5,595 research outputs found

    The nucleosynthesis of deterium and helium-3

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    A new model of the creation of D and 3He in supernova of the first generation was considered. It is based on the idea that a supernova event leads simultaneously to acceleration of particles in the shock wave front and to their interactions with supernova atmosphere matter. The D, 3He, Li, Be, B and bypassed isotopes are created in these interactions. The cosmic abundances of the bypassed isotopes with A or = 113 allowed to determine the integral proton flux I sub p (E sub p 25 MeV) = 5 x 10 to the 21/sq cm the spectral index - gamma = 3. The calculations of the D and 3He yields in various nuclear reactions at these irradiation conditions show that only the 4He(p,d)3He reaction leads to cosmic abundances of these isotopes on the assumption that all matter has been exposed

    Cold air outbreaks and their signature in the ozonometric data at the mountain station near Kislovodsk, Russia

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    International audienceTwo cases of cold air outbreak in November 2001 are analyzed on the basis of ozone concentration measurements and weather data at the mountain station (43°44' N, 42°43 E, 2070 m a.s.l.) near Kislovodsk, North Caucasus, Russia. Two cold fronts, with fast clearing up in the rear of the cloud zone, passed the station in the morning of 12 and 16 November. In both cases, the ozone concentration drops down to 7?8 ppb within the frontal cloud zones, under 100% relative humidity, RH, and then sharply increases to 43?45 ppb in dry (RH about 50%), cold air during several hours. After a warm front passage (12 November) or RH growth in the cold post-frontal airmass (16 November), the ozone concentration decreases again to its average values near 30 ppb. Neither diurnal cycle nor photochemical generation could produce in the ozonometric data this specific "drop-and-peak'' signature which is considered to be caused by cold outbreak with post-frontal flow of "dry air stream'' type. Synoptic situation and tropopause topography are analyzed using the objective analysis data and METEOSAT images in the water vapor radiation band. It is concluded that the ozone growth in the rear of the cold fronts is associated with sinking of substratospheric or stratospherically influenced air from the areas of tropopause folding. Motion of cold surges with their frontal zones, jet streams, and tropopause folds is analyzed, including development of wave disturbances at the streamers and formation of substratospheric air "tongues'' underflowing the high tropopause and representing "aged'' intrusions

    Optical studies of the X-ray transient XTE J2123-058 -I. Photometry

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    We present optical photometry of the X-ray transient XTE J2123-058, obtained in July-October 1998. The light curves are strongly modulated on the 5.95hrs orbital period, and exhibit dramatic changes in amplitude and form during the decline. We used synthetic models which include the effect of partial eclipses and X-ray heating effects, to estimate the system parameters, and we constrain the binary inclination to be i=73+-4 degrees. The model is successful in reproducing the light curves at different stages of the decay by requiring the accretion disc to become smaller and thinner by 30% as the system fades by 1.7 mags in the optical. From Aug 26 the system reaches quiescence with a mean magnitude of R=21.7+-0.1 and our data are consistent with the optical variability being dominated by the companion's ellipsoidal modulation.Comment: 6 pages, 6 figure

    Formation of human capital as a key factor in ensuring the national security of agriculture in the digital economy

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    Over the past few years in many literary sources and the media an issue of the digital economy is rapidly gaining popularity due to the qualitative technological changes in society. In current circumstances the qualitative component of labor resources called “human capital” is a priority value. The authors have identified the main realities of the development of agribusiness, studied the main directions of information support on the example of the agricultural sector of the economy and identified the root causes of the slowdown in the innovation development of agriculture in Russia, the features of using information technologies in agribusiness have been considered in detail.peer-reviewe

    Constructions of regular algebras Lpw(G)L_p^w(G)

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    Criterion of (Shilov) regularity for weighted algebras L1w(G)L_1^w(G) on a locally compact abelian group GG is known by works of Beurling (1949) and Domar (1956). In the present paper this criterion is extended to translation invariant weighted algebras Lpw(G)L_p^w(G) with p>1p>1. Regular algebras Lpw(G)L_p^w(G) are constructed on any sigma-compact abelian group GG. It was proved earlier by the author that sigma-compactness is necessary (in the abelian case) for the existence of weighted algebras Lpw(G)L_p^w(G) with p>1p>1.Comment: Submitted to Mat. Sborni

    A photoelectron spectroscopy study of the electronic structure evolution in CuInSe2-related compounds at changing copper content

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    Evolution of the valence-band structure at gradually increasing copper content has been analysed by x-ray photoelectron spectroscopy (XPS) in In2Se3, CuIn5Se8, CuIn3Se5, and CuInSe2 single crystals. A comparison of these spectra with calculated total and angular-momentum resolved density-of-states (DOS) revealed the main trends of this evolution. The formation of the theoretically predicted gap between the bonding and non-bonding states has been observed in both experimental XPS spectra and theoretical DOS

    Engineering chiral spin interactions with Rydberg atoms

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    We propose to simulate the anisotropic and chiral Dzyaloshinskii-Moriya (DM) interaction with Rydberg atom arrays. The DM Hamiltonian is engineered in a one-dimensional optical lattice or trap array with effective long-range Rydberg spins, interacting indirectly via a mobile mediator Rydberg atom. A host of XXZ and DM Hamiltonians can be simulated with out-of-phase sign periodic coupling strengths; for initial states in a stationary condensate, the DM interaction vanishes. This theory allows for determination of the DM interaction (DMI) vector components from first principles. The inherent anisotropy of the Rydberg-Rydberg interactions, facilitates the DMI coupling to be tuned so as to be comparable to the XXZ interaction. Our results make plausible the formation of non-trivial topological spin textures with Rydberg atom arrays.Comment: 4 pages, 2 figure
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