Properties of enhançons in supergravity

A certain class of naked singularities, related to N = 2 pure super Yang-Mills theory, are resolved in string theory with the enhançon mechanism. We study the properties of the enhançon in supergravity. Initially we consider the stability of the supergravity solutions. We study small perturbations of these solutions, constructing a sufficiently general ansatz for linearised perturbations of the non-extremal solutions, and show that the linearised equations are consistent. We investigate linearised perturbations of the horizon branch and the extremal solution numerically. We show that these solutions are stable against the perturbations we consider. This provides further evidence that these latter supergravity solutions are capturing some of the true physics of the enhançon. We show that the shell branch solutions violate the weak energy condition, and are hence unphysical. We extend the investigation of nonextremal enhançons, finding the most general solutions with the correct symmetry and charges. There are two families of solutions. One of these contains a solution with a regular horizon found previously; this previous example is shown to be the unique solution with a regular horizon. The other family generalises a previous nonextreme extension of the enhançon, producing solutions with shells which satisfy the Weak Energy Condition. We argue that identifying a unique solution with a shell requires input beyond supergravity

Scanning Electron Microscopy Studies of Extended Defects in Semiconductors

Extended defects, such as dislocations and grain boundaries, play an important role in determining the performance of various semiconductor devices. This paper reviews applications of electron-beam-induced-current and cathodoluminescence scanning electron microscopy for the investigation of dislocations and grain boundaries in semiconductors. We developed a simple analytical method for the determination of the grain boundary recombination velocity and the minority carrier diffusion length, in contrast to a previous method which requires the use of a computer for the numerical calculation of an integral expression. We, also, studied theoretically the influence of an individual dislocation on the minority carrier lifetime. Investigation of dislocations in GaP indicated that the carrier recombination takes place at a Cottrell atmosphere of the S-donor/Cu complexes surrounding the dislocations

The use of information systems for logistics and supply chain management in South East Europe: Current status and future direction

This research aims to investigate the current status and future direction of the use of information systems for logistics and supply chain management (LSCM) in South East Europe. The objectives are threefold: (1) to identify major challenges and developments on the use of information systems for LSCM by enterprises, (2) to examine the actual level of satisfaction of current policy on LSCM, and (3) to reveal the actual need of enterprises in South East Europe on effective use of information systems for LSCM. Mixed methodology of literature review and questionnaire survey is adopted in this research. Data collected from 79 enterprises are analysed using descriptive analysis in SPSS. The findings suggest that enterprises in Albania, Bulgaria, Greece, Former Yugoslav Republic of Macedonia (FYROM), Romania, and Serbia and Montenegro, face similar challenges but all are in different stages of developments of LSCM. Their use of information systems explains their heavy focus on supply chain partnership and weakness in demand chain partnership. Major findings suggest that companies and governments alike in that region do not seem to be ready for playing a significant and demanding role in global supply chains. Current deficiencies, including limited abilities in building valuable forward relations, weak strategic planning and organisation, and infrastructural problems, are major obstacles for fast development in LSCM. At the same time though, traces of changing mentalities do exist, setting the ground for improved performance and ultimately for a better position in global business

Implementing a system to evaluate quality assurance in rehabilitation in Greece.

BACKGROUND: Use of a widely accepted quality assurance tool is an essential procedure of effective and result-oriented quality management in the rehabilitation sector, and generally in health care and social services, but is still lacking in Greece. OBJECTIVE: This study aims to explore to what extent a Quality Assurance System in Rehabilitation (QASR) in the Greek setting could respond to the needs for quality evaluation of the facilities for people with a disability and to discuss possibilities of its use in rehabilitation organizations, sites and hospitals. METHODS: The European Quality in Social Services (EQUASS) Assurance self-assessment questionnaire was officially translated and used as the basis for the new tool, which consisted of 110 questions in 11 sections on development and 6 questions on its evaluation. This tool was tested in 15 specialized centers. RESULTS: The study received a high (93.75%) response rate. Overall score ranged from 11% to one perfect 100%; 53.3% of the facilities fell short of the preset qualification standards, while 4 (26.7%) were qualified for level-1 accreditation. Evaluation of the QASR questionnaire for the function of the rehabilitation facilities for the disabled was extremely positive. CONCLUSIONS: The EQUASS assurance-based Greek QASR has received proper attention in its first implementation and it was shown promising to assess the needs of sites that would like to improve their services. The next steps are to establish its validity and reliability so that it can significantly emerge as the standard system for guiding policy in the rehabilitation sector in Greece

Hierarchy and Competition in CSCW applications: Model and case study

CSCW applications need to adapt themselves to the functional and organizational structures of people that use them. However they do not usually support division in groups with a certain hierarchical structure among them. In this paper, we propose and study a theoretical model of groupware appliations that reflects those hierarchical interactions. The proposed model is also intended to evaluate the effects in performance derived from competitive and collaborative relationships among the components of a hierarchy of groups. In order to demonstrate the above ideas, a groupware game, called Alymod, was designed and implemented using a modified version of a well-known CSCW Toolkit, namely Groupkit. Groupkit was modified in order to support group interactions in the same CSCW application. In Alymod, participants compete or collaborate within a hierarchical structure to achieve a common goal (completing gaps in a text, finishing numerical series, resolving University course examinations, etc.).Publicad

Malevolent app pairs: An android permission overpassing scheme

© 2016 Copyright held by the owner/author(s).Portable smart devices potentially store a wealth of information of personal data, making them attractive targets for data exfiltration attacks. Permission based schemes are core security controls for reducing privacy and security risks. In this paper we demonstrate that current permission schemes cannot effectively mitigate risks posed by covert channels. We show that a pair of apps with different permission settings may collude in order to effectively create a state where a union of their permissions is obtained, giving opportunities for leaking sensitive data, whilst keeping the leak potentially unnoticed. We then propose a solution for such attacks