757 research outputs found

    Two-proton radioactivity and three-body decay. V. Improved momentum distributions

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    Nowadays quantum-mechanical theory allows one to reliably calculate the processes of 2p radioactivity (true three-body decays) and the corresponding energy and angular correlations up to distances of the order of 1000 fm. However, the precision of modern experiments has now become sufficient to indicate some deficiency of the predicted theoretical distributions. In this paper we discuss the extrapolation along the classical trajectories as a method to improve the convergence of the theoretical energy and angular correlations at very large distances (of the order of atomic distances), where only the long-range Coulomb forces are still operating. The precision of this approach is demonstrated using the "exactly" solvable semianalytical models with simplified three-body Hamiltonians. It is also demonstrated that for heavy 2p emitters, the 2p decay momentum distributions can be sensitive to the effect of the screening by atomic electrons. We compare theoretical results with available experimental data.Comment: 13 pages, 18 figure

    From Coulomb excitation cross sections to non-resonant astrophysical rates in three-body systems: 17^{17}Ne case

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    Coulomb and nuclear dissociation of 17^{17}Ne on light and heavy targets are studied theoretically. The dipole E1 strength function is determined in a broad energy range including energies of astrophysical interest. Dependence of the strength function on different parameters of the 17^{17}Ne ground state structure and continuum dynamics is analyzed in a three-body model. The discovered dependence plays an important role for studies of the strength functions for the three-body E1 dissociation and radiative capture. The constraints on the [s2]/[d2][s^2]/[d^2] configuration mixing in 17^{17}Ne and on pp-wave interaction in the 15^{15}O+pp channel are imposed based on experimental data for 17^{17}Ne Coulomb dissociation on heavy target.Comment: 12 pages, 13 figure

    Emerg. Infect. Dis

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    The multidrug-resistant (MDR) Salmonella enterica serotype Newport strain that produces CMY-2 β-lactamase(Newport MDR-AmpC) was the source of sporadic cases and outbreaks in humans in France during 2000–2005. Because this strain was not detected in food animals, it was most likely introduced into France through imported food products

    Trace Formulas in Connection with Scattering Theory for Quasi-Periodic Background

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    We investigate trace formulas for Jacobi operators which are trace class perturbations of quasi-periodic finite-gap operators using Krein's spectral shift theory. In particular we establish the conserved quantities for the solutions of the Toda hierarchy in this class.Comment: 7 page

    Coulomb Dissociation of 17Ne^{17}Ne

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    Niños con discapacidades en la educación y preparación de la participación de sus padres

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    The article provides an overview of philosophical and humanitarian approaches to training parents in an inclusive education and the training system itself. The study purpose is to substantiate, develop and test a system for preparing parents of children with disabilities for assistance in the education, based on the humanistic approach and the axiological concept of philosophy. These approaches in the parent training system lead society to the fact that parental competencies should be based on the special education methods, techniques and technologies for educating children with special needs; to predict the result of education and manage the correctional and pedagogical process based on an individual approach to the child. The implementation of the developed system resulted in a high level of parents’ readiness to participate in inclusive children education.El artículo proporciona una visión general de los enfoques filosóficos y humanitarios para capacitar a los padres en una educación inclusiva y el sistema de capacitación en sí. El propósito del estudio es corroborar, desarrollar y probar un sistema para preparar a los padres de niños con discapacidades para la asistencia en la educación, basado en el enfoque humanista y el concepto axiológico de la filosofía. Estos enfoques en el sistema de capacitación para padres llevan a la sociedad al hecho de que las competencias de los padres deben basarse en los métodos, técnicas y tecnologías de educación especial para educar a los niños con necesidades especiales; predecir el resultado de la educación y gestionar el proceso correccional y pedagógico basado en un enfoque individual del niño. La implementación del sistema desarrollado resultó en un alto nivel de preparación de los padres para participar en la educación inclusiva de los niños

    Dependence of the Energy Spectrum of UHE Cosmic Rays on the Latitude of an Extensive Air Shower Array

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    Several energy spectra of cosmic rays with energies E_0 \geq 10^17 eV measured at the Yakutsk EAS, AGASA, Haverah Park, HiRes, Auger, and SUGAR arrays are considered. It is shown that the fairly good mutual agreement of the spectrum shapes can be achieved if the energy of each spectrum is multiplied by a factor K specific for each spectrum. These factors exhibit a pronounced dependence on the latitude of the above-mentioned arrays.Comment: 4 pages, 4 figure

    Spatial beam self-cleaning and supercontinuum generation with Yb-doped multimode graded-index fiber taper based on accelerating self-imaging and dissipative landscape

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    We experimentally demonstrate spatial beam self-cleaning and supercontinuum generation in a tapered Ytterbium-doped multimode optical fiber with parabolic core refractive index profile when 1064 nm pulsed beams propagate from wider (122 µm) into smaller (37 µm) diameter. In the passive mode, increasing the input beam peak power above 20 kW leads to a bell-shaped output beam profile. In the active configuration, gain from the pump laser diode permits to combine beam self-cleaning with supercontinuum generation between 520-2600 nm. By taper cut-back, we observed that the dissipative landscape, i.e., a non-monotonic variation of the average beam power along the MMF, leads to modal transitions of self-cleaned beams along the taper length

    The observation of long-range three-body Coloumb effects in the decay of 16Ne

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    The interaction of an E/AE/A=57.6-MeV 17^{17}Ne beam with a Be target was used to populate levels in 16^{16}Ne following neutron knockout reactions. The decay of 16^{16}Ne states into the three-body 14^{14}O+pp+pp continuum was observed in the High Resolution Array (HiRA). For the first time for a 2p emitter, correlations between the momenta of the three decay products were measured with sufficient resolution and statistics to allow for an unambiguous demonstration of their dependence on the long-range nature of the Coulomb interaction. Contrary to previous experiments, the intrinsic decay width of the 16^{16}Ne ground state was found to be narrow (Γ<60\Gamma<60~keV), consistent with theoretical estimates.Comment: 6 pages, 5 figure

    Detection of international high-risk clones of food-borne pathogens Salmonella and Escherichia coli in the Russian Federation

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    The use of whole genome sequencing, standard analyze methods and international databases allows to detect international high-risk clones of food-borne pathogens, to assess their evolution and geographical distribution due to international trade of animal food products and farm animals. In Saint-Petersburg, Russian Federation, Salmonella Newport, Salmonella Kentucky and Escherichia coli O26:H11 of well-known international high-risk clones were first identified from patients with diarrhea. Two S. Kentucky strains isolated in 2015 and 2019 were identical to the international clone ST198 widely distributed in European countries: had multidrug resistance, high-level fluoroquinolone resistance (MIC of ciprofloxacin  &gt;  32,0 mg/l) due to three single-nucleotide substitutions in the gyrA (Ser83Phe and Asp87Asn) and parC (Ser80Ile). In 2008, a multidrug resistant S. Newport strain resistant to extended-spectrum cephalosporins due to AmpC-cephalosporinase CMY-2 was isolated, belonging to the international clone of S. Newport MDR-AmpC/CMY-2  which caused sporadic cases and outbreaks in the USA and Europe in the 2000s. The plasmid containing the blaCMY-2 had a PstI-restriction profile, one of the most prevalent in the international clone. E. coli O26:H11 strains, isolated in Saint-Petersburg,  produced the shiga-like toxin STX1 (stx1a), had additional virulence genes: ehxA (enterohemolysin), katP (catalase peroxidase), espP (serine protease), as well as cba (colicin B), gad (glutamate decarboxylase), cif (type III secreted effector), iss (increased serum survival), belonged to the phylogenetic group B1 and the international high-risk clone  E. coli O26:H11 ST21 widely distributed in Europe and the USA. 25% of the strains had multidrug resistance and produced CTX-M extended spectrum beta-lactamases. In the Russian Federation E. coli O26 is consider as the pathogen of diarrheal diseases and registered as Enteropathogenic E. coli in routine bacteriological laboratories without detecting of H-antigen and shiga-like toxins
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