Returning Genius to the Place

Advocates of sustainable design since the early 1990s, HOK are intent on disseminating new research, resources and tools across their global design teams. Mary Ann Lazarus , Sustainable Design Director at HOK, and Chip Crawford , Planning Group Director at HOK, describe a particularly innovative project that the two groups have collaborated on with the essential input of the Biomimicry Guild (see p 44). Addressing critical environmental issues at the habitat scale and performance standards, they have developed ecological design tools that have been employed on masterplans for Lavasa, India, and Langfang, China. Copyright © 2011 John Wiley & Sons, Ltd.     

Design Constraints and Reconstruction Algorithms for Traverse-Continuous-Rotate CT Scanners

In this paper a new configuration for a computerized tomographic (CT) scanner is presented. The machine is essentially a hybrid combination of second- and third-generation scanners. A single source of X-rays and an array of detectors are mounted on a gantry. The source/detector array grouping traverses the object while the gantry continuously rotates around the object. Conditions will be derived so that the projection data will completely cover the Radon space without any holes or partial overlaps, thus ensuring the existence of efficiently implementable reconstruction algorithms for inverting the data. We will also present a new convolution-backprojection algorithm for reconstructing tomographic images from data generated on such a scanner.     

利益相关者对辐射防护的看法

辐射照射许可标准及其制定方法必须体现维护健康和民主的原则。当辐射危害的科学是不确定的时候,举证没有构成危险的责任在于危险源的一方,而不在可能受影响的公众的或工作人员一方。科学论证的进程必须对公众透明,必须考虑所有的相关危险问题和疾病终点(不仅是癌),必须考虑受到辐射危险的人们的实际经验和意见。科学家们往往太轻视公众的经验和权益,尽管常常证明公众和工作人员的意见对于制定辐射防护原则是有价值的。既要礼貌地体现工作人员和公众的关注、观点和经验,又要维护高标准的科学工作,必须是标准制定过程的基础部分。ICRP阐明的“强加的危险必须伴有明确的利益”的原则应当是标准制定过程中一个更加明确的部分,必须保证所有已知的危险是被揭示出来了,所怀疑的危险如某些放射性核素与紊乱荷尔蒙的化学品之间可能的协同作用是得到了认真的考虑。最后,鉴于许多放射性核素的长寿命特性和未来自然的、社会的、经济的以及其它条件的巨大不确定度,在制定标准的过程中如何体现子孙后代的权益是一个困难的但是至关重要的的问题。     

Ionospheric wave spectrum measurements

A significant quantity to be measured in the ionosphere is the local spectrum, S(k,ω), of either potential or electron density fluctuations. One can determine from S(k,ω) characteristics of the macroscopic plasma such as the local density and temperature, transport coefficients, and drift current. Determination of S(k,ω) may be carried out by measurement of the cross-power spectrum. Signals from two probes are passed through a cross-power spectrum analyzer, and the measurement is repeated for a series of probe separations. The resulting cross-power spectra, H(r,ω), must be Fourier-transformed to obtain S(k,ω). A number of questions pertinent to the use of this method in space are discussed. These include the expected signal-to-noise ratio, and the frequency and wave-number resolution attainable.     

Report of the treasurer.

Provides a treasurer's report for the American Psychological Association that covers the last year completed and audited, the current year, and the next year. The fiscal period is the calendar year. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Consequences of the photodynamic treatment of resting and activated peripheral T lymphocytes

Silencing of the cryptic mating-type loci HMR and HML requires the recognition of DNA sequence elements called silencers by the Sir1p, one of four proteins dedicated to the assembly of silenced chromatin in Saccharomyces cerevisiae. The Sir1p is thought to recognize silencers indirectly through interactions with proteins that bind the silencer DNA directly, such as the origin recognition complex (ORC). Eight recessive alleles of SIR1 were discovered that encode mutant Sir1 proteins specifically defective in their ability to recognize the HMR-E silencer. The eight missense mutations all map within a 17-amino-acid segment of Sir1p, and this segment was also required for Sir1p's interaction with Orc1p. The mutant Sir1 proteins could function in silencing if tethered to a silencer directly through a heterologous DNA-binding domain. Thus the amino acids identified are required for Sir1 protein's recognition of the HMR-E silencer and interaction with Orc1p, but not for its ability to function in silencing per se. The approach used to find these mutations may be applicable to defining interaction surfaces on proteins involved in other processes that require the assembly of macromolecular complexes.     

Solid freeform fabrication

Researchers at Austin have been working on technologies termed solid freeform fabrication (SFF) or, as reported in the popular press, desktop manufacturing, rapid prototyping, and layered manufacturing. Such processes have the potential to produce accurate, structurally sound 3-D renditions of objects designed with computers and manufactured directly from a CAD database, without part-specific tooling or human intervention, and to make them available to the user in minutes or hours. The benefits include greatly reduced prototyping cost and design time and reliability to achieve, in one operation, shapes that would otherwise require multiple operations or in some cases be impossible to produce with standard techniques. Automated manufacturing technologies in general are well suited to large production numbers, but ill suited to low-volume runs. In the latter case, the components are too few to adequately amortize the cost of part-specific tooling; instead, they are typically made by hand at much greater unit cost and longer completion times. Nor is it a completely desirable low-volume option to interface CAD systems with numerically controlled (NC) machining centers-in essence, computer controlled material removal systems-because so much human intervention is involved in producing NC programs and setting up and supervising NC systems. In fact, the low-volume production arena is exactly where SFF slashes cost and time to completion     

What's in the Middle?

Enterprise Middleware has the power to help you quickly develop, deploy and manage critical on-line transaction processing and client/server applications to take advantage more easily of new business opportunities and to manage, change or extend your business — but first you need to know what to look for in the increasingly diverse range of technology products. This paper discusses the issues that a programme in BT should consider when selecting middleware products to deploy with BT systems. The paper draws upon the experiences gained within the Client/Server Evolution Laboratory (CSLab), part of in Ipswich Software Engineering Centre's (ISEC's) Systems and Software Strategy Unit, with particular emphasis on the Object Management Group's Common Object Request Broker Architecture (CORBA), Distributed Computing Environment and Java.     

Ultrafast electron diffraction and direct observation of transient structures in a chemical reaction

Ultrafast electron diffraction is a unique method for the studies of structural changes of complex molecular systems. In this contribution, we report direct ultrafast electron diffraction study of the evolution of short-lived intermediates in the course of a chemical change. Specifically, we observe the transient intermediate in the elimination reaction of 1,2-diiodotetrafluoroethane (C2F4I2) to produce the corresponding ethylene derivative by the breakage of two carbon-iodine, C---I, bonds. The evolution of the ground-state intermediate (C2F4I radical) is directly revealed in the population change of a single chemical bond, namely the second C---I bond. The elimination of two iodine atoms was shown to be nonconcerted, with reaction time of the second C---I bond breakage being 17 +/- 2 ps. The structure of the short-lived C2F4I radical is more favorable to the classical radical structure than to the bridged radical structure. This leap in our ability to record structural changes on the ps and shorter time scales bodes well for many future applications in complex molecular systems.