Universality in the distribution of caustics in the expanding Universe

We numerically investigate the long--time evolution of density perturbations after the first appearance of caustics in an expanding cosmological model with one--dimensional `single--wave' initial conditions. Focussing on the time--intervals of caustic appearances and the spatial distribution of caustics at subsequent times, we find that the time--intervals of caustic appearances approach a constant, i.e., their time--subsequent ratio converges to 1; it is also found that the spatial distribution of caustics at a given time features some universality rules, e.g., the ratio between the position of the nearest caustic from the center and that of the second nearest caustic from the center approaches a constant. Furthermore we find some rules for the mass distribution for each caustic. Using these universality constants we are in the position to predict the spatial distribution of caustics at an arbitrary time in order to give an estimate for the power spectral index in the fully--developed non--dissipative turbulent (`virialized') regime.Comment: 23 pages, 19 figure

Smart windows: cation internal and anion external activation for electrochromic films of nickel hydroxide

Two methods - internal and external - were used for improving the electrochemical activity and electrochromic properties of Ni(OH)2 films. In the case of internal activation, Al3+ ions were added to the electrolyte composition during the electrochemical precipitation process. In the case of external activation, [Fe(CN)6]4− ions were used in the electrolyte during the cycling process. In all the experiments there were used Ni(OH)2 films synthesized by the electrochemical template method with polyvinyl alcohol (PVA) addition to the electrolyte composition. It was shown that the addition of [Fe(CN)6]4− ions into the electrolyte for cycling leads to significant improvement of electrochemical and electrochromic (colorization-bleaching) properties. At the same time, the addition of Al3+ ions into the electrolyte for Ni(OH)2 films precipitation leads to drastic worsening of their properties. Also, possible mechanisms of Al3+ and [Fe(CN)6]4− ions influence were considered in this work

Blue spectra and induced formation of primordial black holes

We investigate the statistical properties of primordial black hole (PBH) formation in the very early Universe. We show that the high level of inhomogeneity of the early Universe leads to the formation of the first generation PBHs. %The existence of these PBHs This causes later the appearance of a dust-like phase of the cosmological expansion. We discuss here a new mechanism for the second generation of PBH formation during the dust-like phase. This mechanism is based on the coagulation process. We demonstrate that the blue power spectrum of initial adiabatic perturbations after inflation leads to overproduction of primordial black holes with $10^9$g$\le M\le10^{15}$g if the power index is $n\ge1.2$.Comment: 16 pages, 2 figure

The comparison of velocity distribution between Adhesion approximation and the Euler-Jeans-Newton model

For the evolution of density fluctuation in nonlinear cosmological dynamics, adhesion approximation (AA) is proposed as a phenomenological model, which is especially useful for describing nonlinear evolution. However, the origin of the artificial viscosity in AA is not clarified. Recently, Buchert and Dom\'{\i}nguez report if the velocity dispersion of the dust fluid is regarded as isotropic, it works on a principle similar to viscosity or effective pressure, and they consider isotropic velocity dispersion as the origin of the artificial viscosity in AA. They name their model the Euler-Jeans-Newton (EJN) model. In this paper, we focus on the velocity distribution in AA and the EJN model and examine the time evolution in both models. We find the behavior of AA differs from that of the EJN model, i.e., although the peculiar velocity in the EJN model oscillates, that in AA is monotonically decelerated due to viscosity without oscillation. Therefore it is hard to regard viscosity in AA as effective pressure in the EJN model.Comment: 11 pages, 5 figures; accepted for publication in Phys.Rev.

Inflation: flow, fixed points and observables to arbitrary order in slow roll

I generalize the inflationary flow equations of Hoffman and Turner to arbitrary order in slow roll. This makes it possible to study the predictions of slow roll inflation in the full observable parameter space of tensor/scalar ratio $r$, spectral index $n$, and running $d n / d \ln k$. It also becomes possible to identify exact fixed points in the parameter flow. I numerically evaluate the flow equations to fifth order in slow roll for a set of randomly chosen initial conditions and find that the models cluster strongly in the observable parameter space, indicating a ``generic'' set of predictions for slow roll inflation. I comment briefly on the the interesting proposed correspondence between flow in inflationary parameter space and renormalization group flow in a boundary conformal field theory.Comment: 16 pages, 7 figures. LaTeX. V4: Fixed important error in numerical constant in the second-order slow roll expressions for the observables r, n, and dn/dlog(k). See footnote after Eq. (48). New figures, minor changes to conclusions. Supersedes version published in Phys. Rev.

Sensory Communication

Contains table of contents for Section 2, an introduction and reports on twelve research projects.National Institutes of Health Grant 5 R01 DC00117National Institutes of Health Contract 2 P01 DC00361National Institutes of Health Grant 5 R01 DC00126National Institutes of Health Grant R01-DC00270U.S. Air Force - Office of Scientific Research Contract AFOSR-90-0200National Institutes of Health Grant R29-DC00625U.S. Navy - Office of Naval Research Grant N00014-88-K-0604U.S. Navy - Office of Naval Research Grant N00014-91-J-1454U.S. Navy - Office of Naval Research Grant N00014-92-J-1814U.S. Navy - Naval Training Systems Center Contract N61339-93-M-1213U.S. Navy - Naval Training Systems Center Contract N61339-93-C-0055U.S. Navy - Naval Training Systems Center Contract N61339-93-C-0083U.S. Navy - Office of Naval Research Grant N00014-92-J-4005U.S. Navy - Office of Naval Research Grant N00014-93-1-119

Investigation of charge and discharge regimes of nanomodified heataccumulating materials

Charge/discharge regimes of nanomodified paraffins have been studied. The nanomodification of paraffin was carried out by using the "Taunit" series nanomaterials with different morphological parameters under ultrasonic treatment. Comparative studies of thermophysical parameters (thermal conductivity and heat capacity) have been conducted for the prepared samples. Under charge/discharge regimes, the effect of "tracking thermal contact" manifests. The thermal conductivity increases to 0.48, 0.42 and 0.36 W/m°C in case of CNM-MD, CNM-M and CNM, relative to the initial thermal conductivity of 0.25 w/m°C. It has been established that the extreme on the thermal dependency graph depends on heat capacity (57, 63 and 72 °C for CNM, CNM-M and CNM-MD correspondingly). Modification of paraffin with carbon nanotubes allows controlling the phase-transition parameters, which allows obtaining a variety of temperature dependencies of heat capacity, thermal conductivity and physical-mechanical characteristics by combining different ratios of the "Taunit" series nanotubes and physical influences such as thermal fields and ultrasound. The heat-accumulating materials prepared in such a way allow achieving optimized operation of the heat accumulator under different temperature regimes. © A. Schegolkov, A. Schegolkov, N. Karpus, V. Kovalenko, V. Kotok, 2017

Investigation of charge and discharge regimes of nanomodified heataccumulating materials

Charge/discharge regimes of nanomodified paraffins have been studied. The nanomodification of paraffin was carried out by using the "Taunit" series nanomaterials with different morphological parameters under ultrasonic treatment. Comparative studies of thermophysical parameters (thermal conductivity and heat capacity) have been conducted for the prepared samples. Under charge/discharge regimes, the effect of "tracking thermal contact" manifests. The thermal conductivity increases to 0.48, 0.42 and 0.36 W/m°C in case of CNM-MD, CNM-M and CNM, relative to the initial thermal conductivity of 0.25 w/m°C. It has been established that the extreme on the thermal dependency graph depends on heat capacity (57, 63 and 72 °C for CNM, CNM-M and CNM-MD correspondingly). Modification of paraffin with carbon nanotubes allows controlling the phase-transition parameters, which allows obtaining a variety of temperature dependencies of heat capacity, thermal conductivity and physical-mechanical characteristics by combining different ratios of the "Taunit" series nanotubes and physical influences such as thermal fields and ultrasound. The heat-accumulating materials prepared in such a way allow achieving optimized operation of the heat accumulator under different temperature regimes. © A. Schegolkov, A. Schegolkov, N. Karpus, V. Kovalenko, V. Kotok, 2017

Synthesis and Characterisation of Dye­intercalated Nickel­aluminium Layered­double Hydroxide as a Cosmetic Pigment

Dye­intercalated layered double hydroxides (LDH) are modern promising pigments for paint and cosmetics industry. For the preparation of high­quality cosmetic pigments, particularly for nail polish, it was proposed to use not only intercalation but also chemisorption. For the pigment synthesis, Ni­AL LDH was chosen, along with murexide (Ammonium (purpurate) 2,6­dioxo­5­[(2,4,6­trioxo­5­hexahydropyrimidinylidene)amino]­3H­pyrimidin­4­olate), in which colored purpurate anion is able to form complex compounds with Ni2+. The murexide­intercalated (murexide amount for intercalation only) and murexide­intercalated­chemisorbed (murexide amount for Ni2+) Ni­Al LDH pigments were synthesized and used for the preparation of nail polish samples. The crystallographic composition was studied by means of XRD analysis. The color parameters (coordinates of color and chromaticity, dominant wavelength and color purity) of pigment powders and nail polish samples with these pigments have been studied using a color comparator. Organoleptic characteristics of pigment and nail polish samples were studied. The positive influence of chemisorption was shown: murexide­intercalated­chemisorbed pigment is easily ground, with the formation of highly dispersed powder, which during the preparation of nail polish was easily dispersed with the formation of stable yellow samples (dominant wavelength 583 nm) with high color purity of 43 %. Also, high covering ability of the murexide­intercalated­chemisorbed pigment was shown: high­quality, opaque, colored nail polish coat was formed at the pigment content of 45 %, 30 % and 15 % (wt.). For the synthesis of such pigments, it was recommended to choose anionic dyes that can form coordination bonds with LDH cations