596 research outputs found
A symplectic realization of the Volterra lattice
We examine the multiple Hamiltonian structure and construct a symplectic
realization of the Volterra model. We rediscover the hierarchy of invariants,
Poisson brackets and master symmetries via the use of a recursion operator. The
rational Volterra bracket is obtained using a negative recursion operator.Comment: 8 page
Spectral signatures of the Luttinger liquid to charge-density-wave transition
Electron- and phonon spectral functions of the one-dimensional,
spinless-fermion Holstein model at half filling are calculated in the four
distinct regimes of the phase diagram, corresponding to an attractive or
repulsive Luttinger liquid at weak electron-phonon coupling, and a band- or
polaronic insulator at strong coupling. The results obtained by means of kernel
polynomial and systematic cluster approaches reveal substantially different
physics in these regimes and further indicate that the size of the phonon
frequency significantly affects the nature of the quantum Peierls phase
transition.Comment: 5 pages, 4 figures; final version, accepted for publication in
Physical Review
Robotised program conducting out laboratory works of chemistry
In a message addressed the conditions necessary and sufficient for creating robotised program for laboratory work in chemistry as an element of innovation-axiological approach in educationВ сообщении рассмотрены условия необходимые и достаточные для создания роботизированной программы проведения лабораторных работ по химии как элемента инновационно-аксиологического подхода в образовани
ACID-CATALYZED REARRANGEMENT OF FURYL-TETHERED OXIMES: SYNTHESIS OF FUNCTIONALIZED PYRROLES
Polyarylated pyrroles have extensively utilized as building-blocks in material science. High demand for functionalyzed pyrrole substrates motivated us to develop a general synthetic protocol toward such valuable compounds based on furan dearomatization approach.This work was supported by the Russian Foundation for Basic Research, project # 01-01-00001
Low Momentum Scattering in the Dirac Equation
It is shown that the amplitude for reflection of a Dirac particle with
arbitrarily low momentum incident on a potential of finite range is -1 and
hence the transmission coefficient T=0 in general. If however the potential
supports a half-bound state at k=0 this result does not hold. In the case of an
asymmetric potential the transmission coefficient T will be non-zero whilst for
a symmetric potential T=1.Comment: 12 pages; revised to include additional references; to be published
in J Phys
Global Alfven Wave Heating of the Magnetosphere of Young Stars
Excitation of a Global Alfven wave (GAW) is proposed as a viable mechanism to
explain plasma heating in the magnetosphere of young stars. The wave and basic
plasma parameters are compatible with the requirement that the dissipation
length of GAWs be comparable to the distance between the shocked region at the
star's surface and the truncation region in the accretion disk. A two-fluid
magnetohydrodynamic plasma model is used in the analysis. A current carrying
filament along magnetic field lines acts as a waveguide for the GAW. The
current in the filament is driven by plasma waves along the magnetic field
lines and/or by plasma crossing magnetic field lines in the truncated region of
the disk of the accreting plasma. The conversion of a small fraction of the
kinetic energy into GAW energy is sufficient to heat the plasma filament to
observed temperatures.Comment: Submitted to ApJ, aheatf.tex, 2 figure
Multitemporal generalization of the Tangherlini solution
The n-time generalization of the Tangherlini solution [1] is considered. The
equations of geodesics for the metric are integrated. For it is shown
that the naked singularity is absent only for two sets of parameters,
corresponding to the trivial extensions of the Tangherlini solution. The motion
of a relativistic particle in the multitemporal background is considered. This
motion is governed by the gravitational mass tensor. Some generalizations of
the solution, including the multitemporal analogue of the Myers-Perry charged
black hole solution, are obtained.Comment: 14 pages. RGA-CSVR-005/9
Submesoscale physicochemical dynamics directly shape bacterioplankton community structure in space and time
Submesoscale eddies and fronts are important components of oceanic mixing and energy fluxes. These phenomena occur in the surface ocean for a period of several days, on scales between a few hundred meters and few tens of kilometers. Remote sensing and modeling suggest that eddies and fronts may influence marine ecosystem dynamics, but their limited temporal and spatial scales make them challenging for observation and in situ sampling. Here, the study of a submesoscale filament in summerly Arctic waters (depth 0–400 m) revealed enhanced mixing of Polar and Atlantic water masses, resulting in a ca. 4 km wide and ca. 50 km long filament with distinct physical and biogeochemical characteristics. Compared to the surrounding waters, the filament was characterized by a distinct phytoplankton bloom, associated with depleted inorganic nutrients, elevated chlorophyll a concentrations, as well as twofold higher phyto- and bacterioplankton cell abundances. High-throughput 16S rRNA gene sequencing of bacterioplankton communities revealed enrichment of typical phytoplankton bloom-associated taxonomic groups (e.g., Flavobacteriales) inside the filament. Furthermore, linked to the strong water subduction, the vertical export of organic matter to 400 m depth inside the filament was twofold higher compared to the surrounding waters. Altogether, our results show that physical submesoscale mixing can shape distinct biogeochemical conditions and microbial communities within a few kilometers of the ocean. Hence, the role of submesoscale features in polar waters for surface ocean biodiversity and biogeochemical processes need further investigation, especially with regard to the fate of sea ice in the warming Arctic Ocean
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