Luminescence dating of canal sediments from Angkor Borei, Mekong Delta, Southern Cambodia     

David C.W. Sanderson  Paul Bishop  Miriam Stark  Sally Alexander  Dan Penny 《Quaternary Geochronology》2007,2(1-4):322-329

Work to apply luminescence dating to archaeological sites in the Lower Mekong Delta has continued with a programme aimed at dating ancient canal sediments and brick monuments in the vicinity of ancient city of Angkor Borei. Following the successful application of OSL dating to the Paris 2 canal near Angkor Borei further fieldwork and analysis has been undertaken. The infill and substrate of the larger Paris 4 canal connecting Angkor Borei to Oc Eo, some 80 km to the south in Vietnam has been sampled and subjected to luminescence analysis. Field spectroscopy and underwater bleaching experiments were also conducted in the Baray and Angkor Borei in 2004. The results show that both illumination intensities and spectral distributions are severely altered by as little as 1.5 m of turbid water, and that OSL bleaching rates for both quartz and feldspars are reduced. Since quartz resetting is heavily dependant on the UV components in daylight, which have preferentially attenuated the effects of turbid water on OSL zeroing rates are especially marked. The new data from the Paris 4 canal, which has been dated by OSL to be between the first millenium BC and the late first millenium AD are significant to understanding the archaeological development of the Fu Nan state in the Lower Mekong Delta, and the sequence of development of the canal network linking inland agrarian sites and coastal trading centres.  相似文献   

Dust in the core of the metal-rich globular cluster NGC 6356     

M. E. L. Hopwood  A. Evans  A. Penny  & S. P. S. Eyres 《Monthly notices of the Royal Astronomical Society》1998,301(2):30L-32L

We report the 3.5σ detection of dust in the core of the metal-rich ([Fe/H] =−0.4) globular cluster NGC 6356. The dust mass in the core is ∼ 4–17 × 10⁻³ M⊙, depending on the dust equilibrium temperature. We rule out sputtering as a grain destruction mechanism in NGC 6356, unless grains are very small (∼30 Å). We also place the upper limit of 6.6 × 10⁻³ on the CO-to-dust ratio in this cluster. This value is significantly smaller than the CO-to-dust ratio in the general Galactic interstellar medium, and in the outflows of evolved stars.  相似文献   

Temporal and spatial variability of biogenic particles fluxes during the JGOFS northeast Atlantic process studies at 47°N, 20°W     

Philip P. Newton  Richard S. Lampitt  Timothy D. Jickells  Penny King  Clare Boutle   《Deep Sea Research Part I: Oceanographic Research Papers》1994,41(11-12)

Particle fluxes to 3100 m depth at 45°50′N, 19°30′W were measured using time-series sediment traps during a 17 month period encompassing 1989 and 1990 JGOFS spring bloom process studies in the northeast Atlantic. There was a marked intra-annual variability in fluxes of mass, particulate inorganic carbon (PIC), particulate organic carbon (POC) and opal, appearing as two major flux events in each year. In 1989, the first flux event represented the settlement of spring bloom-type material, whereas the second, in autumn, was heavily enriched in mucopolysaccharides. In 1990, in contrast, the two flux events comprised spring bloom-type material and arrived at depth at different times relative to the 1989 events. The intra- and interannual variability evident for all three biogenic components was most notable for POC: (i) the autumn 1989 event supplied twice as much POC to 3100 m as the earlier spring bloom settlement—a quite unexpected observation—and (ii) the annual average POC flux in 1989 was 3–4 times more than in 1990. A synthesis of process study datasets with sediment trap data enables an evaluation of the coupling of deep fluxes with surface-water events. Spatial variability of the 1989 deep flux events is assessed by comparing the sediment trap data reported here with those from a second site 100 km away (Honjo and Manganini,Deep-Sea Research II,40, 587–607, 1993). The timing and magnitude of the 1989 spring bloom settlement was indistinguishable in the two datasets, indicating no spatial variability in flux between these sites. In contrast, the autumn 1989 flux event was barely recorded at the second site. Given the biogeochemical importance of this latter event to deep waters, most notable in terms of its contribution to POC flux, this observation of deep-water mesoscale flux variability indicates a significant problem in determining regional carbon budgets. Construction of basin-scale budgets is a central goal of JGOFS and for this to be achieved further studies of mesoscale variability of particle flux are essential.  相似文献   

Lithospheric structure north of Scotland—I. P-wave modelling, deep reflection profiles and gravity     

R. Peter LL. Morgan  Penny J. Barton  Mike Warner  Joanna Morgan  Claire Price †  Kevin Jones 《Geophysical Journal International》2000,142(3):716-736

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Stardust interstellar dust calibration: Hydrocode modeling of impacts on Al‐1100 foil at velocities up to 300 km s−1 and validation with experimental data     

Mark C. PRICE  Anton T. KEARSLEY  Mark J. BURCHELL  Lauren E. HOWARD  Jon K. HILLIER  Natalie A. STARKEY  Penny J. WOZNIAKIEWICZ  Mike J. COLE 《Meteoritics & planetary science》2012,47(4):684-695

Abstract– We present initial results from hydrocode modeling of impacts on Al‐1100 foils, undertaken to aid the interstellar preliminary examination (ISPE) phase for the NASA Stardust mission interstellar dust collector tray. We used Ansys’ AUTODYN to model impacts of micrometer‐scale, and smaller projectiles onto Stardust foil (100 μm thick Al‐1100) at velocities up to 300 km s^?1. It is thought that impacts onto the interstellar dust collector foils may have been made by a combination of interstellar dust particles (ISP), interplanetary dust particles (IDP) on comet, and asteroid derived orbits, β micrometeoroids, nanometer dust in the solar wind, and spacecraft derived secondary ejecta. The characteristic velocity of the potential impactors thus ranges from <<1 to a few km s^?1 (secondary ejecta), approximately 4–25 km s^?1 for ISP and IDP, up to hundreds of km s^?1 for the nanoscale dust reported by Meyer‐Vernet et al. (2009) . There are currently no extensive experimental calibrations for the higher velocity conditions, and the main focus of this work was therefore to use hydrocode models to investigate the morphometry of impact craters, as a means to determine an approximate impactor speed, and thus origin. The model was validated against existing experimental data for impact speeds up to approximately 30 km s^?1 for particles ranging in density from 2.4 kg m^?3 (glass) to 7.8 kg m^?3 (iron). Interpolation equations are given to predict the crater depth and diameter for a solid impactor with any diameter between 100 nm and 4 μm and density between 2.4 and 7.8 kg m^?3.  相似文献   

Echelle spectroscopy of Ca ii HK activity in Southern Hemisphere planet search targets     

C. G. Tinney  Chris McCarthy  Hugh R. A. Jones  R. Paul Butler  Brad D. Carter  Geoffrey W. Marcy  Alan J. Penny 《Monthly notices of the Royal Astronomical Society》2002,332(3):759-763

We present the results of ultraviolet echelle spectroscopy of a sample of 59 F, G, K and M stars from the Anglo-Australian Planet Search target list. Ca  ii activity indices, which are essential in the interpretation of planet detection claims, have been determined for these stars and placed on the Mount Wilson R '_HK system.  相似文献   

A new upper limit on the reflected starlight from τ Bootis b     

Christopher Leigh  rew Collier Cameron  Keith Horne  Alan Penny  David James 《Monthly notices of the Royal Astronomical Society》2003,344(4):1271-1282

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A survey for planetary transits in the field of NGC 7789     

D. M. Bramich  Keith Horne  I. A. Bond  R. A. Street  A. Collier Cameron  B. Hood  J. Cooke  D. James  T. A. Lister  D. Mitchell  K. Pearson  A. Penny  A. Quirrenbach  N. Safizadeh  Y. Tsapras 《Monthly notices of the Royal Astronomical Society》2005,359(3):1096-1116

We present results from 30 nights of observations of the open cluster NGC 7789 with the Wide Field Camera on the Isaac Newton Telescope, La Palma. From ∼900 epochs, we obtained light curves and Sloan   r '− i '  colours for ∼33 000 stars, with ∼2400 stars having better than 1 per cent precision. We expected to detect ∼2 transiting hot Jupiter planets if 1 per cent of stars host such a companion and a typical hot Jupiter radius is  ∼1.2  R _J  . We find 24 transit candidates, 14 of which we can assign a period. We rule out the transiting planet model for 21 of these candidates using various robust arguments. For two candidates, we are unable to decide on their nature, although it seems most likely that they are eclipsing binaries as well. We have one candidate exhibiting a single eclipse, for which we derive a radius of  1.81^+0.09_−0.00  R _J  . Three candidates remain that require follow-up observations in order to determine their nature.  相似文献   

An exoplanet in orbit around τ¹ Gruis     

Hugh R. A. Jones  R. Paul Butler  C. G. Tinney  Geoffrey W. Marcy  Alan J. Penny  Chris McCarthy  Brad D. Carter 《Monthly notices of the Royal Astronomical Society》2003,341(3):948-952

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Use of Representative Climate Futures in impact and adaptation assessment     

Penny Whetton  Kevin Hennessy  John Clarke  Kathleen McInnes  David Kent 《Climatic change》2012,115(3-4):433-442

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