510 research outputs found

    Non-sequential double ionization below laser-intensity threshold: Anticorrelation of electrons without excitation of parent ion

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    Two-electron correlated spectra of non-sequential double ionization below laser-intensity threshold are known to exhibit back-to-back scattering of the electrons, viz., the anticorrelation of the electrons. Currently, the widely accepted interpretation of the anticorrelation is recollision-induced excitation of the ion plus subsequent field ionization of the second electron. We argue that another mechanism, namely simultaneous electron emission, when the time of return of the rescattered electron is equal to the time of liberation of the bounded electron (the ion has no time for excitation), can also explain the anticorrelation of the electrons in the deep below laser-intensity threshold regime. Our conclusion is based on the results of the numerical solution of the time-dependent Schr\"{o}dinger equation for a model system of two one-dimensional electrons as well as an adiabatic analytic model that allows for a closed-form solution.Comment: 6 pages and 3 figure

    The pH Level Influence on Hydroxyapatite Phase Composition Synthesized with Hydrothermal Method

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    This paper reports the pH level influence on hydroxyapatite phase composition synthesized with hydrothermal method in Ca(OH)2-H3PO4, Ca(NO3)2-(NH4)2HPO4-NH[4]OH, Ca(OH)[2]-NH[4]H[2]PO[4].The obtained samples were studied with X-Ray diffraction, Fourier Transform Infrared (FTIR) and Raman spectroscopy. The one phase Ca[5]H[2]O[13]P[3] high crystallinity hydroxyapatite was synthesized with hydrothermal method at pH equal to 11. The crystallinity degree was calculated from the X-Ray diffraction pattern and became 0.96. The increasing pH level from 7 to 11 provides obtaining one phase hydroxyapatite at pH level 11 instead the two phase Ca[9.04](PO[4])6(OH)[1.68], CaHPO[4] at pH level 9 and CaPO[3](OH), Ca(OH)[2] at pH level 7

    The pH Level Influence on Hydroxyapatite Phase Composition Synthesized with Hydrothermal Method

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    This paper reports the pH level influence on hydroxyapatite phase composition synthesized with hydrothermal method in Ca(OH)2-H3PO4, Ca(NO3)2-(NH4)2HPO4-NH[4]OH, Ca(OH)[2]-NH[4]H[2]PO[4].The obtained samples were studied with X-Ray diffraction, Fourier Transform Infrared (FTIR) and Raman spectroscopy. The one phase Ca[5]H[2]O[13]P[3] high crystallinity hydroxyapatite was synthesized with hydrothermal method at pH equal to 11. The crystallinity degree was calculated from the X-Ray diffraction pattern and became 0.96. The increasing pH level from 7 to 11 provides obtaining one phase hydroxyapatite at pH level 11 instead the two phase Ca[9.04](PO[4])6(OH)[1.68], CaHPO[4] at pH level 9 and CaPO[3](OH), Ca(OH)[2] at pH level 7

    Application of reproductive technologies to the improvement of dairy cattle genomic selection

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    Genomic selection is a direction of breeding in which the value of an animal is predicted from DNA markers evenly covering the entire genome. This review summarizes information on modern trends in the genomic selection of dairy cattle and on application of reproductive technologies to the improvement of breeding process. The main trends in the development of genomic selection include improvement of the accuracy of breeding value estimations by combination of reference populations; use genotyping of cows in breeding programs; imputation of genotypes for absent SNPs with low marker density microarrays, and prediction of animal genotypes from the genotypes of relatives. Genomic selection can be even more profitable in combination with up-to-date reproductive biotechnologies: semen sexing, multiple ovulation and embryo transfer, ovum pick-up followed by in vitro fertilization, embryo genotyping, cloning of best breeders, etc. In programs of dairy cattle genomic selection, biotechnological procedures with gametes and embryos allow improvement of a variety of parameters determining breeding efficacy: selection intensity, accurate breeding value assessment, and generation interval. Successful methods for embryo genotyping for numerous markers after biopsy at the morula or blastocyst stage are based on whole genome amplification of embryo DNA. Eventually, these achievements will provide grounds for new approaches to the reduction of generation interval, selection of elite cows, reduction of inbreeding rate, etc

    Inelastic Processes in the Collision of Relativistic Highly Charged Ions with Atoms

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    A general expression for the cross sections of inelastic collisions of fast (including relativistic) multicharged ions with atoms which is based on the genelazition of the eikonal approximation is derived. This expression is applicable for wide range of collision energy and has the standard nonrelativistic limit and in the ultrarelativistic limit coincides with the Baltz's exact solution ~\cite{art13} of the Dirac equation. As an application of the obtained result the following processes are calculated: the excitation and ionization cross sections of hydrogenlike atom; the single and double excitation and ionization of heliumlike atom; the multiply ionization of neon and argon atoms; the probability and cross section of K-vacancy production in the relativistic U92+U91+U^{92+} - U^{91+} collision. The simple analytic formulae for the cross sections of inelastic collisions and the recurrence relations between the ionization cross sections of different multiplicities are also obtained. Comparison of our results with the experimental data and the results of other calculations are given.Comment: 25 pages, latex, 7 figures avialable upon request,submitted to PR
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