Price of anarchy in non-cooperative load balancing games

We investigate the price of anarchy of a load balancing game with K dispatchers. The service rates and holding costs are assumed to depend on the server, and the service discipline is assumed to be processor-sharing at each server. The performance criterion is taken to be the weighted mean number of jobs in the system, or equivalently, the weighted mean sojourn time in the system. Independent of the state of the servers, each dispatcher seeks to determine the routing strategy that optimizes the performance for its own traffic. The interaction of the various dispatchers thus gives rise to a non-cooperative game. For this game, we first show that, for a fixed amount of total incoming traffic, the worst-case Nash equilibrium occurs when each player routes exactly the same amount of traffic, i.e., when the game is symmetric. For this symmetric game, we provide the expression for the loads on the servers at the Nash equilibrium. Using this result, we then show that, for a system with two or more servers, the price of anarchy, which is the worst-case ratio of the global cost of the Nash equilibrium to the global cost of the centralized setting, is lower bounded by K(2√K-1) and upper bounded by √K, independent of the number of servers

An exploration of evidence-based policy in Ireland: health and social inclusion

Ireland is a small country with a history of a social partnership approach to policy making. This paper considers how the ambition of government to utilise an evidence-based approach to policy making plays out against this partnership agenda. Drawing on the authors\u27 experiences and personal reflections, the paper considers how these issues operate within a number of health and social inclusion policy areas, and it explores the role of stakeholders\u27 expectations and involvement in generating evidence for policy

Data driven SMART intercontinental overlay networks

This paper addresses the use of Big Data and machine learning based analytics to the real-time management of Internet scale Quality-of-Service Route Optimisation with the help of an overlay network. Based on the collection of large amounts of data sampled each $2$ minutes over a large number of source-destinations pairs, we show that intercontinental Internet Protocol (IP) paths are far from optimal with respect to Quality of Service (QoS) metrics such as end-to-end round-trip delay. We therefore develop a machine learning based scheme that exploits large scale data collected from communicating node pairs in a multi-hop overlay network that uses IP between the overlay nodes themselves, to select paths that provide substantially better QoS than IP. The approach inspired from Cognitive Packet Network protocol, uses Random Neural Networks with Reinforcement Learning based on the massive data that is collected, to select intermediate overlay hops resulting in significantly better QoS than IP itself. The routing scheme is illustrated on a $20$-node intercontinental overlay network that collects close to $2\times 10^6$ measurements per week, and makes scalable distributed routing decisions. Experimental results show that this approach improves QoS significantly and efficiently in a scalable manner

Insectos e ácaros fitófagos presentes em pomares de citrinos da Ilha Terceira (Açores).

IX Expedição Científica do Departamento de Biologia - Terceira 1994.Com a presente lista de insectos e ácaros fitófagos, elaborada na sequência da Expedição Científica Terceira/94, em Junho-Julho de 1994, foi possível acrescentar comunidade dos agroecossistemas citrícolas da ilha Terceira várias espécies. Esta lista é discutida sob o ponto de vista da distribuição das espécies noutras ilhas e ainda da sua importância económica em Portugal Continental. Foram observadas 20 espécies repartidas por 12 famílias: 9 para os insectos e 3 para os ácaros. 0s Homópteros contem 65% da riqueza específica

Distillation of GHZ states by selective information manipulation

Methods for distilling maximally entangled tripartite (GHZ) states from arbitrary entangled tripartite pure states are described. These techniques work for virtually any input state. Each technique has two stages which we call primary and secondary distillation. Primary distillation produces a GHZ state with some probability, so that when applied to an ensemble of systems, a certain percentage is discarded. Secondary distillation produces further GHZs from the discarded systems. These protocols are developed with the help of an approach to quantum information theory based on absolutely selective information, which has other potential applications.Comment: minor corrections, especially of some numerical values; conclusions unaffecte

Discrete-time quantum walks on one-dimensional lattices

In this paper, we study discrete-time quantum walks on one-dimensional lattices. We find that the coherent dynamics depends on the initial states and coin parameters. For infinite size of lattice, we derive an explicit expression for the return probability, which shows scaling behavior $P(0,t)\sim t^{-1}$ and does not depends on the initial states of the walk. In the long-time limit, the probability distribution shows various patterns, depending on the initial states, coin parameters and the lattice size. The average mixing time $M_{\epsilon}$ closes to the limiting probability in linear $N$ (size of the lattice) for large values of thresholds $\epsilon$. Finally, we introduce another kind of quantum walk on infinite or even-numbered size of lattices, and show that the walk is equivalent to the traditional quantum walk with symmetrical initial state and coin parameter.Comment: 17 pages research not

Differential rotation in fully convective stars

Under the assumption of thermal wind balance and effective entropy mixing in constant rotation surfaces, the isorotational contours of the solar convective zone may be reproduced with great fidelity. Even at this early stage of development, this helioseismology fit may be used to put a lower bound on the midlatitude {\em radial} solar entropy gradient, which in good accord with standard mixing length theory. In this paper, we generalize this solar calculation to fully convective stars (and potentially planets), retaining the assumptions of thermal wind balance and effective entropy mixing in isorotational surfaces. It is found that each isorotation contour is of the form $R^2 = A+B\Phi(r)$, where $R$ is the radius from the rotation axis, $\Phi(r)$ is the (assumed spherical) gravitational potential, and $A$ and $B$ are constant along the contour. This result is applied to simple models of fully convective stars. Both solar-like surface rotation profiles (angular velocity decreasing toward the poles) as well as "antisolar" profiles (angular velocity increasing toward the poles) are modeled; the latter bear some suggestive resemblance to numerical simulations. We also perform exploratory studies of zonal surface flows similar to those seen in Jupiter and Saturn. In addition to providing a practical framework for understanding the results of large scale numerical simulations, our findings may also prove useful in dynamical calculations for which a simple but viable model for the background rotation profile in a convecting fluid is needed. Finally, our work bears directly on an important goal of the CoRoT program: to elucidate the internal structure of rotating, convecting stars.Comment: 21 pages, 20 figures. Accepted for publication in MNRA

Horizontally-aligned carbon nanotubes arrays and their interactions with liquid crystal molecules: Physical characteristics and display applications

We report on the physical characteristics of horizonthally-grown Single-Walled Carbon Nanotubes (h-al-SWNT) arrays and their potential use as transparent and conducting alignment layer for liquid crystals display devices. Microscopy (SEM and AFM), spectroscopic (Raman) and electrical investigations demonstrate the strong anisotropy of h-al-SWNT arrays. Optical measurements show that h-al-SWNTs are efficient alignment layers for Liquid Crystal (LC) molecules allowing the fabrication of optical wave plates. Interactions between h-al-SWNT arrays and LC molecules are also investigated evidencing the weak azimuthal anchoring energy at the interface, which, in turn, leads to LC devices with a high pretilt angle. The electro-optical reponses of h-al-SWNT/LC cells demonstrate that h-al-SWNT arrays are efficient nanostructured electrodes with potential use for the combined replacement of Indium Tin Oxyde and polymeric alignment layers in conventional displays