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BRIGHT METAL-POOR STARS FROM THE HAMBURG/ESO SURVEY. II. A CHEMODYNAMICAL ANALYSIS
Beers, Timothy C.,Placco, Vinicius M.,Carollo, Daniela,Rossi, Silvia,Lee, Young Sun,Frebel, Anna,Norris, John E.,Dietz, Sarah,Masseron, Thomas American Astronomical Society 2017 The Astrophysical journal Vol.835 No.1
<P>We obtain estimates of stellar atmospheric parameters for a previously published sample of 1777 relatively bright (9 < B < 14) metal-poor candidates from the Hamburg/ESO Survey. The original Frebel et al. analysis of these stars was able to derive estimates of [Fe/H] and [C/Fe] only for a subset of the sample, due to limitations in the methodology then available. A new spectroscopic analysis pipeline has been used to obtain estimates of T-eff, log g, [Fe/H], and [C/Fe] for almost the entire data set. This sample is very local-about 90% of the stars are located within 0.5 kpc of the Sun. We consider the chemodynamical properties of these stars in concert with a similarly local sample of stars from a recent analysis of the Bidelman and MacConnell 'weak metal' candidates by Beers et al. We use this combined sample to identify possible members of the halo stream of stars suggested by Helmi et al. and Chiba & Beers, as well as stars that may be associated with stripped debris from the putative parent dwarf of the globular cluster Omega Centauri, suggested to exist by previous authors. We identify a clear increase in the cumulative frequency of carbon-enhanced metal-poor (CEMP) stars with declining metallicity, as well as an increase in the fraction of CEMP stars with distance from the Galactic plane, consistent with previous results. We also identify a relatively large number of CEMP stars with kinematics consistent with the metal-weak thick-disk population, with possible implications for its origin.</P>
Deering-Rice, Cassandra E,Johansen, Mark E,Roberts, Jessica K,Thomas, Karen C,Romero, Erin G,Lee, Jeewoo,Yost, Garold S,Veranth, John M,Reilly, Christopher A American Society for Pharmacology and Experimental 2012 Molecular pharmacology Vol.81 No.3
<P>Environmental particulate matter (PM) pollutants adversely affect human health, but the molecular basis is poorly understood. The ion channel transient receptor potential vanilloid-1 (TRPV1) has been implicated as a sensor for environmental PM and a mediator of adverse events in the respiratory tract. The objectives of this study were to determine whether TRPV1 can distinguish chemically and physically unique PM that represents important sources of air pollution; to elucidate the molecular basis of TRPV1 activation by PM; and to ascertain the contributions of TRPV1 to human lung cell and mouse lung tissue responses exposed to an insoluble PM agonist, coal fly ash (CFA1). The major findings of this study are that TRPV1 is activated by some, but not all of the prototype PM materials evaluated, with rank-ordered responses of CFA1 > diesel exhaust PM > crystalline silica; TRP melastatin-8 is also robustly activated by CFA1, whereas other TRP channels expressed by airway sensory neurons and lung epithelial cells that may also be activated by CFA1, including TRPs ankyrin 1 (A1), canonical 4α (C4α), M2, V2, V3, and V4, were either slightly (TRPA1) or not activated by CFA1; activation of TRPV1 by CFA1 occurs via cell surface interactions between the solid components of CFA1 and specific amino acid residues of TRPV1 that are localized in the putative pore-loop region; and activation of TRPV1 by CFA1 is not exclusive in mouse lungs but represents a pathway by which CFA1 affects the expression of selected genes in lung epithelial cells and airway tissue.</P>
Optimization of supersonic nozzle flow for titanium dioxide thin-film coating by aerosol deposition
Lee, M.W.,Park, J.J.,Kim, D.Y.,Yoon, S.S.,Kim, H.Y.,Kim, D.H.,James, S.C.,Chandra, S.,Coyle, Thomas,Ryu, J.H.,Yoon, W.H.,Park, D.S. Elsevier 2011 Journal of aerosol science Vol.42 No.11
<P><B>Abstract</B></P><P>Aerosol deposition (AD) is an efficient technique for customized coating of various substrates. The small particles of AD yield a dense coating layer with small voids. AD is amenable to rapid coating (mass production), thus, it is economically attractive. Low-temperature AD coating is desirable because it minimizes the thermal degradation of the substrate. An optimized low-cost AD coating technique is of significant interest to solar-cell engineers seeking to reduce manufacturing costs. While most previous studies ignore the importance of nozzle geometry on coating performance, this paper examines non-optimized nozzles and commensurate shockwaves using computational fluid dynamics (CFD). The optimized nozzle geometry obtained from CFD can rapidly prototype nozzles. The CFD-designed nozzles with optimized geometry yielded significantly improved coating quality over non-optimized nozzles.</P> <P><B>Highlights</B></P><P>► Effects of shockwaves, nozzle geometry and dimensionality, carrier-gas viscosity, and particle density. ► Nozzle geometry was adjusted to yield the optimum condition of <I>P</I><SUB>e</SUB>=<I>P</I><SUB>amb</SUB>, which significantly reduced shock formation. ► We, experimentally and numerically, showed that the correctly expanded (<I>first</I>) nozzle yielded a dense and void-free coating layer. ► While the under-expanded (<I>second</I>) nozzle yielded voids and irregularity.</P>
On knot placement for penalized spline regression
Fang Yao,Thomas C.M. Lee 한국통계학회 2008 Journal of the Korean Statistical Society Vol.37 No.3
This paper studies the problem of knot placement in penalized regression spline fitting. Given a pre-specified number of knots, most existing knot placement methods allocate the knots in an equally spaced fashion. This paper proposes a simple knot placement scheme for improving such “equally spaced methods”. This new scheme first identifies locations of local extrema in the target function, and then it places additional knots in such places. The rationale behind this is that quite often such local extrema coincide with the critical locations for placing knots. The proposed scheme is shown to be superior in a simulation study.
S6K1 Phosphorylation of H2B Mediates EZH2 Trimethylation of H3: A Determinant of Early Adipogenesis
Yi, S.,Um, S.,Lee, J.,Yoo, J.,Bang, S.,Park, E.,Lee, M.,Nam, K.,Jeon, Y.,Park, J.,You, J.,Lee, S.J.,Bae, G.U.,Rhie, J.,Kozma, Sara C.,Thomas, G.,Han, J.W. Cell Press 2016 Molecular Cell Vol.62 No.3
S6K1 has been implicated in a number of key metabolic responses, which contribute to obesity. Critical among these is the control of a transcriptional program required for the commitment of mesenchymal stem cells to the adipocytic lineage. However, in contrast to its role in the cytosol, the functions and targets of nuclear S6K1 are unknown. Here, we show that adipogenic stimuli trigger nuclear translocation of S6K1, leading to H2BS36 phosphorylation and recruitment of EZH2 to H3, which mediates H3K27 trimethylation. This blocks Wnt gene expression, inducing the upregulation of PPARγ and Cebpa and driving increased adipogenesis. Consistent with this finding, white adipose tissue from S6K1-deficient mice exhibits no detectable H2BS36 phosphorylation or H3K27 trimethylation, whereas both responses are highly elevated in obese humans or in mice fed a high-fat diet. These findings define an S6K1-dependent mechanism in early adipogenesis, contributing to the promotion of obesity.
Michael H. Le,David M. Le,Thomas C. Baez,Hansen Dang,Vy H. Nguyen,KeeSeok Lee,Christopher D. Stave,Takanori Ito,Yuankai Wu,Yee Hui Yeo,Fanpu Ji,Ramsey Cheung,Mindie H. Nguyen 대한간학회 2024 Clinical and Molecular Hepatology(대한간학회지) Vol.30 No.2
Background/Aims: Nonalcoholic fatty liver disease (NAFLD) is associated with a multitude of adverse outcomes. We aimed to estimate the pooled incidence of NAFLD-related adverse events. Methods: We performed a systematic review and meta-analysis of cohort studies of adults with NAFLD to evaluate the pooled incidence of adverse events. Results: 19,406 articles were screened, 409 full-text articles reviewed, and 79 eligible studies (1,377,466 persons) were included. Mean age was 51.47 years and body mass index 28.90 kg/m2. Baseline comorbidities included metabolic syndrome (41.73%), cardiovascular disease (CVD) (16.83%), cirrhosis (21.97%), and nonalcoholic steatohepatitis (NASH) (58.85%). Incidence rate per 1,000 person-years for mortality included: all-cause (14.6), CVD-related (4.53), non-liver cancer-related (4.53), and liver-related (3.10). Incidence for liver-related events included overall (24.3), fibrosis progression (49.0), cirrhosis (10.9), liver transplant (12.0), and hepatocellular carcinoma (HCC) (3.39). Incidence for non-liver events included metabolic syndrome (25.4), hypertension (25.8), dyslipidemia (26.4), diabetes (19.0), CVD (24.77), renal impairment (30.3), depression/anxiety (29.1), and non-liver cancer (10.5). Biopsy-proven NASH had higher incidence of HCC (P=0.043) compared to non-NASH. Higher rates of CVD and mortality were observed in North America and Europe, hypertension and non-liver cancer in North America, and HCC in Western Pacific/Southeast Asia (P<0.05). No significant differences were observed by sex. Time-period analyses showed decreasing rates of cardiovascular and non-liver cancer mortality and increasing rates of decompensated cirrhosis (P<0.05). Conclusions: People with NAFLD have high incidence of liver and non-liver adverse clinical events, varying by NASH, geographic region, and time-period, but not sex.
Bang, B.H.,Ahn, C.S.,Lee, J.G.,Kim, Y.T.,Lee, M.H.,Horn, B.,Malik, D.,Thomas, K.,James, S.C.,Yarin, A.L.,Yoon, S.S. ELSEVIER 2017 INTERNATIONAL JOURNAL OF THERMAL SCIENCES Vol.120 No.-
Estimating pressure rise due to deflagration in a fully or partially confined space is of practical importance in safety design of a petrochemical plant. Herein, we have developed a new theoretical model to predict the pressure rise due to deflagration in both fully and partially confined spaces. First, the theoretical model was compared and validated against experimental data from the closed-space experiments with hydrogen, methane, propane, and ethane. The theory predicted accurate pressure rises near the stoichiometric regime for all fuel types; outside the stoichiometric regime, especially, for rich mixtures of hydrocarbons with air, the theory over-predicted pressure rise since it does not account for soot formation and the associated energy losses by radiation. Experimental investigation of propane and hydrogen deflagration was conducted in a partially confined space and the theory-based predictions agreed with the data up to 5%. Parametric numerical study was performed to investigate the effect of the initial pressure and temperature of gaseous fuels on pressure rise.