11,477 research outputs found
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
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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”
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