The Detailed Chemical Abundance Patterns of M31 Globular Clusters

We present detailed chemical abundances for $>$20 elements in $\sim$30 globular clusters in M31. These results have been obtained using high resolution ($\lambda/\Delta\lambda\sim$24,000) spectra of their integrated light and analyzed using our original method. The globular clusters have galactocentric radii between 2.5 kpc and 117 kpc, and therefore provide abundance patterns for different phases of galaxy formation recorded in the inner and outer halo of M31. We find that the clusters in our survey have a range in metallicity of $-2.2<$[Fe/H]$<-0.11$. The inner halo clusters cover this full range, while the outer halo globular clusters at R$>$20 kpc have a small range in abundance of [Fe/H]$=-1.6 \pm 0.10$. We also measure abundances of alpha, r- and s-process elements. These results constitute the first abundance pattern constraints for old populations in M31 that are comparable to those known for the Milky Way halo.Comment: XII International Symposium on Nuclei in the Cosmos August 5-12, 2012 Cairns, Australia. To appear in Proceedings of Scienc

The effect of latent heat release on synoptic-to-planetary scale wave interactions and implications for satellite observations: Observational study

Researchers have been exploring methods to facilitate the prediction of rapidly intensifying surface cyclones. Recognizing that synoptic-scale systems, such as these cyclones, are less predictable at medium range and beyond than are planetary-scale circulations, researchers propose that the planetary-scale environment for explosive cyclogenesis could be better predicted than the cyclones themselves. Researchers have therefore constructed a planetary-scale climatology of explosive cyclogenesis by compositing together filtered 500 mb height fields (retaining planetary waves only) corresponding to a large sample of rapidly intensifying surface cyclones, stratified geographically and according to the direction of 500 mb geostrophic flow (southwesterly, northwesterly or westerly) over the cyclone center. The composites are calculated from five days preceding to five days following each rapid cyclogenesis event, and have climatology subtracted so that the evolution of planetary-scale anomalies before and after cyclogenesis can be followed. Whether the anomalies are distinct from background variability and thus provide predictive value is now being evaluated. Following explosive cyclogenesis over which the filtered 500 mb flow is southwesterly, there appear in the composites large positive 500 mb height anomalies downstream. In some cases, these anomalies are associated with blocking patterns. Whether the objectively-defined blocking patterns in the data set are preceded by upstream intense surface cyclone activity is being investigated. Finally, the contribution of synoptic-scale processes, notably warm air advection, to planetary-scale height rises during a block formation following an explosive cyclogenesis event is being diagnosed. Researchers hope to eventually evaluate the impact of satellite derived latent heat release upon the warm air advection in this case

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

On baryogenesis from dark matter annihilation

We study in detail the conditions to generate the baryon asymmetry of the universe from the annihilation of dark matter. This scenario requires a low energy mechanism for thermal baryogenesis, hence we first discuss some of these mechanisms together with the specific constraints due to the connection with the dark matter sector. Then we show that, contrary to what stated in previous studies, it is possible to generate the cosmological asymmetry without adding a light sterile dark sector, both in models with violation and with conservation of B-L. In addition, one of the models we propose yields some connection to neutrino masses.Comment: 30 pages, 9 artistic figures. V2 minor changes, matches published version in JCA

Pion Mass Modification in presence of external magnetic field

In this work, the self energies of $\pi^0$ and $\pi^{\pm}$ up to one loop order have been calculated in the limit of weak external magnetic field. The effective masses are explicitly dependent on the magnetic field which are modified significantly for the pseudoscalar coupling due to weak field approximation of the external field. On the other hand, for the pseudovector coupling, there is a modest increment in the effective masses of the pions. These theoretical developments are relevant for the study of the phenomenological aspect of mesons in the context of neutron stars as well as heavy ion collisions.Comment: Published in conference proceedings of DAE-HEP-2016 (XXII DAE High Energy Physics Symposium, New Delhi, India

R-mode oscillations and rocket effect in rotating superfluid neutron stars. I. Formalism

We derive the hydrodynamical equations of r-mode oscillations in neutron stars in presence of a novel damping mechanism related to particle number changing processes. The change in the number densities of the various species leads to new dissipative terms in the equations which are responsible of the {\it rocket effect}. We employ a two-fluid model, with one fluid consisting of the charged components, while the second fluid consists of superfluid neutrons. We consider two different kind of r-mode oscillations, one associated with comoving displacements, and the second one associated with countermoving, out of phase, displacements.Comment: 10 page

Suicide first aid guidelines for Sri Lanka: a Delphi consensus study.

BACKGROUND: Sri Lanka has one of the highest suicide rates in the world. Gatekeeper programs aimed at specific target groups could be a promising suicide prevention strategy in the country. The aim of this study was to develop guidelines that help members of the public to provide first aid to persons in Sri Lanka who are at risk of suicide. METHODS: The Delphi method was used to elicit consensus on potential helping statements to include in the guidelines. These statements describe information members of the public should have and actions they can take to help a person who is experiencing suicidal thoughts. An expert panel, comprised of mental health and suicide experts in Sri Lanka, rated each statement. The panellists were encouraged to suggest any additional action that was not included in the original questionnaire and, in particular, to include items that were culturally appropriate or gender specific. Responses to open-ended questions were used to generate new items. These items were included in the subsequent Delphi rounds. Three Delphi rounds were carried out. Statements were accepted for inclusion in the guidelines if they were endorsed (rated as essential or important) by at least 80 % of the panel. Statements endorsed by 70-79 % of the panel were re-rated in the following round. Statements with less than 70 % endorsement, or re-rated items that did not receive 80 % or higher endorsement were rejected. RESULTS: The output from the Delphi process was a set of endorsed statements. In the first round questionnaire 473 statements were presented to the panel and 58 new items were generated from responses to the open-ended questions. Of the total 531 statements presented, 304 were endorsed. These statements were used to develop the suicide first aid guidelines for Sri Lanka. CONCLUSION: By engaging Sri Lankans who are experts in the field of mental health or suicide this research developed culturally appropriate guidelines for providing mental health first aid to a person at risk of suicide in Sri Lanka. The guidelines may serve as a basis for developing training for members of the public to provide mental health first aid to persons at risk of suicide as part of Sri Lanka's suicide prevention strategy