143 research outputs found

    Anisotropy characteristics of exposed gravel beds revealed in high-point-density airborne laser scanning data

    Get PDF
    The aim of this study was to examine the relationship between the anisotropy direction of exposed gravel bed and flow direction. Previous studies have shown that the anisotropy direction of a gravel bed surface can be visually determined in the elliptical contours of 2-D variogram surface (2DVS). In this letter, airborne laser scanning (ALS) point clouds were acquired at a gravel bed, and the whole data set was divided into a series of 6 m × 6 m subsets. To estimate the direction of anisotropy, we proposed an ellipse-fitting-based automatic procedure with consideration given to the grain size characteristic d50 to estimate the primary axis of anisotropy [hereafter referred to as the primary continuity direction (PCD)] in the 2DVS. The ALS-derived PCDs were compared to the flow directions (for both high and low flow) derived from hydrodynamic model simulation. Comparison of ALS-derived PCDs and simulated flow directions suggested that ALS-derived PCDs could be used to infer flow direction at different flow rates. Furthermore, we found that the ALS-derived PCDs estimated from any elliptical contour of the 2DVS exhibited a similar orientation when the contours of the 2DVS reveal the clear anisotropic structure, demonstrating the robustness of the technique

    Media Coverage and Stock Return in the Taiwan Stock Market

    Get PDF
    The purposes of this paper were to explore the relationship between media coverage and stock returns in Taiwan stock markets. The empirical results were as follows: (1) stock returns showed causality with either media coverage amounts or the degrees of good/bad media coverage; (2) when impacted by the past stock returns, the stock return might finish its response to the impulse around three days and showed a negative effect, whereas when impacted by the past media coverage amounts, the media coverage amount might also finish its response to the impulse within three day and showed a negative effect; (3) when impacted by the degrees of the past good media coverage, the good media coverage degree might finish its response in three days and showed a negative effect, in which a positive effect might be presented on the first two days, while the effect might turn negative on the third day. Given that, when impacted by the past stock returns, the stock return might finish its response to the impulse within three days and showed a negative effect and, when impacted by the degrees of the past good media coverage, the stock return might also finish its response in three days and showed a negative effect. That is, media coverage could be used as an indicator to predict stock returns in the Taiwan stock markets when making investment decisions

    Potential of ILRIS3D Intensity Data for Planar Surfaces Segmentation

    Get PDF
    Intensity value based point cloud segmentation has received less attention because the intensity value of the terrestrial laser scanner is usually altered by receiving optics/hardware or the internal propriety software, which is unavailable to the end user. We offer a solution by assuming the terrestrial laser scanners are stable and the behavior of the intensity value can be characterized. Then, it is possible to use the intensity value for segmentation by observing its behavior, i.e., intensity value variation, pattern and presence of location of intensity values, etc. In this study, experiment results for characterizing the intensity data of planar surfaces collected by ILRIS3D, a terrestrial laser scanner, are reported. Two intensity formats, grey and raw, are employed by ILRIS3D. It is found from the experiment results that the grey intensity has less variation; hence it is preferable for point cloud segmentation. A warm-up time of approximate 1.5 hours is suggested for more stable intensity data. A segmentation method based on the visual cues of the intensity images sequence, which contains consecutive intensity images, is proposed in order to segment the 3D laser points of ILRIS3D. This method is unique to ILRIS3D data and does not require radiometric calibration

    Use of Chinese Herbal Medicine Was Related to Lower Risk of Osteoporotic Fracture in Sarcopenia Patients: Evidence from Population-Based Health Claims

    Get PDF
    Introduction: With population aging, sarcopenia and its accompanying risk of osteoporotic fracture has drawn increased attention. Nowadays, while Chinese herbal medicine (CHM) is often used as complementary therapy for many medical conditions, its effect against likelihood of osteoporotic fracture among sarcopenia subjects was not fully elucidated yet. We therefore conducted a population-level study to compare osteoporotic fracture risk for sarcopenia persons with or without CHM use. Methods: Using the patient record from a nationwide insurance database, we recruited persons with newly diagnosed sarcopenia and simultaneously free of osteoporotic fracture between 2000 and 2010. Propensity score matching was then applied to randomly select sets of CHM users and non-CHM users. All of them were tracked until end of 2013 to measure the incidence and adjusted hazard ratios (HRs) for new new-onset fracture in multivariable Cox proportional hazards model. Results: Compared to non-CHM users, the CHM users indeed had a lower incidence of osteoporotic fracture (121.22 vs 156.61 per 1000 person-years). Use of CHM correlated significantly with a lower fracture likelihood after adjusting for potential covariates, and those receiving CHM treatment for more than two years experienced a remarkably lower risk by 73%. Uses of several herbal formulae were correlated to reduced risk of osteoporotic fracture, such as Caulis Spatholobi, Xuduan, Duzhong, Danshen, Shu-Jing-Huo-Xue- Tang, Du-Huo-Ji-Sheng-Tang, Shao-Yao-Gan-Cao-Tang, and Shen-Tong-Zhu-Yu -Tang. Conclusion: Our study depicted that cumulative CHM exposure was inversely associated with osteoporotic fracture risk in a duration-dependent manner, implying that CHM treatment may be embraced as routine care in preventing incident osteoporotic fracture

    TLR7 and TLR8 Gene Variations and Susceptibility to Hepatitis C Virus Infection

    Get PDF
    Toll-like receptors (TLRs) play pivotal roles in the innate immune system and control inflammatory responses and adaptive immunity. We previously evaluated associations between TLR7 and TLR8 gene SNPs and susceptibility to hepatitis C virus (HCV) infection. Our results suggested that TLR7IVS2-151G and TLR8-129G alleles were present at higher frequency in males of an HCV-infected group as compared to a control group (24.1% vs. 14.4%, p = 0.028; 17.6% vs. 6.8%, p = 0.004, respectively). Based upon their recognition of single stranded viral RNA, this suggested that TLR7 and TLR8 played a significant role in anti-HCV immune responses. Here, we studied the functional effects of these polymorphisms by analyzing the mRNA expressions of TLR7 and TLR8 and cytokine production induced ex vivo by TLR7- and TLR8-specific agonists using whole blood of subjects with different genotypes. The percentage of CD14+ cells from those with an AG haplotype that expressed TLR7 and TLR8 was significantly lower, but higher in intensity compared to cells from those with GG and AC haplotypes. Cells from those with an AG haplotype produced more IFN-α and less amounts of pro-inflammatory cytokines upon stimulation. This suggests that variations in TLR7 and TLR8 genes might impair immune responses during HCV infection

    Effectiveness and Limitations of Hand Hygiene Promotion on Decreasing Healthcare–Associated Infections

    Get PDF
    BACKGROUND: Limited data describe the sustained impact of hand hygiene programs (HHPs) implemented in teaching hospitals, where the burden of healthcare-associated infections (HAIs) is high. We use a quasi-experimental, before and after, study design with prospective hospital-wide surveillance of HAIs to assess the cost effectiveness of HHPs. METHODS AND FINDINGS: A 4-year hospital-wide HHP, with particular emphasis on using an alcohol-based hand rub, was implemented in April 2004 at a 2,200-bed teaching hospital in Taiwan. Compliance was measured by direct observation and the use of hand rub products. Poisson regression analyses were employed to evaluate the densities and trends of HAIs during the preintervention (January 1999 to March 2004) and intervention (April 2004 to December 2007) periods. The economic impact was estimated based on a case-control study in Taiwan. We observed 8,420 opportunities for hand hygiene during the study period. Compliance improved from 43.3% in April 2004 to 95.6% in 2007 (p<.001), and was closely correlated with increased consumption of the alcohol-based hand rub (r = 0.9399). The disease severity score (Charlson comorbidity index) increased (p = .002) during the intervention period. Nevertheless, we observed an 8.9% decrease in HAIs and a decline in the occurrence of bloodstream, methicillin-resistant Staphylococcus aureus, extensively drug-resistant Acinetobacter baumannii, and intensive care unit infections. The intervention had no discernable impact on HAI rates in the hematology/oncology wards. The net benefit of the HHP was US$5,289,364, and the benefit-cost ratio was 23.7 with a 3% discount rate. CONCLUSIONS: Implementation of a HHP reduces preventable HAIs and is cost effective

    Photothermal responsivity of van der Waals material-based nanomechanical resonators

    Full text link
    Nanomechanical resonators made from van der Waals materials (vdW NMRs) provide a new tool for sensing absorbed laser power. The photothermal response of vdW NMRs, quantified from the resonant frequency shifts induced by optical absorption, is enhanced when incorporated in a Fabry-Perot (FP) interferometer. Along with the enhancement comes the dependence of the photothermal response on NMR displacement, which lacks investigation. Here, we address the knowledge gap by studying electromotively driven niobium diselenide drumheads fabricated on highly reflective substrates. We use a FP-mediated absorptive heating model to explain the measured variations of the photothermal response. The model predicts a higher magnitude and tuning range of photothermal responses on few-layer and monolayer NbSe2_{2} drumheads, which outperform other clamped vdW drum-type NMRs at a laser wavelength of 532 532\,nm. Further analysis of the model shows that both the magnitude and tuning range of NbSe2_{2} drumheads scale with thickness, establishing a displacement-based framework for building bolometers using FP-mediated vdW NMRs.Comment: 7 pages, 4 figure

    Lessons Learned of NSPO’s Picosatellite Mission: Yamsat - 1A, 1B & 1C

    Get PDF
    The YamSat is the first developed picosatellite in National Space Program Office’s (NSPO), Taiwan, R.O.C. It is scheduled to flight in the CubeSat launch in 2003. The rapid-prototyping system engineering different from the past formal discipline opens a new satellite development model in NSPO. The YamSat Test Readiness Review Meeting was successfully held in January 2002 and the environmental tests were completed by end March 2002. Besides the breadboard model and engineering test bed to prove of operation concept are built, three YamSats (1A, 1B, & 1C) instead of one are manufactured with slightly different configurations and purposes. The YamSat- 1A is for flight with ambitious and novel R.O.C. made components, including 15 domestic organizations and companies’ participation. The YamSat-1B is basically for backup purpose and demonstration, whereas the YamSat-1C is for amateur communication experiment end-to-end field test, and for public education purpose. This new experience gives fruitful lessons learned and provides low cost space experimentation and education to the next built picosatellites in Taiwan’s universities. Detailed mission and lessons learned are addressed in this paper
    • …
    corecore