6,138 research outputs found
Critical Care's move to fund open access
SCOPUS: ed.jinfo:eu-repo/semantics/publishe
Thermal Enhancement of Interference Effects in Quantum Point Contacts
We study an electron interferometer formed with a quantum point contact and a
scanning probe tip in a two-dimensional electron gas. The images giving the
conductance as a function of the tip position exhibit fringes spaced by half
the Fermi wavelength. For a contact opened at the edges of a quantized
conductance plateau, the fringes are enhanced as the temperature T increases
and can persist beyond the thermal length l_T. This unusual effect is explained
assuming a simplified model: The fringes are mainly given by a contribution
which vanishes when T -> 0 and has a decay characterized by a T-independent
scale
Fine frequency shift of sigle vortex entrance and exit in superconducting loops
The heat capacity of an array of independent aluminum rings has been
measured under an external magnetic field using highly sensitive
ac-calorimetry based on a silicon membrane sensor. Each superconducting vortex
entrance induces a phase transition and a heat capacity jump and hence
oscillates with . This oscillatory and non-stationary behaviour
measured versus the magnetic field has been studied using the Wigner-Ville
distribution (a time-frequency representation). It is found that the
periodicity of the heat capacity oscillations varies significantly with the
magnetic field; the evolution of the period also depends on the sweeping
direction of the field. This can be attributed to a different behavior between
expulsion and penetration of vortices into the rings. A variation of more than
15% of the periodicity of the heat capacity jumps is observed as the magnetic
field is varied. A description of this phenomenon is given using an analytical
solution of the Ginzburg-Landau equations of superconductivity
The tholeiites of the Valaisan domain (Versoyen, western Alps): a Carboniferous magma emplaced in a small oceanic basin
International audienceThe mafic-ultramafic assemblages of the Versoyen complex exposed in the Valaisan domain is close to the boundary between the Internal and the External domains of the western Alps. Zircons extracted from the Versoyen complex suggest an emplacement during Paleozoic times, and probably during the Visean (~337 Ma). The base of the Versoyen complex is formed of laccoliths and sills associated with black shales, while pillow basalts and tuffs predominate at the uppermost levels. Locally, basaltic dikelets intruded leucocratic gneiss. Ultramafic-mafic cumulates form the bottom of the thickest intrusions while diabases are present along the chilled margins. All these rocks have been affected by a polyphased metamorphism under eclogitic to blueschist and greenschist facies conditions. Magmatic textures have been destroyed and the igneous mineralogy is seldom preserved. The mafic rocks of the Versoyen complex show tholeiitic to alkali-transitional affinities. The pillow basalts and the sill cores have flat REE patterns characteristic of N-MORB and T-MORB. Their {varepsilon}Nd (assuming an age of 337 Ma) ratios range from + 5.7 to + 9 which suggest a mixing of N-MORB and OIB sources. The sill margins show Th, U and LREE-enrichments and negative {varepsilon}Nd ratios. These features are likely related to contamination when hot mafic magmas intruded unconsolidated sediments rich in water. The high Th, U, LREE abundances and low {varepsilon}Nd ratio of the basaltic dikelet are probably related to crustal contamination occurring during magma ascent. The geochemical characteristics of the Versoyen rocks are compatible with a tholeiitic magma emplaced into a small oceanic basin in the vicinity of a continent. The importance of pre-Mesozoic crustal thinning evidenced in one segment of the boundary between the Internal and External zones of the Alps suggests that the Pennine Front is an Alpine mega-thrust inherited from a Variscan suture
Critical Care: a good scientific citizen just got better
EditorialSCOPUS: ed.jinfo:eu-repo/semantics/publishe
The energy flux into a fluidized granular medium at a vibrating wall
We study the power input of a vibrating wall into a fluidized granular
medium, using event driven simulations of a model granular system. The system
consists of inelastic hard disks contained between a stationary and a vibrating
elastic wall, in the absence of gravity. Two scaling relations for the power
input are found, both involving the pressure. The transition between the two
occurs when waves generated at the moving wall can propagate across the system.
Choosing an appropriate waveform for the vibrating wall removes one of these
scalings and renders the second very simple.Comment: 5 pages, revtex, 7 postscript figure
The Surviving Sepsis Campaign: raising awareness to reduce mortality
Sepsis affects 18 million people worldwide every year, and on average each case costs more than US$22 000 to treat. Despite this there is no consensus on the clinical definition of sepsis, and successful diagnosis and treatment is difficult. The Barcelona Declaration, issued by the Surviving Sepsis Campaign in October 2002, outlines a six-point plan to reduce the relative mortality of sepsis by 25% over the next 5 years. The Campaign organizers are currently producing evidence-based guidelines on source control and management of sepsis, as well as a policy document on how sepsis is managed around the world
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