Différentes interprétations d'un modèle de RI à base d'inclusion graduelle

National audienceRécemment, un modèle théorique de RI à base d'inclusion graduelle a été proposé (Bosc et al., 2008b). Dans ce modèle, dérivé de la division de relations floues, l'inclusion gra- duelle d'une requête dans un document est modélisée par une implication floue. Dans des tra- vaux précédents, nous avons montré que ce modèle pouvait être interprété comme un modèle vectoriel sous certaines conditions. Dans cet article, nous proposons d'explorer d'autres inter- prétations possibles offertes par la modélisation à base d'inclusion graduelle. Nous montrons notamment qu'il est possible d'interpréter notre système flou comme un système de RI à base de modèles de langues, et nous revenons sur les liens entre le modèle flou et les modèles logiques de RI. Plus généralement, nous essayons de clarifier les liens existants entre ces différents mo- dèles, vus sous l'angle de notre SRI flou. RÉSUMÉ. Recently, a theoretical fuzzy IR system, based on gradual inclusion measures, has been proposed (Bosc et al., 2008b). In this model, derived from the division of fuzzy relations, the gradual inclusion of a query in a document is modeled by a fuzzy implication. In previous papers, we have shown that, under some assumptions, this model can be seen as a Vector Space Model. This paper also studies other itnerpretations of our fuzzy IR models based on gradual inclusions. It is shown that the fuzzy models can be interpreted as language models for IR. The links with logical models to IR are also recalled. More generaly, this paper discusses the links between these models, shown from the angle of our fuzzy models

Pathogenesis of frog virus 3 (Ranavirus sp, Iridoviridae) in the wood frog, Rana sylvatica (Lithobates sylvaticus)

Amphibian populations suffer massive mortalities from infection with Frog Virus 3 (FV3, Ranavirus, Iridoviridae), a pathogen also responsible for mortalities of fish and reptiles. Wood frogs, Rana sylvatica, have been proposed as a research model to study diseases of native amphibians in North America. Our objectives were: 1) describe the longbterm housing, feeding and veterinary care of wildbcaught wood frogs, 2) develop a Ranavirusb wood frog model of infection with FV3, 3) review the literature on amphibian clinical pathology, 4) determine hematological reference intervals (RIs) for adult wood frogs and the hematological alterations associated with infection with FV3, and 5) establish the chronology of lesions due to a lethal infection with FV3. Wildbcaught adults and tadpoles were collected from Prince Edward Island and maintained in captivity for up to a year. Survival was good for wildbcaught individuals: 75 % for wildbcaught adults and 77 % for tadpoles raised to adulthood. A dose trial on adults raised from wildbcaught tadpoles established a lethal dose 50 (LD50) of 102.93 (2.42b3.44) pfu of FV3 for frogs averaging 35 mm in length. Onset of clinical signs occurred 6b14 days postbinfection (dpi) (median 11 dpi) and timebtobdeath 10b14 dpi (median 12 dpi). Each tenbfold increase in virus dose increased the odds of dying by 23bfold and accelerated onset of clinical signs and death by approximately 15%. Ranavirus DNA was demonstrated in skin and liver of all frogs that died or were euthanized because of severe clinical signs. Shedding of virus occurred in feces (7b10 dpi; 3b4.5 d before death) and skin sheds (10 dpi; 0b1.5 d before death) of some frogs that died from infection. Most common lesions were dermal erosion and hemorrhages, hematopoietic necrosis in bone marrow, kidney, spleen and liver, necrosis in renal glomeruli and in tongue, gastrointestinal tract, and urinary bladder mucosa. Intracytoplasmic inclusion bodies (probably viral) were present in the bone marrow and the epithelia of the oral cavity, gastrointestinal tract, renal tubules and urinary bladder. A timebcourse trial on wildbcaught adults using a lethal dose of FV3 (104.43 pfu/frog) followed by euthanasia at 0.25, 0.5, 1, 2, 4, 9 and 14 dpi established pathogenesis and hematological alterations due to infection. Infection with FV3 caused neutrophilia, increase in undifferentiated blastblike cells and relative reduction of basophils. Lymphocytes decreased at 4 and 9 dpi but increased 14 dpi. From 9 dpi onwards, nuclear deterioration and mild toxic change were present in neutrophils; cytoplasmic inclusion bodies were present in lymphocytes, monocytes, neutrophils and eosinophils. FV3 first targets hematopoietic tissue in the bone marrow and endothelial cells in the skin causing very mild microscopic lesions (1b2 dpi). Approximately 9 dpi, FV3 caused severe lesions in medullary and extamedullary hematopoietic tissue, lymphoid tissue and epithelial cells of skin and mucosae throughout the body. Direct contact (skin) and fecalboral contamination are likely effective routes of transmission

Meeting the challenges related to material issues in chemical industries

Reliable performance and profitability are two important requirements for any chemical industry. In order to achieve high level of reliability and excellent performance, several issues related to design, materials selection, fabrication, quality assurance, transport, storage, inputs from condition monitoring, failure analysis etc. have to be adequately addressed and implemented. Technology related to nondestructive testing and monitoring of the plant is also essential for precise identification of defect sites and to take appropriate remedial decision regarding repair, replacement or modification of process conditions. The interdisciplinary holistic approach enhances the life of critical engineering components in chemical plants. Further, understanding the failure modes of the components through the analysis of failed components throws light on the choice of appropriate preventive measures to be taken well in advance, to have a control over the overall health of the plant. The failure analysis also leads to better design modification and condition monitoring methodologies, for the next generation components and plants. At the Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam, a unique combination of the expertise in design, materials selection, fabrication, NDT development, condition monitoring, life prediction and failure analysis exists to obtain desired results for achieving high levels of reliability and performance assessment of critical engineering components in chemical industries. Case studies related to design, materials selection and fabrication aspects of critical components in nuclear fuel reprocessing plants, NDT development and condition monitoring of various components of nuclear power plants, and important failure investigations on critical engineering components in chemical and allied industries are discussed in this paper. Future directions are identified and planned approaches are briefly described

Shedding light on living cells and mineralised tissues using Raman spectroscopy

Raman micro-spectroscopy presents a highly sensitive, non-invasive, and rapid way to collect biochemical information from cells and tissues. The resulting Raman spectrum is a chemical ‘fingerprint’ containing a wealth of molecular level information which has been used to characterize, monitor, compare and confirm biological processes from the cellular to tissue levels. The work presented in this thesis utilizes Raman spectroscopy to test live in vitro cellular models, classify human tissues of interest, and determine the biomolecular differences in tissue samples which are diseased or undergoing therapeutic treatment. Additionally new ways of visualizing and interpreting multivariate analytical results are proposed and demonstrated to ease the determination of the biomolecular features which are most important when comparing sample groups. A persistent challenge in the interpretation of information rich biological Raman spectra includes the multitude of signals from lipids, proteins, carbohydrates, nucleic acids, and minerals found in a limited spectral range and in some instances overlapping significantly. Partial Least Squares – Discriminant Analysis (PLS-DA) Variable Importance Projection (VIP) scores were presented as heat maps overlaying difference spectra to ease the visualization of significant biochemical bond changes between sample groups and their trends. The advantages of applying PLS-DA VIP scores in this way are demonstrated in well studied and known system including a cultured cellular model incorporating fixation methods and a human tissue comparison between healthy and osteoporotic bone. PLS-DA VIP score plots were additionally utilized to characterize and compare the biolomecular environments surrounding the recently described microscopic mineral inclusions in human aortic valves and aortae. The PLS-DA VIP score plots exposed the chemical differences in these systems through highlighting the corresponding spectral bands in an easy to read and interpret way. Raman micro-spectroscopy was also applied to investigate an in vitro ‘calcified’ porcine aortic valvular interstitial cell model. This model system was probed for the first time using the combination of Raman micro-spectroscopy and complimentary gold standard biological techniques to determine the protein and potential mineral content within these nodular, cellular systems. The ‘calcified’ porcine aortic valvular cell nodules showed no evidence of mineral inclusion. These nodules did exhibit a heavy extracellular matrix production including the production of collagen I. The porcine aortic valvular cell nodules acting as a model system for diseased aortic valve tissue requires not only the characterization of the cell nodule in vitro but also the characterization of the human disease spectrum which the model is suggested to replicate. The discovery and characterisation of microscopic mineral spherical inclusions (50nm-200µm) located in both valvular and vascular tissues leads to an interesting question on the introduction and role of microscopic mineral deposits in cardiovascular disease. Here Raman micro-spectroscopy was utilized to investigate the organic matrix surrounding these microscopic mineral deposits to determine if any colocalised protein changes exist. Protein and specifically collagen changes are demonstrated between tissues with and without the spherical mineral deposits despite being macroscopically indistinguishable. Raman spectroscopy was also utilized to provide direct insights into tissue constituent and structural changes on the molecular level in heat-induced tissue fusion via radio-frequency (RF) energy. This type of tissue fusion has gained wide acceptance clinically and is presented here as the first optical-Raman-spectroscopy study on tissue fusion samples in vitro. This study exposed spectroscopic evidence for the loss of distinct collagen fibres rich tissue layers as well as the denaturing and restructuring of collagen crosslinks post RF fusion. Raman spectroscopy is a demonstrated, powerful, biomolecular imaging technique which benefits from advancements in mathematical analytical techniques as well as its own application in biological investigations. This thesis explores the application of Raman spectroscopy in combination with powerful analytical techniques to further characterize and compare biological systems of interest.Open Acces

Advanced Turbine Technology Applications Project (ATTAP)

This report summarizes work performed in support of the development and demonstration of a structural ceramic technology for automotive gas turbine engines. The AGT101 regenerated gas turbine engine developed under the previous DOE/NASA Advanced Gas Turbine (AGT) program is being utilized for verification testing of the durability of next-generation ceramic components and their suitability for service at reference powertrain design conditions. Topics covered in this report include ceramic processing definition and refinement, design improvements to the test bed engine and test rigs, and design methodologies related to ceramic impact and fracture mechanisms. Appendices include reports by ATTAP subcontractors addressing the development of silicon nitride and silicon carbide families of materials and processes