Affine maps of density matrices

For quantum systems described by finite matrices, linear and affine maps of matrices are shown to provide equivalent descriptions of evolution of density matrices for a subsystem caused by unitary Hamiltonian evolution in a larger system; an affine map can be replaced by a linear map, and a linear map can be replaced by an affine map. There may be significant advantage in using an affine map. The linear map is generally not completely positive, but the linear part of an equivalent affine map can be chosen to be completely positive and related in the simplest possible way to the unitary Hamiltonian evolution in the larger system.Comment: 4 pages, title changed, sentence added, reference update

Dynamic model of fiber bundles

A realistic continuous-time dynamics for fiber bundles is introduced and studied both analytically and numerically. The equation of motion reproduces known stationary-state results in the deterministic limit while the system under non-vanishing stress always breaks down in the presence of noise. Revealed in particular is the characteristic time evolution that the system tends to resist the stress for considerable time, followed by sudden complete rupture. The critical stress beyond which the complete rupture emerges is also obtained

Non-Classical Response from Quench-Cooled Solid Helium Confined in Porous Gold

We have investigated the non-classical response of solid 4He confined in porous gold set to torsional oscillation. When solid helium is grown rapidly, nearly 7% of the solid helium appears to be decoupled from the oscillation below about 200 mK. Dissipation appears at temperatures where the decoupling shows maximum variation. In contrast, the decoupling is substantially reduced in slowly grown solid helium. The dynamic response of solid helium was also studied by imposing a sudden increase in the amplitude of oscillation. Extended relaxation in the resonant period shift, suggesting the emergence of the pinning of low energy excitations, was observed below the onset temperature of the non-classical response. The motion of a dislocation or a glassy solid is restricted in the entangled narrow pores and is not likely responsible for the period shift and long relaxation

Dynamical solution to the μ\mu problem at TeV scale

We introduce a new confining force (\mu-color) at TeV scale to dynamically generate a supersymmetry preserving mass scale which would replace the \mu parameter in the minimal supersymmetric standard model (MSSM). We discuss the Higgs phenomenology and also the pattern of soft supersymmetry breaking parameters allowing the correct electroweak symmetry breaking within the \mu-color model, which have quite distinctive features from the MSSM and also from other generalizations of the MSSM.Comment: 12 pages, REVte

Targeting kidney mesangium by nanoparticles of defined size

Nanoparticles are being investigated for numerous medical applications and are showing potential as an emerging class of carriers for drug delivery. Investigations on how the physicochemical properties (e.g., size, surface charge, shape, and density of targeting ligands) of nanoparticles enable their ability to overcome biological barriers and reach designated cellular destinations in sufficient amounts to elicit biological efficacy are of interest. Despite proven success in nanoparticle accumulation at cellular locations and occurrence of downstream therapeutic effects (e.g., target gene inhibition) in a selected few organs such as tumor and liver, reports on effective delivery of engineered nanoparticles to other organs still remain scarce. Here, we show that nanoparticles of ~75 ± 25-nm diameters target the mesangium of the kidney. These data show the effects of particle diameter on targeting the mesangium of the kidney. Because many diseases originate from this area of the kidney, our findings establish design criteria for constructing nanoparticle-based therapeutics for targeting diseases that involve the mesangium of the kidney

Dynamic model for failures in biological systems

A dynamic model for failures in biological organisms is proposed and studied both analytically and numerically. Each cell in the organism becomes dead under sufficiently strong stress, and is then allowed to be healed with some probability. It is found that unlike the case of no healing, the organism in general does not completely break down even in the presence of noise. Revealed is the characteristic time evolution that the system tends to resist the stress longer than the system without healing, followed by sudden breakdown with some fraction of cells surviving. When the noise is weak, the critical stress beyond which the system breaks down increases rapidly as the healing parameter is raised from zero, indicative of the importance of healing in biological systems.Comment: To appear in Europhys. Let

Effect of surface roughness on rate-dependent slip in simple fluids

Molecular dynamics simulations are used to investigate the influence of molecular-scale surface roughness on the slip behavior in thin liquid films. The slip length increases almost linearly with the shear rate for atomically smooth rigid walls and incommensurate structures of the liquid/solid interface. The thermal fluctuations of the wall atoms lead to an effective surface roughness, which makes the slip length weakly dependent on the shear rate. With increasing the elastic stiffness of the wall, the surface roughness smoothes out and the strong rate dependence is restored again. Both periodically and randomly corrugated rigid surfaces reduce the slip length and its shear rate dependence.Comment: 15 pages, 5 figures; submitted to J. Chem. Phy

Testing a new luminosity/redshift indicator for γ\gamma-ray bursts

We have tested a relative spectral lag (RSL) method suggested earlier as a luminosity/redshift (or distance) estimator, using the generalized method by Schaefer & Collazzi. We find the derivations from the luminosity/redshift-RSL (L/R-RSL) relation are comparable with the corresponding observations. Applying the luminosity-RSL relation to two different GRB samples, we find that there exist no violators from the generalized test, namely the Nakar & Piran test and Li test. We also find that about 36 per cent of Schaefer's sample are outliers for the L/R-RSL relation within 1$\sigma$ confidence level, but no violators at 3$\sigma$ level within the current precision of L/R-RSL relation. An analysis of several potential outliers for other luminosity relations shows they can match the L/R-RSL relation well within an acceptable uncertainty. All the coincident results seem to suggest that this relation could be a potential tool for cosmological study.Comment: 7 pages, 6 figures and 1 table; Comments are welcom