2,843 research outputs found
Delocalization in random polymer models
A random polymer model is a one-dimensional Jacobi matrix randomly composed
of two finite building blocks. If the two associated transfer matrices commute,
the corresponding energy is called critical. Such critical energies appear in
physical models, an example being the widely studied random dimer model. It is
proven that the Lyapunov exponent vanishes quadratically at a generic critical
energy and that the density of states is positive there. Large deviation
estimates around these asymptotics allow to prove optimal lower bounds on
quantum transport, showing that it is almost surely overdiffusive even though
the models are known to have pure-point spectrum with exponentially localized
eigenstates for almost every configuration of the polymers. Furthermore, the
level spacing is shown to be regular at the critical energy
Platform neutrality and the global balance of powers
This paper defines platform neutrality as a concept for large technology companies, most notably, social media platform providers. It is deduced from the concept of state neutrality, and acknowledges societal and political functions as well as state-like structures these companies have put into place. The paper argues that recent developments demonstrate a convergence of social media towards platform neutrality. It explains the benefit of platform neutrality both for businesses as well as societies
Interacting multi-component exciton gases in a potential trap: phase separation and Bose-Einstein condensation
The system under consideration is a multi-component gas of interacting para-
and orthoexcitons confined in a three dimensional potential trap. We calculate
the spatially resolved optical emission spectrum due to interband transitions
involving weak direct and phonon mediated exciton-photon interactions. For each
component, the occurrence of a Bose-Einstein condensate changes the spectrum in
a characteristic way so that it directly reflects the constant chemical
potential of the excitons and the renormalization of the quasiparticle
excitation spectrum. Moreover, the interaction between the components leads, in
dependence on temperature and particle number, to modifications of the spectra
indicating phase separation of the subsystems. Typical examples of density
profiles and luminescence spectra of ground-state para- and orthoexcitons in
cuprous oxide are given.Comment: 7 pages, 6 figure
Julia Randall Papers
This collection has manuscripts, teaching papers, and correspondence of poet Julia Randall. The correspondence include letters to or from colleagues, alumnae, and friends.https://digitalcommons.hollins.edu/finding_aids/1005/thumbnail.jp
Permanent Superhumps in V1974 Cyg
We present results of 32 nights of CCD photometry of V1974 Cygni, from the
years 1994 and 1995. We verify the presence of two distinct periodicities in
the light curve: 0.0812585 day~1.95 hours and 0.0849767 d~2.04 hr. We establish
that the shorter periodicity is the orbital period of the underlying binary
system. The longer period oscillates with an average value of |dot(P)| ~
3x10^(7)--typical to permanent superhumps. The two periods obey the linear
relation between the orbital and superhump periods that holds among members of
the SU Ursae Majoris class of dwarf novae. A third periodicity of 0.083204
d~2.00 hr appeared in 1994 but not in 1995. It may be related to the recently
discovered anti-superhump phenomenon. These results suggest a linkage between
the classical nova V1974 Cyg and the SU UMa stars, and indicate the existence
of an accretion disk and permanent superhumps in the system no later than 30
months after the nova outburst. From the precessing disk model of the superhump
phenomenon we estimate that the mass ratio in the binary system is between 2.2
and 3.6. Combined with previous results this implies a white dwarf mass of
0.75-1.07 M sun.Comment: 11 pages, 10 eps. figures, Latex, accepted for publication in MNRA
A quantitative central limit theorem for linear statistics of random matrix eigenvalues
It is known that the fluctuations of suitable linear statistics of Haar
distributed elements of the compact classical groups satisfy a central limit
theorem. We show that if the corresponding test functions are sufficiently
smooth, a rate of convergence of order almost can be obtained using a
quantitative multivariate CLT for traces of powers that was recently proven
using Stein's method of exchangeable pairs.Comment: Title modified; main result stated under slightly weaker conditions;
accepted for publication in the Journal of Theoretical Probabilit
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