2,184 research outputs found
Dynamical oscillations in nonlinear optical media
The spatial dynamics of pulses in Kerr media with parabolic index profile are
examined. It is found that when diffraction and graded-index have opposite
signs propagating pulses exhibit an oscillatory pattern, similar to a breathing
behavior. Furthermore, if the pulse and the index profile are not aligned the
pulse oscillates around the index origin with frequency that depends on the
values of the diffraction and index of refraction. These oscillations are not
observed when diffraction and graded-index share the same sign
InSiDDe: A server for designing artificial disordered proteins
InSiDDe (In Silico Disorder Design) is a program for the in silico design of intrinsically disordered proteins of desired length and disorder probability. The latter is assessed using IUPred and spans values ranging from 0.55 to 0.95 with 0.05 increments. One to ten artificial sequences per query, each made of 50 to 200 residues, can be generated by InSiDDe. We describe the rationale used to set up InSiDDe and show that an artificial sequence of 100 residues with an IUPred score of 0.6 designed by InSiDDe could be recombinantly expressed in E. coli at high levels without degradation when fused to a natural molecular recognition element (MoRE). In addition, the artificial fusion protein exhibited the expected behavior in terms of binding modulation of the specific partner recognized by the MoRE. To the best of our knowledge, InSiDDe is the first publicly available software for the design of intrinsically disordered protein (IDP) sequences. InSiDDE is publicly available online
Invisibility in non-Hermitian tight-binding lattices
Reflectionless defects in Hermitian tight-binding lattices, synthesized by
the intertwining operator technique of supersymmetric quantum mechanics, are
generally not invisible and time-of-flight measurements could reveal the
existence of the defects. Here it is shown that, in a certain class of
non-Hermitian tight-binding lattices with complex hopping amplitudes, defects
in the lattice can appear fully invisible to an outside observer. The
synthesized non-Hermitian lattices with invisible defects possess a real-valued
energy spectrum, however they lack of parity-time (PT) symmetry, which does not
play any role in the present work.Comment: to appear in Phys. Rev.
Salvage of Upper Limb following a Severe Crushing Trauma: Immediate Reconstruction with a Free Flap and Subsequent Hyperbaric Oxygen Therapy
A microsurgical latissimus dorsi flap was performed for resurfacing a large soft tissue defect of the forearm with exposure of the vital structures and contaminated wound. Early coverage of a defect is a generally accepted concept to achieve a better functional result. The authors present a case report where a free latissimus dorsi flap with subsequent hyperbaric oxygen therapy allowed a successful single stage reconstruction of this complex severely contaminated defect
Forecasting Regional Labour Market Developments under Spatial Heterogeneity and Spatial Autocorrelation
Because of heterogeneity across regions, economic policy measures are increasingly targeted at the regional level. As a result, the need for economic forecasts at a sub-national level is rapidly increasing. The data available to compute regional forecasts is usually based on a pseudo-panel that consists of a limited number of observations over time, and a large number of areas (regions) strongly interacting with each other. In such a situation, the application of traditional time-series techniques to distinct time series of regional data may then become a sub-optimal forecasting strategy. In the field of regional forecasting of socio-economic variables, both linear and non-linear models have recently been applied and evaluated. However, often such analyses tend to ignore the spatial structure of the data and the spatial interactions that are likely to exist among regions. In this paper, we evaluate the ability of different statistical techniques – namely spatial lag and spatial error models – to correct for misspecification due to neglected spatial autocorrelation in the data set. Our empirical application concerns short-term forecasts of employment in 326 West German labour market regions. We find that the superimposed spatial structure that is required for the estimation of spatial models improves the forecasting performance of non-spatial forecasting models
Multistable Pulse-like Solutions in a Parametrically Driven Ginzburg-Landau Equation
It is well known that pulse-like solutions of the cubic complex
Ginzburg-Landau equation are unstable but can be stabilised by the addition of
quintic terms. In this paper we explore an alternative mechanism where the role
of the stabilising agent is played by the parametric driver. Our analysis is
based on the numerical continuation of solutions in one of the parameters of
the Ginzburg-Landau equation (the diffusion coefficient ), starting from the
nonlinear Schr\"odinger limit (for which ). The continuation generates,
recursively, a sequence of coexisting stable solutions with increasing number
of humps. The sequence "converges" to a long pulse which can be interpreted as
a bound state of two fronts with opposite polarities.Comment: 13 pages, 6 figures; to appear in PR
Optical realization of the two-site Bose-Hubbard model in waveguide lattices
A classical realization of the two-site Bose-Hubbard Hamiltonian, based on
light transport in engineered optical waveguide lattices, is theoretically
proposed. The optical lattice enables a direct visualization of the
Bose-Hubbard dynamics in Fock space.Comment: to be published, J Phys. B (Fast Track Communication
SL(2,R) model with two Hamiltonian constraints
We describe a simple dynamical model characterized by the presence of two
noncommuting Hamiltonian constraints. This feature mimics the constraint
structure of general relativity, where there is one Hamiltonian constraint
associated with each space point. We solve the classical and quantum dynamics
of the model, which turns out to be governed by an SL(2,R) gauge symmetry,
local in time. In classical theory, we solve the equations of motion, find a
SO(2,2) algebra of Dirac observables, find the gauge transformations for the
Lagrangian and canonical variables and for the Lagrange multipliers. In quantum
theory, we find the physical states, the quantum observables, and the physical
inner product, which is determined by the reality conditions. In addition, we
construct the classical and quantum evolving constants of the system. The model
illustrates how to describe physical gauge-invariant relative evolution when
coordinate time evolution is a gauge.Comment: 9 pages, 1 figure, revised version, to appear in Phys. Rev.
Circumareolar Mastopexy with Multiple Glandular Plications for Symmetry of the Contra-Lateral Breast, in Patients Undergoing Breast Reconstruction with Prosthesis. Experience on 50 Cases
4 years experience on 50 cases using the Elliott’s technique for symmetrization of the contra-lateral breast in patients undergoing breast reconstruction with an anatomical prosthesis is presented in this paper
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