A one dimensional model for the prediction of extraction yields in a two phases modified twin-screw extruder

Solid/liquid extraction is performed on raw plant substrate with a modified twin-screw extruder (TSE) used as a thermo-mecanochemical reactor. Visual observations and experimental residence time distributions (RTD) are used to develop a solid transport model based on classical chemical engineering method. Modeled and experimental residence times are compared. The transport model is then coupled with a reactive extraction model in order to predict extraction yields

Une approche de la théorie institutionnelle à la réglementation de l'audit légale et statutaire

En tant que cadre d'analyse, la théorie institutionnelle a été utilisée pour expliquer les différentes manières que les organisations développent et évoluent à travers le temps, en réponse à différents types de pressions institutionnelles. Cet article contribue à la littérature de la théorie institutionnelle de plusieurs façons. Tout d'abord, l'objet de l'étude est sur les récents changements dans les structures de régulation de l'audit légale et statutaire, une fonction importante dans le capitalisme contemporain. Deuxièmement, nous étendons la théorie institutionnelle par le biais d'une analyse comparative internationale des changements dans les structures de réglementation de l'audit légale et statutaire aux Etats-Unis, la France et le Canada. Troisièmement, d'une manière analogue à Dillard et al. (2004), nous étendons la théorie institutionnelle à travers une plus grande focalisation sur les aspects politiques de changement institutionnel en ce qui concerne la réglementation de l'audit légale et statutaire. Notre constat est qu'il y a eu des changements significatifs dans les structures de réglementation de l'audit légale et statutaire au cours des dernières années, entraînant une augmentation des niveaux d'isomorphisme institutionnel. Pressions, surtout à l'extérieur de cadres réglementaires nationaux, ont abouti à un plus grand légalisme dans la régulation de l'audit légale et statutaire dans les trois pays étudiés. La mondialisation des marchés de capitaux internationaux explique en partie ce phénomène, mais l'isomorphisme coercitif et isomorphisme mimétique sont également considérés comme jouant un rôle important dans ce processus.Audit légale et statutaire; réglementation; la théorie institutionnelle

Further developments in stress initialization in geomechanics via FEM and a two-step procedure involving airy functions

The in-situ stress field in rock masses is a key aspect when a numerical analysis of a rock mass is carried out in any area of geo-engineering, such as civil, mining, or Oil & Gas. A method for the numerical generation of the in-situ stress state in the FE context, based on Airy stress functions was previously introduced. It involves two steps: 1) an estimate of the stress state at each Gauss point is generated, and 2) global equilibrium is verified and re-balancing nodal forces are applied as needed. In this paper, new developments towards improving the accuracy of the stress proposal are discussed. A real application example has been used to illustrate the results achieved with the new implementation

Two phase residence time distribution in a modified twin screw extruder

Biomass fractionation is performed with a modified Clextral twin-screw extruder used as a thermo-mechano-chemical reactor. This new process is firstly analyzed. Visual observations, residence time distributions, and global mass balances are used to obtain information about the process phenomena and their coupling. Residence time distributions (RTD) classical models are adopted to represent the experimental plots. The influence of continuous and discrete process parameters upon the RTD of the solid and liquid phases is analyzed

Coil embolization of a gluteal false aneurysm in a patient with Marfan syndrome

AbstractThe classic cardiovascular complications of Marfan syndrome are annuloaortic ectasia, mitral valve disease, and aortic dissection. These conditions can be explained by a progressive loss of connective tissue elastic fibers of the inner arterial wall that lead to its fragility and distensibility. Other aneurysmal locations have been reported in relation to this condition, though clearly less frequently. We report here the case of a patient with Marfan syndrome who successively had annuloaortic ectasia and Barlow's disease, which were successfully treated in 1987, a false aneurysm on the reimplantation of the right coronary artery that necessitated reintervention in 1992, and a gluteal false aneurysm diagnosed and treated in 1993

Evaluation and selection of indicators for land degradation and desertification monitoring : methodological approach

International audienceAn approach to derive relationships for defining land degradation and desertification risk and developing appropriate tools for assessing the effectiveness of the various land management practices using indicators is presented in the present paper. In order to investigate which indicators are most effective in assessing the level of desertification risk, a total of 70 candidate indicators was selected providing information for the biophysical environment , socioeconomic conditions, and land management characteristics. The indicators were defined in 1,672 field sites located in 17 study areas in the Mediterranean region, Eastern Europe, Latin America, Africa, and Asia. Based on an existing geo-referenced database, classes were designated for each indicator and a sensitivity score todesertification was assigned to each class based on existing research. The obtained data were analyzed for the various processes of land degradation at farm level. The derived methodology was assessed using independent indicators, such as the measured soil erosion rate, and the organic matter content of the soil. Based on regression analyses, the collected indicator set can be reduced to a number of effective indicators ranging from 8 to 17 in the various processes of land degradation. Among the most important indicators identified as affecting land degradation and desertification risk were rain seasonality, slope gradient,plant cover, rate of land abandonment, land-use intensity, and the level of policy implementation

Constraining late-time transitions in the dark energy equation of state

One of the most compelling goals of observational cosmology is the characterisation of the properties of the dark energy component thought to be responsible for the recent acceleration of the universe, including its possible dynamics. In this work we study phenomenological but physically motivated classes of models in which the dark energy equation of state can undergo a rapid transition at low redshifts, perhaps associated with the onset of the acceleration phase itself. Through a standard statistical analysis we have used low-redshift cosmological data, coming from Type Ia supernova and Hubble parameter measurements, to set constraints on the steepness of these possible transitions as well as on the present-day values of the dark energy equation of state and in the asymptotic past in these models. We have also studied the way in which these constraints depend on the specific parametrisation being used. Our results confirm that such late-time transitions are strongly constrained. If one demands a matter-like pre-transition behaviour, then the transition is constrained to occur at high redshifts (effectively in the matter era), while if the pre-transition equation of state is a free parameter then it is constrained to be close to that of a cosmological constant. In any case, the value of dark energy equation of state near the present day must also be very similar to that of a cosmological constant. The overall conclusion is that any significant deviations from this behaviour can only occur in the deep matter era, so there is no evidence for a transition associated with the onset of acceleration. Observational tools capable of probing the dynamics of the universe in the deep matter era are therefore particularly important.Comment: 9 pages, 7 figures; Astronomy & Astrophysics (in press