4,157 research outputs found
Lipschitz shadowing implies structural stability
We show that the Lipschitz shadowing property of a diffeomorphism is
equivalent to structural stability. As a corollary, we show that an expansive
diffeomorphism having the Lipschitz shadowing property is Anosov.Comment: 11 page
Experimental evidence of planar channeling in a periodically bent crystal
The usage of a Crystalline Undulator (CU) has been identified as a promising
solution for generating powerful and monochromatic -rays. A CU was
fabricated at SSL through the grooving method, i.e., by the manufacturing of a
series of periodical grooves on the major surfaces of a crystal. The CU was
extensively characterized both morphologically via optical interferometry at
SSL and structurally via X-ray diffraction at ESRF. Then, it was finally tested
for channeling with a 400 GeV/c proton beam at CERN. The experimental results
were compared to Monte Carlo simulations. Evidence of planar channeling in the
CU was firmly observed. Finally, the emission spectrum of the positron beam
interacting with the CU was simulated for possible usage in currently existing
facilities
Local Ferroelectricity in SrTiO_3 Thin Films
The temperature-dependent polarization of SrTiO_3 thin films is investigated
using confocal scanning optical microscopy. A homogeneous out-of-plane and
inhomogeneous in-plane ferroelectric phase are identified from images of the
linear electrooptic response. Both hysteretic and non-hysteretic behavior are
observed under a dc bias field. Unlike classical transitions in bulk
ferroelectrics, local ferroelectricity is observed at temperatures far above
the dielectric permittivity maximum. The results demonstrate the utility of
local probe experiments in understanding inhomogeneous ferroelectrics.Comment: 8 pages, 3 figures, accepted for publication in PR
Подходы к определению ставки дисконтирования в проектном финансировании: отечественный и международный опыт
Дисконтирование денежных потоков сегодня широко используется в практике оценки стоимости бизнеса, проектном финансировании, при составлении финансовой отчетности. При этом подходы к расчету ставки дисконтирования могут различаться в зависимости от объекта и цели анализа, вида денежного потока, имеющихся источников информации и подходов конкретных стандартов оценки или финансовой отчетности, аналитиков, банков, профессиональных сообществ.В статье рассмотрены подходы к определению основных компонентов наиболее часто применяемой методологии расчета ставки — средневзвешенной стоимости капитала компании. Акцент сделан на выбор между плавающей и фиксированной ставками, определение стоимости заемного финансирования, премии за акционерный риск, а также наиболее субъективного компонента — премии за специфический риск компании или проекта.Дополнительно в статье представлены результаты эмпирического исследования — обзора ставок крупнейших отечественных компаний, раскрытых в их финансовой отчетности
Meson vacuum phenomenology in a three-flavor linear sigma model with (axial-)vector mesons
We study scalar, pseudoscalar, vector, and axial-vector mesons with
non-strange and strange quantum numbers in the framework of a linear sigma
model with global chiral symmetry. We perform a
global fit of meson masses, decay widths, as well as decay amplitudes. The
quality of the fit is, for a hadronic model that does not consider
isospin-breaking effects, surprisingly good. We also investigate the question
whether the scalar states lie below or above 1 GeV and find the
scalar states above 1 GeV to be preferred as states. Additionally,
we also describe the axial-vector resonances as states.Comment: 29 pages, 4 figures, 3 tables. v2 is the updated version after
referee remarks (dilaton field discussed, a new figure added
DANSSino: a pilot version of the DANSS neutrino detector
DANSSino is a reduced pilot version of a solid-state detector of reactor
antineutrinos (to be created within the DANSS project and installed under the
industrial 3 GW(th) reactor of the Kalinin Nuclear Power Plant -- KNPP).
Numerous tests performed at a distance of 11 m from the reactor core
demonstrate operability of the chosen design and reveal the main sources of the
background. In spite of its small size (20x20x100 ccm), the pilot detector
turned out to be quite sensitive to reactor antineutrinos, detecting about 70
IBD events per day with the signal-to-background ratio about unity.Comment: 16 pages, 11 figures, 3 tables. arXiv admin note: substantial text
overlap with arXiv:1304.369
Predictability in the large: an extension of the concept of Lyapunov exponent
We investigate the predictability problem in dynamical systems with many
degrees of freedom and a wide spectrum of temporal scales. In particular, we
study the case of turbulence at high Reynolds numbers by introducing a
finite-size Lyapunov exponent which measures the growth rate of finite-size
perturbations. For sufficiently small perturbations this quantity coincides
with the usual Lyapunov exponent. When the perturbation is still small compared
to large-scale fluctuations, but large compared to fluctuations at the smallest
dynamically active scales, the finite-size Lyapunov exponent is inversely
proportional to the square of the perturbation size. Our results are supported
by numerical experiments on shell models. We find that intermittency
corrections do not change the scaling law of predictability. We also discuss
the relation between finite-size Lyapunov exponent and information entropy.Comment: 4 pages, 2 Postscript figures (included), RevTeX 3.0, files packed
with uufile
Moduli of mathematical instanton vector bundles with odd c_2 on projective space
The problem of irreducibility of the moduli space I_n of rank-2 mathematical
instanton vector bundles with arbitrary positive second Chern class n on the
projective 3-space is considered. The irreducibility of I_n was known for small
values of n: Barth 1977 (n=1), Hartshorne 1978 (n=2), Ellingsrud and Stromme
1981 (n=3), Barth 1981 (n=4), Coanda, Tikhomirov and Trautmann 2003 (n=5). In
this paper we prove the irreducibility of I_n for an arbitrary odd n.Comment: 62 page
Erbium-doped tellurite glasses with high quantum efficiency and broadband stimulated emission cross section at 1.5 μm
Optical transitions of Er3+ ion in two tellurite glasses of molar composition 75TeO2:12ZnO:10Na2O:2PbO:1Er2O3 and 75TeO2:12ZnO:10Na2O:2GeO2:1Er2O3 were investigated. The measured absorption and emission spectra were analysed by Judd–Ofelt and McCumber theories, in order to obtain radiative transition rates and stimulated emission cross sections. It was found that these glasses have high and broadband absorption and stimulated emission cross sections at 1.5 μm. For the metastable 4I13/2level, by comparing the measured lifetime with the calculated radiative decay time, quantum efficiency higher than 80% was found
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