58 research outputs found
Bitcoin: a Money-like Informational Commodity
The question "what is Bitcoin" allows for many answers depending on the
objectives aimed at when providing such answers. The question addressed in this
paper is to determine a top-level classification, or type, for Bitcoin. We will
classify Bitcoin as a system of type money-like informational commodity (MLIC)
Magneto-Transport in the Two-Dimensional Lorentz Gas
We consider the two-dimensional Lorentz gas with Poisson distributed hard
disk scatterers and a constant magnetic field perpendicular to the plane of
motion. The velocity autocorrelation is computed numerically over the full
range of densities and magnetic fields with particular attention to the
percolation threshold between hopping transport and pure edge currents. The
Ohmic and Hall conductance are compared with mode-coupling theory and a recent
generalized kinetic equation valid for low densities and small fields. We argue
that the long time tail as persists for non-zero magnetic field.Comment: 7 pages, 14 figures. Uses RevTeX and epsfig.sty. Submitted to
Physical Review
Quasiclassical negative magnetoresistance of a 2D electron gas: interplay of strong scatterers and smooth disorder
We study the quasiclassical magnetotransport of non-interacting fermions in
two dimensions moving in a random array of strong scatterers (antidots,
impurities or defects) on the background of a smooth random potential. We
demonstrate that the combination of the two types of disorder induces a novel
mechanism leading to a strong negative magnetoresistance, followed by the
saturation of the magnetoresistivity at a value determined
solely by the smooth disorder. Experimental relevance to the transport in
semiconductor heterostructures is discussed.Comment: 4 pages, 2 figure
Chaotic Properties of Dilute Two and Three Dimensional Random Lorentz Gases I: Equilibrium Systems
We compute the Lyapunov spectrum and the Kolmogorov-Sinai entropy for a
moving particle placed in a dilute, random array of hard disk or hard sphere
scatterers - i.e. the dilute Lorentz gas model. This is carried out in two
ways: First we use simple kinetic theory arguments to compute the Lyapunov
spectrum for both two and three dimensional systems. In order to provide a
method that can easily be generalized to non-uniform systems we then use a
method based upon extensions of the Lorentz-Boltzmann (LB) equation to include
variables that characterize the chaotic behavior of the system. The extended LB
equations depend upon the number of dimensions and on whether one is computing
positive or negative Lyapunov exponents. In the latter case the extended LB
equation is closely related to an "anti-Lorentz-Boltzmann equation" where the
collision operator has the opposite sign from the ordinary LB equation. Finally
we compare our results with computer simulations of Dellago and Posch and find
very good agreement.Comment: 48 pages, 3 ps fig
The Localization Transition of the Two-Dimensional Lorentz Model
We investigate the dynamics of a single tracer particle performing Brownian
motion in a two-dimensional course of randomly distributed hard obstacles. At a
certain critical obstacle density, the motion of the tracer becomes anomalous
over many decades in time, which is rationalized in terms of an underlying
percolation transition of the void space. In the vicinity of this critical
density the dynamics follows the anomalous one up to a crossover time scale
where the motion becomes either diffusive or localized. We analyze the scaling
behavior of the time-dependent diffusion coefficient D(t) including corrections
to scaling. Away from the critical density, D(t) exhibits universal
hydrodynamic long-time tails both in the diffusive as well as in the localized
phase.Comment: 13 pages, 7 figures
Drift mobility of large polarons in the intermediate coupling region
Contains fulltext :
mmubn000001_251483169.pdf (publisher's version ) (Open Access)Promotor : E. Verbovenviii, 41 p
Crosstalk between the catalytic and regulatory domains allows bidirectional regulation of Src
The catalytic activity of Src family tyrosine kinases is inhibited by intramolecular interactions between the regulatory SH3 and SH2 domains and the catalytic domain. In the inactive state, the critical alphaC-helix in the catalytic domain is positioned such that the formation of the Glu 310-Lys 295 salt bridge is precluded, Tyr 416 in the activation loop is unphosphorylated, and the SH2 and SH3 domains are unavailable for interactions with other proteins. We found that phosphorylation of the activation loop or mutation of the loop preceding the alphaC-helix activates Src and increases the accessibility of the SH3 domain for ligands. Interaction of the alphaC-helix with the activation loop is a central component of this regulatory system. Our data suggest a bidirectional regulation mechanism in which the regulatory domains inhibit Src activity, and Src activity controls the availability of the regulatory domains. By this mechanism, Src family kinases can be activated by proteins phosphorylating or changing the conformation of the catalytic domain. Once active, Src family kinases become less prone to regulation, implying a positive feedback loop on their activity
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