60,443 research outputs found
Inhomogenous electronic structure, transport gap, and percolation threshold in disordered bilayer graphene
The inhomogenous real-space electronic structure of gapless and gapped
disordered bilayer graphene is calculated in the presence of quenched charge
impurities. For gapped bilayer graphene we find that for current experimental
conditions the amplitude of the fluctuations of the screened disorder potential
is of the order of (or often larger than) the intrinsic gap induced by
the application of a perpendicular electric field. We calculate the crossover
chemical potential, , separating the insulating regime from a
percolative regime in which less than half of the area of the bilayer graphene
sample is insulating. We find that most of the current experiments are in the
percolative regime with . The huge suppression of
compared with provides a possible explanation for
the large difference between the theoretical band gap and the
experimentally extracted transport gap.Comment: 5 Pages, 2 figures. Published versio
No Escape
The initial idea for the film came from an inspiring performance of Chaplin's Easy Street (1917) accompanied by Donald MacKenzie, resident organist at the Odeon Leicester Square, which led me into researches of early cinema (c1895-1907), a period described by Tom Gunning as the âcinema of attractionsâ. James Lastra points out that during this time competition between cinemas was based on the success of various sound strategies all emphasising the âlivenessâ of the film experience and films were made to motivate particular types of sound accompaniment.
Particularly intriguing was the use of live sound effects performed by a skilled troupe from behind the film screen to produce ârealisticâ sound effects. This is translated in No Escape into the manipulation of on-screen diegetic sound, also inspired by Pierre Schaeffer's musique concrĂšte and his notions of the sound object and reduced listening. The interaction between the live piano and the onscreen sound is crucial to No Escape as is that of the piano and images, which exist alone together for long stretches.
The visual content and structure of the film draws on the city symphonies of Walter Ruttman and especially Dziga Vertov whose formal experimentation, startling juxtaposition of images and very rapid editing is important to No Escapeâs non-narrative and at times complex montage of British rural and urban vistas. Vertovâs Man with a Movie Camera (1929) is by and partially about the man with the camera as is No Escape, the title of which refers to the idea that though we may travel to get away from something, there is no escape from the inner life. This is represented by the piano music, which varies but within fairly restricted limits. It does respond or drive image choice and editing but the overall sense should be that one cannot escape and these responses are temporary and fleeting
Extrapolating from Tom Gunning's cinema of attractions, James Beattie's concept of âdocumentary displayâ - a poetic, sensual and subjective approach which encourages listening and looking rather than cognitive understanding - underpins the aesthetic of No Escape, as is a belief in the supremacy of sound and of film as a performative event
Involvement of leukotriene pathway in the pathogenesis of ischemia-reperfusion injury and septic and non-septic shock.
The 5-lipoxygenase (5-LO) pathway is responsible for the production of leukotrienes (LTs), inflammatory lipid mediators which play a role in innate immunity. More recently, a pivotal role of LTs in ischemia-reperfusion and shock injury has been suggested. In fact, these pathological conditions are characterized by a severe neutrophil infiltration that gives rise to tissue injury and 5-LO metabolites control neutrophil recruitment in injured tissue by the modulation of adhesion molecule expression. The aim of this review is to analyze the results reported in the literature on the role of 5-LO pathway, with particular regard to LTs, in these pathological conditions. A better understanding of the mechanisms underlying the role of the 5-LO enzyme and/or its metabolites in the regulation of neutrophil trafficking, might open new perspectives in the therapy of organ dysfunction and/or injury associated with shock and ischemia-reperfusion injury
Extension of the C star rotation curve of the Milky Way to 24 kpc
Demers and Battinelli published, in 2007 the rotation curve of the Milky Way
based on the radial velocity of carbon stars outside the Solar circle. Since
then we have established a new list of candidates for spectroscopy. The goal of
this paper is to determine the rotation curve of the galaxy, as far as possible
from the galactic center, using N type carbon stars. The stars were selected
from their dereddened 2MASS colours, then the spectra were obtained with the
Dominion Astrophysical Observatory and Asiago 1.8 meter telescopes. This
publication adds radial velocities and Galactrocentric distances of 36 carbon
stars, from which 20 are new confirmed. The new results for stars up to 25 kpc
from the galactic center, suggest that the rotation curve shows a slight
decline beyond the Solar circle.Comment: 13 pages, 3 figures, 1 table; accepted for publication in
Astrophysic
A mixed integer linear programming heuristics for computing nonstationary (s,S) policy parameters
Making Fanaroff-Riley I radio sources. Numerical Hydrodynamic 3D Simulations of Low Power Jets
Extragalactic radio sources have been classified into two classes,
Fanaroff-Riley I and II, which differ in morphology and radio power. Strongly
emitting sources belong to the edge-brightened FR II class, and weakly emitting
sources to the edge-darkened FR I class. The origin of this dichotomy is not
yet fully understood. Numerical simulations are successful in generating FR II
morphologies, but they fail to reproduce the diffuse structure of FR Is.
By means of hydro-dynamical 3D simulations of supersonic jets, we investigate
how the displayed morphologies depend on the jet parameters. Bow shocks and
Mach disks at the jet head, which are probably responsible for the hot spots in
the FR II sources, disappear for a jet kinetic power L_kin < 10^43 erg/s. This
threshold compares favorably with the luminosity at which the FR I/FR II
transition is observed.
The problem is addressed by numerical means carrying out 3D HD simulations of
supersonic jets that propagate in a non-homogeneous medium with the ambient
temperature that increases with distance from the jet origin, which maintains
constant pressure.
The jet energy in the lower power sources, instead of being deposited at the
terminal shock, is gradually dissipated by the turbulence. The jets spread out
while propagating, and they smoothly decelerate while mixing with the ambient
medium and produce the plumes characteristic of FR I objects.
Three-dimensionality is an essential ingredient to explore the FR I evolution
because the properties of turbulence in two and three dimensions are very
different, since there is no energy cascade to small scales in two dimensions,
and two-dimensional simulations with the same parameters lead to FRII-like
behavior.Comment: 11 pages, 12 figures, to appear on A&
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