254 research outputs found
Investigation of DNA denaturation in Peyrard-Bishop-Dauxois model by molecular dynamics method
The phase transition of duplex into the denaturated
state is studied in the Peyrard-Bishop-Dauxois model by the method of direct
molecular-dynamical modeling. The temperature dependencies of the total energy
and heat capacity of the duplex are calculated. The approach applied can be
used to calculate the statistical properties of the duplexes of any length and
nucleotide composition.Comment: 6 pages, 4 figure
On the thermodynamics of DNA in the Peyrard-Bishop-Dauxois model
Based on the direct method of molecular dynamics, the temperature dependence
of energy, partition function, entropy and free energy, describing the
first-order phase transition, is calculated for the classical
Peyrard-Bishop-Dauxois model of the DNA molecule. It is shown that without
taking into account the quantum freezing of the degrees of freedom at low
temperatures, the relationship between these quantities is not determined. An
estimation was given for the number of bubbles in homogeneous DNA chains:
PolyA/PolyT and PolyG/PolyC.Comment: 4 pages, 2 figure
Review of scientific topics for Millimetron space observatory
This paper describes outstanding issues in astrophysics and cosmology that
can be solved by astronomical observations in a broad spectral range from far
infrared to millimeter wavelengths. The discussed problems related to the
formation of stars and planets, galaxies and the interstellar medium, studies
of black holes and the development of the cosmological model can be addressed
by the planned space observatory Millimetron (the "Spectr-M" project) equipped
with a cooled 10-m mirror. Millimetron can operate both as a single-dish
telescope and as a part of a space-ground interferometer with very long
baseline.Comment: The translation of the original article in Physics Uspekhi
http://ufn.ru/ru/articles/2014/12/c
Structural and transport properties of GaAs/delta<Mn>/GaAs/InxGa1-xAs/GaAs quantum wells
We report results of investigations of structural and transport properties of
GaAs/Ga(1-x)In(x)As/GaAs quantum wells (QWs) having a 0.5-1.8 ML thick Mn
layer, separated from the QW by a 3 nm thick spacer. The structure has hole
mobility of about 2000 cm2/(V*s) being by several orders of magnitude higher
than in known ferromagnetic two-dimensional structures. The analysis of the
electro-physical properties of these systems is based on detailed study of
their structure by means of high-resolution X-ray diffractometry and
glancing-incidence reflection, which allow us to restore the depth profiles of
structural characteristics of the QWs and thin Mn containing layers. These
investigations show absence of Mn atoms inside the QWs. The quality of the
structures was also characterized by photoluminescence spectra from the QWs.
Transport properties reveal features inherent to ferromagnetic systems: a
specific maximum in the temperature dependence of the resistance and the
anomalous Hall effect (AHE) observed in samples with both "metallic" and
activated types of conductivity up to ~100 K. AHE is most pronounced in the
temperature range where the resistance maximum is observed, and decreases with
decreasing temperature. The results are discussed in terms of interaction of
2D-holes and magnetic Mn ions in presence of large-scale potential fluctuations
related to random distribution of Mn atoms. The AHE values are compared with
calculations taking into account its "intrinsic" mechanism in ferromagnetic
systems.Comment: 15 pages, 9 figure
Multiplicities of secondaries in nuclear interactions, induced by Ne-20, Ar-40 and Fe-56 nuclei at 0.1-0.5 GeV/nucleon
Multiplicities of various species of charged secondaries produced in inelastic interactions of Ne-20, Ar-40, and Fe-56 nuclei with emulsion nuclei, at 0.1-0.5 GeV/nucleon have been measured. The data obtained are compared with the results for interactions of higher energy nuclei with emulsion nuclei. The dependences of the nucleus-nucleus interaction parameters on masses and energies of colliding nuclei are examined
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