6,430 research outputs found
When a -tensor generates separation of variables of a certain metric
By a -tensor field , we construct an explicit system of
differential invariants that vanish if and only if there (locally) exists a
metric for which generates separation of variables.Comment: 16 pages, no figure
Inelastic Processes in the Collision of Relativistic Highly Charged Ions with Atoms
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 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
The level of serum creatine phosphokinase as a criterion of recovery in professional soccer players during the competitive period
Objective: the aim of this study was to evaluate the dynamics of the enzyme creatine phospokinase (CPK) in professional soccer players during the competitive period and to develop criteria and standards for the short and long-term adaptation of the athlete's body to physical exertion. Materials and methods: clinical and laboratory monitoring. During two seasons of the national championship 26 soccer players of high sports qualification (age: 26.7±3.1 years, height: 181.5±5.8 cm, fat content in the body: 9.9±1.7%) were examined. All athletes met the following criteria for inclusion in the study: participation in the pre-season, competition period; measurement of CPK level before the start of the season and at all time points after three games during the season; participation time - at least 75 minutes of the match (75-90 min/match); absence of muscle damage and complaints from the muscular system. Results: a twofold increase in the level of CPK was registered on the day after the match; a uniform decrease in the concentration of the enzyme was detected 60-72 hours after the match with the return of indicators to the pre-game level (
Darboux transformations for a 6-point scheme
We introduce (binary) Darboux transformation for general differential
equation of the second order in two independent variables. We present a
discrete version of the transformation for a 6-point difference scheme. The
scheme is appropriate to solving a hyperbolic type initial-boundary value
problem. We discuss several reductions and specifications of the
transformations as well as construction of other Darboux covariant schemes by
means of existing ones. In particular we introduce a 10-point scheme which can
be regarded as the discretization of self-adjoint hyperbolic equation
Dynamics of diproton formation in the and reactions in the GeV region
Mechanisms for the production of diproton pairs, , in the
reaction are studied at proton beam energies 0.5 -- 2 GeV in
kinematics similar to those of backward elastic scattering. This reaction
provides valuable information on the short-range and interactions
that is complementary to that investigated in the well known and
processes. The reaction is related to the
subprocesses and using two different
one--pion--exchange (OPE) diagrams. Within both these models a reasonable
agreement could be obtained with the data below 1GeV. The similar energy
dependence of the and cross sections and the small
ratio of about 1.5% in the production of to deuteron final states
follow naturally within the OPE models.Comment: 10 pages, 7 figures, Late
Zero-bias anomaly in two-dimensional electron layers and multiwall nanotubes
The zero-bias anomaly in the dependence of the tunneling density of states
on the energy of the tunneling particle for two-
and one-dimensional multilayered structures is studied. We show that for a
ballistic two-dimensional (2D) system the first order interaction correction to
DOS due to the plasmon excitations studied by Khveshchenko and Reizer is partly
compensated by the contribution of electron-hole pairs which is twice as small
and has the opposite sign. For multilayered systems the total correction to the
density of states near the Fermi energy has the form , where is the plasmon
energy gap of the multilayered 2D system. In the case of one-dimensional
conductors we study multiwall nanotubes with the elastic mean free path
exceeding the radius of the nanotube. The dependence of the tunneling density
of states energy, temperature and on the number of shells is found.Comment: 8 pages, 3 figure
- …