985 research outputs found
Theory of Light Emission in Sonoluminescence as Thermal Radiation
Based on the model proposed by Hilgenfeldt {\it at al.} [Nature {\bf 398},
401 (1999)], we present here a comprehensive theory of thermal radiation in
single-bubble sonoluminescence (SBSL). We first invoke the generalized
Kirchhoff's law to obtain the thermal emissivity from the absorption
cross-section of a multilayered sphere (MLS). A sonoluminescing bubble, whose
internal structure is determined from hydrodynamic simulations, is then
modelled as a MLS and in turn the thermal radiation is evaluated. Numerical
results obtained from simulations for argon bubbles show that our theory
successfully captures the major features observed in SBSL experiments.Comment: 17 pages, 20 figure
Atributos agronômicos de linhagens de arroz vermelho desenvolvidas para o Nordeste.
O objetivo deste trabalho foi avaliar os principais atributos agronômicos de linhagens avançadas de arroz vermelho, nas condições do Nordeste brasileiro
Towards a Realistic Type IIA T^6/Z_4 Orientifold Model with Background Fluxes, Part 1: Moduli Stabilization
We apply the methods of DeWolfe et al. [hep-th/0505160] to a T^6/Z_4
orientifold model. This is the first step in an attempt to build a
phenomenologically interesting meta-stable de Sitter model with small
cosmological constant and standard model gauge groups.Comment: 1+30 pages, 2 figures, LaTeX, v2: minor corrections, stability
analysis of b_a moduli added, refs added, version accepted for publication in
JHE
Soft branes in supersymmetry-breaking backgrounds
We revisit the analysis of effective field theories resulting from
non-supersymmetric perturbations to supersymmetric flux compactifications of
the type-IIB superstring with an eye towards those resulting from the
backreaction of a small number of anti-D3-branes. Independently of the
background, we show that the low-energy Lagrangian describing the fluctuations
of a stack of probe D3-branes exhibits soft supersymmetry breaking, despite
perturbations to marginal operators that were not fully considered in some
previous treatments. We take this as an indication that the breaking of
supersymmetry by anti-D3-branes or other sources may be spontaneous rather than
explicit. In support of this, we consider the action of an anti-D3-brane
probing an otherwise supersymmetric configuration and identify a candidate for
the corresponding goldstino.Comment: 36+5 pages. References added, minor typos correcte
MSSM-like AdS Flux Vacua with Frozen Open-string Moduli
We construct supersymmetric Pati-Salam flux vacua in AdS from intersecting
D6-branes on T^6/(Z_2 x Z_2'). The models constructed have three generations of
MSSM matter plus right-handed neutrinos. Because the cycles wrapped by the
D-branes are rigid there are no extra massless fields in the adjoint
representation, arising as open-string moduli. However, we find that it is
problematic to break the Pati-Salam gauge symmetry to the Standard Model (SM)
while keeping the SM hypercharge massless.Comment: 30 page
Evaluation of performance of sugarcane genotypes inoculated with endophytic diazotropic bacteria.
The present experiment was aimed to evaluate the response of sugarcane varieties inoculated with endophytic diazotrophic bacteria. Sixteen sugarcane varieties were used for three kind of treatrnents (no inoculation and inoculation with 120 kg N/hectare). The inoculant was a mixture of five strains of bacterial species isolated from sugarcane. There were significant differences between genotypes (G) and genotype x treatment interaction (GxT) for ali the traits. The variety SP 71-6949,SP 78-4764and RB 867515 were found responsive to biological nitrogen fixation and can be used in breeding programs which are directed to study and selection of promising genotypes responsible for the biological nitrogen fixation
Entanglement-assisted quantum low-density parity-check codes
This paper develops a general method for constructing entanglement-assisted
quantum low-density parity-check (LDPC) codes, which is based on combinatorial
design theory. Explicit constructions are given for entanglement-assisted
quantum error-correcting codes (EAQECCs) with many desirable properties. These
properties include the requirement of only one initial entanglement bit, high
error correction performance, high rates, and low decoding complexity. The
proposed method produces infinitely many new codes with a wide variety of
parameters and entanglement requirements. Our framework encompasses various
codes including the previously known entanglement-assisted quantum LDPC codes
having the best error correction performance and many new codes with better
block error rates in simulations over the depolarizing channel. We also
determine important parameters of several well-known classes of quantum and
classical LDPC codes for previously unsettled cases.Comment: 20 pages, 5 figures. Final version appearing in Physical Review
Effects of insemination and blood-feeding on locomotor activity of Aedes albopictus and Aedes aegypti (Diptera: Culicidae) females under laboratory conditions
Background\ud
Dengue is an arbovirus disease transmitted by two Aedes mosquitoes: Ae. aegypti and Ae. albopictus. Virgin females of these two species generally show a bimodal and diurnal pattern of activity, with early morning and late afternoon peaks. Although some studies on the flight activity of virgin, inseminated and blood-fed Ae. aegypti females have been carried out under laboratory conditions, little is known about the effects of such physiological states on the locomotor activity of Ae. albopictus and Ae. aegypti females. The aim of this study was to analyze, under laboratory conditions, the effects of insemination and blood-feeding on the locomotor activity of Ae. albopictus and Ae. aegypti females under LD 12:12, at 25°C.\ud
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Methods\ud
Both Ae. albopictus and Ae. aegypti females were obtained from established laboratory colonies. Control groups were represented by virgin/unfed Ae. albopictus and Ae. aegypti females. Experiments were conducted under laboratory conditions, using an activity monitor that registers individual activity every thirty minutes.\ud
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Results\ud
Virgin/unfed Ae. albopictus and Ae. aegypti females showed a diurnal and bimodal pattern of locomotor activity, with peaks at early morning and late afternoon. Insemination and blood-feeding significantly decreased the locomotor activity of Ae. aegypti females, but inseminated/blood-fed Ae. aegypti and Ae. albopictus females showed a similar significant decrease on the locomotor activity compared to virgin/unfed females.\ud
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Conclusions\ud
This study is the first demonstration of the effects of insemination and blood-feeding on the locomotor activity of Ae. albopictus and Ae. aegypti females under artificial conditions. Data suggest that Ae. albopictus and Ae. aegypti females respond in different ways to physiological status changes and such divergence between these two dengue vectors, associated with several ecological differences, could be related to the greater dengue vectorial capacity of Ae. aegypti in Americas in comparison to Ae. albopictus.HHMIFiocruzFaperjCNP
Role of quantum coherence in chromophoric energy transport
The role of quantum coherence and the environment in the dynamics of
excitation energy transfer is not fully understood. In this work, we introduce
the concept of dynamical contributions of various physical processes to the
energy transfer efficiency. We develop two complementary approaches, based on a
Green's function method and energy transfer susceptibilities, and quantify the
importance of the Hamiltonian evolution, phonon-induced decoherence, and
spatial relaxation pathways. We investigate the Fenna-Matthews-Olson protein
complex, where we find a contribution of coherent dynamics of about 10% and of
relaxation of 80%.Comment: 5 pages, 3 figures, included static disorder, correlated environmen
Gaugino Condensation and Nonperturbative Superpotentials in Flux Compactifications
There are two known sources of nonperturbative superpotentials for K\"ahler
moduli in type IIB orientifolds, or F-theory compactifications on Calabi-Yau
fourfolds, with flux: Euclidean brane instantons and low-energy dynamics in D7
brane gauge theories. The first class of effects, Euclidean D3 branes which
lift in M-theory to M5 branes wrapping divisors of arithmetic genus 1 in the
fourfold, is relatively well understood. The second class has been less
explored. In this paper, we consider the explicit example of F-theory on with flux. The fluxes lift the D7 brane matter fields, and stabilize
stacks of D7 branes at loci of enhanced gauge symmetry. The resulting theories
exhibit gaugino condensation, and generate a nonperturbative superpotential for
K\"ahler moduli. We describe how the relevant geometries in general contain
cycles of arithmetic genus (and how divisors can
contribute to the superpotential, in the presence of flux). This second class
of effects is likely to be important in finding even larger classes of models
where the KKLT mechanism of moduli stabilization can be realized. We also
address various claims about the situation for IIB models with a single
K\"ahler modulus.Comment: 24 pages, harvmac, no figures, references adde
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