863 research outputs found
Strong geometric frustration in model glassformers
We consider three popular model glassformers, the Kob-Andersen and
Wahnstr\"om binary Lennard-Jones models and weakly polydisperse hard spheres.
Although these systems exhibit a range of fragilities, all feature a rather
similar behaviour in their local structure approaching dynamic arrest. In
particular we use the dynamic topological cluster classification to extract a
locally favoured structure which is particular to each system. These structures
form percolating networks, however in all cases there is a strong decoupling
between structural and dynamic lengthscales. We suggest that the lack of growth
of the structural lengthscale may be related to strong geometric frustration.Comment: 14 pages, Accepted by J. Non-Crystalline Solids, 7th International
Discussion Meeting on Relaxation in Complex Systems Proceeding
Solace in St. Louis: A case study in heroic cultural nostalgia
This thesis examines the response of American popular culture to the terrorist attacks of September 11, 2001. By utilizing the September 17, 2001 pre-game ceremony, held at Busch Stadium as a case study example, larger generalizations are made about the role popular culture played in the days following the tragedy. In order to analyze this example, I have developed heroic cultural nostalgia, a framework that combines elements of myth, nostalgia and national identity. Heroic cultural nostalgia provides an explanation of how popular culture plays a role in crisis response. The framework highlights the role of individuals with heroic characteristics in evoking nostalgia as a means of providing an escape from current conditions and as a reinforcement of American exceptionalism
Lie systems and integrability conditions for t-dependent frequency harmonic oscillators
Time-dependent frequency harmonic oscillators (TDFHO's) are studied through
the theory of Lie systems. We show that they are related to a certain kind of
equations in the Lie group SL(2,R). Some integrability conditions appear as
conditions to be able to transform such equations into simpler ones in a very
specific way. As a particular application of our results we find t-dependent
constants of the motion for certain one-dimensional TDFHO's. Our approach
provides an unifying framework which allows us to apply our developments to all
Lie systems associated with equations in SL(2,R) and to generalise our methods
to study any Lie system
Quantum Kalb-Ramond Field in D-dimensional de Sitter Spacetimes
In this work we investigate the quantum theory of the Kalb-Ramond fields
propagating in dimensional de Sitter spacetimes using the dynamic invariant
method developed by Lewis and Riesenfeld [J. Math. Phys. 10, 1458 (1969)] to
obtain the solution of the time-dependent Schr\"odinger equation. The wave
function is written in terms of a number quantity satisfying of the
Milne-Pinney equation, whose solution can be expressed in terms of two
independent solutions of the respective equation of motion. We obtain the exact
solution for the quantum Kalb-Ramond field in the de Sitter background and
discuss its relation with the Cremmer-Scherk-Kalb-Ramond model
On the Lie symmetries of a class of generalized Ermakov systems
The symmetry analysis of Ermakov systems is extended to the generalized case
where the frequency depends on the dynamical variables besides time. In this
extended framework, a whole class of nonlinearly coupled oscillators are viewed
as Hamiltonian Ermakov system and exactly solved in closed form
Systemic amyloidosis in England: an epidemiological study.
Epidemiological studies of systemic amyloidosis are scarce and the burden of disease in England has not previously been estimated. In 1999, the National Health Service commissioned the National Amyloidosis Centre (NAC) to provide a national clinical service for all patients with amyloidosis. Data for all individuals referred to the NAC is held on a comprehensive central database, and these were compared with English death certificate data for amyloidosis from 2000 to 2008, obtained from the Office of National Statistics. Amyloidosis was stated on death certificates of 2543 individuals, representing 0·58/1000 recorded deaths. During the same period, 1143 amyloidosis patients followed at the NAC died, 903 (79%) of whom had amyloidosis recorded on their death certificates. The estimated minimum incidence of systemic amyloidosis in the English population in 2008, based on new referrals to the NAC, was 0·4/100 000 population. The incidence peaked at age 60-79 years. Systemic AL amyloidosis was the most common type with an estimated minimum incidence of 0·3/100 000 population. Although there are various limitations to this study, the available data suggest the incidence of systemic amyloidosis in England exceeds 0·8/100 000 of the population
Resonance of isochronous oscillators
An oscillator such that all motions have the same minimal period is called isochronous. When the isochronous is forced by a time-dependent perturbation with the same natural frequency as the oscillator the phenomenon of resonance can appear. This fact is well understood for the harmonic oscillator and we extend it to the nonlinear scenario
Solutions to Maxwell's Equations using Spheroidal Coordinates
Analytical solutions to the wave equation in spheroidal coordinates in the
short wavelength limit are considered. The asymptotic solutions for the radial
function are significantly simplified, allowing scalar spheroidal wave
functions to be defined in a form which is directly reminiscent of the
Laguerre-Gaussian solutions to the paraxial wave equation in optics.
Expressions for the Cartesian derivatives of the scalar spheroidal wave
functions are derived, leading to a new set of vector solutions to Maxwell's
equations. The results are an ideal starting point for calculations of
corrections to the paraxial approximation
Reconstruction of Network Evolutionary History from Extant Network Topology and Duplication History
Genome-wide protein-protein interaction (PPI) data are readily available
thanks to recent breakthroughs in biotechnology. However, PPI networks of
extant organisms are only snapshots of the network evolution. How to infer the
whole evolution history becomes a challenging problem in computational biology.
In this paper, we present a likelihood-based approach to inferring network
evolution history from the topology of PPI networks and the duplication
relationship among the paralogs. Simulations show that our approach outperforms
the existing ones in terms of the accuracy of reconstruction. Moreover, the
growth parameters of several real PPI networks estimated by our method are more
consistent with the ones predicted in literature.Comment: 15 pages, 5 figures, submitted to ISBRA 201
Nonlinearity Management in Higher Dimensions
In the present short communication, we revisit nonlinearity management of the
time-periodic nonlinear Schrodinger equation and the related averaging
procedure. We prove that the averaged nonlinear Schrodinger equation does not
support the blow-up of solutions in higher dimensions, independently of the
strength in the nonlinearity coefficient variance. This conclusion agrees with
earlier works in the case of strong nonlinearity management but contradicts
those in the case of weak nonlinearity management. The apparent discrepancy is
explained by the divergence of the averaging procedure in the limit of weak
nonlinearity management.Comment: 9 pages, 1 figure
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