3,983 research outputs found
Pseudospin Magnetism in Graphene
We predict that neutral graphene bilayers are pseudospin magnets in which the
charge density-contribution from each valley and spin spontaneously shifts to
one of the two layers. The band structure of this system is characterized by a
momentum-space vortex which is responsible for unusual competition between band
and kinetic energies leading to symmetry breaking in the vortex core. We
discuss the possibility of realizing a pseudospin version of ferromagnetic
metal spintronics in graphene bilayers based on hysteresis associated with this
broken symmetry.Comment: 5 pages, 4 figures; added figure 1, modified introduction and
discussion; updated reference
The Role of Electron-electron Interactions in Graphene ARPES Spectra
We report on a theoretical study of the influence of electron-electron
interactions on ARPES spectra in graphene that is based on the
random-phase-approximation and on graphene's massless Dirac equation continuum
model. We find that level repulsion between quasiparticle and plasmaron
resonances gives rise to a gap-like feature at small k. ARPES spectra are
sensitive to the electron-electron interaction coupling strength and might enable an experimental determination of this material parameter.Comment: 5 Pages, 4 Figures, Submitte
Characterisation of Hybrid Pixel Detectors with capacitive charge division
In order to fully exploit the physics potential of the future high energy e+
e- linear collider, a Vertex Tracker providing high resolution track
reconstruction is required. Hybrid pixel sensors are an attractive technology
due to their fast read-out capabilities and radiation hardness. A novel pixel
detector layout with interleaved cells between the readout nodes has been
developed to improve the single point resolution. The results of the
characterisation of the first processed prototypes are reported.Comment: 5 pages, 2 figures, presented at LCWS2000, Linear Collider Workshop,
October 24-28 2000, Fermi National Accelerator Laboratory, Batavia, Illinois,
U.S.A. Proceedings to be published by the American Institute of Physic
Hybrid Pixel Detector Development for the Linear Collider Vertex Tracker
In order to fully exploit the physics potential of the future high energy
e+e- linear collider, a Vertex Tracker able to provide particle track
extrapolation with very high resolution is needed. Hybrid Si pixel sensors are
an attractive technology due to their fast read-out capabilities and radiation
hardness. A novel pixel detector layout with interleaved cells has been
developed to improve the single point resolution. Results of the
characterisation of the first processed prototypes by electrostatic
measurements and charge collection studies are discussed.Comment: 5 pages, 1 figure, to appear in the Proceedings of the 9th Int.
Workshop on Vertex Detectors, Lake Michigan MI (USA), September~200
Antihypertensive drug class and dyslipidemia: risk association among Chinese patients with uncomplicated hypertension
Factors associated with dyslipidemia in Chinese patients with uncomplicated hypertension were investigated in 1,139 patients newly prescribed a single antihypertensive drug in the public primary healthcare setting in Hong Kong, where their fasting lipid profiles were measured 4 to 16 weeks after the first prescription. Multivariate logistic regression showed that thiazide users were more likely (OR 3.67, 95% C.I. 1.13, 11.88, p=0.030) to have adverse (> 6.2mmol/l) total cholesterol (TC) compared with drugs acting on the renin angiotensin system (RAS), but the absolute difference in mean TC between thiazide users and all patients was small ( 0.14 mmol/l), while advanced age and male gender were also associated with some aspects of dyslipidemia. Clinicians should be aware of the increased risk of dyslipidemia in these groups, but the mild dyslipidemic profile associated with thiazides should not in itself deter its use as a possible first-line antihypertensive agent among Chinese patients
Statistical Analysis of a Semilinear Hyperbolic System Advected by a White in Time Random Velocity Field
We study a system of semilinear hyperbolic equations passively advected by
smooth white noise in time random velocity fields. Such a system arises in
modeling non-premixed isothermal turbulent flames under single-step kinetics of
fuel and oxidizer. We derive closed equations for one-point and multi-point
probability distribution functions (PDFs) and closed form analytical formulas
for the one point PDF function, as well as the two-point PDF function under
homogeneity and isotropy. Exact solution formulas allows us to analyze the
ensemble averaged fuel/oxidizer concentrations and the motion of their level
curves. We recover the empirical formulas of combustion in the thin reaction
zone limit and show that these approximate formulas can either underestimate or
overestimate average concentrations when reaction zone is not tending to zero.
We show that the averaged reaction rate slows down locally in space due to
random advection induced diffusion; and that the level curves of ensemble
averaged concentration undergo diffusion about mean locations.Comment: 18 page
Dynamical response functions and collective modes of bilayer graphene
Bilayer graphene (BLG) has recently attracted a great deal of attention
because of its electrically tunable energy gaps and its unusual electronic
structure. In this Letter we present analytical and semi-analytical
expressions, based on the four-band continuum model, for the layer-sum and
layer-difference density response functions of neutral and doped BLG. These
results demonstrate that BLG density-fluctuations can exhibit either
single-component massive-chiral character or standard two-layer character,
depending on energy and doping.Comment: 4 + epsilon pages, 4 figures, submitte
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