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1.
Noam Nisan 《Computational Complexity》1994,4(1):1-11
We show that any randomized logspace algorithm (running in polynomial time with bounded two-sided error) can be simulated deterministically in polynomial time andO(log2
n) space. This puts RL in SC, Steve's Class In particular, we get a polynomial time,O(log2
n) space algorithm for thest-connectivity problem on undirected graphs.Subject classifications. 68Q10, 68Q15, 68Q25. 相似文献
2.
Competitive analysis of incentive compatible on-line auctions 总被引:4,自引:0,他引:4
This paper studies auctions in a setting where the different bidders arrive at different times and the auction mechanism is required to make decisions about each bid as it is received. Such settings occur in computerized auctions of computational resources as well as in other settings. We call such auctions, on-line auctions.
We first characterize exactly on-line auctions that are incentive compatible, i.e. where rational bidders are always motivated to bid their true valuation. We then embark on a competitive worst-case analysis of incentive compatible on-line auctions. We obtain several results, the cleanest of which is an incentive compatible on-line auction for a large number of identical items. This auction has an optimal competitive ratio, both in terms of seller's revenue and in terms of the total social efficiency obtained. 相似文献
3.
S Knutton I Rosenshine MJ Pallen I Nisan BC Neves C Bain C Wolff G Dougan G Frankel 《Canadian Metallurgical Quarterly》1998,17(8):2166-2176
Enteropathogenic Escherichia coli (EPEC), like many bacterial pathogens, employ a type III secretion system to deliver effector proteins across the bacterial cell. In EPEC, four proteins are known to be exported by a type III secretion system_EspA, EspB and EspD required for subversion of host cell signal transduction pathways and a translocated intimin receptor (Tir) protein (formerly Hp90) which is tyrosine-phosphorylated following transfer to the host cell to become a receptor for intimin-mediated intimate attachment and 'attaching and effacing' (A/E) lesion formation. The structural basis for protein translocation has yet to be fully elucidated for any type III secretion system. Here, we describe a novel EspA-containing filamentous organelle that is present on the bacterial surface during the early stage of A/E lesion formation, forms a physical bridge between the bacterium and the infected eukaryotic cell surface and is required for the translocation of EspB into infected epithelial cells. 相似文献
4.
The effects of operating parameters such astransmembrane pressure, retentate, and recirculation volumetric flow rates on the productivity of an ultrafiltration membrane were studied using field data and development of a management model. Correlation equations for predicting the volumetric permeate flow rates were derived from general membrane blocking laws and experimental data. The experimental data were obtained from a pilot study carried out in the Arad wastewater treatment system (a pilot plant operating in feed and bleed operation mode) located several kilometers west of the City of Arad, Israel. Correlation predictions were confirmed with the independent experimental results. The results enabled us to develop a mathematical expression accurately describing the decline in flux due to fouling. 相似文献
5.
S. J. Piet L. Di Pace G. Federici D. F. Holland K. A. McCarthy S. Nisan Y. Oda Y. Seki L. N. Topilski 《Journal of Fusion Energy》1997,16(1-2):11-17
We describe the radioactive sources in the International Thermonuclear Experimental Reactor (ITER). The most important sources are co-deposited tritium, tritiated water, tokamak dust, and corrosion products. The co-deposited tritium is limited to 1 kg-T; the total on-site tritium inventory in the Basic Performance Phase (BPP) is 4 kg-T. Tritiated water concentrations are kept below 0.2 g-T/m3 in the divertor; other coolant loops have lower tritium concentrations. The in-vessel dust inventory is up to 100 kg-W, 100 kg-Be, and 200 kg-C. The activated corrosion product inventory is kept below 10 kg per loop. 相似文献
6.
We show thatBPP can be simulated in subexponential time for infinitely many input lengths unless exponential time
We also show thatBPP is contained in subexponential time unless exponential time has publishable proofs for infinitely many input lengths. In addition, we showBPP can be simulated in subexponential time for infinitely many input lengths unless there exist unary languages inMA-P. 相似文献
| collapses to the second level of the polynomial-time hierarchy. |
| has polynomial-size circuits and |
| has publishable proofs (EXPTIME=MA). |
7.
S. Nisan G. Caruso J. -R. Humphries G. Mini A. Naviglio B. Bielak O. Asuar Alonso N. Martins L. Volpi 《Nuclear Engineering and Design》2003,221(1-3):251
This paper summarises our recent investigations undertaken as part of the EURODESAL project on nuclear desalination, currently being carried out by a consortium of four European, and one Canadian, industrials and two leading EU R&D organisations.Major achievements of the project, as discussed in this paper are:
- • Coherent demonstration of the technical feasibility of nuclear desalination through the elaboration of coupling schemes for optimum cogeneration of electricity and water and by exploring the unique capabilities of the innovative nuclear reactors and desalination technologies.
- • Verification that the integrated system design does not adversely affect nuclear reactor safety.
- • Development of codes and methods for an objective economic assessment of the competitiveness and sustainability of proposed options through comparison, in European conditions, with fossil energy based systems.
8.
Gave 111 children aged 6, 7, 8, and 9 yrs old a choice between an immediate reward and a larger, delayed reward. Half of the Ss in each age group saw the rewards before choosing, while the other half did not. Exposure to the rewards led to more choices of delayed reward for 7 yr olds. The 6 yr olds predominantly chose immediate rewards regardless of exposure, while the 8 and 9 yr olds predominantly chose the delayed reward regardless of exposure. 2 explanations are offered for the results for the 7 yr olds. In one, the results are attributed to the effect of exposure on value and/or expectancy of the delayed reward. In the other, it is suggested that exposure orients attention to the value, rather than the immediacy, of the alternatives. In this view, delay of gratification in young children reflects a form of decentration. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
Lower bounds on arithmetic circuits via partial derivatives 总被引:1,自引:1,他引:0
In this paper we describe a new technique for obtaining lower bounds on restricted classes of non-monotone arithmetic circuits. The heart of this technique is a complexity measure for multivariate polynomials, based on the linear span of their partial derivatives. We use the technique to obtain new lower bounds for computing symmetric polynomials (that hold over fields of characteristic zero) and iterated matrix products (that hold for all fields).Dedicated to the memory of Roman Smolensky 相似文献
10.
60 boys and 60 girls in the 1st and 4th grades in Israel were interviewed to examine the distinction between moral and conventional norms. Ss were equally divided between 3 groups: secular urban Jews, secular kibbutz Jews, and traditional Arab villagers. Ss were presented with 8 behaviors, all breaches of moral or conventional norms. Two of them dealt with norms strongly observed by the traditional but not by the other groups and 2 with norms central to the kibbutz. Ss were asked the extent to which the behavior was bad (or good) in a country where (a) it was prohibited and (b) it was permitted. They were also asked whether it should be forbidden by law, and why. City and kibbutz Ss did not differ in their judgments, even in regard to behaviors emphasized in the kibbutz. Compared with these groups, the traditional group judged all behaviors as bad even when permitted; they thought all should be prohibited by law and their justifications tended to be in normative terms. Results are interpreted in terms of 2 distinct orientations to social norms: one where the criteria for social judgment of behaviors and norms are consequences to others and law, and the other where social norms are considered to have absolute validity and constitute the dominant criterion for moral judgment. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献