Femtosecond transparency in the extreme ultraviolet

Electromagnetically induced transparency-like behavior in the extreme ultraviolet (XUV) is studied theoretically, including the effect of intense 800 nm laser dressing of He 2s2p (1Po) and 2p^2 (1Se) autoionizing states. We present an ab initio solution of the time-dependent Schrodinger equation (TDSE) in an LS-coupling configuration interaction basis set. The method enables a rigorous treatment of optical field ionization of these coupled autoionizing states into the N = 2 continuum in addition to N = 1. Our calculated transient absorption spectra show encouraging agreement with experiment.Comment: 25 pages, 7 figures, 1 tabl

Influence of Health Status on the Association Between Diabetes and Depression Among Adults in Europe: Findings From the SHARE International Survey.

The association between diabetes and depression, a common health comorbidity in people with diabetes, has been recognized but not well understood. The purpose of this study was to explore the association between diabetes and depression in a large international sample of adults, adjusting for demographics, socioeconomic status, behavioral risks, and current health status. The association between diabetes and depression was assessed in a sample of 57,004 Europeans ≥50 years of age from 15 European countries using data from the fifth wave of SHARE (the Survey of Health, Ageing, and Retirement in Europe). Multiple logistic regression models of the association between diabetes and depression were conducted, adjusting for potential confounders. Analyses showed that, despite diabetes being associated with depression in crude and partially adjusted models, further adjustment for self-perceived health made the association between diabetes and depression no longer statistically significant (odds ratio 1.0, 95% CI 0.9-1.0). Adjustment for a variety of demographic, socioeconomic, behavioral risk, and health status variables reduced the estimated association between diabetes and depression until it was no longer significant. Further research should explore the specific symptoms of distress characterized in people with diabetes

Dynamics of a one-dimensional spinor Bose liquid: a phenomenological approach

The ground state of a spinor Bose liquid is ferromagnetic, while the softest excitation above the ground state is the magnon mode. The dispersion relation of the magnon in a one-dimensional liquid is periodic in the wavenumber q with the period 2\pi n, determined by the density n of the liquid. Dynamic correlation functions, such as e.g. spin-spin correlation function, exhibit power-law singularities at the magnon spectrum, $\omega\to\omega_m(q,n)$. Without using any specific model of the inter-particle interactions, we relate the corresponding exponents to independently measurable quantities $\partial\omega_m/\partial q$ and $\partial\omega_m/\partial n$.Comment: 4 pages

Electric field induced strong localization of electrons on solid hydrogen surface: possible applications to quantum computing

Two-dimensional electron system on the liquid helium surface is one of the leading candidates for constructing large analog quantum computers (P.M. Platzman and M.I. Dykman, Science 284, 1967 (1999)). Similar electron systems on the surfaces of solid hydrogen or solid neon may have some important advantages with respect to electrons on liquid helium in quantum computing applications, such as larger state separation $\Delta E$, absence of propagating capillary waves (or ripplons), smaller vapor pressure, etc. As a result, it may operate at higher temperatures. Surface roughness is the main hurdle to overcome in building a realistic quantum computer using these states. Electric field induced strong localization of surface electrons is shown to be a convenient tool to characterize surface roughness.Comment: 4 pages, 3 figure

On the possibility to supercool molecular hydrogen down to superfluid transition

Recent calculations by Vorobev and Malyshenko (JETP Letters, 71, 39, 2000) show that molecular hydrogen may stay liquid and superfluid in strong electric fields of the order of $4\times 10^7 V/cm$. I demonstrate that strong local electric fields of similar magnitude exist beneath a two-dimensional layer of electrons localized in the image potential above the surface of solid hydrogen. Even stronger local fields exist around charged particles (ions or electrons) if surface or bulk of a solid hydrogen crystal is statically charged. Measurements of the frequency shift of the $1 \to 2$ photoresonance transition in the spectrum of two-dimensional layer of electrons above positively or negatively charged solid hydrogen surface performed in the temperature range 7 - 13.8 K support the prediction of electric field induced surface melting. The range of surface charge density necessary to stabilize the liquid phase of molecular hydrogen at the temperature of superfluid transition is estimated.Comment: 5 pages, 2 figure

Statistical equilibrium of silicon in the solar atmosphere

The statistical equilibrium of neutral and ionised silicon in the solar photosphere is investigated. Line formation is discussed and the solar silicon abundance determined. High-resolution solar spectra were used to determine solar $\log gf\epsilon_{\rm Si}$ values by comparison with Si line synthesis based on LTE and NLTE level populations. The results will be used in a forthcoming paper for differential abundance analyses of metal-poor stars. A detailed analysis of silicon line spectra leads to setting up realistic model atoms, which are exposed to interactions in plane-parallel solar atmospheric models. The resulting departure coefficients are entered into a line-by-line analysis of the visible and near-infrared solar silicon spectrum. The statistical equilibrium of \ion{Si}{i} turns out to depend marginally on bound-free interaction processes, both radiative and collisional. Bound-bound interaction processes do not play a significant role either, except for hydrogen collisions, which have to be chosen adequately for fitting the cores of the near-infrared lines. Except for some near-infrared lines, the NLTE influence on the abundances is weak. Taking the deviations from LTE in silicon into account, it is possible to calculate the ionisation equilibrium from neutral and ionised lines. The solar abundance based on the experimental $f$-values of Garz corrected for the Becker et al.'s measurement is $7.52 \pm 0.05$. Combined with an extended line sample with selected NIST $f$-values, the solar abundance is $7.52 \pm 0.06$, with a nearly perfect ionisation equilibrium of \Delta\log\epsilon_\odot(\ion{Si}{ii}/\ion{Si}{i}) = -0.01.Comment: 13pages 10 figures. A&A acceptte

О разрешимости бездефектности для сетей потоков работ с неограниченным ресурсом

In this work, we consider the modeling of workflow systems with Petri nets. A resource workflow net (RWF-net) is a workflow net supplied with an additional set of initially marked resource places. Resources can be consumed and/or produced by transitions. We constrain neither the intermediate nor final resource markings, hence a net can have an infinite number of different reachable states. An initially marked RWF-net is called sound if it properly terminates its work and, moreover, an increase of the initial resource does not violate its proper termination. An unmarked RWF-net is sound if it is sound for some initial resource. In this paper, we prove the decidability of both marked and unmarked soundness for a restricted class of RWF-nets with a single unbounded resource place (1-dim RWF-nets). We present an algorithm for computing the minimal sound resource for a given sound 1-dim RWF-net.Рассматривается моделирование схем потоков работ (workflow) при помощи сетей Петри. Определяется класс сетей потоков работ с ресурсами (RWF- сетей) — обычных workflow-сетей, в которых дополнительно добавлено множество ресурсных позиций, содержащих какую-то начальную разметку (начальный ресурс). Ресурсы могут уничтожаться и производиться при срабатываниях переходов. Мы не накладываем ограничений ни на промежуточные, ни на финальные ресурсные разметки, поэтому сеть может порождать бесконечное множество различных достижимых состояний. RWF-сеть с данной начальной ресурсной разметкой называется бездефектной, если, во-первых, она всегда корректно завершает свою работу, и, во- вторых, любое увеличение начального ресурса не нарушает свойства корректного завершения. Неразмеченная RWF-сеть бездефектна, если она бездефектна при некоторой начальной ресурсной разметке. В данной работе доказана разрешимость обоих вариантов бездефектности для важного подкласса RWF- сетей — сетей с одномерным ресурсом (одной ресурсной позицией). Также представлен алгоритм вычисления наименьшего бездефектного ресурса

Однородные супермногообразия с ретрактом CP (1|4, k1k2 11)

We give the results of classification of all nonsplit homogeneous supermanifolds over the complex projective line whose retract is corresponding to a holomorphic vector bundle with a set (k1, k2,1,1), where k1 >= k2 >= 1. See [3] and [4] for more information about the complex supermanifolds theory.Излагаются результаты классификации однородных нерасщепимых супермногообразий, связанных с комплексной проективной прямой в случае, когда ретракт определяется векторным расслоением с сигнатурой (ki, k2,1,1), где к >= к2 >= 1. Необходимые сведения по теории комплексных супермногообразий можно найти в [3] и [4]

Guiding and Trapping Electron Spin Waves in Atomic Hydrogen Gas

We present a high magnetic field study of electron spin waves in atomic hydrogen gas compressed to high densities of 10^18 cm^-3 at temperatures ranging from 0.26 to 0.6 K. We observed a variety of spin wave modes caused by the identical spin rotation effect with strong dependence on the spatial profile of the polarizing magnetic field. We demonstrate confinement of these modes in regions of strong magnetic field and manipulate their spatial distribution by changing the position of the field maximum.Comment: 5 pages, 4 figure

Collective dynamics of internal states in a Bose gas

Theory for the Rabi and internal Josephson effects in an interacting Bose gas in the cold collision regime is presented. By using microscopic transport equation for the density matrix the problem is mapped onto a problem of precession of two coupled classical spins. In the absence of an external excitation field our results agree with the theory for the density induced frequency shifts in atomic clocks. In the presence of the external field, the internal Josephson effect takes place in a condensed Bose gas as well as in a non-condensed gas. The crossover from Rabi oscillations to the Josephson oscillations as a function of interaction strength is studied in detail.Comment: 18 pages, 2 figure