Agent技术在Web服务中的应用探讨

Web服务是一组采用面向服务的体系架构的基于标准的Web协议的软件构件,而Agent是一种在某个环境中自主行动以实现其设计目标的智能化软件实体.Web服务与多Agent系统(MAS,Multi-Agent System)在架构、范例和技术方法等方面具有很大的相似性.Web服务的可信性是未来计算机软件发展关键的问题,实现Web服务在分布式环境下的协同式测试具有一定的挑战性.本文在探讨Web服务与Agent技术的共性的基础上,分析并总结了Agent技术在Web服务中的应用.针对Web服务测试的开放性、协同性、动态性和不确定性等特点,结合Agent系统的自主性、反应性、适应性和社会性,本文提出了一种基于MAS的Web服务测试框架(MAST,Multi-Agent-based Service Testing),并对其关键技术进行了探讨.     

动静态信息相结合的UML2.0序列图逆向生成方法

符合UML2.0标准的序列图在UMLl.x序列图的基础上添加了控制流信息.为此,本文提出一种基于动静态信息相结合的UML2.0序列图逆向生成方法.该方法首先利用目标程序运行时的动态信息产生基本的方法调用序列,然后依据静态的程序依赖图对其进行补充和调整,在其上添加方法间的逻辑关系,使产生的序列图带有控制流信息.这种方法生成的序列图符合UML2.0标准,可以很好地辅助用户理解目标程序.     

多Agent信息系统知识发现研究

本文根据信息系统的定义,提出了采用集合方法描述的多Agent信息系统,研究了在多Agent交互中规则的形成过程.对规则表示和存储方法进行了研究.鉴于各Agent的规则可存储在数据库中,采用ID3算法对这些规则进行挖掘是可行的.对该方法用实例进行了验证.     

基于免疫Agent的网络入侵检测系统

结合计算机免疫学原理和多Agent 技术构建了一个网络化、分布式、智能化的入侵检测系统,该系统融合了两者的优势,同时继承了多Agent系统和免疫系统的优点.其特点是能同时进行多层次的监测和不同级别的响应.系统是完全分布式结构,监视Agent生成后在网络上漫游,各个Agent分布在网络的各个结点上,单个结点受到攻击不会影响其他结点的检测能力,避免了单点失效问题.将疫苗概念引入系统,使得各个Agent可以实现互相学习,增强了整个网络的耐受性、"记忆"机制及新抗体生成机制的能力,提高了系统的适应性,不仅能检测到已知的攻击,而且还能检测到未知的攻击.     

电子商务中基于社会交换的谈判

以Agent为中介的电子商务研究忽略了社会关系等社会因素对Agent的谈判的影响.本文在分析价值交换和相应的谈判过程中的社会关系基础上,将基于社会关系的谈判与一种扩展价值交换相联结,提出了一种基于价值交换的谈判的理论框架及其实现机制.     

基于TPM硬件的移动Agent安全模型研究

主要讨论了安全强度较高的基于硬件的移动Agent安全方案.将可信计算技术与平台引入移动Agent的安全机制,基于可信硬件TPM所提供的相关安全服务实现移动Agent的主动保护机制.设计了在可信硬件平台上的移动Agent安全框架模型并进行了详细分析.     

网格环境下基于移动Agent的教育资源发现研究

本文使用教育元数据描述规范LOM(Learning Object Management)描述教育资源,并结合移动Agent技术,提出了一种网格环境下基于移动Agent的教育资源发现模型,阐述了教育资源发现过程,并对相关问题进行了讨论.     

基于SVM的多Agent信息融合算法

支持向量机(SVM)是一种基于结构风险最小化原理、具有很高泛化性能的学习算法,为小样本、非线性、高维数一类信息融合问题的建模提供了一种有效的途径.本文将Mobile Agent运用到信息融合系统中,对信息融合系统中原有OODA模型进行改进,提出了一种基于SVM的Mobile Agent信息融合模型及算法.相关实验表明,本文中的训练算法可达到更为满意的分类效果,并且可以得到较高的分类精度.     

基于ORD和FSM的Web应用的建模与测试

Web测试是保证高质量Web应用的一种有效技术.然而,由于其特殊性和复杂性,很难直接将传统的测试理论与方法学运用到Web应用的测试当中来.对Web应用进行了分析与建模,并对其进行测试,提出了一种可行的Web测试模型.首先得到页面流图(PFD,Page Flow Diagram),进而产生对象关系图(ORD,Object Relation Diagram),然后根据提出的算法将ORD转化为形式化的有限状态机(FSM,Finite State Machine)模型.基于FSM模型,提出了一种有效的测试路径自动生成方法,这些测试路径可以转化为XML语法的测试规格说明.测试引擎将测试规格说明作为输入最终产生测试报告.全文以所开发的一个小型的Web应用SWLS(Simple Web Login System)为例进行阐述.     

多Agent CRM系统模型及其协同通信研究

客户关系管理(CRM)是企业赢得竞争优势的重要手段.本文研究了多Agent的CRM系统模型系统内和系统外Agent间的通信与交互问题,对现在客户关系管理产品服务过程自动化以及系统各功能模块协同能力进行了改进,为改善现有客户关系管理产品提供了一种新的手段.     

Concern-driven integrated approaches to nanomaterial testing and assessment – report of the NanoSafety Cluster Working Group 10

Bringing together topic-related European Union (EU)-funded projects, the so-called “NanoSafety Cluster” aims at identifying key areas for further research on risk assessment procedures for nanomaterials (NM). The outcome of NanoSafety Cluster Working Group 10, this commentary presents a vision for concern-driven integrated approaches for the (eco-)toxicological testing and assessment (IATA) of NM. Such approaches should start out by determining concerns, i.e., specific information needs for a given NM based on realistic exposure scenarios. Recognised concerns can be addressed in a set of tiers using standardised protocols for NM preparation and testing. Tier 1 includes determining physico-chemical properties, non-testing (e.g., structure–activity relationships) and evaluating existing data. In tier 2, a limited set of in vitro and in vivo tests are performed that can either indicate that the risk of the specific concern is sufficiently known or indicate the need for further testing, including details for such testing. Ecotoxicological testing begins with representative test organisms followed by complex test systems. After each tier, it is evaluated whether the information gained permits assessing the safety of the NM so that further testing can be waived. By effectively exploiting all available information, IATA allow accelerating the risk assessment process and reducing testing costs and animal use (in line with the 3Rs principle implemented in EU Directive 2010/63/EU). Combining material properties, exposure, biokinetics and hazard data, information gained with IATA can be used to recognise groups of NM based upon similar modes of action. Grouping of substances in return should form integral part of the IATA themselves.     

Solution behavior of IFN-beta-1a: an empirical phase diagram based approach

An empirical phase diagram approach has been developed as a practical tool to aid macromolecular preformulation/formulation studies. This method employs an eigenvector based procedure to visualize and interpret complex data sets. Human Inteferon-beta-1a, an important therapeutic protein, was used to further develop the method and test its utility. The protein was characterized in solution as a function of pH (2-8), temperature (10 degrees C-85 degrees C) and ionic strength (I = 0.1 and 1.0) using intrinsic and ANS fluorescence, Far-UV circular dichroism (Far-UV CD), Fourier Transform Infrared spectroscopy (FTIR) and derivative UV absorbance spectroscopies, as well as differential scanning calorimetry (DSC) to supplement spectroscopic thermal stability studies. Derivative UV absorbance data were initially used to construct a pH-temperature phase diagram at each ionic strength. Three distinctive phases at I = 0.1 and two major phases at I = 1.0 were identified corresponding to different conformation/aggregation states of the protein. For the first time, heterogeneous data sets (i.e., data from different techniques) including Far-UV CD, fluorescence and UV absorbance results were used to generate empirical phase diagrams. Results from different data sets are compared; precautions in applying the method and its overall utility are discussed.     

Biophysical characterization of polymeric and liposomal gene delivery systems using empirical phase diagrams

A major problem with the pharmaceutical use of nonviral gene delivery systems arises from their limited characterization due to their size and heterogeneity. In this study, we provide a more intuitive view of their structure and behavior employing an empirically based phase diagram approach. Complexes formed between plasmid DNA and four cationic carriers (a monovalent lipid, the same monovalent lipid combined with a helper lipid, polylysine, and a branched form of polyethyleneimine), at both positive and negative nitrogen/phosphorous ratios, are characterized employing dynamic light scattering, circular dichroism, and extrinsic dye fluorescence as methods sensitive to various aspects of the structure of the complexes. These measurements were performed as a function of pH and ionic strength to perturb the electrostatic contacts that are key to complex formation. Using a multidimensional eigenvalue approach, the data are presented in the form of a colored, five dimensional diagram. The resultant eight empirical phase diagrams display three to five variably resolved phases. In contrast, the phase diagram of the plasmid alone showed only two to three such phases. Each state is assigned to a particular form of the complex in terms of their size, extent of collapse and conformation of the associated DNA component. The utility of this approach is then briefly discussed.     

ASRSP——一种新的并发程序测试准则

可达性测试是目前较为成熟的一种并发程序测试方法,该方法解决了如何生成最小完备偏序测试序列集的问题.但研究表明,对于一般规模的并发程序,这一测试序列集仍然太大,以至穷尽测试无法完成.因此,目前亟需能投入实际应用的并发程序测试准则和相应的测试序列生成算法.本文提出了一种实用性较高的并发程序测试准则:全发送接收语句对(ASRSP),并针对该准则提出了一种新的并发程序测试方法:全发送接收语句对可达性测试(ASR-SP-RT).该方法利用可达性测试生成测试序列集的完备性来保证覆盖所有的发送接收语句对,并在每次生成新序列 之后及时去掉对覆盖剩下发送接收语句对无作用的序列,从而达到约简测试序列集的目的.     

Equivalence Testing for Parallelism in the Four-Parameter Logistic Model

For assay or dose-response data in drug discovery, it is often important to test for parallelism of the response curves for two preparations, such as a test drug and a standard drug, in order to determine the potency of the test preparation relative to the standard preparation. A typical approach is to perform a three-degree of freedom approximate F test of the null hypothesis that the relevant parameters are equal for the two preparations. We argue that this problem may be more appropriately viewed as a practical equivalence testing problem, and present an alternative method for testing parallelism in the four-parameter logistic response curve, based on the theory of intersection–union tests. The approach is intuitively appealing and simple to implement using commonly available software, and may provide more appropriate inference for the problem of interest. Two examples are discussed to illustrate the testing approach outlined in this article, and to compare it with the typical approach to testing parallelism. A simulation study is also presented to compare the empirical properties of the two different testing approaches for a set of cases based approximately on one of the examples.     

Long-term evaluation of organophosphate toxicity and antidotal therapy in co-cultures of spinal cord and muscle tissue

Victims of nerve agents basically require antidotal treatment. There is need for novel antidotes and for therapeutic procedures that are specifically adapted to these patients. To cope with this challenge, in vitro test systems which are easy to handle and allow for conducting long-term studies would be of great benefit. The present work introduces co-cultures of spinal cord and muscle tissue as ex vivo testing systems meeting these criteria. Cell cultures in which functional neuromuscular synapses formed ex vivo were prepared from embryonic mice. Spontaneous muscle activity was recorded by video microscopy. Muscle contractions involved intact neuromuscular transmission as indicated by the effect of succinylcholine, a muscle relaxant that completely abolished muscle activity. At a concentration of 0.75 μM the nerve agent VX reduced the frequency of spontaneous muscle contractions by about 75%. Subsequent application of obidoxime re-established muscle movements. After 24 h of antidotal treatment, muscle activity approached the level of sham-treated cultures and remained stable over the following week. In summary, co-cultures of spinal cord and muscle tissue are promising tools for evaluating the success of antidotal treatment following organophosphate intoxication over a period of at least seven days.     

Neuromuscular blockade,reversal agent use,and operating room time: retrospective analysis of US inpatient surgeries

ABSTRACT

Purpose: Reducing operating room (OR) time is of interest to hospital administrators because of high costs of OR utilization. Neuromuscular blocking agents (NMBAs) induce muscle relaxation during surgery. Several acetylcholinesterase inhibitors are used to reverse neuromuscular blockade to shorten recovery time. This study explored the relationship between elapsed OR time and the use of specific NMBAs and reversal agents among patients undergoing selected surgeries based on data from two large hospitals. Specifically, this study sought to test the hypothesis that the application of reversal agents in surgeries using a neuromuscular block would be associated with a decrease in elapsed OR time.

Methods: This retrospective cohort study used clinical data from two large hospitals. The authors selected seven types of surgical cases involving thoracic, cardiac, vascular, abdominal, peripheral, urological, and neurological systems. Eligible cases were elective surgeries performed under general anesthesia and using one or more NMBAs (including rocuronium, vecuronium, cisatracurium, and/or pancuronium). Multivariate linear regressions were conducted to examine the relationships among neuromuscular blockade, reversal agent use (including neostigmine, pyridostigmine, and edrophonium), and elapsed OR time by controlling for age, gender, and patient comorbidities.

Results: A total of 9670 surgeries were included in this analysis. The mean elapsed OR time across all surgeries was 227?min, and vecuronium was the most commonly used NMBA. Approximately 67% of all surgeries used a reversal agent. After controlling for confounding factors, use of a reversal agent was shown to be associated with the reduction of elapsed OR time in six of seven types of surgery. The magnitude of this effect ranged from 12 to 46?min of OR time saved. The exception was thoracic surgeries, for which use of a reversal agent was shown to be associated with longer OR time (approximately 26?min). Multivariate regression analyses revealed that the type of NMBA used was also a significant predictor of elapsed time for all surgeries (except cardiac).

Conclusions: This analysis has shown that use of selected neuromuscular blockade reversal agents may lead to more efficient OR resource use.     

Cardiac sensitization: methodology and interpretation in risk assessment

An increased sensitivity of the heart to endogenous epinephrine (adrenaline), a phenomenon referred to as cardiac sensitization, has long been recognized as a risk during exposure to hydrocarbons, principally halogenated hydrocarbons. Cardiac sensitization, which can result in serious arrhythmia and death, requires a certain critical blood level of both the sensitizing agent and epinephrine. The original research and methods utilized an exogenous epinephrine challenge during inhalation exposure to a chemical to assess cardiac sensitization potential in Beagle dogs. These screening tests were developed about 30 years ago, although in the last 15 years some modifications of these methods have occurred in response to testing chlorofluorocarbon (CFC) replacements. Results from these experimental cardiac sensitization studies have been used for semi-quantitative risk evaluation for occupational exposures but now are being used more quantitatively for regulatory purposes. The risks associated with cardiac sensitization from CFC replacements are unknown but expected to be low based on cardiac sensitization studies in the 1970s where dogs were made to generate their own adrenaline. With the advent of physiologically based pharmacokinetic (PBPK) modeling, greater emphasis is being placed on quantitative risk assessment for cardiac sensitization. In this investigation, we have examined the various methodologies used for detection of cardiac sensitization and discussed their limitations and advantages. In addition, we examined the potential concerns involved in using experimental cardiac sensitization data and PBPK modeling to predict exposure scenarios.     

Sterility testing of antimicrobial-containing injectable solutions prepared in the pharmacy.

The need for sterility testing of antimicrobial-containing injectable solutions is discussed and specific testing methods are described. Despite their antimicrobial activity, antimicrobial-containing injectable drug products are not necessarily self-sterilizing and can become contaminated. In addition to practicing aseptic technique, pharmacists must perform end-product sterility testing on intravenous solutions to ensure their sterility. The United States Pharmacopeia provides guidelines for the performance and validation of two sterility test methods: membrane filtration and direct transfer to culture media. Membrane filtration is the method of choice for sterility testing of many antimicrobial-containing injectable solutions. After the test article is filtered, the membrane is rinsed with sterile fluid to remove residual antimicrobial agent, cut into two portions, and immersed in two types of culture medium. Visible turbidity of a sample within the appropriate incubation period indicates the presence of a contaminating microorganism. Closed filtration systems minimize false-positive results. In the direct transfer method, samples of the test article are directly inoculated into vessels of culture media, and antimicrobial activity is eliminated by dilution or by deactivation with chemical or enzymatic agents. Sterility testing as well as aseptic technique is needed to ensure the sterility of antimicrobial-containing injectable solutions.     

Statistical analysis of skin tumor data from Tg.AC mouse bioassays.

New strategies for identifying chemical carcinogens and assessing risk have been proposed based on the Tg.AC (zetaglobin promoted v-Ha-ras) transgenic mouse. Preliminary studies suggest that the Tg. AC mouse bioassay may be an effective means of quickly evaluating the carcinogenic potential of a test agent. The skin of the Tg.AC mouse is genetically initiated, and the induction of epidermal papillomas in response to dermal or oral exposure to a chemical agent acts as a reporter phenotype of the activity of the test chemical. In Tg.AC mouse bioassays, the test agent is typically applied topically for up to 26 weeks, and the number of papillomas in the treated area is counted weekly. Statistical analyses are complicated by within-animal and serial dependency in the papilloma counts, survival differences between animals, and missing data. In this paper, we describe a statistical model for the analysis of skin tumor data from a Tg.AC mouse bioassay. The model separates effects on papilloma latency and multiplicity and accommodates important features of the data, including variability in expression of the transgene and dependency in the tumor counts. Methods are described for carcinogenicity testing and risk assessment. We illustrate our approach using data from a study of the effect of 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD) exposure on tumorigenesis.