793 resultados para current mirrors
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The links between gender, sex and sexuality and their relevance are theoretically and politically problematic (Richardson, 2007). One of the difficulties in understanding their interconnections is that these terms are often used differently and ambiguously by different authors (and even by the same authors). This article reports the results of an analysis of the articles published in open access communication journals with known impact factor, edited in Portugal and published between 2005 and 2012. The diverse conceptualisations of those three basic concepts and of their (inter)relationships within communication research are identified. The complexity and the intricate (and often implicit) nature of both the meanings of these categories and their relationships underlie and justify our attention and further research. What the findings suggest about the current communication research into gender issues published in the two journals surveyed is that the ‘Gender differences discourse’ (Sunderland, 2004) is the most pervasive discourse (also) in academic practice. Additionally, they show that gender and sex are mainly taken for a fact, not a question that is worth being studied. The editors of these journals, as well as the scholars submitting manuscripts, need to be more aware of the traditional nature of the theoretical and methodological choices that they make regarding gender- and sex-related issues, as well as of the relative lack of attention to sexuality as a research subject.
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Mycotoxins are secondary metabolites produced by filamentous fungi that are toxic for humans and animals in small amounts and that are found worldwide in a large number of agricultural commodities. They are usually ingested involuntarily, when contaminated plant products are consumed, and represent a great risk for public health. Therefore, governments throughout the world have imposed strict legal limits for their levels in food and feed products in order to reduce potential health risks for consumers. Despite of its ubiquity, the mycotoxin problem is mainly dependent on regional factors, such as the mycotoxigenic characteristics of the local mycoflora, the local climate conditions, and the local agricultural practices. For this reason, a constant vigilance from local governmental food safety agencies and from the local researcher community is needed. This communication will review the current situation on the occurrence of mycotoxigenic fungi in some Portuguese cultures, such as wine grapes, corn and dried fruits. Particular attention will be given to the incidence of mycotoxigenic Aspergillus strains in those cultures and to the levels of ochratoxin A, aflatoxins, cyclopiazonic acid and fumonisin B2 produced. Data will be discussed taking into account the geographical origin of the isolates and the particular climate conditions of each sampling region. An updated review on the levels of the main mycotoxins found in local products and in imported commodities will also be presented.
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Objective: To test the potential mediation effect of psychosomatic symptoms on the relationship between parents' history of childhood physical victimization and current risk for child physical maltreatment. Methods: Data from the Portuguese National Representative Study of Psychosocial Context of Child Abuse and Neglect were used. Nine-hundred and twenty-four parents completed the Childhood History Questionnaire, the Psychosomatic Scale of the Brief Symptom Inventory, and the Child Abuse Potential Inventory. Results: Mediation analysis revealed that the total effect of the childhood physical victimization on child maltreatment risk was significant. The results showed that the direct effect from the parents' history of childhood physical victimization to their current maltreatment risk was still significant once parents' psychosomatic symptoms were added to the model, indicating that the increase in psychosomatic symptomatology mediated in part the increase of parents' current child maltreatment risk. Discussion: The mediation analysis showed parents' psychosomatic symptomatology as a causal pathway through which parents' childhood history of physical victimization exerts its effect on increased of child maltreatment risk. Somatization-related alterations in stress and emotional regulation are discussed as potential theoretical explanation of our findings. A cumulative risk perspective is also discussed in order to elucidate about the mechanisms that contribute for the intergenerational continuity of child physical maltreatment.
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This paper presents a model predictive current control applied to a proposed single-phase five-level active rectifier (FLAR). This current control strategy uses the discrete-time nature of the active rectifier to define its state in each sampling interval. Although the switching frequency is not constant, this current control strategy allows to follow the reference with low total harmonic distortion (THDF). The implementation of the active rectifier that was used to obtain the experimental results is described in detail along the paper, presenting the circuit topology, the principle of operation, the power theory, and the current control strategy. The experimental results confirm the robustness and good performance (with low current THDF and controlled output voltage) of the proposed single-phase FLAR operating with model predictive current control.
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The adoption of a sustainable approach to meeting the energy needs of society has recently taken on a more central and urgent place in the minds of many people. There are many reasons for this including ecological, environmental and economic concerns. One particular area where a sustainable approach has become very relevant is in the production of electricity. The contribution of renewable sources to the energy mix supplying the electricity grid is nothing new, but the focus has begun to move away from the more conventional renewable sources such as wind and hydro. The necessity of exploring new and innovative sources of renewable energy is now seen as imperative as the older forms (i.e. hydro) reach the saturation point of their possible exploitation. One such innovative source of energy currently beginning to be utilised in this regard is tidal energy. The purpose of this thesis is to isolate one specific drawback to tidal energy, which could be considered a roadblock to this energy source being a major contributor to the Irish national grid. This drawback presents itself in the inconsistent nature in which a tidal device generates energy over the course of a 24 hour period. This inconsistency of supply can result in the cycling of conventional power plants in order to even out the supply, subsequently leading to additional costs. The thesis includes a review of literature relevant to the area of tidal and other marine energy sources with an emphasis on the state of the art devices currently in development or production. The research carried out included tidal data analysis and manipulation into a model of the power generating potential at specific sites. A solution is then proposed to the drawback of inconsistency of supply, which involves the positioning of various tidal generation installations at specifically selected locations around the Irish coast. The temporal shift achieved in the power supply profiles of the individual sites by locating the installations in the correct locations, successfully produced an overall power supply profile with the smoother curve and a consistent base load energy supply. Some limitations to the method employed were also outlined, and suggestions for further improvements to the method were made.
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There is described data processing at the flaw detector with combined multisectional eddy-current transducer and heterofrequency magnetic field. The application of this method for detecting flaws in rods and pipes under the conditions of significant transverse displacements is described.
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n.s. no.67(1992)
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The lesser grison (Galictis cuja) is one of the least-known mustelids in the Neotropics, despite its broad range across South America. This study aimed to explore current knowledge of the distribution of the species to identify gaps in knowledge and anticipate its full geographic distribution. Eighty-nine articles have mentioned G. cuja since 1969, but only 13 focused on the species. We generated a detailed model of the species' potential distribution that validated previous maps, but with improved detail, supporting previous southernmost records, and providing a means of identifying priority sites for conservation and management of the species.
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This paper analyses the theoretical relevance of the dynamical aspects of growth on the discussion about the observed positive correlation between per capita real income and real exchange rates. With this purpose, we develop a simple exogenous growth model where the internal, external and intertemporal equilibrium conditions of a typical macroeconomic model are imposed; this last one through the inclusion of a balanced growth path for the foreign assets accumulation. The main result under this consideration is that the relationship defended by the Balassa-Samuelson hypothesis is no more so straightforward. In our particular approach, the mentioned bilateral relationship depends on a parameter measuring thriftiness in the economy. Therefore, the probability of ending up with a positive relationship between growth and real exchange rates -as the classical economic theory predicts- will be higher when the economy is able to maintain a minimum saving ratio. Moreover, given that our model considers a simple Keynesian consumption function, some explosive paths can also be possible.
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vegeu resum en el fitxer adjunt a l'inici del treball de recerca
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Pendent
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Biological materials are increasingly used in abdominal surgery for ventral, pelvic and perineal reconstructions, especially in contaminated fields. Future applications are multi-fold and include prevention and one-step closure of infected areas. This includes prevention of abdominal, parastomal and pelvic hernia, but could also include prevention of separation of multiple anastomoses, suture- or staple-lines. Further indications could be a containment of infected and/or inflammatory areas and protection of vital implants such as vascular grafts. Reinforcement patches of high-risk anastomoses or unresectable perforation sites are possibilities at least. Current applications are based mostly on case series and better data is urgently needed. Clinical benefits need to be assessed in prospective studies to provide reliable proof of efficacy with a sufficient follow-up. Only superior results compared with standard treatment will justify the higher costs of these materials. To date, the use of biological materials is not standard and applications should be limited to case-by-case decision.