The restriction of the Ising model to a layer

We discuss the status of recent Gibbsian descriptions of the restriction (projection) of the Ising phases to a layer. We concentrate on the projection of the two-dimensional low temperature Ising phases for which we prove a variational principle.Comment: 38 page

A novel adaptive weight selection algorithm for multi-objective multi-agent reinforcement learning

To solve multi-objective problems, multiple reward signals are often scalarized into a single value and further processed using established single-objective problem solving techniques. While the field of multi-objective optimization has made many advances in applying scalarization techniques to obtain good solution trade-offs, the utility of applying these techniques in the multi-objective multi-agent learning domain has not yet been thoroughly investigated. Agents learn the value of their decisions by linearly scalarizing their reward signals at the local level, while acceptable system wide behaviour results. However, the non-linear relationship between weighting parameters of the scalarization function and the learned policy makes the discovery of system wide trade-offs time consuming. Our first contribution is a thorough analysis of well known scalarization schemes within the multi-objective multi-agent reinforcement learning setup. The analysed approaches intelligently explore the weight-space in order to find a wider range of system trade-offs. In our second contribution, we propose a novel adaptive weight algorithm which interacts with the underlying local multi-objective solvers and allows for a better coverage of the Pareto front. Our third contribution is the experimental validation of our approach by learning bi-objective policies in self-organising smart camera networks. We note that our algorithm (i) explores the objective space faster on many problem instances, (ii) obtained solutions that exhibit a larger hypervolume, while (iii) acquiring a greater spread in the objective space

On the Efficiency of Voice over Integrated Services using Guaranteed

Abstract-This paper presents an efficiency study of voice over Integrated Services (IntServ). In particular, the Guaranteed Service class is considered. This service class provides a deterministic upper bound on the end-to-end queuing delay. A method to calculate the optimal packetization delay, and hence, the optimal packet size, is presented. Choosing this packet size involves a trade-off between bandwidth efficiency and delay. Two scenarios are considered in this paper: an IP-phone-to-IP-phone and a gateway-to-gateway scenario. For the latter scenario two multiplexing approaches are evaluated and it is shown that they achieve approximately equal bandwidth efficiency. In addition our results demonstrate that with aggregated voice flows on one reserved bit pipe (gateway-to-gateway scenario) high bandwidth efficiency can be achieved. Index terms--IntServ, Voice over IP, efficiency A. INTRODUCTION 1st. Background Introducing telephony services on IP networks brings its own challenges with respect to voice quality, call set-up time and reliability. The performance of a VoIP network should be comparable to the current PSTN. Especially, the voice quality is of great concern. It depends on many parameters: on the application layer the type of codec, packetization and dejittering delay and on the transport layer the one-way delay, jitter and packet loss. The Quality of Service (QoS) of packet switched networks (e.g. IntServ) controls the transport parameters. The requirements for these parameters are requested by the voice application such that together with the application parameters a certain desired speech quality is obtained. By offering different classes of speech quality, an operator is able to offer telephony services at different prices, targeting different market segments. 2nd. Overview of previous work Telephony has very stringent delay requirements. When perfect echo control is applied, the mouth-to-ear delay should not exceed 150 ms in order to obtain traditional PSTN quality This paper extends these results with several contributions. First, for the calculations of the optimal packetization delay the (static) dejittering delay is also taken into account. Second, the bandwidth efficiency is studied for different types of codecs and third, the gateway-to-gateway scenario is considered. In other words, the scenario where a single reservation is made for an aggregate of voice flows. In this paper we first consider the IP-phone-to-IP-phone scenario with regard to the optimal packet size when a static dejittering delay is used and the bandwidth efficiency when using different types of codecs. Then, we present a study of the gateway-to-gateway scenario. In this case one bit pipe is reserved between two gateways to transport multiple calls. Two methods are considered to multiplex voice flows into a bit pipe. One method is to multiplex IP packets from different flows and the second one is to multiplex voice frames from different voice flows into a single IP packet. 3rd. Contents In Section B the different components of the mouth-to-ear delay are listed. How to specify the traffic parameters that describe a voice flow is shown in Section C. The IntServ architecture is discussed in Section D. The calculation of the optimal packetization delay for an IntServ network with Weighted Fair Queuing (WFQ) schedulers is described in Section E. The efficiency corresponding to this optimal packetization delay is evaluated in Section F. The paper concludes with Section G

A novel preference articulation operator for the Evolutionary Multi-Objective Optimisation of classifiers in concealed weapons detection

Abstract The incorporation of decision maker preferences is often neglected in the Evolutionary Multi-Objective Optimisation (EMO) literature. The majority of the research in the field and the development of EMO algorithms is primarily focussed on converging to a Pareto optimal approximation close to or along the true Pareto front of synthetic test problems. However, when EMO is applied to real-world optimisation problems there is often a decision maker who is only interested in a portion of the Pareto front (the Region of Interest) which is defined by their expressed preferences for the problem objectives. In this paper a novel preference articulation operator for EMO algorithms is introduced (named the Weighted Z-score Preference Articulation Operator) with the flexibility of being incorporated a priori, a posteriori or progressively, and as either a primary or auxiliary fitness operator. The Weighted Z-score Preference Articulation Operator is incorporated into an implementation of the Multi-Objective Evolutionary Algorithm Based on Decomposition (named WZ-MOEA/D) and benchmarked against MOEA/D-DRA on a number of bi-objective and five-objective test problems with test cases containing preference information. After promising results are obtained when comparing WZ-MOEA/D to MOEA/D-DRA in the presence of decision maker preferences, WZ-MOEA/D is successfully applied to a real-world optimisation problem to optimise a classifier for concealed weapon detection, producing better results than previously published classifier implementations

Bilateral testicular self-castration due to cannabis abuse: a case report

<p>Abstract</p> <p>Introduction</p> <p>The self-mutilating patient is an unusual psychiatric presentation in the emergency room. Nonetheless, serious underlying psychiatric pathology and drug abuse are important background risk factors. A careful stepwise approach in the emergency room is essential, although the prognosis, follow-up, and eventual rehabilitation can be problematic.</p> <p>We present a unique and original case of bilateral self-castration caused by cannabis abuse.</p> <p>Case Presentation</p> <p>We report a case of a 40-year-old Berber man, who was presented to our emergency room with externalization of both testes using his long fingernails, associated with hemodynamic shock. After stabilization of his state, our patient was admitted to the operating room where hemostasis was achieved.</p> <p>Conclusion</p> <p>The clinical characteristics of self-mutilation are manifold and there is a lack of agreement about its etiology. The complex behavior associated with drug abuse may be one cause of self-mutilation. Dysfunction of the inhibitory brain circuitry caused by substance abuse could explain why this cannabis-addicted patient lost control and self-mutilated. To the best of our knowledge, this is the first case report which presents an association between self-castration and cannabis abuse.</p