Carbon and oxygen in metal-poor halo stars

Carbon and oxygen are key tracers of the Galactic chemical evolution; in particular, a reported upturn in [C/O] towards decreasing [O/H] in metal-poor halo stars could be a signature of nucleosynthesis by massive Population III stars. We reanalyse carbon, oxygen, and iron abundances in thirty-nine metal-poor turn-off stars. For the first time, we take into account three-dimensional (3D) hydrodynamic effects together with departures from local thermodynamic equilibrium (LTE) when determining both the stellar parameters and the elemental abundances, by deriving effective temperatures from 3D non-LTE H$\beta$ profiles, surface gravities from Gaia parallaxes, iron abundances from 3D LTE Feii equivalent widths, and carbon and oxygen abundances from 3D non-LTE Ci and Oi equivalent widths. We find that [C/Fe] stays flat with [Fe/H], whereas [O/Fe] increases linearly up to $0.75$ dex with decreasing [Fe/H] down to $-3.0$ dex. As such [C/O] monotonically decreases towards decreasing [O/H], in contrast to previous findings, mainly by virtue of less severe non-LTE effects for Oi at low [Fe/H] with our improved calculations.Comment: 5 pages, 2 figures; published in A&A Letter

Cosmological Cosmic Rays and the observed Li6 plateau in metal poor halo stars

Very recent observations of the Li6 isotope in halo stars reveal a Li6 plateau about 1000 times above the predicted BBN abundance. We calculate the evolution of Li6 versus redshift generated from an initial burst of cosmological cosmic rays (CCRs) up to the formation of the Galaxy. We show that the pregalactic production of the Li6 isotope can account for the Li6 plateau observed in metal poor halo stars without additional over-production of Li7. The derived relation between the amplitude of the CCR energy spectra and the redshift of the initial CCR production puts constraints on the physics and history of the objects, such as pop III stars, responsible for these early cosmic rays. Consequently, we consider the evolution of Li6 in the Galaxy. Since Li6 is also produced in Galactic cosmic ray nucleosynthesis, we argue that halo stars with metallicities between [Fe/H] = -2 and -1, must be somewhat depleted in Li6.Comment: 8 pages, 6 figures, version accepted for publication in Ap

A New Limit on Signals of Lorentz Violation in Electrodynamics

We describe the results of an experiment to test for spacetime anisotropy terms that might exist from Lorentz violations. The apparatus consists of a pair of cylindrical superconducting cavity-stabilized oscillators operating in the TM_{010} mode with one axis east-west and the other vertical. Spatial anisotropy is detected by monitoring the beat frequency at the sidereal rate and its first harmonic. We see no anisotropy to a part in 10^{13}. This puts a comparable bound on four linear combinations of parameters in the general Standard Model extension, and a weaker bound of <4 x 10^{-9} on three others.Comment: 4 pages, 3 figures, 2 table

Digesting New Elements in Peptide Transport

In this issue of Structure, Beale et al. (2015) define structurally and functionally a large extracellular domain unique to mammalian peptide transporters and its implications for the transport of basic di- and tri-peptides (Beale et al., 2015)

s/alpha/Fe Abundance Ratios in Halo Field Stars: Is there a Globular Cluster Connection?

We try to understand the s- and r-process elements vs Ti/Fe plots derived by Jehin et al. (1999) for mildly metal-poor stars within the framework of the analytical semi-empirical models for these elements by Pagel & Tautvaisiene (1995, 1997). Jehin et al. distinguished two Pop II subgroups: IIa with alpha/Fe and s-elements/Fe increasing together, which they attribute to pure SNII activity, and IIb with constant alpha/Fe and a range in s/Fe which they attribute to a prolonged accretion phase in parent globular clusters. However, their sample consists mainly of thick-disk stars with only 4 clear halo members, of which two are `anomalous' in the sense defined by Nissen & Schuster (1997). Only the remaining two halo stars (and one in Nissen & Schuster's sample) depart significantly from Y/Ti (or s/alpha) ratios predicted by our model.Comment: 6 pages, 5 figures To appear in: Roma-Trieste Workshop 1999: `The Chemical Evolution of the Milky Way: Stars vs Clusters', Vulcano Sept. 1999. F. Giovanelli & F. Matteucci (eds), Kluwer, Dordrech

IVUS-based imaging modalities for tissue characterization: similarities and differences

Gray-scale intravascular ultrasound (IVUS) is the modality that has been established as the golden standard for in vivo imaging of the vessel wall of the coronary arteries. The use of IVUS in clinical practice is an important diagnostic tool used for quantitative assessment of coronary artery disease. This has made IVUS the de-facto invasive imaging method to evaluate new interventional therapies such as new stent designs and for atherosclerosis progression-regression studies. However, the gray-scale representation of the coronary vessel wall and plaque morphology in combination with the limited resolution of the current IVUS catheters makes it difficult, if not impossible, to identify qualitatively (e.g. visually) the plaque morphology similar as that of histopathology, the golden standard to characterize and quantify coronary plaque tissue components. Meanwhile, this limitation has been partially overcome by new innovative IVUS-based post-processing methods such as: virtual histology IVUS (VH-IVUS, Volcano Therapeutics, Rancho Cordova, CA, USA), iMAP-IVUS (Bostoc Scientific, Santa Clara, CA, USA), Integrated Backscatter IVUS (IB-IVUS) and Automated Differential Echogenicity (ADE)

The professional and personal characteristics of effective psychotherapists : a systematic review

Objective: Psychotherapists differ notably in the outcomes their patients achieve, and the characteristics that may explain these differences have attracted increasing interest. We systematically review studies on therapist pre-treatment characteristics predicting patient outcomes. Method: Systematic searches on databases for psychotherapy research, clinical psychology, and medical science for the years 2000-2018 identified published research examining therapist characteristics and psychotherapy outcomes. Of 2041 studies, 31 met inclusion criteria. Results: Findings show a few direct effects of therapist intrapersonal variables (e.g., self-relatedness, attachment) and several interaction effects with other constructs (e.g., patient pathology) on outcome. There is little support for the relevance of self-rated social skills. However, more consistent evidence has recently emerged for performance-based measurements of professional interpersonal skills, especially when elicited in challenging situations. Patient outcomes were also predicted by therapists' self-rated professional characteristics, such as their experienced difficulties in practice, coping mechanisms, and attitudes towards therapeutic work, indicating that therapist self-perception also matters, although not always in the direction expected. Conclusions: More effective therapists seem characterized by professionally cultivated interpersonal capacities, which are likely rooted in their personal lives and attachment history. Research guidelines are proposed for moving this field forward (including larger samples, multilevel modeling, and in-depth qualitative work).Peer reviewe

The Rolodex model: understanding relationship complexity as a precursor to the design of organizational forms for chaotic environments

The emerging business environment is increasingly complex, characterized by hypercompetition, compound interdependence, and electronic webs This heightened complexity is triggering a slew of new organizational forms and shifts in the underlying logics of organizational forms These new organizational forms are not only more complex, but they have new kinds of complexity - increasingly hybrid and heterarchical, more flexible, and dynamically reconfigurable. The report argues that in such new conditions we need to rethink how we conceive the structural dimensions of organizational form and base them on a process model of inter-organizational relationships. This report examines relationship complexity as a structural topology that underlies organizational form It identifies three structural dimensions of relationship complexity reach, range, and reciprocity and combines them in a model that allows dynamic reconfigurability. The model is based on the primacy of perspective of practicing managers and we have termed it the Rolodex Model as it has overtones of an organizational version of a manager's card file of contacts. Using the concepts of energy and phase space from physics to enrich the Rolodex Model, the report shows how it can be used to explain existing archetypes of organizational forms, to identity new organizational forms, and to provide insights for organizational design The report then argues that further elaboration of energy concepts and relationship complexity may be necessary before we can fully respond to, and anticipate, the complex, dynamic, hypercompetitive organizational environment of today , much less that likely to exist tomorrow.Approved for public release; distribution is unlimited

Sulphur abundances in metal-poor stars

We investigate the debated "sulphur discrepancy" found among metal-poor stars of the Galactic halo with [Fe/H] < -2. This discrepancy stems in part from the use of two different sets of sulphur lines, the very weak triplet at 8694-95 A and the stronger triplet lines at 9212 - 9237 A. For three representative cases of metal-poor dwarf, turnoff and subgiant stars, we argue that the abundances from the 8694-95 lines have been overestimated which has led to a continually rising trend of [S/Fe] as metallicity decreases. Given that the near-IR region is subject to CCD fringing, these weak lines become excessively difficult to measure accurately in the metallicity regime of [Fe/H] < -2. Based on homogeneously determined spectroscopic stellar parameters, we also present updated [S/Fe] ratios from the 9212-9237 lines which suggest a plateau-like behaviour similar to that seen for other alpha elements.Comment: accepted by A&A, 4 pages, 3 tables, 1 figure; v2: Table2 updated with metallicities from other work