A new HCN maser in IRAS 15082-4808

We have identified a new vibrational HCN maser at 89.087 GHz in the asymptotic giant branch (AGB) star IRAS 15082-4808, a maser which is thought to trace the innermost region of an AGB envelope. The observations of this maser at three epochs are presented: two positive detections and one null detection. The line profile has varied between the positive detections, as has the intensity of the maser. The major component of the maser is found to be offset by -2.0+/-0.9 km/s with respect to the systemic velocity of the envelope, as derived from the 88.631 GHz transition of HCN. Similar blueshifts are measured in the other 9 sources where this maser has been detected. Maser variability with pulsation phase has been investigated for the first time using the 10 stars now available. Comparisons with AGB model atmospheres constrain the position of the formation region of the maser to the region between the pulsation shocks and the onset of dust acceleration, between 2 and 4 stellar radii.Comment: 11 pages, 10 figures, accepted MNRAS, minor correction to equation

The initial conditions of stellar protocluster formation. II. A catalogue of starless and protostellar clumps embedded in IRDCs in the Galactic longitude range 15<l<55

We present a catalogue of starless and protostellar clumps associated with infrared dark clouds (IRDCs) in a 40 degrees wide region of the inner Galactic Plane (b<1). We have extracted the far-infrared (FIR) counterparts of 3493 IRDCs with known distance in the Galactic longitude range 15<l<55 and searched for the young clumps using Hi-GAL, the survey of the Galactic Plane carried out with the Herschel satellite. Each clump is identified as a compact source detected at 160, 250 and 350 mum. The clumps have been classified as protostellar or starless, based on their emission (or lack of emission) at 70 mum. We identify 1723 clumps, 1056 (61%) of which are protostellar and 667 (39%) starless. These clumps are found within 764 different IRDCs, 375 (49%) of which are only associated with protostellar clumps, 178 (23%) only with starless clumps, and 211 (28%) with both categories of clumps. The clumps have a median mass of 250 M_sun and range up to >10^4$ M_sun in mass and up to 10^5 L_sun in luminosity. The mass-radius distribution shows that almost 30% of the starless clumps identified in this survey could form high-mass stars, however these massive clumps are confined in only ~4% of the IRDCs. Assuming a minimum mass surface density threshold for the formation of high-mass stars, the comparison of the numbers of massive starless clumps and those already containing embedded sources suggests an upper limit lifetime for the starless phase of 10^5 years for clumps with a mass M>500 M_sun.Comment: accepted for publication in MNRAS. Online catalogues available soon, please contact the authors if intereste

Development of a mercury electromagnetic centrifugal pump for the SNAP-8 refractory boiler development program

An electromagnetic pump, in which pressure is developed in mercury because of the interaction of the magnetic field and current which flows as a result of the voltage induced in the mercury contained in the pump duct, was developed for the SNAP-8 refractory boiler test facility. Pump performance results are presented for ten duct configurations and two stator sizes. These test results were used to design and fabricate a pump which met the SNAP-8 criteria of 530 psi developed pressure at 12,500 lb/hr. The pump operated continuously for over 13,000 hours without failure or performance degradation. Included in this report are descriptions of the experimental equipment, measurement techniques, all experimental data, and an analysis of the electrical losses in the pump

Neutrinos in Cosmology and Astrophysics

We briefly review the recent developments in neutrino physics and astrophysics which have import for frontline research in nuclear physics. These developments, we argue, tie nuclear physics to exciting developments in observational cosmology and astrophysics in new ways. Moreover, the behavior of neutrinos in dense matter is itself a fundamental problem in many-body quantum mechanics, in some ways akin to well-known issues in nuclear matter and nuclei, and in some ways radically different, especially because of nonlinearity and quantum de-coherence. The self-interacting neutrino gas is the only many body system driven by the weak interactions.Comment: 7 pages, 1 figur

The role of goal structures and peer climate in trajectories of social achievement goals during high school

Students’ social goals—reasons for engaging in interpersonal relationships with peers—are consequential for students’ interactions with their peers at school and for their well-being. Despite the salience of peer relationships during adolescence, research on social goals is generally lacking compared with academic goals, and it is unknown how these social goals develop over time, especially among high school students. The aim of the study was to assess trajectories of students’ social goals and to determine how relevant individual and contextual variables predicted initial levels and trajectories of students’ social goals. Participants were 9th through 12th grade students (N = 526) attending a U.S. high school. Students filled out surveys of their social goals (social development, social demonstration-approach, and social demonstration-avoidance) 6 times across 2 school years. Nonlinear growth curve analyses and piecewise growth curve analyses were used to assess trajectories of social goals across time. Students’ initial levels of social goals differed based on their gender, grade level, prior achievement, and perceptions of classroom goals structures and peer climate. Furthermore, despite substantial stability over time, the shapes of these goal trajectories were predicted by students’ gender, grade level, and perceptions of classroom goal structures and peer climate. In particular, students who perceived an increase in performance-avoidance classroom goals maintained higher demonstration social goals and decreased in developmental social goals over time, and students who perceived an increase in positive peer climate decreased in demonstration-avoidance social goals. Implications and directions for future research on social goals are discussed

COMMENT: A THEORETICAL FRAMEWORK FOR ANALYZING SOCIAL COSTS OF THE TOBACCO PROGRAM

Institutional and Behavioral Economics,

Tightening the belt: Constraining the mass and evolution in SDC335

Recent ALMA observations identified one of the most massive star-forming cores yet observed in the Milky Way; SDC335-MM1, within the infrared dark cloud SDC335.579-0.292. Along with an accompanying core MM2, SDC335 appears to be in the early stages of its star formation process. In this paper we aim to constrain the properties of the stars forming within these two massive millimetre sources. Observations of SDC335 at 6, 8, 23 and 25GHz were made with the ATCA. We report the results of these continuum measurements, which combined with archival data, allow us to build and analyse the spectral energy distributions (SEDs) of the compact sources in SDC335. Three HCHII regions within SDC335 are identified, two within the MM1 core. For each HCHII region, a free-free emission curve is fit to the data allowing the derivation of the sources' emission measure, ionising photon flux and electron density. Using these physical properties we assign each HCHII region a ZAMS spectral type, finding two protostars with characteristics of spectral type B1.5 and one with a lower limit of B1-B1.5. Ancillary data from infrared to mm wavelength are used to construct free-free component subtracted SEDs for the mm-cores, allowing calculation of the bolometric luminosities and revision of the previous gas mass estimates. The measured luminosities for the two mm-cores are lower than expected from accreting sources displaying characteristics of the ZAMS spectral type assigned to them. The protostars are still actively accreting, suggesting that a mechanism is limiting the accretion luminosity, we present the case for two different mechanisms capable of causing this. Finally, using the ZAMS mass values as lower limit constraints, a final stellar population for SDC335 was synthesised finding SDC335 is likely to be in the process of forming a stellar cluster comparable to the Trapezium Cluster and NGC6334 I(N).Comment: 10 pages, 5 figures. Accepted for publication in A&

Students’ interpersonal connections with peers and staff at the start of higher education

Establishing positive social relationships is important for students’ success and retention in higher education (HE). This can be especially challenging during the transition into HE since students often move to a larger educational setting and need to build relationships with new peers and staff. Research is needed to better understand social connections during this critical time, including the role of demographics, curricular and extracurricular participation, and how peer and staff connections predict academic achievement. Surveys of 290 first-year students at a large US public university assessed with whom students were interacting, how often, for what reasons, and with what modes of communication. Results include a detailed description of students’ interpersonal connections at the transition into HE, differences by demographics, curricular, and extracurricular participation, and the associations between students’ patterns of relationships and their academic achievement

SNAP 8 refractory boiler development program - Shell side hydraulic characteristics of a full scale SNAP 8 multiple tube model boiler Topical report no. 5

Shell side hydraulic characteristics of full-scale SNAP 8 multiple-tube model boiler over turbulent Reynolds number from 18,000 to 38,00