Collective dynamics of chemically active particles trapped at a fluid interface

Chemically active colloids generate changes in the chemical composition of their surrounding solution and thereby induce flows in the ambient fluid which affect their dynamical evolution. Here we study the many-body dynamics of a monolayer of active particles trapped at a fluid-fluid interface. To this end we consider a mean-field model which incorporates the direct pair interaction (including also the capillary interaction which is caused specifically by the interfacial trapping) as well as the effect of hydrodynamic interactions (including the Marangoni flow induced by the response of the interface to the chemical activity). The values of the relevant physical parameters for typical experimental realizations of such systems are estimated and various scenarios, which are predicted by our approach for the dynamics of the monolayer, are discussed. In particular, we show that the chemically-induced Marangoni flow can prevent the clustering instability driven by the capillary attraction.Comment: 8 pages, 2 figure

An integration of partial evaluation in a generic abstract interpretation framework

Information generated by abstract interpreters has long been used to perform program specialization. Additionally, if the abstract interpreter generates a multivariant analysis, it is also possible to perform múltiple specialization. Information about valúes of variables is propagated by simulating program execution and performing fixpoint computations for recursive calis. In contrast, traditional partial evaluators (mainly) use unfolding for both propagating valúes of variables and transforming the program. It is known that abstract interpretation is a better technique for propagating success valúes than unfolding. However, the program transformations induced by unfolding may lead to important optimizations which are not directly achievable in the existing frameworks for múltiple specialization based on abstract interpretation. The aim of this work is to devise a specialization framework which integrates the better information propagation of abstract interpretation with the powerful program transformations performed by partial evaluation, and which can be implemented via small modifications to existing generic abstract interpreters. With this aim, we will relate top-down abstract interpretation with traditional concepts in partial evaluation and sketch how the sophisticated techniques developed for controlling partial evaluation can be adapted to the proposed specialization framework. We conclude that there can be both practical and conceptual advantages in the proposed integration of partial evaluation and abstract interpretation

La réforme pénale et la réciprocité des droits

This letter deals with two major questions. The first shows how the “program” of criminology which emerged in the 19th century contributes to a neutralisation of the impact of discussions concerning human rights in the case of punishment. To do this, the author compares two paradigms of penal reform. The second question tries to clarify the relations established in Quebec between the rights of prisoners and abolitionist alternatives from 1975 on

La réforme pénale au Canada : l’apport de la Commission canadienne sur la détermination de la peine

This study is a critical analysis of the penal reform project put forward by the Canadian Commission on Sentencing from the point of view of moderation. The author first considers the Commission's position in the penological debate between the Medical Model and the Justice Model. He then analyses the “new theory on sanctions” proposed by the Commission, as well as its position on “community measures” and on the ideal of rehabilitation. Finally, his analysis focuses on a number of the Commission's major recommendations for reform, its policy in terms of maximum and minimum sentences, the new “exceptional sentence” (intended to replace the present measures regarding “dangerous criminals”), its position on imprisonment of “twenty-five years' minimum” and its general guidelines for Canada. In conclusion, the author make an evaluation of the orientation of the Commission's reform with respect to the principle of moderation