130 research outputs found
A proposal of a UCN experiment to check an earthquake waves model
Elastic waves with transverse polarization inside incidence plane can create
longitudinal surface wave (LSW) after reflection from a free surface. At a
critical incidence angle this LSW accumulates energy density, which can be
orders of magnitude higher than energy density of the incident transverse wave.
A specially arranged vessel for storage of ultracold neutrons (UCN) can be used
to verify this effect.Comment: 8 pages 3 figures added a paragraph on vibrations along surface at
critical angl
On EPR paradox, Bell's inequalities and experiments which prove nothing
This article shows that the there is no paradox. Violation of Bell's
inequalities should not be identified with a proof of non locality in quantum
mechanics. A number of past experiments is reviewed, and it is concluded that
the experimental results should be re-evaluated. The results of the experiments
with atomic cascade are shown not to contradict the local realism. The article
points out flaws in the experiments with down-converted photons. The
experiments with neutron interferometer on measuring the "contextuality" and
Bell-like inequalities are analyzed, and it is shown that the experimental
results can be explained without such notions. Alternative experiment is
proposed to prove the validity of local realism.Comment: 27 pages, 8 figures. I edited a little the text and abstract I
corrected equations (49) and (50
Those wonderful elastic waves
We consider in a simple and general way elastic waves in isotropic and
anisotropic media, their polarization, speeds, reflection from interfaces with
mode conversion, and surface waves. Reflection of quasi transverse waves in
anisotropic media from a free surface is shown to be characterized by three
critical angles.Comment: 11 Figures 26 page
Surface roughness effect on ultracold neutron interaction with a wall and implications for computer simulations
We review the diffuse scattering and the loss coefficient in ultracold
neutron reflection from slightly rough surfaces, report a surprising reduction
in loss coefficient due to roughness, and discuss the possibility of transition
from quantum treatment to ray optics. The results are used in a computer
simulation of neutron storage in a recent neutron lifetime experiment that
re-ported a large discrepancy of neutron lifetime with the current particle
data value. Our partial re-analysis suggests the possibility of systematic
effects that were not included in this publication.Comment: 39 pages, 9 figures; additional calculations include
Coherent Schwinger Interaction from Darboux Transformation
The exactly solvable scalar-tensor potential of the four-component Dirac
equation has been obtained by the Darboux transformation method. The
constructed potential has been interpreted in terms of nucleon-nucleon and
Schwinger interactions of neutral particles with lattice sites during their
channeling Hamiltonians of a Schwinger type is obtained by means of the Darboux
transformation chain. The analitic structure of the Lyapunov function of
periodic continuation for each of the Hamiltonians of the family is considered.Comment: 12 pages, Latex, six figures; six sections, one figure adde
Rayleigh Imaging of Graphene and Graphene Layers
We investigate graphene and graphene layers on different substrates by
monochromatic and white-light confocal Rayleigh scattering microscopy. The
image contrast depends sensitively on the dielectric properties of the sample
as well as the substrate geometry and can be described quantitatively using the
complex refractive index of bulk graphite. For few layers (<6) the
monochromatic contrast increases linearly with thickness: the samples behave as
a superposition of single sheets which act as independent two dimensional
electron gases. Thus, Rayleigh imaging is a general, simple and quick tool to
identify graphene layers, that is readily combined with Raman scattering, which
provides structural identification.Comment: 8 pages, 9 figure
Entanglement production with multimode Bose-Einstein condensates in optical lattices
Deep optical lattices are considered, in each site of which there are many
Bose-condensed atoms. By the resonant modulation of trapping potentials it is
possible to transfer a macroscopic portion of atoms to the collective nonlinear
states corresponding to topological coherent modes. Entanglement can be
generated between these modes. By varying the resonant modulating field it is
possible to effectively regulate entanglement production in this multimode
multitrap system of Bose condensates.Comment: Latex file, 16 pages, 7 figure
Exploring the limits of single emitter detection in fluorescence and extinction
We present an experimental comparison and a theoretical analysis of the
signal-to-noise ratios in fluorescence and extinction spectroscopy of a single
emitter. We show that extinction measurements can be advantageous if the
emitter is weakly excited. Furthermore, we discuss the potential of this method
for the detection and spectroscopy of weakly emitting systems such as rare
earth ions.Comment: 11 pages, 5 figure
Fitness Ranking of Individual Mutants Drives Patterns of Epistatic Interactions in HIV-1
This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Синтез новых производных арилкарбоновых кислот, содержащих гетероциклические заместители
The method for preparation of new substituted arylcarboxylic acids containing the amino function, that are the key precursors for new functionally substituted amides, has been described.Путем прямого восстановительного алкилирования 2-ариламинопиримидинов и первичных ароматических (гетероароматических) аминов осуществлен синтез новых замещенных арилкарбоновых кислот, содержащих в молекуле аминную функциональность, которые являются ключевыми синтетическими предшественниками новых функционализированных амидов
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