Initiating scientific collaborations across career levels and disciplines – a network analysis on behavioral data

International Journal of Computer-Supported Collaborative Learning - Collaborations are essential in research, especially in answering increasingly complex questions that require integrating...     

Supporting activity modelling from activity traces

We present a new method and tool for activity modelling through qualitative sequential data analysis. In particular, we address the question of constructing a symbolic abstract representation of an activity from an activity trace. We use knowledge engineering techniques to help the analyst build an ontology of the activity, that is, a set of symbols and hierarchical semantics that supports the construction of activity models. The ontology construction is pragmatic, evolutionist and driven by the analyst in accordance with their modelling goals and their research questions. Our tool helps the analyst define transformation rules to process the raw trace into abstract traces based on the ontology. The analyst visualizes the abstract traces and iteratively tests the ontology, the transformation rules and the visualization format to confirm the models of activity. With this tool and this method, we found innovative ways to represent a car‐driving activity at different levels of abstraction from activity traces collected from an instrumented vehicle. As examples, we report two new strategies of lane changing on motorways that we have found and modelled with this approach.     

(Nano)Fibrillar morphology development in biobased poly(butylene succinate-co-adipate)/poly(amide-11) blown films

Thin films with (nano)fibrillar morphologies were successfully obtained in fully-biobased poly(butylene succinate-co-adipate)/poly(amide-11) blends (PBSA/PA11, 85/15 wt/wt) using an extrusion-blowing process. Impacts of PA11 grade and take-up ratio on the morphology of PBSA/PA11 were particularly highlighted. Scanning electron microscopy analyses indicated that PA11 with high melt volume-flow rates are beneficial to the development of (nano)fibrillar morphologies in PBSA/PA11 blown film. On the contrary, unstable film blowing processing without fibrillar morphologies was attested for PA11 with low melt volume-flow rates. Increasing the take-up ratio during extrusion-blowing of PBSA/PA11 clearly generates finer PA11 (nano)fibrils into PBSA. Fibril diameters down to 300 nm could be reached with an optimal PA11 grade promoting enhanced mechanical properties (higher ductility and toughness). The formation of stable PA11 (nano)fibrils into PBSA is discussed via rheological assessments of viscosity/elasticity ratio. A specific attention was finally paid to the PBSA strain-hardening behavior in PBSA/PA11 using elongational rheological tests. PA11 (nano)fibrillation helps maintaining the strong PBSA strain-hardening and thus play a major role on the processability of PBSA/PA11 blends by extrusion blowing. As a conclusion, the PA11 grade represents a crucial parameter to control the production of PBSA/PA11 blown films with refined (nano)fibrillar structures and enhanced physico-chemical properties.     

Catalytic Performance of Nanoscale‐Corrugated Gold and Silver Films for Surface‐Enhanced Chemiluminescence

Biochips of corrugated gold and silver displaying surface plasmon resonance at different energies are fabricated to determine the nature of the mechanism responsible for the surface‐enhanced chemiluminescence (SECL) of luminol. This Full Paper proves that, whereas silver possesses the strongest resonance and the greatest plasmon overlap with luminol emission, silver is also the metal that induces the lowest CL enhancement (two orders of magnitude less than gold). Therefore, the enhancement mechanism is not related to plasmon‐assisted processes but rather originates from catalytic properties induced by corrugation of the metal film.     

Toward Docking‐Based Virtual Screening for Discovering Antitubulin Agents by Targeting Taxane and Colchicine Binding Sites

Docking‐based virtual screening : Flexible docking, scoring, and virtual screening of ligand databases are on the way to fulfilling the promise. Docking‐based virtual screening that targets taxane and colchicine binding sites will certainly provide new antitubulin agents.

     

Unsupported Ni/Mo(W)S2 Catalysts from Hexamethylenediammonium Thiometallates Precursors: In Situ Activation During the HDS of DBT

Unsupported Ni/MoS₂ and Ni/WS₂ HDS catalysts were prepared by in situ activation of hexamethylenediammonium thiometallates promoted with Ni. The method involved an aqueous solution reaction of ammonium thiomolybdate (ATM) or ammonium thiotungstate (ATT) with Ni(NO₃)₂·6H₂O and hexamethylenediamine. Ni-promoted precursors were then in situ activated during the hydrodesulfurization (HDS) of dibenzothiophene (DBT) producing Ni/MoS₂ and Ni/WS₂ catalysts. Solids were analyzed after the in situ activation by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and for textural properties by using the BET and BJH methods. Catalysts with relatively high surface area and type IV N₂ adsorption–desorption isotherms were obtained. The use of the hexamethylenediammonium precursor led to a significant nickel promotion of MoS₂ and WS₂ catalysts. For Ni/MoS₂, the use of this carbon-containing precursor was found to be more beneficial for the final HDS catalytic activity than using the classical ammonium tetrathiomolybdate (ATM) without carbon. For Ni/WS₂, compared to tetraalkylammonium thiosalts, the lower amount of carbon in excess formed during the decomposition of the hexamethylenediammonium precursor coupled with a lower crystallization rate of WS₂ favors a correct nickel accommodation on the WS₂ edges.     

Crack tip enrichment in the XFEM using a cutoff function

We consider a variant of the eXtended Finite Element Method (XFEM) in which a cutoff function is used to localize the singular enrichment surface. The goal of this variant is to obtain numerically an optimal convergence rate while reducing the computational cost of the classical XFEM with a fixed enrichment area. We give a mathematical result of quasi‐optimal error estimate. One of the key points of this paper is to prove the optimality of the coupling between the singular and the discontinuous enrichments. Finally, we present some numerical computations validating the theoretical result. These computations are compared with those of the classical XFEM and a non‐enriched method. Copyright © 2008 John Wiley & Sons, Ltd.     

Preparation and catalytic activity of nanostructured Pd catalysts supported on hydrogenotitanate nanotubes

Nanostructured palladium particles (nanorods, icosahedra, cubes) were synthesized in aqueous solution using a seeding-mediated approach with a structure-directing agent. These nanostructured Pd particles were then impregnated onto hydrogenotitanate nanotubes using two different impregnation procedures. The as-prepared catalysts were then tested in the selective hydrogenation of cinnamaldehyde at 323 K under 10 bars of H₂. The selectivity is influenced by the morphology of the Pd nanostructured particles with a higher selectivity into saturated alcohols when the proportion of (111) Pd sites increases.     

Testing bibliometric indicators by their prediction of scientists promotions

We have developed a method to obtain robust quantitative bibliometric indicators for several thousand scientists. This allows us to study the dependence of bibliometric indicators (such as number of publications, number of citations, Hirsch index...) on the age, position, etc. of CNRS scientists. Our data suggests that the normalized h-index (h divided by the career length) is not constant for scientists with the same productivity but different ages. We also compare the predictions of several bibliometric indicators on the promotions of about 600 CNRS researchers. Contrary to previous publications, our study encompasses most disciplines, and shows that no single indicator is the best predictor for all disciplines. Overall, however, the Hirsch index h provides the least bad correlations, followed by the number of papers published. It is important to realize however that even h is able to recover only half of the actual promotions. The number of citations or the mean number of citations per paper are definitely not good predictors of promotion. Due to space constraints, this paper is a short version of a more detailed article. [JENSEN & AL., 2008B]     

Incidence structures and Stone–Priestley duality

We observe that if R: = (I,ρ, J) is an incidence structure, viewed as a matrix, then the topological closure of the set of columns is the Stone space of the Boolean algebra generated by the rows. As a consequence, we obtain that the topological closure of the collection of principal initial segments of a poset P is the Stone space of the Boolean algebra Tailalg (P) generated by the collection of principal final segments of P, the so-called tail-algebra of P. Similar results concerning Priestley spaces and distributive lattices are given. A generalization to incidence structures valued by abstract algebras is considered.