概率2-距离空间的概率列紧性

本文讨论了2－PM空间中集合的概率列紧性，在一定的条件下证明了2－Menger空间中的概率列紧集是概率可分的。     

吡格列酮治疗伴胰岛素抵抗非糖尿病缺血性卒中或短暂性脑缺血发作的成本效用分析

目的:评价在当前中国医疗环境下,伴胰岛素抵抗的非糖尿病缺血性卒中或短暂性脑缺血发作(TIA)后吡格列酮治疗的成本效用情况。方法:建立短期决策树模型和长期马尔可夫模型以评估卒中或TIA后吡格列酮治疗与非吡格列酮治疗的成本效用情况。采用临床试验数据、现有数据库分析、文献查阅等方法收集治疗效果、成本、健康效用、转移概率等模型参数,估计每个质量调整生命年(QALY)的短期和长期成本并进行单因素和概率敏感性分析,以模型拟合结果的稳定性。结果:与不使用吡格列酮治疗相比,吡格列酮治疗从第6年开始是值得的。吡格列酮治疗后30年增加0.129个QALY,增加成本6 990元,增量成本效果比(ICER)为54 186元·QALY^-1。概率敏感性分析显示,当意愿支付阈值为243 000元·QALY^-1时,吡格列酮治疗在99.9%的模型模拟中具有成本效果性。结论:在我国当前国情背景下,对于伴胰岛素抵抗非糖尿病缺血性卒中或TIA患者,使用吡格列酮治疗是值得的。     

Cox模型及预测列线图在R软件中的实现

基于R软件survival包和design包对实例进行生存分析,旨在介绍R软件中拟合Cox回归模型、绘制生存概率预测列线图的方法。结果表明,在R软件中建立Cox回归模型并绘制列线图简单、方便,在估计相对风险的基础上,对个体生存概率的预测直观、形象。     

探讨牙列重度磨损的病因及修复治疗

目的探讨牙列重度磨损的病因及修复方法。方法回顾分析自2009年9月至2012年9月在本院治疗的34名牙列磨损患者资料。根据患者牙列磨损的程度,先做暂时性颌垫,在行永久性颌修复治疗。结果其中23名患者采用颌垫式活动义齿修复,8名患者采用固定桥修复,3名患者采用套筒冠义齿。结论牙列重度磨损的修复关键要缓解牙颌紧的状态,恢复垂直距离,根据患者实际病情采用适合患者的修复方案。     

多门限分割技术及其在微核图象处理中的应用

利用概率统计中组间距离与组内距离的思想，对一幅图象的象素点进行分类，以达到最优分割图象的目的     

对牙列缺失较长的义齿修复体会

在牙列缺失修复的病人中,经常会遇到一些拔牙时间5年以下而不镶复的患者,按常规修复不能取得良好的固位,如果适当采取以下一些措施,都能取得满意的效果。1 病例介绍患者秦××,男,72岁,牙列缺失近9年,因儿女劝说来我科就诊,要求镶复。口腔检查:上、下牙列缺失,软组织发白,粘膜干燥,无光泽。上颌牙槽嵴低平,前牙区突出,唇颊系带紧,连牙槽嵴。双侧上颌结节明显突出,腭盖低平。下颌牙槽嵴极度低平,舌系带紧连牙槽嵴,下唇肌肉紧张,颌间距离偏大。2 治疗方法2.1 取模一次采取的模型感到吸附力较差,调适量的印模材,均匀放在刚采下的印模上,重新放入口内,在印模材料     

恩格列净治疗射血分数降低型心力衰竭的成本—效果分析

目的 评价恩格列净联合标准治疗方案治疗射血分数降低型心力衰竭患者的成本-效果分析。方法 基于EMPEROR-Reduced试验的临床研究数据以及中国统计数据,构建循环周期为3个月、时限为10年的多状态Markov心力衰竭模型,以医疗卫生系统为研究角度,模拟恩格列净联合标准治疗方案（恩格列净组）和单独标准治疗方案（对照组）治疗射血分数降低型心力衰竭患者的质量调整生命年（QALYs）和直接医疗成本,利用成本-效果分析对恩格列净进行药物经济学评价。结果 与对照组方案相比,恩格列净组总人群成本为33 585.55元,高出对照组5223.34元,总效用值为3.98 QALYs,高出对照组0.14 QALYs;计算增量成本-效果比（ICER）值为36 849.47元/QALYs,低于我国2021年人均国内生产总值（GDP） 80 976.00元,非糖尿病人群与糖尿病人群模拟结果与总人群一致。单因素敏感性分析显示,在总人群中,心血管性死亡是成本-效果分析的最敏感因素。概率敏感性分析显示,在意愿支付（WTP）阈值为80 976.00元/QALYs时,总人群使用恩格列净联合标准治疗方案具有经济性的概率为...     

Locale中的插入性(英文)

对于‘■’关系满足插入性的locale,我们给出了Banaschewski-Mulvey式紧正则反射的构造性描述。进一步,证明了正规locale满足插入性;从而,给出了其紧正则反射。     

恩格列净治疗射血分数降低的心力衰竭的药物经济学评价

目的对恩格列净治疗射血分数降低的心力衰竭(HFrEF)进行药物经济学评价,为临床合理用药和医疗卫生决策提供循证依据。方法运用马尔可夫模型对恩格列净治疗HFrEF的方案进行成本-效果分析,评价标准治疗方案联合恩格列净(恩格列净组)与单用标准治疗方案(标准治疗组)的成本和效果。临床参数来自EMPEROR-Reduced研究,成本和健康效用值数据来自己发表的文献。模型的循环周期为1个月,模拟时间为20年。采用单因素敏感性分析和概率敏感性分析对成本-效果分析的结果进行验证。结果恩格列净组较标准治疗组每增加1个质量调整生命年要多花费37 995.94元,低于1倍2020年中国人均国内生产总值(GDP),即72 447元。单因素敏感性分析结果显示,两组患者的稳定状态住院率是对增量成本-效果比影响最大的因素。概率敏感性分析结果显示,当支付意愿阈值(WTP)取1倍2020年中国人均GDP(72 447元)时,恩格列净组有58.8%的概率具有成本-效果优势;当WTP取3倍2020年中国人均GDP(217 341元)时,恩格列净组有63.8%的概率具有成本-效果优势。结论采用标准治疗方案联合恩格列净治疗HFrEF较单纯采用标准治疗方案更具有成本-效果优势,但经济性概率不高。     

沙库巴曲缬沙坦、达格列净和恩格列净治疗射血分数降低心力衰竭的成本-效用分析

目的 从我国卫生体系的角度出发,对比沙库巴曲缬沙坦、达格列净和恩格列净3种方案治疗射血分数降低心力衰竭（HFrEF）的成本-效用分析,为临床治疗药物的选择提供依据。方法 基于DAPA-HF和EMPEROR-Reduced 2项临床试验数据构建Markov模型,模拟HFrEF疾病发展状况,评价3种方案治疗HFrEF患者的成本-效用,并对结果进行敏感性分析。结果 与恩格列净组相比,达格列净组和沙库巴曲缬沙坦组的增量成本-效用比（ICUR）分别为20 248.63,23 860.98元/质量调整生命年（QALY）;与达格列净组相比,沙库巴曲缬沙坦组的ICUR为28 423.95元/QALY,3组两两相比的ICUR均小于2021年1倍人均国内生产总值。概率敏感性分析显示,当意愿支付阈值超过30 000元/QALY时,沙库巴曲缬沙坦较达格列净、恩格列净方案具有经济性的概率为100%。结论 沙库巴曲缬沙坦在治疗HFrEF方面的经济性优于达格列净和恩格列净。     

一般分布和多元正态分布的检验

分别根据Q-Q图法的原理以及条件概率性质和线性回归性质检验一般分布和多元正态分布,利用模拟方法验证。结果表明方法正确,具有一定的实用价值,并且证实马氏距离并不服从卡方分布。     

计算古典概率的若干简化方法

基于古典概率计算这个概率论学科教学中碰到的首个重点与难点,提出了突出重点,化解难点的若干简化方法。将古典概率的计算明确分解为两个步骤完成:第一步是根据欲求概率的事件A的本质特征选取适当的样本空间Ω,使它满足"有限、等可能"且AΩ;第二步是计算Ω与A所包含的样本点数nΩ与mA,强调应当重视第一步。     

Pharmacokinetic parameter estimations by minimum relative entropy method

For estimating pharmacokinetic parameters, we introduce the minimum relative entropy (MRE) method and compare its performance with least squares methods. There are several variants of least squares, such as ordinary least squares (OLS), weighted least squares, and iteratively reweighted least squares. In addition to these traditional methods, even extended least squares (ELS), a relatively new approach to nonlinear regression analysis, can be regarded as a variant of least squares. These methods are different from each other in their manner of handling weights. It has been recognized that least squares methods with an inadequate weighting scheme may cause misleading results (the “choice of weights” problem). Although least squares with uniform weights, i.e., OLS, is rarely used in pharmacokinetic analysis, it offers the principle of least squares. The objective function of OLS can be regarded as a distance between observed and theoretical pharmacokinetic values on the Euclidean space ℝ^N, whereN is the number of observations. Thus OLS produces its estimates by minimizing the Euclidean distance. On the other hand, MRE works by minimizing the relative entropy which expresses discrepancy between two probability densities. Because pharmacokinetic functions are not density function in general, we use a particular form of the relative entropy whose domain is extended to the space of all positive functions. MRE never assumes any distribution of errors involved in observations. Thus, it can be a possible solution to the choice of weights problem. Moreover, since the mathematical form of the relative entropy, i.e., an expectation of the log-ratio of two probability density functions, is different from that of a usual Euclidean distance, the behavior of MRE may be different from those of least squares methods. To clarify the behavior of MRE, we have compared the performance of MRE with those of ELS and OLS by carrying out an intensive simulation study, where four pharmacokinetic models (mono- or biexponential, Bateman, Michaelis-Menten) and several variance models for distribution of observation errors are employed. The relative precision of each method was investigated by examining the absolute deviation of each individual parameter estimate from the known value. OLS is the best method and MRE is not a good one when the actual observation error magnitude conforms to the assumption of OLS, that is, error variance is constant, but OLS always behaves poorly with the other variance models. On the other hand, MRE performs better than ELS and OLS when the variance of observation is proportional to its mean. In contrast, ELS is superior to MRE and OLS when the standard deviation of observation is proportional to its mean. In either case the difference between MRE and ELS is relatively small. Generally, the performance of MRE is comparable to that of ELS. Thus MRE provides as reliable a method as ELS for estimating pharmacokinetic parameters.     

Activity spaces among injection drug users in San Francisco

BackgroundRepresentations of activity spaces, defined as the local areas within which people move or travel in the course of their daily activities, are unexplored among injection drug users (IDUs). The purpose of this paper is to use an activity space framework to study place and drug user health.MethodsData for this analysis is from an epidemiological study of street-recruited IDUs in San Francisco (N = 1084). Study participants reported geographic intersections of where they most often slept at night, hung out during the day, and used drugs during a 6 month time period. We used GIS software to construct and map activity space routes of street-based network paths between these intersections. We further identified if syringe exchange program (SEP) locations intersected with, participant activity space routes. We used logistic regression to estimate associations between activity space variables and HIV serostatus, syringe sharing, and non-fatal overdose, after adjusting for individual and Census tract covariates.ResultsMean activity space distance for all participants was 1.5 miles. 9.6% of participants had a SEP located along their activity space. An increase in activity space distance was associated with a decrease in odds of being HIV positive. An increase in residential transience, or the number of different locations slept in by participants in a 6 month time period, was associated with higher odds of syringe sharing. Activity space distance was not independently associated with overdose or syringe sharing.DiscussionResearch that locates individuals in places of perceived importance is needed to inform placement and accessibility of HIV and overdose prevention programs. More attention needs to be given to the logistics of collecting sensitive geospatial data from vulnerable populations as well as how to maximize the use of GIS software for visualizing and understanding how IDUs interact with their environment.     

Conformational energy analysis of melanostatin

Conformational energy calculations were carried out on the hypothalamic hormone melanostatin, a tripeptide with the primary structure H-L-Pro-L-Leu-Gly-NH₂. The calculated lowest energy conformation was a type II β bend, very similar to that reported in an X-ray crystal study. This conformation, however, was only one of 109 low-energy structures (≤ 3 kcal/mol above the global minimum), indicating that the molecule in solution exists as an ensemble of conformations and is very flexible, in agreement with relaxation data from n.m.r. measurements. A statistical analysis yielded an average end-to-end distance of 6.8 Å and a bend probability of 0.62, suggesting that, in nonpolar solvents, bend structures predominate within the statistical ensemble. The statistical analysis, however, also yielded a probability of only 0.11 for the occurrence of a 4 → 1 hydrogen bond. Hence, the calculations show that, although bend conformations predominate, bends would be difficult to observe in solution if the experiments were designed only to detect 4 → 1 hydrogen bonds.     

A theoretical approach to the spectrophotometry of nucleic acids on paper disks

A linear approximated model is presented that takes into account a local anisotropic distribution of scattered light within a turbid medium. Light intensity depends upon the distance from the boundary surface of the scattering centers, so that the probability of photon-chromophore interaction is a function of the distance. For the sake of simplicity it is assumed that there are only two main zones, corresponding to two probabilities of photon-chromophore interaction. In this form, the Kubelka-Munk theory fits the experimental data supplied by bichromatic photometry of nucleic acids on paper disks.     

Restricted psychological horizon in active methamphetamine users: future, past, probability, and social discounting

Methamphetamine users (MAU) exhibit an exaggerated bias for immediate rewards that reflects a restricted time horizon, where outcomes in the future are excessively discounted. An accumulating literature indicates that time in the future shares features with other dimensions of psychological distances including time in the past, probability, and social distance, suggesting that bias for immediacy may be reducible to a more general restriction of psychological horizon. The purpose of the present study was to explore generalized restricted psychological horizon in active MAU by assessing future, past, probability, and social discounting. Compared with nonusing controls, MAU preferred psychologically proximal outcomes, resulting in higher rates for all types of discounting, which supports the conceptualization that MAU insufficiently integrate outcomes of psychological distance (i.e. in the future, the past, probabilistic, for others) into the valuation of current behavioral alternatives. The present results are suggestive of a more fundamental process of problematic decision-making associated with methamphetamine use, indicating the necessity of more comprehensive approaches to address the generalized limitations of restricted psychological horizon.     

Solvent constraints on the property space of acetylcholine. 2. Ordered media

The objective of this study was to investigate the conformational and property spaces of acetylcholine in hydrated octanol and in a membrane model. Molecular dynamics simulations of long duration (15 ns) were carried out, yielding 3000 conformers. For each, we calculated N(+)-C8 distance, solvent-accessible surface area (SAS), polar surface area (PSA), dipole moment, and lipophilicity (virtual logP). Their variations as a function of the dihedral angles tau(2) and tau(3) remained unexpectedly broad and comparable to those seen previously in a vacuum, in water, and in chloroform.(12) Thus, each of the seven conformational clusters was able to access a marked proportion of the lipophilicity space accessible to acetylcholine (0.40 in the logP scale). Histograms of logP distributions revealed two overlapping populations, namely more lipophilic and more hydrophilic. Their deconvolution into two Gaussian curves demonstrated solvent-mediated constraints on the lipophilicity space of acetylcholine, clearly showing how a polar medium favors polar conformers, whereas the opposite is true for media of low polarity.     

A new device for microinjection of drugs into the lower brain stem of conscious rats: Studies on site of action of morphine

A technique for microinjection into the bulbar structures of conscious rats was designed. An injection cannula was constructed from two units: a fine glass tube (0.14 mm o.d.) with a relatively large i.d. (0.08–0.12 mm) and a stainless steel holder that protects the glass tube from destruction when manipulated. The stainless steel holder was introduced into a guide cannula (0.60 mm o.d.) that had been stereotaxically implanted in the cerebellum so that the tip was located at a given distance (usually 4.0 mm) dorsal to the injection site, while the rat was gently restrained with one hand. The glass tube, previously calibrated, protruded at the set distance from the tip of the guide cannula and was inserted into the intended site only when the microinjection was given. By using such a fine glass tube, abnormal behavior was negated and the spread of drug solution along the space in the tissue made by pulling out the tube was limited. It was thus possible to give a localized and quantitative microinjection of 0.5 μl.     

Selection of test series by a modified multidimensional mapping method

Maintaining a realistic minimum distance between compounds in a defined multidimensional parameter space ensures well-spread sets of parameter values. It has been suggested, however, that the use of this multidimensional mapping method may lead to series of compounds with high multicollinearities of parameter values. An alternative method, multidimensional mapping by distance and determinant, is discussed here. This method maximizes the determinant of the interparameter correlation matrix as well as maintaining the minimum distance criterion. Its performance is compared with other methods, and it is shown that collinearities may be overcome or maintained at low levels when this method is used.