5,339 research outputs found
Mechanisms for Spin-Supersolidity in S=1/2 Spin-Dimer Antiferromagnets
Using perturbative expansions and the contractor renormalization (CORE)
algorithm, we obtain effective hard-core bosonic Hamiltonians describing the
low-energy physics of spin-dimer antiferromagnets known to display
supersolid phases under an applied magnetic field. The resulting effective
models are investigated by means of mean-field analysis and quantum Monte Carlo
simulations. A "leapfrog mechanism", through means of which extra singlets
delocalize in a checkerboard-solid environment via correlated hoppings, is
unveiled that accounts for the supersolid behavior.Comment: 12 pages, 10 figure
Astrophysical Neutrino Event Rates and Sensitivity for Neutrino Telescopes
Spectacular processes in astrophysical sites produce high-energy cosmic rays
which are further accelerated by Fermi-shocks into a power-law spectrum. These,
in passing through radiation fields and matter, produce neutrinos. Neutrino
telescopes are designed with large detection volumes to observe such
astrophysical sources. A large volume is necessary because the fluxes and
cross-sections are small. We estimate various telescopes' sensitivities and
expected event rates from astrophysical sources of high-energy neutrinos. We
find that an ideal detector of km^2 incident area can be sensitive to a flux of
neutrinos integrated over energy from 10^5 and 10^{7} GeV as low as 1.3 *
10^(-8) * E^(-2) (GeV/cm^2 s sr) which is three times smaller than the
Waxman-Bachall conservative upper limit on potential neutrino flux. A real
detector will have degraded performance. Detection from known point sources is
possible but unlikely unless there is prior knowledge of the source location
and neutrino arrival time.Comment: Section added +modification
Efeito das mudanças climáticas sobre a duração da fase lagarta do curuquerê-do-algodoeiro no nordeste brasileiro.
Resumo: Este trabalho teve como objetivo avaliar o impacto das mudanças climáticas no desenvolvimento de uma das mais importantes pragas desfolhadoras do algodão no Nordeste brasileiro, o curuquerê-do-algodoeiro Alabama argillacea (Hübner) na fase larval, utilizando Sistema de Informações Geográficas. A ocorrência do curuquerê-do-algodoeiro foi estimada empregando-se o modelo de desenvolvimento proposto por Kasten Junior e Parra (1984). Foram elaborados mapas que simulam a duração em dias da fase larval do inseto para o Nordeste no perÃodo de referência (1961-1990) e nas condições climáticas futuras projetadas pelo IPCC, nos perÃodos de 2011-2040, 2041-2070, 2071-2100, no cenário A2. Os resultados indicam que no futuro, de um modo geral, haverá uma diminuição da duração em dias da fase larval, implicando em aumento nas populações do curuquerê-do-algodoeiro, comparado ao perÃodo de 1961 a 1990 no Nordeste. Abstract: The objective of this study was to evaluate the impact of the climate change on the development of one of the most important cotton leaf defoliator pest in the Brazilian Northeast, the leafworm Alabama argillacea (Hübner) in larval stage, using Geographic Information System. The occurrence of leaf worm on cotton was estimated using the model of development proposed by Kasten Junior and Parra (1984). Maps were prepared to simulate the duration in days of the leafworm on cotton larval stage, to the Northeast in the reference period (1961-1990) and future climate conditions projected by the IPCC for the periods of 2011-2040, 2041-2070, 2071 - 2100, A2 scenario. The results indicate that in the future, generally, there will be a decrease in the duration in days of the larval stage implying the increase of the population of the cotton leafworm compared to the period of 1961 to 1990 in the Northeast region
Análise comparativa de rentabilidade: Brs Platina e Prata Anã.
A banana é a segunda fruta ais produzida e consumida no Brasil, com área colhida de 503 mil hectares e produção de 7,3 milhões de toneladas em 2011 (1). A maior parte do cultivo é realizada em pequenas propriedades. A variedade de maior produção e comercialização no Brasil é a ?Prata Anã?. No entanto, a suscetibilidade à Sigatoka-amarela e ao mal-do-Panamá estimulou a busca por variedades resistentes a tais doenças, resultando na variedade ?BRS Platina?
X, Y and Z States
Many new states in the charmonium mass region were recently discovered by
BaBar, Belle, CLEO-c, CDF, D0, BESIII, LHCb and CMS Collaborations. We use the
QCD Sum Rule approach to study the possible structure of some of these states.Comment: Contribution for the proceedings of the "XII Quark Confinement and
the Hadron Spectrum - CONF12" conferenc
Sistema de controle de pesca de Mato Grosso do Sul SCPESCA/MS 2 - 1995.
Neste documento encontram-se as informacoes coletadas e organizadas pelo Sistema de Controle da Pesca de Mato Grosso do Sul - SCPESCA/MS, para o ano de 1995. Essas informacoes foram obtidas para todo o pescado (profissional e esportivo) oficialmente vistoriado e desembarcado no Estado. Foi registrado um total de 1.399 toneladas de pescado, onde 31,4% correspondem a pesca profissional e a 68,6% a pesca esportiva. As especies mais capturadas foram: pacu (427t), pintado (280t), piavucu (129t), cachara (108t), jau (55t), barbado (50t) e piranha (48t). A contribuicao dos rios mais piscosos foi: Paraguai 53,1%, Miranda 19,8%, Aquidauana 7,1%, Taquari 5,2% e Cuiaba (localmente conhecido como Sao Lourenco) 3,2%. Um total de 43.921 pescadores esprotivos visitaram o Estado, com maior concentracao nos meses de julho a outubro, provenientes, principalmente, de Sao Paulo (71,1%), Parana (11,0%) e Minas Gerais (7,1%). Em mediana, os pescadores profissionais realizaram viagens de pesca com duracao de 1 a 7 dias, capturando entre 36 e 84kg de pescado por viagem; os pescadores esportivos realizaram viagens de pesca com duracao de 4 a 5 dias, capturando entre 20 a 27kg de pescado por viagem.bitstream/item/37438/1/BP14.pd
Evolution of 5-hydroxymethylfurfural (HMF) and furfural (F) in fortified wines submitted to overheating conditions
As furfural (F) and 5-hydroxymethylfurfural (HMF) are essentially formed from sugar dehydration, especially in food submitted to heat, they can be found in beverages, as well as fortified sweet wines. In order to assess the impact of temperature on Madeira winemaking, three traditional varieties of Madeira wines (Malvasia, Sercial and Tinta Negra Mole) were studied to evaluate the F and HMF contents. The wines were produced by two vinification processes, following traditional and modern methodologies, heated at standard conditions (30 °C and 45 °C, for 4 months) and compared with the same wines submitted to overheating conditions (55 °C, for 4 months). The RP-HPLC-DAD methodology used for the control of F and HMF during the process showed no significant changes in the wines maintained at 30 °C (canteiro) and a noticeable but controlled increase in the wines heated at 45 °C (estufagem) where values up to about 150 mg/L of HMF could be found in sweet wines. The strong relation of this compound with the sugar content and baking temperature stood out in the wines submitted to overheating conditions where values higher than 1 g/L could be found for sweeter wines, with HMF level being in general higher than F.
The results clearly suggest that the amount of HMF in these fortified wines can be easily controlled when submitted to adequate conditions of heating during estufagem and storage. Furthermore, different temperatures for the baking of sweet and dry wines may be considered
Neutrino Telescopes' Sensitivity to Dark Matter
The nature of the dark matter of the Universe is yet unknown and most likely
is connected with new physics. The search for its composition is under way
through direct and indirect detection. Fundamental physical aspects such as
energy threshold, geometry and location are taken into account to investigate
proposed neutrino telescopes of km^3 volume sensitivities to dark matter. These
sensitivities are just sufficient to test a few WIMP scenarios. Telescopes of
km^3 volume, such as IceCube, can definitely discover or exclude superheavy (M
> 10^10 GeV) Strong Interacting Massive Particles (Simpzillas). Smaller
neutrino telescopes such as ANTARES, AMANDA-II and NESTOR can probe a large
region of the Simpzilla parameter space.Comment: 28 pages, 9 figure
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