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Search Results: 1 - 10 of 329344 matches for " Sanghyuk S. Shin "
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Cigarette-Smoking Intensity and Interferon-Gamma Release Assay Conversion among Persons Who Inject Drugs: A Cohort Study
Sanghyuk S. Shin,Manuel Gallardo,Remedios Lozada,Daniela Abramovitz
Pulmonary Medicine , 2012, DOI: 10.1155/2012/828106
Abstract:
The Association between Active and Passive Smoking and Latent Tuberculosis Infection in Adults and Children in the United States: Results from NHANES
Ryan P. Lindsay, Sanghyuk S. Shin, Richard S. Garfein, Melanie L. A. Rusch, Thomas E. Novotny
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0093137
Abstract: Background Few studies assessing the relationship between active and passive smoking and tuberculosis have used biomarkers to measure smoke exposure. We sought to determine the association between active and passive smoking and LTBI in a representative sample of US adults and children. Methods We used the 1999–2000 US National Health and Nutrition Examination Survey (NHANES) dataset with tuberculin skin test (TST) data to assess the association between cotinine-confirmed smoke exposure and latent tuberculosis infection (LTBI) among adults ages ≥20 years (n = 3598) and children 3–19 years (n = 2943) and estimate the prevalence of smoke exposure among those with LTBI. Weighted multivariate logistic regression was used to measure the associations between active and passive smoking and LTBI. Results LTBI prevalence in 1999–2000 among cotinine-confirmed active, passive, and non-smoking adults and children was 6.0%, 5.2%, 3.3% and 0.3%, 1.0%, 1.5%, respectively. This corresponds to approximately 3,556,000 active and 3,379,000 passive smoking adults with LTBI in the US civilian non-institutionalized population in 1999–2000. Controlling for age, gender, socioeconomic status, race, birthplace (US vs. foreign-born), household size, and having ever lived with someone with TB, adult active smokers were significantly more likely to have LTBI than non-smoking adults (AOR = 2.31 95% CI 1.17–4.55). Adult passive smokers also had a greater odds of LTBI compared with non-smokers, but this association did not achieve statistical significance (AOR = 2.00 95% CI 0.87–4.60). Neither active or passive smoking was associated with LTBI among children. Among only the foreign-born adults, both active (AOR = 2.56 (95% CI 1.20–5.45) and passive smoking (AOR = 2.27 95% CI 1.09–4.72) were significantly associated with LTBI. Conclusions Active adult smokers and both foreign-born active and passive smokers in the United States are at elevated risk for LTBI. Targeted smoking prevention and cessation programs should be included in comprehensive national and international TB control efforts.
Smoking among Young Rural to Urban Migrant Women in China: A Cross-Sectional Survey
Xia Wan,Sanghyuk S. Shin,Qian Wang,H. Fisher Raymond,Huilin Liu,Ding Ding,Gonghuan Yang,Thomas E. Novotny
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0023028
Abstract: Rural-to-urban migrant women may be vulnerable to smoking initiation as they are newly exposed to risk factors in the urban environment. We sought to identify correlates of smoking among rural-to-urban migrant women in China.
Cigarette-Smoking Intensity and Interferon-Gamma Release Assay Conversion among Persons Who Inject Drugs: A Cohort Study
Sanghyuk S. Shin,Manuel Gallardo,Remedios Lozada,Daniela Abramovitz,Jose Luis Burgos,Rafael Laniado-Laborin,Timothy C. Rodwell,Thomas E. Novotny,Steffanie A. Strathdee,Richard S. Garfein
Pulmonary Medicine , 2012, DOI: 10.1155/2012/828106
Abstract: We analyzed data from a longitudinal cohort study of persons who inject drugs (PWID) in Tijuana, Mexico, to explore whether cigarette smoking increases the risk of interferon gamma release assay (IGRA) conversion. PWID were recruited using respondent driven sampling (RDS). QuantiFERON-TB Gold In-Tube (QFT) assay conversion was defined as interferon-gamma concentrations <0.35?IU/mL at baseline and ≥0.7?IU/mL at 18 months. We used multivariable Poisson regression adjusted for RDS weights to estimate risk ratios (RRs). Of 129 eligible participants, 125 (96.9%) smoked at least one cigarette during followup with a median of 11 cigarettes smoked daily, and 52 (40.3%) had QFT conversion. In bivariate analysis, QFT conversion was not associated with the number of cigarettes smoked daily ( ). Controlling for age, gender, education, and alcohol use, the RRs of QFT conversion for smoking 6–10, 11–15, and ≥16 cigarettes daily compared to smoking 0–5 cigarettes daily were 0.9 (95% confidence interval (CI), 0.5–1.6), 0.5 (95% CI, 0.3–1.2), and 0.7 (95% CI, 0.3–1.6), respectively. Although this study did not find an association between self-reported smoking intensity and QFT conversion, it was not powered sufficiently to negate such an association. Larger longitudinal studies are needed to fully explore this relationship. 1. Introduction Evidence has accumulated over the years which demonstrates a causal relationship between tobacco use and increased tuberculosis (TB) morbidity and mortality [1–6]. However, the strength of evidence for this relationship varies by TB outcome [3]. For example, while high-quality longitudinal cohort studies provide strong evidence that tobacco use increases the risk of TB disease, the evidence for the relationship between tobacco use and the risk of Mycobacterium tuberculosis infection is relatively weak [3, 7, 8]. Previous studies exploring this relationship utilized cross-sectional or case-control methodologies to determine the association between “ever” or “current” smoking and lifetime infection with M. tuberculosis as determined by a single tuberculin skin test (TST) result [9–14]. Therefore, these studies were not able to assess the temporality between tobacco use and M. tuberculosis infection. For example, a participant infected with M. tuberculosis as a child who subsequently began smoking years later would contribute to the positive association between smoking and TST positivity. An improved understanding of the relationship between cigarette smoking and M. tuberculosis infection would help inform the implementation of tobacco
Scalable Iterative Algorithm for Robust Subspace Clustering
Sanghyuk Chun,Yung-Kyun Noh,Jinwoo Shin
Computer Science , 2015,
Abstract: Subspace clustering (SC) is a popular method for dimensionality reduction of high-dimensional data, where it generalizes Principal Component Analysis (PCA). Recently, several methods have been proposed to enhance the robustness of PCA and SC, while most of them are computationally very expensive, in particular, for high dimensional large-scale data. In this paper, we develop much faster iterative algorithms for SC, incorporating robustness using a {\em non-squared} $\ell_2$-norm objective. The known implementations for optimizing the objective would be costly due to the alternative optimization of two separate objectives: optimal cluster-membership assignment and robust subspace selection, while the substitution of one process to a faster surrogate can cause failure in convergence. To address the issue, we use a simplified procedure requiring efficient matrix-vector multiplications for subspace update instead of solving an expensive eigenvector problem at each iteration, in addition to release nested robust PCA loops. We prove that the proposed algorithm monotonically converges to a local minimum with approximation guarantees, e.g., it achieves 2-approximation for the robust PCA objective. In our experiments, the proposed algorithm is shown to converge at an order of magnitude faster than known algorithms optimizing the same objective, and have outperforms prior subspace clustering methods in accuracy and running time for MNIST dataset.
Pointwise convergence of solutions to Schr?dinger equations
Sanghyuk Lee
Mathematics , 2007,
Abstract: We study pointwise convergence of the solutions to Schr\"odinger equations with initial datum $f\in H^s(\mathbb R^n)$. The conjecture is that the solution $e^{it\Delta}f$ converges to $f$ almost everywhere for all $f\in H^s(\mathbb R^n)$ if and only if $s\ge 1/4$. The conjecture is known true for one spatial dimension and the convergence when $s>1/2$ was verified for $n\ge 2$. Recently, concrete progresses have been made in $\mathbb R^2$ for some $s<1/2$. However, when $n\ge 3$ no positive result is known for the initial datum $f\in H^s(\mathbb R^n)$, $s\le 1/2$. We show that $\lim_{t\to 0} e^{it\Delta}f= f$ a.e. for $f\in H^s(\mathbb R^3)$ whenever $s>1/2-1/{24}$.
On inhomogeneous Strichartz estimates for the Schr?dinger equation
Sanghyuk Lee,Ihyeok Seo
Mathematics , 2012,
Abstract: In this paper we consider inhomogeneous Strichartz estimates in the mixed norm spaces which are given by taking temporal integration before spatial integration. We obtain some new estimates, and discuss about the necessary conditions.
Restriction Estimates for space curves with respect to general measures
Seheon Ham,Sanghyuk Lee
Mathematics , 2013, DOI: 10.1016/j.aim.2013.12.017
Abstract: In this paper we consider adjoint restriction estimates for space curves with respect to general measures and obtain optimal estimates when the curves satisfy a finite type condition. The argument here is new in that it doesn't rely on the \emph{offspring curve} method, which has been extensively used in the previous works. Our work was inspired by the recent argument due to Bourgain and Guth which was used to deduce linear restriction estimates from multilinear estimates for hypersurfaces.
Strichartz Estimates in Spherical Coordinates
Yonggeun Cho,Sanghyuk Lee
Mathematics , 2012,
Abstract: In this paper we study Strichartz estimates for dispersive equations which are defined by radially symmetric pseudo-differential operators, and of which initial data belongs to spaces of Sobolev type defined in spherical coordinates. We obtain the space time estimates on the best possible range including the endpoint cases.
On radial Fourier multipliers and almost everywhere convergence
Sanghyuk Lee,Andreas Seeger
Mathematics , 2014, DOI: 10.1112/jlms/jdu066
Abstract: We study a.e. convergence on $L^p$, and Lorentz spaces $L^{p,q}$, $p>\tfrac{2d}{d-1}$, for variants of Riesz means at the critical index $d(\tfrac 12-\tfrac 1p)-\tfrac12$. We derive more general results for (quasi-)radial Fourier multipliers and associated maximal functions, acting on $L^2$ spaces with power weights, and their interpolation spaces. We also include a characterization of boundedness of such multiplier transformations on weighted $L^2$ spaces, and a sharp endpoint bound for Stein's square-function associated with the Riesz means.
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