Una herborització a Montserrat a la primavera de 1860

Aquest article tracta sobre una herborització duta a terme a la muntanya de Montserrat (Barcelona) l?any 1860. Són interessants tant l?antiguitat de les citacions de les 124 espècies que s?hi relacionen, com el personatge que va fer l?herborització: John Stuart Mill. Es tracta d?un intel·lectual anglès ben conegut pels seus treballs en el camp de la filosofia i l?economia, però l?activitat botànica del qual ha passat desapercebuda. Amb aquest treball pretenem realçar la faceta inèdita d?un home del qual prompte es commemorarà el segon centenari del seu naixement.The present article describes botanical observations made on the mountain of Montserrat (Barcelona) in 1860. They are of interest not only for the early records of the 124 species listed but also for the identity of the author: John Stuart Mill was an English intellectual well known for his contributions in the field of philosophy and economics but his botanical activity has remained unnoticed. We show this unknown facet of a man whose bicentenary will be soon commemorated.El presente artículo trata sobre una herborización llevada a cabo en la montaña de Montserrat (Barcelona) en el año 1860. Resultan interesantes tanto la antigüedad de las citas de las 124 especies que se relacionan, como el personaje que hizo la herborización: John Stuart Mill. Se trata de un intelectual inglés bien conocido por sus trabajos en el campo de la filosofía y la economía pero cuya actividad botánica ha pasado desapercibida. Pretendemos realzar una faceta inédita en un hombre del que pronto se conmemorará el segundo centenario de su nacimiento

Dialogue des droits et dialogue des traditions juridiques

Le premier paradoxe du droit est d'être un " indéfinissable concret " : chacun sait de quoi il s'agit mais aucune entente n'existe pour le définir. En effet, le droit est l'élément d'appréhension de la réalité sociale le plus concret, tant pour les acteurs que pour les observateurs. Au moment où les codes sociaux non juridiques s'effacent devant l'individualisme, le droit est précisément ce qui permet à l'acteur de s'appuyer sur des règles tangibles

Polarisation control of linear dipole radiation using spin-momentum locking of light

We experimentally demonstrate that a linear dipole is not restricted to emit linearly polarised light, provided it is embedded in the appropriate nanophotonic environment. We observe emission of various elliptical polarisations by a linear dipole including circularly polarised light, without the need for birefringent components. We further show that the emitted state of polarisation can theoretically span the entire Poincare sphere. The experimental demonstration is based on elongated gold nanoparticles (nanorods) deposited on an optical nanofibre and excited by a free-space laser beam. The light directly collected in the guided mode of the nanofibre is analysed in regard to the azimuthal position and orientation of the nanorods, observed by means of scanning electron microscopy. This work constitutes a demonstration of the mapping between purely geometrical degrees of freedom of a light source and all polarisation states and could open the way to new methods for polarisation control of light sources at the nanoscale.Comment: 5 pages, 4 figure

Functional ecology of the biological soil crust in semiarid SE Spain: sun and shade populations of Diploschistes diacapsis (Ach.) Lumbsch

The Tabernas badlands in semiarid south-east Spain is one of the driest regions in Europe with a mean annual precipitation of c. 240 mm. The landscape is deeply dissected, with canyons, ramblas and sparsely vegetated eroded badland slopes. The vegetation is predominantly a biological soil crust consisting of different types of lichen-rich communities, one of the more conspicuous being dominated by Diploschistes diacapsis (Ach.) Lumbsch. This lichen is mainly restricted to the north- facing slopes, where it forms extensive whitish carpets and probably plays an important role in preventing erosion of the slopes and allowing plant colonization. South-facing slopes are much more eroded and generally lack vegetation. %The photosynthetic performance of north (shade) and south-facing (sun) populations of D. diacapsis was studied to determine if these different populations showed any adaptations to the microclimatic conditions of their individual habitats. The response of CO2 exchange to light intensity, temperature and water content was measured under controlled conditions in the laboratory. Dry weight-based net photosynthetic rates were higher in the southern-exposed population but quantum efficiency, and light compensation points were similar. Thallus weight per unit area (LMA) was considerably higher for shade specimens but maximum water content and optimal water content were very similar and chlorophyll content on a dry weight basis was also similar. Chlorophyll content on an area basis was higher in the northern-exposed population and always much larger than those reported in other studies on the same species (up to 8 times larger) with the result that NP values on a chlorophyll basis were relatively low. The larger LMA meant that shade thalli stored more water per unit area which should ensure longer active periods than sun thalli. The results support a strategy pair of high NP and short active time versus low NP and long active time, both having been reported for other soil crust species. However, the visibly larger biomass of the shade D. diacapsis suggests that the lichen is at the limit of its adaptability in these habitats