199,114 research outputs found
Allocution de M. Guillaume Wunsch, président de l'Académie et directeur de la Classe
No full textWunsch Guillaume. Allocution de M. Guillaume Wunsch, président de l'Académie et directeur de la Classe. In: Bulletin de la Classe des lettres et des sciences morales et politiques, tome 14, n°1-6, 2003. pp. 11-12
Needleman-Wunsch algorithm after the generation of the M matrix.
No full textNeedleman-Wunsch algorithm after the generation of the M matrix.</p
Large time behavior in Wasserstein spaces and relative entropy for bipolar drift-diffusion-Poisson models
No full textWe prove asymptotic stability results for nonlinear bipolar drift-diffusion-Poisson Systems arising in semiconductor device modeling and plasma physics in one space dimension. In particular, we prove that, under certain structural assumptions on the external potentials and on the doping profile, all solutions match for large times with respect to all q-Wasserstein distances. We also prove exponential convergence to stationary solutions in relative entropy via the so called entropy dissipation (or Bakry-Émery) method
Inferring causal relations by modelling structures
No full textThis paper provides an overview of structural modelling in its close relation to explanation
and causation. It stems from previous works by the authors and stresses the role
and importance of the notions of invariance, recursive decomposition, exogeneity and
background knowledge. It closes with some considerations about the importance of the
structural approach for practicing scientists
Inferring causality through counterfactuals in observational studies. Some epistemological issues
No full textThis paper contributes to the debate on the virtues and vices of counterfactuals as a basis for causal inference. The goal is to put the counterfactual approach in an epistemological perspective. We discuss a number of issues, ranging from its non-observable basis to the parallelisms drawn between the counterfactual approach in statistics and in philosophy. We argue that the question is not to oppose or to endorse the counterfactual approach as a matter of principle, but to decide what modelling framework is best to adopt depending on the research context
Do we necessarily need longitudinal data to infer causal relations?
No full textIt is generally admitted that causes precede their effects in time. This usually justifies the preference for longitudinal studies over cross-sectional ones, because the former allow the modelling of the dynamic process generating the outcome, while the latter cannot. Supporters of the longitudinal view make two interrelated claims: (i) causal inference requires following the same individuals over time, and (ii) no causal inference can be drawn from cross-sectional data. In this paper, we challenge this view and offer counter-arguments to both claims. We also argue that the possibility of establishing causal relations does not so much depend upon whether we use longitudinal or cross-sectional data, but rather on whether or not the modelling strategy is structural
The decadal mean ocean circulation and Sverdrup balance
No full textElementary Sverdrup balance is tested in the context of the time-average of a 16-year duration time-varying ocean circulation estimate employing the great majority of global-scale data available between 1992 and 2007. The time-average circulation exhibits all of the conventional major features as depicted both through its absolute surface topography and vertically integrated transport stream function. Important small-scale features of the time average only become apparent, however, in the time-average vertical velocity, whether near the surface or in the abyss. In testing Sverdrup balance, the requirement is made that there should be a mid-water column depth where the magnitude of the vertical velocity is less than 10[superscript -8]m/s (about 0.3 m/year displacement). The requirement is not met in the Southern Ocean or high northern latitudes. Over much of the subtropical and lower latitude ocean, Sverdrup balance appears to provide a quantitatively useful estimate of the meridional transport (about 40% of the oceanic area). Application to computing the zonal component, by integration from the eastern boundary is, however, precluded in many places by failure of the local balances close to the coasts. Failure of Sverdrup balance at high northern latitudes is consistent with the expected much longer time to achieve dynamic equilibrium there, and the action of other forces, and has important consequences for ongoing ocean monitoring efforts.United States. National Aeronautics and Space Administration (Contract NNX09AI87G)United States. National Aeronautics and Space Administration (Contract NNX08AV89G
The Practive of Constitutional Development: Vincent Ostrom's Quest to Understand Human Affairs
No full text203-22
On steady linear diffusion-driven flow
No full textWunsch (1970) and Phillips (1970) (Deep-Sea Res. vol. 17, pp. 293, 435) showed that a temperature flux condition on a sloping non-slip surface in a stratified fluid can generate a slow steady upward flow along a thin 'buoyancy layer'. Their analysis is extended here to the more-general case of steady flow in a contained fluid where buoyancy layers may expel or entrain fluid from their outer edge. A compatibility condition that relates the mass flux and temperature gradient along that edge is derived, and this allows the fluid recirculation and temperature perturbation to be determined in the broader-scale 'outer flow' region. The analysis applies when the Wunsch-Phillips parameter R is small, in the linear case for which the density variations are dominated by a constant vertical gradient
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
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