学生学习水平的马尔可夫链评估法

马尔可夫链评估法是一种以概率论和随机过程理论为基础,运用随机数学模型来分析现实动态系统状态和状态转移情况的一种统计方法。本文研究马尔可夫链在学生的学习水平评估中的应用。1 方法与原理1.1 首先根据学生的学习成绩均分,将学生分为优、良、中、及格、不及五个等级。     

现代流行病学特点和进展

流行病学是一门医学科学的基础学科和方法学，主要具有群体性、分布性、对比性、概率论、宏观方法性、社会医学性、实用性和预防为主的特点。目前流行病学发展趋势是研究领域不断扩大和相关学科不断增加，主要表现包括新评价指标，如累计发生率（CI）、发病率密度（ID）、潜在寿命损失年（PYLL）、失能调整的寿命年（DALY）和新方法，如Meta分析、巢式病例对照研究、捕捉-标记-再捕捉法（CMR）、串联筛查法、按容量比例概率抽样方法（PPS）、批质量保证抽样法（LQAS）、通径分析、随机应答技术（RRT）、德尔菲法、多维综合评价法以及新概念，如主动监测、第2代监测、偏倚、效应修饰作用。展望未来，流行病学将向高层次发展掘进，应高度警惕新出现疾病出现、积极探索非传染病病因、努力提高健康水准，做好流行病学评价工作。     

随机数学理论对Logistic模型的解释

目的：建立Logistic随机数学模型。方法：运用概率论原理，结果：设时刻t菌浇的细胞数为，ξt,M－E（ξt）,V＝D（ξt)，则有dM/dt=K1M-K2(M2 V）。结论：logistic随机数学模型更接近客观实际。     

小议随机事件及其概率的教学

概率论是从数量方面研究随机现象规律性的数学分支学科。随着医药学科研究的日益深入与教学化,作为医学生,学习概率论基础知识,初步掌握一些概率论的基本理论和方法,也是适应现代医药学发展的需要。     

生物信息学中模式识别技术应用与发展

评述生物信息学研究中常见的模式识别技术，主要包括人工神经网络（ANN）、聚类分析法（CA）、主元分析法（PCA）和隐马尔可夫模型（HMM）等，并分析生物信息科学研究中模式识别技术的发展与要求。     

不同缺失场景下各缺失值不同处理方法的结果比较

目的 收集四川省肿瘤医院头颈部肿瘤患者住院病案信息数据，探讨不同缺失场景下数据缺失值通过完成者数据集法、期望-极大化法(EM)、马尔可夫链-蒙特卡洛法(MCMC)3种方法处理后的标准化住院天数对标准化住院费用对数值的回归系数估计值r的优劣。方法 运用R 3.4.1软件，采用蒙特卡洛模拟，通过设定缺失比例和缺失机制模拟不同场景的缺失数据集，运用完成者数据集法、期望-极大化法、马尔可夫链-蒙特卡洛法估计不同缺失场景的模拟数据集中标准化住院天数对标准化住院费用对数值的回归系数估计值r，并与完整数据集的回归系数估计值r_c结果进行比较，从准确度（各种方法估计的r与r_c比较）和精确度（各种方法的r的变异程度s）两个角度进行评价。结果 3种缺失值处理方法的优劣在不同的缺失场景中均有所差异，完全随机缺失（MCAR）和随机缺失（MAR）(1∶2)机制下，当缺失比例小于30%时3种方法的估计值r均在可接受范围（r_c±0.5s _c）；MAR(比例=2∶1)机制任意缺失比例下3种方法的估计值r均在可接受范围内；任意缺失场景下用EM法估计的r的标准误s 最小，且与r_c的标准误s _c最为接近。结论 在选择缺失值处理方法时，应该考虑数据的缺失比例和缺失机制。     

多靶随机搜索模型与搜索性能

人类视觉搜索的过程实际上是用视力角（ｖｉｓｕａｌｌｏｂｅ）去覆盖搜索场景的过程。而搜索模式通常可分为系统搜索和随机搜索。实验发现,当搜索条件相对困难时,参试者多数倾向于进行随机搜索。本研究从概率论的观点提出了关于多靶随机搜索效率的数学模型,经过精心选定有关参数,数学模型与实验结果较好地拟合。     

细胞膜K离子通道的动力学模型

离子通道的开闭反映了蛋白质构象变化的动力学过程，单通道膜片钳记录是有关通道蛋白动力学性质的主要信息来源，对开闭时间长短的分析可以揭示其门控机制。当今，齐次马尔可夫过程深沉用来分析膜片钳实验的数据，但未经验检齐次性，不能拿来即用。我们给出了一个新的模型，称之为非齐次马尔可夫模型，通过它，可以把时间和速度常数ｒｏｃ联系起来，把ｒｏｃ写作ｒｏｃ（ｔ），把ｒｃｏ写作Ｒｃｏ（ｔ），而不再当成常量，我们给出了     

脑出血患者微创血肿清除术后肿瘤坏死因子-α及白细胞介素-6的变化

脑出血（ICH）是临床上常见的脑血管疾病，因缺乏有效的治疗方法，病死率和致残率较高，存活患者常遗留严重的神经功能障碍。通过微创血肿清除术（简称微创术）治疗ICH患者，对急性ICH患者肿瘤坏死因子-α（TNF-α）和白细胞介素-6（IL-6）含量进行了测定，以探讨这2种炎性细胞因子在ICH发生发展过程中的临床意义，并研究微创术对ICH病理生理的影响。     

马尔可夫链模型在医学高等教育教学质量评价中的应用研究

文章首先介绍了医学高等教育教学质量评价中的马尔可夫链模型基本原理,基于医学高等教育的教学过程带有诸多随机因素的特点,运用马尔可夫链建立相应的动态的随机过程模型进行分析和质量评价。通过流行病与卫生统计学学科的教学质量评价的实例检验,证明了将马尔可夫链模型应用到医学高等教育的教学质量评价中的科学性和可行性。最后总结了该方法的优缺点并提出了对其进行改进的思路。     

Value of D-Dimers in patients with acute aortic dissection

Objective: To evaluatel the value of D-dimers in patients with acute aortic dissection (AAD). Methods: This study consisted of 16 patients with AAD and 27 non-AAD patients. Serum D-dimets were measured by Sta-Liatest D-DI immunoturbidimetric assay. Results: D-dimer level was higher (P ＜ 0.001) in patients with AAD(7.91 ± 5.52 μg/ml) than that in non- AAD group(1.57±1.24 μg/ml). D-dimer was positive (＞0.4 μg/ml) in all patients with AAD and in 10 control group patients (37%). Among patients with acute AAD, D-dimers tended to be higher in Stanford A than in Stanford B (8.67 ± 4.31 μg/ml vs. 3.24±1.27 μg/ml, P ＜0.01). D-dimer values tended to be higher in more extended disease(3.84 ± 1.65 μg/ml, 8.57 ± 3.58 μg/ml and 11.87 ± 5.69 μg/ml in thoracic aorta, thoracic and abdominal aorta, thoracic and abdominal aorta and iliacal arteries, respectively, P ＜ 0.05 for both 8.57 ± 3.58 and 11.87 ± 5.69 vs. 3.84 ± 1.65 ). Including the control group into the analysis, we found a sensitivity of 100%, a negative predictive value of 100%, and a specificity of 66% and a positive predictive value of 64% for D-dimer in diagnosis of AAD in our patients with suspected AAD. Conclusion: D-dimer was elevated in patients with AAD. A negative D-dimer test result could be useful in excluding AAD.     

Research of combined liver-kidney transplantation model in rats

Objective： To set up a simple and reliable rat model of combined liver-kidney transplantation. Methods： SD rats served as both donors and recipients. 4℃ sodium lactate Ringer＇s was infused from portal veins to donated livers,and from abdominal aorta to donated kidneys, respectively. Anastomosis of the portal vein and the inferior vena cava （IVC） inferior to the right kidney between the graft and the recipient was performed by a double cuff method, then the superior hepatic vena cava with suture. A patch of donated renal artery was anastomosed to the recipient abdominal aorta. The urethra and bile duct were reconstructed with a simple inside bracket. Results： Among 65 cases of combined liver-kidney transplantation, the success rate in the late 40 cases was 77.5%. The function of the grafted liver and kidney remained normal. Conclusion： This rat model of combined liver-kidney transplantation can be established in common laboratory conditions with high success rate and meet the needs of renal transplantation experiment.     

BLOOD PRESSURE CHANGE WITH AGE IN SALT-SENSITIVE TEENAGERS

Objective To observe blood pressure change with age in salt-sensitive teenagers whose salt sensitivity were determined by repeated testing.Methods Salt sensitivity was determined through intravenous infusion of normal saline combined with volume-depletion by oral diuretic furosemide in 55 teenagers. After five years, salt sensitivity was re-examined and subject blood pressure was followed up. Blood pressure changes in salt-sensitive teenagers were compared to that of non-salt sensitive teenagers over five years.Results After 5 years, the repetition rate of salt sensitivity determined by intravenous saline loading is 92.7%. In teenagers with salt sensitivity on the baseline, both the systolic blood pressure increments and increment rates were much higher than non-salt sensitive teenagers (12.7±12.1 mmHg vs. 2.8±5.2 mmHg, P＜ 0.01; 12.2%± 12.0% vs. 2.5% ±4.4%, P＜ 0.001,respectively). There was a similar trend for diastolic blood pressure (8.4 ± 6.4 mmHg vs. 3.7 ± 6.4 mmHg, P = 0.052; 13.2% ±10.6 % vs. 6.8%± 10.1%, P = 0.053, respectively).Conclusions Salt sensitivity determined by intravenous saline loading showed good reproducibility. Blood pressure increments with age were much higher in salt-sensitive teenagers than non-salt sensitive teenagers, especially in terms of systolic blood pressure.     

安心颗粒对急诊经皮冠状动脉介入术后生活质量影响的研究

目的：评价使用安心颗粒对急诊经皮冠状动脉介入术（PPCI）术后生活质量的影响.方法：将160例接受PPCI的急性ST段抬高型心肌梗死患者随机分为安心颗粒组（术前顿服安心颗粒8.8g,术后安心颗粒4.4 g/次,每日2次）和对照组（仅接受基础药物治疗）.所有患者均服用阿司匹林、氯吡格雷和阿托伐他汀.分别在入院时、出院前1d、出院后180 d时,应用心肌梗死多维度量表（MIDAS）、中文版SF-36评价量表对患者生活质量评分.并观察术后30 d以内的出血并发症、血小板减少症发生情况.结果：入院时和出院前1d,两组患者的心肌梗死MIDAS、SF-36量表评分比较无差异（P＞0.05）;出院后180 d时,与对照组比较,安心颗粒组MIDAS、SF-36评分明显减低（P＜0.05）;组内与入院时比较,两组出院前1d、出院后180 d时,MIDAS、SF-36评分均降低（P＜0.05）.两组患者在随访期间均无大量出血、少量出血、重度和极重度血小板减少症发生,安心颗粒组有4例、对照组有7例发生不明显出血（P＞0.05）.两组发生轻度血小板减少症的患者数比较无差异（P＞0.05）.结论：PPCI使用安心颗粒,能改善急性ST段抬高型心肌梗死患者的生活质量,且不增加出血风险.     

The comparative studies of the influences of Urapidil and Nicardipine on sino-atrial node function, atrio-ventricular node function and hemodynamics

Objective:To investigate the influences of urapidil and nicardipine on rabbit sinus function,atrio-ventricular node function and hemodynamics.Methods:Thirty-two Angora's rabbits were selected and randomly divided into four groups.U1 group:urapidil 0.25 mg/kg;U2 group:urapidil 0.5 mg/kg;N1 group:nicardipine 10 μg/kg;N2 group:nicardipine 20 μg/kg.All these medicine were administrated within 30 seconds.Measurements were taken before and after the administration of urapidil or nicardipine for the following data:mean blood pressure(MAP),heart rate(HR),sino-atrial conduction time(SACT),maximal sinoatrial recovery time(SNRTmax)corrected sinus node recovery time(CSNRT),index of sinus node recovery time(SNRTI),Wenckebach A-V conduction frequency (WB),and P-R interval.Results:Significant MAP and HR changes were identified in all of the four groups before and after administration of both urapidil and nicardipine.No significant changes could be found in the rest of the parameters.Intergroup analysis showed that SACT and CSNRT of N1 and N2 groups were shorter than those of the U2 group(P＜0.01);the MAP decreased(P＜0.01)and the HR increased drastically(P＜0.01).Conclusions:Neither urapidil(0.25 mg/kg,0.5 mg/kg)nor nicardipine(10μg/kg,20μg/kg)has any significant influence on rabbit sinus function or rabbit atrio-ventricular node function.Nicardipine could be a better choice than urapidil for parafunctional sinus node patients.     

Expression of OPGmRNA and ODFmRNA in the patients of hip fracture due to osteoporosis

Objective：To investigate the gene expression of osteoprotegerin（OPG） and osteoclast differentiation factor（ODF） in the bone tissue of patients with hip fracture due to osteoporosis. Methods：OPGmRNA and ODFmRNA in the bone tissue in 50 cases of osteoporosis sufferers（over 50 years old） with hip fracture（Observer Group） and 30 cases of hip facture sufferers with no osteoporosis（Control group） were analyzed with the Semi-Quantitative RT-PCR method. Results：The mRNA expressed of ODF, OPG were both high in the patients with hip fracture. In the control group, the expression of OPG mRNA was observed, while the expression of ODF mRNA was very slight. Conclusion：Aged patients contained all signals including OPG, ODF that are essential for inducing osteoclastogenesis and promoting bone resorption.     

The clinicopathological and immuohistochemical analysis of solid-pseudopapillary tumor of the pancreas： report of 9 cases

Objective：To investigate the clinical features, pathological characteristics and immunophenotype of solid-pseudopapillary tumor of the pancreas（SPTP）. Methods：Nine surgically treated cases of SPTP were retrospectively reviewed. Hematoxylin and Eosin（HE） staining and immunohistochemical staining were used to analyze all cases, and the general clinical data was collected. Results：Six patients were asymptomatic except for a palpable mass. Two patients complained of vague-epigastric pain. One patient appeared jaundice. The tumor was encapsulated and solid tissues alternately with cystic tissues. Histologically, the histological structure of solid portion was pseudopapillary with a fibrovascular core. Tumor cells were uniform and medium-sized which were arranged in sheets ets or nests or pseudopapillary patterns. Immunohistochemical studies demonstrated that SPTP proved positive in vimentin（9/9 cases）, AAT（9/9 cases）, NSE（9/9 cases）, ACT（7/9 cases）, CK20（2/9 cases）, CgA（1/9 cases）, S-100（3/gcases）, PR（4/gcases）, Syn（3/9 cases） and CD56（5/9cases）, negative in CEA and ER. Conclusion：SPTP is a tumor predominantly occurring in young women frequently without special symptoms. This tumor has various characteristical histological patterns with different immunophenotype.     

Dynamic Changes in Serum Estradiol and Progesterone levels in Patients of Premenstrual Syndrome with Adverse Flow of Liver-qi

Objective:To probe into the influence of changes of ovarian hormones on the pathogenesis of the specific sub-type premenstrual syndrome(PMS)and reveal partial microcosmic mechanisms of adverse flow of liver-qi.Methods:Estradiol(E2)and progesterone(P)levels in serum were determined at different phases of menstrual cycle by radioimmunoassay.Results:In the group of PMS with adverse flow of liver-qi.the secretive peak value Of E2 and P at the follicular phase significantly decreased,and the secretive peak value at the luteal phase did not come into being.Conclusions:Low E2 and P secretive peak at the follicular phase and absence of secretive peak at the luteal phase is one of the microcosmic mechanisms of PMS with adverse flow of liver-qi.One of the pathophysiologic mechanisms of specific sub-type PMS is probably the continuous low level of E2and P.     

Real-time Three-dimensional Echocardiography in Assessment of Left Ventricular and Right Ventricular Volumes

Real-time three-dimensional echocardiography (RT3DE)is a new ultrasound technique that enables dynamic threedimensional visualization and quantification of the heart in real time. Investigation of feasibility and methodology of RT3DE in determining left ventricular (LV) and right ventricular (RV) volumes, RT3DE was performed in 35 normal adults using Philips SONOS 7500 system with a 2-4 MHz matrix array transducer. The 60°×60° "pyramid" volume database was obtained and analyzed on a TomTec echo workstation. Both LV and RV volumes were calculated with four 3DE methods (i.e. apical 2, 4, 8, and 16-plane) through manually tracing ventricular endocardial borders in end diastole and end systole. Stroke volumes were then calculated. LV volume was also measured by 2DE Simpson's rule using GE VIVID 7 ultrasound machine.     

SCREENING FOR A 21-CHROMOSOME ABNORMALITY IN PREIMPLANTED EMBRYOS OF ELDERLY WOMEN

Increasing maternal age is the only etiological factor unequivocally linked to Down's syndrome in humans. The occurrence rate of newborns with Down's syndrome is about 1/220 in women over 35 years old. However, the occurrence rate in embryos fertilized in vitro, of the elder woman is unclear. Using FISH we screened the number of chromosome 21 in preimplanted embryos of 5 elderly women (average age, 38.4 years) to study the feasibility and necessity of screening trisomy 21 in embryos in patients over 35 years old at the in vitro fertilization (IVF) center.