Toxicological Patterns of Multicomponent Polymer Systems

Development of new polymer systems (PS) based on thermo-active resins is important not only from a chemical viewpoint but also because of the opportunity for programmable changing their properties and subsequent application in clinical practice. Some chemical features of a new composition for a multicomponent polymer system (MPS) based on hydrophilized unsaturated polyester resin (HUPR) are presented. Strength parameters of several resins of different compositions are examined. The analysis of the acute oral toxicity of these resins in white Wistar rats proves that they are low toxic. These PS do not demonstrate any harmful effects on human skin after the predicting irritation and sensitization tests using epicutaneous samples. Their main advantages include preliminary water-solubility and capacity to incorporate water, good dilution into water and resin water dispersions, porosity, low relative mass, high strength indices, improved ecological features, thin-founding capacity, good relief impressions in combination with high adhesion ability towards wet surfaces. A wide MPS usage in the manufacture of orthopedic plaster dressings, prostheses, splints, insoles, positive-sample dental imprints, and casts is recommended

Inelastic Quantum Transport

We solve a Schrodinger equation for inelastic quantum transport that retains full quantum coherence, in contrast to previous rate or Boltzmann equation approaches. The model Hamiltonian is the zero temperature 1d Holstein model for an electron coupled to optical phonons (polaron), in a strong electric field. The Hilbert space grows exponentially with electron position, forming a non-standard Bethe lattice. We calculate nonperturbatively the transport current, electron-phonon correlations, and quantum diffusion. This system is a toy model for the constantly branching ``wavefunction of the universe''.Comment: revtex, 13 pages, 4 figure

The effect of inelastic processes on tunneling

We study an electron that interacts with phonons or other linear or nonlinear excitations as it resonantly tunnels. The method we use is based on mapping a many-body problem in a large variational space exactly onto a one-body problem. The method is conceptually simpler than previous Green's function approaches, and allows the essentially exact numerical solution of much more general problems. We solve tunneling problems with transverse channels, multiple sites coupled to phonons, and multiple phonon degrees of freedom and excitations.Comment: 12 pages, REVTex, 4 figures in compressed tar .ps forma

Dark energy from conformal symmetry breaking

The breakdown of conformal symmetry in a conformally invariant scalar-tensor gravitational model is revisited in the cosmological context. Although the old scenario of conformal symmetry breaking in cosmology containing scalar field has already been used in many earlier works, it seems that no special attention has been paid for the investigation on the possible connection between the breakdown of conformal symmetry and the existence of dark energy. In this paper, it is shown that the old scenario of conformal symmetry breaking in cosmology, if properly interpreted, not only has a potential ability to describe the origin of dark energy as a symmetry breaking effect, but also may resolve the coincidence problem.Comment: 11 pages, minor revision, published online in EPJ

Coherent states for the hydrogen atom: discrete and continuous spectra

We construct the systems of generalised coherent states for the discrete and continuous spectra of the hydrogen atom. These systems are expressed in elementary functions and are invariant under the $SO(3, 2)$ (discrete spectrum) and $SO(4, 1)$ (continuous spectrum) subgroups of the dynamical symmetry group $SO(4, 2)$ of the hydrogen atom. Both systems of coherent states are particular cases of the kernel of integral operator which interwines irreducible representations of the $SO(4, 2)$ group.Comment: 15 pages, LATEX, minor sign corrections, to appear in J.Phys.

Temporally stable coherent states in energy degenerate systems: The hydrogen atom

Klauder's recent generalization of the harmonic oscillator coherent states [J. Phys. A 29, L293 (1996)] is applicable only in non-degenerate systems, requiring some additional structure if applied to systems with degeneracies. The author suggests how this structure could be added, and applies the complete method to the hydrogen atom problem. To illustrate how a certain degree of freedom in the construction may be exercised, states are constructed which are initially localized and evolve semi-classically, and whose long time evolution exhibits "fractional revivals."Comment: 9 pages, 3 figure

Cosmological Evolution Across Phantom Crossing and the Nature of the Horizon

In standard cosmology, with the evolution of the universe, the matter density and thermodynamic pressure gradually decreases. Also in course of evolution, the matter in the universe obeys (or violates) some restrictions or energy conditions. If the matter distribution obeys strong energy condition (SEC), the universe is in a decelerating phase while violation of SEC indicates an accelerated expansion of the universe. In the period of accelerated expansion the matter may be either of quintessence nature or of phantom nature depending on the fulfilment of the weak energy condition (WEC) or violation of it. As recent observational evidences demand that the universe is going through an accelerated expansion so mater should be either quintessence or phantom in nature. In the present work we study the evolution of the universe through the phantom barrier (i.e. the dividing line between the quintessence and phantom era) and examine how apparent and event horizon change across the barrier. Finally, we investigate the possibility of occurrence of any singularity in phantom era.Comment: 7 pages and 4 figure

Stochastic evolution of cosmological parameters in the early universe

We develop a stochastic formulation of cosmology in the early universe, after considering the scatter in the redshift-apparent magnitude diagram in the early epochs as an observational evidence for the non-deterministic evolution of early universe. We consider the stochastic evolution of density parameter in the early universe after the inflationary phase qualitatively, under the assumption of fluctuating $w$ factor in the equation of state, in the Fokker-Planck formalism. Since the scale factor for the universe depends on the energy density, from the coupled Friedmann equations we calculated the two variable probability distribution function assuming a flat space geometry.Comment: 10 page

Born-Infeld-type phantom on the brane world

We study the evolution of Born-Infeld-type phantom in the second Randall-Sundrum brane scenario, and find that there exists attractor solution for the potential with a maximum, which implies a cosmological constant at the late time. Especially, we discuss the BI model of constant potential without and with dust matter. In the weak tension limit of the brane, we obtain an exact solution for the BI phantom and scale factor and show that there is no big rip during the evolution of the brane.Comment: 5 pages, 2 figures, Reference added, Phys. Rev. D in pres

Interacting Dark Energy in Ho\v{r}ava-Lifshitz Cosmology

In the usual Ho\v{r}ava-Lifshitz cosmological models, the scalar field is responsible for dark matter. Using an additional scalar field, Saridakis \cite{sari} has formulated Ho\v{r}ava-Lifshitz cosmology with an effective dark energy sector. In the paper \cite{sari} the scalar fields do not interact with each other, here we extend this work to the interacting case, where matter scalar field $\phi$ interact with dark energy scalar field $\sigma$. We will show that in contrast with \cite{sari}, where $\sigma$-filed is absent, we can obtain $w_d ^{\rm eff}<-1$, that is we result to an effective dark energy presenting phantom behaviour. This behaviour is pure effect of the interaction.Comment: 10 pages, no figur