Results of radiation protection programmes on mammography

In this paper, we present the results of mammography quality control tests related to the work with Portuguese mammography equipment, either in conventional or in digital mammography computed radiography, showing the main differences in the tested equipments. Quality control in mammography is a very special area of quality control in radiology, which demands relatively high knowledge on physics. Digital imaging is changing the standards of the radiographic imaging. Regarding mammography, this is yet a controversial issue owing to some limitations of the digital detectors, like the resolution for instance. A complete set of results regarding radiation protection of the patients submitted to mammography diagnosis is presented. A discussion of the quality image parameters and its interpretation in conventional and digital mammography is presented. In conclusion, we present a sample of results that can be considered as characteristics of mammography equipment in Portugal.

Protection against oxidative stress through SUA7/TFIIB regulation in Saccharomyces cerevisiae

The general transcription factor TFIIB, encoded by SUA7 in Saccharomyces cerevisiae, is required for transcription activation but apparently of a specific subset of genes, for example, linked with mitochondrial activity and hence with oxidative environments. Therefore, studying SUA7/TFIIB as a potential target of oxidative stress is fundamental. We found that controlled SUA7 expression under oxidative conditions occurs at transcriptional and mRNA stability levels. Both regulatory events are associated with the transcription activator Yap1 in distinct ways: Yap1 affects SUA7 transcription up regulation in exponentially growing cells facing oxidative signals; the absence of this activator per se contributes to increase SUA7 mRNA stability. However, unlike SUA7 mRNA, TFIIB abundance is not altered on oxidative signals. The biological impact of this preferential regulation of SUA7 mRNA pool is revealed by the partial suppression of cellular oxidative sensitivity by SUA7 overexpression, and supported by the insights on the existence of a novel RNA-binding factor, acting as an oxidative sensor, which regulates mRNA stability. Taken together the results point out a primarily cellular commitment to guarantee SUA7 mRNA levels under oxidative environments.

Diagnóstico de higiene e segurança no trabalho: proposta de medidas correctivas

O trabalho que é de seguida apresentado foi desenvolvido durante o estágio efectuado no Instituto de Desenvolvimento e Inovação Tecnológica (IDIT), tendo em vista a realização de um projecto de fim de Mestrado em Engenharia Química no ramo de Tecnologias de Protecção Ambiental. O projecto teve como principal objectivo a elaboração de um diagnóstico de Segurança, Higiene e Saúde no Trabalho tendo por base as medições de factores de riscos, efectuadas numa empresa pertencente ao sector da alimentação, e o seu respectivo enquadramento legal. A realização deste trabalho consistiu na avaliação de factores físicos e químicos presentes em todas as actividades industriais, que podem constituir riscos para a higiene, saúde e segurança dos trabalhadores. Os factores considerados neste estudo foram: o ruído, a iluminância, as vibrações, o ambiente térmico e os contaminantes químicos. Ao longo do trabalho são apresentados os resultados obtidos nas avaliações efectuadas e a sua análise, que permitiu o conhecimento das condições de trabalho, para as diversas actividades desempenhadas na empresa, revelando as não concordâncias dos factores estudados. Segundo os resultados obtidos conclui-se que a empresa apresenta condições de Higiene, Saúde e Segurança bastantes satisfatórias, apresentando apenas algumas não conformidades, particularmente nos níveis de pressão sonora. No entanto, estas não conformidades podem ser contornadas com a aplicação de medidas correctivas previstas no enquadramento legal que abrange cada factor avaliado. A escassez de tempo não permitiu a elaboração de um diagnóstico de HST completo, uma vez que, uma análise de risco completa necessita de um estudo mais aprofundado na área e uma prática considerável, que não foi possível adquirir até então.

Modelização e análise de desempenho de redes de distribuição mistas

A evolução tecnológica a que se assistiu nas últimas décadas tem sido um dos principais fatores da necessidade de utilização de energia elétrica. Consequentemente, remodelações tanto a nível de equipamentos na rede de distribuição como da qualidade de serviço têm sido determinantes para fazer face a uma evolução crescente do consumo de energia elétrica por parte da sociedade. Esta evolução tem afetado significativamente o desempenho dos sistemas de proteção e automatismos associados, sendo estes cada vez mais fiáveis e proporcionando maior segurança tanto aos ativos da rede como a pessoas. No entanto, esta evolução tem tido também impacto nas linhas de distribuição em média tensão, estando estas a evoluir de rede aérea para linhas mistas de distribuição. As linhas mistas de distribuição têm diferentes desempenhos técnicos e económicos no que respeita aos sistemas de proteção e respetivos automatismos de religação automática. Neste trabalho são analisados alguns parâmetros que têm influência na atuação das proteções e respetivos automatismos de religação.

Ethernet goes real-time: a survey on research and technological developments

Ethernet is the most popular LAN technology. Its low price and robustness, resulting from its wide acceptance and deployment, has created an eagerness to expand its responsibilities to the factory-floor, where real-time requirements are to be fulfilled. However, it is difficult to build a real-time control network using Ethernet, because its MAC protocol, the 1-persistent CSMA/CD protocol with the BEB collision resolution algorithm, has unpredictable delay characteristics. Many anticipate that the recent technological advances in Ethernet such as the emerging Fast/Gigabit Ethernet, micro-segmentation and full-duplex operation using switches will also enable it to support time-critical applications. This technical report provides a comprehensive look at the unpredictability inherent to Ethernet and at recent technological advances towards real-time operation.

Estudo dos sistema de automação da protecção diferencial de linha e comparação direccional

O tema do sistema de automação da protecção diferencial de linha e comparação direccional é merecedor de uma nova abordagem devido às recentes inovações tecnológicas ocorridas desde o aparecimento dos relés digitais e à consequente comunicação entre os sistemas de protecção, em particular na comunicação entre protecções diferenciais de linha. A protecção diferencial de linha apresenta claras vantagens face às protecções actualmente utilizadas para a protecção de linhas de transmissão e distribuição, tais como, Protecção de Máximo Intensidade de Fase, Máximo Intensidade Homopolar Direccionale Protecção de Distância. Contudo, existem alguns problemas associados a este tipo de protecções, nomeadamente na comunicação entre relés. Para automação e comunicação de protecções diferenciais de linhas de transmissão, no caso da ocorrência de defeitos na zona protegida pelo sistema de protecção diferencial foi empregue um método inovador para este tipo de sistema. Uma vez que a eficácia da actuação das protecções diferenciais depende do rigor das variáveis que são necessárias enviar entre protecções que se encontram localizadas em subestações distintas, recorreu-se à utilização de um automatismo para comunicação entre relés suportado pelo desenvolvimento de novos algoritmos para detectar quase instantaneamente um defeito em qualquer zona de protecção de uma linha de transmissão. Estes algoritmos são baseados na Transformada de Park, pelo que, é introduzido um novo conceito neste tipo de protecções. Através destes algoritmos é possível atenuar os problemas associados à protecção diferencial de linha. No sentido de verificar a aplicabilidade destes algoritmos à protecção diferencial de linha são apresentados diversos casos de estudo. Através dos resultados obtidos também foi possível verificar as vantagens associadas à utilização dos algoritmos propostos.

Social protection systems in vulnerable families: their importance for the public health

OBJECTIVE To analyze the effectiveness of the Chilean System of Childhood Welfare in transferring benefits to socially vulnerable families. METHODS A cross-sectional study with a sample of 132 families from the Metropolitan Region, Chile, stratified according to degree of social vulnerability, between September 2011 and January 2012. Semi-structured interviews were conducted with mothers of the studied families in public health facilities or their households. The variables studied were family structure, psychosocial risk in the family context and integrated benefits from the welfare system in families that fulfill the necessary requirements for transfer of benefits. Descriptive statistics to measure location and dispersion were calculated. A binary logistic regression, which accounts for the sample size of the study, was carried out. RESULTS The groups were homogenous regarding family size, the presence of biological father in the household, the number of relatives living in the same dwelling, income generation capacity and the rate of dependency and psychosocial risk (p ≥ 0.05). The transfer of benefits was low in all three groups of the sample (≤ 23.0%). The benefit with the best coverage in the system was the Single Family Subsidy, whose transfer was associated with the size of the family, the presence of relatives in the dwelling, the absence of the father in the household, a high rate of dependency and a high income generation capacity (p ≤ 0.10). CONCLUSIONS The effectiveness of benefit transfer was poor, especially in families that were extremely socially vulnerable. Further explanatory studies of benefit transfers to the vulnerable population, of differing intensity and duration, are required in order to reduce health disparities and inequalities.

Perceptually driven video error protection using a distributed source coding approach

In video communication systems, the video signals are typically compressed and sent to the decoder through an error-prone transmission channel that may corrupt the compressed signal, causing the degradation of the final decoded video quality. In this context, it is possible to enhance the error resilience of typical predictive video coding schemes using as inspiration principles and tools from an alternative video coding approach, the so-called Distributed Video Coding (DVC), based on the Distributed Source Coding (DSC) theory. Further improvements in the decoded video quality after error-prone transmission may also be obtained by considering the perceptual relevance of the video content, as distortions occurring in different regions of a picture have a different impact on the user's final experience. In this context, this paper proposes a Perceptually Driven Error Protection (PDEP) video coding solution that enhances the error resilience of a state-of-the-art H.264/AVC predictive video codec using DSC principles and perceptual considerations. To increase the H.264/AVC error resilience performance, the main technical novelties brought by the proposed video coding solution are: (i) design of an improved compressed domain perceptual classification mechanism; (ii) design of an improved transcoding tool for the DSC-based protection mechanism; and (iii) integration of a perceptual classification mechanism in an H.264/AVC compliant codec with a DSC-based error protection mechanism. The performance results obtained show that the proposed PDEP video codec provides a better performing alternative to traditional error protection video coding schemes, notably Forward Error Correction (FEC)-based schemes. (C) 2013 Elsevier B.V. All rights reserved.

Application of robust fixed point transformations for technological operation of robots

A robot’s drive has to exert appropriate driving forces that can keep its arm and end effector at the proper position, velocity and acceleration, and simultaneously has to compensate for the effects of the contact forces arising between the tool and the workpiece depending on the needs of the actual technological operation. Balancing the effects of a priori unknown external disturbance forces and the inaccuracies of the available dynamic model of the robot is also important. Technological tasks requiring well prescribed end effector trajectories and contact forces simultaneously are challenging control problems that can be tackled in various manners.

Gender and other factors associated with the use of hearing protection devices at work

OBJECTIVE To analyze whether sociodemographic, occupational, and health-related data are associated with the use of hearing protection devices at work, according to gender. METHODS A cross-sectional study was conducted in 2006, using a random sample of 2,429 workers, aged between 18 and 65 years old, from residential sub-areas in Salvador, BA, Northeastern Brazil. Questionnaires were used to obtain sociodemographic, occupational, and health-related data. Workers who reported that they worked in places where they needed to shout in order to be heard were considered to be exposed to noise. Exposed workers were asked whether they used hearing protection devices, and if so, how frequently. Analyses were conducted according to gender, with estimates made about prevalence of the use of hearing protection devices, prevalence ratios, and their respective 95% confidence intervals. RESULTS Twelve percent (12.3%) of study subjects reported that they were exposed to noise while working. Prevalence of the use of hearing protection devices was 59.3% for men and 21.4% for women. Men from higher socioeconomic levels (PR = 1.47; 95%CI 1.14;1.90) and who had previous audiometric tests (PR = 1.47; 95%CI 1.15;1.88) were more likely to use hearing protection devices. For women, greater perceived safety was associated with the use of protection devices (PR = 2.92; 95%CI 1.34;6.34). This perception was specifically related to the presence of supervisors committed to safety (PR = 2.09; 95%CI 1.04;4.21), the existence of clear rules to prevent workplace injuries (PR = 2.81; 95%CI 1.41;5.59), and whether they were informed about workplace safety (PR = 2.42; 95%CI 1.23;4.76). CONCLUSIONS There is a gender bias regarding the use of hearing protection devices that is less favorable to women. The use of such devices among women is positively influenced by their perception of a safe workplace, suggesting that gender should be considered as a factor in hearing conservation programs.

Anti-Corrosion performance of a new silane coating for corrosion protection of AZ31 Magnesium alloy in Hank’s solution

Mg alloys can be used as bioresorsable metallic implants. However, the high corrosion rate of magnesium alloys has limited their biomedical applications. Although Mg ions are essential to the human body, an excess may cause undesirable health effects. Therefore, surface treatments are required to enhance the corrosion resistance of magnesium parts, decreasing its rate to biocompatible levels and allowing its safe application as bioresorbable metallic implants. The application of biocompatible silane coatings is envisaged as a suitable strategy for retarding the corrosion process of magnesium alloys. In the current work, a new glycidoxypropyltrimethoxysilane (GPTMS) based coating was tested on AZ31 magnesium substrates subjected to different surface conditioning procedures before coating deposition. The surface conditioning included a short etching with hydrofluoric acid (HF) or a dc polarisation in alkaline electrolyte. The silane coated samples were immersed in Hank's solution and the protective performance of the coating was studied through electrochemical impedance spectroscopy (EIS). The EIS data was treated by new equivalent circuit models and the results revealed that the surface conditioning process plays a key role in the effectiveness of the silane coating. The HF treated samples led to the highest impedance values and delayed the coating degradation, compared to the mechanically polished samples or to those submitted to dc polarisation.

Protection of interconnected wind turbines against lightning effects: overvoltages and electromagnetic transientes study

This paper is concerned with direct or indirect lightning strokes on wind turbines, studying overvoltages and electromagnetic transients. As wind power generation undergoes rapid growth, lightning damages involving wind turbines have come to be regarded with more attention. With the aim of providing further insights into the lightning protection of wind turbines, describing the transient behavior in an accurate way, the restructured version (RV) of the electromagnetic transients program (EMTP) is used in this paper. A new case study is presented with two interconnected wind turbines, considering a direct lightning stroke to the blade or considering that lightning strikes the soil near a tower. Comprehensive computer simulations with EMTP-RV are presented and conclusions are duly drawn.

Protection of athymic (Nu/Nu) BALB/c mice against Plasmodium berghei by splenocytes from normal (Nu/ +) BALB/c mice

Athymic BALB/c (Nu/Nu) mice died at 7-13 days after inoculation (DAI) of Plasmodium berghei NK65, whereas their heterozygous (Nu/+) littermates died at 7-8 DAI. Nude (Nu/Nu) mice, reconstituted with 2 x 10(7) splenocytes from uninfected heterozygous (Nu/+) littermates at 20 days before parasite inoculation (DBI), died about 2 days earlier than control nude mice; nude mice reconstituted at 10 or 2 DBI lived 2 to 4 days longer than control nudes; and nude mice reconstituted 2 DAI lived even longer and some survived. These findings indicate that P. berghei NK65 induces at least two T-cell dependent immune phenomena, one suppressive and the other stimulatory. Reconstitution of nude mice with T-cells from BALB/c (Nu/+) mice appeared to reduce or bypass suppressive T-cell activities which allowed the formation of a protective immune response by some of the nude mice.

Data analysis applied to the evaluation of a technological nature teaching model as a regional development tool

This paper presents the creation and development of technological schools directly linked to the business community and to higher public education. Establishing themselves as the key interface between the two sectors they make a signigicant contribution by having a greater competitive edge when faced with increasing competition in the tradional markets. The development of new business strategies supported by references of excellence, quality and competitiveness also provides a good link between the estalishment of partnerships aiming at the qualification of education boards at a medium level between the technological school and higher education with a technological foundation. We present a case study as an example depicting the success of Escola Tecnológica de Vale de Cambra.