12,374 research outputs found
Anomalous latent heat in non-equilibrium phase transitions
We study first-order phase transitions in a two-temperature system, where due
to the time-scale separation all the basic thermodynamical quantities (free
energy, entropy, etc) are well-defined. The sign of the latent heat is found to
be counterintuitive: it is positive when going from the phase where the
temperatures and the entropy are higher to the one where these quantities are
lower. The effect exists only out of equilibrium and requires conflicting
interactions. It is displayed on a lattice gas model of ferromagnetically
interacting spin-1/2 particles.Comment: 4 pages, 2 figure
Valence Quark Distribution in A=3 Nuclei
We calculate the quark distribution function for 3He/3H in a relativistic
quark model of nuclear structure which adequately reproduces the nucleon
approximation, nuclear binding energies, and nuclear sizes for small nuclei.
The results show a clear distortion from the quark distribution function for
individual nucleons (EMC effect) arising dominantly from a combination of
recoil and quark tunneling effects. Antisymmetrization (Pauli) effects are
found to be small due to limited spatial overlaps. We compare our predictions
with a published parameterization of the nuclear valence quark distributions
and find significant agreement.Comment: 18pp., revtex4, 4 fig
Fragile antiferromagnetism in the heavy-fermion compound YbBiPt
We report results from neutron scattering experiments on single crystals of
YbBiPt that demonstrate antiferromagnetic order characterized by a propagation
vector, = (), and
ordered moments that align along the [1 1 1] direction of the cubic unit cell.
We describe the scattering in terms of a two-Gaussian peak fit, which consists
of a narrower component that appears below K and
corresponds to a magnetic correlation length of 80
, and a broad component that persists up to 0.7 K and
corresponds to antiferromagnetic correlations extending over 20 . Our results illustrate the fragile magnetic order
present in YbBiPt and provide a path forward for microscopic investigations of
the ground states and fluctuations associated with the purported quantum
critical point in this heavy-fermion compound.Comment: 5 pages, 3 figure
Discovery of a Wide Substellar Companion to a Nearby Low-Mass Star
We report the discovery of a wide (135+/-25 AU), unusually blue L5 companion
2MASS J17114559+4028578 to the nearby M4.5 dwarf G 203-50 as a result of a
targeted search for common proper motion pairs in the Sloan Digital Sky Survey
and the Two Micron All Sky Survey. Adaptive Optics imaging with Subaru
indicates that neither component is a nearly equal mass binary with separation
> 0.18", and places limits on the existence of additional faint companions. An
examination of TiO and CaH features in the primary's spectrum is consistent
with solar metallicity and provides no evidence that G 203-50 is metal poor. We
estimate an age for the primary of 1-5 Gyr based on activity. Assuming
coevality of the companion, its age, gravity and metallicity can be constrained
from properties of the primary, making it a suitable benchmark object for the
calibration of evolutionary models and for determining the atmospheric
properties of peculiar blue L dwarfs. The low total mass (M_tot=0.21+/-0.03
M_sun), intermediate mass ratio (q=0.45+/-0.14), and wide separation of this
system demonstrate that the star formation process is capable of forming wide,
weakly bound binary systems with low mass and BD components. Based on the
sensitivity of our search we find that no more than 2.2% of early-to-mid M
dwarfs (9.0 0.06 M_sun.Comment: 24 pages, 5 figures, accepted for publication in Ap
Text-based Editing of Talking-head Video
Editing talking-head video to change the speech content or to remove filler words is challenging. We propose a novel method to edit talking-head video based on its transcript to produce a realistic output video in which the dialogue of the speaker has been modified, while maintaining a seamless audio-visual flow (i.e. no jump cuts). Our method automatically annotates an input talking-head video with phonemes, visemes, 3D face pose and geometry, reflectance, expression and scene illumination per frame. To edit a video, the user has to only edit the transcript, and an optimization strategy then chooses segments of the input corpus as base material. The annotated parameters corresponding to the selected segments are seamlessly stitched together and used to produce an intermediate video representation in which the lower half of the face is rendered with a parametric face model. Finally, a recurrent video generation network transforms this representation to a photorealistic video that matches the edited transcript. We demonstrate a large variety of edits, such as the addition, removal, and alteration of words, as well as convincing language translation and full sentence synthesis
Suppression of quantum chaos in a quantum computer hardware
We present numerical and analytical studies of a quantum computer proposed by
the Yamamoto group in Phys. Rev. Lett. 89, 017901 (2002). The stable and
quantum chaos regimes in the quantum computer hardware are identified as a
function of magnetic field gradient and dipole-dipole couplings between qubits
on a square lattice. It is shown that a strong magnetic field gradient leads to
suppression of quantum chaos.Comment: 8 pages, 8 figures, research done at
http://www.quantware.ups-tlse.fr
The spirit of sport: the case for criminalisation of doping in the UK
This article examines public perceptions of doping in sport, critically evaluates the effectiveness of current anti-doping sanctions and proposes the criminalisation of doping in sport in the UK as part of a growing global movement towards such criminalisation at national level. Criminalising doping is advanced on two main grounds: as a stigmatic deterrent and as a form of retributive punishment enforced through the criminal justice system. The ‘spirit of sport’ defined by the World Anti-Doping Agency (WADA) as being based on the values of ethics, health and fair-play is identified as being undermined by the ineffectiveness of existing anti-doping policy in the current climate of doping revelations, and is assessed as relevant to public perceptions and the future of sport as a whole. The harm-reductionist approach permitting the use of certain performance enhancing drugs (PEDs) is considered as an alternative to anti-doping, taking into account athlete psychology, the problems encountered in containing doping in sport through anti-doping measures and the effect of these difficulties on the ‘spirit of sport’. This approach is dismissed in favour of criminalising doping in sport based on the offence of fraud. It will be argued that the criminalisation of doping could act as a greater deterrent than existing sanctions imposed by International Federations, and, when used in conjunction with those sanctions, will raise the overall ‘price’ of doping. The revelations of corruption within the existing system of self-governance within sport have contributed to a disbelieving public and it will be argued that the criminalisation of doping in sport could assist in satisfying the public that justice is being done and in turn achieve greater belief in the truth of athletic performances
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