25 research outputs found

    Thermal conductivity in harmonic lattices with random collisions

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    We review recent rigorous mathematical results about the macroscopic behaviour of harmonic chains with the dynamics perturbed by a random exchange of velocities between nearest neighbor particles. The random exchange models the effects of nonlinearities of anharmonic chains and the resulting dynamics have similar macroscopic behaviour. In particular there is a superdiffusion of energy for unpinned acoustic chains. The corresponding evolution of the temperature profile is governed by a fractional heat equation. In non-acoustic chains we have normal diffusivity, even if momentum is conserved.Comment: Review paper, to appear in the Springer Lecture Notes in Physics volume "Thermal transport in low dimensions: from statistical physics to nanoscale heat transfer" (S. Lepri ed.

    Renormalization Scheme Dependence and the Problem of Theoretical Uncertainties in Next-Next-to-Leading Order QCD Predictions

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    Renormalization scheme uncertainties in the next-next-to-leading order QCD predictions are discussed. To obtain an estimate of these uncertainties it is proposed to compare predictions in all schemes that do not have unnaturally large expansion coefficients. A concrete prescription for eliminating the unnatural schemes is given, based on the requirement that large cancellations in the expression for the characteristic renormalization scheme invariant should be avoided. As an example the QCD corrections to the Bjorken sum rule are considered. The importance of the next-next-to-leading order corrections for a proper evaluation of perturbative QCD predictions is emphasized.Comment: 15 pages, 3 figures,Late

    25 Years of Self-organized Criticality: Concepts and Controversies

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    Introduced by the late Per Bak and his colleagues, self-organized criticality (SOC) has been one of the most stimulating concepts to come out of statistical mechanics and condensed matter theory in the last few decades, and has played a significant role in the development of complexity science. SOC, and more generally fractals and power laws, have attracted much comment, ranging from the very positive to the polemical. The other papers (Aschwanden et al. in Space Sci. Rev., 2014, this issue; McAteer et al. in Space Sci. Rev., 2015, this issue; Sharma et al. in Space Sci. Rev. 2015, in preparation) in this special issue showcase the considerable body of observations in solar, magnetospheric and fusion plasma inspired by the SOC idea, and expose the fertile role the new paradigm has played in approaches to modeling and understanding multiscale plasma instabilities. This very broad impact, and the necessary process of adapting a scientific hypothesis to the conditions of a given physical system, has meant that SOC as studied in these fields has sometimes differed significantly from the definition originally given by its creators. In Bak’s own field of theoretical physics there are significant observational and theoretical open questions, even 25 years on (Pruessner 2012). One aim of the present review is to address the dichotomy between the great reception SOC has received in some areas, and its shortcomings, as they became manifest in the controversies it triggered. Our article tries to clear up what we think are misunderstandings of SOC in fields more remote from its origins in statistical mechanics, condensed matter and dynamical systems by revisiting Bak, Tang and Wiesenfeld’s original papers

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    Not AvailableOur study reports the collection, biodiversity analyses, isolation and identification of microalgae from different habitats of India. Cyanophyceae and Chlorophyceae were the most dominant algal groups recorded, with the highest number being recorded for non-heterocystous cyanobacteria (48), followed by 44 unicellular forms. Sagar Island, Sunderbans recorded the greatest number of algae, and unicellular/colonial green algae were present in all the samples. Shannon’s Diversity Index was highest in Koikhali, Sunderbans, followed by Rushikulya River, Odisha. Selective enrichment, purification through serial dilution followed by plating and regular observations led to the isolation of sixteen strains. Identification was done by using microscopic observations, supported with standard monographs and classified as belonging to seven genera (Chlorella, Chlorococcum, Kirchneria, Scenedesmus, Chlamydomonas, Tetracystis and Ulothrix). 18S rDNA sequencing was undertaken for four strains. The set of sixteen strains were screened under standard cultural conditions for their growth kinetics and Chlorella sorokiniana MIC-G5, followed by Chlorella sp. MIC-G4 exhibited the highest growth rates. The strain Chlorococcum sp. MIC-G2 recorded highest chlorophyll, while MIC-G3 ranked highest for carbohydrates. The study aided in identifying the dominant microalgae in the diverse habitats and characterizing their growth rate and carbohydrate content, providing a valuable germplasm for further utilization in agriculture and industry.Not Availabl

    Building and Querying Microbial Ontology, Procedia Technology

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    Not AvailableThe microbial taxonomy is based on the characteristics of microorganisms that can be objectively observed and measured. There are many scheme of microbial classification, but the latest is the three domain system and is the most accepted. Ontologies are the new form of knowledge representation that acts in synergy with agents and Semantic Web Architecture. Ontologies define domain concepts and the relationships between them, and thus provide a domain language that is meaningful to both humans and machines. The relationships in Ontology are explicitly named and developed with specification of rules and constraints so that they reflect the context of domain for which the knowledge is modelled. Ontologies can be built by using various GUI based software tools, known as Ontology editors. Among all editors Protégé is widely supported by a huge research community. For effective use of Ontology, protégé provides a query interface known as SPARQL query panel. SPARQL is a syntactically-SQL-like language for querying RDF graphs. Microbial Taxonomy Ontology is developed for the three domain system of microbes for the domain Bacteria which will be helpful for the study of Agriculturally Important Microbes (Bacteria). This ontology is built in the Protégé OWL editor from Domain to Genus level. Using this ontology, a query interface can be developed that will help detailed study of microbial taxonomy, classification of microbes as well as exchange knowledge between software agents and systems.Not Availabl

    Building and Querying Microbial Ontology

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    AbstractThe microbial taxonomy is based on the characteristics of microorganisms that can be objectively observed and measured. There are many scheme of microbial classification, but the latest is the three domain system and is the most accepted. Ontologies are the new form of knowledge representation that acts in synergy with agents and Semantic Web Architecture. Ontologies define domain concepts and the relationships between them, and thus provide a domain language that is meaningful to both humans and machines. The relationships in Ontology are explicitly named and developed with specification of rules and constraints so that they reflect the context of domain for which the knowledge is modelled. Ontologies can be built by using various GUI based software tools, known as Ontology editors. Among all editors Protégé is widely supported by a huge research community. For effective use of Ontology, protégé provides a query interface known as SPARQL query panel. SPARQL is a syntactically-SQL-like language for querying RDF graphs. Microbial Taxonomy Ontology is developed for the three domain system of microbes for the domain Bacteria which will be helpful for the study of Agriculturally Important Microbes (Bacteria). This ontology is built in the Protégé OWL editor from Domain to Genus level. Using this ontology, a query interface can be developed that will help detailed study of microbial taxonomy, classification of microbes as well as exchange knowledge between software agents and systems

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    Not AvailableIdentification of cost-effective cell disruption methods to facilitate lipid extraction from microalgae represents a crucial step in identifying promising biofuel-producing species. Various cell disruption methods including autoclaving, microwave, osmotic shock and pasteurization were tested in the microalgae Chlorococcum sp. MCC30, Botryococcus sp. MCC31, Botryococcus sp. MCC32 and Chlorella sorokiniana MIC-G5. Lipid content (on dry weight basis) from the four cultures on day 7 ranged from 11.15% to 48.33%, and on day 14 from 11.42% to 44.26%. Among the methods tested, enhanced lipid extraction was achieved through osmotic shock (15% NaCl) for Botryococcus sp. MCC32, microwave (6 min) for Botryococcus sp. MCC31, osmotic shock (5% NaCl) for Chlorella sorokiniana MIC-G5 and microwave (2 min) for Chlorococcum sp. MCC30. The highest palmitate (16:0) contents of (25.64% and 34.20%) were recorded with osmotic shock (15% NaCl) treatment for Botryococcus sp. MCC32 and microwave (6 min) for Botryococcus sp. MCC31, respectively. Two strains, along with their respective cell disruption methods, were identified as promising oil blends or nutraceuticals due to their high unsaturated fatty acids (UFA) content: Botryococcus sp. MCC31 (37.6% oleic acid content; 39.37% UFA) after autoclaving and Botryococcus sp. MCC32 after osmotic shock of 15% NaCl treatment (19.95% oleic acid content; 38.17% UFA).This article is protected by copyright. All rights reservedNot Availabl

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    Not AvailableIdentification of cost-effective cell disruption methods to facilitate lipid extraction from microalgae represents a crucial step in identifying promising biofuel-producing species. Various cell disruption methods including autoclaving, microwave, osmotic shock and pasteurization were tested in the microalgae Chlorococcum sp. MCC30, Botryococcus sp. MCC31, Botryococcus sp. MCC32 and Chlorella sorokiniana MIC-G5. Lipid content (on dry weight basis) from the four cultures on day 7 ranged from 11.15% to 48.33%, and on day 14 from 11.42% to 44.26%. Among the methods tested, enhanced lipid extraction was achieved through osmotic shock (15% NaCl) for Botryococcus sp. MCC32, microwave (6 min) for Botryococcus sp. MCC31, osmotic shock (5% NaCl) for Chlorella sorokiniana MIC-G5 and microwave (2 min) for Chlorococcum sp. MCC30. The highest palmitate (16:0) contents of (25.64% and 34.20%) were recorded with osmotic shock (15% NaCl) treatment for Botryococcus sp. MCC32 and microwave (6 min) for Botryococcus sp. MCC31, respectively. Two strains, along with their respective cell disruption methods, were identified as promising oil blends or nutraceuticals due to their high unsaturated fatty acids (UFA) content: Botryococcus sp. MCC31 (37.6% oleic acid content; 39.37% UFA) after autoclaving and Botryococcus sp. MCC32 after osmotic shock of 15% NaCl treatment (19.95% oleic acid content; 38.17% UFA).This article is protected by copyright. All rights reservedNot Availabl

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    Not AvailableThe genus Chlorella is a widely employed microalga for biodiesel, as it can be grown using photo/mixo/heterotrophic mode of cultivation. The present investigation was undertaken with the hypothesis that addition of different substrates (amino acids, carbon sources, vitamins) along with reducing agents may aid in diverting Acetyl CoA to malonyl CoA or fatty acid biosynthesis, under mixotrophic conditions in Chlorella sorokiniana. Preliminary investigations undertaken with two reducing agents individually (sodium thiosulphate and methyl viologen) along with selected substrates revealed the promise of sodium thiosulphate (1%) in enhancing lipid accumulation significantly. Further, the role of inclusion of twelve substrates and sodium thiosulphate revealed that supplementation with tryptophan (0.1%) recorded 57.28% enhancement in lipid productivity on 4th day. Highest values of lipid productivity of 33% were recorded on 8th day in 0.1% glucose supplemented medium containing sodium thiosulphate. Fatty Acid Methyl Ester (FAME) profiles generated revealed significant reduction in the content of Poly unsaturated fatty acids (PUFA) and enhanced Mono unsaturated fatty acids (MUFA) (especially oleic acid) in the treatments involving tryptophan, Vitamin B12, sodium pyruvate and glucose. This study reveals the promise of using sodium thiosulphate along with selected substrate for enriching the quality and quantity of lipids, which can be valuable for exploiting algae as a source of biodiesel.Not Availabl

    Harnessing the Experience Web to Support User-Generated Product Reviews

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    Proceedings of the 20th International Conference, ICCBR 2012, Lyon, France, September 3-6, 2012.Today, online reviews for products and services have become an important class of user-generated content and they play a valuable role for countless online businesses by helping to convert casual browsers into informed and satisfied buyers. In many respects, the content of user reviews is every bit as important as the catalog content that describes a given product or service. As users gravitate towards sites that offer insightful and objective reviews, the ability to source helpful reviews from a community of users is increasingly important. In this work we describe the Reviewer’s Assistant, a case-based reasoning inspired recommender system designed to help people to write more helpful reviews on sites such as Amazon and TripAdvisor. In particular, we describe two approaches to helping users during the review writing process and evaluate each as part of a blind live-user study. Our results point to high levels of user satisfaction and improved review quality compared to a control-set of Amazon reviews.TS 23.05.1
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