Anisotropic superconducting properties of aligned MgB2 crystallites

Samples of aligned MgB2 crystallites have been prepared, allowing for the first time the direct identification of an upper critical field anisotropy Hc2^{ab}/Hc2^{c}= xi_{ab}/xi_{c} ~ 1.73; with xi_{o,ab} ~ 70 A, xi_{o,c} ~ 40 A, and a mass anisotropy ratio m_{ab}/m_{c} ~ 0.3. A ferromagnetic background signal was identified, possibly related to the raw materials purity.Comment: 4 pages, 4 figures; Revised version to appear in Phys. Rev. Let

Theoretical investigation of moir\'e patterns in quantum images

Moir\'e patterns are produced when two periodic structures with different spatial frequencies are superposed. The transmission of the resulting structure gives rise to spatial beatings which are called moir\'e fringes. In classical optics, the interest in moir\'e fringes comes from the fact that the spatial beating given by the frequency difference gives information about details(high spatial frequency) of a given spatial structure. We show that moir\'e fringes can also arise in the spatial distribution of the coincidence count rate of twin photons from the parametric down-conversion, when spatial structures with different frequencies are placed in the path of each one of the twin beams. In other words,we demonstrate how moir\'e fringes can arise from quantum images

Irreversible magnetization under rotating fields and lock-in effect on ErBa_2Cu_3O_7 single crystal with columnar defects

We have measured the irreversible magnetization M_i of an ErBa_2Cu_3O_7 single crystal with columnar defects (CD), using a technique based on sample rotation under a fixed magnetic field H. This method is valid for samples whose magnetization vector remains perpendicular to the sample surface over a wide angle range - which is the case for platelets and thin films - and presents several advantages over measurements of M_L(H) loops at fixed angles. The resulting M_i(\Theta) curves for several temperatures show a peak in the CD direction at high fields. At lower fields, a very well defined plateau indicative of the vortex lock-in to the CD develops. The H dependence of the lock-in angle \phi_L follows the H^{-1} theoretical prediction, while the temperature dependence is in agreement with entropic smearing effects corresponding to short range vortex-defects interactions.Comment: 7 pages, 6 figures, to be published in Phys. Rev.

Temperature effect on (2+1) experimental Kardar-Parisi-Zhang growth

We report on the effect of substrate temperature (T) on both local structure and long-wavelength fluctuations of polycrystalline CdTe thin films deposited on Si(001). A strong T-dependent mound evolution is observed and explained in terms of the energy barrier to inter-grain diffusion at grain boundaries, as corroborated by Monte Carlo simulations. This leads to transitions from uncorrelated growth to a crossover from random-to-correlated growth and transient anomalous scaling as T increases. Due to these finite-time effects, we were not able to determine the universality class of the system through the critical exponents. Nevertheless, we demonstrate that this can be circumvented by analyzing height, roughness and maximal height distributions, which allow us to prove that CdTe grows asymptotically according to the Kardar-Parisi-Zhang (KPZ) equation in a broad range of T. More important, one finds positive (negative) velocity excess in the growth at low (high) T, indicating that it is possible to control the KPZ non-linearity by adjusting the temperature.Comment: 6 pages, 5 figure

Ionising radiation exposure from medical imaging – A review of Patient's (un) awareness

Introduction: Medical imaging is the main source of artificial radiation exposure. Evidence, however, suggests that patients are poorly informed about radiation exposure when attending diagnostic scans. This review provides an overview of published literature with a focus on nuclear medicine patients on the level of awareness of radiation exposure from diagnostic imaging. Methods: A review of available literature on awareness, knowledge and perception of ionising radiation in medical imaging was conducted. Articles that met the inclusion criteria were subjected to critical appraisal using the Mixed Methods Appraisal Tool. Results: 140 articles identified and screened for eligibility, 24 critically assessed and 4 studies included in synthesis. All studies demonstrated that patients were generally lacking awareness about radiation exposure and highlighted a lack of communication between healthcare professionals and patients with respect to radiation exposure. Conclusion: Studies demonstrate a need to better inform patients about their radiation exposure, and further studies focusing on nuclear medicine patients are particularly warranted. Implications for practice: Adequate and accurate information is crucial to ensure the principle of informed consent is present

Caracterização biometrica de frutos e sementes de matrizes de pracaxi (Pentaclethara macroloba - Wild).

P. macroloba (Fabaceae), conhecida popularmente como Pracaxi, é muito requisitada no mercado de óleos. Foram avaliados 50 frutos de cada uma das quatro matrizes, avaliando-se as seguintes variáveis dos frutos: massa, comprimento, largura, espessura, número total de sementes, número de sementes boas, número de sementes chochas e número de sementes danificadas por insetos. Nas sementes boas, avaliou-se a massa, comprimento, largura e espessura. As medias foram comparadas pelo teste de Tukey ao nível de 5% de probabilidade. Os frutos das quatro matrizes apresentaram massa fresca variando de 76,2 a 89,2g, comprimento de 318,2 a 385,5mm, largura de 41,5 a 46,2mm e espessura de 12,6 a 14,2mm, apresentando em media de 3,18 a 4,36 sementes, sendo de 2,35 a 3,74 sementes boas. As sementes apresentaram massa variando de 4,80 a 6,62g, comprimento de 39,95 a 43,81mm, largura de 27,60 a 31,02mm e espessura de 7,36 a 9,43mm. No geral, a matriz 482 apresentou os melhores resultados com relação à caracterização das sementes, enquanto que a matriz 515 obteve os maiores frutos

Proposta de indicadores para a avaliação da qualidade no ensino superior público: um caso de estudo

A Gestão da Qualidade é um dos factores de maior interesse no campo da gestão estratégica de uma organização. No entanto, embora a Gestão da Qualidade, inicialmente implantada na indústria, tenha hoje boa divulgação no sector de serviços, inclusive na Administração Pública, a mesma não teve avanços tão significativos como no campo industrial. Assim, e dado que a qualidade é uma teoria de gestão que terá de ser, cada vez mais, implementada na Administração Pública Portuguesa, torna-se importante fornecer instrumentos que permitam fazer a sua avaliação. Para tal e com vista a contribuir para o enriquecimento de estudos sobre esta temática, foi propósito deste trabalho apresentar alguns indicadores para avaliar a qualidade de uma Instituição Pública, nomeadamente do Ensino Superior. Teve-se como objecto de estudo a Escola Superior de Tecnologia e de Gestão integrada no Instituto Politécnico de Bragança.Quality Management is one of the main factors within an organization’s strategic management. Despite its initial implementation within the Industrial sector, and its present widespread use in the Services Sector including Public Administration, quality management did not make the same headway within Industry. Since quality is a management theory that must be increasingly implemented in the Portuguese Public Administration, it is important to provide the relevant evaluation tools. For this purpose and to help improve the level of studies in this subject, it is our aim to present through this work, some indicators to measure the quality of a Public Institution such as a College for Higher Education. The subject for this study was the “Escola Superior de Tecnologia e de Gestão” part of the “Instituto Politécnico de Bragança”

Metodología y análisis para evaluar la calidad en la enseñanza superior pública: un caso de estudio

La Gestión de la Calidad es uno de los factores de mayor interés dentro del campo de la gestión estratégica de una organización. Sin embargo, aunque la Gestión de la Calidad, inicialmente implementada en la industria, tiene hoy una buena divulgación en el sector de los servicios, incluyendo la Administración Pública, no ha presentado avances tan significativos como en el campo industrial. De este modo, y dado que la calidad es una teoría de gestión que deberá ser, cada vez más, implantada en la Administración Pública Portuguesa, resulta necesario facilitar herramientas que permitan llevar a cabo su evaluación. Así, con vistas a contribuir al enriquecimiento de los estudios sobre este tema, el propósito del presente trabajo es presentar algunos indicadores capaces de evaluar la calidad de una Institución Pública de la Enseñanza Superior. Se tomó como objeto del estudio la Escola Superior de Tecnologia e de Gestão del Instituto Politécnico de Bragança.Quality Management is one of the main factors within an organization’s strategic management. Despite its initial implementation within the Industrial sector, and its present widespread use in the Services Sector including Public Administration, quality management did not make the same headway within Industry. Since quality is a management theory that must be increasingly implemented in the Portuguese Public Administration, it is important to provide the relevant evaluation tools. For this purpose and to help improve the level of studies in this subject, it is our aim to present through this work, some indicators to measure the quality of a Public Institution such as a College for Higher Education. The subject for this study was the “Escola Superior de Tecnologia e de Gestão” part of the “Instituto Politécnico de Bragança”