59 research outputs found

    Site 1216

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    Site 1216 (21°27.16´N, 139°28.79´W; 5152 meters below sea level [mbsl]; Fig. F1) is situated in abyssal hill topography south of the Molokai Fracture Zone and two small associated unnamed parasitic fracture zones (Fig. F2). Based on magnetic lineations, Site 1216 appears to be situated on normal ocean crust formed during the C25r magnetic anomaly (~57 Ma; Atwater and Severinghaus, 1989). Site 1216 was chosen for drilling because it is near the thickest section of lower Eocene sediments along the 56-Ma transect, which was based upon the seismic stratigraphy of seismic reflection data acquired on site survey cruise EW9709 during transits between the proposed drill sites (Lyle et al., this volume; Moore et al., 2002). The Cenozoic history of sedimentation in this region was poorly constrained prior to Leg 199, being largely based on two Deep Sea Drilling Project (DSDP) drill sites (40 and 41) and piston core data (EW9709-3PC) from ~1.5° in latitude to the south. Based on data from these drill sites, we expected the sedimentary sequence at Site 1216 to comprise red clays (a mixture of wind-blown dust and authigenic precipitates) overlying a biogenic sediment section composed of an upper middle Eocene radiolarian ooze and lower carbonate ooze deposited when the site was near the ridge crest in the late Paleocene and early Eocene. The broad paleoceanographic objectives of drilling the sedimentary sequence anticipated at Site 1216 are as follows: (1) to help define the shift in the Intertropical Convergence Zone through the Paleogene by following the change in eolian-dust composition and flux through time (red clays) and (2) to help define the latitudinal extent, composition, and mass accumulation of plankton communities in the north equatorial Pacific region thereby constraining ocean circulation patterns and the extent of the equatorial high-productivity belt in the Eocene ocean. Results from Site 1216 will also provide important information to test whether there was significant motion of the Hawaiian hotspot with respect to the Earth's spin axis during the early Cenozoic. At 56 Ma, the backtracked location of Site 1216 based upon a hotspot reference frame (Gripp and Gordon, 1990, for 0- to 5-Ma Pacific hotspot rotation pole; Engebretson et al., 1985, for older poles) is about 9°N, 108°W. If significant hotspot motion or true polar wander occurred since 57 Ma (Petronotis et al., 1994), this drill site could have been much nearer to the equator

    Site 1220

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    Site 1220 (10°10.600´N, 142°45.503´W; 5218 meters below sea level (mbsl); Fig. F1) forms a southerly component of the 56-Ma transect drilled during Leg 199. It is situated about midway between the Clipperton and Clarion Fracture Zones in typical abyssal hill topography. On the basis of regional magnetic anomalies, we anticipated basement age at Site 1220 to be equivalent to Chron C25n (~56 Ma; Cande et al., 1989), slightly older than at Site 1219. At the outset of drilling at Site 1220, our estimate for total sediment depth was ~225 meters below seafloor (mbsf) (Fig. F2). Based upon a fixed hotspot model (Gripp and Gordon, 1990, for 0- to 5-Ma Pacific hotspot rotation pole; Engebretson et al., 1985, for older poles), Site 1220 should have been located ~3° south of the equator at 56 Ma and in an equatorial position at 40 Ma. Thus, Site 1220 should have been situated underneath the South Equatorial Current in the early Eocene. A nearby piston core (EW9709-13PC) taken during the site survey cruise recovered >16 m of red clay, with the base of the core dated as middle-early Miocene on the basis of radiolarian biostratigraphy (Lyle, 2000). Site 1220 will be used to study equatorial ocean circulation from the late Paleocene through the late Eocene during the early Cenozoic thermal maximum. Sediment records from this site will help to define the calcite compensation depth (CCD) and lysocline during the Paleocene-Eocene and Eocene-Oligocene transitions. In this and other respects, Site 1220 will act as an interesting analog to Site 1218. Both sites are thought to have been located on the equator at ~40 Ma, but the older crustal age anticipated at Site 1220 dictates a greater paleowater depth than for contemporaneous sediments accumulating at Site 1218

    Site 1222

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    Site 1222 (13°48.98´N, 143°53.35´W; 4989 meters below sea level [mbsl]; Fig. F1) forms a south-central component of the 56-Ma transect drilled during Leg 199 and is situated ~2° south of the Clarion Fracture Zone in typical abyssal hill topography. On the basis of regional magnetic anomalies, we anticipated basement age at Site 1222 to be equivalent to Chron C25r or Chron C25n (~56-57 Ma) (Cande et al., 1989), which is slightly older than at Site 1219. At the outset of drilling at Site 1222, our estimate for total sediment thickness was ~115 m (Fig. F2). Based upon a fixed hotspot model (Gripp and Gordon, 1990, for 0- to 5-Ma Pacific hotspot rotation pole; Engebretson et al., 1985, for older poles) Site 1222 should have been located ~1° north of the equator at 56 Ma and ~4°N at 40 Ma. A nearby gravity core (EW9709-17GC), taken during the site survey cruise, recovered >5 m of red clay with a late-middle Miocene age on the basis of radiolarian biostratigraphy (Lyle, 2000). Deep Sea Drilling Project (DSDP) Site 42 located ~4° east of Site 1222, was not drilled to basement but contains a thin sedimentary section (~100 m thick) of upper Oligocene nannofossil ooze through middle Eocene radiolarian nannofossil ooze. In turn, DSDP Site 162 lies ~1° north of DSDP Site 42 and is situated on young crust (49 Ma) that contains ~150 m of clayey radiolarian and nannofossil oozes of early Oligocene-middle Eocene age. Site 1222 will be used to study the position of the Intertropical Convergence Zone in the late Eocene and Oligocene, to sample late Paleocene and early Eocene sediments in the central tropical Pacific Ocean, and to help determine whether or not there has been significant southward movement of the hotspots with respect to the spin axis prior to 40 Ma

    Site 1217

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    Site 1217 (16°52.02´N, 138°06.00´W; 5342 meters below sea level [mbsl]; Fig. F1) is one of seven sites drilled to target upper Paleocene crust along a latitudinal transect during Leg 199 and will be used to investigate paleoceanographic processes in the northern tropical early Eocene Pacific Ocean. Site 1217 is situated ~1° north of the Clarion Fracture Zone on abyssal hill topography typical of the central Pacific. Based on magnetic lineations, basement age at Site 1217 should be in magnetic Anomaly C25r or ~57 Ma (Cande et al., 1989; timescale of Cande and Kent, 1995). The Cenozoic history of sedimentation in this region was poorly constrained prior to Leg 199 drilling because the nearest drill site (Deep Sea Drilling Project [DSDP] Site 162) is situated ~300 km south and west on 48-Ma crust. Based on data from this early rotary-cored hole, magnetic anomaly maps, a shallow-penetration piston core near Site 1217 (EW9709-4PC), and seismic profiling (Fig. F2), we expected the sedimentary sequence at Site 1217 to comprise a relatively thick (25 to 35 m thick) section of red clays overlying a radiolarian ooze and a basal carbonate section with possible chert near basement (estimated total depth ~125-150 meters below seafloor [mbsf]) deposited when the site was near the ridge crest in the late Paleocene and early Eocene. Site 1217 was chosen because it is anticipated to have been located just outside of the equatorial region at 56 Ma, ~5°N, 106°W based upon a fixed hotspot model (Gripp and Gordon, 1990, for 0- to 5-Ma Pacific hotspot rotation pole; Engebretson et al., 1985, for older poles). On the same basis at 40 Ma, the site was located at ~8°N, 111°W. Thus, Site 1217 should help define the paleoceanography of the northern tropical Pacific, in particular locating the ancient North Equatorial Countercurrent (NECC) region. General circulation-model experiments for the early Eocene (see Huber, this volume) suggest that the NECC was a well-developed current during this time period. Other paleoceanographic and paleoclimatic objectives of drilling the sedimentary sequence anticipated at Site 1217 are as follows: (1) to help define the shift in the Intertropical Convergence Zone through the Paleogene by following the change in eolian dust composition and flux through time (red clays); (2) to help constrain the middle-late Eocene calcite compensation depth (CCD); and (3) to sample the Paleocene/Eocene (P/E) boundary, one of the most climatologically critical intervals of Cenozoic time. Recovery of deep-sea sediments from this time interval during Leg 199 is a high priority because the P/E boundary has never before been sampled in the central tropical Pacific Ocean. Results from Site 1217 will also provide important information to test whether there was significant motion of the Hawaiian hotspot, with respect to the Earth's spin axis during the early Cenozoic. At 56 Ma, the backtracked location based upon a hotspot reference frame is ~5°N, 106°W, and at 40 Ma is ~8°N, 106°W. If significant hotspot motion or true polar wander occurred since 57 Ma (Petronotis et al., 1994), this drill site could have been much nearer to the equator

    Geochemical analysis of bulk marine sediment by Inductively Coupled Plasma–Atomic Emission Spectroscopy on board the JOIDES Resolution

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    Geochemical analyses on board the JOIDES Resolution have been enhanced with the addition of a Jobin-Yvon Ultrace inductively coupled plasma-atomic emission spectrometer (ICP-AES) as an upgrade from the previous X-ray fluorescence facility. During Leg 199, we sought to both challenge and utilize the capabilities of the ICP-AES in order to provide an extensive bulk-sediment geochemical database during the cruise. These near real-time analyses were then used to help characterize the recovered sedimentary sequences, calculate mass accumulation rates of the different sedimentary components, and assist with cruise and postcruise sampling requests. The general procedures, sample preparation techniques, and basic protocol for ICP-AES analyses on board ship are outlined by Murray et al. (2000) in Ocean Drilling Program Tech Note, 29. We expand on those concepts and offer suggestions for ICP-AES methodology, calibration by standard reference materials, data reduction procedures, and challenges that are specific to the analysis of bulk-sediment samples. During Leg 199, we employed an extensive bulk-sediment analytical program of ~600 samples of varying lithologies, thereby providing several opportunities for refinement of techniques. We also discuss some difficulties and challenges that were faced and suggest how to alleviate such occurrences for sedimentary chemical analyses during future legs

    Using Core (mcd) to log (mbsf) depth miss-matches as a basis for interpreting core elastic rebound and re-calculating core physical properties. Results from ODP Leg 199 (abstract of paper presented at AGU Fall Meeting, San Francisco, 6-10 Dec 2002)

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    Leg 199 drilled a series of sites in the equatorial Pacific in order to investigate the paleoceanography of the Paleogene Pacific Ocean. The two deepest cored sites, (1218 and 1219) have provided continuous/near continuous spliced sedimentary sections and in situ wireline log data. Comparison of core to log data sets shows the familiar non-linear, increasing with depth, miss-match between the core (metres composite depth - mcd) and log (mbsf) depths and concomitant offset between core and log physical property data sets e.g. porosity, density, velocity. The depth miss-matches represent core expansion due to elastic rebound experienced by the sediments upon unloading i.e. removal of overburden stress, which is a function of the sediment void ratio and log of the effective in situ stress. The increasing depth offset observed between the 1218 core and log data is used to calculate an expansion index (Cr_{r}) for continuous discrete measurement intervals, down the core. The Cr_{r} values are used to re-compress the core (mcd) depth scale and as expected provide a good match with the log (mbsf) depths. The Cr_{r} values are also used to correct the core index property data, to in situ values. The quality of the corrected core index property data is good when compared with the in situ measured log data. Cr_{r} values are dependent upon the sediment composition (especially the quantity of clay) and core light absorption spectroscopy (LAS) data collected on Leg 199, provides a continuous down-core record of sediment composition, in terms of the percent clay, carbonate and opal. A relationship between the Cr_{r} values and the sediment LAS composition is established and is then applied to the Site 1219 core LAS data, allowing appropriate Cr_{r} values to be assigned to continuous, discrete core intervals. These composition based Cr_{r} values are then used to re-calculate the core (mcd) depths and correct the index property data to in situ values. The quality of the depth and index property corrections are checked by comparison with the in situ measured log data, and provide encouraging results

    Validation of the use of Actigraph GT3X accelerometers to estimate energy expenditure in full time manual wheel chair users with Spinal Cord Injury

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    Study design: Cross-sectional validation study. Objectives: The goals of this study were to validate the use of accelerometers by means of multiple linear models (MLMs) to estimate the O2 consumption (VO2) in paraplegic persons and to determine the best placement for accelerometers on the human body. Setting: Non-hospitalized paraplegics’ community. Methods: Twenty participants (age=40.03 years, weight=75.8 kg and height=1.76 m) completed sedentary, propulsion and housework activities for 10 min each. A portable gas analyzer was used to record VO2. Additionally, four accelerometers (placed on the non-dominant chest, non-dominant waist and both wrists) were used to collect second-by-second acceleration signals. Minute-by-minute VO2 (ml kg−1 min−1) collected from minutes 4 to 7 was used as the dependent variable. Thirty-six features extracted from the acceleration signals were used as independent variables. These variables were, for each axis including the resultant vector, the percentiles 10th, 25th, 50th, 75th and 90th; the autocorrelation with lag of 1 s and three variables extracted from wavelet analysis. The independent variables that were determined to be statistically significant using the forward stepwise method were subsequently analyzed using MLMs. Results: The model obtained for the non-dominant wrist was the most accurate (VO2=4.0558−0.0318Y25+0.0107Y90+0.0051YND2−0.0061ZND2+0.0357VR50) with an r-value of 0.86 and a root mean square error of 2.23 ml kg−1 min−1. Conclusions: The use of MLMs is appropriate to estimate VO2 by accelerometer data in paraplegic persons. The model obtained to the non-dominant wrist accelerometer (best placement) data improves the previous models for this population.LM Garcia-Raffi and EA Sanchez-Perez gratefully acknowledge the support of the Ministerio de Economia y Competitividad under project #MTM2012-36740-c02-02. X Garcia-Masso is a Vali + D researcher in training with support from the Generalitat Valenciana.Garcia Masso, X.; Serra Añó, P.; García Raffi, LM.; Sánchez Pérez, EA.; Lopez Pascual, J.; González, L. (2013). Validation of the use of Actigraph GT3X accelerometers to estimate energy expenditure in full time manual wheel chair users with Spinal Cord Injury. Spinal Cord. 51(12):898-903. https://doi.org/10.1038/sc.2013.85S8989035112Van den Berg-Emons RJ, Bussmann JB, Haisma JA, Sluis TA, van der Woude LH, Bergen MP et al. A prospective study on physical activity levels after spinal cord injury during inpatient rehabilitation and the year after discharge. Arch Phys Med Rehabil 2008; 89: 2094–2101.Jacobs PL, Nash MS . Exercise recommendations for individuals with spinal cord injury. Sports Med 2004; 34: 727–751.Erikssen G . Physical fitness and changes in mortality: the survival of the fittest. Sports Med 2001; 31: 571–576.Warburton DER, Nicol CW, Bredin SSD . 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    Evidence of early bottom water current flow after the Messinian Salinity Crisis in the Gulf of Cadiz

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    Highlights • Stratigraphic framework over the Miocene-Pliocene boundary at IODP Site U1387. • Abrupt sedimentary changes over the Miocene-Pliocene boundary. • Clear hints for onset of Mediterranean Outflow after the Messinian Salinity Crisis. • Evidence of bottom water currents in contouritic sedimentation and elevated Zr/Al. • Quiet, hemipelagic sediment deposition during the Messinian in the Gulf of Cadiz. Abstract Integrated Ocean Drilling Program (IODP) Expedition 339 cored multiple sites in the Gulf of Cadiz in order to study contourite deposition resulting from Mediterranean Outflow water (MOW). One hole, U1387C, was cored to a depth of 865.6 meters below seafloor (mbsf) with the goal of recovering the Latest Miocene to Pliocene transition in order to evaluate the history of MOW immediately after the end of the Messinian Salinity Crisis. To understand this history, an accurate age model for the succession is needed, but is challenging to construct, because the Miocene-Pliocene boundary is not marked by a clear biostratigraphic event in the Atlantic and coring gaps occur within the recovered stratigraphic record. These limitations are overcome by combining a variety of chronostratigraphic datasets to construct an age-model that fits the currently available age indicators and demonstrates that coring in Hole U1387C did indeed recover the Miocene-Pliocene boundary at around 826 mbsf. This boundary is associated with a distinct and abrupt change in depositional environment. During the latest Messinian, hemipelagic sediments exhibiting precession-induced climate variability were deposited. These are overlain by Pliocene sediments deposited at a much higher sedimentation rate, with much higher and more variable XRF-scanning Zr/Al ratios than the underlying sediment, and that show evidence of winnowing, particle sorting and increasing grain size, which we interpret to be related to the increasing flow of MOW. Pliocene sedimentary cyclicity is clearly visible in both the benthic δ18O record and the Zr/Al data and is probably also precessionally controlled. Two contouritic bigradational sandy-beds are revealed above the third sedimentary cycle of the Pliocene. On the basis of these results, we conclude that sedimentation associated with weak Mediterranean-Atlantic exchange, began in the Gulf of Cadiz virtually at or shortly after the Miocene-Pliocene boundary

    Update on prevention, diagnosis, and treatment of chronic hepatitis B: AASLD 2018 hepatitis B guidance

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142904/1/hep29800.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142904/2/hep29800_am.pd
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