572 research outputs found
K^- ^3He and K^+K^- interactions in the pd -> ^3He K^+K^- reaction
We investigate the K^- ^3He and K^+ K^- interactions in the reaction pd ->
^3He K^+ K^- near threshold and compare our model calculations with data from
the MOMO experiment at COSY-Juelich. A large attractive effective K^- p
amplitude would give a significant K^- ^3He final-state interaction effect
which is not supported by the experimental data. We also estimate upper limits
for the a_0(980) and f_0(980) contributions to the produced K^+ K^- pairs.Comment: 5 pages, 2 figures, accepted for publication in PR
Doctoral Dissertation in Soviet Dissertation System: Experience of Defenses in 1930s — Early 1940s
The process of formation of the Soviet dissertation system (1920 — early 1940s) is considered. Attention is paid to the discussion of the degree of doctor of science in the 1920s, as well as the status of the doctoral dissertation in the regulations of the 1930s. It is hypothesized that the Soviet dissertation system grew out of the pre-revolutionary experience of awarding scientific degrees, but in the process of its formation it developed its own specific rituals. The hypothesis was tested on the example of dissertation disputes by M. D. Priselkov and A. I. Andreev — historians, whose entry into the scientific community began in the pre-Soviet period, and the achievement of the highest academic degree of Doctor of Science occurred at the turn of the 1930s—1940s. An assessment of the degree of continuity/gap of the Soviet dissertation system in relation to the pre-revolutionary experience has been carried out. The conclusion is drawn that the content of the disputes in the pre-war period was focused on the prerevolutionary traditions of the university system. It is argued that the scientific component of dissertation disputes at that time determined their atmosphere and content of discussions. The authors believe that the detailed transcripts of dissertation defenses in the Soviet era are an underestimated source for studying the Soviet dissertation system
Aspects of a0-f0 mixing in the reaction pn->da0
Some aspects of a0-f0 mixing effects in the reaction
with perpendicular polarized proton beam are discussed. An angular--asymmetry
parameter is defined to study those effects. It is shown that, for energies
close to the production threshold, the angular--asymmetry parameter is proportional to the a0-f0 mixing amplitude for arbitrary polar and
azimuthal angles and of the outgoing meson. This
statement is also valid for arbitrary energies, but then only at polar angles
and . The mass dependence of the differential cross
section in the reaction in the
presence of \mix mixing is also discussed.Comment: 17 pages, 3 Figure
Near-threshold production of -mesons in and NN collisions and -mixing
We consider near-threshold -meson production in and
collisions. An effective Lagrangian approach with one-pion exchange is applied
to analyze different contributions to the cross section for different isospin
channels. The Reggeon exchange mechanism is also evaluated for comparison. The
results from reactions are used to calculate the contribution of the
meson to the cross sections and invariant mass distributions
of the reactions and . It is found that
the experimental observation of mesons in the reaction is much more promising than the observation of mesons in
the reaction . Effects of isospin violation in the reactions
, , and , which are induced by -- mixing, are also analyzed.Comment: 43 pages, including 16 eps figures, to be bublished in Phys. Atom.
Nucl. (Yad. Fiz.) vol. 65, No. 11 (2002
Angular asymmetries in the reactions pp \to d\pi^+\eta and pn \to d\pi^0\eta and a_0-f_0 mixing
The reactions pp\to d\pi^+\eta and pn\to d\pi^0\eta are of special interest
for investigating the a_0(980) (J^P=0^+) resonance in the process NN \to da_0
\to d\pi\eta. We study some aspects of those reactions within a general
formalism and also in a concrete phenomenological model. In particular, it is
shown that the presence of nonresonant (i.e. without excitation of the a_0
resonance) contributions to these reactions yields nonvanishing values for
specific polarization observables, i.e. to effects like those generated by
a_0-f_0 mixing. An experimental determination of these observables for the
reaction pp\to d\pi^+\eta would provide concrete information on the magnitude
of those nonresonant contributions to \pi\eta production. We discuss also the
possibility of extracting information about a_0-f_0 mixing from the reaction pn
\to d\pi^0\eta with polarized proton beam.Comment: 14 pages, 3 figure
Epidemiology of Blastomycosis and Paracoccdioidomycosis
In recent years, an increase of tourist flow, strengthening of social and economic connections between the countries take place. The processes of the world economy globalization, development of international transport systems, and migration of population form preconditions for the spread of new infectious diseases in the territory of Russia and CIS countries. Imported cases of blastomycosis and paracoccidioidomycosis are already registered in many countries of Europe and Asia among persons who returned from endemic countries. Thus, it is likely to find infected persons and patients in Russia. The purpose of our review is to provide data indicating the need for improvement of methods for epidemiological control of blastomycosis and paracoccidioidomycosis. Diagnostic studies should be carried out by competent personnel in specialized laboratories that meet the necessary safety requirements. Thus, awareness about these diseases of as many experts as possible, guarantees the successful implementation of strategies for diagnostics and treatment
Indication of asymptotic scaling in the reactions H, He and
It is shown that the differential cross sections of the reactions and measured at c.m.s.scattering angle
in the interval of the deuteron beam energy 0.5 - 1.2 GeV demonstrate the
scaling behaviour,, which follows from constituent
quark counting rules. It is found also that the differential cross section of
the elastic scattering at follows
the scaling regime at beam energies 0.5 - 5 GeV. These data are
parameterized here using the Reggeon exchange.Comment: 6 pages, Latex, 2 eps figures; final version accepted by Pis'ma v
ZHETF, corrected and completed reference
The effect of water dynamics on conformation changes of albumin in pre-denaturation state:photon correlation spectroscopy and simulation
Water is essential for protein three-dimensional structure, conformational dynamics, and activity. Human serum albumin (HSA) is one of major blood plasma proteins, and its functioning is fundamentally determined by the dynamics of surrounding water. The goal of this study is to link the conformational dynamics of albumin to the thermal motions in water taking place in the physiological temperature range. We report the results of photon correlation spectroscopy and molecular dynamics simulations of HSA in aqueous solution. The experimental data processing produced the temperature dependence of the HSA hydrodynamic radius and its zeta potential. Molecular dynamics reproduced the results of experiments and revealed changes in the secondary structure caused by the destruction of hydrogen bonds in the macromolecule's globule
a0+(980)-resonance production in pp->dK+Kbar0 reactions close to threshold
The reaction pp->d K+ Kbar0 has been investigated at an excess energy of Q=46
MeV above the (K+ Kbar0) threshold with ANKE at COSY-Juelich. From the detected
coincident dK+ pairs about 1000 events with a missing Kbar0 were identified,
corresponding to a total cross section of sigma(pp->d K+ Kbar0)=(38 +/- 2(stat)
+/- 14(syst)) nb. Invariant-mass and angular distributions have been jointly
analyzed and reveal s-wave dominance between the two kaons, accompanied by a
p-wave between the deuteron and the kaon system. This is interpreted in terms
of a0+(980)-resonance production.Comment: 4 pages, 4 figures; accepted by Phys. Rev. Let
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