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Social media data are a highly contextual health information source. The objective of this study was to identify Korean keywords for detecting influenza epidemics from social media data.
We included data from Twitter and online blog posts to obtain a sufficient number of candidate indicators and to represent a larger proportion of the Korean population. We performed the following steps: initial keyword selection; generation of a keyword time series using a preprocessing approach; optimal feature selection; model building and validation using least absolute shrinkage and selection operator, support vector machine (SVM), and random forest regression (RFR).
A total of 15 keywords optimally detected the influenza epidemic, evenly distributed across Twitter and blog data sources. Model estimates generated using our SVM model were highly correlated with recent influenza incidence data.
The basic principles underpinning our approach could be applied to other countries, languages, infectious diseases, and social media sources. Social media monitoring using our approach may support and extend the capacity of traditional surveillance systems for detecting emerging influenza. (Disaster Med Public Health Preparedness. 2018; 12: 352–359)
To validate a brief FFQ developed for capturing short-term antioxidant intake in a sample of US college students.
A seventy-four-item antioxidant FFQ was developed based on major antioxidant sources in the American diet. The FFQ was validated against 30 d food records (FR) and plasma antioxidant concentrations. The reliability of the FFQ was evaluated by two FFQ administered at a 1-month interval.
University of Connecticut, CT, USA.
Sixty healthy college students.
Estimates of dietary antioxidants from the FFQ were moderately to highly correlated with those estimated from the 30 d FR (r = 0·29–0·80; P < 0·05) except for γ-tocopherol and β-cryptoxanthin. Total antioxidant capacity from diet only or from diet and supplements estimated by the 30 d FR and FFQ were highly correlated (r = 0·67 and 0·71, respectively; P < 0·0001). The FFQ categorized 91 % of participants into the same or adjacent tertiles of antioxidant intake as the 30 d FR. Most dietary carotenoids estimated from the FFQ were correlated with plasma levels (P < 0·05). Correlation coefficients for test–retest reliability ranged from 0·39 to 0·86. More than 94 % of the participants were classified in the same or adjacent tertiles between the two administrations of the FFQ.
The brief FFQ demonstrated reasonable validity for capturing a comprehensive antioxidant intake profile. This FFQ is applicable in epidemiological or clinical studies to capture short-term antioxidant intake or to simply document the variations of antioxidant intake in intervention trials. Cross-validation studies are warranted in other target populations.
To compare the characteristics and risk factors for surgical site infections (SSIs) after total hip arthroplasty (THA) and total knee arthroplasty (TKA) in a nationwide survey, using shared case detection and recording systems.
Retrospective cohort study.
Twenty-six hospitals participating in the Korean Nosocomial Infections Surveillance System (KONIS).
From 2006 to 2009, all patients undergoing THA and TKA in KONIS were enrolled.
SSI occurred in 161 (2.35%) of 6,848 cases (3,422 THAs and 3,426 TKAs). Pooled mean SSI rates were 1.69% and 2.82% for THA and TKA, respectively. Of the cases we examined, 42 (26%) were superficial-incisional SSIs and 119 (74%) were “severe” SSIs; of the latter, 24 (15%) were deep-incisional SSIs and 95 (59%) were organ/space SSIs. In multivariate analysis, a duration of preoperative hospital stay of greater than 3 days was a risk factor for total SSI after both THA and TKA. Diabetes mellitus, revision surgery, prolonged duration of surgery (above the 75th percentile), and the need for surgery due to trauma were independent risk factors for total and severe SSI after THA, while male sex and an operating room without artificial ventilation were independent risk factors for total and severe SSI after TKA. A large volume of surgeries (more than 10 procedures per month) protected against total and severe SSI, but only in patients who underwent TKA.
Risk factors for SSI after arthroplasty differ according to the site of the arthroplasty. Therefore, clinicians should take into account the site of arthroplasty in the analysis of SSI and the development of strategies for reducing SSI.
Organo-soluble rigid-rod and segmented rigid-rod polyimides and their copolyimides exhibit isotropic solutions in hot m-cresol, but form gels upon cooling. A lyotropic liquid crystal phase is observed below the gel/sol transition. Mechanical gel formation is caused by liquid-liquid phase separation, while the liquid crystal phase may be formed through a nucleation process after gelation. High performance fibers can be spun from the hot isotropic solutions using a dry-jet wet spinning method. After the fibers are drawn at high temperatures, they display tensile strength higher than 3.2 GPa and an initial modulus higher than 130 GPa. In particular, the fibers retain relatively high mechanical properties at elevated temperatures. Solution casted films exhibit very low thermal expansion coefficients and dielectric constants. Their structure, morphology and property relationships will also be discussed.
Ion-beam-assisted deposition (IBAD) was used for cathode preparation in organic light-emitting diodes to fabricate dense electrode. Dark spot growth rate was decreased by employing the IBAD process due to a highly packed aluminum structure inhibiting the permeation of H2O and O2. However, undesirable leakage current was generated because energetic particles of Al assisted by Ar+ ion may damage the organic material resulting in reduction of contact resistance. The decrease of contact resistance in the IBAD device may be caused by large contact area, increase of density of states, and Li diffusion to phenyl-substituted poly-p-phenylene vinylene.
Tin oxide films were deposited on amorphous SiO2/Si and Si (100) substrates by ion-assisted deposition (IAD) at various ion beam potentials (VI) at room temperature and a working pressure of 8 × 10−5 torr. The structural and chemical properties of the as-grown tin oxide films were investigated to determine the effects of the oxygen ion/atom arrival ratio (Ri). X-ray diffraction patterns indicated that the as-grown films with different average energy per atom (Eave) showed different growth directions. The as-grown films with oxygen/Sn ratio (NO/NSn) of 2.03 and 2.02 had preferred orientation of (101) and (002), respectively. In addition, the as-grown film with low Ri was amorphous. Comparison of the observed d spacings with those for standard SnO2 samples, indicated that the crystalline as-grown films had compressive and tensile stress depending on Eave. In transmission electron microscopy analysis, a buffer layer of amorphous tin oxide was observed at the interface between the substrate and the film, and the crystalline grains were grown on this buffer layer. The crystalline grains were arranged in large spherical clusters, and this shape directly affected surface roughness. Rutherford backscattering spectroscopy spectra showed that the tin oxide thin films were inhomogeneous. The density of films decreased and the porosity and oxygen trapped in the films increased with increasing Ri. The densest film had about 6% porosity.
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