298 research outputs found
Emile Borel's difficult days in 1941
The German forces occupying Paris arrested Emile Borel and three other
members of the Acad\'emie des Sciences in October 1941 and released them about
five weeks later. Why? We examine some relevant German and French archives and
other sources and propose some hypotheses. In the process, we review how the
Occupation was structured and how it dealt with French higher education and
some French mathematicians
The emergence of French statistics. How mathematics entered the world of statistics in France during the 1920s
This paper concerns the emergence of modern mathematical statistics in France
after the First World War. Emile Borel's achievements are presented, and
especially his creation of two institutions where mathematical statistics was
developed: the {\it Statistical Institute of Paris University}, (ISUP) in 1922
and above all the {\it Henri Poincar\'e Institute} (IHP) in 1928. At the IHP, a
new journal {\it Annales de l'Institut Henri Poincar\'e} was created in 1931.
We discuss the first papers in that journal dealing with mathematical
statistics
Optimal control for rough differential equations
In this note, we consider an optimal control problem associated to a
differential equation driven by a H\"{o}lder continuous function g of index
greater than 1/2. We split our study in two cases. If the coefficient of dg\_t
does not depend on the control process, we prove an existence theorem for a
slightly generalized control problem, that is we obtain a literal extension of
the corresponding deterministic situation. If the coefficient of dg\_t depends
on the control process, we also prove an existence theorem but we are here
obliged to restrict the set of controls to sufficiently regular functions.Comment: 13 page
Biosynthesis of α-Tocopherol and Plastoquinone-9 in spinach chloroplasts
Prenylation and methylation reaction in al biosynthesis is localized in the
envelope membranes of the chloroplasts, while PQ-9 biosynthesis takes place in
the envelope membranes and also in the thylakoid membranes. The sequence in a-T
biosynthesis in spinach is (see also Figure 1): Homogentisate + Phytyl-PP —> Me-6-PQH?—> 2,3-Me2PQH?—>γ J ->a T ; for the PQ-9 biosynthesis it is: Homogentisate
+ Solanesyf-PP4-> Me-6-SQH2—> PQH2
The ghosts of the Ecole Normale. Life, death and legacy of Ren\'e Gateaux
The present paper deals with the life and some aspects of the scientific
contributions of the mathematician Ren\'e Gateaux, killed during World War 1 at
the age of 25. Though he died very young, he left interesting results in
functional analysis. In particular, he was among the first to try to construct
an integral over an infinite dimensional space. His ideas were extensively
developed later by Paul L\'evy. Among other things, L\'evy interpreted
Gateaux's integral in a probabilistic framework that later contributed to the
construction of the Wiener measure. This article tries to explain this singular
personal and professional destiny in pre- and postwar France
Au delà des réels. Borel et l'approche probabiliste de la réalité
Nous examinons dans cet article la manière singulière dont Emile Borel, à partir de ses études sur la structure des nombres réels et un certain rejet de la vision abstraite de Cantor, a trouvé dans le calcul des probabilités un outil adéquat pour formuler une nouvelle approche des problèmes, en même temps prenait conscience de son utilité pour l'approche des phénomènes de la physique et de la société
- …