5,192 research outputs found

    Practical Algorithms for Multicast Support in Input Queues Switches

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    Abstract — This paper deals with multicast flow support in N × N Input Queued switch architectures. A practical approach to support multicast traffic is presented, assuming that O(N) queues are available at each input port. The focus is on dynamic queueing policies, where, at each input port, multicast flows are assigned to one among the available queues when flows become active: flows are assigned to queues according to switch queue status and, possibly, to flow information. We discuss queueing assignments, scheduling algorithms and flow activity definition models. We explain why dynamic queueing disciplines may outperform static policies, and we show that, even in the most favorable conditions for static policies, they provide comparable performance. I

    Infectious agents in atherosclerotic cardiovascular diseases through oxidative stress

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    Accumulating evidence demonstrates that vascular oxidative stress is a critical feature of atherosclerotic process, potentially triggered by several infectious agents that are considered as risk co-factors for the atherosclerotic cardiovascular diseases (CVDs). C. pneumoniae has been shown to upregulate multiple enzymatic systems capable of producing reactive oxygen species (ROS) such as NADPH oxidase (NOX) and cyclooxygenase in vascular endothelial cells, NOX and cytochrome c oxidase in macrophages as well as nitric oxide synthase and lipoxygenase in platelets contributing to both early and late stages of atherosclerosis. P. gingivalis seems to be markedly involved in the atherosclerotic process as compared to A. actinomycetemcomitans contributing to LDL oxidation and foam cell formation. Particularly interesting is the evidence describing the NLRP3 inflammasome activation as a new molecular mechanism underlying P. gingivalis-induced oxidative stress and inflammation. Amongst viral agents, immunodeficiency virus-1 and hepatitis C virus seem to have a major role in promoting ROS production, contributing, hence, to the early stages of atherosclerosis including endothelial dysfunction and LDL oxidation. In conclusion, oxidative mechanisms activated by several infectious agents during the atherosclerotic process underlying CVDs are very complex and not well-known, remaining, thus, an attractive target for future research

    Sensitivity Analysis of Streeter-Phelps Models

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    Sensitivity theory is applied in this paper to a class of generalized Streeter-Phelps models in order to predict the variations induced in BOD by the variations of some parameters characterizing the river system. The paper shows how simple and elegant this technique is, and at the same time proves that many relatively complex phenomena can be explained by Streeter-Phelps models

    Optimal Allocation of Artificial In-Stream Aeration

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    This paper presents some simple properties of the problem of optimal allocation and design of a system of mechanical surface aerators. These properties are proved to be valid for an extremely wide class of river quality models and it is shown how they can be usefully employed to simplify the problem and to improve the efficiency of some dynamic programming algorithms. Finally a method is suggested for dealing with the allocation problem in a river basin composed of a main stream and its tributaries

    A Min-Max Approach to Reservoir Management

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    Analysis concerned with problems of the rational use of natural resources almost invariably deals with uncertainties with regard to the future behavior of the system In question and with multiple objectives reflecting conflicting goals of the users of the resources. Uncertainty means that the information available is not sufficient to unambiguously predict the future of the system, and the multiplicity of the objectives, on the other hand, calls for establishing rational trade-offs among them. The rationality of the trade-offs is quite often of subjective nature and cannot be formally incorporated into mathematical models supporting the analysis, and the information with regard to the future may vary with time. Then the challenge to the analyst is to elaborate a mathematical and computer implemented system that can be used to perform the analysis recognizing both the above aspects of real world problems. These were the issues addressed during the summer study "Real-Time Forecast versus Real-Time Management of Hydrosystems," organized by the Resources and Environment Area of IIASA in 1981. The general line of research was the elaboration of new approaches to analyzing reservoir regulation problems and to estimating the value of the information reducing the uncertainties. Computationally, the research was based on the hydrosystem of Lake Como, Northern Italy. This paper describes the application of an innovative approach to problems of reservoir management. This approach, which focuses on a risk-adverse regulation of a hydrosystem, takes into account both major aspects of this type of problem: uncertainty with regard to inflows of water into the system, and also multiple objectives which are faced by the manager. The theoretical basis of the approach has been described in another paper of this series of publications. This paper is more application-oriented, and contains also computational results for the regulation problem of Lake Como in Northern Italy

    Uncertainty and Multiple Objectives in Storage Control Problems (A Min-Max Approach)

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    Analysis concerned with problems of the rational use of natural resources almost invariably deals with uncertainties with regard to the future behavior of the system in question and with multiple objectives reflecting conflicting goals of the users of the resources. Uncertainty means that the information available is not sufficient to unambiguously predict the future of the system, and the multiplicity of the objectives, on the other hand, calls for establishing rational trade-offs among them. The rationality of the trade-offs is quite often of subjective nature and can not be formally incorporated into mathematical models supporting the analysis, and the information with regard to the future may vary with time. Then the challenge to the analyst is to elaborate a mathematical and computer implemented system that can be used to perform the analysis recognizing both the above aspects of real world problems. These were the issues addressed during the summer study "Real- Time Forecast versus Real-Time Management of Hydrosystems", organized by the Resources and Environment Area of IIASA in 1981. The general line of research was the elaboration of new approaches to analyzing reservoir regulation problems and to estimating the value of the information reducing the uncertainties. Computationally, the research was based on the hydrosystem of Lake Como, Northern Italy. This paper starts a short series of IIASA publications based upon the results obtained during the study. It describes the theoretical background for the new max-min approach to analyzing multiobjective problems with uncertainties and outlines briefly some applications of the approach to water reservoir regulation problems

    On sequences of contractive mappings and their fixed points

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    By using a condition of Reich, we establish two fixed point theorems concerning sequences of contractive mappings and their fixed points. A suitable example is also given

    Optimal Sequencing in the Implementation of Wastewater Treatment Plants

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    If a set of wastewater treatment plants is to be installed in a river basin within a given time period, an interesting optimization problem is to select the best sequence in which the plants should be built. Two sequencing problems of this kind are discussed in this paper, and branch and bound algorithms are proposed for solving them. The validity of some simplifying assumptions and the effectiveness of the methods from a computational point of view are shown by analyzing the case of the Rhine river in The Federal Republic of Germany

    Image Correlation-Based Identification of Fracture Parameters for Structural Adhesives

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    We consider the identification problem of a cohesive model using kinematic full-field data obtained via digital image correlation during the fracture test of an adhesive joint. A criterion is presented for selecting measurements that exhibit optimal features for identification purposes. The proposed selection scheme is constructed using the sensitivity information and its performances are evaluated at varying noise-to-signal ratio

    Total Hemi-overgrowth in Pigmentary Mosaicism of the (Hypomelanosis of) Ito Type: Eight Case Reports.

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    Pigmentary mosaicism of the (hypomelanosis of) Ito type is an umbrella term, which includes phenotypes characterized by mosaic hypopigmentation in the form of streaks, whorls, patchy, or more bizarre skin configurations (running along the lines of Blaschko): these cutaneous patterns can manifest as an isolated skin disorder (pigmentary mosaicism of the Ito type) or as a complex malformation syndrome in association with extracutaneous anomalies (most often of the musculoskeletal and/or nervous systems) (hypomelanosis of Ito). Affected individuals are anecdotally reported to have also partial or total body hemi-overgrowth (HOG), which often causes moderate to severe complications.We studied the occurrence and features of HOG in the 114 children and adults with mosaic pigmentary disorders of the Ito type diagnosed and followed up (from 2 to 22 years; average follow-up 16 years) at our Institutions.Eight patients (5 M, 3 F; aged 4 to 25 years; median age 16 years) out of the 114 analyzed (7%) fulfilled the criteria for unilateral HOG, with differences in diameter ranging from 0.4 to 4.0 cm (upper limbs) and 1.0 to 9.0 cm (lower limbs). Moreover, among these 8 patients, 5/8 filled in the 75th to 90th percentile for height; 6/8 had associated kyphoscoliosis; and 5/8 showed cognitive delays. No tumour complications were recorded. Overall, 6/8 HOG patients presented with additional (extracutaneous) syndromic manifestations, apart from the HOG (ie, with a clinical phenotype of hypomelanosis of Ito).The present study, which includes children and adults with the longest follow-up so far recorded, confirms the association between pigmentary mosaicism of the Ito type and HOG lowering previous estimates (7% vs 16%) for HOG in the context of mosaic hypopigmentation. A careful examination, looking at subtle to moderate asymmetries and associated complications within the spectrum of these mosaic pigmentary disorders, is recommended
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