SPECIES I: Spectroscopic Parameters and atmosphEric ChemIstriEs of Stars

The detection and subsequent characterisation of exoplanets are intimately linked to the characteristics of their host star. Therefore, it is necessary to study the star in detail in order to understand the formation history and characteristics of their companion(s). Our aims were to develop a community tool that allows the automated calculation of stellar parameters for a large number of stars, using high resolution echelle spectra and minimal photometric magnitudes, and introduce the first results in this work. We measured the equivalent widths of several iron lines and used them to solve the radiative transfer equation assuming local thermodynamic equilibrium to obtain the atmospheric parameters ($T_{\text{eff}}$, [Fe/H], logg and $\xi_t$). We used these values to derive the abundance of 11 chemical elements in the stellar photosphere (Na, Mg, Al, Si, Ca, Ti, Cr, Mn, Ni, Cu and Zn). Rotation and macroturbulent velocity were obtained using temperature calibrators and synthetic line profiles to match the observed spectra of five absorption lines. Finally, by interpolating in a grid of MIST isochrones, we derived the mass, radius and age using a Bayesian approach. SPECIES obtains bulk parameters that are in good agreement with measured values from different existing catalogues, including when different methods are used to derive them. We find excellent agreement with previous works that used similar methodologies. We find discrepancies in the chemical abundances for some elements with respect to other works, which could be produced by differences in $T_{\text{eff}}$, or in the line list or the atomic line data used to derive them. We also obtained analytic relations to describe the correlations between different parameters, and we implemented new methods to better handle these correlations, which provides a better description of the uncertainties associated with the measurements.Comment: 28 pages, 26 figures, resubmitted to A&

Decuplet baryon magnetic moments in a QCD-based quark model beyond quenched approximation

We study the decuplet baryon magnetic moments in a QCD-based quark model beyond quenched approximation. Our approach for unquenching the theory is based on the heavy baryon perturbation theory in which the axial couplings for baryon - meson and the meson-meson-photon couplings from the chiral perturbation theory are used together with the QM moment couplings. It also involves the introduction of a form factor characterizing the structure of baryons considered as composite particles. Using the parameters obtained from fitting the octet baryon magnetic moments, we predict the decuplet baryon magnetic moments. The $\Omega^-$ magnetic moment is found to be in good agreement with experiment: $\mu_{\Omega^-}$ is predicted to be $-1.97 \mu_N$ compared to the experimental result of ($-$2.02 $\pm$ 0.05) $\mu_N$.Comment: 19 pages, 2 figure

Long-term variations in abundance and distribution of sulfuric acid vapor in the Venus atmosphere inferred from Pioneer Venus and Magellan radio occultation studies

Radio occultation experiments have been used to study various properties of planetary atmospheres, including pressure and temperature profiles, and the abundance profiles of absorbing constituents in those planetary atmospheres. However, the reduction of amplitude data from such experiments to determine abundance profiles requires the application of the inverse Abel transform (IAT) and numerical differentiation of experimental data. These two operations preferentially amplify measurement errors above the true signal underlying the data. A new technique for processing radio occultation data has been developed that greatly reduces the errors in the derived absorptivity and abundance profiles. This technique has been applied to datasets acquired from Pioneer Venus Orbiter radio occultation studies and more recently to experiments conducted with the Magellan spacecraft. While primarily designed for radar studies of the Venus surface, the high radiated power (EIRP) from the Magellan spacecraft makes it an ideal transmitter for measuring the refractivity and absorptivity of the Venus atmosphere by such experiments. The longevity of the Pioneer Venus Orbiter has made it possible to study long-term changes in the abundance and distribution of sulfuric acid vapor, H2SO4(g), in the Venus atmosphere between 1979 and 1992. The abundance of H2SO4(g) can be inferred from vertical profiles of 13-cm absorptivity profiles retrieved from radio occultation experiments. Data from 1979 and 1986-87 suggest that the abundance of H2SO4(g) at latitudes northward of 70 deg decreased over this time period. This change may be due to a period of active volcanism in the late 1970s followed by a relative quiescent period, or some other dynamic process in the Venus atmosphere. While the cause is not certain, such changes must be incorporated into dynamic models of the Venus atmosphere. Potentially, the Magellan spacecraft will extend the results of Pioneer Venus Orbiter and allow the continued monitoring of the abundance of distribution of H2SO4(g) in the Venus atmosphere, as well as other interesting atmospheric properties. Without such measurements it will be difficult to address other issues such as the short-term spatial variability of the abundance of H2SO4(g) at similar latitudes in Venus atmosphere, and the identities of particles responsible for large-scale variations observed in NIR images

Experimental creep data for a built-up aluminum/titanium structure subjected to heating and loading

Experimental creep, temperature, and strain data resulting from a laboratory experiment on a built-up aluminum/titanium structure are presented. The structure and the experiment are described in detail. A heating and loading experiment lasting approximately six hours is conducted on a test structure. Considerable creep strain resulted from compressive stresses in the heated skin. Large residual stresses were found after the experiment was completed. The residual stresses in the substructure frames were large enough to preclude further cycles of creep experiments with this built-up structure because of concern that the frame webs would buckle

Enskog Theory for Polydisperse Granular Mixtures II. Sonine Polynomial Approximation

The linear integral equations defining the Navier-Stokes (NS) transport coefficients for polydisperse granular mixtures of smooth inelastic hard disks or spheres are solved by using the leading terms in a Sonine polynomial expansion. Explicit expressions for all the NS transport coefficients are given in terms of the sizes, masses, compositions, density and restitution coefficients. In addition, the cooling rate is also evaluated to first order in the gradients. The results hold for arbitrary degree of inelasticity and are not limited to specific values of the parameters of the mixture. Finally, a detailed comparison between the derivation of the current theory and previous theories for mixtures is made, with attention paid to the implication of the various treatments employed to date.Comment: 26 pages, to be published in Phys. Rev.

The Decuplet Revisited in χ\chiPT

The paper deals with two issues. First, we explore the quantitiative importance of higher multiplets for properties of the $\Delta$ decuplet in chiral perturbation theory. In particular, it is found that the lowest order one--loop contributions from the Roper octet to the decuplet masses and magnetic moments are substantial. The relevance of these results to the chiral expansion in general is discussed. The exact values of the magnetic moments depend upon delicate cancellations involving ill--determined coupling constants. Second, we present new relations between the magnetic moments of the $\Delta$ decuplet that are independent of all couplings. They are exact at the order of the chiral expansion used in this paper.Comment: 7 pages of double column revtex, no figure

Chiral Perturbation Theory Analysis of the Baryon Magnetic Moments

Nonanalytic $m_q^{1/2}$ and $m_q\ln m_q$ chiral corrections to the baryon magnetic moments are computed. The calculation includes contributions from both intermediate octet and decuplet baryon states. Unlike the one-loop contributions to the baryon axial currents and masses, the contribution from decuplet intermediate states does not partially cancel that from octet intermediate states. The fit to the observed magnetic moments including $m_q^{1/2}$ corrections is found to be much worse than the tree level SU(3) fit if values for the baryon-pion axial coupling constants obtained from a tree level extraction are used. Using the axial coupling constant values extracted at one loop results in a better fit to the magnetic moments than the tree level SU(3) fit. There are three linear relations amongst the magnetic moments when $m_q^{1/2}$ corrections are included, and one relation including $m_q^{1/2}$, $m_q\ln m_q$ and $m_q$ corrections. These relations are independent of the axial coupling constants of the baryons and agree well with experiment.Comment: (16 pages, 2 figures; uses harvmac and uufiles), CERN-TH.6735/92, UCSD/PTH 92-3

Beyond and beneath the hierarchical market economy: global production and working-class conflict in Argentina's automobile industry

This paper argues that the hierarchical market economy (HME) category does not provide an adequate starting point for addressing capitalist diversity in Latin America. Building from a critical perspective on the global commodity chain (GCC) and global production network (GPN) approaches, it instead considers the impact of firms’ transnational relations and the often neglected role of working-class struggles. It will argue that capitalist diversity can only be understood at the nexus of these ostensibly global and local phenomena; and by specifying the strategic decisions taken by firms in Argentina’s automobile industry, it will account for the failure of that sector. Finally, it examines the role of working-class struggles in the industry in Córdoba, Argentina, arguing that these were vital in shaping the specific and unstable form of capitalist diversity in Argentina, as well as potential alternatives to it