16,794 research outputs found
Suppression of two-bounce windows in kink-antikink collisions
We consider a class of topological defects in -dimensions with a
deformed kink structure whose stability analysis leads to a
Schr\"odinger-like equation with a zero-mode and at least one vibrational
(shape) mode. We are interested in the dynamics of kink-antikink collisions,
focusing on the structure of two-bounce windows. For small deformation and for
one or two vibrational modes, the observed two-bounce windows are explained by
the standard mechanism of a resonant effect between the first vibrational and
the translational modes. With the increasing of the deformation, the effect of
the appearance of more than one vibrational mode is the gradual disappearance
of the initial two-bounce windows. The total suppression of two-bounce windows
even with the presence of a vibrational mode offers a counterexample from what
expected from the standard mechanism. For even larger deformation, some
two-bounce windows reappear, but with a non-standard structure.Comment: 13 pages, 6 figure
The Efficiency of Gravitational Bremsstrahlung Production in the Collision of Two Schwarzschild Black Holes
We examine the efficiency of gravitational bremsstrahlung production in the
process of head-on collision of two boosted Schwarzschild black holes. We
constructed initial data for the characteristic initial value problem in
Robinson-Trautman spacetimes, that represent two instantaneously stationary
Schwarzschild black holes in motion towards each other with the same velocity.
The Robinson-Trautman equation was integrated for these initial data using a
numerical code based on the Galerkin method. The final resulting configuration
is a boosted black hole with Bondi mass greater than the sum of the individual
mass of each initial black hole. Two relevant aspects of the process are
presented. The first relates the efficiency of the energy extraction
by gravitational wave emission to the mass of the final black hole. This
relation is fitted by a distribution function of non-extensive thermostatistics
with entropic parameter ; the result extends and validates
analysis based on the linearized theory of gravitational wave emission. The
second is a typical bremsstrahlung angular pattern in the early period of
emission at the wave zone, a consequence of the deceleration of the black holes
as they coalesce; this pattern evolves to a quadrupole form for later times.Comment: 16 pages, 4 figures, to appear in Int. J. Modern Phys. D (2008
Universal features and tail analysis of the order-parameter distribution of the two-dimensional Ising model: An entropic sampling Monte Carlo study
We present a numerical study of the order-parameter probability density
function (PDF) of the square Ising model for lattices with linear sizes
. A recent efficient entropic sampling scheme, combining the
Wang-Landau and broad histogram methods and based on the high-levels of the
Wang-Landau process in dominant energy subspaces is employed. We find that for
large lattices there exists a stable window of the scaled order-parameter in
which the full ansatz including the pre-exponential factor for the tail regime
of the universal PDF is well obeyed. This window is used to estimate the
equation of state exponent and to observe the behavior of the universal
constants implicit in the functional form of the universal PDF. The probability
densities are used to estimate the universal Privman-Fisher coefficient and to
investigate whether one could obtain reliable estimates of the universal
constants controlling the asymptotic behavior of the tail regime.Comment: 24 pages, 5 figure
Magnetically controlled exciton transfer in hybrid quantum dot-quantum well nanostructures
A magnetophotoluminescence study of the carrier transfer with hybrid
InAs/GaAs quantum dot(QD)-InGaAs quantum well (QW) structures is carried out
where we observe an unsual dependence of the photoluminescence (PL) on the GaAs
barrier thickness at strong magnetic field and excitation density. For the case
of a thin barrier the QW PL intensity is observed to increase at the expense of
a decrease in the QD PL intensity. This is attributed to changes in the
interplane carrier dynamics in the QW and the wetting layer (WL) resulting from
increasing the magnetic field along with changes in the coupling between QD
excited states and exciton states in the QW and the WL
Comportamento de híbridos de maracujá em relação à verrugose e a virose do endurecimento dos frutos.
A cultura do maracujá vem se expandindo no Brasil e a presença de doenças é um fator limitante. Este trabalho avaliou o comportamento de híbridos obtidos pelo programa de melhoramento do maracujazeiro da Embrapa Mandioca e Fruticultura, em relação às doenças verrugose e endurecimento dos frutos.PDF. 1094
Sincronização de estro em cabras da raça Toggenburg após a utilização de protocolos hormonais de curta, média e longa duração.
Oestrous syncronization in Toggenburg after use of long, médium and short-term protocols
Hepatite E Fulminante numa Mulher Grávida
Hepatitis E is an inflammatory liver disease caused by hepatitis E virus (HEV) infection, which is endemic in China, India, Nepal, and in several Asian and African countries, where the prevalence can be as high as 50%. In non-endemic countries, an increasing number of
non-travel associated HEV has been reported in recent years, particularly in Europe.
The authors describe the clinical case of a puerperal 24-year-old woman from Pakistan admitted
to our Tertiary Care Medical Center with acute hepatic failure developed during the third trimester of her pregnancy. She was icteric with grade III encephalopathy and hypothermia. Laboratory values showed significant AST, ALT and LDH elevations of twelve times the upper normal limit, and total bilirubin was significantly elevated (41.20 mg/dL). Prothrombin time was
prolonged (4 s) and factor V activity was diminished (15.1%). Extracorporeal albumin dialysis was initiated, but clinical deterioration occurred within 48 h, so she underwent OLT at day 4 post-admission.
Severe forms of HEV are known to be more pronounced in pregnant women. Even though
most of the described cases of acute hepatic failure associated to HEV during pregnancy had a favorable clinical course, some cases of fulminant liver failure and death are described. It is unknown whether liver transplant outcomes in this setting are different from other causes of
acute liver failure. To our knowledge, this is the first case report in Portugal from a pregnant woman who developed hepatic failure due to fulminant hepatitis E that underwent successful liver transplantation
A timeband framework for modelling real-time systems
Complex real-time systems must integrate physical processes with digital control, human operation and organisational structures. New scientific foundations are required for specifying, designing and implementing these systems. One key challenge is to cope with the wide range of time scales and dynamics inherent in such systems. To exploit the unique properties of time, with the aim of producing more dependable computer-based systems, it is desirable to explicitly identify distinct time bands in which the system is situated. Such a framework enables the temporal properties and associated dynamic behaviour of existing systems to be described and the requirements for new or modified systems to be specified. A system model based on a finite set of distinct time bands is motivated and developed in this paper
Efeito de diferentes dosagens de nitrogênio em aspectos morfométricos do pulgão-gigante-do-pínus Cinara atlantica (Hemiptera:aphididae) criado em Pinus taeda.
EVINCI. Resumo 018
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