9,562 research outputs found

    A bayesian analysis of beta testing

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    In this article, we define a model for fault detection during the beta testing phase of a software design project. Given sampled data, we illustrate how to estimate the failure rate and the number of faults in the software using Bayesian statistical methods with various different prior distributions. Secondly, given a suitable cost function, we also show how to optimise the duration of a further test period for each one of the prior distribution structures considered

    Solitons and Almost-Intertwining Matrices

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    We define the set of almost-intertwining matrices to be all triples(X,Y,Z) of n x n matrices for which XZ=YX+T for some rank one matrix T. A surprisingly simple formula is given for tau-functions of the KP hierarchy in terms of such triples. The tau-functions produced in this way include the soliton and vanishing rational solutions. The induced dynamics of the eigenvalues of the matrix X are considered, leading in special cases to the Ruijsenaars-Schneider particle system

    Inference for double Pareto lognormal queues with applications

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    In this article we describe a method for carrying out Bayesian inference for the double Pareto lognormal (dPlN) distribution which has recently been proposed as a model for heavy-tailed phenomena. We apply our approach to inference for the dPlN/M/1 and M/dPlN/1 queueing systems. These systems cannot be analyzed using standard techniques due to the fact that the dPlN distribution does not posses a Laplace transform in closed form. This difficulty is overcome using some recent approximations for the Laplace transform for the Pareto/M/1 system. Our procedure is illustrated with applications in internet traffic analysis and risk theory.Heavy tails, Bayesian inference, Queueing theory

    In vitro effect of canine hyperimmune sera on TNFa activity

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    [Introduction]: Septic shock in dogs is caused by cardiovascular and vasomotor failure associated with an uncontrolled intrinsic release of inflammatory mediators [1–5]. The syndrome is characterized by cardiovascular dysfunction, vascular permeability alterations, pulmonary oedema and tissue hypoxia resulting from microthrombi which may culminate in disseminated intravascular coagulation and catastrophic multiple organ failure [6,7]. Systemic bacterial infection, particularly by Gram-negative enterobacteria, haemorrhagic trauma, gastric dilation/volvulus and pancreatitis are the major underlying causes leading tosepsis [8,9]. Because of haemodynamic instability and associated hypovolemia, fluid replacement therapy is generally applied to restore effective circulating volume. The use of fresh frozen plasma has been recommended in cases of coagulopathies as it has been recognized to assist restoration of haemodynamic stability [1,5,10,11]. There is increasing evidence that the drivers of the haemodynamic instability are inflammatory mediators (particularly TNFa) activated primarily by bacterial endotoxin [3,4,12,13]

    Inference for double Pareto lognormal queues with applications

    Get PDF
    In this article we describe a method for carrying out Bayesian inference for the double Pareto lognormal (dPlN) distribution which has recently been proposed as a model for heavy-tailed phenomena. We apply our approach to inference for the dPlN/M/1 and M/dPlN/1 queueing systems. These systems cannot be analyzed using standard techniques due to the fact that the dPlN distribution does not posses a Laplace transform in closed form. This difficulty is overcome using some recent approximations for the Laplace transform for the Pareto/M/1 system. Our procedure is illustrated with applications in internet traffic analysis and risk theory

    Reconciling diverse lacustrine and terrestrial system response to penultimate deglacial warming in southern Europe

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    Unlike the most recent deglaciation, the regional expression of climate changes during the penultimate deglaciation remains understudied, even though it led into a period of excess warmth with estimates of global average temperature 1–2 °C, and sea level ∼6 m, above pre-industrial values. We present the first complete high-resolution southern European diatom record capturing the penultimate glacial-interglacial transition, from Lake Ioannina (northwest Greece). It forms part of a suite of proxies selected to assess the character and phase relationships of terrestrial and aquatic ecosystem response to rapid climate warming, and to resolve apparent conflicts in proxy evidence for regional paleohydrology. The diatom data suggest a complex penultimate deglaciation driven primarily by multiple oscillations in lake level, and provide firm evidence for the regional influence of abrupt changes in North Atlantic conditions. There is diachroneity in lake and terrestrial ecosystem response to warming at the onset of the last interglacial, with an abrupt increase in lake level occurring ∼2.7 k.y. prior to sustained forest expansion with peak precipitation. We identify the potentially important role of direct input of snow melt and glacial meltwater transfer to the subterranean karst system in response to warming, which would cause rising regional groundwater levels. This explanation, and the greater sensitivity of diatoms to subtle changes in temperature, reconciles the divergent lacustrine and terrestrial proxy evidence and highlights the sensitivity of lakes situated in mountainous karstic environments to past climate warming
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