Efficient Binary Tomographic Reconstruction

Tomographic reconstruction of a binary image from few projections is considered. A novel heuristic algorithm is proposed, the central element of which is a nonlinear transformation ψ(p)=log(p/(1?p)) of the probability p that a pixel of the sought image be 1-valued. It consists of backprojections based on ψ(p) and iterative corrections. Application of this algorithm to a series of artificial test cases leads to exact binary reconstructions, (i.e., recovery of the binary image for each single pixel) from the knowledge of projection data over a few directions. Images up to 10⁶ pixels are reconstructed in a few seconds. A series of test cases is performed for comparison with previous methods, showing a better efficiency and reduced computation times.     

Characterization of Maximum Likelihood Solutions to Image Reconstruction in Photon Emission Tomography

For photon emission tomography, the maximum likelihood (ML) estimator for image reconstruction is generally solution to a nonlinear equation involving the vector of measured data. No explicit closed-form solution is known in general for such a nonlinear ML equation, and numerical resolution is usually implemented, with a very popular iterative method formed by the expectation-maximization algorithm. The numerical character of such resolutions usually makes it difficult to obtain a general characterization of the performance of the ML solution. We show that the nonlinear ML equation can be replaced by an equivalent system of two dual linear equations nonlinearly coupled. This formulation allows us to exhibit explicit (to some extent) forms for the solutions to the ML equation, in general conditions corresponding to the various possible configurations of the imaging system, and to characterize their performance with expressions for the mean-squared error, bias and Cramér-Rao bound. The approach especially applies to characterize the ML solutions obtained numerically, and offers a theoretical framework to contribute to better appreciation of the capabilities of ML reconstruction in photon emission tomography.     

Quantitative preparation of long chain thioethers from an oxo-trans-2-enoic ester and a 9,12-dioxo-trans-10-enoic acid

Branched-chain thioethers have been prepared from methyl 4-oxo-trans-2-hexadecenoate and 9,12-dioxo-trans-10-octadecenoic acid. The reagents involved in these preparations were mercaptoacetic and mercaptopropionic acids. The yields of these thioethers are almost quantitative.     

陶瓷坯体增强剂聚丙烯酸钠在艺术瓷成形过程的应用

本文合成了一系列不同相对分子质量的聚丙烯酸钠,应用于艺术瓷的坯体中,研究了聚丙烯酸钠对艺术瓷坯体强度、变形率的影响,并对聚丙烯酸钠增强机理进行了探讨。结果表明:聚丙烯酸钠可有效地提高艺术瓷坯体的成形强度,减少了坯体的变形率,当增强剂c加入的质量分数为0.6%时,坯体的干燥强度增加率达167.5%,坯体的变形率从50%降低到10%。     

Cotton Seed Oil Oxidation Catalysed by Amino Acids and Albumin in Aqueous and Non-Aqueous Media

The oxidation of refined cotton seed oil catalysed by various α-amino acids and albumin have been studied in aqueous and non-aqueous media. Cysteine, phenylalanine and albumin possessed pro-oxidant effect in cotton seed oil in aqueous and non-aqueous media. Serine exhibited pro-oxidant activity in aqueous media and minor anti-oxidant effect in non-aqueous media. The effectiveness of the amino acids on cotton seed oil oxidation was in the following descending order in both aqueous and non-aqueous media: cysteine > phenylalanine > serine. The pro-oxidant effect in aqueous media might be due to the predominant presence of the protonated amino nitrogen. Whilst, amino acid-metal complex might be responsible for the pro-oxidant effect in non-aqueous media.     

Evaluation of Trans and Essential Fatty Acid Content in Some Egyptian Consumer-Available Hydrogenated Fats

The fatty acid composition of cottonseed and com oils was determined before and after the technological hydrogenation process. In hydrogenated cottonseed and corn oils the essential fatty acid content (linoleic, 18:2 ω⁶) was decreased while the trans-18:1 acid was increased as compared to the native oils. The trans as well as the essential fatty acid contents in some consumeravailable hydrogenated fats were evaluated. The composition of cis and trans monoene isomers were also determined. This study revealed that some of the Egyptian consumer-available hydrogenated fats contain considerable amounts of trans acids.     

A web-based platform for biosignal visualization and annotation

With the advent of wearable sensing and mobile technologies, biosignals have seen an increasingly growing number of application areas, leading to the collection of large volumes of data. One of the difficulties in dealing with these data sets, and in the development of automated machine learning systems which use them as input, is the lack of reliable ground truth information. In this paper we present a new web-based platform for visualization, retrieval and annotation of biosignals by non-technical users, aimed at improving the process of ground truth collection for biomedical applications. Moreover, a novel extendable and scalable data representation model and persistency framework is presented. The results of the experimental evaluation with possible users has further confirmed the potential of the presented framework.     

支持多种手机客户端的校园信息发布系统

针对数字化校园建设中存在的信息孤岛问题,设计开发了基于客户服务架构的能支持多种手机客户端的校园信息发布系统。分析了系统功能,描述了系统拓扑结构和软件架构,对数据交换接口、网页和手机客户端信息提醒等关键技术进行了探讨。试用结果表明系统运行良好,达到了设计目的。     

Conceptualization,measurement, and application of semantic transparency in visual notations

Numerous visual notations are present in technical and business domains. Notations have to be cognitively effective to ease the planning, documentation, and communication of the domains’ concepts. Semantic transparency (ST) is one of the elementary principles that influence notations’ cognitive effectiveness. However, the principle is criticized for not being well defined and challenges arise in the evaluations and applications of ST. Accordingly, this research’s objectives were to answer how the ST principle is defined, operationalized, and evaluated in present notations as well as applied in the design of new notations in ICT and related areas. To meet these objectives, a systematic literature review was conducted with 94 studies passing the selection process criteria. The results reject one of the three aspects, which define semantic transparency, namely “ST is achieved with the use of icons.” Besides, taxonomies of related concepts and research methods, evaluation metrics, and other findings from this study can help to conduct verifiable ST-related experiments and applications, consequently improving the visual vocabularies of notations and effectiveness of the resulting diagrams.