Ratiometric Interactions of Anionic Surfactants with Calf Thymus DNA Bound Cationic Surfactants: Study II

Cationic surfactant cetyltrimethylammonium bromide (CTAB) and cetylpyridinium bromide (CPB) bind to the calf thymus DNA (ct‐DNA) like anionic biopolymers electrostatically, and establish equilibrium in aqueous medium at pH 7. At low concentration, ct‐DNA does not interact with anionic surfactants, sodium dodecylsulfate (SDS) and sodium dodecylbenzylsulfonate (SDBS). However, in the ground state, anionic surfactant is found to clearly establish equilibrium with ct‐DNA‐bound cationic surfactant whereby the same surfactant–DNA isosbestic point reappears. We herein report a detail ratiometric binding of CPB with ct‐DNA, and interaction of anionic SDBS with DNA‐bound CPB in comparison with the combined ct‐DNA–CTAB–SDS system. Compaction of ct‐DNA in presence of CPB and its decompaction using anionic SDBS is also studied in comparison with CTAB–SDS combination. The techniques used are tensiometry, spectrophotometry, viscometry, cyclic voltammetry, circular dichroism, isothermal titration calorimetry, and density functional theory (DFT)‐based computational calculations. The size and surface charge density of the surfactant headgroups and the phosphate group in DNA have a contributing role in the DNA compaction–decompaction phenomenon.     

Muscle activity and cardiovascular response during computer-mouse work with and without memory demands

Computer-mouse work is characterized by repetitive movements combined with mental demands. The present purpose was to study how the body responded to simulated Computer Aided Design (CAD) work without memory demand and when a high short-term memory demand was introduced. Nine female subjects repetitively performed a task which involved 15 s of elevation of the right index and middle fingers followed by 6 s of rest. Every second time the fingers rested, the left index finger was required to type a six-figure number, either ‘123456’ (without memory demand) or a random number shown half a minute before (with memory demand). After 7 min of performing the task without memory demand, the memory demand was introduced and continued for 1 h. Introduction of memory demand resulted in increased heart rate (77 ← 84 beats/min), blood pressure (systolic 129 ← 140 mmHg; diastolic 72 ← 79 mmHg) and forearm extensor muscle activity (wrist, 2.7 ← 4.5% EMGmax; finger, 5.6 ← 7.5% EMGmax) and finger flexor muscle activity (0.7 1.2% EMGmax) indicating increased co-contraction. Hereafter, muscle activity and cardiovascular response tended to decrease. Self-reported stress and rating of perceived exertion (RPE) for the right shoulder increased throughout the period. Two additional sub-studies were inlcuded, which focused on adaptation to the physical load, showing a decrease in muscle activity and arousal, and reintroduction of the memory load, showing a lower response as compared to the initial response. The practical consequences of the findings suggest that job content should have variable mental demands.     

基于分布式结构的实时混合型播放算法

把周期性广播算法和批处理算法运用到分布式视频点播系统中,推导出实时混合型播放算法,新算法有效地解决了视频点播系统资源瓶颈问题;性能分析结果显示,新算法能够及时响应用户的请求,对客户端无存储要求,并且具有良好的效率、稳定性和扩展性。在当前带宽等资源相对匮乏及客户端无缓存的情况下,该文所述的播放算法是一个很好的选择。     

操作权限管理和控制在C＋＋Builder中的设计与实现

操作权限管理与控制是大多数计算机系统中的一个子系统,在保证整个系统正常、安全运行中起着重要的作用,该操作权限管理与控制子系统在作者使用C＋＋Builder开发的多个应用系统中已成功使用,效果很好。     

视频点播在网络应用中的问题及对策

通过对视频点播系统概念、原理、组成、功能和应用现状的介绍,分析了视频点播系统在实际应用中的前景及其存在的问题,并提出了解决问题的建议。     

Data center demand response: Avoiding the coincident peak via workload shifting and local generation

Demand response is a crucial aspect of the future smart grid. It has the potential to provide significant peak demand reduction and to ease the incorporation of renewable energy into the grid. Data centers’ participation in demand response is becoming increasingly important given their high and increasing energy consumption and their flexibility in demand management compared to conventional industrial facilities. In this paper, we study two demand response schemes to reduce a data center’s peak loads and energy expenditure: workload shifting and the use of local power generation. We conduct a detailed characterization study of coincident peak data over two decades from Fort Collins Utilities, Colorado and then develop two algorithms for data centers by combining workload scheduling and local power generation to avoid the coincident peak and reduce the energy expenditure. The first algorithm optimizes the expected cost and the second one provides a good worst-case guarantee for any coincident peak pattern, workload demand and renewable generation prediction error distributions. We evaluate these algorithms via numerical simulations based on real world traces from production systems. The results show that using workload shifting in combination with local generation can provide significant cost savings (up to 40% under the Fort Collins Utilities charging scheme) compared to either alone.     

Inventory management with log-normal demand per unit time

This paper examines optimal policies in a continuous review inventory management system when demand in each time period follows a log-normal distribution. In this scenario, the distribution for demand during the entire lead time period has no known form. The proposed procedure uses the Fenton-Wilkinson method to estimate the parameters for a single log-normal distribution that approximates the probability density function (PDF) for lead time demand, conditional on a specific lead time. Once these parameters are determined, a mixture of truncated exponentials (MTE) function that approximates the lead time demand distribution is constructed. The objective is to include the log-normal distribution in a robust decision support system where the PDF that best fits the historical period demand data is used to construct the lead time demand distribution. Experimental results indicate that when the log-normal distribution is the best fit, the model presented in this paper reduces expected inventory costs by improving optimal policies, as compared to other potential approximations.     

改进型遗传算法智能组卷系统的设计与实现

本文介绍了改进型遗传算法智能组卷系统的需求分析,然后根据分析结果来设计和实现具有良好的通用性和可扩展性一套智能组卷系统,其中组卷算法的关键点给出了具体的实现代码。     

不同单体浓度下三种聚季铵的合成及其性质

采用不同单体浓度制得了三种系列聚季铵(即季铵盐型阳离子聚合物):丙烯酰胺-二甲基二烯丙基氯化铵共聚物;丙烯酰胺-三甲基单烯丙基氯化铵共聚物和季铵化丙烯酸铵均聚物.研究了单体浓度对产物的阳离子度、分子量的影响.     

企业生产经营中的市场需求分析

本文论述了企业经济活动中的市场需求分析的概念及其三个层次，并着重讨论了模糊评判在企业市场占有率分析中的应用以及它们对企业生产经营决策的影响。