2,299 research outputs found
Study of 9Be+12C elastic scattering at energies near the Coulomb barrier
In this work, angular distribution measurements for the elastic channel were
performed for the 9Be+12C reaction at the energies ELab=13.0, 14.5, 17.3, 19.0
and 21.0 MeV, near the Coulomb barrier. The data have been analyzed in the
framework of the double folding S\~ao Paulo potential. The experimental elastic
scattering angular distributions were well described by the optical potential
at forward angles for all measured energies. However, for the three highest
energies, an enhancement was observed for intermediate and backward angles.
This can be explained by the elastic transfer mechanism.
Keywords: 9Be+12C, Elastic Scattering, S\~aoo Paulo Potential
Influência das variáveis meteorológicas na temperatura da superfície da Caatinga em Petrolina, PE.
A análise da temperatura de um organismo compreende a principal variável utilizada para a compreensão de sua termorregulação. Esta por sua vez, pode variar em função de elementos meteorológicos e principalmente da disponibilidade hídrica do local, sendo um indicador do grau de estresse hídrico da vegetação. O objetivo deste trabalho foi analisar a influencia de variáveis ambientais nos valores da temperatura da superfície da caatinga em Petrolina, PE. Para tanto, realizou-se um experimento em uma área de caatinga preservada pertencente à Embrapa Semiárido, Petrolina ? PE. As medições foram realizadas durante o ano de 2012 por meio de uma torre micrometeorológica de 16m de altura equipada com um sistema de aquisição de dados datalogger. Para determinação da temperatura da superfície utilizou-se o termômetro infravermelho (SI111) instalado a 13,9 metros de altura da superfície do solo. Concomitantemente, foram realizadas medidas dos elementos meteorológicos: temperatura do ar, déficit de pressão de vapor, radiação solar e umidade relativa do ar. Procedeu-se realizando correlações para analisar a influencia de cada variável nos valores médios da temperatura da superfície por meio de regressões e do coeficiente de determinação. Com os resultados observou-se que as variáveis que melhor representaram a temperatura da superfície foram a temperatura do ar e o déficit de pressão de vapor com r² iguais a 0,856 e 0,6327. Essas informações podem ser utilizadas para melhor compreender as respostas dessa área de Caatinga às condições do ambiente, bem como para subsidiar estudos de fluxos de carbono e modelagem climática no Bioma Caatinga
Karyotypic; Characterization of representatives from Melolonthinae (Coleoptera: Scarabaeidae): karyotypic analysis, banding and fluorescent in siyu hybridization (FISH).
The aim study is to investigate the meiotic chromosomes of males of the species Phyllophage (Phytalus) vestita, Phyllophage aff capillata and Lyogenys fuscus using conventional stating, differential chromosome banding techniques and fluorescent in situ hybridization (FISH). the use of these techniques permitted a comparative analysis of the three Melolonthinae species studied
6Li direct breakup lifetimes
alpha-d coincidence data were studied for the 6Li + 59Co reaction at E(lab) =
29.6 MeV. By using a kinematic analysis, it was possible to identify which
process, leading to the same final state, has the major contribution for each
of the selected angular regions. Contributions of the 6Li sequential and direct
breakup to the incomplete fusion/transfer process were discussed by considering
the lifetimes obtained by using a semiclassical approach, for both breakup
components.Comment: 5 pages, 4 figures, Invited Talk (Parrallel Sessions) of A. Szanto de
Toledo, prepared for the Proccedings of the 10th International Conference on
Nucleus-Nucleus Collisions, August 16-21, 2009, Beijing, China; submitted to
Nucl. Phys. A (Proceedings of NN2009
Structural properties of crumpled cream layers
The cream layer is a complex heterogeneous material of biological origin
which forms spontaneously at the air-milk interface. Here, it is studied the
crumpling of a single cream layer packing under its own weight at room
temperature in three-dimensional space. The structure obtained in these
circumstances has low volume fraction and anomalous fractal dimensions. Direct
means and noninvasive NMR imaging technique are used to investigate the
internal and external structure of these systems.Comment: 9 pages, 4 figures, accepted in J. Phys. D: Appl. Phy
Public perceptions of hazards associated with Brazil nuts (Bertholletia excelsa) : evaluation of risk within an European context
One of the most important economic plants of the Amazon is the Brazil nut (Bertholletia
excelsa). Brazil nuts for international trade are mainly obtained from wild collection rather than
from plantations, often cited as one of the most important products of extractive reserves in
Amazonia. The European Commission (2003/493/EC) has imposed strict regulations on the
import from Brazil of Brazil nuts in their shells, as the shells have been found to contain high
levels of aflatoxins, which can lead to liver cancer. This may have a negative impact on the
Brazilian exports of shelled Brazil nuts, due to possible public awareness. The aim of the
present research is to assess public perceptions regarding Brazil nuts and to contrast these
with other nuts in general through the use of the Portuguese version of the Perceived Food
Risk Index (PFRI). A sample of 418 consumers was drawn through a door-to-door interview using a random route walk procedure and following a quota sampling controlled for sex, age and location. Consumers
were asked to choose the most relevant quality and preservation characteristics and to identify
their consumption patterns for Brazil nuts and for nuts in general. Risk perception was
evaluated over ten risk characteristics, for each of the following hazards: i) aflatoxins; ii)
biological contaminants; iii) organoleptic changes; iv) fragments and strange bodies and v)
microbial contamination. Additionally, subjects were asked to rate the probability of each hazard
occurring in Brazil nuts or in nuts in general. Results show high consumptions of nuts in general, and a reduced consumption of Brazil nuts, although with low differences on the dimensions of risk perception. Concluding, this work adds to knowledge about the perceptions of risk connected to Brazil nuts consumption, namely that consumers perceive Brazil nuts as safe as nuts in general
Flat-band quantum communication induced by disorder
We show that a qubit transfer protocol can be realized through a flat band
hosted by a disordered spin-1/2 diamond chain. In the absence of disorder,
the transmission becomes impossible due to the compact localized states forming
the flat band. When off-diagonal disorder is considered, the degeneracy of the
band is preserved but the associated states are no longer confined to the unit
cells. By perturbatively coupling the sender and receiver to the flat band, we
derive a general effective Hamiltonian resembling a star network model with two
hubs. The effective couplings correspond to wavefunctions associated with the
flat-band modes. Specific relationships between these parameters define the
quality of the quantum-state transfer which, in turn, are related to the degree
of localization in the flat band. Our findings establish a framework for
further studies of flat bands in the context of quantum communication.Comment: 7 figures, 8 page
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