非拦截式弱束流剖面测量方法的研究----剩余气体束流剖面探测系统的研制

随着加速器束流诊断技术的不断发展，非拦截式束流测量方法及弱束流诊断技术在加速器领域被广泛应用。为了跟踪国际上加速器技术研究前沿，配合HIRFL改造，以满足CSR大科学工程对HIRFL束流品质及调束效率提出的更高要求，本论文开展了弱束流测量方法的研究和一种新型的非拦截式束流位置及剖面探测装置的研制。论文中简要概述了国际国内加速器束流诊断技术的发展现状以及非拦截式弱束流测量技术在加速器中的应用，调研了国际上研制的利用剩余气体获取束流参数的各种束诊设备，为开展本课题的研究奠定了理论基础；论文中重点论述了研制剩余气体束流剖面探测系统的工作原理，利用平行板电极形成的均匀电场收集束流与剩余气体分子碰撞时产生的剩余气体正离子，通过微通道板与连续型电阻阳极构成的位置灵敏探测器将剩余气体正离子放大、读出，最终获得束流位置及剖面等参数；详细介绍了剩余气体束流剖面测量系统的设计，包括机械装置和信号获取系统，机械部分主要由真空测量室、平行板式高压电极和位置灵敏探测器组成，获取系统由电荷灵敏前置放大器、主放大器、加法器、位置灵敏分析器、计算机多道分析系统及符合电路组成；最后给出了离线和在线测试实验分析结果。本论文主要基于剩余气体电离理论，以非拦截式束流探测技术为主导思想，从理论上分析了利用剩余气体测量束流位置及束流剖面的可行性，首次在国内加速器领域研制出剩余气体束流剖面探测装置，并将其应用于重离子加速器实验，初步实验结果证明系统设计结构合理，测量灵敏度，位置分辨及线性基本达到了系统设计要求。本课题的研究无论是对于HIRFL非拦截诊断技术的扩展，还是对于HIRFL-CSR束诊系统的发展都具有深远意义。

A strategy for constructing a hybrid bilayer membrane based on a carbon substrate

We construct a hybrid bilayer membrane (HBM) on a new substrate-carbon electrode. It is an extension of HBM based on other substrates. Primary alkylamine was chemically modified onto the surface of a carbon electrode by electrochemical scans; thus, a monolayer was formed on the electrode. Because the alkane chains section is toward the outside, a hydrophobic surface was constructed. Then a lipid monolayer was spread on the hydrophobic surface of the carbon electrode. The formed HBM was characterized by electrochemical and ATR-FT-IR methods. From ATR-FT-IR results, the lipid order parameter (S) of 0.73 was obtained. This kind of hybrid membrane has the advantages of a lipid/alkanethiol HBM. A potential application of this HBM as a biosensor (detecting K+) was given.

基于神经网络的永磁同步电机矢量控制

采用单神经元自适应PID控制器对永磁同步电机进行了调速控制。详细介绍了PMSM(PermanentMagnetSynchronousMotor)的矢量控制原理。最后给出PMSM单神经元自适应PID控制的仿真结果和硬件实现方法。仿真结果表明,该系统具有良好的动态性能。

Recovering Heading for Visually-Guided Navigation

We present a model for recovering the direction of heading of an observer who is moving relative to a scene that may contain self-moving objects. The model builds upon an algorithm proposed by Rieger and Lawton (1985), which is based on earlier work by Longuet-Higgens and Prazdny (1981). The algorithm uses velocity differences computed in regions of high depth variation to estimate the location of the focus of expansion, which indicates the observer's heading direction. We relate the behavior of the proposed model to psychophysical observations regarding the ability of human observers to judge their heading direction, and show how the model can cope with self-moving objects in the environment. We also discuss this model in the broader context of a navigational system that performs tasks requiring rapid sensing and response through the interaction of simple task-specific routines.

The cost of biopharmaceutical R&D: Is biotech different?

The costs of developing the types of new drugs that have been pursued by traditional pharmaceutical firms have been estimated in a number of studies. However, similar analyses have not been published on the costs of developing the types of molecules on which biotech firms have focused. This study represents a first attempt to get a sense for the magnitude of the R&D costs associated with the discovery and development of new therapeutic biopharmaceuticals (specifically, recombinant proteins and monoclonal antibodies [mAbs]). We utilize drug-specific data on cash outlays, development times, and success in obtaining regulatory marketing approval to estimate the average pre-tax R&D resource cost for biopharmaceuticals up to the point of initial US marketing approval (in year 2005 dollars). We found average out-of-pocket (cash outlay) cost estimates per approved biopharmaceutical of $198 million, $361 million, and $559 million for the preclinical period, the clinical period, and in total, respectively. Including the time costs associated with biopharmaceutical R&D, we found average capitalized cost estimates per approved biopharmaceutical of $615 million, $626 million, and $1241 million for the preclinical period, the clinical period, and in total, respectively. Adjusting previously published estimates of R&D costs for traditional pharmaceutical firms by using past growth rates for pharmaceutical company costs to correspond to the more recent period to which our biopharmaceutical data apply, we found that total out-of-pocket cost per approved biopharmaceutical was somewhat lower than for the pharmaceutical company data ($559 million vs $672 million). However, estimated total capitalized cost per approved new molecule was nearly the same for biopharmaceuticals as for the adjusted pharmaceutical company data ($1241 million versus $1318 million). The results should be viewed with some caution for now given a limited number of biopharmaceutical molecules with data on cash outlays, different therapeutic class distributions for biopharmaceuticals and for pharmaceutical company drugs, and uncertainty about whether recent growth rates in pharmaceutical company costs are different from immediate past growth rates. Copyright © 2007 John Wiley & Sons, Ltd.

Entry and competition in generic biologics

Patents for several blockbuster biological products are expected to expire soon. The Food and Drug Administration is examining whether biologies can and should be treated like pharmaceuticals with regard to generics. In contrast with pharmaceuticals, which are manufactured through chemical synthesis, biologies are manufactured through fermentation, a process that is more variable and costly. Regulators might require extensive clinical testing of generic biologies to demonstrate equivalence to the branded product. The focus of the debate on generic biologies has been on legal and health concerns, but there are important economic implications. We combine a theoretical model of generic biologies with regression estimates from generic pharmaceuticals to estimate market entry and prices in the generic biologic market. We find that generic biologies will have high fixed costs from clinical testing and from manufacturing, so there will be less entry than would be expected for generic pharmaceuticals. With fewer generic competitors, generic biologies will be relatively close in price to branded biologies. Policy makers should be prudent in estimating financial benefits of generic biologies for consumers and payers. We also examine possible government strategies to promote generic competition. Copyright © 2007 John Wiley & Sons, Ltd.

Making the link: a customised social networking site can foster learning

Thanks to the internet, students today can do things that students of the past could not. They can learn formally or informally by interacting on social networking sites in a way that is not easily accomplished in a lecture theatre or classroom.

Drug calculations part 2: alternative strategies to the formula

Drug calculations are an essential skill for nurses. The clinical skill of performing a drug calculation has come under recent scrutiny,resulting in the development of essential skills clusters inwhich pre-registration nurses must be competent before qualifying (Nursing and Midwifery Council 2007). The focuson drug calculation skills places renewed emphasis on how these skills are taught in higher education institutions and how they are learned by students theoretically and in clinical practice.

Drug calculations part 1: a critique of the formula used by nurses

The role of mathematics is integral to nursing practice, and careful and accurate calculations are important to help prevent medication errors. This two-part article examines different methods for solving drug calculation problems. The first part critiques the commonly taught nursing drug calculation formula. Part 2, to be published next week, explores a range of other methods that are used in practice to calculate drug dosages.

Theory and practice of manual blood pressure management

This article outlines the process of taking a manual blood pressure measurement. The author suggests that it is a skill that nursing students should be using in clinical practice rather than relying on automated monitors.

Characteristics of people who assault nurses in clinical practice

This article discusses certain variables relating to the characteristics of people who assault nurses, including patients, relatives and friends. The author suggests that the nature of nurses' occupational roles and responsibilities puts them at risk in their work but that individual or organisational strategies can be developed to minimise this risk.

Factors that influence aggressive behaviour in acute care settings

Patients with critical illness or severe trauma may feel fear, anxiety and powerlessness, which can lead to aggressive behaviour. This article examines factors that contribute to patient aggression in acute care areas and identifies how these incidents can be minimised.