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71.
The basic algorithms involved in reason maintenance in the standard ATMS is known to have a computational complexity that is exponential in the worst case. Yet, also in average-case problem solving, the ATMS often lays claim to a major part of the computational effort spent by a problem solver/ATMS system. In this paper, we argue that within the limits of the worst-case computational complexity, it is possible to improve on the average-case complexity of reason maintenance and query processing by eliminating computation that is of no relevance to the problem solver's performance. To this purpose, we present a set of algorithms designed to control the effort spent by the ATMS on label updating. The basic idea underlying these algorithms is that of lazy evaluation: labels are not automatically maintained on all datums but are computed only when needed (either directly or indirectly) by the problem solver. The algorithms have been implemented in the LazyRMS with which we have experimented in the context of model-based diagnosis; our experiments show a substantial saving in the computational effort spent on reason maintenance.  相似文献   
72.
Abstract: A system for the generation of naval flying programmes is described. The task is typical of some resource allocation problems, and comprises both the allocation of airborne resources to naval activities whilst taking into account a number of constraints, and the re-allocation of these resources when circumstances change whilst retaining as much of the original plan as possible. Techniques for constraint-based reasoning and assumption-based reasoning are combined to solve the task. An algorithm is described, based around an Assumption-Based Truth Maintenance System (ATMS), that is able to generate an initial allocation, determine the knock-on effects of changing requirements or resources, to retain those parts of the plan that were unaffected, and to re-allocate those parts that were affected. An interactive graphical interface has been designed that allows the user and the system to cooperate in the creation of flying programmes that meet the constraints and fit the situation at hand.  相似文献   
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CD-1 mice received daily subcutaneous injections of either cocaine (20 mg/kg or 40 mg/kg) or saline solution (0.9% NaCl) from postnatal days 2 to 15. Pups were tested on days 16-17 for learning and 24-h retention of a passive avoidance task, where entering a dark compartment was punished with a mild foot shock. Locomotor activity and general behaviour in an open field arena were assessed on day 21, following administration of either the muscarinic blocker scopolamine (0.8 mg/kg) or saline solution. In addition, immunostaining for the enzyme choline acetyltransferase (ChAT) was measured in different basal forebrain areas (medial septum, striatum, and nucleus basalis) on day 30. Cocaine treatment failed to affect either learning or retention capabilities. Nonetheless, neophobic behaviour during the learning session was enhanced in control nonpunished mice exposed to the 20-mg/kg dose. In the open field test, although baseline activity levels were unaffected by cocaine exposure, the 40-mg/kg cocaine-treated pups showed decreased sensitivity to the hyperkinetic effects of scopolamine. ChAT immunocytochemistry revealed a significant reduction of the number of ChAT-immunopositive neurons in the nucleus basalis but not in the other cholinergic basal forebrain regions.  相似文献   
75.
Considering the structural similarity between gabexate mesylate (FOY), a drug for serine proteinase-mediated diseases, and L-arginine, the effect of gabexate mesylate on the nitric oxide (NO) pathway has been investigated. Gabexate mesylate inhibits competitively constitutive and inducible NO synthase (cNOS and iNOS, respectively), with Ki values of 1.0 x 10(-4) M and 5.0 x 10(-3) M, respectively, at pH 7.4 and 37.0 degrees C. However, gabexate mesylate is not an NO precursor. Moreover, like other NOS inhibitors, gabexate mesylate increases iNOS mRNA expression in rat C6 glioma cells, as induced by E. coli lipopolysaccharide plus interferon-gamma. Finally, gabexate mesylate inhibits dose-dependently nitrite production (i.e. NO release) in rat C6 glioma cells, as induced by E. coli lipopolysaccharide plus interferon-gamma. Thus, this drug should be administered under careful control, since enzyme inhibition may occur also in vivo.  相似文献   
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There are two major elements of a General World Administrative Radio Conference such as WARC-79. One is to review and revise allocations of radio frequencies to functional services such as fixed, mobile, satellite, and radionavigation. The other major element is the detailed radio regulations concerning use of these allocations by member Administrations. These regulations combine technical, economic, geopolitical, and other considerations into a framework which attempts to satisfy the perceived requirements of all Administrations. This aspect of WARC79 is the subject of this paper. As will be seen, some substantial changes in regulations were made at the Conference, especially those concerning HF assignments and use. Other changes are implicit in the Resolutions for future conferences which were adopted at WARC-79. The key to success in framing effective and acceptable allocations, and regulations, is cooperation. In this respect, WARC-79 was not much different from preceding conferences, despite contrary misgivings.  相似文献   
79.
Although research has demonstrated the efficacy of psychological services for ameliorating physical conditions, consumers are often uninformed of the advantages of integrated health care. To begin to address this knowledge gap, the authors developed, offered, and assessed a 2-hr community outreach program, which included lectures highlighting the benefits of providing psychological services within general health care, a demonstration of stress-reduction techniques, and first-person accounts of the benefits of psychological health care. The preliminary results of the evaluation were positive. It is recommended that similar programs be disseminated in diverse communities. Suggestions for planning and conducting these types of programs are offered. Furthermore, strategies for improving the goals and content of workshops are offered, with a focus on the distinction between promotion of attitudinal change versus practical activism. Finally, implications for community outreach that is intended to inform the public of the value of psychological health care services are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
80.
Interpreting top-down mass spectra using spectral alignment   总被引:1,自引:0,他引:1  
Recent advances in mass spectrometry instrumentation, such as FTICR and OrbiTrap, have made it possible to generate high-resolution spectra of entire proteins. While these methods offer new opportunities for performing "top-down" studies of proteins, the computational tools for analyzing top-down data are still scarce. In this paper we investigate the application of spectral alignment to the problem of identifying protein forms in top-down mass spectra (i.e., identifying the modifications, mutations, insertions, and deletions). We demonstrate how spectral alignment efficiently discovers protein forms even in the presence of numerous modifications and how the algorithm can be extended to discover positional isomers from spectra of mixtures of isobaric protein forms.  相似文献   
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