Abstract
In IEEE 802.11 based wireless networks adding more access points does not always guarantee an increase of network capacity. In some cases, additional access points may contribute to degrade the aggregated network throughput as more interference is introduced. This paper characterizes the power interference in CSMA/CA based networks consisting of nodes using directional antenna. The severity of the interference is quantized via an improved form of the Attacking Case metric as the original form of this metric was developed for nodes using omnidirectional antenna. The proposed metric is attractive because it considers nodes using directional or omnidirectional antenna, and it enables the quantization of interference in wireless networks using multiple transmission power schemes. The improved Attacking Case metric is useful to study the aggregated throughput of IEEE 802.11 based networks; reducing Attacking Case probably results in an increase of aggregated throughput. This reduction can be implemented using strategies such as directional antenna, transmit power control, or both.

Abstract
Cyber Physical Production Systems (CPSS) built on the concept of “Plug-and-Produce” aim at delivering truly agile production systems. These systems are modular by nature and can be adapted based on changing requirements. One of the challenges in this domain is how to store and propagate information within CPPS. In this paper, a Redundant and Decentralised Directory Facilitator will be introduced to provide the capability to store and broadcast the existing system assembly capabilities. Additionally, this solution will provide redundancy and delocalization of the assembly capabilities information. The model used is described, as well as interactions, behaviours and deployment strategies. Finally a validation scenario is presented and conclusions are discussed. © Springer International Publishing AG 2017.

Abstract
ICT in healthcare businesses has been growing in Portugal in the past few decades. The implementation of large scale information systems in hospitals, the deployment of electronic prescription and electronic patient records applications are just a few examples. Telemedicine is another emergent and widely used ICT solution to smooth the communication between patients and healthcare professionals, by allowing video and voice transfer over the Internet. Although there are several implementations of telemedicine solutions, they usually have some drawbacks, namely: i) too specific for a purpose; ii) based on proprietary applications; iii) require additional software installation; iv) and usually have associated costs. In this paper we propose a telemedicine solution based on WebRTC Application Programming Interface (API) to transmit video and voice in real time over the Internet, through a web browser. Besides microphone and webcam control, we have also included two additional functionalities that may be useful to both patients and healthcare professionals during the communication, namely i) bidirectional sending files capability and ii) shared whiteboard which allows free drawing. The proposed solution uses exclusively open source software components and requires solely a WebRTC compatible web browser, like Google Chrome or Firefox. We have made two types of tests in healthcare environment: i) a bidirectional patient-doctor communication; ii) and connecting at one end an external USB medical device with an integrated webcam. The results were promising, since they revealed the potential of using WebRTC API to control microphone and webcam in a telemedicine application, as well as the appropriateness and acceptance of the features included. (C) 2016 Published by Elsevier B.V.

Abstract
Grid connected energy storage systems are regarded as promising solutions for providing ancillary services to electricity networks and to play an important role in the development of smart grids. Thus far, the more mature battery technologies have been installed in pilot projects and studies have indicated their main advantages and shortcomings. The main concerns for wide adoption are the overall cost, the limited number of charging cycles (or lifetime), the depth of discharge, the low energy density and the sustainability of materials used. Vanadium Redox Flow Batteries (VRFB) are a promising option to mitigate many of these shortcomings, and demonstration projects using this technology are being implemented both in Europe and in the USA. This study presents a model using MATLAB/Simulink, to demonstrate how a VRFB based storage device can provide multi-ancillary services, focusing on frequency regulation and peak-shaving functions. The study presents a storage system at a medium voltage substation and considers a small grid load profile, originating from a residential neighbourhood and fast charging stations demand. The model also includes an inverter controller that provides a net power output from the battery system, in order to offer both services simultaneously. Simulation results show that the VRFB storage device can regulate frequency effectively due to its fast response time, while still performing peak-shaving services. VRFB potential in grid connected systems is discussed to increase awareness of decision makers, while identifying the main challenges for wider implementation of storage systems, particularly related to market structure and standardisation requirements.

Abstract
This research aims to verify whether physical activity influences the levels of self-esteem and depression in the elderly. The sample is constituted by 215 subjects (61 males and 154 females), practitioners and non-practitioners of physical activity, aged 60 to 100 years. The study variables were evaluated by applying two instruments, the Rosenberg Self-Esteem Scale and the Anxiety, Depression and Stress Scale (DASS-21). The results showed that elderly people who practice physical activity reveal high levels of self-esteem and lower levels of depression. It was found that self-esteem decreases with age, while depressive symptoms increase. Gender, marital status, educational level and institutionalization reached statistical significance in the self-esteem scale. Were elderly male, with partners, higher educational level and non-institutionalized who reported higher levels. We conclude that as the frequency of physical activity increases, levels of selfesteem become more accentuated, while levels of depression decrease. Regarding the relationship between self-esteem and depression, there was a negative correlate with small effect. © 2016: Servicio de Publicaciones de la Universidad de Murcia Murcia (España).

Abstract
QVT Relations (QVT-R) is the standard language proposed by the OMG to specify bidirectional model transformations. Unfortunately, in part due to ambiguities and omissions in the original semantics, acceptance and development of effective tool support have been slow. Recently, the checking semantics of QVT-R has been clarified and formalized. In this article, we propose a QVT-R tool that complies to such semantics. Unlike any other existing tool, it also supports meta-models enriched with OCL constraints (thus avoiding returning ill-formed models) and proposes an alternative enforcement semantics that works according to the simple and predictable "principle of least change." The implementation is based on an embedding of both QVT-R transformations and UML class diagrams (annotated with OCL) in Alloy, a lightweight formal specification language with support for automatic model finding via SAT solving. We also show how this technique can be applied to bidirectionalize ATL, a popular (but unidirectional) model transformation language.