Center of mass energy and system-size dependence of photon production at forward rapidity at RHIC

We present the multiplicity and pseudorapidity distributions of photons produced in Au + Au and Cu + Cu collisions at root(NN)-N-s = 62.4 and 200 GeV. The photons are measured in the region -3.7 < eta < -2.3 using the photon Multiplicity detector in the STAR experiment at RHIC. The number of photons produced per average number of participating nucleon pairs increases with the beam energy and is independent of (lie collision centrality. For collisions with similar average numbers of participating nucleons the photon multiplicities are observed to be similar for An + Au and Cu + Cu collisions at a given beam energy. The ratios of the number of charged particles to photons in the measured pseudorapidity range are found to be 1.4 +/- 0.1 and 1.2 +/- 0.1 for root(NN)-N-s = 62.4 and 200 GeV, respectively. The energy dependence of this ratio could reflect varying contributions from baryons to charged particles, while mesons are the dominant contributors to photon production in the given kinematic region. The photon pseudorapidity distributions normalized by average number of participating nucleon pairs, when plotted as a function of eta-Y-beam, are found to follow a longitudinal scaling independent of centrality and colliding ion species at both beam energies. (C) 2009 Elsevier B.V. All rights reserved.

等时性回旋加速器的理论与设计

本论文比较系统地介绍了等时性回旋加速器的理论，并以兰州重离子加速器系统的注入器SFC和主加速器SSC两台等时性回旋加速器为例介绍该类型加速器的设计特点和设计方法，以及作者在这两台加速器上所做的一些具体设计和改进工作。 首先一般性地介绍加速器尤其是回旋加速器在原子核物理及粒子物理中的作用以及在其它应用学科中的作用，加速器学科尤其是回旋加速器的发展水平和发展趋势。在第二章中给出经典回旋加速器和等时性回旋加速器的理论基础，包括等时性加速原理，轴向聚焦和径向聚焦的稳定加速条件以及由扇块产生的方位角调变磁场提供的轴向聚焦力，径向运动稳定区和共振理论，和加速平衡轨道理论。从第三章到第五章，从等时场的建立，注入系统及引出系统等比较具体的方面来阐述该类型加速器的理论和各种实现方法。第三章介绍GORDON理论和Kb——Kr两种比较常见的理论等时场的建立方法，磁铁和线圈的设计和作用，以及磁场的测量。还介绍了对实际等时性磁场的评价以及通过对束流相位的测量来反映实际等时场的作用和对等时场的再优化等方法。在第四章中，系统地介绍了利用外离子源或利用其它加速器作为注入器时通常采用轴向或者径向注入方法。注入引出系统尤其是注入系统通常是影响一台加速器传输效率的关键性部分，因而在如何提高注入系统的效率方面人们做了大量的工作，特别是轴向注入方法。回旋加速器的中心区是注入的结束和正常加速过程的开始，其设计的好坏对注入效率和后面的束流轨道也是很重要的。第五章在讨论束流从加速器中的引出时，主要强调束流用户或后级加速器对引出束流品质的要求以及引出效率，因而强调了较高的内束流质量和单圈引出的重要性，以及提高引出点的圈距的具体的方法如提高加速圈距、共振进动和非共振进动方法。引出路径上的束流聚焦也是引出系统设计应考虑的一个方面。另外还介绍了再生引出和剥离膜引出方法。在这几章中不仅介绍了回旋加速器的理论，通常从Hamilton方法出发，而且还介绍了进行实际加速器设计中常用的束流轨道数值计算方法。但前者在理解加速器的物理图像方法以及在设计初期对某些重要的参数的评价和估计方面是很必要的。在介绍等时性回旋加速器的理论和设计方法的同时还以SFC和SSC两台回旋加速器和它们的分系统的具体设计为例子作了比较详细的实际应用对照。 论文的最后部分，即第六章是介绍作者自己在回旋加速器的理论和设计方面的部分工作，为了保持整篇论文的协调一致，没有将在国外所做的工作列入，只编入了在HIRFL上进行的直接与回旋加速器的物理设计有关的工作： ① 作者提出的一种新的等时场垫补和优化方法，该方法利用回旋加速器垫补线圈的磁场贡献具有台阶性的特点，对垫补或优化区域采取从小半径到大半径或反过来逐步垫补的方法，它既适用于紧凑式回旋加速器也适用于分离扇回旋加速器，它具有直观性和可对垫补及优化过程进行直接干预的特点。 ② 对SFC的轴向注入系统进行了改进设计，新的注入系统配备两台在线ECR离子源并加强和增加了注入束运线的功能，如增加了离子源的电荷态分析能力，束流发射度的限制功能、进行发射度测量和束流状态的监测功能等等。新的注入系统还提高了三次谐波加速情况下的注入电压以减小空间电荷效应的影响。相比原系统新的轴向注入束运系统有更高的注入效率，更好的调束手段和更好的空间安排。 ③ 对SFC轴向注入束运线的聚束器系统进行了重新设计，用二台分别工作再SFC采用基波加速模式和三次谐波加速模式下的不同聚束器结构代替原来的一台聚束器，以适应SFC较宽的加速粒子和能量范围，并提高了聚束器本身的指标，可以明显地提高轴向注入系统的传输效率和SFC的内束流质量，同时该聚束器系统还采用了新的半频聚束模式，在不影响SFC的效率和束流质量的情况下可以将SFC与SSC的理论纵向匹配效率由原设计的50%提高到100%。 ④ 对SFC加速器的中心区进行了改进设计，配合轴向注入系统将三次谐波加速时的注入半径由2.5cm提高到3.0cm，使加速较重的重离子的条件得到改善，并保留基波加速时2.5cm的注入半径，即新的中心区要适应两套注入参数，每次仅更换新的螺旋线型静电偏转镜。新的中心区还照顾到SFC高频DEE电压在某些情况下偏低的不足。 ⑤ 在对HIRFL加速器系统进行了全面的分析后，提出了一系列的提高其束流指标和运行效率的改进措施，作为进一步工作的方向，并给出了在完成目前正在进行的改进工作后和2000年前后HIRFL可能达到的束流指标。 在附录中一般性地介绍了Hamilton分析力学和带电粒子束的相空间理论，在讨论了束流动力学研究中经常用到的传输矩阵方法和轨迹跟踪方法。在附录二中介绍了加速器用的多电荷态离子源的情况，尤其是以ECR离子源为代表的高电荷重离子源的情况。

Pressure-dependent glass-transition temperatures of poly(methyl methacrylate)/poly(styrene-co-acrylonitrile) blends

The pressure-dependent glass-transition temperatures (T-g's) of poly(methyl methacrylate) (PMMA)/poly(styrene-co-acrylonitrile) (SAN) blends were determined by pressure-volume-temperature (PVT) dilatometry via an isobaric cooling procedure. The Gordon-Taylor and Fox equations were used to evaluate the relationships between the T-g's and compositions of the PMMA/SAN system at different pressures. The relationships were well fitted by the Gordon-Taylor equation, and the experimental data for T-g positively deviated from the values calculated with the Fox equation. Also, the influence of the cooling rate (during the PVT measurements) on T-g was examined.

Effects of molecular weight and interaction parameter on the glass transition temperature of polystyrene mixtures and its blends with polystyrene/poly(2,6-dimethyl-p-phenylene oxide)

The glass transition temperature (T-g) of mixtures of polystyrene (PS) with different molecular weight and of blends of poly(2,6-dimethyl-p-phenylene oxide) (PPO) and polystyrene with different molecular weight (DMWPS) was studied by a DSC method. For the whole range of composition, the curves of T-g vs composition obtained by experiment were compared with predictions from the Fox, Gordon-Taylor, Couchman and Lu-Weiss, equations. It was found that the experimental results were not in agreement with those from the Fox, Gordon-TayIor and Couchman equations for the binary mixtures of DMWPS, where the interaction parameter chi was approximately zero. However, for the blends PPO/DMWPS (chi < 0), with an increase of molecular weight of PS, it was shown that the experimental results fitted well with those obtained from the Couchman, Gordon-Taylor and Fox equations, respectively. Furthermore, the Gordon-Taylor equation was nearly identical to the Lu-Weiss equation when \chi\ was not very large. Further, the dependence of the change of heat capacity associated with the glass transition (Delta C-p) on the molecular weight of PS was investigated and an empirical equation was presented. (C) 1997 Elsevier Science Ltd.

MISCIBILITY OF POLY(N-VINYL-2-PYRROLIDONE) WITH POLY(ETHER SULFONE) AND 2 PHENOLPHTHALEIN-BASED POLYMERS

Blends of poly(N-vinyl-2-pyrrolidone) (PVP) with poly(ether sulphone) and two phenolphthalein-based polymers, viz. phenolphthalein poly(ether ether sulphone) and phenolphthalein poly(ether ether ketone) were prepared by casting from a common solvent and studied by differential scanning calorimetry. It was found that all the PVP blends are miscible and show a single, composition-dependent glass transition temperature (T(g)). The T(g)-composition dependence has been analysed by the use of the Gordon-Taylor equation. The values of the k parameter in the Gordon-Taylor equation obtained are all not high for the three pairs, in accordance with the fact that there is no strongly specific interaction between PVP and any of the other polymers.

激光热透镜光度分析方法(综述)

激光热透镜效应是1964年Gordon等人首次报道的。他们在研究分子拉曼散射时发现了这一现象,并预言可用于测量溶液中痕量物质的微弱吸收。经过Fang、Swoffod、及Hu等人的努力,使得激光热透镜效应的理论得到了充实和发展,为其在分析领域中的应用打下了基础。1979年Dovichi和Harris首次发表了应用激光热透镜效应进行定量分析,用He-Ne激光为光源建立了单光束实验装置,对Cu-EDTA体系进行了测定。Imasaka等人于1980年采用双光束

Qualidade da semente e densidade de semeadura no estabelecimento e na produtividade do milho.

Uma das principais causas da baixa produtividade de milho é a qualidade da semente, que afeta o estande inicial, o vigor das plantas, e conseqüentemente, a produtividade. O objetivo deste trabalho foi determinar o efeito da qualidade da semente e a densidade de semeadura no estabelecimento e na produtividade de milho. Quatro lotes de sementes de milho BRS 201, com germinação de 95%, 90%, 85% e 75%, foram semeados em três densidades de semeadura: 50, 60 e 70 mil sementes/ha, nos anos de 1996/97 e 1997/98. A baixa qualidade da semente provocou reduções acentuadas na emergência de campo, no número de plantas e, conseqüentemente, na produtividade do milho BRS 201.O aumento da densidade de 50 para 70 mil sementes/ha, na semeadura, não compensou a redução da qualidade da semente. Para o acréscimo de 15% na germinação, foi observado, em média, um ganho de produtividade de 30%. Com base nos resultados destes trabalho, recomenda-se aos produtores de milho a utilização de lotes de sementes com germinação superior a 90% e densidade de semeadura entre 50 e 60 mil sementes/ha.

Automated Assembly Using Feature Localization

Automated assembly of mechanical devices is studies by researching methods of operating assembly equipment in a variable manner; that is, systems which may be configured to perform many different assembly operations are studied. The general parts assembly operation involves the removal of alignment errors within some tolerance and without damaging the parts. Two methods for eliminating alignment errors are discussed: a priori suppression and measurement and removal. Both methods are studied with the more novel measurement and removal technique being studied in greater detail. During the study of this technique, a fast and accurate six degree-of-freedom position sensor based on a light-stripe vision technique was developed. Specifications for the sensor were derived from an assembly-system error analysis. Studies on extracting accurate information from the sensor by optimally reducing redundant information, filtering quantization noise, and careful calibration procedures were performed. Prototype assembly systems for both error elimination techniques were implemented and used to assemble several products. The assembly system based on the a priori suppression technique uses a number of mechanical assembly tools and software systems which extend the capabilities of industrial robots. The need for the tools was determined through an assembly task analysis of several consumer and automotive products. The assembly system based on the measurement and removal technique used the six degree-of-freedom position sensor to measure part misalignments. Robot commands for aligning the parts were automatically calculated based on the sensor data and executed.

Representing and Reasoning About Change in Geologic Interpretation

Geologic interpretation is the task of inferring a sequence of events to explain how a given geologic region could have been formed. This report describes the design and implementation of one part of a geologic interpretation problem solver -- a system which uses a simulation technique called imagining to check the validity of a candidate sequence of events. Imagining uses a combination of qualitative and quantitative simulations to reason about the changes which occured to the geologic region. The spatial changes which occur are simulated by constructing a sequence of diagrams. The quantitative simulation needs numeric parameters which are determined by using the qualitative simulation to establish the cumulative changes to an object and by using a description of the current geologic region to make quantitative measurements. The diversity of reasoning skills used in imagining has necessitated the development of multiple representations, each specialized for a different task. Representations to facilitate doing temporal, spatial and numeric reasoning are described in detail. We have also found it useful to explicitly represent processes. Both the qualitative and quantitative simulations use a discrete 'layer cake' model of geologic processes, but each uses a separate representation, specialized to support the type of simulation. These multiple representations have enabled us to develop a powerful, yet modular, system for reasoning about change.

International transport costs and the margins of Intra-Latin American maritime trade.

This paper focuses on the analysis of the relationship between maritime trade and transport cost in Latin America. The analysis is based on disaggregated (SITC 5 digit level) trade data for intra Latin maritime trade routes over the period 1999-2004. The research contributes to the literature by disentangling the effects of transport costs on the range of traded goods (extensive margin) and the traded volumes of goods (intensive margin) of international trade in order to test some of the predictions of the trade theories that introduce firm heterogeneity in productivity, as well as fixed costs of exporting. Recent investigations show that spatial frictions (distance) reduce trade mainly by trimming the number of shipments and that most firms ship only to geographically proximate customers, instead of shipping to many destinations in quantities that decrease in distance. Our analyses confirm these findings and show that the opposite pattern is observed for ad-valorem freight rates that reduce aggregate trade values mainly by reducing the volume of imported goods (intensive margin).

The use of podcasts to enhance research-teaching linkages in undergraduate nursing students.

An understanding of research is important to enable nurses to provide evidencebasedcare. However, undergraduate nursing students often find research a challenging subject. The purpose of this paper is to present an evaluation of the introduction of podcasts in an undergraduate research module to enhance research teaching linkages between the theoretical content and research in practice and improve the level of student support offered in a blended learning environment. Two cohorts of students (n=228 and n=233) were given access to a series of 5 “guest speaker” podcasts made up of presentations and interviews with research experts within Edinburgh Napier. These staff would not normally have contact with students on this module, but through the podcasts were able to share their research expertise and methods with our learners. The main positive results of the podcasts suggest the increased understanding achieved by students due to the multi-modal delivery approach, a more personal student/tutor relationship leading to greater engagement, and the effective use of materials for revision and consolidation purposes. Negative effects of the podcasts centred around problems with the technology, most often difficulty in downloading and accessing the material. This paper contributes to the emerging knowledge base of podcasting in nurse education by demonstrating how podcasts can be used to enhance research-teaching linkages and raises the question of why students do not exploit the opportunities for mobile learning.

Entrepreneurship and rural economic development: a scenario analysis approach

Fuller-Love, N., Midmore, P., Thomas, D., Henley, A. (2006). Entrepreneurship and rural economic development: A scenario analysis approach. International Journal of Entrepreneurial Behaviour and Research, 12 (5), 289-305. RAE2008

Spatial distribution of upland beetles in relation to landform, vegetation and grazing management

Dennis, P., Aspinall, R. J., Gordon, I. J. (2002). Spatial distribution of upland beetles in relation to landform vegetation and grazing management. Basic and Applied Ecology, 3 (2), 183?193. Sponsorship: SEERAD RAE2008