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Sample records for deep field north

  1. A molecular line scan in the Hubble deep field north

    SciTech Connect

    Decarli, R.; Walter, F.; Colombo, D.; Da Cunha, E.; Rix, H.-W.; Carilli, C.; Riechers, D.; Cox, P.; Neri, R.; Downes, D.; Aravena, M.; Bell, E.; Bertoldi, F.; Daddi, E.; Sargent, M.; Ellis, R.; Lentati, L.; Maiolino, R.; Menten, K. M.; and others

    2014-02-20

    We present a molecular line scan in the Hubble Deep Field North (HDF-N) that covers the entire 3 mm window (79-115 GHz) using the IRAM Plateau de Bure Interferometer. Our CO redshift coverage spans z ≲ 0.45, 1 ≲ z ≲ 1.9 and all z ≳ 2. We reach a CO detection limit that is deep enough to detect essentially all z > 1 CO lines reported in the literature so far. We have developed and applied different line-searching algorithms, resulting in the discovery of 17 line candidates. We estimate that the rate of false positive line detections is ∼2/17. We identify optical/NIR counterparts from the deep ancillary database of the HDF-N for seven of these candidates and investigate their available spectral energy distributions. Two secure CO detections in our scan are identified with star-forming galaxies at z = 1.784 and at z = 2.047. These galaxies have colors consistent with the 'BzK' color selection and they show relatively bright CO emission compared with galaxies of similar dust continuum luminosity. We also detect two spectral lines in the submillimeter galaxy HDF 850.1 at z = 5.183. We consider an additional nine line candidates as high quality. Our observations also provide a deep 3 mm continuum map (1σ noise level = 8.6 μJy beam{sup –1}). Via a stacking approach, we find that optical/MIR bright galaxies contribute only to <50% of the star formation rate density at 1 < z < 3, unless high dust temperatures are invoked. The present study represents a first, fundamental step toward an unbiased census of molecular gas in 'normal' galaxies at high-z, a crucial goal of extragalactic astronomy in the ALMA era.

  2. A molecular scan in the Hubble Deep Field North

    NASA Astrophysics Data System (ADS)

    Decarli, Roberto; Walter, Fabian; Carilli, Chris; Riechers, Dominik

    2015-02-01

    Our understanding of galaxy evolution has traditionally been driven by pre-selection of galaxies based on their broad-band continuum emission. This approach is potentially biased, in particular against gas-rich systems at high-redshift which may be dust-obscured. To overcome this limitation, we have recently concluded a blind CO survey at 3mm in a region of the Hubble Deep Field North using the IRAM Plateau de Bure Interferometer. Our study resulted in 1) the discovery of the redshift of the bright SMG HDF850.1 (z = 5.183); 2) the discovery of a bright line identified as CO(2-1) arising from a BzK galaxy at z = 1.785, and of other 6 CO lines associated with various galaxies in the field; 3) the detection of a few lines (presumably CO(3-2) at z ~ 2) with no optical/NIR/MIR counterparts. These observational results allowed us to expand the parameter space of galaxy properties probed so far in high-z molecular gas studies. Most importantly, we could set first direct constraints on the cosmic evolution of the molecular gas content of the universe. The present study represents a first, fundamental step towards an unbiased census of molecular gas in `normal' galaxies at high-z, a crucial goal of extragalactic astronomy in the ALMA era.

  3. PHOTOMETRIC REDSHIFTS IN THE HAWAII-HUBBLE DEEP FIELD-NORTH (H-HDF-N)

    SciTech Connect

    Yang, G.; Xue, Y. Q.; Kong, X.; Wang, J.-X.; Yuan, Y.-F.; Zhou, H. Y.; Luo, B.; Brandt, W. N.; Alexander, D. M.; Bauer, F. E.; Cui, W.; Lehmer, B. D.; Wu, X.-B.; Yuan, F. E-mail: xuey@ustc.edu.cn

    2015-01-01

    We derive photometric redshifts (z {sub phot}) for sources in the entire (∼0.4 deg{sup 2}) Hawaii-Hubble Deep Field-North (H-HDF-N) field with the EAzY code, based on point-spread-function-matched photometry of 15 broad bands from the ultraviolet (U band) to mid-infrared (IRAC 4.5 μm). Our catalog consists of a total of 131,678 sources. We evaluate the z {sub phot} quality by comparing z {sub phot} with spectroscopic redshifts (z {sub spec}) when available, and find a value of normalized median absolute deviation σ{sub NMAD} = 0.029 and an outlier fraction of 5.5% (outliers are defined as sources having |z{sub phot} – z{sub spec} |/(1 + z{sub spec} ) > 0.15) for non-X-ray sources. More specifically, we obtain σ{sub NMAD} = 0.024 with 2.7% outliers for sources brighter than R = 23 mag, σ{sub NMAD} = 0.035 with 7.4% outliers for sources fainter than R = 23 mag, σ{sub NMAD} = 0.026 with 3.9% outliers for sources having z < 1, and σ{sub NMAD} = 0.034 with 9.0% outliers for sources having z > 1. Our z {sub phot} quality shows an overall improvement over an earlier z {sub phot} work that focused only on the central H-HDF-N area. We also classify each object as a star or galaxy through template spectral energy distribution fitting and complementary morphological parameterization, resulting in 4959 stars and 126,719 galaxies. Furthermore, we match our catalog with the 2 Ms Chandra Deep Field-North main X-ray catalog. For the 462 matched non-stellar X-ray sources (281 having z {sub spec}), we improve their z {sub phot} quality by adding three additional active galactic nucleus templates, achieving σ{sub NMAD} = 0.035 and an outlier fraction of 12.5%. We make our catalog publicly available presenting both photometry and z {sub phot}, and provide guidance on how to make use of our catalog.

  4. Photometric Redshifts in the Hawaii-Hubble Deep Field-North

    NASA Astrophysics Data System (ADS)

    Yang, Guang; Xue, Yongquan

    2015-08-01

    We derive photometric redshifts (\\zp) for sources in the entire (˜0.4 deg^2) Hawaii-Hubble Deep Field-North (H-HDF-N) field with the EAzY code, based on point spread function-matched photometry of 15 broad bands from the ultraviolet to mid-infrared (IRAC 4.5um). Our catalog consists of a total of 131,678 sources. We evaluate the \\zp~quality by comparing \\zp~with spectroscopic redshifts (\\zs) when available, and find a value of normalized median absolute deviation \\sigm=0.029 and an outlier fraction of 5.5\\% (outliers are defined as sources having |\\zp - \\zs|/(1+\\zs)>0.15) for non-X-ray sources. More specifically, we obtain \\sigm=0.024 with 2.7\\% outliers for sources brighter than R=23mag, \\sigm=0.035 with 7.4\\% outliers for sources fainter than R=23mag, \\sigm=0.026 with 3.9\\% outliers for sources having z<1, and \\sigm=0.034 with 9.0\\% outliers for sources having z>1. Our \\zp\\ quality shows an overall improvement over an earlier \\zp\\ work that focused only on the central H-HDF-N area. We also classify each object as star or galaxy through template spectral energy distribution fitting and complementary morphological parametrization, resulting in 4959 stars and 126,719 galaxies. Furthermore, we match our catalog with the 2Ms Chandra Deep Field-North main X-ray catalog. For the 462 matched non-stellar X-ray sources (281 having \\zs), we improve their \\zp~quality by adding three additional AGN templates, achieving \\sigm=0.035 and an outlier fraction of 12.5\\%. We make our catalog publicly available presenting both photometry and \\zp, and provide guidance on how to make use of our catalog. (This work has been published as Yang, Xue, et al. 2014, ApJS, 215, 27; December 2014.)

  5. Photometric Redshifts in the Hawaii-Hubble Deep Field-North (H-HDF-N)

    NASA Astrophysics Data System (ADS)

    Yang, G.; Xue, Y. Q.; Luo, B.; Brandt, W. N.; Alexander, D. M.; Bauer, F. E.; Cui, W.; Kong, X.; Lehmer, B. D.; Wang, J.-X.; Wu, X.-B.; Yuan, F.; Yuan, Y.-F.; Zhou, H. Y.

    2014-12-01

    We derive photometric redshifts (z phot) for sources in the entire (~0.4 deg2) Hawaii-Hubble Deep Field-North (H-HDF-N) field with the EAzY code, based on point-spread-function-matched photometry of 15 broad bands from the ultraviolet (U band) to mid-infrared (IRAC 4.5 μm). Our catalog consists of a total of 131,678 sources. We evaluate the z phot quality by comparing z phot with spectroscopic redshifts (z spec) when available, and find a value of normalized median absolute deviation σNMAD = 0.029 and an outlier fraction of 5.5% (outliers are defined as sources having |zphot - zspec |/(1 + zspec ) > 0.15) for non-X-ray sources. More specifically, we obtain σNMAD = 0.024 with 2.7% outliers for sources brighter than R = 23 mag, σNMAD = 0.035 with 7.4% outliers for sources fainter than R = 23 mag, σNMAD = 0.026 with 3.9% outliers for sources having z < 1, and σNMAD = 0.034 with 9.0% outliers for sources having z > 1. Our z phot quality shows an overall improvement over an earlier z phot work that focused only on the central H-HDF-N area. We also classify each object as a star or galaxy through template spectral energy distribution fitting and complementary morphological parameterization, resulting in 4959 stars and 126,719 galaxies. Furthermore, we match our catalog with the 2 Ms Chandra Deep Field-North main X-ray catalog. For the 462 matched non-stellar X-ray sources (281 having z spec), we improve their z phot quality by adding three additional active galactic nucleus templates, achieving σNMAD = 0.035 and an outlier fraction of 12.5%. We make our catalog publicly available presenting both photometry and z phot, and provide guidance on how to make use of our catalog.

  6. A sub-millimetre survey of dust enshrouded galaxies in the Hubble Deep Field North region

    NASA Astrophysics Data System (ADS)

    Borys, C. J.

    2002-12-01

    This thesis investigates the emission of sub-millimetre-wave radiation from galaxies in the Hubble Deep Field North region. The data were obtained from dedicated observing runs from our group and others using the SCUBA camera on the James Clerk Maxwell Telescope. The data were combined using techniques specifically developed here for low signal-to-noise source recovery. The sources found represent over 10% of all cosmological sources SCUBA has detected since it was commissioned. The number of sub-mm galaxies we detect account for a significant fraction of the sub-mm background, and we show that mild extrapolations can reproduce it entirely. We comment on their clustering properties, both with themselves and other high-redshift galaxy types. A multi-wavelength analysis of these galaxies shows that SCUBA sources do not all have similar properties, and are made of a collection including: star-forming radio galaxies; optically invisible objects; active galactic nuclei; and extremely red objects. Reasonable attempts to determine the redshift distribution of the sample show that SCUBA galaxies have a median redshift of around 2, and suggest that the global star formation rate may be dominated by such objects at redshifts beyond about 1. The thesis summarises the current state of extra-galactic sub-mm astronomy, and comments on how new surveys and detectors will allow us to place stronger constraints on the evolution properties of the high-redshift Universe. The research described here was made possible from grants by the Natural Science and Engineering Research Council of Canada, and a generous scholarship from the University of British Columbia.

  7. X-Ray Properties of Lyman Break Galaxies in the Hubble Deep Field North Region

    NASA Technical Reports Server (NTRS)

    Nandra, K.; Mushotzky, R. F.; Arnaud, K.; Steidel, C. C.; Adelberger, K. L.; Gardner, J. P.; Teplitz, H. I.; Windhorst, R. A.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We describe the X-ray properties of a large sample of z approximately 3 Lyman Break Galaxies (LBGs) in the region of the Hubble Deep Field North, derived from the 1 Ms public Chandra observation. Of our sample of 148 LBGs, four are detected individually. This immediately gives a measure of the bright AGN (active galactic nuclei) fraction in these galaxies of approximately 3 per cent, which is in agreement with that derived from the UV (ultraviolet) spectra. The X-ray color of the detected sources indicates that they are probably moderately obscured. Stacking of the remainder shows a significant detection (6 sigma) with an average luminosity of 3.5 x 10(exp 41) erg/s per galaxy in the rest frame 2-10 keV band. We have also studied a comparison sample of 95 z approximately 1 "Balmer Break" galaxies. Eight of these are detected directly, with at least two clear AGN based on their high X-ray luminosity and very hard X-ray spectra respectively. The remainder are of relatively low luminosity (< 10(exp 42) erg/s, and the X-rays could arise from either AGN or rapid star-formation. The X-ray colors and evidence from other wavebands favor the latter interpretation. Excluding the clear AGN, we deduce a mean X-ray luminosity of 6.6 x 10(exp 40) erg/s, a factor approximately 5 lower than the LBGs. The average ratio of the UV and X-ray luminosities of these star forming galaxies L(sub UV)/L (sub X), however, is approximately the same at z = 1 as it is at z = 3. This scaling implies that the X-ray emission follows the current star formation rate, as measured by the UV luminosity. We use our results to constrain the star formation rate at z approximately 3 from an X-ray perspective. Assuming the locally established correlation between X-ray and far-IR (infrared) luminosity, the average inferred star formation rate in each Lyman break galaxy is found to be approximately 60 solar mass/yr, in excellent agreement with the extinction-corrected UV estimates. This provides an external

  8. The Evolution of Early-type Field Galaxies Selected from a NICMOS Map of the Hubble Deep Field North

    SciTech Connect

    Somerville, R; Stanford, S A; Budavari, T; Conselice, C J

    2004-03-03

    The redshift distribution of well-defined samples of distant early-type galaxies offers a means to test the predictions of monolithic and hierarchical galaxy formation scenarios. NICMOS maps of the entire Hubble Deep Field North in the F110W and F160W filters, when combined with the available WFPC2 data, allow us to calculate photometric redshifts and determine the morphological appearance of galaxies at rest-frame optical wavelengths out to z {approx} 2.5. Here we report results for two subsamples of early-type galaxies, defined primarily by their morphologies in the F160W band, which were selected from the NICMOS data down to H{sub 160AB} < 24.0. A primary subsample is defined as the 34 galaxies with early-type galaxy morphologies and early-type galaxy spectral energy distributions. The secondary subsample is defined as those 42 objects which have early-type galaxy morphologies with non-early type galaxy spectral energy distributions. The observed redshift distributions of our two early-type samples do not match that predicted by a monolithic collapse model, which shows an overabundance at z > 1.5. A (V/V{sub max}) test confirms this result. When the effects of passive luminosity evolution are included in the calculation, the mean value of Vmax for the primary sample is 0.22 {+-} 0.05, and 0.31 {+-} 0.04 for all the early-types. A hierarchical formation model better matches the redshift distribution of the HDF-N early-types at z > 1.5, but still does not adequately describe the observed early-types. The hierarchical model predicts significantly bluer colors on average than the observed early-type colors, and underpredicts the observed number of early-types at z {approx} 2. Though the observed redshift distribution of the early-type galaxies in our HDF-NICMOS sample is better matched by a hierarchical galaxy formation model, the reliability of this conclusion is tempered by the restricted sampling area and relatively small number of early-type galaxies selected by

  9. The Chandra Deep Survey of the Hubble Deep Field-North Area. II. Results from the Caltech Faint Field Galaxy Redshift Survey Area

    NASA Astrophysics Data System (ADS)

    Hornschemeier, A. E.; Brandt, W. N.; Garmire, G. P.; Schneider, D. P.; Barger, A. J.; Broos, P. S.; Cowie, L. L.; Townsley, L. K.; Bautz, M. W.; Burrows, D. N.; Chartas, G.; Feigelson, E. D.; Griffiths, R. E.; Lumb, D.; Nousek, J. A.; Ramsey, L. W.; Sargent, W. L. W.

    2001-06-01

    A deep X-ray survey of the Hubble Deep Field-North (HDF-N) and its environs is performed using data collected by the Advanced CCD Imaging Spectrometer (ACIS) on board the Chandra X-Ray Observatory. Currently a 221.9 ks exposure is available, the deepest ever presented, and here we give results on X-ray sources located in the 8.6‧×8.7‧ area covered by the Caltech Faint Field Galaxy Redshift Survey (the ``Caltech area''). This area has (1) deep photometric coverage in several optical and near-infrared bands; (2) extensive coverage at radio, submillimeter, and mid-infrared wavelengths; and (3) some of the deepest and most complete spectroscopic coverage ever obtained. It is also where the X-ray data have the greatest sensitivity; the minimum detectable fluxes in the 0.5-2 keV (soft) and 2-8 keV (hard) bands are ~1.3×10-16 and ~6.5×10-16 ergs cm-2 s-1, respectively. More than ~80% of the extragalactic X-ray background in the hard band is resolved. The 82 Chandra sources detected in the Caltech area are correlated with more than 25 multiwavelength source catalogs, and the results of these correlations as well as spectroscopic follow-up results obtained with the Keck and Hobby-Eberly Telescopes are presented. All but nine of the Chandra sources are detected optically with R<~26.5. Redshifts are available for 39% of the Chandra sources, including 96% of the sources with R<23 the redshift range is 0.1-3.5, with most sources having z<1.5. Eight of the X-ray sources are located in the HDF-N itself, including two not previously reported. A population of X-ray faint, optically bright, nearby galaxies emerges at soft-band fluxes of <~3×10-16 ergs cm-2 s-1. Our multiwavelength correlations have set the tightest constraints to date on the X-ray emission properties of μJy radio sources, mid-infrared sources detected by the Infrared Space Observatory (ISO), and very red (R-Ks>5.0) objects. A total of 16 of the 67 1.4 GHz μJy sources in the Caltech area are detected in the

  10. Hubble Deep Fields

    NASA Astrophysics Data System (ADS)

    Ferguson, H.; Murdin, P.

    2000-11-01

    The Hubble Deep Fields are two small areas of the sky that were carefully selected for deep observations by the HUBBLE SPACE TELESCOPE (HST). They represent the deepest optical observations to date and reveal galaxies as faint as V=30, 4 billion times fainter than can be seen with the unaided eye....

  11. The Capodimonte Deep Field

    NASA Astrophysics Data System (ADS)

    2001-04-01

    x 1060 pix - 870k] [Hi-Res - JPEG: 2768 x 3668 pix - 6.2M] Caption : A further enlargement of a galaxy cluster of which most members are located in the north-east quadrant (upper left) and have a reddish colour. The nebulous object to the upper left is a dwarf galaxy of spheroidal shape. The red object, located near the centre of the field and resembling a double star, is very likely a gravitational lens [2]. Some of the very red, point-like objects in the field may be distant quasars, very-low mass stars or, possibly, relatively nearby brown dwarf stars. The field shown covers 1380 x 1630 pixels, or 5.5 x 6.5 arcmin 2. ESO PR Photo 15e/01 ESO PR Photo 15e/01 [Preview - JPEG: 400 x 418 pix - 56k] [Normal - JPEG: 800 x 835 pix - 700k] [Hi-Res - JPEG: 3000 x 3131 pix - 5.0M] Caption : Enlargement of a moderately distant galaxy cluster in the south-east quadrant (lower left) of the OACDF2 field. The field measures 1380 x 1260 pixels, or about 5.5 x 5.0 arcmin 2 in the sky. ESO PR Photo 15f/01 ESO PR Photo 15f/01 [Preview - JPEG: 449 x 400 pix - 68k] [Normal - JPEG: 897 x 800 pix - 799k] [Hi-Res - JPEG: 3000 x 2675 pix - 5.6M] Caption : Enlargement of the elliptical galaxy that is located to the west (right) in the OACDF2 field. The numerous tiny objects surrounding the galaxy may be globular clusters. The fuzzy object on the right edge of the field may be a dwarf spheroidal galaxy. The size of the field is about 6 x 5 arcmin 2. Technical Information about the OACDF Survey The observations for the OACDF project were performed in three different ESO periods (18-22 April 1999, 7-12 March 2000 and 26-30 April 2000). Some 100 Gbyte of raw data were collected during each of the three observing runs. The first OACDF run was done just after the commissioning of the ESO-WFI. The observational strategy was to perform a 1 x 1 deg 2 short-exposure ("shallow") survey and then a 0.5 x 1 deg 2 "deep" survey. The shallow survey was performed in the B, V, R and I broad-band filters

  12. North Pacific Acoustic Laboratory and Deep Water Acoustics

    DTIC Science & Technology

    2015-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. North Pacific Acoustic Laboratory and Deep Water...coherence of the received signal, while the ambient noise field is in direct competition with the received signal. Research conducted in the North Pacific ...The scientific objectives of the North Pacific Acoustic Laboratory and Deep Water Acoustics research are: 1. To study the spatial and temporal

  13. Geomagnetic field intensity, North Atlantic Deep Water circulation and atmospheric Δ 14C during the last 50 kyr

    NASA Astrophysics Data System (ADS)

    Laj, Carlo; Kissel, Catherine; Mazaud, Alain; Michel, Elisabeth; Muscheler, Raimund; Beer, Juerg

    2002-06-01

    We present simulated records of past changes in the atmospheric Δ 14C for the last 50 kyr due to changes in geomagnetic field intensity and in the strength of the North Atlantic Deep Water (NADW). A new geomagnetic record was used, largely based on the NAPIS-75 record [Laj et al., Phil. Trans. R. Soc. London A 358 (2000) 1009-1025] which has been extended for the 0-20 kyr interval using archeomagnetic and volcanic data. Past changes of the NADW were derived from a mineral magnetic study of the cores used in the construction of NAPIS-75. Two box models of different complexity (4 and 17 boxes) were used to simulate the carbon cycle. Calculated records of Δ 14C are consistent with experimental determinations for the last 24 kyr. For older ages, the records calculated with variable oceanic circulation conditions reach values as high as 600‰ (with an average of 500‰) between 20 and 40 kyr with maxima around 21, 30 and 38 kyr (GISP2 age model), while low values are observed prior to 42 kyr. Although large inconsistencies in experimental data preclude precise comparison, the average record simulated with the 17-box model is overall consistent with the Icelandic Sea record [Voelker et al., Radiocarbon 40 (1998) 517-534; 42 (2000) 437-452], except for the extremely high peak observed in this record at 40.5 kyr. On the other hand, the results recently reported from a stalagmite recovered from a submerged cave in the Bahamas [Beck et al., Science 292 (2001) 2453-2458] are inconsistent with all our model simulations. In the 20-45 kyr interval, the improved geomagnetic record combined with the new NADW profile allows us to give a modeled evaluation of the relative contribution of these factors to changes in atmospheric Δ 14C. The average simulation provides a first order modeled correction for conventional radiocarbon ages older than 25 kyr for which no calibration curve is available as yet.

  14. Sand remobilization enhanced complexity to mounded geometry, Early Tertiary deep water sand reservoirs, Balder Oil Field North Sea

    SciTech Connect

    Bergslien, D.; Rye-Larsen, M.; Jenssen, A.I.

    1996-12-31

    Sand remobilization played a major role in generating the high relief mounded geometries that trap oil in the early Tertiary reservoirs at Balder Field in Norwegian North Sea blocks 25/10 and 25/11. The thick massive submarine-fan sandstones were shed from the East Shetland Platform and deposited from high density turbidity currents. These thick massive sandstones lie in the distal portions of the fan system on the northwestern margin of the Utsira High. An intricate interaction between deposition and soft sediment deformation processes generated the complex cluster of thick mounded sand geometries comprising the Balder oil field. Slumping, sliding and sand remobilization with associated sand injections into overlying shales were the dominant deformation processes that mainly occurred during the early Eocene. The field is comprised of three reservoirs, the Paleocene Heimdal and Hermod Formations and the Early Eocene Balder Formation. The sandstones, which have excellent reservoir properties, share a common pressure system and oil-water contact. This is probably related to the soft-sediment deformation and associated sand injections establishing cross-stratal communication.

  15. Sand remobilization enhanced complexity to mounded geometry, Early Tertiary deep water sand reservoirs, Balder Oil Field North Sea

    SciTech Connect

    Bergslien, D.; Rye-Larsen, M.; Jenssen, A.I. )

    1996-01-01

    Sand remobilization played a major role in generating the high relief mounded geometries that trap oil in the early Tertiary reservoirs at Balder Field in Norwegian North Sea blocks 25/10 and 25/11. The thick massive submarine-fan sandstones were shed from the East Shetland Platform and deposited from high density turbidity currents. These thick massive sandstones lie in the distal portions of the fan system on the northwestern margin of the Utsira High. An intricate interaction between deposition and soft sediment deformation processes generated the complex cluster of thick mounded sand geometries comprising the Balder oil field. Slumping, sliding and sand remobilization with associated sand injections into overlying shales were the dominant deformation processes that mainly occurred during the early Eocene. The field is comprised of three reservoirs, the Paleocene Heimdal and Hermod Formations and the Early Eocene Balder Formation. The sandstones, which have excellent reservoir properties, share a common pressure system and oil-water contact. This is probably related to the soft-sediment deformation and associated sand injections establishing cross-stratal communication.

  16. LOFAR/H-ATLAS: a deep low-frequency survey of the Herschel-ATLAS North Galactic Pole field

    NASA Astrophysics Data System (ADS)

    Hardcastle, M. J.; Gürkan, G.; van Weeren, R. J.; Williams, W. L.; Best, P. N.; de Gasperin, F.; Rafferty, D. A.; Read, S. C.; Sabater, J.; Shimwell, T. W.; Smith, D. J. B.; Tasse, C.; Bourne, N.; Brienza, M.; Brüggen, M.; Brunetti, G.; Chyży, K. T.; Conway, J.; Dunne, L.; Eales, S. A.; Maddox, S. J.; Jarvis, M. J.; Mahony, E. K.; Morganti, R.; Prandoni, I.; Röttgering, H. J. A.; Valiante, E.; White, G. J.

    2016-10-01

    We present Low-Frequency Array (LOFAR) High-Band Array observations of the Herschel-ATLAS North Galactic Pole survey area. The survey we have carried out, consisting of four pointings covering around 142 deg2 of sky in the frequency range 126-173 MHz, does not provide uniform noise coverage but otherwise is representative of the quality of data to be expected in the planned LOFAR wide-area surveys, and has been reduced using recently developed `facet calibration' methods at a resolution approaching the full resolution of the data sets (˜10 × 6 arcsec) and an rms off-source noise that ranges from 100 μJy beam-1 in the centre of the best fields to around 2 mJy beam-1 at the furthest extent of our imaging. We describe the imaging, cataloguing and source identification processes, and present some initial science results based on a 5σ source catalogue. These include (i) an initial look at the radio/far-infrared correlation at 150 MHz, showing that many Herschel sources are not yet detected by LOFAR; (ii) number counts at 150 MHz, including, for the first time, observational constraints on the numbers of star-forming galaxies; (iii) the 150-MHz luminosity functions for active and star-forming galaxies, which agree well with determinations at higher frequencies at low redshift, and show strong redshift evolution of the star-forming population; and (iv) some discussion of the implications of our observations for studies of radio galaxy life cycles.

  17. North Atlantic Deep Water Formation

    NASA Technical Reports Server (NTRS)

    Bennett, T. (Editor); Broecker, W. S. (Editor); Hansen, J. (Editor)

    1984-01-01

    Various studies concerning differing aspects of the North Atlantic are presented. The three major topics under which the works are classified include: (1) oceanography; (2) paleoclimate; and (3) ocean, ice and climate modeling.

  18. Ultra-deep Large Binocular Camera U-band Imaging of the GOODS-North Field: Depth vs. Resolution

    NASA Astrophysics Data System (ADS)

    Ashcraft, Teresa; Windhorst, Rogier A.; Jansen, Rolf A.; Cohen, Seth H.; Grazian, Andrea; Boutsia, Konstantina; Fontana, Adriano; Giallongo, Emanuele; O'Connell, Robert W.; Paris, Diego; Rutkowski, Michael J.; Scarlata, Claudia; Testa, Vincenzo

    2017-01-01

    We present a study of the trade-off between depth and resolution using a large number of U-band images in the GOODS-North field obtained with the Large Binocular Camera (LBC) on the Large Binocular Telescope (LBT). Having acquired over 30 hours of total exposure time (315 images, each 5-6 min), we generated multiple image mosaics, starting with the subset of images with the best (FWHM < 0."8) atmospheric seeing (~10% of the total data set). For subsequent mosaics, we added in data with larger seeing values until the final, deepest mosaic included all images with FWHM < 1."8 (~94% of the total data set). For each mosaic, we created object catalogs to compare the optimal-resolution, yet shallower image to the low-resolution but deeper image and found the number counts for both images are ~90% complete to AB = 26 mag. In the optimal-resolution image, object counts start to drop-off dramatically, fainter than AB ~ 27 mag, while in the deepest image the drop is more gradual because of the better surface-brightness sensitivity ( SB ~ 32 mag arcsec-2). We conclude that for studies of brighter galaxies and features within them, the optimal-resolution image should be used. However, to fully explore and understand the faintest objects, the deeper imaging with lower resolution are also required. We also discuss how high-resolution F336W HST data complements our LBT mosaics.For 220 brighter galaxies with U < 24 mag, we find only marginal differences (< 0.07 mag in total integrated flux) between the optimal-resolution and low-resolution light-profiles to SB ~ 32 mag arcsec-2. This helps constrain how much flux can be missed in galaxy outskirts, which is important for studies of Extragalactic Background Light.In the future, we will expand our analysis of the GOODS-N field to ~26 hours of LBT/LBC R-band surface photometry to similar depths.

  19. Post-Drilling Changes in Seabed Landscape and Megabenthos in a Deep-Sea Hydrothermal System, the Iheya North Field, Okinawa Trough

    PubMed Central

    Nakajima, Ryota; Yamamoto, Hiroyuki; Kawagucci, Shinsuke; Takaya, Yutaro; Nozaki, Tatsuo; Chen, Chong; Fujikura, Katsunori; Miwa, Tetsuya; Takai, Ken

    2015-01-01

    There has been an increasing interest in seafloor exploitation such as mineral mining in deep-sea hydrothermal fields, but the environmental impact of anthropogenic disturbance to the seafloor is poorly known. In this study, the effect of such anthropogenic disturbance by scientific drilling operations (IODP Expedition 331) on seabed landscape and megafaunal habitation was surveyed for over 3 years using remotely operated vehicle video observation in a deep-sea hydrothermal field, the Iheya North field, in the Okinawa Trough. We focused on observations from a particular drilling site (Site C0014) where the most dynamic change of landscape and megafaunal habitation was observed among the drilling sites of IODP Exp. 331. No visible hydrothermal fluid discharge had been observed at the sedimentary seafloor at Site C0014, where Calyptogena clam colonies were known for more than 10 years, before the drilling event. After drilling commenced, the original Calyptogena colonies were completely buried by the drilling deposits. Several months after the drilling, diffusing high-temperature hydrothermal fluid began to discharge from the sedimentary subseafloor in the area of over 20 m from the drill holes, ‘artificially’ creating a new hydrothermal vent habitat. Widespread microbial mats developed on the seafloor with the diffusing hydrothermal fluids and the galatheid crab Shinkaia crosnieri endemic to vents dominated the new vent community. The previously soft, sedimentary seafloor was hardened probably due to barite/gypsum mineralization or silicification, becoming rough and undulated with many fissures after the drilling operation. Although the effects of the drilling operation on seabed landscape and megafaunal composition are probably confined to an area of maximally 30 m from the drill holes, the newly established hydrothermal vent ecosystem has already lasted 2 years and is like to continue to exist until the fluid discharge ceases and thus the ecosystem in the area

  20. Post-drilling changes in seabed landscape and megabenthos in a deep-sea hydrothermal system, the Iheya North field, Okinawa Trough.

    PubMed

    Nakajima, Ryota; Yamamoto, Hiroyuki; Kawagucci, Shinsuke; Takaya, Yutaro; Nozaki, Tatsuo; Chen, Chong; Fujikura, Katsunori; Miwa, Tetsuya; Takai, Ken

    2015-01-01

    There has been an increasing interest in seafloor exploitation such as mineral mining in deep-sea hydrothermal fields, but the environmental impact of anthropogenic disturbance to the seafloor is poorly known. In this study, the effect of such anthropogenic disturbance by scientific drilling operations (IODP Expedition 331) on seabed landscape and megafaunal habitation was surveyed for over 3 years using remotely operated vehicle video observation in a deep-sea hydrothermal field, the Iheya North field, in the Okinawa Trough. We focused on observations from a particular drilling site (Site C0014) where the most dynamic change of landscape and megafaunal habitation was observed among the drilling sites of IODP Exp. 331. No visible hydrothermal fluid discharge had been observed at the sedimentary seafloor at Site C0014, where Calyptogena clam colonies were known for more than 10 years, before the drilling event. After drilling commenced, the original Calyptogena colonies were completely buried by the drilling deposits. Several months after the drilling, diffusing high-temperature hydrothermal fluid began to discharge from the sedimentary subseafloor in the area of over 20 m from the drill holes, 'artificially' creating a new hydrothermal vent habitat. Widespread microbial mats developed on the seafloor with the diffusing hydrothermal fluids and the galatheid crab Shinkaia crosnieri endemic to vents dominated the new vent community. The previously soft, sedimentary seafloor was hardened probably due to barite/gypsum mineralization or silicification, becoming rough and undulated with many fissures after the drilling operation. Although the effects of the drilling operation on seabed landscape and megafaunal composition are probably confined to an area of maximally 30 m from the drill holes, the newly established hydrothermal vent ecosystem has already lasted 2 years and is like to continue to exist until the fluid discharge ceases and thus the ecosystem in the area has

  1. High excitation emission line nebula associated with an ultra-luminous X-ray source at z = 0.027 in the AKARI North Ecliptic Pole Deep Field

    NASA Astrophysics Data System (ADS)

    Díaz Tello, J.; Miyaji, T.; Ishigaki, T.; Krumpe, M.; Ueda, Y.; Brunner, H.; Goto, T.; Hanami, H.; Toba, Y.

    2017-07-01

    Aims: We report our finding of a high excitation emission line nebula associated with an ultra-luminous X-ray source (ULX) at z= 0.027, which we found in our Chandra observation of the AKARI North Ecliptic Pole Deep Field. Methods: We present a Chandra X-ray and Gran Telescopio Canarias (GTC) optical spectral analysis of the ULX blob. We investigated the nature of the emission line nebula using line ratio diagnostic diagrams and estimated the physical properties of the nebula with spectral energy distribution (SED) fitting. Results: The optical spectrum of this ULX blob shows emission line ratios that are located on the borderlines between star formation and Seyfert regimes in [OIII]/Hβ-[OI]/Hα, [OIII]/Hβ-[SII]/Hα, and [OIII]/Hβ-[OIII]/[OII] diagnostic diagrams. These are in contrast with those of a nearby blob observed with the same slit, which occupies the HII regimes. Conclusions: This result suggests that the energy input from the accretion power of the ULX, in addition to the star formation activity in the blob, significantly contribute to the ionization of the emission line nebula associated with the ULX, suggesting the existence of an accretion disk in the ULX emitting UV radiation or exerting shock waves.

  2. A molecular line scan in the Hubble deep field north: Constraints on the co luminosity function and the cosmic H{sub 2} density

    SciTech Connect

    Walter, F.; Decarli, R.; Da Cunha, E.; Sargent, M.; Dickinson, M.; Daddi, E.; Riechers, D.; Ellis, R.; Stark, D.; Weiner, B.; Aravena, M.; Bell, E.; Bertoldi, F.; Cox, P.; Downes, D.; Neri, R.; Lentati, L.; Maiolino, R.; Menten, K. M.; and others

    2014-02-20

    We present direct constraints on the CO luminosity function at high redshift and the resulting cosmic evolution of the molecular gas density, ρ{sub H{sub 2}}(z), based on a blind molecular line scan in the Hubble Deep Field North (HDF-N) using the IRAM Plateau de Bure Interferometer. Our line scan of the entire 3 mm window (79-115 GHz) covers a cosmic volume of ∼7000 Mpc{sup 3}, and redshift ranges z < 0.45, 1.01 < z < 1.89 and z > 2. We use the rich multiwavelength and spectroscopic database of the HDF-N to derive some of the best constraints on CO luminosities in high redshift galaxies to date. We combine the blind CO detections in our molecular line scan (presented in a companion paper) with stacked CO limits from galaxies with available spectroscopic redshifts (slit or mask spectroscopy from Keck and grism spectroscopy from the Hubble Space Telescope) to give first blind constraints on high-z CO luminosity functions and the cosmic evolution of the H{sub 2} mass density ρ{sub H{sub 2}}(z) out to redshifts z ∼ 3. A comparison to empirical predictions of ρ{sub H{sub 2}}(z) shows that the securely detected sources in our molecular line scan already provide significant contributions to the predicted ρ{sub H{sub 2}}(z) in the redshift bins (z) ∼ 1.5 and (z) ∼ 2.7. Accounting for galaxies with CO luminosities that are not probed by our observations results in cosmic molecular gas densities ρ{sub H{sub 2}}(z) that are higher than current predictions. We note, however, that the current uncertainties (in particular the luminosity limits, number of detections, as well as cosmic volume probed) are significant, a situation that is about to change with the emerging ALMA observatory.

  3. Moytirra: Discovery of the first known deep-sea hydrothermal vent field on the slow-spreading Mid-Atlantic Ridge north of the Azores

    NASA Astrophysics Data System (ADS)

    Wheeler, A. J.; Murton, B.; Copley, J.; Lim, A.; Carlsson, J.; Collins, P.; Dorschel, B.; Green, D.; Judge, M.; Nye, V.; Benzie, J.; Antoniacomi, A.; Coughlan, M.; Morris, K.

    2013-10-01

    Geological, biological, morphological, and hydrochemical data are presented for the newly discovered Moytirra vent field at 45oN. This is the only high temperature hydrothermal vent known between the Azores and Iceland, in the North Atlantic and is located on a slow to ultraslow-spreading mid-ocean ridge uniquely situated on the 300 m high fault scarp of the eastern axial wall, 3.5 km from the axial volcanic ridge crest. Furthermore, the Moytirra vent field is, unusually for tectonically controlled hydrothermal vents systems, basalt hosted and perched midway up on the median valley wall and presumably heated by an off-axis magma chamber. The Moytirra vent field consists of an alignment of four sites of venting, three actively emitting "black smoke," producing a complex of chimneys and beehive diffusers. The largest chimney is 18 m tall and vigorously venting. The vent fauna described here are the only ones documented for the North Atlantic (Azores to Reykjanes Ridge) and significantly expands our knowledge of North Atlantic biodiversity. The surfaces of the vent chimneys are occupied by aggregations of gastropods (Peltospira sp.) and populations of alvinocaridid shrimp (Mirocaris sp. with Rimicaris sp. also present). Other fauna present include bythograeid crabs (Segonzacia sp.) and zoarcid fish (Pachycara sp.), but bathymodiolin mussels and actinostolid anemones were not observed in the vent field. The discovery of the Moytirra vent field therefore expands the known latitudinal distributions of several vent-endemic genera in the north Atlantic, and reveals faunal affinities with vents south of the Azores rather than north of Iceland.

  4. The mass-metallicity relation of AKARI-FMOS infrared galaxies at z ∼ 0.88 in the AKARI North Ecliptic Pole Deep Survey Field

    NASA Astrophysics Data System (ADS)

    Oi, Nagisa; Goto, Tomotsugu; Malkan, Matthew; Pearson, Chris; Matsuhara, Hideo

    2017-08-01

    The mass, metallicity, and star formation rate (SFR) of a galaxy are crucial parameters in understanding galaxy formation and evolution. However, the relation between these parameters, (i.e., the fundamental relation) is still a matter of debate for luminous infrared (IR) galaxies, which carry a bulk of the SFR budget of the universe at z ∼ 1. We have investigated the relation among stellar mass, gas-phase oxygen abundance, and SFR of the Japanese infrared satellite AKARI-detected mid-IR galaxies at z ∼ 0.88 in the AKARI north ecliptic pole deep field. We observed ∼350 AKARI sources with Subaru/Fiber Multi Object Spectrograph near-IR spectrograph, and detected confirmed Hα emission lines from 25 galaxies and expected Hα emission lines from 44 galaxies. The SFRHα, IR of our sample is almost constant (〈SFRHα, IR〉 = ∼ 25 M⊙ yr - 1) over the stellar mass range of our sample. Compared with main-sequence (MS) galaxies at a similar redshift range (z ∼ 0.78), the average SFR of our detected sample is comparable for massive galaxies ( ∼ 1010.58 M⊙), while higher by ∼0.6 dex for less massive galaxies ( ∼ 1010.05 M⊙). We measure metallicities from the [N II]/Hα emission line ratio. We find that the mass-metallicity relation of our individually measured sources agrees with that for optically-selected star-forming galaxies at z ∼ 0.1, while metallicities of stacked spectra agree with that of MS galaxies at z ∼ 0.78. Considering the high SFR of individually measured sources, the fundamental metallicity relation (FMR) of the IR galaxies is different from that at z ∼ 0.1. However, on the mass-metallicity plane, they are consistent with the MS galaxies, highlighting the higher SFR of the IR galaxies. This suggests that the evolutionary path of our infrared galaxies is different from that of MS galaxies. A possible physical interpretation includes that the star-formation activities of IR galaxies at z ∼ 0.88 in our sample are enhanced by

  5. A very deep IRAS survey at the north ecliptic pole

    NASA Technical Reports Server (NTRS)

    Houck, J. R.; Hacking, P. B.; Condon, J. J.

    1987-01-01

    The data from approximately 20 hours observation of the 4- to 6-square degree field surrounding the north ecliptic pole have been combined to produce a very deep IR survey at the four IRAS bands. Scans from both pointed and survey observations were included in the data analysis. At 12 and 25 microns the deep survey is limited by detector noise and is approximately 50 times deeper than the IRAS Point Source Catalog (PSC). At 60 microns the problems of source confusion and Galactic cirrus combine to limit the deep survey to approximately 12 times deeper than the PSC. These problems are so severe at 100 microns that flux values are only given for locations corresponding to sources selected at 60 microns. In all, 47 sources were detected at 12 microns, 37 at 25 microns, and 99 at 60 microns. The data-analysis procedures and the significance of the 12- and 60-micron source-count results are discussed.

  6. The North Carolina Field Test

    SciTech Connect

    Sharp, T.R.; Ternes, M.P.

    1990-08-01

    The North Carolina Field Test will test the effectiveness of two weatherization approaches: the current North Carolina Low-Income Weatherization Assistance Program and the North Carolina Field Test Audit. The Field Test Audit will differ from North Carolina's current weatherization program in that it will incorporate new weatherization measures and techniques, a procedure for basing measure selection of the characteristics of the individual house and the cost-effectiveness of the measure, and also emphasize cooling energy savings. The field test will determine the differences of the two weatherization approaches from the viewpoints of energy savings, cost effectiveness, and implementation ease. This Experimental Plan details the steps in performing the field test. The field test will be a group effort by several participating organizations. Pre- and post-weatherization data will be collected over a two-year period (November 1989 through August 1991). The 120 houses included in the test will be divided into a control group and two treatment groups (one for each weatherization procedure) of 40 houses each. Weekly energy use data will be collected for each house representing whole-house electric, space heating and cooling, and water heating energy uses. Corresponding outdoor weather and house indoor temperature data will also be collected. The energy savings of each house will be determined using linear-regression based models. To account for variations between the pre- and post-weatherization periods, house energy savings will be normalized for differences in outdoor weather conditions and indoor temperatures. Differences between the average energy savings of treatment groups will be identified using an analysis of variance approach. Differences between energy savings will be quantified using multiple comparison techniques. 9 refs., 8 figs., 5 tabs.

  7. Tests for orbital influences on the geomagnetic field, and Quarternary magnetic records from North Atlantic and Arctic deep-sea sediments

    NASA Astrophysics Data System (ADS)

    Xuan, Chuang

    This dissertation investigated the possible connection between orbital variations and the Earth's magnetic field, and the origin of orbital periods in sedimentary relative paleointensity (RPI) records, using previously published data. Circular statistic methods were utilized to test whether there is any consistent relationship between the phase of orbital parameters and the timing of geomagnetic reversals or excursions. The results indicate no discernable tendency, disagreeing with orbital forcing on the geodynamo. Numerical simulations further indicate that precision of the current polarity timescales need to be improved for any firm relationship to be established. Wavelet analyses methods were employed to investigate the origin of orbital periods in the RPI records. In some records, significant coherence at orbital periods occurs between RPI and a particular magnetic grain-size proxy. Therefore, orbital periods in some RPI records are attributed to lithologic 'contamination' resulted from incomplete normalization of the natural remanent magnetization (NRM) record. Comparison of RPI records from different regions of the world in both the time and time-frequency domains imply that the 'contamination' does not debilitate most RPI records as a global signal that is primarily of geomagnetic origin. Calibrated RPI and oxygen isotope stack records (PISO-1500) were developed by simultaneously matching and stacking both RPI and oxygen isotope data for 13 pairs of high-resolution global records. Wavelet analyses on the PISO-1500 RPI stack record failed to show significant orbital periods, and no tendencies were found for RPI minima in the stack to occur at particular phases of orbital variations. The generation of high-resolution paleomagnetic data is often associated with processing large volumes of measurement data. MATLAB(TM) software with graphical user interfaces was developed in this dissertation work to improve the efficiency of processing large volumes of

  8. The deep Madden Field, a super-deep Madison gas reservoir, Wind River Basin, Wyoming

    SciTech Connect

    Moore, C.H. ); Hawkins, C. )

    1996-01-01

    Madison dolomites form the reservoir of a super deep, potential giant sour gas field developed on the Madden Anticline immediately in front of the Owl Creek Thrust along the northern rim of the Wind River Basin, central Wyoming. The Madison reservoir dolomites are presently buried to some 25,000 feet at Madden Field and exhibit porosity in excess of 15%. An equivalent dolomitized Madison sequence is exposed in outcrop only 5 miles to the north on the hanging wall of the Owl Creek thrust at Lysite Mountain. Preliminary comparative stratigraphic, geochemical and petrologic data, between outcrop and available cores and logs at Deep Madden suggests: (1) early, sea level-controlled, evaporite-related dolomitization of the reservoir and outcrop prior to significant burial; (2) both outcrop and deep reservoir dolomites underwent significant recrystallization during a common burial history until their connection was severed during Laramide faulting in the Eocene; (3) While the dolomite reservoir at Madden suffered additional diagenesis during an additional 7-10 thousand feet of burial, the pore systems between outcrop and deep reservoir are remarkably similar. The two existing deep Madison wells at Madden are on stream, with a third deep Madison well currently drilling. The sequence stratigraphic framework and the diagenetic history of the Madison strongly suggests that outcrops and surface cores of the Madison in the Owl Creek Mountains will be useful in further development and detailed reservoir modeling of the Madden Deep Field.

  9. The deep Madden Field, a super-deep Madison gas reservoir, Wind River Basin, Wyoming

    SciTech Connect

    Moore, C.H.; Hawkins, C.

    1996-12-31

    Madison dolomites form the reservoir of a super deep, potential giant sour gas field developed on the Madden Anticline immediately in front of the Owl Creek Thrust along the northern rim of the Wind River Basin, central Wyoming. The Madison reservoir dolomites are presently buried to some 25,000 feet at Madden Field and exhibit porosity in excess of 15%. An equivalent dolomitized Madison sequence is exposed in outcrop only 5 miles to the north on the hanging wall of the Owl Creek thrust at Lysite Mountain. Preliminary comparative stratigraphic, geochemical and petrologic data, between outcrop and available cores and logs at Deep Madden suggests: (1) early, sea level-controlled, evaporite-related dolomitization of the reservoir and outcrop prior to significant burial; (2) both outcrop and deep reservoir dolomites underwent significant recrystallization during a common burial history until their connection was severed during Laramide faulting in the Eocene; (3) While the dolomite reservoir at Madden suffered additional diagenesis during an additional 7-10 thousand feet of burial, the pore systems between outcrop and deep reservoir are remarkably similar. The two existing deep Madison wells at Madden are on stream, with a third deep Madison well currently drilling. The sequence stratigraphic framework and the diagenetic history of the Madison strongly suggests that outcrops and surface cores of the Madison in the Owl Creek Mountains will be useful in further development and detailed reservoir modeling of the Madden Deep Field.

  10. The AGN Population in the Akari NEP Deep Field

    NASA Astrophysics Data System (ADS)

    Barrufet de Soto, Laia; White, Glenn J.; Pearson, Chris; Serjeant, Stephen; Lim, Tanya; Matsuhara, Hideo; Oi, Nagisa; Karouzos, Marios; AKARI-NEP Team

    2017-03-01

    The AKARI North Ecliptic Pole Deep Field is a natural location to accomplish deep extragalactic surveys. It is supported by comprehensive ancillary data extending from radio to X-ray wavelengths, which have been used to classify radio sources as radio-loud and radio-quiet objects and to create a catalogue of Active Galactic Nuclei (AGN). This has been achieved by using a radio-optical classification and colour-colour diagrams rather than the more usual way based on spectroscopy Furthermore, we explore whether this technique can be extended by using a far-Infrared (FIR) colour-colour diagram which has been used to identify 268 high redshift candidates.

  11. North Atlantic Deep Water Production during the Last Glacial Maximum

    PubMed Central

    Howe, Jacob N. W.; Piotrowski, Alexander M.; Noble, Taryn L.; Mulitza, Stefan; Chiessi, Cristiano M.; Bayon, Germain

    2016-01-01

    Changes in deep ocean ventilation are commonly invoked as the primary cause of lower glacial atmospheric CO2. The water mass structure of the glacial deep Atlantic Ocean and the mechanism by which it may have sequestered carbon remain elusive. Here we present neodymium isotope measurements from cores throughout the Atlantic that reveal glacial–interglacial changes in water mass distributions. These results demonstrate the sustained production of North Atlantic Deep Water under glacial conditions, indicating that southern-sourced waters were not as spatially extensive during the Last Glacial Maximum as previously believed. We demonstrate that the depleted glacial δ13C values in the deep Atlantic Ocean cannot be explained solely by water mass source changes. A greater amount of respired carbon, therefore, must have been stored in the abyssal Atlantic during the Last Glacial Maximum. We infer that this was achieved by a sluggish deep overturning cell, comprised of well-mixed northern- and southern-sourced waters. PMID:27256826

  12. North Atlantic Deep Water Production during the Last Glacial Maximum.

    PubMed

    Howe, Jacob N W; Piotrowski, Alexander M; Noble, Taryn L; Mulitza, Stefan; Chiessi, Cristiano M; Bayon, Germain

    2016-06-03

    Changes in deep ocean ventilation are commonly invoked as the primary cause of lower glacial atmospheric CO2. The water mass structure of the glacial deep Atlantic Ocean and the mechanism by which it may have sequestered carbon remain elusive. Here we present neodymium isotope measurements from cores throughout the Atlantic that reveal glacial-interglacial changes in water mass distributions. These results demonstrate the sustained production of North Atlantic Deep Water under glacial conditions, indicating that southern-sourced waters were not as spatially extensive during the Last Glacial Maximum as previously believed. We demonstrate that the depleted glacial δ(13)C values in the deep Atlantic Ocean cannot be explained solely by water mass source changes. A greater amount of respired carbon, therefore, must have been stored in the abyssal Atlantic during the Last Glacial Maximum. We infer that this was achieved by a sluggish deep overturning cell, comprised of well-mixed northern- and southern-sourced waters.

  13. A Deep ALMA Image of the Hubble Ultra Deep Field

    NASA Astrophysics Data System (ADS)

    Dunlop, J. S.

    2016-12-01

    Although primarily designed as a high-resolution imaging spectrometer at submillimetre/millimetre wavelengths, the Atacama Large Millimeter/submillimeter Array (ALMA) has a vital role to play in producing the key deep, unconfused, submillimetre/millimetre continuum surveys required to bridge the current gap in our understanding of visible and dust-obscured star formation in the young Universe. The first such survey has now been completed, comprising a mosaic of 45 ALMA pointings at a wavelength of 1.3 mm, covering the Hubble Ultra Deep Field (HUDF). This deep, homogeneous ALMA survey, combined with the wealth of existing data in the HUDF, has already provided new clarity on the nature of dusty star-forming galaxies, and the relative evolution of dust-obscured and unobscured star formation over cosmic time.

  14. Seismicity in the Triassic Deep River Basin, North Carolina

    NASA Astrophysics Data System (ADS)

    Portner, D. E.; Wagner, L. S.; Fouch, M. J.; James, D. E.; Roman, D. C.; Golden, S.

    2013-12-01

    The Deep River Basin in central North Carolina is one of a series of Triassic rift basins along the east coast called the Newark Supergroup. Although the east coast lies on a passive plate margin, there is recorded seismicity within all of the coastal states, much of which is attributed to boundary faults of the Newark Supergroup basins. However, this seismicity is conspicuously absent around the Deep River Basin and most of North Carolina east of the Appalachian Mountains. In March 2012 we installed a 12 station broadband seismic network surrounding the Sanford Sub-Basin of the Deep River Basin to measure unrecorded seismicity. Through fifteen months of data collection, we have confidently detected and located more than 160 low magnitude seismic events within the array. However, the event locations cluster in four locations - three of which are near local rock quarries and one is near an unidentified anthropic feature. Further, these events consistently occur between the hours of 9am and 6pm local time, Monday through Friday indicating that they are anthropogenic. The Deep River Basin is one of the most likely places east of the Appalachian Mountains in North Carolina to be seismically active, yet we have measured no natural seismicity. Using receiver functions and known origins of the local seismic events we will be examining the crustal structure beneath the Deep River Basin to explain the conspicuous lack of local seismic activity.

  15. Deep suture zone in the North Barents Basin

    NASA Astrophysics Data System (ADS)

    Butsenko, Viktor; Kireev, Artem; Piskarev, Alexey; Savin, Vasily; Smirnov, Oleg

    2015-04-01

    Study of sedimentary basin evolution is a part of research for the forecast of oil and gas capacity of the North Barents shelf. Maps of potential fields anomalies are compiled on the basis of the latest geophysical databases, structural maps of the seismic horizons are analyzed, the location of sources of potential fields anomalies are calculated, 3D density and magnetic models of Earth's crust are constructed. Six seismic complexes are allocated in sedimentary cover structure: Devonian - Lower Carboniferous, Upper Carboniferous - Lower Permian, Mid Permian - Lower Triassic, Triassic - Lower Jurassic, Upper Jurassic - Lower Cretaceous, Lower Cretaceous - Quaternary. The research of lateral changes of allocated layers thickness gives an idea of sedimentation in the region on various time intervals. The structural and tectonic scheme of the region is made after analysis of new geologic-geophysical materials. Contact zones of heterogeneous blocks of the crystalline basement are marked, disjunctive dislocations in a sedimentary cover and the upper crust, and also zones of increase of sediments thickness in various seismic complexes are designated. The deep suture zone delimiting Mesozoic and Paleozoic sedimentary basins has the most important geological value among disjunctive zones of the region. This zone stretches along the Admiralty Arch in East part of the North Barents shelf and is marked by negative magnetic anomaly 30-50 km wide. In view of special tectonic value of the suture zone marked by this anomaly we have calculated the 3D magnetic crust model. The sedimentary layers of a model section is based on seismic data. As a result of modeling the studied anomaly of a magnetic field can be approximated by the block of basement rocks of the lowered magnetization (1.2 A/m). The surface of this block is located in a zone of anomaly at a depth of 12-14 km. The asymmetry of anomaly is accounted by an inclination to East of the borders of the block with low

  16. Deep Spitzer/IRAC Imaging of the Subaru Deep Field

    NASA Astrophysics Data System (ADS)

    Jiang, Linhua; Egami, Eiichi; Cohen, Seth; Fan, Xiaohui; Ly, Chun; Mechtley, Matthew; Windhorst, Rogier

    2013-10-01

    The last decade saw great progress in our understanding of the distant Universe as a number of objects at z > 6 were discovered. The Subaru Deep Field (SDF) project has played an important role on study of high-z galaxies. The SDF is unique: it covers a large area of 850 sq arcmin; it has extremely deep optical images in a series of broad and narrow bands; it has the largest sample of spectroscopically-confirmed galaxies known at z >= 6, including ~100 Lyman alpha emitters (LAEs) and ~50 Lyman break galaxies (LBGs). Here we propose to carry out deep IRAC imaging observations of the central 75% of the SDF. The proposed observations together with those from our previous Spitzer programs will reach a depth of ~10 hours, and enable the first complete census of physical properties and stellar populations of spectroscopically-confirmed galaxies at the end of cosmic reionization. IRAC data is the key to measure stellar masses and constrain stellar populations in high-z galaxies. From SED modeling with secure redshifts, we will characterize the physical properties of these galaxies, and trace their mass assembly and star formation history. In particular, it allows us, for the first time, to study stellar populations in a large sample of z >=6 LAEs. We will also address some critical questions, such as whether LAEs and LBGs represent physically different galaxy populations. All these will help us to understand the earliest galaxy formation and evolution, and better constrain the galaxy contribution to reionization. The IRAC data will also cover 10,000 emission-line selected galaxies at z < 1.5, 50,000 UV and mass selected LBGs at 1.5 < z < 3, and more than 5,000 LBGs at 3 < z < 6. It will have a legacy value for SDF-related programs.

  17. Early Oligocene initiation of North Atlantic Deep Water formation.

    PubMed

    Davies, R; Cartwright, J; Pike, J; Line, C

    2001-04-19

    Dating the onset of deep-water flow between the Arctic and North Atlantic oceans is critical for modelling climate change in the Northern Hemisphere and for explaining changes in global ocean circulation throughout the Cenozoic era (from about 65 million years ago to the present). In the early Cenozoic era, exchange between these two ocean basins was inhibited by the Greenland-Scotland ridge, but a gateway through the Faeroe-Shetland basin has been hypothesized. Previous estimates of the date marking the onset of deep-water circulation through this basin-on the basis of circumstantial evidence from neighbouring basins-have been contradictory, ranging from about 35 to 15 million years ago. Here we describe the newly discovered Southeast Faeroes drift, which extends for 120 km parallel to the basin axis. The onset of deposition in this drift has been dated to the early Oligocene epoch ( approximately 35 million years ago) from a petroleum exploration borehole. We show that the drift was deposited under a southerly flow regime, and conclude that the initiation of deep-water circulation from the Norwegian Sea into the North Atlantic Ocean took place much earlier than is currently assumed in most numerical models of ancient ocean circulation.

  18. Benchmark field study of deep neutron penetration

    SciTech Connect

    Morgan, J.F.; Sale, K. ); Gold, R.; Roberts, J.H.; Preston, C.C. )

    1991-06-10

    A unique benchmark neutron field has been established at the Lawrence Livermore National Laboratory (LLNL) to study deep penetration neutron transport. At LLNL, a tandem accelerator is used to generate a monoenergetic neutron source that permits investigation of deep neutron penetration under conditions that are virtually ideal to model, namely the transport of mono-energetic neutrons through a single material in a simple geometry. General features of the Lawrence Tandem (LATAN) benchmark field are described with emphasis on neutron source characteristics and room return background. The single material chosen for the first benchmark, LATAN-1, is a steel representative of Light Water Reactor (LWR) Pressure Vessels (PV). Also included is a brief description of the Little Boy replica, a critical reactor assembly designed to mimic the radiation doses from the atomic bomb dropped on Hiroshima, and its us in neutron spectrometry. 18 refs.

  19. Deep Chandra image in the Bootes Field

    NASA Astrophysics Data System (ADS)

    Wang, J. X.; Malhotra, S.; Rhoads, J. E.; Brown, M. J. I.; Dey, A.; Jannuzi, B. T.; Dawson, S.; Spinrad, H.; Heckman, T. M.; Norman, C. A.; Stern, D.; Tiede, G. P.; Tozzi, P.

    2004-05-01

    A 172 ks long Chandra exposure was carried out in the LALA-Bootes field and a similar one for the LALA cetus field. These exposure were deep enough to detect LALA sources, if they were type-II quasars. Lyman-alpha emitters found with LALA show high equivalent widths and AGN phenomenon is one explanation. A total of 101 Ly-alpha emitters are covered by the two Chandra images. No Ly-alpha emitters are detected individually or in the co-added X-ray images. Our analysis indicates that fewer than 4.8 Ly-alpha emitters could be possible AGNs based on the upper limit of their average X-ray to Ly-alpha ratio. The two X-ray images are among the deepest taken by Chandra, with a total of 348 X-ray sources detected, similar to the number of X-ray sources in Chandra Deep Field South. We also see field-to-field variations of the hard X-ray source counts in different Chandra fields, due to large scale structure.

  20. Phosphorus cycling in the deep subseafloor biosphere at North Pond

    NASA Astrophysics Data System (ADS)

    Defforey, D.; Paytan, A.

    2013-12-01

    Phosphorus is a macronutrient involved both in functional and structural components of all living cells. This makes it an essential nutrient for life, including microbial life in the deep subseafloor habitat. Phosphorus availability in this environment is limited since it is thought to be mainly present in refractory mineral phases. However, recent estimates suggest that the deep biosphere may contain up to 1% of Earth's total biomass, which implies that microorganisms may possess mechanisms to harvest recalcitrant phosphorus compounds in this environment. This study sheds light on those mechanisms by investigating phosphorus cycling in deep open-ocean sediments using stable oxygen isotope ratios in phosphate. Furthermore, this study provides insight into changes in phosphorus bioavailability and mobility under a range of natural environmental conditions within the deep biosphere. Sediment samples were collected from four boreholes drilled during the IODP Expedition 336 to North Pond, an isolated sediment pond on the western flank of the Mid-Atlantic Ridge. Sedimentary phosphorus compounds are characterized using sequential extractions (SEDEX), which separate them into five distinct pools. Phosphate from the various extracts are then concentrated, purified through a series of steps, then converted to silver phosphate, which is pyrolyzed and analyzed by continuous-flow isotope ratio mass spectrometry (CF-IRMS). The isotopic signatures and/or fractionations associated with many of the potential reactions and transformations operating in the P cycle have been determined, and provide the basis for interpreting isotopic data that are obtained from the phosphate extracts.

  1. EXTERIOR OVERVIEW, LOOKING NORTH, OF THIS 400' DEEP LIMESTONE QUARRY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    EXTERIOR OVERVIEW, LOOKING NORTH, OF THIS 400' DEEP LIMESTONE QUARRY PIT ("THE OLD PIT") WITH LEDGE PREPARED FOR LIMESTONE EXTRACTION. AN ELEVEN-HOLE SHOT WILL DISLODGE APPROXIMATELY 25,000 TONS OF LIMESTONE WHICH, AFTER LOADING AND CRUSHING, WILL BE USED FOR ROAD CONSTRUCTION. THE CALERA QUARRY IS ONE OF FOUR ACTIVE VULCAN MATERIALS COMPANY QUARRIES IN THE DISTRICT. VULCAN MATERIALS, A FORTUNE 500 FIRM, ESTABLISHED IN BIRMINGHAM IN 1906 AS BIRMINGHAM SLAG COMPANY, VULCAN MATERIALS IS THE NATION'S FOREMOST PRODUCER OF CONSTRUCTION AGGREGATE AND A LEADING CHEMICALS MANUFACTURER - Vulcan Material Company, Calera Quarry, 1614 Highway 84, Calera, Shelby County, AL

  2. EXTERIOR OVERVIEW, LOOKING NORTH, OF THIS 400' DEEP LIMESTONE QUARRY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    EXTERIOR OVERVIEW, LOOKING NORTH, OF THIS 400' DEEP LIMESTONE QUARRY PIT ('THE OLD PIT') WITH LEDGE PREPARED FOR LIMESTONE EXTRACTION. AN ELEVEN-HOLE SHOT WILL DISLODGE APPROXIMATELY 25,000 TONS OF LIMESTONE WHICH, AFTER LOADING AND CRUSHING, WILL BE USED FOR ROAD CONSTRUCTION. THE CALERA QUARRY IS ONE OF FOUR ACTIVE VULCAN MATERIALS COMPANY QUARRIES IN THE DISTRICT. VULCAN MATERIALS, A FORTUNE 500 FIRM, ESTABLISHED IN BIRMINGHAM IN 1906 AS BIRMINGHAM SLAG COMPANY, VULCAN MATERIALS IS THE NATION'S FOREMOST PRODUCER OF CONSTRUCTION AGGREGATE AND A LEADING CHEMICALS MANUFACTURER. - Vulcan Material Company, Calera Quarry, 1614 Highway 84, Calera, Shelby County, AL

  3. The Local Group: the ultimate deep field

    NASA Astrophysics Data System (ADS)

    Boylan-Kolchin, Michael; Weisz, Daniel R.; Bullock, James S.; Cooper, Michael C.

    2016-10-01

    Near-field cosmology - using detailed observations of the Local Group and its environs to study wide-ranging questions in galaxy formation and dark matter physics - has become a mature and rich field over the past decade. There are lingering concerns, however, that the relatively small size of the present-day Local Group (˜2 Mpc diameter) imposes insurmountable sample-variance uncertainties, limiting its broader utility. We consider the region spanned by the Local Group's progenitors at earlier times and show that it reaches 3 arcmin ≈ 7 comoving Mpc in linear size (a volume of ≈350 Mpc3) at z = 7. This size at early cosmic epochs is large enough to be representative in terms of the matter density and counts of dark matter haloes with Mvir(z = 7) ≲ 2 × 109 M⊙. The Local Group's stellar fossil record traces the cosmic evolution of galaxies with 103 ≲ M⋆(z = 0)/M⊙ ≲ 109 (reaching M1500 > -9 at z ˜ 7) over a region that is comparable to or larger than the Hubble Ultra-Deep Field (HUDF) for the entire history of the Universe. In the JWST era, resolved stellar populations will probe regions larger than the HUDF and any deep JWST fields, further enhancing the value of near-field cosmology.

  4. Shaping field for deep tissue microscopy

    NASA Astrophysics Data System (ADS)

    Colon, J.; Lim, H.

    2015-05-01

    Information capacity of a lossless image-forming system is a conserved property determined by two imaging parameters - the resolution and the field of view (FOV). Adaptive optics improves the former by manipulating the phase, or wavefront, in the pupil plane. Here we describe a homologous approach, namely adaptive field microscopy, which aims to enhance the FOV by controlling the phase, or defocus, in the focal plane. In deep tissue imaging, the useful FOV can be severely limited if the region of interest is buried in a thick sample and not perpendicular to the optic axis. One must acquire many z-scans and reconstruct by post-processing, which exposes tissue to excessive radiation and is also time consuming. We demonstrate the effective FOV can be substantially enhanced by dynamic control of the image plane. Specifically, the tilt of the image plane is continuously adjusted in situ to match the oblique orientation of the sample plane within tissue. The utility of adaptive field microscopy is tested for imaging tissue with non-planar morphology. Ocular tissue of small animals was imaged by two-photon excited fluorescence. Our results show that adaptive field microscopy can utilize the full FOV. The freedom to adjust the image plane to account for the geometrical variations of sample could be extremely useful for 3D biological imaging. Furthermore, it could facilitate rapid surveillance of cellular features within deep tissue while avoiding photo damages, making it suitable for in vivo imaging.

  5. A deep ALMA image of the Hubble Ultra Deep Field

    NASA Astrophysics Data System (ADS)

    Dunlop, J. S.; McLure, R. J.; Biggs, A. D.; Geach, J. E.; Michałowski, M. J.; Ivison, R. J.; Rujopakarn, W.; van Kampen, E.; Kirkpatrick, A.; Pope, A.; Scott, D.; Swinbank, A. M.; Targett, T. A.; Aretxaga, I.; Austermann, J. E.; Best, P. N.; Bruce, V. A.; Chapin, E. L.; Charlot, S.; Cirasuolo, M.; Coppin, K.; Ellis, R. S.; Finkelstein, S. L.; Hayward, C. C.; Hughes, D. H.; Ibar, E.; Jagannathan, P.; Khochfar, S.; Koprowski, M. P.; Narayanan, D.; Nyland, K.; Papovich, C.; Peacock, J. A.; Rieke, G. H.; Robertson, B.; Vernstrom, T.; Werf, P. P. van der; Wilson, G. W.; Yun, M.

    2017-04-01

    We present the results of the first, deep Atacama Large Millimeter Array (ALMA) imaging covering the full ≃4.5 arcmin2 of the Hubble Ultra Deep Field (HUDF) imaged with Wide Field Camera 3/IR on HST. Using a 45-pointing mosaic, we have obtained a homogeneous 1.3-mm image reaching σ1.3 ≃ 35 μJy, at a resolution of ≃0.7 arcsec. From an initial list of ≃50 > 3.5σ peaks, a rigorous analysis confirms 16 sources with S1.3 > 120 μJy. All of these have secure galaxy counterparts with robust redshifts ( = 2.15). Due to the unparalleled supporting data, the physical properties of the ALMA sources are well constrained, including their stellar masses (M*) and UV+FIR star formation rates (SFR). Our results show that stellar mass is the best predictor of SFR in the high-redshift Universe; indeed at z ≥ 2 our ALMA sample contains seven of the nine galaxies in the HUDF with M* ≥ 2 × 1010 M⊙, and we detect only one galaxy at z > 3.5, reflecting the rapid drop-off of high-mass galaxies with increasing redshift. The detections, coupled with stacking, allow us to probe the redshift/mass distribution of the 1.3-mm background down to S1.3 ≃ 10 μJy. We find strong evidence for a steep star-forming 'main sequence' at z ≃ 2, with SFR ∝M* and a mean specific SFR ≃ 2.2 Gyr-1. Moreover, we find that ≃85 per cent of total star formation at z ≃ 2 is enshrouded in dust, with ≃65 per cent of all star formation at this epoch occurring in high-mass galaxies (M* > 2 × 1010 M⊙), for which the average obscured:unobscured SF ratio is ≃200. Finally, we revisit the cosmic evolution of SFR density; we find this peaks at z ≃ 2.5, and that the star-forming Universe transits from primarily unobscured to primarily obscured at z ≃ 4.

  6. North Atlantic Deep Water and the World Ocean

    NASA Technical Reports Server (NTRS)

    Gordon, A. L.

    1984-01-01

    North Atlantic Deep Water (NADW) by being warmer and more saline than the average abyssal water parcel introduces heat and salt into the abyssal ocean. The source of these properties is upper layer or thermocline water considered to occupy the ocean less dense than sigma-theta of 27.6. That NADW convects even though it's warmer than the abyssal ocean is obviously due to the high salinity. In this way, NADW formation may be viewed as saline convection. The counter force removing heat and salinity (or introducing fresh water) is usually considered to to take place in the Southern Ocean where upwelling deep water is converted to cold fresher Antarctic water masses. The Southern ocean convective process is driven by low temperatures and hence may be considered as thermal convection. A significant fresh water source may also occur in the North Pacific where the northward flowing of abyssal water from the Southern circumpolar belt is saltier and denser than the southward flowing, return abyssal water. The source of the low salinity input may be vertical mixing of the low salinity surface water or the low salinity intermediate water.

  7. THE DEEP SWIRE FIELD. III. WIYN SPECTROSCOPY

    SciTech Connect

    Owen, Frazer N.; Morrison, G. E.

    2009-06-15

    We present the results of spectroscopy using HYDRA on the WIYN 3.5 m telescope of objects in the deep SWIRE radio field. The goal of the project was to determine spectroscopic redshifts for as many of the brighter objects in the field as possible, especially those detected in the radio and at 24 {mu}m. These redshifts are primarily being used in studies of galaxy evolution and the connection of that evolution to active galactic nuclei and star formation. Redshifts measured for 365 individual objects are reported. The redshifts range from 0.03 to 2.5, mostly with z < 0.9. The sources were selected to be within the WIYN HYDRA field of approximately 30' in radius from the center of the SWIRE deep field, 10{sup h}46{sup m}00{sup s}, 59{sup 0}01'00'' (J2000). Optical sources for spectroscopic observation were selected from an r-band image of the field. A priority list of spectroscopic targets was established in the following order: 20 cm detections, 24 m detections, galaxies with r < 20 and the balance made up of fainter galaxies in the field. We provide a table listing the galaxy positions, measured redshift and error, and note any emission lines that were visible in the spectrum. In practice, almost all the galaxies with r < 19 were observed including all of the radio sources and most of the 24 {mu}m sources with r < 20 and a sample of radio sources which had fainter optical counterparts on the r-band image.

  8. THE SPITZER DEEP, WIDE-FIELD SURVEY

    SciTech Connect

    Ashby, M. L. N.; Brodwin, M.; Stern, D.; Griffith, R.; Eisenhardt, P.; Gorjian, V.; Kozlowski, S.; Kochanek, C. S.; Bock, J. J.; Borys, C.; Brand, K.; Grogin, N. A.; Brown, M. J. I.; Cool, R.; Cooray, A.; Croft, S.; Dey, A.; Eisenstein, D.; Gonzalez, A. H.; Ivison, R. J.

    2009-08-10

    The Spitzer Deep, Wide-Field Survey (SDWFS) is a four-epoch infrared survey of 10 deg.{sup 2} in the Booetes field of the NOAO Deep Wide-Field Survey using the IRAC instrument on the Spitzer Space Telescope. SDWFS, a Spitzer Cycle 4 Legacy project, occupies a unique position in the area-depth survey space defined by other Spitzer surveys. The four epochs that make up SDWFS permit-for the first time-the selection of infrared-variable and high proper motion objects over a wide field on timescales of years. Because of its large survey volume, SDWFS is sensitive to galaxies out to z {approx} 3 with relatively little impact from cosmic variance for all but the richest systems. The SDWFS data sets will thus be especially useful for characterizing galaxy evolution beyond z {approx} 1.5. This paper explains the SDWFS observing strategy and data processing, presents the SDWFS mosaics and source catalogs, and discusses some early scientific findings. The publicly released, full-depth catalogs contain 6.78, 5.23, 1.20, and 0.96 x 10{sup 5} distinct sources detected to the average 5{sigma}, 4''-diameter, aperture-corrected limits of 19.77, 18.83, 16.50, and 15.82 Vega mag at 3.6, 4.5, 5.8, and 8.0 {mu}m, respectively. The SDWFS number counts and color-color distribution are consistent with other, earlier Spitzer surveys. At the 6 minute integration time of the SDWFS IRAC imaging, >50% of isolated Faint Images of the Radio Sky at Twenty cm radio sources and >80% of on-axis XBooetes sources are detected out to 8.0 {mu}m. Finally, we present the four highest proper motion IRAC-selected sources identified from the multi-epoch imaging, two of which are likely field brown dwarfs of mid-T spectral class.

  9. The Hubble Deep Field and its Legacy

    NASA Astrophysics Data System (ADS)

    Williams, Robert E.

    2014-01-01

    Although deep images of distant galaxies were hardly a novel concept at the time, various aspects of the Hubble Deep Field resulted in its influence on subsequent studies of high redshift objects and on the culture in which large projects are carried out on unique facilities. The sensitivity, spatial resolution, and low background of HST were essential in making the HDF a success in its imaging of galaxy evolution from after the epoch of reionization to the present time. Subsequent deep fields and follow up studies on HST and other facilities have produced a number of results important to our understanding of galaxy evolution. Among these are: establishing the credibility of photometric redshifts as a foundation for extragalactic research; determination of the rate of star formation over cosmological time; producing early, reliable maps of dark matter; providing essential SNe data that revealed dark energy; resolving the X-ray background; enabling the evolution of galaxy luminosity functions to be determined; and yielding detailed gravitational lensing maps that identify the locations of magnified images of z>10 objects around clusters of galaxies. Undertaken using HST Director’s Discretionary time the HDF set a precedent by providing unique non-proprietary observational data to the community in addition to a fully reduced dataset virtually immediately after the observations were taken. Collaborative follow up studies on other facilities, e.g., Keck spectroscopy, Chandra X-ray imaging, etc., that were important to the interpretation of the HDF images were arranged even before the HDF observations were taken in order to facilitate analysis of the joint data. These collaborative programs were as essential to the success of the HDF as the HST images themselves.

  10. Deep Borehole Field Test Conceptual Design Report

    SciTech Connect

    Hardin, Ernest L.

    2016-09-30

    This report documents conceptual design development for the Deep Borehole Field Test (DBFT), including test packages (simulated waste packages, not containing waste) and a system for demonstrating emplacement and retrieval of those packages in the planned Field Test Borehole (FTB). For the DBFT to have demonstration value, it must be based on conceptualization of a deep borehole disposal (DBD) system. This document therefore identifies key options for a DBD system, describes an updated reference DBD concept, and derives a recommended concept for the DBFT demonstration. The objective of the DBFT is to confirm the safety and feasibility of the DBD concept for long-term isolation of radioactive waste. The conceptual design described in this report will demonstrate equipment and operations for safe waste handling and downhole emplacement of test packages, while contributing to an evaluation of the overall safety and practicality of the DBD concept. The DBFT also includes drilling and downhole characterization investigations that are described elsewhere (see Section 1). Importantly, no radioactive waste will be used in the DBFT, nor will the DBFT site be used for disposal of any type of waste. The foremost performance objective for conduct of the DBFT is to demonstrate safe operations in all aspects of the test.

  11. The Ultra Deep Field - WFPC2 Parallels

    NASA Astrophysics Data System (ADS)

    Beckwith, Steven

    2003-07-01

    The ACS Ultra Deep Field {UDF} is a survey carried out by using Director's Discretionary time. The main science drivers are galaxy evolution and cosmology. The primary instrument is the Advanced Camera for Surveys but WFPC2, NICMOS, and STIS will also be used in pure parallel mode. The data will be made public. The UDF consists of a single ultra-deep field {410 orbits in total} within the CDF-S GOODS area. We request a modification of the default pure parallel programs. Rather than duplicate the redder bands which will be done much better with ACS, we propose to observe in the near-ultraviolet F300W filter. These data will enable study of the rest-frame ultraviolet morphology of galaxies at 0

  12. Connectivity between surface and deep waters determines prokaryotic diversity in the North Atlantic Deep Water.

    PubMed

    Frank, Alexander H; Garcia, Juan A L; Herndl, Gerhard J; Reinthaler, Thomas

    2016-06-01

    To decipher the influence of depth stratification and surface provincialism on the dark ocean prokaryotic community composition, we sampled the major deep-water masses in the eastern North Atlantic covering three biogeographic provinces. Their diversity was evaluated using ordination and canonical analysis of 454 pyrotag sequences. Variance partitioning suggested that 16% of the variation in the bacterial community composition was based on depth stratification while 9% of the variation was due to geographic location. General linear mixed effect models showed that the community of the subsurface waters was connected to the dark ocean prokaryotic communities in different biogeographic provinces. Cluster analysis indicated that some prokaryotic taxa are specific to distinct regions in bathypelagic water masses. Taken together, our data suggest that the dark ocean prokaryotic community composition of the eastern North Atlantic is primed by the formation and the horizontal transport of water masses. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  13. North Pacific Acoustic Laboratory and Deep Water Acoustics

    DTIC Science & Technology

    2016-10-27

    ocean noise for seven sites in the North Pacific Ocean . (authors - Andrew, Howe, and Mercer). This paper was submitted to JUA in February of 2016...limitations to the performance of long-range sonar are due to ocean sound speed perturbations and the characteristics of the ambient acoustic noise...field. Scattering and diffraction resulting from internal waves and other ocean processes limit the temporal and spatial coherence of the received

  14. Oceanographic influences on Deep Scattering Layers across the North Atlantic

    NASA Astrophysics Data System (ADS)

    Fennell, Sheena; Rose, George

    2015-11-01

    The distribution and density of Deep Scattering Layers (DSLs) were quantified along North Atlantic transits from Ireland to the Grand Banks of Newfoundland in the springs of 2012, 2013 and 2014 employing a calibrated Simrad EK60 echo sounder at 38 kHz. Concurrently, Sippican T5 XBTs (eXpendable Bathy Thermographs) were used to profile temperatures to 1800 m. In each year the scattering layers spanned the deep basin at depths ranging from near surface to approximately 900 m, but annual mean densities differed significantly. Higher DSL densities were recorded during years that exhibited higher sea temperatures at the depths of major DSL concentration (400-600 m), higher sea level anomalies and stronger eastward geostrophic currents. The highest concentration of the DSLs in each year was found in the area east of the Grand Banks that corresponded with areas of anticyclonic eddies. In this region DSL densities in 2014 were among the highest recorded worldwide (>7000 m2 nautical mile-2). Midwater fishing indicated DSLs were dominated by Myctophids and Sternoptychids. Anticyclonic eddy formation is discussed as a possible means of transport and aggregation of the DSLs in that region, where oceanographic influences may play a dominant role in the distribution and density of the DSLs and upper trophic level fishes.

  15. Slip Line Field Applied To Deep Drawing

    NASA Astrophysics Data System (ADS)

    Miguel, V.; Benet, J.; Coello, J.; Calatayud, A.; Martínez, A.

    2007-05-01

    Slip Line Field is a numerical method applied for modelling plane-strain processes. This method has been successfully checked properly for sheet drawing. Flange deformation in deep drawing is considered without change in thickness. A drawing mechanical test has been developed in order to reproduce the flange stresses state in sheet strips with the rolling direction selected. The fundamentals of this test, and some experimental results obtained from it, have been presented previously in different Congresses. In this work, an algorithm based on SLF has been implemented and theoretical results evaluated for different conditions. The algorithm have been applied to a mild DDQ steel and to a DDQ AISI 304 stainless steel. Theoretical and experimental results are compared. A good concordance in them has been found out under some conditions. One of the most important aspects is that it must not be considered tensile material properties but a modified behavior under multiaxial conditions.

  16. VizieR Online Data Catalog: z~4-7 Lyman break galaxies in Hubble deep fields (Harikane+, 2016)

    NASA Astrophysics Data System (ADS)

    Harikane, Y.; Ouchi, M.; Ono, Y.; More, S.; Saito, S.; Lin, Y.-T.; Coupon, J.; Shimasaku, K.; Shibuya, T.; Price, P. A.; Lin, L.; Hsieh, B.-C.; Ishigaki, M.; Komiyama, Y.; Silverman, J.; Takata, T.; Tamazawa, H.; Toshikawa, J.

    2016-07-01

    We use 10 deep optical-near-IR imaging data sets of the Hubble Ultra Deep Field (HUDF), Great Observatories Origins Deep Survey (GOODS)-North-Deep, GOODS-North-Wide, GOODS-South-Deep, GOODS-South-Wide, Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS)-All-Wavelength Extended Groth Strip International Survey (AEGIS), CANDELS-Cosmological Evolution Survey (COSMOS), CANDELS-Ultra Deep Survey (UDS), Hubble Frontier Field (HFF)-Abell2744P, and HFF-MACS0416P that are taken with ACS and WFC3 on the HST. The total area of the Hubble data is ~600arcmin2. The typical FWHMs of the PSFs of ACS and WFC3 images are 0.1" and 0.2", respectively. (1 data file).

  17. MOVING OBJECTS IN THE HUBBLE ULTRA DEEP FIELD

    SciTech Connect

    Kilic, Mukremin; Gianninas, Alexandros; Von Hippel, Ted E-mail: alexg@nhn.ou.edu

    2013-09-01

    We identify proper motion objects in the Hubble Ultra Deep Field (UDF) using the optical data from the original UDF program in 2004 and the near-infrared data from the 128 orbit UDF 2012 campaign. There are 12 sources brighter than I = 27 mag that display >3{sigma} significant proper motions. We do not find any proper motion objects fainter than this magnitude limit. Combining optical and near-infrared photometry, we model the spectral energy distribution of each point-source using stellar templates and state-of-the-art white dwarf models. For I {<=} 27 mag, we identify 23 stars with K0-M6 spectral types and two faint blue objects that are clearly old, thick disk white dwarfs. We measure a thick disk white dwarf space density of 0.1-1.7 Multiplication-Sign 10{sup -3} pc{sup -3} from these two objects. There are no halo white dwarfs in the UDF down to I = 27 mag. Combining the Hubble Deep Field North, South, and the UDF data, we do not see any evidence for dark matter in the form of faint halo white dwarfs, and the observed population of white dwarfs can be explained with the standard Galactic models.

  18. Alaska's North Slope: developing the smaller fields

    SciTech Connect

    Bradner, M.

    1984-08-13

    Oil development on Alaska's North Slope is entering a new phase. There is an increasing emphasis on reducing the high development cost of small, marginally-economic reservoirs near the large Prudhoe Bay oilfield. The exploration hunt for Arctic super-giants continues in the Beaufort Sea and in remote areas like the Arctic National Wildlife Refuge. But meanwhile, North Slope oil companies are paying more attention to smaller, undeveloped fields near Prudhoe. Kuparuk, west of Prudhoe, has been in production since 1981, for example, but next year Conoco will build facilities for the small Milne Point field, tying into infrastructure built for Kuparuk. Likewise, Lisburne and Endicott, two other fields now ready for development, will tie into the larger Prudhoe Bay pipeline system. 1 figure.

  19. Hubble Deep Field guide star photometry

    NASA Astrophysics Data System (ADS)

    Zwintz, K.; Kuschnig, R.; Weiss, W. W.; Gray, R. O.; Jenkner, H.

    1999-03-01

    Since the advent of asteroseismology as a promising innovative tool for investigating internal stellar structure, numerous attempts to detect solar type oscillations in distant stars have been conducted. The three Fine Guidance Sensors of the Hubble Space Telescope can contribute to asteroseismology, but only after the data have been corrected for systematic effects, the South Atlantic Anomaly and terrestrial stray light being the most important. We have applied these corrections and obtained essentially photon noise-limited photometry for two guide stars used during the Hubble Deep Field program. Ground-based spectral classification has revealed that the brighter of the two guide stars is a solar-type star with a spectral type of G2mG0iv. Fine Guidance Sensor photometry for this star gives a noise level in the amplitude spectrum of only 23 ppm, which makes it a good candidate for detecting stochastically driven oscillations. We compare our result with theoretical predictions. The second guide star was classified as K1v and therefore is not a candidate for solar type oscillations. Based on observations made with the NASA/ESA {\\it Hubble Space Telescope}, obtained from the data archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

  20. Deep-Sea coral evidence for rapid change in ventilation of the deep north atlantic 15,400 years Ago

    PubMed

    Adkins; Cheng; Boyle; Druffel; Edwards

    1998-05-01

    Coupled radiocarbon and thorium-230 dates from benthic coral species reveal that the ventilation rate of the North Atlantic upper deep water varied greatly during the last deglaciation. Radiocarbon ages in several corals of the same age, 15.41 +/- 0.17 thousand years, and nearly the same depth, 1800 meters, in the western North Atlantic Ocean increased by as much as 670 years during the 30- to 160-year life spans of the samples. Cadmium/calcium ratios in one coral imply that the nutrient content of these deep waters also increased. Our data show that the deep ocean changed on decadal-centennial time scales during rapid changes in the surface ocean and the atmosphere.

  1. Deep Vadose Zone Applied Field Research Initiative (DVZ AFRI) - Overview

    SciTech Connect

    2011-02-01

    The Deep Vadoze Zone Applied Field Research Initiative (DVZ AFRI) was established to protect water resources and to address the challenge of preventing contamination in the deep vadose zone from reaching groundwater. This factsheet provides an overview of the initiative and the approach to integrate basic science and needs-driven applied research activities with cleanup operations.

  2. Protein Secondary Structure Prediction Using Deep Convolutional Neural Fields

    NASA Astrophysics Data System (ADS)

    Wang, Sheng; Peng, Jian; Ma, Jianzhu; Xu, Jinbo

    2016-01-01

    Protein secondary structure (SS) prediction is important for studying protein structure and function. When only the sequence (profile) information is used as input feature, currently the best predictors can obtain ~80% Q3 accuracy, which has not been improved in the past decade. Here we present DeepCNF (Deep Convolutional Neural Fields) for protein SS prediction. DeepCNF is a Deep Learning extension of Conditional Neural Fields (CNF), which is an integration of Conditional Random Fields (CRF) and shallow neural networks. DeepCNF can model not only complex sequence-structure relationship by a deep hierarchical architecture, but also interdependency between adjacent SS labels, so it is much more powerful than CNF. Experimental results show that DeepCNF can obtain ~84% Q3 accuracy, ~85% SOV score, and ~72% Q8 accuracy, respectively, on the CASP and CAMEO test proteins, greatly outperforming currently popular predictors. As a general framework, DeepCNF can be used to predict other protein structure properties such as contact number, disorder regions, and solvent accessibility.

  3. Inter-relationship between shallow and deep aquifers under the influence of deep groundwater exploitation in the North China Plain

    NASA Astrophysics Data System (ADS)

    Han, Dongmei; Cao, Guoliang; Love, Andrew J.

    2017-04-01

    In the North China Plain (NCP), the interaction between shallow and deep groundwater flow systems enhanced by groundwater extraction has been investigated using multi-isotopic and chemical tracers for understanding the mechanism of salt water transport, which has long been one of the major regional environmental hydrogeological problems in NCP. Information about the problem will be determined using multiple lines of evidence, including field surveys of drilling and water sampling, as well as laboratory experiments and physical and numerical simulations. A conceptual model of groundwater flow system along WE cross-section from piedmont area to coastal region (Shijiazhuang-Hengshui-Cangzhou) has been developed and verified by geochemical modeling. A combined hydrogeochemical and isotopic investigation using ion relationships such as Cl/Br ratios, and environment isotopes (δ 18O, δ 2H, δ 34SSO4-δ 18OSO4, δ 15NNO_3-δ 18ONO_3, δ 13C and 87Sr/86Sr) was reviewed and carried for determining the sources of aquifer recharge, the origin of solutes and the mixing processes in groundwater flow system under the anthropogenic pumping and pollution. Results indicate that hydrochemistry of groundwater is characterized by mixing between end-members coming directly from Piedmont recharge areas, saline groundwater formed during geohistorical transgression in the shallow aquifers of central plain, and to groundwater circulating in a deeply buried Quaternary sediments. We also reviewed the groundwater age (tritium contents, 14C ages, 3H-3He ages, basin-scale flow modeling ages of groundwater) to recognize the local distributed recharge in this strongly exploited aquifer system. Finally, combined with the 1-D Cl transport modeling for the pore water of clay-rich aquitard, we reveal that salt transport in the aquitard is primarily controlled by vertical diffusion on million years' time scale, and the observed the salinized groundwater in deep aquifer may be caused by passing

  4. Quaternary North Atlantic Surface Paleoceanography in Regions of Potential Deep-water Formation

    NASA Technical Reports Server (NTRS)

    Ruddiman, W. F.

    1984-01-01

    At the time scale of the Quaternary climate cycles, the sites of formation of North Atlantic Deep Water are not known. The interglacial extreme is presumably exemplified by the modern regions; the Norwegian, Greenland and Labrador Seas. During the major glacial-age coolings in the North Atlantic, the sites may have shifted well to the south, perhaps as far as the limit of the polar front at 40 to 50 N. Still other sites may have been important during intermediate climatic conditions. Because of the close coupling of high-latitude surface waters to North Atlantic Deep Water in the modern ocean, the history of sea-surface temperature (SST) oscillations across the high-latitude North Atlantic is relevant to an understanding of deep-water formation on the longer time scales.

  5. The North Pacific Acoustic Laboratory deep-water acoustic propagation experiments in the Philippine Sea.

    PubMed

    Worcester, Peter F; Dzieciuch, Matthew A; Mercer, James A; Andrew, Rex K; Dushaw, Brian D; Baggeroer, Arthur B; Heaney, Kevin D; D'Spain, Gerald L; Colosi, John A; Stephen, Ralph A; Kemp, John N; Howe, Bruce M; Van Uffelen, Lora J; Wage, Kathleen E

    2013-10-01

    A series of experiments conducted in the Philippine Sea during 2009-2011 investigated deep-water acoustic propagation and ambient noise in this oceanographically and geologically complex region: (i) the 2009 North Pacific Acoustic Laboratory (NPAL) Pilot Study/Engineering Test, (ii) the 2010-2011 NPAL Philippine Sea Experiment, and (iii) the Ocean Bottom Seismometer Augmentation of the 2010-2011 NPAL Philippine Sea Experiment. The experimental goals included (a) understanding the impacts of fronts, eddies, and internal tides on acoustic propagation, (b) determining whether acoustic methods, together with other measurements and ocean modeling, can yield estimates of the time-evolving ocean state useful for making improved acoustic predictions, (c) improving our understanding of the physics of scattering by internal waves and spice, (d) characterizing the depth dependence and temporal variability of ambient noise, and (e) understanding the relationship between the acoustic field in the water column and the seismic field in the seafloor. In these experiments, moored and ship-suspended low-frequency acoustic sources transmitted to a newly developed distributed vertical line array receiver capable of spanning the water column in the deep ocean. The acoustic transmissions and ambient noise were also recorded by a towed hydrophone array, by acoustic Seagliders, and by ocean bottom seismometers.

  6. Impact of Deep Convection on UTLS Composition -New Observations from Recent Airborne Field Studies

    NASA Astrophysics Data System (ADS)

    Pan, L.

    2014-12-01

    Deep convection redistributes chemical trace gas species throughout the troposphere. Tropopause-penetrating deep convection injects water vapor and pollutants into the lower stratosphere. To obtain the necessary information for characterizing its role in chemistry-climate coupling, the impact of deep convection on UTLS ozone, water vapor, and short-lived organic species has been a key component of several recent airborne field campaigns. We present selected findings and observational highlights from two airborne field campaigns. They are the CONvective TRansport of Active Species in the Tropics (CONTRAST) experiment, conducted January-February 2014 over the western Pacific using the NCAR GV research aircraft, in collaboration with the UK FAAM BAe146 and the NASA Global Hawk, and the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) experiment, conducted August-September 2013 over the north America using the NASA DC-8 and ER-2 research aircraft.

  7. North Atlantic deep water formation and AMOC in CMIP5 models

    NASA Astrophysics Data System (ADS)

    Heuzé, Céline

    2017-07-01

    Deep water formation in climate models is indicative of their ability to simulate future ocean circulation, carbon and heat uptake, and sea level rise. Present-day temperature, salinity, sea ice concentration and ocean transport in the North Atlantic subpolar gyre and Nordic Seas from 23 CMIP5 (Climate Model Intercomparison Project, phase 5) models are compared with observations to assess the biases, causes and consequences of North Atlantic deep convection in models. The majority of models convect too deep, over too large an area, too often and too far south. Deep convection occurs at the sea ice edge and is most realistic in models with accurate sea ice extent, mostly those using the CICE model. Half of the models convect in response to local cooling or salinification of the surface waters; only a third have a dynamic relationship between freshwater coming from the Arctic and deep convection. The models with the most intense deep convection have the warmest deep waters, due to a redistribution of heat through the water column. For the majority of models, the variability of the Atlantic Meridional Overturning Circulation (AMOC) is explained by the volumes of deep water produced in the subpolar gyre and Nordic Seas up to 2 years before. In turn, models with the strongest AMOC have the largest heat export to the Arctic. Understanding the dynamical drivers of deep convection and AMOC in models is hence key to realistically forecasting Arctic oceanic warming and its consequences for the global ocean circulation, cryosphere and marine life.

  8. Recharge to the North Richland well field

    SciTech Connect

    Law, A.G.

    1989-07-01

    The investigation was based on a preliminary ground-water flow model of the 1100 Area. Because few local data were available for this effort, an existing regional ground-water flow model of the Hanford Site was applied, which is based on the Variable Thickness Transient (VTT) ground-water flow code (Kipp et al., 1976). A submodel of the Hanford Site model was developed based on the VTT code. An independent model consisting of a simple representation of the local conditions in the vicinity of the North Richland well field was also used in the investigation. This model, based on the MODFLOW code (McDonald and Harbaugh, 1984), was used in a series of transient simulations to examine dynamic aspects of the well field/recharge basin. Results from this simple model also provide an independent, qualitative check of results produced with the 1100 Area model based on the VTT code. This report summarizes the 1100 Area modeling investigation, including the approach used to generate results for the regional and 1100 Area VTT models, the approach used in the transient MODFLOW model, results from some initial steady-state and transient simulations with the submodel and the MODFLOW models, and resulting conclusions and recommendations. Because local data were lacking to develop and calibrate the models, the investigation described in this report can best be described as a ''sensitivity analysis'' of ground-water flow in the 1100 Area. 4 refs., 10 figs., 2 tabs.

  9. North Atlantic deep water formation and AMOC in CMIP5 models

    NASA Astrophysics Data System (ADS)

    Heuzé, Céline; Wåhlin, Anna

    2017-04-01

    North Atlantic deep water formation processes and properties in climate models are indicative of their ability to simulate future ocean circulation, ventilation, carbon and heat uptake, and sea level rise. Historical time series of temperature, salinity, sea ice concentration and ocean transport in the North Atlantic subpolar gyre and Nordic Seas from 23 CMIP5 (Climate Model Intercomparison Project, phase 5) models are compared with observations to reveal the causes and consequences of North Atlantic deep water formation in models. Deep convection occurs at the sea ice edge and is most realistic in models with accurate sea ice extent, mostly those using the CICE model. The trigger of deep convection varies among models; for one third it is intense surface cooling only, while the remaining two thirds also need upward mixing of subsurface warm salty water. The models with the most intense deep convection have the most accurate deep water properties, which are warmer and fresher than in the other models. They also have the strongest Atlantic Meridional Overturning Circulation (AMOC). For over half of the models, 40% of the variability of the AMOC is explained by the volumes of deep water produced in the subpolar gyre and Nordic Seas, with 3 and 4 years lag respectively. Understanding the dynamical drivers of the AMOC in models is key to realistically forecast a possible slow down and its consequences on the global circulation and marine life.

  10. The SPT-Spitzer Deep Field

    NASA Astrophysics Data System (ADS)

    Stanford, Spencer; Brodwin, Mark; Mohr, Joe; Eisenhardt, Peter; Bartlett, James; Papovich, Casey; Holder, Gil; Mei, Simona; Tran, Vy; Stern, Daniel; Kelson, Dan; Rosati, Piero; High, Will; Dey, Arjun; Crawford, Tom; Carlstrom, John; Muzzin, Adam; Moustakas, Leonidas; Ashby, Matt; Mulchaey, John; Vieira, Joaquin; Shaw, Laurie; Desai, Shantanu; Marrone, Dan; Dressler, Alan; Pierre, Marguerite; Pacaud, Florian; Benson, Brad; Gonzalez, Anthony; Galametz, Audrey; Holden, Brad; Jannuzi, Buell; Armstrong, Bob; Knox, Lloyd

    2011-05-01

    We propose to conduct an IRAC survey of a contiguous 100 deg2 area within the deepest South Pole Telescope survey field. The resulting IRAC dataset will be used in combination with Sunyaev-Zel'dovich information from the SPT to study the complete baryon budget in dense environments at all redshifts, to measure halo masses at 1 < z< 2 via lensing of the CMB, and to cross calibrate SZ, X-ray, and optical-IR methods of constructing galaxy cluster catalogs and estimating galaxy cluster masses. The target field will contain a publicly-available suite of X-ray, optical, NIR, FIR, and millimeter data, making it an ideal location to conduct a wide-field IRAC extragalactic legacy survey.

  11. Deep Borehole Field Test Research Activities at LBNL

    SciTech Connect

    Dobson, Patrick; Tsang, Chin-Fu; Kneafsey, Timothy; Borglin, Sharon; Piceno, Yvette; Andersen, Gary; Nakagawa, Seiji; Nihei, Kurt; Rutqvist, Jonny; Doughty, Christine; Reagan, Matthew

    2016-08-19

    The goal of the U.S. Department of Energy Used Fuel Disposition’s (UFD) Deep Borehole Field Test is to drill two 5 km large-diameter boreholes: a characterization borehole with a bottom-hole diameter of 8.5 inches and a field test borehole with a bottom-hole diameter of 17 inches. These boreholes will be used to demonstrate the ability to drill such holes in crystalline rocks, effectively characterize the bedrock repository system using geophysical, geochemical, and hydrological techniques, and emplace and retrieve test waste packages. These studies will be used to test the deep borehole disposal concept, which requires a hydrologically isolated environment characterized by low permeability, stable fluid density, reducing fluid chemistry conditions, and an effective borehole seal. During FY16, Lawrence Berkeley National Laboratory scientists conducted a number of research studies to support the UFD Deep Borehole Field Test effort. This work included providing supporting data for the Los Alamos National Laboratory geologic framework model for the proposed deep borehole site, conducting an analog study using an extensive suite of geoscience data and samples from a deep (2.5 km) research borehole in Sweden, conducting laboratory experiments and coupled process modeling related to borehole seals, and developing a suite of potential techniques that could be applied to the characterization and monitoring of the deep borehole environment. The results of these studies are presented in this report.

  12. North American deep underground laboratories: Soudan Underground Laboratory, SNOLab, and the Sanford Underground Research Facility

    NASA Astrophysics Data System (ADS)

    Lesko, Kevin T.

    2015-08-01

    Over the past several decades, fundamental physics experiments have required access to deep underground laboratories to satisfy the increasingly strict requirements for ultra-low background environments and shielding from cosmic rays. In this presentation, I summarize the existing and anticipated physics programs and laboratory facilities of North America's deep facilities: The Soudan Underground Laboratory in Minnesota, SNOLab in Ontario, Canada, and the Sanford Underground Research Facility in Lead, South Dakota.

  13. Using Species-Area Relationships to Inform Baseline Conservation Targets for the Deep North East Atlantic

    PubMed Central

    Foster, Nicola L.; Foggo, Andrew; Howell, Kerry L.

    2013-01-01

    Demands on the resources of the deep-sea have increased in recent years. Consequently, the need to create and implement a comprehensive network of Marine Protected Areas (MPAs) to help manage and protect these resources has become a global political priority. Efforts are currently underway to implement MPA networks in the deep North East Atlantic. To ensure these networks are effective, it is essential that baseline information be available to inform the conservation planning process. Using empirical data, we calculated conservation targets for sessile benthic invertebrates in the deep North East Atlantic for consideration during the planning process. We assessed Species-Area Relationships across two depth bands (200–1100 m and 1100–1800 m) and nine substrata. Conservation targets were predicted for each substratum within each depth band using z-values obtained from fitting a power model to the Species-Area Relationships of observed and estimated species richness (Chao1). Results suggest an MPA network incorporating 10% of the North East Atlantic’s deep-sea area would protect approximately 58% and 49% of sessile benthic species for the depth bands 200–1100 m and 1100–1800 m, respectively. Species richness was shown to vary with substratum type indicating that, along with depth, substratum information needs to be incorporated into the conservation planning process to ensure the most effective MPA network is implemented in the deep North East Atlantic. PMID:23527053

  14. Rapid subduction in the deep North Western Mediterranean

    NASA Astrophysics Data System (ADS)

    Aguilar, J. A.; Albert, A.; Anghinolfi, M.; Anton, G.; Anvar, S.; Ardid, M.; Assis Jesus, A. C.; Astraatmadja, T.; Aubert, J.-J.; Auer, R.; Baret, B.; Basa, S.; Bazzotti, M.; Bertin, V.; Biagi, S.; Bigongiari, C.; Bou-Cabo, M.; Bouwhuis, M. C.; Brown, A.; Brunner, J.; Busto, J.; Camarena, F.; Capone, A.; Carminati, G.; Carr, J.; Castel, D.; Castorina, E.; Cavasinni, V.; Cecchini, S.; Charvis, Ph.; Chiarusi, T.; Circella, M.; Coniglione, R.; Costantini, H.; Cottini, N.; Coyle, P.; Curtil, C.; de Bonis, G.; Decowski, M. P.; Dekeyser, I.; Deschamps, A.; Distefano, C.; Donzaud, C.; Dornic, D.; Drouhin, D.; Eberl, T.; Emanuele, U.; Ernenwein, J.-P.; Escoffier, S.; Fehr, F.; Flaminio, V.; Fratini, K.; Fritsch, U.; Fuda, J.-L.; Giacomelli, G.; Gómez-González, J. P.; Graf, K.; Guillard, G.; Halladjian, G.; Hallewell, G.; van Haren, H.; Heijboer, A. J.; Hello, Y.; Hernández-Rey, J. J.; Hößl, J.; de Jong, M.; Kalantar-Nayestanaki, N.; Kalekin, O.; Kappes, A.; Katz, U.; Kooijman, P.; Kopper, C.; Kouchner, A.; Kretschmer, W.; Lahmann, R.; Lamare, P.; Lambard, G.; Larosa, G.; Laschinsky, H.; Lefèvre, D.; Lelaizant, G.; Lim, G.; Lo Presti, D.; Loehner, H.; Loucatos, S.; Lucarelli, F.; Lyons, K.; Mangano, S.; Marcelin, M.; Margiotta, A.; Martinez-Mora, J. A.; Maurin, G.; Mazure, A.; Melissas, M.; Montaruli, T.; Morganti, M.; Moscoso, L.; Motz, H.; Naumann, C.; Neff, M.; Ostasch, R.; Palioselitis, G.; Păvălaş, G. E.; Payre, P.; Petrovic, J.; Piattelli, P.; Picot-Clemente, N.; Picq, C.; Pillet, R.; Popa, V.; Pradier, T.; Presani, E.; Racca, C.; Radu, A.; Reed, C.; Riccobene, G.; Richardt, C.; Rujoiu, M.; Russo, G. V.; Salesa, F.; Schoeck, F.; Schuller, J.-P.; Shanidze, R.; Simeone, F.; Spurio, M.; Steijger, J. J. M.; Stolarczyk, Th.; Tamburini, C.; Tasca, L.; Taupier-Letage, I.; Toscano, S.; Vallage, B.; van Elewyck, V.; Vecchi, M.; Vernin, P.; Wijnker, G.; de Wolf, E.; Yepes, H.; Zaborov, D.; Zornoza, J. D.; Zúñiga, J.

    2010-03-01

    An Acoustic Doppler Current Profiler (ADCP) moored at the deep-sea ANTARES neutrino telescope site near Toulon, France, measured downward vertical currents of amplitudes up to 0.03 m s-1 in spring 2006. The currents were accompanied by enhanced levels of acoustic reflection by a factor of about 10 and by horizontal currents reaching 0.35 m s-1. These observations coincided with high levels of bioluminescence detected by the telescope. Although during winter 2006 deep dense-water formation occurred in this area, episodes of high levels of suspended particles and large vertical currents continuing into the summer are not direct evidence of this process. It is hypothesized that the main process allowing for particles to be moved across the entire water column (2500 m) within a few days, is local convection, triggered by small-mesoscale phenomena, such as meanders including a bipolar vortex, linked with boundary current instabilities.

  15. 3. OVERVIEW OF NORTH PART, SOLDIER FIELD, LOOKING NORTHEAST FROM ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. OVERVIEW OF NORTH PART, SOLDIER FIELD, LOOKING NORTHEAST FROM THE WALL ALONG THE WEST SIDE, OPPOSITE THE CHAPEL. NOTE STONE WALL AND PILASTERS IN THE FAR CENTRAL DISTANCE. - Presidio of Monterey, Soldier Field, Monterey, Monterey County, CA

  16. Strong-mixing induced deep ocean heat uptake events in the North Atlantic.

    NASA Astrophysics Data System (ADS)

    Somavilla Cabrillo, Raquel; Gonzalez-Pola, Cesar; Schauer, Ursula; Budeus, Gedeon

    2015-04-01

    The deceleration of the upper ocean heat storage during the last decade has resulted in an active search for the 'missing heat' in the deep ocean. Modeling work has provided new insights into the role of the central Pacific Ocean on the present hiatus in global warming and the efficient transfer of heat to the deep ocean, but recent studies have highlighted also the large contribution of the North Atlantic basin to these processes, mainly based on ocean observations. The deep ocean heat uptake (below 300 m) in the North Atlantic is not confined to the subpolar gyre region but extends to mid-latitudes of the Eastern North Atlantic (ENA), requiring an additional process for its explanation other than deep convection considered until now. Here, using oceanographic in-situ data, we describe a mechanism of heat and salt injection to the deep ocean after years of warming and saltening at the surface occurred both in regions of mode (43°-48°N) and deep water (74°-76°N) formation in the ENA. The mechanism, although punctual meditated by strong winter mixing events, is between 2 and 6 times higher than the 2000-2010 ocean heat uptake at depths of mode (300-700m) and deep water (>2000m) formation, contributing significantly to the observed deep ocean heat uptake in the North Atlantic. Nutrient, hydrographic and reanalysis data indicate that the strong mixing-induced deep ocean heat uptake events at areas of mode and deep water formation in the North Atlantic are connected through the northward propagation of salty ENA mode waters triggered by the contraction of the subpolar gyre reinforced by the occurrences of blocking anomalies in the ENA. Such connection is not unique of the last decade but observed also during the 1960s. Natural climate variability seems the ultimate driver of the strong mixing-induced deep ocean heat uptake events, although the anthropogenic global warming and its forcing on the Arctic sea-ice retreat and frequency of extreme weather events could

  17. Changes of the North Atlantic deep circulation at the Eirik Drift since the Pliocene

    NASA Astrophysics Data System (ADS)

    Müller-Michaelis, A.; Uenzelmann-Neben, G.

    2013-12-01

    The global climate and its changes are coupled to the ocean circulation. The surface ocean stores and transports heat and freshwater, interacts with the overlying atmosphere and thereby impacts the climate. The global Thermohaline circulation (THC) is described as a conveyor belt for heat and freshwater within the world's oceans. Deep-water formation in high latitudes is the driving mechanism of the THC. It connects the surface circulation with the reversed deep circulation. The Eirik Drift, located offshore southern Greenland, lies closely downstream of the deep-water formation regions of the Nordic Seas and is built under the influence of the deep branch of the North Atlantic THC. The sedimentary packages and structures of the Eirik Drift therefore bear information about strength and direction of the North Atlantic deep-water circulation in a changing climate. High-resolution seismic reflection data collected during RV Maria S. Merian cruise MSM12/2 in 2009 were incorporated with geological information from ODP Leg 105 Site 646 and IODP Expedition 303 Sites 1305-1307 and led to a seismostratigraphic analysis of the sedimentary structure of the Eirik Drift. For the Pliocene Epoch we observed an intensification of the deep circulation at the Eirik Drift along with the climate reversal to the early Pliocene warm period (~5.6 Ma, horizon R2). The maximum intensity of the deep circulation at the Eirik Drift is documented in an erosional unconformity at ~4.5 Ma. The deep circulation at the Eirik Drift remained strong during the transition to Pliocene cooling (~3.2 Ma) until ~2.5 Ma (horizon R1), when the onset of ice rafting documents the intensification of Northern Hemisphere glaciation. During the series of glaciations of the Pleistocene Epoch a shallowing and weakening of the deep current system at the Eirik Drift was observed. The observation of intensification of the deep circulation during warm climate conditions and weakening during cold climate phases is in

  18. Deep water formation in the North Pacific and deglacial CO2 rise

    NASA Astrophysics Data System (ADS)

    Rae, James W. B.; Sarnthein, Michael; Foster, Gavin L.; Ridgwell, Andy; Grootes, Pieter M.; Elliott, Tim

    2014-06-01

    Deep water formation in the North Atlantic and Southern Ocean is widely thought to influence deglacial CO2 rise and climate change; here we suggest that deep water formation in the North Pacific may also play an important role. We present paired radiocarbon and boron isotope data from foraminifera from sediment core MD02-2489 at 3640 m in the North East Pacific. These show a pronounced excursion during Heinrich Stadial 1, with benthic-planktic radiocarbon offsets dropping to ~350 years, accompanied by a decrease in benthic δ11B. We suggest that this is driven by the onset of deep convection in the North Pacific, which mixes young shallow waters to depth, old deep waters to the surface, and low-pH water from intermediate depths into the deep ocean. This deep water formation event was likely driven by an increase in surface salinity, due to subdued atmospheric/monsoonal freshwater flux during Heinrich Stadial 1. The ability of North Pacific Deep Water (NPDW) formation to explain the excursions seen in our data is demonstrated in a series of experiments with an intermediate complexity Earth system model. These experiments also show that breakdown of stratification in the North Pacific leads to a rapid ~30 ppm increase in atmospheric CO2, along with decreases in atmospheric δ13C and Δ14C, consistent with observations of the early deglaciation. Our inference of deep water formation is based mainly on results from a single sediment core, and our boron isotope data are unavoidably sparse in the key HS1 interval, so this hypothesis merits further testing. However, we note that there is independent support for breakdown of stratification in shallower waters during this period, including a minimum in δ15N, younging in intermediate water 14C, and regional warming. We also re-evaluate deglacial changes in North Pacific productivity and carbonate preservation in light of our new data and suggest that the regional pulse of export production observed during the B

  19. Making Data Mobile: The Hubble Deep Field Academy iPad app

    NASA Astrophysics Data System (ADS)

    Eisenhamer, Bonnie; Cordes, K.; Davis, S.; Eisenhamer, J.

    2013-01-01

    Many school districts are purchasing iPads for educators and students to use as learning tools in the classroom. Educators often prefer these devices to desktop and laptop computers because they offer portability and an intuitive design, while having a larger screen size when compared to smart phones. As a result, we began investigating the potential of adapting online activities for use on Apple’s iPad to enhance the dissemination and usage of these activities in instructional settings while continuing to meet educators’ needs. As a pilot effort, we are developing an iPad app for the “Hubble Deep Field Academy” - an activity that is currently available online and commonly used by middle school educators. The Hubble Deep Field Academy app features the HDF-North image while centering on the theme of how scientists use light to explore and study the universe. It also includes features such as embedded links to vocabulary, images and videos, teacher background materials, and readings about Hubble’s other deep field surveys. It is our goal is to impact students’ engagement in STEM-related activities, while enhancing educators’ usage of NASA data via new and innovative mediums. We also hope to develop and share lessons learned with the E/PO community that can be used to support similar projects. We plan to test the Hubble Deep Field Academy app during the school year to determine if this new activity format is beneficial to the education community.

  20. Transformations of organic matter in the deep biosphere at North Pond

    NASA Astrophysics Data System (ADS)

    Jaekel, U.; Dittmar, T.; Meyer, J. L.; Huber, J. A.; Glazer, B. T.; Girguis, P. R.

    2012-12-01

    It has been long known that the oceanic crust is the largest aquifer on Earth. However, relatively little is known about how this aquifer influences biogeochemical cycles in deep ocean sediments. Recent studies have shown that in some seafloor settings such as at North Pond, an isolated sediment pond at 22°45'N near the Mid-Atlantic Ridge, crustal aquifer fluids are replete with oxygen or nitrate, replenishing the deep sediments with additional oxidants. It remains unknown to what extend a recharge of oxidants from below affects the fate of the refractory organic carbon pool in deep sediments. Ultimately, an enhanced recycling of deep organic matter in deep sediments due to the supply of oxidants from below could affect the cycling of carbon between marine sediments and the water column, thereby also influencing atmospheric CO2 levels. To investigate the transformation of the dissolved organic matter (DOM) pool in sediments at North Pond, representative sediment samples for the upper oxic, the below anoxic and the deep and oxygen replete sediment horizons were collected from three boreholes, drilled during an Integrated Ocean Drilling Program (IODP) Expedition (336) at North Pond in 2011. Analyses of DOM within the contrasting redox horizons and across the three boreholes by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS) was used to generate high-resolution profiles of the molecular composition of DOM. Comparative analyses of this data shed light on the transformations of DOM within these redox horizons and the ability of deep subsurface microorganisms to mineralize recalcitrant organic carbon in deep sediments that are replete in oxidants. Quantitative molecular approaches will be used to better examine the role of select microbial groups and functional genes involved in DOM transformations.

  1. Spatial correlation of large historical earthquakes and moderate shocks >10 km deep in eastern North America

    SciTech Connect

    Acharya, H.

    1980-12-01

    A good spatial correlation is noted between historical earthquakes with epicentral intensity > or =VIII (MM) and recent moderate size earthquakes with focal depth >10 km, suggesting that large historical earthquakes in eastern North America may be associated with deep-seated faults

  2. Seasonal copepod lipid pump promotes carbon sequestration in the deep North Atlantic.

    PubMed

    Jónasdóttir, Sigrún Huld; Visser, André W; Richardson, Katherine; Heath, Michael R

    2015-09-29

    Estimates of carbon flux to the deep oceans are essential for our understanding of global carbon budgets. Sinking of detrital material ("biological pump") is usually thought to be the main biological component of this flux. Here, we identify an additional biological mechanism, the seasonal "lipid pump," which is highly efficient at sequestering carbon into the deep ocean. It involves the vertical transport and metabolism of carbon rich lipids by overwintering zooplankton. We show that one species, the copepod Calanus finmarchicus overwintering in the North Atlantic, sequesters an amount of carbon equivalent to the sinking flux of detrital material. The efficiency of the lipid pump derives from a near-complete decoupling between nutrient and carbon cycling—a "lipid shunt," and its direct transport of carbon through the mesopelagic zone to below the permanent thermocline with very little attenuation. Inclusion of the lipid pump almost doubles the previous estimates of deep-ocean carbon sequestration by biological processes in the North Atlantic.

  3. Seasonal copepod lipid pump promotes carbon sequestration in the deep North Atlantic

    NASA Astrophysics Data System (ADS)

    Huld Jónasdóttir, Sigrún; Visser, André W.; Richardson, Katherine; Heath, Michael R.

    2015-09-01

    Estimates of carbon flux to the deep oceans are essential for our understanding of global carbon budgets. Sinking of detrital material ("biological pump") is usually thought to be the main biological component of this flux. Here, we identify an additional biological mechanism, the seasonal "lipid pump," which is highly efficient at sequestering carbon into the deep ocean. It involves the vertical transport and metabolism of carbon rich lipids by overwintering zooplankton. We show that one species, the copepod Calanus finmarchicus overwintering in the North Atlantic, sequesters an amount of carbon equivalent to the sinking flux of detrital material. The efficiency of the lipid pump derives from a near-complete decoupling between nutrient and carbon cycling-a "lipid shunt," and its direct transport of carbon through the mesopelagic zone to below the permanent thermocline with very little attenuation. Inclusion of the lipid pump almost doubles the previous estimates of deep-ocean carbon sequestration by biological processes in the North Atlantic.

  4. Projected pH reductions by 2100 might put deep North Atlantic biodiversity at risk

    NASA Astrophysics Data System (ADS)

    Gehlen, M.; Séférian, R.; Jones, D. O. B.; Roy, T.; Roth, R.; Barry, J.; Bopp, L.; Doney, S. C.; Dunne, J. P.; Heinze, C.; Joos, F.; Orr, J. C.; Resplandy, L.; Segschneider, J.; Tjiputra, J.

    2014-12-01

    This study aims to evaluate the potential for impacts of ocean acidification on North Atlantic deep-sea ecosystems in response to IPCC AR5 Representative Concentration Pathways (RCPs). Deep-sea biota is likely highly vulnerable to changes in seawater chemistry and sensitive to moderate excursions in pH. Here we show, from seven fully coupled Earth system models, that for three out of four RCPs over 17% of the seafloor area below 500 m depth in the North Atlantic sector will experience pH reductions exceeding -0.2 units by 2100. Increased stratification in response to climate change partially alleviates the impact of ocean acidification on deep benthic environments. We report on major pH reductions over the deep North Atlantic seafloor (depth >500 m) and at important deep-sea features, such as seamounts and canyons. By 2100, and under the high CO2 scenario RCP8.5, pH reductions exceeding -0.2 (-0.3) units are projected in close to 23% (~15%) of North Atlantic deep-sea canyons and ~8% (3%) of seamounts - including seamounts proposed as sites of marine protected areas. The spatial pattern of impacts reflects the depth of the pH perturbation and does not scale linearly with atmospheric CO2 concentration. Impacts may cause negative changes of the same magnitude or exceeding the current target of 10% of preservation of marine biomes set by the convention on biological diversity, implying that ocean acidification may offset benefits from conservation/management strategies relying on the regulation of resource exploitation.

  5. Reduced admixture of North Atlantic Deep Water to the deep central South Pacific during the last two glacial periods

    NASA Astrophysics Data System (ADS)

    Molina-Kescher, Mario; Frank, Martin; Tapia, Raúl; Ronge, Thomas A.; Nürnberg, Dirk; Tiedemann, Ralf

    2016-06-01

    The South Pacific is a sensitive location for the variability of the global oceanic thermohaline circulation given that deep waters from the Atlantic Ocean, the Southern Ocean, and the Pacific Basin are exchanged. Here we reconstruct the deep water circulation of the central South Pacific for the last two glacial cycles (from 240,000 years ago to the Holocene) based on radiogenic neodymium (Nd) and lead (Pb) isotope records complemented by benthic stable carbon data obtained from two sediment cores located on the flanks of the East Pacific Rise. The records show small but consistent glacial/interglacial changes in all three isotopic systems with interglacial average values of -5.8 and 18.757 for ɛNd and 206Pb/204Pb, respectively, whereas glacial averages are -5.3 and 18.744. Comparison of this variability of Circumpolar Deep Water (CDW) to previously published records along the pathway of the global thermohaline circulation is consistent with reduced admixture of North Atlantic Deep Water to CDW during cold stages. The absolute values and amplitudes of the benthic δ13C variations are essentially indistinguishable from other records of the Southern Hemisphere and confirm that the low central South Pacific sedimentation rates did not result in a significant reduction of the amplitude of any of the measured proxies. In addition, the combined detrital Nd and strontium (87Sr/86Sr) isotope signatures imply that Australian and New Zealand dust has remained the principal contributor of lithogenic material to the central South Pacific.

  6. Hydrogeochemical signatures of thermal springs compared to deep formation water of North Germany

    NASA Astrophysics Data System (ADS)

    Bozau, Elke; van Berk, Wolfgang

    2014-05-01

    Thermal springs and hot deep formation waters can be used for geothermal energy production. Depending on the chemical composition of the used waters, geothermal power plants have to deal with scaling and corrosion effects. Therefore, the understanding of the hydrogeochemical behaviour of such waters can be helpful to enhance the efficiency of the energy production. This study is comparing hydrogeochemical characteristics of thermal springs in the Harz Mountains (North Germany) and deep formation water of the North German Basin. The Harz Mountains consist of uplifted Palaeozoic rocks, whereas the North German Basin consists of sedimentary layers of Permian, Mesozoic and Cenozoic age. Volcanic rocks are included in the Permian layers. The thickness of the sedimentary basin varies between 2 km and more than 8 km. The deep aquifers of the North German Basin are mostly not involved in the recent meteoric water cycle. Their waters have contents of Total Dissolved Solids (TDS) up to about 400 g/L. Thermal springs of the Harz Mountains are situated close to the main fracture system of the region. These springs are connected to the meteoric water cycle and display lower contents of TDS (< 25 g/L). In both geological systems the TDS content is increasing with depth and temperature. The elemental ratios of the waters (e.g., Na/Cl, Cl/Br, Na/Ca) indicate similar hydrogeochemical formation processes in the Harz Mountains and the North German Basin. The concentrations of calcium, sodium, and chloride differ due to salt dissolution and feldspar transformation (albitisation) in the thermal springs as well as in the deep formation waters. Based on today's knowledge hydrochemical and stratigraphical data from the North German Basin can be used to elucidate the geological origin of the thermal springs in the Harz Mountains. Acknowledgements. The presented data are results of the collaborative research program "gebo" (Geothermal energy and high performance drilling), financed by the

  7. Modeling Extremely Deep Convection over North America as a Source of Stratospheric Water Vapor

    NASA Astrophysics Data System (ADS)

    Leroy, S. S.; Clapp, C.; Smith, J. B.; Anderson, J. G.

    2015-12-01

    We have run the Advanced Research Weather Research and Forecasting Model (ARW) at scales that numerically resolve convection over a broad swath of the north central U.S. Our intentions were to simulate convective events that generated stratospheric water vapor plumes observed during the SEAC4RS mission, to quantify the amount of water vapor injected into the stratosphere by extremely deep convection, and to investigate ARW as a potential tool to forecast multi-decadal trends in extremely deep convection over North America. We have run ARW for five and a half days beginning at 12 UTC on 26 August 2013 on a 3-km horizontal grid with 50 vertical levels. We used MERRA for the initial conditions and boundary conditions because of its skill in reanalysis of water vapor. ARW was able to simulate many of the fundamental features of deep convection over North America, including specific events. We have shown that the convection simulated by ARW bears many of the features of mesoscale convective systems, including the flow of cold air over warm moist air, cold downdrafts and gust fronts, mid-level inflow, and wedges reminiscent of squall lines. The source of water vapor for the convection is low-level eastward transport into the ARW domain. Convection is initiated where local maxima in equivalent potential temperature of surface air form. Convection regularly penetrates to the level of neutral buoyancy of the surface air and can even influence the concentration of water vapor above. A few convective events inject water vapor above the 400 K potential temperature surface. Surprisingly, deep convective events can also desiccate the upper air, even in the stratosphere. There is clear evidence of convection generating ducted internal gravity waves that propagate upstream to trigger more deep convection. We will present a quantification of the amount of water vapor injected into the stratosphere by extremely deep convection, the causes of desiccation, and the mechanisms

  8. VizieR Online Data Catalog: Spitzer-CANDELS catalog within 5 deep fields (Ashby+, 2015)

    NASA Astrophysics Data System (ADS)

    Ashby, M. L. N.; Willner, S. P.; Fazio, G. G.; Dunlop, J. S.; Egami, E.; Faber, S. M.; Ferguson, H. C.; Grogin, N. A.; Hora, J. L.; Huang, J.-S.; Koekemoer, A. M.; Labbe, I.; Wang, Z.

    2015-08-01

    We chose to locate S-CANDELS inside the wider and shallower fields already covered by Spitzer Extended Deep Survey (SEDS), in regions that enjoy deep optical and NIR imaging from HST/CANDELS. These S-CANDELS fields are thus the Extended GOODS-south (aka the GEMS field, hereafter ECDFS; Rix et al. 2004ApJS..152..163R; Castellano et al. 2010A&A...511A..20C), the Extended GOODS-north (HDFN; Giavalisco et al. 2004, II/261; Wang et al. 2010, J/ApJS/187/251; Hathi et al. 2012ApJ...757...43H; Lin et al. 2012ApJ...756...71L), the UKIDSS UDS (aka the Subaru/XMM Deep Field, Ouchi et al. 2001ApJ...558L..83O; Lawrence et al. 2007, II/319), a narrow field within the EGS (Davis et al. 2007ApJ...660L...1D; Bielby et al. 2012A&A...545A..23B), and a strip within the UltraVista deep survey of the larger COSMOS field (Scoville et al. 2007ApJS..172...38S; McCracken et al. 2012, J/A+A/544/A156). The S-CANDELS observing strategy was designed to maximize the area covered to full depth within the CANDELS area. Each field was visited twice with six months separating the two visits. Table 1 lists the epochs for each field. All of the IRAC full-depth coverage is within the SEDS area (Ashby et al. 2013, J/ApJ/769/80), and almost all is within the area covered by HST for CANDELS. (6 data files).

  9. NICMOS Calibration Challenges in the Ultra Deep Field

    NASA Technical Reports Server (NTRS)

    Thompson, Rodger I.

    2006-01-01

    The reduction of NICMOS observations in the Hubble Ultra Deep Field required unique reduction and calibration techniques, not required for images containing brighter sources. This paper describes some of these techniques which may be useful in the reduction of other fields containing extremely faint sources. These techniques apply to NICMOS camera 3 which was the only NICMOS camera utilized in the observations. The absolute accuracy of the NICMOS camera 3 photometry was also investigated using the observations of the solar analog star P330-E. As a result the sensitivity of the camera in the F110W and F160W was found to be less than the sensitivities used in the construction of the Version 2.0 NICMOS Treasury catalog for the observations in the Hubble Ultra Deep Field. The catalog fluxes are too low by between 8 and 9%.

  10. The first microbiological contamination assessment by deep-sea drilling and coring by the D/V Chikyu at the Iheya North hydrothermal field in the Mid-Okinawa Trough (IODP Expedition 331)

    PubMed Central

    Yanagawa, Katsunori; Nunoura, Takuro; McAllister, Sean M.; Hirai, Miho; Breuker, Anja; Brandt, Leah; House, Christopher H.; Moyer, Craig L.; Birrien, Jean-Louis; Aoike, Kan; Sunamura, Michinari; Urabe, Tetsuro; Mottl, Michael J.; Takai, Ken

    2013-01-01

    During the Integrated Ocean Drilling Program (IODP) Expedition 331 at the Iheya North hydrothermal system in the Mid-Okinawa Trough by the D/V Chikyu, we conducted microbiological contamination tests of the drilling and coring operations. The contamination from the drilling mud fluids was assessed using both perfluorocarbon tracers (PFT) and fluorescent microsphere beads. PFT infiltration was detected from the periphery of almost all whole round cores (WRCs). By contrast, fluorescent microspheres were not detected in hydrothermally active core samples, possibly due to thermal decomposition of the microspheres under high-temperature conditions. Microbial contamination from drilling mud fluids to the core interior subsamples was further characterized by molecular-based evaluation. The microbial 16S rRNA gene phylotype compositions in the drilling mud fluids were mainly composed of sequences of Beta- and Gammaproteobacteria, and Bacteroidetes and not archaeal sequences. The phylotypes that displayed more than 97% similarity to the sequences obtained from the drilling mud fluids were defined as possible contaminants in this study and were detected as minor components of the bacterial phylotype compositions in 13 of 37 core samples. The degree of microbiological contamination was consistent with that determined by the PFT and/or microsphere assessments. This study suggests a constructive approach for evaluation and eliminating microbial contamination during riser-less drilling and coring operations by the D/V Chikyu. PMID:24265628

  11. The first microbiological contamination assessment by deep-sea drilling and coring by the D/V Chikyu at the Iheya North hydrothermal field in the Mid-Okinawa Trough (IODP Expedition 331).

    PubMed

    Yanagawa, Katsunori; Nunoura, Takuro; McAllister, Sean M; Hirai, Miho; Breuker, Anja; Brandt, Leah; House, Christopher H; Moyer, Craig L; Birrien, Jean-Louis; Aoike, Kan; Sunamura, Michinari; Urabe, Tetsuro; Mottl, Michael J; Takai, Ken

    2013-01-01

    During the Integrated Ocean Drilling Program (IODP) Expedition 331 at the Iheya North hydrothermal system in the Mid-Okinawa Trough by the D/V Chikyu, we conducted microbiological contamination tests of the drilling and coring operations. The contamination from the drilling mud fluids was assessed using both perfluorocarbon tracers (PFT) and fluorescent microsphere beads. PFT infiltration was detected from the periphery of almost all whole round cores (WRCs). By contrast, fluorescent microspheres were not detected in hydrothermally active core samples, possibly due to thermal decomposition of the microspheres under high-temperature conditions. Microbial contamination from drilling mud fluids to the core interior subsamples was further characterized by molecular-based evaluation. The microbial 16S rRNA gene phylotype compositions in the drilling mud fluids were mainly composed of sequences of Beta- and Gammaproteobacteria, and Bacteroidetes and not archaeal sequences. The phylotypes that displayed more than 97% similarity to the sequences obtained from the drilling mud fluids were defined as possible contaminants in this study and were detected as minor components of the bacterial phylotype compositions in 13 of 37 core samples. The degree of microbiological contamination was consistent with that determined by the PFT and/or microsphere assessments. This study suggests a constructive approach for evaluation and eliminating microbial contamination during riser-less drilling and coring operations by the D/V Chikyu.

  12. Connectivity between surface and deep waters determines prokaryotic diversity in the North Atlantic Deep Water

    PubMed Central

    Frank, Alexander H.; Garcia, Juan A. L.; Herndl, Gerhard J.

    2016-01-01

    Summary To decipher the influence of depth stratification and surface provincialism on the dark ocean prokaryotic community composition, we sampled the major deep‐water masses in the eastern North Atlantic covering three biogeographic provinces. Their diversity was evaluated using ordination and canonical analysis of 454 pyrotag sequences. Variance partitioning suggested that 16% of the variation in the bacterial community composition was based on depth stratification while 9% of the variation was due to geographic location. General linear mixed effect models showed that the community of the subsurface waters was connected to the dark ocean prokaryotic communities in different biogeographic provinces. Cluster analysis indicated that some prokaryotic taxa are specific to distinct regions in bathypelagic water masses. Taken together, our data suggest that the dark ocean prokaryotic community composition of the eastern North Atlantic is primed by the formation and the horizontal transport of water masses. PMID:26914787

  13. Abrupt changes in the southern extent of North Atlantic Deep Water during Dansgaard-Oeschger events

    NASA Astrophysics Data System (ADS)

    Gottschalk, Julia; Skinner, Luke C.; Misra, Sambuddha; Waelbroeck, Claire; Menviel, Laurie; Timmermann, Axel

    2015-12-01

    The glacial climate system transitioned rapidly between cold (stadial) and warm (interstadial) conditions in the Northern Hemisphere. This variability, referred to as Dansgaard-Oeschger variability, is widely believed to arise from perturbations of the Atlantic Meridional Overturning Circulation. Evidence for such changes during the longer Heinrich stadials has been identified, but direct evidence for overturning circulation changes during Dansgaard-Oeschger events has proven elusive. Here we reconstruct bottom water [CO32-] variability from B/Ca ratios of benthic foraminifera and indicators of sedimentary dissolution, and use these reconstructions to infer the flow of northern-sourced deep water to the deep central sub-Antarctic Atlantic Ocean. We find that nearly every Dansgaard-Oeschger interstadial is accompanied by a rapid incursion of North Atlantic Deep Water into the deep South Atlantic. Based on these results and transient climate model simulations, we conclude that North Atlantic stadial-interstadial climate variability was associated with significant Atlantic overturning circulation changes that were rapidly transmitted across the Atlantic. However, by demonstrating the persistent role of Atlantic overturning circulation changes in past abrupt climate variability, our reconstructions of carbonate chemistry further indicate that the carbon cycle response to abrupt climate change was not a simple function of North Atlantic overturning.

  14. Baseball field looking North from same camera station as previous ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Baseball field looking North from same camera station as previous view - New York State Soldiers & Sailors Home, Department of Veterans Affairs Medical Center, 76 Veterans Avenue, Bath, Steuben County, NY

  15. Deep Borehole Field Test Requirements and Controlled Assumptions.

    SciTech Connect

    Hardin, Ernest

    2015-07-01

    This document presents design requirements and controlled assumptions intended for use in the engineering development and testing of: 1) prototype packages for radioactive waste disposal in deep boreholes; 2) a waste package surface handling system; and 3) a subsurface system for emplacing and retrieving packages in deep boreholes. Engineering development and testing is being performed as part of the Deep Borehole Field Test (DBFT; SNL 2014a). This document presents parallel sets of requirements for a waste disposal system and for the DBFT, showing the close relationship. In addition to design, it will also inform planning for drilling, construction, and scientific characterization activities for the DBFT. The information presented here follows typical preparations for engineering design. It includes functional and operating requirements for handling and emplacement/retrieval equipment, waste package design and emplacement requirements, borehole construction requirements, sealing requirements, and performance criteria. Assumptions are included where they could impact engineering design. Design solutions are avoided in the requirements discussion. Deep Borehole Field Test Requirements and Controlled Assumptions July 21, 2015 iv ACKNOWLEDGEMENTS This set of requirements and assumptions has benefited greatly from reviews by Gordon Appel, Geoff Freeze, Kris Kuhlman, Bob MacKinnon, Steve Pye, David Sassani, Dave Sevougian, and Jiann Su.

  16. Latitudinal gradients of species richness in the deep-sea benthos of the North Atlantic.

    PubMed

    Rex, M A; Stuart, C T; Coyne, G

    2000-04-11

    Latitudinal species diversity gradients (LSDGs) in the Northern Hemisphere are the most well established biogeographic patterns on Earth. Despite long-standing interest in LSDGs as a central problem in ecology, their explanation remains uncertain. In terrestrial as well as coastal and pelagic marine ecosystems, these poleward declines in diversity typically have been represented and interpreted in terms of species richness, the number of coexisting species. Newly discovered LSDGs in the bathyal (500-4,000 m) benthos of the North Atlantic may help to resolve the underlying causes of these large-scale trends because the deep sea is such a physically distinct environment. However, a major problem in comparing surface and deep-sea LSDGs is that the latter have been measured differently, by using species diversity indices that are affected by both species richness and the evenness of relative abundance. Here, we demonstrate that deep-sea isopods, gastropods, and bivalves in the North Atlantic do exhibit poleward decreases in species richness, just as those found in other environments. A comprehensive systematic revision of the largest deep-sea gastropod family (Turridae) has provided a unique database on geographic distributions that is directly comparable to those used to document LSDGs in surface biotas. This taxon also shows a poleward decline in the number of species. Seasonal organic enrichment from sinking phytodetritus is the most plausible ecological explanation for deep-sea LSDGs and is the environmental factor most consistently associated with depressed diversity in a variety of bathyal habitats.

  17. The Radio-Far Infrared Correlation in the NEP Deep Field

    NASA Astrophysics Data System (ADS)

    Barrufet, Laia; White, Glenn J.; Pearson, Chris; Serjeant, Stephen; Lim, Tanya; Matsuhara, Hideo; Oi, Nagisa; Karouzos, Marios; AKARI-NEP Team

    2017-03-01

    We report the results of a multi-wavelength study in the North Ecliptic Pole (NEP) deep field and examine the far infrared-radio correlation (FIRC) for high and low redshift objects. We have found a correlation between the GMRT data at 610 MHz and the Herschel data at 250 μm that has been used to define a spectral index. This spectral index shows no evolution against redshift. As a result of the study, we show a radio colour-infrared diagram that can be used as a redshift indicator.

  18. Ultraviolet Galaxy Counts From STIS Observations of The Hubble Deep Fields

    NASA Technical Reports Server (NTRS)

    Gardner, J. P.; Brown, T. M.; Ferguson, H. C.; Fisher, Richard R. (Technical Monitor)

    2000-01-01

    We present galaxy counts in the near and far ultraviolet (NUV and FUV) obtained from Space Telescope Imaging Spectrograph (STIS) observations of portions of the Hubble Deep Field North, (HDFN), the Hubble Deep Field South, (HDFS) and a parallel field near the HDFN. All three fields have deep (AB>29) optical imaging, and we determine magnitudes by taking the ultraviolet flux detected within the limiting optical isophote. An analysis of the UV-optical colors of detected objects, combined with a visual inspection of the UV images, indicates that there are no detectable objects in the UV images which are not also detected in the optical. We measure the detection area and completeness as a function of magnitude by taking the size-magnitude distribution of galaxies in the entire HDFN WFPC2 V+I image, applying the measured UV-optical colors from the detected galaxies, and determining the total area over which each galaxy would have been detected in the UV images. The average area for the simulated galaxies in each UV magnitude bin, (including galaxies which would not be detected at all), provides the effective area and completeness for the bin. We test this procedure with Monte Carlo simulations. The galaxy counts reach to AB=29 in both the NUV and FUV; 1 magnitude fainter than the HDF F30OW counts, and 7 magnitudes fainter than balloon-based counts. We compare our measured counts to various models.

  19. Ultraviolet Galaxy Counts From STIS Observations of The Hubble Deep Fields

    NASA Technical Reports Server (NTRS)

    Gardner, J. P.; Brown, T. M.; Ferguson, H. C.; Fisher, Richard R. (Technical Monitor)

    2000-01-01

    We present galaxy counts in the near and far ultraviolet (NUV and FUV) obtained from Space Telescope Imaging Spectrograph (STIS) observations of portions of the Hubble Deep Field North, (HDFN), the Hubble Deep Field South, (HDFS) and a parallel field near the HDFN. All three fields have deep (AB>29) optical imaging, and we determine magnitudes by taking the ultraviolet flux detected within the limiting optical isophote. An analysis of the UV-optical colors of detected objects, combined with a visual inspection of the UV images, indicates that there are no detectable objects in the UV images which are not also detected in the optical. We measure the detection area and completeness as a function of magnitude by taking the size-magnitude distribution of galaxies in the entire HDFN WFPC2 V+I image, applying the measured UV-optical colors from the detected galaxies, and determining the total area over which each galaxy would have been detected in the UV images. The average area for the simulated galaxies in each UV magnitude bin, (including galaxies which would not be detected at all), provides the effective area and completeness for the bin. We test this procedure with Monte Carlo simulations. The galaxy counts reach to AB=29 in both the NUV and FUV; 1 magnitude fainter than the HDF F30OW counts, and 7 magnitudes fainter than balloon-based counts. We compare our measured counts to various models.

  20. Enhanced North Atlantic deep convection preceding Heinrich 1 glacial ice sheet destabilization

    NASA Astrophysics Data System (ADS)

    Seidenkrantz, Marit-Solveig; Kuijpers, Antoon; Lindgreen, Holger

    2015-04-01

    The Labrador Sea is a crucial center of action for North Atlantic meridional overturning circulation. This region is characterized in winter by strong cold and dry winds from land or ice surfaces inducing large heat and moisture fluxes at the ocean-atmosphere interface. Particularly in late winter these conditions favor deep-convection processes leading to the formation of a relatively homogeneous and oxygen-rich intermediate water mass (Labrador Sea Water, LSW) spreading to other parts of the North Atlantic at water depths between about 1,000 and 2,000 m. Sedimentary records from the Labrador Sea have previously indicated here the presence of North Atlantic Deep Water during periods in between glacial ('Heinrich') ice-rafting events. The present sediment core investigation based on clay mineralogical analysis and study of the benthic foraminiferal fauna shows a significant oxygenation event at 18000 cal.yrs BP recorded both in the Labrador Sea and at the northern margin of Rockall Trough at 2381 m and 1286 m water depth, respectively. We conclude this ventilation pulse to be related to a period of enhanced deep convection and formation of glacial North Atlantic Intermediate Water occupying those parts of the water column presently affected under conditions of strong LSW formation. This ventilation event implies an early, significant re-activation of North Atlantic meridional overturning circulation after the Last Glacial Maximum immediately prior to Heinrich 1 large-scale ice-sheet destabilization. This scenario points to an oceanic trigger mechanism for large-scale glacial iceberg surges around the northern North Atlantic, which involves enhanced northward ocean (sub)surface heat transport and subsequent enhanced bottom melting of floating outlet glaciers and ice shelves.

  1. Projected pH reductions by 2100 might put deep North Atlantic biodiversity at risk

    NASA Astrophysics Data System (ADS)

    Gehlen, M.; Séférian, R.; Jones, D. O. B.; Roy, T.; Roth, R.; Barry, J.; Bopp, L.; Doney, S. C.; Dunne, J. P.; Heinze, C.; Joos, F.; Orr, J. C.; Resplandy, L.; Segschneider, J.; Tjiputra, J.

    2014-06-01

    This study aims at evaluating the potential for impacts of ocean acidification on North Atlantic deep-sea ecosystems in response to IPCC AR5 Representative Concentration Pathways (RCP). Deep-sea biota is likely highly vulnerable to changes in seawater chemistry and sensitive to moderate excursions in pH. Here we show, from seven fully-coupled Earth system models, that for three out of four RCPs over 17% of the seafloor area below 500 m depth in the North Atlantic sector will experience pH reductions exceeding -0.2 units by 2100. Increased stratification in response to climate change partially alleviates the impact of ocean acidification on deep benthic environment. We report major potential consequences of pH reductions for deep-sea biodiversity hotspots, such as seamounts and canyons. By 2100 and under the high CO2 scenario RCP8.5 pH reductions exceeding -0.2, (respectively -0.3) units are projected in close to 23% (~ 15%) of North Atlantic deep-sea canyons and ~ 8% (3%) of seamounts - including seamounts proposed as sites of marine protected areas. The spatial pattern of impacts reflects the depth of the pH perturbation and does not scale linearly with atmospheric CO2 concentration. Impacts may cause negative changes of the same magnitude or exceeding the current target of 10% of preservation of marine biomes set by the convention on biological diversity implying that ocean acidification may offset benefits from conservation/management strategies relying on the regulation of resource exploitation.

  2. Human Activities on the Deep Seafloor in the North East Atlantic: An Assessment of Spatial Extent

    PubMed Central

    Benn, Angela R.; Weaver, Philip P.; Billet, David S. M.; van den Hove, Sybille; Murdock, Andrew P.; Doneghan, Gemma B.; Le Bas, Tim

    2010-01-01

    Background Environmental impacts of human activities on the deep seafloor are of increasing concern. While activities within waters shallower than 200 m have been the focus of previous assessments of anthropogenic impacts, no study has quantified the extent of individual activities or determined the relative severity of each type of impact in the deep sea. Methodology The OSPAR maritime area of the North East Atlantic was chosen for the study because it is considered to be one of the most heavily impacted by human activities. In addition, it was assumed data would be accessible and comprehensive. Using the available data we map and estimate the spatial extent of five major human activities in the North East Atlantic that impact the deep seafloor: submarine communication cables, marine scientific research, oil and gas industry, bottom trawling and the historical dumping of radioactive waste, munitions and chemical weapons. It was not possible to map military activities. The extent of each activity has been quantified for a single year, 2005. Principal Findings Human activities on the deep seafloor of the OSPAR area of the North Atlantic are significant but their footprints vary. Some activities have an immediate impact after which seafloor communities could re-establish, while others can continue to make an impact for many years and the impact could extend far beyond the physical disturbance. The spatial extent of waste disposal, telecommunication cables, the hydrocarbon industry and marine research activities is relatively small. The extent of bottom trawling is very significant and, even on the lowest possible estimates, is an order of magnitude greater than the total extent of all the other activities. Conclusions/Significance To meet future ecosystem-based management and governance objectives for the deep sea significant improvements are required in data collection and availability as well as a greater awareness of the relative impact of each human activity

  3. Incursions of southern-sourced water into the deep North Atlantic during late Pliocene glacial intensification

    NASA Astrophysics Data System (ADS)

    Lang, David C.; Bailey, Ian; Wilson, Paul A.; Chalk, Thomas B.; Foster, Gavin L.; Gutjahr, Marcus

    2016-05-01

    The circulation and internal structure of the oceans exert a strong influence on Earth's climate because they control latitudinal heat transport and the segregation of carbon between the atmosphere and the abyss. Circulation change, particularly in the Atlantic Ocean, is widely suggested to have been instrumental in the intensification of Northern Hemisphere glaciation when large ice sheets first developed on North America and Eurasia during the late Pliocene, approximately 2.7 million years ago. Yet the mechanistic link and cause/effect relationship between ocean circulation and glaciation are debated. Here we present new records of North Atlantic Ocean structure using the carbon and neodymium isotopic composition of marine sediments recording deep water for both the Last Glacial to Holocene (35-5 thousand years ago) and the late Pliocene to earliest Pleistocene (3.3-2.4 million years ago). Our data show no secular change. Instead we document major southern-sourced water incursions into the deep North Atlantic during prominent glacials from 2.7 million years ago. Our results suggest that Atlantic circulation acts as a positive feedback rather than as an underlying cause of late Pliocene Northern Hemisphere glaciation. We propose that, once surface Southern Ocean stratification and/or extensive sea-ice cover was established, cold-stage expansions of southern-sourced water such as those documented here enhanced carbon dioxide storage in the deep ocean, helping to increase the amplitude of glacial cycles.

  4. Rapid reductions in North Atlantic Deep Water during the peak of the last interglacial period.

    PubMed

    Galaasen, Eirik Vinje; Ninnemann, Ulysses S; Irvalı, Nil; Kleiven, Helga Kikki F; Rosenthal, Yair; Kissel, Catherine; Hodell, David A

    2014-03-07

    Deep ocean circulation has been considered relatively stable during interglacial periods, yet little is known about its behavior on submillennial time scales. Using a subcentennially resolved epibenthic foraminiferal δ(13)C record, we show that the influence of North Atlantic Deep Water (NADW) was strong at the onset of the last interglacial period and was then interrupted by several prominent centennial-scale reductions. These NADW transients occurred during periods of increased ice rafting and southward expansions of polar water influence, suggesting that a buoyancy threshold for convective instability was triggered by freshwater and circum-Arctic cryosphere changes. The deep Atlantic chemical changes were similar in magnitude to those associated with glaciations, implying that the canonical view of a relatively stable interglacial circulation may not hold for conditions warmer and fresher than at present.

  5. THE 2012 HUBBLE ULTRA DEEP FIELD (UDF12): OBSERVATIONAL OVERVIEW

    SciTech Connect

    Koekemoer, Anton M.; Ellis, Richard S.; Schenker, Matthew A.; McLure, Ross J.; Dunlop, James S.; Bowler, Rebecca A. A.; Rogers, Alexander B.; Curtis-Lake, Emma; Cirasuolo, Michele; Wild, V.; Targett, T.; Robertson, Brant E.; Schneider, Evan; Stark, Daniel P.; Ono, Yoshiaki; Ouchi, Masami; Charlot, Stephane; Furlanetto, Steven R.

    2013-11-01

    We present the 2012 Hubble Ultra Deep Field campaign (UDF12), a large 128 orbit Cycle 19 Hubble Space Telescope program aimed at extending previous Wide Field Camera 3 (WFC3)/IR observations of the UDF by quadrupling the exposure time in the F105W filter, imaging in an additional F140W filter, and extending the F160W exposure time by 50%, as well as adding an extremely deep parallel field with the Advanced Camera for Surveys (ACS) in the F814W filter with a total exposure time of 128 orbits. The principal scientific goal of this project is to determine whether galaxies reionized the universe; our observations are designed to provide a robust determination of the star formation density at z ∼> 8, improve measurements of the ultraviolet continuum slope at z ∼ 7-8, facilitate the construction of new samples of z ∼ 9-10 candidates, and enable the detection of sources up to z ∼ 12. For this project we committed to combining these and other WFC3/IR imaging observations of the UDF area into a single homogeneous dataset to provide the deepest near-infrared observations of the sky. In this paper we present the observational overview of the project and describe the procedures used in reducing the data as well as the final products that were produced. We present the details of several special procedures that we implemented to correct calibration issues in the data for both the WFC3/IR observations of the main UDF field and our deep 128 orbit ACS/WFC F814W parallel field image, including treatment for persistence, correction for time-variable sky backgrounds, and astrometric alignment to an accuracy of a few milliarcseconds. We release the full, combined mosaics comprising a single, unified set of mosaics of the UDF, providing the deepest near-infrared blank-field view of the universe currently achievable, reaching magnitudes as deep as AB ∼ 30 mag in the near-infrared, and yielding a legacy dataset on this field.

  6. Rapid freshening of the deep North Atlantic Ocean over the past four decades.

    PubMed

    Dickson, Bob; Yashayaev, Igor; Meincke, Jens; Turrell, Bill; Dye, Stephen; Holfort, Juergen

    2002-04-25

    The overflow and descent of cold, dense water from the sills of the Denmark Strait and the Faroe Shetland channel into the North Atlantic Ocean is the principal means of ventilating the deep oceans, and is therefore a key element of the global thermohaline circulation. Most computer simulations of the ocean system in a climate with increasing atmospheric greenhouse-gas concentrations predict a weakening thermohaline circulation in the North Atlantic as the subpolar seas become fresher and warmer, and it is assumed that this signal will be transferred to the deep ocean by the two overflows. From observations it has not been possible to detect whether the ocean's overturning circulation is changing, but recent evidence suggests that the transport over the sills may be slackening. Here we show, through the analysis of long hydrographic records, that the system of overflow and entrainment that ventilates the deep Atlantic has steadily changed over the past four decades. We find that these changes have already led to sustained and widespread freshening of the deep ocean.

  7. Reserve growth in oil fields of the North Sea

    USGS Publications Warehouse

    Klett, T.R.; Gautier, D.L.

    2005-01-01

    The assessment of petroleum resources of the North Sea, as well as other areas of the world, requires a viable means to forecast the amount of growth of reserve estimates (reserve growth) for discovered fields and to predict the potential fully developed sizes of undiscovered fields. This study investigates the utility of North Sea oil field data to construct reserve-growth models. Oil fields of the North Sea provide an excellent dataset in which to examine the mechanisms, characteristics, rates and quantities of reserve growth because of the high level of capital investments, implementation of sophisticated technologies and careful data collection. Additionally, these field data are well reported and available publicly. Increases in successive annual estimat es of recoverable crude oil volumes indicate that oil fields in the North Sea, collectively and in each country, experience reserve growth. Specific patterns of reserve growth are observed among countries and primary producing reservoir-rock types. Since 1985, Norwegian oil fields had the greatest volume increase; Danish oil fields increased by the greatest percentage relative to 1985 estimates; and British oil fields experienced an increase in recoverable oil estimates for the first ten years since 1985, followed by a slight reduction. Fields producing primarily from clastic reservoirs account for the majority of the estimated recoverable oil and, therefore, these fields had the largest volumetric increase. Fields producing primarily from chalk (limestone) reservoirs increased by a greater percentage relative to 1985 estimates than did fields producing primarily from clastic reservoirs. Additionally, the largest oil fields had the greatest volumetric increases. Although different reserve-growth patterns are observed among oil fields located in different countries, the small number of fields in Denmark precludes construction of reserve-growth models for that country. However, differences in reserve

  8. The sources of deep ocean infragravity waves observed in the North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Crawford, Wayne; Ballu, Valerie; Bertin, Xavier; Karpytchev, Mikhail

    2015-07-01

    Infragravity waves are long-period (25-250 s) ocean surface gravity waves generated in coastal zones through wave-wave interactions or oscillation of the breaking point. Most of the infragravity wave energy is trapped or dissipated near coastlines, but a small percentage escapes into the open oceans. The source of deep ocean infragravity waves is debated, specifically whether they come mostly from regions with strong source waves or from sites with particular morphologies/orientations. We correlate measurements of infragravity waves in the deep North Atlantic Ocean with infragravity wave generation parameters throughout the Atlantic Ocean to find the dominant sources of deep ocean infragravity wave energy in the North Atlantic Ocean. The deep ocean infragravity wave data are from a 5 year deployment of absolute pressure gauges west of the Azores islands (37°N, 35°W) and shorter data sets from seafloor tsunami gauges (DART buoys). Two main sources are identified: one off of the west coast of southern Europe and northern Africa (25°N-40°N) in northern hemisphere winter and the other off the west coast of equatorial Africa (the Gulf of Guinea) in southern hemisphere winter. These regions have relatively weak source waves and weak infragravity wave propagation paths to the main measurement site, indicating that that the site morphology/orientation dominates the creation of deep ocean infragravity waves. Both regions have also been identified as potential sources of global seismological noise, suggesting that the same mechanisms may be behind the generation of deep ocean infragravity waves and global seismological noise in the frequency band from 0.001 to 0.04 Hz.

  9. North Pacific Acoustic Laboratory: Deep Water Acoustic Propagation in the Philippine Sea

    DTIC Science & Technology

    2014-09-30

    capitalize on the three-dimensional character of the sound and noise fields. OBJECTIVES During 2009–2011 three experiments were conducted to study...Worcester et al., 2009). The DVLA consisted of two 1000-m subarrays: an axial subarray spanning the sound -channel axis and a deep subarray spanning... Octave Research Array (FORA). PhilSea10. The 2010–2011 NPAL Philippine Sea deep-water acoustic propagation experiment combined measurements of

  10. North Pacific Acoustic Laboratory: Deep Water Acoustic Propagation in the Philippine Sea

    DTIC Science & Technology

    2012-09-30

    high power, rubidium oscillator that is turned on once a day to check the frequency of a less precise, but low power, Q-Tech Microcomputer...understanding of (i) the basic physics of low- frequency , broadband propagation in deep water, including the effects of oceanographic variability on signal...stability and coherence, (ii) the structure of the ambient noise field in deep water at low frequencies , and (iii) the extent to which acoustic

  11. Floating production systems hit stride in North Sea fields

    SciTech Connect

    Knott, D.

    1994-05-23

    Floating production system (FPS) technology has come of age in the North Sea. That's apparent in plans to use FPSs to tap two of Northwest Europe's largest offshore oil discoveries in the last 10 years. First North Sea oil production with a floater involved a converted semisubmersible drilling rig. Floaters have been in use for small field development projects ever since. Now, industry's rising interest in FPSs reflects two trends: As the North Sea matures, discoveries are likely to be in deeper, more remote locations; and Operators increasingly are under pressure to slash costs. The paper discusses UK trends, Norway's needs, the Norne field, Norne contract, discovery of oil west of the Shetland Islands, Shell-Esso plans, the UK Machar field test, the UK Fife field, and prospects for other potential floater developments.

  12. Supernova/Acceleration Probe: Science with Wide Deep Fields

    NASA Astrophysics Data System (ADS)

    Linder, E.; Akerlof, C.; Aldering, G.; Amidei, D.; Astier, P.; Baden, A.; Bebek, C.; Bergstrom, L.; Bernstein, G.; Campbell, M.; Carithers, W.; Commins, E.; Curtis, D.; Deustua, S.; Edwards, W.; Ellis, R.; Fruchter, A.; Frye, B.; Genat, J. F.; Goldhaber, G.; Goobar, A.; Goodman, J.; Graham, J.; Hardin, D.; Harris, S.; Harvey, P.; Heetderks, H.; Holland, S.; Hook, I.; Huterer, D.; Kasen, D.; Kim, A.; Knop, R.; Lafever, R.; Lampton, M.; Levi, M.; Levin, D.; Levy, J.-M.; Lidman, C.; Lin, R.; Loken, S.; McKay, T.; McKee, S.; Metzger, M.; Miquel, R.; Mourao, A.; Nugent, P.; Pain, R.; Pankow, D.; Pennypacker, C.; Perlmutter, S.; Refregier, A.; Rich, J.; Robinson, K.; Schahmaneche, K.; Schubnell, M.; Spadafora, A.; Smoot, G.; Sullivan, G.; Tarle, G.; Tomasch, A.; SNAP Collaboration

    2001-12-01

    The SNAP satellite will survey 20 square degrees down to magnitude R=30.4 with coadded images to m(AB)=32. This is 13000 times the area of the HDF and 6300 times the area of the ACS, to about the same depth and resolution. Like the Hubble Deep Field, SNAP survey data will be eminently combinable with other observations and analyses. It can act as a feeder for NGST in galaxy structure and evolution, weak and strong lensing, rare objects, and other studies that benefit from an ultra deep 11 band survey. Its time domain capabilities probe gamma ray burst afterglows, proper motions, supernova phenomenology, and outer solar system objects. This project is supported by the US Department of Energy/Office of High Energy Physics.

  13. The transfer of bomb radiocarbon and anthropogenic lead to the deep North Atlantic Ocean observed from a deep sea coral

    NASA Astrophysics Data System (ADS)

    Lee, Jong-Mi; Eltgroth, Selene F.; Boyle, Edward A.; Adkins, Jess F.

    2017-01-01

    Deep-ocean, Δ14C, Pb concentrations, and Pb isotopes were reconstructed from a deep-sea coral Enallopsammia rostrata from 1410 m depth off of Bermuda. Our high-resolution time series is created from closely spaced radial cross sections, with samples taken from the center of concentric coral growth bands that we show to be the oldest portion of the section. Prebomb radiocarbon ages from the coral demonstrate that the vertical growth rate of the coral is linear, and the age of the coral is estimated to be 560-630 yr old based on the growth rate. Using this age model to reconstruct Δ14C in deep seawater, we first detect bomb radiocarbon at the coral growth site around 1980, and show that Δ14C increased from - 80 ± 1 ‰ (average 1930-1979) to a plateau at - 39 ± 3 ‰ (1999-2001). Pb/Ca of the coral ranges between 1.1-4.5 nmol/mol during the 16th and 17th centuries, and Pb isotope ratios (206Pb/207Pb = 1.21, 208Pb/207Pb = 2.495) in this period agree with pre-anthropogenic values found in the pelagic sediments of the North Atlantic Ocean basin. Coral Pb/Ca is slightly elevated to 6.2 ± 0.9 nmol /mol between the 1740s and the 1850s and then increases to 25.1 ± 0.2 nmol /mol in the 1990s. The increase in coral Pb/Ca is accompanied by a decrease in coral 206Pb/207Pb and 208Pb/207Pb, indicating that the increase was caused by the infiltration of anthropogenic Pb to the coral growth site. Comparing our data to the surface coral Δ14C and Pb records from Bermuda reveals a time scale of tracer transport from the surface ocean to the coral growth site. Some characteristic features, e.g., the bomb-derived Δ14C increase, appear in the deep ocean approximately 25 yr later than the surface, but the overall increase of Δ14C and Pb in the deep ocean is smaller and slower than the surface, showing the importance of mixing during the transport of these tracers.

  14. Gyre-scale deep convection in the subpolar North Atlantic Ocean during winter 2014-2015

    NASA Astrophysics Data System (ADS)

    Piron, A.; Thierry, V.; Mercier, H.; Caniaux, G.

    2017-02-01

    Using Argo floats, we show that a major deep convective activity occurred simultaneously in the Labrador Sea (LAB), south of Cape Farewell (SCF), and the Irminger Sea (IRM) during winter 2014-2015. Convection was driven by exceptional heat loss to the atmosphere (up to 50% higher than the climatological mean). This is the first observation of deep convection over such a widespread area. Mixed layer depths exceptionally reached 1700 m in SCF and 1400 m in IRM. The deep thermocline density gradient limited the mixed layer deepening in the Labrador Sea to 1800 m. Potential densities of deep waters were similar in the three basins (27.73-27.74 kg m-3) but warmer by 0.3°C and saltier by 0.04 in IRM than in LAB and SCF, meaning that each basin formed locally its own deep water. The cold anomaly that developed recently in the North Atlantic Ocean favored and was enhanced by this exceptional convection.

  15. Climatic forcing of Quaternary deep-sea benthic communities in the North Pacific Ocean

    USGS Publications Warehouse

    Yasuhara, Moriaki; Hunt, G.; Cronin, T. M.; Hokanishi, N.; Kawahata, H.; Tsujimoto, Akira; Ishitake, M.

    2012-01-01

    There is growing evidence that changes in deep-sea benthic ecosystems are modulated by climate changes, but most evidence to date comes from the North Atlantic Ocean. Here we analyze new ostracod and published foraminiferal records for the last 250,000 years on Shatsky Rise in the North Pacific Ocean. Using linear models, we evaluate statistically the ability of environmental drivers (temperature, productivity, and seasonality of productivity) to predict changes in faunal diversity, abundance, and composition. These microfossil data show glacial-interglacial shifts in overall abundances and species diversities that are low during glacial intervals and high during interglacials. These patterns replicate those previously documented in the North Atlantic Ocean, suggesting that the climatic forcing of the deep-sea ecosystem is widespread, and possibly global in nature. However, these results also reveal differences with prior studies that probably reflect the isolated nature of Shatsky Rise as a remote oceanic plateau. Ostracod assemblages on Shatsky Rise are highly endemic but of low diversity, consistent with the limited dispersal potential of these animals. Benthic foraminifera, by contrast, have much greater dispersal ability and their assemblages at Shatsky Rise show diversities typical for deep-sea faunas in other regions. Statistical analyses also reveal ostracod-foraminferal differences in relationships between environmental drivers and biotic change. Rarefied diversity is best explained as a hump-shaped function of surface productivity in ostracods, but as having a weak and positive relationship with temperature in foraminifera. Abundance shows a positive relationship with both productivity and seasonality of productivity in foraminifera, and a hump-shaped relationship with productivity in ostracods. Finally, species composition in ostracods is influenced by both temperature and productivity, but only a temperature effect is evident in foraminifera. Though

  16. Anomalous Capacitive Sheath with Deep Radio Frequency Electric Field Penetration

    SciTech Connect

    Igor D. Kaganovich

    2002-01-18

    A novel nonlinear effect of anomalously deep penetration of an external radio-frequency electric field into a plasma is described. A self-consistent kinetic treatment reveals a transition region between the sheath and the plasma. Because of the electron velocity modulation in the sheath, bunches in the energetic electron density are formed in the transition region adjusted to the sheath. The width of the region is of order V(subscript T)/omega, where V(subscript T) is the electron thermal velocity, and w is frequency of the electric field. The presence of the electric field in the transition region results in a cooling of the energetic electrons and an additional heating of the cold electrons in comparison with the case when the transition region is neglected.

  17. Decoupling of Northern North Atlantic Sea Surface Temperature and Deep Circulation during Abrupt Glacial Climate Change

    NASA Astrophysics Data System (ADS)

    Jonkers, L.; Barker, S.; Hall, I. R.

    2014-12-01

    Abrupt climate change is a prominent feature of the ice ages. The prevailing view is that these changes are related to fluctuations in ocean circulation, possibly triggered by changes in freshwater forcing as a result of ice-rafting events in the North Atlantic. Here we investigate this view by presenting results from a sediment core in the Northern North Atlantic (ODP 983 60.4°N, 23.6°W, 1984m depth, ~12-35 kyr), which is ideally positioned to monitor changes in the flow speed of Iceland-Scotland Overflow Waters. The mean size of silt (10-63 μm) has been proposed as a useful flow speed indicator, but can be influenced the presence of ice-rafted detritus (IRD). We present grain size data obtained using a Coulter counter as well as a laser diffraction particle sizer, which we compare to the proportion of Neogloboquadrina pachyderma (proxy for sea surface temperature) and manually counted coarse IRD. Grain size results are comparable for the two techniques and the influence of IRD is clearly visible in the mean size data. We use end-member modelling to derive an IRD-free estimate of flow speed variability and find clear reductions in the flow speed associated with IRD input. Sea surface temperature however, appears to vary independently from IRD input and hence deep circulation. In particular, IRD appears and current speed decreases after the onset of cooling and additional temperature variability is observed that is not associated with IRD events or changes in the deep circulation. These results question the classical view of freshwater forcing as the driver of abrupt climate change. We suggest that North Atlantic temperature variability may be related to shifts in position of the polar front and that, while IRD events may be coeval with changes in the deep circulation, these changes are not required to explain the abrupt temperature variability in the Northern North Atlantic.

  18. An Introduction to the NOAO Deep Wide-Field Survey

    NASA Astrophysics Data System (ADS)

    Jannuzi, B. T.; Dey, A.; Brown, M. J. I.; Tiede, G. P.; NDWFS Team

    2004-05-01

    The NOAO Deep Wide-Field Survey (NDWFS) is a very deep optical and IR (BWRIJHK) imaging survey of 18 square degrees of the sky with the primary goal of studying the evolution of large-scale structure from redshift 1 to 4. The survey enables investigation of the formation and evolution of galaxies and the detection of luminous, very distant (z>4), star-forming galaxies and quasars. The 9.3 square degree Boötes sub-field of the survey is of particular interest because of the extensive multi-wavelength observations now available. These include Chandra (X-rays), GALEX (UV), Spitzer (near, mid, and far IR), the VLA, and Westerbork (radio). I will review the design of the survey and the processing of the optical and near-IR imaging data as a prelude to the talks following in the special session on the NDWFS Boötes field. Our research is supported by the National Optical Astronomy Observatory which is operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under a cooperative agreement with the National Science Foundation.

  19. Characterization Efforts in a Deep Borehole Field Test

    NASA Astrophysics Data System (ADS)

    Kuhlman, K. L.; Sassani, D.; Freeze, G. A.; Hardin, E. L.; Brady, P. V.

    2016-12-01

    The US Department of Energy Office of Nuclear Energy is embarking on a Deep Borehole Field Test to investigate the feasibility of constructing and characterizing two boreholes in crystalline basement rock to a depth of 5 km (16,400 ft). The concept of deep borehole disposal for radioactive waste has some advantages, including incremental construction and loading and the enhanced natural barriers provided by deep continental crystalline basement. Site characterization activities will include geomechanical (i.e., hydrofracture stress measurements), geological (i.e., core and mud logging), hydrological (i.e., packer-based pulse and pumping tests), and chemical (i.e., fluids sampled in situ from packer intervals and extracted from cores) tests. Borehole-based characterization will be used to determine the variability of system state (i.e., stress, pressure, temperature, and chemistry) with depth and interpretation of material and system parameters relevant to numerical site simulation. We explore the effects fluid density and geothermal temperature gradients (i.e., thermohaline convection) have on characterization goals in light of expected downhole conditions, including a disturbed rock zone surrounding the borehole. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  20. Marginal Shape Deep Learning: Applications to Pediatric Lung Field Segmentation.

    PubMed

    Mansoor, Awais; Cerrolaza, Juan J; Perez, Geovanny; Biggs, Elijah; Nino, Gustavo; Linguraru, Marius George

    2017-02-11

    Representation learning through deep learning (DL) architecture has shown tremendous potential for identification, localization, and texture classification in various medical imaging modalities. However, DL applications to segmentation of objects especially to deformable objects are rather limited and mostly restricted to pixel classification. In this work, we propose marginal shape deep learning (MaShDL), a framework that extends the application of DL to deformable shape segmentation by using deep classifiers to estimate the shape parameters. MaShDL combines the strength of statistical shape models with the automated feature learning architecture of DL. Unlike the iterative shape parameters estimation approach of classical shape models that often leads to a local minima, the proposed framework is robust to local minima optimization and illumination changes. Furthermore, since the direct application of DL framework to a multi-parameter estimation problem results in a very high complexity, our framework provides an excellent run-time performance solution by independently learning shape parameter classifiers in marginal eigenspaces in the decreasing order of variation. We evaluated MaShDL for segmenting the lung field from 314 normal and abnormal pediatric chest radiographs and obtained a mean Dice similarity coefficient of 0.927 using only the four highest modes of variation (compared to 0.888 with classical ASM(1) (p-value=0.01) using same configuration). To the best of our knowledge this is the first demonstration of using DL framework for parametrized shape learning for the delineation of deformable objects.

  1. Overview of North Ecliptic Pole Deep Multi-wavelength Survey as a Probe of the Cosmic Noon Era

    NASA Astrophysics Data System (ADS)

    Matsuhara, Hideo; Oi, Nagisa

    2015-08-01

    An overview of the North Ecliptic Pole deep (0.5 deg2, NEP-Deep) multi-wavelength survey covering from X-ray to radio-wave is presented. The NEP-Deep provides us with several thousands of 15 μm or 18 μm selected sample of galaxies, which is the largest sample ever made at these wavelengths. A continuous filter coverage in the mid-infrared wavelength (7, 9, 11, 15, 18, and 24 μm) is unique and vital to diagnose the contributions from starbursts and AGNs in the galaxies out to z=2. The goal of the project is to resolve the nature of the cosmic star formation history at the cosmic noon era (e.g. z=1--2), and to find a clue to understand its decline from z=1 to present universe by utilizing the unique power of the multiwavelength survey. To achieve the goal we use a few diagnostic physical parameters unique to the NEP dataset: specific star-formation rate, dust attenuation, and obscured AGN fraction, etc.It is also noteworthy that the NEP is the legacy field thanks to its high visibility by the space observatories, such as eROSITA, Euclid, JWST, and SPICA. SPICA, the next generation large cooled space telescope is extremely powerful to study the rise and fall of the cosmic star-formation history in the universe.

  2. Deglacial pulses of deep-ocean silicate into the subtropical North Atlantic Ocean.

    PubMed

    Meckler, A N; Sigman, D M; Gibson, K A; François, R; Martínez-García, A; Jaccard, S L; Röhl, U; Peterson, L C; Tiedemann, R; Haug, G H

    2013-03-28

    Growing evidence suggests that the low atmospheric CO2 concentration of the ice ages resulted from enhanced storage of CO2 in the ocean interior, largely as a result of changes in the Southern Ocean. Early in the most recent deglaciation, a reduction in North Atlantic overturning circulation seems to have driven CO2 release from the Southern Ocean, but the mechanism connecting the North Atlantic and the Southern Ocean remains unclear. Biogenic opal export in the low-latitude ocean relies on silicate from the underlying thermocline, the concentration of which is affected by the circulation of the ocean interior. Here we report a record of biogenic opal export from a coastal upwelling system off the coast of northwest Africa that shows pronounced opal maxima during each glacial termination over the past 550,000 years. These opal peaks are consistent with a strong deglacial reduction in the formation of silicate-poor glacial North Atlantic intermediate water (GNAIW). The loss of GNAIW allowed mixing with underlying silicate-rich deep water to increase the silicate supply to the surface ocean. An increase in westerly-wind-driven upwelling in the Southern Ocean in response to the North Atlantic change has been proposed to drive the deglacial rise in atmospheric CO2 (refs 3, 4). However, such a circulation change would have accelerated the formation of Antarctic intermediate water and sub-Antarctic mode water, which today have as little silicate as North Atlantic Deep Water and would have thus maintained low silicate concentrations in the Atlantic thermocline. The deglacial opal maxima reported here suggest an alternative mechanism for the deglacial CO2 release. Just as the reduction in GNAIW led to upward silicate transport, it should also have allowed the downward mixing of warm, low-density surface water to reach into the deep ocean. The resulting decrease in the density of the deep Atlantic relative to the Southern Ocean surface promoted Antarctic overturning

  3. Distribution of Thermophilic Marine Sulfate Reducers in North Sea Oil Field Waters and Oil Reservoirs

    PubMed Central

    Nilsen, R. K.; Beeder, J.; Thorstenson, T.; Torsvik, T.

    1996-01-01

    The distribution of thermophilic marine sulfate reducers in produced oil reservoir waters from the Gullfaks oil field in the Norwegian sector of the North Sea was investigated by using enrichment cultures and genus-specific fluorescent antibodies produced against the genera Archaeoglobus, Desulfotomaculum, and Thermodesulforhabdus. The thermophilic marine sulfate reducers in this environment could mainly be classified as species belonging to the genera Archaeoglobus and Thermodesulforhabdus. In addition, some unidentified sulfate reducers were present. Culturable thermophilic Desulfotomaculum strains were not detected. Specific strains of thermophilic sulfate reducers inhabited different parts of the oil reservoir. No correlation between the duration of seawater injection and the numbers of thermophilic sulfate reducers in the produced waters was observed. Neither was there any correlation between the concentration of hydrogen sulfide and the numbers of thermophilic sulfate reducers. The results indicate that thermophilic and hyperthermophilic sulfate reducers are indigenous to North Sea oil field reservoirs and that they belong to a deep subterranean biosphere. PMID:16535321

  4. Wave Field Continuation Methods for Passive Imaging Under Deep Basins

    NASA Astrophysics Data System (ADS)

    Langston, C. A.

    2009-12-01

    The coastal plains of the central and eastern United States contain deep sections of unconsolidated to poorly consolidated sediments. These sediments mask deeper crustal and upper mantle converted phases in teleseismic receiver functions through large amplitude, near-surface reverberations, and also amplify ambient noise levels to generally reduce data signal-to-noise ratios. Removing shallow sediment wave propagation effects is critical for imaging deep lithospheric structure and will be a major hurdle to overcome when the EarthScope Transportable array and related flex array experiments are deployed within these areas. Targets include the Mississippi embayment to examine the lithosphere under a failed rift zone and along the Gulf and Atlantic coasts to illuminate the transition from continental to oceanic lithosphere. A propagator matrix formalism is used to downward continue the wave field for teleseismic P waves into the mid-crust in order to separate the upgoing S wave field from the total teleseismic response of the P wave, exposing deep Sp conversions. This method requires that the earth model from the surface to the reference depth be known. Synthetic tests show that imperfect knowledge of the earth model is not critical for calculating the upgoing P wave and downgoing P and S waves within the structure. However, the upgoing S wave field may contain large non-causal S wave arrivals before the P wave arrival. An improved earth model may be found by minimizing these non-causal arrivals. Model perturbations also show interesting effects where velocity parameters for the true model may be bracketed by stacking calculated upgoing S waves to approximately remove the non-causal arrivals. Decomposing the teleseismic wave field also yields another method for estimating the upgoing P wave that can be used in receiver function deconvolution. Upward continuation of the wave field from bedrock into the sediment section is useful for understanding the effect of thick

  5. Seasonal copepod lipid pump promotes carbon sequestration in the deep North Atlantic

    PubMed Central

    Jónasdóttir, Sigrún Huld; Visser, André W.; Richardson, Katherine; Heath, Michael R.

    2015-01-01

    Estimates of carbon flux to the deep oceans are essential for our understanding of global carbon budgets. Sinking of detrital material (“biological pump”) is usually thought to be the main biological component of this flux. Here, we identify an additional biological mechanism, the seasonal “lipid pump,” which is highly efficient at sequestering carbon into the deep ocean. It involves the vertical transport and metabolism of carbon rich lipids by overwintering zooplankton. We show that one species, the copepod Calanus finmarchicus overwintering in the North Atlantic, sequesters an amount of carbon equivalent to the sinking flux of detrital material. The efficiency of the lipid pump derives from a near-complete decoupling between nutrient and carbon cycling—a “lipid shunt,” and its direct transport of carbon through the mesopelagic zone to below the permanent thermocline with very little attenuation. Inclusion of the lipid pump almost doubles the previous estimates of deep-ocean carbon sequestration by biological processes in the North Atlantic. PMID:26338976

  6. Distribution, abundance and habitat use of deep diving cetaceans in the North-East Atlantic

    NASA Astrophysics Data System (ADS)

    Rogan, Emer; Cañadas, Ana; Macleod, Kelly; Santos, M. Begoña; Mikkelsen, Bjarni; Uriarte, Ainhize; Van Canneyt, Olivier; Vázquez, José Antonio; Hammond, Philip S.

    2017-07-01

    In spite of their oceanic habitat, deep diving cetacean species have been found to be affected by anthropogenic activities, with potential population impacts of high intensity sounds generated by naval research and oil prospecting receiving the most attention. Improving the knowledge of the distribution and abundance of this poorly known group is an essential prerequisite to inform mitigation strategies seeking to minimize their spatial and temporal overlap with human activities. We provide for the first time abundance estimates for five deep diving cetacean species (sperm whale, long-finned pilot whale, northern bottlenose whale, Cuvier's beaked whale and Sowerby's beaked whale) using data from three dedicated cetacean sighting surveys that covered the oceanic and shelf waters of the North-East Atlantic. Density surface modelling was used to obtain model-based estimates of abundance and to explore the physical and biological characteristics of the habitat used by these species. Distribution of all species was found to be significantly related to depth, distance from the 2000m depth contour, the contour index (a measure of variability in the seabed) and sea surface temperature. Predicted distribution maps also suggest that there is little spatial overlap between these species. Our results represent the best abundance estimates for deep-diving whales in the North-East Atlantic, predict areas of high density during summer and constitute important baseline information to guide future risk assessments of human activities on these species, evaluate potential spatial and temporal trends and inform EU Directives and future conservation efforts.

  7. Deep Medium-Band Subaru Imaging of the MUSYC Extended Chandra Deep Field South

    NASA Astrophysics Data System (ADS)

    Urry, C. Megan; Cardamone, C.; van Dokkum, P.; Gawiser, E.; Brammer, G.; Taylor, N.; Treister, E.; Taniguchi, Y.; Sasaki, S.; Virani, S.; Kriek, M.

    2009-01-01

    We report on deep medium-band imaging with the Subaru telescope, in 18 filters from 427 nm to 856 nm, of the MUSYC survey field in the Extended Chandra Deep Field South. We detect 80,000 galaxies to equivalent magnitude R 27 mag, of which approximately 1,000 are X-ray-luminous AGN observed with Chandra and XMM. Combining the Subaru data with optical and IR data (in U,U38,B,V,R,I,z,J,K) we obtain photometric redshifts using EAZY, a fast public photometric redshift code, in the range 0

  8. Earthquakes and Ice Cores Point to Wet Feet at the NorthGRIP Deep Drill Site

    NASA Astrophysics Data System (ADS)

    Dahl-Jensen, D.; Dahl-Jensen, T.; Gundestrup, N. S.

    2001-12-01

    A seismic broadband station was placed at the NorthGRIP deep drill site (75N, 42W) on the Greenland Ice Cap for the summer 2000. During the 2 month acquisition period 15 earthquakes with sufficient quality for Receiver Function analysis aimed at crust and mantle structure under NorthGRIP were recorded. The models are consistent with the presence of a thin sedimentary layer at the base of the ice. The seismic velocities in the sediments are lower than in the ice, indicating wet sediments. The results from the deep drilling program reveal high basal temperatures at the base of the 3080 m thick ice at NorthGRIP. The measured temperatures and the observed layer thickness' in the ice core indicate that there is basal melting of the order of 5 mm /yr. and that the geothermal heatflow is of the order of 100 mW/m2 (REF), much higher than expected. A detailed radio echo mapping of the bedrock show that NorthGRIP is located in a large, flat-bottomed valley, suggesting that the sediments observed are lacustrine. The thin layer of sediments cannot account for the unexpected high heatflow causing equally unexpected basal melting. The geology is presumed to be Precambrian. Heatflow determined in a similar way at the GRIP deep drill site (73N, 38W) is 51 mW/ m2 (Dahl-Jensen et al, 1998), more in line with expected values. Magnetic anomaly data do not indicate any volcanic structures, which could help explain the high heatflow. Gravity anomaly data show that NorthGRIP is located at the edge of marked gravity discontinuity. The cause of the discontinuity is not known, but "edge effects" could be speculated upon to be the cause of the high heatflow. D. Dahl-Jensen, N. Gundestrup, H. Miller, O. Watanabe, S.J. Johnsen, J.P. Steffensen, H.B. Clausen, A. Svensson, L.B. Larsen in press: The NorthGRIP drilling program. Annals of Glaciology, vol 35 D. Dahl-Jensen, K Mosegaard, N. Grundestrup, G.D. Clow, S.J. Johnson and N. Balling 1998: Past Temperatures Directly from the Greenland Ice

  9. The Canada-France Deep Fields Photometric Redshift Survey

    NASA Astrophysics Data System (ADS)

    Brodwin, M.; Lilly, S. J.; McCracken, H. J.; Foucaud, S.; Le Fèvre, O.; Crampton, D.

    2002-12-01

    The Canada-France Deep Fields is a UBVRIZ imaging survey covering 1 deg2 to I ~ 25. A template-fitting photometric redshift algorithm has been developed and rigorously tested, producing redshifts with a dispersion of Δ z/(1+z) ~ 0.08 for galaxies at 0Deep Field. Statistically motivated confidence intervals are computed taking into account the unique redshift likelihood function for each galaxy. Previous results from the CFDF include measurements of the angular correlation function of galaxies to I ~ 25 (McCracken et al. 2001, A&A, 376, 756) and of colour-selected Lyman Break Galaxies (Foucaud et al. 2002, submitted). The CFDF photometric redshift survey, calibrated with CFRS spectroscopy, was designed to study galaxy evolution since z ~ 1.3. With the full 3-D spatial information, real-space clustering and luminosity density evolution will be quantified over this redshift range. In this talk I will present the first results from the photometric redshift component of the survey.

  10. Reconstructing Deep Ocean Circulation in the North Atlantic from Bermuda Rise, and Beyond

    NASA Astrophysics Data System (ADS)

    McManus, J. F.

    2016-12-01

    The large-scale subsurface circulation of the ocean is an important component of the Earth's climate system, and contributes to the global and regional transport of heat and mass. Assessing how this system has changed in the past is thus a priority for understanding natural climate variability. A long-coring campaign on Bermuda Rise has provided additional abundant high-quality sediments from this site of rapid accumulation in the deep western basin, situated beneath the subtropical gyre of the North Atlantic Ocean. These sediments allow the high-resolution reconstruction of deepwater chemistry and export from this key location throughout the last 150,000 years, covering the entire last glacial cycle in a continuous section of 35 meters in core KNR191-CDH19. The suite of proxy indicators analyzed includes uranium-series disequilibria, neodymium isotopes, and benthic stable isotopes. Combined with multiple previous studies of nearby cores on Bermuda Rise, the published and new proxy data from CDH19 confirm the variability of the deep circulation in the Atlantic Ocean in association with past climate changes. The multiple indicators, along with complementary data from other locations, display coherent evidence for contrasts between deep circulation during glacial and interglacial intervals, with persistent strong, deep ventilation only within the peak interglacial of marine isotope stage 5e (MIS 5e) and the Holocene. In contrast, repeated, dramatic variability in deep ocean circulation accompanied the millennial climate changes of the last glaciation and deglaciation. The largest magnitude circulation shifts occurred at the transitions into stadials associated with the Hudson strait iceberg discharges and between them and the ensuing northern interstadial warmings, significantly exceeding that of the overall glacial-interglacial difference, highlighting the potential oceanographic and climatic importance of short-term perturbations to the deep ocean circulation.

  11. High resolution near-infrared deep fields with MCAO

    NASA Astrophysics Data System (ADS)

    Lacy, Mark; Ridgway, Susan; Jaggannathan, Preshanth; Pforr, Janine; Maraston, Claudia; Servs Team

    2014-07-01

    We have used the SERVS warm Spitzer survey to identify five rare 3-star asterisms suitable for extragalactic observations with the current multi-conjugate adaptive optics GeMS/GSAOI instrument on Gemini-South, and have been awarded time to observe them. Initial observations of one of the fields show that high image quality (better than HST in K-band) can be obtained across the entire field of view. We use lower-resolution surveys from Herschel, Spitzer and ground-based near-infrared observations to characterize the galaxies in the fields and estimate photo-zs. We discuss the use of high resolution multi-wavelength data can be used in conjunction with these images to characterize the morphologies of starforming galaxy population in these fields, concentrating on deep, 0.2" resolution 8GHz VLA data we have for three of the fields. Finally, we describe how pilot surveys such as these can be extended into the TMT era, and discuss the additional science goals that could be achieved using data from TMT instruments.

  12. Carbon isotope evidence for a northern source of deep water in the glacial western North Atlantic

    NASA Astrophysics Data System (ADS)

    Keigwin, Lloyd D.; Swift, Stephen A.

    2017-03-01

    The prevailing view of western Atlantic hydrography during the Last Glacial Maximum (LGM) calls for transport and intermixing of deep southern and intermediate northern end members. However, δ13C and Δ14C results on foraminifera from a sediment core at 5.0 km in the northern subtropics show that there may have also been a northern source of relatively young, very dense, nutrient-depleted water during the LGM (18 ky to 21 ky ago). These results, when integrated with data from other western North Atlantic locations, indicate that the ocean was poorly ventilated at 4.2 km, with better ventilation above and below that depth. If this is a signal of water mass source and not nutrient storage, it would indicate that a previously unrecognized deep water end member originated along the western margin of the Labrador Sea, analogous to dense water formation today around Antarctica and in the Okhotsk Sea.

  13. (137)Cs vertical distribution at the deep basins of the North and Central Aegean Sea, Greece.

    PubMed

    Tsabaris, C; Zervakis, V; Kaberi, H; Delfanti, R; Georgopoulos, D; Lampropoulou, M; Kalfas, C A

    2014-06-01

    Large volume seawater samples were collected for the determination of (137)Cs concentration along with depth in the deep basins of North and Central Aegean Sea. The vertical (137)Cs distribution showed maximum concentration at the bottom of the basins, while the minimum values corresponded to the intermediate layer, where Levantine water exists. The surface (137)Cs activity is found to lie between the two limits and is originated from the Black Sea waters. The typical oceanographic advection-diffusion balance model is modified to a diffusion-settling-decay balance model to better understand the vertical distribution and variation of the (137)Cs concentration in the deep basins. In addition, the diffusivity of each basin, as well as the settling speed of particulate (137)Cs is also estimated. The results are compared with theoretical approach as well as with previous data. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Petrographically deduced triassic climate for the Deep River Basin, eastern piedmont of North Carolina

    SciTech Connect

    McCarn, S.T.; Mansfield, C.F.

    1985-01-01

    A petrographic comparison of Triassic, fluvial sandstones from the Deep River Basin in the eastern piedmont of North Carolina with nearby Holocene stream sands (1) indicates that he Triassic climate was more arid than today's and (2) distinguishes an eastern, more plutonic terrane from a western, more metamorphic source terrane. The paleoclimatic interpretation is based on differences in framework composition between modern and ancient sands of the same grain size, derived from the same rock type, transported similar distances and deposited in similar settings. The Triassic sandstones contain more lithic-fragments but less quartz than otherwise equivalent, modern sand in the Deep River Basin. Feldspar content is more complex, controlled by both source-rock composition and climate. Sand from the more plutonic terrane contains more feldspar and plutonic lithic-fragments than sand from the more metamorphic terrane, which contains more quartz and metamorphic lithic-fragments. This petrographic interpretation of the Triassic sandstones along with the presence of coal, limestone, chert and caliche in the middle of the section suggests that the Triassic climate was cyclic, changing from arid to humid and back to arid. Plate-tectonic reconstructions place the Deep River Basin between the Triassic equator and Tropic of cancer, where the easterly trade winds would predominate. Therefore, the arid portions of the cycle could have been due to a periodic, orographic, rain shadow formed as the result of intermittent movement along the Jonesboro Fault, creating a highland area east of the Deep River Basin.

  15. The mantle flow field beneath western North America.

    PubMed

    Silver, P G; Holt, W E

    2002-02-08

    Although motions at the surface of tectonic plates are well determined, the accompanying horizontal mantle flow is not. We have combined observations of surface deformation and upper mantle seismic anisotropy to estimate this flow field for western North America. We find that the mantle velocity is 5.5 +/- 1.5 centimeters per year due east in a hot spot reference frame, nearly opposite to the direction of North American plate motion (west-southwest). The flow is only weakly coupled to the motion of the surface plate, producing a small drag force. This flow field is probably due to heterogeneity in mantle density associated with the former Farallon oceanic plate beneath North America.

  16. Nd isotopes in deep-sea corals in the North-eastern Atlantic

    NASA Astrophysics Data System (ADS)

    Copard, Kevin; Colin, Christophe; Douville, Eric; Freiwald, Andre; Gudmundsson, Gudmundur; De Mol, Ben; Frank, Norbert

    2010-09-01

    Neodymium (Nd) concentrations and isotopic signatures of living and fossil deep-sea coral species Lophelia pertusa, Desmophyllum dianthus and Madrepora oculata from the northeast Atlantic Ocean have been investigated in order to test the ability of deep-sea corals to reconstruct the seawater Nd isotopic signature and past changes of ocean circulation in the eastern North Atlantic. Small quantities of Nd—less than 45 ng/g—are incorporated into the aragonite skeleton of living deep-sea corals that dwell at upper intermediate depths throughout the Northeast Atlantic. Rigorous cleaning techniques are needed in order to avoid Nd contamination from manganese-oxide and iron hydroxide coatings. Moreover, Nd isotopic compositions have been measured using thermal ionization mass spectrometry (TIMS) by Nd-oxide method. Our data indicate that the isotopic signatures of modern corals are similar to those of adjacent water masses, implying that deep-sea corals can serve as an archive of the seawater Nd isotopic compositions in the past. The first results from few fully-cleaned fossils corals collected within the Porcupine Seabight and the southwest Rockall Bank reveal significantly higher ɛNd for corals dated between 150 ± 40 and 3060 ± 90 yrs than those of the living corals located in similar areas. This suggests rapid hydrological variations along the eastern margin of the North Atlantic Ocean at intermediate water depth with higher contribution of the Mediterranean Overflow Waters (MOW) or other temperate Atlantic mid-depth water masses (ENACW or NAC) in the past.

  17. Meteoroid mayhem in Ole Virginny: source of the North American tektite strewn field

    USGS Publications Warehouse

    Poag, C.W.; Powars, D.S.; Poppe, L.J.; Mixon, R.B.

    1994-01-01

    New seismic reflection data from Chesapeake Bay reveal a buried, 85-km-wide, 1.5-2.0-km-deep, peak-ring impact crater, carved through upper Eocene to Lower Cretaceous sedimentary strata and into underlying pre-Mesozoic crystalline basement rocks. A polymictic, late Eocene impact breccia, composed mainly of locally derived sedimentary debris (determined from four continuous cores), surrounds and partly fills the crater. Structural and sedimentary characteristics of the Chesapeake Bay crater closely resemble those of the Miocene Ries peak-ring crater in southern Germany. It is speculated that the Chesapeake Bay crater is the source of the North American tektite strewn field. -Authors

  18. Meteoroid mayhem in Ole Virginny: Source of the North American tektite strewn field

    USGS Publications Warehouse

    Poag, C. Wylie; Powars, David S.; Poppe, Lawrence J.; Mixon, Robert B.

    1994-01-01

    New seismic reflection data from Chesapeake Bay reveal a buried, 85-km-wide, 1.5-2.0-km-deep, peak-ring impact crater, carved through upper Eocene to Lower Cretaceous sedimentary strata and into underlying pre-Mesozoic crystalline basement rocks. A polymictic, late Eocene impact breccia, composed mainly of locally derived sedimentary debris (determined from four continuous cores), surrounds and partly fills the crater. Structural and sedimentary characteristics of the Chesapeake Bay crater closely resemble those of the Miocene Ries peakring crater in southern Germany. We speculate that the Chesapeake Bay crater is the source of the North American tektite strewn field.

  19. Instructor's Field Manual: North Carolina Outward Bound School.

    ERIC Educational Resources Information Center

    Outward Bound, Morganton, NC.

    A supplement to the North Carolina Outward Bound School's Instructor's Handbook, this field manual presents useful, but not required, information gleaned from old timers and resource books which may enable the instructor to conduct a better course. Section one considers advantages and disadvantages and provides directions and topographical maps…

  20. Instructor's Field Manual: North Carolina Outward Bound School.

    ERIC Educational Resources Information Center

    Outward Bound, Morganton, NC.

    A supplement to the North Carolina Outward Bound School's Instructor's Handbook, this field manual presents useful, but not required, information gleaned from old timers and resource books which may enable the instructor to conduct a better course. Section one considers advantages and disadvantages and provides directions and topographical maps…

  1. Faint U-Band Dropouts in the WFPC2 Parallels of the Hubble Ultra Deep Field

    NASA Astrophysics Data System (ADS)

    Wadadekar, Yogesh; Casertano, Stefano; de Mello, Duilia

    2006-09-01

    We combine data from the extremely deep Hubble Space Telescope U (F300W) image, obtained using WFPC2 as part of the parallel observations of the Hubble Ultra Deep Field campaign, with BVi images from the Great Observatories Origins Deep Survey to identify a sample of Lyman break galaxies in the redshift range 2.0<~z<~3.5. We use recent stellar population synthesis models with a wide variety of ages, metallicities, redshifts, and dust content, and a detailed representation of the H I cosmic opacity as a function of redshift to model the colors of galaxies in our combination of WFPC2 and ACS filters. Using these models, we derive improved color selection criteria that provide a clean selection of relatively unobscured star-forming galaxies in this redshift range. Our WFPC2 F300W image is the deepest image ever obtained at that wavelength. The 10 σ limiting magnitude measured over 0.2 arcsec2 is 27.5 mag in the WFPC2 F300W image, about 0.5 mag deeper than the F300W image in the Hubble Deep Field (HDF)-North. This extra depth relative to the HDFs allows us to directly probe the luminosity function about 0.5 mag deeper than the depth accessible with the HDF data along an independent line of sight. Our sample of star-forming galaxies with 2.0<~z<~3.5 includes 125 objects, the majority of which show clumpy morphologies. We measure a star formation rate density of 0.18 Msolar yr-1 Mpc-3, marginally higher than the value measured for the HDFs.

  2. QSOs and Intervening Absorbers around the Hubble Deep Field

    NASA Astrophysics Data System (ADS)

    Vanden Berk, D. E.; Stoughton, C.; Crotts, A. P. S.; Tytler, D.; Kirkman, D.

    1999-12-01

    We have imaged a 45 arcmin by 45 arcmin area centered on the Hubble Deep Field (HDF) in UBVRI passbands, down to respective limiting magnitudes of approximately 21.5, 22.5, 22.2, 22.2 and 21.2. The principal goals of the survey are to identify QSOs and to map structure traced by luminous galaxies and QSO absorption line systems in a wide volume containing the HDF. The area surveyed is 400 times that of the HDF, and 40 times that of the HDF Flanking Fields. We have selected QSO candidates from color space, and identified four QSOs and two narrow emission-line galaxies (NELGs) which have not previously been discovered, bringing the total number of known QSOs in the area to 20. The bright z=1.31 QSO only 12 arcmin away from the HDF fulfills for the northern HDF the design goal of HDFS, which was selected for its proximity to a bright QSO. About half of the QSO candidates remain for spectroscopic verification. Absorption line spectroscopy has been obtained for three bright QSOs in the field, using the Keck 10m, McDonald 2.7m, and MDM 2.4m telescopes. Five heavy-element absorption line systems have been identified, three of which overlap the well-explored redshift range covered by deep galaxy redshift surveys towards the HDF. The two absorbers occur at the same redshift as the second most populated redshift peak in the galaxy distribution, but each is more than 7/h Mpc (comoving) away from the HDF line of sight in the transverse dimension, indicating large sheet-like structures traversing the HDF at high redshift.

  3. Deep Borehole Field Test Laboratory and Borehole Testing Strategy

    SciTech Connect

    Kuhlman, Kristopher L.; Brady, Patrick V.; MacKinnon, Robert J.; Heath, Jason E.; Herrick, Courtney G.; Jensen, Richard P.; Gardner, W. Payton; Sevougian, S. David; Bryan, Charles R.; Jang, Je-Hun; Stein, Emily R.; Bauer, Stephen J.; Daley, Tom; Freifeld, Barry M.; Birkholzer, Jens; Spane, Frank A.

    2016-09-19

    Deep Borehole Disposal (DBD) of high-level radioactive wastes has been considered an option for geological isolation for many years (Hess et al. 1957). Recent advances in drilling technology have decreased costs and increased reliability for large-diameter (i.e., ≥50 cm [19.7”]) boreholes to depths of several kilometers (Beswick 2008; Beswick et al. 2014). These advances have therefore also increased the feasibility of the DBD concept (Brady et al. 2009; Cornwall 2015), and the current field test design will demonstrate the DBD concept and these advances. The US Department of Energy (DOE) Strategy for the Management and Disposal of Used Nuclear Fuel and High-Level Radioactive Waste (DOE 2013) specifically recommended developing a research and development plan for DBD. DOE sought input or expression of interest from States, local communities, individuals, private groups, academia, or any other stakeholders willing to host a Deep Borehole Field Test (DBFT). The DBFT includes drilling two boreholes nominally 200m [656’] apart to approximately 5 km [16,400’] total depth, in a region where crystalline basement is expected to begin at less than 2 km depth [6,560’]. The characterization borehole (CB) is the smaller-diameter borehole (i.e., 21.6 cm [8.5”] diameter at total depth), and will be drilled first. The geologic, hydrogeologic, geochemical, geomechanical and thermal testing will take place in the CB. The field test borehole (FTB) is the larger-diameter borehole (i.e., 43.2 cm [17”] diameter at total depth). Surface handling and borehole emplacement of test package will be demonstrated using the FTB to evaluate engineering feasibility and safety of disposal operations (SNL 2016).

  4. Evolution of Elliptical Galaxies in the FORS Deep Field

    NASA Astrophysics Data System (ADS)

    Fritz, A.; Böhm, A.; Ziegler, B. L.

    Much work has been done to study the evolution of elliptical galaxies in clusters of galaxies using scaling relations and line diagnostic diagrams. Concordant results are that the bulk of the stars for the majority of the galaxies are old and have been formed at a high redshift (e.g. Jørgensen et al. 1999, MNRAS 308, 833). But there are only a few observational studies on the evolution of field ellipticals (e.g. van Dokkum et al. 2001, ApJL 553, 39 or Koo, astro-ph/9906243) claiming that there is little difference to the cluster ellipticals. This is in contrast to expectations from hierarchical merging CDM models where giant field galaxies can still be formed at redshifts z<1 (e.g. Kauffmann 1996, MNRAS 218, 487). Therefore, we have observed spectroscopically most of the ellipticals in the FORS Deep Field (Appenzeller et al. 2000, The Messenger 100, 44) down to R=22m using the VLT/FORS1 and 2 instruments. The 34 galaxies are distributed in redshifts from z=0.16 to 0.62 with =0.35. Both the spectral resolution (1200) and the exposure times (5 h) were adequate to accurately determine absorption line strengths and velocity dispersions (σ). Here, we present first results on the evolution of the Faber-Jackson (L vs. σ) and Mg-σ relations and the age/metallicity and [Mg/Fe] abundance distributions of these field ellipticals.

  5. Deep Vadose Zone–Applied Field Research Initiative Fiscal Year 2012 Annual Report

    SciTech Connect

    Wellman, Dawn M.; Truex, Michael J.; Johnson, Timothy C.; Bunn, Amoret L.; Golovich, Elizabeth C.

    2013-03-14

    This annual report describes the background of the Deep Vadose Zone-Applied Field Research Initiative, and some of the programmatic approaches and transformational technologies in groundwater and deep vadose zone remediation developed during fiscal year 2012.

  6. Site Characterization for a Deep Borehole Field Test

    NASA Astrophysics Data System (ADS)

    Kuhlman, K. L.; Hardin, E. L.; Freeze, G. A.; Sassani, D.; Brady, P. V.

    2015-12-01

    The US Department of Energy Office of Nuclear Energy is at the beginning of 5-year Deep Borehole Field Test (DBFT) to investigate the feasibility of constructing and characterizing two boreholes in crystalline basement rock to a depth of 5 km (16,400 ft). The concept of deep borehole disposal for radioactive waste has some advantages over mined repositories, including incremental construction and loading, the enhanced natural barriers provided by deep continental crystalline basement, and reduced site characterization. Site characterization efforts need to determine an eligible site that does not have the following disqualifying characteristics: greater than 2 km to crystalline basement, upward vertical fluid potential gradients, presence of economically exploitable natural resources, presence of high permeability connection to the shallow subsurface, and significant probability of future seismic or volcanic activity. Site characterization activities for the DBFT will include geomechanical (i.e., rock in situ stress state, and fluid pressure), geological (i.e., rock and fracture infill lithology), hydrological (i.e., quantity of fluid, fluid convection properties, and solute transport mechanisms), and geochemical (i.e., rock-water interaction and natural tracers) aspects. Both direct (i.e., sampling and in situ testing) and indirect (i.e., borehole geophysical) methods are planned for efficient and effective characterization of these site aspects and physical processes. Borehole-based characterization will be used to determine the variability of system state (i.e., stress, pressure, temperature, and chemistry) with depth, and interpretation of material and system parameters relevant to numerical site simulation. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE

  7. Circulation and deep water export of the subpolar North Atlantic during the 1990's

    NASA Astrophysics Data System (ADS)

    Schott, Friedrich A.; Brandt, Peter

    Moored array observations and deep float trajectories have allowed an improved quantification of the deep subpolar circulation, in particular regarding the Deep Western Boundary Currents (DWBCs) at the exit of the subpolar gyre and the circulation of Labrador Sea Water (LSW). With the decrease of Labrador Sea deep convection during the mid 1990's, LSW salinity and temperature increased by 0.005/yr and 0.06°C/yr, respectively, over the past decade through eddy exchange with the warmer, saltier boundary current water. At the same time, water masses with upper LSW properties were generated in large quantities by shallow convection compensating the lack of classical LSW formation. Sea-level observations and model simulations have pointed to a decrease of the large-scale near-surface cyclonic subpolar gyre circulation over the past decade and we compare the associated gyre indices. The LSW-level currents at the exit of the Labrador Sea, however, show a strengthening during 1997-2005, while the DWBC east of the Grand Banks showed no significant changes from the period 1993-95 to 2005. The mean Meridional Overturning Circulation (MOC) at the exit of the subpolar gyre has been estimated by several inverse model studies to be 16±2 Sv and the corresponding heat transport at 0.61±0.07 PW. Inverse analysis for MOC variations among five hydrographic sections taken during 1993-2000 across the North Atlantic at approximately 48°N found no detectable decadal trend nor large changes, with the estimates of the MOC intensity varying among the five realizations only from 13.8 to 16.6 Sv. Two assimilation models, ECCO and SODA-POP, are evaluated for MOC variability at the exit of the subpolar basin. Only small MOC changes are found, with no indication of a decadal "MOC slowdown", in agreement also with the observed deep boundary currents in the western outflow regime.

  8. The redshift evolution of clustering in the Hubble Deep Field

    NASA Astrophysics Data System (ADS)

    Magliocchetti, M.; Maddox, S. J.

    1999-07-01

    We present a correlation function analysis for the catalogue of photometric redshifts obtained from the Hubble Deep Field image by Fernandez-Soto, Lanzetta & Yahil. By dividing the catalogue into redshift bins of width Deltaz=0.4 we measured the angular correlation function w(theta) as a function of redshift up to z~4.8. From these measurements we derive the trend of the correlation length r_0. We find that r_0(z) is roughly constant with look-back time up to z~=2, and then increases to higher values at z>~2.4. We estimate the values of r_0, assuming xi(r,z)=[rr_0(z)]^-gamma, gamma=1.8 and various geometries. For Omega_0=1 we find r_0(z=3)~=7.00+/-4.87h^-1Mpc, in good agreement with the values obtained from analysis of the Lyman break galaxies.

  9. Taxonomy of quaternary deep-sea ostracods from the Western North Atlantic ocean

    USGS Publications Warehouse

    Yasuhara, Moriaki; Okahashi, H.; Cronin, T. M.

    2009-01-01

    Late Quaternary sediments from Ocean Drilling Program (ODP) Hole 1055B, Carolina Slope, western North Atlantic (32??47.041??? N, 76??17.179??? W; 1798m water depth) were examined for deep-sea ostracod taxonomy. A total of 13933 specimens were picked from 207 samples and c. 120 species were identified. Among them, 87 species were included and illustrated in this paper. Twenty-eight new species are described. The new species are: Ambocythere sturgio, Argilloecia abba, Argilloecia caju, Argilloecia keigwini, Argilloecia robinwhatleyi, Aversovalva carolinensis, Bythoceratina willemvandenboldi, Bythocythere eugeneschornikovi, Chejudocythere tenuis, Cytheropteron aielloi, Cytheropteron demenocali, Cytheropteron didieae, Cytheropteron richarddinglei, Cytheropteron fugu, Cytheropteron guerneti, Cytheropteron richardbensoni, Eucytherura hazeli, Eucytherura mayressi, Eucytherura namericana, Eucytherura spinicorona, Posacythere hunti, Paracytherois bondi, Pedicythere atroposopetasi, Pedicythere kennettopetasi, Pedicythere klothopetasi, Pedicythere lachesisopetasi, Ruggieriella mcmanusi and Xestoleberis oppoae. Taxonomic revisions of several common species were made to reduce taxonomic uncertainty in the literature. This study provides a robust taxonomic baseline for application to palaeoceanographical reconstruction and biodiversity analyses in the deep and intermediate-depth environments of the North Atlantic Ocean. ?? The Palaeontological Association, 2009.

  10. Deep Mapping of Teuthivorous Whales and Their Prey Fields

    DTIC Science & Technology

    2016-01-01

    Ocean, Cetacean, Beaked Whale, Risso’s Dolphin, Predator- Prey, Anthropogenic Noise, Sonar, Foraging, Ecosystem , Deep-Sea, Heterogeneity, Patchiness 16... Ecosystem , Deep-Sea, Heterogeneity, Patchiness Acknowledgements We gratefully acknowledge the contributions of our collaborators on various

  11. Overflow Water Pathways in the Subpolar North Atlantic Observed with Deep Floats

    NASA Astrophysics Data System (ADS)

    Bower, Amy; Furey, Heather; Lozier, Susan

    2017-04-01

    As part of the Overturning in the Subpolar North Atlantic Program (OSNAP), a total of 135 acoustically tracked RAFOS floats have been deployed in the deep boundary currents of the Iceland, Irminger and Labrador Basins, and in the Charlie-Gibbs Fracture Zone, to investigate the pathways of Iceland-Scotland Overflow Water (ISOW) and Denmark Strait Overflow Water (DSOW). Floats were released annually in 2014, 2015 and 2016 at depths between 1800 and 2800 m for two-year missions. The array of sound sources used for tracking was expanded from 10 to 13 moorings in 2016 when it was discovered that wintertime surface roughness was negatively impacting acoustic ranges. The floats from the first setting reveal several examples of persistent , deep coherent eddy motion, including a cyclonic eddy spinning off the tip of Eirik Ridge (southwest of Cape Farewell), a cyclonic eddy in the northeastern Labrador Basin near where anticyclonic Irminger Rings are formed, and an anticyclonic eddy under the North Atlantic Current (NAC) in the central Iceland Basin. A consistent region of boundary-interior exchange was observed near Hamilton Bank on the western boundary of the Labrador Sea. Deep cyclonic recirculation gyres are revealed in all three basins. Floats released in the southward-flowing deep boundary current over the eastern flank of the Reykjanes Ridge show that shallower layers of ISOW peel off to the west and cross the Ridge into the Irminger Basin through various gaps south of 60°N, including the Bight Fracture Zone. These floats tend to turn northward and continue along the slope in the Irminger Basin. Interestingly, floats released at the ISOW level in the CGFZ did not turn into the Irminger Basin as often depicted in deep circulation schematics, but rather drifted west-northwestward toward the Labrador Sea, or eddied around west of the CGFZ and (in some cases) turned southward. This result is consistent with some previous hydrographic and high-resolution model results

  12. Grace-Derived Groundwater Depletion from Both Shallow and Deep Aquifers within North China Plain

    NASA Astrophysics Data System (ADS)

    Pan, Y.; Huang, Z.; Yeh, P. J. F.; Gong, H.

    2014-12-01

    This study explores the capability of GRACE to detect groundwater storage variations in the two sub-regions in the North China Plain (NCP): the Piedmont Plain (PP, mainly shallow unconfined-aquifers) and East-Central Plain (ECP, mainly deep confined-aquifers), both of which have the areas smaller than the typical GRACE footprint (~200,000 km2). Our assessments were based on the forward modeling method using GRACE release-05 (RL-05) solutions, hydrological models (2003-2013), and in situ groundwater level measurements (2005~2010) from both shallow and deep aquifers. Results show that the GRACE-derived GWS variation in the PP experienced a severe depletion of GWS (-46.5±6.4 mm yr-1) over the past decade, nearly 3 times that of the ECP (-16.9±2.1 mm yr-1). There were apparent renewal episodes of GWS (e.g. since 2010) in PP, which may reveal the high replenishing capability of unconfined aquifers. Despite the lower depletion rate, the deep GWS with poor recoverability may have been overexploited. The depletion rate (-16.9±2.1 mm yr-1) exceeded the maximum allowable depletion rate (~12.4 mm yr-1) based on a 50-year groundwater budget.

  13. Advection of North Atlantic Deep Water from the Labrador Sea to the southern hemisphere

    NASA Astrophysics Data System (ADS)

    Rhein, Monika; Kieke, Dagmar; Steinfeldt, Reiner

    2015-04-01

    Recently formed Labrador Seawater (LSW) and overflow water from Denmark Strait (DSOW) are main components of the Atlantic Meridional Overturning Circulation. Both exhibit a distinct chlorofluorocarbon (CFC) maximum. Here we use 25 years of CFC observations in the Atlantic to study the main features of the circulation of LSW and DSOW. From the CFC data, the age and fraction of young deep water are inferred. Due to the superior spatial data resolution compared to former attempts, regional differences in the spreading velocity and pathways of young deep water become evident, dependent on the regional circulation. The observed distributions of young LSW and DSOW showed that the DWBC is the fastest pathway to reach the southern hemisphere. The downstream decrease of the fractions of young LSW in the DWBC is slower compared to model studies. From 47°N to 42°N, DWBC transports of young LSW and DSOW decrease by 44% and 49%, respectively. At 26°N, the DWBC transport of young water is still 39% of the LSW formation rate and 44% of the DSOW overflow transport. Interior pathways also exist, especially in the subpolar North Atlantic and in the transition zone between the subpolar and subtropical gyre. Compared to DSOW, the distributions indicate a higher tendency for LSW to follow additional interior pathways. North of 45°N the major part of LSW is younger than 20 years. The general weakening of new LSW formation since the 1990s worked toward a homogenization between the LSW in the western and the eastern subpolar North Atlantic.

  14. Dispersal and population connectivity in the deep North Atlantic estimated from physical transport processes

    NASA Astrophysics Data System (ADS)

    Etter, Ron J.; Bower, Amy S.

    2015-10-01

    Little is known about how larvae disperse in deep ocean currents despite how critical estimates of population connectivity are for ecology, evolution and conservation. Estimates of connectivity can provide important insights about the mechanisms that shape patterns of genetic variation. Strong population genetic divergence above and below about 3000 m has been documented for multiple protobranch bivalves in the western North Atlantic. One possible explanation for this congruent divergence is that the Deep Western Boundary Current (DWBC), which flows southwestward along the slope in this region, entrains larvae and impedes dispersal between the upper/middle slope and the lower slope or abyss. We used Lagrangian particle trajectories based on an eddy-resolving ocean general circulation model (specifically FLAME - Family of Linked Atlantic Model Experiments) to estimate the nature and scale of dispersal of passive larvae released near the sea floor at 4 depths across the continental slope (1500, 2000, 2500 and 3200 m) in the western North Atlantic and to test the potential role of the DWBC in explaining patterns of genetic variation on the continental margin. Passive particles released into the model DWBC followed highly complex trajectories that led to both onshore and offshore transport. Transport averaged about 1 km d-1 with dispersal kernels skewed strongly right indicating that some larvae dispersed much greater distances. Offshore transport was more likely than onshore and, despite a prevailing southwestward flow, some particles drifted north and east. Dispersal trajectories and estimates of population connectivity suggested that the DWBC is unlikely to prevent dispersal among depths, in part because of strong cross-slope forces induced by interactions between the DWBC and the deeper flows of the Gulf Stream. The strong genetic divergence we find in this region of the Northwest Atlantic is therefore likely driven by larval behaviors and/or mortality that limit

  15. Radiocarbon variability in modern deep-sea bamboo coral skeletons from the North Atlantic

    NASA Astrophysics Data System (ADS)

    Farmer, J. R.; Hoenisch, B.; Robinson, L. F.

    2013-12-01

    Geochemical records from modern and recent deep-sea corals can provide new opportunities for understanding how changes in intermediate to deep ocean chemistry and circulation relate to climatic changes during the Common Era. Of critical importance for such comparisons are well-constrained coral growth rates (and hence chronology). Bamboo coral specimens of the genus Keratoisis are widely distributed in the modern oceans, but their calcitic skeletons exhibit open system U-Th behavior and many specimens show obscure growth banding, limiting available techniques for growth rate determinations. We measured radial transects of radiocarbon across the skeletons of six Keratoisis specimens that were live-collected in the northwestern North Atlantic Ocean between 1879 and 2005. Initial results show that Δ14C from the outer surface of three modern corals is within error of seawater Δ14C estimates at the site of coral collection from GLODAP. Most specimens show increasing 14C age toward the coral center, implying near-linear growth rates of 40 to 60 μm/14C year that are consistent with growth rates for North Atlantic Keratoisis specimens established by skeletal 210Pb and organic (gorgonian) 14C measurements. However, other specimens show radiocarbon variability that precludes accurate growth rate determinations for parts of the skeleton. In particular, multiple specimens exhibit systematic radiocarbon age reversals within 1-3 mm of the central growth axis, which is assumed to be the ontogenetically oldest part of the skeleton. This observation is consistent with previously published records of elevated unsupported 210Pb around the central growth axis of some North Atlantic Keratoisis specimens. We discuss potential physical and biological causes for the observed radiocarbon variability and implications for accurate growth rate determinations for bamboo coral skeletons.

  16. Crustal thinning and nature of extension in the northern North Sea from deep seismic reflection profiling

    NASA Astrophysics Data System (ADS)

    Klemperer, Simon L.

    1988-08-01

    A regional network of deep seismic reflection profiles recorded in the northern North Sea has been used to map Mesozoic and Cenozoic basin thickness and crustal thickness in the Viking Graben and adjacent platform areas. Depth to the reflection Moho varies from about 20 km in parts of the Viking Graben to about 32 km beneath the Shetlands and the Norwegian margin. The shallowing of the reflection Moho beneath the Viking Graben implies crustal stretching factors for Mesozoic extension greater than 2 in the center of the North Sea basin. The axis of crustal thinning is located directly beneath the Viking Graben, the axis of the sedimentary basin. Steeply dipping basin-bounding faults are imaged in the upper crust and several dipping reflectors are observed in the upper mantle, but no continuous reflective feature extending from the sedimentary basin to beneath the Moho is observed on any of the deep profiles. Thus these data do not support the existence of lithosphere-penetrating low-angle detachments (zones of simple shear) as the cause of extension in the northern North Sea. Some of the mantle reflectors dip to the west and some to the east, suggesting that simple shear, if it occurs in the upper mantle, is not of uniform sense. Rather, these data suggest a complex, depth-dependent pattern of brittle extensional deformation in the upper crust; pervasive, ductile extension (bulk pure shear) in the lower crust (which is decoupled from deformation in the mantle); and extension accommodated by discrete, dipping shear zones in the lithospheric mantle.

  17. Formation and pathways of North Atlantic Deep Water in a coupled ice-ocean model of the Arctic-North Atlantic Oceans

    NASA Astrophysics Data System (ADS)

    Bailey, David A.; Rhines, Peter B.; Häkkinen, Sirpa

    2005-10-01

    We investigate the formation process and pathways of deep water masses in a coupled ice-ocean model of the Arctic and North Atlantic Oceans. The intent is to determine the relative roles of these water masses from the different source regions (Arctic Ocean, Nordic Seas, and Subpolar Atlantic) in the meridional overturning circulation. The model exhibits significant decadal variability in the deep western boundary current and the overturning circulation. We use detailed diagnostics to understand the process of water mass formation in the model and the resulting effects on the North Atlantic overturning circulation. Particular emphasis is given to the multiple sources of North Atlantic Deep Water, the dominant deep water masses of the world ocean. The correct balance of Labrador Sea, Greenland Sea and Norwegian Sea sources is difficult to achieve in climate models, owing to small-scale sinking and convection processes. The global overturning circulation is described as a function of potential temperature and salinity, which more clearly signifies dynamical processes and clarifies resolution problems inherent to the high latitude oceans. We find that fluxes of deep water masses through various passages in the model are higher than observed estimates. Despite the excessive volume flux, the Nordic Seas overflow waters are diluted by strong mixing and enter the Labrador Sea at a lighter density. Through strong subpolar convection, these waters along with other North Atlantic water masses are converted into the densest waters [similar density to Antarctic Bottom Water (AABW)] in the North Atlantic. We describe the diminished role of salinity in the Labrador Sea, where a shortage of buoyant surface water (or excess of high salinity water) leads to overly strong convection. The result is that the Atlantic overturning circulation in the model is very sensitive to the surface heat flux in the Labrador Sea and hence is correlated with the North Atlantic Oscillation. As strong

  18. D" Discontinuity Structure Beneath the North Atlantic Based on Observations from the Deep 2010 Spanish Earthquake

    NASA Astrophysics Data System (ADS)

    Yao, Y.; Whittaker, S.; Thorne, M. S.

    2014-12-01

    The D" discontinuity is typically observed as an increase in P- and S-wave velocity of 1-3% roughly 150-300 km above the CMB. The discontinuity shows strong laterally variability in spatial location and height above the CMB. Previous studies have revealed strong evidence for the existence of the discontinuity under North Central Asia, Alaska, the Arctic, Australasia, and Central America, but only a handful of observations have been made beneath the North Atlantic due to the limited numbers of deep earthquakes in Europe. We collected transverse component recordings from all available broadband stations in the USArray to examine the D" discontinuity structure under the North Atlantic using array processing techniques. We searched for earthquakes in the European region between Jan. 2005 and Jun. 2014 with moment magnitudes between 5.5 and 7.5, event depths greater than 75 km, and epicentral distances from 55° to 90°. A total of five events were found matching these criteria. We collected a total of 2077 transverse component seismograms. We inspected each trace manually and removed traces without clear S and ScS arrivals. The remaining traces were aligned and normalized to unity on the S-wave arrival and collected into 3° geographic bins. We calculated velocity seismograms (vespagrams) for each geographic bin and screened vespagrams based on signal-to-noise ratio and slowness resolution of S and ScS. Only the 616 km deep M6.3 southern Spain event of April 11th, 2010 demonstrated high enough data quality. A total of 372 transverse traces from this event were collected into 39 3° geographic bins. Clear Scd arrivals indicative of the D" discontinuity were identified on 20 out of 39 vespagrams. We calculated the height of the D" discontinuity above the CMB for each Scd observation based on the travel time difference between S and Scd. The results indicate a D" discontinuity with an average thickness of 261 km above the CMB beneath the North Atlantic between 45°-60° N

  19. Ultra-deep catalog of X-ray groups in the Extended Chandra Deep Field South

    NASA Astrophysics Data System (ADS)

    Finoguenov, A.; Tanaka, M.; Cooper, M.; Allevato, V.; Cappelluti, N.; Choi, A.; Heymans, C.; Bauer, F. E.; Ziparo, F.; Ranalli, P.; Silverman, J.; Brandt, W. N.; Xue, Y. Q.; Mulchaey, J.; Howes, L.; Schmid, C.; Wilman, D.; Comastri, A.; Hasinger, G.; Mainieri, V.; Luo, B.; Tozzi, P.; Rosati, P.; Capak, P.; Popesso, P.

    2015-04-01

    Aims: We present the detection, identification and calibration of extended sources in the deepest X-ray dataset to date, the Extended Chandra Deep Field South (ECDF-S). Methods: Ultra-deep observations of ECDF-S with Chandra and XMM-Newton enable a search for extended X-ray emission down to an unprecedented flux of 2 × 10-16 ergs s-1 cm-2. By using simulations and comparing them with the Chandra and XMM data, we show that it is feasible to probe extended sources of this flux level, which is 10 000 times fainter than the first X-ray group catalogs of the ROSAT all sky survey. Extensive spectroscopic surveys at the VLT and Magellan have been completed, providing spectroscopic identification of galaxy groups to high redshifts. Furthermore, available HST imaging enables a weak-lensing calibration of the group masses. Results: We present the search for the extended emission on spatial scales of 32'' in both Chandra and XMM data, covering 0.3 square degrees and model the extended emission on scales of arcminutes. We present a catalog of 46 spectroscopically identified groups, reaching a redshift of 1.6. We show that the statistical properties of ECDF-S, such as log N - log S and X-ray luminosity function are broadly consistent with LCDM, with the exception that dn/dz/dΩ test reveals that a redshift range of 0.2 < z < 0.5 in ECDF-S is sparsely populated. The lack of nearby structure, however, makes studies of high-redshift groups particularly easier both in X-rays and lensing, due to a lower level of clustered foreground. We present one and two point statistics of the galaxy groups as well as weak-lensing analysis to show that the detected low-luminosity systems are indeed low-mass systems. We verify the applicability of the scaling relations between the X-ray luminosity and the total mass of the group, derived for the COSMOS survey to lower masses and higher redshifts probed by ECDF-S by means of stacked weak lensing and clustering analysis, constraining any possible

  20. North south asymmetry in the coronal and photospheric magnetic fields

    NASA Astrophysics Data System (ADS)

    Virtanen, I.; Mursula, K.

    2013-12-01

    Several recent studies have shown that the Heliospheric current sheet (HCS) is southward shifted during about three years in the solar declining phase (the so-called bashful ballerina phenomenon). We study the hemispherical asymmetry in the photospheric and coronal magnetic fields using Wilcox Solar Observatory (WSO) measurements of the photospheric magnetic field since 1976 and the potential field source surface (PFSS) model. Multipole analysis of the photospheric magnetic field shows that during the late declining phase of solar cycles since 1970s, bashful ballerina phenomenon is a consequence of g02 quadrupole term, signed oppositely to the dipole moment. Surges of new flux transport magnetic field from low latitudes to the poles, thus leading to a systematically varying contribution to the g02-term from different latitudes. In the case of a north-south asymmetric flux production this is seen as a quadrupole contribution traveling towards higher latitudes. When the quadrupole term is largest the main contribution comes from the polar latitudes. At least during the four recent solar cycles the g02-term arises because the magnitude of the southern polar field is larger than in the north in the declining phase of the cycle. Magnetic flux is transported polewards by the meridional flow and it is most likely that besides the north-south asymmetric production of the magnetic flux, also the asymmetric transportation may significantly contribute to the observed asymmetry of polar field intensities. The overall activity during solar cycle is not significantly different in the northern and southern hemispheres, but hemispheres tend to develop in a different phase.

  1. Site Guidelines for a Deep Borehole Field Test

    NASA Astrophysics Data System (ADS)

    Sassani, D.; Kuhlman, K. L.; Freeze, G. A.; MacKinnon, R. J.; Perry, F.

    2015-12-01

    The US DOE Office of Nuclear Energy Used Nuclear Fuel Disposition Campaign (UFDC) is initiating a Deep Borehole Field Test (DBFT), without use of any radioactive waste, to evaluate the geoscience of the approach and technical capabilities for implementation. DOE has identified Sandia National Laboratories (SNL) as the Technical Lead for the UFDC DBFT Project, with the role of supporting DOE in (i) developing the overall DBFT Project Plan, (ii) management and integration of all DBFT Project activities, and (iii) providing Project technical guidance to DOE, other DOE National Laboratories, and university partners. The DBFT includes drilling one Characterization Borehole (CB-8.5" diameter), followed by an optional Field Test Borehole (FTB), to a depth of about 5,000 m (16,400 feet) into crystalline basement rock in a geologically stable continental location. The DBFT CB will be drilled and completed to facilitate downhole scientific testing and analyses. If site conditions are found to be favorable, DOE may drill the larger-diameter (17") FTB to facilitate proof-of-concept of handling, emplacement, and retrieval activities using surrogate waste containers. Guidelines for favorable DBFT site geohydrochemical and geomechanical conditions will be discussed and status of the DBFT Project will be provided. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. SAND2015-6426A.

  2. Deep Geothermal Energy for Lower Saxony (North Germany) - Combined Investigations of Geothermal Reservoir Characteristics

    NASA Astrophysics Data System (ADS)

    Hahne, Barbara; Thomas, Rüdiger

    2014-05-01

    In Germany, successful deep geothermal projects are mainly situated in Southern Germany in the Molassebecken, furthermore in the Upper Rhine Graben and, to a minor extend, in the North German Basin. Mostly they are hydrothermal projects with the aim of heat production. In a few cases, they are also constructed for the generation of electricity. In the North German Basin temperature gradients are moderate. Therefore, deep drilling of several thousand meters is necessary to reach temperatures high enough for electricity production. However, the porosity of the sedimentary rocks is not sufficient for hydrothermal projects, so that natural fracture zones have to be used or the rocks must be hydraulically stimulated. In order to make deep geothermal projects in Lower Saxony (Northern Germany) economically more attractive, the interdisciplinary research program "Geothermal Energy and High-Performance Drilling" (gebo) was initiated in 2009. It comprises four focus areas: Geosystem, Drilling Technology, Materials and Technical System and aims at improving exploration of the geothermal reservoir, reducing costs of drilling and optimizing exploitation. Here we want to give an overview of results of the focus area "Geosystem" which investigates geological, geophysical, geochemical and modeling aspects of the geothermal reservoir. Geological and rock mechanical investigations in quarrys and core samples give a comprehensive overview on rock properties and fracture zone characteristics in sandstones and carbonates. We also show that it is possible to transfer results of rock property measurements from quarry samples to core samples or to in situ conditions by use of empirical relations. Geophysical prospecting methods were tested near the surface in a North German Graben system. We aim at transferring the results to the prospection of deep situated fracture zones. The comparison of P- and S-wave measurements shows that we can get hints on a possible fluid content of the

  3. Surface electric fields for North America during historical geomagnetic storms

    USGS Publications Warehouse

    Wei, Lisa H.; Homeier, Nichole; Gannon, Jennifer L.

    2013-01-01

    To better understand the impact of geomagnetic disturbances on the electric grid, we recreate surface electric fields from two historical geomagnetic storms—the 1989 “Quebec” storm and the 2003 “Halloween” storms. Using the Spherical Elementary Current Systems method, we interpolate sparsely distributed magnetometer data across North America. We find good agreement between the measured and interpolated data, with larger RMS deviations at higher latitudes corresponding to larger magnetic field variations. The interpolated magnetic field data are combined with surface impedances for 25 unique physiographic regions from the United States Geological Survey and literature to estimate the horizontal, orthogonal surface electric fields in 1 min time steps. The induced horizontal electric field strongly depends on the local surface impedance, resulting in surprisingly strong electric field amplitudes along the Atlantic and Gulf Coast. The relative peak electric field amplitude of each physiographic region, normalized to the value in the Interior Plains region, varies by a factor of 2 for different input magnetic field time series. The order of peak electric field amplitudes (largest to smallest), however, does not depend much on the input. These results suggest that regions at lower magnetic latitudes with high ground resistivities are also at risk from the effect of geomagnetically induced currents. The historical electric field time series are useful for estimating the flow of the induced currents through long transmission lines to study power flow and grid stability during geomagnetic disturbances.

  4. Surface electric fields for North America during historical geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Wei, Lisa H.; Homeier, Nicole; Gannon, Jennifer L.

    2013-08-01

    To better understand the impact of geomagnetic disturbances on the electric grid, we recreate surface electric fields from two historical geomagnetic storms—the 1989 "Quebec" storm and the 2003 "Halloween" storms. Using the Spherical Elementary Current Systems method, we interpolate sparsely distributed magnetometer data across North America. We find good agreement between the measured and interpolated data, with larger RMS deviations at higher latitudes corresponding to larger magnetic field variations. The interpolated magnetic field data are combined with surface impedances for 25 unique physiographic regions from the United States Geological Survey and literature to estimate the horizontal, orthogonal surface electric fields in 1 min time steps. The induced horizontal electric field strongly depends on the local surface impedance, resulting in surprisingly strong electric field amplitudes along the Atlantic and Gulf Coast. The relative peak electric field amplitude of each physiographic region, normalized to the value in the Interior Plains region, varies by a factor of 2 for different input magnetic field time series. The order of peak electric field amplitudes (largest to smallest), however, does not depend much on the input. These results suggest that regions at lower magnetic latitudes with high ground resistivities are also at risk from the effect of geomagnetically induced currents. The historical electric field time series are useful for estimating the flow of the induced currents through long transmission lines to study power flow and grid stability during geomagnetic disturbances.

  5. The structure and circulation of intermediate, deep and bottom water masses of the North Atlantic

    NASA Astrophysics Data System (ADS)

    Khmelnitskaya, Olga

    2014-05-01

    Water mass is one of the basic concepts of oceanography. Changing the characteristics of the main water masses in the North Atlantic can be causes of climate variability. The purpose of the present study is a quantitative assessment of the characteristics of water masses using the Optimum multiparameter (OMP) analysis. OMP analysis of water masses is a continuation of the thermohaline analysis. To study water mass mixing besides temperature and salinity such advanced features as concentration of nutrients, CFCs, isotopes, Redfield ratios and potential vorticity are used. Mathematically the OMP analysis is a system of linear equations for each point of the observations. Using four parameters of the water masses one can find the ratio of five water masses in the volume of water being under investigation. To study the structure of the North Atlantic Ocean we were identified eight major water masses: 1) ABW - Antarctic Bottom Water; 2) DSOW - Denmark Strait Overflow Water; 3) ISOW - Iceland-Scotland Overflow Water; 4) LSW - Labrador Sea Water; 5) MW - Mediterranean Water; 6) AIW - Antarctic Intermediate Water; 7) SPMW - Subpolar Mode Water; 8) STMW - Subtropical Mode Water. Percentage of each water mass was calculated for each section. Upon solving equation systems a data array was performed using the algorithm written in Fortran. The calculations were performed for 12 oceanographic sections made in the North Atlantic (24-64°N) in 1980-2004. We investigated the water masses located deeper than 500 m where there are practically no seasonal changes. On analysis of the water mass percentage in the vertical water sections pathways of intermediate and deep waters can be traced. Comparison of the percentage in the different sections gives an indication of the variability in the intermediate and deep circulation. We calculated the volume of each water mass in the North Atlantic Ocean (24-64°N, 0-77°W) below 500 meters on the basis of data on the percentage of water masses

  6. Suborbital timescale variability of North Atlantic Deep Water during the past 200,000 years

    NASA Astrophysics Data System (ADS)

    Oppo, Delia W.; Lehman, Scott J.

    1995-10-01

    We generated ˜200-kyr-long proxy records of surface and deepwater variability from a subpolar North Atlantic core (V29-202), enabling us to assess the linkage between surface and deepwater changes on suborbital timescales. In particular, we used a benthic δ13C record to evaluate the deep water response to Dansgaard-Oeschger temperature oscillations and to Heinrich events, times of massive iceberg delivery to the North Atlantic. We found that the reduction of North Atlantic Deep Water (NADW) production was generally associated with cold or dropping sea surface temperatures (SSTs) as indicated by planktonic foraminiferal assemblages. The NADW contribution to the site did not drop appreciably during Heinrich events H4 through H2, probably because these events followed intervals of prolonged surface cooling already characterized by low rates of NADW production. By contrast NADW reduction appears to have been synchronous with H5. SST rise associated with both Dansgaard-Oeschger oscillations and Heinrich events was usually accompanied by increasing NADW strength. In a few cases the NADW recovery appeared to lag the SST rise; however, the apparent delay is most likely an artefact of the sedimentary record (low concentrations of benthic foraminifera). As a result of low benthic foraminiferal abundances during stage 6, the stage 6 benthic foraminiferal δ13C record is of lower resolution than the younger part of the record. The stage 6 proxy records for surface hydrography nevertheless reveal millennial-scale oscillations similar to those seen in stage 3. The available δ13C data suggest that NADW weakened in association with the cold portions of stage 6 SST oscillations. We also sought to confirm a recent study which concluded that there was little NADW variability during the peak of the last interglaciation, marine oxygen isotope substage 5e (Eemian). Isotope stage 5 was marked by a trend of increasing benthic δ13C in V29-202. Rising δ13C through isotope stage 5 is

  7. Deep Infrared Survey of the Deep Chandra Field on SgrA*

    NASA Astrophysics Data System (ADS)

    Laycock, S.; Grindlay, J.; Hong, J.; Koenig, X.; Schlegel, E.; van den Berg, M.; Zhao, P.; Persson, E.

    2004-08-01

    We have observed the galactic center with the PANIC infrared imager at Magellan. In 3 nights of optimal seeing (many hours of approx. 0.3 arcsec) we obtained a 10x10 arcmin mosaic centered on SgrA*, in J,H,K and Bracket gamma. This represents the deepest IR survey surrounding SgrA* which covers the majority of the deep Chandra field obtained by Muno et al and also being studied as part of our ongoing ChaMPlane survey. The discovery of several thousand hard X-ray point sources in the GC by Muno et al a key Chandra result and this work is directed at identifying these sources, by cutting through the obscuring dust clouds and attaining the highest possible spatial resolution over the Chandra field. We will present the multicolor mosaic and preliminary analysis, concentrating on positional matches for Chandra sources. The survey is designed to find sources with colors suggestive of Be-HMXBs, CVs and other X-ray binaries. The narrow band Br-gamma data is unique in its depth and resolution and will enable discrimination of accretion sources in even the most crowded regions. This IR mosaic extends our optical work on low extinction windows in the galactic bulge (see papers by Grindlay et al and van den Berg et al), and our optical survey of the galactic bulge for ChaMPlane (see paper by Zhao et al). This work is supported by Chandra grants AR3-4002A, AR4-5003A and GO3-4033A and NSF grant AST-0098683.

  8. Lensing Signals in the Hubble Ultra-deep Field using all 2nd-order Shape Deformations

    SciTech Connect

    Irwin, John; Shmakova, Marina; Anderson, Jay; /Rice U.

    2006-07-17

    The long exposure times of the HST Ultra-Deep Field plus the use of an empirically derived position-dependent PSF, have enabled us to measure a cardioid/displacement distortion map coefficient as well as improving upon the sextupole map coefficient. We confirmed that curved background galaxies are clumped on the same angular scale as found in the HST Deep Field North. The new cardioid/displacement map coefficient is strongly correlated to a product of the sextupole and quadrupole coefficients. One would expect to see such a correlation from fits to background galaxies with quadrupole and sextupole moments. Events that depart from this correlation are expected to arise from map coefficient changes due to lensing, and several galaxy subsets selected using this criteria are indeed clumped.

  9. Resolving the phasing and forcing dynamics between North Atlantic climate and deep ocean circulation changes

    NASA Astrophysics Data System (ADS)

    Irvali, Nil; Ninnemann, Ulysses S.; Kleiven, Helga (Kikki) F.; Haflidason, Haflidi; Mjell, Tor L.

    2017-04-01

    Multidecadal changes in North Atlantic climate (e.g., AMO/AMV) have been attributed to changes in the Atlantic Meridional Overturning Circulation (AMOC) and suggested as a driver of overturning changes. While simulations find an in-phase relationship when AMOC modulates basin-wide climate, AMOC lags when basin scale climate is forced externally (e.g., volcanoes and solar). Unfortunately the observational records are too short to assess these multi-decadal scale dynamics. The surface climate reconstructions, based on annually resolved archives, have excellent time control raising the possibility for precise determination of phasing with other well dated records. Yet, all currently available reconstructions of deep ocean circulation have radiometric based age models; with inherent errors (±30-50 years minimum) preventing the determination of the absolute phasing between deep ocean circulation changes and AMO/AMV. In order to reduce these uncertainties we use stratigraphical appearance, abundance and geochemical composition of tephra grains from a high sedimentation rate site off the Gardar Drift, south of Iceland (GS06-144-09MC-D; 60˚ 19'N, 23˚ 58'W, 2081 m water depth). Identifying tephra layers (and their association) in the core and fingerprinting with known volcanic eruptions on Iceland provides absolute age markers. Combining these age markers with 210Pb and 14C AMS dates within the same core, we have built a new chronology for the core GS06-144-09MC-D. Changes in surface ocean hydrography and climate are further portrayed using planktonic foraminiferal δ18O, assemblage counts, modern analog technique derived sea surface temperatures and Mg/Ca paleothermometry. Records of Iceland Scotland Overflow Water (ISOW) vigor (Sortable Silt mean grain size; Mjell et al., 2016) and benthic carbon isotopes from the same core allow us to determine the absolute phasing between changes in basin-wide climate, deep ocean circulation, and deep water carbon chemistry spanning

  10. H-band observations of the Chandra Deep Field South

    NASA Astrophysics Data System (ADS)

    Moy, E.; Barmby, P.; Rigopoulou, D.; Huang, J.-S.; Willner, S. P.; Fazio, G. G.

    2003-05-01

    We report results of our H-band survey of the Chandra Deep Field South (CDFS). The observations, made with SofI on the NTT, cover 0.027 square degrees to H< 20.5 and 0.17 square degrees to H< 19.8 (50% completeness limits). In total, 4819 objects were detected, of which 80% are galaxies based on the SExtractor parameter ``stellarity index'' having a value less than 0.5. Our astrometric solutions are in good agreement with those of the Las Campanas Infrared Survey (LCIRS), the COMBO-17, and the ESO-EIS surveys. Our photometry compares satisfactorily with the LCIRS results as well as with GOODS data. Galaxy number counts are ~ 50 000 galaxies per square degree at H< 20.75, in good agreement with those of LCIRS. The object catalog is published electronically at the CDS. The whole catalog is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/403/493}. Based on observations collected at the European Southern Observatory, Chile under programs 66.A-0451 and 68.A-0375.

  11. Geomechanical Considerations for the Deep Borehole Field Test

    NASA Astrophysics Data System (ADS)

    Park, B. Y.

    2015-12-01

    Deep borehole disposal of high-level radioactive waste is under consideration as a potential alternative to shallower mined repositories. The disposal concept consists of drilling a borehole into crystalline basement rocks to a depth of 5 km, emplacement of canisters containing solid waste in the lower 2 km, and plugging and sealing the upper 3 km of the borehole. Crystalline rocks such as granites are particularly attractive for borehole emplacement because of their low permeability and porosity at depth, and high mechanical strength to resist borehole deformation. In addition, high overburden pressures contribute to sealing of some of the fractures that provide transport pathways. We present geomechanical considerations during construction (e.g., borehole breakouts, disturbed rock zone development, and creep closure), relevant to both the smaller-diameter characterization borehole (8.5") and the larger-diameter field test borehole (17"). Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  12. Tadpole Galaxies in the Hubble Ultra Deep Field

    NASA Astrophysics Data System (ADS)

    Elmegreen, Bruce G.; Elmegreen, Debra Meloy

    2010-10-01

    Tadpole galaxies have a head-tail shape with a large clump of star formation at the head and a diffuse tail or streak of stars off to one side. We measured the head and tail masses, ages, surface brightnesses, and sizes for 66 tadpoles in the Hubble Ultra Deep Field (UDF) and looked at the distribution of neighbor densities and tadpole orientations with respect to neighbors. The heads have masses of 107-108 M sun and photometric ages of ~0.1 Gyr for z ~ 2. The tails have slightly larger masses than the heads and comparable or slightly older ages. The most obvious interpretation of tadpoles as young merger remnants is difficult to verify. They have no enhanced proximity to other resolved galaxies as a class, and the heads, typically <0.2 kpc in diameter, usually have no obvious double-core structure. Another possibility is ram pressure interaction between a gas-rich galaxy and a diffuse cosmological flow. Ram pressure can trigger star formation on one side of a galaxy disk, giving the tadpole shape when viewed edge-on. Ram pressure can also strip away gas from a galaxy and put it into a tail, which then forms new stars and gravitationally drags along old stars with it. Such an effect might have already been observed in the Virgo Cluster. Another possibility is that tadpoles are edge-on disks with large, off-center clumps. Analogous lop-sided star formation in UDF clump clusters is shown.

  13. High-Redshift Supernovae in the Hubble Deep Field

    SciTech Connect

    Gilliland, R.L.; Nugent, P.E.; Phillips, M.M.

    1999-08-01

    Two supernovae detected in the Hubble Deep Field (HDF) using the original 1995 December epoch and data from a shorter (63,000 s in F814W) 1997 December visit with {ital HST} are discussed. The supernovae (SNe) are both associated with distinct galaxies at redshifts of 0.95 (spectroscopic) from Cohen et al. and 1.32 (photometric) from the work of Fern{acute a}ndez-Soto, Lanzetta, & Yahil. These redshifts are near, in the case of 0.95, and well beyond, for 1.32, the greatest distance reported previously for SNe. We show that our observations are sensitive to supernovae to z{approx_lt}1.8 in either epoch for an event near peak brightness. Detailed simulations are discussed that quantify the level at which false events from our search phase would start to arise and the completeness of our search as a function of both SN brightness and host galaxy redshift. The number of Type Ia and Type II SNe expected as a function of redshift in the two HDF epochs are discussed in relation to several published predictions and our own detailed calculations. A mean detection frequency of one SN per epoch for the small HDF area is consistent with expectations from current theory. {copyright} {ital {copyright} 1999.} {ital The American Astronomical Society}

  14. The Deep Convective Clouds and Chemistry (DC3) Field Experiment

    NASA Astrophysics Data System (ADS)

    Barth, M. C.; Brune, W. H.; Cantrell, C. A.; Rutledge, S. A.; Crawford, J. H.; Huntrieser, H.; Homeyer, C. R.; Nault, B.; Cohen, R. C.; Pan, L.; Ziemba, L. D.

    2014-12-01

    The Deep Convective Clouds and Chemistry (DC3) field experiment took place in the central U.S. in May and June 2012 and had the objectives of characterizing the effect of thunderstorms on the chemical composition of the lower atmosphere and determining the chemical aging of upper troposphere (UT) convective outflow plumes. DC3 employed ground-based radars, lightning mapping arrays, and weather balloon soundings in conjunction with aircraft measurements sampling the composition of the inflow and outflow of a variety of thunderstorms in northeast Colorado, West Texas to central Oklahoma, and northern Alabama. A unique aspect of the DC3 strategy was to locate and sample the convective outflow a day after active convection in order to measure the chemical transformations within the UT convective plume. The DC3 data are being analyzed to investigate transport and dynamics of the storms, scavenging of soluble trace gases and aerosols, production of nitrogen oxides by lightning, relationships between lightning flash rates and storm parameters, and chemistry in the UT that is affected by the convection. In this presentation, we give an overview of the DC3 field campaign and highlight results from the campaign that are relevant to the upper troposphere and lower stratosphere region. These highlights include stratosphere-troposphere exchange in connection with thunderstorms, the 0-12 hour chemical aging and new particle formation in the UT outflow of a dissipating mesoscale convective system observed on June 21, 2012, and UT chemical aging in convective outflow as sampled the day after convection occurred and modeled in the Weather Research and Forecasting coupled with Chemistry model.

  15. Evidence for deep-water production in the North Pacific Ocean during the early Cenozoic warm interval.

    PubMed

    Thomas, Deborah J

    2004-07-01

    The deep-ocean circulation is responsible for a significant component of global heat transport. In the present mode of circulation, deep waters form in the North Atlantic and Southern oceans where surface water becomes sufficiently cold and dense to sink. Polar temperatures during the warmest climatic interval of the Cenozoic era (approximately 65 to 40 million years (Myr) ago) were significantly warmer than today, and this may have been a consequence of enhanced oceanic heat transport. However, understanding the relationship between deep-ocean circulation and ancient climate is complicated by differences in oceanic gateways, which affect where deep waters form and how they circulate. Here I report records of neodymium isotopes from two cores in the Pacific Ocean that indicate a shift in deep-water production from the Southern Ocean to the North Pacific approximately 65 Myr ago. The source of deep waters reverted back to the Southern Ocean 40 Myr ago. The relative timing of changes in the neodymium and oxygen isotope records indicates that changes in Cenozoic deep-water circulation patterns were the consequence, not the cause, of extreme Cenozoic warmth.

  16. Defying Dissolution: Discovery of Deep-Sea Scleractinian Coral Reefs in the North Pacific.

    PubMed

    Baco, Amy R; Morgan, Nicole; Roark, E Brendan; Silva, Mauricio; Shamberger, Kathryn E F; Miller, Kelci

    2017-07-14

    Deep-sea scleractinian coral reefs are protected ecologically and biologically significant areas that support global fisheries. The absence of observations of deep-sea scleractinian reefs in the Central and Northeast Pacific, combined with the shallow aragonite saturation horizon (ASH) and high carbonate dissolution rates there, fueled the hypothesis that reef formation in the North Pacific was improbable. Despite this, we report the discovery of live scleractinian reefs on six seamounts of the Northwestern Hawaiian Islands and Emperor Seamount Chain at depths of 535-732 m and aragonite saturation state (Ωarag) values of 0.71-1.33. Although the ASH becomes deeper moving northwest along the chains, the depth distribution of the reefs becomes shallower, suggesting the ASH is having little influence on their distribution. Higher chlorophyll moving to the northwest may partially explain the geographic distribution of the reefs. Principle Components Analysis suggests that currents are also an important factor in their distribution, but neither chlorophyll nor the available current data can explain the unexpected depth distribution. Further environmental data is needed to elucidate the reason for the distribution of these reefs. The discovery of reef-forming scleractinians in this region is of concern because a number of the sites occur on seamounts with active trawl fisheries.

  17. Egg brooding by deep-sea octopuses in the North Pacific Ocean.

    PubMed

    Voight, J R; Grehan, A J

    2000-02-01

    Videotapes made from the submersible Alvin on Baby Bare, a 2600-m-deep North Pacific basalt outcrop, and at two other deep-sea localities document that octopuses of the genera Graneledone and Benthoctopus attach their eggs to hard substrate and apparently brood them through development. The behavior of brooding females was generally similar to that of shallow-water octopuses, but the genera showed apparent differences. In addition to the high density of brooding females observed at Baby Bare, which may relate to the increased availability of exposed hard substrates for egg attachment and of prey, females are suggested to increasingly associate with hard substrates as they mature. The biology of Baby Bare may seem unduly unique because the outcrop is isolated on a sedimented plain and is among the few exposures of hard substrate other than hydrothermal vents that have been explored by submersible. On the sediment-covered ocean floor, the availability of hard substrate may strongly affect the distribution of brooding octopuses. The size and shape of boreholes in 19 of over 400 thyasirid clam shells collected from Baby Bare support the hypothesis that octopuses had preyed upon the clams.

  18. The deep-sea zooplankton of the North, Central, and South Atlantic: Biomass, abundance, diversity

    NASA Astrophysics Data System (ADS)

    Vereshchaka, Alexander; Abyzova, Galina; Lunina, Anastasia; Musaeva, Eteri

    2017-03-01

    Ocean-scale surveys of vertical distribution of the zooplankton from the surface to the bathypelagic zone along transects are quite rare in the North Atlantic and absent in the Equatorial and South Atlantic. We present the first deep-sea quantitative survey of the zooplankton in the Equatorial and South Atlantic, analyze the interaction between environment (depth, water masses, surface productivity) and zooplankton abundance and biomass, and assess the biodiversity and role of copepods in various deep strata. Samples were taken at 20 sites along a submeridional transect between 40°N and 30°S at four discrete depth strata: epi- meso-, upper- and lower- bathypelagic. A closing Bogorov-Rass plankton net (1 m2 opening, 500 μm mesh size, towed at a speed of 1 m s-1) was used and three major plankton groups were defined: non-gelatinous mesozooplankton (mainly copepods and chaetognaths; 1-30 mm length), gelatinous mesozooplankton (mainly siphonophorans, medudae and salps; individual or zooid; 1-30 mm length) and macroplankton (mainly shrimps; over 30 mm length). Over 300 plankton taxa were identified, among which 243 belonged to Copepoda. Two-dimensional distribution (latitude versus depth zone) of major group biomass, total copepod abundance, and abundance of dominant species is presented as well as distribution of biodiversity parameters (number of species, Shannon and 'dominance' indices). Biomass and abundance of all major groups were depth-dependent. The number of taxa (N) was depended on surface productivity, diversity of the communities was strongly linked to depth, whilst 'evenness' was independant upon both variables. Each of depth strata was inhabited by distinct copepod assemblages, which significantly differed from each other. The paper is concluded with brief descriptions of the deep Atlantic plankton communities from studied strata.

  19. Major contribution of autotrophy to microbial carbon cycling in the deep North Atlantic’s interior

    NASA Astrophysics Data System (ADS)

    Reinthaler, Thomas; van Aken, Hendrik M.; Herndl, Gerhard J.

    2010-08-01

    Current estimates point to a mismatch of particulate organic carbon supply derived from the surface ocean and the microbial organic carbon demand in the meso- and bathypelagic realm. Based on recent findings that chemoautotrophic Crenarchaeota are abundant in the mesopelagic zone, we quantified dissolved inorganic carbon (DIC) fixation in the meso- and bathypelagic North Atlantic and compared it with heterotrophic microbial activity. Measuring 14C-bicarbonate fixation and 3H-leucine incorporation revealed that microbial DIC fixation is substantial in the mesopelagic water masses, ranging from 0.1 to 56.7 μmol C m -3 d -1, and is within the same order of magnitude as heterotrophic microbial activity. Integrated over the dark ocean's water column, DIC fixation ranged from 1-2.5 mmol C m -2 d -1, indicating that chemoautotrophy in the dark ocean represents a significant source of autochthonously produced 'new organic carbon' in the ocean's interior amounting to about 15-53% of the phytoplankton export production. Hence, chemoautotrophic DIC fixation in the oxygenated meso- and bathypelagic water column of the North Atlantic might substantially contribute to the organic carbon demand of the deep-water microbial food web.

  20. Deep subsurface life from North Pond: Enrichment, isolation, characterization and genomes of heterotrophic bacteria

    DOE PAGES

    Russell, Joseph A.; Leon-Zayas, Rosa; Wrighton, Kelly; ...

    2016-05-10

    Studies of subsurface microorganisms have yielded few environmentally relevant isolates for laboratory studies. In order to address this lack of cultivated microorganisms, we initiated several enrichments on sediment and underlying basalt samples from North Pond, a sediment basin ringed by basalt outcrops underlying an oligotrophic watercolumn west of the Mid-Atlantic Ridge at 22° N. In contrast to anoxic enrichments, growth was observed in aerobic, heterotrophic enrichments from sediment of IODP Hole U1382B at 4 and 68 m below seafloor (mbsf). These sediment depths, respectively, correspond to the fringes of oxygen penetration from overlying seawater in the top of the sedimentmore » column and upward migration of oxygen from oxic seawater from the basalt aquifer below the sediment. Here we report the enrichment, isolation, initial characterization and genomes of three isolated aerobic heterotrophs from North Pond sediments; an Arthrobacter species from 4 mbsf, and Paracoccus and Pseudomonas species from 68 mbsf. These cultivated bacteria are represented in the amplicon 16S rRNA gene libraries created from whole sediments, albeit at low (up to 2%) relative abundance. We provide genomic evidence from our isolates demonstrating that the Arthrobacter and Pseudomonas isolates have the potential to respire nitrate and oxygen, though dissimilatory nitrate reduction could not be confirmed in laboratory cultures. Furthermore, the cultures from this study represent members of abundant phyla, as determined by amplicon sequencing of environmental DNA extracts, and allow for further studies into geochemical factors impacting life in the deep subsurface.« less

  1. Deep Subsurface Life from North Pond: Enrichment, Isolation, Characterization and Genomes of Heterotrophic Bacteria

    PubMed Central

    Russell, Joseph A.; León-Zayas, Rosa; Wrighton, Kelly; Biddle, Jennifer F.

    2016-01-01

    Studies of subsurface microorganisms have yielded few environmentally relevant isolates for laboratory studies. In order to address this lack of cultivated microorganisms, we initiated several enrichments on sediment and underlying basalt samples from North Pond, a sediment basin ringed by basalt outcrops underlying an oligotrophic water-column west of the Mid-Atlantic Ridge at 22°N. In contrast to anoxic enrichments, growth was observed in aerobic, heterotrophic enrichments from sediment of IODP Hole U1382B at 4 and 68 m below seafloor (mbsf). These sediment depths, respectively, correspond to the fringes of oxygen penetration from overlying seawater in the top of the sediment column and upward migration of oxygen from oxic seawater from the basalt aquifer below the sediment. Here we report the enrichment, isolation, initial characterization and genomes of three isolated aerobic heterotrophs from North Pond sediments; an Arthrobacter species from 4 mbsf, and Paracoccus and Pseudomonas species from 68 mbsf. These cultivated bacteria are represented in the amplicon 16S rRNA gene libraries created from whole sediments, albeit at low (up to 2%) relative abundance. We provide genomic evidence from our isolates demonstrating that the Arthrobacter and Pseudomonas isolates have the potential to respire nitrate and oxygen, though dissimilatory nitrate reduction could not be confirmed in laboratory cultures. The cultures from this study represent members of abundant phyla, as determined by amplicon sequencing of environmental DNA extracts, and allow for further studies into geochemical factors impacting life in the deep subsurface. PMID:27242705

  2. Vertical diffusion and oxygen consumption during stagnation periods in the deep North Aegean

    NASA Astrophysics Data System (ADS)

    Zervakis, Vassilis; Krasakopoulou, Evangelia; Georgopoulos, Dimitris; Souvermezoglou, Ekaterini

    2003-01-01

    Ventilation of the deep basins of the North Aegean Sea takes place during relatively scarce events of massive dense water formation in that region. In the time intervals between such events, the bottom waters of each sub-basin are excluded from interaction with other water masses through advection or isopycnal mixing and the only process that changes their properties is diapycnal mixing with overlying waters. In this work we utilize a simple one-dimensional model in order to estimate the vertical eddy diffusion coefficient Kρ based on the observed rate of change of density and stratification. Vertical diffusivity is estimated for each of three sub-basins of the North Aegean, one of convex shape of the seabed and the other two of concave topography. It is noteworthy that the convex sub-basin exhibited much higher vertical diffusivity than the two concave sub-basins, a fact consistent with theoretical predictions that internal-wave-induced mixing is higher over the former shape of seabed. Furthermore, the estimates of Kρ are exploited in computing the vertical transport of dissolved oxygen through diffusion and the rate of oxygen consumption by decaying organic matter. The different levels of the estimated diffusion and oxygen consumption rates testify to the dynamical and biogeochemical characteristics of each basin.

  3. Climatic Impact of a Change in North Atlantic Deep Water Formation

    NASA Technical Reports Server (NTRS)

    Rind, D.

    1984-01-01

    The response of the ocean to climate changes is one of the most uncertain questions regarding the impact of increasing CO2 on climate and society. North Atlantic deep water (NADW) formation apparently depends on a complex confluence of different water masses originating in different areas, all of which will presumably be affected by changes in wind, evaporation, etc., as the atmosphere warms. To analyze from first principles what the effect will be on NADW formation is a task which requires an ocean modeling capability not yet available. As a substitute, past climates can be investigated to see if there is any evidence for alterations in NADW formation. In addition, the possible impact of such changes on climate can be explored. An estimate of NADW sensitivity (at least in the past) and of the climate consequences can be studied. The North Atlantic surface water temperatures can be reconstructed to indicate a substantial cooling between 11,000 and 10,000 years B.P. Were NADW formation to have ceased, it would have resulted in cooler surface waters; whether the reconstructed temperatures were due to this or some other effect cannot be determined at this time. Nevertheless, it was decided that it would be useful to see what the effect these colder temperatures would have had on the climate.

  4. Deep X-ray spectroscopy of high-z obscured AGN in the Chandra Deep Field South

    NASA Astrophysics Data System (ADS)

    Comastri, Andrea; Vignali, Cristian; Gilli, Roberto; Iwasawa, Kazushi; Georgantopoulos, Ioannis

    2012-07-01

    According to the recent models for the joint evolution of Super Massive Black Holes and their Host Galaxies, heavy obscuration represents an important phase and is expected to play a key role in the feedback mechanisms self regulating the SMBH growth. The smoking gun signature of heavy absorption is the presence of a heavily absorbed or reflected X-ray spectrum plus a strong Iron line. X-ray spectroscopy thus represents the most efficient method to uncover the most obscured sources. I will present the results of a systematic search for strong iron lines in the ultra-deep (3 Ms) XMM survey in the Chandra Deep Field South (CDFS). I will also highlight the power of deep spectroscopy to obtain redshift estimates more accurate and reliable than available photo-z. Some notable examples of synergies between ultra-deep Chandra (4 Ms) and XMM observations will be also reported.

  5. North Atlantic Surface and Deep-Water Hydrography during the Early Pliocene Warm Period

    NASA Astrophysics Data System (ADS)

    Voelker, A. H. L.; Evans, H. F.; Naafs, B. D.; Cavaleiro, C. D.; Rebotim, A.; Ventura, C.; Stein, R. H.; Channell, J. E. T.

    2014-12-01

    The early Pliocene, with atmospheric carbon dioxide concentrations at levels similar to today, is seen as a case study for Earth's future climate evolution. During this period the progressive closing of the Central American Seaway led to increased poleward heat and salt transport within the Atlantic with North Atlantic Deep Water (NADW) becoming warmer and saltier and resulting in an enhanced Atlantic Meridional Overturning Circulation (AMOC). In order to understand how stable the AMOC really was we produced millennial-scale (1-2 kyr) surface and deep-water records for IODP Site U1313 (41°N, 33°W, 3412m) for the interval from 3.4 to 4.1 Ma. This site is ideally located to monitor past AMOC changes with North Atlantic Drift waters at the surface and NADW in the deep. Although interglacial/glacial cycles are visible, the higher frequency oscillations recorded in both the planktonic G. ruber (white) and benthic Cibicidoides sp. δ18O records impede tuning to the LR04 stack (Lisiecki and Raymo, 2005). We therefore exploit a different approach: using the magnetic polarity chrons (Gilbert, Cochiti) as recorded at Site U1313 as framework, we tune our benthic δ18O record to that of ODP Site 1085 (on LR04 ages). The benthic δ13C record shows millennial-scale oscillations, and the values indicate nearly continuous NADW presence and confirm a strong AMOC, also during most of the glacial periods. Varying surface water conditions, especially during the younger interglacial periods, are reflected in the G. ruber isotope data and appear to be linked to salinity changes since they are not recorded in the alkenone sea-surface temperature data. Although glacial stages Gi 2 and Gi 4 show the expected higher benthic δ18O values, Gi 6 was the glacial period with the strongest impact on the AMOC as revealed by cooler, less ventilated surface waters and a less ventilated NADW. Overall, the AMOC was strong throughout, but experienced high frequency oscillations at a level similar to

  6. Geomorphology of the Eastern North American Continental Margin: the role of deep sea sedimentation processes

    NASA Astrophysics Data System (ADS)

    Mosher, D. C.; Campbell, C.; Piper, D.; Chaytor, J. D.; Gardner, J. V.; Rebesco, M.

    2016-12-01

    Deep-sea sedimentation processes impart a fundamental control on the morphology of the western North Atlantic continental margin from Blake Spur to Hudson Strait. This fact is illustrated by the variable patterns of cross-margin gradients that are based on extensive new multibeam echo-sounder data in concert with subbottom profiler and seismic reflection data. Most of the continental margin has a steep (>3o) upper slope down to 1500 to 2500 m and then a gradual middle and lower slope with a general concave upward shape There is a constant interplay of deep sea sedimentation processes, but the general morphology is dictated by the dominant one. Erosion by off-shelf sediment transport in turbidity currents creating channels, gullies and canyons creates the steep upper slope. These gullies and canyons amalgamate to form singular channels that are conduits to the abyssal plain. This process results in a general seaward flattening of gradients, producing an exponentially decaying slope profile. Comparatively, sediment mass failure produces steeper upper slopes due to head scarp development and a wedging architecture to the lower slope as deposits thin in the downslope direction. This process results in either a two-segment slope, and/or a significant downslope gradient change where MTDs pinch out. Large sediment bodies deposited by contour-following currents are developed all along the margin. Blake Ridge, Sackville Spur, and Hamilton Spur are large detached drifts on disparate parts of the margin. Along their crests, they form a linear profile from the shelf to abyssal plain. Deeper portions of the US continental margin are dominated by the Chesapeake Drift and Hatteras Outer Ridge; both plastered elongate mounded drifts. Farther north, particularly on the Grand Banks margin, are plastered and separated drifts. These drifts tend to form bathymetric steps in profile, where they onlap the margin. Stacked drifts create several steps. Turbidites of the abyssal plain onlap

  7. The life cycle of Anisakis simplex in the Norwegian Deep (northern North Sea).

    PubMed

    Klimpel, Sven; Palm, Harry W; Rückert, Sonja; Piatkowski, Uwe

    2004-09-01

    Copepoda (Calanus finmarchicus n = 1,722, Paraeuchaeta norvegica n = 1,955), Hyperiidae (n = 3,019), Euphausiacea (Meganyctiphanes norvegica n = 4,780), and the fishes Maurolicus muelleri (n = 500) and Pollachius virens (n = 33) were collected in the Norwegian Deep (northern North Sea) during summer 2001 to examine the importance of pelagic invertebrates and vertebrates as hosts of Anisakis simplex and their roles in the transfer of this nematode to its final hosts (Cetaceans). Third stage larvae (L3) of A. simplex were found in P. norvegica, M. muelleri and P. virens. The prevalence of A. simplex in dissected P. norvegica was 0.26%, with an intensity of 1. Prevalences in M. muelleri and P. virens were 49.6% and 100.0%, with mean intensities of 1.1-2.6 (total fish length >or=6.0-7.2) and 193.6, respectively. All specimens of C. finmarchicus and M. norvegica examined were free of anisakid nematode species and no other parasites were detected. P. norvegica, which harboured the third stage larvae, is the obligatory first intermediate host of A. simplex in the investigated area. Though there was no apparent development of larvae in M. muelleri, this fish can be considered as the obligatory second intermediate host of A. simplex in the Norwegian Deep. However, it is unlikely that the larva from P. norvegica can be successfully transmitted into the cetacean or pinniped final hosts, where they reach the adult stage. An additional growth phase and a second intermediate host is the next phase in the life cycle. Larger predators such as P. virens serve as paratenic hosts, accumulating the already infective stage from M. muelleri. The oceanic life cycle of A. simplex in the Norwegian Deep is very different in terms of hosts and proposed life cycle patterns of A. simplex from other regions, involving only a few intermediate hosts. In contrast to earlier suggestions, euphausiids have no importance at all for the successful transmission of A. simplex in the Norwegian Deep. This

  8. On the Angular Correlation Functions of the Hubble Deep Field

    NASA Astrophysics Data System (ADS)

    Roukema, B. F.

    Roukema & Valls-Gabaud (1997, RVG) reinforce the conclusion of Colley et al. (1996, 1997) that the Hubble Deep Field (HDF) ``galaxies'' are probably star-forming regions, not ``building-blocks''. Consider a ``building-block'' hypothesis: (1) all (colour-selected high z) HDF galaxy-like objects are galaxies; (2) these objects have a spatial correlation function xi(r,z) = b2 (r0 / r)gamma (1+z)-(3+epsilon-gamma) where b >> 1 is a strong bias factor at high z; and b > = 1, db/dr < 0 for all r,z; such that the projection of xi (3-D) into w (angular correlation; 2-D) (via Limber's equation) matches Figs 1a, 1d of Colley et al. (1996). Since w(1 arcsecond) > approx 1 in Figs 1a,1d of Colley et al. (1996), at least 50% of the 1 arcsecond object pairs can be considered ``excess pairs''. Table 1 of RVG therefore shows, conservatively, that of all the 1 arcsecond object pairs, and under the above hypotheses, 25% are spatially separated by a median of only 3-7h-1 kpc (proper units), and 45% are spatially separated by a median of 12-30h-1 kpc$, taking into account projection effects. Many excess pairs have theta approx 0.25 arcseconds. Hence, for a pure ``building-block'' model, galaxy formation models would have to post-dict the existence of many Rhalo << 2 kpc, very highly biased galaxies, at 2.5 < z < 5. This result is little sensitive to epsilon, Omega0, lambda0 or zmedian.

  9. TADPOLE GALAXIES IN THE HUBBLE ULTRA DEEP FIELD

    SciTech Connect

    Elmegreen, Bruce G.; Elmegreen, Debra Meloy E-mail: elmegreen@vassar.ed

    2010-10-20

    Tadpole galaxies have a head-tail shape with a large clump of star formation at the head and a diffuse tail or streak of stars off to one side. We measured the head and tail masses, ages, surface brightnesses, and sizes for 66 tadpoles in the Hubble Ultra Deep Field (UDF) and looked at the distribution of neighbor densities and tadpole orientations with respect to neighbors. The heads have masses of 10{sup 7}-10{sup 8} M{sub sun} and photometric ages of {approx}0.1 Gyr for z {approx} 2. The tails have slightly larger masses than the heads and comparable or slightly older ages. The most obvious interpretation of tadpoles as young merger remnants is difficult to verify. They have no enhanced proximity to other resolved galaxies as a class, and the heads, typically <0.2 kpc in diameter, usually have no obvious double-core structure. Another possibility is ram pressure interaction between a gas-rich galaxy and a diffuse cosmological flow. Ram pressure can trigger star formation on one side of a galaxy disk, giving the tadpole shape when viewed edge-on. Ram pressure can also strip away gas from a galaxy and put it into a tail, which then forms new stars and gravitationally drags along old stars with it. Such an effect might have already been observed in the Virgo Cluster. Another possibility is that tadpoles are edge-on disks with large, off-center clumps. Analogous lop-sided star formation in UDF clump clusters is shown.

  10. The JWST North Ecliptic Pole Survey Field for Time-domain Studies

    NASA Astrophysics Data System (ADS)

    Jansen, Rolf A.; Alpaslan, Mehmet; Ashby, Matthew; Ashcraft, Teresa; Cohen, Seth H.; Condon, James J.; Conselice, Christopher; Ferrara, Andrea; Frye, Brenda L.; Grogin, Norman A.; Hammel, Heidi B.; Hathi, Nimish P.; Joshi, Bhavin; Kim, Duho; Koekemoer, Anton M.; Mechtley, Matt; Milam, Stefanie N.; Rodney, Steven A.; Rutkowski, Michael J.; Strolger, Louis-Gregory; Trujillo, Chadwick A.; Willmer, Christopher; Windhorst, Rogier A.; Yan, Haojing

    2017-01-01

    The JWST North Ecliptic Pole (NEP) Survey field is located within JWST's northern Continuous Viewing Zone, will span ˜14‧ in diameter (˜10‧ with NIRISS coverage) and will be roughly circular in shape (initially sampled during Cycle 1 at 4 distinct orientations with JWST/NIRCam's 4.4‧×2.2‧ FoV —the JWST “windmill”) and will have NIRISS slitless grism spectroscopy taken in parallel, overlapping an alternate NIRCam orientation. This is the only region in the sky where JWST can observe a clean extragalactic deep survey field (free of bright foreground stars and with low Galactic foreground extinction AV) at arbitrary cadence or at arbitrary orientation. This will crucially enable a wide range of new and exciting time-domain science, including high redshift transient searches and monitoring (e.g., SNe), variability studies from Active Galactic Nuclei to brown dwarf atmospheres, as well as proper motions of extreme scattered Kuiper Belt and Oort Cloud Objects, and of nearby Galactic brown dwarfs, low-mass stars, and ultracool white dwarfs. We therefore welcome and encourage follow-up through GO programs of the initial GTO observations to realize its potential as a JWST time-domain community field. The JWST NEP Survey field was selected from an analysis of WISE 3.4+4.6 micron, 2MASS JHKs, and SDSS ugriz source counts and of Galactic foreground extinction, and is one of very few such ˜10‧ fields that are devoid of sources brighter than mAB = 16 mag. We have secured deep (mAB ˜ 26 mag) wide-field (˜23‧×25‧) Ugrz images of this field and its surroundings with LBT/LBC. We also expect that deep MMT/MMIRS YJHK images, deep 8-12 GHz VLA radio observations (pending), and possibly HST ACS/WFC and WFC3/UVIS ultraviolet-visible images will be available before JWST launches in Oct 2018.

  11. The JWST North Ecliptic Pole Survey Field for Time-domain Studies

    NASA Astrophysics Data System (ADS)

    Jansen, Rolf A.; Webb Medium Deep Fields IDS GTO Team, the NEPTDS-VLA/VLBA Team, and the NEPTDS-Chandra Team

    2017-06-01

    The JWST North Ecliptic Pole (NEP) Survey field is located within JWST's northern Continuous Viewing Zone, will span ~14‧ in diameter (~10‧ with NIRISS coverage) and will be roughly circular in shape (initially sampled during Cycle 1 at 4 distinct orientations with JWST/NIRCam's 4.4‧×2.2‧ FoV —the JWST "windmill") and will have NIRISS slitless grism spectroscopy taken in parallel, overlapping an alternate NIRCam orientation. This is the only region in the sky where JWST can observe a clean extragalactic deep survey field (free of bright foreground stars and with low Galactic foreground extinction AV) at arbitrary cadence or at arbitrary orientation. This will crucially enable a wide range of new and exciting time-domain science, including high redshift transient searches and monitoring (e.g., SNe), variability studies from Active Galactic Nuclei to brown dwarf atmospheres, as well as proper motions of extreme scattered Kuiper Belt and Oort Cloud Objects, and of nearby Galactic brown dwarfs, low-mass stars, and ultracool white dwarfs. We therefore welcome and encourage follow-up through GO programs of the initial GTO observations to realize its potential as a JWST time-domain community field. The JWST NEP Survey field was selected from an analysis of WISE 3.4+4.6 μm, 2MASS JHKs, and SDSS ugriz source counts and of Galactic foreground extinction, and is one of very few such ~10‧ fields that are devoid of sources brighter than mAB = 16 mag. We have secured deep (mAB ~ 26 mag) wide-field (~23‧×25‧) Ugrz images of this field and its surroundings with LBT/LBC. We also expect that deep MMT/MMIRS YJHK images, deep 3-4.5 GHz VLA and VLBA radio observations, and possibly HST ACS/WFC and WFC3/UVIS ultraviolet-visible (pending) and Chandra/ACIS X-ray (pending) images will be available before JWST launches in Oct 2018.

  12. Microbial diversity in the deep-sea sediments of Iheya North and Iheya Ridge, Okinawa Trough.

    PubMed

    Zhang, Jian; Sun, Qing-lei; Zeng, Zhi-gang; Chen, Shuai; Sun, Li

    2015-08-01

    In this study, we analyzed the bacterial and archaeal diversities of the deep-sea sediments in Iheya North and Iheya Ridge, Okinawa Trough, using the high-throughput sequencing technology of Illumina MiSeq 2500 platform. Four samples (IN1, IN2, IR1 and IR2) were used in this study, of which IN1 and IN2 were located at regions close to and distant, respectively, from the active hydrothermal vents in Iheya North, while IR1 and IR2 were located at regions close to and distant, respectively, from the active hydrothermal vents in Iheya Ridge. The four samples were rich in different metal elements. Sequence analysis based on the V3-V4 regions of 16S rDNA gene obtained 170,363 taxon tags, including 122,920 bacterial tags and 47,433 archaeal tags, which cover 31 phyla, 50 classes, 59 orders, 87 families, and 138 genera. Overall, the microbial communities in all samples were dominated by bacteria, in which Proteobacteria was the largest phylum, followed by Chloroflexi, Firmicutes, Acidobacteria, Actinobacteria, Gemmatimonadetes, and Nitrospirae, which together accounted for 64.6% of the total taxon tags. In contrast to the high bacterial diversities, the archaeal diversity was low and dominated by Thaumarchaeota, which accounted for 22.9% of the total taxon tags. Comparative analysis showed that (i) IN2 and IR2 exhibited more microbial richness than IN1 and IR1, (ii) IR1 and IR2 exhibited higher microbial diversities than IN1 and IN2, (iii) samples from Iheya Ridge and Iheya North fell into two groups based on principle component analysis. Furthermore, microbes potentially involved in sulfur, nitrogen, and metal metabolism and cycling were detected in all samples. These results provide for the first time a comparative picture of the microbial diversities in the sediments of Iheya North and Iheya Ridge and indicate that geological features and distance from active hydrothermal vents likely play important roles in the shaping of microbial community structure. Copyright

  13. Deep HST imaging of distant weak radio and field galaxies

    NASA Technical Reports Server (NTRS)

    Windhorst, R. A.; Gordon, J. M.; Pascarelle, S. M.; Schmidtke, P. C.; Keel, W. C.; Burkey, J. M.; Dunlop, J. S.

    1994-01-01

    We present deep Hubble Space Telescope (HST) Wide-Field Camera (WFC) V- and I-band images of three distant weak radio galaxies with z = 0.311-2.390 and seven field galaxies with z = 0.131-0.58. The images were deconvolved with both the Lucy and multiresolution CLEAN methods, which yield a restoring Full Width at Half Maximum (FWHM) of less than or equal to 0.2 sec, (nearly) preserve photons and signal-to-noise ratio at low spatial frequencies, and produce consistent light profiles down to our 2 sigma surface brightness sensitivity limit of V approximately 27.2 and I approximately 25.9 mag/sq arcsec. Multi-component image modeling was used to provide deconvolution-independent estimates of structural parameters for symmetric galaxies. We present 12-band (m(sub 2750) UBVRIgriJHK) photometry for a subset of the galaxies and bootstrap the unknown FOC/48 zero point at 2750 A in three independent ways (yielding m(sub 2750) = 21.34 +/- 0.09 mag for 1.0 e(-)/s). Two radio galaxies with z = 0.311 and 0.528, as well as one field galaxy with z = 0.58, have the colors and spectra of early-type galaxies, and a(exp 1/4)-like light profiles in the HST images. The two at z greater than 0.5 have little or no color gradients in V - I and are likely giant ellipticals, while the z = 0.311 radio galaxy has a dim exponential disk and is likely an S0. Six of the seven field galaxies have light profiles that indicate (small) inner bulges following a(exp 1/4) laws and outer exponential disks, both with little or no color gradients. These are (early-type) spiral galaxies with z = 0.131-0.528. About half have faint companions or bars. One shows lumpy structure, possibly a merger. The compact narrow-line galaxy 53W002 at z = 2.390 has less than or = 30% +/- 10% of its HST V and I flux in the central kiloparsec (due to its weak Active Galactic Nucleus (AGN)). Most of its light (V approximately equal to 23.3) occurs in a symmetric envelope with a regular a(exp 1/4)-like profile of effective

  14. Variations of deep western boundary currents in the Melanesian Basin in the western North Pacific

    NASA Astrophysics Data System (ADS)

    Kawabe, Masaki; Yanagimoto, Daigo; Kitagawa, Shoji

    2006-06-01

    Five moorings ML1-ML5 were deployed on the slope of the Solomon Rise in the Melanesian Basin in the western North Pacific, northeastward at increasing water depths. We measured the velocities of the western branch current of the deep western boundary current (DWBC) and the upper deep current carrying the Lower and Upper Circumpolar Waters (LCPW, UCPW), respectively. The daily mean velocity data from 1-3 February 1999 to 24-26 February 2000 were analyzed, and variability of the DWBCs was clarified. Although the current meters did not entirely cover the western branch current of the DWBC composed of two or three streams, a stream of the western branch current was observed at a depth of 4700 m at ML4 or 4260 m at ML5 for more than half of the observation period. The stream had a mean velocity of 3.7 cm s -1 and alternated between ML4 and ML5 at 20- to 40-day intervals without occupying both of ML4 and ML5 simultaneously. This shows that the width of the stream is less than 120 km (distance between ML4 and ML5), and the position changes in a similar range. In contrast to the velocity of the eastern branch current of the DWBC, that of the western branch current did not decrease with decreasing depths to 4000 m. This reflects the vertical division into the branch currents by the bifurcation of the DWBC. The western branch current of the DWBC is located at the deep side of the countercurrent which was almost always observed at depths of 3880 and 4080 m at ML3. The countercurrent was thought to be the return flow of the western branch current that is partly reversed in the East Mariana Basin. The previous estimate of geostrophic transport of LCPW at the time of the mooring deployment was corrected to 1.4 Sv (10 6 m 3 s -1) in the western branch current, 1.7 Sv in the countercurrent, and 1.1 Sv in the inflow to the East Caroline Basin. The upper deep current was located over the slope of the Solomon Rise with water depth less than 4500 m including ML1-ML3. It flowed at

  15. Investigating completion strategies; Cormorant Field, U. K. North Sea

    SciTech Connect

    Stiles, J.H. Jr. ); Valenti, N.P. )

    1990-03-01

    This paper describes studies that evaluate various completion strategies for new subsea wells in the Cormorant field, U.K. North Sea. These studies, which complement work done by the field operator, include detailed reservoir description work to define oil-in-place (OIP) and permeability distribution and a waterflood simulation for a representative reservoir cross section. Wellbore, flowline, and pipeline hydraulics for the complex production/injection system are included to model well rates more accurately. The results provide general insight into the nature of displacement during waterflooding of a stratified section with a limited number of wells. They also provide specific guidance on dual vs. single completions; perforating, testing, and stimulation sequence; and the benefits of partially perforating high-permeability sands.

  16. DeepAnomaly: Combining Background Subtraction and Deep Learning for Detecting Obstacles and Anomalies in an Agricultural Field

    PubMed Central

    Christiansen, Peter; Nielsen, Lars N.; Steen, Kim A.; Jørgensen, Rasmus N.; Karstoft, Henrik

    2016-01-01

    Convolutional neural network (CNN)-based systems are increasingly used in autonomous vehicles for detecting obstacles. CNN-based object detection and per-pixel classification (semantic segmentation) algorithms are trained for detecting and classifying a predefined set of object types. These algorithms have difficulties in detecting distant and heavily occluded objects and are, by definition, not capable of detecting unknown object types or unusual scenarios. The visual characteristics of an agriculture field is homogeneous, and obstacles, like people, animals and other obstacles, occur rarely and are of distinct appearance compared to the field. This paper introduces DeepAnomaly, an algorithm combining deep learning and anomaly detection to exploit the homogenous characteristics of a field to perform anomaly detection. We demonstrate DeepAnomaly as a fast state-of-the-art detector for obstacles that are distant, heavily occluded and unknown. DeepAnomaly is compared to state-of-the-art obstacle detectors including “Faster R-CNN: Towards Real-Time Object Detection with Region Proposal Networks” (RCNN). In a human detector test case, we demonstrate that DeepAnomaly detects humans at longer ranges (45–90 m) than RCNN. RCNN has a similar performance at a short range (0–30 m). However, DeepAnomaly has much fewer model parameters and (182 ms/25 ms =) a 7.28-times faster processing time per image. Unlike most CNN-based methods, the high accuracy, the low computation time and the low memory footprint make it suitable for a real-time system running on a embedded GPU (Graphics Processing Unit). PMID:27845717

  17. DeepAnomaly: Combining Background Subtraction and Deep Learning for Detecting Obstacles and Anomalies in an Agricultural Field.

    PubMed

    Christiansen, Peter; Nielsen, Lars N; Steen, Kim A; Jørgensen, Rasmus N; Karstoft, Henrik

    2016-11-11

    Convolutional neural network (CNN)-based systems are increasingly used in autonomous vehicles for detecting obstacles. CNN-based object detection and per-pixel classification (semantic segmentation) algorithms are trained for detecting and classifying a predefined set of object types. These algorithms have difficulties in detecting distant and heavily occluded objects and are, by definition, not capable of detecting unknown object types or unusual scenarios. The visual characteristics of an agriculture field is homogeneous, and obstacles, like people, animals and other obstacles, occur rarely and are of distinct appearance compared to the field. This paper introduces DeepAnomaly, an algorithm combining deep learning and anomaly detection to exploit the homogenous characteristics of a field to perform anomaly detection. We demonstrate DeepAnomaly as a fast state-of-the-art detector for obstacles that are distant, heavily occluded and unknown. DeepAnomaly is compared to state-of-the-art obstacle detectors including "Faster R-CNN: Towards Real-Time Object Detection with Region Proposal Networks" (RCNN). In a human detector test case, we demonstrate that DeepAnomaly detects humans at longer ranges (45-90 m) than RCNN. RCNN has a similar performance at a short range (0-30 m). However, DeepAnomaly has much fewer model parameters and (182 ms/25 ms =) a 7.28-times faster processing time per image. Unlike most CNN-based methods, the high accuracy, the low computation time and the low memory footprint make it suitable for a real-time system running on a embedded GPU (Graphics Processing Unit).

  18. Holocene Instabilities of Deep Circulation in the North Atlantic Based on nd and PB Isotope Sedimentary Records

    NASA Astrophysics Data System (ADS)

    Fagel, N.

    2013-12-01

    Many studies revealed the variability of deep ocean circulation over glacial/interglacial cycles. Instabilities in Holocene circulation and deep water production have been documented in marine archives. Unstable deep-water conditions prior to the mid-Holocene optimum were attributed to remnants of ice-sheets. However the millenial variability in Atlantic circulation continued after the melting of the ice-sheets. The correlation between observed NADW disturbances and surface cooling events in Nordic Seas argued for a linkage between surface variability and deep water masses over the Holocene. Nd and Pb isotopic compositions of the clay-size fraction of Holocene sediments were analysed in deep North Atlantic cores to trace the particle provenance. The aims are to identify the origin of the particles driven by deep currents and reconstruct deep circulation changes over the Holocene. Radiogenic signatures can be used as indirect paleoceanographic tracers. In particular Nd and Pb isotopes constitute suitable tracers for the origin of deep sediments in the Labrador Sea. The approach has been demonstrated over different timescales on cores collected at the southern tip of Greenland. Their sediment compositions reflect variable contributions of mantel-derived distal sources from mid-Atlantic Ridge and crustal-derived proximal inputs from Canadian and Greenland margins. As distal inputs are supplied by deep current the sedimentary isotopic composition record the fingerprint of the particles carried by the current. Here we compare the results from the Labrador Sea with three cores retrieved in fracture zones; two of them are located in the Island Basin along the gyre of North Atlantic Deep Water, and the third core is located off the present deep circulation gyre in the Labrador Sea. Whereas sedimentary supplies in the Labrador Sea were derived from proximal sources, the geochemical mixing trends in the Iceland Basin samples indicate pronounced changes in the relative

  19. Nitrate supply from deep to near-surface waters of the North Pacific subtropical gyre.

    PubMed

    Johnson, Kenneth S; Riser, Stephen C; Karl, David M

    2010-06-24

    Concentrations of dissolved inorganic carbon (DIC) decrease in the surface mixed layers during spring and summer in most of the oligotrophic ocean. Mass balance calculations require that the missing DIC is converted into particulate carbon by photosynthesis. This DIC uptake represents one of the largest components of net community production in the world ocean. However, mixed-layer waters in these regions of the ocean typically contain negligible concentrations of plant nutrients such as nitrate and phosphate. Combined nutrient supply mechanisms including nitrogen fixation, diffusive transport and vertical entrainment are believed to be insufficient to supply the required nutrients for photosynthesis. The basin-scale potential for episodic nutrient transport by eddy events is unresolved. As a result, it is not understood how biologically mediated DIC uptake can be supported in the absence of nutrients. Here we report on high-resolution measurements of nitrate (NO(3)(-)) and oxygen (O(2)) concentration made over 21 months using a profiling float deployed near the Hawaii Ocean Time-series station in the North Pacific subtropical gyre. Our measurements demonstrate that as O(2) was produced and DIC was consumed over two annual cycles, a corresponding seasonal deficit in dissolved NO(3)(-) appeared in water at depths from 100 to 250 m. The deep-water deficit in NO(3)(-) was in near-stoichiometric balance with the fixed nitrogen exported to depth. Thus, when the water column from the surface to 250 m is considered as a whole, there is near equivalence between nutrient supply and demand. Short-lived transport events (<10 days) that connect deep stocks of nitrate to nutrient-poor surface waters were clearly present in 12 of the 127 vertical profiles.

  20. High-resolution and Deep Crustal Imaging Across The North Sicily Continental Margin (southern Tyrrhenian Sea)

    NASA Astrophysics Data System (ADS)

    Agate, M.; Bertotti, G.; Catalano, R.; Pepe, F.; Sulli, A.

    Three multichannel seismic reflection profiles across the North Sicily continental mar- gin have been reprocessed and interpreted. Data consist of an unpublished high pene- tration seismic profile (deep crust Italian CROP Project) and a high-resolution seismic line. These lines run in the NNE-SSW direction, from the Sicilian continental shelf to the Tyrrhenian abyssal plain (Marsili area), and are tied by a third, high penetration seismic line MS104 crossing the Sisifo High. The North Sicily continental margin represents the inner sector of the Sicilian-Maghrebian chain that is collapsed as con- sequence of extensional tectonics. The chain is formed by a tectonic wedge (12-15 km thick. It includes basinal Meso-Cenozoic carbonate units overthrusting carbonate platform rock units (Catalano et al., 2000). Presently, main culmination (e.g. Monte Solunto) and a number of tectonic depressions (e.g. Cefalù basin), filled by >1000 m thick Plio-Pleistocene sedimentary wedge, are observed along the investigated tran- sect. Seismic attributes and reflector pattern depicts a complex crustal structure. Be- tween the coast and the M. Solunto high, a transparent to diffractive band (assigned to the upper crust) is recognised above low frequency reflective layers (occurring be- tween 9 and 11 s/TWT) that dips towards the North. Their bottom can be correlated to the seismological (African?) Moho discontinuity which is (26 km deep in the Sicilian shelf (Scarascia et al., 1994). Beneath the Monte Solunto ridge, strongly deformed re- flectors occurring between 8 to 9.5 s/TWT (European lower crust?) overly the African (?) lower crust. The resulting geometry suggests underplating of the African crust respect to the European crust (?). The already deformed crustal edifice is dissected by a number of N-dipping normal faults that open extensional basins and are associ- ated with crustal thinning. The Plio-Pleistocene fill of the Cefalù basin can be subdi- vided into three subunits by

  1. Mitigating Groundwater Depletion in North China Plain with Cropping System that Alternate Deep and Shallow Rooted Crops

    PubMed Central

    Yang, Xiao-Lin; Chen, Yuan-Quan; Steenhuis, Tammo S.; Pacenka, Steven; Gao, Wang-Sheng; Ma, Li; Zhang, Min; Sui, Peng

    2017-01-01

    In the North China Plain, groundwater tables have been dropping at unsustainable rates of 1 m per year due to irrigation of a double cropping system of winter wheat and summer maize. To reverse the trend, we examined whether alternative crop rotations could save water. Moisture contents were measured weekly at 20 cm intervals in the top 180 cm of soil as part of a 12-year field experiment with four crop rotations: sweet potato→ cotton→ sweet potato→ winter wheat-summer maize (SpCSpWS, 4-year cycle); peanuts → winter wheat-summer maize (PWS, 2-year cycle); ryegrass–cotton→ peanuts→ winter wheat-summer maize (RCPWS, 3-year cycle); and winter wheat-summer maize (WS, each year). We found that, compared to WS, the SpCSpWS annual evapotranspiration was 28% lower, PWS was 19% lower and RCPWS was 14% lower. The yield per unit of water evaporated improved for wheat within any alternative rotation compared to WS, increasing up to 19%. Average soil moisture contents at the sowing date of wheat in the SpCSpWS, PWS, and RCPWS rotations were 7, 4, and 10% higher than WS, respectively. The advantage of alternative rotations was that a deep rooted crop of winter wheat reaching down to 180 cm followed shallow rooted crops (sweet potato and peanut drawing soil moisture from 0 to 120 cm). They benefited from the sequencing and vertical complementarity of soil moisture extraction. Thus, replacing the traditional crop rotation with cropping system that involves rotating with annual shallow rooted crops is promising for reducing groundwater depletion in the North China Plain. PMID:28642779

  2. A reservoir model for the Lower Cretaceous deep marine sandstones in the Maloy Fault Block area, Norwegian North Sea

    SciTech Connect

    Kloster, A.; Areklett, E.K.; Milton, N.

    1995-08-01

    The Maloy Fault Block area of the North Viking Graben forms a platform to the east of the Sogn Graben next to the coast of Norway. This area is characterized by an unusual and thick Lower Cretaceous section containing a number of discrete sandstone packages. Wells drilled elsewhere in the Norwegian North Sea are in contrast dominated by a relatively thin mud and marl dominated section in the Lower Cretaceous. Two wells in block 35/3 (the Agat field) encountered gas bearing sandstones of Albian age interpreted to represent deposition in a deep marine environment. An integrated sequence stratigraphic approach to the Lower Cretaceous stratigraphy in the Maloy Fault Block area has led to a new and more detailed understanding of controls on deposition in this area. This is based both on a regional dataset and good quality 3D seismic data. A Valanginian-Hauterivian relict slope/shelf system is present along the eastern basin margin. It formed a long-lasting topographic feature and in some areas was not onlapped until the Campanian time. A dramatic change in the basin configuration took place most likely in the Aptian time. This was initiated by erosion of the slope/shelf system which cut multiple huge canyons along the basin-margin. The canyons focused sediment input to the basin along discrete and mappable transport routes, some of which are controlled by erosion features inherited from the Late Jurassic. A complex history of deposition and filling followed. This was controlled by a constantly changing basin floor topography and left a complex pattern of partly constrained fan deposition.

  3. Deep subsurface life from North Pond: Enrichment, isolation, characterization and genomes of heterotrophic bacteria

    SciTech Connect

    Russell, Joseph A.; Leon-Zayas, Rosa; Wrighton, Kelly; Biddle, Jennifer F.

    2016-05-10

    Studies of subsurface microorganisms have yielded few environmentally relevant isolates for laboratory studies. In order to address this lack of cultivated microorganisms, we initiated several enrichments on sediment and underlying basalt samples from North Pond, a sediment basin ringed by basalt outcrops underlying an oligotrophic watercolumn west of the Mid-Atlantic Ridge at 22° N. In contrast to anoxic enrichments, growth was observed in aerobic, heterotrophic enrichments from sediment of IODP Hole U1382B at 4 and 68 m below seafloor (mbsf). These sediment depths, respectively, correspond to the fringes of oxygen penetration from overlying seawater in the top of the sediment column and upward migration of oxygen from oxic seawater from the basalt aquifer below the sediment. Here we report the enrichment, isolation, initial characterization and genomes of three isolated aerobic heterotrophs from North Pond sediments; an Arthrobacter species from 4 mbsf, and Paracoccus and Pseudomonas species from 68 mbsf. These cultivated bacteria are represented in the amplicon 16S rRNA gene libraries created from whole sediments, albeit at low (up to 2%) relative abundance. We provide genomic evidence from our isolates demonstrating that the Arthrobacter and Pseudomonas isolates have the potential to respire nitrate and oxygen, though dissimilatory nitrate reduction could not be confirmed in laboratory cultures. Furthermore, the cultures from this study represent members of abundant phyla, as determined by amplicon sequencing of environmental DNA extracts, and allow for further studies into geochemical factors impacting life in the deep subsurface.

  4. A view of the Mid-Pleistocene Transition from the deep North Pacific

    NASA Astrophysics Data System (ADS)

    Ford, H. L.; Haynes, L.; Hoenisch, B.; Raymo, M. E.

    2015-12-01

    During the Mid-Pleistocene Transition (MPT, ~900 kyrs ago), the climate system's glacial/interglacial pacing, as reflected in benthic δ18O, changed from a dominant periodicity of 41,000 to one of 100,000 kyr, without a comparable change in orbital forcing. Proposed changes in the climate system that accompanied or could help explain this transition include an increase in the northern hemisphere and/or Antarctic ice volume, thermohaline circulation reorganization, and atmospheric pCO2 drawdown. Here we reconstruct bottom water temperature and δ18O of seawater (δ18Oseawater) from Mg/Ca and d18O signatures of Uvigerina spp., and carbonate ion concentration ([CO32-]) from B/Ca values of Cibicidoides wuellerstorfi to evaluate changes in ice volume and deep ocean carbon storage. The study is based on North Pacific ODP Site 1208 (36.13°N, 158.20°W, 3350 m water depth) and covers Marine Isotope Stages (MIS) 26 to 19 (~780-970 kyr). Our high-resolution (~2 kyrs) bottom water temperature record is largely in agreement with the high-resolution record from South Pacific ODP Site 1123 (Elderfield et al., 2012). At MIS 22, Site 1123 shows an abrupt 0.5 per mil δ18Oseawater increase that persists during subsequent glacial periods, interpreted by Elderfield et al. as a step-wise increase in glacial ice volume in Antarctica. By contrast, our preliminary Site 1208 δ18Oseawater record exhibits a transient increase in glacial δ18Oseawater at MIS 22, but suggests no significant, permanent glacial ice volume growth occurred. Preliminary low-resolution B/Ca results indicate a gradual and large decrease in [CO32-] from MIS 25 to MIS 21 at Site 1208, which may have been caused by a marked increase in deep ocean carbon storage over the MPT. Based on our preliminary analyses, we propose that thermohaline reorganization during the MPT may have changed deep ocean carbon storage and contributed to pCO2 drawdown.

  5. Handheld deep ultraviolet emission device based on aluminum nitride quantum wells and graphene nanoneedle field emitters.

    PubMed

    Matsumoto, Takahiro; Iwayama, Sho; Saito, Takao; Kawakami, Yasuyuki; Kubo, Fumio; Amano, Hiroshi

    2012-10-22

    We report the successful fabrication of a compact deep ultraviolet emission device via a marriage of AlGaN quantum wells and graphene nanoneedle field electron emitters. The device demonstrated a 20-mW deep ultraviolet output power and an approximately 4% power efficiency. The performance of this device may lead toward the realization of an environmentally friendly, convenient and practical deep ultraviolet light source.

  6. Wide Field Imaging of the Hubble Deep Field-South Region III: Catalog

    NASA Technical Reports Server (NTRS)

    Palunas, Povilas; Collins, Nicholas R.; Gardner, Jonathan P.; Hill, Robert S.; Malumuth, Eliot M.; Rhodes, Jason; Teplitz, Harry I.; Woodgate, Bruce E.

    2002-01-01

    We present 1/2 square degree uBVRI imaging around the Hubble Deep Field - South. These data have been used in earlier papers to examine the QSO population and the evolution of the correlation function in the region around the HDF-S. The images were obtained with the Big Throughput Camera at CTIO in September 1998. The images reach 5 sigma limits of u approx. 24.4, B approx. 25.6, V approx. 25.3, R approx. 24.9 and I approx. 23.9. We present a catalog of approx. 22,000 galaxies. We also present number-magnitude counts and a comparison with other observations of the same field. The data presented here are available over the world wide web.

  7. Holocene eolian activity in the Minot dune field, North Dakota

    USGS Publications Warehouse

    Muhs, D.R.; Stafford, Thomas W.; Been, J.; Mahan, S.A.; Burdett, J.; Skipp, G.; Rowland, Z.M.

    1997-01-01

    Stabilized eolian sand is common over much of the Great Plains region of the United States and Canada, including a subhumid area of ??? 1500 km2 near Minot, North Dakota. Eolian landforms consist of sand sheets and northwest-trending parabolic dunes. Dunes and sand sheets in the Minot field are presently stabilized by a cover of prairie grasses or oak woodland. Stratigraphic studies and accelerator mass spectrometry radiocarbon dating of paleosols indicate at least two periods of eolian sand movement in the late Holocene. Pedologic data suggest that all of the dune field has experienced late Holocene dune activity, though not all parts of the dune field may have been active simultaneously. Similar immobile element (Ti, Zr, La, Ce) concentrations support the interpretation that eolian sands are derived from local glaciofluvial and glaciolacustrine sediments. However, glaciolacustrine and glaciofluvial source sediments have high Ca concentrations from carbonate minerals, whereas dune sands are depleted in Ca. Because noneolian-derived soils in the area are calcareous, these data indicate that the Minot dune field may have had extended periods of activity in the Holocene, such that eolian abrasion removed soft carbonate minerals. The southwest-facing parts of some presently stabilized dunes were active during the 1930s drought, but were revegetated during the wetter years of the 1940s. These observations indicate that severe droughts accompanied by high temperatures are the most likely cause of Holocene eolian activity.

  8. Revision of the biostratigraphy of the Chatham Group (Upper Triassic), Deep River basin, North Carolina, USA

    USGS Publications Warehouse

    Litwin, R.J.; Ash, S.R.

    1993-01-01

    Paleontological evidence from the Upper Triassic Chatham Group in the three subbasins of the Deep River basin (North Carolina, USA) supports a significant revision of the ages assigned to most of this non-marine continental sedimentary sequence. This study confirms an early(?) or mid-Carnian age in the Sanford subbasin for the base of the Pekin Formation, the lowest unit of the Chatham Group. However, diagnostic late Carnian palynomorphs have been recovered from coals in the lower part of the Cumnock Formation in the Sanford subbasin, and from a sample of the Cumnock Formation equivalent in the Wadesboro subbasin. Plant megafossils and fossil verebrates from rocks in the Sanford subbasin also support a late Carnian age for the Cumnock Formation and its equivalents. The overlying Sanford Formation, which has not yet been dated paleontologically, probably includes beds of Norian age, as over 1000 m of strata may be present between the Cumnock Formation coals (dated here as late Carnian) and the top of the Sanford Formation. This chronostratigraphic interval appears similar to, but slightly longer than, that preserved in the Dan River-Danville and Davie County basins 100 km to the northwest. Our evidence, therefore, indicates that the Chatham Group was deposited over a much longer time interval [early(?) to mid-Carnian through early Norian] than previously was believed. ?? 1993.

  9. Bathymetric patterns of morphological disparity in deep-sea gastropods from the western North Atlantic basin.

    PubMed

    McClain, Craig R

    2005-07-01

    Understanding patterns of species richness requires knowledge of the individual roles species play in community structure. Here, I use gastropod shells as a source of information about both their ecological and their evolutionary functions in generating bathymetric gradients of diversity. Specifically, morphological disparity of shell architecture in deep-sea gastropods is evaluated over a depth gradient in the western North Atlantic by constructing an empirical morphospace based on an eigenshape analysis. Morphological disparity is quantified by calculating the centroid, total range, and dispersion of the morphospace at each station along the depth gradient. The results indicate that local faunas are drawn from a regional pool with the same variance but that average dissimilarity in forms reflects the number of species in the sample. The range of the morphospace at local scales is also less than at regional scales, resulting from the variability of the morphospace centroid over depth. Although the position of the morphospace changes with depth, morphological disparity remains unaffected. Despite the lack of bathymetric patterns in variance, patterns in nearest neighbor distance persist. The findings suggest the importance of interacting ecological and evolutionary processes at varying spatiotemporal scales for both morphological disparity and species richness.

  10. Linking Deep-Waer Prey Fields with Odontocete Population Structure and Behavior

    DTIC Science & Technology

    2015-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Linking deep -water prey fields with odontocete population...column to examine the coherence between surface and deep -water prey characteristics • Examine the relationship between historical beaked whale...ground- truthed with net tows. Beaked whale habitat use was quantified using a combination of synoptic visual observations from the ship and

  11. Map showing a deep-tow geophysical study of the north end of the San Clemente Fault, California Borderland

    USGS Publications Warehouse

    Ford, George A.; Normark, William R.

    1980-01-01

    A deep-tow geophysical study of a small ridge along the north end of the San Clemente fault, informally termed Kimki Ridge by Arne Junger and J.G. Vedder (unpub. data, 1979), was conducted in April 1976 using the R/V Melville of the Scripps Institution of Oceanography. The purpose of the survey was to search for evidence of active faulting along the north-ward extension of the San Clemente fault, a major structural feature in the California Borderland (fig. 1). 

  12. Deep formation waters of Western Europe, Russia and North America characterised by sodium, calcium, magnesium and chloride concentrations

    NASA Astrophysics Data System (ADS)

    Bozau, Elke; Hemme, Christina; Sattler, Carl-Diedrich; van Berk, Wolfgang

    2015-04-01

    Deep formation water can be classified according to depth, temperature, and salinity (e.g., Graf et al. 1966, Kharaka & Hanor 2007). Most of the deep formation waters contain dissolved solids in excess of sea water. The hydrogeochemical development of formation water has been discussed for a long time. It is widely accepted that deep aquifers are influenced by the meteoric cycle and geochemical processes within the crust (e.g., Hebig et al. 2012). Similar hydrogeochemical signatures are found in deep formation waters of all continents and can be explained by general geochemical processes within the deep reservoirs (e.g., Land 1995). Therefore, data of deep formation waters from Western Europe, Russia, and North America are collected and classified by the major water components. The data are used to identify important hydrogeochemical processes (e.g., halite dissolution and albitisation) leading to different compositions of formation water. Two significant water types are identified: Na-Cl water and Na-Ca-Cl water. Based on the collected hydrogeochemical data, development trends are stated for the formation waters, and albitisation is favoured as the main process for calcium enrichment. Furthermore, differences of formation water according to stratigraphical units are shown for deep reservoirs of the North German Basin and the North Sea. References: Graf, D.L., 1982. Chemical osmosis, reverse chemical osmosis, and the origin of subsurface brines. Geochimica Cosmochimica Acta 46, 1431-1448. Hebig, K.H., Ito, N., Scheytt, T., Marui, A., 2012. Review: Deep groundwater research with focus on Germany. Hydrogeology Journal 20, 227-243. Kharaka, Y.K., Hanor, J.S., 2007. Deep fluids in continents: I. Sedimentary Basins. Treatise on Geochemistry 5, 1-48. Land, L.S., 1995. The role of saline formation water in the crustal cycling. Aquatic Geochemistry 1, 137-145. Acknowledgements: The presented data are results of the collaborative research program "gebo" (Geothermal energy

  13. The Evolution of Faint Field Galaxies: Implications from the Hubble Deep Field

    NASA Astrophysics Data System (ADS)

    Gronwall, C.

    1996-12-01

    The Hubble Deep Field (HDF) is a four square arcminute area of the sky imaged for ten consecutive days with the Hubble Space Telescope. It is the deepest optical imaging survey of field galaxies in existence, reaching ~ 2-3 mag fainter than the deepest ground-based observations. In addition to its unprecedented depth, the spatial resolution of the HDF enables the measurement of structural and morphological parameters for an extremely faint sample of galaxies. We (see Gronwall & Koo 1995) have developed a modeling technique which differs from previous work by adopting the very simple assumption that the local galaxy luminosity function and galaxy mix are not well-defined. Instead, we use a non-negative least squares fitting technique to derive a set of best-fitting local luminosity functions for different galaxy spectral types. By only including traditional luminosity evolution (i.e., the photometric evolution of stars over time given reasonable assumptions of the star formation history of various galaxy types), plus the addition of galaxy reddening, we are able to fit the observed optical and near-IR galaxy counts, B-R colors, and redshifts of faint field galaxies extremely well to B ~ 25. We present the extension of the obove modeling technique to the multicolor photometric information and structural parameters (in particular, angular sizes) provided by the HDF. Our newst models also include additional evolutionary components -- merging and starbursting -- to try to constrain the relative importances of different forms of evolution in faint field galaxies.

  14. Snapshots from deep magma chambers: decoding field observations

    NASA Astrophysics Data System (ADS)

    De Campos, Cristina P.

    2014-05-01

    mingling, between contrasting magmas generated from different sources and depths. When flow patterns from these plutonic structures are compared to those obtained from experiments and numerical modeling, vortex-like systems may be locally recognized with chaotic regions among concentric regular flow cells, separated by major flow shearing zones. These patterns may be in remarkable good agreement with less complex flow patterns obtained for simpler dynamic systems. Differences in the magma supply and flow regimes between distinct plutons, in time and space, depict frozen moments in their evolution and therefore may explain some of the discrepancies in the different hybridization degrees for different complexes. The combination of detailed mapping of flow patterns in the field, numerical modeling and experimental results using natural magmatic products as end-members may provide new insights into the dynamics of magma chambers, specially for shallow chambers in a volcanic environment. Due to high viscosities and non-Newtonian behavior during a long time-interval, the application of fluid dynamics to understanding magmatic processes, especially those taking place in the deep crust, is still a major challenge to Geosciences. Extrapolation for plutonic environments remains therefore a great defiance. This discussion aims to show that it is nevertheless worthwhile.

  15. [Evapotranspiration of winter wheat field in North China Plain].

    PubMed

    Guo, Jiaxuan; Li, Yuzhong; Yan, Chang-Rong; Zhao, Quansheng; Mei, Xurong

    2006-12-01

    By using eddy covariance and remote sensing techniques, the relationships between winter wheat soil moisture content and farmland evapotranspiration or canopy temperature were analyzed at field scale under various environmental conditions in the North China Plain. The results showed that when the soil moisture content was below 65% of field capacity, the evaporative fraction under full canopy was low and stable during the middle part of clear days. Under clear sky condition, there was a good non-linear correlation between latent heat flux and crop canopy temperature with diurnal and seasonal patterns. The temperature difference between crop canopy and air as well as the relative evapotranspiration had a close link to the relative moisture content of 0 - 100 cm soil layer. Based on the in situ measurements of daily evapotranspiration amount (ET(d)), daily net radiation flux (Rn(d), mm), average canopy temperature (T(e), degrees C) from 13 : 30 to 14: 00, and daily maximum air temperature (T(a max), degrees C) during the field experiment, the parameters of simplified estimation model for daily evapotranspiration were established.

  16. Archaeoglobus fulgidus Isolated from Hot North Sea Oil Field Waters

    PubMed Central

    Beeder, Janiche; Nilsen, Roald Kåre; Rosnes, Jan Thomas; Torsvik, Terje; Lien, Torleiv

    1994-01-01

    A hyperthermophilic sulfate reducer, strain 7324, was isolated from hot (75°C) oil field waters from an oil production platform in the Norwegian sector of the North Sea. It was enriched on a complex medium and isolated on lactate with sulfate. The cells were nonmotile, irregular coccoid to disc shaped, and 0.3 to 1.0 μm wide. The temperature for growth was between 60 and 85°C with an optimum of 76°C. Lactate, pyruvate, and valerate plus H2 were utilized as carbon and energy sources with sulfate as electron acceptor. Lactate was completely oxidized to CO2. The cells contained an active carbon monoxide dehydrogenase but no 2-oxoglutarate dehydrogenase activity, indicating that lactate was oxidized to CO2 via the acetyl coenzyme A/carbon monoxide dehydrogenase pathway. The cells produced small amounts of methane simultaneously with sulfate reduction. F420 was detected in the cells which showed a blue-green fluorescence at 420 nm. On the basis of morphological, physiological, and serological features, the isolate was classified as an Archaeoglobus sp. Strain 7324 showed 100% DNA-DNA homology with A. fulgidus Z, indicating that it belongs to the species A. fulgidus. Archaeoglobus sp. has been selectively enriched and immunomagnetically captured from oil field waters from three different platforms in the North Sea. Our results show that strain 7324 may grow in oil reservoirs at 70 to 85°C and contribute to hydrogen sulfide formation in this environment. Images PMID:16349231

  17. X-ray observations of dust obscured galaxies in the Chandra deep field south

    NASA Astrophysics Data System (ADS)

    Corral, A.; Georgantopoulos, I.; Comastri, A.; Ranalli, P.; Akylas, A.; Salvato, M.; Lanzuisi, G.; Vignali, C.; Koutoulidis, L.

    2016-08-01

    We present the properties of X-ray detected dust obscured galaxies (DOGs) in the Chandra deep field south. In recent years, it has been proposed that a significant percentage of the elusive Compton-thick (CT) active galactic nuclei (AGN) could be hidden among DOGs. This type of galaxy is characterized by a very high infrared (IR) to optical flux ratio (f24 μm/fR > 1000), which in the case of CT AGN could be due to the suppression of AGN emission by absorption and its subsequent re-emission in the IR. The most reliable way of confirming the CT nature of an AGN is by X-ray spectroscopy. In a previous work, we presented the properties of X-ray detected DOGs by making use of the deepest X-ray observations available at that time, the 2Ms observations of the Chandra deep fields, the Chandra deep field north (CDF-N), and the Chandra deep field south (CDF-S). In that work, we only found a moderate percentage (<50%) of CT AGN among the DOGs sample. However, we pointed out that the limited photon statistics for most of the sources in the sample did not allow us to strongly constrain this number. In this paper, we further explore the properties of the sample of DOGs in the CDF-S presented in that work by using not only a deeper 6Ms Chandra survey of the CDF-S, but also by combining these data with the 3Ms XMM-Newton survey of the CDF-S. We also take advantage of the great coverage of the CDF-S region from the UV to the far-IR to fit the spectral energy distributions (SEDs) of our sources. Out of the 14 AGN composing our sample, 9 are highly absorbed (NH > 1023 cm-2), whereas 2 look unabsorbed, and the other 3 are only moderately absorbed. Among the highly absorbed AGN, we find that only three could be considered CT AGN. In only one of these three cases, we detect a strong Fe Kα emission line; the source is already classified as a CT AGN with Chandra data in a previous work. Here we confirm its CT nature by combining Chandra and XMM-Newton data. For the other two CT

  18. Properties of Dust Obscured Galaxies in the Nep-Deep Field

    NASA Astrophysics Data System (ADS)

    Oi, Nagisa; Matsuhara, Hideo; Pearson, Chris; Buat, Veronique; Burgarella, Denis; Malkan, Matt; Miyaji, Takamitsu; AKARI-NEP Team

    2017-03-01

    We selected 47 DOGs at z∼1.5 using optical R (or r^{'}), AKARI 18 μm, and 24 μm color in the AKARI North Ecliptic Pole (NEP) Deep survey field. Using the colors among 3, 4, 7, and 9μm, we classified them into 3 groups; bump DOGs (23 sources), power-law DOGs (16 sources), and unknown DOGs (8 sources). We built spectral energy distributions (SEDs) with optical to far-infrared photometric data and investigated their properties using SED fitting method. We found that AGN activity such as a AGN contribution to the infrared luminosity and a Chandra detection rate for bump and power-law DOGs are significantly different, while stellar component properties like a stellar mass and a star-formation rate are similar to each other. A specific star-formation rate range of power-law DOGs is slightly higher than that of bump DOGs with wide overlap. Herschel/PACS detection rates are almost the same between bump and power-law DOGs. On the other hand SPIRE detection rates show large differences between bump and power-law DOGs. These results might be explained by differences in dust temperatures. Both groups of DOGs host hot and/or warm dust (∼ 50 Kelvin), and many bump DOGs contain cooler dust (≤ 30 Kelvin)

  19. Clustering of the AKARI NEP Deep Field mid infrared selected galaxies

    NASA Astrophysics Data System (ADS)

    Solarz, Aleksandra; Pollo, Agnieszka; Takeuchi, Tsutomu T.; Małek, Katarzyna

    2016-06-01

    We present a method of selection of 24 μm galaxies from the AKARI North Ecliptic Pole (NEP) Deep Field and measurements of their two-point correlation function. We aim to associate different 24 μm selected galaxy populations with present day galaxies, and to investigate the impact of their environment on the direction of their subsequent evolution. We discuss the use of Support Vector Machines (SVM) algorithms applied to infrared photometric data to perform star-galaxy separation, in which we achieve an accuracy > 80%. We explore the redshift dependance of the correlation function parameters as well as the linear bias evolution (which relates galaxy distribution to the one of the underlying dark matter). We find that the bias parameter increases slowly with redshift, from b = 0.9 at z < 0.5 to b ˜ 1.9 at z ˜ 1.1. Total infrared luminosities (L_{TIR}) found for different samples, suggest that galaxies with higher L_{TIR} do not necessarily reside in higher mass dark matter halos. We find that luminous infrared galaxies (LIRGs) at z˜1 can be ancestors of present day L_{*} early type galaxies.

  20. A sub-millimetre survey of dust enshrouded galaxies in the Hubble Deep Field region

    NASA Astrophysics Data System (ADS)

    Borys, Colin James Kelvin

    This thesis investigates the emission of sub-millimetre- wave radiation from galaxies in the Hubble Deep Field North region. The data were obtained from dedicated observing runs from our group and others using the SCUBA camera on the James Clerk Maxwell Telescope. The data were combined using techniques specifically developed here for low signal-to-noise source recovery. The sources found represent over 10% of all cosmological sources SCUBA has detected since it was commissioned. The number of sub-mm galaxies we detect account for a significant fraction of the sub-mm back-ground, and we show that mild extrapolations can reproduce it entirely. We comment on their clustering properties, both with themselves and other high-redshift galaxy types. A multi-wavelength analysis of these galaxies shows that SCUBA sources do not all have similar properties, and are made of a collection including: star-forming radio galaxies; optically invisible objects; active galactic nuclei; and extremely red objects. Reasonable attempts to determine the redshift distribution of the sample show that SCUBA galaxies have a median redshift of around 2, and suggest that the global star formation rate may be dominated by such objects at redshifts beyond about 1. The thesis summarises the current state of extra-galactic sub-mm astronomy, and comments on how new surveys and detectors will allow us to place stronger constraints on the evolution properties of the high-redshift Universe.

  1. MONA LISA - Deep seismic investigations of the lithosphere in the southeastern North Sea

    NASA Astrophysics Data System (ADS)

    MONA LISA Working Group

    1997-01-01

    The MONA LISA collaborative project has collected 1112 km of seismic normal-incidence reflection data (recorded to 26 s) and wide-angle data from 26 onshore and 2 offshore locations along 4 profiles in the southeastern North Sea. The seismic data clearly image structures in the crust and uppermost mantle that may be related to Caledonian collision and Late Palaeozoic to Mesozoic rifting and basin formation. For the first time, dipping and subhorizontal reflections from the mantle have been observed to 24 s twt in seismic normal-incidence reflection sections. Strong sub-horizontal reflections are observed on two perpendicular profiles at c. 21 s twt, which is near the base of the lithosphere. These deep reflections are sharper than expected from a thermal-rheological transition suggesting that they are generated at lithological or tectonic interfaces. The Moho is reflective along all four profiles. Particularly strong and sharp normal-incidence and wide-angle reflections were recorded from the Moho south of the Caledonian Deformation Front. The normal-incidence reflection sections show unusually low intra-crustal reflectivity. Lower crustal, subhorizontal reflectivity is only observed west of the Central Graben and in a short profile segment at the base of the interpreted Caledonian Deformation Front. The crustal suture between Avalonia and Baltica is interpreted to be south- to west-dipping. SSW- and N-dipping reflections to 20 s twt are observed from the uppermost mantle. Two models of Tornquist Sea subduction may explain these events: either southward subduction and later extensional reactivation or northward subduction with later extension along a SSW-dipping shear zone. The crust is c. 5 km thinner below the Central Graben than below the surrounding parts of the Mid North Sea-Ringkøbing-Fyn High. The lower crust is reflective on the western flank of the Central Graben. East-dipping reflections from the lower crust and the upper mantle to the east of the graben

  2. Developments in deep brain stimulation using time dependent magnetic fields

    SciTech Connect

    Crowther, L.J.; Nlebedim, I.C.; Jiles, D.C.

    2012-03-07

    The effect of head model complexity upon the strength of field in different brain regions for transcranial magnetic stimulation (TMS) has been investigated. Experimental measurements were used to verify the validity of magnetic field calculations and induced electric field calculations for three 3D human head models of varying complexity. Results show the inability for simplified head models to accurately determine the site of high fields that lead to neuronal stimulation and highlight the necessity for realistic head modeling for TMS applications.

  3. Hydrocarbon emissions in the Bakken oil field in North Dakota

    NASA Astrophysics Data System (ADS)

    Mielke-Maday, I.; Petron, G.; Miller, B.; Frost, G. J.; Peischl, J.; Kort, E. A.; Smith, M. L.; Karion, A.; Dlugokencky, E. J.; Montzka, S. A.; Sweeney, C.; Ryerson, T. B.; Tans, P. P.; Schnell, R. C.

    2014-12-01

    Within the past five years, the production of oil and natural gas in the United States from tight formations has increased rapidly due to advances in technology, such as horizontal drilling and hydraulic fracturing. With the expansion of oil and natural gas extraction operations comes the need to better quantify their emissions and potential impacts on climate forcing and air quality. The Bakken formation within the Williston Basin in North Dakota has emerged as a large contributor to the recent growth in oil production and accounts for over 10% of domestic production. Close to 30% of associated gas co-produced with the oil is flared. Very little independent information is currently available to assess the oil and gas industry emissions and their impacts on regional air quality. In May 2014, an airborne field campaign was conducted by the National Oceanic and Atmospheric Administration's (NOAA) Earth System Research Laboratory and the University of Michigan to investigate hydrocarbon emissions from operations in the oil field. Here, we present results from the analysis for methane, several non-methane hydrocarbons and combustion tracers in 72 discrete air samples collected by the aircraft on nine different flights. Samples were obtained in the boundary layer upwind and downwind of the operations and in the free troposphere. We will show results of a multiple species analysis and compare them with field campaign data from other U.S. oil and gas fields, measurements from NOAA's Global Monitoring Division long-term observing network, and available bottom-up information on emissions from oil and gas operations.

  4. Geophysical constraints on the deep structure of a limited ocean-continent subduction zone at the North Iberian Margin

    NASA Astrophysics Data System (ADS)

    Ayarza, P.; MartíNez CataláN, J. R.; Alvarez-Marrón, J.; Zeyen, H.; Juhlin, C.

    2004-02-01

    Late Cretaceous to Cenozoic convergence between Iberia and Europe led to the partial closure of the Bay of Biscay with limited southward subduction of oceanic crust below the North Iberian Margin. Inclined sub-Moho reflections and diffractions observed in deep seismic reflection profiles shot across the margin are especially well represented in two reflection profiles: ESCIN-3.2 and ESCIN-3.3. These two profiles have been chosen to test if the sub-Moho reflections correspond to true primary deep events and, provided that they are reflecting off the subduction zone, to investigate its deep structure. Spectral analysis together with travel time estimation and migration allow us to characterize a number of these sub-Moho events as deep-source, low-frequency (˜19 Hz), reflections and diffractions. Synthetic seismograms were generated by three-dimensional seismic modeling of a sub-Moho southward dipping surface, interpreted to correspond to the top of subducted oceanic crust. Comparison between the real and synthetic data show that inclined, low-frequency sub-Moho reflections in both, ESCIN-3.2 and ESCIN-3.3 profiles may correspond to reflections from southward subducted Bay of Biscay oceanic crust. Geoid, free-air gravity, and absolute topography modeling provides additional constraints on the lithospheric-scale structure of this limited ocean-continent subduction zone beneath the North Iberian Margin.

  5. Target-oriented Marchenko imaging of a North Sea field

    NASA Astrophysics Data System (ADS)

    Ravasi, Matteo; Vasconcelos, Ivan; Kritski, Alexander; Curtis, Andrew; Filho, Carlos Alberto da Costa; Meles, Giovanni Angelo

    2016-04-01

    Seismic imaging provides much of our information about the Earth's crustal structure. The principal source of imaging errors derives from simplicistically modeled predictions of the complex, scattered wavefields that interact with each subsurface point to be imaged. A new method of wavefield extrapolation based on inverse scattering theory produces accurate estimates of these subsurface scattered wavefields, while still using relatively little information about the Earth's properties. We use it for the first time to create real target-oriented seismic images of a North Sea field. We synthesize underside illumination from surface reflection data, and use it to reveal subsurface features that are not present in an image from conventional migration of surface data. To reconstruct underside reflections, we rely on the so-called downgoing focusing function, whose coda consists entirely of transmission-born multiple scattering. As such, we provide the first field data example of reconstructing underside reflections with contributions from transmitted multiples, without the need to first locate or image any reflectors in order to reconstruct multiple scattering effects.

  6. Hydrocarbon Source Rocks in the Deep River and Dan River Triassic Basins, North Carolina

    USGS Publications Warehouse

    Reid, Jeffrey C.; Milici, Robert C.

    2008-01-01

    This report presents an interpretation of the hydrocarbon source rock potential of the Triassic sedimentary rocks of the Deep River and Dan River basins, North Carolina, based on previously unpublished organic geochemistry data. The organic geochemical data, 87 samples from 28 drill holes, are from the Sanford sub-basin (Cumnock Formation) of the Deep River basin, and from the Dan River basin (Cow Branch Formation). The available organic geochemical data are biased, however, because many of the samples collected for analyses by industry were from drill holes that contained intrusive diabase dikes, sills, and sheets of early Mesozoic age. These intrusive rocks heated and metamorphosed the surrounding sediments and organic matter in the black shale and coal bed source rocks and, thus, masked the source rock potential that they would have had in an unaltered state. In places, heat from the intrusives generated over-mature vitrinite reflectance (%Ro) profiles and metamorphosed the coals to semi-anthracite, anthracite, and coke. The maximum burial depth of these coal beds is unknown, and depth of burial may also have contributed to elevated thermal maturation profiles. The organic geochemistry data show that potential source rocks exist in the Sanford sub-basin and Dan River basin and that the sediments are gas prone rather than oil prone, although both types of hydrocarbons were generated. Total organic carbon (TOC) data for 56 of the samples are greater than the conservative 1.4% TOC threshold necessary for hydrocarbon expulsion. Both the Cow Branch Formation (Dan River basin) and the Cumnock Formation (Deep River basin, Sanford sub-basin) contain potential source rocks for oil, but they are more likely to have yielded natural gas. The organic material in these formations was derived primarily from terrestrial Type III woody (coaly) material and secondarily from lacustrine Type I (algal) material. Both the thermal alteration index (TAI) and vitrinite reflectance data

  7. Nitrogen cycling in the deep sedimentary biosphere: nitrate isotopes in porewaters underlying the oligotrophic North Atlantic

    NASA Astrophysics Data System (ADS)

    Wankel, S. D.; Buchwald, C.; Ziebis, W.; Wenk, C. B.; Lehmann, M. F.

    2015-12-01

    Nitrogen (N) is a key component of fundamental biomolecules. Hence, its cycling and availability are central factors governing the extent of ecosystems across the Earth. In the organic-lean sediment porewaters underlying the oligotrophic ocean, where low levels of microbial activity persist despite limited organic matter delivery from overlying water, the extent and modes of nitrogen transformations have not been widely investigated. Here we use the N and oxygen (O) isotopic composition of porewater nitrate (NO3-) from a site in the oligotrophic North Atlantic (Integrated Ocean Drilling Program - IODP) to determine the extent and magnitude of microbial nitrate production (via nitrification) and consumption (via denitrification). We find that NO3- accumulates far above bottom seawater concentrations (~ 21 μM) throughout the sediment column (up to ~ 50 μM) down to the oceanic basement as deep as 90 m b.s.f. (below sea floor), reflecting the predominance of aerobic nitrification/remineralization within the deep marine sediments. Large changes in the δ15N and δ18O of nitrate, however, reveal variable influence of nitrate respiration across the three sites. We use an inverse porewater diffusion-reaction model, constrained by the N and O isotope systematics of nitrification and denitrification and the porewater NO3- isotopic composition, to estimate rates of nitrification and denitrification throughout the sediment column. Results indicate variability of reaction rates across and within the three boreholes that are generally consistent with the differential distribution of dissolved oxygen at this site, though not necessarily with the canonical view of how redox thresholds separate nitrate regeneration from dissimilative consumption spatially. That is, we provide stable isotopic evidence for expanded zones of co-occurring nitrification and denitrification. The isotope biogeochemical modeling also yielded estimates for the δ15N and δ18O of newly produced nitrate (

  8. Circulation and north atlantic deep water formation rates based on evolution of the cfc signal in the north atlantic ocean

    NASA Astrophysics Data System (ADS)

    Smethie, W.; Lebel, D.

    2003-04-01

    The first high quality CFC measurements in the North Atlantic were made in 1981 as part of the TTO program. The WOCE survey in 1996-1998 provided the first synoptic CFC survey of the entire North Atlantic, but CFC measurements were made throughout the North Atlantic on a non-synoptic basis prior to WOCE. The pre-WOCE and WOCE CFC data sets will be compared on a regional basis using maps of concentrations on neutral density surfaces, maps of CFC-11 inventories, and plots of CFCs verses potential temperature for the major components of NADW. Circulation patterns and time scales inferred from the CFC distributions will be presented. The CFC inventories reflect the formation rate of a given water mass and formation rates calculated from the CFC inventories will be presented and compared for pre-WOCE and WOCE data.

  9. Pliocene (3.2-2.4 Ma) ostracode faunal cycles and deep ocean circulation, North Atlantic Ocean

    USGS Publications Warehouse

    Cronin, T. M.; Raymo, M.E.; Kyle, K.P.

    1996-01-01

    Ostracode assemblages from Deep Sea Drilling Project Sites 607 (western Mid-Atlantic Ridge) and 610 (southeast Rockall Plateau) show rapid, systematic shifts during late Pliocene glacial-interglacial cycles that reflect deep-sea environmental change. Progressive decreases in North Atlantic deep-water taxa and increases in Southern Ocean taxa occur from 3.4 to 2.4 Ma, and high-amplitude faunal cycles begin near 2.8 Ma. Four ostracode assemblages, each with a characteristic phase relative to 41 k.y. obliquity glacial-interglacial ??18O cycles, characterize the benthic faunal record at Site 607. Cross-spectral analysis shows that the Site 607 glacial assemblage has a 41 k.y. periodicity significant at the 95% level; other assemblages show a less significant, but still obvious, concentration of variance at 41 k.y. Faunal patterns suggest climatically controlled reorganization of deep-sea benthic communities during glacial-interglacial cycles due to oscillating deep-sea environments.

  10. Current-mode deep level transient spectroscopy of a semiconductor nanowire field-effect transistor

    NASA Astrophysics Data System (ADS)

    Isakov, Ivan; Sourribes, Marion J. L.; Warburton, Paul A.

    2017-09-01

    One of the main limiting factors in the carrier mobility in semiconductor nanowires is the presence of deep trap levels. While deep-level transient spectroscopy (DLTS) has proved to be a powerful tool in analysing traps in bulk semiconductors, this technique is ineffective for the characterisation of nanowires due to their very small capacitance. Here, we introduce a new technique for measuring the spectrum of deep traps in nanowires. In current-mode DLTS ("I-DLTS"), the temperature-dependence of the transient current through a nanowire field-effect transistor in response to an applied gate voltage pulse is measured. We demonstrate the applicability of I-DLTS to determine the activation energy and capture cross-sections of several deep defect states in zinc oxide nanowires. In addition to characterising deep defect states, we show that I-DLTS can be used to measure the surface barrier height in semiconductor nanowires.

  11. Soft sediment deformation associated with the passage of North Atlantic Deep water through the deep Ariel Graben, Mozambique Ridge southwest Indian Ocean.

    NASA Astrophysics Data System (ADS)

    Wiles, Errol; Green, Andrew; Watkeys, Mike; Jokat, Wilfried; Krocker, Ralph

    2014-05-01

    Interactions between bottom water currents and seafloor sediments are well known. Bottom current generated bedforms are varied both morphologicaly and sedimentologicaly. Sediment transport and deposition, associated with bottom water circulation, plays a significant role is sculpting seafloor morphology in all ocean basins. Indeed, bedforms have been used to great effect to define the presence, direction and strength of bottom water circulation globally. Here we present new multibeam swath bathymetry and high frequency seismic data from the Natal Valley and Mozambique Ridge, southwest Indian Ocean. These data show a deep (-3200 m) channel-like feature (Ariel Graben, situated at 28° 30"S on the Mozambique Ridge) connecting the northern Natal Valley to the Mozambique Basin. A distinct W - E change in seafloor morphology and seismic character is noted moving from the Natal Valley through the Ariel Graben. The northern flank of the graben exhibits smooth plastered drifts which give way to undulating seafloor in the east. The plastered drifts are characterised by distinct bottom echoes, with several discontinuous sub-bottom reflections. In contrast, the undulating seafloor is characterised by distinct hyperbolic echoes, with occasional indistinct sub-bottom reflectors. The W - E orientated undulations are straight crested, parallel / sub-parallel to the local isobaths. Wavelength is variable, ranging from 600 m to 1200 m. Cross-sectional symmetry of these features varies from symmetrical to asymmetrical, with board crests and narrow troughs. When asymmetrical, the lower (south-facing) limb is the longer (511.76 m average) than the upper (north-facing) limb (323.53 m average). The lower limbs are also steeper than the upper limbs; calculated averages being 3.80° and 1.55°, respectively. Overall, the slope on which the undulations are found, is south-facing with a gradient of 1.54°, however, the area affected by undulations is slightly steeper (average slope of 1.75

  12. APL-UW Deep Water Propagation: Philippine Sea Signal Physics and North Pacific Ambient Noise

    DTIC Science & Technology

    2015-10-15

    DISTRIBUTION STATEMENT A: Approved for public release: distribution is unlimited APL-UW Deep Water Propagation: Philippine Sea Signal Physics and...2015 1 Abstract We proposed a program involving two inter-related components of ASW: signal and noise. Deep water signal propagation is largely thought...fundamental statis- tics of broadband low-frequency acoustical signals evolve during propagation through a dynamically-varying deep ocean, and how

  13. Deep-sea ecosystem response to the Middle Eocene Climate Optimum (MECO) in the North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Bunzel, Dorothea; Schmiedl, Gerhard; Friedrich, Oliver

    2016-04-01

    We investigated the benthic foraminiferal diversity and species composition from North Atlantic IODP Site U1408 in order to document changes in deep-water circulation and organic matter fluxes across the Middle Eocene Climate Optimum (MECO). Site U1408 was drilled at a present water depth of 3022 m southeast of the coast of Newfoundland. The benthic foraminiferal faunas are characterized by generally high species diversity suggesting favorable environmental conditions throughout the studied interval. Among a total of 193 benthic foraminiferal taxa the most dominant genera include Nuttallides, Oridorsalis, Cibicidoides, Pullenia, Anomalinoides, Globocassidulina and Gyroidinoides. Increased abundances of elongate-cylindrical infaunal species suggest approximately 460 ka duration of the MECO (from around 40.19 to 39.73 Ma) and the presence of slightly less ventilated bottom waters and elevated food availability during this time interval. The duration of the MECO also coincides with the presence of the planktonic foraminifer Orbulinoides beckmanni, which therefore is used as an Eocene biostratigraphy marker defining the end of the warm interval with its Last Appearance Datum. Changes in the benthic foraminiferal fauna probably reflect the onset of deep-water formation in the northern North Atlantic Ocean as response to the long-term climatic cooling trend of the middle Eocene. The intensification of deep-water currents and increased influence of cold and well-ventilated deep-water masses is reflected by increased importance of the Nuttallides truempyi-fauna. Superimposed on this long-term faunal trend are changes in the distribution of Globocassidulina subglobosa at a period of approximately 200 ka suggesting an eccentricity forcing of deep-water formation and associated food quality at the sea floor.

  14. Geochemistry of oil-field water from the North Slope

    SciTech Connect

    Kharaka, Y.K.; Carothers, W.W.

    1989-01-01

    Knowledge of the chemical composition of oil-field water is important in understanding the origin and migration of petroleum as well as the water mineral reactions that affect the porosity and permeability of the reservoir rocks. This knowledge is essential in interpreting electric logs and in determining potential pollution, corrosion, and disposal problems of water produced with oil and gas. Finally, the chemical composition of water is an important factor in determining the conditions (temperature, pressure) for the formation of clathrates. This chapter reports detailed chemical analyses of seven formation-water samples from wells within the NPRA and one surface-and two formation-water samples from the Prudhoe Bay oil field. The authors also report {delta}D and {delta}{sup 18}O values for eight of the water samples as well as analyses for gases from six wells. The formation-water samples were obtained from depths ranging from about 700 to 2800 m and from reservoir rocks ranging in age from Mississippian (Lisburne Group) to Triassic. The reservoir rocks are sandstone except for sample 79-AK-5, which was obtained from a limestone interbedded with sandstone. Generally, the pre-Cretaceous sandstone reservoir rocks on the North Slope have a similar mineral composition. Van de Kamp (1979) gave the following description of these sandstones: Quartz (usually monocrystalline) and chert are the major components; carbonate and clay are variable. Carbonate occurs as detrital grains and as cement, siderite being the most common type. Siderite can form as much as 30 percent of the rock. Clay occurs as a common matrix, generally making up less than 10 percent of the rock. Accessory minerals include pyrite, plagioclase, microcline, glauconite, zircon, sphene, tourmaline, and muscovite.

  15. Lead isotopes in North Pacific deep water - Implications for past changes in input sources and circulation patterns

    USGS Publications Warehouse

    van de Flierdt, T.; Frank, M.; Halliday, A.N.; Hein, J.R.; Hattendorf, B.; Gunther, D.; Kubik, P.W.

    2003-01-01

    The sources of non-anthropogenic Pb in seawater have been the subject of debate. Here we present Pb isotope time-series that indicate that the non-anthropogenic Pb budget of the northernmost Pacific Ocean has been governed by ocean circulation and riverine inputs, which in turn have ultimately been controlled by tectonic processes. Despite the fact that the investigated locations are situated within the Asian dust plume, and proximal to extensive arc volcanism, eolian contributions have had little impact. We have obtained the first high-resolution and high-precision Pb isotope time-series of North Pacific deep water from two ferromanganese crusts from the Gulf of Alaska in the NE Pacific Ocean, and from the Detroit Seamount in the NW Pacific Ocean. Both crusts were dated applying 10 Be/9Be ratios and yield continuous time-series for the past 13.5 and 9.6 Myr, respectively. Lead isotopes show a monotonic evolution in 206Pb/204Pb from low values in the Miocene (??? 18.57) to high values at present day (??? 18.84) in both crusts, even though they are separated by more than 3000 km along the Aleutian Arc. The variation exceeds the amplitude found in Equatorial Pacific deep water records by about three-fold. There also is a striking similarity in 207Pb/204Pb and 208Pb/ 204Pb ratios of the two crusts, indicating the existence of a local circulation cell in the sub-polar North Pacific, where efficient lateral mixing has taken place but only limited exchange (in terms of Pb) with deep water from the Equatorial Pacific has occurred. Both crusts display well-defined trends with age in Pb-Pb isotope mixing plots, which require the involvement of at least four distinct Pb sources for North Pacific deep water. The Pb isotope time-series reveal that eolian supplies (volcanic ash and continent-derived loess) have only been of minor importance for the dissolved Pb budget of marginal sites in the deep North Pacific over the past 6 Myr. The two predominant sources have been young

  16. Lead isotopes in North Pacific deep water - implications for past changes in input sources and circulation patterns

    NASA Astrophysics Data System (ADS)

    van de Flierdt, Tina; Frank, Martin; Halliday, Alex N.; Hein, James R.; Hattendorf, Bodo; Günther, Detlef; Kubik, Peter W.

    2003-04-01

    The sources of non-anthropogenic Pb in seawater have been the subject of debate. Here we present Pb isotope time-series that indicate that the non-anthropogenic Pb budget of the northernmost Pacific Ocean has been governed by ocean circulation and riverine inputs, which in turn have ultimately been controlled by tectonic processes. Despite the fact that the investigated locations are situated within the Asian dust plume, and proximal to extensive arc volcanism, eolian contributions have had little impact. We have obtained the first high-resolution and high-precision Pb isotope time-series of North Pacific deep water from two ferromanganese crusts from the Gulf of Alaska in the NE Pacific Ocean, and from the Detroit Seamount in the NW Pacific Ocean. Both crusts were dated applying 10Be/ 9Be ratios and yield continuous time-series for the past 13.5 and 9.6 Myr, respectively. Lead isotopes show a monotonic evolution in 206Pb/ 204Pb from low values in the Miocene (≤18.57) to high values at present day (≥18.84) in both crusts, even though they are separated by more than 3000 km along the Aleutian Arc. The variation exceeds the amplitude found in Equatorial Pacific deep water records by about three-fold. There also is a striking similarity in 207Pb/ 204Pb and 208Pb/ 204Pb ratios of the two crusts, indicating the existence of a local circulation cell in the sub-polar North Pacific, where efficient lateral mixing has taken place but only limited exchange (in terms of Pb) with deep water from the Equatorial Pacific has occurred. Both crusts display well-defined trends with age in Pb-Pb isotope mixing plots, which require the involvement of at least four distinct Pb sources for North Pacific deep water. The Pb isotope time-series reveal that eolian supplies (volcanic ash and continent-derived loess) have only been of minor importance for the dissolved Pb budget of marginal sites in the deep North Pacific over the past 6 Myr. The two predominant sources have been young

  17. Cosmic Star-Formation History and Deep ALMA imaging of the Hubble Ultra Deep Field

    NASA Astrophysics Data System (ADS)

    Dunlop, James

    2015-08-01

    I will give an overview of how recent work at UV, optical, infrared, mm and radio wavelengths have impacted on our current understanding of the cosmic evolution of co-moving star-formation rate density. I will review recent progress at redshifts z ~ 2 - 3, corresponding to the putative peak of star-formation activity. However, I will focus primarily on new results at the very highest redshifts, within 1 Gyr of the Big Bang, where dramatic recent observational progress with Hubble, Spitzer, Vista, and spectrographs on 8-m telescopes has enabled us to chart the rise of the early galaxy population back to redshifts z ~ 10, and to deduce the basic physical properties of galaxies at these early times. We have also been able to estimate the contribution of young galaxies to the reionization of the Universe, and I will show that the inferred progress of reionization is now in excellent agreement with new measurements of the Thomson scattering optical depth from microwave background observations with Planck. I will conclude with a discussion of how new results from deep ALMA imaging have the potential to clarify and complete our understanding of cosmic star-formation history.

  18. The deep biosphere below North Pond: A mid-Atlantic microbial observatory

    NASA Astrophysics Data System (ADS)

    Edwards, K. J.; Bach, W.; Klaus, A.

    2011-12-01

    IODP Expedition 336 (Sept-Nov 2011) was executed to address fundamental microbiological questions concerning the nature of the subseafloor deep biosphere in oceanic hydrological, geological, and biogeochemical context (Edwards et al., 2010). Our principal objective is to study the subseafloor microbiological communities in young igneous ocean crust, in order to understand their role in ocean crust alteration and their ecology in hydrological and biogeochemical context. Specifically, we are testing the hypothesis that microbes play an active role in ocean crust alteration, while also exploring broad based ecological questions such as how hydrological structure and geochemistry influence microbial community structures. We will accomplish this by installing borehole observatories (CORKs) for coupled microbiological, geochemical, and hydrological experiments. These CORKs will allow us to monitor conditions and study processes in-situ,after the drilling disturbance and contaminating influences in the borehole environment have dissipated. Operations during Expedition 336 will lay the foundation for long-term monitoring, experimentation, and observations by subsequent ROV or submersible dive expeditions. CORKs will be used in perturbation and monitoring points for single- and cross-hole experiments, and will use recently developed novel in-situ microbiological experimentation system "FLOCS" (Orcutt et al., 2010a; Orcutt et al., 2010b). This talk will present initial results from Expedition 336 and discuss plans for future observatory operations. Edwards KJ, Bach W, Klaus A (2010). Mid-Atlantic ridge flank microbiology: Initiation of long-term coupled microbiological, geochemical, and hydrological experimentation within the seafloor at North Pond, western flank of the Mid-Atlantic ridge. IODP Sci. Prosp., 336. Integrated Ocean Drilling Program: College Station, TX. p 62 pp.http://publications.iodp.org/scientific_prospectus/336/ Orcutt B, Wheat CG, Edwards KJ (2010a

  19. The Earthquake Loading Cycle and the Deep Structure of the North Anatolian Fault

    NASA Astrophysics Data System (ADS)

    Wright, T. J.; Cornwell, D. G.; Farrell, K.; Hawthorne, J. C.; Houseman, G. A.; Hussain, E.; Lloyd, G. E.; Phillips, R. J.; Thompson, D. A.; Rost, S.; Yamasaki, T.; Turkelli, N.; Gülen, L.

    2014-12-01

    Deformation of the Earth's upper crust is localized onto narrow fault zones, which may slip suddenly and catastrophically in earthquakes. Strain in the upper mantle is more broadly distributed and is thought to occur by continuous ductile creep. The properties of the lower crust are the primary control on the behavior of the coupled system during the earthquake loading cycle. However, the distribution of strain in the lower crust is poorly understood. Here we show that the North Anatolian Fault (NAF) continues as a narrow structure through most of the crust. We use scattering migration from an 18 month deployment of 73 broadband seismometers in a dense array (~7 km spacing) across the NAF in the location of the 1999 Izmit earthquake rupture. The results reveal clear discontinuities in the lower crust across the northern and southern branches of the NAF, which extend to a depth of at least 25 km. Seismicity, by contrast, is confined to the upper ~15 km. Deformation on the fault was well recorded both before and after the 1999 earthquakes. Prior to the earthquake, strain was focused in a ~50 km region around the fault. Following the earthquake, a rapid post-seismic transient was observed, which slowly decayed over the subsequent decade. Earthquake cycle models require at least two relaxation time constants to explain these observations - a strong material to allow focused interseismic strain, and a material capable of relaxing quickly, to give rapid postseismic deformation. We present two models capable of reproducing these observations - (i) a visco-elastic model in which the weak material is found in a zone beneath the seismogenic fault, and (ii) a model in which postseismic deformation occurs through afterslip on a deep extension of the seismogenic fault plane. The latter appears more consistent with the seismic images. We also present results from geological analogues of the mid-lower crust beneath the NAF, which are also consistent with the idea that strain is

  20. Archaeal- and Bacterial-Specific Predation in the Deep North Atlantic

    NASA Astrophysics Data System (ADS)

    Seyler, L. M.; Tuorto, S. J.; McGuinness, L. R.; Gong, D.; Kerkhof, L. J.

    2016-02-01

    Archaea and bacteria are thought to have existed on Earth for nearly 3.5 billion years. Furthermore, bacterial and TACK-archaeota populations have been shown to compete for the same organic resources including acetate, glycine, lipids, and high levels of urea in salt marsh sediments. This competition should lead to a competitive exclusion by one domain or another. However, multiple mechanisms have been proposed to account for this co-occurrence, such as temporal/seasonal separation of activity, resource partitioning, and differential responses to predation. In this study, stable isotope probing (SIP) was used to track archaeal, bacterial, and eukaryotic 13C-uptake in the North Atlantic along a 3800 km transect (52˚W) to assess resource partitioning between archaea and bacteria and determine if 13C-labeled DNA from eukaryotic predators could be detected. Microcosms were amended with 13C-acetate or 13C-urea (20-30 µM) and incubated for 48 hrs along with 12C-controls. The results indicated archaea often outcompeted bacteria for 13C-urea while both archaea and bacteria could incorporate 13C-acetate. This 13C label could also be detected in 37 eukaryotic OTUs in the SIP incubations. The largest number of 13C-labeled eukaryotic OTUs were observed in the absence of either 13C-archaeal or 13C-bacterial signal, suggesting an osmotrophic lifestyle. However, other specific 13C-eukaryotic OTUs were exclusively associated with either 13C-archaeal or 13C-bacterial OTUs or both. These archaeal-specific and bacterial-specific eukaryotic OTUs are often related to known bactivorous predators. Our findings suggests both resource partitioning and selective predation can account for a portion of the archaeal/bacterial coexistence in the deep-sea environment. These types of SIP approaches can map out these trophic interaction between microbial predators and their prey to better predict the fate of dissolved and particulate organic carbon in marine ecosystems.

  1. The distribution of deep-sea sponge aggregations in the North Atlantic and implications for their effective spatial management

    NASA Astrophysics Data System (ADS)

    Howell, Kerry-Louise; Piechaud, Nils; Downie, Anna-Leena; Kenny, Andrew

    2016-09-01

    Sponge aggregations have been recognised as key component of shallow benthic ecosystems providing several important functional roles including habitat building and nutrient recycling. Within the deep-sea ecosystem, sponge aggregations may be extensive and available evidence suggests they may also play important functional roles, however data on their ecology, extent and distribution in the North Atlantic is lacking, hampering conservation efforts. In this study, we used Maximum Entropy Modelling and presence data for two deep-sea sponge aggregation types, Pheronema carpenteri aggregations and ostur aggregations dominated by geodid sponges, to address the following questions: 1) What environmental factors drive the broad-scale distribution of these selected sponge grounds? 2) What is the predicted distribution of these grounds in the northern North Atlantic, Norwegian and Barents Sea? 3) How are these sponge grounds distributed between Exclusive Economic Zones (EEZs) and High Seas areas? 4) What percentage of these grounds in High Seas areas are protected by the current High Seas MPA network? Our results suggest that silicate concentration, temperature, depth and amount of particulate organic carbon are the most important drivers of sponge distribution. Most of the sponge grounds are located within national EEZs rather than in the High Seas. Coordinated conservation planning between nations with significant areas of sponge grounds such as Iceland, Greenland and Faroes (Denmark), Norway (coastal Norway and Svalbard), Portugal and the UK, should be implemented in order to effectively manage these communities in view of the increasing level of human activity within the deep-sea environment.

  2. Deep geothermal processes acting on faults and solid tides in coastal Xinzhou geothermal field, Guangdong, China

    NASA Astrophysics Data System (ADS)

    Lu, Guoping; Wang, Xiao; Li, Fusi; Xu, Fangyiming; Wang, Yanxin; Qi, Shihua; Yuen, David

    2017-03-01

    This paper investigated the deep fault thermal flow processes in the Xinzhou geothermal field in the Yangjiang region of Guangdong Province. Deep faults channel geothermal energy to the shallow ground, which makes it difficult to study due to the hidden nature. We conducted numerical experiments in order to investigate the physical states of the geothermal water inside the fault zone. We view the deep fault as a fast flow path for the thermal water from the deep crust driven up by the buoyancy. Temperature measurements at the springs or wells constrain the upper boundary, and the temperature inferred from the Currie temperature interface bounds the bottom. The deepened boundary allows the thermal reservoir to revolve rather than to be at a fixed temperature. The results detail the concept of a thermal reservoir in terms of its formation and heat distribution. The concept also reconciles the discrepancy in reservoir temperatures predicted from both quartz and Na-K-Mg. The downward displacement of the crust increases the pressure at the deep ground and leads to an elevated temperature and a lighter water density. Ultimately, our results are a first step in implementing numerical studies of deep faults through geothermal water flows; future works need to extend to cases of supercritical states. This approach is applicable to general deep-fault thermal flows and dissipation paths for the seismic energy from the deep crust.

  3. Contrasting patterns of α- and β-diversity in deep-sea bivalves of the eastern and western North Atlantic

    NASA Astrophysics Data System (ADS)

    Brault, Solange; Stuart, Carol T.; Wagstaff, Martine C.; McClain, Craig R.; Allen, John A.; Rex, Michael A.

    2013-08-01

    We analyzed patterns of α- and β-diversity in deep-sea bivalves collected by epibenthic sleds from the western North Atlantic south of New England, and from the eastern North Atlantic in the Rockall Trough, Porcupine Seabight and Porcupine Abyssal Plain. In the western North Atlantic, species diversity, measured as the normalized expected number of species, shows a unimodal bathymetric trend peaking at mid-bathyal depths. In the eastern North Atlantic, diversity increases monotonically with depth reaching a maximum at abyssal depths. We used Baselga's (2010) metrics to distinguish two separate components of β-diversity along depth gradients, species dissimilarity among sites due to spatial replacement (turnover) and species loss leading to nestedness. We also examined the rank order of nestedness with depth using Rodríguez-Gironés and Santamaría's (2006) BINMATNEST. The primary difference in β-diversity between west and east centers on the composition of abyssal communities. In the western North Atlantic, abyssal assemblages are nested subsets of bathyal assemblages. In the eastern North Atlantic, turnover dominates at all depths. These very fundamental differences in community structure between the basins may be attributable to differences in food supply, which is greater in the eastern North Atlantic region sampled. POC-flux to abyssal depths in the east may not reach levels low enough to depress species diversity as it does in the west. In the west, the abyssal fauna is largely an impoverished nested subset of the bathyal fauna that shows less endemism and may be maintained partly by source-sink dynamics.

  4. Vertical distribution of living ostracods in deep-sea sediments, North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Jöst, Anna B.; Yasuhara, Moriaki; Okahashi, Hisayo; Ostmann, Alexandra; Arbizu, Pedro Martínez; Brix, Saskia

    2017-04-01

    The depth distribution of living specimens of deep-sea benthic ostracods (small crustaceans with calcareous shells that are preserved as microfossils) in sediments is poorly understood, despite the importance of this aspect of basic ostracod biology for paleoecologic and paleoceanographic interpretations. Here, we investigated living benthic ostracod specimens from deep-sea multiple core samples, to reveal their depths distributions within sediment cores. The results showed shallow distribution and low population density of living deep-sea benthic ostracods (which are mostly composed of Podocopa). The living specimens are concentrated in the top 1 cm of the sediment, hence deep-sea benthic ostracods are either epifauna or shallow infauna. This observation is consistent with the information from shallow-water species. We also confirmed shallow infaunal (0.5-2 cm) and very shallow infaunal (0-1 cm) habitats of the deep-sea ostracod genera Krithe and Argilloecia, respectively.

  5. Results of injection and tracer tests in Olkaria north east field in Kenya

    SciTech Connect

    Karingithi, C.W.

    1995-12-31

    Tracer and injection tests were performed in the Olkaria North East Field with the objective to reduce uncertainty in the engineering design and to determine the suitability of well OW-704 as a re-injection well for the waste brine from the steam field during production. An organic dye (sodium fluorescein) was injected into well OW-704 as a slug. The tracer returns were observed in well OW-M2 which is 580 m deep, 620 m from well OW-704 and well OW-716 which is 900 m from well OW-704. The other wells on discharge, OW-714, and OW-725 did not show any tracer returns. However, other chemical constituents suggested., that well OW-716 experienced a chemical breakthrough earlier than OW-M2. Tracer return velocities of 0.31 m/hr and 1.3 m/hr were observed. Results of the tracer and injection tests indicate that OW-704 may be used as a re-injection well provided a close monitoring program is put in place.

  6. UVUDF: Ultraviolet imaging of the Hubble ultra deep field with wide-field camera 3

    SciTech Connect

    Teplitz, Harry I.; Rafelski, Marc; Colbert, James W.; Hanish, Daniel J.; Kurczynski, Peter; Gawiser, Eric; Bond, Nicholas A.; Gardner, Jonathan P.; De Mello, Duilia F.; Grogin, Norman; Koekemoer, Anton M.; Brown, Thomas M.; Coe, Dan; Ferguson, Henry C.; Atek, Hakim; Finkelstein, Steven L.; Giavalisco, Mauro; Gronwall, Caryl; Lee, Kyoung-Soo; Ravindranath, Swara; and others

    2013-12-01

    We present an overview of a 90 orbit Hubble Space Telescope treasury program to obtain near-ultraviolet imaging of the Hubble Ultra Deep Field using the Wide Field Camera 3 UVIS detector with the F225W, F275W, and F336W filters. This survey is designed to: (1) investigate the episode of peak star formation activity in galaxies at 1 < z < 2.5; (2) probe the evolution of massive galaxies by resolving sub-galactic units (clumps); (3) examine the escape fraction of ionizing radiation from galaxies at z ∼ 2-3; (4) greatly improve the reliability of photometric redshift estimates; and (5) measure the star formation rate efficiency of neutral atomic-dominated hydrogen gas at z ∼ 1-3. In this overview paper, we describe the survey details and data reduction challenges, including both the necessity of specialized calibrations and the effects of charge transfer inefficiency. We provide a stark demonstration of the effects of charge transfer inefficiency on resultant data products, which when uncorrected, result in uncertain photometry, elongation of morphology in the readout direction, and loss of faint sources far from the readout. We agree with the STScI recommendation that future UVIS observations that require very sensitive measurements use the instrument's capability to add background light through a 'post-flash'. Preliminary results on number counts of UV-selected galaxies and morphology of galaxies at z ∼ 1 are presented. We find that the number density of UV dropouts at redshifts 1.7, 2.1, and 2.7 is largely consistent with the number predicted by published luminosity functions. We also confirm that the image mosaics have sufficient sensitivity and resolution to support the analysis of the evolution of star-forming clumps, reaching 28-29th magnitude depth at 5σ in a 0.''2 radius aperture depending on filter and observing epoch.

  7. Near-field effects of asteroid impacts in deep water

    SciTech Connect

    Gisler, Galen R; Weaver, Robert P; Gittings, Michael L

    2009-06-11

    Our previous work has shown that ocean impacts of asteroids below 500 m in diameter do not produce devastating long-distance tsunamis. Nevertheless, a significant portion of the ocean lies close enough to land that near-field effects may prove to be the greatest danger from asteroid impacts in the ocean. Crown splashes and central jets that rise up many kilometres into the atmosphere can produce, upon their collapse, highly non-linear breaking waves that could devastate shorelines within a hundred kilometres of the impact site. We present illustrative calculations, in two and three dimensions, of such impacts for a range of asteroid sizes and impact angles. We find that, as for land impacts, the greatest dangers from oceanic impacts are the short-term near-field, and long-term atmospheric effects.

  8. DSDP Site 603: First deep (>1000-m) penetration of the continental rise along the passive margin of eastern North America

    NASA Astrophysics Data System (ADS)

    van Hinte, Jan E.; Wise, Sherwood W., Jr.; Biart, Brian N. M.; Mitchener Covington, J.; Dunn, Dean A.; Haggerty, Janet A.; Johns, Mark W.; Meyers, Philip A.; Moullade, Michel R.; Muza, Jay P.; Ogg, James G.; Okamura, Makoto; Sarti, Massimo; von Rad, Ulrich

    1985-06-01

    Drilling at Deep Sea Drilling Project Site 603 has provided the first deep (>1000-m) penetration of strata beneath the continental rise off the Atlantic margin of North America. Nearly continuously cored through 1585 m of section down to Berriasian pelagic limestones, the site 435 km (270 mi) east of Cape Hatteras intersected an extensive Lower Cretaceous deep-sea fan complex, which provides new information on the petroleum potential of the continental rise. Hauterivian to early Aptian in age, this 208-m interval of interbedded limestones, sand, and black shale turbidites begs the existence of any post-Valanginian reefs along the Baltimore Canyon Trough. Less extensive terrigenous turbidites were encountered higher in the section up to the Cretaceous/Tertiary boundary, which is marked by a current-laminated sand rich in dark spherules. Pelagic early Paleogene clays are disconformably overlain by Miocene pelagic mud. Turbiditic silts and clays began to accumulate rapidly at this site during the middle Miocene, leading to deposition of muddy contourites that formed the Lower Continental Rise Hills of the Hatteras Outer Ridge as sand turbidites were ponded concurrently on its landward side. The section at Site 603 confirms the concept that eustatic and other large-scale events subdivide Earth history into distinct chapters allowing the correlation of deep-sea seismic sequence boundaries with continental shelf and margin unconformities.

  9. Deep-Water Benthic Foraminifers from the Paleocene and Eocene of the North Pacific Region: Paleontology, Biostratigraphy, and Paleoceanological Reconstructions

    NASA Astrophysics Data System (ADS)

    Olshanetskiy, D. M.

    2015-12-01

    A zonal scheme for the Lower Paleogene of the northern Pacific Ocean is proposed on the basis of the stratigraphic distribution of benthic foraminifers in the lower bathyal-abyssal beds studied in boreholes in the North and South Pacific regions. This scheme includes eight subdivisions (six zones and two subzones). The boundaries of the benthic zonal subdivisions are defined by bioevents (appearance or disappearance of stratigraphically important taxa) and are linked to the zonal scales based on planktonic foraminifers and calcareous nannoplankton. It is established that most of these bioevents are recognized subglobally. Apart from the evolutionary events, changes in the deep-water benthic foraminiferal assemblages were caused by changes in the paleooceanological environment. This allowed detailed characterization of a global mass extinction of assemblages of deep-water benthic foraminifers in the region studied. It is also established that changes in the assemblages of deep-water benthic foraminifers, observed in either change in their taxonomic composition or changes in abundance and diversity, resulted from the presence of different deep-water masses in the region.

  10. The deep thermal field of the Upper Rhine Graben

    NASA Astrophysics Data System (ADS)

    Freymark, Jessica; Sippel, Judith; Scheck-Wenderoth, Magdalena; Bär, Kristian; Stiller, Manfred; Fritsche, Johann-Gerhard; Kracht, Matthias

    2017-01-01

    The Upper Rhine Graben has a significant socioeconomic relevance as it provides a great potential for geothermal energy production. The key for the utilisation of this energy resource is to understand the controlling factors of the thermal field in this area. We have therefore built a data-based lithospheric-scale 3D structural model of the Upper Rhine Graben and its adjacent areas. In addition, 3D gravity modelling was performed to constrain the internal structure of the crystalline crust consistent with seismic information. Based on this lithosphere scale 3D structural model the present-day conductive thermal field was calculated and compared to measured temperatures. Our results show that the regional thermal field is mainly controlled by the configuration of the upper crust, which has different thermal properties characteristic for the Variscan and Alpine domains. Temperature maxima are predicted for the Upper Rhine Graben where thick insulating Cenozoic sediments cause a thermal blanketing effect and where the underlying crustal units are characterised by high radiogenic heat production. The comparison of calculated and measured temperatures overall shows a reasonable fit, while locally occuring model deviations indicate where a larger influence of groundwater flow may be expected.

  11. North Pacific Acoustic Laboratory: Deep Water Acoustic Propagation in the Philippine Sea

    DTIC Science & Technology

    2016-06-21

    the "Special Issue on Deep-water Ocean Acoustics" in the Journal of the Acoustical Society of America (Vol. 134, No . 4, Pt. 2 of 2 , October20 13...15. SUBJECT TERMS ocean acoustics, deep water acousti c propagati on 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF a. REPORT b. ABSTRACT c...the 2009- 2011 NPAL Philippine Sea experiments funded by ONR Grant NOOO 14- 08-1-0840, although some additional work on deep-water ocean acoustics is

  12. Long Range Effect of The M7.8 April 2015 Nepal Earth Quake on the Deep Groudwater Outflow in a Thousand-Mile-Away Geothermal Field in Southern China's Guangdong

    NASA Astrophysics Data System (ADS)

    Lu, G.; Yu, S.; Xu, F.; Wang, X.; Yan, K.; Yuen, D. A.

    2015-12-01

    Deep ground waters sustain high temperature and pressure and are susceptible to impact from an earthquake. How an earthquake would have been associated with long-range effect on geological environment of deep groundwater is a question of interest to the scientific community and general public. The massive Richter 8.1 Nepal Earthquake (on April 25, 2015) provided a rare opportunity to test the response of deep groundwater systems. Deep ground waters at elevated temperature would naturally flow to ground surface along preferential flow path such as a deep fault, forming geothermal water flows. Geothermal water flows are susceptible to stress variation and can reflect the physical conditions of supercritical hot water kilometers deep down inside the crust. This paper introduces the monitoring work on the outflow in Xijiang Geothermal Field of Xinyi City, Guangdong Province in southern China. The geothermal field is one of typical geothermal fields with deep faults in Guangdong. The geothermal spring has characteristic daily variation of up to 72% in flow rate, which results from being associated with a north-south run deep fault susceptible to earthquake event. We use year-long monitoring data to illustrate how the Nepal earthquake would have affected the flows at the field site over 2.5 thousand kilometers away. The irregularity of flow is judged by deviation from otherwise good correlation of geothermal spring flow with solid earth tidal waves. This work could potentially provide the basis for further study of deep groundwater systems and insight to earthquake prediction.

  13. A PILOT FOR A VERY LARGE ARRAY H I DEEP FIELD

    SciTech Connect

    Fernandez, Ximena; Van Gorkom, J. H.; Schiminovich, David; Hess, Kelley M.; Pisano, D. J.; Kreckel, Kathryn; Momjian, Emmanuel; Popping, Attila; Oosterloo, Tom; Chomiuk, Laura; Verheijen, M. A. W.; Henning, Patricia A.; Bershady, Matthew A.; Wilcots, Eric M.; Scoville, Nick

    2013-06-20

    High-resolution 21 cm H I deep fields provide spatially and kinematically resolved images of neutral hydrogen at different redshifts, which are key to understanding galaxy evolution across cosmic time and testing predictions of cosmological simulations. Here we present results from a pilot for an H I deep field done with the Karl G. Jansky Very Large Array (VLA). We take advantage of the newly expanded capabilities of the telescope to probe the redshift interval 0 < z < 0.193 in one observation. We observe the COSMOS field for 50 hr, which contains 413 galaxies with optical spectroscopic redshifts in the imaged field of 34' Multiplication-Sign 34' and the observed redshift interval. We have detected neutral hydrogen gas in 33 galaxies in different environments spanning the probed redshift range, including three without a previously known spectroscopic redshift. The detections have a range of H I and stellar masses, indicating the diversity of galaxies we are probing. We discuss the observations, data reduction, results, and highlight interesting detections. We find that the VLA's B-array is the ideal configuration for H I deep fields since its long spacings mitigate radio frequency interference. This pilot shows that the VLA is ready to carry out such a survey, and serves as a test for future H I deep fields planned with other Square Kilometer Array pathfinders.

  14. A Pilot for a Very Large Array H I Deep Field

    NASA Astrophysics Data System (ADS)

    Fernández, Ximena; van Gorkom, J. H.; Hess, Kelley M.; Pisano, D. J.; Kreckel, Kathryn; Momjian, Emmanuel; Popping, Attila; Oosterloo, Tom; Chomiuk, Laura; Verheijen, M. A. W.; Henning, Patricia A.; Schiminovich, David; Bershady, Matthew A.; Wilcots, Eric M.; Scoville, Nick

    2013-06-01

    High-resolution 21 cm H I deep fields provide spatially and kinematically resolved images of neutral hydrogen at different redshifts, which are key to understanding galaxy evolution across cosmic time and testing predictions of cosmological simulations. Here we present results from a pilot for an H I deep field done with the Karl G. Jansky Very Large Array (VLA). We take advantage of the newly expanded capabilities of the telescope to probe the redshift interval 0 < z < 0.193 in one observation. We observe the COSMOS field for 50 hr, which contains 413 galaxies with optical spectroscopic redshifts in the imaged field of 34' × 34' and the observed redshift interval. We have detected neutral hydrogen gas in 33 galaxies in different environments spanning the probed redshift range, including three without a previously known spectroscopic redshift. The detections have a range of H I and stellar masses, indicating the diversity of galaxies we are probing. We discuss the observations, data reduction, results, and highlight interesting detections. We find that the VLA's B-array is the ideal configuration for H I deep fields since its long spacings mitigate radio frequency interference. This pilot shows that the VLA is ready to carry out such a survey, and serves as a test for future H I deep fields planned with other Square Kilometer Array pathfinders.

  15. The nitrate leached below maize root zone is available for deep-rooted wheat in winter wheat-summer maize rotation in the North China Plain.

    PubMed

    Zhou, Shun-Li; Wu, Yong-Cheng; Wang, Zhi-Min; Lu, Lai-Qing; Wang, Run-Zheng

    2008-04-01

    In winter wheat (Triticum aestivum L.)-summer maize (Zea mays L.) rotation system in the North China Plain, maize roots do not extend beyond 1.2 m in the vertical soil profile, but wheat roots can reach up to 2.0 m. Increases in soil nitrate content at maize harvest and significant reductions after winter wheat harvest were observed in the 1.4-2.0 m depth under field conditions. The recovery of 15N isotope (calcium nitrate) from various (1.0, 1.2, 1.4, 1.6, 1.8 and 2.0 m) soil depths showed that deep-rooting winter wheat could use soil nitrate up to the 2.0 m depth. This accounted partially, for the reduced nitrate in the 1.4-2.0 m depth of the soil after harvest of wheat in the rotation system.

  16. The demise of the early Eocene greenhouse - Decoupled deep and surface water cooling in the eastern North Atlantic

    NASA Astrophysics Data System (ADS)

    Bornemann, André; D'haenens, Simon; Norris, Richard D.; Speijer, Robert P.

    2016-10-01

    Early Paleogene greenhouse climate culminated during the early Eocene Climatic Optimum (EECO, 50 to 53 Ma). This episode of global warmth is subsequently followed by an almost 20 million year-long cooling trend leading to the Eocene-Oligocene glaciation of Antarctica. Here we present the first detailed planktic and benthic foraminiferal isotope single site record (δ13C, δ18O) of late Paleocene to middle Eocene age from the North Atlantic (Deep Sea Drilling Project Site 401, Bay of Biscay). Good core recovery in combination with well preserved foraminifera makes this site suitable for correlations and comparison with previously published long-term records from the Pacific Ocean (e.g. Allison Guyot, Shatsky Rise), the Southern Ocean (Maud Rise) and the equatorial Atlantic (Demerara Rise). Whereas our North Atlantic benthic foraminiferal δ18O and δ13C data agree with the global trend showing the long-term shift toward heavier δ18O values, we only observe minor surface water δ18O changes during the middle Eocene (if at all) in planktic foraminiferal data. Apparently, the surface North Atlantic did not cool substantially during the middle Eocene. Thus, the North Atlantic appears to have had a different surface ocean cooling history during the middle Eocene than the southern hemisphere, whereas cooler deep-water masses were comparatively well mixed. Our results are in agreement with previously published findings from Tanzania, which also support the idea of a muted post-EECO surface-water cooling outside the southern high-latitudes.

  17. Eruption style and flow emplacement in the Submarine North Arch Volcanic Field, Hawaii

    NASA Astrophysics Data System (ADS)

    Clague, David A.; Uto, Kozo; Satake, Kenji; Davis, Alicé S.

    The North Arch Volcanic Field covers about 24,000 km2 of seafloor north of Oahu and has an estimated volume between 1,000 and 1,250 km3. The field straddles the Hawaiian flexural arch about 250 km north of the axis of the island chain and surrounds numerous Cretaceous volcanic ridges, circular flat-topped volcanoes, and low-relief regions of sediment-covered seafloor. New SeaBeam bathymetric maps that cover about 1/3 of the flow field reveal nearly 100 volcanic structures ranging from low shields to steep cones. One shield is modified by a pit crater, approximately 1.1×1.25 km and 300 m deep. A lava flow in the SE part of the volcanic field covers about 3,600 km2, has an estimated volume of 36-72 km3, and apparently erupted from a 75-km-long NNW-trending fissure system. A 108-km-long flow advanced north in a graben parallel to the Cretaceous mid-ocean ridge that formed the crust; its surface gradient is 1.9 m/km (slope of 0.1°). Shinkai 6500 submersible dive 502 explored one of the composite volcanoes and observed and collected dense alkalic basalt sheet flows erupted after vesicular basanite pillow basalts and fragmental hyaloclastite that make up the steep-sided cone. Dive 503 collected alkalic basalt sheet flows and pillow basalt from the top 122 m of the southern wall of a pit crater that formed by collapse caused by a decrease in magma volume from a shallow storage chamber located 1-2 km below the surface. The volume change may have been caused by loss of gas bubbles from the stored magma when replenishment ceased at the end of the eruption. The surficial drapery-folded sheet flow is covered by only a few cm of sediment, indicating that it is younger than the 0.5-1.5 Ma ages previously estimated for North Arch flows and vents. The near-vent constructs and flow characteristics indicate that vigorous eruption of highly vesicular lava constructed steep-sided cones of pillow basalt and hyaloclastite whereas steady eruption of dense lava that had lost its bubbles

  18. Research on Fast Nitriding by Direct Current Field Base on the Deep-layer QPQ Technology

    NASA Astrophysics Data System (ADS)

    Wang, K.; Luo, D. F.; Zhang, L.

    In recent years the QPQ technical innovator is the development and application of deep-layer QPQ. But also brings a lot of problems need to solve. This article introduces a new technology use direct current field at low temperature and short time base on the deep-layer QPQ. Use 45# as material, we make a comparative between DC treatment and normal treatment at the same condition. The results show that the DC treatment was beneficial forms of the nitrided layer and the performance index was the same as normal treatment. The formation of the nitrided layer in the direct current field situation is analyzed.

  19. Large field-of-view telescope for deep surveys

    NASA Astrophysics Data System (ADS)

    Barbe, Jacques P.; Cerutti-Maori, Guy; Rozelot, Jean-Pierre

    1997-03-01

    Conventional astronomical telescope makes use of a Ritchey- Chretien 2-mirror telescope, with a limited FOV except in the case of use of complex field corrector inducing spectral range limitations. For the future, large imaging telescope could offer main scientific advantages, like: (1) obtain a 3D description of the content of a large volume of the universe; (2) galaxy content and morphology; (3) galaxy red shift; (4) dark matter distribution; (5) absolute length scale. The present paper proposes for this large imaging telescope mission, the use of a Korsh, 3-mirror telescope thats characteristics are: (1) size approximately equals 2.5 meter; (2) field is greater than or equal to 1.5 degrees (but with no light on the optical axis); (3) image quality is less than or equal to 0.3 feet; (4) multispectral capabilities: from 0.35 micrometer up to 2.5 micrometer and more if needed; (5) real exit pupil with flat mirror; (6) good focal plane accessibility allowing multiple instrumentations: turret rotation of the previous flat mirror can be used, with several fixed instruments.

  20. The spatial distribution of X-ray selected AGN in the Chandra deep fields: a theoretical perspective

    NASA Astrophysics Data System (ADS)

    Marulli, Federico; Bonoli, Silvia; Branchini, Enzo; Gilli, Roberto; Moscardini, Lauro; Springel, Volker

    2009-07-01

    We study the spatial distribution of X-ray selected active galactic nuclei (AGN) in the framework of hierarchical coevolution of supermassive black holes and their host galaxies and dark matter haloes. To this end, we have applied the theoretical model developed by Croton et al., De Lucia & Blaizot and Marulli et al. to the output of the Millennium Run and obtained hundreds of realizations of past light cones from which we have extracted realistic mock AGN catalogues that mimic the Chandra deep fields. We find that the model AGN number counts are in fair agreement with observations both in the soft and in the hard X-ray bands, except at fluxes <~10-15ergcm-2s-1, where the model systematically overestimates the observations. However, a large fraction of these faint objects are typically excluded from the spectroscopic AGN samples of the Chandra fields. We find that the spatial two-point correlation function predicted by the model is well described by a power-law relation out to 20h-1Mpc, in close agreement with observations. Our model matches the correlation length r0 of AGN in the Chandra Deep Field-North but underestimates it in the Chandra Deep Field-South. When fixing the slope to γ = 1.4, as in Gilli et al., the statistical significance of the mismatch is 2σ-2.5σ, suggesting that the predicted cosmic variance, which dominates the error budget, may not account for the different correlation length of the AGN in the two fields. However, the overall mismatch between the model and the observed correlation function decreases when both r0 and γ are allowed to vary, suggesting that more realistic AGN models and a full account of all observational errors may significantly reduce the tension between AGN clustering in the two fields. While our results are robust to changes in the model prescriptions for the AGN light curves, the luminosity dependence of the clustering is sensitive to the different light-curve models adopted. However, irrespective of the model

  1. North Pacific Acoustic Laboratory: Deep Water Acoustic Propagation in the Philippine Sea

    DTIC Science & Technology

    2014-06-09

    J. A., and Howe, B. M. (2013). "Deep seafloor arrivals in long range ocean acoustic propagation," J. Acoust. Soc. Am. 134,3307-3317. Udovydchenkov... Spread , steepness and skewness of surface slopes," Annual Review of Marine Science 1, 377-415. Skarsoulis, E. K., Comuelle, B. D., and Dzieciuch, M...Dzieciuch, M. A., Worcester, P. F., Andrew, R. K., Buck, L. J., Mercer, J. A., Colosi, J. A., and Howe, B. M. (2009). "Deep seafloor arrivals: An

  2. AKARI North Ecliptic Pole Deep Survey. Revision of the catalogue via a new image analysis

    NASA Astrophysics Data System (ADS)

    Murata, K.; Matsuhara, H.; Wada, T.; Arimatsu, K.; Oi, N.; Takagi, T.; Oyabu, S.; Goto, T.; Ohyama, Y.; Malkan, M.; Pearson, C.; Małek, K.; Solarz, A.

    2013-11-01

    Context. We present the revised near- to mid-infrared catalogue of the AKARI North Ecliptic Pole deep survey. The survey has the unique advantage of continuous filter coverage from 2 to 24 μm over nine photometric bands, but the initial version of the survey catalogue leaves room for improvement in the image analysis stage; the original images are strongly contaminated by the behaviour of the detector and the optical system. Aims: The purpose of this study is to devise new image analysis methods and to improve the detection limit and reliability of the source extraction. Methods: We removed the scattered light and stray light from the Earth limb, and corrected for artificial patterns in the images by creating appropriate templates. We also removed any artificial sources due to bright sources by using their properties or masked them out visually. In addition, for the mid-infrared source extraction, we created detection images by stacking all six bands. This reduced the sky noise and enabled us to detect fainter sources more reliably. For the near-infrared source catalogue, we considered only objects with counterparts from ground-based catalogues to avoid fake sources. For our ground-based catalogues, we used catalogues based on the CFHT/MegaCam z' band, CFHT/WIRCam Ks band and Subaru/Scam z' band. Objects with multiple counterparts were all listed in the catalogue with a merged flag for the AKARI flux. Results: The detection limits of all mid-infrared bands were improved by ~20%, and the total number of detected objects was increased by ~2000 compared with the previous version of the catalogue; it now has 9560 objects. The 5σ detection limits in our catalogue are 11, 9, 10, 30, 34, 57, 87, 93, and 256 μJy in the N2, N3, N4, S7, S9W, S11, L15, L18W, and L24 bands, respectively. The astrometric accuracies of these band detections are 0.48, 0.52, 0.55, 0.99, 0.95, 1.1, 1.2, 1.3, and 1.6 arcsec, respectively. The false-detection rate of all nine bands was decreased

  3. Deep significance of the field concept in contemporary biomedical sciences.

    PubMed

    Jerman, Igor; Krasovec, Rok; Leskovar, Robert T

    2009-01-01

    Since antiquity, biology has had two opposing views of life and organisms: holistic (organismic) and reductionist. In contemporary biology, the molecular reductionist approach prevails--its central entity being the gene. Organicism lingers on the margin of biology, having well-elaborated ideas but no empirical confirmation for the integrative biological entity. The latter could be found in the endogenous coherent EM field (ECEMF), since it organizes countless cellular processes, including cell's division, and through the coupling of coherence domains integrates the whole organism. A serious and thorough reconsideration of life and organisms in light of this new biological entity would have far-reaching consequences in all areas of biological science, i.e., in ontogeny, the theory of evolution, understanding and combating serious illnesses, and above all, cancer.

  4. Phylogeographic analysis reveals a deep lineage split within North Atlantic Littorina saxatilis.

    PubMed

    Doellman, Meredith M; Trussell, Geoffrey C; Grahame, John W; Vollmer, Steve V

    2011-11-07

    Phylogeographic studies provide critical insight into the evolutionary histories of model organisms; yet, to date, range-wide data are lacking for the rough periwinkle Littorina saxatilis, a classic example of marine sympatric speciation. Here, we use mitochondrial DNA (mtDNA) sequence data to demonstrate that L. saxatilis is not monophyletic for this marker, but is composed of two distinct mtDNA lineages (I and II) that are shared with sister species Littorina arcana and Littorina compressa. Bayesian coalescent dating and phylogeographic patterns indicate that both L. saxatilis lineages originated in the eastern North Atlantic, around the British Isles, at approximately 0.64 Ma. Both lineages are now distributed broadly across the eastern, central and western North Atlantic, and show strong phylogeographic structure among regions. The Iberian Peninsula is genetically distinct, suggesting prolonged isolation from northeastern North Atlantic populations. Western North Atlantic populations of L. saxatilis lineages I and II predate the last glacial maximum and have been isolated from eastern North Atlantic populations since that time. This identification of two distinct, broadly distributed mtDNA lineages further complicates observed patterns of repeated incipient ecological speciation in L. saxatilis, because the sympatric origins of distinct ecotype pairs on eastern North Atlantic shores may be confounded by admixture of divergent lineages.

  5. Phylogeographic analysis reveals a deep lineage split within North Atlantic Littorina saxatilis

    PubMed Central

    Doellman, Meredith M.; Trussell, Geoffrey C.; Grahame, John W.; Vollmer, Steve V.

    2011-01-01

    Phylogeographic studies provide critical insight into the evolutionary histories of model organisms; yet, to date, range-wide data are lacking for the rough periwinkle Littorina saxatilis, a classic example of marine sympatric speciation. Here, we use mitochondrial DNA (mtDNA) sequence data to demonstrate that L. saxatilis is not monophyletic for this marker, but is composed of two distinct mtDNA lineages (I and II) that are shared with sister species Littorina arcana and Littorina compressa. Bayesian coalescent dating and phylogeographic patterns indicate that both L. saxatilis lineages originated in the eastern North Atlantic, around the British Isles, at approximately 0.64 Ma. Both lineages are now distributed broadly across the eastern, central and western North Atlantic, and show strong phylogeographic structure among regions. The Iberian Peninsula is genetically distinct, suggesting prolonged isolation from northeastern North Atlantic populations. Western North Atlantic populations of L. saxatilis lineages I and II predate the last glacial maximum and have been isolated from eastern North Atlantic populations since that time. This identification of two distinct, broadly distributed mtDNA lineages further complicates observed patterns of repeated incipient ecological speciation in L. saxatilis, because the sympatric origins of distinct ecotype pairs on eastern North Atlantic shores may be confounded by admixture of divergent lineages. PMID:21429920

  6. The Photometric Stability of ACS: Revisiting the Hubble Deep Field

    NASA Astrophysics Data System (ADS)

    Riess, A.

    2004-12-01

    We utilized 10 epochs of 15-tile ACS WFC mosaics imaging the HDFN in the F850lp filter over two years, and originally obtained for the science goal of finding type Ia supernovae at z>1, to examine the photometric stability of the WFC (with at least filter f850lp). Using repeated measurements of 371 stars, we performed a multi-variate linear regression to determine the dependence of photometric variations on the time-dependent components of parallel and serial CTE degradation as well as an overall time-dependence which would indicate a change in the WFC's sensitivity. Despite important differences between the HDFN scenes and those in the original calibration field of 47 Tuc (i.e., source crowding and sky level), we find the losses due to imperfect CTE to be consistent between the two independent calibrations. Interestingly, we also find a decrease in the overall sensitivity of the ACS WFC at a rate of 0.004 +/- 0.001 magnitudes per year (consistent with findings based on 47 Tuc data from work in progress by Mack et al. 2005, in prep.).

  7. Dynamic depositional and early diagenetic processes in a deep-water shelf setting, upper cretaceous Austin Chalk, North Texas

    SciTech Connect

    Hovorka, S.D.; Nance, H.S.

    1994-12-31

    The Austin Chalk of north Texas was deposited on a deep-water shelf north of the Sea Marcos Platform during a worldwide Coniacian and Santonian sea-level highstand. Transgressive (lowermost lower Austin Chalk), highstand (uppermost lower Austin Chalk), and regressive (middle and upper Austin Chalk) phases of cyclic chalk and marl sedimentation are recognized in excavations and tunnels created in Ellis County for the Superconducting Super Collider provide new evidence of sediment transport during Austin Chalk deposition. During transgression, bottom currents syndepositionally reworked nannoplankton oozes, incising channels as much as 120 ft across and 8 ft deep. Weakly burrowed channel fills having preservation of fine lamination document rapid infilling. Channel fills are composed of pyritized and carbonized wood and Inoceramus lag deposits, pellets, echinoderm fragments, and globigerinid grainstones, and coccolith ooze. During maximum highstand, bottom reworking was suppressed. Detrital content of highstand marls is low (>20 percent); organic content is high (1.4 to 3.5 percent). Coccolith preservation is excellent because of minimal diagenetic alteration. Regression is marked by resumed channel cutting and storm-bed winnowing in the middle and upper Austin Chalk. Suppressed resistivity log response and recessive weathering characteristics of the middle Austin Chalk are not primarily related to depositional environment but rather to increased input of volcanic ash during the accumulation of this interval. Early stabilization of ash produced clay-coated microfabrics in sediments that are otherwise similar to the transgressive deposits.

  8. The VIMOS VLT Deep Survey. Public release of 1599 redshifts to IAB≤24 across the Chandra Deep Field South

    NASA Astrophysics Data System (ADS)

    Le Fèvre, O.; Vettolani, G.; Paltani, S.; Tresse, L.; Zamorani, G.; Le Brun, V.; Moreau, C.; Bottini, D.; Maccagni, D.; Picat, J. P.; Scaramella, R.; Scodeggio, M.; Zanichelli, A.; Adami, C.; Arnouts, S.; Bardelli, S.; Bolzonella, M.; Cappi, A.; Charlot, S.; Contini, T.; Foucaud, S.; Franzetti, P.; Garilli, B.; Gavignaud, I.; Guzzo, L.; Ilbert, O.; Iovino, A.; McCracken, H. J.; Mancini, D.; Marano, B.; Marinoni, C.; Mathez, G.; Mazure, A.; Meneux, B.; Merighi, R.; Pellò, R.; Pollo, A.; Pozzetti, L.; Radovich, M.; Zucca, E.; Arnaboldi, M.; Bondi, M.; Bongiorno, A.; Busarello, G.; Ciliegi, P.; Gregorini, L.; Mellier, Y.; Merluzzi, P.; Ripepi, V.; Rizzo, D.

    2004-12-01

    This paper presents the VIMOS VLT Deep Survey around the Chandra Deep Field South (CDFS). We have measured 1599 new redshifts with VIMOS on the European Observatory Very Large Telescope - UT3, in an area 21 × 21.6 arcmin2, including 784 redshifts in the Hubble Space Telescope - Advanced Camera for Surveys GOODS area. 30% of all objects with IAB=24 have been observed independently of magnitude, indicating that the sample is purely magnitude limited. We have reached an unprecedented completeness level of 84% in terms of the ratio of secure measurements vs. observed objects, while 95% of all objects have a redshift measurement. A total of 1452 galaxies, 139 stars, 8 QSOs have a redshift identification, 141 of these being unsecure measurements. The redshift distribution down to IAB=24 is peaked at a median redshift z=0.73, with a significant high redshift tail extending up to ˜4. Several high density peaks in the distribution of galaxies are identified. In particular, the strong peak at z=0.735 contains more than 130 galaxies in a velocity range ±2000 km s-1 distributed all across the transverse ˜20 h-1 Mpc of the survey. We are releasing all redshifts to the community, along with the cross identification with HST-ACS GOODS sources on the CENCOS database environment http://cencosw.oamp.fr. The data presented in this paper has been obtained with the European Southern Observatory Very Large Telescope, Paranal, Chile.

  9. Accurate segmentation of lung fields on chest radiographs using deep convolutional networks

    NASA Astrophysics Data System (ADS)

    Arbabshirani, Mohammad R.; Dallal, Ahmed H.; Agarwal, Chirag; Patel, Aalpan; Moore, Gregory

    2017-02-01

    Accurate segmentation of lung fields on chest radiographs is the primary step for computer-aided detection of various conditions such as lung cancer and tuberculosis. The size, shape and texture of lung fields are key parameters for chest X-ray (CXR) based lung disease diagnosis in which the lung field segmentation is a significant primary step. Although many methods have been proposed for this problem, lung field segmentation remains as a challenge. In recent years, deep learning has shown state of the art performance in many visual tasks such as object detection, image classification and semantic image segmentation. In this study, we propose a deep convolutional neural network (CNN) framework for segmentation of lung fields. The algorithm was developed and tested on 167 clinical posterior-anterior (PA) CXR images collected retrospectively from picture archiving and communication system (PACS) of Geisinger Health System. The proposed multi-scale network is composed of five convolutional and two fully connected layers. The framework achieved IOU (intersection over union) of 0.96 on the testing dataset as compared to manual segmentation. The suggested framework outperforms state of the art registration-based segmentation by a significant margin. To our knowledge, this is the first deep learning based study of lung field segmentation on CXR images developed on a heterogeneous clinical dataset. The results suggest that convolutional neural networks could be employed reliably for lung field segmentation.

  10. Intermediate and deep water paleoceanography of the northern North Atlantic over the past 21,000 years

    NASA Astrophysics Data System (ADS)

    Thornalley, David J. R.; Elderfield, Harry; McCave, I. Nick

    2010-03-01

    Benthic foraminiferal stable isotope records from four high-resolution sediment cores, forming a depth transect between 1237 m and 2303 m on the South Iceland Rise, have been used to reconstruct intermediate and deep water paleoceanographic changes in the northern North Atlantic during the last 21 ka (spanning Termination I and the Holocene). Typically, a sampling resolution of ˜100 years is attained. Deglacial core chronologies are accurately tied to North Greenland Ice Core Project (NGRIP) ice core records through the correlation of tephra layers and changes in the percent abundance of Neogloboquadrina pachyderma (sinistral) with transitions in NGRIP. The evolution from the glacial mode of circulation to the present regime is punctuated by two periods with low benthic δ13C and δ18O values, which do not lie on glacial or Holocene water mass mixing lines. These periods correlate with the late Younger Dryas/Early Holocene (11.5-12.2 ka) and Heinrich Stadial 1 (14.7-16.8 ka) during which time freshwater input and sea-ice formation led to brine rejection both locally and as an overflow exported from the Nordic seas into the northern North Atlantic, as earlier reported by Meland et al. (2008). The export of brine with low δ13C values from the Nordic seas complicates traditional interpretations of low δ13C values during the deglaciation as incursions of southern sourced water, although the spatial extent of this brine is uncertain. The records also reveal that the onset of the Younger Dryas was accompanied by an abrupt and transient (˜200-300 year duration) decrease in the ventilation of the northern North Atlantic. During the Holocene, Iceland-Scotland Overflow Water only reached its modern flow strength and/or depth over the South Iceland Rise by 7-8 ka, in parallel with surface ocean reorganizations and a cessation in deglacial meltwater input to the North Atlantic.

  11. North Atlantic demersal deep-water fish distribution and biology: present knowledge and challenges for the future.

    PubMed

    Bergstad, O A

    2013-12-01

    This paper summarizes knowledge and knowledge gaps on benthic and benthopelagic deep-water fishes of the North Atlantic Ocean, i.e. species inhabiting deep continental shelf areas, continental and island slopes, seamounts and the Mid-Atlantic Ridge. While several studies demonstrate that distribution patterns are species specific, several also show that assemblages of species can be defined and such assemblages are associated with circulatory features and water mass distributions. In many subareas, sampling has, however, been scattered, restricted to shallow areas or soft substrata, and results from different studies tend to be difficult to compare quantitatively because of sampler differences. Particularly, few studies have been conducted on isolated deep oceanic seamounts and in Arctic deep-water areas. Time series of data are very few and most series are short. Recent studies of population structure of widely distributed demersal species show less than expected present connectivity and considerable spatial genetic heterogeneity and complexity for some species. In other species, genetic homogeneity across wide ranges was discovered. Mechanisms underlying the observed patterns have been proposed, but to test emerging hypotheses more species should be investigated across their entire distribution ranges. Studies of population biology reveal greater diversity in life-history strategies than often assumed, even between co-occurring species of the same family. Some slope and ridge-associated species are rather short-lived, others very long-lived, and growth patterns also show considerable variation. Recent comparative studies suggest variation in life-history strategies along a continuum correlated with depth, ranging from shelf waters to the deep sea where comparatively more species have extended lifetimes, and slow rates of growth and reproduction. Reproductive biology remains too poorly known for most deep-water species, and temporal variation in recruitment has

  12. Ultra-deep K-band Imaging of the Hubble Frontier Fields

    NASA Astrophysics Data System (ADS)

    Brammer, G. B.; Marchesini, D.; Labbé, I.; Spitler, L.; Lange-Vagle, D.; Barker, E. A.; Tanaka, M.; Fontana, A.; Galametz, A.; Ferré-Mateu, A.; Kodama, T.; Lundgren, B.; Martis, N.; Muzzin, A.; Stefanon, M.; Toft, S.; van der Wel, A.; Vulcani, B.; Whitaker, K. E.

    2016-09-01

    We have recently completed a deep near-infrared imaging survey with the High Acuity Wide Field K-band Imager (HAWK-I), nicknamed KIFF (Ks-band Imaging of the Frontier Fields). KIFF provides ultra-deep images of six fields around massive galaxy clusters that have also recently been observed with the Hubble and Spitzer Space Telescopes as part of the Frontier Fields programme. Each of the KIFF mosaics is among the deepest Ks-band images ever obtained, and, with a boost from strong gravitational lensing by the galaxy clusters, they will be used to reveal the stellar populations of galaxies seen only a few hundred million years after the Big Bang. Fully reduced images are made available to the community through the Phase 3 infrastructure of the ESO Science Archive Facility.

  13. Neutralizing Carbonic Acid in Deep Carbonate Strata below the North Atlantic

    SciTech Connect

    Klaus Lackner; Charles Harvey; Bruce Watson

    2008-01-14

    Carbon dioxide injection into deep sea sediments below 2700 m water depth and a few hundred meters to fifteen hundred meters deep in the sediment column may provide permanent geologic storage by gravitational trapping. At high pressures and low temperatures common in deep sea sediments a few hundred meters below sea floor, CO{sub 2} will be in its liquid phase and will be denser than the overlying pore fluid. The lower density of the pore fluid provides a cap to the denser CO{sub 2} and ensures gravitational trapping in the short term. The overall storage capacity for CO{sub 2} in such deep sea formations below the ocean floor is primarily determined by the permeability, and will vary with seafloor depth, geothermal gradient, porosity, and pore water salinity. Furthermore, the dissemination of the injected CO{sub 2} in the sediments and potential chemical reactions between CO{sub 2}, pore fluid and sediments will define its fate in the storage reservoir. The main objectives of our research was to evaluate the potential for sub-seabed CO{sub 2} storage in deep sea sediments using a range of approaches including experiments, permeability analysis, and modeling. Over the course of the three-year award, our results support an important role for sub-seabed storage in a diverse portfolio of carbons sequestration options. Our analysis has shown the feasibility of this type of storage, and also emphasizes that escape or leakage from such sites would be negligible. The most difficult challenge is to overcome the low permeability of typical deep-sea sediments, and a variety of approaches are suggested for future research.

  14. 2011 North Plains research field 12-200 limited irrigation corn production study

    USDA-ARS?s Scientific Manuscript database

    The North Plains Water Conservation District started a water conservation project in 2010 on corn irrigation aimed at using just 12 inches of irrigation and producing 200 bu/ac of corn. This report is for 2011, the second year of the study, conducted at the North Plains Research Field (NPRF) in Ett...

  15. Subregional-scale groundwater depletion detected by GRACE for both shallow and deep aquifers in North China Plain

    NASA Astrophysics Data System (ADS)

    Huang, Zhiyong; Pan, Yun; Gong, Huili; Yeh, Pat J.-F.; Li, Xiaojuan; Zhou, Demin; Zhao, Wenji

    2015-03-01

    This study explores the capability of Gravity Recovery and Climate Experiment (GRACE) to detect heterogeneous groundwater storage (GWS) variations in two subregions of the North China Plain: the Piedmont Plain (PP, ~54,000 km2, mainly exploiting shallow groundwater) and East Central Plain (ECP, ~86,000 km2, mainly exploiting deep groundwater). Results show that the GWS anomalies estimated from GRACE data (2003-2013) agree well with those estimated from in situ observations (2005-2010) for both PP (R2 = 0.91) and ECP (R2 = 0.75). The shallow GWS (2003-2013) in PP declines faster (-46.5 ± 6.8 mm/yr) than the deep GWS in ECP (-16.9 ± 1.9 mm/yr). However, the shallow GWS in PP recovered more quickly especially during the 2008-2011 drought period. Despite its lower magnitude, the GRACE-derived GWS depletion in ECP reveals the overexploitation of deep GWS. This study demonstrated that the heterogeneous GWS variations can potentially be detected by GRACE at the subregional scale smaller than the typical GRACE footprint (200,000 km2).

  16. Orbital and suborbital variability in North Atlantic bottom water temperature obtained from deep-sea ostracod Mg/Ca ratios

    USGS Publications Warehouse

    Cronin, T. M.; Dwyer, G.S.; Baker, P.A.; Rodriguez-Lazaro, J.; DeMartino, D.M.

    2000-01-01

    Magnesium/calcium (Mg/Ca) ratios were measured in the deep-sea ostracod (Crustacea) genus Krithe from Chain core 82-24-4PC from the western mid-Atlantic Ridge (3427 m) in order to estimate ocean circulation and bottom water temperature (BWT) variability over the past 200,000 years. Mg/Ca ratios have been used as a paleothermometer because the ratios are controlled primarily by ambient water temperatures at the time the organism secretes its adult carapace. Over the past two glacial-interglacial cycles, Mg/Ca values oscillated between about 7 mmol/mol and 12 mmol/mol, equivalent to a BWT range of 0 to > 3.5??C. The lowest values were obtained on specimens from glacial marine isotope stages (MISs) 2, 4 and 6; the highest values were obtained from specimens from the early part of the Holocene interglacial (MIS 1), and also from MISs 5 and 7. These trends suggest that BWTs in the North Atlantic Ocean fluctuate over orbital time scales. Suborbital variability in Mg/Ca ratios and BWT was also observed for the past 100,000 years. Ratios rose from ~8 mmol/mol to ~10 mmol/mol (implying a BWT increase of ~1 to 3??C) during 14 Mg/Ca excursions. The highest ratios were found in Krithe dated at approximately 32, 36-38, 43, 48, 73, 85 and 93 ka. Although the age model for the Chain 82-24-4PC and temporal resolution do not allow precise correlation, some of these deep-sea bottom temperature excursions appear to correspond to Heinrich events recorded in other regions of the North Atlantic and perhaps Dansgaard-Oeschger interstadial events recorded in Greenland ice cores. If confirmed, this would support the hypothesis that millennial-scale oscillations of climate in the North Atlantic are capable of affecting global climate via thermohaline circulation changes. (C) 2000 Elsevier Science B.V.

  17. Deep regional resistivity structure across the Battle Mountain-Eureka and Carlin trends, north-central Nevada

    USGS Publications Warehouse

    Rodriguez, Brian D.; Williams, Jackie M.

    2001-01-01

    Magnetotelluric data collected along four, regional scale, southwest-to-northeast profiles show deep resistivity structures beneath the Battle Mountain-Eureka and Carlin gold trends in north-central Nevada, which appear consistent with tectonic breaks in the crust that possibly served as channels for hydrothermal fluids. It seems likely that gold deposits along these linear trends were, therefore, controlled by deep regional crustal fault systems. Two-dimensional resistivity modeling of the magnetotelluric data generally show resistive (30 to 1,000 ohm-m) crustal blocks broken by narrow, sub-vertical, two-dimensional, conductive (1 to 10 ohm-m) zones that are indicative of large-scale crustal fault zones. These inferred fault zones are regional in scale, trend southeast-to-northwest, and extend to mid-crustal (20 km) depths. The conductors are about 3 to 15 km wide, extend from 1 to 8 km below the surface to about 20 km depth, and show two-dimensional electrical structure with general north to northwesterly strikes. From connecting the locations of the conductors together, a single regional crustal fault zone can be inferred that is about 10 km wide within the upper crust and about 150-km long. It coincides with the Battle Mountain-Eureka mineral trend. The images also show regional changes in the resistive crust from north to south. Most of Reese River Valley and Boulder Valley are underlain by a thick (20 km) southwest-to-northeast section of conductive (1 to 10 ohm-m) rock, suggesting that hightemperature fluids are more pervasive in this area (Battle Mountain Heat-Flow High), which implies that the crust beneath these valleys is more fractured than in the areas surveyed to the south

  18. MUSE deep-fields: the Ly α luminosity function in the Hubble Deep Field-South at 2.91 < z < 6.64

    NASA Astrophysics Data System (ADS)

    Drake, Alyssa B.; Guiderdoni, Bruno; Blaizot, Jérémy; Wisotzki, Lutz; Herenz, Edmund Christian; Garel, Thibault; Richard, Johan; Bacon, Roland; Bina, David; Cantalupo, Sebastiano; Contini, Thierry; den Brok, Mark; Hashimoto, Takuya; Marino, Raffaella Anna; Pelló, Roser; Schaye, Joop; Schmidt, Kasper B.

    2017-10-01

    We present the first estimate of the Ly α luminosity function using blind spectroscopy from the Multi Unit Spectroscopic Explorer, MUSE, in the Hubble Deep Field-South. Using automatic source-detection software, we assemble a homogeneously detected sample of 59 Ly α emitters covering a flux range of -18.0 < log10 (F) < -16.3 (erg s-1 cm-2), corresponding to luminosities of 41.4 < log10 (L) < 42.8 (erg s-1). As recent studies have shown, Ly α fluxes can be underestimated by a factor of 2 or more via traditional methods, and so we undertake a careful assessment of each object's Ly α flux using a curve-of-growth analysis to account for extended emission. We describe our self-consistent method for determining the completeness of the sample, and present an estimate of the global Ly α luminosity function between redshifts 2.91 < z < 6.64 using the 1/Vmax estimator. We find that the luminosity function is higher than many number densities reported in the literature by a factor of 2-3, although our result is consistent at the 1σ level with most of these studies. Our observed luminosity function is also in good agreement with predictions from semi-analytic models, and shows no evidence for strong evolution between the high- and low-redshift halves of the data. We demonstrate that one's approach to Ly α flux estimation does alter the observed luminosity function, and caution that accurate flux assessments will be crucial in measurements of the faint-end slope. This is a pilot study for the Ly α luminosity function in the MUSE deep-fields, to be built on with data from the Hubble Ultra Deep Field that will increase the size of our sample by almost a factor of 10.

  19. Behavior of Deep Eutectic Solvents under External Electric Fields: A Molecular Dynamics Approach.

    PubMed

    Atilhan, Mert; Aparicio, Santiago

    2017-01-12

    The properties of selected deep eutectic solvents (DESs) comprising choline chloride as a hydrogen bond acceptor and several types of hydrogen bond donors under static and dynamic external electric fields (EEFs) have been studied in this work using classical molecular dynamics simulations. The effects of field intensities under static conditions and of field frequencies under dynamic conditions were simulated. The response of the fluids to the external fields was analyzed from the changes in dipolar arrangements, intermolecular interaction energies, nanoscopic arrangements, and molecular diffusion. These results show for the very first time the nonequilibrium behavior of DESs under EEFs.

  20. "Complexity" in Polarity Transitions at the Matuyama-Brunhes Boundary and top Jaramillo in North Atlantic Deep-sea Sediments

    NASA Astrophysics Data System (ADS)

    Channell, J. E. T.

    2016-12-01

    Integrated Ocean Drilling Program (IODP) Expedition 303 to the North Atlantic provided 16 records of the Matuyama-Brunhes polarity transition (MBT) and the top Jaramillo transition, based on u-channel and discrete samples, from holes drilled at three sites (Sites U1304, U1305 and U1306) that have mean Brunhes sedimentation rates of 16-18 cm/kyr. The MBT occurs during the transition from marine isotope stage (MIS) 19.3 to MIS 18.4, with mid-point at 773 ka, and a transition duration of 5-8 kyr. The top Jaramillo occurs during MIS 28 at 992 ka with a similar 5 kyr transition duration. Combining the new records with previously published North Atlantic records (ODP Sites 983, 984 and 1063) yields a total of 24 high sedimentation rate records. The MBT yields a repetitive pattern of transitional field states as virtual geomagnetic poles (VGPs) move from high southern latitudes to loop over the Pacific, cluster in NE Asia, and transit into the mid-latitude South Atlantic before reaching high latitudes in the Northern Hemisphere. The VGPs for the top Jaramillo transition feature a loop over the Pacific, then occupation of the NE Asia cluster before transit over the Indian Ocean to high southerly latitudes. The North Atlantic MBT records described here are very different to the longitudinally constrained North Atlantic VGP paths from MBT records that are the basis for a 2007 Bayesian inversion of the MBT field. We conclude that the relatively low sedimentation rate ( 4 cm/kyr) records utilized in the Bayesian inversion have been heavily smoothed by the remanence acquisition process, and do not adequately represent the MBT field. The VGPs at the MBT and top Jaramillo, as measured in the North Atlantic, have similarities with excursion (Iceland Basin) VGP paths, and are apparently guided by maxima in downward vertical flux in the modern non-dipole (ND) field, implying longevity in ND features through time.

  1. Methane hydrate potential and development of a shallow gas field in the arctic: The Walakpa Field North Slope Alaska

    SciTech Connect

    Glenn, R.K.

    1992-01-01

    The goal of the North Slope Hydrate Study is to evaluate the methane hydrate potential of the Walakpa gas field, a shallow gas field located near Barrow, Alaska. Observing, understanding, and predicting the production characteristics of the Walakpa field will be accomplished by the analysis of the reservoir geology, and of the individual well production data, derived from reservoir engineering studies conducted in the field.

  2. Methane hydrate potential and development of a shallow gas field in the arctic: The Walakpa Field North Slope Alaska

    SciTech Connect

    Glenn, R.K.

    1992-06-01

    The goal of the North Slope Hydrate Study is to evaluate the methane hydrate potential of the Walakpa gas field, a shallow gas field located near Barrow, Alaska. Observing, understanding, and predicting the production characteristics of the Walakpa field will be accomplished by the analysis of the reservoir geology, and of the individual well production data, derived from reservoir engineering studies conducted in the field.

  3. Results of study of deep underground structure of mud volcanoes in North-Western Caucasus by means of geological and geophysical methods

    NASA Astrophysics Data System (ADS)

    Sobissevitch, A. L.; Gorbatikov, A. V.; Ovsuychenko, A. N.; Sobissevitch, L. E.; Stepanova, M. Yu.; Morev, B. A.

    2009-04-01

    Results of complementary geological and geophysical studies of mud volcanic phenomena in North-Western Caucasus (Taman mud volcanic province) are presented. New technology for passive subsurface sounding of the Earth's crust has been originally developed at the Schmidt Institute of Physics of the Earth, Russian Academy of Sciences. Patented since 2005, this technology represents the new kind of seismic survey based on specific features of propagation of the Rayleigh waves. It uses natural background microseismic noise as a sounding signal. By using the method of low-frequency microseismic sounding in the course of field works carried out in 2006 - 2008, there have been obtained three vertical cross-sections for the two mud volcanoes down to the depth of 25 km. For the two different mud volcanoes their deep subsurface structure has been revealed and discussed. The Gora Karabetova mud volcano is one of the most active mud volcanoes in the Taman peninsula with primarily explosive behaviour while the Shugo mud volcano's activity pattern is different, explosive events are rare and both types of phenomena may be explained by the configuration of their feeding systems, tectonic position and deep pathways of migration of fluids. Complementary interpretation of raw data sets delivered form geophysical and geological surveys allows considering principal differences of origin and mechanisms of mud volcanic activity for the Shugo and the Gora Karabetova mud volcanoes.

  4. LINDLEY NURSERY COMPLEX NORTH loOKING SOUTHEAST ACROSS FORMER FIELDS THROUGH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    LINDLEY NURSERY COMPLEX NORTH loOKING SOUTHEAST ACROSS FORMER FIELDS THROUGH MORNING MIST - Overhills, Fort Bragg Military Reservation, Approximately 15 miles NW of Fayetteville, Overhills, Harnett County, NC

  5. Field keys to predators of the balsam woolly aphid in North Carolina

    Treesearch

    Gene D. Amman

    1970-01-01

    These keys will be useful for field identification of immature insect, adult mite, and slug predators of the balsam woolly aphid. The keys include, in addition to native predators, the larvae of three species introduced to North Carolina.

  6. Near Infrared Imaging of the Hubble Deep Field with Keck Telescope

    NASA Technical Reports Server (NTRS)

    Hogg, David W.; Neugebauer, G.; Armus, Lee; Matthews, K.; Pahre, Michael A.; Soifer, B. T.; Weinberger, A. J.

    1997-01-01

    Two deep K-band (2.2 micrometer) images, with point-source detection limits of K=25.2 mag (one sigma), taken with the Keck Telescope in subfields of the Hubble Deep Field, are presented and analyzed. A sample of objects to K=24 mag is constructed and V(sub 606)- I(sub 814) and I(sub 814)-K colors are measured. By stacking visually selected objects, mean I(sub 814)-K colors can be measured to very faint levels, the mean I(sub 814)-K color is constant with apparent magnitude down to V(sub 606)=28 mag.

  7. New Insights on the North American Monsoon from the 2004 Name Field Campaign

    NASA Astrophysics Data System (ADS)

    Johnson, R. H.

    2014-12-01

    The 2004 North American Monsoon Experiment (NAME) was an international field campaign conducted over northwestern Mexico, the Gulf of California, and the surrounding region. The overarching goal of NAME was the determination of the sources and limits of predictability of warm season precipitation over North America, with emphasis on time scales ranging from seasonal-to-interannual. The observational component of NAME involved measurements of a range of monsoon phenomena using aircraft, soundings, profilers, research radars, ships, surface stations, rain gauges, and surface flux sites. The NAME enhanced observational network has confirmed a number of previous theories and hypotheses with respect to North American Monsoon (NAM) processes, but also yielded new insight and details regarding specific phenomena of the NAM region. Several new findings stemming from NAME observations are: The 12-14 July 2004 overall gulf surge event was comprised of several stages: an initial disturbance identified as a Kelvin shock (an internal bore modified by rotation) followed by a general acceleration of the flow by multiple convectively generated gravity currents and bores along the span of the Gulf, then ending again in the northern Gulf as a Kelvin shock disturbance; A tropical upper-tropospheric trough (TUTT) associated with the 12-14 July Gulf Surged enhanced precipitation on its western flank as it passed over the mountains of northern Mexico. It is found that these upper-level disturbances modify the low-level flow and slightly increase CAPE so as to cause more highly organized mesoscale convective systems to move off the Sierra Madre Occidental toward the west and in doing so, strengthen moisture surges over the Gulf of California; and The diurnal cycle of convection determined from sounding-based heat and moisture budgets over the Sierra Madre Occidental (SMO) is characterized by shallow convection around noon, deep convection at 1800 LT, evolving to stratiform precipitation

  8. New estimates of area and mass for the North American tektite strewn field

    NASA Technical Reports Server (NTRS)

    Koeberl, C.

    1989-01-01

    A revised estimate is given for the total mass of the North American tektite material, which is based on a concept of patches or rays of distribution rather than on a continuous tektite and microtektite blanket. This concept yields a total mass of about 3 x 10 to the 14th g, which is less than a third of previous estimates. The shape of the North American tektite strewn field is in agreement with other tektite strewn fields.

  9. Deep blank-field catalogue for medium- and large-sized telescopes

    NASA Astrophysics Data System (ADS)

    Jiménez Esteban, F. M.; Cabrera Lavers, A.; Cardiel, N.; Alacid, J. M.

    2012-11-01

    The observation of blank fields, defined as regions of the sky that are devoid of stars down to a given threshold magnitude, constitutes one of the most relevant calibration procedures required for the proper reduction of astronomical data obtained following typical observing strategies. In this work, we have used Delaunay triangulation to search for deep blank fields throughout the whole sky, with a minimum size of 10 arcmin in diameter and an increasing threshold magnitude from 15 to 18 in the R band of the USNO-B Catalog of the United States Naval Observatory. The result is a catalogue with the deepest blank fields known so far. A short sample of these regions has been tested with the 10.4-m Gran Telescopio Canarias, and it has been shown to be extremely useful for medium- and large-sized telescopes. Because some of the regions found could also be suitable for new extragalactic studies, we have estimated the galactic extinction in the direction of each deep blank field. This catalogue is accessible through the virtual observatory tool TESELA, and the user can retrieve - and visualize using ALADIN - the deep blank fields available near a given position in the sky.

  10. Deep-Earth reactor: Nuclear fission, helium, and the geomagnetic field

    PubMed Central

    Hollenbach, D. F.; Herndon, J. M.

    2001-01-01

    Geomagnetic field reversals and changes in intensity are understandable from an energy standpoint as natural consequences of intermittent and/or variable nuclear fission chain reactions deep within the Earth. Moreover, deep-Earth production of helium, having 3He/4He ratios within the range observed from deep-mantle sources, is demonstrated to be a consequence of nuclear fission. Numerical simulations of a planetary-scale geo-reactor were made by using the SCALE sequence of codes. The results clearly demonstrate that such a geo-reactor (i) would function as a fast-neutron fuel breeder reactor; (ii) could, under appropriate conditions, operate over the entire period of geologic time; and (iii) would function in such a manner as to yield variable and/or intermittent output power. PMID:11562483

  11. Deep-Earth reactor: Nuclear fission, helium, and the geomagnetic field

    NASA Astrophysics Data System (ADS)

    Hollenbach, D. F.; Herndon, J. M.

    2001-09-01

    Geomagnetic field reversals and changes in intensity are understandable from an energy standpoint as natural consequences of intermittent and/or variable nuclear fission chain reactions deep within the Earth. Moreover, deep-Earth production of helium, having 3He/4He ratios within the range observed from deep-mantle sources, is demonstrated to be a consequence of nuclear fission. Numerical simulations of a planetary-scale geo-reactor were made by using the SCALE sequence of codes. The results clearly demonstrate that such a geo-reactor (i) would function as a fast-neutron fuel breeder reactor; (ii) could, under appropriate conditions, operate over the entire period of geologic time; and (iii) would function in such a manner as to yield variable and/or intermittent output power.

  12. Deep-Earth reactor: nuclear fission, helium, and the geomagnetic field.

    PubMed

    Hollenbach, D F; Herndon, J M

    2001-09-25

    Geomagnetic field reversals and changes in intensity are understandable from an energy standpoint as natural consequences of intermittent and/or variable nuclear fission chain reactions deep within the Earth. Moreover, deep-Earth production of helium, having (3)He/(4)He ratios within the range observed from deep-mantle sources, is demonstrated to be a consequence of nuclear fission. Numerical simulations of a planetary-scale geo-reactor were made by using the SCALE sequence of codes. The results clearly demonstrate that such a geo-reactor (i) would function as a fast-neutron fuel breeder reactor; (ii) could, under appropriate conditions, operate over the entire period of geologic time; and (iii) would function in such a manner as to yield variable and/or intermittent output power.

  13. Considerations for Deep Maneuver: Lessons from North Africa, 1941-1942.

    DTIC Science & Technology

    1985-01-01

    yields the greatest benefits.2 Despite this offensive orientation his army remained one that maneuvered by regiments and was tied to a cumbersome...82175 Both advocated deep penetration by mechanized forces to disrupt enemy command, control , and logistics; both realized the psychological impact of...everywhere. By splitting up their two available divisions into at least five separate elements, none of which were mutually supporting and most of which

  14. Dispersal Patterns of Pleistocene Sands on the North Atlantic Deep-Sea Floor.

    PubMed

    Hubert, J F

    1962-05-04

    Glauconitic, quartzose sands previously modified on the continental shelf from feldspathic glacial detritus were transported through submarine canyons onto the Hudson deep-sea fan, the Hatteras abyssal plain, and the western and central Sohm abyssal plain. These feldspar-poor, quartzose sands contrast with highly feldspathic sands derived directly from a glacial source and probably transported through the Newfoundland abyssal gap onto the eastern and southern Sohm abyssal plain.

  15. Learning Depth from Single Monocular Images Using Deep Convolutional Neural Fields.

    PubMed

    Liu, Fayao; Shen, Chunhua; Lin, Guosheng; Reid, Ian

    2016-10-01

    In this article, we tackle the problem of depth estimation from single monocular images. Compared with depth estimation using multiple images such as stereo depth perception, depth from monocular images is much more challenging. Prior work typically focuses on exploiting geometric priors or additional sources of information, most using hand-crafted features. Recently, there is mounting evidence that features from deep convolutional neural networks (CNN) set new records for various vision applications. On the other hand, considering the continuous characteristic of the depth values, depth estimation can be naturally formulated as a continuous conditional random field (CRF) learning problem. Therefore, here we present a deep convolutional neural field model for estimating depths from single monocular images, aiming to jointly explore the capacity of deep CNN and continuous CRF. In particular, we propose a deep structured learning scheme which learns the unary and pairwise potentials of continuous CRF in a unified deep CNN framework. We then further propose an equally effective model based on fully convolutional networks and a novel superpixel pooling method, which is about 10 times faster, to speedup the patch-wise convolutions in the deep model. With this more efficient model, we are able to design deeper networks to pursue better performance. Our proposed method can be used for depth estimation of general scenes with no geometric priors nor any extra information injected. In our case, the integral of the partition function can be calculated in a closed form such that we can exactly solve the log-likelihood maximization. Moreover, solving the inference problem for predicting depths of a test image is highly efficient as closed-form solutions exist. Experiments on both indoor and outdoor scene datasets demonstrate that the proposed method outperforms state-of-the-art depth estimation approaches.

  16. Observation of deep water microseisms in the North Atlantic Ocean using tide modulations

    NASA Astrophysics Data System (ADS)

    Beucler, Éric; Mocquet, Antoine; Schimmel, Martin; Chevrot, Sébastien; Quillard, Olivier; Vergne, Jérôme; Sylvander, Matthieu

    2015-01-01

    Ocean activity produces continuous and ubiquitous seismic energy mostly in the 2-20 s period band, known as microseismic noise. Between 2 and 10 s period, secondary microseisms (SM) are generated by swell reflections close to the shores and/or by opposing swells in the deep ocean. However, unique conditions are required in order for surface waves generated by deep-ocean microseisms to be observed on land. By comparing short-duration power spectral densities at both Atlantic shoreline and inland seismic stations, we show that ocean tides strongly modulate the seismic energy in a wide period band except between 2.5 and 5 s. This tidal proxy reveals the existence of an ex situ short-period contribution of the SM peak. Comparison with swell spectra at surrounding buoys suggests that the largest part of this extra energy comes from deep ocean-generated microseisms. The energy modulation might be also used in numerical models of microseismic generation to constrain coastal reflection coefficients.

  17. The deep structure of the Western Pyrenees: constraints from tomographic imaging, field and marine geological observations

    NASA Astrophysics Data System (ADS)

    Tugend, Julie; Manatschal, Gianreto; Chevrot, Sébastien; Mohn, Geoffroy

    2015-04-01

    Knowledge of magma-poor rifted margin architecture has significantly evolved over the past decades. Refraction seismic data combined with drill-hole observations unravelled the velocity structure and lithological assemblages of the most distal part of continental rifted margins. Present-day models of continental rifted margins include the occurrence of hyperextended domains consisting in extremely thinned continental crust and/or exhumed subcontinental mantle as described at many rifted margins. Studies in mountain belts revealed that remnants of hyperextended domains could also be identified in internal parts of collisional orogens. Integrating recent developments in the understanding of rifted margins in the study of mountain building processes, in particular the importance of the reactivation of inherited rift structures is therefore essential and may result in alternative interpretations of the lithospheric scale structure of collisional orogens. In this contribution, we focus on the western part of the Pyrenean orogen that resulted from the inversion of a complex Late Jurassic to Mid Cretaceous rift system. The transition from preserved oceanic and rift domains to the west (in the offshore Bay of Biscay) to their complete inversion in the east provides simultaneous access to seismically imaged and exposed parts of a hyperextended rift system. Based on a multi-scale dataset that combines sub-surface data (field and drill-hole observations) with tomographic imaging (PYROPE experiment) and integrating new concepts derived from the study of present-day rifted margins, we investigate the lithospheric-scale architecture of the Western Pyrenees. Our results suggest that the imaged north-dipping crustal root may correspond to the former exhumed mantle and hyperthinned domains that have been subducted/underthrust at the onset of convergence. This interpretation contrasts with the classical assumption that the crustal root is made of lower crustal rocks. This

  18. High Latitude Meridional Flow on the Sun May Explain North-South Polar Field Asymmetry

    NASA Technical Reports Server (NTRS)

    Kosak, Katie; Upton, Lisa; Hathaway, David

    2012-01-01

    We measured the flows of magnetic elements on the Sun at very high latitudes by analyzing magnetic images from the Helioseismic and Magnetic Imager (HMI) on the NASA Solar Dynamics Observatory (SDO) Mission. Magnetic maps constructed using a fixed, and north-south symmetric, meridional flow profile give weaker than observed polar fields in the North and stronger than observed polar fields in the South during the decline of Cycle 23 and rise of Cycle 24. Our measurements of the meridional flow at high latitudes indicate systematic north-south differences. In the fall of 2010 (when the North Pole was most visible), there was a strong flow in the North while in the spring of 2011 (when the South Pole was most visible) the flow there was weaker. With these results, we have a possible solution to this polar field asymmetry. The weaker flow in the South should keep the polar fields from becoming too strong while the stronger flow in the North should strengthen the field there. In order to gain a better understanding of the Solar Cycle and magnetic flux transport on the Sun, we need further observations and analyses of the Sun s polar regions in general and the polar meridional flow in particular.

  19. Temporal variations of particle fluxes in the deep subtropical and tropical North Atlantic - Eulerian versus Lagrangian effects

    NASA Technical Reports Server (NTRS)

    Deuser, W. G.; Muller-Karger, F. E.; Hemleben, C.

    1988-01-01

    The flux of particles measured by sediment traps in the deep water of the Sargasso Sea and western tropical North Atlantic undergoes pronounced temporal variation. In the Sargasso Sea the variability is largely due to seasonal changes in mixed-layer depth and attendant changes in primary productivity affecting a wide region. By contrast, the variability in the western tropical Atlantic appears to be caused by patches of elevated nutrient and pigment concentrations which have their origin in the plumes of the Amazon and Orinoco rivers. Coastal zone color scanner scenes demonstrate the great seasonal and interannual differences in the direction and dispersal patterns of the plumes. The river plumes break up into irregular patches which may pass through the catchment area of a sediment trap at varying rates, thereby creating the impression of almost random temporal flux variability at a fixed trap site.

  20. The GISMO two-millimeter deep field in GOODS-N

    SciTech Connect

    Staguhn, Johannes G.; Kovács, Attila; Arendt, Richard G.; Benford, Dominic J.; Dwek, Eli; Fixsen, Dale J.; Jhabvala, Christine A.; Maher, Stephen F.; Miller, Timothy M.; Moseley, S. Harvey; Sharp, Elmer H.; Wollack, Edward J.; Decarli, Roberto; Walter, Fabian; Hilton, Gene C.; Irwin, Kent D.; Karim, Alexander; Leclercq, Samuel

    2014-07-20

    We present deep continuum observations using the GISMO camera at a wavelength of 2 mm centered on the Hubble Deep Field in the GOODS-N field. These are the first deep field observations ever obtained at this wavelength. The 1σ sensitivity in the innermost ∼4' of the 7' diameter map is ∼135 μJy beam{sup –1}, a factor of three higher in flux/beam sensitivity than the deepest available SCUBA 850 μm observations, and almost a factor of four higher in flux/beam sensitivity than the combined MAMBO/AzTEC 1.2 mm observations of this region. Our source extraction algorithm identifies 12 sources directly, and another 3 through correlation with known sources at 1.2 mm and 850 μm. Five of the directly detected GISMO sources have counterparts in the MAMBO/AzTEC catalog, and four of those also have SCUBA counterparts. HDF850.1, one of the first blank-field detected submillimeter galaxies, is now detected at 2 mm. The median redshift of all sources with counterparts of known redshifts is z-tilde =2.91±0.94. Statistically, the detections are most likely real for five of the seven 2 mm sources without shorter wavelength counterparts, while the probability for none of them being real is negligible.

  1. The GISMO Two-millimeter Deep Field in GOODS-N

    NASA Astrophysics Data System (ADS)

    Staguhn, Johannes G.; Kovács, Attila; Arendt, Richard G.; Benford, Dominic J.; Decarli, Roberto; Dwek, Eli; Fixsen, Dale J.; Hilton, Gene C.; Irwin, Kent D.; Jhabvala, Christine A.; Karim, Alexander; Leclercq, Samuel; Maher, Stephen F.; Miller, Timothy M.; Moseley, S. Harvey; Sharp, Elmer H.; Walter, Fabian; Wollack, Edward J.

    2014-07-01

    We present deep continuum observations using the GISMO camera at a wavelength of 2 mm centered on the Hubble Deep Field in the GOODS-N field. These are the first deep field observations ever obtained at this wavelength. The 1σ sensitivity in the innermost ~4' of the 7' diameter map is ~135 μJy beam-1, a factor of three higher in flux/beam sensitivity than the deepest available SCUBA 850 μm observations, and almost a factor of four higher in flux/beam sensitivity than the combined MAMBO/AzTEC 1.2 mm observations of this region. Our source extraction algorithm identifies 12 sources directly, and another 3 through correlation with known sources at 1.2 mm and 850 μm. Five of the directly detected GISMO sources have counterparts in the MAMBO/AzTEC catalog, and four of those also have SCUBA counterparts. HDF850.1, one of the first blank-field detected submillimeter galaxies, is now detected at 2 mm. The median redshift of all sources with counterparts of known redshifts is \\tilde{z} = 2.91+/- 0.94. Statistically, the detections are most likely real for five of the seven 2 mm sources without shorter wavelength counterparts, while the probability for none of them being real is negligible.

  2. North Pecan Island field: a mature trend discovery in Miocene of southern Louisiana

    SciTech Connect

    Bauer, A.G.; McCormick, J.A.

    1985-02-01

    The Exxon 1 M.J. Epley discovery well for North Pecan Island field was completed in early 1982 as a discovery of significant new gas and condensate reserves in the mature Miocene trend of south Louisiana. The field is located in Vermilion Parish within a large megablock between 2 major down-to-the basin growth-fault systems and is on the southern end of a south-plunging structural nose. Traps in 2 fault segments are formed in southeasterly dipping beds upthrown to 2 north dipping, sealing faults. Six separate Robulus chambersi sandstones contain gas and condensate reserves. Major gas and condensate reserves from sandstone reservoirs in the R. chambersi section were discovered in the mid-1960s 3.3 mi. west in the Pecan island field and in the North Freshwater Bayou field, 5 mi northeast of the North Pecan Island field discovery. Several earlier dry holes just north of the discovery were drilled seeking to extend production from the upstructure Fire Island field (3 mi north), which produced a limited amount of gas and condensate from R. chambersi sandstones. Extensive structural and isopach mapping, aided by new high-resolution seismic data, revealed the North Pecan Island prospect to be structural high to production at Pecan Island and that the prospective section was deposited over a growing paleostructure. Four wells have been completed to date in the field, with flow rates as high as 30 MMCFGB. Current estimates place the new field recoverable at approximately 250 bcf of gas and 6 million bbl condensate.

  3. Insights into North Atlantic deep water formation during the peak interglacial interval of Marine Isotope Stage 9 (MIS 9)

    NASA Astrophysics Data System (ADS)

    Mokeddem, Zohra; McManus, Jerry F.

    2017-01-01

    Foraminifera abundance and stable isotope records from ODP Site 984 (61.25°N, 24.04°W, 1648 m) in the North Atlantic are used to reconstruct surface circulation variations and the relative strength of the North Atlantic Deep Water (NADW) formation over the period spanning the peak warmth of Marine Interglacial Stage (MIS) 9e ( 324-336 ka). This interval includes the preceding deglaciation, Termination 4 (T4), and the subsequent glacial inception of MIS 9d. The records indicate a greatly reduced contribution of NADW during T4, as observed in more recent deglaciations. In contrast with the most recent deglaciation, the lack of a significant NADW signal extended from T4 well into the peak interglacial MIS 9e and persisted nearly until the transition to the subsequent glacial stage MIS 9d. Although NADW formation resumed during MIS 9e, only depths greater than 2000 m appear to have been ventilated. The poorly ventilated intermediate depth of Site 984 (<2000 m) may have resulted on one hand from a general reduction of deep water ventilation by NADW during the study interval or, on the other hand, from different pathways of the spread of newly formed NADW that bypassed the study location. The intermediate depths may have also been invaded by southern-sourced waters as the formation of intermediate depth NADW weakened. The absence of any significant NADW signal at the water depth of Site 984 during the climatic optimum contrasts sharply with subsequent interglacial peaks (MIS 5e and the Holocene). Despite the perturbed intermediate depth circulation, oceanic heat transport northeastward was not interrupted and may have contributed to the relatively mild interglacial conditions of MIS 9e.

  4. Potential field modelling of palaeozoic sediments, intrusions and orogenic structures in the southern part of the Danish North Sea.

    NASA Astrophysics Data System (ADS)

    Lyngsie, S. B.; Thybo, H.

    2003-04-01

    Palaeozoic sediments cover the entire Danish area and vary considerably in depth and thickness (less than 0.5 s twt on the 'Kattegat Skagerak Platform' to more than 1.5 s twt on the 'Ringkøbing Fyn High' (RFH), and up to 2-3 s twt in the deep basins). The Palaeozoic interval and orogenic structures of the crystalline crust are modelled by integrating reflection seismic data and potential field data in the southern part of the Danish Central Graben (CG) Area and the RFH. Using a variety of transformation and imaging methods the potential field data from the North Sea are analysed for shallow and deep-seated orogenic structures. By integrating a depth-converted section of the MONA LISA 3 profile with potential field data extracted along the profile, excellent control on the gravity and magnetic modelling is obtained with 2 1/2 D modelling using the program GM-SYS. The modelled profile indicates a strongly block faulted RFH covered by a thick (> 3 km) Palaeozoic sequence and vertical and horizontal intrusions beneath the CG and in the crystalline crust of the RFH. A 3D modelling method is used to calculate the gravity effects of seawater and all sediments of post Early Permian age in the CG area and the RFH area. The residual gravity image clearly supports the results of the modelled profile by revealing evidence of intrusions in the crust beneath CG and the RFH. Velocity modelling based on wide-angle refraction data, supports the indication of the presence of down faulted Palaeozoic sediments. Correlation of several deep seismic reflection profiles indicates internal orogenic crustal structures, probably of pre-Caledonian age, in areas adjacent to RFH.

  5. The diversity, distribution and status of deep-water elasmobranchs in the Rockall Trough, north-east Atlantic Ocean.

    PubMed

    Neat, F C; Burns, F; Jones, E; Blasdale, T

    2015-12-01

    Data from a scientific deep-water trawl fisheries survey in the north-east Atlantic were analysed to determine the spatial and bathymetric distribution of elasmobranch species and assess the change in relative abundance over the period 1998-2013. During this period, commercial fisheries for deep-water sharks went from being entirely unregulated, to being briefly managed, to being completely prohibited. A total of 22 species of shark and 10 species of skate were recorded between depths of 300 and 2030 m. All showed strong species-specific depth-related trends in abundance. Out of the 11 more common species, five showed no change in relative abundance over time, two (Centrophorus squamosus and Centroselachus crepidater) declined significantly and four increased in relative abundance (Apristurus aphyodes, Apristurus microps, Galeus melastomus and Deania calcea). Assuming these populations were depleted by fisheries in the past, the current data do not suggest there has been an overall recovery. Positive signs for some species in the most recent years suggest movement or recruitment back into the area; however, it is of concern that two species continued to decline. There is a continued need to have precautionary management of these elasmobranch species, and the current ban on landing these species in European waters remains appropriate.

  6. NeQuick 2 total electron content predictions for middle latitudes of North American region during a deep solar minimum

    NASA Astrophysics Data System (ADS)

    Ezquer, R. G.; Scidá, L. A.; Migoya Orué, Y. O.; Lescano, G. E.; Alazo-Cuartas, K.; Cabrera, M. A.; Radicella, S. M.

    2017-02-01

    The performance of NeQuick 2 model in computing the vertical total electron content (VTEC) over a wide region placed at middle latitudes of North America during the deep solar minimum that occurred in 2008 has been checked. The long term relationship between EUV irradiance and F10.7 solar flux has changed markedly during the cycle 23/24 minimum with EUV levels decreasing more than expected from F10.7 proxy. A decrease of ionization in the ionosphere could have occurred. Thus, it could be expected that the models overestimate the value of ionospheric parameters for that deep solar minimum. For this study a high density VTEC data grid that covers the Continental United States (CONUS) has been compared with monthly median maps constructed with NeQuick 2. The results show that NeQuick 2 generally gives good predictions for the region which lies between 35°N to 50°N suggesting that nothing exceptional was happening during the 2008 minimum in terms of VTEC NeQuick 2's predictive capabilities. Taking into account that the modeled value is obtained by integration in height of the electron density profile, NeQuick2 would be assuming an inadequate profile for the few highest deviations observed, between 30°N and 35°N. Overall, the model does not give significant overestimation of VTEC as could be expected.

  7. Near-UV Sources in the Hubble Ultra Deep Field: The Catalog

    NASA Technical Reports Server (NTRS)

    Gardner, Jonathan P.; Voyrer, Elysse; de Mello, Duilia F.; Siana, Brian; Quirk, Cori; Teplitz, Harry I.

    2009-01-01

    The catalog from the first high resolution U-band image of the Hubble Ultra Deep Field, taken with Hubble s Wide Field Planetary Camera 2 through the F300W filter, is presented. We detect 96 U-band objects and compare and combine this catalog with a Great Observatories Origins Deep Survey (GOODS) B-selected catalog that provides B, V, i, and z photometry, spectral types, and photometric redshifts. We have also obtained Far-Ultraviolet (FUV, 1614 Angstroms) data with Hubble s Advanced Camera for Surveys Solar Blind Channel (ACS/SBC) and with Galaxy Evolution Explorer (GALEX). We detected 31 sources with ACS/SBC, 28 with GALEX/FUV, and 45 with GALEX/NUV. The methods of observations, image processing, object identification, catalog preparation, and catalog matching are presented.

  8. Spontaneous and Widespread Electricity Generation in Natural Deep-Sea Hydrothermal Fields.

    PubMed

    Yamamoto, Masahiro; Nakamura, Ryuhei; Kasaya, Takafumi; Kumagai, Hidenori; Suzuki, Katsuhiko; Takai, Ken

    2017-05-15

    Deep-sea hydrothermal vents discharge abundant reductive energy into oxidative seawater. Herein, we demonstrated that in situ measurements of redox potentials on the surfaces of active hydrothermal mineral deposits were more negative than the surrounding seawater potential, driving electrical current generation. We also demonstrated that negative potentials in the surface of minerals were widespread in the hydrothermal fields, regardless of the proximity to hydrothermal fluid discharges. Lab experiments verified that the negative potential of the mineral surface was induced by a distant electron transfer from the hydrothermal fluid through the metallic and catalytic properties of minerals. These results indicate that electric current is spontaneously and widely generated in natural mineral deposits in deep-sea hydrothermal fields. Our discovery provides important insights into the microbial communities that are supported by extracellular electron transfer and the prebiotic chemical and metabolic evolution of the ocean hydrothermal systems. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Complexity in Matuyama-Brunhes polarity transitions from North Atlantic IODP/ODP deep-sea sites

    NASA Astrophysics Data System (ADS)

    Channell, J. E. T.

    2017-06-01

    Integrated Ocean Drilling Program (IODP) Expedition 303 to the North Atlantic provided 16 records of the Matuyama-Brunhes polarity transition (MBT), based on u-channel and discrete samples, from holes drilled at three sites (Sites U1304, U1305 and U1306) that have mean Brunhes sedimentation rates of 16-18 cm/kyr. The MBT occurs during the transition from marine isotope stage (MIS) 19c to MIS 18e, with mid-point at ∼773 ka, and a transition duration of ∼8 kyr. Combining the new MBT records, including one new record for the top Jaramillo, with previously published North Atlantic MBT records (ODP Sites 983, 984 and 1063) yields a total of more than 20 high-sedimentation-rate polarity transition records. The MBT yields a repetitive pattern of transitional field states as virtual geomagnetic poles (VGPs) move from high southern latitudes to loop over the Pacific, group in NE Asia, and transit into the mid-latitude South Atlantic before reaching high latitudes in the Northern Hemisphere. The VGPs for the top Jaramillo transition feature a loop over the Pacific, then a NE Asia group before transit over the Indian Ocean to high southerly latitudes. The North Atlantic MBT records described here contrast with longitudinally-constrained VGP paths for the MBT, indicating that relatively low sedimentation rate (∼4 cm/kyr) records of the MBT are heavily smoothed by the remanence acquisition process and do not adequately represent the MBT field. The VGPs at the MBT and top Jaramillo, as measured in the North Atlantic, have similarities with excursion (Iceland Basin) VGP paths, and were apparently guided by maxima in downward vertical flux similar to those seen in the modern non-dipole (ND) field, implying longevity in ND features through time.

  10. Probing the Epoch of Reionization with the Hubble Ultra Deep Field

    NASA Astrophysics Data System (ADS)

    Stiavelli, M.; Fall, S. M.; Panagia, N.

    2004-12-01

    We derive the expected properties of reionization sources with very low metallicity and show how the z=6 galaxies identified as i-band dropouts in the Hubble Ultra Deep Field and in the GOODS survey would be capable of reionizing the Universe provided their metallicity is very low and/or their mass function is top heavy. We discuss possible alternatives to that of a very low metallicity and how some of these alternatives could be tested with observations.

  11. Reconstructing 7000 years of North Atlantic hurricane variability using deep-sea sediment cores from the western Great Bahama Bank

    NASA Astrophysics Data System (ADS)

    Toomey, Michael R.; Curry, William B.; Donnelly, Jeffrey P.; van Hengstum, Peter J.

    2013-01-01

    overwash records from coastal barrier systems document significant variability in North Atlantic hurricane activity during the late Holocene. The same climate forcings that may have controlled cyclone activity over this interval (e.g., the West African Monsoon, El Niño-Southern Oscillation (ENSO)) show abrupt changes around 6000 yrs B.P., but most coastal sedimentary records do not span this time period. Establishing longer records is essential for understanding mid-Holocene patterns of storminess and their climatic drivers, which will lead to better forecasting of how climate change over the next century may affect tropical cyclone frequency and intensity. Storms are thought to be an important mechanism for transporting coarse sediment from shallow carbonate platforms to the deep-sea, and bank-edge sediments may offer an unexplored archive of long-term hurricane activity. Here, we develop this new approach, reconstructing more than 7000 years of North Atlantic hurricane variability using coarse-grained deposits in sediment cores from the leeward margin of the Great Bahama Bank. High energy event layers within the resulting archive are (1) broadly correlated throughout an offbank transect of multi-cores, (2) closely matched with historic hurricane events, and (3) synchronous with previous intervals of heightened North Atlantic hurricane activity in overwash reconstructions from Puerto Rico and elsewhere in the Bahamas. Lower storm frequency prior to 4400 yrs B.P. in our records suggests that precession and increased NH summer insolation may have greatly limited hurricane potential intensity, outweighing weakened ENSO and a stronger West African Monsoon—factors thought to be favorable for hurricane development.

  12. Primary experimental study on safety of deep brain stimulation in RF electromagnetic field.

    PubMed

    Jun, Xu; Luming, Li; Hongwei, Hao

    2009-01-01

    With the rapid growth of clinical application of Deep Brain Stimulation, its safety and functional concern in the electromagnetic field, another pollution becoming much more serious, has become more and more significant. Meanwhile, the measuring standards on Electromagnetic Compatibility (EMC) for DBS are still incomplete. Particularly, the knowledge of the electromagnetic field induced signals on the implanted lead is ignorant while some informal reports some side effects. This paper briefly surmised the status of EMC standards on implantable medical devices. Based on the EMC experiments of DBS device we developed, two experiments for measuring the induced voltage of the deep brain stimulator in RF electromagnetic field were reported. The measured data showed that the induced voltage in some frequency was prominent, for example over 2V. As a primary research, we think these results would be significant to cause researcher to pay more attention to the EMC safety problem and biological effects of the induced voltage in deep brain stimulation and other implantable devices.

  13. Deep rooting conferred by DEEPER ROOTING 1 enhances rice yield in paddy fields

    PubMed Central

    Arai-Sanoh, Yumiko; Takai, Toshiyuki; Yoshinaga, Satoshi; Nakano, Hiroshi; Kojima, Mikiko; Sakakibara, Hitoshi; Kondo, Motohiko; Uga, Yusaku

    2014-01-01

    To clarify the effect of deep rooting on grain yield in rice (Oryza sativa L.) in an irrigated paddy field with or without fertilizer, we used the shallow-rooting IR64 and the deep-rooting Dro1-NIL (a near-isogenic line homozygous for the Kinandang Patong allele of DEEPER ROOTING 1 (DRO1) in the IR64 genetic background). Although total root length was similar in both lines, more roots were distributed within the lower soil layer of the paddy field in Dro1-NIL than in IR64, irrespective of fertilizer treatment. At maturity, Dro1-NIL showed approximately 10% higher grain yield than IR64, irrespective of fertilizer treatment. Higher grain yield of Dro1-NIL was mainly due to the increased 1000-kernel weight and increased percentage of ripened grains, which resulted in a higher harvest index. After heading, the uptake of nitrogen from soil and leaf nitrogen concentration were higher in Dro1-NIL than in IR64. At the mid-grain-filling stage, Dro1-NIL maintained higher cytokinin fluxes from roots to shoots than IR64. These results suggest that deep rooting by DRO1 enhances nitrogen uptake and cytokinin fluxes at late stages, resulting in better grain filling in Dro1-NIL in a paddy field in this study. PMID:24988911

  14. [Book review] Lichens of the north woods: a field guide to 111 northern species, by Joe Walewski

    USGS Publications Warehouse

    Bennett, J.

    2007-01-01

    Review of: LICHENS OF THE NORTH WOODS, A FIELD GUIDE TO 111 NORTHERN SPECIES. Joe Walewski. 2007. North Woods Naturalist Series, Kollath & Stensaas Publishing, Duluth, Minnesota. 152 pp, softcover. ISBN: 0-9673793-50. $18.95.

  15. Experience of cathodic protection, fabrication and installation of anodes for deep water pipelines in the North Sea and the Norwegian Sea

    SciTech Connect

    Eliassen, S.; Pettersen, N.H.

    1996-08-01

    Statoil is the major operator of the oil and gas pipelines in the North Sea and the Norwegian Sea. Different coating systems have been used for external corrosion protection of the pipelines. The paper presents the company`s experience regarding cathodic protection design and fabrication and installation of anodes for deep water pipelines.

  16. High Latitude Meridional Flow on the Sun May Explain North-South Polar Field Asymmetry

    NASA Technical Reports Server (NTRS)

    Kosak, Katie; Upton, Lisa; Hathaway, David

    2012-01-01

    We measured the flows of magnetic elements on the Sun at very high latitudes by analyzing magnetic images from the Helioseismic and Magnetic Imager (HMI) on the NASA Solar Dynamics Observatory (SDO) Mission. Magnetic maps constructed using a fixed, and north-south symmetric, meridional flow profile give weaker than observed polar fields in the North and stronger than observed polar fields in the South during the decline of Cycle 23 and rise of Cycle 24. Our measurements of the meridional flow at high latitudes indicate systematic north-south differences. There was a strong flow in the North while the flow in the South was weaker. With these results, we have a possible solution to the polar field asymmetry. The weaker flow in the South should keep the polar fields from becoming too strong while the stronger flow in the North should strengthen the field there. In order to gain a better understanding of the Solar Cycle and magnetic flux transport on the Sun, we need further observations and analyses of the Sun's polar regions in general and the polar meridonal flow in particular.

  17. High Latitude Meridional Flow on the Sun May Explain North-South Polar Field Asymmetry

    NASA Technical Reports Server (NTRS)

    Kosak, Katie; Upton, Lisa; Hathaway, David

    2012-01-01

    We measured the flows of magnetic elements on the Sun at very high latitudes by analyzing magnetic images from the Helioseismic and Magnetic Imager (HMI) on the NASA Solar Dynamics Observatory (SDO) Mission. Magnetic maps constructed using a fixed, and north ]south symmetric, meridional flow profile give weaker than observed polar fields in the North and stronger than observed polar fields in the South during the decline of Cycle 23 and rise of Cycle 24. Our measurements of the meridional flow at high latitudes indicate systematic north ]south differences. There was a strong flow in the North while the flow in the South was weaker. With these results, we have a possible solution to the polar field asymmetry. The weaker flow in the South should keep the polar fields from becoming too strong while the stronger flow in the North should strengthen the field there. In order to gain a better understanding of the Solar Cycle and magnetic flux transport on the Sun, we need further observations and analyses of the Sun fs polar regions in general and the polar meridional flow in particular

  18. Neutralizing Carbonic Acid in Deep Carbonate Strata below the North Atlantic

    SciTech Connect

    Daniel P. Schrag

    2005-12-01

    Our research is aimed at investigating several technical issues associated with carbon dioxide sequestration in calcium carbonate sediments below the sea floor through laboratory experiments and chemical transport modeling. Our goal is to evaluate the basic feasibility of this approach, including an assessment of optimal depths, sediment types, and other issues related to site selection. Through laboratory and modeling efforts, we are studying the flow of liquid carbon dioxide and carbon dioxide-water mixtures through calcium carbonate sediments to better understand the geomechanical and structural stability of the sediments during and after injection. Our modeling efforts in the first year show that the idea is feasible, but requires more sophisticated analysis of fluid flow at high pressure in deep sea sediments. In addition, we are investigating the kinetics of calcium carbonate dissolution in the presence of CO{sub 2}-water fluids, which is a critical feature of the system as it allows for increased permeability during injection. Our experimental results from the first year of work have shown that the kinetics are likely to be fast enough to create dissolution which will affect permeability. However, additional experiments are needed at high pressures, which will be a focus for years 2 and 3. We are also investigating the possibility of carbon dioxide hydrate formation in the pore fluid, which might complicate the injection procedure by reducing sediment permeability but might also provide an upper seal in the sediment-pore fluid system, preventing release of CO{sub 2} into the deep ocean, particularly if depth and temperature at the injection point rule out immediate hydrate formation. Finally, we are in the beginning stages of an economic analysis to estimate costs of drilling and gas injection, site monitoring as well as the availability of potential disposal sites with particular emphasis on those sites that are within the 200-mile economic zone of the

  19. Deriving Deep Ocean Temperature Changes From the Ambient Acoustic Noise Field

    NASA Astrophysics Data System (ADS)

    Sambell, K.; Evers, L. G.; Snellen, M.

    2016-12-01

    Passively deriving the deep ocean temperature is a challenge. However, knowledge about changes in the deep ocean temperature are important in relation to climate change. In-situ observations are are and satellite observations are hardly applicable. Low-frequency sound waves of a few hertz can penetrate the deep oceans over long distances. As their propagation is temperature dependent, these waves contain valuable information that can be used for temperature monitoring. In this study, the use of interferometry is demonstrated by applying this technique to ambient noise measured at two hydrophone arrays located near Robinson Crusoe Island in the South Pacific Ocean. The arrays are separated by 40 km and are located at a depth of 800 m. Both arrays consist of three hydrophones with an interstation distance of 2 km. It is shown that the acoustic velocity, and with this the temperature variation, can be derived from measured hydro-acoustic data. Furthermore, the findings are supported by ocean models that describe the propagation of sound between the hydrophone arrays. This study shows the potential of using the ambient noise field for temperature monitoring in the deep ocean.

  20. Characterizing, modelling and understanding the climate variability of the deep water formation in the North-Western Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Somot, Samuel; Houpert, Loic; Sevault, Florence; Testor, Pierre; Bosse, Anthony; Taupier-Letage, Isabelle; Bouin, Marie-Noelle; Waldman, Robin; Cassou, Christophe; Sanchez-Gomez, Emilia; Durrieu de Madron, Xavier; Adloff, Fanny; Nabat, Pierre; Herrmann, Marine

    2016-08-01

    Observing, modelling and understanding the climate-scale variability of the deep water formation (DWF) in the North-Western Mediterranean Sea remains today very challenging. In this study, we first characterize the interannual variability of this phenomenon by a thorough reanalysis of observations in order to establish reference time series. These quantitative indicators include 31 observed years for the yearly maximum mixed layer depth over the period 1980-2013 and a detailed multi-indicator description of the period 2007-2013. Then a 1980-2013 hindcast simulation is performed with a fully-coupled regional climate system model including the high-resolution representation of the regional atmosphere, ocean, land-surface and rivers. The simulation reproduces quantitatively well the mean behaviour and the large interannual variability of the DWF phenomenon. The model shows convection deeper than 1000 m in 2/3 of the modelled winters, a mean DWF rate equal to 0.35 Sv with maximum values of 1.7 (resp. 1.6) Sv in 2013 (resp. 2005). Using the model results, the winter-integrated buoyancy loss over the Gulf of Lions is identified as the primary driving factor of the DWF interannual variability and explains, alone, around 50 % of its variance. It is itself explained by the occurrence of few stormy days during winter. At daily scale, the Atlantic ridge weather regime is identified as favourable to strong buoyancy losses and therefore DWF, whereas the positive phase of the North Atlantic oscillation is unfavourable. The driving role of the vertical stratification in autumn, a measure of the water column inhibition to mixing, has also been analyzed. Combining both driving factors allows to explain more than 70 % of the interannual variance of the phenomenon and in particular the occurrence of the five strongest convective years of the model (1981, 1999, 2005, 2009, 2013). The model simulates qualitatively well the trends in the deep waters (warming, saltening, increase in the

  1. EMPIRICAL PREDICTIONS FOR (SUB-)MILLIMETER LINE AND CONTINUUM DEEP FIELDS

    SciTech Connect

    Da Cunha, Elisabete; Walter, Fabian; Decarli, Roberto; Rix, Hans-Walter; Bertoldi, Frank; Carilli, Chris; Daddi, Emanuele; Elbaz, David; Sargent, Mark; Maiolino, Roberto; Riechers, Dominik; Smail, Ian; Weiss, Axel

    2013-03-01

    Modern (sub-)millimeter/radio interferometers such as ALMA, JVLA, and the PdBI successor NOEMA will enable us to measure the dust and molecular gas emission from galaxies that have luminosities lower than the Milky Way, out to high redshifts and with unprecedented spatial resolution and sensitivity. This will provide new constraints on the star formation properties and gas reservoir in galaxies throughout cosmic times through dedicated deep field campaigns targeting the CO/[C II] lines and dust continuum emission in the (sub-)millimeter regime. In this paper, we present empirical predictions for such line and continuum deep fields. We base these predictions on the deepest available optical/near-infrared Advanced Camera for Surveys and NICMOS data on the Hubble Ultra Deep Field (over an area of about 12 arcmin{sup 2}). Using a physically motivated spectral energy distribution model, we fit the observed optical/near-infrared emission of 13,099 galaxies with redshifts up to z = 5, and obtain median-likelihood estimates of their stellar mass, star formation rate, dust attenuation, and dust luminosity. We combine the attenuated stellar spectra with a library of infrared emission models spanning a wide range of dust temperatures to derive statistical constraints on the dust emission in the infrared and (sub-)millimeter which are consistent with the observed optical/near-infrared emission in terms of energy balance. This allows us to estimate, for each galaxy, the (sub-)millimeter continuum flux densities in several ALMA, PdBI/NOEMA, and JVLA bands. As a consistency check, we verify that the 850 {mu}m number counts and extragalactic background light derived using our predictions are consistent with previous observations. Using empirical relations between the observed CO/[C II] line luminosities and the infrared luminosity of star-forming galaxies, we infer the luminosity of the CO(1-0) and [C II] lines from the estimated infrared luminosity of each galaxy in our sample

  2. Empirical Predictions for (Sub-)millimeter Line and Continuum Deep Fields

    NASA Astrophysics Data System (ADS)

    da Cunha, Elisabete; Walter, Fabian; Decarli, Roberto; Bertoldi, Frank; Carilli, Chris; Daddi, Emanuele; Elbaz, David; Ivison, Rob; Maiolino, Roberto; Riechers, Dominik; Rix, Hans-Walter; Sargent, Mark; Smail, Ian; Weiss, Axel

    2013-03-01

    Modern (sub-)millimeter/radio interferometers such as ALMA, JVLA, and the PdBI successor NOEMA will enable us to measure the dust and molecular gas emission from galaxies that have luminosities lower than the Milky Way, out to high redshifts and with unprecedented spatial resolution and sensitivity. This will provide new constraints on the star formation properties and gas reservoir in galaxies throughout cosmic times through dedicated deep field campaigns targeting the CO/[C II] lines and dust continuum emission in the (sub-)millimeter regime. In this paper, we present empirical predictions for such line and continuum deep fields. We base these predictions on the deepest available optical/near-infrared Advanced Camera for Surveys and NICMOS data on the Hubble Ultra Deep Field (over an area of about 12 arcmin2). Using a physically motivated spectral energy distribution model, we fit the observed optical/near-infrared emission of 13,099 galaxies with redshifts up to z = 5, and obtain median-likelihood estimates of their stellar mass, star formation rate, dust attenuation, and dust luminosity. We combine the attenuated stellar spectra with a library of infrared emission models spanning a wide range of dust temperatures to derive statistical constraints on the dust emission in the infrared and (sub-)millimeter which are consistent with the observed optical/near-infrared emission in terms of energy balance. This allows us to estimate, for each galaxy, the (sub-)millimeter continuum flux densities in several ALMA, PdBI/NOEMA, and JVLA bands. As a consistency check, we verify that the 850 μm number counts and extragalactic background light derived using our predictions are consistent with previous observations. Using empirical relations between the observed CO/[C II] line luminosities and the infrared luminosity of star-forming galaxies, we infer the luminosity of the CO(1-0) and [C II] lines from the estimated infrared luminosity of each galaxy in our sample. We then

  3. Development of the Endicott field (Kekiktuk Formation), North Slope, Alaska

    SciTech Connect

    Metzger, R.R.; St. Aubin, L.A. )

    1991-03-01

    Endicott field, located 2 mi offshore in the Arctic Ocean, produces approximately 100 MBPD from Mississippian Kekiktuk Formation fluvial sands. The field is the first Arctic offshore development. Currently 65 wells have been drilled from two man-made gravel drilling and production islands. Production started in 1987 and 77 MMBO have been produced to date. Original volumes in place are estimated at 1 BSTB, 365 bcf of gas cap gas, and 750 bcf of solution gas. The Kekiktuk Formation, deposited by a southerly flowing fluvial system in response to the Ellesmerian orogeny, rests unconformably on Franklinian (Devonian) basement. The field is a combined structural/stratigraphic trap and is delineated by three major normal faults. Within the field, the Endicott Group sediments are truncated by the regional Lower Cretaceous Unconformity (LCU). A reservoir seal is provided by the overlying conformable Itkilyariak Formation carbonates and Cretaceous shales above the LCU. Due to complex reservoir geometry, a subzone approach to reservoir development, surveillance, and management has been implemented. Structural dip combined with continuous interbedded shales and sealing intrareservoir faults divide the reservoir into six separate hydrologic subzones. Additionally, structural dip creates narrow oil corridors in each reservoir subzone. All development wells are within {approximately}1500 ft of the updip gas cap and downdip aquifer. The high priority placed on incorporating reservoir description with surveillance data has resulted in optimal field management and minimized development risk.

  4. Nitrogen Cycling In The Deep Subsurface Underlying Oligotrophic Open Ocean Regions: Metagenomic Analyses of North Pond Sediment Microbial Communities

    NASA Astrophysics Data System (ADS)

    Ziebis, W.

    2016-12-01

    Recent research of the deep ocean floor underlying open ocean regions in the Atlantic and Pacific has revealed that oxygen penetrates several tens of meters into the sediment column from the overlying water. And, in contrast to the better-studied continental margin setting, nitrate also persists within these organic-poor sediments throughout the sediment column. Moreover, in places where seawater flows through the basaltic crust, it has been shown that oxygen diffuses upward into the overlying sediment, creating an oxic sediment layer above the basalt. The flanks of the Mid-Atlantic Ridge are characterized by sediment-filled depressions that are surrounded by a steep topography of basaltic outcrops, which are the conduits for low-temperature hydrothermally driven seawater circulation through the basaltic basement. IODP Expedition 336 targeted North Pond, one of such sediment ponds. 3 sites were drilled which varied in sediment thickness from about 90 m (U1382B, U1384A) to 40 m (U1383D/E). Oxygen penetrated deeply into the sediment column from the overlying water (30 m) and diffused upward from the basaltic basement to several meters (10 - 20 m) above the basalt. Aerobic respiration created an anoxic zone in the middle of the sediment column. Concurrently, nitrate accumulated above bottom seawater concentrations to up to 50 µM. Previous investigations, using a stable isotope approach, showed an active subsurface nitrogen cycle. We obtained samples from all 3 drilling sites and selected 10 samples from the oxic upper layer, the upper suboxic transition zone, the anoxic middle, the lower suboxic zone and the deep oxic layer above the basalt for detailed analyses. We extracted intact cells from large volumes of sediment (1 L) using a density centrifugation approach for amplicon (16s rRNA) and metagenome sequencing, with the goal to characterize the phylogenetic and functional gene inventory in these different sediment layers. We will provide first results on the deep

  5. Quantification of deep percolation from two flood-irrigated alfalfa field, Roswell Basin, New Mexico

    USGS Publications Warehouse

    Roark, D. Michael; Healy, D.F.

    1998-01-01

    For many years water management in the Roswell ground-water basin (Roswell Basin) and other declared basins in New Mexico has been the responsibility of the State of New Mexico. One of the water management issues requiring better quantification is the amount of deep percolation from applied irrigation water. Two adjacent fields, planted in alfalfa, were studied to determine deep percolation by the water-budget, volumetric-moisture, and chloride mass-balance methods. Components of the water-budget method were measured, in study plots called borders, for both fields during the 1996 irrigation season. The amount of irrigation water applied in the west border was 95.8 centimeters and in the east border was 169.8 centimeters. The total amount of precipitation that fell during the irrigation season was 21.9 centimeters. The increase in soil-moisture storage from the beginning to the end of the irrigation season was 3.2 centimeters in the west border and 8.8 centimeters in the east border. Evapotranspiration, as estimated by the Bowen ratio energy balance technique, in the west border was 97.8 centimeters and in the east border was 101.0 centimeters. Deep percolation determined using the water-budget method was 16.4 centimeters in the west border and 81.6 centimeters in the east border. An average deep percolation of 22.3 centimeters in the west border and 31.6 centimeters in the east border was determined using the volumetric-moisture method. The chloride mass-balance method determined the multiyear deep percolation to be 15.0 centimeters in the west border and 38.0 centimeters in the east border. Large differences in the amount of deep percolation between the two borders calculated by the water-budget method are due to differences in the amount of water that was applied to each border. More water was required to flood the east border because of the greater permeability of the soils in that field and the smaller rate at which water could be applied.

  6. A MULTIWAVELENGTH STUDY OF TADPOLE GALAXIES IN THE HUBBLE ULTRA DEEP FIELD

    SciTech Connect

    Straughn, Amber N.; Eufrasio, Rafael T.; Gardner, Jonathan P.; Voyer, Elysse N.; Mello, Duilia de; Soto, Emmaris; Petty, Sara; Kassin, Susan; Ravindranath, Swara

    2015-12-01

    Multiwavelength data are essential in order to provide a complete picture of galaxy evolution and to inform studies of galaxies’ morphological properties across cosmic time. Here we present the results of a multiwavelength investigation of the morphologies of “tadpole” galaxies at intermediate redshift (0.314 < z < 3.175) in the Hubble Ultra Deep Field. These galaxies were previously selected from deep Hubble Space Telescope (HST) F775W data based on their distinct asymmetric knot-plus-tail morphologies. Here we use deep Wide Field Camera 3 near-infrared imaging in addition to the HST optical data in order to study the rest-frame UV/optical morphologies of these galaxies across the redshift range 0.3 < z < 3.2. This study reveals that the majority of these galaxies do retain their general asymmetric morphology in the rest-frame optical over this redshift range, if not the distinct “tadpole” shape. The average stellar mass of tadpole galaxies is lower than that of field galaxies, with the effect being slightly greater at higher redshift within the errors. Estimated from spectral energy distribution fits, the average age of tadpole galaxies is younger than that of field galaxies in the lower-redshift bin, and the average metallicity is lower (whereas the specific star formation rate for tadpoles is roughly the same as field galaxies across the redshift range probed here). These average effects combined support the conclusion that this subset of galaxies is in an active phase of assembly, either late-stage merging or cold gas accretion causing localized clumpy star formation.

  7. An Analysis of Near Fields of 34m Antennas of JPL/NASA Deep Space Network

    NASA Technical Reports Server (NTRS)

    Jamnejad, Vahraz; Juan, Nuria Llombart

    2011-01-01

    This paper addresses the issue of calculating near fields of the 34m Beam Waveguide (BWG) antennas of the NASA/JPL Deep Space Network (DSN). Calculating the near fields of DSN antennas are of interest in receive mode where the transmitting signals from nearby flying objects such as helicopters and airplanes could interfere with the operation of sensitive RF receiving system of DSN antennas, and in the transmit mode where fields from high-powered DSN antennas interfere with receivers on nearby flying objects, as well as safety considerations for the operators and visitors to the grounds surrounding the antenna sites. A complete and detailed analysis has been performed using PO/PTD techniques, including surface errors and support struts effects. Some results are presented, including comparisons with preliminary field tests.

  8. CTEPP: RECRUITING AND FIELD SAMPLING IN NORTH CAROLINA AND OHIO

    EPA Science Inventory

    The research field study (CTEPP) of approximately 260 preschool children's exposures to persistent organic pollutants in their everyday environments began in early 2000. CTEPP is a multimedia study of the children's aggregate (total) exposures over a 48-hr period, both at thei...

  9. CTEPP: RECRUITING AND FIELD SAMPLING IN NORTH CAROLINA AND OHIO

    EPA Science Inventory

    The research field study (CTEPP) of approximately 260 preschool children's exposures to persistent organic pollutants in their everyday environments began in early 2000. CTEPP is a multimedia study of the children's aggregate (total) exposures over a 48-hr period, both at thei...

  10. The most distant galaxy clusters in the SPT Spitzer Deep Field Survey

    NASA Astrophysics Data System (ADS)

    Rettura, Alessandro; Stanford, S. A.; Stern, D.; Mei, S.; Brodwin, M.; Gonzalez, A. H.; Gettings, D.; Ashby, M.; Bartlett, J.; Rosati, P.

    2014-01-01

    We present a sample of more than 300 galaxy cluster candidates at z>1.3 selected within 94 deg2 from the Spitzer SPT Deep Field (SSDF) survey. To discover distant clusters at z>1.3, we have used a three-filter algorithm based upon Spitzer/IRAC color ([3.6]-[4.5]>-0.1,AB) combined with a non-detection in shallow optical data. Our sample is selected to be a complete stellar mass-limited sample at z>1.3 and therefore has a well defined survey volume. The uniqueness of SSDF resides not just in its area, one of the very largest with Spitzer, but also in its coverage by deep observations for the Sunyaev-Zel'dovich (SZ) effect with the South Pole Telescope (SPT). Deeper observations are also planned with the new SPT camera, SPTpol, that will reach, for the first time, SZ clusters up to 2 (George et al., 2012). This field also has deep X-ray observations from the XMM XXL Survey (Pierre et al., 2012). Thanks to this rich data set, we will be able to determine accurate cluster masses for the vast majority of our SSDF clusters at 1.3

  11. Alignments of Radio Sources in the GMRT ELAIS N1 Deep Field

    NASA Astrophysics Data System (ADS)

    Jagannathan, Preshanth; Taylor, R.

    2014-01-01

    Results of the active galactic jet position angle alignments in the ELAIS N1 Deep radio survey are presented here. The ELAIS N1 deep radio survey was carried out with the Giant Meter-wave Radio Telescope at 615 MHz. The deep field is a seven pointing mosaic that covers 1.0 square degrees of the ELAIS N1 field with an average angular resolution of 5 arcsec by 5 arcsec, across the mosaic. The average sensitivity of the mosaicked image is 10 microJy/beam in Stokes I. There were 65 extended radio galaxy jets extracted from the mosaic of which 33 galaxies have redshift information available. The position angles of radio galaxy jets are expected to be uniform, but the radio galaxy jets in our sample were found to deviate from uniform distribution of positions angles to 99 percent significance level. Further testing with angular covariance reveals alignments in radio position angles, across angular scales of up to 1.8 degrees. Position angle correlations at scales of 1.8 degrees translates to a co-moving scale of 53 Mpc at a redshift of 1. These results corroborate prior evidence for large scale alignments in quasar optical polarization studies. The absence of interfering propagation effects that introduce uncertainty in optical polarization studies makes the study of radio galaxy jet position angles an attractive alternative methodology.

  12. Spatial correlation of the high intensity zone in deep-water acoustic field

    NASA Astrophysics Data System (ADS)

    Li, Jun; Li, Zheng-Lin; Ren, Yun

    2016-12-01

    The spatial correlations of acoustic field have important implications for underwater target detection and other applications in deep water. In this paper, the spatial correlations of the high intensity zone in the deep-water acoustic field are investigated by using the experimental data obtained in the South China Sea. The experimental results show that the structures of the spatial correlation coefficient at different ranges and depths are similar to the transmission loss structure in deep water. The main reason for this phenomenon is analyzed by combining the normal mode theory with the ray theory. It is shown that the received signals in the high intensity zone mainly include one or two main pulses which are contributed by the interference of a group of waterborne modes with similar phases. The horizontal-longitudinal correlations at the same receiver depth but in different high intensity zones are analyzed. At some positions, more pulses are received in the arrival structure of the signal due to bottom reflection and the horizontal-longitudinal correlation coefficient decreases accordingly. The multi-path arrival structure of receiving signal becomes more complex with increasing receiver depth. Project supported by the National Natural Science Foundation of China (Grant Nos. 11434012 and 41561144006).

  13. Contamination by field late-M, L, and T dwarfs in deep surveys

    NASA Astrophysics Data System (ADS)

    Caballero, J. A.; Burgasser, A. J.; Klement, R.

    2008-09-01

    Context: Deep photometric surveys of substellar objects in young clusters and high-redshift quasars are affected by contaminant sources at different heliocentric distances. If not correctly taken into account, the contamination may have a strong effect on the Initial Mass Function determination and on the identification of quasars. Aims: We calculate in detail the back- and foreground contamination by field dwarfs of very late spectral types (intermediate and late M, L, and T) in deep surveys and provide the data and tools for the computation. Methods: We adopt the latest models and data from the literature, which include the following: (i) a model of the Galactic thin disc by an exponential law; (ii) the length and height scales of late-type dwarfs; and (iii) the local spatial densities, absolute magnitudes, and colours of dwarfs for each spectral type. Results: We derive a simplified expression for the spatial density in the thin disc that depends on the heliocentric distance and the galactic coordinates (l, b) and integrate this into the truncated cone studied in the survey. As a practical application, we compute the numbers of L- and T-type field dwarfs in very deep (I = 21{-}29 mag) surveys in the direction of the young σ Orionis cluster. The increasing number of contaminants at the faintest magnitudes could inhibit the study of the opacity mass limit at M ⪉ 0.003 M_⊙ in the cluster.

  14. Optical Survey with KMTNet for Dusty Star-Forming Galaxies in the Akari Deep Field South

    NASA Astrophysics Data System (ADS)

    Jeong, Woong-Seob; Ko, Kyeongyeon; Kim, Minjin; Ko, Jongwan; Kim, Sam; Pyo, Jeonghyun; Kim, Seong Jin; Kim, Taehyun; Seo, Hyun Jong; Park, Won-Kee; Park, Sung-Joon; Kim, Min Gyu; Kim, Dong Jin; Cha, Sang-Mok; Lee, Yongseok; Lee, Chung-Uk; Kim, Seung-Lee; Matsuura, Shuji; Pearson, Chris; Matsuhara, Hideo

    2016-10-01

    We present an optical imaging survey of AKARI Deep Field South (ADF-S) using the Korea Microlensing Telescope Network (KMTNet), to find optical counterparts of dusty star-forming galaxies. The ADF-S is a deep far-infrared imaging survey region with AKARI covering around 12 deg^2, where the deep optical imaging data are not yet available. By utilizing the wide-field capability of the KMTNet telescopes (˜4 deg^2), we obtain optical images in B, R and I bands for three regions. The target depth of images in B, R and I bands is ˜24 mag (AB) at 5σ, which enables us to detect most dusty star-forming galaxies discovered by AKARI in the ADF-S. Those optical datasets will be helpful to constrain optical spectral energy distributions as well as to identify rare types of dusty star-forming galaxies such as dust-obscured galaxy, sub-millimeter galaxy at high redshift.}

  15. Deep-subwavelength imaging of both electric and magnetic localized optical fields by plasmonic campanile nanoantenna

    SciTech Connect

    Caselli, Niccolò; La China, Federico; Bao, Wei; Riboli, Francesco; Gerardino, Annamaria; Li, Lianhe; Linfield, Edmund H.; Pagliano, Francesco; Fiore, Andrea; Schuck, P. James; Cabrini, Stefano; Weber-Bargioni, Alexander; Gurioli, Massimo; Intonti, Francesca

    2015-06-05

    Tailoring the electromagnetic field at the nanoscale has led to artificial materials exhibiting fascinating optical properties unavailable in naturally occurring substances. Besides having fundamental implications for classical and quantum optics, nanoscale metamaterials provide a platform for developing disruptive novel technologies, in which a combination of both the electric and magnetic radiation field components at optical frequencies is relevant to engineer the light-matter interaction. Thus, an experimental investigation of the spatial distribution of the photonic states at the nanoscale for both field components is of crucial importance. Here we experimentally demonstrate a concomitant deep-subwavelength near-field imaging of the electric and magnetic intensities of the optical modes localized in a photonic crystal nanocavity. We take advantage of the “campanile tip”, a plasmonic near-field probe that efficiently combines broadband field enhancement with strong far-field to near-field coupling. In conclusion, by exploiting the electric and magnetic polarizability components of the campanile tip along with the perturbation imaging method, we are able to map in a single measurement both the electric and magnetic localized near-field distributions.

  16. Deep-subwavelength imaging of both electric and magnetic localized optical fields by plasmonic campanile nanoantenna.

    PubMed

    Caselli, Niccolò; La China, Federico; Bao, Wei; Riboli, Francesco; Gerardino, Annamaria; Li, Lianhe; Linfield, Edmund H; Pagliano, Francesco; Fiore, Andrea; Schuck, P James; Cabrini, Stefano; Weber-Bargioni, Alexander; Gurioli, Massimo; Intonti, Francesca

    2015-06-05

    Tailoring the electromagnetic field at the nanoscale has led to artificial materials exhibiting fascinating optical properties unavailable in naturally occurring substances. Besides having fundamental implications for classical and quantum optics, nanoscale metamaterials provide a platform for developing disruptive novel technologies, in which a combination of both the electric and magnetic radiation field components at optical frequencies is relevant to engineer the light-matter interaction. Thus, an experimental investigation of the spatial distribution of the photonic states at the nanoscale for both field components is of crucial importance. Here we experimentally demonstrate a concomitant deep-subwavelength near-field imaging of the electric and magnetic intensities of the optical modes localized in a photonic crystal nanocavity. We take advantage of the "campanile tip", a plasmonic near-field probe that efficiently combines broadband field enhancement with strong far-field to near-field coupling. By exploiting the electric and magnetic polarizability components of the campanile tip along with the perturbation imaging method, we are able to map in a single measurement both the electric and magnetic localized near-field distributions.

  17. Deep-subwavelength imaging of both electric and magnetic localized optical fields by plasmonic campanile nanoantenna

    DOE PAGES

    Caselli, Niccolò; La China, Federico; Bao, Wei; ...

    2015-06-05

    Tailoring the electromagnetic field at the nanoscale has led to artificial materials exhibiting fascinating optical properties unavailable in naturally occurring substances. Besides having fundamental implications for classical and quantum optics, nanoscale metamaterials provide a platform for developing disruptive novel technologies, in which a combination of both the electric and magnetic radiation field components at optical frequencies is relevant to engineer the light-matter interaction. Thus, an experimental investigation of the spatial distribution of the photonic states at the nanoscale for both field components is of crucial importance. Here we experimentally demonstrate a concomitant deep-subwavelength near-field imaging of the electric and magneticmore » intensities of the optical modes localized in a photonic crystal nanocavity. We take advantage of the “campanile tip”, a plasmonic near-field probe that efficiently combines broadband field enhancement with strong far-field to near-field coupling. In conclusion, by exploiting the electric and magnetic polarizability components of the campanile tip along with the perturbation imaging method, we are able to map in a single measurement both the electric and magnetic localized near-field distributions.« less

  18. Deep-subwavelength imaging of both electric and magnetic localized optical fields by plasmonic campanile nanoantenna

    PubMed Central

    Caselli, Niccolò; La China, Federico; Bao, Wei; Riboli, Francesco; Gerardino, Annamaria; Li, Lianhe; Linfield, Edmund H.; Pagliano, Francesco; Fiore, Andrea; Schuck, P. James; Cabrini, Stefano; Weber-Bargioni, Alexander; Gurioli, Massimo; Intonti, Francesca

    2015-01-01

    Tailoring the electromagnetic field at the nanoscale has led to artificial materials exhibiting fascinating optical properties unavailable in naturally occurring substances. Besides having fundamental implications for classical and quantum optics, nanoscale metamaterials provide a platform for developing disruptive novel technologies, in which a combination of both the electric and magnetic radiation field components at optical frequencies is relevant to engineer the light-matter interaction. Thus, an experimental investigation of the spatial distribution of the photonic states at the nanoscale for both field components is of crucial importance. Here we experimentally demonstrate a concomitant deep-subwavelength near-field imaging of the electric and magnetic intensities of the optical modes localized in a photonic crystal nanocavity. We take advantage of the “campanile tip”, a plasmonic near-field probe that efficiently combines broadband field enhancement with strong far-field to near-field coupling. By exploiting the electric and magnetic polarizability components of the campanile tip along with the perturbation imaging method, we are able to map in a single measurement both the electric and magnetic localized near-field distributions. PMID:26045401

  19. Deep-Sea Field Studies of the Biological Consequences of Direct Ocean CO2 Sequestration

    NASA Astrophysics Data System (ADS)

    Barry, J. P.; Seibel, B. A.; Lovera, C.

    2001-12-01

    While the notion of carbon sequestration by direct ocean disposal of CO2 in the deep ocean holds promise for mitigating atmospheric greenhouse warming, the consequences of this approach for deep-sea ecosystems are understood poorly, but are potentially large. Several factors suggest that deep-sea fauna may be more sensitive to deep-sea CO2 releases than related groups inhabiting the upper ocean. The evolution of deep-sea species in the relatively invariant environment of the deep ocean has likely led to the intolerance of many species to perturbations in seawater chemistry associated with direct CO2 injection (e.g. pH reduction) that may be more tolerable to shallow-living groups. Food limitation and reduced metabolic rates typical in deep-sea ecosystems may also limit the ability of many organisms to tolerate changes in pH (i.e. pH compensation) or CO2 (e.g. metabolic depression). We recently performed field experiments at depths from 3000 to 3600 m to evaluate the biological responses of representative deep-sea organisms to changes in seawater chemistry caused by carbon dioxide sequestration. Several small pools (ca. 15 l) of liquid CO2 were deployed on the seafloor from the ROV Tiburon operated by the Monterey Bay Aquarium Research Institute, using a novel CO2 release system. Rates of survival and aspects of the physiological condition of various elements of the seafloor faunal community were compared between sites near (<1 m) and distant (control sites >30 m away) from CO2 pools. Tidally oscillating currents swept a plume of CO2-rich water away from the pools as the liquid CO2 dissolved, resulting in periodic reductions of pH around the pools to 6.0 to 7.0 units within 1 m. Rates of survival for two common megafaunal echinoderms (echinoid 1 and holothurian 1) held in cages adjacent to CO2 pools were very low compared were compared to control sites. Decalcification of urchin spines and skeletal elements was evident for animals near CO2 pools. The abundances of

  20. Neutralizing Carbonic Acid in Deep Carbonate Strata below the North Atlantic

    SciTech Connect

    Daniel P. Schrag

    2006-07-14

    Our research is aimed at investigating several technical issues associated with carbon dioxide sequestration in calcium carbonate sediments below the sea floor through laboratory experiments and chemical transport modeling. Our goal is to evaluate the basic feasibility of this approach, including an assessment of optimal depths, sediment types, and other issues related to site selection. The results of our modeling efforts were published this past summer in the Proceedings of the National Academy of Sciences. We are expanding on that work through a variety of laboratory and modeling efforts. In the laboratories at Columbia and at Harvard, we are studying the flow of liquid carbon dioxide and carbon dioxide-water mixtures through calcium carbonate sediments to better understand the geomechanical and structural stability of the sediments during and after injection. We are currently preparing the results of these findings for publication. In addition, we are investigating the kinetics of calcium carbonate dissolution in the presence of CO{sub 2}-water fluids, which is a critical feature of the system as it allows for increased permeability during injection. We are also investigating the possibility of carbon dioxide hydrate formation in the pore fluid, which might complicate the injection procedure by reducing sediment permeability but might also provide an upper seal in the sediment-pore fluid system, preventing release of CO{sub 2} into the deep ocean, particularly if depth and temperature at the injection point rule out immediate hydrate formation. This is done by injecting liquid CO{sub 2} into various types of porous media, and then monitoring the changes in permeability. Finally, we are performing an economic analysis to estimate costs of drilling and gas injection, site monitoring as well as the availability of potential disposal sites with particular emphasis on those sites that are within the 200-mile economic zone of the United States. We present some

  1. Deep Vadose Zone-Applied Field Research Initiative Fiscal Year 2011 Annual Report

    SciTech Connect

    Wellman, Dawn M.; Johnson, Timothy C.; Smith, Ronald M.; Truex, Michael J.; Matthews, Hope E.

    2011-10-01

    This annual report describes the background of the Deep Vadose Zone-Applied Field Research Initiative, and some of the programmatic approaches and transformational technologies in groundwater and deep vadose zone remediation developed during fiscal year 2011. The Department of Energy (DOE) Office of Technology Innovation and Development's (OTID) mission is to transform science into viable solutions for environmental cleanup. In 2010, OTID developed the Impact Plan, Science and Technology to Reduce the Life Cycle Cost of Closure to outline the benefits of research and development of the lifecycle cost of cleanup across the DOE complex. This plan outlines OTID's ability to reduce by $50 billion, the $200 billion life-cycle cost in waste processing, groundwater and soil, nuclear materials, and deactivation and decommissioning. The projected life-cycle costs and return on investment are based on actual savings realized from technology innovation, development, and insertion into remedial strategies and schedules at the Fernald, Mound, and Ashtabula sites. To achieve our goals, OTID developed Applied Field Research Initiatives to facilitate and accelerate collaborative development and implementation of new tools and approaches that reduce risk, cost and time for site closure. The primary mission of the Deep Vadose Zone-Applied Field Research Initiative (DVZ-AFRI) is to protect our nation's water resources, keeping them clean and safe for future generations. The DVZ-AFRI was established for the DOE to develop effective, science-based solutions for remediating, characterizing, monitoring, and predicting the behavior and fate of deep vadose zone contamination. Subsurface contaminants include radionuclides, metals, organics, and liquid waste that originated from various sources, including legacy waste from the nation's nuclear weapons complexes. The DVZ-AFRI project team is translating strategy into action by working to solve these complex challenges in a collaborative

  2. Reservoir compartmentalization of deep-water Intra Qua Iboe sand (Pliocene), Edop field, offshore Nigeria

    SciTech Connect

    Hermance, W.E.; Olaifa, J.O.; Shanmugam, G.

    1995-08-01

    An integration of 3-D seismic and sedimentological information provides a basis for recognizing and mapping individual flow units within the Intra Qua Iboe (IQI) reservoir (Pliocene), Edop Field, offshore Nigeria. Core examination show the following depositional facies: A-Sandy slump/mass flow, B-Muddy slump/mass flow, C. Bottom current reworking. D-Non-channelized turbidity currents, E. Channelized (coalesced) turbidity currents. F-Channelized (isolated) turbidity currents, G-Pelagic/hemipelagic, H-Levee, I-Reworked slope, J-Wave dominated, and K-Tide dominated facies. With the exception of facies J and K, all these facies are of deep-water affinity. The IQI was deposited on an upper slope environment in close proximity to the shelf edge. Through time, as the shelf edge migrated scaward, deposition began with a channel dominated deep-water system (IQI 1 and 2) and progressed through a slump/debris flow dominated deep-water system (IQI 3, the principle reservoir) to a tide and wave dominated shallow-water system (IQI 4). Compositional and textural similarities between the deep-water facies result in similar log motifs. Furthermore, these depositional facies are not readily apparent as distinct seismic facies. Deep-water facies A, D, E, and F are reservoir facies, whereas facies B, C, G, H, and I are non-reservoir facies. However, Facies G is useful as a seismically mappable event throughout the study area. Mapping of these non-reservoir events provides the framework for understanding gross reservoir architecture. This study has resulted in seven defined reservoir units within the IQI, which serves as the architectural framework for ongoing reservoir characterization.

  3. Magma mixing in the Kalaqin core complex, northern North China Craton: Linking deep lithospheric destruction and shallow extension

    NASA Astrophysics Data System (ADS)

    Fu, Lebing; Wei, Junhao; Tan, Jun; Santosh, M.; Zhang, Daohan; Chen, Jiajie; Li, Yanjun; Zhao, Shaoqing; Peng, Lina

    2016-09-01

    The widespread Mesozoic magmatism in the North China Craton (NCC) has received considerable attention as a trigger for large scale lithospheric destruction. Here we investigate the Early Cretaceous Jiguanzi adamellite from the northern part of the NCC which is contemporaneous with shallow extensional deformation and deep lithospheric destruction. This intrusion emplaced at ca. 133 Ma is located in the foot wall of the Kalaqin metamorphic core complex (MCC), and occurs as a synextensional ring complex with numerous magmatic equigranular (Group 1) and porphyritic (Group 2) enclaves. Hornblende and plagioclase from the host adamellite and xenocrysts of Group 2 enclaves show distinct inverse zoning with Mg- and Ca-rich mantle. The Group 2 enclaves are characterized by plagioclase xenocrysts hosting hornblende, biotite and apatite inclusions, quartz ocelli with fine-grained rim enriched in biotite and hornblende, and poikilitic biotite surrounded by hornblende. Geochemically, the host intrusion is calc-alkaline to alkaline and metaluminous with variable contents of SiO2 (60.70-72.20 wt.%), Al2O3 (14.19-17.22 wt.%), Na2O + K2O (6.16-9.42 wt.%), and Mg# values (28.0-47.7), whereas the Group 2 enclaves exhibit low SiO2 (54.05-55.55 wt.%), high Fe2O3 (8.18-8.64 wt.%) and TiO2 (2.08-2.28 wt.%), and moderate Mg# (44.0-44.1). Both the host intrusion and Group 2 enclaves are enriched in large-ion lithophile and light rare earth elements, and depleted in high field strength elements and heavy rare earth elements except that the latter has lower Ba and high Nb, Ta and Ti contents. The major and trace element contents of the Group 1 enclaves are broadly similar to those of the host intrusion. Analyses of Sr-Nd-Hf isotopes in the host intrusion, and in Group 1 and Group 2 enclaves show (87Sr/86Sr)ihost = 0.70600-0.70618, εNd(t)host = - 8.2 to - 9.6, T2DM(Nd)host = 1592-1706 Ma, εHf(t)host = - 9.2 to - 12.0, (87Sr/86Sr)iGroup 1 = 0.70590-0.70635, εNd(t)Group 1 = - 9.6 to - 10

  4. Unusual Long and Luminous Optical Transient in the Subaru Deep Field

    NASA Astrophysics Data System (ADS)

    Urata, Yuji; Tsai, Patrick P.; Huang, Kuiyun; Morokuma, Tomoki; Yasuda, Naoki; Tanaka, Masaomi; Motohara, Kentaro; Hayashi, Masao; Kashikawa, Nobunari; Ly, Chun; Malkan, Matthew A.

    2012-11-01

    We present observations of SDF-05M05, an unusual optical transient discovered in the Subaru Deep Field (SDF). The duration of the transient is > ~ 800 days in the observer frame, and the maximum brightness during observation reached approximately 23 mag in the i' and z' bands. The faint host galaxy is clearly identified in all five optical bands of the deep SDF images. The photometric redshift of the host yields z ~ 0.6 and the corresponding absolute magnitude at maximum is ~ - 20. This implies that this event shone with an absolute magnitude brighter than -19 mag for approximately 300 days in the rest frame, which is significantly longer than a typical supernova and ultraluminous supernova. The total radiated energy during our observation was 1 × 1051 erg. The light curves and color evolution are marginally consistent with some luminous IIn supernovae. We suggest that the transient may be a unique and peculiar supernova at intermediate redshift.

  5. VizieR Online Data Catalog: Subaru/XMM Deep Field radio imaging. III. (Simpson+, 2012)

    NASA Astrophysics Data System (ADS)

    Simpson, C.; Rawlings, S.; Ivison, R.; Akiyama, M.; Almaini, O.; Bradshaw, E.; Chapman, S.; Chuter, R.; Croom, S.; Dunlop, J.; Foucaud, S.; Hartley, W.

    2013-03-01

    Many of the spectra presented here were obtained as part of the European Southern Observatory (ESO) programme P074.A-0333, undertaken using the Visible Multi-Object Spectrograph (VIMOS) instrument on UT3/Melipal, VIMOS. Several observational campaigns have obtained spectra of objects within the Subaru/XMM-Newton Deep Field (SXDF), and Paper II (Vardoulaki et al., 2008MNRAS.387..505V) presented spectra for 28 of the brightest 37 radio sources, obtained from a variety of sources. The near-infrared data used here come from the third data release (DR3) of the UKIRT (United Kingdom Infrared telescope) Infrared Deep Sky Survey. The optical data in the UDS come from the SXDF, which comprises five separate Suprime-Cam pointings. (1 data file).

  6. Measurements of laser-induced plasma temperature field in deep penetration laser welding

    NASA Astrophysics Data System (ADS)

    Chen, Genyu; Zhang, Mingjun; Zhao, Zhi; Zhang, Yi; Li, Shichun

    2013-02-01

    Laser-induced plasma in deep penetration laser welding is located inside or outside the keyhole, namely, keyhole plasma or plasma plume, respectively. The emergence of laser-induced plasma in laser welding reveals important information of the welding technological process. Generally, electron temperature and electron density are two important characteristic parameters of plasma. In this paper, spectroscopic measurements of electron temperature and electron density of the keyhole plasma and plasma plume in deep penetration laser welding conditions were carried out. To receive spectra from several points separately and simultaneously, an Optical Multi-channel Analyser (OMA) was developed. On the assumption that the plasma was in local thermal equilibrium, the temperature was calculated with the spectral relative intensity method. The spectra collected were processed with Abel inversion method to obtain the temperature fields of keyhole plasma and plasma plume.

  7. North Pole Marathon Laboratory Lessons and Field Success.

    PubMed

    Barwood, Martin J; Burrows, Holly; Cessford, Jessica

    2016-05-01

    This case study documents the training, laboratory preparation, and in-race performance data from Great Britain's top finisher in the 13(th) edition of the UVU North Pole Marathon. We report data from a preparatory laboratory test in simulated cold conditions (-15°C) with and without wind chill during high- and low-intensity expected 'race pace' running. These tests examined the adequacy of the selected clothing assembly and provided recommendations for the race. The tests established that there was no risk of hypothermia, as the clothing assembly provided too much insulation; terminal rectal temperature was 39.25°C. Skin temperature (Tsk) data revealed no impending risk of frostbite; nadir Tsk was 20.2°C at the hamstring. Oxygen consumption data revealed the self-selected high intensity was potentially not sustainable based on estimates of substrate utilization. We recommended: 1) a maximum running speed; 2) some of the clothing base layers could be removed pre-race; 3) vents and/or zips could be used to offload or retain heat; and 4) an even pacing profile should be adopted. The participant completed the race in 6:55:24 (h:mm:ss) in temperatures of -41°C. GPS data revealed a positive pacing template (i.e., marginally quicker in the first half). Neither hypothermia nor frostbite occurred. Peak pace from the laboratory tests was not consistently exceeded. Marathon performance can be undertaken in one of the world's most inhospitable environments when careful consideration is given to clothing insulation and exercise intensity by planning for the dynamic thermal changes that may occur as the race ensues.

  8. Field Verification of Structural Performance of Thermoplastic Pipe Under Deep Backfill Conditions

    NASA Astrophysics Data System (ADS)

    Sargand, S.

    2002-05-01

    This report provides information regarding the structural performance of thermoplastic pipes under relatively deep soil cover conditions. The eighteen (12 HDPE, 6 PVC) thermoplastic pipes, with diameter ranging from 30 to 60 in., were instrumented with sensors, embedded with granular backfill in shallow trenches, and subjected to 20-ft or 40-ft high soil fill for about 10 months. Their installation plans involved two types of backfill soil, three relative compactions, and varying bedding thickness to study the effects of these installation parameters on the pipe performance. Once the field performance of each test pipe was presented and discussed, comparative cross examinations of the entire field data were made to identify the effects of various installation parameters on the pipe deformations/deflections and soil pressure against pipe. A comprehensive set of soil testing was performed in the laboratory to characterize each of the three soil types that existed in the field. Results from the shear strength tests were analyzed further to obtain hyperbolic model parameter values for these soils. Three analytical methods (modified Iowa formula, elastic solutions, and finite element) were applied to evaluate their abilities to predict the field performance of the thermoplastic pipes under relatively deep soil cover. In their applications, material properties measured in the laboratory were utilized as much as possible.

  9. The Pan-STARRS 1 Medium Deep Field Variable Star Catalog

    NASA Astrophysics Data System (ADS)

    Flewelling, Heather

    2016-01-01

    We present the first Pan-STARRS 1 Medium Deep Field Variable Star Catalog (PS1-MDF-VSC). The Pan-STARRS 1 (PS1) telescope is a 1.8 meter survey telescope with a 1.4 Gigapixel camera, located in Haleakala, Hawaii. The Medium Deep survey, which consists of 10 fields located uniformly across the sky, totaling 70 square degrees, is observed each night, in 2-3 filters per field, with 8 exposures per filter, resulting in 3000-4000 data points per star over a time span of 3.5 years. To find the variables, we select objects with > 200 detections, and remove those flagged as saturated. No other cuts are used. There are approximately 2.4 million objects that fit this criteria, with magnitudes between 13th and 24th. These objects are then passed through a lomb-scargle fitting routine to determine periodicity. After a periodicity cut, the candidates are classified by eye into different types of variable stars. We have identified several thousand periodic variable stars, with periods ranging between a few minutes to a few days. We compare our findings to the variable star catalogs within Vizier and AAVSO. In particular, for field MD02, we recover all the variables that are faint in Vizier, and we find good agreement with the periods reported in Vizier.

  10. Deep wide-field imaging of main belt comets and asteroids

    NASA Astrophysics Data System (ADS)

    Rajagopal, Jayadev; Jewitt, David; Ridgway, Susan

    2014-02-01

    We propose to continue a deep imaging study, using the pODI optical imager on the WIYN telescope, of selected regions of the main asteroid belt that contain a known main-belt comet (MBC). An MBC is an asteroid that shows evidence of significant mass loss, seen as transient, comet- like tails and comae. In 2013, we were awarded 4 nights over the two semesters and obtained high-impact wide-field, deep images of two new MBCs, P/2010 A2 and P/2013 P5, to study their origins. In addition, we use the considerable pODI field-of-view to search for direct evidence of very low-level mass-loss activity in the sample of main belt asteroids that will also be detected. Asteroids could be repositories of primordial water and a supply for volatiles on earth. In order to test this possibility (suggested by the recent TALCS asteroid survey at CFHT) and further characterize the mass-loss in known MBC activity, we will observe ~ 25- arcminute fields around ~ 3 known MBCs to significantly deeper levels than TALCS with better resolution. More than half of the 2013A allocation was lost to weather. We request 4 nights in 2014A. With this additional time we are confident of reaching publishable results on low level mass-loss and on the evolution of the activity in known MBCs. We will follow the secular evolution of P/2010 A2. And, as in the previous two semesters, we hope to add a spectacular wide-field deep image of a new MBC.

  11. An early to mid-Pleistocene deep Arctic Ocean ostracode fauna with North Atlantic affinities

    USGS Publications Warehouse

    DeNinno, Lauren H.; Cronin, Thomas M.; Rodriquez-Lazaro, J.; Brenner, Alec R.

    2015-01-01

    An early to middle Pleistocene ostracode fauna was discovered in sediment core P1-93-AR-23 (P23, 76.95°N, 155.07°W) from 951 meter water depth from the Northwind Ridge, western Arctic Ocean. Piston core P23 yielded more than 30,000 specimens and a total of about 30 species. Several early to mid-Pleistocene species in the genera Krithe,Echinocythereis, Pterygocythereis, and Arcacythere are now extinct in the Arctic and show taxonomic affinities to North Atlantic Ocean species. Our results suggest that there was a major ostracode faunal turnover during the global climate transitions known as the Mid-Pleistocene Transition (MPT, ~ 1.2 to 0.7 Ma) and the Mid-Brunhes Event (MBE, ~ 400 ka) reflecting the development of perennial sea ice during interglacial periods and large ice shelves during glacial periods over the last 400,000 years.

  12. Ultra-deep K S-band Imaging of the Hubble Frontier Fields

    NASA Astrophysics Data System (ADS)

    Brammer, Gabriel B.; Marchesini, Danilo; Labbé, Ivo; Spitler, Lee; Lange-Vagle, Daniel; Barker, Elizbeth A.; Tanaka, Masayuki; Fontana, Adriano; Galametz, Audrey; Ferré-Mateu, Anna; Kodama, Tadayuki; Lundgren, Britt; Martis, Nicholas; Muzzin, Adam; Stefanon, Mauro; Toft, Sune; van der Wel, Arjen; Vulcani, Benedetta; Whitaker, Katherine E.

    2016-09-01

    We present an overview of the “KIFF” project, which provides ultra-deep K s -band imaging of all six of the Hubble Frontier Fields clusters, Abell 2744, MACS-0416, Abell S1063, Abell 370, MACS-0717, and MACS-1149. All of these fields have recently been observed with large allocations of Directors’ Discretionary Time with the Hubble and Spitzer telescopes, covering 0.4\\lt λ \\lt 1.6 μ {{m}} and 3.6-4.5 μ {{m}}, respectively. VLT/HAWK-I integrations of the first four fields reach 5σ limiting depths of {K}s˜ 26.0 (AB, point sources) and have excellent image quality (FWHM ˜ 0.″4). The MACS-0717 and MACS-1149 fields are observable from the northern hemisphere, and shorter Keck/MOSFIRE integrations on those fields reach limiting depths of K s = 25.5 and 25.1, with a seeing FWHM of ˜ 0.″4 and 0\\buildrel{\\prime\\prime}\\over{.} 5. In all cases the K s -band mosaics cover the primary cluster and parallel HST/ACS+WFC3 fields. The total area of the K s -band coverage is 490 arcmin2. The K s -band at 2.2 μ {{m}} crucially fills the gap between the reddest HST filter (1.6 μ {{m}} ˜ H band) and the IRAC 3.6 μ {{m}} passband. While reaching the full depths of the space-based imaging is not currently feasible from the ground, the deep K s -band images provide important constraints on both the redshifts and the stellar population properties of galaxies extending well below the characteristic stellar mass across most of the age of the universe, down to and including the redshifts of the targeted galaxy clusters (z≲ 0.5). Reduced, aligned mosaics of all six survey fields are provided.

  13. Deep Structure and Evolution of The Central Graben, North Sea: Constraints From Seismic Observations and Numerical Dynamic Modelling.

    NASA Astrophysics Data System (ADS)

    Balling, N.; Frederiksen, S.; Nielsen, L.; Nørmark, E.; Nielsen, S. B.; Jacobsen, B. H.

    The Central Graben forms the southern arm of a three-arm rift system in the North Sea, with the Viking Graben as the northern arm and the Moray Firth Basin as the western arm. It is a 70-130 km wide graben with a length of about 550 km. High qual- ity normal-incidence and wide-angle seismic data from the MONA LISA deep seismic experiment across the Central Graben show crustal thinning by a factor of 2 in areas of thickest sedimentary sequences and localized seismic reflectivity in the upper mantle dipping away from the deepest parts of the graben. A numerical dynamic lithospheric model with significant Triassic and Late Jurassic extensional phases as well as Mid- dle Jurassic thermal doming accounts for the observed up to 8 km of Late Permian to Cenozoic sediments in the deepest parts of the Graben, for most of the observed lateral thickness variation of sedimentary formations and is consistent with both the deep-seismic data, present-day heat-flow and gravity data. The detailed crustal model produced by joint inverse modelling of seimic refraction data and gravity data shows a distinct thinning of the crust and local elevation of Moho by up to 5 km in a 40 km narrow zone below areas of thick upper Jurassic sediments. This Moho structure suggests that a relatively shallow and otherwise strong uppermost mantle has been interrupted, perhaps by mantle shear zones induced by strain softening as in our nu- merical model. The integrated seismic observational and numerical modelling results indicate that an initially pure-shear donimated extensional regime changed into an ex- tensional regime where simple shear played an important part with mantle shear zones developed during the Late Jurassic extension.

  14. Imaging the deep electrical conductivity structure of the Rennick Graben (North Victoria Land, Antartide)

    NASA Astrophysics Data System (ADS)

    Armadillo, E.; Tabellario, G.; Bozzo, E.; Caneva, G.

    2003-04-01

    A preliminary interpretation of the electrical conductivity structures beneath the Rennick Graben is presented based on Geomagnetic Depth Soundings (GDS) carried out the BACKTAM expedition (1999/2000). The Rennick Graben is the most important Cenozoic tectonics structure of NVL, a region of dominating NW-SE trending dextral slip. Its formation is framed in the contest of Austalia-Antarctica spreading and its study is fundamental to understanding the recent Meso-Cenozoic tectonics. The GDS provides a view on the internal conductivity distribution, of a region of interest, from measurements of the geomagnetic transient variations at discrete geographical points. In the initial stages of data processing, an advanced robust regression technique proposed by Egbert and Booker (1986), is applied to derive transfer functions used to diagnose the lateral conductivity distribution in the study region. The presentation of the transfer functions in the form of induction arrow helps to identify regions of enhanced conductivity. In this study we have considered the shorter periods, in the range 20-170 s, that are suitable to crustal investigations. The qualitative analysis of the induction arrows reveals an approximately 2D regional electrical conductivity pattern with a clear differentation between the three Terrains crossed by the GDS transect: the Robertson Bay, the Bowers and the Wilson Terrain. For the two dimensional inversion of our data set we have adopted the efficient variant of Siripunvaraporn and Egbert (2000) of the Occam inversion approach. Two dimensional models reveal a deep electrical conductivity anomaly (approximately 20-50 km) on the east side of the Rennick. Lateral discontinuities seem to be related with the Leap Year Fault and the Lanterman Fault on the east and the Daniels Range on the west.

  15. Early Pliocene closing of the Indonesian Seaway: evidence from north-east Indian Ocean and Tropical Pacific deep sea cores

    NASA Astrophysics Data System (ADS)

    Srinivasan, M. S.; Sinha, D. K.

    1998-04-01

    Deep sea cores from sites 214 and 758 A (Ninetyeast Ridge, north-east Indian Ocean), 761 B (Wombat Plateau, north-east Indian Ocean) and 586 B (Ontong Java Plateau, Tropical Pacific) are ideally located for comparison of late Neogene planktic foraminiferal biogeography and paleoceanographic records of tropical Indian and Pacific oceans to infer the timing of closing of the Indonesian Seaway. A consistent stratigraphy was developed between sites 214 and 586 B using graphic correlation and was integrated with the paleomagnetic time scale of Berggren et al. (1985) to provide an accurate chronology to compare interocean stratigraphic ranges of late Neogene planktic foraminifera. Tropical planktic foraminifera occur throughout each sequence at all sites. At each site the Miocene-Pliocene boundary is defined by the first appearance of Globorotalia tumida (5.2 Ma), the early/late Pliocene boundary by the first appearance of Globigerinoides fistulosus (3.2 Ma) and the Pliocene-Pleistocene boundary by the last appearance of G. fistulosus (1.6 Ma). Neogene planktic foraminiferal assemblages at sites 214, 758A, 761 B and 586B are generally similar until the beginning of the Pliocene (5.2 Ma) when the faunal record indicates divergence. A notable difference is complete absence of early Pliocene taxon Pulleniatina spectabilis from all the Indian Ocean sites. This difference suggests that the Indonesian Seaway became an effective biogeographic barrier to planktic foraminifera at the beginning of the Pliocene. However, there is still exchange of surface waters through this Seaway. Earlier studies suggested a Middle to Late Miocene occurrence for this biogeographic barrier. P. spectabilis evolved from P. primalis in the equatorial Pacific at about 5.2 Ma. It is a short-ranging early Pliocene species spanning about 1.3 my and occurred only in Pacific, unlike earlier suggestions of a broader distribution into the Indian Ocean.

  16. Origin of north Queensland Cenozoic volcanism: Relationships to long lava flow basaltic fields, Australia

    NASA Astrophysics Data System (ADS)

    Sutherland, F. L.

    1998-11-01

    A plume model proposed for north Queensland late Cenozoic volcanism and long lava flow distribution combines basalt ages with recent seismic studies of Australia's mantle, regional stress fields, and plate motion. Several basalt fields overlie mantle "thermal" anomalies, and other fields outside these anomalies can be traced to them through past lithospheric motion. Elsewhere, anomalies close to Australia's eastern rift margin show little volcanism, probably due to gravity-enhanced compression. Since final collision of north Queensland with New Guinea, areas of basaltic volcanism have developed over 10 Myr, and episodes appear to migrate southward from 15° to 20°S. Long lava flows increase southward as area/volume of fields increases, but topography, vent distributions, and uplifts play a role. This is attributed to magmatic plume activation within a tensional zone, as lithosphere moves over mantle thermal anomalies. The plume model predicts peak magmatism under the McBride field, coincident with the Undara long lava flow and that long lava flow fields will erupt for another 5-10 Myr. Queensland's movement over a major N-S thermal system imparts a consistent isotopic signature to its northern younger basalts, distinct to basalts from older or more southern thermal systems. Australia's motion toward this northern thermal system will give north Queensland fields continued vigorous volcanism, in contrast to the Victorian field which is leaving its southern thermal system.

  17. An Organochronology and Deep History of a North Carolina Tidal Marsh

    NASA Astrophysics Data System (ADS)

    Morris, J. T.; Kemp, A.; Horton, B.

    2016-12-01

    Tidal marshes have survived for millennia in a dynamic equilibrium with sea level. A record of their history can be found in the sediments underlying modern marshes. Since the industrial revolution the rate of relative sea-level rise has been increasing and the equilibrium is changing. To reconstruct the history of these marshes we analyzed a 1000 year record of soil organic matter content (SOM) from Tump Point, Cedar Island, North Carolina. SOM concentration is a function of the standing biomass at the time of its creation, its subsequent preservation, and annual input of inorganic matter. SOM and inorganic concentration determine the soil bulk density and volume. The standing biomass, sediment organic matter input, and consequent carbon sequestration are functions of hydroperiod or, by proxy, the paleo-marsh elevation (PME) below mean high water. The annual input of inorganic matter is determined by the depth, duration, and frequency of flooding, concentration of total suspended solids (TSS), and settling velocity. Using an inverse modeling technique we were able to solve the Marsh Equilibrium Model (MEM) for PME and relative sea level that would have resulted in the observed SOM chronologies. The TSS was inferred from the accretion rates derived from dated core sections. Consistent with foraminifera-derived relative sea-level reconstructions, the MEM-derived rate of SLR doubled after 1700 CE compared with the previous 900 years, and the PME has declined and is approaching the lower limit of the vegetation. We estimate that C-sequestration prior to 1260 varied between 15 and 40 (average 30) g C m-2 y-1, but has since declined to a range of 5 to 33 (average 16) g C m-2 y-1. The decline in carbon sequestration can be attributed to the acceleration in rate of sea-level rise and is a trend that probably will characterize most tidal wetlands in the future.

  18. Monitoring Microseismicity in a Carbonate Oil Field, North Oman

    NASA Astrophysics Data System (ADS)

    El-Hussain, I.; Al-Lazki, A.; Al-Hashmi, S.; Al-Toubi, K.; Al-Shijbi, Y.; Al-Saifi, M.; Al-Kindy, F.; Ibi, O.

    2006-12-01

    Microseismicity was monitored continuously for 2003 and 2004 years using shallow downhole seismic network in a carbonate oil field in Northern Oman. A total of 406 microearthquake events were analyzed to assess events location relative to producing horizons. The depth of the microearthquakes ranges from 0 to 2.95 km below the ground surface. The events location is confined to the carbonate reservoir boundary and temporally correlates well with the gas production, total fluid productions and water injection for the 2003 year. There is no temporal correlation between oil production and seismic activity for the 2003. Direct month to month temporal correlation is not apparent between any of oil, gas, fluid productions/water injections and the microseismic activity for the 2004 year. However, a strong temporal correlation between gas production and the number of events and an improved correlation between the oil production and the number of events were obtained when applying a time lag of one month. The focal plane solutions for the largest events in the 2003 indicate normal faulting with extensional stress is in the NW-SE directions. The spatial and temporal distribution of seismic events in the carbonate field fit the characteristics of reservoir induced seismicity and the triggering mechanism can be explained by the Mohr envelope criterion. This indicates that the reservoir layers are critically stressed and the pore pressure is changing at variable rate.

  19. Relationship between neural activation and electric field distribution during deep brain stimulation.

    PubMed

    Åström, Mattias; Diczfalusy, Elin; Martens, Hubert; Wårdell, Karin

    2015-02-01

    Models and simulations are commonly used to study deep brain stimulation (DBS). Simulated stimulation fields are often defined and visualized by electric field isolevels or volumes of tissue activated (VTA). The aim of the present study was to evaluate the relationship between stimulation field strength as defined by the electric potential V, the electric field E, and the divergence of the electric field ∇(2) V, and neural activation. Axon cable models were developed and coupled to finite-element DBS models in three-dimensional (3-D). Field thresholds ( VT , ET, and ∇(2) VT ) were derived at the location of activation for various stimulation amplitudes (1 to 5 V), pulse widths (30 to 120 μs), and axon diameters (2.0 to 7.5 μm). Results showed that thresholds for VT and ∇(2) VT were highly dependent on the stimulation amplitude while ET were approximately independent of the amplitude for large axons. The activation field strength thresholds presented in this study may be used in future studies to approximate the VTA during model-based investigations of DBS without the need of computational axon models.

  20. Comparative metagenomics reveals insights into the deep-sea adaptation mechanism of the microorganisms in Iheya hydrothermal fields.

    PubMed

    Wang, Hai-Liang; Sun, Li

    2017-05-01

    In this study, comparative metagenomic analysis was performed to investigate the genetic profiles of the microbial communities inhabiting the sediments surrounding Iheya North and Iheya Ridge hydrothermal fields. Four samples were used, which differed in their distances from hydrothermal vents. The results showed that genes involved in cell surface structure synthesis, polyamine metabolism and homeostasis, osmoadaptation, pH and Na(+) homeostasis, and heavy-metal transport were abundant. Pathways for putrescine and spermidine synthesis and transport were identified in the four metagenomes, which possibly participate in the regulation of cytoplasmic pH. Genes involved in the transport of K(+) and the biosynthesis of glycine betaine, proline, and trehalose, together with genes encoding mechanosensitive channel of small conductance, were contributors of osmoadaptation. Detection of genes encoding F1Fo-ATPase and cation/proton antiporters indicated critical roles played by pH and sodium homeostasis. Cu(2+)-exporting and Cd(2+)/Zn(2+)-exporting ATPases functioned in the expulsion of toxic metals across cellular membranes. It is noteworthy that the distribution of some genes, such as that encoding cardiolipin synthase, was apparently affected by distance to the vent site. These findings provide insight into microbial adaptation mechanisms in deep-sea sediment environments.

  1. Rhythms and community dynamics of a hydrothermal tubeworm assemblage at main endeavour field - a multidisciplinary deep-sea observatory approach.

    PubMed

    Cuvelier, Daphne; Legendre, Pierre; Laes, Agathe; Sarradin, Pierre-Marie; Sarrazin, Jozée

    2014-01-01

    The NEPTUNE cabled observatory network hosts an ecological module called TEMPO-mini that focuses on hydrothermal vent ecology and time series, granting us real-time access to data originating from the deep sea. In 2011-2012, during TEMPO-mini's first deployment on the NEPTUNE network, the module recorded high-resolution imagery, temperature, iron (Fe) and oxygen on a hydrothermal assemblage at 2186 m depth at Main Endeavour Field (North East Pacific). 23 days of continuous imagery were analysed with an hourly frequency. Community dynamics were analysed in detail for Ridgeia piscesae tubeworms, Polynoidae, Pycnogonida and Buccinidae, documenting faunal variations, natural change and biotic interactions in the filmed tubeworm assemblage as well as links with the local environment. Semi-diurnal and diurnal periods were identified both in fauna and environment, revealing the influence of tidal cycles. Species interactions were described and distribution patterns were indicative of possible microhabitat preference. The importance of high-resolution frequencies (<1 h) to fully comprehend rhythms in fauna and environment was emphasised, as well as the need for the development of automated or semi-automated imagery analysis tools.

  2. Deep Imaging of the HCG 95 Field. I. Ultra-diffuse Galaxies

    NASA Astrophysics Data System (ADS)

    Shi, Dong Dong; Zheng, Xian Zhong; Zhao, Hai Bin; Pan, Zhi Zheng; Li, Bin; Zou, Hu; Zhou, Xu; Guo, KeXin; An, Fang Xia; Li, Yu Bin

    2017-09-01

    We present a detection of 89 candidates of ultra-diffuse galaxies (UDGs) in a 4.9 degree2 field centered on the Hickson Compact Group 95 (HCG 95) using deep g- and r-band images taken with the Chinese Near Object Survey Telescope. This field contains one rich galaxy cluster (Abell 2588 at z = 0.199) and two poor clusters (Pegasus I at z = 0.013 and Pegasus II at z = 0.040). The 89 candidates are likely associated with the two poor clusters, giving about 50–60 true UDGs with a half-light radius {r}{{e}}> 1.5 {kpc} and a central surface brightness μ (g,0)> 24.0 mag arcsec‑2. Deep z\\prime -band images are available for 84 of the 89 galaxies from the Dark Energy Camera Legacy Survey (DECaLS), confirming that these galaxies have an extremely low central surface brightness. Moreover, our UDG candidates are spread over a wide range in g ‑ r color, and ∼26% are as blue as normal star-forming galaxies, which is suggestive of young UDGs that are still in formation. Interestingly, we find that one UDG linked with HCG 95 is a gas-rich galaxy with H i mass 1.1× {10}9 M ⊙ detected by the Very Large Array, and has a stellar mass of {M}\\star ∼ 1.8× {10}8 M ⊙. This indicates that UDGs at least partially overlap with the population of nearly dark galaxies found in deep H i surveys. Our results show that the high abundance of blue UDGs in the HCG 95 field is favored by the environment of poor galaxy clusters residing in H i-rich large-scale structures.

  3. The Chandra Deep Field South as a test case for Global Multi Conjugate Adaptive Optics

    NASA Astrophysics Data System (ADS)

    Portaluri, E.; Viotto, V.; Ragazzoni, R.; Gullieuszik, M.; Bergomi, M.; Greggio, D.; Biondi, F.; Dima, M.; Magrin, D.; Farinato, J.

    2017-04-01

    The era of the next generation of giant telescopes requires not only the advent of new technologies but also the development of novel methods, in order to exploit fully the extraordinary potential they are built for. Global Multi Conjugate Adaptive Optics (GMCAO) pursues this approach, with the goal of achieving good performance over a field of view of a few arcmin and an increase in sky coverage. In this article, we show the gain offered by this technique to an astrophysical application, such as the photometric survey strategy applied to the Chandra Deep Field South as a case study. We simulated a close-to-real observation of a 500 × 500 arcsec2 extragalactic deep field with a 40-m class telescope that implements GMCAO. We analysed mock K-band images of 6000 high-redshift (up to z = 2.75) galaxies therein as if they were real to recover the initial input parameters. We attained 94.5 per cent completeness for source detection with SEXTRACTOR. We also measured the morphological parameters of all the sources with the two-dimensional fitting tools GALFIT. The agreement we found between recovered and intrinsic parameters demonstrates GMCAO as a reliable approach to assist extremely large telescope (ELT) observations of extragalactic interest.

  4. A systematic search for z ≥ 5 active galactic nuclei in the Chandra Deep Field South

    NASA Astrophysics Data System (ADS)

    Weigel, Anna K.; Schawinski, Kevin; Treister, Ezequiel; Koss, Michael; Urry, C. Megan; Trakhtenbrot, Benny

    2015-01-01

    We investigate early black hole growth through the methodical search for z ≥ 5 AGN in the Chandra Deep Field South.We base our search on the Chandra 4-Ms data that should allow us to detect Compton-thin AGN with MBH >107 M⊙ accreting at Eddington ratios > 0.1.The Chandra Deep Field South contains over 600 z ≥ 5 Lyman Break Galaxies. These high-redshift galaxies are the progenitors of massive, local galaxies and based on lower redshift relations we would expect ~ 20 of them to host AGN.We combine the Chandra data with GOODS/ACS, CANDELS/WFC3 and Spitzer/IRAC data. After excluding clear low-redshift sources our sample consists of 58 high-redshift candidates. We use a range of redshift estimators including a photo-z code, stacking, colour criteria and the Lyman Break Technique. We also use the X-ray Hardness Ratio as additional information.The final z ≥ 5 candidates that remain after we combine our redshift tests, are likely to be low-redshift interlopers. We thus conclude that, contrary to our expectation of finding at least a few high-redshift AGN, the field does not contain any convincing z ≥ 5 AGN candidates.Our results place interesting constraints on early black hole growth and we discuss a range of possible explanations.

  5. The Pan-STARRS 1 Medium Deep Field Variable Star Catalog

    NASA Astrophysics Data System (ADS)

    Flewelling, Heather

    2015-01-01

    We present the first Pan-STARRS 1 Medium Deep Field Variable Star Catalog (PS1-MDF-VSC). The Pan-STARRS 1 (PS1) telescope is a 1.8 meter survey telescope with a 1.4 Gigapixel camera, located in Haleakala, Hawaii. The Medium Deep survey, which consists of 10 fields located uniformly across the sky, totalling 70 square degrees, is observed each night, in 2-3 filters per field, with 8 exposures per filter, resulting in 3000-4000 data points per star over a time span of 3.5 years. To find the variables, we select the stars with > 200 detections, between 16th and 21st magnitude. There are approximately 500k stars that fit this criteria, they then go through a lomb-scargle fitting routine to determine periodicity. After a periodicity cut, the ~400 candidates are classified by eye into different types of variable stars. We have identified several hundred variable stars, with periods ranging between a few minutes to a few days, and about half are not previously identified in the literature. We compare our results to the stripe 82 variable catalog, which overlaps part of the sky with the PS1 catalog.

  6. The Pan-STARRS 1 Medium Deep Field Variable Star Catalog

    NASA Astrophysics Data System (ADS)

    Flewelling, Heather

    2015-08-01

    We present the first Pan-STARRS 1 Medium Deep Field Variable Star Catalog (PS1-MDF-VSC). The Pan-STARRS 1 (PS1) telescope is a 1.8 meter survey telescope with a 1.4 Gigapixel camera, located in Haleakala, Hawaii. The Medium Deep survey, which consists of 10 fields located uniformly across the sky, totalling 70 square degrees, is observed each night, in 2-3 filters per field, with 8 exposures per filter, resulting in 3000-4000 data points per star over a time span of 3.5 years. To find the variables, we select the stars with > 200 detections, between 16th and 21st magnitude. There are approximately 500k stars that fit this criteria, they then go through a lomb-scargle fitting routine to determine periodicity. After a periodicity cut, the ~400 candidates are classified by eye into different types of variable stars. We have identified several hundred variable stars, with periods ranging between a few minutes to a few days, and about half are not previously identified in the literature. We compare our results to the stripe 82 variable catalog, which overlaps part of the sky with the PS1 catalog.

  7. DEEP VADOSE ZONE APPLIED FIELD RESEARCH CENTER: TRANSFORMATIONAL TECHNOLOGY DEVELOPMENT FOR ENVIRONMENTAL REMEDIATION

    SciTech Connect

    Wellman, Dawn M.; Triplett, Mark B.; Freshley, Mark D.; Truex, Michael J.; Gephart, Roy E.; Johnson, Timothy C.; Chronister, Glen B.; Gerdes, Kurt D.; Chamberlain, Skip; Marble, Justin; Ramirez, Rosa

    2011-02-27

    DOE-EM, Office of Groundwater and Soil Remediation and DOE Richland, in collaboration with the Hanford site and Pacific Northwest National Laboratory, have established the Deep Vadose Zone Applied Field Research Center (DVZ-AFRC). The DVZ-AFRC leverages DOE investments in basic science from the Office of Science, applied research from DOE EM Office of Technology Innovation and Development, and site operation (e.g., site contractors [CH2M HILL Plateau Remediation Contractor and Washington River Protection Solutions], DOE-EM RL and ORP) in a collaborative effort to address the complex region of the deep vadose zone. Although the aim, goal, motivation, and contractual obligation of each organization is different, the integration of these activities into the framework of the DVZ-AFRC brings the resources and creativity of many to provide sites with viable alternative remedial strategies to current baseline approaches for persistent contaminants and deep vadose zone contamination. This cooperative strategy removes stove pipes, prevents duplication of efforts, maximizes resources, and facilitates development of the scientific foundation needed to make sound and defensible remedial decisions that will successfully meet the target cleanup goals for one of DOE EM's most intractable problems, in a manner that is acceptable by regulators.

  8. Field testing of stiffened deep cement mixing piles under lateral cyclic loading

    NASA Astrophysics Data System (ADS)

    Raongjant, Werasak; Jing, Meng

    2013-06-01

    Construction of seaside and underground wall bracing often uses stiffened deep cement mixed columns (SDCM). This research investigates methods used to improve the level of bearing capacity of these SDCM when subjected to cyclic lateral loading via various types of stiffer cores. Eight piles, two deep cement mixed piles and six stiffened deep cement mixing piles with three different types of cores, H shape cross section prestressed concrete, steel pipe, and H-beam steel, were embedded though soft clay into medium-hard clay on site in Thailand. Cyclic horizontal loading was gradually applied until pile failure and the hysteresis loops of lateral load vs. lateral deformation were recorded. The lateral carrying capacities of the SDCM piles with an H-beam steel core increased by 3-4 times that of the DCM piles. This field research clearly shows that using H-beam steel as a stiffer core for SDCM piles is the best method to improve its lateral carrying capacity, ductility and energy dissipation capacity.

  9. SOLAR WAVE-FIELD SIMULATION FOR TESTING PROSPECTS OF HELIOSEISMIC MEASUREMENTS OF DEEP MERIDIONAL FLOWS

    SciTech Connect

    Hartlep, T.; Zhao, J.; Kosovichev, A. G.; Mansour, N. N.

    2013-01-10

    The meridional flow in the Sun is an axisymmetric flow that is generally directed poleward at the surface, and is presumed to be of fundamental importance in the generation and transport of magnetic fields. Its true shape and strength, however, are debated. We present a numerical simulation of helioseismic wave propagation in the whole solar interior in the presence of a prescribed, stationary, single-cell, deep meridional circulation serving as synthetic data for helioseismic measurement techniques. A deep-focusing time-distance helioseismology technique is applied to the synthetic data, showing that it can in fact be used to measure the effects of the meridional flow very deep in the solar convection zone. It is shown that the ray approximation that is commonly used for interpretation of helioseismology measurements remains a reasonable approximation even for very long distances between 12 Degree-Sign and 42 Degree-Sign corresponding to depths between 52 and 195 Mm. From the measurement noise, we extrapolate that time-resolved observations on the order of a full solar cycle may be needed to probe the flow all the way to the base of the convection zone.

  10. CANDELS MULTIWAVELENGTH CATALOGS: SOURCE IDENTIFICATION AND PHOTOMETRY IN THE CANDELS UKIDSS ULTRA-DEEP SURVEY FIELD

    SciTech Connect

    Galametz, Audrey; Grazian, Andrea; Fontana, Adriano; Castellano, Marco; Ferguson, Henry C.; Dahlen, Tomas; Grogin, Norman; Huang, Kuang-Han; Koekemoer, Anton M.; Ashby, M. L. N.; Willner, S. P.; Barro, Guillermo; Faber, Sandy M.; Guo, Yicheng; Kocevski, Dale D.; Lee, Kyoung-Soo; McGrath, Elizabeth J.; Peth, Michael; Almaini, Omar; Collaboration: CANDELS team; and others

    2013-06-01

    We present the multiwavelength-ultraviolet to mid-infrared-catalog of the UKIRT Infrared Deep Sky Survey (UKIDSS) Ultra-Deep Survey field observed as part of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS). Based on publicly available data, the catalog includes the CANDELS data from the Hubble Space Telescope (near-infrared WFC3 F125W and F160W data and visible ACS F606W and F814W data); u-band data from CFHT/Megacam; B, V, R{sub c} , i', and z' band data from Subaru/Suprime-Cam; Y and K{sub s} band data from VLT/HAWK-I; J, H, and K band data from UKIDSS (Data Release 8); and Spitzer/IRAC data (3.6, 4.5 {mu}m from SEDS; 5.8 and 8.0 {mu}m from SpUDS). The present catalog is F160W-selected and contains 35, 932 sources over an area of 201.7 arcmin{sup 2} and includes radio- and X-ray-detected sources and spectroscopic redshifts available for 210 sources.

  11. CANDELS Multiwavelength Catalogs: Source Identification and Photometry in the CANDELS UKIDSS Ultra-deep Survey Field

    NASA Astrophysics Data System (ADS)

    Galametz, Audrey; Grazian, Andrea; Fontana, Adriano; Ferguson, Henry C.; Ashby, M. L. N.; Barro, Guillermo; Castellano, Marco; Dahlen, Tomas; Donley, Jennifer L.; Faber, Sandy M.; Grogin, Norman; Guo, Yicheng; Huang, Kuang-Han; Kocevski, Dale D.; Koekemoer, Anton M.; Lee, Kyoung-Soo; McGrath, Elizabeth J.; Peth, Michael; Willner, S. P.; Almaini, Omar; Cooper, Michael; Cooray, Asantha; Conselice, Christopher J.; Dickinson, Mark; Dunlop, James S.; Fazio, G. G.; Foucaud, Sebastien; Gardner, Jonathan P.; Giavalisco, Mauro; Hathi, N. P.; Hartley, Will G.; Koo, David C.; Lai, Kamson; de Mello, Duilia F.; McLure, Ross J.; Lucas, Ray A.; Paris, Diego; Pentericci, Laura; Santini, Paola; Simpson, Chris; Sommariva, Veronica; Targett, Thomas; Weiner, Benjamin J.; Wuyts, Stijn; the CANDELS Team

    2013-06-01

    We present the multiwavelength—ultraviolet to mid-infrared—catalog of the UKIRT Infrared Deep Sky Survey (UKIDSS) Ultra-Deep Survey field observed as part of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS). Based on publicly available data, the catalog includes the CANDELS data from the Hubble Space Telescope (near-infrared WFC3 F125W and F160W data and visible ACS F606W and F814W data); u-band data from CFHT/Megacam; B, V, Rc , i', and z' band data from Subaru/Suprime-Cam; Y and Ks band data from VLT/HAWK-I; J, H, and K band data from UKIDSS (Data Release 8); and Spitzer/IRAC data (3.6, 4.5 μm from SEDS; 5.8 and 8.0 μm from SpUDS). The present catalog is F160W-selected and contains 35, 932 sources over an area of 201.7 arcmin2 and includes radio- and X-ray-detected sources and spectroscopic redshifts available for 210 sources.

  12. THE DEEP3 GALAXY REDSHIFT SURVEY: KECK/DEIMOS SPECTROSCOPY IN THE GOODS-N FIELD

    SciTech Connect

    Cooper, Michael C.; Aird, James A.; Coil, Alison L. E-mail: acoil@ucsd.edu

    2011-03-15

    We present the results of spectroscopic observations in the GOODS-N field completed using DEIMOS on the Keck II telescope as part of the DEEP3 Galaxy Redshift Survey. Observations of 370 unique targets down to a limiting magnitude of R {sub AB} = 24.4 yielded 156 secure redshifts. In addition to redshift information, we provide sky-subtracted one- and two-dimensional spectra of each target. Observations were conducted following the procedures of the Team Keck Redshift Survey (TKRS), thereby producing spectra that augment the TKRS sample while maintaining the uniformity of its spectral database.

  13. Infrared Faint Radio Sources in the Extended Chandra Deep Field South

    NASA Astrophysics Data System (ADS)

    Huynh, Minh T.

    2009-01-01

    Infrared-Faint Radio Sources (IFRSs) are a class of radio objects found in the Australia Telescope Large Area Survey (ATLAS) which have no observable counterpart in the Spitzer Wide-area Infrared Extragalactic Survey (SWIRE). The extended Chandra Deep Field South now has even deeper Spitzer imaging (3.6 to 70 micron) from a number of Legacy surveys. We report the detections of two IFRS sources in IRAC images. The non-detection of two other IFRSs allows us to constrain the source type. Detailed modeling of the SED of these objects shows that they are consistent with high redshift AGN (z > 2).

  14. Meiofauna assemblages of the Condor Seamount (North-East Atlantic Ocean) and adjacent deep-sea sediments

    NASA Astrophysics Data System (ADS)

    Zeppilli, Daniela; Bongiorni, Lucia; Cattaneo, Antonio; Danovaro, Roberto; Santos, Ricardo Serrão

    2013-12-01

    Seamounts are currently considered hotspots of biodiversity and biomass for macro- and megabenthic taxa, but knowledge of meiofauna is still limited. Studies have revealed the existence of highly diverse meiofauna assemblages; however most data are mainly qualitative or focused only on specific groups, thus preventing comparisons among seamounts and with other deep-sea areas. This study, conducted on Condor Seamount (Azores, North-East Atlantic Ocean), describes variation in abundance, biomass, community structure and biodiversity of benthic meiofauna from five sites located on the Condor Seamount: and one site away from the seamount. While the summit of the seamount hosted the highest alpha biodiversity, the flanks and the bases showed a rich meiofauna assemblage in terms of abundance and biomass. The observed marked differences in grain size composition of sediments reflected the oceanographic conditions impacting different sectors of the Condor seamount, and could play an important role in the spatial distribution of different meiofaunal taxa. Trophic conditions (biochemical composition of organic matter) explained 78% of the variability in the meiofauna biomass pattern while sediment grain influenced the vertical distribution of meiofauna and only partially explained meiofaunal taxa composition. This study provides a further advancement in the knowledge of meiofaunal communities of seamounts. Only a deeper understanding of the whole benthic communities (including meiofauna) will allow to elaborate effective management and conservation tools for seamount ecosystems.

  15. Seismic triggering of fluid flow in the North Alex mud volcano on the western Nile deep-sea fan

    NASA Astrophysics Data System (ADS)

    Brückmann, Warner; Lefeldt, Marten; Hölz, Sebastian; Tryon, Mike; Bialas, Jörg

    2010-05-01

    Submarine mud volcanoes are generally characterized by fluid formation and fluidization occuring at depths of several kilometers below the seafloor driving a complex system of interacting geochemical, geological and microbial processes. As mud volcanoes are natural leakages of oil and gas reservoirs, near-surface observations can be used for monitoring of these phenomena occurring at great depth. North Alex Mud Volcano (NAMV), located on the upper slope of the western Nile deep-sea fan is the focus of an RWE Dea funded research project using existing and newly developed observatory technologies to better understand and quantify the internal dynamics and its long-term variability in relation to underlying gas reservoirs. As it is known that the activity of mud volcanoes varies significantly over periods of months and weeks, the assessment of the activity of NAMV focuses on proxies of fluid and gas emanations. Since the initiation of the project in 2007 NAMV has arguably become one of the best-instrumented mud volcanoes worldwide with a network of observatories collecting long-term records of chemical fluxes, seismicity, temperature, ground deformation, and methane concentration. First results from parallel measurements of fluid flow variations and seismic events in the center of NAMV show a high degree of correlation. Harmonic oscillations of the uppermost gas-saturated part of the sediment conduit (see Lefeldt et al.) clearly stimulate synchronous fluid flow and gas ebullition episodes of several days duration.

  16. Winnepegosis facies and reservoir characteristics, Temple field, North Dakota

    SciTech Connect

    Ehrets, J.R.; Kissling, D.L.

    1988-07-01

    Since its discovery in 1982, Temple field has been developed into the largest Winnipegosis oil pool in the Williston basin. Situated on a subordinate limb of the Nesson anticline in northeastern Williams County, the combined structural-stratigraphic trap contains approximately 7.5 million bbl of primary recoverable oil reserves defined by 22 productive wells. Dolomitized upper slope mudstone represents the principal reservoir facies. This facies is overlain by a poorly dolomitized platform-margin reef facies that serves as the reservoir seal. The Temple Winnipegosis reservoir is envisioned to have developed in response to late Winnipegosis sea level drawdown and widespread exposure of the carbonate platform. Confined between less permeable strata represented by underlying argillaceous slope facies and overlying reef facies, the nonargillaceous slope facies was dolomitized in a mixing zone created by downward and seaward movement of meteoric water into connate marine water. Early cementation of reef facies also served to limit brine invasion and salt plugging of the reservoir upon later transgression of the platform by the hypersaline Prairie sea. The slope reservoir is generally characterized by 12-20% porosity and 10-70 md permeability. By comparison, reef porosity is typically 2-8%, with less than 3 md permeability. Halite cement is a common constituent in reef facies, having precipitated from hypersaline brine that invaded the reef through a system of fractures and vugs. Halite cement is also responsible for partial reservoir destruction in the underlying slope reservoir, particularly where the reef is poorly developed.

  17. The Magic Field Campaign in the Eastern North Pacific

    NASA Astrophysics Data System (ADS)

    Lewis, E. R.

    2013-12-01

    The MAGIC field campaign, funded and operated by the ARM (Atmospheric Radiation Measurement) Climate Research Facility of the US Department of Energy, occurred between September, 2012 and October, 2013 aboard the Horizon Lines cargo container ship Spirit making regular round trips between Los Angeles, CA and Honolulu, HI. Along this route, which lies very near the GPCI (GCSS Pacific Cross-Section Intercomparison) transect, the cloud regime changes from predominantly stratocumulus near the California coast to predominantly trade-wind cumulus near Hawaii. The transition between these two regimes is poorly understood and not accurately represented in climate models. The goal of the campaign was to improve the representation of this transition in models by acquiring statistics of the transition by making repeated transects through this region measuring properties of clouds and precipitation, aerosols, radiation, and atmospheric structure. To achieve these goals, the Second ARM Mobile Facility (AMF2) was deployed on the Horizon Spirit and nearly forty excursions through this transition were taken. The AMF2 consists of three 20-foot SeaTainers and other instruments that were installed on the Spirit. Two technicians accompanied the AMF2 and scientists rode as observers. Radiosondes were launched four times per day, and an overflight by the SPEC Learjet occurred in July. An overview of the deployment, preliminary results, and future plans will be presented.

  18. A PROVISIONAL FIELD DICTIONARY OF THE RUNGUS DUSUN LANGUAGE OF NORTH BORNEO.

    ERIC Educational Resources Information Center

    APPELL, GEORGE N.; APPELL, LAURA W.R.

    THIS DICTIONARY WAS PREPARED FOR USE DURING FIELD WORK AMONG THE RUNGUS DUSUN PEOPLE IN NORTH BORNEO. MANY WORDS WHOSE REFERENTS AND SEMANTIC RANGES WERE UNKNOWN OR UNCERTAIN WERE INCLUDED FOR RESEARCH PURPOSES. REPRESENTING THE FIRST STAGE OF STRUCTURAL ANALYSIS OF THE LANGUAGE, THIS COMPILATION CONTAINS A MINIMAL SECTION ON THE PHONETIC SYMBOLS…

  19. COMPARISON OF SCIENTIFIC FINDINGS FROM MAJOR OZONE FIELD STUDIES IN NORTH AMERICA AND EUROPE

    EPA Science Inventory

    During the past decade, nearly 600 million dollars were invested in more than 30 major field studies in North America and Europe examining tropospheric ozone chemistry, meteorology, precursor emissions, and modeling. Most of these studies were undertaken to provide new or refin...

  20. 2012 North Plains research field 12-200 limited irrigation corn production study

    USDA-ARS?s Scientific Manuscript database

    2012 represented the third sequential year of research regarding the limited irrigation 12-200 corn production assessment study at the North Plains Research Field (NPRF) with the yield results being improved from that of the 2011 season but less than of the 2010 season. The study's purpose was to ev...

  1. Field Guide for the Biological Control of Weeds in Eastern North America

    USDA-ARS?s Scientific Manuscript database

    This field guide provides information about invasive weeds in Eastern North America and their associated biological control agents. Information about plant identification and ecology is provided through photographs and descriptions for each weed species. The guide also includes photographs of the bi...

  2. MULTIMEDIA CHEMICAL ANALYSIS PLAN FOR CHILDREN'S AGGREGATE EXPOSURE FIELD STUDIES IN NORTH CAROLINA AND OHIO

    EPA Science Inventory

    The samples collected in the CTEPP North Carolina and Ohio field campaigns were analyzed for a suite of organic chemicals in various compound classes, chosen because of their possible carcinogenicity, acute or chronic toxicity, or potential for endocrine system disruption. The...

  3. First LNG from North field overcomes feed, start-up problems

    SciTech Connect

    Redha, A.; Rahman, A.; Al-Thani, N.H.; Ishikura, Masayuki; Kikkawa, Yoshitsugi

    1998-08-24

    Qatar Gas LNG is the first LNG project in the gas-development program of the world`s largest gas reservoir, North field. The LNG plant was completed within the budget and schedule. The paper discusses the LNG plant design, LNG storage and loading, alternative mercaptan removal, layout modification, information and control systems, training, data management systems, start-up, and performance testing.

  4. Influence of heterogeneous and anisotropic tissue conductivity on electric field distribution in deep brain stimulation.

    PubMed

    Aström, Mattias; Lemaire, Jean-Jacques; Wårdell, Karin

    2012-01-01

    The aim was to quantify the influence of heterogeneous isotropic and heterogeneous anisotropic tissue on the spatial distribution of the electric field during deep brain stimulation (DBS). Three finite element tissue models were created of one patient treated with DBS. Tissue conductivity was modelled as (I) homogeneous isotropic, (II) heterogeneous isotropic based on MRI, and (III) heterogeneous anisotropic based on diffusion tensor MRI. Modelled DBS electrodes were positioned in the subthalamic area, the pallidum, and the internal capsule in each tissue model. Electric fields generated during DBS were simulated for each model and target-combination and visualized with isolevels at 0.20 (inner), and 0.05 V mm(-1) (outer). Statistical and vector analysis was used for evaluation of the distribution of the electric field. Heterogeneous isotropic tissue altered the spatial distribution of the electric field by up to 4% at inner, and up to 10% at outer isolevel. Heterogeneous anisotropic tissue influenced the distribution of the electric field by up to 18 and 15% at each isolevel, respectively. The influence of heterogeneous and anisotropic tissue on the electric field may be clinically relevant in anatomic regions that are functionally subdivided and surrounded by multiple fibres of passage.

  5. On the nature of infrared-faint radio sources in the Subaru X-ray Deep and Very Large Array-VIMOS VLT Deep Survey fields

    NASA Astrophysics Data System (ADS)

    Singh, Veeresh; Wadadekar, Yogesh; Ishwara-Chandra, C. H.; Sirothia, Sandeep; Sievers, Jonathan; Beelen, Alexandre; Omont, Alain

    2017-10-01

    Infrared-faint radio sources (IFRSs) are an unusual class of objects that are relatively bright at radio wavelengths but have faint or undetected infrared counterparts, even in deep surveys. We identify and investigate the nature of IFRSs using deep radio (S1.4 GHz ˜ 100 μJy beam-1 at 5σ), optical (mr ˜ 26-27.7 at 5σ) and near-infrared (S3.6 μm ˜ 1.3-2.0 μJy beam-1 at 5σ) data that are available in two deep fields: the Subaru X-ray Deep Field (SXDF) and the Very Large Array-VIMOS VLT Deep Survey (VLA-VVDS) field. In 1.8 deg2 of the two fields, we identify a total of nine confirmed and ten candidate IFRSs. We find that our IFRSs are high-redshift radio-loud active galactic nuclei, with 12/19 sources having redshift estimates in the range of z ˜ 1.7-4.3, while a limit of z ≥ 2.0 is placed on the remaining seven sources. Notably, for the first time, our study finds IFRSs with measured redshift >3.0, and also redshift estimates for IFRSs in the faintest 3.6-μm flux regime (i.e. S3.6 μm < 1.3 μJy). Radio observations show that our IFRSs exhibit both compact unresolved and extended double-lobe morphologies, and have predominantly steep radio spectra between 1.4 GHz and 325 MHz. The non-detection of all but one IFRSs in the X-ray band and the optical-to-mid-infrared colour (mr-m24 μm) suggest that a significant fraction of IFRSs are likely to be hosted in dusty obscured galaxies.

  6. Deep Coral Habitat Characterization of the North End of Raita Bank, Papahānaumokuākea Marine National Monument in the Northwestern Hawaiian Islands

    NASA Astrophysics Data System (ADS)

    Foxworth, L.; Sautter, L.

    2016-02-01

    The purpose of this study is to characterize and explore the north end of Raita Bank in the Northwestern Hawaiian Islands, to assess where deep marine coral would most likely grow and flourish. The bank is located within the largest U.S marine protected area, the Papahānaumokuākea Marine National Monument (PMNM), 1120 km northwest of Honolulu, Hawaii. Multibeam sonar data were collected by the Schmidt Ocean Institute using the R/V Falkor's Kongsberg EM302 and EM710 during an exploratory cruise within the PMNM in May-June 2014. Raita Bank hosts both shallow and deep coral; however, this study was focused on potential deep coral habitat at depths ranging 400 to 3000 m. The bank stretches approximately 44.0 km east-west and 35.8 km north-south and its shallowest point surveyed is 320 m. Overall gradients between 400 and 3000 m depths range from 0.10 to 0.26, including major terraces at 500 and 1000 m. The steeper gradients and terraced areas indicate favorable conditions for deep coral. A bathymetric map created with CARIS HIPS and SIPS 9.0 software was used to visualize seafloor geomorphology and characterize deep coral habitat by examining slope relief, distance to shelf edge, and other geomorphologic features. Additionally, backscatter was used to analyze the seafloor's relative hardness to identify hard-bottom seafloor areas that would be more likely to support deep coral. Maps generated from this study will be invaluable for future explorations of deep coral habitat on the bank.

  7. The 1.1-Ga Midcontinent Rift System, central North America: sedimentology of two deep boreholes, Lake Superior region

    NASA Astrophysics Data System (ADS)

    Ojakangas, Richard W.; Dickas, Albert B.

    2002-03-01

    The Midcontinent Rift System (MRS) of central North America is a 1.1-Ga, 2500-km long structural feature that has been interpreted as a triple-junction rift developed over a mantle plume. As much as 20 km of subaerial lava flows, mainly flood basalts, are overlain by as much as 10 km of sedimentary rocks that are mostly continental fluvial red beds. This rock sequence, known as the Keweenawan Supergroup, has been penetrated by a few deep boreholes in the search for petroleum. In this paper, two deep boreholes in the Upper Peninsula of Michigan are described in detail for the first time. Both the Amoco Production #1-29R test, herein referred to as the St. Amour well, and the nearby Hickey Creek well drilled by Cleveland Cliffs Mining Services, were 100% cored. The former is 7238 ft (2410 m) deep and the latter is 5345 ft (1780 m) deep. The entirety of the stratigraphic succession of the Hickey Creek core correlates very well with the upper portion of the St. Amour core, as determined by core description and point-counting of 43 thin sections selected out of 100 studied thin sections. Two Lower Paleozoic units and two Keweenawan red bed units—the Jacobsville Sandstone and the underlying Freda Sandstone—are described. The Jacobsville is largely a feldspatholithic sandstone and the Freda is largely a lithofeldspathic sandstone. Below the Freda, the remaining footage of the St. Amour core consists of a thick quartzose sandstone unit that overlies a heterogenous unit of intercalated red bed units of conglomerate, sandstone, siltstone, and shale; black shale; individual basalt flows; and a basal ignimbritic rhyolite. This lower portion of the St. Amour core presents an enigma, as it correlates very poorly with other key boreholes located to the west and southwest. While a black shale sequence is similar to the petroleum-bearing Nonesuch Formation farther west, there is no conglomerate unit to correlate with the Copper Harbor Conglomerate. Other key boreholes are

  8. Diffraction of a one-dimensional phase grating in the deep Fresnel field.

    PubMed

    Teng, Shuyun; Zhang, Ningyu; Dong, Qingrui; Cheng, Chuanfu

    2007-11-01

    We analyze theoretically the diffraction of phase gratings in the deep Fresnel field on the basis of the theory of scalar diffraction and Green's theorem and present the general formula for the diffraction intensity of a one-dimensional sinusoidal phase grating. The numerical calculations show that in the deep Fresnel region the diffraction distribution can be described by designating three characteristic regions that are influenced by the parameters of the grating. The microlensing effect of the interface of the phase grating provides the corresponding explanation. Moreover, according to the viewpoint that the diffraction intensity distribution is the result of the interference of the diffraction orders of the grating, we find that the diffraction patterns, depending on the carved depth of the phase grating, are determined by the contributing diffraction orders, their relative power, and the quasi-Talbot effect of the phase grating, which results from the second meeting of the diffraction orders carrying most of the power of the total field, as in the case of the amplitude grating.

  9. SEARCH FOR HIGH PROPER MOTION OBJECTS IN THE CFHTLS DEEP FIELDS

    SciTech Connect

    Hu, Juei-Hwa; Ip, Wing-Huen; Richer, Harvey; Gwyn, Stephen D. J.

    2013-03-20

    We present the results of a search for high proper motion white dwarfs in the deep survey of the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS). The CFHTLS Deep Survey covers 4 deg{sup 2} in five filters (u*, g', r', i', and z'). For the first and the fourth fields, we use data for a 5 year baseline from 2004 to 2009. For the second and the third fields, we have a 4 year baseline from 2004 to 2008. Proper motion selection is used to distinguish cool high-velocity white dwarfs from distant objects with similar blue colors such as compact faint galaxies and quasars. We discovered 44 white dwarf candidates brighter than g' = 24 on the basis of their spectral energy distribution and reduced proper motions. We found one white dwarf candidate with effective temperature less than 4000 K. From its estimated tangential velocity of 31 km s{sup -1} and a distance of 124 pc, it appears to be located in the thin or thick disk of the Galaxy. We also find five candidates having T{sub eff} between 4000 K and 5000 K. One candidate in D2 with effective temperature of 5000 K and tangential velocity of 190 km s{sup -1} indicates that it could be in the thick disk or in the halo. The other four candidates are likely located in the thin disk because of their estimated distances and tangential velocity.

  10. Comparison of ELTs, interferometers and hypertelescopes for deep field imaging and coronagraphy

    NASA Astrophysics Data System (ADS)

    Labeyrie, Antoine

    2007-04-01

    We compare the science potential of ELTs, interferometers and hypertelescopes having the same collecting area. Hypertelescopes with hundreds or thousands of small apertures overcome the ‘field crowding’ problem which interferometers have for aperture synthesis with few apertures. They also improve the signal/noise ratio as N if N is the number of apertures. With a modified laser guide star scheme, currently being explored, they become, in principle, suitable for observing deep fields of remote galaxies, with a limiting magnitude identical to an ELT, and with higher resolution. Before initiating major ground-based projects, the comparison of these architectures should be studied in more detail, for the various observing targets and science cases. To cite this article: A. Labeyrie, C. R. Physique 8 (2007).

  11. Condenser for ring-field deep-ultraviolet and extreme-ultraviolet lithography

    DOEpatents

    Chapman, Henry N.; Nugent, Keith A.

    2001-01-01

    A condenser for use with a ring-field deep ultraviolet or extreme ultraviolet lithography system. A condenser includes a ripple-plate mirror which is illuminated by a collimated beam at grazing incidence. The ripple plate comprises a plate mirror into which is formed a series of channels along an axis of the mirror to produce a series of concave surfaces in an undulating pattern. Light incident along the channels of the mirror is reflected onto a series of cones. The distribution of slopes on the ripple plate leads to a distribution of angles of reflection of the incident beam. This distribution has the form of an arc, with the extremes of the arc given by the greatest slope in the ripple plate. An imaging mirror focuses this distribution to a ring-field arc at the mask plane.

  12. Condenser for ring-field deep ultraviolet and extreme ultraviolet lithography

    DOEpatents

    Chapman, Henry N.; Nugent, Keith A.

    2002-01-01

    A condenser for use with a ring-field deep ultraviolet or extreme ultraviolet lithography system. A condenser includes a ripple-plate mirror which is illuminated by a collimated or converging beam at grazing incidence. The ripple plate comprises a flat or curved plate mirror into which is formed a series of channels along an axis of the mirror to produce a series of concave surfaces in an undulating pattern. Light incident along the channels of the mirror is reflected onto a series of cones. The distribution of slopes on the ripple plate leads to a distribution of angles of reflection of the incident beam. This distribution has the form of an arc, with the extremes of the arc given by the greatest slope in the ripple plate. An imaging mirror focuses this distribution to a ring-field arc at the mask plane.

  13. Management of a giant deep field: El Furrial Field, Eastern Venezuela

    SciTech Connect

    Pinto, N.; Mengual, R.; Anz, J.; Rodney, C.

    1996-08-01

    The Furrial Field is located in Eastern Venezuela and produces a 25 to 30{degrees} API asphaltenic crude oil from a 1500 ft thick Oligocene sand interval at a depth of 15,000 ft. The bubble point is about 4500 psi as compared to an original pressure of 11,000 psi. Oil in place is approximately 6800 million STB. Currently production is 350 MB/D from 77 well streams (Naricual Formation), and water is being injected at 400 MB/D to maintain pressure. The combination of a volumetric reservoir and asphaltenic nature of crude oil resulted in a rapid decrease in well productivity and reservoir pressure, creating the necessity to maintain reservoir pressure to maximize recovery. Discussed in this paper are the reservoir management techniques and strategies used by Lagoven to develop and operate these complex reservoirs. Acquisition and analysis of these data adequate to properly implement these management techniques are covered in detail.

  14. M4 - A Globular Cluster Hubble Deep Field: The Inner Halo Field Population

    NASA Astrophysics Data System (ADS)

    Rich, R. M.; Brewer, J.; Fahlman, G. G.; Gibson, B.; Hansen, B.; Ibata, R.; Limongi, M.; Richer, H. B.; Stetson, P. B.; Shara, M.

    2001-12-01

    We report analysis of our data from GO-8769, a 123 orbit exposure with HST/WFPC2 in F606W (wide V) and F814W (I) of a field in the globular cluster M4. Our photometry reaches to V ~ 30 and I ~ 28.5, and we are able to combine our data with imagery obtained 6 years earlier to produce a proper-motion selected sample. The reduced proper motion diagram shows two clumps: a very tight clump corresponding to members of M4, and a separate well-defined clump of stars with a much larger proper motion dispersion, which we attribute to the inner halo. M4 has l,b=(351,16) and the sight line therefore intersects in the inner halo roughly 2.5 kpc from the nucleus. Using the grouping in the reduced proper motion diagram, we are able to isolate those stars with membership in the inner halo (bulge?) population. We find a well defined main sequence extending to V≈ 29, or MV ~ +14 and this also will give one of the deepest luminosity functions ever constructed for the spheroid. The main sequence is substantially wider than that of the cluster, which we attribute both the dispersion in spatial location and metallicity. Our estimate of the proper motion dispersion gives 0.25 arcsec/century, or ≈ 100 km/sec at a distance of 8 kpc --- consistent with that found in other bulge fields. RMR acknowledges support from grant GO-8769 through the Space Telescope Science Institute.

  15. The systematic search for z ≳ 5 active galactic nuclei in the Chandra Deep Field South

    NASA Astrophysics Data System (ADS)

    Weigel, Anna K.; Schawinski, Kevin; Treister, Ezequiel; Urry, C. Megan; Koss, Michael; Trakhtenbrot, Benny

    2015-04-01

    We investigate early black hole (BH) growth through the methodical search for z ≳ 5 active galactic nuclei (AGN) in the Chandra Deep Field South. We base our search on the Chandra 4-Ms data with flux limits of 9.1 × 10-18 (soft, 0.5-2 keV) and 5.5 × 10-17 erg s-1 cm-2 (hard, 2-8 keV). At z ˜ 5, this corresponds to luminosities as low as ˜1042 (˜1043) erg s-1 in the soft (hard) band and should allow us to detect Compton-thin AGN with MBH > 107 M⊙ and Eddington ratios >0.1. Our field (0.03 deg2) contains over 600z ˜ 5 Lyman Break Galaxies. Based on lower redshift relations, we would expect ˜20 of them to host AGN. After combining the Chandra data with Great Observatories Origins Deep Survey (GOODS)/Advanced Camera for Surveys (ACS), CANDELS/Wide Field Camera 3 and Spitzer/Infrared Array Camera data, the sample consists of 58 high-redshift candidates. We run a photometric redshift code, stack the GOODS/ACS data, apply colour criteria and the Lyman Break Technique and use the X-ray Hardness Ratio. We combine our tests and using additional data find that all sources are most likely at low redshift. We also find five X-ray sources without a counterpart in the optical or infrared which might be spurious detections. We conclude that our field does not contain any convincing z ≳ 5 AGN. Explanations for this result include a low BH occupation fraction, a low AGN fraction, short, super-Eddington growth modes, BH growth through BH-BH mergers or in optically faint galaxies. By searching for z ≳ 5 AGN, we are setting the foundation for constraining early BH growth and seed formation scenarios.

  16. Intermediate-wavelength magnetic anomaly field of the North Pacific and posible source distributions

    NASA Technical Reports Server (NTRS)

    Labrecque, J. L.; Cande, S. C.; Jarrard, R. D.

    1985-01-01

    A technique that eliminates external field sources and the effects of strike aliasing was used to extract from marine survey data the intermediate wavelength magnetic anomaly field for (B) in the North Pacific. A strong correlation exists between this field and the Magsat field although a directional sensitivity in the Magsat field can be detected. The intermediate wavelength field is correlated to tectonic features. Island arcs appear as positive anomalies of induced origin likely due to variations in crustal thickness. Seamount chains and oceanic plateaus also are manifested by strong anomalies. The primary contribution to many of these anomalies appears to be due to a remanent magnetization. The source parameters for the remainder of these features are presently unidentified ambiguous. Results indicate that the sea surface field is a valuable source of information for secular variation analysis and the resolution of intermediate wavelength source parameters.

  17. The intermediate wavelength magnetic anomaly field of the north Pacific and possible source distributions

    NASA Technical Reports Server (NTRS)

    Labrecque, J. L.; Cande, S. C.; Jarrard, R. D. (Principal Investigator)

    1983-01-01

    A technique that eliminates external field sources and the effects of strike aliasing was used to extract from marine survey data the intermediate wavelength magnetic anomaly field for (B) in the North Pacific. A strong correlation exists between this field and the MAGSAT field although a directional sensitivity in the MAGSAT field can be detected. The intermediate wavelength field is correlated to tectonic features. Island arcs appear as positive anomalies of induced origin likely due to variations in crustal thickness. Seamount chains and oceanic plateaus also are manifested by strong anomalies. The primary contribution to many of these anomalies appears to be due to a remanent magnetization. The source parameters for the remainder of these features are presently unidentified ambiguous. Results indicate that the sea surface field is a valuable source of information for secular variation analysis and the resolution of intermediate wavelength source parameters.

  18. Emission-Line Galaxies from the PEARS Hubble Ultra Deep Field: A 2-D Detection Method and First Results

    NASA Technical Reports Server (NTRS)

    Gardner, J. P.; Straughn, Amber N.; Meurer, Gerhardt R.; Pirzkal, Norbert; Cohen, Seth H.; Malhotra, Sangeeta; Rhoads, james; Windhorst, Rogier A.; Gardner, Jonathan P.; Hathi, Nimish P.; Xu, Chun; Gronwall, Caryl; Koekemoer, Anton M.; Walsh, Jeremy; diSeregoAlighieri, Sperello

    2007-01-01

    The Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) grism PEARS (Probing Evolution And Reionization Spectroscopically) survey provides a large dataset of low-resolution spectra from thousands of galaxies in the GOODS North and South fields. One important subset of objects in these data are emission-line galaxies (ELGs), and we have investigated several different methods aimed at systematically selecting these galaxies. Here we present a new methodology and results of a search for these ELGs in the PEARS observations of the Hubble Ultra Deep Field (HUDF) using a 2D detection method that utilizes the observation that many emission lines originate from clumpy knots within galaxies. This 2D line-finding method proves to be useful in detecting emission lines from compact knots within galaxies that might not otherwise be detected using more traditional 1D line-finding techniques. We find in total 96 emission lines in the HUDF, originating from 81 distinct "knots" within 63 individual galaxies. We find in general that [0 1111 emitters are the most common, comprising 44% of the sample, and on average have high equivalent widths (70% of [0 1111 emitters having rest-frame EW> 100A). There are 12 galaxies with multiple emitting knots; several show evidence of variations in H-alpha flux in the knots, suggesting that the differing star formation properties across a single galaxy can in general be probed at redshifts approximately greater than 0.2 - 0.4. The most prevalent morphologies are large face-on spirals and clumpy interacting systems, many being unique detections owing to the 2D method described here, thus highlighting the strength of this technique.

  19. Field guide to Laramide basin evolution and drilling activity in North Park and Middle Park, Colorado

    USGS Publications Warehouse

    Dechesne, Marieke; Cole, James Channing; Martin, Christopher B.

    2016-01-01

    Overview of the geologic history of the North Park–Middle Park area and its past and recent drilling activity. Field trip stops highlight basin formation and the consequences of geologic configuration on oil and gas plays and development. The starting point is the west flank of the Denver Basin to compare and contrast the latest Cretaceous through Eocene basin fill on both flanks of the Front Range, before exploring sediments of the same age in the North Park – Middle Park intermontane basin.

  20. Eastern North Atlantic deep-sea corals: tracing upper intermediate water Δ 14C during the Holocene

    NASA Astrophysics Data System (ADS)

    Frank, Norbert; Paterne, Martine; Ayliffe, Linda; van Weering, Tjeerd; Henriet, Jean-Pierre; Blamart, Dominique

    2004-03-01

    Paired 230Th/U and 14C dating were performed on deep-sea corals (Lophelia pertusa and Madrepora oculata) from the northeastern North Atlantic at ∼730 m bsl to investigate past changes of the thermohaline circulation. These were estimated using the Δ14C value of the upper intermediate waters, based on the 14C ages of the top and base of each coral, where possible, and the 230Th/U dating. The reliability of these estimates was checked by dating two very young corals of the species L. pertusa. One of these corals, collected alive in 1999 AD, gave a 230Th/U age of 1995±4 AD after correction for non-radiogenic 230Th. Another coral, the top of which dated to 1969±6 AD, recorded the atmospheric 14C/12C increase due to the nuclear tests in the early 1960s. The calculated Δ14C values from these two corals agree with those measured at GEOSECS Station 23 in 1972-1973 [Östlund et al., Earth Planet. Sci. Lett. 23 (1974) 69-86] and 1991-1992 [Nydal and Gisfelos, Radiocarbon 38 (1996) 389-406]. This, together with the 100% aragonite content and the δ234U and 230Th/232Th values of all the dated corals, indicates that none of the corals behaved as open systems with respect to their U-series nuclides and that they closely represent the water mass properties in which they lived. The pre-anthropogenic Δ14C value of the North Atlantic intermediate waters was estimated at -69±4‰. The reservoir age varies from ∼400 years to ∼600 years, and this variation is due to atmospheric 14C/12C changes. A reservoir age of 610±80 years, close to the pre-anthropogenic value, was determined from one coral dated at 10 430±120 cal yr BP, when the global sea level was approximately at -35 m [Bard et al., Nature 382 (1996) 241-244]. This suggests a modern-like pattern of the oceanic circulation prevailed in the Northeast Atlantic Ocean at this time although the deglaciation was not completely achieved.

  1. Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey -- UDS Field

    NASA Astrophysics Data System (ADS)

    Faber, Sandra

    2010-09-01

    The Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey {CANDELS}is designed to document the ?rst third of galactic evolution from z =8 to 1.5 via deep imaging of more than 250,000 galaxies with WFC3/IRand ACS. It will also find the first Type Ia SNe beyond z > 1.5 andestablish their accuracy as standard candles for cosmology. Fivepremier multi-wavelength sky regions are selected from the SpitzerExtragalactic Deep Survey {SEDS} to provide complementary IRAC imagingdata down to 26.5 AB mag, a unique resource for stellar masses at allredshifts. The use of ?ve widely separated ?elds mitigates cosmicvariance and yields statistically robust and complete samples ofgalaxies down to 10^9 solar masses out to z 8.The program merges two originally separate MCT proposals. The Faberprogram incorporates a ?Wide? imaging survey in three separate fieldsto 2 orbit depth over 0.2 sq. degrees, plus a ?Deep? imaging surveyto 12 orbit depth in the two GOODS regions over 0.04 sq. degrees.In combination with ultra-deep imaging from the Hubble Ultradeep Fieldprogram {GO 11563}, the result is a three-tiered strategy that ef?cientlysamples both bright/rare and faint/common extragalactic objects. TheFerguson program adds an extensive high-redshift Type Ia SNe search,plus ultraviolet "daytime" UVIS exposures in GOODS-N to exploit theCVZ opportunity in that field.This program, GO 12064, is part of the Wide mosaic survey, which has thefollowing field centers and sizes: Field ID RA{2000} Dec{2000} WFC3 Dim. PA on sky UDS 02 17 38 -05 12 02 4x11 270 COSMOS 10 00 31 +02 24 00 4x11 180 EGS 14 19 31 +52 54 10 3x15 41 Science highlights from the Wide program: * Underlying structural properties of galaxies as revealed by WFC3-IR images sensitive to older stars {beyond the 4000-A break} and less affected by dust than ACS. A key redshift is z 2, where star-formation peaks, QSOs are most abundant, and where restframe B-band is still accessible to WFC3. Sample questions include: - Structure in young

  2. Deep X-ray spectroscopy of obscured AGN in the ultra-deep XMM surveys of the Chandra Deep Field South (CDFS)

    NASA Astrophysics Data System (ADS)

    Comastri, Andrea; Ranalli, P.; Vignali, C.; Cappelluti, N.; Gilli, R.; Iwasawa, K.; Carrera, F. J.; Brusa, M.; Vito, F.; Georgantopoulos, I.; Rovilos, E.; Fiore, F.; Civano, F.; Brandt, W. N.; Tozzi, P.; Barcons, X.; Puccetti, S.; Falocco, S.; Paolillo, M.

    2012-09-01

    According to the recent models for the joint evolution of Super Massive Black Holes and their Host Galaxies, heavy obscuration represents a crucial phase and is expected to play a key role in the feedback mechanisms self regulating the SMBH growth. The smoking gun signature of heavy absorption is the presence of a low energy cut-off and/or reflection signatures (i.e. iron lines and edges) in the X-ray spectrum. Deep X-ray spectroscopy represents the most efficient method to uncover the most obscured sources at cosmological distances. After a brief description of the XMM ultra-deep (3 Ms) survey in the CDFS, I will present the results of a systematic search for heavily obscured and Compton thick AGN and discuss the results in the light of recent phenomenological (i.e. XRB synthesis) and theoretical models. I will also highlight the power of deep spectral spectroscopy to obtain redshift estimates, via the iron line, more accurate and reliable than available photo-z. Synergies between ultra-deep Chandra (4 Ms) and XMM observations and perspectives for future surveys will be also reported.

  3. Resource Assessment of the In-Place and Potentially Recoverable Deep Natural Gas Resource of the Onshore Interior Salt Basins, North Central and Northeastern Gulf of Mexico

    SciTech Connect

    Ernest A. Mancini; Donald A. Goddard

    2004-10-28

    The objectives of the study are: to perform resource assessment of the in-place deep (>15,000 ft) natural gas resource of the onshore interior salt basins of the North Central and Northeastern Gulf of Mexico areas through petroleum system identification, characterization and modeling and to use the petroleum system based resource assessment to estimate the volume of the in-place deep gas resource that is potentially recoverable and to identify those areas in the interior salt basins with high potential to recover commercial quantities of the deep gas resource. The principal research effort for Year 1 of the project is data compilation and petroleum system identification. The research focus for the first nine (9) months of Year 1 is on data compilation and for the remainder of the year the emphasis is on petroleum system identification.

  4. Organohalogen compounds in deep-sea fishes from the western North Pacific, off-Tohoku, Japan: Contamination status and bioaccumulation profiles.

    PubMed

    Takahashi, Shin; Oshihoi, Tomoko; Ramu, Karri; Isobe, Tomohiko; Ohmori, Koji; Kubodera, Tsunemi; Tanabe, Shinsuke

    2010-02-01

    Twelve species of deep-sea fishes collected in 2005 from the western North Pacific, off-Tohoku, Japan were analyzed for organohalogen compounds. Among the compounds analyzed, concentrations of DDTs and PCBs (up to 23,000 and 12,400 ng/g lipid wt, respectively) were the highest. The present study is the foremost to report the occurrence of brominated flame retardants such as PBDEs and HBCDs in deep-sea organisms from the North Pacific region. Significant positive correlations found between delta(15)N ( per thousand) and PCBs, DDTs and PBDEs suggest the high biomagnification potential of these contaminants in food web. The large variation in delta(13)C (per thousand) values observed between the species indicate multiple sources of carbon in the food web and specific accumulation of hydrophobic organohalogen compounds in benthic dwelling carnivore species like snubnosed eel. The results obtained in this study highlight the usefulness of deep-sea fishes as sentinel species to monitor the deep-sea environment.

  5. Deep probing of the photospheric sunspot penumbra: no evidence of field-free gaps

    NASA Astrophysics Data System (ADS)

    Borrero, J. M.; Asensio Ramos, A.; Collados, M.; Schlichenmaier, R.; Balthasar, H.; Franz, M.; Rezaei, R.; Kiess, C.; Orozco Suárez, D.; Pastor, A.; Berkefeld, T.; von der Lühe, O.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Soltau, D.; Volkmer, R.; Waldmann, T.; Denker, C.; Hofmann, A.; Staude, J.; Strassmeier, K. G.; Feller, A.; Lagg, A.; Solanki, S. K.; Sobotka, M.; Nicklas, H.

    2016-11-01

    Context. Some models for the topology of the magnetic field in sunspot penumbrae predict regions free of magnetic fields or with only dynamically weak fields in the deep photosphere. Aims: We aim to confirm or refute the existence of weak-field regions in the deepest photospheric layers of the penumbra. Methods: We investigated the magnetic field at log τ5 = 0 is by inverting spectropolarimetric data of two different sunspots located very close to disk center with a spatial resolution of approximately 0.4-0.45''. The data have been recorded using the GRIS instrument attached to the 1.5-m solar telescope GREGOR at the El Teide observatory. The data include three Fe i lines around 1565 nm, whose sensitivity to the magnetic field peaks half a pressure scale height deeper than the sensitivity of the widely used Fe i spectral line pair at 630 nm. Before the inversion, the data were corrected for the effects of scattered light using a deconvolution method with several point spread functions. Results: At log τ5 = 0 we find no evidence of regions with dynamically weak (B< 500 Gauss) magnetic fields in sunspot penumbrae. This result is much more reliable than previous investigations made on Fe i lines at 630 nm. Moreover, the result is independent of the number of nodes employed in the inversion, is independent of the point spread function used to deconvolve the data, and does not depend on the amount of stray light (i.e., wide-angle scattered light) considered.

  6. SIMULTANEOUS EXOPLANET CHARACTERIZATION AND DEEP WIDE-FIELD IMAGING WITH A DIFFRACTIVE PUPIL TELESCOPE

    SciTech Connect

    Guyon, Olivier; Eisner, Josh A.; Angel, Roger; Woolf, Neville J.; Bendek, Eduardo A.; Milster, Thomas D.; Ammons, S. Mark; Shao, Michael; Shaklan, Stuart; Levine, Marie; Nemati, Bijan; Martinache, Frantz; Pitman, Joe; Woodruff, Robert A.; Belikov, Ruslan

    2013-04-10

    High-precision astrometry can identify exoplanets and measure their orbits and masses while coronagraphic imaging enables detailed characterization of their physical properties and atmospheric compositions through spectroscopy. In a previous paper, we showed that a diffractive pupil telescope (DPT) in space can enable sub-{mu}as accuracy astrometric measurements from wide-field images by creating faint but sharp diffraction spikes around the bright target star. The DPT allows simultaneous astrometric measurement and coronagraphic imaging, and we discuss and quantify in this paper the scientific benefits of this combination for exoplanet science investigations: identification of exoplanets with increased sensitivity and robustness, and ability to measure planetary masses to high accuracy. We show how using both measurements to identify planets and measure their masses offers greater sensitivity and provides more reliable measurements than possible with separate missions, and therefore results in a large gain in mission efficiency. The combined measurements reliably identify potentially habitable planets in multiple systems with a few observations, while astrometry or imaging alone would require many measurements over a long time baseline. In addition, the combined measurement allows direct determination of stellar masses to percent-level accuracy, using planets as test particles. We also show that the DPT maintains the full sensitivity of the telescope for deep wide-field imaging, and is therefore compatible with simultaneous scientific observations unrelated to exoplanets. We conclude that astrometry, coronagraphy, and deep wide-field imaging can be performed simultaneously on a single telescope without significant negative impact on the performance of any of the three techniques.

  7. Deep 3-GHz observations of the Lockman Hole North with the Very Large Array - I. Source extraction and uncertainty analysis

    NASA Astrophysics Data System (ADS)

    Vernstrom, T.; Scott, Douglas; Wall, J. V.; Condon, J. J.; Cotton, W. D.; Perley, R. A.

    2016-09-01

    This is the first of two papers describing the observations and cataloguing of deep 3-GHz observations of the Lockman Hole North using the Karl G. Jansky Very Large Array. The aim of this paper is to investigate, through the use of simulated images, the uncertainties and accuracy of source-finding routines, as well as to quantify systematic effects due to resolution, such as source confusion and source size. While these effects are not new, this work is intended as a particular case study that can be scaled and translated to other surveys. We use the simulations to derive uncertainties in the fitted parameters, as well as bias corrections for the actual catalogue (presented in Paper II). We compare two different source-finding routines, OBIT and AEGEAN, and two different effective resolutions, 8 and 2.75 arcsec. We find that the two routines perform comparably well, with OBIT being slightly better at de-blending sources, but slightly worse at fitting resolved sources. We show that 30-70 per cent of sources are missed or fit inaccurately once the source size becomes larger than the beam, possibly explaining source count errors in high-resolution surveys. We also investigate the effect of blending, finding that any sources with separations smaller than the beam size are fit as single sources. We show that the use of machine-learning techniques can correctly identify blended sources up to 90 per cent of the time, and prior-driven fitting can lead to a 70 per cent improvement in the number of de-blended sources.

  8. Iron(III) hydroxide solubility and humic-type fluorescent organic matter in the deep water column of the Okhotsk Sea and the northwestern North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Tani, Heihachiro; Nishioka, Jun; Kuma, Kenshi; Takata, Hyoe; Yamashita, Youhei; Tanoue, Eiichiro; Midorikawa, Takashi

    2003-09-01

    Vertical distributions of Fe(III) hydroxide solubility were studied in the Okhotsk Sea and the northwestern North Pacific Ocean during May and June 2000. Fe(III) solubility minima (0.35- 0.45 nM) were present in a narrow depth range (80- 100 m) below the surface mixed layer at all stations. In general, the Fe(III) solubility levels in intermediate and deep waters are characterized by mid-depth maxima (0.76- 0.86 nM) at 800- 1250 m depth and, below that, a slight decrease to 0.4- 0.6 nM with depth in association with increase in nutrient, apparent oxygen utilization (AOU) and humic-type fluorescence intensity. The most significant correlation between the Fe(III) solubility and humic-type fluorescence in intermediate and deep waters suggests that the distribution of humic-type fluorescent organic matter may control the distribution of Fe(III) solubility in deep ocean waters. The solubility profiles reveal that dissolved Fe concentrations in deep ocean waters may be controlled primarily by Fe(III) complexation with natural organic ligands, such as marine dissolved humic substances released through the oxidative decomposition and transformation of biogenic organic matter in intermediate and deep waters. In addition, high Fe(III) hydroxide solubility values (1.0- 1.6 nM) were observed in the surface mixed layer at a station in the northwestern North Pacific Ocean where a phytoplankton bloom was observed. The higher Fe(III) solubility in the surface waters was probably due to a higher concentration or stronger affinity of natural organic Fe(III) chelators, which may be released by dominant phytoplankton and/or bacteria during the spring bloom and probably have a different chemical composition from those found in intermediate and deep waters.

  9. DEEP GALEX UV SURVEY OF THE KEPLER FIELD. I. POINT SOURCE CATALOG

    SciTech Connect

    Olmedo, Manuel; Chávez, Miguel; Bertone, Emanuele; Lloyd, James; Mamajek, Eric E.; Martin, D. Christopher; Neill, James D.

    2015-11-10

    We report observations of a deep near-ultraviolet (NUV) survey of the Kepler field made in 2012 with the Galaxy Evolution Explorer (GALEX) Complete All-Sky UV Survey Extension (CAUSE). The GALEX-CAUSE Kepler survey (GCK) covers 104 square degrees of the Kepler field and reaches a limiting magnitude of NUV ≃ 22.6 at 3σ. Analysis of the GCK survey has yielded a catalog of 669,928 NUV sources, of which 475,164 are cross-matched with stars in the Kepler Input Catalog. Approximately 327 of 451 confirmed exoplanet host stars and 2614 of 4696 candidate exoplanet host stars identified by Kepler have NUV photometry in the GCK survey. The GCK catalog should enable the identification and characterization of UV-excess stars in the Kepler field (young solar-type and low-mass stars, chromospherically active binaries, white dwarfs, horizontal branch stars, etc.), and elucidation of various astrophysics problems related to the stars and planetary systems in the Kepler field.

  10. A 6 GHz Synoptic Survey of the COSMOS Deep Field with the JVLA

    NASA Astrophysics Data System (ADS)

    Sink, Joseph R.; Myers, Steven T.

    2016-01-01

    The Cosmic Evolution Survey (COSMOS) covers two square degrees, and is observed over a large portion of the electromagnetic spectrum from X-ray to Radio. Key science goals of COSMOS include probing the evolution of galaxies, AGN, and large scale structures of the Universe. As well as constraining cosmological models and the star and structure formation history of the Universe. The wide range of frequencies and deep surveys are suitable for many astrophysical studies.Beginning in 2013, observations of the COSMOS field in C-band (4 - 8 GHz) using the JVLA have been carried out in every configuration spanning 21 months (April 2013 - Jan 2015) for a total of 13 observations. The observations are comprised of 1 hour time blocks using a technique called On-The-Fly Mosaicking (OTFM). Using OTFM we see an increased efficiency for an allotted observation block by collecting data as the array scans across the field, rather than a pointed mosaic which requires settle down time after each new pointing. Each observation consists of 2160 1-second integrations on 432 phase centers that require calibration and image processing before they can be mosaicked to create the final image of the entire COSMOS field.The primary science goal of this survey is to identify, catalog, and study the variable and transient radio sources in the COSMOS field, comparing these to other radio, optical, IR, and X-ray observations. The main class of variables we are interested in Active Galactic Nuclei.

  11. Propulsion Utilizing Laser-Driven Ponderomotive Fields for Deep-Space Missions

    SciTech Connect

    Williams, George J.; Gilland, James H.

    2009-03-16

    The generation of large amplitude electric fields in plasmas by high-power lasers has been studied for several years in the context of high-energy particle acceleration. Fields on the order of GeV/m are generated in the plasma wake of the laser by non-linear ponderomotive forces. The laser fields generate longitudinal and translational electron plasma waves with phase velocities close to the speed of light. These fields and velocities offer the potential to revolutionize spacecraft propulsion, leading to extended deep space robotic probes. Based on these initial calculations, plasma acceleration by means of laser-induced ponderomotive forces appears to offer significant potential for spacecraft propulsion. Relatively high-efficiencies appear possible with proper beam conditioning, resulting in an order of magnitude more thrust than alternative concepts for high I{sub SP} (>10{sup 5} s) and elimination of the primary life-limiting erosion phenomena associated with conventional electric propulsion systems. Ponderomotive propulsion readily lends itself to beamed power which might overcome some of the constraints of power-limited propulsion concepts. A preliminary assessment of the impact of these propulsion systems for several promising configurations on mission architectures has been conducted. Emphasizing interstellar and interstellar-precursor applications, performance and technical requirements are identified for a number of missions. The use of in-situ plasma and gas for propellant is evaluated as well.

  12. Propulsion Utilizing Laser-Driven Ponderomotive Fields for Deep-Space Missions

    NASA Astrophysics Data System (ADS)

    Williams, George J.; Gilland, James H.

    2009-03-01

    The generation of large amplitude electric fields in plasmas by high-power lasers has been studied for several years in the context of high-energy particle acceleration. Fields on the order of GeV/m are generated in the plasma wake of the laser by non-linear ponderomotive forces. The laser fields generate longitudinal and translational electron plasma waves with phase velocities close to the speed of light. These fields and velocities offer the potential to revolutionize spacecraft propulsion, leading to extended deep space robotic probes. Based on these initial calculations, plasma acceleration by means of laser-induced ponderomotive forces appears to offer significant potential for spacecraft propulsion. Relatively high-efficiencies appear possible with proper beam conditioning, resulting in an order of magnitude more thrust than alternative concepts for high ISP (>105 s) and elimination of the primary life-limiting erosion phenomena associated with conventional electric propulsion systems. Ponderomotive propulsion readily lends itself to beamed power which might overcome some of the constraints of power-limited propulsion concepts. A preliminary assessment of the impact of these propulsion systems for several promising configurations on mission architectures has been conducted. Emphasizing interstellar and interstellar-precursor applications, performance and technical requirements are identified for a number of missions. The use of in-situ plasma and gas for propellant is evaluated as well.

  13. X-RAY GROUPS OF GALAXIES IN THE AEGIS DEEP AND WIDE FIELDS

    SciTech Connect

    Erfanianfar, G.; Lerchster, M.; Nandra, K.; Connelly, J. L.; Mirkazemi, M.; Finoguenov, A.; Tanaka, M.; Laird, E.; Bielby, R.; Faber, S. M.; Kocevski, D.; Jeltema, T.; Newman, J. A.; Coil, A. L.; Brimioulle, F.; Davis, M.; McCracken, H. J.; Willmer, C.; Gerke, B.; and others

    2013-03-10

    We present the results of a search for extended X-ray sources and their corresponding galaxy groups from 800 ks Chandra coverage of the All-wavelength Extended Groth Strip International Survey (AEGIS). This yields one of the largest X-ray-selected galaxy group catalogs from a blind survey to date. The red-sequence technique and spectroscopic redshifts allow us to identify 100% of reliable sources, leading to a catalog of 52 galaxy groups. These groups span the redshift range z {approx} 0.066-1.544 and virial mass range M{sub 200} {approx} 1.34 Multiplication-Sign 10{sup 13}-1.33 Multiplication-Sign 10{sup 14} M{sub Sun }. For the 49 extended sources that lie within DEEP2 and DEEP3 Galaxy Redshift Survey coverage, we identify spectroscopic counterparts and determine velocity dispersions. We select member galaxies by applying different cuts along the line of sight or in projected spatial coordinates. A constant cut along the line of sight can cause a large scatter in scaling relations in low-mass or high-mass systems depending on the size of the cut. A velocity-dispersion-based virial radius can cause a larger overestimation of velocity dispersion in comparison to an X-ray-based virial radius for low-mass systems. There is no significant difference between these two radial cuts for more massive systems. Independent of radial cut, an overestimation of velocity dispersion can be created in the case of the existence of significant substructure and compactness in X-ray emission, which mostly occur in low-mass systems. We also present a comparison between X-ray galaxy groups and optical galaxy groups detected using the Voronoi-Delaunay method for DEEP2 data in this field.

  14. Tectonic Framework of the Beaufort-Mackenzie Margin, Canadian Arctic Ocean, from Integrated Deep Seismic and Potential-Field Studies

    NASA Astrophysics Data System (ADS)

    Helwig, J. A.; Bird, D. E.; Kumar, N.; Emmet, P. A.; Dinkelman, M.

    2012-12-01

    A five-year long, ION ArcticSPAN seismic survey program in the Canadian Beaufort Sea expands and elaborates the tectonic framework of the Canada Basin passive margin. The margin is clearly subdivided into three segments of different orientation and structure: 1) the overprinted Cordilleran-Beaufort Foldbelt segment trending west towards Alaska; 2) the transtensional Tuk segment trending northeast off the Tuktoyaktuk Peninsula; and 3) the extensional Banks segment trending north off Banks Island. From nearshore to 2500 m depth, over 20,000 km of 2D long-offset data were acquired and processed into 40 km deep PSDM profiles. The latest lines used special technology for shooting beneath first-year ice-covered areas, and 450 km of OBC data were acquired in the nearshore transition zone. From well control in the Mackenzie Delta area, a geological interpretation is extended into the late Jurassic to Recent passive margin stratigraphy as well as the varying underlying crust of both oceanic affinity, and Ellesmerian and Laurentian continental affinities. Major elements of a tectonic synthesis include: 1) deep profiles show the Tertiary detached Beaufort foldbelt overlies greatly extended continental and/or oceanic crust although the COB is obscured by the overprint; 2) oceanic crust with steep relief is found at the inferred junction of the extinct spreading center of the Canada Basin in the Mackenzie delta; 3) on the Tuk margin, thick Proterozoic and Paleozoic strata flanking the Laurentian craton are terminated at the COB by a transform fault system; and 4) architecture of the Banks segment includes late Jurassic rift structure, and a continent-ocean transition beneath the continental slope prism that includes gravitational folds down-dip of shallower extensional break-away faults and rollover folds in the Tertiary. Our tectonic framework is consistent with a rotational model for opening of the Canada Basin. The free air gravity field is dominated by a high

  15. Investigating the flux of North Atlantic Deep Water into the South Atlantic Basin during Termination I: Observations from Neodymium Isotopes

    NASA Astrophysics Data System (ADS)

    Hartman, A. E.; Goldstein, S. L.; Hemming, S. R.; Pahnke, K.

    2010-12-01

    The South Atlantic is a region of intermixing between North Atlantic Deep Water (NADW) and southern-sourced deep waters. The strength of NADW formation can be used to monitor changes in meridional overturning circulation. Neodymium (Nd) isotopes have been shown to be a valuable water mass tracer in this region because the ɛNd value of intermediate and deep waters is dependent on the mixing ratio of southern- and northern-sourced water. A spliced record from cores RC11-83 (42.07°S, 9.717°E, 4718m) and TNO57-21 (40.6°S, 7.816°E, 4918 m) showed a decrease (>2ɛNd units) during the last termination, indicative of a retreat or shoaling of NADW in the South Atlantic during glacial periods1. Nearby core TNO57-6 (42.92°S, 8.88°E, 3750m) is slightly further south and significantly shallower than RC11-83/TNO57-21. A substantially greater Last Glacial Maximum (LGM) to Holocene offset (>4 ɛNd units) at this site was replicated in two studies1,2. The more dramatic shift was interpreted to record more Pacific-like waters reaching the TNO57-6 site, and the Circum-Antarctic in general, during the LGM. Here we show that the methods for obtaining the bottom water ɛNd signal were likely compromised by a contaminating phase within the fine sediment during leaching. To develop a reliable record for TNO57-6, we modified our previous procedure, in line with the Cambridge group3, and are extracting the ɛNd values of dissolved Fe-Mn oxide encrusted, mixed-species planktonic foraminifera. The ɛNd values of fish debris from the same depth confirm that the foram record is representing the bottom water signal. Although the new record still predicts an ɛNd unit decrease during Termination I, the bottom waters at this site during the LGM are less Pacific-like than originally thought. Therefore, the new record shows a very similar trend to RC11-83/TNO57-21 and both core sites were likely bathed in the same bottom waters during the LGM and Holocene. However, there are clues that the

  16. Clusters, groups, and filaments in the Chandra deep field-south up to redshift 1

    SciTech Connect

    Dehghan, S.; Johnston-Hollitt, M.

    2014-03-01

    We present a comprehensive structure detection analysis of the 0.3 deg{sup 2} area of the MUSYC-ACES field, which covers the Chandra Deep Field-South (CDFS). Using a density-based clustering algorithm on the MUSYC and ACES photometric and spectroscopic catalogs, we find 62 overdense regions up to redshifts of 1, including clusters, groups, and filaments. We also present the detection of a relatively small void of ∼10 Mpc{sup 2} at z ∼ 0.53. All structures are confirmed using the DBSCAN method, including the detection of nine structures previously reported in the literature. We present a catalog of all structures present, including their central position, mean redshift, velocity dispersions, and classification based on their morphological and spectroscopic distributions. In particular, we find 13 galaxy clusters and 6 large groups/small clusters. Comparison of these massive structures with published XMM-Newton imaging (where available) shows that 80% of these structures are associated with diffuse, soft-band (0.4-1 keV) X-ray emission, including 90% of all objects classified as clusters. The presence of soft-band X-ray emission in these massive structures (M {sub 200} ≥ 4.9 × 10{sup 13} M {sub ☉}) provides a strong independent confirmation of our methodology and classification scheme. In the closest two clusters identified (z < 0.13) high-quality optical imaging from the Deep2c field of the Garching-Bonn Deep Survey reveals the cD galaxies and demonstrates that they sit at the center of the detected X-ray emission. Nearly 60% of the clusters, groups, and filaments are detected in the known enhanced density regions of the CDFS at z ≅ 0.13, 0.52, 0.68, and 0.73. Additionally, all of the clusters, bar the most distant, are found in these overdense redshift regions. Many of the clusters and groups exhibit signs of ongoing formation seen in their velocity distributions, position within the detected cosmic web, and in one case through the presence of tidally

  17. Microsurgical robotic system for the deep surgical field: development of a prototype and feasibility studies in animal and cadaveric models.

    PubMed

    Morita, Akio; Sora, Shigeo; Mitsuishi, Mamoru; Warisawa, Shinichi; Suruman, Katopo; Asai, Daisuke; Arata, Junpei; Baba, Shoichi; Takahashi, Hidechika; Mochizuki, Ryo; Kirino, Takaaki

    2005-08-01

    To enhance the surgeon's dexterity and maneuverability in the deep surgical field, the authors developed a master-slave microsurgical robotic system. This concept and the results of preliminary experiments are reported in this paper. The system has a master control unit, which conveys motion commands in six degrees of freedom (X, Y, and Z directions; rotation; tip flexion; and grasping) to two arms. The slave manipulator has a hanging base with an additional six degrees of freedom; it holds a motorized operating unit with two manipulators (5 mm in diameter, 18 cm in length). The accuracy of the prototype in both shallow and deep surgical fields was compared with routine freehand microsurgery. Closure of a partial arteriotomy and complete end-to-end anastomosis of the carotid artery (CA) in the deep operative field were performed in 20 Wistar rats. Three routine surgical procedures were also performed in cadavers. The accuracy of pointing with the nondominant hand in the deep surgical field was significantly improved through the use of robotics. The authors successfully closed the partial arteriotomy and completely anastomosed the rat CAs in the deep surgical field. The time needed for stitching was significantly shortened over the course of the first 10 rat experiments. The robotic instruments also moved satisfactorily in cadavers, but the manipulators still need to be smaller to fit into the narrow intracranial space. Computer-controlled surgical manipulation will be an important tool for neurosurgery, and preliminary experiments involving this robotic system demonstrate its promising maneuverability.

  18. Deep ocean sound speed characteristics passively derived from the ambient acoustic noise field

    NASA Astrophysics Data System (ADS)

    Evers, L. G.; Wapenaar, K.; Heaney, K. D.; Snellen, M.

    2017-02-01

    The propagation of acoustic waves in the ocean strongly depends on the temperature. Low frequency acoustic waves can penetrate the ocean down to depths where few in-situ measurements are available. It is therefore attractive to obtain a measure of the deep ocean temperature from acoustic waves. The latter is especially true if the ambient acoustic noise field can be used instead of deterministic transient signals. In this study the acoustic velocity, and hence the temperature, is derived in an interferometric approach from hydrophone array recordings. The arrays were separated by over 125 km, near Ascension Island in the Atlantic Ocean, at a depth of 850m. Furthermore, the dispersive characteristics of the deep ocean sound channel are resolved based on the retrieved lag times for different modes. In addition, it is shown how the resolution of the interferometric approach can be increased by cross correlating array beams rather than recordings from single-sensor pairs. The observed acoustic lag times between the arrays corresponds well to modeled values, based on full-wave modeling through best-known oceanic models.

  19. Redshifts of Emission-Line Objects in the Hubble Ultra Deep Field

    NASA Astrophysics Data System (ADS)

    Xu, Chun; Pirzkal, Norbert; Malhotra, Sangeeta; Rhoads, James E.; Mobasher, Bahram; Daddi, Emanuele; Gronwall, Caryl; Hathi, Nimish P.; Panagia, Nino; Ferguson, Henry C.; Koekemoer, Anton M.; Kümmel, Martin; Moustakas, Leonidas A.; Pasquali, Anna; di Serego Alighieri, Sperello; Vernet, Joel; Walsh, Jeremy R.; Windhorst, Rogier; Yan, Haojing

    2007-07-01

    We present redshifts for 115 emission-line objects in the Hubble Ultra Deep Field identified through the Grism ACS Program for Extragalactic Science (GRAPES) project using the slitless grism spectroscopy mode of the Advanced Camera for Surveys on the Hubble Space Telescope (HST). The sample was selected by an emission-line search on all extracted one-dimensional GRAPES spectra. We identify the emission lines using line wavelength ratios where multiple lines are detected in the grism wavelength range (5800 Å<~λ<~9600 Å), and using photometric redshift information where multiple lines are unavailable. We then derive redshifts using the identified lines. Our redshifts are accurate to δz~0.009, based on both statistical uncertainty estimates and comparison with published ground-based spectra. Over 40% of our sample is fainter than typical magnitude limits for ground-based spectroscopy (with iAB>25 mag). Such emission lines would likely remain undiscovered without our deep survey. The emission-line objects fall into three categories: (1) most are low- to moderate-redshift galaxies (0<=z<=2), including many actively star-forming galaxies with strong H II regions; (2) nine are high-redshift (4<=z<=7) Lyα emitters; and (3) at least three are candidate active galactic nuclei.

  20. GRAPES, Grism Spectroscopy of the Hubble Ultra Deep Field: Description and Data Reduction

    NASA Astrophysics Data System (ADS)

    Pirzkal, N.; Xu, C.; Malhotra, S.; Rhoads, J. E.; Koekemoer, A. M.; Moustakas, L. A.; Walsh, J. R.; Windhorst, R. A.; Daddi, E.; Cimatti, A.; Ferguson, H. C.; Gardner, Jonathan P.; Gronwall, C.; Haiman, Z.; Kümmel, M.; Panagia, N.; Pasquali, A.; Stiavelli, M.; di Serego Alighieri, S.; Tsvetanov, Z.; Vernet, J.; Yan, H.

    2004-10-01

    We present deep unbiased spectroscopy of the Hubble Ultra Deep Field (UDF) carried out using the slitless grism spectroscopy mode of the Advanced Camera for Surveys on the Hubble Space Telescope (HST). The Grism ACS Program for Extragalactic Science (GRAPES) achieves continuum detection as faint as zAB=27.2 using 40 orbits (9.2×104 s) on HST. The data were taken at four orientation angles to correct for the overlap of spectra. GRAPES data provide a unique, uninterrupted, low-resolution (R=100) spectral coverage for 5500Å<λ<10500Å and allow us to detect high-redshift galaxies at 4

  1. Implementation Plan for the Deep Vadose Zone-Applied Field Research Center

    SciTech Connect

    Wellman, Dawn M.; Truex, Michael J.; Freshley, Mark D.; Gephart, Roy E.; Triplett, Mark B.; Johnson, Timothy C.

    2011-02-11

    The Long-Range Deep Vadose Zone Program Plan was published in October 2010. It summarized the U.S. Department of Energy’s (DOE’s) state-of-knowledge about the contaminant remediation challenges facing the deep vadose zone (DVZ) beneath the Central Plateau of the Hanford Site and their approach to solving those challenges. Developing an implementation plan is the next step to address the knowledge and capabilities required to solve DVZ challenges when needed. This multi-year plan (FY-11 through FY-20) identifies the short to long-term research, management, and execution plans required to solve those problems facing the DVZ-Applied Field Research Center (DVZ-AFRC). The schedule supporting implementation overlies existing activities and milestones from Hanford’s DOE-Environmental Management (EM) end-user projects. Success relies upon multi-project teams focused on coordinated subsurface projects undertaken across the DOE Complex combined with facilitated, problem-focused, research investments implemented through the DVZ-AFRC.

  2. Feasibility study to identify deep Earth signals in current and future gravity field missions

    NASA Astrophysics Data System (ADS)

    Ghelichkhan, S.; Murböck, M.; Pail, R.; Colli, L.; Bunge, H. P.

    2016-12-01

    Next generation gravity missions are expected to improve the accuracy of temporal Earth's gravity models significantly. Periodic signals and trends are related to mass redistributions in the Earth system and carry essential information on dynamic processes in the atmosphere, cryosphere, hydrosphere and the solid Earth. Gravity signals from the deep solid Earth are commonly thought to lie below the detection limit of satellite gravity missions, as one assumes them to have very small amplitudes and be restricted to the longest spatial and temporal scales. However, robust evidence from geologic records exists for episodes of very rapid uplift and subsidence events at regional scales, especially along passive continental margins. These uplift and subsidence events, which are inferred from regional seismic stratigraphy, landscape evolution studies, and the analysis of river profiles, result from flow in the underlying mantle and imply faster rates and smaller scales for the contribution of the solid Earth to the time-dependent gravity field. Here we exploit high resolution global mantle convection models capable of resolving fine scale mantle flow in conjunction with an innovative adjoint method. The adjoint method allows us to derive time trajectories for global mantle flow, thus providing first order estimates for temporal variations of gravity signals related to solid Earth. This is then analyzed with numerical low-low SST closed-loop simulations including GRACE-like observation noise. We find out that a Bender-type double pair mission scenario would be able to resolve the gravitational signal from deep mantle convection.

  3. A Deep-Structured Conditional Random Field Model for Object Silhouette Tracking

    PubMed Central

    Shafiee, Mohammad Javad; Azimifar, Zohreh; Wong, Alexander

    2015-01-01

    In this work, we introduce a deep-structured conditional random field (DS-CRF) model for the purpose of state-based object silhouette tracking. The proposed DS-CRF model consists of a series of state layers, where each state layer spatially characterizes the object silhouette at a particular point in time. The interactions between adjacent state layers are established by inter-layer connectivity dynamically determined based on inter-frame optical flow. By incorporate both spatial and temporal context in a dynamic fashion within such a deep-structured probabilistic graphical model, the proposed DS-CRF model allows us to develop a framework that can accurately and efficiently track object silhouettes that can change greatly over time, as well as under different situations such as occlusion and multiple targets within the scene. Experiment results using video surveillance datasets containing different scenarios such as occlusion and multiple targets showed that the proposed DS-CRF approach provides strong object silhouette tracking performance when compared to baseline methods such as mean-shift tracking, as well as state-of-the-art methods such as context tracking and boosted particle filtering. PMID:26313943

  4. The Metal Abundances across Cosmic Time (MACT) Survey. I. Optical Spectroscopy in the Subaru Deep Field

    NASA Astrophysics Data System (ADS)

    Ly, Chun; Malhotra, Sangeeta; Malkan, Matthew A.; Rigby, Jane R.; Kashikawa, Nobunari; de los Reyes, Mithi A.; Rhoads, James E.

    2016-09-01

    Deep rest-frame optical spectroscopy is critical for characterizing and understanding the physical conditions and properties of the ionized gas in galaxies. Here, we present a new spectroscopic survey called “Metal Abundances across Cosmic Time” or { M }{ A }{ C }{ T }, which will obtain rest-frame optical spectra for ˜3000 emission-line galaxies. This paper describes the optical spectroscopy that has been conducted with MMT/Hectospec and Keck/DEIMOS for ≈1900 z = 0.1-1 emission-line galaxies selected from our narrowband and intermediate-band imaging in the Subaru Deep Field. In addition, we present a sample of 164 galaxies for which we have measured the weak [O iii]λ4363 line (66 with at least 3σ detections and 98 with significant upper limits). This nebular emission line determines the gas-phase metallicity by measuring the electron temperature of the ionized gas. This paper presents the optical spectra, emission-line measurements, interstellar properties (e.g., metallicity, gas density), and stellar properties (e.g., star formation rates, stellar mass). Paper II of the { M }{ A }{ C }{ T } survey (Ly et al.) presents the first results on the stellar mass-gas metallicity relation at z ≲ 1 using the sample with [O iii]λ4363 measurements.

  5. Selected First Results from the 7 Ms Chandra Deep Field-South Survey

    NASA Astrophysics Data System (ADS)

    Brandt, W. Niel; Chandra Deep Field-South Team

    2017-01-01

    The exposure on the Chandra Deep Field-South (CDF-S) has recently been increased to 7 Ms, making it the most sensitive extragalactic X-ray survey by a wide margin. About 1050 X-ray sources have been detected, primarily distant active galactic nuclei (AGNs) and starburst/normal galaxies. The unmatched deep multiwavelength coverage for these sources allows superb follow-up investigations; e.g., 98.4% of the X-ray sources have multiwavelength counterparts, and 97.8% have spectroscopic/photometric redshifts. I will briefly describe the source catalog for the 7 Ms CDF-S and some exciting first science results. The latter will likely include (1) constraints on SMBH growth in the first galaxies as revealed by direct detection and stacking; (2) long-term variability studies of the AGNs producing most of cosmic accretion power; (3) AGN/galaxy interactions as investigated via the host properties of X-ray AGNs; and (4) measurements of the evolving X-ray binary populations of normal and starburst galaxies.

  6. Deep ocean sound speed characteristics passively derived from the ambient acoustic noise field

    NASA Astrophysics Data System (ADS)

    Evers, L. G.; Wapenaar, K.; Heaney, K. D.; Snellen, M.

    2017-07-01

    The propagation of acoustic waves in the ocean strongly depends on the temperature. Low-frequency acoustic waves can penetrate the ocean down to depths where few in situ measurements are available. It is therefore attractive to obtain a measure of the deep ocean temperature from acoustic waves. The latter is especially true if the ambient acoustic noise field can be used instead of deterministic transient signals. In this study the acoustic velocity, and hence the temperature, is derived in an interferometric approach from hydrophone array recordings. The arrays were separated by over 125 km, near Ascension Island in the Atlantic Ocean, at a depth of 850 m. Furthermore, the dispersive characteristics of the deep ocean sound channel are resolved based on the retrieved lag times for different modes. In addition, it is shown how the resolution of the interferometric approach can be increased by cross correlating array beams rather than recordings from single-sensor pairs. The observed acoustic lag times between the arrays corresponds well to modelled values, based on full-wave modelling through best-known oceanic models.

  7. Feasibility study to identify deep Earth signals in current and future gravity field missions

    NASA Astrophysics Data System (ADS)

    Ghelichkhan, Siavash; Murböck, Michael; Colli, Lorenzo; Pail, Roland; Bunge, Hans-Peter

    2017-04-01

    Next generation gravity missions are expected to improve the accuracy of temporal Earth's gravity models significantly. Periodic signals and trends are related to mass redistributions in the Earth system and carry essential information on dynamic processes in the atmosphere, cryosphere, hydrosphere and the solid Earth. Gravity signals from the deep solid Earth are commonly thought to lie below the detection limit of satellite gravity missions, as one assumes them to have very small amplitudes and be restricted to the longest spatial and temporal scales. However, robust evidence from geologic records exists for episodes of very rapid uplift and subsidence events at regional scales, especially along passive continental margins. These uplift and subsidence events, which are inferred from regional seismic stratigraphy, landscape evolution studies, and the analysis of river profiles, result from flow in the underlying mantle and imply faster rates and smaller scales for the contribution of the solid Earth to the time-dependent gravity field. Here we exploit high resolution global mantle convection models capable of resolving fine scale mantle flow in conjunction with an innovative adjoint method. The adjoint method allows us to derive time trajectories for global mantle flow, thus providing first order estimates for temporal variations of gravity signals related to solid Earth. This is then analyzed with numerical low-low SST closed-loop simulations including GRACE-like observation noise. We find out that a Bender-type double pair mission scenario would be able to resolve the gravitational signal from deep mantle convection.

  8. Sulfur metabolisms in epsilon- and gamma-proteobacteria in deep-sea hydrothermal fields.

    PubMed

    Yamamoto, Masahiro; Takai, Ken

    2011-01-01

    In deep-sea hydrothermal systems, super hot and reduced vent fluids from the subseafloor blend with cold and oxidized seawater. Very unique and dense ecosystems are formed within these environments. Many molecular ecological studies showed that chemoautotrophic epsilon- and gamma-Proteobacteria are predominant primary producers in both free-living and symbiotic microbial communities in global deep-sea hydrothermal fields. Inorganic sulfur compounds are important substrates for the energy conservative metabolic pathways in these microorganisms. Recent genomic and metagenomic analyses and biochemical studies have contributed to the understanding of potential sulfur metabolic pathways for these chemoautotrophs. Epsilon-Proteobacteria use sulfur compounds for both electron-donors and -acceptors. On the other hand, gamma-Proteobacteria utilize two different sulfur-oxidizing pathways. It is hypothesized that differences between the metabolic pathways used by these two predominant proteobacterial phyla are associated with different ecophysiological strategies; extending the energetically feasible habitats with versatile energy metabolisms in the epsilon-Proteobacteria and optimizing energy production rate and yield for relatively narrow habitable zones in the gamma-Proteobacteria.

  9. Sulfur Metabolisms in Epsilon- and Gamma-Proteobacteria in Deep-Sea Hydrothermal Fields

    PubMed Central

    Yamamoto, Masahiro; Takai, Ken

    2011-01-01

    In deep-sea hydrothermal systems, super hot and reduced vent fluids from the subseafloor blend with cold and oxidized seawater. Very unique and dense ecosystems are formed within these environments. Many molecular ecological studies showed that chemoautotrophic epsilon- and gamma-Proteobacteria are predominant primary producers in both free-living and symbiotic microbial communities in global deep-sea hydrothermal fields. Inorganic sulfur compounds are important substrates for the energy conservative metabolic pathways in these microorganisms. Recent genomic and metagenomic analyses and biochemical studies have contributed to the understanding of potential sulfur metabolic pathways for these chemoautotrophs. Epsilon-Proteobacteria use sulfur compounds for both electron-donors and -acceptors. On the other hand, gamma-Proteobacteria utilize two different sulfur-oxidizing pathways. It is hypothesized that differences between the metabolic pathways used by these two predominant proteobacterial phyla are associated with different ecophysiological strategies; extending the energetically feasible habitats with versatile energy metabolisms in the epsilon-Proteobacteria and optimizing energy production rate and yield for relatively narrow habitable zones in the gamma-Proteobacteria. PMID:21960986

  10. Epicontinental- to deep marine environmental transitions in the Triassic rifted margin of the north Arabian plate, Israel

    NASA Astrophysics Data System (ADS)

    Korngreen, Dorit; Benjamini, Chaim

    2010-05-01

    The transition from the Arabian plate epicontinental margin toward the deeper marine depositional system of the Middle to Late Triassic is tracked using data from deep boreholes in northern Israel. Biotic, sedimentological and diagenetic components from borehole cuttings were used to construct a carbonate-evaporitic depositional facies model for the Triassic. Three N-S trending subparallel facies strips were recognized, trending along a narrow belt less than 45 km wide but 300 km long. The proximal stable inland region is an extension of the epicontinental marginal marine facies during the Anisian. To the north and west lies the second strip, characterized by a subsiding platform. In this strip, sections are consistently much thicker than the proximal strip, more richly fossiliferous with open marine microfauna, and where evaporitic, tend to have more salina -like features than the sabkhas typical of the more eastern facies strip. Despite these differences, these two facies strips have many features in common. A short-lived tectonic phase in the Pelsonian is recognized in both strips and interpreted as rifting, taking place over no more than 3 Myr. Both strips react to sea level rise in the Ladinian by increased deposition of carbonates, and to salinity changes in the Carnian by establishment of evaporitic regimes. A second short-lived rifting phase in the Tuvalian took place over no more than 7 Myr. Northward thickening commenced in the Anisian and continued into the late Carnian, to values well above average for the Triassic of the Arabian margin. Norian termination of rifting and evaporite deposition was accompanied by reversal of the subsidence pattern, with greater uplift towards the north. This uplift is apparently associated with volcanic thermal doming, but also represents the first phase of extensive uplift known regionally at the base of the Jurassic. The western-most strip is the more tectonically active coastal shelf-edge region, displaying a facies

  11. Marine litter on deep Arctic seafloor continues to increase and spreads to the North at the HAUSGARTEN observatory

    NASA Astrophysics Data System (ADS)

    Tekman, Mine B.; Krumpen, Thomas; Bergmann, Melanie

    2017-02-01

    The increased global production of plastics has been mirrored by greater accumulations of plastic litter in marine environments worldwide. Global plastic litter estimates based on field observations account only for 1% of the total volumes of plastic assumed to enter the marine ecosystem from land, raising again the question 'Where is all the plastic? '. Scant information exists on temporal trends on litter transport and litter accumulation on the deep seafloor. Here, we present the results of photographic time-series surveys indicating a strong increase in marine litter over the period of 2002-2014 at two stations of the HAUSGARTEN observatory in the Arctic (2500 m depth). Plastic accounted for the highest proportion (47%) of litter recorded at HAUSGARTEN for the whole study period. When the most southern station was considered separately, the proportion of plastic items was even higher (65%). Increasing quantities of small plastics raise concerns about fragmentation and future microplastic contamination. Analysis of litter types and sizes indicate temporal and spatial differences in the transport pathways to the deep sea for different categories of litter. Litter densities were positively correlated with the counts of ship entering harbour at Longyearbyen, the number of active fishing vessels and extent of summer sea ice. Sea ice may act as a transport vehicle for entrained litter, being released during periods of melting. The receding sea ice coverage associated with global change has opened hitherto largely inaccessible environments to humans and the impacts of tourism, industrial activities including shipping and fisheries, all of which are potential sources of marine litter.

  12. Automatic land cover classification of geo-tagged field photos using deep learning method

    NASA Astrophysics Data System (ADS)

    Xu, G.; Zhu, X.; Fu, D.; Dong, J.; Xiao, X.

    2016-12-01

    With the popularity of smartphones, more and more crowdsourcing geo-tagged field photos have been shared by the public online. They are becoming a potentially valuable information source for the environmental studies. However, the labelling and recognition of these photos are time-consuming. To utilise and exploit such information, this research aims to propose a land cover type recognition model for geo-tagged field photo based on the deep learning technique. This model combines a pre-trained convolutional neural network (CNN) as the image feature extractor and the softmax regression model as the feature classifier. The pre-trained CNN model Inception-v3 is used in this study. The previously labelled field photos from the Global Geo-Referenced Field Photo Library (http://eomf.ou.edu/photos) are chosen for model training and validation. The results indicate that our field photo recognition model achieves an acceptable accuracy (50.34% for top-1 prediction and 78.20% for top-3 prediction) of land cover classification. What is more important, this model can provide the probabilities for the predictions as the self-assessment of uncertainty. After filtering out the predictions with the certainty of less than 75%, the overall accuracy can increase to 80.14%, which implies that the model is fully aware of its prediction uncertainty and can quantitatively assess it. Hopefully, by proving the possibility of this type of research, other similar studies could be further conducted, such as geological and atmospheric information extraction from field photos. This research could be a critical exploration of how artificial intelligence and crowd-sourced data can help the earth studies.

  13. Vacuum field-effect transistor with a deep submicron channel fabricated by electro-forming

    NASA Astrophysics Data System (ADS)

    Wang, Xiao; Shen, Zhihua; Wu, Shengli; Zhang, Jintao

    2017-06-01

    Vacuum field-effect transistors (VFETs) with channel lengths down to 500 nm (i.e., the deep submicron scale) were fabricated with the mature technology of the surface conduction electron emitter fabrication process in our former experiments. The vacuum channel of this new VFET was generated by using the electro-forming process. During electro-forming, the joule heat cracks the conductive film and then generates the submicron scale gap that serves as the vacuum channel. The gap separates the conductive film into two plane-to-plane electrodes, which serve as a source (cathode) electrode and a drain (anode) electrode of the VFET, respectively. Experimental results reveal that the fabricated device demonstrates a clear triode behavior of the gate modulation. Fowler-Nordheim theory was used to analyze the electron emission mechanism and operating principle of the device.

  14. Changes in North Atlantic deep-sea temperature during climatic fluctuations of the last 25,000 years based on ostracode Mg/Ca ratios

    USGS Publications Warehouse

    Dwyer, Gary S.; Cronin, Thomas M.; Baker, Paul A.; Rodriguez-Lazaro, Julio

    2000-01-01

    We reconstructed three time series of last glacial-to-present deep-sea temperature from deep and intermediate water sediment cores from the western North Atlantic using Mg/Ca ratios of benthic ostracode shells. Although the Mg/Ca data show considerable variability (“scatter”) that is common to single-shell chemical analyses, comparisons between cores, between core top shells and modern bottom water temperatures (BWT), and comparison to other paleo-BWT proxies, among other factors, suggest that multiple-shell average Mg/Ca ratios provide reliable estimates of BWT history at these sites. The BWT records show not only glacial-to-interglacial variations but also indicate BWT changes during the deglacial and within the Holocene interglacial stage. At the deeper sites (4500- and 3400-m water depth), BWT decreased during the last glacial maximum (LGM), the late Holocene, and possibly during the Younger Dryas. Maximum deep-sea warming occurred during the latest deglacial and early Holocene, when BWT exceeded modern values by as much as 2.5°C. This warming was apparently most intense around 3000 m, the depth of the modern-day core of North Atlantic deep water (NADW). The BWT variations at the deeper water sites are consistent with changes in thermohaline circulation: warmer BWT signifies enhanced NADW influence relative to Antarctic bottom water (AABW). Thus maximum NADW production and associated heat flux likely occurred during the early Holocene and decreased abruptly around 6500 years B.P., a finding that is largely consistent with paleonutrient studies in the deep North Atlantic. BWT changes in intermediate waters (1000-m water depth) of the subtropical gyre roughly parallel the deep BWT variations including dramatic mid-Holocene cooling of around 4°C. Joint consideration of the Mg/Ca-based BWT estimates and benthic oxygen isotopes suggests that the cooling was accompanied by a decrease in salinity at this site. Subsequently, intermediate waters warmed to modern

  15. FORS spectroscopy of galaxies in the Hubble Deep Field-South

    NASA Astrophysics Data System (ADS)

    Rigopoulou, D.; Vacca, W. D.; Berta, S.; Franceschini, A.; Aussel, H.

    2005-09-01

    We present low resolution multi-object spectroscopy of an I-band magnitude limited (IAB ≃ 23-23.5) sample of galaxies located in an area centered on the Hubble Deep Field-South (HDFS). The observations were obtained using the Focal Reducer/low dispersion Spectrograph (FORS) on the ESO Very Large Telescope. Thirty-two primary spectroscopic targets in the HST-WFPC2 HDFS were supplemented with galaxies detected in the Infrared Space Observatory's survey of the HDFS and the ESO Imaging Deep Survey to comprise a sample of 100 galaxies for spectroscopic observations. Based on detections of several emission lines, such as [OII]λ3727, Hβ and [OIII]λ5007, or of other spectroscopic features, we measured accurate redshifts for 50 objects in the central HDFS and flanking fields. The redshift range of the current sample of galaxies is 0.6-1.2, with a median redshift of 1.13 (at I ≃ 23.5 not corrected for completeness). The sample is dominated by starburst galaxies with only a small fraction of ellipticals (~10%). For the emission line objects, the extinction corrected [OII]λ3727 line strengths yield estimates of star formation rates in the range 0.5-30 M⊙ yr-1. We used the present data to derive the [OII]λ3727 luminosity function up to redshift of 1.2. When combined with [OII]λ3727 luminosity densities for the local and high redshift Universe, our results confirm the steep rise in the star formation rate (SFR) to z ≃ 1.3.

  16. NEW CONSTRAINTS ON COSMIC REIONIZATION FROM THE 2012 HUBBLE ULTRA DEEP FIELD CAMPAIGN

    SciTech Connect

    Robertson, Brant E.; Schneider, Evan; Stark, Daniel P.; Furlanetto, Steven R.; Charlot, Stephane; Ellis, Richard S.; Schenker, Matthew A.; McLure, Ross J.; Dunlop, James S.; Curtis-Lake, Emma; Rogers, Alexander B.; Bowler, Rebecca A. A.; Cirasuolo, Michele; Koekemoer, Anton; Ouchi, Masami; Ono, Yoshiaki

    2013-05-01

    Understanding cosmic reionization requires the identification and characterization of early sources of hydrogen-ionizing photons. The 2012 Hubble Ultra Deep Field (UDF12) campaign has acquired the deepest infrared images with the Wide Field Camera 3 aboard Hubble Space Telescope and, for the first time, systematically explored the galaxy population deep into the era when cosmic microwave background (CMB) data indicate reionization was underway. The UDF12 campaign thus provides the best constraints to date on the abundance, luminosity distribution, and spectral properties of early star-forming galaxies. We synthesize the new UDF12 results with the most recent constraints from CMB observations to infer redshift-dependent ultraviolet (UV) luminosity densities, reionization histories, and electron scattering optical depth evolution consistent with the available data. Under reasonable assumptions about the escape fraction of hydrogen-ionizing photons and the intergalactic medium clumping factor, we find that to fully reionize the universe by redshift z {approx} 6 the population of star-forming galaxies at redshifts z {approx} 7-9 likely must extend in luminosity below the UDF12 limits to absolute UV magnitudes of M{sub UV} {approx} -13 or fainter. Moreover, low levels of star formation extending to redshifts z {approx} 15-25, as suggested by the normal UV colors of z {approx_equal} 7-8 galaxies and the smooth decline in abundance with redshift observed by UDF12 to z {approx_equal} 10, are additionally likely required to reproduce the optical depth to electron scattering inferred from CMB observations.

  17. ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Survey Description

    NASA Astrophysics Data System (ADS)

    Walter, Fabian; Decarli, Roberto; Aravena, Manuel; Carilli, Chris; Bouwens, Rychard; da Cunha, Elisabete; Daddi, Emanuele; Ivison, R. J.; Riechers, Dominik; Smail, Ian; Swinbank, Mark; Weiss, Axel; Anguita, Timo; Assef, Roberto; Bacon, Roland; Bauer, Franz; Bell, Eric F.; Bertoldi, Frank; Chapman, Scott; Colina, Luis; Cortes, Paulo C.; Cox, Pierre; Dickinson, Mark; Elbaz, David; Gónzalez-López, Jorge; Ibar, Edo; Inami, Hanae; Infante, Leopoldo; Hodge, Jacqueline; Karim, Alex; Le Fevre, Olivier; Magnelli, Benjamin; Neri, Roberto; Oesch, Pascal; Ota, Kazuaki; Popping, Gergö; Rix, Hans-Walter; Sargent, Mark; Sheth, Kartik; van der Wel, Arjen; van der Werf, Paul; Wagg, Jeff

    2016-12-01

    We present the rationale for and the observational description of ASPECS: the ALMA SPECtroscopic Survey in the Hubble Ultra-Deep Field (UDF), the cosmological deep field that has the deepest multi-wavelength data available. Our overarching goal is to obtain an unbiased census of molecular gas and dust continuum emission in high-redshift (z > 0.5) galaxies. The ˜1‧ region covered within the UDF was chosen to overlap with the deepest available imaging from the Hubble Space Telescope. Our ALMA observations consist of full frequency scans in band 3 (84-115 GHz) and band 6 (212-272 GHz) at approximately uniform line sensitivity ({L}{CO}\\prime ˜ 2 × 109 K km s-1 pc2), and continuum noise levels of 3.8 μJy beam-1 and 12.7 μJy beam-1, respectively. The molecular surveys cover the different rotational transitions of the CO molecule, leading to essentially full redshift coverage. The [C ii] emission line is also covered at redshifts 6.0\\lt z\\lt 8.0. We present a customized algorithm to identify line candidates in the molecular line scans and quantify our ability to recover artificial sources from our data. Based on whether multiple CO lines are detected, and whether optical spectroscopic redshifts as well as optical counterparts exist, we constrain the most likely line identification. We report 10 (11) CO line candidates in the 3 mm (1 mm) band, and our statistical analysis shows that <4 of these (in each band) are likely spurious. Less than one-third of the total CO flux in the low-J CO line candidates are from sources that are not associated with an optical/NIR counterpart. We also present continuum maps of both the band 3 and band 6 observations. The data presented here form the basis of a number of dedicated studies that are presented in subsequent papers.

  18. Effects of Vegetated Field Borders on Arthropods in Cotton Fields in Eastern North Carolina

    PubMed Central

    Outward, Randy; Sorenson, Clyde E.; Bradley, J. R.

    2008-01-01

    The influence, if any, of 5m wide, feral, herbaceous field borders on pest and beneficial arthropods in commercial cotton, Gossypium hirsutum (L.) (Malvales: Malvaceae), fields was measured through a variety of sampling techniques over three years. In each year, 5 fields with managed, feral vegetation borders and five fields without such borders were examined. Sampling was stratified from the field border or edge in each field in an attempt to elucidate any edge effects that might have occurred. Early season thrips populations appeared to be unaffected by the presence of a border. Pitfall sampling disclosed no differences in ground-dwelling predaceous arthropods but did detect increased populations of crickets around fields with borders. Cotton aphid (Aphis gossypii Glover) (Hemiptera: Aphididae) populations were too low during the study to adequately assess border effects. Heliothines, Heliothis virescens (F.) and Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), egg numbers and damage rates were largely unaffected by the presence or absence of a border, although in one instance egg numbers were significantly lower in fields with borders. Overall, foliage-dwelling predaceous arthropods were somewhat more abundant in fields with borders than in fields without borders. Tarnished plant bugs, Lygus lineolaris (Palisot de Beauvois) (Heteroptera: Miridae) were significantly more abundant in fields with borders, but stink bugs, Acrosternum hilare (Say), and Euschistus servus (Say) (Hemiptera: Pentatomidae) numbers appeared to be largely unaffected by border treatment. Few taxa clearly exhibited distributional edge effects relative to the presence or absence of border vegetation. Field borders like those examined in this study likely will have little impact on insect pest management in cotton under current insect management regimens. PMID:20345293

  19. Deep Mantle Dynamics under the North American Continent Drives Localised Flow and Stress Below the New Madrid Seismic Zone

    NASA Astrophysics Data System (ADS)

    Forte, A. M.; Mitrovica, J. X.; Moucha, R.; Simmons, N. A.; Grand, S. P.

    2007-12-01

    The origin of intraplate earthquakes represents one of the outstanding problems in modern geophysical research, and the major earthquake sequence that struck the central Mississippi River Valley in 1811-1812, the so-called New Madrid seismic sequence, has become a principal target of this research. As Johnston and Schweig (1996) have noted, the occurrence of such large magnitude earthquakes in "stable" North American crust, far from any plate boundaries, remains an enigma. To understand the possible origin of this enigmatic seismic activity we have developed a new high resolution model of mantle flow below North America. The model is constrained by simultaneously inverting global seismic and mantle-convection data sets and it includes an explicit treatment of the positive chemical buoyancy of the continental tectosphere. Moreover, it adopts a depth dependent mantle viscosity structure which reconciles both glacial isostatic adjustment (GIA) and convection data. The flow model successfully reproduces plate velocities and observations of surface gravity and topography, including the continent-scale quasi-linear depression (after corrections for GIA and crustal heterogeneity) extending from northern Alaska to Venezuela. The predictions also match lithospheric flow and stress fields inferred from local and regional measurements of seismic anisotropy and surface deformation. We demonstrate that these signals are largely driven by viscous flow coupled to density anomalies within the lower mantle associated with the descent of the ancient Kula-Farallon plate system. More importantly, the flow calculations elucidate how these large-scale heterogeneities give rise to flow and stress patterns below the New Madrid Seismic Zone which are favourably oriented with respect the local fault geometry in this portion of the Mississippi valley.

  20. STAR FORMATION IN THE CHANDRA DEEP FIELD SOUTH: OBSERVATIONS CONFRONT SIMULATIONS

    SciTech Connect

    Damen, Maaike; Franx, Marijn; Foerster Schreiber, Natascha M.; Labbe, Ivo; Toft, Sune; Van Dokkum, Pieter G.; Wuyts, Stijn

    2009-11-01

    We investigate the star formation history of the universe using FIREWORKS, a multiwavelength survey of the Chandra Deep Field South. We study the evolution of the specific star formation rate (sSFR) with redshift in different mass bins from z = 0 to z approx 3. We find that the sSFR increases with redshift for all masses. The logarithmic increase of the sSFR with redshift is nearly independent of mass, but this cannot yet be verified at the lowest-mass bins at z>0.8, due to incompleteness. We convert the sSFRs to a dimensionless growth rate to facilitate a comparison with a semianalytic galaxy formation model that was implemented on the Millennium Simulation. The model predicts that the growth rates and sSFRs increase similarly with redshift for all masses, consistent with the observations. However, we find that for all masses, the inferred observed growth rates increase more rapidly with redshift than the model predictions. We discuss several possible causes for this discrepancy, ranging from field-to-field variance, conversions to SFR, and shape of the initial mass function. We find that none of these can solve the discrepancy completely. We conclude that the models need to be adapted to produce the steep increase in growth rate between redshift z = 0 and z = 1.

  1. Ultra-High Field Template-Assisted Target Selection for Deep Brain Stimulation Surgery.

    PubMed

    Lau, Jonathan C; MacDougall, Keith W; Arango, Miguel F; Peters, Terry M; Parrent, Andrew G; Khan, Ali R

    2017-07-01

    Template and atlas guidance are fundamental aspects of stereotactic neurosurgery. The recent availability of ultra-high field (7 Tesla) magnetic resonance imaging has enabled in vivo visualization at the submillimeter scale. In this Doing More with Less article, we describe our experiences with integrating ultra-high field template data into the clinical workflow to assist with target selection in deep brain stimulation (DBS) surgical planning. The creation of a high-resolution 7T template is described, generated from group data acquired at our center. A computational workflow was developed for spatially aligning the 7T template with standard clinical data and furthermore, integrating the derived imaging volumes into the surgical planning workstation. We demonstrate that our methodology can be effective for assisting with target selection in 2 cases: unilateral internal pallidum DBS for painful dystonia and bilateral subthalamic nucleus DBS for Parkinson's disease. In this article, we have described a workflow for the integration of high-resolution in vivo ultra-high field templates into the surgical navigation system as a means to assist with DBS planning. The method does not require any additional cost or time to the patient. Future work will include prospectively evaluating different templates and their impact on target selection. Crown Copyright © 2017. Published by Elsevier Inc. All rights reserved.

  2. Hubble Space Telescope Medium Deep Survey. 2: Deconvolution of Wide Field Camera field galaxy images in the 13 hour + 43 deg field

    NASA Technical Reports Server (NTRS)

    Windhorst, R. A.; Schmidtke, P. C.; Pascarelle, S. M.; Gordon, J. M.; Griffiths, R. E.; Ratnatunga, K. U.; Neuschaefer, L. W.; Ellis, R. S.; Gilmore, G.; Glazebrook, K.

    1994-01-01

    We present isophotal profiles of six faint field galaxies from some of the first deep images taken for the Hubble Space Telescope (HST) Medium Deep Survey (MDS). These have redshifts in the range z = 0.126 to 0.402. The images were taken with the Wide Field Camera (WFC) in `parallel mode' and deconvolved with the Lucy method using as the point-spread function nearby stars in the image stack. The WFC deconvolutions have a dynamic range of 16 to 20 dB (4 to 5 mag) and an effective resolution approximately less than 0.2 sec (FWHM). The multiorbit HST images allow us to trace the morphology, light profiles, and color gradients of faint field galaxies down to V approximately equal to 22 to 23 mag at sub-kpc resolution, since the redshift range covered is z = 0.1 to 0.4. The goals of the MDS are to study the sub-kpc scale morphology, light profiles, and color gradients for a large samole of faint field galaxies down to V approximately equal to 23 mag, and to trace the fraction of early to late-type galaxies as function of cosmic time. In this paper we study the brighter MDS galaxies in the 13 hour + 43 deg MDS field in detail, and investigate to what extent model fits with pure exponential disks or a(exp 1/4) bulges are justified at V approximately less than 22 mag. Four of the six field galaxies have light profiles that indicate (small) inner bulges following r(exp 1/4) laws down to 0.2 sec resolution, plus a dominant surrounding exponential disk with little or no color gradients. Two occur in a group at z = 0.401, two are barred spiral galaxies at z = 0.179 and z = 0.302, and two are rather subluminous (and edge-on) disk galaxies at z = 0.126 and z = 0.179. Our deep MDS images can detect galaxies down to V, I approximately less than 25 to 26 mag, and demonstrate the impressive potential of HST--even with its pre-refurbished optics--to resolve morphological details in galaxies at cosmologically significant distances (v approximately less than 23 mag). Since the median

  3. Decay of deep water convection in CMIP5 GCMs in the North Atlantic and Southern Ocean in the 21st century

    NASA Astrophysics Data System (ADS)

    Molodtsov, S.; Anis, A.; Marinov, I.; Cabre, A.

    2016-12-01

    Contemporary changes in the climate system due to anthropogenic activity have already resulted in unprecedented melting rates of the polar ice caps. This in turn may have a significant impact on the thermohaline circulation in the future. The freshening of the surface waters increases stable stratification in regions of deep water formation, eventually triggering a weakening and, ultimately, may bring to a cessation of deep convection in these regions. Here we present comparatively an analysis of the response of deep convective processes in the North Atlantic (NA) and Southern Ocean (SO) to anthropogenic forcing using output from the latest generation of Earth System Models (ESM), part of the CMIP5 intercomparison. Our findings indicate an attenuation of deep convection by the end of the 21st century from ESM simulations under representative concentration pathways (RCP) 8.5 scenario when compared to the years under historical scenario in both NA and SO. The average depth of the mixed layer in the regions studied during March/September, the months with maximum mixed layer depths in the NA/SO, respectively, was found to decrease dramatically by the end of the 21st century. Furthermore, the increase in stratification and decrease in mixed layer depths, resulting in the decay of deep convection, leads to accumulation of excess heat, previously released during the convection events, in the ocean interior in both regions.

  4. Confirmed field hybridization of native and introduced Phragmites australis (Poaceae) in North America.

    PubMed

    Saltonstall, Kristin; Castillo, Hilda E; Blossey, Bernd

    2014-01-01

    Intraspecific hybridization between native and introduced lineages of a species can increase invasiveness and may lead to the decline of native lineages. The introduction of Eurasian Phragmites australis has caused profound changes to wetland habitats across North America, yet evidence for hybridization between native and introduced Phragmites australis in North America is lacking and has puzzled researchers for over a decade. Here we present the first confirmed field hybridization event between the two lineages. Hybrid plants were initially recognized during field surveys by their intermediate morphology and distinct herbivore community. We verified hybrid status using chloroplast DNA haplotypes and microsatellite markers. Confirmed hybrid stems were restricted to one site and displayed morphological characteristics of both native and introduced P. australis. Based on their microsatellite profiles, all samples likely represent a single clone of a first generation hybrid. Sequencing of cpDNA indicates that the maternal parent is from the introduced lineage. Identification of hybrid P. australis in the field is complex and requires multiple characters. All suspected hybrids should be verified using genetic techniques. Preventing the spread of introduced genes and genotypes through North America will require recognition and rapid management response to hybrid plants.

  5. Transport of the North Atlantic Deep Western Boundary Current about 39°N, 70°W: 2004-2008

    NASA Astrophysics Data System (ADS)

    Toole, J. M.; Curry, R. G.; Joyce, T. M.; McCartney, M.; Peña-Molino, B.

    2011-09-01

    Begun in spring 2004, a sustained measurement program - Line W - is returning high-resolution observations of the North Atlantic's Deep Western Boundary Current (DWBC) southeast of New England. The study focuses on the cold limb of the Atlantic Meridional Overturning Circulation near the boundary between the subpolar and subtropical gyres. The field study consists of a 6-element, continental-slope-spanning moored array on a line underlying an altimeter satellite ground track, and periodic reoccupations of a full-depth hydrographic section along the line extending from the continental shelf towards Bermuda. Here, data from the first 4 years of the array (May 10, 2004-April 9, 2008) are analyzed along with 9 realizations of the section. The array, a mix of Moored Profiler and discrete, fixed-depth instrument moorings, returned temperature, salinity and horizontal velocity data with various temporal and depth resolutions. After averaging to filter inertial, tidal and other high-frequency motions, the combined moored data set was binned to the lowest common temporal resolution of 5-days (the nominal burst sample interval of the Moored Profilers) and interpolated to 2-dbar vertical resolution. Temperature, salinity, dissolved oxygen, tracer chemical concentrations and direct velocity data were acquired on the hydrographic cruises. The present work focuses on the 4-year-mean and time-varying meridional transport in 4 layers bounded by neutral density surfaces: Upper and Classical Labrador Sea Waters, Iceland-Scotland Overflow Waters and Denmark Strait Overflow Waters. The 5-d, 4-layer-summed meridional transport estimates range between -3.5 and -79.9 Sv with a record mean average transport of -25.1 Sv and standard deviation of 12.5 Sv. Bias adjustment to account for the finite width of the moored array increases the 4-layer mean transport estimate to -28.7 Sv. At time scales longer than about 1 month, the variations in equatorward DWBC transport appear correlated with

  6. MID-INFRARED VARIABILITY FROM THE SPITZER DEEP WIDE-FIELD SURVEY

    SciTech Connect

    Kozlowski, Szymon; Kochanek, Christopher S.; Assef, Roberto J.; Stern, Daniel; Eisenhardt, P. R.; Gorjian, V.; Griffith, R.; Ashby, Matthew L. N.; Brodwin, M.; Bock, J. J.; Borys, C.; Brand, K.; Grogin, N.; Brown, M. J. I.; Cool, R.; Cooray, A.; Croft, S.; Dey, Arjun; Gonzalez, A.; Ivison, R.

    2010-06-10

    We use the multi-epoch, mid-infrared Spitzer Deep Wide-Field Survey to investigate the variability of objects in 8.1 deg{sup 2} of the NOAO Deep Wide Field Survey Booetes field. We perform a Difference Image Analysis of the four available epochs between 2004 and 2008, focusing on the deeper 3.6 and 4.5 {mu}m bands. Out of 474, 179 analyzed sources, 1.1% meet our standard variability selection criteria that the two light curves are strongly correlated (r>0.8) and that their joint variance ({sigma}{sub 12}) exceeds that for all sources with the same magnitude by 2{sigma}. We then examine the mid-IR colors of the variable sources and match them with X-ray sources from the XBooetes survey, radio catalogs, 24 {mu}m selected active galactic nucleus (AGN) candidates, and spectroscopically identified AGNs from the AGN and Galaxy Evolution Survey (AGES). Based on their mid-IR colors, most of the variable sources are AGNs (76%), with smaller contributions from stars (11%), galaxies (6%), and unclassified objects, although most of the stellar, galaxy, and unclassified sources are false positives. For our standard selection criteria, 11%-12% of the mid-IR counterparts to X-ray sources, 24 {mu}m AGN candidates, and spectroscopically identified AGNs show variability. The exact fractions depend on both the search depth and the selection criteria. For example, 12% of the 1131 known z>1 AGNs in the field and 14%-17% of the known AGNs with well-measured fluxes in all four Infrared Array Camera bands meet our standard selection criteria. The mid-IR AGN variability can be well described by a single power-law structure function with an index of {gamma} {approx} 0.5 at both 3.6 and 4.5 {mu}m, and an amplitude of S {sub 0} {approx_equal} 0.1 mag on rest-frame timescales of 2 yr. The variability amplitude is higher for shorter rest-frame wavelengths and lower luminosities.

  7. Mid-infrared Variability from the Spitzer Deep Wide-field Survey

    NASA Astrophysics Data System (ADS)

    Kozłowski, Szymon; Kochanek, Christopher S.; Stern, Daniel; Ashby, Matthew L. N.; Assef, Roberto J.; Bock, J. J.; Borys, C.; Brand, K.; Brodwin, M.; Brown, M. J. I.; Cool, R.; Cooray, A.; Croft, S.; Dey, Arjun; Eisenhardt, P. R.; Gonzalez, A.; Gorjian, V.; Griffith, R.; Grogin, N.; Ivison, R.; Jacob, J.; Jannuzi, B. T.; Mainzer, A.; Moustakas, L.; Röttgering, H.; Seymour, N.; Smith, H. A.; Stanford, S. A.; Stauffer, J. R.; Sullivan, I. S.; van Breugel, W.; Willner, S. P.; Wright, E. L.

    2010-06-01

    We use the multi-epoch, mid-infrared Spitzer Deep Wide-Field Survey to investigate the variability of objects in 8.1 deg2 of the NOAO Deep Wide Field Survey Boötes field. We perform a Difference Image Analysis of the four available epochs between 2004 and 2008, focusing on the deeper 3.6 and 4.5 μm bands. Out of 474, 179 analyzed sources, 1.1% meet our standard variability selection criteria that the two light curves are strongly correlated (r>0.8) and that their joint variance (σ12) exceeds that for all sources with the same magnitude by 2σ. We then examine the mid-IR colors of the variable sources and match them with X-ray sources from the XBoötes survey, radio catalogs, 24 μm selected active galactic nucleus (AGN) candidates, and spectroscopically identified AGNs from the AGN and Galaxy Evolution Survey (AGES). Based on their mid-IR colors, most of the variable sources are AGNs (76%), with smaller contributions from stars (11%), galaxies (6%), and unclassified objects, although most of the stellar, galaxy, and unclassified sources are false positives. For our standard selection criteria, 11%-12% of the mid-IR counterparts to X-ray sources, 24 μm AGN candidates, and spectroscopically identified AGNs show variability. The exact fractions depend on both the search depth and the selection criteria. For example, 12% of the 1131 known z>1 AGNs in the field and 14%-17% of the known AGNs with well-measured fluxes in all four Infrared Array Camera bands meet our standard selection criteria. The mid-IR AGN variability can be well described by a single power-law structure function with an index of γ ≈ 0.5 at both 3.6 and 4.5 μm, and an amplitude of S 0 ~= 0.1 mag on rest-frame timescales of 2 yr. The variability amplitude is higher for shorter rest-frame wavelengths and lower luminosities.

  8. An integrated deep electrical resistivity model of the Larderello geothermal field (Italy)

    NASA Astrophysics Data System (ADS)

    Rizzo, Enzo; Capozzoli, Luigi; De martino, Gregory; Godio, Alberto; Manzella, Adele; Perciante, Felice; Santilano, Alessandro

    2017-04-01

    A new deep electrical resistivity acquisition was carried out in Larderello geothermal area (Tuscania Region, Italy) by 3D Deep Electrical Resistivity Tomography (3D-DERT) and Magnetotelluric (M) acquisition. The investigated area is located close the Venelle2 well in the southern part of Larderello site, where there is the oldest field in the world under exploitation for power production (actual installed capacity is about 795 MWe). A vapour-dominated system is exploited to depth over 3500 m, with temperatures exceeding 350°C, from two different reservoirs. The Larderello area has been investigated by many geological and geophysical data of previous exploration projects but nowadays several critical issues on deep features of the field are still matter of debate, e.g., permeability distribution in the hydrothermal reservoir and the presence of fluids at supercritical condition at depth. The 3D-DERT system was designed by Surface-Surface and Surface-Hole electrode distributions in the area around Venelle2 well covering an area around 16km2. The well (kindly provided by Enel GP) was accessible down to 1.6 km with a temperature up to 250°C and a metallic casing down to 1 km. The in-hole thermal cable is characterized by n.12 flexible metallic electrodes with an electrodes space of 50m covering the open-hole portion (1050m-1600m). The surface electrodes are located around the Venelle2 hole on n.23 different positions connected to automatic dataloger to acquire the drop of potential and to transmitter device to inject the current (5-10A). The crucial task was the data processing, considering the large distance between the Tx and Rx systems that strongly reduces the signal to-noise ratio. To overcome this drawback, for each quadripole position the corresponding voltage signal was filtered, stored and processed with advanced statistical packages. The new 22 station were installed in the studied area and the data were carried out taking in account a permanent remote

  9. Low-flow characteristics and profiles for the Deep River in the Cape Fear River basin, North Carolina

    USGS Publications Warehouse

    Weaver, J.C.

    1997-01-01

    Drainage area and low-flow discharge profiles are presented for the Deep River. The drainage-area profile shows downstream increases in basin size. At the mouth, the drainage area for the Deep River is 1,441 square miles. Low-flow discharge profiles for the Deep River include 7Q10, 30Q2, W7Q10, and 7Q2 discharges in a continuous profile with contributions from major tributaries included.

  10. A subsurface study of the North Frisco City field, Monroe County, Alabama

    SciTech Connect

    Stephanson, M.A.; Cox, J.G.; Harmount, M.; Bruno, L. )

    1993-09-01

    The 1991 discovery of the North Frisco City field has led to a resurgence of industry activity in the updip Jurassic trend of Monroe County, Alabama. Six wells in the field are presently delivering 6,000 BOPD and 5 MMJCFGP out of the Frisco City Sand Member of the lower Haynesville Formation. The North Frisco City field is a combination structural-stratigraphic trap associated with Paleozoic basement topography. A geological and geophysical exploration model for Haynesville production in Alabama was developed from existing subsurface and seismic control. The model predicted hydrocarbons generated from Smackover carbonates migrated through an incompetent or absent Buckner Anhydrite seal into the overlying Frisco City Sand. The Frisco City Sand is vertically sealed by overlying Haynesville shales and anhydrites. The sedimentary strata of the Frisco City Sand Member at North Frisco City field are interpreted to have accumulated as fluvial deposits. The predominant lithology is a coarse- to fine-grained sandstone deposited in a sandy braided-stream environment. The sandy braided-stream deposits occur in stacked fining-upward sequences and have excellent reservoir character. Some of these sequences are very gravel rich and may have accumulated in braided streams associated with alluvial fans. A nonconformity exists totally between the Jurassic sediments and the underlying crystalline metamorphic basement rock. A three-dimensional (3-D) seismic survey was acquired after the discovery well was drilled. The survey covered 8 mi[sup 2] of surface area with a bin size of 82.5 ft. This provided excellent structural control across the prospective area and resulted in better drilling decisions. Also, once 3-D acquisition was complete, the field was developed at an accelerated pace, which has had a positive impact on cash flow and field economics.

  11. Neodymium Isotopic Composition of Deep-sea Corals from Rockall Bank, Implications for Variations of Eastern North Atlantic Intermediate Water Hydrology During the Past 10,000 years

    NASA Astrophysics Data System (ADS)

    Colin, C.; Frank, N.; Blamart, D.

    2006-12-01

    The main proxies for reconstructing past circulation of the ocean are stable C isotope ratios (d13C) of dissolved inorganic carbon (DIC) and Cd/Ca ratios as recorded by benthic foraminifers. Both proxies vary as a function of nutrient content of ambient deep water and it is difficult to make quantitative estimates of mixing between water masses. In contrast to those classical ocean tracers, Nd-isotope ratios have been shown to be a promising new proxy to trace the water mass provenance and mixing. It has the advantage to be independent of fractionation induced by biological processes in the water column. Neodymium isotope ratios have been analyzed at high resolution on deep-sea corals (Lophelia pertusa) from core MD01-2454 (55°31.17N - 15°39.08W, water depth : 747 m) located on the Rockall bank in order to trace the eastern North Atlantic intermediate water hydrology during Holocene. To obtain this record rigorous cleaning techniques have been investigated to remove the authigenic fraction of Nd that can be precipitated on deep-water corals by iron-manganese oxide precipitation (Frank, 1998). In addition, a Nd-Oxyde technique for thermal ionization mass spectrometry has been used to precisely determine eNd of corals, which is mandatory as Nd is incorporated in the coralline aragonite solely in small traces (~5-10 ng/g). Deep-sea corals have been dated precisely by means of U-series dating. Core MD01-2454 provides a sedimentary record extending down to the last 10,000 years. eNd(0) values of the deep-sea corals from core MD01-2454G exhibit a range from -12 to -15.5 indicating a significant changes in water mass composition on Rockall Bank over the past 10,000 years. Moreover, several modern deep-water corals, collected from Gibraltar straight to the Norwegian Sea, have been analyzed and confirm that the Nd isotopic signature of deep-sea corals reflect those of the different modern intermediate water masses of the eastern North Atlantic (LSW, MOW, NAC, etc...). For

  12. Physical oceanographic field program offshore North Carolina. Second annual progress report

    SciTech Connect

    Not Avail