On Salem numbers, expansive polynomials and Stieltjes continued fractions

A converse method to the Construction of Salem (1945) of convergent families of Salem numbers is investigated in terms of an association between Salem polynomials and Hurwitz quotients via expansive polynomials of small Mahler measure. This association makes use of Bertin-Boyd's Theorem A (1995) of interlacing of conjugates on the unit circle; in this context, a Salem number $\beta$ is produced and coded by an m-tuple of positive rational numbers characterizing the (SITZ) Stieltjes continued fraction of the corresponding Hurwitz quotient (alternant). The subset of Stieltjes continued fractions over a Salem polynomial having simple roots, not cancelling at $\pm 1$, coming from monic expansive polynomials of constant term equal to their Mahler measure, has a semigroup structure. The sets of corresponding generalized Garsia numbers inherit this semi-group structure.Comment: 35 pages, Journal de Th{\'e}orie des nombres de Bordeaux, Soumissio

Some Paradoxes on the Rates of Certain Currencies and Gold in Time of Crisis

In time of crisis, surprising developments: changes in currency rates can be observed; the large countries which are suffering the most see their respective currencies appreciate while at the same time the gold price decreases. There is an explanation for these paradoxes!

Recherches expérimentales sur des méthodes de nettoyage en milieu liquide

On connaît l'importance des opérations de nettoyage des objets dans toutes les industries confrontées à la contamination particulaire de leurs produits. La plupart des méthodes employées passent par le milieu liquide et l'utilisation des bacs à ultra-sons remplis de fluorocarbonés s'est généralisée dans les années passées. Si on s'interroge sur les raisons du succès de tel ou tel procédé de nettoyage en milieu liquide, on s'aperçoit que l'efficacité n'est pas le seul paramètre pris en compte mais que des considérations, telles que la facilité d'épuration du liquide ou encore le séchage rapide des pièces à leur sortie du bain sont des facteurS qui peuvent emporter la décision. La mauvaise réputation écologique (justifiée ou non) des fréons, amènes les industries à revoir leurs pratiques de nettoyage aux ultra-sons et on s'intéresse de nouveau aux méthodes classiques utilisant des milieux aqueux agités mécaniquement

An Ever-Rebounding Crisis

The current crisis is spreading from the rich countries to those which surround them respectively, countries wherein its degree of gravity is even greater; in turn, that effect sets off a yet stronger backwash in those countries in the Centre, which further aggravates the situation. This reaction is particularly true of the relations between Western and Eastern Europe.Crisis, Protectionism, Change, Countries in the East Europe, Risk, Default in payment

Confluent Thalamic Hyperintensities in CADASIL

Background: CADASIL is responsible for diffuse hyperintensities in the white matter on FLAIR images. These lesions are often associated with focal lesions in the basal ganglia such as lacunar infarctions. The prevalence and significance of diffuse or confluent thalamic hyperintensities (CTH) remain unknown. Methods: The frequency of hyperintensities on FLAIR images in the thalamus was assessed in 147 CADASIL patients, and signal abnormalities on both FLAIR and T(1)-weighted images were categorized as focal/punctuate or diffuse/confluent by the same reader. The areas of increased diffusion were also analyzed on apparent diffusion coefficient maps. The association of CTH with vascular risk factors, the main clinical manifestations of the disease and MRI markers (brain parenchymal fraction, volume of white matter hyperintensities, volume of lacunar infarcts and number of microbleeds) was analyzed with generalized linear regression models. Results: CTH were detected in 12% of the CADASIL subjects in association with hypointensities on T(1)-weighted images. CTH corresponded to areas of increased diffusion apparent diffusion coefficient maps. CTH were found significantly associated with age and independently related to the volume of white matter hyperintensities but not to that of lacunar infarctions or to cerebral atrophy after adjustment for age and sex. No significant association was found between CTH and global cognitive performances. Conclusion: CTH are observed on FLAIR images in a sizeable proportion of CADASIL patients. They are mainly related to the extent of white matter hyperintensities and do not correlate with cognitive decline. Demyelination and/or loss of glial cells appear to be the most plausible cause of these confluent signal changes in the thalamus. Copyright (C) 2010 S. Karger AG, Base

Theoretical frames for the new tasks in career guidance and counseling

Personal and career development interventions aim to help people find answers to personal and career development issues that stem from the societal context in which they live. Societal definitions of these career issues have a double consequence. On the one hand, these issues differ from one culture to another; and, on the other, they evolve along with the contexts in which they are expressed. Implementation of rigorous career development interventions requires, first, a scientific reconstruction of these societal issues and, second, a clear definition of these interventions' goals and ends. Our current view of the societal issues relating to personal and career development interventions may be phrased thus--"How can we help individuals direct their lives, in the (human) society where they interact?" It may be turned into the following scientific question: "What are the factors and processes of life-long self-construction?" An articulation of three major propositions (sociological, cognitive and dynamic) seems to be needed to answer this question. Such a theoretical frame does not allow for a definition of personal and career development interventions ends. In the world of today, the adoption by everyone of a personal ethic of responsibility towards all life on Earth (H. Jonas) could well be a fundamental end to these interventions.Departamento de Psicologí