5,698 research outputs found

    Valuation of the Risk of SARS in Taiwan

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    Two surveys conducted in Taiwan during the spring 2003 SARS epidemic reveal a high degree of concern about the threat posed by SARS to Taiwan and to residents, although respondents believe they are knowledgeable about the risk of SARS and that it is susceptible to individual control. WTP to reduce the risk of infection and death from SARS is elicited using contingent valuation methods. Estimated WTP is high, implying values per statistical life of US$3 to 12 million. While consistent with estimates for high-income countries, these values are substantially larger than previous estimates for Taiwan and may be attributable to the high degree of concern about SARS at the time the data were collected.

    Numerical Study of the Poisson-Boltzmann Equation for Biomolecular Electrostatics

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    Electrostatics interaction plays a very important role in almost all biomolecular systems. The Poisson-Boltzmann equation is widely used to treat this electrostatic effect in an ionic solution. In this work, a simple mixed discrete-continuum model is considered and boundary element method is used to solve for the solution.Singapore-MIT Alliance (SMA

    The Effect of Prenatal Exposure to Radiation on Birth Outcomes: Exploiting a Natural Experiment in Taiwan

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    We estimate the effect of prenatal exposure to radiation on infant health. By exploiting the 1983 Taiwanese radiation-contaminated buildings (RCBs) accident as a natural experiment, we compare birth outcomes between siblings and cousins exposed to different radiation levels. Given the 1983 accident was unanticipated and exposed cohorts were unaware of the risk until 1992, our design isolates the effect of radiation exposure during pregnancy from other effects. We provide the first evidence that prenatal exposure to a continuous low-level dose of radiation significantly reduces gestational length and increases the probabilities of prematurity and low birth weight

    Aging male symptoms scale (AMS) for health-related quality of life in aging men: translation and adaptation in Malay

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    The Aging Male Symptoms Scale (AMS) measures health-related quality of life in aging men. The objective of this paper is to describe the translation and validation of the AMS into Bahasa Melayu (BM). The original English version of the AMS was translated into BM by 2 translators to produce BM1 and BM2, and subsequently harmonized to produce BM3. Two other independent translators, blinded to the English version, back-translated BM3 to yield E2 and E3. All versions (BM1, BM2, BM3, E2, E3) were compared with the English version. The BM pre-final version was produced, and pre-tested in 8 participants. Proportion Agreement, Weighted Kappa, Spearman Rank Correlation Coefficient, and verbatim responses were used. The English and the BM versions showed excellent equivalence (weighted Kappa and Spearman Rank Coefficients, ranged from 0.72 to 1.00, and Proportion Agreement values ranged from 75.0% to 100%). In conclusion, the BM version of the AMS was successfully translated and adapted

    Upper limits on the solar-neutron flux at the Yangbajing neutron monitor from BATSE-detected solar flares

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    The purpose of this work is to search the Yangbajing neutron monitor data obtained between 1998 October and 2000 June for solar neutrons associated with solar flares. Using the onset times of 166 BATSE-detected flares with the GOES peak flux (1 -- 8 \AA) higher than 1.0×1051.0 \times 10^{-5} Wm2\mathrm{Wm^{-2}}, we prepare for each flare a light curve of the Yangbajing neutron monitor, spanning ±\pm 1.5 hours from the BATSE onset time. Based on the light curves, a systematic search for solar neutrons in energies above 100 MeV from the 166 flares was performed. No statistically significant signals due to solar neutrons were found in the present work. Therefore, we put upper limits on the >> 100 MeV solar-neutron flux for 18 events consisting of 2 X and 16 M class flares. The calculation assumed a power-law shaped neutron energy spectrum and three types of neutron emission profiles at the Sun. Compared with the other positive neutron detections associated with X-class flares, typical 95% confidence level upper limits for the two X-class flares are found to be comparable to the lowest and second lowest neutron fluxes at the top of the atmosphere.In addition, the upper limits for M-class flares scatter in the range of 10210^{-2} to 1 neutrons cm2s1\mathrm{cm^{-2}s^{-1}}. This provides the first upper limits on the solar-neutron flux from M-class solar flares, using space observatories as well as ground-based neutron monitors.Comment: accepted for publication in Astronomy and Astrophysics, section 9. The Su

    Measurement of Scintillation and Ionization Yield and Scintillation Pulse Shape from Nuclear Recoils in Liquid Argon

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    We have measured the scintillation and ionization yield of recoiling nuclei in liquid argon as a function of applied electric field by exposing a dual-phase liquid argon time projection chamber (LAr-TPC) to a low energy pulsed narrow band neutron beam produced at the Notre Dame Institute for Structure and Nuclear Astrophysics. Liquid scintillation counters were arranged to detect and identify neutrons scattered in the TPC and to select the energy of the recoiling nuclei. We report measurements of the scintillation yields for nuclear recoils with energies from 10.3 to 57.3 keV and for median applied electric fields from 0 to 970 V/cm. For the ionization yields, we report measurements from 16.9 to 57.3 keV and for electric fields from 96.4 to 486 V/cm. We also report the observation of an anticorrelation between scintillation and ionization from nuclear recoils, which is similar to the anticorrelation between scintillation and ionization from electron recoils. Assuming that the energy loss partitions into excitons and ion pairs from 83m^{83m}Kr internal conversion electrons is comparable to that from 207^{207}Bi conversion electrons, we obtained the numbers of excitons (NexN_{ex}) and ion pairs (NiN_i) and their ratio (Nex/NiN_{ex}/N_i) produced by nuclear recoils from 16.9 to 57.3 keV. Motivated by arguments suggesting direction sensitivity in LAr-TPC signals due to columnar recombination, a comparison of the light and charge yield of recoils parallel and perpendicular to the applied electric field is presented for the first time.Comment: v2 to reflect published versio

    Spermatogenesis and sertoli cell activity in mice lacking Sertoli cell receptors for follicle stimulating hormone and androgen

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    Spermatogenesis in the adult male depends on the action of FSH and androgen. Ablation of either hormone has deleterious effects on Sertoli cell function and the progression of germ cells through spermatogenesis. In this study we generated mice lacking both FSH receptors (FSHRKO) and androgen receptors on the Sertoli cell (SCARKO) to examine how FSH and androgen combine to regulate Sertoli cell function and spermatogenesis. Sertoli cell number in FSHRKO-SCARKO mice was reduced by about 50% but was not significantly different from FSHRKO mice. In contrast, total germ cell number in FSHRKO-SCARKO mice was reduced to 2% of control mice (and 20% of SCARKO mice) due to a failure to progress beyond early meiosis. Measurement of Sertoli cell-specific transcript levels showed that about a third were independent of hormonal action on the Sertoli cell, whereas others were predominantly androgen dependent or showed redundant control by FSH and androgen. Results show that FSH and androgen act through redundant, additive, and synergistic regulation of spermatogenesis and Sertoli cell activity. In addition, the Sertoli cell retains a significant capacity for activity, which is independent of direct hormonal regulation

    Cultural Constraints on Brain Development: Evidence from a Developmental Study of Visual Word Processing in Mandarin Chinese

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    Developmental differences in phonological and orthographic processing in Chinese were examined in 9 year olds, 11 year olds, and adults using functional magnetic resonance imaging. Rhyming and spelling judgments were made to 2-character words presented sequentially in the visual modality. The spelling task showed greater activation than the rhyming task in right superior parietal lobule and right inferior temporal gyrus, and there were developmental increases across tasks bilaterally in these regions in addition to bilateral occipital cortex, suggesting increased involvement over age on visuo-orthographic analysis. The rhyming task showed greater activation than the spelling task in left superior temporal gyrus and there were developmental decreases across tasks in this region, suggesting reduced involvement over age on phonological representations. The rhyming and spelling tasks included words with conflicting orthographic and phonological information (i.e., rhyming words spelled differently or nonrhyming words spelled similarly) or nonconflicting information. There was a developmental increase in the difference between conflicting and nonconflicting words in left inferior parietal lobule, suggesting greater engagement of systems for mapping between orthographic and phonological representations. Finally, there were developmental increases across tasks in an anterior (Broadman area [BA] 45, 46) and posterior (BA 9) left inferior frontal gyrus, suggesting greater reliance on controlled retrieval and selection of posterior lexical representations

    Detection of Multi-TeV Gamma Rays from Markarian 501 during an Unforeseen Flaring State in 1997 with the Tibet Air Shower Array

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    In 1997, the BL Lac Object Mrk 501 entered a very active phase and was the brightest source in the sky at TeV energies, showing strong and frequent flaring. Using the data obtained with a high density air shower array that has been operating successfully at Yangbajing in Tibet since 1996, we searched for gamma-ray signals from this source during the period from February through August in 1997. Our observation detected multi-TeV γ\gamma-ray signals at the 3.7-Sigma level during this period. The most rapid increase of the excess counts was observed between April 7 and June 16 and the statistical significance of the excess counts in this period was 4.7-Sigma. Among several observations of flaring TeV gamma-rays from Mrk 501 in 1997, this is the only observation using a conventional air shower array. We present the energy spectrum of gamma-rays which will be worthy to compare with those obtained by imaging atmospheric Cerenkov telescopes.Comment: 9 pages, 7 figures, To appear in Ap
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