460 research outputs found

    Anthropogenic lead isotopes in Antarctica

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    We report the first measurements of Pb isotopes in Antarctic snow, which show that even recent snow containing 2.3 pg/g is highly polluted with anthropogenic Pb. This follows from a comparison of isotope abundances of Pb in surface snow and terrestrial dust extracted from ancient Antarctic ice (Dome C, depth 308 m, approximate age 7,500 a BP), the latter being distinctly more radiogenic. This result is independent of geochemical arguments based on measurements of Al, Na and SO_4. South America is suggested as a likely source of this anthropogenic Pb. The presence of significantly less radiogenic Pb in the snow adjacent to two Antarctic base stations indicates that there is contamination from station emissions, although emission from Australia is an alternative explanation for a site 33 km from Dumont d'Urville

    Atypical propylthiouracil-induced ANCA-positive vasculitis: report of a case with unusual clinical and histopathologic findings

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    The side effects of propylthiouracil, including cytopenia and vasculitis, are well established.  We present an interesting case in which cytopenia and cutaneous vasculopathy occurred concomitantly in a critically ill patient.  The patient was initially treated for suspected infection until dermatologic and rheumatologic workup revealed ANCA-positivity and vasculopathy on histopathology, most consistent with an atypical presentation of ANCA-positive vasculitis.  Upon initiation of immunosuppressive therapy, the patient’s condition rapidly improved emphasizing the importance of early recognition of this condition

    Lead Isotopes and Selected Metals in Ice from Law Dome, Antarctica

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    The isotopic composition. of Pb and the concentrations of Pb, Ba and Bi were measured in selected ice-core samples from Law Dome, East Antarctica, to a depth of 1196 m. The range of concentrations found in decontaminated ice was 0.03-1.5 pg g-1 for Pb, 0.9-6.1 pg g-1 for Ba and 0.4-17 fg g-1 for Bi, excluding the deepest sample which contained ∼1 ppm of rock dust. The abundances of all four stable lead isotopes were measured and gave 206Pb/207Pb ratios ≤ ∼1.23. A value of 208Pb/207Pb = 2.78 was measured in the deepest sample and is consistent with reported Pb isotope ratios of Antarctic granulites. Although the element concentrations in some samples were lower than have been reported elsewhere, geochemical and isotopic evidence indicated that a number of samples were contaminated with Pb not present in the original ice. However, it appears that the technical skills now available are approaching the level where careful sample selection, decontamination and analysis can yield accurate results for the concentration and isotopic composition of Pb in Earth\u27s purest naturally occurring ice

    Finding bichromatic-bidirectional waves with ADVS

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    The aim of this study is to investigate Bichromatic-Bidirectional waves to characterize the subtractive wave-wave nonlinear interactions, using adaptive techniques rather than traditional spectral techniques. A physical model test in a 3D-wave basin was conducted and measurements were made with two arrays of ultrasonic sensors of free surface and one array of ADVs. The Hilbert-Huang transform, aided by the Multivariate Empirical Mode Decomposition, was applied to the orbital velocity data and the main characteristics of the infragravity wave (velocity amplitude, period and direction) were extracted with a good precision. © 2018 American Society of Civil Engineers (ASCE). All rights reserved

    HST Observations of Heavy Elements in Metal-Poor Galactic Halo Stars

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    We present new abundance determinations of neutron-capture elements Ge, Zr, Os, Ir, and Pt in a sample of 11 metal-poor (-3.1 <= [Fe/H] <= -1.6) Galactic halo giant stars, based on Hubble Space Telescope UV and Keck I optical high-resolution spectroscopy. The stellar sample is dominated by r-process-rich stars such as the well-studied CS 22892-052 and bd+173248, but also includes the r-process-poor, bright giant HD 122563. Our results demonstrate that abundances of the 3rd r-process peak elements Os, Ir and Pt in these metal-poor halo stars are very well-correlated among themselves, and with the abundances of the canonical r-process element Eu (determined in other studies), thus arguing for a common origin or site for r-process nucleosynthesis of heavier (Z>56) elements. However, the large (and correlated) scatters of [Eu,Os,Ir,Pt/Fe] suggests that the heaviest neutron-capture r-process elements are not formed in all supernovae. In contrast, the Ge abundances of all program stars track their Fe abundances, very well. An explosive process on iron-peak nuclei (e.g., the alpha-rich freeze-out in supernovae), rather than neutron capture, appears to have been the dominant synthesis mechanism for this element at low metallicities -- Ge abundances seem completely uncorrelated with Eu.Comment: 35 pages, 5 tables, 7 figures; To appear in the Astrophysical Journa

    The Dutch multicenter experience of the Endo-Sponge treatment for anastomotic leakage after colorectal surgery

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    Anastomotic leakage is a feared complication following colorectal surgery and is associated with early and long-term morbidity and mortality. The presacral cavity as the result of leakage can be treated with an endo-sponge (B-Braun Medical). The aim of this study was to assess the effectiveness of endo-sponge treatment of the presacral cavity as the result of anastomotic leakage in the Netherlands. Between July 2006 and April 2008, 16 patients (M/F = 9:7) with median age 64 years (range 19-78 years) who underwent surgery for rectal cancer (n = 13) or ulcerative colitis (n = 3) were treated with the endo-sponge treatment after anastomotic leakage. Of the 16 patients, eight patients started with the endo-sponge treatment within 6 weeks after the initial surgery. In these patients the endo-sponge was placed after a median of 24 days (range 13-39 days) following surgery. In the remaining eight patients the endo-sponge treatment was started later than 6 weeks after the initial surgery. In this group there was a median of 74 days (range 43-1,602 days) between surgery and the start of endo-sponge placement. There was closure in six out of eight patients (75%) in the group that started with the endo-sponge treatment within 6 weeks of surgery compared with three out of eight patients (38%) in the group that started later (p = 0.315). Closure was achieved in a median of 40 (range 28-90) days with a median number of 13 sponge replacements (range 8-17). Endo-sponge placement can be helpful in the treatment for anastomotic leakage after colorectal surgery and might prevent a chronic presacral sinus. However, it is not yet clear if this new treatment modality results in quicker healin

    Detection of the Natural Alpha Decay of Tungsten

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    The natural alpha decay of 180W has been unambiguously detected for the first time. The alpha peak is found in a (gamma,beta and neutron)-free background spectrum. This has been achieved by the simultaneous measurement of phonon and light signals with the CRESST cryogenic detectors. A half-life of T1/2 = (1.8 +- 0.2) x 10^18 y and an energy release of Q = (2516.4 +- 1.1 (stat.) +- 1.2 (sys.)) keV have been measured. New limits are also set on the half-lives of the other naturally occurring tungsten isotopes.Comment: Submitted to Physical Review C Revised versio

    Hydrodynamics and seed dispersal in the lower Amazon.

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    The transport of seeds by water, i.e. hydrochory, is a key mechanism of long-distance dispersal constrained by the attributes of the seed and hydrodynamics. In the freshwater Amazon estuary, river hydrodynamics are influenced by seasonal changes in precipitation and tidal cycles. It is not known to what extent a hydrodynamic model may be able to predict seed dispersal. Here we parameterised a simulation model (SisBaHia) to estimate maximum seed dispersal distances per tidal cycle, which were then compared with data from in situ seed dispersal experiments. The study was conducted along a 27-km stretch of a tributary of the Amazon estuary, using the seeds of a widely distributed riparian tree?Carapa guianensis (Meliaceae). Based on the simulation model, maximum potential seed dispersal distance was higher in the rainy season (c. 8.7 km) when compared with the dry season (5.6 km), for one tidal cycle (12 hr). The seeds of C. guianensis were dispersed further during the ebb than flood tide during the rainy season, the period of seed dispersal. Average dispersal distances observed in seed dispersal experiments conducted during the rainy season, and those predicted by SisBaHia for the same period were within the same order of magnitude. The results of this study confirm that the period of higher precipitation provides favourable hydrological conditions for hydrochory in the Amazon river-estuary complex. The fact that the time taken for the tide to fall is longer in relation to the time taken for it to rise also favours the arrival of the seeds in the main channel of the Amazon, thereby increasing the probability of long-distance dispersal events

    Beta decay of 115-In to the first excited level of 115-Sn: Potential outcome for neutrino mass

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    Recent observation of beta decay of 115-In to the first excited level of 115-Sn with an extremely low Q_beta value (Q_beta ~ 1 keV) could be used to set a limit on neutrino mass. To give restriction potentially competitive with those extracted from experiments with 3-H (~2 eV) and 187-Re (~15 eV), atomic mass difference between 115-In and 115-Sn and energy of the first 115-Sn level should be remeasured with higher accuracy (possibly of the order of ~1 eV).Comment: 9 pages, 3 figures; talk at the NANP'05 Conferenc

    Cardiorespiratory comorbidity and postoperative complications following esophagectomy: a European multicenter cohort study

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    BACKGROUND: The impact of cardiorespiratory comorbidity on operative outcomes after esophagectomy remains controversial. This study investigated the effect of cardiorespiratory comorbidity on postoperative complications for patients treated for esophageal or gastroesophageal junction cancer. PATIENTS AND METHODS: A European multicenter cohort study from five high-volume esophageal cancer centers including patients treated between 2010 and 2017 was conducted. The effect of cardiorespiratory comorbidity and respiratory function upon postoperative outcomes was assessed. RESULTS: In total 1590 patients from five centers were included; 274 (17.2%) had respiratory comorbidity, and 468 (29.4%) had cardiac comorbidity. Respiratory comorbidity was associated with increased risk of overall postoperative complications, anastomotic leak, pulmonary complications, pneumonia, increased Clavien-Dindo score, and critical care and hospital length of stay. After neoadjuvant chemoradiotherapy, respiratory comorbidity was associated with increased risk of anastomotic leak [odds ratio (OR) 1.83, 95% confidence interval (CI) 1.11-3.04], pneumonia (OR 1.65, 95% CI 1.10-2.47), and any pulmonary complication (OR 1.52, 95% CI 1.04-2.22), an effect which was not observed following neoadjuvant chemotherapy or surgery alone. Cardiac comorbidity was associated with increased risk of cardiovascular and pulmonary complications, respiratory failure, and Clavien-Dindo score ≥ IIIa. Among all patients, forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ratio > 70% was associated with reduced risk of overall postoperative complications, cardiovascular complications, atrial fibrillation, pulmonary complications, and pneumonia. CONCLUSIONS: The results of this study suggest that cardiorespiratory comorbidity and impaired pulmonary function are associated with increased risk of postoperative complications after esophagectomy performed in high-volume European centers. Given the observed interaction with neoadjuvant approach, these data indicate a potentially modifiable index of perioperative risk
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