417 research outputs found
Bound, virtual and resonance -matrix poles from the Schr\"odinger equation
A general method, which we call the potential -matrix pole method, is
developed for obtaining the -matrix pole parameters for bound, virtual and
resonant states based on numerical solutions of the Schr\"odinger equation.
This method is well-known for bound states. In this work we generalize it for
resonant and virtual states, although the corresponding solutions increase
exponentially when . Concrete calculations are performed for the
ground and the first excited states of , the resonance
states (, ), low-lying states of and
, and the subthreshold resonances in the proton-proton system. We
also demonstrate that in the case the broad resonances their energy and width
can be found from the fitting of the experimental phase shifts using the
analytical expression for the elastic scattering -matrix. We compare the
-matrix pole and the -matrix for broad resonance in
Comment: 14 pages, 5 figures (figures 3 and 4 consist of two figures each) and
4 table
Identification of the nature of traps involved in the field cycling of Hfâ‚€.â‚…Zrâ‚€.â‚…Oâ‚‚-based ferroelectric thin films
The discovery of ferroelectricity in hafnium oxide has revived the interest in ferroelectric memories as a viable option for low power non-volatile memories. However, due to the high coercive field of ferroelectric hafnium oxide, instabilities in the field cycling process are commonly observed and explained by the defect movement, defect generation and field induced phase transitions. In this work, the optical and transport experiments are combined with ab-initio simulations and transport modeling to validate that the defects which act as charge traps in ferroelectric active layers are oxygen vacancies. A new oxygen vacancy generation leads to a fast growth of leakage currents and a consequent degradation of the ferroelectric response in Hfâ‚€.â‚…Zrâ‚€.â‚…Oâ‚‚ films. Two possible pathways of the Hfâ‚€.â‚…Zrâ‚€.â‚…Oâ‚‚ ferroelectric property degradation are discussed
Production technology of heat-resistant high-strength syntactic carbon foams for operation in extreme conditions
© Published under licence by IOP Publishing Ltd. Production technology of products based on the syntactic carbon foams designed to operate in extreme conditions is proposed. The components and regime parameters for the production of foams of an open-pore cellular structure with specified thermophysical and strength characteristics for manufacturing the large-sized products of complex shape are determined
STUDIES ON PROTECTIVE EFFECTS OF A VACCINE, BASED ON RECOMBINANT Ag85, TB10 AND FliC PROTEINS
At present time, there is an obvious need for a new generation of vaccines as the most effective preventive approach, in order to stop spreading of tuberculosis infection. So far, the most popular strategy is aimed at heterological vaccination. The idea is to use BCG, or improved BCG, or attenuated M. tuberculosis for primary vaccination. For the further booster vaccination one may apply thw s.c. subunit or vector vaccines, containing protective mycobacterial proteins. The aim of our investigation was to evaluate protective effects of a new vaccine based on recombinant bacterial proteins Ag85, ТВ10 and FliC. We used a model with aerosol M. tuberculosis H37Rv infection, and compared lung and spleen CFU counts and life-span of vaccinated versus non-vaccinated С57BL/6 mice. As a result, we revealed three vaccine variants with comparable protective capacity against BCG using our experimental model. The most promising variant is suggested for testing in preclinical trials
Dynamical Masses of the Binary Brown Dwarf GJ 569Bab
We have obtained new images and high-resolution (R ~ 22400) near-infrared
(1.2400-1.2575 micron) spectra of each component of the brown dwarf binary GJ
569Bab using the Adaptive Optics facility of the Keck II telescope and the
NIRSPEC spectrometer. These data have allowed us to improve the determination
of the astrometric orbit and to measure radial velocities of the components. We
have used the astrometric and spectroscopic measurements to derive the
dynamical mass of each brown dwarf and the systemic velocity of the pair by
means of a chi^2 fitting technique. From various considerations, the mass of
each component is likely in the range 0.034-0.070 Msol (GJ 569Bb) and
0.055-0.087 Msol (GJ 569Ba). This implies that the mass ratio, q, of the binary
is greater than 0.4, being the most likely value q = 0.75-0.85. Adopting 0.072
Msol as the most conservative location of the substellar limit for solar
metallicity, our analysis confirms GJ 569Bb as the first genuine brown dwarf
known without any theoretical assumption. We have compared the dynamical masses
of GJ 569Ba and Bb, and their effective temperatures and luminosities, to the
predictions of state-of-the-art theoretical evolutionary isochrones, finding
that models exhibit good performance in the regime of high substellar masses if
the binary is about a few hundred million years old. However, the surface
gravities of GJ 569Ba (M8.5V) and Bb (M9V) derived from our spectral analysis
(the observed data have been compared to the latest synthetic spectra) appear
to be smaller than the values provided by the evolutionary models.Comment: 36 pages (tables and figures included). Accepted for publication in
Ap
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An active target concept for the electronuclear reactor
Preliminary identification of the components and efficiency estimations for the proposed (by Chelyabinsk-70) concept of active target for electronuclear reactor are goals of this work. (The electronuclear reactor comprises a high-energy proton acclerator, a high-atomic-number target (lead, tungsten) which produces neutrons from the protons, and a subcritical blanket.) Results of preliminary neutron and thermal-hydraulic simulations of the target are represented in the paper and preliminary detailing of the active target components is performed. It is shown that the use of active target can lead to an essential reduction of the requirements to the accelerator power without deterioration of the safety of the system
Magneto-Conductance Anisotropy and Interference Effects in Variable Range Hopping
We investigate the magneto-conductance (MC) anisotropy in the variable range
hopping regime, caused by quantum interference effects in three dimensions.
When no spin-orbit scattering is included, there is an increase in the
localization length (as in two dimensions), producing a large positive MC. By
contrast, with spin-orbit scattering present, there is no change in the
localization length, and only a small increase in the overall tunneling
amplitude. The numerical data for small magnetic fields , and hopping
lengths , can be collapsed by using scaling variables , and
in the perpendicular and parallel field orientations
respectively. This is in agreement with the flux through a `cigar'--shaped
region with a diffusive transverse dimension proportional to . If a
single hop dominates the conductivity of the sample, this leads to a
characteristic orientational `finger print' for the MC anisotropy. However, we
estimate that many hops contribute to conductivity of typical samples, and thus
averaging over critical hop orientations renders the bulk sample isotropic, as
seen experimentally. Anisotropy appears for thin films, when the length of the
hop is comparable to the thickness. The hops are then restricted to align with
the sample plane, leading to different MC behaviors parallel and perpendicular
to it, even after averaging over many hops. We predict the variations of such
anisotropy with both the hop size and the magnetic field strength. An
orientational bias produced by strong electric fields will also lead to MC
anisotropy.Comment: 24 pages, RevTex, 9 postscript figures uuencoded Submitted to PR
Representations of sl(2,?) in category O and master symmetries
We show that the indecomposable sl(2,?)-modules in the Bernstein-Gelfand-Gelfand category O naturally arise for homogeneous integrable nonlinear evolution systems. We then develop a new approach called the O scheme to construct master symmetries for such integrable systems. This method naturally allows computing the hierarchy of time-dependent symmetries. We finally illustrate the method using both classical and new examples. We compare our approach to the known existing methods used to construct master symmetries. For new integrable equations such as a Benjamin-Ono-type equation, a new integrable Davey-Stewartson-type equation, and two different versions of (2+1)-dimensional generalized Volterra chains, we generate their conserved densities using their master symmetries
Measurement of decay rate and parameters at KEDR
Using the inclusive photon spectrum based on a data sample collected at the
peak with the KEDR detector at the VEPP-4M collider, we
measured the rate of the radiative decay as well
as mass and width. Taking into account an asymmetric photon
lineshape we obtained keV, MeV/, MeV.Comment: 6 pages, 3 figure
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