Steady and unsteady inundation modeling based on high resolution topographic data

Poster (2010, April 22)

Steady state and (bi-) stability evaluation of simple protease signalling networks

in Biosystems (2007), 90(3), 591-601

Signal transduction networks are complex, as are their mathematical models. Gaining a deeper understanding requires a system analysis. Important aspects are the number, location and stability of steady ... [more ▼]

Signal transduction networks are complex, as are their mathematical models. Gaining a deeper understanding requires a system analysis. Important aspects are the number, location and stability of steady states. In particular, bistability has been recognised as an important feature to achieve molecular switching. This paper compares different model structures and analysis methods particularly useful for bistability analysis. The biological applications include proteolytic cascades as, for example, encountered in the apoptotic signalling pathway or in the blood clotting system. We compare three model structures containing zero-order, inhibitor and cooperative ultrasensitive reactions, all known to achieve bistability. The combination of phase plane and bifurcation analysis provides an illustrative and comprehensive understanding of how bistability can be achieved and indicates how robust this behaviour is. Experimentally, some so-called "inactive" components were shown to have a residual activity. This has been mostly ignored in mathematical models. Our analysis reveals that bistability is only mildly affected in the case of zero-order or inhibitor ultrasensitivity. However, the case where bistability is achieved by cooperative ultrasensitivity is severely affected by this perturbation. (c) 2007 Elsevier Ireland Ltd. All rights reserved. [less ▲]

Steak up to the horns: Conventionalisation of Organic stock farming: knowledge's lock-in in the agrifood chain.

in GeoJournal (2008), 73(1), 31-44

Recent conversations concerning organic food systems have focused on the conventionalization hypothesis, which posits that the organic food sector has become increasingly bifurcated between “historical” ... [more ▼]

Recent conversations concerning organic food systems have focused on the conventionalization hypothesis, which posits that the organic food sector has become increasingly bifurcated between “historical” players in the organic movement on one side, and on the other by distributors and industrial operators recently arrived in the sector, who practice a more conventionalized form of organic agriculture which is now on the ascendancy. The most prominent explanations for the growth and dominance of a conventionalized organic food system have been economic, based in the logics of input costs, especially land rent. We use the cases of the Belgian Blue commodity system and the Belgian organic beef commodity system to argue that conventionalization is also cognitive. To understand the role of cognition in the ascendance of the conventional organic food sector, we utilize concept of “référentiel”—or system of cognitive references—as developed by Muller and Jobert. We believe that comparing organic and conventional practices as two systems of cognitive references makes a deeper understanding of conventionalization possible in two ways: first because it makes it clear that the two systems coexist on a cognitive level, understood in a broad sense as tightly knit sets of knowledges, beliefs, standards, and images. Secondly, the concept of référentiel enables one to understand how the conventional system can become irreversible (lock-in effect) and thus incompatible with the development of the organic system. [less ▲]

Stealth macromolecular platforms for the design of MRI blood pool contrast agents

in Polymer Chemistry (2011), 2(10), 2316-2327

Stealth macromolecular platforms bearing alkyne groups and poly(ethylene oxide) brushes were synthesized by reversible addition fragmentation chain transfer (RAFT) polymerization. The anchoring of Gd3 ... [more ▼]

Stealth macromolecular platforms bearing alkyne groups and poly(ethylene oxide) brushes were synthesized by reversible addition fragmentation chain transfer (RAFT) polymerization. The anchoring of Gd3+-chelates bearing an azide group was then carried out by the Huisgen 1,3-dipolar cycloaddition (“click”) reaction in mild conditions, leading to macrocontrast agents for MRI applications. The gadolinium complex is hidden in the PEO shell that renders the macrocontrast agents free of any cytotoxicity and stealth to proteins of the immune system. Relaxometry measurements have evidenced an improved relaxivity of the macrocontrast agent compared to ungrafted gadolinium chelate. Moreover, this relaxivity is further enhanced when the spacer length between the Gd3+-chelate and the polymer backbone is shorter, as the result of its decreased tumbling rate. These novel products are therefore promising candidates for MRI applications. [less ▲]

La steam explosion : application en tant que prétraitement de la matière cellulosique

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2010), 14(Spécial N°2),

Steam explosion is a thermomechanochemical process which allows the breakdown of lignocellulosic structural components by steam heating, hydrolysis of glycosidic bonds by organic acid formed during the ... [more ▼]

Steam explosion is a thermomechanochemical process which allows the breakdown of lignocellulosic structural components by steam heating, hydrolysis of glycosidic bonds by organic acid formed during the process and shearing forces due to the expansion of the moisture. The process is composed of two distinct stages: vapocracking and explosive decompression. Cumul effects of both phases include modification of the physical properties of the material (specific surface area, water retention capacities, color, cellulose cristallinity rate,…), hydrolysis of hemicellulosic components (mono and oligosaccharides released) and modification of the chemical structure of lignin. These effects permit the opening of lignocellulosic structures and increase the enzymatic hydrolysis rate of cellulose components in the aim to obtain fermentable sugars used in second generation biofuels or high value-added molecules process. [less ▲]

STEAM EXPLOSION : PROCESS AND IMPACT ON LIGNOCELLULOSIC MATERIAL

Poster (2012, March 01)

Steam explosion is a thermomechanochemical process which allows the breakdown of lignocellulosic structural components by steam heating, hydrolysis of glycosidic bonds by organic acid formed during the ... [more ▼]

Steam explosion is a thermomechanochemical process which allows the breakdown of lignocellulosic structural components by steam heating, hydrolysis of glycosidic bonds by organic acid formed during the process and shearing forces due to the expansion of the moisture. The process is composed of two distinct stages: vapocracking and explosive decompression. Cumul effects of both phases include modification of the physical properties of the material (specific surface area, water retention capacities, color, cellulose crystallinity rate,…), hydrolysis of hemicellulosic components (mono and oligosaccharides released) and modification of the chemical structure of lignin. These effects permit the opening of lignocellulosic structures and increase the enzymatic hydrolysis rate of cellulose components in the aim to obtain fermentable sugars used in second generation biofuels process. [less ▲]

Steam explosion, application en tant que prétraitement de la matière ligno-cellulosique en vue de l’obtention de sucres fermentescibles, valorisables dans les unités de production de biocarburants de deuxième génération ou de molécules à haute valeur ajoutée.

Scientific conference (2012, March 23)

Steatosis-induced proteomic changes in liver mitochondria evidenced by two-dimensional differential in-gel electrophoresis

in Journal of Proteome Research (2005), 4(6), 2024-2031

Steatosis encompasses the accumulation of droplets of fats into hepatocytes. In this work, we performed a comparative analysis of mitochondrial protein patterns found in wild-type and steatosis-affected ... [more ▼]

Steatosis encompasses the accumulation of droplets of fats into hepatocytes. In this work, we performed a comparative analysis of mitochondrial protein patterns found in wild-type and steatosis-affected liver using the novel technique two-dimensional differential in-gel electrophoresis (2D-DIGE). A total of 56 proteins exhibiting significant difference in their abundances were unambiguously identified. Interestingly, major proteins that regulate generation and consumption of the acetyl-CoA pool were dramatically changed during steatosis. Many proteins involved in the response to oxidative stress were also affected. [less ▲]

A steel beam element accounting for the cross section deformation

in Proceedings of the 3rd DIANA World Conferences - Finite Elements in Civil Engineering Applications (2002)

Classical beam elements are based on the assumption that the cross section of the element re-mains unchanged during the entire loading. However, this can be too simple for modeling the behavior of thin ... [more ▼]

Classical beam elements are based on the assumption that the cross section of the element re-mains unchanged during the entire loading. However, this can be too simple for modeling the behavior of thin-walled steel profiles, where local and distortional buckling are likely to occur. In this perspective, a spe-cial element taking into account the deformation of the cross section is presented and some examples of com-putations of critical bifurcation loads are presented. [less ▲]

Steel construction and sustainability

Conference (2009, July 10)