一个安全有效的有向门限签名方案

签名只有接受者才能验证,而任何第三方只有在接受者的合作下才能验证签名的数字签名方案称之为有向签名．而在大多数情况下,有向签名通常是一个人,然而当所需签名的消息代表一个群体时,就需要群体中的一部分人同意,门限签名方案就被用作解决这个问题．由于在许多特定的应用环境下,一个可被所有成员信任的可信中心并不存在,所以不需要可信中心的门限签名方案就显得很有吸引力．文章提供了一个安全有效的有向门限签名方案．     

Feedback Solution of a Class of Differential Games with Endogenous Horizons

In this paper, we consider a class of differential games in which the game ends when a subset of its state variables reaches a certain target at the terminal time. A special feature of the game is that its horizon is not fixed at the outset, but is determined endogenously by the actions of the players; conditions characterizing a feedback Nash equilibrium (FNE) solution of the game are derived for the first time. Extensions and illustrations of the derivation of FNE solutions of the game are provided.     

高效液相色谱法同时分离测定仁用杏花芽中8种植物激素

采用Shim-Park C18 VP-ODS色谱柱(150mm×4.6mm,5μm)、岛津SPD-10A VP UV-检测器,以V(甲醇)∶V(0.075%冰乙酸水溶液)=45∶55为流动相,在流速0.7mL/min、柱温30℃、检测波长254nm的条件下,同时分离测定了仁用杏花芽中的腺素、玉米素、赤霉素、生长素、6-苄氨基嘌呤、秋水仙素、脱落酸和吲哚-3-丁酸8种植物激素。各峰的分离效果理想,加标回收率达到95.41%~103.48%;测量灵敏度达0.0001volt;精密度RSD%<0.1。     

通信网络系统可信性测度模型

针对通信网络的安全性、可控性和可生存性的测度问题,采用连续时间多态有奖马尔可夫方法建立网络模型,定量分析其性能并构建可信性测度模型.提出了系统结构方程方法解决传统状态分析法中的"状态爆炸"问题.运用通用生成函数方法优化状态转换概率求解步骤,降低计算复杂度.实例仿真实验表明,计算模型正确、可行.     

Development and validation of an LC–MS/MS quantitative method for endogenous deoxynucleoside triphosphates in cellular lysate

The endogenous deoxynucleoside triphosphate (dNTP) pool includes deoxyadenosine triphosphate (dATP), deoxycytidine triphosphate (dCTP), deoxyguanosine triphosphate (dGTP) and thymidine triphosphate (TTP). The endogenous dNTP pool is regulated by complex enzymatic pathways that can be targeted by drugs, such as antimetabolites. In addition, these components compete with antiviral nucleos(t)ide analog triphosphates, contributing to the mechanism of pharmacologic action. This communication describes the development and validation of a sensitive method to quantify the intracellular dNTP pool in cellular lysates. The extraction process was optimized for dNTPs using an indirect strategy – the separation of mono‐, di‐ and triphosphate moieties by strong anion exchange, dephosphorylation of target fractions to molar equivalent nucleosides – followed by sensitive quantitation using liquid chromatography–tandem mass spectrometry. The validated analytical range was 50–2500 fmol/sample for each dNTP. The assay was used to quantify dNTPs in peripheral blood mononuclear cells from 40 clinical research participants (n = 279 samples). Median (interquartile range) concentrations were 143 (116, 169) for dATP, 737 (605, 887) for dCTP, 237 (200, 290) for dGTP and 315 (220, 456) for TTP, in femtomoles per million cells. This method allows for future studies of endogenous dNTP disposition in subjects receiving antimetabolites or nucleos(t)ide analogs, or for other clinical scenarios.     

Semiparametric estimation of average treatment effect through a random coefficient dummy endogenous variable model

This paper provides an estimation procedure for average treatment effect through a random coefficient dummy endogenous variable model. A leading example of the model is estimating the effect of a training program on earnings. The model is composed of two equations: an outcome equation and a decision equation. Given the linear restriction in outcome and decision equations, Chen (1999) provided a distribution-free estimation procedure under conditional symmetric error distributions. In this paper we extend Chen’s estimator by relaxing the linear index into a nonparametric function, which greatly reduces the risk of model misspecification. A two-step approach is proposed: the first step uses a nonparametric regression estimator for the decision variable, and the second step uses an instrumental variables approach to estimate average treatment effect in the outcome equation. The proposed estimator is shown to be consistent and asymptotically normally distributed. Furthermore, we investigate the finite performance of our estimator by a Monte Carlo study and also use our estimator to study the return of college education in different periods of China. The estimates seem more reasonable than those of other commonly used estimators.     

风险内生的委托代理模型研究

证券投资基金的委托代理关系与一般的委托代理关系不同,在一般的委托代理关系中,产出的风险是外生的,而基金产出的风险是内生的,即风险是由基金管理人来选择的.在模型假设的背景下,在不考虑基金管理人的努力成本时,基金委托代理关系中不存在道德风险问题.如果考虑基金管理人的努力成本,当其行为不可观测时,基金投资者无法通过契约参数的变化来影响基金管理人的努力水平,但此时投资组合的风险水平将低于基金管理人行为可观测时的情况.实证研究证实了基金收益分享比例与基金管理人努力程度无关的模型推论.     

基于信任扩展的可信虚拟执行环境构建方法研究

为保护虚拟机运行环境及上层服务软件的完整性、安全性,提出了一种基于信任扩展的可信虚拟执行环境的构建方法.首先,建立物理平台配置寄存器(PCR,platform configuration register)与虚拟PCR的映射关系,以此实现虚拟可信平台模块(vTPM)与底层可信计算基的绑定;其次,利用本地vTPM管理器签...     

基于TPM的可信集群系统设计与实现

集群系统既有分布式系统的特点,又有单一系统的特征。由于传统集群计算节点缺少可信计算平台的支持,集群作为一个单一的系统缺少可信安全技术的支持。作为一个分布式系统,其可信安全机制和信任链传递机制又很不同于单机系统。在TCG可信计算的规范和可信链的基础之上,提出了可信集群的构架,构建了基于TPM的可信集群,实现了基于可信集群架构的可信集群系统。针对集群中的应用,对所实现的可信集群系统如何解决集群中的可信安全问题作了探讨和研究。     

The Anti-Tumor Effect and Underlying Apoptotic Mechanism of Ginsenoside Rk1 and Rg5 in Human Liver Cancer Cells

Ginsenoside Rk1 and Rg5 are minor ginseng saponins that have received more attention recently because of their high oral bioavailability. Each of them can effectively inhibit the survival and proliferation of human liver cancer cells, but the underlying mechanism remains largely unknown. Network pharmacology and bioinformatics analysis demonstrated that G-Rk1 and G-Rg5 yielded 142 potential targets, and shared 44 putative targets associated with hepatocellular carcinoma. Enrichment analysis of the overlapped genes showed that G-Rk1 and G-Rg5 may induce apoptosis of liver cancer cells through inhibition of mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) signal pathways. Methyl thiazolyl tetrazolium (MTT) assay was used to confirm the inhibition of cell viability with G-Rk1 or G-Rg5 in highly metastatic human cancer MHCC-97H cells. We evaluated the apoptosis of MHCC-97H cells by using flow cytometry and 4′,6-diamidino-2-phenylindole (DAPI) staining. The translocation of Bax/Bak led to the depolarization of mitochondrial membrane potential and release of cytochrome c and Smac. A sequential activation of caspase-9 and caspase-3 and the cleavage of poly(ADP-ribose) polymerase (PARP) were observed after that. The levels of anti-apoptotic proteins were decreased after treatment of G-Rk1 or G-Rg5 in MHCC-97H cells. Taken together, G-Rk1 and G-Rg5 promoted the endogenous apoptotic pathway in MHCC-97H cells by targeting and regulating some critical liver cancer related genes that are involved in the signal pathways associated with cell survival and proliferation.