972 resultados para voltage stability margin


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We analyze which normal form solution concepts capture the notion offorward induction, as defined by van Damme (JET, 1989) in the classof generic two player normal form games preceded by an outsideoption. We find that none of the known strategic stability concepts(including Mertens stable sets and hyperstable sets) captures this form of forward induction. On the other hand, we show that the evolutionary concept of EES set (Swinkels, JET, 1992) is always consistent with forward induction.

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We argue the importance both of developing simple sufficientconditions for the stability of general multiclass queueing networks and also of assessing such conditions under a range of assumptions on the weight of the traffic flowing between service stations. To achieve the former, we review a peak-rate stability condition and extend its range of application and for the latter, we introduce a generalisation of the Lu-Kumar network on which the stability condition may be tested for a range of traffic configurations. The peak-rate condition is close to exact when the between-station traffic is light, but degrades as this traffic increases.

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This study investigates the intra-individual stability of the speed of several motor tasks and the intensity of associated movements in 256 children (131 girls, 125 boys) from the Zurich generational study using the Zurich neuromotor assessment battery (ZNA) over a 12-year period from the age of 6 to 18 years. The stability was assessed by correlograms of standard deviation scores calculated from age- and gender-adjusted normative values and compared with standing height and full scale intelligence quotient (IQ). While motor tasks of hand, finger and foot (HFT) and contralateral associated movements (CAM) exhibited a moderate stability (summary measure as correlation coefficients between two measurements made 4 years apart: .61 and .60), other tasks (dynamic balance, static balance and pegboard) were only weakly stable (.46, .47 and .49). IQ and height were more stable than neuromotor components (.72 and .86). We conclude that the moderately stable HFT and CAM may reflect "motor traits", while the stability of the pegboard and balance tasks is weaker because these skills are more experience related and state-dependent.

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This paper presents a classical Cournot oligopoly model with some peculiar features: it is non--quasi--competitive as price under N-poly is greater than monopoly price; Cournot equilibrium exists and is unique with each new entry; the successive equilibria after new entries are stable under the adjustment mechanism that assumes that actual output of each seller is adjusted proportionally to the difference between actual output and profit maximizing output. Moreover, the model tends to perfect competition as N goes to infinity, reaching the monopoly price again.

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Croisant les concepts de traduction culturelle et une approche « queer » de l'identité, notre article propose une lecture de l'utilisation de tropes végétaux ou organiques dans le roman de Geetanjali Shree, Mai, comme critique de la logique binaire du centre et de la marge qui caractérise autant l'orientalisme que le système patriarcal. Ecrit à la première personne, le roman invente un nouvel espace d'énonciation en narrant l'enfance et la jeunesse d'une jeune femme et la constitution de son identité à travers la relation complexe qu'elle entretient avec sa mère, son milieu familial issu de la classe moyenne du Nord de l'Inde, et la société indienne contemporaine aux prises avec la globalisation. Toutefois, ce cercle ou centre est en constante évolution puisque le contexte postcolonial dans lequel ces identités féminines se situent nous amène à considérer d'autres modes d'intervention (agency) qui opèrent non seulement à travers la prise de parole mais aussi à travers l'usage stratégique du silence. Fleurissant entre l'anglais et le hindi, ces identités hybrides nous poussent à revoir nos cartographies critiques et à investiguer et investir des lieux liminaux dans lesquels des subjectivités traversent les frontières et transgressent les limites imposées par l'ordre patriarcal et les cartographies imposées par les centres de pouvoir.

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We described the colonization dynamics of Staphylococcus aureus in a group of 266 healthy carriers over a period of approximately 1 year. We used precise genotyping methods, i.e., amplified fragment length polymorphism (AFLP), spa typing, and double-locus sequence typing (DLST), to detect changes in strain identity. Strain change took place rather rarely: out of 89 carriers who had initially been colonized, only 7 acquired a strain different from the original one. Approximately one-third of the carriers eliminated the colonization, and a similar number became newly colonized. Some of these events probably represent detection failure rather than genuine colonization loss or acquisition. Lower bacterial counts were associated with increased probability of eliminating the colonization. We have confirmed a high mutation rate in the spa locus: 6 out of 53 strains underwent mutation in the spa locus. There was no overall change in S. aureus genotype composition.

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Travertines and volcanic landforms in the eastern pyrenees margin

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The second differential of the entropy is used for analysing the stability of a thermodynamic climatic model. A delay time for the heat flux is introduced whereby it becomes an independent variable. Two different expressions for the second differential of the entropy are used: one follows classical irreversible thermodynamics theory; the second is related to the introduction of response time and is due to the extended irreversible thermodynamics theory. the second differential of the classical entropy leads to unstable solutions for high values of delay times. the extended expression always implies stable states for an ice-free earth. When the ice-albedo feedback is included, a discontinuous distribution of stable states is found for high response times. Following the thermodynamic analysis of the model, the maximum rates of entropy production at the steady state are obtained. A latitudinally isothermal earth produces the extremum in global entropy production. the material contribution to entropy production (by which we mean the production of entropy by material transport of heat) is a maximum when the latitudinal distribution of temperatures becomes less homogeneous than present values

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The involvement of voltage-gated calcium channels in the survival of immature CNS neurons was studied in aggregating brain cell cultures by examining cell type-specific effects of various channel blockers. Nifedipine (10 microM), a specific blocker of L-type calcium channels, caused a pronounced and irreversible decrease of glutamic acid decarboxylase activity, whereas the activity of choline acetyltransferase was significantly less affected. Flunarizine (1-10 microM, a relatively unspecific ion channel blocker) elicited similar effects, that were attenuated by NMDA. The glia-specific marker enzymes, glutamine synthetase and 2',3'-cyclic nucleotide 3'-phosphohydrolase, were affected only after treatment with high concentrations of nifedipine (50 microM) or NiCl2 (100 microM, shown to block T-type calcium channels). Nifedipine (50 microM), NiCl2 (100 microM), and flunarizine (5 microM) also caused a significant increase in the soluble nucleosome concentration, indicating increased apoptotic cell death. This effect was prevented by cycloheximide (1 microM). Furthermore, the combined treatment with calcicludine (10 nM, blocking L-type calcium channels) and funnel-web spider toxin-3.3 (100 nM, blocking T-type channels) also caused a significant increase in free nucleosomes as well as a decrease in glutamic acid decarboxylase activity. In contrast, cell viability was not affected by peptide blockers specific for N-, P-, and/or Q-type calcium channels. Highly differentiated cultures showed diminished susceptibility to nifedipine and flunarizine. The present data suggest that the survival of immature neurons, and particularly that of immature GABAergic neurons, requires the sustained entry of Ca2+ through voltage-gated calcium channels.

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Neuroimaging studies typically compare experimental conditions using average brain responses, thereby overlooking the stimulus-related information conveyed by distributed spatio-temporal patterns of single-trial responses. Here, we take advantage of this rich information at a single-trial level to decode stimulus-related signals in two event-related potential (ERP) studies. Our method models the statistical distribution of the voltage topographies with a Gaussian Mixture Model (GMM), which reduces the dataset to a number of representative voltage topographies. The degree of presence of these topographies across trials at specific latencies is then used to classify experimental conditions. We tested the algorithm using a cross-validation procedure in two independent EEG datasets. In the first ERP study, we classified left- versus right-hemifield checkerboard stimuli for upper and lower visual hemifields. In a second ERP study, when functional differences cannot be assumed, we classified initial versus repeated presentations of visual objects. With minimal a priori information, the GMM model provides neurophysiologically interpretable features - vis à vis voltage topographies - as well as dynamic information about brain function. This method can in principle be applied to any ERP dataset testing the functional relevance of specific time periods for stimulus processing, the predictability of subject's behavior and cognitive states, and the discrimination between healthy and clinical populations.

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A cutaneous horn was observed close to the free margin of the inferior right eyelid in a 26-year-old-male patient. A minimal resection was primarily performed. Histopathologic study disclosed a precancerous keratosis. As the tumor had not been entirely excised, a complementary resection was performed secondarily to obtain the entire resection of the tumor.