Louis Lavelle : la philosophie, chemin de sagesse

Pour Louis Lavelle qui voulait écrire De la sagesse comme un couronnement de son oeuvre, la question de la sagesse se trouve au centre même de la philosophie. Le sage s’interroge sur le sens de l’existence. Par la sagesse, l’homme, être libre et temporel, choisit les possibles qui le rapprochent de l’Être. La sagesse lavellienne est une sagesse de l’amour, de l’esprit et de l’être. L’ami de la sagesse, homme de raison et d’intériorité, découvre dans l’amour la cime et l’essence des valeurs. La pensée lavellienne de la sagesse, gravitant autour de la notion d’esprit, unit des sources bibliques, spirituelles, mystiques à des sources purement philosophiques. À la fois théorique et pratique, cultivant un idéal grec de modération et de mesure, la sagesse aspire à la lumière de la présence.For Louis Lavelle who wanted to write De la sagesse as a crowning of his work, the question of wisdom stands in the very centre of philosophy. The wise questions the meaning of existence. Thanks to wisdom, man, a free and temporal being, chooses the possible realities that bring him closer to Being. Wisdom in Lavelle’s sense is a wisdom of love, of mind and of being. The friend of wisdom, a man of reason and interiority, discovers in love the summit and the essence of values. Lavelle’s thought on wisdom, gravitating around the notion of mind, brings together biblical, spiritual, mystic sources and purely philosophical sources. Both theoretical and practical, cultivating a Greek ideal of moderation and measure, wisdom aspires to the light of presence

Transitional Interface: Concept, Issues and Framework

Transitional Interfaces have emerged as a new way to interact and collaborate between different interaction spaces such as Reality, Virtual Reality and Augmented Reality. In this paper we explore this concept further. We introduce a descriptive model of the concept, its collaborative aspect and how it can be generalized to describe natural and continuous transitions between contexts (e.g. across space, scale, viewpoint, and representation)

Self-affine surface morphology of plastically deformed metals

We analyze the surface morphology of metals after plastic deformation over a range of scales from 10 nm to 2 mm, using a combination of atomic force microscopy and scanning white-light interferometry. We demonstrate that an initially smooth surface during deformation develops self-affine roughness over almost four orders of magnitude in scale. The Hurst exponent $H$ of one-dimensional surface profiles is initially found to decrease with increasing strain and then stabilizes at $H \approx 0.75$. By analyzing their statistical properties we show that the one-dimensional surface profiles can be mathematically modelled as graphs of a fractional Brownian motion. Our findings can be understood in terms of a fractal distribution of plastic strain within the deformed samples

La pensée sapientielle de Pascal

Passionné de vérité, Pascal est aussi en quête de sagesse. Il trouve dans la Bible la source d’une pensée du cœur, attentive au mystère, qui donne sa place à l’inquiétude spirituelle. La vraie sagesse naît de l’écoute de la Parole. Si elle est utile, la sagesse profane demeure impuissante à saisir la plénitude de la vérité. La pensée sapientielle de Pascal, de nature exis­tentielle, tragique, se centre sur le Christ qui illumine secrètement l’hu­maine condition. Exégétique, cette pensée trouve une issue à l’impasse philosophique dans le séjour à l’intérieur du texte sacré. La sagesse d’ins­piration biblique ordonne la raison à l’amour. La pensée sapientielle de Pascal ne peut se dissocier de l’expérience incandescente du Mémorial. C’est une pensée du témoignage, vibrante d’un humanisme lucide et poi­gnant. Sans juste langage il n’est de véritable sagesse. La pensée sapientielle de l’auteur de l’Apologie de la religion chrétienne prend l’inoubliable coloration du poème

Multifaceted contributions : health workers and smallpox eradication in India

Smallpox eradication in South Asia was a result of the efforts of many grades of health-workers. Working from within the confines of international organisations and government structures, the role of the field officials, who were of various nationalities and also drawn from the cities and rural enclaves of the countries in these regions, was crucial to the development and deployment of policies. However, the role of these personnel is often downplayed in official histories and academic histories, which highlight instead the roles played by a handful of senior officials within the World Health Organization and the federal governments in the sub-continent. This article attempts to provide a more rounded assessment of the complex situation in the field. In this regard, an effort is made to underline the great usefulness of the operational flexibility displayed by field officers, wherein lessons learnt in the field were made an integral part of deploying local campaigns; careful engagement with the communities being targeted, as well as the employment of short term workers from amongst them, was an important feature of this work

A Study of the Accuracy of Mass-Radius Relationships for Silicate-Rich and Ice-Rich Planets up to 100 Earth Masses

A mass-radius relationship is proposed for solid planets and solid cores ranging from 1 to 100 Earth-mass planets. It relies on the assumption that solid spheres are composed of iron and silicates, around which a variable amount of water is added. The M-R law has been set up assuming that the planetary composition is similar to the averaged composition for silicates and iron obtained from the major elements ratio of 94 stars hosting exoplanets. Except on Earth for which a tremendous amount of data is available, the composition of silicate mantles and metallic cores cannot be constrained. Similarly, thermal profiles are poorly known. In this work, the effect of compositional parameters and thermal profiles on radii estimates is quantified. It will be demonstrated that uncertainties related to composition and temperature are of second order compared to the effect of the water amount. The Super-Earths family includes four classes of planets: iron-rich, silicate-rich, water-rich, or with a thick atmosphere. For a given mass, the planetary radius increases significantly from the ironrich to the atmospheric-rich planet. Even if some overlaps are likely, M-R measurements could be accurate enough to ascertain the discovery of an earth-like planet .The present work describes how the amount of water can be assessed from M-R measurements. Such an estimate depends on several assumptions including i) the accuracy of the internal structure model and ii) the accuracy of mass and radius measurements. It is shown that if the mass and the radius are perfectly known, the standard deviation on the amount of water is about 4.5 %. This value increases rapidly with the radius uncertainty but does not strongly depend on the mass uncertainty.Comment: In press in The Astrophysical Journa

Electron irradiation: from test to material tayloring

In this article, we report some examples of how high-energy electron irradiation can be used as a tool for shaping material properties turning the generation of point-defects into an advantage beyond the presumed degradation of the properties. Such an approach is radically different from what often occurs when irradiation is used as a test for radiation hard materials or devices degradation in harsh environments. We illustrate the potential of this emerging technique by results obtained on two families of materials, namely semiconductors and superconductors

The Interior Dynamics of Water Planets

The ever-expanding catalog of detected super-Earths calls for theoretical studies of their properties in the case of a substantial water layer. This work considers such water planets with a range of masses and water mass fractions (2 to 5 M_Earth, 0.02% to 50% H2 O). First, we model the thermal and dynamical structure of the near-surface for icy and oceanic surfaces, finding separate regimes where the planet is expected to maintain a subsurface liquid ocean and where it is expected to exhibit ice tectonics. Newly discovered exoplanets may be placed into one of these regimes given estimates of surface temperature, heat flux, and gravity. Second, we construct a parameterized convection model for the underlying ice mantle of higher ice phases, finding that materials released from the silicate iron core should traverse the ice mantle on the timescale of 0.1 to 100 megayears. We present the dependence of the overturn times of the ice mantle and the planetary radius on total mass and water mass fraction. Finally, we discuss the implications of these internal processes on atmospheric observables.Comment: 9 page 4 figure

Mass-radius relationships for exoplanets

For planets other than Earth, interpretation of the composition and structure depends largely on comparing the mass and radius with the composition expected given their distance from the parent star. The composition implies a mass-radius relation which relies heavily on equations of state calculated from electronic structure theory and measured experimentally on Earth. We lay out a method for deriving and testing equations of state, and deduce mass-radius and mass-pressure relations for key materials whose equation of state is reasonably well established, and for differentiated Fe/rock. We find that variations in the equation of state, such as may arise when extrapolating from low pressure data, can have significant effects on predicted mass- radius relations, and on planetary pressure profiles. The relations are compared with the observed masses and radii of planets and exoplanets. Kepler-10b is apparently 'Earth- like,' likely with a proportionately larger core than Earth's, nominally 2/3 of the mass of the planet. CoRoT-7b is consistent with a rocky mantle over an Fe-based core which is likely to be proportionately smaller than Earth's. GJ 1214b lies between the mass-radius curves for H2O and CH4, suggesting an 'icy' composition with a relatively large core or a relatively large proportion of H2O. CoRoT-2b is less dense than the hydrogen relation, which could be explained by an anomalously high degree of heating or by higher than assumed atmospheric opacity. HAT-P-2b is slightly denser than the mass-radius relation for hydrogen, suggesting the presence of a significant amount of matter of higher atomic number. CoRoT-3b lies close to the hydrogen relation. The pressure at the center of Kepler-10b is 1.5+1.2-1.0 TPa. The central pressure in CoRoT-7b is probably close to 0.8TPa, though may be up to 2TPa.Comment: Added more recent exoplanets. Tidied text and references. Added extra "rock" compositions. Responded to referee comment