584 research outputs found
Early stages in the evolution of the atmosphere and climate on the Earth-group planets
The early evolution of the atmospheres and climate of the Earth, Mars and Venus is discussed, based on a concept of common initial conditions and main processes (besides known differences in chemical composition and outgassing rate). It is concluded that: (1) liquid water appeared on the surface of the earth in the first few hundred million years; the average surface temperature was near the melting point for about the first two eons; CO2 was the main component of the atmosphere in the first 100-500 million years; (2) much more temperate outgassing and low solar heating led to the much later appearance of liquid water on the Martian surface, only one to two billion years ago; the Martian era of rivers, relatively dense atmosphere and warm climate ended as a result of irreversible chemical bonding of CO2 by Urey equilibrium processes; (3) a great lack of water in the primordial material of Venus is proposed; liquid water never was present on the surface of the planet, and there was practically no chemical bonding of CO2; the surface temperature was over 600 K four billion years ago
Preliminary results of measurements by automated probes Vega 1 and 2 or particle concentration in clouds of Venus at heights 47-63 KM
Results of the preliminary processing of the Vega 1 and 2 descender data on the cloud layer structure of the Venusian atmosphere are discussed. A photoelectric counter for aerosol particles is described together with its optical and pneumatic circuits and operation algorithm. Vertical profiles of concentrations of particles with a diameter of 0.4 microns agree quantitatively with the Pioneer-Venus and Venera 9 and 10 data. Concentrations of these particles are: in the B layer, up to 190/cu cm; in the C layer, up to 10/cu cm; and in the D layer, up to 130/cu cm. Layers have sharp boundaries with a significant vertical heterogeneity of the aerosol concentration field inside them
On the low-temperature anomalies in the thermal conductivity of plastically deformed crystals due to phonon-kink scattering
Previous experimental studies of the thermal conductivity of plastically
deformed lead crystals in the superconducting state have shown strong anomalies
in the thermal conductivity. Similar effects were also found for the thermal
conductivity of bent samples. Until now, a theoretical
explanation for these results was missing. In this paper we will introduce the
process of phonon-kink scattering and show that it qualitatively explains the
anomalies that experiments had found.Comment: 3 pages, follow-up paper to appear soo
Gaudin models for gl(m|n)
Date of Acceptance: 16/04/2015We establish the basics of the Bethe ansatz for the Gaudin model associated to the Lie superalgebra gl(m|n). In particular, we prove the completeness of the Bethe ansatz in the case of tensor products of fundamental representations.Peer reviewedFinal Accepted Versio
Quantum spin chains and integrable many-body systems of classical mechanics
This note is a review of the recently revealed intriguing connection between
integrable quantum spin chains and integrable many-body systems of classical
mechanics. The essence of this connection lies in the fact that the spectral
problem for quantum Hamiltonians of the former models is closely related to a
sort of inverse spectral problem for Lax matrices of the latter ones. For
simplicity, we focus on the most transparent and familiar case of spin chains
on N sites constructed by means of the GL(2)-invariant R-matrix. They are
related to the classical Ruijsenaars-Schneider system of N particles, which is
known to be an integrable deformation of the Calogero-Moser system. As an
explicit example the case N=2 is considered in detail.Comment: 17 pages, misprints corrected, written for Proceedings of the
International School and Workshop "Nonlinear Mathematical Physics and Natural
Hazards", Sofia, Bulgaria, November 28 - December 2, 2013, to be published in
Lecture Notes in Physic
Spaces of quasi-exponentials and representations of gl_N
We consider the action of the Bethe algebra B_K on (\otimes_{s=1}^k
L_{\lambda^{(s)}})_\lambda, the weight subspace of weight of the
tensor product of k polynomial irreducible gl_N-modules with highest weights
\lambda^{(1)},...,\lambda^{(k)}, respectively. The Bethe algebra depends on N
complex numbers K=(K_1,...,K_N). Under the assumption that K_1,...,K_N are
distinct, we prove that the image of B_K in the endomorphisms of
(\otimes_{s=1}^k L_{\lambda^{(s)}})_\lambda is isomorphic to the algebra of
functions on the intersection of k suitable Schubert cycles in the Grassmannian
of N-dimensional spaces of quasi-exponentials with exponents K. We also prove
that the B_K-module (\otimes_{s=1}^k L_{\lambda^{(s)}})_\lambda is isomorphic
to the coregular representation of that algebra of functions. We present a
Bethe ansatz construction identifying the eigenvectors of the Bethe algebra
with points of that intersection of Schubert cycles.Comment: Latex, 29 page
High-field AFMR in single-crystalline La_{0.95}Sr_{0.05}MnO_3: Experimental evidence for the existence of a canted magnetic structure
High-field antiferromagnetic-resonance (AFMR) spectra were obtained in the
frequency range 60 GHz < \nu < 700 GHz and for magnetic fields up to 8 T in
twin-free single crystals of La_{0.95}Sr_{0.05}MnO_3. At low temperatures two
antiferromagnetic modes were detected, which reveal different excitation
conditions and magnetic field dependencies. No splitting of these modes was
observed for any orientation of the static magnetic field excluding the
phase-separation scenario for this composition. Instead, the full data set
including the anisotropic magnetization can be well described using a
two-sublattice model of a canted antiferromagnetic structure.Comment: 4 pages, 3 figure
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