Globular Cluster Abundances from High-Resolution, Integrated-Light Spectroscopy. II. Expanding the Metallicity Range for Old Clusters and Updated Analysis Techniques

We present abundances of globular clusters in the Milky Way and Fornax from integrated light spectra. Our goal is to evaluate the consistency of the integrated light analysis relative to standard abundance analysis for individual stars in those same clusters. This sample includes an updated analysis of 7 clusters from our previous publications and results for 5 new clusters that expand the metallicity range over which our technique has been tested. We find that the [Fe/H] measured from integrated light spectra agrees to $\sim$0.1 dex for globular clusters with metallicities as high as [Fe/H]=$-0.3$, but the abundances measured for more metal rich clusters may be underestimated. In addition we systematically evaluate the accuracy of abundance ratios, [X/Fe], for Na I, Mg I, Al I, Si I, Ca I, Ti I, Ti II, Sc II, V I, Cr I, Mn I, Co I, Ni I, Cu I, Y II, Zr I, Ba II, La II, Nd II, and Eu II. The elements for which the integrated light analysis gives results that are most similar to analysis of individual stellar spectra are Fe I, Ca I, Si I, Ni I, and Ba II. The elements that show the greatest differences include Mg I and Zr I. Some elements show good agreement only over a limited range in metallicity. More stellar abundance data in these clusters would enable more complete evaluation of the integrated light results for other important elements.Comment: Accepted for publication in ApJ, 37 pages, 13 tables, 29 figure

Roundoff error sequences in fixed-point arithmetic digital processors

Three assumptions are normally made about roundoff error sequences in fixed-point arithmetic digital processors: all values of error, within the limits set by the roundoff process, have an equal probability of occurrence; they are random; and they are not correlated with any other signal or error sequence. The validity of these assumptions for digital filter realisations employing a signal wordlength in the range of 4 to 3 bits is examined. The investigation begins by using a fast Fourier transform algorithm to perform spectral analysis on roundoff error sequences when the test signal is a quantised sinusoid. It continues by comparing the variance of the error sequence measured at the output of various filter realisations with that theoretically predicted using the normal assumptions; this is done using random test sequences. It is shown that under certain conditions, for the signal wordlengths under consideration, each of the three assumptions can become invalid. In conclusion this work reports attempts to develop more accurate predictive noise models which only incorporate assumptions of greater validity

The Evolution of Oxygen and Magnesium in the Bulge and Disk of the Milky Way

We show that the Galactic bulge and disk share a similar, strong, decline in [O/Mg] ratio with [Mg/H]. The similarity of the [O/Mg] trend in these two, markedly different, populations suggests a metallicity-dependent modulation of the stellar yields from massive stars, by mass loss from winds, and related to the Wolf-Rayet phenomenon, as proposed by McWilliam & Rich (2004). We have modified existing models for the chemical evolution of the Galactic bulge and the solar neighborhood with the inclusion of metallicity-dependent oxygen yields from theoretical predictions for massive stars that include mass loss by stellar winds. Our results significantly improve the agreement between predicted and observed [O/Mg] ratios in the bulge and disk above solar metallicity; however, a small zero-point normalization problem remains to be resolved. The zero-point shift indicates that either the semi-empirical yields of Francois et al. (2004) need adjustment, or that the bulge IMF is not quite as flat as found by Ballero et al. (2007); the former explanation is preferred. Our result removes a previous inconsistency between the interpretation of [O/Fe] and [Mg/Fe] ratios in the bulge, and confirms the conclusion that the bulge formed more rapidly than the disk, based on the over-abundances of elements produced by massive stars. We also provide an explanation for the long-standing difference between [Mg/Fe] and [O/Fe] trends among disk stars more metal-rich than the sun.Comment: 22 pages including 5 figures. Submitted to the Astronomical Journa

An Update on the 0Z Project

We give an update on our 0Z Survey to find more extremely metal poor (EMP) stars with [Fe/H] < -3 dex through mining the database of the Hamburg/ESO Survey. We present the most extreme such stars we have found from ~1550 moderate resolution follow up spectra. One of these, HE1424-0241, has highly anomalous abundance ratios not seen in any previously known halo giant, with very deficient Si, moderately deficient Ca and Ti, highly enhanced Mn and Co, and low C, all with respect to Fe. We suggest a SNII where the nucleosynthetic yield for explosive alpha-burning nuclei was very low compared to that for the hydrostatic alpha-burning element Mg, which is normal in this star relative to Fe. A second, less extreme, outlier star with high [Sc/Fe] has also been found. We examine the extremely metal-poor tail of the HES metallicity distribution function (MDF). We suggest on the basis of comparison of our high resolution detailed abundance analyses with [Fe/H](HES) for stars in our sample that the MDF inferred from follow up spectra of the HES sample of candidate EMP stars is heavily contaminated for [Fe/H](HES) < -3 dex; many of the supposed EMP stars below that metallicity are of substantially higher Fe-metallicity, including most of the very C-rich stars, or are spurious objects.Comment: to appear in conference proceedings "First Stars III", ed. B. O'Shea, A. Heger & T.Abel, 4 pages, 2 figure

Hydrogen bonding in substituted nitroanilines : isolated nets in 1,3-diamino-4-nitrobenzene and continuously interwoven nets in 3,5-dinitroaniline

Peer reviewedPublisher PD

Sorting It Out: A Community Mediation Training Program at a Therapeutic Prison

A pilot study was conducted to assess the feasibility and effect of a community mediation program (‘Sorting It Out’) in a therapeutic prison (the Compulsory Drug Treatment Correctional Centre, or CDTCC). The program is unique as both staff and inmates were trained together. Also, in contrast to traditional dispute resolution, which is invoked after conflict has progressed, the program, which is based on therapeutic jurisprudence principles, trains participants in mediation to constructively address issues at the point of identification, prior to escalation. Measured outcomes included pre- and post-program questionnaires incorporating a social climate scale (EssenCES©), qualitative interviews and researcher observations. The participation rate was high, with all participants recommending the program. The outcomes included an enduring improvement in social climate and improvement in the CDTCC operation. Staff reported increased feelings of safety and support, and inmates reported increased understanding of staff and their roles. A large majority reported benefits to themselves and the community, including adoption of attitudes and behaviours learned in the program, improvement in staff–inmate interaction and a positive effect on staff work

Repurposing Statins for Renal Protection: Is It a Class Effect?

There has been a great deal of excitement regarding the potential benefits of statins beyond their lipid-lowering effect, and repurposing them for other indications. In this commentary, we evaluate the role of statins in protecting the kidneys, with a focus on three areas: cardiac surgery, contrast-induced nephropathy, and aminoglycoside-induced nephrotoxicity