4,609 research outputs found

    Signs of outflow feedback from a nearby young stellar object on the protostellar envelope around HL Tau

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    HL Tau is a Class I-II protostar embedded in an infalling and rotating envelope and possibly associated with a planet forming disk, and it is co-located in a 0.1 pc molecular cloud with two nearby young stellar objects. Our ALMA observations revealed two arc-like structures on a 1000 au scale connected to the disk, and their kinematics could not be explained with any conventional model of infalling and rotational motions. In this work, we investigate the nature of these arc-like structures connected to the HL Tau disk. We conducted new observations in the 13CO and C18O (3-2; 2-1) lines with JCMT and IRAM 30m, and obtained the ACA data with the 7-m array. With the single-dish, ACA, and ALMA data, we analyzed the gas motions on both 0.1 pc and 1000 au scales in the HL Tau region. We constructed new kinematical models of an infalling and rotating envelope with the consideration of relative motion between HL Tau and the envelope. By including the relative motion between HL Tau and its protostellar envelope, our kinematical model can explain the observed velocity features in the arc-like structures. The morphologies of the arc-like structures can also be explained with an asymmetric initial density distribution in our model envelope. In addition, our single-dish results support that HL Tau is located at the edge of a large-scale (0.1 pc) expanding shell driven by the wind or outflow from XZ Tau, as suggested in the literature. The estimated expanding velocity of the shell is comparable to the relative velocity between HL Tau and its envelope in our kinematical model. These results hints that the large-scale expanding motion likely impacts the protostellar envelope around HL Tau and affects its gas kinematics. We found that the mass infalling rate from the envelope onto the HL Tau disk can be decreased by a factor of two due to this impact by the large-scale expanding shell.Comment: Accepted by A&

    Use of Multi-Functional Flexible Micro-Sensors for in situ Measurement of Temperature, Voltage and Fuel Flow in a Proton Exchange Membrane Fuel Cell

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    Temperature, voltage and fuel flow distribution all contribute considerably to fuel cell performance. Conventional methods cannot accurately determine parameter changes inside a fuel cell. This investigation developed flexible and multi-functional micro sensors on a 40 ÎĽm-thick stainless steel foil substrate by using micro-electro-mechanical systems (MEMS) and embedded them in a proton exchange membrane fuel cell (PEMFC) to measure the temperature, voltage and flow. Users can monitor and control in situ the temperature, voltage and fuel flow distribution in the cell. Thereby, both fuel cell performance and lifetime can be increased

    Incorporating machine reliability issue and backlogging into the EMQ model - Part II: Random breakdown occurring in inventory piling time

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    This paper presents the second part of a research which is concerned with incorporating machine reliability issues and backlogging into the economic manufacturing quantity (EMQ) model. It may be noted that in a production system when back-ordering is permitted, a random machine failure can take place in either backorder filling stage or in on-hand inventory piling time. The first part of the research investigates the effect of a machine failure occurring in backorder filling stage on the optimal lot-size; while this paper (the second part of the research) studies the effect of random breakdown happening in inventory piling time on the optimal batch size for such an imperfect EMQ model. The objective is to determine the optimal replenishment lot-size that minimizes the overall productioninventory costs. Mathematical modelling is used and the renewal reward theorem is employed to cope with the variable cycle length. Hessian matrix equations are utilized to prove convexity of the cost function. Then, the optimal lot size for such a real-life imperfect manufacturing system is derived. Practitioners and managers in the field can adopt these replenishment policies to establish their own robust production plan accordingly

    High serum levels of procalcitonin and soluble TREM-1 correlated with poor prognosis in pulmonary tuberculosis

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    SummaryObjectivesComparisons of procalcitonin (PCT), C-reactive protein (CRP), and soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) would expand our knowledge of which biomarker is the best predictor for outcomes of patients with pulmonary tuberculosis (PTB).MethodsWe prospectively enrolled 243 PTB patients, in whom PCT, CRP, and sTREM-1 measurement were performed to evaluate their prognostic value for 6-month mortality.ResultsSerum PCT, CRP, and sTREM-1 levels on diagnosis of PTB were significantly higher in nonsurvivors (2.22 ± 6.22 vs. 0.13 ± 0.31 ng/mL, P = 0.043; 42.1 ± 59.4 vs. 12.5 ± 29.1 mg/L, P = 0.004; 332 ± 362 vs. 128 ± 98 pg/mL, P = 0.001, respectively) as compared with 6-month survivors. In multivariate Cox regression analysis, PCT ≧0.5 ng/mL (hazard ratio 4.13, 95% CI, 1.99–8.58) and sTREM-1 ≧129 pg/mL (hazard ratio 3.39, 95% CI, 1.52–7.58) remained independent mortality predictors. Serum PCT and sTREM-1 levels above the cutoffs were also associated with the presence of disseminated tuberculosis.ConclusionsAmong PTB patients, higher PCT, CRP, and sTREM-1 levels are observed in nonsurvivors than in 6-month survivors. Serum levels of PCT and sTREM-1 over the cutoffs are independently associated with a poor outcome. In addition, higher PCT and sTREM-1 levels would raise the clinical suspicion of disseminated tuberculosis

    The experience and attitude of TMU faculty and researchers toward predatory journals and research productivity

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    A questionnaire related to journal submission was sent to researchers for a 2-week period to investigate the submission status as well as the problems faced by Taipei Medical University faculties and researchers. This study has two major findings including the Experience of predatory journal and Calculations of academic performance point and discuss about users’ cognition and their needs from the library and the university, as well as the library policy and services related to predatory journals. It is authors’ hope that the research results can serve as reference for other medical libraries planning to provide relevant services

    Total white blood cell count or neutrophil count predict ischemic stroke events among adult Taiwanese: report from a community-based cohort study

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    BACKGROUND: Evidence about whether white blood cell (WBC) or its subtypes can act as a biomarker to predict the ischemic stroke events in the general population is scanty, particularly in Asian populations. The aim of this study is to establish the predictive ability of total WBC count or subtypes for long-term ischemic stroke events in the cohort population in Taiwan. METHODS: The Chin-Shan Community Cohort Study began from 1990 to 2007 by recruiting 1782 men and 1814 women of Chinese ethnicity. Following a total of 3416 participants free from ischemic stroke events at baseline for a median of 15.9 years; we documented 187 new incident cases. RESULTS: The multivariate relative risk for the comparison of the participants in the fifth and first WBC count quintiles was 1.67 (95% confidence interval [CI], 1.02–2.73; P for trend=0.03), and the corresponding relative risk for neutrophil count was 1.93 (95% CI, 1.13–3.29; P for trend=0.02). The discriminative ability by WBC and neutrophil counts were similar (area under the receiver operating characteristic curve, 0.600 for adding WBC, 0.610 for adding neutrophils, 0.595 for traditional risk factor model). In addition, the net reclassification improvement (NRI) values between the neutrophil and white blood cell count models were not significant (NRI, =-2.60%, P=0.35), indicating the similar discrimination performance for both WBC and neutrophil counts. CONCLUSIONS: WBC and neutrophil count had a similar ability to predict the long-term ischemic stroke events among Taiwanese

    New Attenuation Relationship for Peak Ground and Pseudo-Spectral Acceleration of Normal-Faulting Earthquakes in Offshore Northeast Taiwan

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    Ground motions from normal-faulting earthquakes are generally considered to be smaller than those of strike-slip and thrust events. On 11 April 2011 a crustal normal-faulting earthquake [the Fukushima earthquake (Mw 6.6)] occurred in Eastern Japan. The peak ground acceleration (PGA) observed was considerably higher than the predictions of several ground-motion prediction equations (GMPEs), which were derived mainly from thrust or strike-slip earthquakes. In northeast Taiwan, the tectonic structure of the Ryukyu Arc and the Okinawa Trough typically entail normal-faulting earthquakes. Because of the normal-faulting earthquakes relevance to ground motions and nuclear power plant sites in northeast Taiwan, we evaluated the impact of the ground motion of normal-faulting earthquakes in offshore northeast Taiwan using a newly constructed attenuation relationship for PGA and pseudo-spectral acceleration (Sa). We collected 832 records from 13 normal-faulting earthquakes with focal depths of less than 50 km. The moment magnitude (Mw) of the 13 events was between 4 - 6. The Sa and PGA of normal-faulting earthquakes offshore northeast Taiwan determined with the newly constructed attenuation relationship were higher and lower, respectively, than those obtained using attenuation equations commonly used in the Taiwan subduction zone
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