Improved Log(gf) Values for Lines of Ti I and Abundance Determinations in the Photospheres of the Sun and Metal-Poor Star HD 84937 (Accurate Transition Probabilities for Ti I)

New atomic transition probability measurements for 948 lines of Ti I are reported. Branching fractions from Fourier transform spectra and from spectra recorded using a 3 m echelle spectrometer are combined with published radiative lifetimes from laser-induced fluorescence measurements to determine these transition probabilities. Generally good agreement is found in comparisons to the NIST Atomic Spectra Database. The new Ti I data are applied to re-determine the Ti abundance in the photospheres of the Sun and metal-poor star HD 84937 using many lines covering a range of wavelength and excitation potential to explore possible non-local thermal equilibrium effects. The variation of relative Ti/Fe abundance with metallicity in metal-poor stars observed in earlier studies is supported in this study.NSF AST-1211055, AST-0908978, AST-1211585NSF REU grant AST-1004881ESO Science Archive Facility 073.D-0024, 266.D-5655NASA NAS 5-26555Astronom

Comparing Strategies to Prevent Stroke and Ischemic Heart Disease in the Tunisian Population: Markov Modeling Approach Using a Comprehensive Sensitivity Analysis Algorithm.

Background. Mathematical models offer the potential to analyze and compare the effectiveness of very different interventions to prevent future cardiovascular disease. We developed a comprehensive Markov model to assess the impact of three interventions to reduce ischemic heart diseases (IHD) and stroke deaths: (i) improved medical treatments in acute phase, (ii) secondary prevention by increasing the uptake of statins, (iii) primary prevention using health promotion to reduce dietary salt consumption. Methods. We developed and validated a Markov model for the Tunisian population aged 35–94 years old over a 20-year time horizon. We compared the impact of specific treatments for stroke, lifestyle, and primary prevention on both IHD and stroke deaths. We then undertook extensive sensitivity analyses using both a probabilistic multivariate approach and simple linear regression (metamodeling). Results. The model forecast a dramatic mortality rise, with 111,134 IHD and stroke deaths (95% CI 106567 to 115048) predicted in 2025 in Tunisia. The salt reduction offered the potentially most powerful preventive intervention that might reduce IHD and stroke deaths by 27% (−30240 [−30580 to −29900]) compared with 1% for medical strategies and 3% for secondary prevention. The metamodeling highlighted that the initial development of a minor stroke substantially increased the subsequent probability of a fatal stroke or IHD death. Conclusions. The primary prevention of cardiovascular disease via a reduction in dietary salt consumption appeared much more effective than secondary or tertiary prevention approaches. Our simple but comprehensive model offers a potentially attractive methodological approach that might now be extended and replicated in other contexts and populations

The Nature of Nearby Counterparts to Intermediate Redshift Luminous Compact Blue Galaxies I. Optical/H I Properties and Dynamical Masses

We present single-dish H I spectra obtained with the Green Bank Telescope, along with optical photometric properties from the Sloan Digital Sky Survey, of 20 nearby (D < 70 Mpc) Luminous Compact Blue Galaxies (LCBGs). These ~L*, blue, high surface brightness, starbursting galaxies were selected with the same criteria used to define LCBGs at higher redshifts. We find these galaxies are gas-rich, with M(HI) ranging from 5*10^8 to 8*10^9 M_sun, and M(HI)/L_B ranging from 0.2 to 2 M_sun/L_sun, consistent with a variety of morphological types of galaxies. We find the dynamical masses (measured within R_25) span a wide range, from 3*10^9 to 1*10^11 M_sun. However, at least half have dynamical mass-to-light ratios smaller than nearby galaxies of all Hubble types, as found for LCBGs at intermediate redshifts. By comparing line widths and effective radii with local galaxy populations, we find that LCBGs are consistent with the dynamical mass properties of Magellanic (low luminosity) spirals, and the more massive irregulars and dwarf ellipticals, such as NGC 205.Comment: 33 pages, 8 figures, accepted by Ap

Non-Markovian dynamics in atom-laser outcoupling from a double-well Bose-Einstein condensate

We investigate the dynamics of a continuous atom laser based on the merging of independently formed atomic condensates. In a first attempt to understand the dynamics of the system, we consider two independent elongated Bose-Einstein condensates which approach each other and focus on intermediate inter-trap distances so that a two-mode model is well justified. In the framework of a mean-field theory, we discuss the quasi steady-state population of the traps as well as the energy distribution of the outcoupled atoms.Comment: 21 pages, 9 figure, to appear in J. Phys.

The IRAM-30m line survey of the Horsehead PDR: IV. Comparative chemistry of H2CO and CH3OH

Aims. We investigate the dominant formation mechanism of H2CO and CH3OH in the Horsehead PDR and its associated dense core. Methods. We performed deep integrations of several H2CO and CH3OH lines at two positions in the Horsehead, namely the PDR and dense core, with the IRAM-30m telescope. In addition, we observed one H2CO higher frequency line with the CSO telescope at both positions. We determine the H2CO and CH3OH column densities and abundances from the single-dish observations complemented with IRAM-PdBI high-angular resolution maps (6") of both species. We compare the observed abundances with PDR models including either pure gas-phase chemistry or both gas-phase and grain surface chemistry. Results. We derive CH3OH abundances relative to total number of hydrogen atoms of ~1.2e-10 and ~2.3e-10 in the PDR and dense core positions, respectively. These abundances are similar to the inferred H2CO abundance in both positions (~2e-10). We find an abundance ratio H2CO/CH3OH of ~2 in the PDR and ~1 in the dense core. Pure gas-phase models cannot reproduce the observed abundances of either H2CO or CH3OH at the PDR position. Both species are therefore formed on the surface of dust grains and are subsequently photodesorbed into the gas-phase at this position. At the dense core, on the other hand, photodesorption of ices is needed to explain the observed abundance of CH3OH, while a pure gas-phase model can reproduce the observed H2CO abundance. The high-resolution observations show that CH3OH is depleted onto grains at the dense core. CH3OH is thus present in an envelope around this position, while H2CO is present in both the envelope and the dense core itself. Conclusions. Photodesorption is an efficient mechanism to release complex molecules in low FUV-illuminated PDRs, where thermal desorption of ice mantles is ineffective.Comment: 12 pages, 5 tables, 7 figures; Accepted for publication in A&

Quantum and classical thermal correlations in the XY spin-1/2 chain

We investigate pairwise quantum correlation as measured by the quantum discord as well as its classical counterpart in the thermodynamic limit of anisotropic XY spin-1/2 chains in a transverse magnetic field for both zero and finite temperatures. Analytical expressions for both classical and quantum correlations are obtained for spin pairs at any distance. In the case of zero temperature, it is shown that the quantum discord for spin pairs farther than second-neighbors is able to characterize a quantum phase transition, even though pairwise entanglement is absent for such distances. For finite temperatures, we show that quantum correlations can be increased with temperature in the presence of a magnetic field. Moreover, in the XX limit, the thermal quantum discord is found to be dominant over classical correlation while the opposite scenario takes place for the transverse field Ising model limit

The Universality of the Fundamental Plane of E and S0 Galaxies. Spectroscopic data

We present here central velocity dispersion measurements for 325 early-type galaxies in eight clusters and groups of galaxies, including new observations for 212 galaxies. The clusters and groups are the A262, A1367, Coma (A1656), A2634, Cancer and Pegasus clusters, and the NGC 383 and NGC 507 groups. The new measurements were derived from medium dispersion spectra, that cover 600 A centered on the Mg Ib triplet at lambda ~ 5175. Velocity dispersions were measured using the Tonry & Davis cross-correlation method, with a typical accuracy of 6%. A detailed comparison with other data sources is made.Comment: 12 pages, 5 tables, 3 figures, to appear in AJ. Note that tables 2 and 3 are in separate files, as they should be printed in landscape forma

NGPaaS framework for enriched and customized virtual network functions-as-a-service

This paper describes how the novel Next Generation Platform-as-a-Service (NGPaaS) framework can facilitate major benefits for Network Operators and Vertical Service Providers (VSPs) who wish to leverage Virtual Network Functions-as-a-Service (VNFaaS) capabilities. Network Operators can benefit by providing an "on demand" PaaS with required features for the VSPs, thus generating new revenue streams but with low operational overhead due to the high degree of automation. VSPs can benefit from the PaaS-oriented approach, by being able to flexibly on-board new VNF types and "value-added" service capabilities like monitoring, healing and profiling, to deliver customized service blueprints to meet the needs of their end customers. The paper outlines the design of an early prototype, built on the Open-CORD platform and using industry-standard Virtualised Network Functions (VNFs)

The Evolution of NGC 7027 at Radio Frequencies: A New Determination of the Distance and Core Mass

We present the results of a 25-year program to monitor the radio flux evolution of the planetary nebula NGC7027. We find significant evolution of the spectral flux densities. The flux density at 1465 MHz, where the nebula is optically thick, is increasing at a rate of 0.251+-0.015 % per year, caused by the expansion of the ionized nebula. At frequencies where the emission is optically thin, the spectral flux density is changing at a rate of -0.145+-0.005 % per year, caused by a decrease in the number of ionizing photons coming from the central star. A distance of 980+-100 pc is derived. By fitting interpolated models of post-AGB evolution to the observed changes, we find that over the 25-yr monitoring period, the stellar temperature has increased by 3900+-900 K and the stellar bolometric luminosity has decreased by 1.75+-0.38 %. We derive a distance-independent stellar mass of 0.655+-0.01 solar masses adopting the Bloecker stellar evolution models, or about 0.04 solar masses higher when using models of Vassiliadis & Wood which may provide a better fit. A Cloudy photoionization model is used to fit all epochs at all frequencies simultaneously. The differences between the radio flux density predictions and the observed values show some time-independent residuals of typically 1 %. A possible explanation is inaccuracies in the radio flux scale of Baars et al. We propose an adjustment to the flux density scale of the primary radio flux calibrator 3C286, based on the Cloudy model of NGC7027. We also calculate precise flux densities for NGC7027 for all standard continuum bands used at the VLA, as well as for some new 30GHz experiments.Comment: submitted to the Astrophysical Journa

Effects of interatomic collisions on atom laser outcoupling

We present a computational approach to the outcoupling in a simple one-dimensional atom laser model, the objective being to circumvent mathematical difficulties arising from the breakdown of the Born and Markov approximations. The approach relies on the discretization of the continuum representing the reservoir of output modes, which allows the treatment of arbitrary forms of outcoupling as well as the incorporation of non-linear terms in the Hamiltonian, associated with interatomic collisions. By considering a single-mode trapped condensate, we study the influence of elastic collisions between trapped and free atoms on the quasi steady-state population of the trap, as well as the energy distribution and the coherence of the outcoupled atoms.Comment: 25 pages, 11 figures, to appear in J. Phys.