144,763 research outputs found
On the two-dimensional rotational body of maximal Newtonian resistance
We investigate, by means of computer simulations, shapes of nonconvex bodies
that maximize resistance to their motion through a rarefied medium, considering
that bodies are moving forward and at the same time slowly rotating. A
two-dimensional geometric shape that confers to the body a resistance very
close to the theoretical supremum value is obtained, improving previous
results.Comment: This is a preprint version of the paper published in J. Math. Sci.
(N. Y.), Vol. 161, no. 6, 2009, 811--819. DOI:10.1007/s10958-009-9602-
Lorentz violation in the linearized gravity
We study some consequences of the introduction of a Lorentz-violating
modification term in the linearized gravity, which leads to modified dispersion
relations for gravitational waves in the vacuum. We also discuss possible
mechanisms for the induction of such a term in the Lagrangian.Comment: Presented at the Fifth Meeting on CPT and Lorentz Symmetry,
Bloomington, Indiana, June 28-July 2, 201
Chameleon Cosmology Model Describing the Phantom Divide Line Crossing
An exact solution describing the evolution of the type Bang-to-Rip with the
phantom divide line crossing is constructed in the Chameleon cosmology model,
based on two independent functions of the scalar field.Comment: 9 page
Supersolidity and phase diagram of softcore bosons in a triangular lattice
We study the softcore extended Bose Hubbard model in a two-dimensional
triangular lattice by using the quantum Monte Carlo methods. The ground state
phase diagram of the system exhibits a very fruitful structure. Except the Mott
insulating state, four kinds of solid states with respect to the commensurate
filling factors and are identified. Two of them (CDW II
and CDW III) are newly predicted. In incommensurate fillings, superfluid,
spuersolid as well as phase separation states are detected . As in the case for
the hardcore bosons, a supersolid phase exists in while it is
unstable towards the phase separation in . However, this instability
is refrained in due to the softening of the bosons and then a
supersolid phase survives.Comment: 4 pages, 5 figure
Crossed Andreev reflection in diffusive contacts
Crossed Andreev reflection in multiterminal structures in the diffusive
regime is addressed within the quasiclassical Keldysh-Usadel formalism. The
elastic cotunneling and crossed Andreev reflection of quasiparticles give
nonlocal currents and voltages (depending on the actual biasing of the devices)
by virtue of the induced proximity effect in the normal metal electrodes. The
magnitude of the nonlocal processes is found to scale with the square of the
barrier transparency and to decay exponentially with interface spacing.
Nonlocal cotunneling and crossed Andreev conductances are found to contribute
equally to the nonlocal current, which is of relevance to the use of normal
metal-superconducting heterostructures as sources of entanglement
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