593 research outputs found
New data on morphology and taxonomy of some species of the genus Nicrophorus Fabricius, 1775 (Coleoptera: Silphidae)
Descriptions of the endophallus (for 10
species) and female genital segments and genitalia (for
8 species) of the genus Nicrophorus Fabricius, 1775 are
presented in the paper. Figures of described structures
are given. A status of N. investigator interruptus stat. n. is
lowered to subspecies level, N. tennuipes (Lewis, 1887) is
included in the subgenus Nicrophorus Fabricius, 1775. Status
of the following taxa is restored: subgenera Acanthopsilus
Portevin, 1914 stat. resurr., Neonicrophorus Hatch, 1946
stat. resurr., Necrocleptes Semenov, 1933 stat. resurr.,
Nicrophorus Fabricius, 1775 stat. resurr., and subspecies
Nicrophorus germanicus morio (Gebler, 1817) stat. resurr.,
N. germanicus fascifer (Reitter, 1884) stat. resurr
On the formation mechanism of impurity-helium solids: evidence for extensive clustering
Optical emission studies on a discharged nitrogen-helium gas jet injected into superfluid helium near 1.5 K are described. The analysis of atomic (a-group) and molecular Vegard-Kaplan transitions clearly indicates that the emitting species are embedded in the nitrogen clusters. The formation of the clusters is most efficient in the crater formed on the liquid surface. The model calculations based on the classical bubble model and density functional theory suggest that under the experimental conditions only clusters consisting of more than 1000 molecules have a kinetic energy sufficient for the stable cavity formation inside liquid helium. The results obtained suggest that the formation of impurity-helium solids is a consequence of extensive clustering in the gas jet
Relaxation rates and collision integrals for Bose-Einstein condensates
Near equilibrium, the rate of relaxation to equilibrium and the transport
properties of excitations (bogolons) in a dilute Bose-Einstein condensate (BEC)
are determined by three collision integrals, ,
, and . All three collision integrals
conserve momentum and energy during bogolon collisions, but only conserves bogolon number. Previous works have considered the
contribution of only two collision integrals, and . In this work, we show that the third collision integral makes a significant contribution to the bogolon number
relaxation rate and needs to be retained when computing relaxation properties
of the BEC. We provide values of relaxation rates in a form that can be applied
to a variety of dilute Bose-Einstein condensates.Comment: 18 pages, 4 figures, accepted by Journal of Low Temperature Physics
7/201
Quantum theory of resonantly enhanced four-wave mixing: mean-field and exact numerical solutions
We present a full quantum analysis of resonant forward four-wave mixing based
on electromagnetically induced transparency (EIT). In particular, we study the
regime of efficient nonlinear conversion with low-intensity fields that has
been predicted from a semiclassical analysis. We derive an effective nonlinear
interaction Hamiltonian in the adiabatic limit. In contrast to conventional
nonlinear optics this Hamiltonian does not have a power expansion in the fields
and the conversion length increases with the input power. We analyze the
stationary wave-mixing process in the forward scattering configuration using an
exact numerical analysis for up to input photons and compare the results
with a mean-field approach. Due to quantum effects, complete conversion from
the two pump fields into the signal and idler modes is achieved only
asymptotically for large coherent pump intensities or for pump fields in
few-photon Fock states. The signal and idler fields are perfectly quantum
correlated which has potential applications in quantum communication schemes.
We also discuss the implementation of a single-photon phase gate for continuous
quantum computation.Comment: 10 pages, 11 figure
Theoretical analysis of the kinetics of low-temperature defect recombination in alkali halide crystals
We analyzed carefully the experimental kinetics of the low-temperature diffusion-controlled F, H center recombination in a series of irradiated alkali halides and extracted the migration energies and pre-exponential parameters for the hole H centers. The migration energy for the complementary electronic F centers in NaCl was obtained from the colloid formation kinetics observed above room temperature. The obtained parameters were compared with data available from the literature
Atomic structure at 2.5 Å resolution of uridine phosphorylase from E. coli as refined in the monoclinic crystal lattice
AbstractUridine phosphorylase from E. coli (Upase) has been crystallized using vapor diffusion technique in a new monoclinic crystal form. The structure was determined by the molecular replacement method at 2.5 Å resolution. The coordinates of the trigonal crystal form were used as a starting model and the refinement by the program XPLOR led to the R-factor of 18.6%. The amino acid fold of the protein was found to be the same as that in the trigonal crystals. The positions of flexible regions were refined. The conclusion about the involvement in the active site is in good agreement with the results of the biochemical experiments
Full quantum solutions to the resonant four-wave mixing of two single-photon wave packets
We analyze both analytically and numerically the resonant four-wave mixing of
two co-propagating single-photon wave packets. We present analytic expressions
for the two-photon wave function and show that soliton-type quantum solutions
exist which display a shape-preserving oscillatory exchange of excitations
between the modes. Potential applications including quantum information
processing are discussed.Comment: 7 pages, 3 figure
Measurement of (1020) meson leptonic width with CMD-2 detector at VEPP-2M Collider
The (1020) meson leptonic width has been determined from the combined
analysis of 4 major decay modes of the resonance () studied with the CMD-2 detector at
the VEPP-2M collider. The following value has been obtained:
keV.
The meson parameters in four main decay channels have been also
recalculated: , , , .Comment: 14 pages, 3 figure
Клиническое значение лазерного конверсионного тестирования в диагностике и лечении хронического эндометрита
In article presents the identified characteristics of spectral characteristics of endometrium in normal and chronic adnexitis. Identifies opportunities and prospects of laser conversion diagnostics monitoring, efficiency treatment and rehabilitation of patients with chronic èndometritom.В статье представлены данные выявленных особенностей спектральных характеристик эндометрия в норме и при хроническом эндометрите. Определены возможности и перспективы использования лазерной конверсионной диагностики в мониторинге эффективности лечения и реабилитации больных хроническим эндометритом
Observation of semileptonic decays with CMD-2 detector
The decay has been observed by the CMD-2 detector at
the e^+e^- collider VEPP-2M at Novosibirsk. Of 6 million produced
pairs, events of the decay were selected. The
corresponding branching ratio is . This result is consistent with the evaluation of from the semileptonic rate and lifetime
assuming .Comment: 7 pages, 6 figures, LaTex2e. Submitted to Phys.Lett.
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