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The 12C(γ,pn) and 12C(γ,pp) reactions have been studied using tagged photons of energy Eγ = 150–400 MeV. Recoil momentum distributions are compared to the results of Monte Carlo calculations based on a two-nucleon photon absorption model and two different phase space models. The 12C(γ,pn) data at low missing energy are consistent with absorption on 1p2 and 1s1p nucleon pairs.  相似文献   
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The effect of simultaneous substitution of a fluctuating cation and a divalent cation in LaMnO3 perovskite modifies the properties of the material to exhibit large valence colossal magnetoresistance (CMR) effect. A good example of these properties is (La1−2x Pr x Ca x )MnO3 (LPCMO) type CMR material. In this communication it is reported that, with the increase in x (for x=0.1, 0.15, 0.2), the T c varies between 100 and 120 K with improvisation in metal-insulator transition. Interestingly, resistance increases with x from few hundred ohms to few kilo ohms with corresponding decrease in the unit cell volume. The results of the studies using X-ray diffraction (XRD), electrical resistivity, magnetoresistance and ac susceptibility measurements on LPCMO samples for understanding the structural, transport and magnetic properties are discussed in detail.  相似文献   
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In this paper, the optimal design and analysis of evacuation routes in transportation networks is examined. An methodology for optimal egress route assignment is suggested. An integer programming (IP) formulation for optimal route assignment is presented, which utilizes M/G/c/c state dependent queueing models to cope with congestion and time delays on road links. M/G/c/c simulation software is used to evaluate performance measures of the evacuation plan: clearance time, total travelled distance and blocking probabilities. Extensive experimental results are included.  相似文献   
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This paper introduces a theoretical framework that describes the importance of affect in guiding judgments and decisions. As used here, “affect” means the specific quality of “goodness” or “badness” (i) experienced as a feeling state (with or without consciousness) and (ii) demarcating a positive or negative quality of a stimulus. Affective responses occur rapidly and automatically—note how quickly you sense the feelings associated with the stimulus word “treasure” or the word “hate”. We argue that reliance on such feelings can be characterized as “the affect heuristic”. In this paper we trace the development of the affect heuristic across a variety of research paths followed by ourselves and many others. We also discuss some of the important practical implications resulting from ways that this heuristic impacts our daily lives.  相似文献   
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This paper considers the problem of finding minimal length tree networks on the unit sphere of a given point set (V) where distance is measured along great circular arcs. The related problems of finding a Steiner Minimal TreeSMT(V) and of finding a Minimum Spanning TreeMST(V) are treated through a simplicial decomposition technique based on computing the Delaunay TriangulationDT(V) and the Voronoi DiagramVD(V) of the given point set.O(N logN) algorithms for computingDT(V),VD(V), andMST(V) as well as anO(N logN) heuristic for finding a sub-optimalSMT(V) solution are presented, together with experimental results for randomly distributed points on .  相似文献   
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