19,193 research outputs found
Role of Landau-Rabi quantization of electron motion on the crust of magnetars within the nuclear energy density functional theory
Magnetic fields of order G have been measured at the surface of
some neutron stars, and much stronger magnetic fields are expected to be
present in the solid region beneath the surface. The effects of the magnetic
field on the equation of state and on the composition of the crust due to
Landau-Rabi quantization of electron motion are studied. Both the outer and
inner crustal regions are described in a unified and consistent way within the
nuclear-energy density functional theory.Comment: 23 pages, 11 figure
The "zeroth law" of turbulence: Isotropic turbulence simulations revisited
The dimensionless kinetic energy dissipation rate C_epsilon is estimated from
numerical simulations of statistically stationary isotropic box turbulence that
is slightly compressible. The Taylor microscale Reynolds number Re_lambda range
is 20 < Re_lambda < 220 and the statistical stationarity is achieved with a
random phase forcing method. The strong Re_lambda dependence of C_epsilon
abates when Re_lambda approx. 100 after which C_epsilon slowly approaches
approx 0.5 a value slightly different to previously reported simulations but in
good agreement with experimental results. If C_epsilon is estimated at a
specific time step from the time series of the quantities involved it is
necessary to account for the time lag between energy injection and energy
dissipation. Also, the resulting value can differ from the ensemble averaged
value by up to +-30%. This may explain the spread in results from previously
published estimates of C_epsilon.Comment: 7 pages, 7 figures. Submitted to Phys. Rev.
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Lithium and carbon isotopic fractionations between the alteration assemblages of Nakhla and Lafayette
Nakhla and Lafayette delta 7Li values for samples and extracts (4.1-14.2�) are consistent with brine evaporation. Relatively 13C-poor siderite in Lafayette suggests more than one carbon source was sampled
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Separation of Q from carbon in CR meteorites during stepped combustion
Introduction: The nature of the planetary noble gas carrier (Q) in meteorites remains uncertain. It is known that it is likely to be carbonaceous, but represents only a small fraction of the total macromolecular material. Q is oxidisible with nitric and other oxidizing acids. It seems to be partly destroyed with pyridine and may have an organic structure. Previously, we have shown that during parent body thermal metamorphism Q is less affected than the majority of other carbonaceous materials. If organic matter is graphitized, as has happened in the enstatite chondrite parent bodies, Q remains unaffected. In the present study we have found that Q is also separable from the majority of carbon in type 2 and 3 CR chondrites during stepped combustion. It is possible that this is because Q has become encased within the matrix, in contrast to other carbon phases, during parent body metamorphism
Subthreshold characteristics of pentacene field-effect transistors influenced by grain boundaries.
Grain boundaries in polycrystalline pentacene films significantly affect the electrical characteristics of pentacene field-effect transistors (FETs). Upon reversal of the gate voltage sweep direction, pentacene FETs exhibited hysteretic behaviours in the subthreshold region, which was more pronounced for the FET having smaller pentacene grains. No shift in the flat-band voltage of the metal-insulator-semiconductor capacitor elucidates that the observed hysteresis was mainly caused by the influence of localized trap states existing at pentacene grain boundaries. From the results of continuous on/off switching operation of the pentacene FETs, hole depletion during the off period is found to be limited by pentacene grain boundaries. It is suggested that the polycrystalline nature of a pentacene film plays an important role on the dynamic characteristics of pentacene FETs
Decision Making: The Neuroethological Turn
Neuroeconomics applies models from economics and psychology to inform neurobiological studies of choice. This approach has revealed neural signatures of concepts like value, risk, and ambiguity, which are known to influence decision making. Such observations have led theorists to hypothesize a single, unified decision process that mediates choice behavior via a common neural currency for outcomes like food, money, or social praise. In parallel, recent neuroethological studies of decision making have focused on natural behaviors like foraging, mate choice, and social interactions. These decisions strongly impact evolutionary fitness and thus are likely to have played a key role in shaping the neural circuits that mediate decision making. This approach has revealed a suite of computational motifs that appear to be shared across a wide variety of organisms. We argue that the existence of deep homologies in the neural circuits mediating choice may have profound implications for understanding human decision making in health and disease
Diffusion, peer pressure and tailed distributions
We present a general, physically motivated non-linear and non-local advection
equation in which the diffusion of interacting random walkers competes with a
local drift arising from a kind of peer pressure. We show, using a mapping to
an integrable dynamical system, that on varying a parameter, the steady state
behaviour undergoes a transition from the standard diffusive behavior to a
localized stationary state characterized by a tailed distribution. Finally, we
show that recent empirical laws on economic growth can be explained as a
collective phenomenon due to peer pressure interaction.Comment: RevTex: 4 pages + 3 eps-figures. Minor Revision and figure 3
replaced. To appear in Phys. Rev. Letter
Intracule functional models. IV. Basis set effects
We have calculated position and dot intracules for a series of atomic and molecular systems, starting from an unrestricted Hartree-Fock wave function, expanded using the STO-3G, 6-31G, 6-311G, 6-311++G, 6-311++G(d,p), 6-311++G(3d,3p), and 6-311++G(3df,3pd) basis sets as well as the nonpolarized part of Dunning's cc-pV5Z basis. We find that the basis set effects on the intracules are small and that correlation energies from the dot intracule ansatz are remarkably insensitive to the basis set quality. Mean absolute errors in correlation energies across the G1 data set agree to within 2 mE(h) for all basis sets tested.P.M.W.G. thanks the APAC Merit Allocation Scheme for
a generous grant of supercomputer resources and the Australian
Research Council Grant Nos. DP0664466 and
DP0771978 for funding
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