Modeling, qualitative analysis, and performance evaluation of theetching area in an IC wafer fabrication system using Petri nets

Integrated circuit (IC) wafer fabrication systems can be characterized as discrete event systems. Petri nets are tools that have been successfully used to model and analyze such systems. This paper reports a project of applying Petri net methodologies to detailed modeling, qualitative analysis, and performance evaluation of the etching area in a real-world IC wafer fabrication system located in Taiwan's Hsinchu Science-Based Industrial Park, To tackle the problem of building a large and complex system model, a synthesis technique is used. The resultant extended net model is checked for important qualitative properties in manufacturing. A simple control policy for deadlock prevention is proposed. To obtain performance measures, simulation is used. The simulation result shows that except a small number of machines, the errors between the simulated and actual utilizations are less than 5%, The validated model can be used to answer many “what-if” questions, such as predicting the maximal throughput and bottleneck machines     

铁艺及居室铁艺装饰

本文讨论了我国铁艺的起源、发展和特征以及铁艺在居室装饰中的特征与运用。说明了铁艺已成为家居装饰的艺术特色之一。     

Influence of hepatitis C virus genotypes and HIV infection on histological severity of chronic hepatitis C. The Hepatitis/HIV Spanish Study Group

OBJECTIVES: The factors influencing the histological severity of chronic hepatitis C (CHC) have not been well established. We therefore investigated the effect of hepatitis C virus (HCV) genotypes and human immunodeficiency virus (HIV) infection on histological liver damage in a cohort of intravenous drug users with CHC. METHODS: We analyzed the histological activity score and the HCV genotypes in 59 HCV-RNA-positive patients with biopsy-proven CHC. Forty-eight (81%) of them had concomitant HIV infection with a CD4+ cell count above 200 x 10(6) cells/L and an absence of AIDS-defining conditions. Multivariate analysis was performed to determine the features associated with the histological severity. RESULTS: Minimal/mild hepatitis was found in 16 patients (27%), moderate chronic hepatitis in 29 (49%), and severe chronic hepatitis in 14 (24%). Patients with HCV subtype 1b had a higher histological score than others (8.7 +/- 3.3 vs. 6.5 +/- 3.2, p = 0.012), either as single or mixed infections. In multivariate analysis, HIV-infected individuals had a higher score of piecemeal necrosis (OR = 21.7, p = 0.002) and a higher stage of fibrosis (OR = 17.9, p = 0.004) than patients without HIV infection. HIV infection and HCV genotype 1b were found to be independent factors of histological severity. CONCLUSIONS: Liver damage in patients with CHC seems to be directly influenced by HCV subtypes. Infection by HCV subtype 1b is closely associated with more severe forms of liver pathology. Furthermore, the presence of HIV infection is an independent factor associated with more aggressive histological damage. In these patients, higher degrees of piecemeal necrosis and fibrosis are commonly seen.     

Ecto-nucleotidases terminate purinergic signalling in the cochlear endolymphatic compartment

There is strong evidence for a purinergic signalling system in the inner ear which regulates auditory sensitivity. This study describes the terminating mechanism for purinergic signalling in the cochlear endolymphatic compartment via ecto-nucleotidases. Exogenous ATP was introduced into the scala media (SM) of the isolated, perfused guinea-pig cochlea, and the effluent was assayed for the adenine nucleotide metabolites by reverse-phase HPLC. Tissue viability was confirmed by fluorescence imaging of cochlear tissues. Extracellular ATP degradation to adenosine was Ca2+/Mg2+ dependent, and was not affected by inhibitors of intracellular ATPases and non-specific alkaline phosphatase. High azide concentration (5 mM) and suramin produced an inhibitory effect on ATP hydrolysis, consistent with inhibition of E-type ATPase activity. The Vmax of ATP hydrolysis (2564 mumol min-1 SM-1) was indicative of high ecto-ATPase activity. Our results support the role of ecto-nucleotidases as a principal mechanism for termination of purinergic signalling within SM, a compartment of the cochlea showing considerable P2X receptor expression.     

Determinants of plasma anti-oxidant vitamin levels in a population at high risk for stomach cancer

A high-performance liquid chromatographic method was developed for the determination of a new antiulcer agent, YJA-20379-2, in human plasma and urine. The sample preparation was simple: 2.5-volume of acetonitrile was added to the biological sample to deproteinize. A 50-microliter aliquot of the supernatant was injected onto a C18 reversed-phase column. The mobile phase employed was methanol-0.1M S?rensen phosphate buffer of pH 7.0-H2O (75:2:25, v/v/v), and was run at a flow-rate of 1.0 ml/min. The column effluent was monitored by ultraviolet detector at 295 nm. The retention time for YJA-20379-2 was approximately 7.0 min. The detection limits for YJA-20379-2 in human plasma and urine were both 100 ng/ml. The coefficients of variation of the assay (within-day and between-day) were generally low (below 9.16%) for both the human plasma and urine. No interference from endogenous substances was found.     

Comparison of endoscopy, radiology and scintigraphy with Tc-99m-exametazine labeled leukocytes and In-111 labeled human polyclonal immunoglobulin G in the diagnosis of inflammatory bowel disease

BACKGROUND: To assess the prognostic value of dipyridamole stress echocardiography in survivors of a first uncomplicated acute myocardial infarction. PATIENTS AND METHODS: A total of 75 patients (68 men, 7 women) aged 58 years (range, 37-77) were studied 3-5 days after a first acute myocardial infarction and followed up for a mean of 10 months. Dipyridamole infusion was administered at high doses: 0.56 mg/kg, adding 0.28 mg/kg if the test was still negative. Two-dimensional echocardiography was continuously recorded during infusion and the test was considered positive if a decrease in regional contractile function appeared and negative if no assynergy was observed up to 15 min after the beginning of dipyridamole administration. A wall motion score index of regional function was derived by summation of individual segment scores divided by the number of interpreted segments. This was calculated for rest and peak dipyridamole echocardiograms. Fifty of 75 patients underwent coronary angiography based on clinical criteria. RESULTS: There were 31 coronary events: 4 deaths, one reinfarction, 13 angina. Thirteen patients underwent coronary revascularization (9 bypass and 4 angioplasty). Dipyridamole echocardiography was positive in 29 patients (39%) and negative in 46 patients (61%). Twenty patients (69%) presented coronary events in the group of positive test versus only 11 (24%) of negatives (p = 0.0001). Four patients died in the positive group while none in the negative group. Sensitivity, specificity and accuracy for all cardiac events were 65, 80 and 73%, respectively. Significant variables from univariate analysis were dipyridamole stress echocardiography response, wall motion score index at peak dipyridamole, ischemic changes in ECG and treatment with two or more antianginal drugs. Multivariate analysis showed positive dipyridamole echocardiography as the only independent prognostic factor to predict cardiac events in postmyocardial infarction patients (RR = 2.56; 95% CI = 1.12-5.84). Four of 19 patients with one vessel disease and 17 of 22 patients with 2-3 vessel disease presented a positive dipyridamole test; whereas the test was negative in the remaining nine patients with normal coronary angiography. CONCLUSION: Dipyridamole stress echocardiography is a safe and feasible pharmacologic stress imaging method to stratify postmyocardial infarction patients at risk of cardiovascular events.     

Renovascular hypertension. Radionuclide renography for detection and prediction of clinical response to revascularization

The most frequently used non invasive tests in the diagnosis of renovascular hypertension are the measurement of peripheral blood renin before and after captopril administration, intravenous pyelogram, renal Doppler examination and radionuclide renography without and with angiotensin converting enzyme inhibitor administration. Measurement of renal vein renin levels and renal angiography are invasive tests commonly used. The latter allows an anatomical diagnosis of renal vein stenosis but does not give information about the functional consequences of such lesion and thus, does not predict the response of blood pressure to revascularization. Radionuclide renography has become the most useful non invasive diagnostic test, with a sensitivity and specificity of 83-94 and 85-97% respectively. It also predicts clinical response to revascularization and is useful for follow up after surgery or angioplasty. It also has good results in patients with renal failure, bilateral stenosis or stenosis in a solitary kidney and in transplanted patients.     

中外合作办学项目中英语教学模式初探

切实提高中外合作办学项目中的英语教学质量,是中等职业学校中的中外合作办学项目顺利发展的关键因素.目前英语教学模式存在外籍教师控堂能力相对较弱,教学效果不够理想,中方教师对教材处理能力不强,学生学习动力不足等诸多问题,阻碍着中外合作项目发展.解决这些问题,一方面要尊重中西文化差异,搭建沟通平台,充分发挥中外教师特长;另一方面要尊重学生差异,实行更加灵活、更富有弹性的分层教学制度.