497 research outputs found

    Autonomic service configuration for telecommunication MASs with extended role-based GAIA and JADEx

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    Autonomie Communications have attracted huge attention recently for the management of telecommunication networks in the European Network Research Community. The purpose of this research is to offer the abilities such as autonomy, scalability, adaptation as well as simplicity for management application in complex networks. The accomplished networks inspired by biological mechanisms or market-based concepts could enable agents to be of intelligence, scalablility, and interoperabliliry in the management functional domains with regards to the large volume requirements from services' fulfillment perspective in decentralized Multi-Agent Systems. In accordance with TMF and FIPA specifications and requirements, the autonomy attributes self-configuring, self-adapting, self-limiting, self-preserving, and self-optimizing are involved into our simulation. Resource allocation requests are bidded for a long session in the multi-unit Vickrey-Clarke-Groves auction. This design adopts the software development methodology-GAIA and the framework-JADEx. We have shown multiple service configuration in dynamic network can be nearly optimized by autonomie behaviors via bidding according to business objectives for getting maximum revenues. We conclude this end-to-end approach maintains self-managing capability, easy-to-implement scalability, and more incentively compatible and efficient over other common implementation so that it could achieve the optimal solution to the flexible requirements for the Service Fulfillment for advanced IP networks. © 2005 IEEE

    Students' mental prototypes for functions and graphs

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    This research study investigates the concept of function developed by students studying English A-level mathematics. It shows that, while students may be able to use functions in their practical mathematics, their grasp of the theoretical nature of the function concept may be tenuous and inconsistent. The hypothesis is that students develop prototypes for the function concept in much the same way as they develop prototypes for concepts in everyday life. The definition of the function concept, though given in the curriculum, is not stressed and proves to be inoperative, with their understanding of the concept reliant on properties of familiar prototype examples: those having regular shaped graphs, such as x2 or sin*, those often encountered (possibly erroneously), such as a circle, those in which y is defined as an explicit formula in x, and so on. Investigations reveal significant misconceptions. For example, threequarters of a sample of students starting a university mathematics course considered that a constant function was not a function in either its graphical or algebraic forms, and threequarters thought that a circle is a function. This reveals a wide gulf between the concepts as perceived to be taught and as actually learned by the students

    Saints, heroes, sages, and villains

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    This essay explores the question of how to be good. My starting point is a thesis about moral worth that I’ve defended in the past: roughly, that an action is morally worthy if and only it is performed for the reasons why it is right. While I think that account gets at one important sense of moral goodness, I argue here that it fails to capture several ways of being worthy of admiration on moral grounds. Moral goodness is more multi-faceted. My title is intended to capture that multi-facetedness: the essay examines saintliness, heroism, and sagacity. The variety of our common-sense moral ideals underscores the inadequacy of any one account of moral admirableness, and I hope to illuminate the distinct roles these ideals play in our everyday understanding of goodness. Along the way, I give an account of what makes actions heroic, of whether such actions are supererogatory, and of what, if anything, is wrong with moral deference. At the close of the essay, I begin to explore the flipside of these ideals: villainy

    Disaggregating political authority: what's wrong with Rawlsian civil disobedience?

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    Contemporary philosophical and theoretical discussions of civil disobedience hope to contribute to significant political debates around when and in which forms political dissent, protest and resistance is appropriate. In doing so, they often focus on and criticize John Rawls' work on civil disobedience. However, ignoring the frame in which Rawls discusses civil disobedience has led critics to wrongly attack his theory for being too restrictive when it is more likely to be too permissive. That permissiveness depends on treating any political order which does not come close to fulfilling his theory of justice as absolutely illegitimate. In this sense, Rawls’ theory of political authority is binary and demanding. The problems his theory shares with most others, including his critics’, show that political authority needs to be disaggregated to make sense of the conditions under which different forms of protest and resistance are appropriate

    Diagnosing students' difficulties in learning mathematics

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    This study considers the results of a diagnostic test of student difficulty and contrasts the difference in performance between the lower attaining quartile and the higher quartile. It illustrates a difference in qualitative thinking between those who succeed and those who fail in mathematics, illustrating a theory that those who fail are performing a more difficult type of mathematics (coordinating procedures) than those who succeed (manipulating concepts). Students who have to coordinate or reverse processes in time will encounter far greater difficulty than those who can manipulate symbols in a flexible way. The consequences of such a dichotomy and implications for remediation are then considered

    Origin of molecular oxygen in Comet 67P/Churyumov-Gerasimenko

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    Molecular oxygen has been detected in the coma of comet 67P/Churyumov-Gerasimenko with abundances in the 1-10% range by the ROSINA-DFMS instrument on board the Rosetta spacecraft. Here we find that the radiolysis of icy grains in low-density environments such as the presolar cloud may induce the production of large amounts of molecular oxygen. We also show that molecular oxygen can be efficiently trapped in clathrates formed in the protosolar nebula, and that its incorporation as crystalline ice is highly implausible because this would imply much larger abundances of Ar and N2 than those observed in the coma. Assuming that radiolysis has been the only O2 production mechanism at work, we conclude that the formation of comet 67P/Churyumov-Gerasimenko is possible in a dense and early protosolar nebula in the framework of two extreme scenarios: (1) agglomeration from pristine amorphous icy grains/particles formed in ISM and (2) agglomeration from clathrates that formed during the disk's cooling. The former scenario is found consistent with the strong correlation between O2 and H2O observed in 67P/C-G's coma while the latter scenario requires that clathrates formed from ISM icy grains that crystallized when entering the protosolar nebula.Comment: The Astrophysical Journal Letters, in pres

    Egalitarian justice and expected value

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    According to all-luck egalitarianism, the differential distributive effects of both brute luck, which defines the outcome of risks which are not deliberately taken, and option luck, which defines the outcome of deliberate gambles, are unjust. Exactly how to correct the effects of option luck is, however, a complex issue. This article argues that (a) option luck should be neutralized not just by correcting luck among gamblers, but among the community as a whole, because it would be unfair for gamblers as a group to be disadvantaged relative to non-gamblers by bad option luck; (b) individuals should receive the warranted expected results of their gambles, except insofar as individuals blamelessly lacked the ability to ascertain which expectations were warranted; and (c) where societal resources are insufficient to deliver expected results to gamblers, gamblers should receive a lesser distributive share which is in proportion to the expected results. Where all-luck egalitarianism is understood in this way, it allows risk-takers to impose externalities on non-risk-takers, which seems counterintuitive. This may, however, be an advantage as it provides a luck egalitarian rationale for assisting ‘negligent victims’

    Cardiac Afferent Denervation Abolishes Ganglionated Plexi and Sympathetic Responses to Apnea: Implications for Atrial Fibrillation

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    Background: The autonomic nervous system response to apnea and its mechanistic connection to atrial fibrillation (AF) are unclear. We hypothesize that sensory neurons within the ganglionated plexi (GP) play a role. We aimed to delineate the autonomic response to apnea and to test the effects of ablation of cardiac sensory neurons with resiniferatoxin (RTX), a neurotoxic TRPV1 (transient receptor potential vanilloid 1) agonist. Methods Sixteen dogs were anesthetized and ventilated. Apnea was induced by stopping ventilation until oxygen saturations decreased to 80%. Nerve recordings from bilateral vagal nerves, left stellate ganglion, and anterior right GP were obtained before and during apnea, before and after RTX injection in the anterior right GP (protocol 1, n=7). Atrial effective refractory period and AF inducibility on single extrastimulation were assessed before and during apnea, and before and after intrapericardial RTX administration (protocol 2, n=9). GPs underwent immunohistochemical staining for TRPV1. Results Apnea increased anterior right GP activity, followed by clustered crescendo vagal bursts synchronized with heart rate and blood pressure oscillations. On further oxygen desaturation, a tonic increase in stellate ganglion activity and blood pressure ensued. Apnea-induced effective refractory period shortening from 110.20+/-31.3 ms to 90.6+/-29.1 ms ( P<0.001), and AF induction in 9/9 dogs versus 0/9 at baseline. After RTX administration, increases in GP and stellate ganglion activity and blood pressure during apnea were abolished, effective refractory period increased to 126.7+/-26.9 ms ( P=0.0001), and AF was not induced. Vagal bursts remained unchanged. GP cells showed cytoplasmic microvacuolization and apoptosis. Conclusions Apnea increases GP activity, followed by vagal bursts and tonic stellate ganglion firing. RTX decreases sympathetic and GP nerve activity, abolishes apnea's electrophysiological response, and AF inducibility. Sensory neurons play a role in apnea-induced AF
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