Geometric conditions for regularity in a time-minimum problem with constant dynamics

Continuing the earlier research on local well-posedness of a time-minimum problem associated to a closed target set C in a Hilbert space H and a convex constant dynamics F we study the Lipschitz (or, in general, Hölder) regularity of the (unique) point in C achieved from x for a minimal time. As a consequence, smoothness of the value function is proved, and an explicit formula for its derivative is given

Back to basics: Data revisions

With few exceptions, most economic data undergo revisions. Although frequently neglected, data revisions may have implications, not only for economic analysis, but also for policy decisions, as revisions may alter current assessment and forecasts of economic developments. In this paper, we reassess data revisions analysis and its impact on forecasting, presenting an encompassing and unified perspective on this subject. For this purpose, we built a real-time database for Portuguese exports and imports of goods. We present a broad set of the measures typically used to gauge revisions and add to this discussion by clarifying the relations between revisions to deferent types of series (for example, revisions to month-on-month and year-on-year rates of change). Furthermore, regarding the (un)predictability of revisions, we suggest an alternative testing approach. The key feature of this approach is that it takes into account both in-sample and out-of-sample performances. We also discuss the impact of revisions on forecasting, focusing on short-term forecasting of first releases. Even though not accounting for data revision implications can lead to suboptimal results, our findings reinforce the need for a case by case analysis.

The effects of low-cost countries on Portuguese manufacturing import prices

This paper estimates the direct effect of low-cost countries on Portuguese manufacturing import prices, using detailed data both by product and by geographical market for the period 1997-2006. The results point to a negative but modest direct effect when compared with studies available for other countries. This is understandable given the lower share of low-cost countries in Portuguese imports. However, besides this direct effect, import prices were influenced by several other factors, some also related to the increasing presence of low-cost countries in international markets. Overall, this lower direct effect was not reflected in a differentiated evolution of manufacturing import prices in Portugal as its evolution was very close to the average of the euro area countries

What is behind the recent evolution of Portuguese terms of trade?

This paper analyses the evolution of Portuguese terms of trade over the last decades. Firstly, their evolution is described: (i) terms of trade registered an upward trend since the second half of the 80s, after the apparent stability observed since 1950; (ii) this was a generalized phenomenon across OECD countries; (iii) and it was specially linked to a very contained evolution of import prices. Secondly, terms of trade are broken down by groups of products, and their evolution is decomposed into two components. The first component results from differences in the composition of import and export baskets of goods (inter-sector specialization), while the second emerges from deviations from the law of one price in each sector (intra-sector segmentation). The results show that terms of trade developments were dominated by the specialization effects related to the evolution of oil prices. Excluding energy and focusing in the manufactured goods, the increase in terms of trade is strongly connected with the positive evolution of relative prices inside each sector, in particular in the usually designated traditional sectors: textiles, clothing and footwear. The effects of globalization on import prices and the structural changes in those manufacturing sectors in Portugal are pointed out as explanations for this phenomenon.

The role of iron related gene variants in liver disease severity and iron metabolism parameters in chronic hepatitis C patients treated with direct-acting antivirals

Chronic hepatitis C (CHC) is usually associated with iron overload, which may modulate the severity of liver disease. Direct-acting antivirals (DAAs) have made HCV treatment faster and more efficient. However, little is known about their effect on liver disease severity and iron metabolism disruption. This study aimed to evaluate the role of iron related gene variants in liver disease severity and iron status associated parameters in CHC patients treated with DAAs. A group of 118 out of 255 CHC patients (49±12 years) was treated with DAAs and clinical evaluation was performed after 3 to 6 months. Liver fibrosis stage was assessed by FibroScan and the following iron status parameters were evaluated: serum iron (Fe), ferritin (FT), transferrin (TF), transferrin saturation (TFS) and haptoglobin (Hp). HFE common variants (H63D and C282Y) were analysed by PCR-RFLP and the TF_rs3811647 by Sanger sequencing. Statistical analysis was performed using SPSS 23.0. Before DAAs treatment, patients with higher fibrosis stage (F3/4) showed significantly higher Fe, FT and TF, and lower Hp (p=0.030; p=0.026; p=0.025; p=0.048). We found higher Fe, TFS and FT in patients HFE_CY or YY (p=0.008; p=0.003; p=0.002) and higher TF in patients TF_rs3811647_GA or AA (p=0.029). After DAAs treatment, patients presented: i) an improvement of liver fibrosis showed by a higher frequency of patients with lower fibrosis stage (F1/2) (p<0.001); and ii) an improvement of iron status revealed by lower Fe, TFS and FT (p=0.007; p=0.048; p<0.001) and higher Hp (p=0.001). We observed that only in patients HFE_CC and HFE_HD or DD, TF decreased after treatment (p=0.028; p=0.012). In these same patients and in those TF_rs3811647_GG or GA, Hp increased (p=0.003; p=0.006) after antiviral treatment. Specific genetic variants in iron related genes may have a relevant role in the predisposition for severe liver disease in CHC patients before DAAs treatment, and in the improvement of iron status after HCV clearance.FCT PDE/BDE/114585/2016 and CENCinfo:eu-repo/semantics/publishedVersio

Desenvolver o conhecimento para ensinar matemática na interação entre contextos formais e não formais

A prática de ensino supervisionada ocupa um tempo privilegiado na formação para o ensino da matemática, promovendo o desenvolvimento de competências associadas å profissão docente, mormente aquelas que serão indispensáveis para a formação de futuros cidadãos responsáveis, ativos e implicados na construção de uma sociedade da qual a matemática é parte indissociável. Para tal, a escola deve ser uma instituição aberta å comunidade, em sintonia com a realidade, renovadora, capaz de proporcionar bem-estar pessoal, físico e social aos jovens e prepará-los harmoniosamente para o futuro. Naturalmente que, se os estagiários não experienciarem situações de planificação, implementação e avaliação de percursos de ensino e aprendizagem e a construção de recursos didáticos ajustados ao ensino de conteúdos curriculares em contextos não formais, fica dificultada a ação de futuros professores no sentido da abertura da escola comunidade e ao meio envolvente. Com o estudo aqui apresentado, sustentado nas premissas e na problemática expostas, propusemo-nos desenvolver e avaliar uma estratégia formativa que proporcionasse aos nossos estagiários a oportunidade de se iniciarem no ensino da matemática, numa perspetiva integradora com outras áreas do currículo do Iº CEB, na interação entre contextos formais e não formais. Os resultados, ao longo dos últimos três anos têm sido muito positivos.Abstract - The supervised teaching practice occupies a privileged time in the training for teaching mathematics, promoting the development of skills associated with teaching profession, especially those that will be essential for the education of future citizens, responsible, active and engaged in building a society in which mathematics is an integral part. To this end, the school should be an open institution to the community, in tune with the surrounding reality, renewing, capable of providing personal, physical and social well-being of young people and prepare them harmoniously for the future. Of course, if trainees have not experience in practice teaching, planning situations, implementation and evaluation of teaching and learning routes and the construction of teaching resources adjusted to the teaching of curricular contents in non-formal contexts, is hampered their action as future teachers opening the school to the community and the environment. With this study, based on presented assumptions and problematic, we took as objective to develop and evaluate a training strategy that gives to our trainees the opportunity to engage in mathematics teaching in non-formal contexts. The results over the last three years have been very positive

Household wealth in Portugal: 1980-2004

The main objective of this paper is to estimate and analyse a relatively long and homogeneous time series (from 1980 onward) on the wealth of households in Portugal. Wealth components covered are financial wealth (financial assets and liabilities) and the housing component of non-financial wealth. We then analyse the results, in terms of developments over the twenty five years under review. For a more recent period, some international comparisons are made, focusing on trends and changes in composition of wealth.