750 research outputs found

    Phase-locked scroll waves defy turbulence induced by negative filament tension

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    Scroll waves in a three-dimensional media may develop into turbulence due to negative tension of the filament. Such negative tension-induced instability of scrollwaves has been observed in the Belousov-Zhabotinsky reaction systems. Here we propose a method to restabilize scroll wave turbulence caused by negative tension in three-dimensional chemical excitable media using a circularly polarized (rotating) external field. The stabilization mechanism is analyzed in terms of phase-locking caused by the external field, which makes the effective filament tension positive. The phase-locked scrollwaves that have positive tension and higher frequency defy the turbulence and finally restore order. A linear theory for the change of filament tension caused by a generic rotating external field is presented and its predictions closely agree with numerical simulations

    Optimal Order Strategy in Uncertain Demands with Free Shipping Option

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    Free shipping with conditions has become one of the most effective marketing tools; more and more companies especially e-business companies prefer to offer free shipping to buyers whenever their orders exceed the minimum quantity specified by them. But in practice, the demands of buyers are uncertain, which are affected by weather, season, and many other factors. Firstly, we model the centralization ordering problem of retailers who face stochastic demands when suppliers offer free shipping, in which limited distributional information such as known mean, support, and some deviation measures of the random data is needed only. Then, based on the linear decision rule mainly for stochastic programming, we analyze the optimal order strategies of retailers and discuss the approximate solution. Further, we present the core allocation between all retailers via dual and cooperative game theory. The existence of core shows that each retailer is pleased to cooperate with others in the centralization problem. Finally, a numerical example is implemented to discuss how uncertain data and parameters affect the optimal solution

    Awareness research report of hematological disease gene detection in the clinical application

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    目的  探讨医务工作者对血液病基因检测临床应用的认知程度。方法  对参加“第三届陆道培血液病高峰论坛”的371名学者进行了以微信为平台的调查研究,调查内容涉及被调查者的基本信息、工作习惯以及他们对基因检测临床应用多方面的观点。结果  调查对象的年龄主要分布在40岁以下,基因检测在三甲医院或高水平专科医院内应用的频度较高,有32.36% 被调查者认为费用过高是基因检测临床应用最主要的制约因素,68.2% 调查对象可以容忍报告在5-10个工作日内出具,对于基因突变报告有49.1% 临床医生认为报告结果太复杂。结论  基因检测已经在临床诊断方面得到较为广泛的应用,尤其是三甲医院和高水平专科医院,费用、有明确临床意义的临床检测项目较少及时间是基因检测临床应用的主要制约因素,大部分临床医生希望基因检测报告可以在5-10个工作日内出具,并且认为报告结果太复杂。Objective: To investigate the cognition of the medical workers on hematological disease gene detection in the clinical application.  Methods: We investigated 371 scholars participating in the “Third Ludaopei Hematology Forum” through WeChat. Investigation contents include the basic information of respondents, work habits and their views on gene testing in clinical application. Results: The age of the respondents are mainly less than 40 years old. Genetic testing finds wide application in the tertiary hospitals and high level of specialized hospitals. 32.36% of respondents believe that genetic testing cost is the main factor restricting the clinical application; 68.2% respondents can tolerate the fact that report is issued at 5-10 working days. For gene mutations report, 49.1% clinical doctors think the results are too complicated. Conclusion: Genetic testing in clinical diagnosis has been more widely applied, especially for the tertiary hospitals and high level of specialized hospitals. The cost, time and the fewness of clinical testing programs which are clinically significant, are the main factors which restricted the clinical application of genetic testing. Most clinicians hope that genetic testing report will be issued at 5-10 working days, and deem that the results are too complicated.

    The Different Nature in Seyfert 2 Galaxies With and Without Hidden Broad-Line Regions

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    We compile a large sample of 120 Seyfert 2 galaxies (Sy2s) which contains 49 hidden broad-line region (HBLR) Sy2s and 71 non-HBLR Sy2s. From the difference in the power sources between two groups, we test if HBLR Sy2s are dominated by active galactic nuclei (AGNs), and if non-HBLR Sy2s are dominated by starbursts. We show that: (1) HBLR Sy2s have larger accretion rates than non-HBLR Sy2s; (2) HBLR Sy2s have larger \Nev λ14.32\lambda 14.32/\Neii λ12.81\lambda 12.81 and \oiv λ25.89\lambda 25.89/\Neii λ12.81\lambda 12.81 line ratios than non-HBLR Sy2s; (3) HBLR Sy2s have smaller IRASIRAS f60/f25f_{60}/f_{25} flux ratio which shows the relative strength of the host galaxy and nuclear emission than non-HBLR Sy2s. So we suggest that HBLR Sy2s and non-HBLR Sy2s are AGN-dominated and starburst-dominated, respectively. In addition, non-HBLR Sy2s can be classified into the luminous (L[OIII]>1041ergss1L_{\rm [O III]}>10^{41} \rm ergs s^{-1}) and less luminous (L[OIII]<1041ergss1L_{\rm [O III]}<10^{41} \rm ergs s^{-1}) samples, when considering only their obscuration. We suggest that: (1) the invisibility of polarized broad lines (PBLs) in the luminous non-HBLR Sy2s depends on the obscuration; (2) the invisibility of PBLs in the less luminous non-HBLR Sy2s depends on the very low Eddington ratio rather than the obscuration.Comment: Accepted by ApJ, 11 pages, 4 figure

    High Human Bocavirus Viral Load Is Associated with Disease Severity in Children under Five Years of Age

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    Human bocavirus (HBoV) is a parvovirus and detected worldwide in lower respiratory tract infections (LRTIs), but its pathogenic role in respiratory illness is still debatable due to high incidence of co-infection with other respiratory viruses. To determine the prevalence of HBoV infection in patients with LRTI in Shanghai and its correlation with disease severity, we performed a 3-year prospective study of HBoV in healthy controls, outpatients and inpatients under five years of age with X-ray diagnosed LRTIs. Nasopharyngeal aspirates were tested by PCR for common respiratory viruses and by real time PCR for HBoV subtypes 1–4. Nasopharyngeal swabs from healthy controls and serum samples and stools from inpatients were also tested for HBoV1-4 by real time PCR. Viral loads were determined by quantitative real time PCR in all HBoV positive samples. HBoV1 was detected in 7.0% of inpatients, with annual rates of 5.1%, 8.0% and 4.8% in 2010, 2011 and 2012, respectively. Respiratory syncytial virus (RSV) subtype A was the most frequent co-infection detected; HBoV1 and RSVA appeared to co-circulate with similar seasonal variations. High HBoV viral loads (>10(6) copies/ml) were significantly more frequent in inpatients and outpatients than in healthy controls. There was a direct correlation of high viral load with increasing disease severity in patients co-infected with HBoV1 and at least one other respiratory virus. In summary, our data suggest that HBoV1 can cause LRTIs, but symptomatic HBoV infection is only observed in the context of high viral load

    Quality Assured Measurements of Animal Building Emissions: Gas Concentrations

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    Comprehensive field studies were initiated in 2002 to measure emissions of ammonia (NH3), hydrogen sulfide (H2S), carbon dioxide (CO2), methane (CH4), nonmethane hydrocarbons (NMHC), particulate matter \u3c10 µm in diameter, and total suspended particulate from swine and poultry production buildings in the United States. This paper focuses on the quasicontinuous gas concentration measurement at multiple locations among paired barns in seven states. Documented principles, used in air pollution monitoring at industrial sources, were applied in developing quality assurance (QA) project plans for these studies. Air was sampled from multiple locations with each gas analyzed with one high quality commercial gas analyzer that was located in an environmentally controlled on-farm instrument shelter. A nominal 4 L/min gas sampling system was designed and constructed with Teflon wetted surfaces, bypass pumping, and sample line flow and pressure sensors. Three-way solenoids were used to automatically switch between multiple gas sampling lines with ≥10 min sampling intervals. Inside and outside gas sampling probes were between 10 and 115 m away from the analyzers. Analyzers used chemiluminescence, fluorescence,photoacoustic infrared, and photoionization detectors for NH3, H2S, CO2, CH4, and NMHC, respectively. Data were collected using personal computer-based data acquisition hardware and software. This paper discusses the methodology of gas concentration measurements and the unique challenges that livestock barns pose for achieving desired accuracy and precision, data representativeness, comparability and completeness, and instrument calibration and maintenance

    Quality-Assured Measurements of Animal Building Emissions: Particulate Matter Concentrations

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    Federally funded, multistate field studies were initiated in 2002 to measure emissions of particulate matter (PM) \u3c10 μm (PM10) and total suspended particulate (TSP), ammonia, hydrogen sulfide, carbon dioxide, methane, non-methane hydrocarbons, and odor from swine and poultry production buildings in the United States. This paper describes the use of a continuous PM analyzer based on the tapered element oscillating microbalance (TEOM). In these studies, the TEOM was used to measure PM emissions at identical locations in paired barns. Measuring PM concentrations in swine and poultry barns, compared with measuring PM in ambient air, required more frequent maintenance of the TEOM. External screens were used to prevent rapid plugging of the insect screen in the PM10 preseparator inlet. Minute means of mass concentrations exhibited a sinusoidal pattern that followed the variation of relative humidity, indicating that mass concentration measurements were affected by water vapor condensation onto and evaporation of moisture from the TEOM filter. Filter loading increased the humidity effect, most likely because of increased water vapor adsorption capacity of added PM. In a single layer barn study, collocated TEOMs, equipped with TSP and PM10 inlets, corresponded well when placed near the inlets of exhaust fans in a layer barn. Initial data showed that average daily mean concentrations of TSP, PM10, and PM2.5concentrations at a layer barn were 1440 ± 182 μg/m3 (n = 2), 553 ± 79 μg/m3 (n = 4), and 33 ± 75 μg/m3 (n = 1), respectively. The daily mean TSP concentration (n =1) of a swine barn sprinkled with soybean oil was 67% lower than an untreated swine barn, which had a daily mean TSP concentration of 1143 ± 619 μg/m3. The daily mean ambient TSP concentration (n = 1) near the swine barns was 25 ± 8 μg/m3. Concentrations of PM inside the swine barns were correlated to pig activity

    Transition Metal Dichalcogenides for the Application of Pollution Reduction: A Review

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    The material characteristics and properties of transition metal dichalcogenide (TMDCs) have gained research interest in various fields, such as electronics, catalytic, and energy storage. In particular, many researchers have been focusing on the applications of TMDCs in dealing with environmental pollution. TMDCs provide a unique opportunity to develop higher-value applications related to environmental matters. This work highlights the applications of TMDCs contributing to pollution reduction in (i) gas sensing technology, (ii) gas adsorption and removal, (iii) wastewater treatment, (iv) fuel cleaning, and (v) carbon dioxide valorization and conversion. Overall, the applications of TMDCs have successfully demonstrated the advantages of contributing to environmental conversation due to their special properties. The challenges and bottlenecks of implementing TMDCs in the actual industry are also highlighted. More efforts need to be devoted to overcoming the hurdles to maximize the potential of TMDCs implementation in the industry
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