On the MBM12 Young Association

I present a comprehensive study of the MBM12 young association (MBM12A). By combining infrared (IR) photometry from the Two-Micron All-Sky Survey (2MASS) survey with new optical imaging and spectroscopy, I have performed a census of the MBM12A membership that is complete to 0.03 Msun (H~15) for a 1.75deg X 1.4deg field encompassing the MBM12 cloud. I find five new members with masses of 0.1-0.4 Msun and a few additional candidates that have not been observed spectroscopically. From an analysis of optical and IR photometry for stars in the direction of MBM12, I identify M dwarfs in the foreground and background of the cloud. By comparing the magnitudes of these stars to those of local field dwarfs, I arrive at a distance modulus 7.2+/-0.5 (275 pc) to the MBM12 cloud; it is not the nearest molecular cloud and is not inside the local bubble of hot ionized gas as had been implied by previous distance estimates of 50-100 pc. I have also used Li strengths and H-R diagrams to constrain the absolute and relative ages of MBM12A and other young populations; these data indicate ages of 2 +3/-1 Myr for MBM12A and 10 Myr for the TW Hya and Eta Cha associations. MBM12A may be a slightly evolved version of the aggregates of young stars within the Taurus dark clouds (~1 Myr) near the age of the IC 348 cluster (~2 Myr).Comment: to be published in The Astrophysical Journal, 41 pages, 14 figures, also found at http://cfa-www.harvard.edu/sfgroup/preprints.htm

Stratigraphy and Whole-Rock Amino Acid Geochronology of Key Holocene and Last Interglacial Carbonate Deposits in the Hawaiian Islands

We evaluated the utility of whole-rock amino acid racemization as a method for the stratigraphic correlation and dating of carbonate sediments in the Hawaiian Islands. D-alloisoleucine/L-isoleucine (A/I) ratios were determined for carbonate sand and sandstone samples from 25 localities in the archipelago. The superposition of A/I ratios within stratigraphic sections and the regional concordance of ratios within geological formations support the integrity of the method. To correlate the A/I ratios with an absolute chronology, comparisons were made with previously published uranium series dates on corals and with 14C dates on carbonate sand and organic material, including several new dates reported herein. The A/I mean from four marine isotope stage (MIS) 5e U-series calibration sites was 0.505 ± 0.027 (n = 11), and 12 "test sites" of previously uncertain or speculative geochronological age yielded an A/I mean of 0.445 ± 0.058 (n = 17). Similarly, extensive Holocene dunes on Moloka'i and Kaua'i were correlated by a mean A/I ratio of 0.266 ± 0.022 (n = 8) and equated with a 14C bulk sediment mean age of 8600 yr B.P. Our results indicate that the eolian dunes currently exposed in various localities in the Islands originated primarily during two major periods of dune formation, the last interglacial (MIS 5e) and the early Holocene (MIS 1). MIS 5e and MIS 1 A/I ratios from the Hawaiian Islands show close agreement with previous whole-rock studies in Bermuda and the Bahamas. We discuss these results in terms of their relevance to models of lithospheric flexure and to imposing constraints on the time frame for the extinction of fossil birds

The Geological Context of Middle Pleistocene Crater Lake Deposits and Fossil Birds at Ulupau Head, Oahu, Hawaiian Islands

Els dipòsits pleistocènics Llacunars del cràter Ulupau, a Oahu, contenen les restes fòssils més antigues d' ocells conegudes a les Illes Hawaïi. Aquests fòssils són importants per documentar les taxes evolutives a una varietat de línies d'ocells terrestres i aquàtics de les illes. Lanàlísí estratigràfic detallat revela diferents cicles deposicionals que comporten dipòsits llacunars interestratificats, colluvium i paleosòls. La conca volcànica va ser oberta per l'erosió marina prèvia al pic del darrer interglacial (estadi isotòpic marí, o 'MIS' Se), fa 125 ka, restringint l'edat dels sediments del Llac al Pleistocè Mitjà. Els tres cicles de deposició (Unitats III, IV i V) semblen estar estretament lligats a pujades interglacials amb una ciclicitat de 100 ka. Donada la complexitat de la successió dels sediments del cràter i el temps requerit per a la seva formació, és probable que la conca deillac s'omplís al Llarg de diferents interglacials, assolint una extensió màxima de més de 50 ha durant l'estadi MIS 11, fa W1S 400 ka. Aquesta és també la màxima edat probable de les capes fossilíferes més riques de la Unitat III, però no es pot excloure que siguin del MIS 9 (fa 300 ka). Els requeriments d'hàbitat probables de diferents elements de l'avifauna donen llum sobre la paleoecologia de la localitat durant el Pleistocè Mitjà.Summary Pleistocene lake deposits in Ulupau Crater on Oahu contain the oldest fossil bird remains known from the Hawaiian Islands. These fossils are important for docwnenting evolutionary rates in a variety of lineages of land and water birds from the islands. Detailed stratigraphic analysis reveals distinct cycles of deposition involving interbedded lacustrine deposits, coLluviwn, and paleosols. The volcanic basin was breached by marine erosion prior to the peak of the last interglaciation (marine isotope stage or 'MIS' Se) over 125 ky ago, constraining the age of the lake sediments to the middle Pleistocene. The three cycles of deposition (Units III, Iv; and V) appear to be closely linked with interglacial highstands with 100 ky cyclicity. Given the complexity of the succession of crater sediments and the time required for their formation, it is probable that the lake basin filled over several interglacials, reaching a maximwn extent of over 50 ha during MIS 11, about 400 ky ago. This is also the likely maximum age of the richest fossil beds in Unit Iv; but MIS 9 (300 ky) also remains a possibility. Probable habitat requirements of the various elements of the avifauna provide insights into the paleoecology of the site during the middle Pleistocene

Discovery of seven T Tauri stars and a brown dwarf candidate in the nearby TW Hydrae Association

We report the discovery of five T Tauri star systems, two of which are resolved binaries, in the vicinity of the nearest known region of recent star formation, the TW Hydrae Association. The newly discovered systems display the same signatures of youth (namely high X-ray flux, large Li abundance and strong chromospheric activity) and the same proper motion as the original five members. These similarities firmly establish the group as a bona fide T Tauri association, unique in its proximity to Earth and its complete isolation from any known molecular clouds. At an age of ~10 Myr and a distance of ~50 pc, the association members are excellent candidates for future studies of circumstellar disk dissipation and the formation of brown dwarfs and planets. Indeed, as an example, our speckle imaging revealed a faint, very likely companion 2" north of CoD-33 7795 (TWA 5). Its color and brightness suggest a spectral type ~M8.5 which, at an age of ~10^7 years, implies a mass ~20 M(Jupiter).Comment: 6 pages, 4 figures and 1 table. AAS LaTeX aas2pp4.sty. To be published in Ap

Long-term condition management for prisoners : improving the processes between community and prison

BACKGROUND: Prisoner populations have a disproportionately high prevalence of risk factors for long-term conditions (LTCs), and movement between community and prisons is a period of potential disruption in the ongoing monitoring and management of LTCs. METHOD: Nineteen qualitative interviews with staff, recruited by purposive sampling for professional background, were conducted to explore facilitators and barriers to screening, monitoring and medicines management for LTCs. RESULTS: There is variability in prisoner behaviours regarding bringing community GP-prescribed medication to prison following arrest and detention in police custody, which affects service ability regarding seamless continuation of community prescribing actions. Systems for actively inputting clinical data into existing, nationally agreed, electronic record templates for QOF monitoring are under-developed in prisons and such activity is dependent upon individual "enthusiast(s)". CONCLUSION: There is a pressing need to embed standardised QOF monitoring systems within an integrated community/prison commissioning framework, supported by connectivity between prison and community primary care records, including all activity related to QOF compliance

Extinction Maps Toward The Milky Way Bulge: Two-Dimensional And Three-Dimensional Tests With APOGEE

Galactic interstellar extinction maps are powerful and necessary tools for Milky Way structure and stellar population analyses, particularly toward the heavily reddened bulge and in the midplane. However, due to the difficulty of obtaining reliable extinction measures and distances for a large number of stars that are independent of these maps, tests of their accuracy and systematics have been limited. Our goal is to assess a variety of photometric stellar extinction estimates, including both two-dimensional and three-dimensional extinction maps, using independent extinction measures based on a large spectroscopic sample of stars toward the Milky Way bulge. We employ stellar atmospheric parameters derived from high-resolution H-band Apache Point Observatory Galactic Evolution Experiment (APOGEE) spectra, combined with theoretical stellar isochrones, to calculate line-of-sight extinction and distances for a sample of more than 2400 giants toward the Milky Way bulge. We compare these extinction values to those predicted by individual near-IR and near+mid-IR stellar colors, two-dimensional bulge extinction maps, and three-dimensional extinction maps. The long baseline, near+mid-IR stellar colors are, on average, the most accurate predictors of the APOGEE extinction estimates, and the two-dimensional and three-dimensional extinction maps derived from different stellar populations along different sightlines show varying degrees of reliability. We present the results of all of the comparisons and discuss reasons for the observed discrepancies. We also demonstrate how the particular stellar atmospheric models adopted can have a strong impact on this type of analysis, and discuss related caveats.NSF Astronomy & Astrophysics Postdoctoral Fellowship AST-1203017Physics Frontier Center/Joint Institute for Nuclear Astrophysics (JINA) PHY 08-22648U.S. National Science FoundationAlfred P. Sloan FoundationParticipating InstitutionsU.S. Department of Energy Office of Science ANR-12-BS05-0015-01Astronom

Overview of the spectrometer optical fiber feed for the Habitable-zone Planet Finder

The Habitable-zone Planet Finder (HPF) is a highly stabilized fiber fed precision radial velocity (RV) spectrograph working in the Near Infrared (NIR): 810 - 1280 nm . In this paper we present an overview of the preparation of the optical fibers for HPF. The entire fiber train from the telescope focus down to the cryostat is detailed. We also discuss the fiber polishing, splicing and its integration into the instrument using a fused silica puck. HPF was designed to be able to operate in two modes, High Resolution (HR- the only mode mode currently commissioned) and High Efficiency (HE). We discuss these fiber heads and the procedure we adopted to attach the slit on to the HR fibers.Comment: Presented at 2018 SPIE Astronomical Telescopes + Instrumentation, Austin, Texas, USA. 18 pages, 25 figures, and 2 table

A Prediction of Brown Dwarfs in Ultracold Molecular Gas

A recent model for the stellar initial mass function (IMF), in which the stellar masses are randomly sampled down to the thermal Jeans mass from hierarchically structured pre-stellar clouds, predicts that regions of ultra-cold CO gas, such as those recently found in nearby galaxies by Allen and collaborators, should make an abundance of Brown Dwarfs with relatively few normal stars. This result comes from the low value of the thermal Jeans mass, considering that the hierarchical cloud model always gives the Salpeter IMF slope above this lower mass limit. The ultracold CO clouds in the inner disk of M31 have T~3K and pressures that are probably 10 times higher than in the solar neighborhood. This gives a mass at the peak of the IMF equal to 0.01 Msun, well below the Brown Dwarf limit of 0.08 Msun. Using a functional approximation to the IMF, the ultracold clouds would have 50% of the star-like mass and 90% of the objects below the Brown Dwarf limit. The brightest of the Brown Dwarfs in M31 should have an apparent, extinction-corrected K-band magnitude of ~21 mag in their pre-main sequence phase.Comment: 13 pages, 2 figures, to be published in Astrophysical Journal, Vol 522, September 10, 199