Technical Efficiency in Portuguese Dairy Farms

This paper addresses issues related to efficiency measurement from an empirical point of view. A stochastic frontier production model using a translog is estimated for a group of Portuguese dairy farms. Farm level survey data for the period 1988 -2005 is used. Stochastic Frontier estimates address behaviour across all periods so the empirical model allows for time varying efficiency as well as technical change. Previous empirical studies use either the value of production or the quantity of milk produced in a single output framework. The value of production approach bundles together decision regarding the quantity and quality components as well as CAP subsidies. Using both approaches for the same data set produce substantial differences in efficiency measurement. The analysis shows that while farmers are quite efficient maximizing quantity produced they are much less efficient when allowing for quality. Sensitivity of estimates to the heterogeneity of the panel data sample as well as to the specification of the dependent variable is discussed. Average efficiency is 84% which indicates a close proximity to the production frontier for 71% of dairy farms but one can not reject the hypothesis that efficiency is decreasing over time and the rate of technical change is negative and close to 2%.

Singular value demodulation of phase-shifted holograms

We report on phase-shifted holographic interferogram demodulation by singular value decomposition. Numerical processing of optically-acquired interferograms over several modulation periods was performed in two steps : 1- rendering of off-axis complex-valued holograms by Fresnel transformation of the interferograms; 2- eigenvalue spectrum assessment of the lag-covariance matrix of hologram pixels. Experimental results in low-light recording conditions were compared with demodulation by Fourier analysis, in the presence of random phase drifts.Comment: 4 pages, 3 figure

MONETARY POLICY AND EXTERNAL VULNERABILITY IN BRAZIL

This paper analyses monetary policy in Brazil, investigating why interest rates were so high and volatile from 1995 to 1998. We identify in monetary policy an overreaction to external shocks, where exogenous changes in international liquidity triggered sharp movements on domestic interest rates. We also show that the Brazilian policy response to these shocks was far more intense than in Argentina and Mexico. We argue that Brazil was caught in a high interest rates trap, which culminated in a currency crisis in January 1999.

A Kolmogorov-Smirnov test for the molecular clock on Bayesian ensembles of phylogenies

Divergence date estimates are central to understand evolutionary processes and depend, in the case of molecular phylogenies, on tests of molecular clocks. Here we propose two non-parametric tests of strict and relaxed molecular clocks built upon a framework that uses the empirical cumulative distribution (ECD) of branch lengths obtained from an ensemble of Bayesian trees and well known non-parametric (one-sample and two-sample) Kolmogorov-Smirnov (KS) goodness-of-fit test. In the strict clock case, the method consists in using the one-sample Kolmogorov-Smirnov (KS) test to directly test if the phylogeny is clock-like, in other words, if it follows a Poisson law. The ECD is computed from the discretized branch lengths and the parameter $\lambda$ of the expected Poisson distribution is calculated as the average branch length over the ensemble of trees. To compensate for the auto-correlation in the ensemble of trees and pseudo-replication we take advantage of thinning and effective sample size, two features provided by Bayesian inference MCMC samplers. Finally, it is observed that tree topologies with very long or very short branches lead to Poisson mixtures and in this case we propose the use of the two-sample KS test with samples from two continuous branch length distributions, one obtained from an ensemble of clock-constrained trees and the other from an ensemble of unconstrained trees. Moreover, in this second form the test can also be applied to test for relaxed clock models. The use of a statistically equivalent ensemble of phylogenies to obtain the branch lengths ECD, instead of one consensus tree, yields considerable reduction of the effects of small sample size and provides again of power.Comment: 14 pages, 9 figures, 8 tables. Minor revision, additin of a new example and new title. Software: https://github.com/FernandoMarcon/PKS_Test.gi

O reconhecimento dos níveis de competência linguística atribuídos pela FAP à luz dos novos requisitos ICAO

A Organização da Aviação Civil Internacional (ICAO) introduziu recentemente uma alteração ao seu Anexo 1 – Personnel Licensing, estabelecendo a obrigatoriedade de demonstração de um nível de competência mínimo na língua inglesa para os agentes aeronáuticos que, em voos internacionais, têm de efectuar comunicações via rádio. Após décadas de atenção centrada essencialmente na fraseologia, a ICAO vem assim reconhecer a importância vital de um conhecimento mais abrangente da língua normalmente utilizada no contexto aeronáutico internacional. Resultados das investigações efectuadas às causas de diversos acidentes e incidentes registados nos últimos anos apontam para a existência de problemas de comunicação entre tripulações e controladores de tráfego aéreo, devido à fraca competência na língua inglesa. A Força Aérea Portuguesa (FAP) tem vindo a seguir uma política que visa o reconhecimento por entidades civis das competências adquiridas no âmbito militar. Nessa medida, a vasta experiência da FAP no campo da avaliação da competência linguística, através do STANAG 6001, tem aqui uma oportunidade para dar o seu contributo ao prosseguimento dessa política, com evidentes vantagens para a organização, em particular no que se refere ao aumento da segurança de voo. Este trabalho de investigação estabelece uma ligação entre os requisitos linguísticos definidos pela ICAO e o sistema de avaliação da competência linguística utilizado pela FAP, através da construção de uma tabela de equivalências. A aceitação da validade desta tabela pela autoridade nacional competente – o INAC – permitirá o reconhecimento dos níveis de competência linguística atribuídos pela FAP e, consequentemente, a conformidade com a alteração preconizada pela ICAO. Seguindo o método de investigação em ciências sociais de Raymond Quivy, este estudo parte da questão central e faz uma análise do STANAG 6001 e do sistema ICAO, relacionando depois os dois sistemas de avaliação. Por fim, as hipóteses formuladas são verificadas e validadas em função dos resultados obtidos. A principal conclusão deste trabalho reside na validação da tabela de equivalências da competência linguística proposta, abrindo assim caminho ao reconhecimento dos níveis atribuídos pela FAP à luz dos novos requisitos ICAO. Abstract: The International Civil Aviation Organization (ICAO) has recently introduced an amendment to its Annex 1 – Personnel Licensing, establishing that aviation professionals who make radiotelephony communications in international flights shall demonstrate a minimum proficiency level in the English language. After decades of attention mainly dedicated to phraseology, ICAO thus recognizes the vital importance of a more comprehensive approach to the language normally used in the international aviation context. Results of investigations on the causes of several accidents and incidents that took place in the last few years indicate the existence of communication problems between flight crews and air traffic controllers due to lack of proficiency in the English language. The Portuguese Air Force (PRTAF) has been following a policy aimed at the recognition by civilian entities of competences acquired in the military context. In this sense, the vast experience of the PRTAF in the field of language proficiency testing, through STANAG 6001, now has an opportunity to give its contribution to this policy, with obvious advantages for the organization, particularly with regard to an increase in flight safety. This research establishes a connection between the ICAO language proficiency requirements and the language proficiency evaluation system used by the PRTAF, through the development of an equivalence table. The acceptance of the validity of this table by the national competent authority – INAC – will allow for the recognition of the language proficiency levels awarded by the PRTAF and, consequently, the conformity with the ICAO amendment. Following Raymond Quivy’s social science research method, this study starts from the research question and analyses the STANAG 6001 and the ICAO system, relating both systems of language proficiency evaluation. Finally, the hypotheses formulated are verified according to the results obtained. The main conclusion of this research lies in the validation of the language proficiency equivalence table that is proposed, thus making way for the recognition of the levels awarded by the PRTAF in light of the new ICAO requirements

From wholesale energy markets to local flexibility markets: structure, models and operation

Most energy markets (EMs) across Europe are based on a design framework involving day-ahead, intraday, and bilateral markets, operating together with balancing markets. This framework was set out, however, when the vast majority of generation units were controllable and fuel-based. The increasing levels of renewable generation create unique challenges in the operation of EMs. In this context, flexibility markets are starting to be recognized as a promising and powerful tool to adequately valorize demand-side flexibility. This chapter describes the models underlying both centralized and bilateral markets, analyzes the operation of several European markets, introduces some energy management tools, analyzes the pressing issue of flexibility in system operation, and describes various pioneering flexibility platforms.info:eu-repo/semantics/publishedVersio

A continuous-stress tetrahedron for finite strain problems

A finite-strain tetrahedron with continuous stresses is proposed and analyzed. The complete stress tensor is now a nodal tensor degree-of-freedom, in addition to displacement. Specifically, stress conjugate to the relative Green-Lagrange strain is used within the framework of the Hellinger-Reissner variational principle. This is an extension of the Dunham and Pister element to arbitrary constitutive laws and finite strain. To avoid the excessive continuity shortcoming, outer faces can have null stress vectors. The resulting formulation is related to the nonlocal approaches popularized as smoothed finite element formulations. In contrast with smoothed formulations, the interpolation and integration domain is retained. Sparsity is also identical to the classical mixed formulations. When compared with variational multiscale methods, there are no parameters. Very high accuracy is obtained for four-node tetrahedra with incompressibility and bending benchmarks being successfully solved. Although the ad-hoc factor is removed and performance is highly competitive, computational cost is high, as each tetrahedron has 36 degrees-of-freedom. Besides the inf-sup test, four benchmark examples are adopted, with exceptional results in bending and compression with finite strains

A instituição do Espaço Lírico na Narrativa Breve de Domingos Monteiro

A obra de Domingos Monteiro (Barqueiros, Mesão Frio, 06/11/1903 – Lisboa 17/08/1980) não tem merecido por parte da crítica, pelo menos em quantidade, uma atenção homóloga à qualidade estético-literária e axiológica que, apesar de tudo, ensaístas de nomeada lhe reconheceram, alguns ainda em vida do autor. A par desta precariedade, são de realçar, entretanto, os dois trabalhos de maior fôlego, ou de maior abrangência, levados a cabo, em épocas muito diferentes, por Álvaro Ribeiro (1965) e Teresa Seruya (2003), sobre o escritor-jurisconsulto, que também foi historiador, crítico literário, autor de textos doutrinários, membro da Academia das Ciências, diretor de Serviços das Bibliotecas Itinerantes da Fundação Calouste Gulbenkian, entre outras funções de destaque. Domingos Monteiro, apesar de ter feito também incursões pela poesia (de que as primeiras publicações são um fulgurante testemunho: Orações do Crepúsculo, em 1920, e Nau Errante, em 1921 – acervo acrescido mais tarde pelos volumes Evasão e Sonetos, respetivamente em 1953 e 1978), foi sobretudo um prócere no conto e na novela, tendo merecido, por isso, o encómio do professor e escritor Eugénio Lisboa de “um dos maiores ficcionistas de sempre e, seguramente, o maior contista português do século XX”. De facto, o escritor teve outras aventuras genológicas, como o drama A Traição Inverosímil e o romance O Caminho para Lá; no entanto, e como afirmou, em relação a este último volume, Teresa Seruya, “o fôlego romanesco é demasiado exigente para o talento sintético de Domingos Monteiro”. O vetor hermenêutico de que nos ocupamos prende-se, então, com o corpus textual dos Contos e Novelas de Monteiro, materializado em quinze títulos, num total de sessenta histórias, relativamente às quais iremos, como parece razoável, proceder a uma triagem que se revele representativa da tal instituição do espaço lírico que julgamos patente, de forma indelével, em fragmentos textuais diversos. Assim, a nível do espaço, pretendemos, com esta investigação, mostrar como Domingos Monteiro construiu um espaço lírico e poético, em relação ao campo e à cidade do país natal e às altas planícies de Castela, a que não faltam também alusões ao Brasil, a África e a certos países europeus. Nesta perspetiva, é nosso objetivo mostrar como o autor de O Mal e o Bem conseguiu conciliar simultaneamente a sua invulgar capacidade de efabulação com a mestria de transfigurar o real, resultando desta fusão uma liricização, em que a narratividade não se perde e a emotividade flui, ora nas personagens, ora no narrador, que muitas vezes também é personagem. Por outras palavras: talvez a recorrência de certos espaços na narrativa breve de Domingos Monteiro derive de uma intromissão da voz lírica do autor na sua criação ficcional