Current density mapping approach for design of clinical magnetic resonance imaging magnets

Novel current density mapping (CDM) schemes are developed for the design of new actively shielded, clinical magnetic resonance imaging (MRI) magnets. This is an extended inverse method in which the entire potential solution space for the superconductors has been considered, rather than single current density layers. The solution provides an insight into the required superconducting coil pattern for a desired magnet configuration. This information is then used as an initial set of parameters for the magnet structure, and a previously developed hybrid numerical optimization technique is used to obtain the final geometry of the magnet. The CDM scheme is applied to the design of compact symmetric, asymmetric, and open architecture 1.0-1.5 T MRI magnet systems of novel geometry and utility. A new symmetric 1.0-T system that is just I m in length with a full 50-cm diameter of the active, or sensitive, volume (DSV) is detailed, as well as an asymmetric system in which a 50-cm DSV begins just 14 cm from the end of the coil structure. Finally a 1.0-T open magnet system with a full 50-cm DSV is presented. These new designs provide clinically useful homogeneous regions and have appropriately restricted stray fields but, in some of the designs, the DSV is much closer to the end of the magnet system than in conventional designs. These new designs have the potential to reduce patient claustrophobia and improve physician access to patients undergoing scans. (C) 2002 Wiley Periodicals, Inc.

The effect of water, brine and ethanol flotation on the quality and shelf life of macadamia kernels - 1. Whole kernels

Whole macadamia kernels were immersed in water (specific gravity 1.00 g/cm(3)), brine (SG 1.02 g/cm(3)) and ethanol solution (SG 0.97 g/cm(3)) for 30 or 60 s, re-dried to 1.0-1.5% moisture (wet basis) and stored under vacuum for 0, 4 and 12 months. Immersion in water had no effect on the quality or shelf life of kernels, as measured by sensory evaluation and analysis of the kernel oil. Immersion in brine and ethanol solutions changed the flavour of kernels, but had no effect on shelf life or kernel oil stability over 12 months storage. Water flotation to separate kernels based on differences in oil content is therefore feasible, but microbiological concerns need to be investigated.

Studies on mosquitoes (Diptera: Culicidae) and anthropic environment: 1- Parity of blood seeking Anopheles (Kerteszia) in South-Eastern Brazil

Populations of Anopheles (Kerteszia) were sampled fortnightly over a one-year period (August 1991 to July 1992) at Ribeira Valley, S. Paulo State, Brazil. Indoor and outdoor collections were made on human bait at evening crepuscular period. The Polovodova technique for age grading was applied to 3,501 females of Anopheles cruzii and to 416 females of An. bellator. That sample represented 34.4% of the total number of mosquitoes collected. The most abundant species found was An. cruzii. However, An. bellator showed an endophagy that was almost three times greater than that of An. cruzii. The overall parous rate was 25.4% and uniparity was practically dominant one. A proportion of 26.9% of An. cruzii and 12.0% of An. bellator were found to be uniparous. Only three outdoor females of the former species (0.1%) showed biparity. Parity of An. cruzii was higher in females caught outdoors than in those caught indoors. Nevertheless, 497 nulliparous females examined (417 cruzii and 80 bellator) had ovaries that had advanced to Christophers and Mer stages III to V. These results imply that these females had already practised hematophagy. Relating these results to those from the parous females, a high statistical significance was found, leading to the conclusion that gonothophic discordance is a common pattern among these anophelines. Further, these results obtained with human bait catches strongly suggest that nearly 38.0% of these host-seeking females had already taken at least one previous blood-meal. So it is possible that enough time could thus be available for the plasmodian development in the vectors.

The effect of the angle of incidence on the aqueous corrosion of ion implanted M50 steel substrates

Following work on tantalum and chromium implanted flat M50 steel substrates, this work reports on the electrochemical behaviour of M50 steel implanted with tantalum and chromium and the effect of the angle of incidence. Proposed optimum doses for resistance to chloride attack were based on the interpretation of results obtained during long-term and accelerated electrochemical testing. After dose optimization from the corrosion viewpoint, substrates were implanted at different angles of incidence (15°, 30°, 45°, 60°, 75°, 90°) and their susceptibility to localized corrosion assessed using open-circuit measurements, step by step polarization and cyclic voltammetry at several scan rates (5–50 mV s-1). Results showed, for tantalum implanted samples, an ennoblement of the pitting potential of approximately 0.5 V for an angle of incidence of 90°. A retained dose of 5 × 1016 atoms cm-2 was found by depth profiling with Rutherford backscattering spectrometry. The retained dose decreases rapidly with angle of incidence. The breakdown potential varies roughly linearly with the angle of incidence up to 30° falling fast to reach -0.1 V (vs. a saturated calomel electrode (SCE)) for 15°. Chromium was found to behave differently. Maximum corrosion resistance was found for angles of 45°–60° according to current densities and breakdown potentials. Cr+ depth profiles ((p,γ) resonance broadening method), showed that retained doses up to an angle of 60° did not change much from the implanted dose at 90°, 2 × 1017 Cr atoms cm-2. The retained implantation dose for tantalum and chromium was found to follow a (cos θ)8/3 dependence where θ is the angle between the sample normal and the beam direction.

A one-dimensional prescribed curvature equation modeling the corneal shape

We prove existence, uniqueness, and stability of solutions of the prescribed curvature problem (u'/root 1 + u'(2))' = au - b/root 1 + u'(2) in [0, 1], u'(0) = u(1) = 0, for any given a > 0 and b > 0. We also develop a linear monotone iterative scheme for approximating the solution. This equation has been proposed as a model of the corneal shape in the recent paper (Okrasinski and Plociniczak in Nonlinear Anal., Real World Appl. 13:1498-1505, 2012), where a simplified version obtained by partial linearization has been investigated.

Prevalence of syphilis in pregnancy and prenatal syphilis testing in Brazil: Birth in Brazil study

OBJECTIVE Determine the coverage rate of syphilis testing during prenatal care and the prevalence of syphilis in pregnant women in Brazil. METHODS This is a national hospital-based cohort study conducted in Brazil with 23,894 postpartum women between 2011 and 2012. Data were obtained using interviews with postpartum women, hospital records, and prenatal care cards. All postpartum women with a reactive serological test result recorded in the prenatal care card or syphilis diagnosis during hospitalization for childbirth were considered cases of syphilis in pregnancy. The Chi-square test was used for determining the disease prevalence and testing coverage rate by region of residence, self-reported skin color, maternal age, and type of prenatal and child delivery care units. RESULTS Prenatal care covered 98.7% postpartum women. Syphilis testing coverage rate was 89.1% (one test) and 41.2% (two tests), and syphilis prevalence in pregnancy was 1.02% (95%CI 0.84;1.25). A lower prenatal coverage rate was observed among women in the North region, indigenous women, those with less education, and those who received prenatal care in public health care units. A lower testing coverage rate was observed among residents in the North, Northeast, and Midwest regions, among younger and non-white skin-color women, among those with lower education, and those who received prenatal care in public health care units. An increased prevalence of syphilis was observed among women with < 8 years of education (1.74%), who self-reported as black (1.8%) or mixed (1.2%), those who did not receive prenatal care (2.5%), and those attending public (1.37%) or mixed (0.93%) health care units. CONCLUSIONS The estimated prevalence of syphilis in pregnancy was similar to that reported in the last sentinel surveillance study conducted in 2006. There was an improvement in prenatal care and testing coverage rate, and the goals suggested by the World Health Organization were achieved in two regions. Regional and social inequalities in access to health care units, coupled with other gaps in health assistance, have led to the persistence of congenital syphilis as a major public health problem in Brazil.

O teatro como eixo curricular de desenvolvimento de competências no 1.º ciclo

Relatório Final apresentado à Escola Superior de Educação de Lisboa para obtenção de grau de mestre em Ensino no 1º e no 2º Ciclos do Ensino Básico

Self-scheduling and bidding strategies of thermal units with stochastic emission constraints

This paper is on the self-scheduling problem for a thermal power producer taking part in a pool-based electricity market as a price-taker, having bilateral contracts and emission-constrained. An approach based on stochastic mixed-integer linear programming approach is proposed for solving the self-scheduling problem. Uncertainty regarding electricity price is considered through a set of scenarios computed by simulation and scenario-reduction. Thermal units are modelled by variable costs, start-up costs and technical operating constraints, such as: forbidden operating zones, ramp up/down limits and minimum up/down time limits. A requirement on emission allowances to mitigate carbon footprint is modelled by a stochastic constraint. Supply functions for different emission allowance levels are accessed in order to establish the optimal bidding strategy. A case study is presented to illustrate the usefulness and the proficiency of the proposed approach in supporting biding strategies. (C) 2014 Elsevier Ltd. All rights reserved.

HTLV-1/2 seroprevalence and coinfection rate in Brazilian first-time blood donors: an 11-year follow-up

The seroprevalence and geographic distribution of HTLV-1/2 among blood donors are extremely important to transfusion services. We evaluated the seroprevalence of HTLV-1/2 infection among first-time blood donor candidates in Ribeirão Preto city and region. From January 2000 to December 2010, 1,038,489 blood donations were obtained and 301,470 were first-time blood donations. All samples were screened with serological tests for HTLV-1/2 using enzyme immunoassay (EIA). In addition, the frequency of coinfection with hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), Chagas disease (CD) and syphilis was also determined. In-house PCR was used as confirmatory test for HTLV-1/2. A total of 296 (0.1%) first-time donors were serologically reactive for HTLV-1/2. Confirmatory PCR of 63 samples showed that 28 were HTLV-1 positive, 13 HTLV-2 positive, 19 negative and three indeterminate. Regarding HTLV coinfection rates, the most prevalent was with HBV (51.3%) and HCV (35.9%), but coinfection with HIV, CD and syphilis was also detected. The real number of HTLV-infected individual and coinfection rate in the population is underestimated and epidemiological studies like ours are very informative.

Preparation and characterization of microfiltration flat polymeric membranes for biomedical applications

Dissertation presented to Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa for obtaining the master degree in Membrane Engineering

Recommendations for the detection of Leptospira in urine by PCR

In the present study PCR was applied to detect leptospires in human urine. Several approaches for sample processing were evaluated to optimize the detection of leptospires in urine mixed with this bacterium. Furthermore, some changes in the composition of the reaction mix were studied. No amplification was observed in acidic urine, therefore neutralization of the sample immediately after collection is strongly recommended. PBS gave better results than Tris or NaOH as neutralizing reagents. Freezing and thawing of samples before processing yielded negative results. Elimination of epithelial cells, leukocytes and crystals by centrifugation at 3,000 rpm at room temperature increased sensitivity. In addition, both the washing step after collecting leptospires by centrifugation and the inclusion of 0.1% bovine serum albumin in the reaction mix minimized the interference of other inhibitory compounds. These modifications were useful to improve the detection of Leptospira in urine by PCR.

Freqüência das infecções pelo HIV-1, rubéola, sífilis, toxoplasmose, citomegalovírus, herpes simples, hepatite B, hepatite C, doença de Chagas e HTLV I/II em gestantes, do Estado de Mato Grosso do Sul

Objetivou-se avaliar a freqüência das infecções por sífilis, rubéola, hepatite B, hepatite C, toxoplasmose, doença de Chagas, HTLV I/II, herpes simples, HIV-1 e citomegalovírus em gestantes e relacionar a faixa etária das pacientes com a freqüência das infecções. Estudo transversal de 32.512 gestantes submetidas à triagem pré-natal no período de novembro de 2002 a outubro de 2003. As freqüências encontradas foram de 0,2% para infecção pelo vírus HIV-1, 0,03% para rubéola, 0,8% para sífilis, 0,4% para toxoplasmose, 0,05% para infecção aguda pelo citomegalovírus, 0,02% pelo vírus herpes simples, 0,3% para hepatite B (HBsAg), 0,1% para hepatite C, 0,1% para HTLV I/II e 0,1% para doença de Chagas. Houve associação significativa entre faixa etária e infecções por rubéola, citomegalovírus, doença de Chagas e herpes vírus. As freqüências de rubéola, sífilis, toxoplasmose, doença de Chagas e citomegalovírus nas gestantes encontram-se abaixo dos valores descritos na literatura.

Decline in prevalence and asymmetric distribution of human T cell lymphotropic virus 1 and 2 in blood donors, State of Minas Gerais, Brazil, 1993 to 2007

INTRODUCTION: Human T cell lymphotropic virus types 1 and 2 (HTLV-1/2) are endemic in Brazil and are screened for in transfusion services since 1993. This study evaluated the evolution of the prevalence of HTLV-1 and 2 in blood donors of the Hemominas Foundation from 1993 to 2007, and its geographical distribution in State of Minas Gerais, Brazil. METHODS: The Hemominas Foundation is a centralized blood center in Minas Gerais, Brazil. The sources of data were the Hemominas Foundation Technical Bulletin and files from the centralized serological laboratory. Donors were tested in the period using enzyme linked immuno sorbent assays (ELISA), followed by Western blot, when repeatedly reactive. The data were analyzed by EPIINFO 6.2 and TABWIN 3.5 softwares. RESULTS: The average seroprevalence in the period 1993-2007 was 0.1%. A steady decline occurred from 0.4% in 1993 to below 0.1% in 2002 and later, with a transient peak of 0.5% in 1994. HTLV reactivity distribution was asymmetrical in the state, with regions of higher prevalence, interspersed with low prevalence areas. Comparison of positive and negative donors verified that increasing age was proportional to virus positivity. Odds ratio for age ranged from 1.43 (30 to 39 years-old) to 3.09 (50 to 65 years-old). Women had a greater chance of being positive (OR-1.64), as previously described. CONCLUSIONS: Possible explanations for HTLV-1/2 prevalence decline are the exclusion of positive donors from the donor pool, an increase in repeat donors and ELISA test improvement, with reduction in the number of false positive results.

Solving large 0–1 multidimensional knapsack problems by a new simplified binary artificial fish swarm algorithm

The artificial fish swarm algorithm has recently been emerged in continuous global optimization. It uses points of a population in space to identify the position of fish in the school. Many real-world optimization problems are described by 0-1 multidimensional knapsack problems that are NP-hard. In the last decades several exact as well as heuristic methods have been proposed for solving these problems. In this paper, a new simpli ed binary version of the artificial fish swarm algorithm is presented, where a point/ fish is represented by a binary string of 0/1 bits. Trial points are created by using crossover and mutation in the different fi sh behavior that are randomly selected by using two user de ned probability values. In order to make the points feasible the presented algorithm uses a random heuristic drop item procedure followed by an add item procedure aiming to increase the profit throughout the adding of more items in the knapsack. A cyclic reinitialization of 50% of the population, and a simple local search that allows the progress of a small percentage of points towards optimality and after that refines the best point in the population greatly improve the quality of the solutions. The presented method is tested on a set of benchmark instances and a comparison with other methods available in literature is shown. The comparison shows that the proposed method can be an alternative method for solving these problems.

Efeito da adição de Zr no endurecimento de ligas Al-Sc

Dissertação de mestrado integrado em Engenharia de Materiais