Understanding the dynamical structure of pulsating stars: The Baade-Wesselink projection factor of the delta Scuti stars AI Vel and beta Cas

Aims. The Baade-Wesselink method of distance determination is based on the oscillations of pulsating stars. The key parameter of this method is the projection factor used to convert the radial velocity into the pulsation velocity. Our analysis was aimed at deriving for the first time the projection factor of delta Scuti stars, using high-resolution spectra of the high-amplitude pulsator AI Vel and of the fast rotator beta Cas. Methods. The geometric component of the projection factor (i.e. p0) was calculated using a limb-darkening model of the intensity distribution for AI Vel, and a fast-rotator model for beta Cas. Then, using SOPHIE/OHP data for beta Cas and HARPS/ESO data for AI Vel, we compared the radial velocity curves of several spectral lines forming at different levels in the atmosphere and derived the velocity gradient associated to the spectral-line-forming regions in the atmosphere of the star. This velocity gradient was used to derive a dynamical projection factor p. Results. We find a flat velocity gradient for both stars and finally p = p0 = 1.44 for AI Vel and p = p0 = 1.41 for beta Cas. By comparing Cepheids and delta Scuti stars, these results bring valuable insights into the dynamical structure of pulsating star atmospheres. They suggest that the period-projection factor relation derived for Cepheids is also applicable to delta Scuti stars pulsating in a dominant radial mode

Paramecium tredecaurelia: A Unique Non-Polymorphic Species of the P. aurelia spp. Complex (Oligohymenophorea, Ciliophora)

New stands of Paramecium tredecaurelia, a rare species of the P. aurelia spp. complex, were identified in Thailand and Madagascar on the basis of mating reactions and molecular markers (rDNA and mtDNA). Analysis of DNA fragments showed that all P. tredecaurelia strains, the recently recorded ones and the ones known previously from France, Mexico, and Israel, form a monophyletic and well-defined clade in the P. aurelia species trees. All of these strains, collected from different localities around the world, represent identical or nearly identical haplotypes in terms of all the studied DNA fragments. Given the huge distances between particular collection sites, such a low level of variability of the studied sequences may result from a slow rate of evolution in P. tredecaurelia

THE IMPROVEMENT OF PUBLIC PROCUREMENT MANAGEMENT AT GOVERNMENT AGENCIES OF MOSCOW

The arguments proving the need for the improvement of public procurement management at government agencies of Moscow are presented. The practice of the Federal Law № 44 published 5 April 2013, provisions application related to setting up of a contract service in sphere of public procurement is considered by the example of the authority of the South-Eastern administrative district of Moscow

THE IMPROVEMENT OF PUBLIC PROCUREMENT MANAGEMENT AT GOVERNMENT AGENCIES OF MOSCOW

The arguments proving the need for the improvement of public procurement management at government agencies of Moscow are presented. The practice of the Federal Law № 44 published 5 April 2013, provisions application related to setting up of a contract service in sphere of public procurement is considered by the example of the authority of the South-Eastern administrative district of Moscow

Estimating the efficiency of two algorithms for segmentation of digital radiation images of test objects

A mathematical model that describes digital radiation images of test objects is presented. Two algorithms are given for automatic segmentation of digital images distorted by additive noises. The efficiency of the algorithms is estimated based on mathematical modeling

Superconductivity in Nanostructured Ga-Ag Eutectic Alloy

The dc and ac magnetizations were studied for the eutectic Ga-Ag alloy embedded into a porous glass with 7 nm mean pore size. The measurements were performed within a temperature range of 1.9 to 10 K which covers the superconducting transition for the nanocomposite. The onset of superconductivity at the magnetic field 10 Oe was found at about 7.1 K which is much higher than in bulk gallium. The phase diagram showed a positive curvature at low magnetic fields. The activation energy of vortex mobility was calculated at different magnetic fields using the ac data.     Keywords: Ga-Ag eutectic alloy, superconductivity, nanoconfinemen

N-(Adamantan-1-yl)-2-chloro­acetamide

In the title compound, C12H18ClNO, which was synthesized as part of a study into potential anti­tuberculosis agents, the adamantine skeleton displays shorter than normal C—C bond lengths ranging between 1.5293 (18) and 1.5366 (15) Å. The structure also displays inter­molecular N—H⋯O hydrogen bonding, which forms an infinite chain in the a-axis direction

Right Ventricular Compression Observed in Echocardiography from Pectus Excavatum Deformity

Pectus excavatum exists as varying anatomic deformities and compression of the right heart by the chest wall can lead to patient symptoms including dyspnea and chest pain with exertion. Echocardiography can be difficult but is critical to the evaluation and diagnosis of this patient population. Modifying standard views such as biplane transthoracic and 3-D transesophageal views may be necessary in some patients due to limitations from the abnormal anatomy of the deformed anterior chest wall. Apical four-chamber views when seen clearly can usually visualize any extrinsic compression to the right ventricle of the heart

Mass-luminosity relation and pulsational properties of Wolf-Rayet stars

Evolution of Population I stars with initial masses from 70M_\odot to 130M_\odot is considered under various assumptions on the mass loss rate \dot M. The mass-luminosity relation of W-R stars is shown to be most sensitive to the mass loss rate during the helium burning phase \dot M_{3\alpha}. Together with the mass-luminosity relation obtained for all evolutionary sequences several more exact relations are determined for the constant ratio f_{3\alpha}=\dot M/\dot M_{3\alpha} with 0.5 \le f_{3\alpha} \le 3. Evolutionary models of W-R stars were used as initial conditions in hydrodynamic computations of radial nonlinear stellar oscillations. The oscillation amplitude is larger in W-R stars with smaller initial mass or with lower mass loss rate due to higher surface abundances of carbon and oxygen. In the evolving W-R star the oscillation amplitude decreases with decreasing stellar mass M and for M < 10M_\odot the sufficiently small nonlinear effects allow us to calculate the integral of the mechanical work W done over the pulsation cycle in each mass zone of the hydrodynamical model. The only positive maximum on the radial dependence of W is in the layers with temperature of T\sim 2e5K where oscillations are excited by the iron Z--bump kappa-mechanism. Radial oscillations of W-R stars with mass of M > 10M_\odot are shown to be also excited by the kappa-mechanism but the instability driving zone is at the bottom of the envelope and pulsation motions exist in the form of nonlinear running waves propagating outward from the inner layers of the envelope.Comment: 15 pages, 10 figures, submitted to Astronomy Letter

Variability in Proto-Planetary Nebulae: I. Light Curve Studies of 12 Carbon-Rich Objects

We have carried out long-term (14 years) V and R photometric monitoring of 12 carbon-rich proto-planetary nebulae. The light and color curves display variability in all of them. The light curves are complex and suggest multiple periods, changing periods, and/or changing amplitudes, which are attributed to pulsation. A dominant period has been determined for each and found to be in the range of ~150 d for the coolest (G8) to 35-40 d for the warmest (F3). A clear, linear inverse relationship has been found in the sample between the pulsation period and the effective temperature and also an inverse linear relationship between the amplitude of light variation and the effective temperature. These are consistent with the expectation for a pulsating post-AGB star evolving toward higher temperature at constant luminosity. The published spectral energy distributions and mid-infrared images show these objects to have cool (200 K), detached dust shells and published models imply that intensive mass loss ended a few thousand years ago. The detection of periods as long as 150 d in these requires a revision in the published post-AGB evolution models that couple the pulsation period to the mass loss rate and that assume that intensive mass loss ended when the pulsation period had decreased to 100 d. This revision will have the effect of extending the time scale for the early phases of post-AGB evolution. It appears that real time evolution in the pulsation periods of individual objects may be detectable on the time scale of two decades