A Framework for the Generation of Adaptive Courses Based on Semantic Metadata

This approach proposes the creation and management of adaptive learning systems by combining component technology, semantic metadata, and adaptation rules. A component model allows interaction among components that share consistent assumptions about what each provides and each requires of the other. It allows indexing, using, reusing, and coupling of components in different contexts powering adaptation. Our claim is that semantic metadata are required to allow a real reusing and assembling of educational component. Finally, a rule language is used to define strategies to rewrite user query and user model. The former allows searching components developing concepts not appearing in the user query but related with user goals, whereas the last allow inferring user knowledge that is not explicit in user model.John Freddy Duitama received his M.Sc. degree in system engineering from the University of Antioquia -Colombia (South America). He is currently a doctoral candidate in the GET – Institut National des Télécommunications, Evry France. This work is sponsored by the University of Antioquia, where he is assistant professor.His research interest includes semantic web and web-based learning systems, educational metadata and learning objects.Bruno Defude received his Ph.D. in Computer Science from the University of Grenoble (I.N.P.G) in 1986. He is currently Professor in the Department of Computer Science at the GET - Institut National des Télécommunications, Evry France where he leads the SIMBAD project (Semantic Interoperability for MoBile and ADaptive applications).His major field of research interest is databases and semantic web, specifically personalized data access, adaptive systems, metadata, interoperability and semantic Peer-to-peer systems with elearning as a privileged application area.He is a member of ACM SIGMOD.Amel Bouzeghoub received a degree of Ph.D. in Computer Sciences at Pierre et Marie Curie University, France.In 2000, she joined the Computer Sciences Department of GET-INT (Institut National des Telecommunications) at Evry (France) as an associate professor.Her research interests include topics related to Web-based Learning Systems, Semantic Metadata for learning resources, Adaptive Learning Systems and Intelligent Tutoring Systems.Claire Lecocq received an Engineer Degree and a Ph.D. in Computer Sciences respectively in 1994 and 1999. In 1997, she joined the Computer Sciences Department at GET-INT (Institut National des Télécommunications) of Evry, France, as an associate professor. Her first research interests included spatial databases and visual query languages. She is now working on adaptive learning systems, particularly on semantic metadata and user models.     

A new family of synthetic diterpenes that regulates cytokine synthesis by inhibiting IkappaBalpha phosphorylation

The synthesis and the biological evaluation of a new family diterpenes are presented. The synthetic studies were inspired by the structural framework of acanthoic acid (1) and yielded a family of compounds that were evaluated as anti-inflammatory agents. Among them, compounds 2, 10, 12, and 16 exhibited a very low nonspecific cytotoxicity and inhibited the synthesis of TNF-alpha with greater than 65 % efficacy at low micromolar concentrations. Cytokine-specificity studies revealed that these compounds also inhibited the synthesis of the proinflammatory cytokines IL-1beta and IL-6, while inhibition of IL-1ra and IL-8 synthesis was marginal and only occurred at high concentrations. Further studies, through EMSA and Western blot analyses, indicated that these compounds decreased the extent of phosphorylation of IkappaBalpha; this suggests that they exert their anti-inflammatory profile by inhibiting NF-kappaB-mediated cytokine synthesis. These findings imply that these diterpenes represent promising leads for the development of novel anti-inflammatory agents.     

Determining Price Levels and Product Mix in a Rolling Mill: A Case Study

The decision model presented in this paper maximizes the firm's overall profit margin in a direct costing system. Price-demand relationships have to be considered for all combinations of sales markets and product groups. Because of the special structure of the production process, the problem can be formulated as a dynamic programming model, which yields detailed results for every product group and global results for every production unit.     

Rat liver messenger ribonucleic acid and enzyme activity of 6-phosphofructo 2-kinase/fructose 2,6-bisphosphatase impairment during the late period of pregnancy

Fructose 2,6-bisphosphate concentration, 6-phosphofructo 2-kinase/fructose 2,6-bisphosphatase (PFK-2/FBPase2) activity, and messenger RNA decreased in maternal rat liver during the last days of gestation, and the recovery started after delivery. Phospho(enol)pyruvate carboxykinase activity and messenger RNA increased in contrast to PFK-2 changes. Measurement of the glycolytic capacity in isolated hepatocytes prepared from rats 1 h after parturition showed a low glucose consumption and an impaired capacity to metabolize glucose. These results stress the relevance of the PFK-2/fructose 2,6-bisphosphate system in the control of the glycolytic flux in liver, and these changes are intended to prevent glucose consumption by maternal liver and contribute to allow gluconeogenesis to proceed at the end of gestation. The physiological basis of this adaptation may lay on the diversion of glucose from maternal to fetal metabolism.     

The influence of wort aeration and yeast preoxygenation on beer staling processes

The influence of oxygen on the beer staling process is considered to be of major importance. Therefore, the impact of wort aeration, which is thought to cause wort oxidation processes, on beer ageing, has been examined. Pilsner and ale beers were produced with the classical wort aeration technique or by the use of the yeast preoxygenation process, in which yeast cells are exposed to oxygen before fermentation. The staling of these beers was studied using P&T GC–MS and sensory analysis. GC–MS analyses of the natural and forced aged beers showed no significant differences between the two treatments. Sensory evaluation of natural and forced beers confirmed these results. Thus, normal wort aeration (8 mg/l) does not appear to determine flavour stability in a direct manner. This is probably due to the short contact of the wort with oxygen at low temperatures before the onset of fermentation.     

Thermal Transport in Disordered Materials

ABSTRACT

We review the status of research on thermal/phonon transport in disordered materials. The term disordered materials is used here to encompass both structural and compositional disorder. It includes structural deviations ranging from an ideal crystal with disordered arrangements of defects all the way to fully amorphous materials, as well as crystals with impurities up through multi-component random alloys. Both types of disorder affect phonons by breaking the symmetry of an idealized crystal and changing their character/mode shapes. These effects have important implications with regard to phonon–phonon interactions, phonon transport and phonon interactions with other quantum particles, which are being actively investigated. Herein, we synthesize the current theoretical understanding, identify the aspects of the problem that require more work, and pose open questions. Abbreviations: BTE: Boltzmann transport equation; DFT: Density functional theory; EPP: Eigenvector periodicity parameter; FAFDTR: Fiber-aligned frequency domain thermoreflectance; GK: Green–Kubo; GKMA: Green–Kubo modal analysis; HCACF: Heat current autocorrelation function; IXS: Inelastic X-ray scattering; LD: Lattice dynamics; LJ: Lennard–Jones; MD: Molecular dynamics; MFP: Mean free path; NEMD: Non-equilibrium molecular dynamics; NMD: Normal-mode dynamics; PDL: Propagon, diffuson, locon; PGM: Phonon gas model; PR: Participation ratio; SCLD: Supercell lattice dynamics; SED: Spectral energy density; TDTR: Time-domain thermoreflectance; VCA: Virtual crystal approximation;     

Conjugated Porous Polymers Based on BODIPY and BOPHY Dyes in Hybrid Heterojunctions for Artificial Photosynthesis

Developing highly efficient photocatalysts for artificial photosynthesis is one of the grand challenges in solar energy conversion. Among advanced photoactive materials, conjugated porous polymers (CPPs) possess a powerful combination of high surface areas, intrinsic porosity, cross-linked nature, and fully π-conjugated electronic systems. Here, based on these fascinating properties, organic–inorganic hybrid heterostructures composed of CPPs and TiO₂ for the photocatalytic CO₂ reduction and H₂ evolution from water are developed. The study is focused on CPPs based on the boron dipyrromethene (BODIPY) and boron pyrrol hydrazine (BOPHY) families of compounds. It is shown that hybrid photocatalysts are active for the conversion of CO₂ mainly into CH₄ and CO, with CH₄ production 4 times over the benchmark TiO₂. Hydrogen evolution from water surpassed by 37.9-times that of TiO₂, reaching 200 mmol g_cat⁻¹ and photonic efficiency of 20.4% in the presence of Pt co-catalyst (1 wt% Pt). Advanced photophysical studies, based on time-resolved photoluminescence and transient absorption spectroscopy, reveal the creation of a type II heterojunction in the hybrids. The unique interfacial interaction between CPPs and TiO₂ results in longer carriers’ lifetimes and a higher driving force for electron transfer, opening the door to a new generation of photocatalysts for artificial photosynthesis.     

New results on the polymerisation of the itaconic acid in aqueous medium

Summary Itaconic acid has been polymerised in aqueous medium using potassium persulphate as initiator. An important dependence on the polymer yield with the initial pH of the reaction medium is observed. Polymers obtained on this work showed to be mainly atactic, with around 1.14 of polydispersity and molecular weight around 5 × 10⁵ ,g/mol. All the Polymers synthesized were characterized by FTIR, ¹H-NMR, ¹³C-NMR, gpc, thermogravimetry and acid number. Analysis of these materials seem to indicate a decrease of acidity related to the lost of one carboxylic group from the itaconic acid residue, probably due to intramolecular interactions when the monomer is incorporated into the polyiner growing chain. Received: 22 April 2002/Revised Version: 15 August 2002/ Accepted: 16 August 2002 RID="1*" ID="1*"Universidad del País Vasco, Facultad de Ciencias, Departamento de Química Bilbao, Espa?ia. Correspondence to Cristóbal Lárez V     

On the modification of photocatalysts for improving visible light and UV degradation of gas-phase toluene over TiO2

The photocatalytic behavior of different TiO₂-based photocatalysts was reported for gas-phase toluene removal under both UV and visible light illumination, and compared to that of commercial P25 (Degussa) TiO₂. Promotion by sulfates and the use of nanosized anatase TiO₂ were reported to strongly increase the toluene removal efficiency under UV illumination. Nanosized-anatase was prepared by a protecting group sol–gel synthesis using hexamethyldisilazane as crystallite growth inhibitor. Sulfates played a double positive role, with photogenerated electrons transfer effects limiting charge recombination and as repulsive species for strongly adsorbed aromatic intermediates that act as poisons. The decrease in particle size obtained on nanosized anatase TiO₂ (5 nm) yielded a considerable enhancement in the toluene removal efficiency. Pure high surface area rutile has been synthesized at low temperature by a polyethylenglycol-containing sol–gel method for visible light activation purposes. A two-way semiconductor coupling phenomenon, consisting of a reciprocal electron/hole transfer between two visible light-activated oxides, rutile TiO₂ and WO₃, was proposed to explain the large gain in efficiency when adding low amounts of WO₃ to rutile TiO₂.