ALMA observations of the supergiant B[e] star Wd1-9

Mass-loss in massive stars plays a critical role in their evolution, although the precise mechanism(s) responsible – radiatively driven winds, impulsive ejection and/or binary interaction – remain uncertain. In this Letter, we present Atacama Large Millimetre/Submillimeter Array line and continuum observations of the supergiant B[e] star Wd1-9, a massive post-main-sequence object located within the starburst cluster Westerlund 1 (Wd1). We find it to be one of the brightest stellar point sources in the sky at millimetre wavelengths, with (serendipitously identified) emission in the H41α radio recombination line. We attribute these properties to a low velocity (∼100 km s-1 ) ionized wind, with an extreme mass-loss rate ≳6.4 × 105(d/5 kpc)1.5 Mȯyr-1. External to this is an extended aspherical ejection nebula indicative of a prior phase of significant mass-loss. Taken together, the millimetre properties of Wd1-9 show a remarkable similarity to those of the highly luminous stellar source MWC349A. We conclude that these objects are interacting binaries evolving away from the main sequence and undergoing rapid case-A mass transfer. As such they – and by extension the wider class of supergiant B[e] stars – may provide a unique window into the physics of a process that shapes the life-cycle of ∼70 per cent of massive stars found in binary systems

Finite-thrust transfer in the two and three body problems Final report

Computer program for optimal finite thrust transfer between two orbit

e-MERLIN 21 cm constraints on the mass-loss rates of OB stars in Cyg OB2

We present e-MERLIN 21 cm (L-band) observations of single luminous OB stars in the Cygnus OB2 association, from the Cyg OB2 Radio Survey Legacy programme. The radio observations potentially offer the most straightforward, least model-dependent, determinations of mass-loss rates, and can be used to help resolve current discrepancies in mass-loss rates via clumped and structured hot star winds. We report here that the 21 cm flux densities of O3 to O6 supergiant and giant stars are less than ∼70 μJy. These fluxes may be translated to ‘smooth’ wind mass-loss upper limits of ∼4.4–4.8 × 10−6 M⊙ yr −1 for O3 supergiants and ≲2.9 × 10−6 M⊙ yr −1 for B0 to B1 supergiants. The first ever resolved 21 cm detections of the hypergiant (and luminous blue variable candidate) Cyg OB2 #12 are discussed; for multiple observations separated by 14 d, we detect an ∼69 per cent increase in its flux density. Our constraints on the upper limits for the mass-loss rates of evolved OB stars in Cyg OB2 support the model that the inner wind region close to the stellar surface (where Hα forms) is more clumped than the very extended geometric region sampled by our radio observations

Effects of periadolescent fluoxetine and paroxetine on elevated plus-maze, acoustic startle, and swimming immobility in rats while on and off-drug

<p>Abstract</p> <p>Rationale</p> <p>Whether selective serotonin reuptake inhibitors (SSRIs) exposure during adolescent brain development causes lasting effects remains unresolved.</p> <p>Objective</p> <p>Assess the effects of fluoxetine and paroxetine 60 days after adolescent exposure compared with when on-drug.</p> <p>Methods</p> <p>Male Sprague-Dawley littermates (41 litters) were gavaged on postnatal days 33-53 with fluoxetine (3 or 10 mg/kg/day), paroxetine (3, 10 or, 17 mg/kg/day), or water; half were tested while on-drug (21 litters) and half after 60 days off-drug (20 litters).</p> <p>Results</p> <p>The highest dose of the drugs reduced body weight gain during treatment that rebounded 1 week post-treatment. On-drug, no significant group differences were found on elevated plus maze time-in-open, zone entries, or latency to first open entry; however, the high dose of paroxetine significantly reduced head-dips (N = 20/group). No significant effects were found on-drug for acoustic startle response/prepulse inhibition (ASR/PPI) although a trend (p < 0.10) was seen, which after combining dose levels, showed a significant increase in ASR amplitude for both fluoxetine and paroxetine (N = 20-21/group). No differences on immobility time were seen in the Porsolt forced swim test or in plasma corticosterone at the end of forced swim (N-19-21/group). Off-drug, no effects were seen in the elevated plus maze (N = 16/group), ASR/PPI (N = 20/group), forced swim (N = 19-20/group), or plasma corticosterone (N = 19/group). At the doses tested, fluoxetine and paroxetine induced minor effects with drug on-board but no residual, long-term adverse effects in rats 60 days after drug discontinuation.</p> <p>Conclusions</p> <p>The data provide no evidence that fluoxetine or paroxetine have long-term adverse effects on the behaviors measured here after adolescent to young adult exposure.</p

SPIDER: CMB Polarimetry from the Edge of Space

Spider is a balloon-borne instrument designed to map the polarization of the millimeter-wave sky at large angular scales. Spider targets the B-mode signature of primordial gravitational waves in the cosmic microwave background (CMB), with a focus on mapping a large sky area with high fidelity at multiple frequencies. Spider ’s first long-duration balloon (LDB) flight in January 2015 deployed a total of 2400 antenna-coupled transition-edge sensors (TESs) at 90 GHz and 150 GHz. In this work we review the design and in-flight performance of the Spider instrument, with a particular focus on the measured performance of the detectors and instrument in a space-like loading and radiation environment. Spider ’s second flight in December 2018 will incorporate payload upgrades and new receivers to map the sky at 285 GHz, providing valuable information for cleaning polarized dust emission from CMB maps

A model for uranium, rhenium, and molybdenum diagenesis in marine sediments based on results from coastal locations

Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 73 (2009): 2938-2960, doi:10.1016/j.gca.2009.02.029.The purpose of this research is to characterize the mobilization and immobilization processes that control the authigenic accumulation of uranium (U), rhenium (Re) and molybdenum (Mo) in marine sediments. We analyzed these redox– sensitive metals (RSM) in benthic chamber, pore water and solid phase samples at a site in Buzzards Bay, Massachusetts, U.S.A., which has high bottom water oxygen concentrations (230–300 mol/L) and high organic matter oxidation rates (390 mol C/cm2/y). The oxygen penetration depth varies from 2–9 mm below the sediment–water interface, but pore water sulfide is below detection (< 2M). The RSM pore water profiles are modeled with a steady–state diagenetic model that includes irrigation, which extends 10–20 cm below the sediment–water interface. To present a consistent description of trace metal diagenesis in marine sediments, RSM results from sediments in Buzzards Bay are compared with previous research from sulfidic sediments (Morford et al., GCA 71). Release of RSM to pore waters during the remineralization of solid phases occurs near the sediment–water interface at depths above the zone of authigenic RSM formation. This release occurs consistently for Mo at both sites, but only in the winter for Re in Buzzards Bay and intermittently for U. At the Buzzards Bay site, Re removal to the solid phase extends to the bottom of the profile, while the zone of removal is restricted to ~2–9 cm for U and Mo. Authigenic Re formation is independent of the anoxic remineralization rate, which is consistent with an abiotic removal mechanism. The rate of authigenic U formation and its modeled removal rate constant increase with increasing anoxic remineralization rates, and is consistent with U reduction being microbially mediated. Authigenic Mo formation is related to the formation of sulfidic microenvironments. The depth and extent of Mo removal from pore water is closely associated with the balance between iron and sulfate reduction and the consumption of pore water sulfide via iron sulfide formation. Pore water RSM reach constant asymptotic concentrations in sulfidic sediments, but only pore water Re is constant at depth in Buzzards Bay. The increases in pore water U at the Buzzards Bay site are consistent with addition via irrigation and subsequent upward diffusion to the removal zone. Deep pore water Mo concentrations exceed its bottom water concentration due to irrigation–induced oxidation and remobilization from the solid phase. In sulfidic sediments, there is no evidence for higher pore water U or Mo concentrations at depth due to the absence of irrigation and/or the presence of more stable authigenic RSM phases. There are good correlations between benthic fluxes and authigenic accumulation rates for U and Mo in sulfidic sediments. However, results from Buzzards Bay suggest irrigation ultimately results in the partial loss of U and Mo from the solid phase, with accumulation rates that are 20–30% of the modeled flux. Irrigation can augment (Re, possibly U) or compromise (U, Mo) authigenic accumulation in sediments, and is important when determining burial rates in continental margin sediments.The authors also acknowledge financial support from the National Science Foundation (JLM, WRM: OCE–0220892), Research Corporation (JLM, CMC), Franklin & Marshall College, and the Hackman Summer Research Program at F&M

Uranium diagenesis in sediments underlying bottom waters with high oxygen content

Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 73 (2009): 2920-2937, doi:10.1016/j.gca.2009.02.014.We measured U in sediments (both pore waters and solid phase) from three locations on the middle Atlantic Bight (MAB) from the eastern margin of the United States: a northern location on the continental shelf off Massachusetts (OC426, 75 m water depth), and two southern locations off North Carolina (EN433-1, 647 m water depth and EN433-2, 2648 m water depth). These sediments underlie high oxygen bottom waters (250-270 μM), but become reducing below the sediment-water interface due to the relatively high organic carbon oxidation rates in sediments (EN433-1: 212 μmol C/cm2/y; OC426: 120±10 μmol C/cm2/y; EN433-2: 33 μmol C/cm2/y). Pore water oxygen goes to zero by 1.4-1.5 cm at EN433-1 and OC426 and slightly deeper oxygen penetration depths were measured at EN433-2 (~4 cm). All of the pore water profiles show removal of U from pore waters. Calculated pore water fluxes are greatest at EN433-1 (0.66±0.08 nmol/cm2/y) and less at EN433-2 and OC426 (0.24±0.05 and 0.13±0.05 nmol/cm2/y, respectively). Solid phase profiles show authigenic U enrichment in sediments from all three locations. The average authigenic U concentrations are greater at EN433-1 and OC426 (5.8±0.7 nmol/g and 5.4±0.2 nmol/g, respectively) relative to EN433-2 (4.1±0.8 nmol/g). This progression is consistent with their relative ordering of ‘reduction intensity’, with greatest reducing conditions in sediments from EN433-1, less at OC426 and least at EN433-2. The authigenic U accumulation rate is largest at EN433-1 (0.47±0.05 nmol/cm2/y), but the average among the three sites on the MAB is ~0.2 nmol/cm2/y. Pore water profiles suggest diffusive fluxes across the sediment-water interface that are 1.4-1.7 times greater than authigenic accumulation rates at EN433-1 and EN433-2. These differences are consistent with oxidation and loss of U from the solid phase via irrigation and/or bioturbation, which may compromise the sequestration of U in continental margin sediments that underlie bottom waters with high oxygen concentrations. Previous literature compilations that include data exclusively from locations where [O2]bw < 150 μM suggest compelling correlations between authigenic U accumulation and organic carbon flux to sediments or organic carbon burial rate. Sediments that underlie waters with high [O2]bw have lower authigenic U accumulation rates than would be predicted from relationships developed from results that include locations where [O2]bw < 150 μM.The authors appreciate the financial support from NSF (JLM, WRM: OCE-0220892; and OCE-0526389 to WRM), Research Corporation (JLM, CMC), Franklin & Marshall College, and the Hackman Summer Research Program (CMC) at F&M

The rp-process and new measurements of beta-delayed proton decay of light Ag and Cd isotopes

Recent network calculations suggest that a high temperature rp-process could explain the abundances of light Mo and Ru isotopes, which have long challenged models of p-process nuclide production. Important ingredients to network calculations involving unstable nuclei near and at the proton drip line are $\beta$-halflives and decay modes, i.e., whether or not $\beta$-delayed proton decay takes place. Of particular importance to these network calculation are the proton-rich isotopes $^{96}$Ag, $^{98}$Ag, $^{96}$Cd and $^{98}$Cd. We report on recent measurements of $\beta$-delayed proton branching ratios for $^{96}$Ag, $^{98}$Ag, and $^{98}$Cd at the on-line mass separator at GSI.Comment: 4 pages, uses espcrc1.sty. Proceedings of the 4th International Symposium Nuclei in the Cosmos, June 1996, Notre Dame/IN, USA, Ed. M. Wiescher, to be published in Nucl.Phys.A. Also available at ftp://ftp.physics.ohio-state.edu/pub/nucex/nic96-gs

Insights on geochemical cycling of U, Re and Mo from seasonal sampling in Boston Harbor, Massachusetts, USA

Author Posting. © The Author(s), 2006. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 71 (2007): 895-917, doi:10.1016/j.gca.2006.10.016.This study examined the removal of U, Mo, and Re from seawater by sedimentary processes at a shallow-water site with near-saturation bottom water O2 levels (240-380 μmol O2/L), very high organic matter oxidation rates (annually averaged rate is 870 μmol C/cm2/y), and shallow oxygen penetration depths (4 mm or less throughout the year). Under these conditions, U, Mo, and Re were removed rapidly to asymptotic pore water concentrations of 2.2–3.3 nmol/kg (U), 7–13 nmol/kg (Mo), and 11–14 pmol/kg (Re). The order in which the three metals were removed, determined by fitting a diffusion-reaction model to measured profiles, was Re < U < Mo. Model fits also suggest that the Mo profiles clearly showed the presence of a near-interface layer in which Mo was added to pore waters by remineralization of a solid phase. The importance of this solid phase source of pore water Mo increased from January to October as the organic matter oxidation rate increased, bottom water O2 decreased, and the O2 penetration depth decreased. Experiments with in situ benthic flux chambers generally showed fluxes of U and Mo into the sediments. However, when the overlying water O2 concentration in the chambers was allowed to drop to very low levels, Mn and Fe were released to the overlying water along with the simultaneous release of Mo and U. These experiments suggest that remineralization of Mn and/or Fe oxides may be a source of Mo and perhaps U to pore waters, and may complicate the accumulation of U and Mo in bioturbated sediments with high organic matter oxidation rates and shallow O2 penetration depths. Benthic chamber experiments including the nonreactive solute tracer, Br-, indicated that sediment irrigation was very important to solute exchange at the study site. The enhancement of sediment-seawater exchange due to irrigation was determined for the nonreactive tracer (Br-), TCO2, NH4 +, U and Mo. The comparisons between these solutes showed that reactions within and around the burrows were very important for modulating the Mo flux, but less important for U. The effect of these reactions on Mo exchange was highly variable, enhancing Mo (and, to a lesser extent, U) uptake at times of relatively modest irrigation, but inhibiting exchange when irrigation rates were faster. These results reinforce the observation that Mo can be released to and removed from pore waters via sedimentary reactions. The removal rate of U and Mo from seawater by sedimentary reactions was found to agree with the rate of accumulation of authigenic U and Mo in the solid phase. The fluxes of U and Mo determined by in situ benthic flux chamber measurements were the largest that have been measured to date. These results confirm that removal of redoxsensitive metals from continental margin sediments underlying oxic bottom water is important, and suggest that continental margin sediments play a key role in the marine budgets of these metals.We appreciate the financial support from the National Science Foundation (OCE-0220892). Funding for this work was also provided to JLM by the Postdoctoral Scholar Program at WHOI courtesy of the Cabot Marine Environmental Science Fund and the J. Seward Johnson Fund. Financial support to IMK was given by The Swedish Foundation for International Cooperation in Research and Higher Education

280 GHz Focal Plane Unit Design and Characterization for the Spider-2 Suborbital Polarimeter

We describe the construction and characterization of the 280 GHz bolometric focal plane units (FPUs) to be deployed on the second flight of the balloon-borne Spider instrument. These FPUs are vital to Spider’s primary science goal of detecting or placing an upper limit on the amplitude of the primordial gravitational wave signature in the cosmic microwave background (CMB) by constraining the B-mode contamination in the CMB from Galactic dust emission. Each 280 GHz focal plane contains a 16×16 grid of corrugated silicon feedhorns coupled to an array of aluminum–manganese transition-edge sensor (TES) bolometers fabricated on 150 mm diameter substrates. In total, the three 280 GHz FPUs contain 1530 polarization-sensitive bolometers (765 spatial pixels) optimized for the low loading environment in flight and read out by time-division SQUID multiplexing. In this paper, we describe the mechanical, thermal, and magnetic shielding architecture of the focal planes and present cryogenic measurements which characterize yield and the uniformity of several bolometer parameters. The assembled FPUs have high yields, with one array as high as 95% including defects from wiring and readout. We demonstrate high uniformity in device parameters, finding the median saturation power for each TES array to be ∼ 3 pW at 300 mK with a less than 6% variation across each array at