41,760 research outputs found

    Image Normalization of Wiener-Hopf operators and boundary-transmission value problems for a junction of two half-planes

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    The present paper deals with an application of the image normalization technique for certain classes of Wiener-Hopf operators (WHOs) associated to ill-posed boundary-transmission value problems. We briefly describe the method of normalization and then apply it to boundary-transmission value problems issued from diffraction problems for a junction of two half-planes, which are relevant in mathematical physics applications. We consider different boundary-transmission conditions on the junction of the two semi-infinite half-planes and analyze the not normally solvability of the corresponding operators.Comment: 15 page

    Triangle-Well and Ramp Interactions in One-Dimensional Fluids: A Fully Analytic Exact Solution

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    The exact statistical-mechanical solution for the equilibrium properties, both thermodynamic and structural, of one-dimensional fluids of particles interacting via the triangle-well and the ramp potentials is worked out. In contrast to previous studies, where the radial distribution function g(r)g(r) was obtained numerically from the structure factor by Fourier inversion, we provide a fully analytic representation of g(r)g(r) up to any desired distance. The solution is employed to perform an extensive study of the equation of state, the excess internal energy per particle, the residual multiparticle entropy, the structure factor, the radial distribution function, and the direct correlation function. In addition, scatter plots of the bridge function versus the indirect correlation function are used to gauge the reliability of the hypernetted-chain, Percus--Yevick, and Martynov--Sarkisov closures. Finally, the Fisher--Widom and Widom lines are obtained in the case of the triangle-well model.Comment: 19 pages, 9 figure

    A large scale cascade model in the context of mathematics curriculum reform: Interactive factor of influence of multipliers’ work.

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    This study aims to know the influences identified by the multipliers on their work with schools, in order to understand the development of the cascade model implemented in the context of a Portuguese national large-scale programme for support mathematics teachers in mathematics curriculum change. 80 multipliers were surveyed with an open-ended questionnaire and the data were analysed with an inductive approach. Multipliers revealed they were affected by interrelated factors from different contexts: their colleagues, the scientific commission, the mathematics teachers and their schools and the Minister of Education. This suggests that the cascade model do not develop in a top down way, neither it is bottom up defined. Instead, it accommodates contrasting influences and its dynamics evolves as conditions change

    EU regulation concerning genetically modified products: an issue of food security or a measure of disguised protectionism?

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    The biggest producers and exporters of agricultural products have been adopting the genetic engineering in order to improve the factors productivity and the firms profits In the last decade, the United States of America (US) and the European Union (EU) have established a high divergent regulation on production, distribution and consumption of genetically modified organisms (GMOs). Apparently, the EU's complex legislative framework related to GMOs was intend to satisfy the European consumers which are concerned about food safety and whish to make more informed choice about the food they eat. The aim of this paper is to understand the potential motivations behind the different policies on GM products adopted by US and EU.Genetically Modified Organisms; Consumers preferences; Food security; Technical barriers to trade.

    PNAEQ - 13 years of post-analytical EQAS in Portugal

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    In the last 13 years, PNAEQ provided a specific program on post-analytical phase. In order to raise the offer of schemes in areas like Thrombosis/ Haemostasis, PNAEQ has established a consortium with ECAT Foundation distributing two more schemes: Post- Analytical Platelet Function and Pre- and Post-Analytical in Haemostasis. Furthermore, five of the analytical schemes organized by PNAEQ include a post-analytical interpretation, such as Blood Morphology, Hemoglobinopathies, Hydatidose, Rubella and Toxoplasmosis. The main objective of implementing specific and integrated programs on post-analytical phase is to evaluate the performance of laboratories on these matters in order to improve their quality service. The specific program on post-analytical phase provided by PNAEQ comprises 6 types of surveys: audits (vertical and presential), case simulation, case-study, document evaluation, quality indicators and questionnaires. Each survey represents a different tool to evaluate several items of the post-analytical process (Table 1), as well as the laboratory collaborators involved in each task (Figure 1). The items in evaluation are annually selected in the PNAEQ Working Group on Pre- and Post-Analytical Phase (created in 2015) and in compliance with the Portuguese Legislation and the ISO 15189:2012(E). Since 2007 PNAEQ has distributed 6 types of tools in the Post-Analytical Phase EQA, stabilizing in 3 of them in the last five years: Audits, Case Simulation and Quality Indicators. The participation rate has been increasing since 2015, which can be due to the multiple actions performed by PNAEQ Working Group on Pre- and Post-Analytical Phase. In addition, the Case Simulation surveys are the most participated (74% average) since the participation depends on PNAEQ. For the future, PNAEQ and the Working Group will work on the continuous update of the tools content distributed in each survey according to international references and the experience of other EQA organizers.N/

    Gender, socio-economic status and metabolic syndrome in middle-aged and old adults.

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    BACKGROUND: Studies that addressed social and economic determinants of cardiovascular diseases, consistently showed an increase prevalence of the individual features of metabolic syndrome in the lower socio-economic strata. Thus, this study aimed to evaluate the association between social class and metabolic syndrome in a sample of urban middle-aged and old Portuguese adults. METHODS: We evaluated 1962 subjects (1207 women and 755 men) aged 40 or more years. Marital status, education, occupation, menarche age and height distribution were used as socioeconomic indicators. Metabolic syndrome was defined according to the ATP III, by the presence of at least three of the following characteristics: waist circumference > 102 cm in men and > 88 cm in women; triglycerides > or = 150 mg/dl; HDL cholesterol or = 130/85 mm Hg; and fasting glucose > or = 110 mg/dl. Proportions were compared using the chi square test or Fisher's exact test. Odds ratios (OR) and 95% confidence intervals (95% CI) were computed using unconditional logistic regression to estimate the magnitude of the associations. RESULTS: Metabolic syndrome was significantly more frequent in females (24.9 vs. 17.4, p < 0.001). In females, the odds favoring metabolic syndrome significantly increased with age and in unfavorable social class as described by occupation, and decreased with education level. In males, metabolic syndrome was significantly more frequent in the 60-69 years age class (OR = 1.82; 95%CI: 1.02-3.26) when compared to those in the 40-49 years age class. Concerning other socioeconomic indicators no significant associations were found. CONCLUSION: This study showed that gender influenced the association of socio-economic status indicators with metabolic syndrome. Females in lower social classes, as defined by education and occupational classification, more frequently presented metabolic syndrome, no such association was found in males

    Yes, we fuck! Challenging the misfit sexual body through disabled women’s narratives

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    Southern European society has been described in sociological literature as ableist, patriarchal and male-oriented. Under such conditions, many disabled women face multiple oppressions on grounds of gender, disability, class, age, sexual orientation, ‘race’ and ethnicity. The social construction of the impaired body as passive and dependent is conducive to a process of desexualization, presenting disabled people as inadequate for a full intimate life. The dominant biomedical model reinforces this process. This article draws on selected works in feminist disability studies to argue that rather than a body which is unfit, or does not fit, the ‘misfit’ is instead a cultural failure in accommodating and cherishing diversity. The authors also suggest that the desexualization of disabled women is replicating, as well as resulting from, historical tendencies to dehumanize and infantilize women. The empirical data is drawn from a larger project ‘Disabled Intimacies? Sexual and Reproductive Citizenship of Disabled Women in Portugal’. Biographical narrative interviews with disabled women are analyzed to explore the notion of ‘misfit’ sexual bodies. Theirs are stories of counter-norms and the struggle for sexual fulfilment and recognition. The women’s discussions of sexuality point to a need to change the ways that disability and intimacy are addressed in mainstream scholarly literature, institutions and the state. Narrow, heteronormative and ableist understandings of sexual intercourse and the linear character of mainstream stories of intimacy are shown as hindering the prospect of the recognition of disabled women as sexual citizens

    The Effects of Maize Trade with Malawi on Price Levels in Mozambique: Implications for Trade and Development Policy

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    Resultados das investigações do Departamento de Análise de Políticas MAP-Direcção de Economíafood security, food policy, Mozambique, maize trade, International Relations/Trade, Q18,

    Skewness in Financial Returns: Evidence from the Portuguese Stock Market (in English)

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    This paper addresses the issue of symmetry in financial returns. The return distributions of the major stocks traded on the Portuguese market and included in the PSI-20 Index are examined for periods from four to nine years. The results show that the symmetry of the returns is rejected against several alternative distributions. Statistically significant differences between returns below and above the mean are detected, which provides additional evidence of skewness in the return distributions. In addition, as observed in other studies, it is interesting to note that such results are similar to other low-capitalization and low-volume markets, which also exhibit asymmetric return distributions.stock markets, skewness, financial returns

    Effects of elevated CO2 and nutrients on the community metabolism of a Cymodocea nodosa bed

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    We assessed the combined effects of elevated CO2 and nutrients on the metabolism of a benthic community dominated by the seagrass Cymodocea nodosa (Ucria) Ascherson in a mesocosm experiment. C. nodosa plants and their associated community were exposed to two CO2 levels simulating future (700 ppm, pH 7.84) and current (360 ppm, pH 8.12) conditions, and two nutrient levels (enriched and ambient concentration) in a total of four treatments (-C-N, -C+N, +C-N, +C+N). Net community production (NCP) was estimated from changes in the concentration of dissolved inorganic carbon in the seawater in light incubations using benthic chambers. The variation pattern of NCP with the ordinance was consistent for all treatments. Although differences among treatments were not statistically significant, average NCP values were lowest under CO2 enrichment conditions. NCP was lower at a high CO2 level and ambient nitrogen concentration compared to when nutrient availability was higher, suggesting that the low nutrient availability may modulate the community response to CO2 enrichment. The results obtained suggest that the stimulation of the net community production of C. nodosa by elevated CO2 concentrations may be curtailed by low nutrient availability