Clinical system for interstitial photodynamic therapy with combined on-line dosimetry measurements

A system for interstitial photodynamic therapy with delta-aminolaevulinic acid and multiple optical fibers has been developed. The system enables photodynamic treatment of large embedded tumor volumes and utilizes real-time measurements to allow on-line dosimetry. Important parameters such as light fluence rate, sensitizer fluorescence intensity, and changes in local blood oxygen saturation are measured with the same fibers that deliver the therapeutic light. Data from the first clinical treatments on nodular basal cell carcinomas indicate a major treatment-induced light absorption increase, rapid sensitizer photobleaching, and a relatively constant global tissue oxygen saturation level during the treatment.     

Prediction of adipose tissue composition using raman spectroscopy: Average properties and individual fatty acids

Raman spectroscopy has been used for the first time to predict the FA composition of unextracted adipose tissue of pork, beef, lamb, and chicken. It was found that the bulk unsaturation parameters could be predicted successfully [R ²=0.97, root mean square error of prediction (RMSEP)=4.6% of 4 δ], with cis unsaturation, which accounted for the majority of the unsaturation, giving similar correlations. The combined abundance of all measured PUFA (≥2 double bonds per chain) was also well predicted with R ²=0.97 and RMSEP=4.0% of 4 δ. Trans unsaturation was not as well modeled (R ²=0.52, RMSEP=18% of 4 δ); this reduced prediction ability can be attributed to the low levels of trans FA found in adipose tissue (0.035 times the cis unsaturation level). For the individual FA, the average partial least squares (PLS) regression coefficient of the 18 most abundant FA (relative abundances ranging from 0.1 to 38.6% of the total FA content) was R ²=0.73; the average RMSEP=11.9% of 4 δ. Regression coefficients and prediction errors for the five most abundant FA were all better than the average value (in some cases as low as RMSEP=4.7% of 4 δ). Cross-correlation between the abundances of the minor FA and more abundant acids could be determined by principal component analysis methods, and the resulting groups of correlated compounds were also well predicted using PLS. The accuracy of the prediction of individual FA was at least as good as other spectroscopic methods, and the extremely straightforward sampling method meant that very rapid analysis of samples at ambient temperature was easily achieved. This work shows that Raman profiling of hundreds of samples per day is easily achievable with an automated sampling system.     

A decentralized approach for convention emergence in multi-agent systems

The field of convention emergence studies how agents involved in repeated coordination games can reach consensus through only local interactions. The literature on this topic is vast and is motivated by human societies, mainly addressing coordination problems between human agents, such as who gets to redial after a dropped telephone call. In contrast, real-world engineering problems, such as coordination in wireless sensor networks, involve agents with limited resources and knowledge and thus pose certain restrictions on the complexity of the coordination mechanisms. Due to these restrictions, strategies proposed for human coordination may not be suitable for engineering applications and need to be further explored in the context of real-world application domains. In this article we take the role of designers of large decentralized multi-agent systems. We investigate the factors that speed up the convergence process of agents arranged in different static and dynamic topologies and under different interaction models, typical for engineering applications. We also study coordination problems both under partial observability and in the presence of faults (or noise). The main contributions of this article are that we propose an approach for emergent coordination, motivated by highly constrained devices, such as wireless nodes and swarm bots, in the absence of a central entity and perform extensive theoretical and empirical studies. Our approach is called Win-Stay Lose-probabilistic-Shift, generalizing two well-known strategies in game theory that have been applied in other domains. We demonstrate that our approach performs well in different settings under limited information and imposes minimal system requirements, due to its simplicity. Moreover, our technique outperforms state-of-the-art coordination mechanisms, guarantees full convergence in any topology and has the property that all convention states are absorbing.     

FRP包裹钢筋混凝土柱抗震加固的耐久性设计

虽然FRP材料已经越来越多地被采用在土木建设方面,但依然缺乏长期的耐久性试验数据,以及在结构水平上的明确的、长期劣化设计理论方法。针对一组试验数据,在材料水平上评定了FRP护套抗震计算的长期劣化标准。共测试了三种不同的系统,快速试验结果被用于材料长期性能的预测,以此分析在四种特殊工况下抗震加固的效果。显而易见,劣化的影响可用预期寿命对应的包裹厚度的增长值来表达。将结果与ACI-440的推荐值以及随时间变化的材料劣化模型结果进行比较,表明ACI的失效推荐值在考虑50年周期时有些保守。通过采用前面所提到的材料耐久性预测方法和FRP防护层厚度设计分析工具,不仅能够更好地对防护层厚度进行估算,而且可以对选择防护层厚度的主要控制机理进行评定。其中,防护层厚度随着暴露时间的长短而改变。快速试验的结果与自然露天测试结果的关系可以用一系列相关的系数来表达。     

Determination of Amylose Content in Different Starches Using Modulated Differential Scanning Calorimetry

A simple calorimetric method for determination of amylose content in starch is reported. Starches were heated in the presence of two common surfactants, viz., sodium dodecyl sulphate (SDS) and cetyltrimethylammonium bromide (CTAB), and the enthalpies of melting of the amylose‐surfactant complexes were determined using Modulated Differential Scanning Calorimetry (MDSC). A large number of native starches including cereal, root and pea starches were examined. The results were compared with those obtained by iodimetry and gel permeation chromatography (GPC) for all the starches. There was a good correlation between the values from iodimetry and GPC with those obtained using the surfactants. Both surfactants seemed to work equally well, even for those starches with about 40% amylose content. However, in case of SDS higher standard deviations were usually obtained than for CTAB in the determination of transition enthalpies.     

Assessing mobile phone communication utility preferences in a social support network

While it is generally accepted that the mobile cell phone has become ubiquitous within society for communicating, the actual use of the utilities on a phone have not been reported. Understanding how communication patterns are changing in society as a result of the mobile cell phone will enable the development and/or modification of existing cell phone utilities, the concept of privacy, and a mobile literacy research domain. To explore mobile cell phone utility use, 99 people completed a mobile phone usage questionnaire. Key results from the questionnaire are physical location when using a mobile cell phone, the length of communication episodes, the usage of phone utilities and existing privacy concerns related to mobile cell phones.     

Reliability performance of safety instrumented systems: A common approach for both low- and high-demand mode of operation

Safety instrumented systems (SISs) are usually divided into two modes of operation, low-demand and high-demand. Unfortunately, this classification is not easy to justify and the available formulas that are used to quantify the reliability performance in these two modes of operation are unable to capture combined effects of functional testing, spurious activations, and successful responses to demands. This article discusses some important modeling issues for SIS reliability performance quantification, and demonstrates their implementation in a Markov model. The accuracy of the Markov model for a simple case study of a pressure transmitter is verified through comparison with a scenario-based formula, and it is shown that the Markov approach gives a sufficiently accurate result for all demand rates, covering both low- and high-demand modes of operation.     

Book reviews

The Housing and Living Environment for Retired people in Australia. edited by Ross Thorne. Sydney: Hale & Iremonger. 1986. pp348 $A 29.95.

The Modern Urban Landscape. by Edward Relph. London: Croom Helm, 1987 pp279. £10.95.

Housing the Homeless. edited by Jon Erickson and Charles Wilhelm New Brunswick, New Jersey: Center for Urban Policy Research, Rutgers University. 1986. pp459. $19.95.

Cities: Special Issue: Shelter and Homelessness. Vol 4 No 1, February 1987. London: Butterworth. pp104.