Large negative and positive delay of optical pulses in coherently prepared dense Rb vapor with buffer gas

We experimentally study the group time delay for a light pulse propagating through hot Rb vapor in the presence of a strong coupling field in a $\Lambda$ configuration. We demonstrate that the ultra-slow pulse propagation is transformed into superluminal propagation as the one-photon detuning of the light increases due to the change in the transmission resonance lineshape. Negative group velocity as low as -c/10^6=-80 m/s is recorded. We also find that the advance time in the regime of the superluminal propagation grows linearly with increasing laser field power.Comment: 5 pages, 6 figure

EIT and diffusion of atomic coherence

We study experimentally the effect of diffusion of Rb atoms on Electromagnetically Induced Transparency (EIT) in a buffer gas vapor cell. In particular, we find that diffusion of atomic coherence in-and-out of the laser beam plays a crucial role in determining the EIT resonance lineshape and the stored light lifetime.Comment: 5 pages, 8 figure

Hox gene expression during postlarval development of the polychaete Alitta virens

BACKGROUND: Hox genes are the family of transcription factors that play a key role in the patterning of the anterior-posterior axis of all bilaterian animals. These genes display clustered organization and colinear expression. Expression boundaries of individual Hox genes usually correspond with morphological boundaries of the body. Previously, we studied Hox gene expression during larval development of the polychaete Alitta virens (formerly Nereis virens) and discovered that Hox genes are expressed in nereid larva according to the spatial colinearity principle. Adult Alitta virens consist of multiple morphologically similar segments, which are formed sequentially in the growth zone. Since the worm grows for most of its life, postlarval segments constantly change their position along the anterior-posterior axis. RESULTS: We studied the expression dynamics of the Hox cluster during postlarval development of the nereid Alitta virens and found that 8 out of 11 Hox genes are transcribed as wide gene-specific gradients in the ventral nerve cord, ectoderm, and mesoderm. The expression domains constantly shift in accordance with the changing proportions of the growing worm, so expression domains of most Hox genes do not have stable anterior or/and posterior boundaries. In the course of our study, we revealed long antisense RNA (asRNA) for some Hox genes. Expression patterns of two of these genes were analyzed using whole-mount in-situ hybridization. This is the first discovery of antisense RNA for Hox genes in Lophotrochozoa. CONCLUSION: Hox gene expression in juvenile A. virens differs significantly from Hox gene expression patterns both in A. virens larva and in other Bilateria. We suppose that the postlarval function of the Hox genes in this polychaete is to establish and maintain positional coordinates in a constantly growing body, as opposed to creating morphological difference between segments

Addressing public subjects in latin american countries

The aim of research was identified comparative legal study of constitutions of American countries. The current study was based on a dialectical approach to disclosure of legal phenomena and processes, using general scientific method, (system, logical, analysis, and synthesis) and private scientific method

Analog studies of thermomechanical fatigue and abrasive wear of cast and forged steels for "autoforge" dies

Processes of thermomechanical fatigue and abrasive wear of suspension-cast precipitation-hardening ferrite-carbide steel 30T6NTiC-1.5 and standard steel 4Kh5MFS are studied. The dominant kinds of fracture typical for dies for semisolid stamping are determined. The factors and parameters of cyclic temperature and force loading are shown to produce a selective action on the competing kinds of damage of the die steels. A comparative analysis of the properties of the steels is performed. Steel 30T6NTiC-1.5 is shown to have substantial advantages over steel 4Kh5FMS traditionally used for making "Autoforge" dies. © 2014 Springer Science+Business Media New York

Assessment of the reforms and programs results of Ukraine’s economy sustainable development by means of neural networks

It is necessary to choose proper methodology and indicators for assessing sustainable economic development as the information becomes a tool for decision-making support of sustainable development policies and implementation of programs. In Ukraine, evaluating the results of implementation of different programs for development is essential as an analytical basis for making a strategy for the next period and a prerequisite for further progress. Certain shortcomings of linear models for evaluating the results appeared during the design and implementation of the strategy to manage sustainable economic development. The potential for establishing erroneous targets increases in the formation of strategic objectives for the next forecast period. There is a special need to choose adequate indicators to comprehensively approximate the factors of economic development and evaluation methods that allow more sensitively measuring the results of management decisions in the implementation of the strategy. The article evaluates the results of the Sustainable Development Strategy “Ukraine – 2020”, employing the potential of the neural network method for a flexible combination of a large number of factors in constructing nonlinear models of impact on the resulting indicator. As a result of applying the neural network model with one hidden layer for evaluation, based on 16 indicators identifying economic, social, and institutional aspects of sustainable development of Ukraine, it was found that institutional transformations contribute most to achieving sustainable development. Reforms in terms of deregulation and support of entrepreneurship, property rights protection, and competitive environment have the most significant positive impact. On the other hand, low efficiency of capital market reforms, implementation of the energy efficiency program, and reform in the field of public procurement determine the need to revise the program of their fulfilment

Coupling to short linear motifs creates versatile PME-1 activities in PP2A holoenzyme demethylation and inhibition

Protein phosphatase 2A (PP2A) holoenzymes target broad substrates by recognizing short motifs via regulatory subunits. PP2A methylesterase 1 (PME-1) is a cancer-promoting enzyme and undergoes methylesterase activation upon binding to the PP2A core enzyme. Here, we showed that PME-1 readily demethylates different families of PP2A holoenzymes and blocks substrate recognition in vitro. The high-resolution cryoelectron microscopy structure of a PP2A-B56 holoenzyme–PME-1 complex reveals that PME-1 disordered regions, including a substrate-mimicking motif, tether to the B56 regulatory subunit at remote sites. They occupy the holoenzyme substrate-binding groove and allow large structural shifts in both holoenzyme and PME-1 to enable multipartite contacts at structured cores to activate the methylesterase. B56 interface mutations selectively block PME-1 activity toward PP2A-B56 holoenzymes and affect the methylation of a fraction of total cellular PP2A. The B56 interface mutations allow us to uncover B56-specific PME-1 functions in p53 signaling. Our studies reveal multiple mechanisms of PME-1 in suppressing holoenzyme functions and versatile PME-1 activities derived from coupling substrate-mimicking motifs to dynamic structured cores

Kinetics of the disorder→order transformation in the Cu - 47 at.% Pd alloy

On the basis of experimental data obtained with the help of resistometric measurements, kinetic C-curves of the isothermal disorder→order transformation have been constructed and the activation energy of the atomic ordering process in the quenched Cu - 47 at.% Pd alloy has been calculated. Deviations from the data in the literature are explained by differences in the methods of obtaining the initial disordered state of the alloy. © 2013 Springer Science+Business Media New York