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Stello, D.,Bruntt, H.,Kjeldsen, H.,Bedding, T. R.,Arentoft, T.,Gilliland, R. L.,Nuspl, J.,Kim, S.-L.,Kang, Y. B.,Koo, J.-R.,Lee, J.-A.,Sterken, C.,Lee, C.-U.,Jensen, H. R.,Jacob, A. P.,Szabó,, R Blackwell Publishing Ltd 2007 Monthly notices of the Royal Astronomical Society Vol.377 No.2
<P>ABSTRACT</P><P>Measuring solar-like oscillations in an ensemble of stars in a cluster, holds promise for testing stellar structure and evolution more stringently than just fitting parameters to single field stars. The most-ambitious attempt to pursue these prospects was by Gilliland et al. who targeted 11 turn-off stars in the open cluster M67 (NGC 2682), but the oscillation amplitudes were too small (<20 μmag) to obtain unambiguous detections. Like Gilliland et al. we also aim at detecting solar-like oscillations in M67, but we target red giant stars with expected amplitudes in the range 50–500 μmag and periods of 1 to 8 h. We analyse our recently published photometry measurements, obtained during a six-week multisite campaign using nine telescopes around the world. The observations are compared with simulations and with estimated properties of the stellar oscillations. Noise levels in the Fourier spectra as low as 27 μmag are obtained for single sites, while the combined data reach 19 μmag, making this the best photometric time series of an ensemble of red giant stars. These data enable us to make the first test of the scaling relations (used to estimate frequency and amplitude) with an homogeneous ensemble of stars. The detected excess power is consistent with the expected signal from stellar oscillations, both in terms of its frequency range and amplitude. However, our results are limited by apparent high levels of non-white noise, which cannot be clearly separated from the stellar signal.</P>
Multisite campaign on the open cluster M67 – III. δ Scuti pulsations in the blue stragglers
Bruntt, H.,Stello, D.,Suá,rez, J. C.,Arentoft, T.,Bedding, T. R.,Bouzid, M. Y.,Csubry, Z.,Dall, T. H.,Dind, Z. E.,Frandsen, S.,Gilliland, R. L.,Jacob, A. P.,Jensen, H. R.,Kang, Y. B.,Kim, S.-L. Blackwell Publishing Ltd 2007 MONTHLY NOTICES- ROYAL ASTRONOMICAL SOCIETY Vol.378 No.4
<P>ABSTRACT</P><P>We have made an asteroseismic analysis of the variable blue stragglers in the open cluster M67. The data set consists of photometric time-series from eight sites using nine 0.6–2.1 m telescopes with a time-baseline of 43 d. In two stars, EW Cnc and EX Cnc, we detect the highest number of frequencies (41 and 26) detected in δ Scuti stars belonging to a stellar cluster, and EW Cnc has the second highest number of frequencies detected in any δ Scuti star. We have computed a grid of pulsation models that take the effects of rotation into account. The distribution of observed and theoretical frequencies shows that in a wide frequency range a significant fraction of the radial and non-radial low-degree modes are excited to detectable amplitudes. Despite the large number of observed frequencies we cannot constrain the fundamental parameters of the stars. To make progress we need to identify the degrees of some of the modes from either multicolour photometry or spectroscopy.</P>
Jake S. Jacob,Michelle E. Lee,Erin Y. Chew,Aaron P. Thrift,Robert J. Sealock 대한소화기내시경학회 2021 Clinical Endoscopy Vol.54 No.2
Background/Aims: The American Society for Gastrointestinal Endoscopy (ASGE) revised its guidelines for risk stratification ofpatients with suspected choledocholithiasis. This study aimed to assess the diagnostic performance of the revision and to compare itto the previous guidelines. Methods: We conducted a retrospective cohort study of 267 patients with suspected choledocholithiasis. We identified high-riskpatients according to the original and revised guidelines and examined the diagnostic accuracy of both guidelines. We measured theassociation between individual criteria and choledocholithiasis. Results: Under the original guidelines, 165 (62%) patients met the criteria for high risk, of whom 79% had confirmedcholedocholithiasis. The categorization had a sensitivity and specificity of 68% and 55%, respectively, for the detectionof choledocholithiasis. Under the revised guidelines, 86 (32%) patients met the criteria for high risk, of whom 83% hadcholedocholithiasis. The revised categorization had a lower sensitivity and higher specificity of 37% and 80%, respectively. Thepositive predictive value of the high-risk categorization increased with the revision, reflecting a potential decrease in diagnosticendoscopic retrograde cholangiopancreatograpies (ERCPs). Stone visualized on imaging had the greatest specificity forcholedocholithiasis. Gallstone pancreatitis was not associated with the risk for choledocholithiasis. Conclusions: The 2019 revision of the ASGE guidelines decreases the utilization of ERCP as a diagnostic modality and offers animproved risk stratification tool.
Surface ozone background in the United States: Canadian and Mexican pollution influences
Wang, H.,Jacob, D.J.,Le Sager, P.,Streets, D.G.,Park, R.J.,Gilliland, A.B.,van Donkelaar, A. Pergamon Press ; Elsevier [distribution] 2009 Atmospheric environment Vol.43 No.6
We use a global chemical transport model (GEOS-Chem) with 1<SUP>o</SUP>x1<SUP>o</SUP> horizontal resolution to quantify the effects of anthropogenic emissions from Canada, Mexico, and outside North America on daily maximum 8-hour average ozone concentrations in US surface air. Simulations for summer 2001 indicate mean North American and US background concentrations of 26+/-8ppb and 30+/-8ppb, as obtained by eliminating anthropogenic emissions in North America vs. in the US only. The US background never exceeds 60ppb in the model. The Canadian and Mexican pollution enhancement averages 3+/-4ppb in the US in summer but can be occasionally much higher in downwind regions of the northeast and southwest, peaking at 33ppb in upstate New York (on a day with 75ppb total ozone) and 18ppb in southern California (on a day with 68ppb total ozone). The model is successful in reproducing the observed variability of ozone in these regions, including the occurrence and magnitude of high-ozone episodes influenced by transboundary pollution. We find that exceedances of the 75ppb US air quality standard in eastern Michigan, western New York, New Jersey, and southern California are often associated with Canadian and Mexican pollution enhancements in excess of 10ppb. Sensitivity simulations with 2020 emission projections suggest that Canadian pollution influence in the Northeast US will become comparable in magnitude to that from domestic power plants.
Liver and Lung Microsomal Metabolism of the Tobacco Alkaloid β-Nicotyrine
Shigenaga, M. K.,Kim, B. H.,Caldera-Munoz, P.,Cairns, T.,Jacob III, P.,Trevor, A. J.,Castagnoli, N. 충남대학교 약학대학 의약품개발연구소 1989 藥學論文集 Vol.5 No.-
The in vitro metabolic fate of β-nicotyrine has been examined in rabbit lung and liver microsomal preparations as part of an effort to characterize the formation of potentially reactive metabolic species that may contribute to the toxic properties of tobacco products. HPLC analysis revealed the formation of an unstable metabolite which displayed HPLC-MS/MS characteristics consistent with the structure 1-methyl-5-(3-pyridyl)-3-pyrrolin-2-one. Attempted synthesis of this pyrrolinone, however, resulted in the isolation of the isomeric 1-methyl-5-(3-pyridyl)-2-pyrrolin-2-one. The HPLC, diode array UV, and mass spectral characteristics of this Δ^4,5-isomer proved to be identical with those of the metabolite derived from β-nicotyrine. Studies in D_2O suggest that the 2- and 3-pyrrolinones are in equilibrium in aqueous solution. The metabolite undergoes autoxidation, possible via radical intermediates, to yield 1-methyl-5-(3-pyridyl)-5-hydroxy-3-pyrrolin-2-one.
Ishan Khosla,Fatima N. Anwar,Andrea M. Roca,Srinath S. Medakkar,Alexandra C. Loya,Aayush Kaul,Jacob C. Wolf,Vincent P. Federico,Arash J. Sayari,Gregory D. Lopez,Kern Singh 대한척추신경외과학회 2024 Neurospine Vol.21 No.1
Objective: To evaluate preoperative disability’s influence on patient-reported outcomes (PROs) following surgery for degenerative spondylolisthesis (DS). Methods: DS patients who underwent surgical intervention were retrospectively identified from a single-surgeon spine registry. Cohorts based on Oswestry Disability Index (ODI) < 41 (milder disability) and ≥ 41 (severe disability) were created. Demographic differences were accounted for with 1:1 propensity score matching. For the matched sample, perioperative and PRO data were additionally collected. PROs assessed included mental health, physical function, pain, and disability. Pre- and up to 2-year postoperative PROs were utilized. Average time to final follow-up was 15.7 ± 8.8 months. Improvements in PROs and minimal clinically important difference (MCID) rates were calculated. Continuous variables were compared through Student t-test and categorical variables were compared through chi-square tests. Results: Altogether, 214 patients were included with 77 in the milder disability group. The severe disability group had worse postoperative day (POD) 1 pain scores and longer hospital stays (p ≤ 0.038, both). The severe disability group reported worse outcomes pre- and postoperatively (p < 0.011, all), but had greater average improvement in 12-item Short Form health survey mental composite score (SF-12 MCS), 9-Item Patient Health Questionnaire (PHQ-9), visual analogue scale (VAS)-back, and ODI by 6 weeks (p ≤ 0.037, all) and PHQ-9, VAS-back and ODI by final follow-up (p ≤ 0.015, all). The severe disability cohort was more likely to achieve MCID for SF-12 MCS, PHQ-9, and ODI (p ≤ 0.003, all). Conclusion: Patients with greater baseline disability report higher POD 1 pain and discharge later than patients with milder disability. While these patients report inferior physical/mental health before and after surgery, they report greater improvements in mental health and disability postoperatively.