12,589 research outputs found
CompetĂȘncias docentes e o perfil profissional dos professores
A razĂŁo essencial de instituir um perfil profissional do professor Ă© um exercĂcio fundamental de sistematização de competĂȘncias docentes que o professor deve revelar para garantir a todos uma boa educação. Melhor do que definir o professor Ă© necessĂĄrio, antes, caracterizĂĄ-lo tendo por base algumas qualidades globais que os ditos bons professores devem possuir, para alĂ©m de outras caracterĂsticas mais especĂficas a que a especialização conduz, de acordo com os diferentes nĂveis de ensino. Uma anĂĄlise mais detalhada da atividade docente revela que qualquer experiĂȘncia de ensino e aprendizagem Ă© de natureza complexa, envolve diversos aspetos que lidam com ĂĄreas de conhecimento tĂŁo diversas como a sociologia, a psicologia, a epistemologia, a biologia, para alĂ©m de outras mais comummente identificĂĄveis com a função de professor, como a pedagogia e a didĂĄtica, o conhecimento curricular. O professor interatua num cenĂĄrio psicossocial dinĂąmico, caracterizado pela mĂșltipla influĂȘncia de diversos fatores e condiçÔes, tanto internos como externos Ă sala de aula e Ă prĂłpria escola. Queremos assim discutir, entre outros aspetos relacionados com competĂȘncias docentes, uma proposta de perfil profissional dos professores que propĂ”e trĂȘs nĂșcleos de competĂȘncias â 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 atravĂ©s da FCT (Fundação para a CiĂȘncia e a Tecnologia) e cofinanciado pelo Fundo Europeu de Desenvolvimento Regional (FEDER) atravĂ©s do COMPETE 2020 â Programa Operacional Competitividade e Internacionalização (POCI) no Ăąmbito do CIEC (Centro de Investigação em Estudos da Criança, da Universidade do Minho) com a referĂȘncia 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
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
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
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
Why are some prices stickier than others? Firm-data evidence on price adjustment lags
Infrequent price changes at the firm level are now well documented in the literature. However, a number of issues remain partly unaddressed. This paper contributes to the literature on price stickiness by investigating the lags of price adjustments to different types of shocks. We find that adjustment lags to cost and demand shocks vary with firm characteristics, namely the firmâs cost structure, the type of pricing policy, and the type of good. We also document that firms react asymmetrically to demand and cost shocks, as well as to positive and negative shocks, and that the degree and direction of the asymmetry varies across firms. JEL Classification: C41, D40, E31Firm heterogeneity, Panel-ordered probit, real rigidities, survey data
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