11,112 research outputs found
Sticky Particles and Stochastic Flows
Gaw\c{e}dzki and Horvai have studied a model for the motion of particles
carried in a turbulent fluid and shown that in a limiting regime with low
levels of viscosity and molecular diffusivity, pairs of particles exhibit the
phenomena of stickiness when they meet. In this paper we characterise the
motion of an arbitrary number of particles in a simplified version of their
model
The N = 1 Supersymmetric Wong Equations and the Non-Abelian Landau Problem
A Lagrangian formulation is given extending to N = 1 supersymmetry the motion
of a charged point particle with spin in a non-abelian external field. The
classical formulation is constructed for any external static non-abelian SU(N)
gauge potential. As an illustration, a specific gauge is fixed enabling
canonical quantization and the study of the supersymmetric non-abelian Landau
problem. The spectrum of the quantum Hamiltonian operator follows in accordance
with the supersymmetric structure.Comment: 10 page
Weak randomness completely trounces the security of QKD
In usual security proofs of quantum protocols the adversary (Eve) is expected
to have full control over any quantum communication between any communicating
parties (Alice and Bob). Eve is also expected to have full access to an
authenticated classical channel between Alice and Bob. Unconditional security
against any attack by Eve can be proved even in the realistic setting of device
and channel imperfection. In this Letter we show that the security of QKD
protocols is ruined if one allows Eve to possess a very limited access to the
random sources used by Alice. Such knowledge should always be expected in
realistic experimental conditions via different side channels
Clusters under strong VUV pulses: A quantum-classical hybrid-description incorporating plasma effects
The quantum-classical hybrid-description of rare-gas clusters interacting
with intense light pulses which we have developed is described in detail. Much
emphasis is put on the treatment of screening electrons in the cluster which
set the time scale for the evolution of the system and form the link between
electrons strongly bound to ions and quasi-free plasma electrons in the
cluster. As an example we discuss the dynamics of an Ar147 cluster exposed to a
short VUV laser pulse of 20eV photon energy.Comment: 8 pages, 9 figure
Ionization of clusters in strong X-ray laser pulses
The effect of intense X-ray laser interaction on argon clusters is studied
theoretically with a mixed quantum/classical approach. In comparison to a
single atom we find that ionization of the cluster is suppressed, which is in
striking contrast to the observed behavior of rare-gas clusters in intense
optical laser pulses. We have identified two effects responsible for this
phenomenon: A high space charge of the cluster in combination with a small
quiver amplitude and delocalization of electrons in the cluster. We elucidate
their impact for different field strengths and cluster sizes.Comment: 4 pages, 4 figure
Long-term efficacy and safety of eculizumab in Japanese patients with generalized myasthenia gravis : a subgroup analysis of the REGAIN open-label extension study
The terminal complement inhibitor eculizumab was shown to improve myasthenia gravis-related symptoms in the 26-week, phase 3, randomized, double-blind, placebo-controlled REGAIN study (NCT01997229). In this 52-week sub-analysis of the open-label extension of REGAIN (NCT02301624), eculizumab's efficacy and safety were assessed in 11 Japanese and 88 Caucasian patients with anti-acetylcholine receptor antibody-positive refractory generalized myasthenia gravis. For patients who had received placebo during REGAIN, treatment with open-label eculizumab resulted in generally similar outcomes in the Japanese and Caucasian populations. Rapid improvements were maintained for 52 weeks, assessed by change in score from open-label extension baseline to week 52 (mean [standard error]) using the following scales (in Japanese and Caucasian patients, respectively): Myasthenia Gravis Activities of Daily Living (-2.4 [1.34] and - 3.3 [0.651); Quantitative Myasthenia Gravis (-2.9 [1.98] and - 4.3 [0.79]); Myasthenia Gravis Composite (-4.5 [2.63] and - 4.9 [1.19]); and Myasthenia Gravis Quality of Life 15-item questionnaire (-8.6 [5.68) and - 6.5 [1.93]). Overall, the safety of eculizumab was consistent with its known safety profile. In this interim sub-analysis, the efficacy and safety of eculizumab in Japanese and Caucasian patients were generally similar, and consistent with the overall REGAIN population
Uniform shrinking and expansion under isotropic Brownian flows
We study some finite time transport properties of isotropic Brownian flows.
Under a certain nondegeneracy condition on the potential spectral measure, we
prove that uniform shrinking or expansion of balls under the flow over some
bounded time interval can happen with positive probability. We also provide a
control theorem for isotropic Brownian flows with drift. Finally, we apply the
above results to show that under the nondegeneracy condition the length of a
rectifiable curve evolving in an isotropic Brownian flow with strictly negative
top Lyapunov exponent converges to zero as with positive
probability
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