Near-Infrared Stellar Populations in the metal-poor, Dwarf irregular Galaxies Sextans A and Leo A

We present JHK$_{s}$ observations of the metal-poor ([Fe/H] $<$ -1.40) Dwarf-irregular galaxies, Leo A and Sextans A obtained with the WIYN High-Resolution Infrared Camera at Kitt Peak. Their near-IR stellar populations are characterized by using a combination of colour-magnitude diagrams and by identifying long-period variable stars. We detected red giant and asymptotic giant branch stars, consistent with membership of the galaxy's intermediate-age populations (2-8 Gyr old). Matching our data to broadband optical and mid-IR photometry we determine luminosities, temperatures and dust-production rates (DPR) for each star. We identify 32 stars in Leo A and 101 stars in Sextans A with a DPR $>10^{-11}$ $M_\odot \,{\rm yr}^{-1}$, confirming that metal-poor stars can form substantial amounts of dust. We also find tentative evidence for oxygen-rich dust formation at low metallicity, contradicting previous models that suggest oxygen-rich dust production is inhibited in metal-poor environments. The total rates of dust injection into the interstellar medium of Leo A and Sextans A are (8.2 $\pm$ 1.8) $\times 10^{-9}$ $M_\odot \,{\rm yr}^{-1}$ and (6.2 $\pm$ 0.2) $\times 10^{-7}$ $M_\odot \,{\rm yr}^{-1}$, respectively. The majority of this dust is produced by a few very dusty evolved stars, and does not vary strongly with metallicity.Comment: 21 pages, 11 figures, 10 tables; accepted for publication in Ap

Magnetic and electric properties of double-perovskites and estimation of their Curie temperatures by ab initio calculations

First principles electronic structure calculations have been carried out on ordered double perovskites Sr_2B'B"O_6 (for B' = Cr or Fe and B" 4d and 5d transition metal elements) with increasing number of valence electrons at the B-sites, and on Ba_2MnReO_6 as well as Ba_2FeMoO_6. The Curie temperatures are estimated ab initio from the electronic structures obtained with the local spin-density functional approximation, full-potential generalized gradient approximation and/or the LDA+U method (U - Hubbard parameter). Frozen spin-spirals are used to model the excited states needed to evaluate the spherical approximation for the Curie temperatures. In cases, where the induced moments on the oxygen was found to be large, the determination of the Curie temperature is improved by additional exchange functions between the oxygen atoms and between oxygen and B' and B" atoms. A pronounced systematics can be found among the experimental and/or calculated Curie temperatures and the total valence electrons of the transition metal elements.Comment: 8 pages, 11 figures. Submitted to the Physical Review

Reconstructing Biological and Digital Phylogenetic Trees in Parallel

In this paper, we study the parallel query complexity of reconstructing biological and digital phylogenetic trees from simple queries involving their nodes. This is motivated from computational biology, data protection, and computer security settings, which can be abstracted in terms of two parties, a responder, Alice, who must correctly answer queries of a given type regarding a degree-d tree, T, and a querier, Bob, who issues batches of queries, with each query in a batch being independent of the others, so as to eventually infer the structure of T. We show that a querier can efficiently reconstruct an n-node degree-d tree, T, with a logarithmic number of rounds and quasilinear number of queries, with high probability, for various types of queries, including relative-distance queries and path queries. Our results are all asymptotically optimal and improve the asymptotic (sequential) query complexity for one of the problems we study. Moreover, through an experimental analysis using both real-world and synthetic data, we provide empirical evidence that our algorithms provide significant parallel speedups while also improving the total query complexities for the problems we study

Mapping Networks via Parallel kth-Hop Traceroute Queries

?(v,w), which return the name of the kth vertex on a shortest path from v to w, where ?(v,w) is the distance between v and w, that is, the number of edges in a shortest-path from v to w. The traceroute command is often used for network mapping applications, the study of the connectivity of networks, and it has been studied theoretically with respect to biases it introduces for network mapping when only a subset of nodes in the network can be the source of traceroute queries. In this paper, we provide efficient network mapping algorithms, that are based on kth-hop traceroute queries. Our results include an algorithm that runs in a constant number of parallel rounds with a subquadratic number of queries under reasonable assumptions about the sampling coverage of the nodes that may issue kth-hop traceroute queries. In addition, we introduce a number of new algorithmic techniques, including a high-probability parametric parallelization of a graph clustering technique of Thorup and Zwick, which may be of independent interest

Correlation Between Quality of Nutritional Workers Services and Patient's Satisfaction in Nutritional Services for Inpatient at Kajen General Hospital of Pekalongan District

Nutritionist services to third-class inpatients in Kajen district general hospital (RSUD) of Pekalongandistrict were not according to what was expected. This was cause by unsatisfaction of patients or theirfamily members regarding: meals that were not served in time; meal presentation that was notinteresting; and nutritional staffs who did not care, were not responsive, and were unpolite. Objectiveof this study was to identify association between perception on service quality of nutritional staffs andpatient satisfation toward nutritional service in the third-class inpatient rooms.This was an analytical survey with cross sectional approach. Data were collected through interviewguided by structured questionnaire. Independent variables were perception on validity,responsiveness, assurance, emphaty, and direct evidences. Dependent variable was patient satisfactory toward nutritional services. The number of study samples was 135 subjects selectedusing consecutive sampling. Data analysis was done by applying Spearman Rank correlation forbivariate analysis, and by applying multiple linier regression for multivariate analysis.Results of the study showed that 59.3% of respondent's perception on validity were good; 61.5% ofrespondent's perception on responsiveness were good; 56.3% respondent's perception on assurancewere good; 50.4% respondent's perception on empathy were good, 65.2% of respondent's perceptionon direct evidence were good; and 58.5% of respondent's satisfaction were satisfactory towardnutritional service. Results of bivariate analysis showed significant associations between patientsatisfaction toward nurtritional service and validity, responsiveness, assurance, empathy, and directevidence (p< 0.05). Result of multivariate analysis showed that the most influencing factor towardpatient satisfaction was perception on the direct evidence (B= 0.230). Hospital management issuggested to improve customer service assistance and training to nutritional staff

Cometary Dust in the Debris Disks of HD 31648 and HD 163296: Two ``Baby'' beta Pics

The debris disks surrounding the pre-main sequence stars HD 31648 and HD 163296 were observed spectroscopically between 3 and 14 microns. Both possess a silicate emission feature at 10 microns which resembles that of the star beta Pictoris and those observed in solar system comets. The structure of the band is consistent with a mixture of olivine and pyroxene material, plus an underlying continuum of unspecified origin. The similarity in both size and structure of the silicate band suggests that the material in these systems had a processing history similar to that in our own solar system prior to the time that the grains were incorporated into comets.Comment: 17 pages, AASTeX, 5 eps figures, accepted for publication in Ap.

Crystal structure of polymeric carbon nitride and the determination of its process-temperature-induced modifications

Based on the arrangement of two-dimensional 'melon', we construct a unit cell for polymeric carbon nitride (PCN) synthesized via thermal polycondensation, whose theoretical diffraction powder pattern includes all major features measured in x-ray diffraction. With the help of this unit cell, we describe the process-temperature-induced crystallographic changes in PCN that occur within a temperature interval between 510 and 610 °C. We also discuss further potential modifications of the unit cell for PCN. It is found that both triazine- and heptazine-based g-C3N4 can only account for minor phases within the investigated synthesis products

Motivations of Volunteer Leaders in an Extension Exercise Program

This article describes findings from a qualitative study of volunteer leaders in the StrongWomen strength training program in Arkansas. The study explored reasons volunteers initially agreed to serve, perceptions of volunteer role, and motivations for continuing to lead strength training groups long-term. Findings suggest a combination of factors supporting volunteer engagement: personal benefit of program, desire to continue program combined with a personal invitation to volunteer extended by the agent, desire to support a co-leader, and exercise and social support needs met through volunteer service. Motivations of Extension health program volunteers are important to address to maximize program impact

Volunteer Delivery of a Community-Based Strength Training Program: Comparison of Adopting and Nonadopting Extension Educator Perspectives

Volunteer leaders are increasingly being utilized to deliver community strength training classes, but the factors affecting adoption of volunteer delivery approaches by educators or program managers have not been well explored. This study sought to identify these factors by comparing perspectives of adopting and nonadopting county Extension educators for a group strength training program delivered through county Cooperative Extension offices. Semistructured interviews were conducted with a purposive sample of adopting (n=6) and nonadopting (n=13) educators. Interviews were recorded, transcribed verbatim, and coded using thematic content analysis. Review of codes related to adoption or nonadoption of volunteer delivery approaches produced common themes. Both groups acknowledged role differences between educators and volunteers and expressed concerns about maintaining program quality. Adopters expressed greater comfort with volunteer-led program approaches and understanding of the educator-volunteer role. Nonadopters were hesitant to request program participants serve as leaders but felt participants were capable. Both groups were motivated to offer the program for dual personal and community benefit, but nonadopters expressed reliance on the program to maintain physical activity habits and for social support. Findings can inform others seeking to adapt community programs for volunteer delivery or engage volunteers in existing program delivery