level specification of the unification task. We will identify some of the capabilities required of a theorem-proving system to perform this derivation automatically.  相似文献   
38.
Cadmium (Cd), a highly toxic environmental pollutant, induces hepatic disorders. The present study has been undertaken to investigate the protective role of the fruit extract of Terminalia arjuna (AE) against Cd-induced oxidative liver impairment using a murine model. Cadmium reduced hepatocytes viability, activated MAPKs, disturbed Bcl-2 family protein balance, increased reactive oxygen species (ROS) production and induced apoptotic cell death by mitochondria dependent caspases-3 activation. AE treatment, however, suppressed all the apoptotic actions of cadmium. Similarly, mice treated with cadmium altered a number biomarkers related to hepatic oxidative stress and other apoptotic indices. Oral administration of AE both pre and post prevented all the Cd-induced hepatic damages.  相似文献   
39.
An evolutionary procedure based on cultural algorithms for the optimal design of adaptive wavelet filters based on lifting scheme is proposed. Numerical results of characterization, based on statistical experiment design, as well as validation, based on the comparison with a genetic optimization algorithm, are presented. Experimental results of the validation on two case studies for reducing uncertainty arising from noise in on-field corrosion rate measurements are highlighted.  相似文献   
40.
Abrasive flow machining (AFM) is gaining widespread application finishing process on difficult to reach surfaces in aviation, automobile, and tooling industry. Al/SiCp-MMC is a promising material in these industries. Here, AFM has been used to finish conventionally machined cylindrical surface of Al/15 wt% SiCp-MMC workpiece. This paper presents the utilization of robust design-based Taguchi method for optimization of AFM parameters. The influences of AFM process parameters on surface finish and material removal have been analyzed. Taguchi experimental design concept, L18 (61?×?37) mixed orthogonal array is used to determine the S/N ratio and optimize the AFM process parameters. Analysis of variance and F test values also indicates the significant AFM parameters affecting the finishing performance. The mathematical models for R a, R t, ΔR a, and ΔR t and material removal are established to investigate the influence of AFM parameters. Conformation test results verify the effectiveness of these models and optimal parametric combination within the considered range. Scanning electron micrographs testifies the effectiveness of AFM process in fine finishing of Al/15 wt% SiCp-MMC.  相似文献   
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