Anonymity and Software Agents: An Interdiscplinary Challenge

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Про деякі зв'язки та узагальнення пронормальних підгруп

Отримано нові результати щодо зв'язків та узагальнень пронормальних підгруп. Зокрема, розглянуто групи, кожна циклічна підгрупа яких є самоспряжено-переставною. Наведено повний опис таких груп в деяких дуже широких класах груп, які містять в собі всі скінченні групи.Получены новые результаты относительно связей и обобщений пронормальных подгрупп. В частности, рассмотрены группы, каждая циклическая подгруппа которых является самосопряженно-переставляемой. Приведено полное описание таких групп в некоторых очень широких классах групп, которые содержат в себе все конечные группы.New results concerning the connections and generalizations of pronormal subgroups are presented. In particular, we studied groups, in which every cyclic subgroup is self-conjugate-permutable. We obtained the full description of such groups in some very wide classes of groups which contain all finite groups

Predictive value of Escherichia coli susceptibility in strains causing asymptomatic bacteriuria for women with recurrent symptomatic urinary tract infections receiving prophylaxis

AbstractA significant proportion of women develop a recurrence following an initial urinary tract infection (UTI). In women with recurrent UTI, the predictive value of asymptomatic bacteriuria (ASB) for the development of a subsequent UTI has not yet been established and it is not known whether information from an asymptomatic sample is useful in guiding antimicrobial therapy. To address these questions, we used data that originated from the ‘Non-antibiotic prophylaxis for recurrent urinary tract infections’ (NAPRUTI) study: two randomized controlled trials on the prevention of recurrent UTI in non-hospitalized premenopausal and postmenopausal women (n = 445). During 15 months of follow-up, no difference was observed in the time to a subsequent UTI between women with and without ASB at baseline (hazard ratio: 1.07, 95% CI 0.80–1.42). The antimicrobial susceptibility and pulsed-field gel-electrophoresis (PFGE) pattern of 50 Escherichia coli strains causing a UTI were compared with those of the ASB strain isolated 1 month previously. The predictive values of the susceptibility pattern of the ASB strain, based on resistance prevalence at baseline, were ≥76%, except in the case of nitrofurantoin-and amoxicillin-clavulanic acid-resistance. Asymptomatic and symptomatic isolates had similar PFGE patterns in 70% (35/50) of the patients. In the present study among women with recurrent UTI receiving prophylaxis, ASB was not predictive for the development of a UTI. However, the susceptibility pattern of E. coli strains isolated in the month before a symptomatic E. coli UTI can be used to make informed choices for empirical antibiotic treatment in this patient population

Spatial heterogeneity and irreversible vegetation change in semi-arid grazing systems

Recent theoretical studies have shown that spatial redistribution of surface water may explain the occurrence of patterns of alternating vegetated and degraded patches in semiarid grasslands. These results implied, however, that spatial redistribution processes cannot explain the collapse of production on coarser scales observed in these systems. We present a spatially explicit vegetation model to investigate possible mechanisms explaining irreversible vegetation collapse on coarse spatial scales. The model results indicate that the dynamics of vegetation on coarse scales are determined by the interaction of two spatial feedback processes. Loss of plant cover in a certain area results in increased availability of water in remaining vegetated patches through run-on of surface water, promoting within-patch plant production. Hence, spatial redistribution of surface water creates negative feedback between reduced plant cover and increased plant growth in remaining vegetation. Reduced plant cover, however, results in focusing of herbivore grazing in the remaining vegetation. Hence, redistribution of herbivores creates positive feedback between reduced plant cover and increased losses due to grazing in remaining vegetated patches, leading to collapse of the entire vegetation. This may explain irreversible vegetation shifts in semiarid grasslands on coarse spatial scales