1,999 research outputs found
Status of Longitudinal Polarized Parton Densities and Higher Twist
The present status of the longitudinal polarized parton densities (PDFs) and
the contribution of their first moments to the nucleon spin is discussed.
Special attention is paid to the role of higher twist effects in determining
the PDFs and to the polarized strange quark and gluon densities, which are
still not well determined from the present data.Comment: 6 pages, 5 figures; to appear in the proceedings of the 18th
International Symposium on Spin Physics (SPIN20008), October 6 - 11, 2008,
Charlottesville, Virginia, US
Orientational Order-Disorder Effects in Molecular Crystals as Evidenced by Low-Frequency Raman Spectra
The studies of reorientational motions of molecules in crystals
of organic compounds by low-frequency Raman spectroscopy are
briefly reported. Some examples illustrate the efficiency of the
investigation of order-disorder phenomena in organic crystals by
the temperature dependence of low-frequency vibrational spectra
combined with simultaneous calculations of the molecular dynamics
by the atom-atom potentials (AAP) method. The conditions have been determined which are necessary in order to affect the low-frequency Raman spectra by anisotropy of molecular reorientations in crystals
Epizootiological and Epidemiological Characteristics of Rabies in Russia in 2019–2021
The review presents an analysis of the epizootic and epidemic situations on rabies in the Russian Federation in 2019–2021. During that period, there was a decrease in the activity of the epizootic process to the level of the 1990s characterized by overhunting of the fox, raccoon dog and corsac. The number of identified potentially hazardous areas declined by 20 %, and the number of sick animals registered in them decreased from 18 to 10. Since 2018, the share of domestic animals has prevailed over wild animals in the structure of animal incidence, and in 2021, the proportion of detected cases of rabies in wild animals was the smallest (37.9 %) over 11 years of observation (2011–2021). The leading role in maintaining the circulation of the rabies pathogen belonged to the fox, which accounted for 34.8–29.9 % of all animal cases in 2019–2021. The raccoon dog actively contributed to the circulation of the virus in the European part of Russia. Since 2012, a downward trend in the incidence of rabies among the population has been established (Tdw. = –9.5 %), the average long-term indicator was 5 cases per year. Dogs and cats that got involved into epizootic process predominated among the sources of hydrophobia – approximately 50 % of the cases. Poor compliance with the rules for keeping pets has led to an increase in human infection with rabies due to the animals in 2020–2021. In 2019–2021, the participation of bats in infecting humans with lyssavirus was established, which draws the attention to the need to study the role of bats in the circulation of lyssaviruses, primarily in the Far East. The risk of rabies infection persisted in almost all regions of the country. In the 21st century, natural foci of infection are ubiquitous in Russia
Some properties of WKB series
We investigate some properties of the WKB series for arbitrary analytic
potentials and then specifically for potentials ( even), where more
explicit formulae for the WKB terms are derived. Our main new results are: (i)
We find the explicit functional form for the general WKB terms ,
where one has only to solve a general recursion relation for the rational
coefficients. (ii) We give a systematic algorithm for a dramatic simplification
of the integrated WKB terms that enter the energy
eigenvalue equation. (iii) We derive almost explicit formulae for the WKB terms
for the energy eigenvalues of the homogeneous power law potentials , where is even. In particular, we obtain effective algorithms to
compute and reduce the terms of these series.Comment: 18 pages, submitted to Journal of Physics A: Mathematical and Genera
Superconductivity and Quantum Criticality in CeCoIn_5
Electrical resistivity measurements on a single crystal of the heavy-fermion
superconductor CeCoIn_5 at pressures to 4.2 GPa reveal a strong crossover in
transport properties near P^* \approx 1.6 GPa, where T_c is a maximum. The
temperature-pressure phase diagram constructed from these data provides a
natural connection to cuprate physics, including the possible existence of a
pseudogap.Comment: 4 pages, 4 figure
Reachability problems for PAMs
Piecewise affine maps (PAMs) are frequently used as a reference model to show
the openness of the reachability questions in other systems. The reachability
problem for one-dimentional PAM is still open even if we define it with only
two intervals. As the main contribution of this paper we introduce new
techniques for solving reachability problems based on p-adic norms and weights
as well as showing decidability for two classes of maps. Then we show the
connections between topological properties for PAM's orbits, reachability
problems and representation of numbers in a rational base system. Finally we
show a particular instance where the uniform distribution of the original orbit
may not remain uniform or even dense after making regular shifts and taking a
fractional part in that sequence.Comment: 16 page
High pressure investigation of the heavy-fermion antiferromagnet U_3Ni_5Al_19
Measurements of magnetic susceptibility, specific heat, and electrical
resistivity at applied pressures up to 55 kbar have been carried out on single
crystals of the heavy-fermion antiferromagnet U_3Ni_5Al_19, which crystallizes
in the Gd_3Ni_5Al_19 orthorhombic structure with two inequivalent U sites. At
ambient pressure, a logarithmic T-dependence of the specific heat and T-linear
electrical resistivity below 5 K indicates non-Fermi liquid (NFL) behavior in
the presence of bulk antiferromagnetic order at T_N=23 K. Electrical
resistivity measurements reveal a crossover from non-Fermi liquid to Fermi
liquid behavior at intermediate pressures between 46 kbar and 51 kbar, followed
by a return to NFL T^{3/2} behavior at higher pressures. These results provide
evidence for an ambient pressure quantum critical point and an additional
antiferromagnetic instability at P_c=60 kbar.Comment: 12 pages, 5 figure
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