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排序方式: 共有460条查询结果,搜索用时 15 毫秒
91.
Edith Hemaspaandra Lane A. Hemaspaandra Jörg Rothe 《Autonomous Agents and Multi-Agent Systems》2017,31(5):1055-1076
Previous work on voter control, which refers to situations where a chair seeks to change the outcome of an election by deleting, adding, or partitioning voters, takes for granted that the chair knows all the voters’ preferences and that all votes are cast simultaneously. However, elections are often held sequentially and the chair thus knows only the previously cast votes and not the future ones, yet needs to decide instantaneously which control action to take. We introduce a framework that models online voter control in sequential elections. We show that the related problems can be much harder than in the standard (non-online) case: For certain election systems, even with efficient winner problems, online control by deleting, adding, or partitioning voters is \(\mathrm {PSPACE}\)-complete, even if there are only two candidates. In addition, we obtain (by a new characterization of coNP in terms of weight-bounded alternating Turing machines) completeness for \({\mathrm {coNP}}\) in the deleting/adding cases with a bounded deletion/addition limit, and we obtain completeness for \({\mathrm {NP}}\) in the partition cases with an additional restriction. We also show that for plurality, online control by deleting or adding voters is in \({\mathrm {P}}\), and for partitioning voters is \({\mathrm {coNP}}\)-hard. 相似文献
92.
Thomas A. Foglia Edith J. Conkerton Philip E. Sonnet 《Journal of the American Oil Chemists' Society》1995,72(11):1275-1279
A modified procedure for the regiospecific analysis of triacylglycerols (TAG) with a 1,3-specific lipase is described. After
partial lipase hydrolysis of the triacylglycerol, the released free fatty acids (FFA) and 1,2(2,3)-diacylglycerols (DAG) were
isolated by thin-layer chromatography (TLC) and converted to fatty acid methyl esters (FAME). The FAME were analyzed by gas-liquid
chromatography (GLC). The 1,3-specific lipases used in this study included supported preparations from strains ofMucor miehei andRhizopus oryzae. The method also was applied to the regiospecific analyses of tung nut and Chinese melon seed oil triacyglycerols, both of
which contain high proportions of α-elaeostearic acid. The TAG composition of the oils was substantiated in parallel analysis
of the oils by highperformance liquid chromatography with chemical ionization mass spectrometric detection of intact TAG. 相似文献
93.
Wilmanns Matthias; Schlagenhauf Edith; Fol Bruno; Jansonius Johan N 《Protein engineering, design & selection : PEDS》1990,3(3):173-180
The recombinant synthase domain of the bifunctional enzyme N-(5'-phosphoribosyl)anthranilateisomerase:indole-3-glycerol-phosphate synthase from Escherichiacoli has been crystallized, and the structure has been solvedat 4 Å resolution. Two closely related crystal forms grownfrom ammonium sulphate diffract to 2 Å resolution. Oneform (space group R32, a = 163 Å, = 29.5°) containsthe unliganded synthase domain; the second crystal form (spacegroup P6322, a = 144 Å, c = 158 Å) is co-crystallizedwith the substrate analogue N-(5'-phosphoribit-1-yl)anthranilate.The structure of the synthaseinhibitor complex has beensolved by the molecular replacement method. This achievementrepresents the first successful use of a (ß)g-barrelmonomer as a trial model. The recombinant synthase domain associatesas a trimer in the crystal, the molecules being related by apseudo-crystallographic triad. The interface contacts betweenthe three domains are mediated by those residues that are alsoinvolved in the domain interface of the bifunctional enzyme.This system provides a model for an interface which is usedin both intermolecular and intramolecular domain contacts. 相似文献
94.
95.
The shield that never was: Societies with single-peaked preferences are more open to manipulation and control 总被引:1,自引:0,他引:1
Much work has been devoted, during the past 20 years, to using complexity to protect elections from manipulation and control. Many “complexity shield” results have been obtained—results showing that the attacker’s task can be made NP-hard. Recently there has been much focus on whether such worst-case hardness protections can be bypassed by frequently correct heuristics or by approximations. This paper takes a very different approach: We argue that when electorates follow the canonical political science model of societal preferences the complexity shield never existed in the first place. In particular, we show that for electorates having single-peaked preferences, many existing NP-hardness results on manipulation and control evaporate. 相似文献
96.
97.
Brand Serge; Gerber Markus; Pühse Uwe; Holsboer-Trachsler Edith 《Canadian Metallurgical Quarterly》2010,17(2):114
A cognitive mediation model was examined to find out how stress, depression, and hypomania precipitate the occurrence of dysfunctional sleep-related cognitions, which in turn lead to insomnia. A total of 862 participants (639 women, 223 men; M age: 24.67 years, SD = 5.91) completed a series of self-report questionnaires assessing perceived stress, depression, hypomania, dysfunctional sleep-related cognitions, and insomnia. Compared to men, women reported higher levels of stress, depression, and insomnia. Women also suffered from more dysfunctional sleep-related cognitions. All variables were intercorrelated. Structural equation analyses showed that the relationship between stress and insomnia was largely mediated by dysfunctional sleep-related cognitions. Links between depression and insomnia were found to be weak when controlled for stress and dysfunctional sleep-related cognitions. The findings support a cognitive model of insomnia. Stress must be seen as a precipitating factor in the onset and maintenance of insomnia. Consequently, competencies to deal with dysfunctional sleep-related cognitions should be fostered in stress management programs. In turn, stress management should be a primary focus in the treatment of insomnia. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
98.
Fama Rosemary; Sullivan Edith V.; Shear Paula K.; Cahn-Weiner Deborah A.; Marsh Laura; Lim Kelvin O.; Yesavage Jerome A.; Tinklenberg Jared R.; Pfefferbaum Adolf 《Canadian Metallurgical Quarterly》2000,14(1):29
This study examined the relationships between regional brain volumes and semantic, phonological, and nonverbal fluency in 32 participants with Alzheimer's disease (AD). Object but not animal semantic fluency correlated with frontal and temporal gray matter volumes. Phonological fluency was not significantly associated with any brain volume examined. Nonverbal fluency was selectively associated with bilateral frontal gray matter volumes. Hippocampal volumes, although markedly reduced in these patients, were not related to any of the fluency measures. Results lend evidence to the importance of the frontal lobes in the directed generation of nonverbal and verbal exemplars by AD patients. Furthermore, both left and right-hemisphere regions contribute to the generation of verbal and nonverbal exemplars. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
99.
Cerebellar volume decline in normal aging, alcoholism, and Korsakoff's syndrome: Relation to ataxia.
Sullivan Edith V.; Deshmukh Anjali; Desmond John E.; Lim Kelvin O.; Pfefferbaum Adolf 《Canadian Metallurgical Quarterly》2000,14(3):341
The authors used magnetic resonance imaging to measure gray and white matter volumes in cerebellar hemispheres and 4 vermian regions in 61 normal control (NC) men aged 23–72 years, 25 men with uncomplicated alcoholism (ALC), and 8 men and 1 woman with alcoholic Korsakoff's syndrome (KS). NC and ALC took quantitative gait and balance tests. Gray but not white matter volume declined with normal age in both hemispheres and anterior–superior vermis. ALC had gray but not white matter cerebellar hemisphere volume deficits, whereas KS had deficits in both tissue types. ALC and KS had gray and white matter volume deficits in anterior superior but not posterior inferior vermis. ALC had a 1 SD ataxia deficit, significantly and selectively correlated with white matter volume in anterior superior vermis. Regional distribution but not severity of cerebellar volume deficits is similar in alcoholic individuals whether or not complicated by KS and relates to ataxia. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
100.
Fundamental study on the effect of hydrostatic pressure treatment on the bread-making performance of oat flour 总被引:2,自引:2,他引:0
Edith K. Hüttner Fabio Dal Bello Elke K. Arendt 《European Food Research and Technology》2010,230(6):827-835
The use of sourdough in wheat and rye breads has been extensively studied; however, little is known about its potential effect
when baking oat bread. Consequently, the impact of sourdough on oat bread quality was investigated. Two different sourdoughs
were prepared from wholegrain oat flour without the addition of starter cultures, by continuous propagation at 28 (SD 28)
or 37 °C (SD 37) until the composition of the lactic acid bacteria remained stable. The dominant LAB were identified by sequence
analysis of the 16S rDNA isolated from pure cultures. LAB from SD 28 belonged to the species Leuconostoc argentinum, Pedicoccus pentosaceus and Weissella cibaria, while Lactobacillus coryniformis dominated SD 37. The isolated LAB were further used as starter cultures for the production of oat sourdoughs. Fundamental
rheology revealed softening of the sourdoughs compared to non-acidified and chemically acidified controls, which could not
be attributed to proteolytic activity. Incorporation of oat sourdough into an oat bread recipe resulted in significantly increased
loaf-specific volume as well as improved texture, independent of addition level or sourdough type. Overall, the results of
this study show that sourdoughs containing lactic acid bacteria isolated from oats have the potential to enhance oat bread
quality. 相似文献