10,608 research outputs found
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
Amphibia, Hylidae, <i>Bokermannohyla sazimai</i> (Cardoso and Andrade 1982): distribution extension
Fate of the Quasi-condensed State for Bias-driven Hard-Core Bosons in one Dimension
Bosons in one dimension display a phenomenon called quasi-condensation, where
correlations decay in a powerlaw fashion. We study the fate of
quasi-condensation in the non-equilibrium steady-state of a chain of hard-core
bosons coupled to macroscopic leads which are held at different chemical
potentials. It is found that a finite bias destroys the quasi-condensed state
and the critical scaling function of the quasi-condensed fraction, near the
zero bias transition, is determined. Associated critical exponents are
determined and numerically verified. Away from equilibrium, the system exhibits
exponentially decaying correlations that are characterized by a bias-dependent
correlation length that diverges in equilibrium. In addition, power-law
corrections are found, which are characterized by an exponent that depends on
the chain-leads coupling and is non-analytic at zero bias. This
exactly-solvable nonequilibrium strongly-interacting system has the remarkable
property that, the near-equilibrium state at infinitesimal bias, cannot be
obtained within linear response. These results aid in unraveling the intricate
properties spawned by strong interactions once liberated from equilibrium
constraints.Comment: 7 pages, 4 figure
Recommended from our members
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
Disorder effects at low temperatures in La_{0.7-x}Y_{x}Ca_{0.3}MnO_{3} manganites
With the aim of probing the effect of magnetic disorder in the
low-temperature excitations of manganites, specific-heat measurements were
performed in zero field, and in magnetic fields up to 9 T in polycrystalline
samples of La_{0.7-x}Y_{x}Ca_{0.3}MnO_{3}, with Y concentrations x=0, 0.10, and
0.15. Yttrium doping yielded the appearance of a cluster-glass state, giving
rise to unusual low-temperature behavior of the specific-heat. The main feature
observed in the results is a strong enhancement of the specific-heat linear
term, which is interpreted as a direct consequence of magnetic disorder. The
analysis was further corroborated by resistivity measurements in the same
compounds.Comment: 9 pages, 2 figure
Caracterização morfológica da flor do camucamuzeiro.
Trabalhos feitos sobre a biologia floral da flor do camucamuzeiro consideraram a espécie com alogamia facultativa, não obrigatória, aceitando a geitonogamia, podendo ainda ser polinizada pelo vento. Estudos de morfologia floral são utilizados em pesquisas para ajudar na compreensão da relação entre estruturas reprodutivas e os polinizadores, além da diferenciação entre genótipos da mesma espécie. O trabalho teve como objetivo realizar a caracterização morfométrica em flores de camucamuzeiro, visando o estabelecimento de descritores morfológicos para a espécie. O estudo foi realizado em flores de dez progênies estabelecidas no BAG Camu-camu. Foram caracterizadas as seguintes estruturas: número de estames, comprimento do estilete e o comprimento do pedicelo. Houve variação em todas as estruturas florais avaliadas, com destaque para o número de estames. As progênies apresentaram flores com média de 126,8 estames. As matrizes CPATU-05 e CPATU-21 diferiram das demais com 163,1 e 162,1 estames, respectivamente. Para o comprimento do estilete, a progênie CPATU-5 teve a maior média, (1,16 cm). Com relação ao tamanho do pedicelo, a progênie CPATU-20 apresentou flores com a maior média (0,38 cm). A caracterização morfométrica das flores de camucamuzeiro permite a identificação de ampla variabilidade genética entre as progênies estabelecidas no BAG- Camu-camu. O número de estame e o comprimento do estilete podem ser utilizados como descritores morfológicos visando à diferenciação entre acessos de camucamuzeiro.PIBIC-2011
Morfometria de fruto em progênies estabelecidas no BAG-CAMU-CAMU.
O camucamuzeiro é espécie frutífera nativa da Amazônia e sua importância econômica é comprovada pelo fato do fruto conter elevado teor de ácido ascórbico. O trabalho teve como objetivo realizar a morfometria de frutos em 15 progênies de camucamuzeiro estabelecidas no BAG-camucamu. A morfometria foi efetuada com base na amostra de 50 frutos de cada progênie, os quais foram individualmente analisados quanto às seguintes características: massa, comprimento, diâmetro, espessura da casca, número de sementes por fruto, além da porcentagem de polpa, casca e sementes. Os resultados obtidos evidenciaram que os frutos de camu-camu das progênies avaliadas apresentaram massa de 7,37±1,64 g, com mínimo de 4,58 g e máximo de 10,19 g. A progênie CPATU-51 foi a que se destacou em relação ao tamanho dos frutos, com frutos pesando acima de 10 gramas. As médias para o comprimento e diâmetro dos frutos foram de 2,17±0,18 cm e 2,32±0,19 cm, respectivamente. A espessura de casca variou de 0,25 a 0,56 mm com média de 0,34 mm. A caracterização física e composição centesimal dos frutos permitem a identificação de ampla variabilidade genética entre as progênies de Myrciaria dubia estabelecidas no BAG ? Camu-camu.PIBIC-2011
- …