612 research outputs found
On the Emergence of Unstable Modes in an Expanding Domain for Energy-Conserving Wave Equations
Motivated by recent work on instabilities in expanding domains in
reaction-diffusion settings, we propose an analog of such mechanisms in
energy-conserving wave equations. In particular, we consider a nonlinear
Schr{\"o}dinger equation in a finite domain and show how the expansion or
contraction of the domain, under appropriate conditions, can destabilize its
originally stable solutions through the modulational instability mechanism.
Using both real and Fourier spacediagnostics, we monitor and control the
crossing of the instability threshold and, hence, the activation of the
instability. We also consider how the manifestation of this mechanism is
modified in a spatially inhomogeneous setting, namely in the presence of an
external parabolic potential, which is relevant to trapped Bose-Einstein
condensates
Paraneoplastic Vitelliform Retinopathy Secondary to Metastatic Melanoma.
Paraneoplastic vitelliform retinopathy secondary to metastatic melanom
The STAR MAPS-based PiXeL detector
The PiXeL detector (PXL) for the Heavy Flavor Tracker (HFT) of the STAR
experiment at RHIC is the first application of the state-of-the-art thin
Monolithic Active Pixel Sensors (MAPS) technology in a collider environment.
Custom built pixel sensors, their readout electronics and the detector
mechanical structure are described in detail. Selected detector design aspects
and production steps are presented. The detector operations during the three
years of data taking (2014-2016) and the overall performance exceeding the
design specifications are discussed in the conclusive sections of this paper
Multistable Solitons in Higher-Dimensional Cubic-Quintic Nonlinear Schroedinger Lattices
We study the existence, stability, and mobility of fundamental discrete
solitons in two- and three-dimensional nonlinear Schroedinger lattices with a
combination of cubic self-focusing and quintic self-defocusing onsite
nonlinearities. Several species of stationary solutions are constructed, and
bifurcations linking their families are investigated using parameter
continuation starting from the anti-continuum limit, and also with the help of
a variational approximation. In particular, a species of hybrid solitons,
intermediate between the site- and bond-centered types of the localized states
(with no counterpart in the 1D model), is analyzed in 2D and 3D lattices. We
also discuss the mobility of multi-dimensional discrete solitons that can be
set in motion by lending them kinetic energy exceeding the appropriately
crafted Peierls-Nabarro barrier; however, they eventually come to a halt, due
to radiation loss.Comment: 12 pages, 17 figure
Entropy and Spin Susceptibility of s-wave Type-II Superconductors near
A theoretical study is performed on the entropy and the spin
susceptibility near the upper critical field of s-wave
type-II superconductors with arbitrary impurity concentrations. The changes of
these quantities through may be expressed as , for example, where is the average flux density
and denotes entropy in the normal state. It is found that the
slopes and at T=0 are identical, connected
directly with the zero-energy density of states, and vary from 1.72 in the
dirty limit to in the clean limit. This mean-free-path dependence
of and at T=0 is quantitatively the same as that
of the slope for the flux-flow resistivity studied
previously. The result suggests that and near
T=0 are convex downward (upward) in the dirty (clean) limit, deviating
substantially from the linear behavior . The specific-heat
jump at also shows fairly large mean-free-path dependence.Comment: 8 pages, 5 figure
Phenological growth stages of tree tomato (Solanum betaceum Cav.), an emerging fruit crop, according to the basic and extended BBCH scale
[EN] The tree tomato (Solanum betaceum Cav.) is a small tree native to the Andean region cultivated for its juicy fruits, which are having an increasing demand. Tree tomato is morphologically and phenologically different from other Solanum crops and tools for the phenological description of the developmental stages are needed for the enhancement of this emerging crop. We developed a basic and an extended numerical BBCH (Biologische Bundesanstalt, Bundessortenamnt, Chemische Industrie) scales which allow the precise identification of the phenological stages of tree tomato. Eight principal stages are described for germination, leaf development, formation of side shoots, stem elongation, inflorescence emergence, flowering, development of fruit, and ripening of fruit and seed. The basic (two-digit) scale is sufficiently precise for germination, stem elongation, and ripening of fruit and seed. However, for leaf development, formation of side shoots, inflorescence emergence, flowering, and development of fruit the extended (three-digit) scale is considered necessary for an adequate description. The description of the phenological stages is combined with illustrations for clarification. The tree tomato BBCH scale has been validated by characterizing 24 accessions of different varietal groups for traits of agronomic interest and evaluating the differences observed among accessions at specific BBCH developmental stages. The basic and extended BBCH scales represent a useful tool for the description and identification of phenological scales of tree tomato. These scales will be useful for the enhancement of this emerging fruit crop. (C) 2015 Elsevier B.V. All rights reserved.Acosta-Quezada, P.; Riofrío-Cuenca, T.; Rojas, J.; Vilanova Navarro, S.; Plazas Ávila, MDLO.; Prohens Tomás, J. (2016). Phenological growth stages of tree tomato (Solanum betaceum Cav.), an emerging fruit crop, according to the basic and extended BBCH scale. Scientia Horticulturae. 199:216-223. doi:10.1016/j.scienta.2015.12.045S21622319
Baryon polarization in low-energy unpolarized meson-baryon scattering
We compute the polarization of the final-state baryon, in its rest frame, in
low-energy meson--baryon scattering with unpolarized initial state, in
Unitarized BChPT. Free parameters are determined by fitting total and
differential cross-section data (and spin-asymmetry or polarization data if
available) for , and scattering. We also compare our
results with those of leading-order BChPT
Predicting haemodynamic networks using electrophysiology: The role of non-linear and cross-frequency interactions
Understanding the electrophysiological basis of resting state networks (RSNs) in the human brain is a critical step towards elucidating how inter-areal connectivity supports healthy brain function. In recent years, the relationship between RSNs (typically measured using haemodynamic signals) and electrophysiology has been explored using functional Magnetic Resonance Imaging (fMRI) and magnetoencephalography (MEG). Significant progress has been made, with similar spatial structure observable in both modalities. However, there is a pressing need to understand this relationship beyond simple visual similarity of RSN patterns. Here, we introduce a mathematical model to predict fMRI-based RSNs using MEG. Our unique model, based upon a multivariate Taylor series, incorporates both phase and amplitude based MEG connectivity metrics, as well as linear and non-linear interactions within and between neural oscillations measured in multiple frequency bands. We show that including non-linear interactions, multiple frequency bands and cross-frequency terms significantly improves fMRI network prediction. This shows that fMRI connectivity is not only the result of direct electrophysiological connections, but is also driven by the overlap of connectivity profiles between separate regions. Our results indicate that a complete understanding of the electrophysiological basis of RSNs goes beyond simple frequency-specific analysis, and further exploration of non-linear and cross-frequency interactions will shed new light on distributed network connectivity, and its perturbation in pathology
Magnetoluminescence
Pulsar Wind Nebulae, Blazars, Gamma Ray Bursts and Magnetars all contain
regions where the electromagnetic energy density greatly exceeds the plasma
energy density. These sources exhibit dramatic flaring activity where the
electromagnetic energy distributed over large volumes, appears to be converted
efficiently into high energy particles and gamma-rays. We call this general
process magnetoluminescence. Global requirements on the underlying, extreme
particle acceleration processes are described and the likely importance of
relativistic beaming in enhancing the observed radiation from a flare is
emphasized. Recent research on fluid descriptions of unstable electromagnetic
configurations are summarized and progress on the associated kinetic
simulations that are needed to account for the acceleration and radiation is
discussed. Future observational, simulation and experimental opportunities are
briefly summarized.Comment: To appear in "Jets and Winds in Pulsar Wind Nebulae, Gamma-ray Bursts
and Blazars: Physics of Extreme Energy Release" of the Space Science Reviews
serie
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