Compilability of Abduction

Abduction is one of the most important forms of reasoning; it has been successfully applied to several practical problems such as diagnosis. In this paper we investigate whether the computational complexity of abduction can be reduced by an appropriate use of preprocessing. This is motivated by the fact that part of the data of the problem (namely, the set of all possible assumptions and the theory relating assumptions and manifestations) are often known before the rest of the problem. In this paper, we show some complexity results about abduction when compilation is allowed

Effect of hydrocarbon fractions, N₂ and CO₂ in feed gas on hydrogen production using sorption enhanced steam reforming: Thermodynamic analysis

H₂ yield and purity from sorption enhanced steam reforming (SE-SR) are determined by temperature, S:C ratio in use, and feed gas composition in hydrocarbons, N₂ and CO₂. Gases with high hydrocarbons composition had the highest H₂ yield and purity. The magnitude of sorption enhancement effects compared to conventional steam reforming (C-SR), i.e. increases in H₂ yield and purity, and drop in CH₄ yield were remarkably insensitive to alkane (C1-C3) and CO₂ content (0.1-10 vol%), with only N₂ content (0.4-70 vol%) having a minor effect. Although the presence of inert (N₂) decreases the partial pressure of the reactants which is beneficial in steam reforming, high inert contents increase the energetic cost of operating the reforming plants. The aim of the study is to investigate and demonstrate the effect of actual shale gas composition in the SE-SR process, with varied hydrocarbon fractions, CO₂ and N₂ in the feedstock

A qualitative study of perceptions of professionalism amongst radiography students

Purpose: To explore perceptions of professionalism amongst Estonian radiography students in order to identify their understandings of professionalism, the factors that influence the development of their understandings and those skills required to achieve professionalism. Methods: A qualitative study using a semi-structured focus group approach involved four main questions: 1. What does the word professionalism mean to you? 2. What does the word unprofessionalism mean to you? 3. What has influenced your understanding of professionalism? 4. What is your current understanding of what you need to become a professional? Prior to the study, first year students had no radiology clinical placement experience unlike third year students. Interviews with first years (n = 7) and third years (n = 10) were recorded and transcribed verbatim. Thematic content analysis was employed to classify student responses resulting in a number of related to general skills, specific skills, personal characteristics and the impacts of educational environments. Results: Four main themes were explored: 1) characteristic features of professionalism; 2) common manifestations of unprofessional conduct; 3) factors influencing the development of professionalism; 4) developmental needs for the achievement of professionalism. Sub-themes emerged related to three groups of influencing factors i.e. theoretical studies, clinical training and personal characteristics. An influencing factor may have a positive effect or a negative effect dependent on the nature of any particular factor. Conclusions: Awareness of student perceptions enables educators and clinical staff to assure the content and organisation of theoretical studies and clinical placements to facilitate the impact of positive factors and minimise the negative factors

Research Notes : Evaluation of soybean germplasm for aluminum tolerance

A growth-chamber experiment was conducted in nutrient solution containing 0 or 8 ppm of aluminum as Al2K(S04)3 to study differential Al tolerance of soybean germplasm representing Maturity Groups V, VI and VII, supplied by Dr. E. E. Hartwig. Two soybean cultivars, one sensitive (\u27Chief\u27) and the other tolerant (\u27Perry\u27), were included as standard checks (Fig. 1). Soybean roots were affected by the presence of Al and showed discoloration, stunted and blackish root tips

Research Notes : United States : Influence of genotype and growth stage on nitrogen fixation in soybeans

One of the many characteristics that makes soybeans a desirable crop is their ability to fix nitrogen. In order to enhance this ability, it is ne-cessary to look at the variation among various cultivars throughout their life cycle. Genetic studies for Spanish clover (Desmodium sandwicense E. Mey) by Pinchbeck et al. (1980) showed a significant difference among genotypes in their ability to fix nitrogen

Protective immunization against murine cytomegalovirus infection using adenoviruses and poxviruses expressing hepatitis B virus chimeras

Recombinant adenoviruses, poxviruses, and plasmid DNA vaccines encoding different hepatitis B virus (HBV)/murine cytomegalovirus (MCMV) protein chimeras were used to immunize mice. Processing of the chimeras resulted in presentation of a protective Ld/CD8+ T-cell epitope of the immediate early 1 protein pp89 (IE1 pp89) of MCMV to the immune system. Different levels of immunogenicity were observed depending on: (i) the type of viral vector used, (ii) whether the antigens were included in the cellular secretion pathway, and (iii) the location of the protective epitope within the chimeric protein. An adenovirus expressing a secretory HBV core protein with the MCMV epitope in its C-terminus induced the highest immune response. When the most immunogenic adenovirus and vaccinia virus were used in a heterologous prime-boost immunization protocol, even higher levels of epitope-specific T cells were obtained. Furthermore, responses were protective against a challenge with MCMV, inducing up to a 96% reduction of viral load in immunized animals, as determined by a sensitive real-time PCR assay. Together, these results confirmed previous observations of the efficient use of adenoviral and poxviral vectors in prime-boost protocols for immunization against diseases whose resolution depends on cellular immunity, as well as the aptness of correctly designed chimeric carrier proteins to facilitate this goal. [Int Microbiol 2007; 10(4):261-269