3,262 research outputs found
The Pulsation Mode and Distance of the Cepheid FF Aquilae
The determination of pulsation mode and distance for field Cepheids is a
complicated problem best resolved by a luminosity estimate. For illustration a
technique based on spectroscopic luminosity discrimination is applied to the
4.47d s-Cepheid FF Aql. Line ratios in high dispersion spectra of the variable
yield values of =-3.40+-0.02 s.e.(+-0.04 s.d.), average effective
temperature Teff=6195+-24 K, and intrinsic color (-)o = +0.506+-0.007,
corresponding to a reddening of E(B-V)=0.25+-0.01, or E(B-V)(B0)=0.26+-0.01.
The skewed light curve, intrinsic color, and luminosity of FF Aql are
consistent with fundamental mode pulsation for a small amplitude classical
Cepheid on the blue side of the instability strip, not a sinusoidal pulsator. A
distance of 413+-14 pc is estimated from the Cepheid's angular diameter in
conjunction with a mean radius of =39.0+-0.7 Rsun inferred from its
luminosity and effective temperature. The dust extinction towards FF Aql is
described by a ratio of total-to-selective extinction of
Rv=Av/E(B-V)=3.16+-0.34 according to the star's apparent distance modulus.Comment: To appear in ApJ
On the reactions p + p -> p + Lambda + K^+ and p + p -> p + Sigma^0 + K^+ near thresholds
The cross sections for the reactions of the strange production p + p -> p +
Lambda + K^+ and p + p -> p + Sigma^0 + K^+ near thresholds of the final states
p Lambda K^+ and p Sigma^0 K^+ are calculated in the effective Lagrangian
approach. Our approach is based on the dominant contribution of the one-pion
exchange and strong interaction of the colliding protons in the initial state.
The theoretical values of the cross sections agree reasonably well with the
experimental data. The polarization properties of the Lambda and Sigma^0
hyperons are discussed.Comment: 15 pages, 1 Postscript figure, Latex, to appear in Eur. Phys. J
THE USE OF COMPUTER TECHNOLOGIES AT THE PRECLINICAL STAGE OF HEPATOTOXICITY ASSESSEMENT OF ANTIVIRAL DRUG RIAMILOVIR
On polarization of strange baryons in reactions p + p -> p + Lambda^0 + K^+ and p + p -> p + Sigma^0 + K^+ near thresholds
Polarization properties of strange baryons produced in pp reactions, p + p ->
p + Lambda^0 + K^+ and p + p -> p + Sigma^0 + K^$, near thresholds of the final
states (p Lambda^0 K^+) and (p Sigma^0 K^+) are analysed relative to
polarizations of colliding protons. The cross sections for pp reactions are
calculated within the effective Lagrangian approach accounting for strong pp
rescattering in the initial state of colliding protons with a dominant
contribution of the one-pion exchange and strong final-state interaction of
daughter hadrons (Eur. Phys. J. A 9, 425 (2000)).Comment: 11 pages, latex, no figure
Anchors for the Cosmic Distance Scale: the Cepheids U Sgr, CF Cas and CEab Cas
New and existing X-ray, UBVJHKsW(1-4), and spectroscopic observations were
analyzed to constrain fundamental parameters for M25, NGC 7790, and dust along
their sight-lines. The star clusters are of particular importance given they
host the classical Cepheids U Sgr, CF Cas, and the visual binary Cepheids CEa
and CEb Cas. Precise results from the multiband analysis, in tandem with a
comprehensive determination of the Cepheids' period evolution (dP/dt) from ~140
years of observations, helped resolve concerns raised regarding the clusters
and their key Cepheid constituents. Specifically, distances derived for members
of M25 and NGC 7790 are 630+-25 pc and 3.40+-0.15 kpc, respectively.Comment: To appear in Astronomy and Astrophysic
Проблемы и перспективные направления развития судебно-психологической экспертизы
The paper examines key problems and encouraging trends in the evolution of forensic psychology, in terms of elaboration of expert criteria for the forensic psychological evaluation of legally relevant characteristics of examinees. The need for continued practice-based scientific inquiry in this area of forensic science is emphasized.Рассматриваются проблемы и перспективные направления развития СПЭ с позиций разработанности экспертных критериев судебно-психологической оценки юридически значимых особенностей подэкспертных лиц. Отмечается необходимость проведения основанных на практике научных изысканий в данной области экспертизы
3-(α-azidoalkyl)quinoxalin-2(1H)-ones and related alkylquinoxalinyl ketones
A convenient method has been developed for the synthesis of 3-alkanoyl-and 3-benzoyl-2-oxo-1,2-dihydroquinoxalines from the corresponding 3-(α-azidoalkyl)quinoxalines using acetic acid. © 2007 Springer Science+Business Media, Inc
Hydrodynamical description of a hadron-quark first-order phase transition
Solutions of hydrodynamical equations are presented for the equation of state
of the Var der Waals type allowing for the first order phase transition.
Attention is focused on description of the hadron-quark phase transition in
heavy ion collisions. It is shown that fluctuations dissolve and grow as if the
fluid is effectively very viscous. Even in spinodal region germs are growing
slowly due to viscosity and critical slowing down. This prevents enhancement of
fluctuations in the near-critical region, which is frequently considered as a
signal of the critical point in heavy ion collisions.Comment: 4 pages, 4 figure
Heuristic Models of Two-Fermion Relativistic Systems with Field-Type Interaction
We use the chain of simple heuristic expedients to obtain perturbative and
exactly solvable relativistic spectra for a family of two-fermionic bound
systems with Coulomb-like interaction. In the case of electromagnetic
interaction the spectrum coincides up to the second order in a coupling
constant with that following from the quantum electrodynamics. Discrepancy
occurs only for S-states which is the well-known difficulty in the bound-state
problem. The confinement interaction is considered too.
PACS number(s): 03.65.Pm, 03.65.Ge, 12.39.PnComment: 16 pages, LaTeX 2.0
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