4,069 research outputs found
Observed transition from Richtmyer-Meshkov jet formation through feedout oscillations to Rayleigh-Taylor instability in a laser target
Experimental study of hydrodynamic perturbation evolution triggered by a
laser-driven shock wave breakout at the free rippled rear surface of a plastic
target is reported. At sub-megabar shock pressure, planar jets manifesting the
development of the Richtmyer-Meshkov-type instability in a non-accelerated
target are observed. As the shock pressure exceeds 1 Mbar, an oscillatory
rippled expansion wave is observed, followed by the "feedout" of the
rear-surface perturbations to the ablation front and the development of the
Rayleigh-Taylor instability, which breaks up the accelerated target.Comment: 12 pages, 4 figure
Socio-economic status over the life-course and depressive symptoms in men and women in Eastern Europe
Objective: Research into social inequalities in depression has studied western populations but data from non-western countries are sparse. In this paper, we investigate the extent of social inequalities in depression in Eastern Europe, the relative importance of social position at different points of the life-course, and whether social patterning of depression differs between men and women.Method: A cross-sectional study examined 12,053 men and 13,582 women in Russia, Poland and the Czech Republic. Depressive symptoms (16 or above on the CESD-20) were examined in relation to socio-economic circumstances at three phases of the life-course: childhood (household amenities and father's education); own education; current circumstances (financial difficulties and possession of household items).Results: Pronounced social differences in depression exist in men and women throughout Eastern Europe. Depression was largely influenced by current circumstances rather than by early life or education, with effects stronger in Poland and Russia. Odds ratios in men for current disadvantage were 3.16 [95% CI: 2.57-3.89], 3.16 [2.74-3.64] and 2.17 [1.80-2.63] in Russia, Poland and the Czech Republic respectively. Social variables did not explain the female excess in depression, which varied from 2.91 [2.58-3.27] in Russia to 1.90 [1.74-2.08] in Poland. Men were more affected by adult disadvantage than women, leading to narrower sex differentials in the presence of disadvantage.Limitations: Cross-sectional data with recall of childhood conditions were used.Conclusion: Current social circumstances are the strongest influence on increased depressive symptoms in countries which have recently experienced social changes. (C) 2007 Elsevier B.V. All rights reserved
Twisted polaritonic crystals in thin van der Waals slabs
Polaritons - hybrid light-mater excitations - are very appealing for the
confinement of light at the nanoscale. Recently, different kinds of polaritons
have been observed in thin slabs of van der Waals (vdW) materials, with
particular interest focused on phonon polaritons (PhPs) - lattice vibrations
coupled to electromagnetic fields in the mid-infrared spectral range with - in
biaxial crystals, such as e.g. MoO3. In particular, hyperbolic PhPs - having
hyperbola-like shape of their isofrequency curves - in MoO3 can exhibit
ultra-high momenta and strongly directional in-plane propagation, promising
novel applications in imaging, sensing or thermal management at the nanoscale
and in a planar geometry. However, the excitation and manipulation of in-plane
hyperbolic PhPs have not yet been well studied and understood. Here we propose
a technological platform for the effective excitation and control of in-plane
hyperbolic PhPs based on polaritonic crystals (PCs) - lattices formed by
elements separated by distances comparable to the PhPs wavelength -, twisted
with respect to the natural vdW crystal axes. In particular, we develop a
general analytical theory valid for an arbitrary PC made in a thin biaxial
slab. As a practical example, we consider a twisted PC formed by rectangular
hole arrays made in MoO3 slab and demonstrate the excitation of Bragg
resonances tunable by the twisting angle. Our findings open novel avenues for
both fundamental studies of PCs in vdW crystals and the development of
mid-infrared sensing and photodetection application
A review on the fabrication and properties of platinum nanoparticles
© 2014 Advanced Study Center Co. Ltd. A review on chemical and physical preparation of platinum nanoparticles and some applications with these nanoparticles is presented. Application perspectives such fields as nanocatalysts, electrical conductivity, optics and nonlinear optics are demonstrated. Different parameters and condition of various fabrication technologies are considered and realized specific physical properties of platinum nanoparticles are discussed
Data-driven efficient score tests for deconvolution problems
We consider testing statistical hypotheses about densities of signals in
deconvolution models. A new approach to this problem is proposed. We
constructed score tests for the deconvolution with the known noise density and
efficient score tests for the case of unknown density. The tests are
incorporated with model selection rules to choose reasonable model dimensions
automatically by the data. Consistency of the tests is proved
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