59 research outputs found
Understanding oscillons: standing waves in a ball
Oscillons are localised long-lived pulsating states in the three-dimensional
theory. We gain insight into the spatio-temporal structure and
bifurcation of the oscillons by studying time-periodic solutions in a ball of a
finite radius. A sequence of weakly localised {\it Bessel waves} -- nonlinear
standing waves with the Bessel-like -dependence -- is shown to extend from
eigenfunctions of the linearised operator. The lowest-frequency Bessel wave
serves as a starting point of a branch of periodic solutions with exponentially
localised cores and small-amplitude tails decaying slowly towards the surface
of the ball. A numerical continuation of this branch gives rise to the
energy-frequency diagram featuring a series of resonant spikes. We show that
the standing waves associated with the resonances are born in the
period-multiplication bifurcations of the Bessel waves with higher frequencies.
The energy-frequency diagram for a sufficiently large ball displays sizeable
intervals of stability against spherically-symmetric perturbations.Comment: 13 pages, 12 figure
Testing He density distributions by calculations of total reaction cross-sections of He+Si
Calculations of the He + Si total reaction cross sections at
intermediate energies are performed on the basis of the Glauber-Sitenko
microscopic optical-limit model. The target-nucleus density distribution is
taken from the electron-nucleus scattering data, and the He densities
are used as they are derived in different models. The results of the
calculations are compared with the existing experimental data. The effects of
the density tails of the projectile nuclei as well as the role of shell
admixtures and short-range correlations are analyzed.Comment: 10 pages, 5 figures. Submitted to the International Journal of Modern
Physics
Study of He+C Elastic Scattering Using a Microscopic Optical Potential
The He+C elastic scattering data at beam energies of 3, 38.3 and
41.6 MeV/nucleon are studied utilizing the microscopic optical potentials
obtained by a double-folding procedure and also by using those inherent in the
high-energy approximation. The calculated optical potentials are based on the
neutron and proton density distributions of colliding nuclei established in an
appropriate model for He and obtained from the electron scattering form
factors for C. The depths of the real and imaginary parts of the
microscopic optical potentials are considered as fitting parameters. At low
energy the volume optical potentials reproduce sufficiently well the
experimental data. At higher energies, generally, additional surface terms
having form of a derivative of the imaginary part of the microscopic optical
potential are needed. The problem of ambiguity of adjusted optical potentials
is resolved requiring the respective volume integrals to obey the determined
dependence on the collision energy. Estimations of the Pauli blocking effects
on the optical potentials and cross sections are also given and discussed.
Conclusions on the role of the aforesaid effects and on the mechanism of the
considered processes are made.Comment: 12 pages, 9 figures, accepted for publication in Physical Review
COST ANALYSIS OF TUBERCULOSIS CONTROL ACTIVITIES CENTERED AT THE PATIENT AND PERFORMED ON THE OUT-PATIENT BASIS IN THE URBAN SETTINGS
Costs of out-patient patient-centered activities introduced into the existing standard model of the tuberculosis treatment have been evaluated in Tomsk TB Service. Additional measures enhancing compliance in the patients included the following: timely detection and management of side effects of chemotherapy, social support to the patients, treatment at home, psychological support and treatment by the Sputnik team of most socially vulnerable patients.The average additional costs for the patient-centered activities per 1 patient treated as per regimens I, II, III made 1367 RUR a month; per 1 PR TB patient – 2978 RUR; and per regimen IV – 4865 RUR. Patient-centered activities performed during the out-patient stage of treatment made 7% out of the total treatment costs for regimens I, II, III; 14% when treating polyresistant TB; and 16% for regimen IV
Calculations of He+p Elastic Cross Sections Using Microscopic Optical Potential
An approach to calculate microscopic optical potential (OP) with the real
part obtained by a folding procedure and with the imaginary part inherent in
the high-energy approximation (HEA) is applied to study the He+p elastic
scattering data at energies of tens of MeV/nucleon (MeV/N). The neutron and
proton density distributions obtained in different models for He are
utilized in the calculations of the differential cross sections. The role of
the spin-orbit potential is studied. Comparison of the calculations with the
available experimental data on the elastic scattering differential cross
sections at beam energies of 15.7, 26.25, 32, 66 and 73 MeV/N is performed. The
problem of the ambiguities of the depths of each component of the optical
potential is considered by means of the imposed physical criterion related to
the known behavior of the volume integrals as functions of the incident energy.
It is shown also that the role of the surface absorption is rather important,
in particular for the lowest incident energies (e.g., 15.7 and 26.25
MeV/nucleon).Comment: 11 pages, 7 figures, accepted for publication in Physical Review
Charge and matter distributions and form factors of light, medium and heavy neutron-rich nuclei
Results of charge form factors calculations for several unstable neutron-rich
isotopes of light, medium and heavy nuclei (He, Li, Ni, Kr, Sn) are presented
and compared to those of stable isotopes in the same isotopic chain. For the
lighter isotopes (He and Li) the proton and neutron densities are obtained
within a microscopic large-scale shell-model, while for heavier ones Ni, Kr and
Sn the densities are calculated in deformed self-consistent mean-field Skyrme
HF+BCS method. We also compare proton densities to matter densities together
with their rms radii and diffuseness parameter values. Whenever possible
comparison of form factors, densities and rms radii with available experimental
data is also performed. Calculations of form factors are carried out both in
plane wave Born approximation (PWBA) and in distorted wave Born approximation
(DWBA). These form factors are suggested as predictions for the future
experiments on the electron-radioactive beam colliders where the effect of the
neutron halo or skin on the proton distributions in exotic nuclei is planned to
be studied and thereby the various theoretical models of exotic nuclei will be
tested.Comment: 26 pages, 11 figures, 3 tables, accepted for publication in Phys.
Rev.
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