Investigation of Anti-Relaxation Coatings for Alkali-Metal Vapor Cells Using Surface Science Techniques

Many technologies based on cells containing alkali-metal atomic vapor benefit from the use of anti-relaxation surface coatings in order to preserve atomic spin polarization. In particular, paraffin has been used for this purpose for several decades and has been demonstrated to allow an atom to experience up to 10,000 collisions with the walls of its container without depolarizing, but the details of its operation remain poorly understood. We apply modern surface and bulk techniques to the study of paraffin coatings, in order to characterize the properties that enable the effective preservation of alkali spin polarization. These methods include Fourier transform infrared spectroscopy, differential scanning calorimetry, atomic force microscopy, near-edge X-ray absorption fine structure spectroscopy, and X-ray photoelectron spectroscopy. We also compare the light-induced atomic desorption yields of several different paraffin materials. Experimental results include the determination that crystallinity of the coating material is unnecessary, and the detection of C=C double bonds present within a particular class of effective paraffin coatings. Further study should lead to the development of more robust paraffin anti-relaxation coatings, as well as the design and synthesis of new classes of coating materials.Comment: 12 pages, 12 figures. Copyright 2010 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in the Journal of Chemical Physics and may be found at http://link.aip.org/link/?JCP/133/14470

Role of magnetic degrees of freedom in a scenario of phase transformations in steel

The diversity of mesostructures formed in steel at cooling from a high-temperature austenite ("gamma") phase is determined by the interplay of shear reconstructions of crystal lattice and diffusion of carbon. Combining first-principles calculations with large-scale phase-field simulations we demonstrate a decisive role of magnetic degrees of freedom in the formation of energy relief along the Bain path of "gamma"-"alpha" transformation and, thus, in this interplay. We show that there is the main factor, namely, the magnetic state of iron and its evolution with temperature which controls the change in character of the transformation. Based on the computational results we propose a simple model which reproduces, in good agreement with experiment, the most important curves of the phase transformation in Fe-C, namely, the lines relevant to a start of ferrite, bainite, and martensite transformations. Phase-field simulations within the model describe qualitatively typical patterns at these transformations

Temporary Acceleration of Electrons While Inside an Intense Electromagnetic Pulse

A free electron can temporarily gain a very significant amount of energy if it is overrun by an intense electromagnetic wave. In principle, this process would permit large enhancements in the center-of-mass energy of electron-electron, electron-positron and electron-photon interactions if these take place in the presence of an intense laser beam. Practical considerations severely limit the utility of this concept for contemporary lasers incident on relativistic electrons. A more accessible laboratory phenomenon is electron-positron production via an intense laser beam incident on a gas. Intense electromagnetic pulses of astrophysical origin can lead to very energetic photons via bremsstrahlung of temporarily accelerated electrons

Achievements and prospects of applying high-throughput sequencing techniques to potato genetics and breeding

In recent years, marker-assisted selection (MAS) has been intensively used to increase potato breeding efficiency. Large-scale studies of the potato genome and genes exploiting next-generation sequence (NGS) approaches are required for broad application of MAS, genomic selection as well as genomic editing (the newest approach for creating potato with desired properties). In this review, trends in potato NGS-based research are overviewed, and related Internet resources are systematized. Special attention is given to peculiarities of the models and the approaches used in potato genetic studies, taking into account the complex organization of its genome and a high level of heterozygosity. In genetic studies diploids are used often, including diploid potato species, artificially obtained heterozygous dihaploids and homozygous double monoploids. The availability of artificially created diploid forms played an essential role in potato genome sequencing, which was completed in 2011. The Potato Genome Sequencing Consortium activities included not only constructing genome libraries, sequencing, assembling and annotation of the genome, but also genome sequence-based investigations uncovering features of potato genome evolution, SNP identification, analysis of genes and gene networks regulating resistance to phytopathogens and technological characteristics. An important outcome of the genome sequencing was further identification of more than 8 thousand SNPs and approbation of the Genotyping-by-sequencing (GBS) method on potato, which is the basis for potato genomic selection and for discovery of economically important genes using genome wide association studies (GWAS). Optimization of existing bioinformatic tools to support these studies, taking into account potato genome organization peculiarities, are carried out. This review gives analysis of databases containing potato genome and transcriptome sequencing results, as well as accompanying resources. This information should prove useful while planning comparative assays of potato transcriptome or application of DNA-markers. Sequencing of the genome as well as transcriptomes and microRNomes of cultivated potato and its wild relatives, on one hand, is of fundamental interest, assisting in detecting features of genome evolution, ontogenetic development and mechanisms of various environmental stresses responses. On the other hand, it is the basis for a wide range of practical applications for developing effective genomic and gene-specific markers and marker-assisted breeding of new potato cultivars with desired properties

Analysis of hadron production in nucleus-nucleus interactions up to and out of kinematical limit of free NN-collisions in the frame of FRITIOF model

In the framework of the modified FRITIOF model, the inclusive spectra of the cumulative $\pi ^0$-, $\pi ^-$-mesons and protons produced in the nucleus-nucleus interactions at 4.5 GeV/c/nucleon and 4.2 GeV/c/nucleon are calculated. It is shown that the model reproduces qualitatively, and in some cases quantitatively the main experimental regularities of $\pi$-mesons production, and "soft" part of the proton spectra. According to the model the production of the cumulative particles is connected with the mechanism of the "soft" nucleon-nucleon interaction.Comment: 12 pages, 11 figure

Photoproduction off Nuclei and Point-like Photon Interactions Part I: Cross Sections and Nuclear Shadowing

High energy photoproduction off nuclear targets is studied within the Glauber-Gribov approximation. The photon is assumed to interact as a $q\bar{q}$-system according to the Generalized Vector Dominance Model and as a ``bare photon'' in direct scattering processes with target nucleons. We calculate total cross sections for interactions of photons with nuclei taking into account coherence length effects and point-like interactions of the photon. Results are compared to data on photon-nucleus cross sections, nuclear shadowing, and quasi- elastic $\rho$-production. Extrapolations of cross sections and of the shadowing behaviour to high energies are given.Comment: 15 pages, 12 figure

Measurement of the Charged Multiplicities in b, c and Light Quark Events from Z0 Decays

Average charged multiplicities have been measured separately in $b$, $c$ and light quark ($u,d,s$) events from $Z^0$ decays measured in the SLD experiment. Impact parameters of charged tracks were used to select enriched samples of $b$ and light quark events, and reconstructed charmed mesons were used to select $c$ quark events. We measured the charged multiplicities: $\bar{n}_{uds} = 20.21 \pm 0.10 (\rm{stat.})\pm 0.22(\rm{syst.})$, $\bar{n}_{c} = 21.28 \pm 0.46(\rm{stat.}) ^{+0.41}_{-0.36}(\rm{syst.})$ $\bar{n}_{b} = 23.14 \pm 0.10(\rm{stat.}) ^{+0.38}_{-0.37}(\rm{syst.})$, from which we derived the differences between the total average charged multiplicities of $c$ or $b$ quark events and light quark events: $\Delta \bar{n}_c = 1.07 \pm 0.47(\rm{stat.})^{+0.36}_{-0.30}(\rm{syst.})$ and $\Delta \bar{n}_b = 2.93 \pm 0.14(\rm{stat.})^{+0.30}_{-0.29}(\rm{syst.})$. We compared these measurements with those at lower center-of-mass energies and with perturbative QCD predictions. These combined results are in agreement with the QCD expectations and disfavor the hypothesis of flavor-independent fragmentation.Comment: 19 pages LaTex, 4 EPS figures, to appear in Physics Letters

CRISPR-based strategies in infectious disease diagnosis and therapy

CRISPR gene-editing technology has the potential to transform the diagnosis and treatment of infectious diseases, but most clinicians are unaware of its broad applicability. Derived from an ancient microbial defence system, these so-called "molecular scissors" enable precise gene editing with a low error rate. However, CRISPR systems can also be targeted against pathogenic DNA or RNA sequences. This potential is being combined with innovative delivery systems to develop new therapeutic approaches to infectious diseases.info:eu-repo/semantics/publishedVersio