The dynamo bifurcation in rotating spherical shells

We investigate the nature of the dynamo bifurcation in a configuration applicable to the Earth's liquid outer core, i.e. in a rotating spherical shell with thermally driven motions. We show that the nature of the bifurcation, which can be either supercritical or subcritical or even take the form of isola (or detached lobes) strongly depends on the parameters. This dependence is described in a range of parameters numerically accessible (which unfortunately remains remote from geophysical application), and we show how the magnetic Prandtl number and the Ekman number control these transitions.Comment: 16 pages, 14 figure

Design Analysis of a High-Altitude Testing Apparatus

Rocket nozzles are designed to perform best at high altitudes. They do so by employing a high expansion ratio to properly expand the plumb at altitude. In a standard ground test, the exhaust plumb is overexpanded, meaning the relatively high ambient air pressure restricts the plumbs ability to expand to the edge of the nozzle, thus limiting thrust levels. High Altitude Testing (HAT) facilities are able to simulate altitudes of up to 100,000-ft, some even higher. The blowdown ejector style HAT facility employs the use of supersonic diffusers and ejectors to evacuate air and rocket exhaust out of the test section fast enough to create such low pressures. Many variables contribute to how well these facilities will perform, including geometry of the diffuser sections, working fluid characteristics, and ambient conditions. Using various analytical and numerical models, one can characterize and fabricate such a facility to meet predefined standards

Sheath Boundary Effects on the Stability of Hall Plasmas

Plasma devices based on the ExB- field con figuration (where the externally applied electric and magnetic fields are everywhere perpendicular) are used for a variety of applications such as electric propulsion (i.e., Hall thrusters), diagnostic tools (e.g., Penning trap) and plasma processing of materials (i.e., magnetrons). Transverse electron current due to the electric and magnetic forces as well as diamagnetic flows due to the presence of pressure and magnetic field gradients are the sources of gradient-drift instabilities which result in turbulence and anomalous transport (the transport of particles, momentum and energy that cannot be explained by theory). Most investigations into plasma instabilities for various configurations of the fields and plasma parameters have been done under the assumption that the plasma is unbounded and, therefore, in neglect of any boundary effect. However, the presence of physical boundaries may significantly alter the dynamics of the plasma by restricting the parallel electron dynamics and introducing plasma sheath regions (regions where quasi-neutrality is violated) near the walls. Previous works have shown that conservation of charge at the boundary of the plasma affects the instability criteria for the gradient-drift modes as well as result in new instabilities. Effects of the sheath boundary conditions on the instabilities of partially magnetized plasmas are further investigated in this project. It is shown, for the first time, that sheath dissipation results in the instability of the anti-drift mode (i.e. the Simon-Hoh instability) due to the plasma density gradient. It is also shown that sheath dissipation results in a strong instability in conditions where the criterion for the standard Simon-Hoh instability (which results from the difference in electron and ion drifts together with a density gradient) is not satis ed; this result is important as it may provide an explanation for anomalous transport when the Simon-Hoh instability is absent. Then, including the electric potential induced by the sheath as well as the sheath boundary condition, one arrives at a set of two nonlinear ordinary differential equations with a non-local integral condition. The boundary conditions are finally derived consistent with the sheath to fully define the boundary-value problem

Incremental-LDI for Multi-View Coding

International audienceThis paper describes an Incremental algorithm for Layer Depth Image construction (I-LDI) from multi-view plus depth data sets. A solution to sampling artifacts is proposed, based on pixel interpolation (inpainting) restricted to isolated unknown pixels. A solution to ghosting artifacts is also proposed, based on a depth discontinuity detection, followed by a local foreground / background classification. We propose a formulation of warping equations which reduces time consumption, specifically for LDI warping. Tests on Breakdancers and Ballet MVD data sets show that extra layers in I-LDI contain only 10% of first layer pixels, compared to 50% for LDI. I-LDI Layers are also more compact, with a less spread pixel distribution, and thus easier to compress than LDI Visual rendering is of similar quality with I-LDI and LDI

Infant mortality and the role of seigneurial tenure in Canada East, 1851

This paper aims to explain differences in infant mortality across the colony of Quebec, known in the 1850s as Canada East, by institutional settings. Areas settled under French laws (known as seigneurial law) implied important transfers from peasants to landlords through private taxes and duties, restrictions on mobility, scant provision of public goods and disincentives to invest in agricultural productivity. As a result, areas under this law system tended to be poor and prone to high mortality. Upon conquering Quebec, the British maintained French land laws but, in 1791, the boundaries of its application were frozen all newly settled lands would be under British land laws. By 1851, the two legal systems had cohabited for six decades allowing us to compare them. Using the 1851 census, we argue that French seigneurial law which reduced living standards through a variety of channels translated into higher rates of infant mortality. After estimating a Zero-inflated Negative Binomial Regression we find that the effect of seigneurial tenure results in an increase in infant death rates from 43.79 to 44.89 for the age group below one and from 5.21 to 5.277 for the age group from one to five. Additionally, we conduct robustness checks by limiting the sample to large settlements and changing the age groups for the dependent variable

Monopsony and industrial development in nineteenth century Quebec : the impact of seigneurial tenure

We argue that the system of seigneurial tenure used in the province of Quebec until the mid-nineteenth centurya system which allowed significant market power in the establishment of plants, factories and mills, combined with restrictions on the mobility of the labor force within each seigneurial estateis best understood as a system of regionalized monopsonies in the non-farm sector. Seigneurs had incentives to reduce their employment in those sectors to reduce wage rates. We use the fact that later, with the Constitutional Act of 1791, all new settled lands had to be settled under a different system (British land laws). This natural experiment allows us to test our hypothesis that seigneurial tenure was a monopsony, using data from the 1831 and 1851 Lower Canada censuses. We find strong evidence that this difference in tenure partially explains the gap in industrial development between Quebec and the neighboring colony of Ontario

Aisey-et-Richecourt – Ancienne gare

Les récents travaux effectués dans la région de Jussey, pour la rectification et l’aménagement du réseau routier, ont fait apparaître de grandes coupes et décaper des formations quaternaires qui jusqu’alors étaient masquées et difficiles à étudier. La prospection de ces coupes a permis la découverte et la récupération d’un matériel lithique en place à base de quartzites taillés. L’interprétation géologique a bénéficié de la présence de cette industrie paléolithique qui constitue un nouveau re..

Infant mortality and the role of seigneurial tenure in Canada East, 1851

This paper aims to explain differences in infant mortality across the colony of Quebec, known in the 1850s as Canada East, by institutional settings. Areas settled under French laws (known as seigneurial law) implied important transfers from peasants to landlords through private taxes and duties, restrictions on mobility, scant provision of public goods and disincentives to invest in agricultural productivity. As a result, areas under this law system tended to be poor and prone to high mortality. Upon conquering Quebec, the British maintained French land laws but, in 1791, the boundaries of its application were frozen all newly settled lands would be under British land laws. By 1851, the two legal systems had cohabited for six decades allowing us to compare them. Using the 1851 census, we argue that French seigneurial law which reduced living standards through a variety of channels translated into higher rates of infant mortality. After estimating a Zero-inflated Negative Binomial Regression we find that the effect of seigneurial tenure results in an increase in infant death rates from 43.79 to 44.89 for the age group below one and from 5.21 to 5.277 for the age group from one to five. Additionally, we conduct robustness checks by limiting the sample to large settlements and changing the age groups for the dependent variable

Les modèles dans l'éducation : idoles et icônes

Pouvant être comprise à la fois comme point de jonction entre la philosophie et la vie, d’une part, et réflexion présupposée à l’une et l’autre, d’autre part, l’éthique a pour clé l’éducation qui s’efforce de transmettre les meilleures habitudes. La présence et l’effet des modèles, moyens incomplets mais néanmoins profondément influents de cette transmission, suscite l’occasion du questionnement dans ce mémoire : quels sont les bons et les mauvais modèles? Comment façonnent-ils notre vie? Ce travail tente d’amorcer une réponse en explorant l’imitation par laquelle se forgent et se brisent les liens bons ou mauvais entre les humains. Cette exploration vise à dégager sommairement les différences entre des modèles que l’on pourrait dire idoles et d’autres, que l’on pourrait oser appeler icône