Competências docentes e o perfil profissional dos professores

A razão essencial de instituir um perfil profissional do professor é um exercício fundamental de sistematização de competências docentes que o professor deve revelar para garantir a todos uma boa educação. Melhor do que definir o professor é necessário, antes, caracterizá-lo tendo por base algumas qualidades globais que os ditos bons professores devem possuir, para além de outras características mais específicas a que a especialização conduz, de acordo com os diferentes níveis de ensino. Uma análise mais detalhada da atividade docente revela que qualquer experiência de ensino e aprendizagem é de natureza complexa, envolve diversos aspetos que lidam com áreas de conhecimento tão diversas como a sociologia, a psicologia, a epistemologia, a biologia, para além de outras mais comummente identificáveis com a função de professor, como a pedagogia e a didática, o conhecimento curricular. O professor interatua num cenário psicossocial dinâmico, caracterizado pela múltipla influência de diversos fatores e condições, tanto internos como externos à sala de aula e à própria escola. Queremos assim discutir, entre outros aspetos relacionados com competências docentes, uma proposta de perfil profissional dos professores que propõe três núcleos de competências – conhecimentos de base, capacidades de aplicação do conhecimento e responsabilidade profissional.CIEC - Centro de Investigação em Estudos da Criança, IE, UMinho (UI 317 da FCT), Portugal; Fundos Nacionais através da FCT (Fundação para a Ciência e a Tecnologia) e cofinanciado pelo Fundo Europeu de Desenvolvimento Regional (FEDER) através do COMPETE 2020 – Programa Operacional Competitividade e Internacionalização (POCI) no âmbito do CIEC (Centro de Investigação em Estudos da Criança, da Universidade do Minho) com a referência POCI-01-0145-FEDER-007562info:eu-repo/semantics/publishedVersio

TVWS policies to enable efficient spectrum sharing

The transition from analogue to the Digital Terrestrial Television (DTV) in Europe is planned to be completed by the end of the year 2012. The DTV spectrum allocation is such that there are a number of TV channels which cannot be used for additional high power broadcast transmitters due to mutual interference and hence are left unused within a given geographical location, i.e. the TV channels are geographically interleaved. The use of geographically interleaved spectrum provides for the so-called TV white spaces (TVWS) an opportunity for deploying new wireless services. The main objective of this paper is to present the spectrum policies that are suitable for TVWS at European level, identified within the COGEU project. The COGEU project aims the efficient exploitation of the geographical interleaved spectrum (TVWS). COGEU is an ICT collaborative project supported by the European Commission within the 7th Framework Programme. Nine partners from seven EU countries representing academia, research institutes and industry are involved in the project. The COGEU project is a composite of technical, business, and regulatory/policy domains, with the objective of taking advantage of the TV digital switchover by developing cognitive radio systems that leverage the favorable propagation characteristics of the UHF broadcast spectrum through the introduction and promotion of real-time secondary spectrum trading and the creation of new spectrum commons regimes. COGEU will also define new methodologies for compliance testing and certification of TVWS equipment to ensure non-interference coexistence with the DVB-T European standard. The innovation brought by COGEU is the combination of cognitive access to TV white spaces with secondary spectrum trading mechanisms.telecommunications,spectrum management,secondary spectrum market,regulation,TV white spaces,cognitive radio

Measuring the importance of the uniform nonsynchronization hypothesis

In this paper we critically reappraise some measures of the importance of time-dependent price setting rules and propose an alternative way to gauge the significance of this type of price setting behaviour. The merits of the proposed measure are highlighted in an application using micro-data. Our results suggest that a large proportion of price trajectories may be compatible with simple time-dependent price setting mechanisms but the strength of this evidence very much depends on the way that is used to evaluate the importance of this type of behaviour. JEL Classification: D40, E31, L11perfect synchronization, Time-dependent price setting models, uniform staggering

Time or state dependent price setting rules? Evidence from Portuguese micro data

In this paper we analyse the ability of time and state dependent price setting rules to explain durations of price spells or the probability of changing prices. Our results suggest that simple time dependent models cannot be seen as providing a reasonable approximation to the data and that state dependent models are required to fully characterise the price setting behaviour of Portuguese firms. Inflation, the level of economic activity and the magnitude of the last price change emerge as relevant variables affecting the probability of changing prices. Moreover, it is seen that the impact differs for negative and positive values of these covariates. JEL Classification: C41, D40, E31CPI data, Hazard functions, inflation

Exciton Regeneration at Polymeric Semiconductor Heterojunctions

Control of the band-edge offsets at heterojunctions between organic semiconductors allows efficient operation of either photovoltaic or light-emitting diodes. We investigate systems where the exciton is marginally stable against charge separation, and show via E-field-dependent time-resolved photoluminescence spectroscopy that excitons that have undergone charge separation at a heterojunction can be efficiently regenerated. This is because the charge transfer produces a geminate electron-hole pair (separation 2.2-3.1nm) which may collapse into an exciplex and then endothermically (E=100-200meV) back-transfer towards the exciton.Comment: 10 pages, 4 figures. Manuscript in press in Phys. Rev. Let

SHStream: Self-Healing Framework for HTTP Video-Streaming

HTTP video-streaming is leading delivery of video content over the Internet. This phenomenon is explained by the ubiquity of web browsers, the permeability of HTTP traffic and the recent video technologies around HTML5. However, the inclusion of multimedia requests imposes new requirements on web servers due to responses with lifespans that can reach dozens of minutes and timing requirements for data fragments transmitted during the response period. Consequently, web- servers require real-time performance control to avoid playback outages caused by overloading and performance anomalies. We present SHStream , a self-healing framework for web servers delivering video-streaming content that provides (1) load admit- tance to avoid server overloading; (2) prediction of performance anomalies using online data stream learning algorithms; (3) continuous evaluation and selection of the best algorithm for prediction; and (4) proactive recovery by migrating the server to other hosts using container-based virtualization techniques. Evaluation of our framework using several variants of Hoeffding trees and ensemble algorithms showed that with a small number of learning instances, it is possible to achieve approximately 98% of recall and 99% of precision for failure predictions. Additionally, proactive failover can be performed in less than 1 secon

Reboot-based Recovery of Performance Anomalies in Adaptive Bitrate Video-Streaming Services

Performance anomalies represent one common type of failures in Internet servers. Overcoming these failures without introducing server downtimes is of the utmost importance in video-streaming services. These services have large user abandon- ment costs when failures occur after users watch a significant part of a video. Reboot is the most popular and effective technique for overcoming performance anomalies but it takes several minutes from start until the server is warmed-up again to run at its full capacity. During that period, the server is unavailable or provides limited capacity to process end-users’ requests. This paper presents a recovery technique for performance anomalies in HTTP Streaming services, which relies on Container-based Virtualization to implement an efficient multi-phase server reboot technique that minimizes the service downtime. The recovery process includes analysis of variance of request-response times to delimit the server warm-up period, after which the server is running at its full capacity. Experimental results show that the Virtual Container recovery process completes in 72 seconds, which contrasts with the 434 seconds required for full operating system recovery. Both recovery types generate service downtimes imperceptible to end-users