9,240 research outputs found
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
Gravitational form factors and decoupling in 2D
We calculate and analyse non-local gravitational form factors induced by quantum matter fields in curved two-dimensional space. The calculations are performed for scalars, spinors and massive vectors by means of the covariant heat kernel method up to the second order in the curvature and confirmed using Feynman diagrams. The analysis of the ultraviolet (UV) limit reveals a generalized “running” form of the Polyakov action for a nonminimal scalar field and the usual Polyakov action in the conformally invariant cases. In the infrared (IR) we establish the gravitational decoupling theorem, which can be seen directly from the form factors or from the physical beta function for fields of any spin
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Radiation exposure awareness from patients undergoing nuclear medicine diagnostic 99mTc-MDP bone scans and 2-deoxy-2-(18F) fluoro-D-glucose PET/computed tomography scans
INTRODUCTION: Medical imaging is on average the largest source of artificial radiation exposure worldwide. This study seeks to understand patient's awareness of radiation exposure derived from nuclear medicine diagnostic scans and assess if current information provided by leaflets is adequate.
METHODS: Single-centre cross-sectional questionnaire study applied to bone scan and FDG PET/computed tomography patients, at a nuclear medicine and PET/computed tomography department over a 15-week period in 2018. Questionnaires on dose comparators were designed in collaboration with patients, public, and experts in radiation exposure. Qualitative data were analysed using thematic analysis and quantitative data using SPSS (V. 24).
RESULTS: A total of 102 questionnaires were completed (bone scan = 50; FDG PET/computed tomography = 52). Across both groups, 33/102 (32.4%) patients reported having a reasonable understanding of nuclear medicine and 21/102 (20.6%) reported a reasonable knowledge of ionising radiations. When asked to compare the exposure dose of respective scans with common comparators 8/50 (16%) of bone scan patients and 11/52 (21.2%) FDG PET/computed tomography answered correctly. On leaflet information, 15/85 (17.6%) patients reported the leaflets do not provide enough information on radiation exposure and of these 10/15 (66.7%) commented the leaflets should incorporate more information on radiation exposure dose.
CONCLUSION: More observational and qualitative studies in collaboration with patients are warranted to evaluate patients' understanding and preferences in communication of radiation exposure from nuclear medicine imaging. This will ensure communication tools and guidelines developed to comply with ionising radiation (medical exposure) regulation 2017 are according to patients needs and preferences
Self-consistent Coulomb effects and charge distribution of quantum dot arrays
This paper considers the self-consistent Coulomb interaction within arrays of
self-assembled InAs quantum dots (QDs) which are embedded in a pn structure.
Strong emphasis is being put on the statistical occupation of the electronic QD
states which has to be solved self-consistently with the actual
three-dimensional potential distribution. A model which is based on a Green's
function formalism including screening effects is used to calculate the
interaction of QD carriers within an array of QDs, where screening due to the
inhomogeneous bulk charge distribution is taken into acount. We apply our model
to simulate capacitance-voltage (CV) characteristics of a pn structure with
embedded QDs. Different size distributions of QDs and ensembles of spatially
perodic and randomly distributed arrays of QDs are investigated.Comment: submitted to pr
On the stability around Chariklo and the confinement of its rings
Chariklo has two narrow and dense rings, C1R and C2R, located at 391 km and
405 km, respectively. In the light of new stellar occultation data, we study
the stability around Chariklo. We also analyse three confinement mechanisms, to
prevent the spreading of the rings, based on shepherd satellites in resonance
with the edges of the rings. This study is made through a set of numerical
simulations and the Poincar\'e surface of section technique. From the numerical
simulation results we verify that, from the current parameters referring to the
shape of Chariklo, the inner edge of the stable region is much closer to
Chariklo than the rings. The Poincar\'e surface of sections allow us to
identify the first kind periodic and quasi-periodic orbits, and also the
resonant islands corresponding to the 1:2, 2:5, and 1:3 resonances. We
construct a map of a versus e space which gives the location and width of the
stable region and the 1:2, 2:5, and 1:3 resonances. We found that the first
kind periodic orbits family can be responsible for a stable region whose
location and size meet that of C1R, for specific values of the ring particles'
eccentricities. However, C2R is located in an unstable region if the width of
the ring is assumed to be about 120 m. After analysing different systems we
propose that the best confinement mechanism is composed of three satellites,
two of them shepherding the inner edge of C1R and the outer edge of C2R, while
the third satellite would be trapped in the 1:3 resonance.Comment: Accepted for publication in Astronomy & Astrophysic
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