The End of Prisons: Reflections from the Decarceration Movement

Book review of The End of Prisons: Reflections from the Decarceration Movement, edited by Mechtild E. Nagel and Anthony J. Nocella (2013)

The End of Prisons: Reflections from the Decarceration Movement

Book review of The End of Prisons: Reflections from the Decarceration Movement, edited by Mechtild E. Nagel and Anthony J. Nocella (2013)

Courbes d'écoulement dans les systèmes de mélange : vers une approche simplifiée

National audienceLe comportement rhéologique de fluides cisaillés dans des géométries de mélange est étudié à partir d'une procédure simplifiée de calcul de la vitesse de cisaillement. L'applicabilité de cette procédure est examinée dans le cas de fluides newtoniens et non newtoniens, en s'intéressant à l'influence de la géométrie de mélange. Les résultats sont favorablement comparés à ceux issues de la littérature. On montre ainsi que cette procédure permet de s'affranchir de la détermination préalable d'un rayon virtuel nécessaire à l'application de l'analogie de Couette, ainsi que du choix à priori du comportement rhéologique du fluide cisaillé

High torque vane rheometer for concrete: principle and validation from rheological measurements

International audienceA high torque vane rheometer is used to measure the yield stress of cement-based materials. It is shown that this apparatus is suitable for the evaluation of the yield stress of various concretes and mortars in the fresh state in comparison with slump tests realized with ASTM Abrams cone. Then, the rheological properties (yield stress and shear flow behaviour) of a homogeneous kaolin clay suspension are studied with the apparatus and favourably compared with other rheometers and geometries

EVENT MODEL: A ROBUST BAYESIAN TOOL FOR CHRONOLOGICAL MODELING

We propose a new modeling approach for combining dates through the Event model by using hierarchical Bayesian statistics. The Event model aims to estimate the date of a context (unit of stratification) from individual dates assumed to be contemporaneous and which are affected by errors of different types: laboratory and calibration curve errors and also irreducible errors related to contaminations, taphonomic disturbances, etc, hence the possible presence of outliers. The Event model has a hierarchical structure which makes it possible to distinguish between date of an Event and dates of the artifacts involved. Prior information on the individual irreducible errors is introduced using a uniform shrinkage density with minimal assumptions about Bayesian parameters. The model is extended in the case of stratigraphic sequences which involve several Events with temporal order constraints (relative dating). Calculations are based on MCMC numerical techniques and can be performed using the ChronoModel software which is freeware, open source and cross-platform. This modeling provides a very simple way to automatically penalize outlying data without having to remove them from the dataset. This approach is compared to alternative approaches implemented in Oxcal or BCal software: we show that the Event model is more robust but generally yields less precise credibility intervals. Mathematical formulations are explained in detail and comparisons are done thanks to synthetic examples. Three application examples are shown: the radiocarbon dating of the shroud of Turin, the dating of a medieval potter's kiln in Lezoux (Auvergne, France) by using radiocarbon, archaeomagnetism and thermoluminescence, and the OSL dating of the Shi'bat Dihya 1 sequence in Wadi Surdud middle paleolithic complex (western Yemen)

Shear flow curve in mixing systems--A simplified approach

The original contribution is available at http://www.sciencedirect.com/science/article/pii/S0009250908004545International audienceRheological behaviour of fluids in mixing systems was studied using a simplified approach in shear rate calculation. The efficiency of this approach is investigated from Newtonian and non-Newtonian fluids, exploring also the geometry of mixing systems. Results are favourably compared with those obtained from previous published works. It is shown that this approach does not require the calculation of a virtual inner radius nor a priori assumption of the rheological behaviour of the fluid mixed

SCC flow curves from vane geometry rheometer

International audienceThe objective of the present study is to show how recording the changes in the rotation torque according to the rotation speed can lead to identifying a characteristic flow curve for the tested concrete. The concrete rheometer used for the study is composed of a vane tool. The rotation speed of the tool is imposed and the resulting torques are measured. The experimental rotation protocol used in this study corresponds to a rapid speed increase followed by a steady speed then the rotation speed slows down. The evolution of the torque measured as the rotation speed decrease (restructuring phase) is considered as being a succession of stationary states. By considering the fluid equivalent to a Bingham fluid for which the yield stress has already been identified and by using an analogy with a coaxial-cylinders rheometer, relevant relationships between the rotation speed of the vane and the rate of shearing along the tool are identified. Shear stress and shear rate calculations for each value of torque and rotation speed lead to the complete flow curve of the tested fluid. The data treatment method is adjusted to accurately evaluate the parameter linked to the flow stop in the case of a non-nil shear rate when the yield stress is reached. The comparison of the characteristic rheological parameters of SCC obtained from the rheometer and both spreading and V-Funnel tests indicate very satisfactory correlations

Navigating Pre-Hospital End of Life Care: A Paramedic Perspective

End of life care (EoLC) issues in the Canadian healthcare system are now commonplace. Palliative care and medical assistance in dying (MAID) programs are giving patients more options than ever before. Consequently, pre-hospital and community paramedicine programs now interact with more patients who require EoLC

Extension of spread-slump formulae for yield stress evaluation

International audienceThis paper provides a new model to evaluate the yield stress of suspensions, slurries or pastes, based on the release of a finite volume of material onto a horizontal surface. Considering the height (h) and the radius (R) of the sample at the flow stoppage, two asymptotic regimes, where h higher than R or h lower than R, lead to different analytical models that allow the determination of yield stress. Experimental observations show typical sample shape at stoppage between slump and spread. Based on these observations, we have developed a new analytical model to evaluate accurately the yield stress of materials in this intermediate regime. The validity of this model was evaluated from data obtained using various Carbopol® dispersions. The yield stress measured with the proposed model was compared with the yield stress evaluated from shear flow curves obtained with roughened plate/plate geometry fitted to the Herschel-Bulkley model. Results show the relevance of the proposed model which that can be applied in the range between models used for the two asymptotic regimes

Posterior archaeomagnetic dating: An example from the Early Medieval site Thunau am Kamp, Austria

International audienceThe Early Medieval valley settlement of Thunau am Kamp in Lower Austria has been under archaeological excavation for 10 years. The site was occupied during the 9th and 10th centuries AD according to potsherds, which seem to indicate two phases of activity: in the older phase ovens were placed in the corners of houses while during the younger phase they are found in the middle of the wall. The present study has been conducted in order to increase the archaeomagnetic database and fill the temporal gap around 900 AD. For this purpose 14 ovens have been sampled for their paleaomagnetic signals. Laboratory treatment generally confirmed that the baked clay has preserved stable directions. Apart from one exception, all the mean characteristic remanent magnetisation directions are concentrated on the Early Medieval part of the directional archaeomagnetic reference curve of Austria at about 900 AD. Using this curve archaeomagnetic dating provides ages between 800 and 1100 AD, which are in agreement with the archaeological dating. Together with the archaeological age estimates and stratigraphic information the new data have been included into the database of the Austrian curve and it has been recalculated using a new version of RenCurve. The new data confine the curve and its error band considerably in the time interval 800 to 1100 AD. This calibration process also provides probability density distributions for each included structure, which allows for posterior dating and refines temporal errors considerably. Because such dating includes archaeological information it is not an independent age estimate but is a combination of all available dating method