Measurement of the conductance of a hydrogen molecule

Recent years have shown steady progress in research towards molecular electronics [1,2], where molecules have been investigated as switches [3-5], diodes [6], and electronic mixers [7]. In much of the previous work a Scanning Tunnelling Microscope was employed to address an individual molecule. As this arrangement does not provide long-term stability, more recently metal-molecule-metal links have been made using break junction devices [8-10]. However, it has been difficult to establish unambiguously that a single molecule forms the contact [11]. Here, we show that a single H2 molecule can form a stable bridge between Pt electrodes. In contrast to results for other organic molecules, the bridge has a nearly perfect conductance of one quantum unit, carried by a single channel. The H2-bridge provides a simple test system and a fundamental step towards understanding transport properties of single-molecule devices.Comment: 6 pages, 4 figure

International Geomagnetic Reference Field: the eleventh generation

The eleventh generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2009 by the International Association of Geomagnetism and Aeronomy Working Group V-MOD. It updates the previous IGRF generation with a definitive main field model for epoch 2005.0, a main field model for epoch 2010.0, and a linear predictive secular variation model for 2010.0-2015.0. In this note the equations defining the IGRF model are provided along with the spherical harmonic coefficients for the eleventh generation. Maps of the magnetic declination, inclination and total intensity for epoch 2010.0 and their predicted rates of change for 2010.0-2015.0 are presented. The recent evolution of the South Atlantic Anomaly and magnetic pole positions are also examine

International Geomagnetic Reference Field: the eleventh generation

The eleventh generation of the International Geomagnetic Reference Field (IGRF)was adopted in December 2009 by the International Association of Geomagnetism and AeronomyWorking Group V-MOD. It updates the previous IGRF generation with a definitive main field model for epoch 2005.0, a main field model for epoch 2010.0, and a linear predictive secular variation model for 2010.0–2015.0. In this note the equations defining the IGRF model are provided along with the spherical harmonic coefficients for the eleventh generation. Maps of the magnetic declination, inclination and total intensity for epoch 2010.0 and their predicted rates of change for 2010.0–2015.0 are presented. The recent evolution of the South Atlantic Anomaly and magnetic pole positions are also examined

Montlleó (Prats i Sansor, Cerdanya). El primer jaciment magdalenià a l'aire lliure en altitud al cor dels Pirineus

El jaciment de Montlleó ha estat una de les grans novetats del Paleolític Superior pirinenc en general i català en particular dels darrers anys. La seva localització a la Cerdanya ja era un repte per si mateix, i l'antiguitat que ens han marcat el material arqueològic i el radiocarboni ens ha confirmat el seu interès cabdal. Aquest treball és, de fet, la primera notícia extensa que es publica, després de les primeres campanyes d'excavacions entre 2000 i 2003. Descriurem el procés de descobriment del jaciment, fet per un dels signants de l'article (JG), l'entorn en el qual es troba i els primers resultats cronoculturals i socioeconòmics que ens ha ofert

Montlleó (Prats i Sansor, Cerdanya). Balanç de 10 campanyes d'excavació

El jaciment a l'aire lliure de Montlleó es troba a l'indret conegut com a coll de Saig, al terme municipal de Prats i Sansor (Cerdanya, Lleida). L'assentament, situat a 1.134 m sobre el nivell del mar, les coordenades UTM del qual són: 31T0402920/4691129. Es localitza al voltant d'un petit aflorament rocós de conglomerats d'edat postmiocènica, corresponent a les restes d'un paleocanal d'un ventall al·luvial; aquest recobria unes argiles grises d'origen lacustre, amb abundants restes vegetals fòssils en el mateix coll de Saig, i amb intercalacions de lignits del Miocè. Els conglomerats, al damunt de les argiles molt toves, formen una petita taula amb un escarpament més pronunciat cap a l'est, al peu del qual hi reconeixem l'emplaçament arqueològic