3,126 research outputs found
Topological Origin of Zero-Energy Edge States in Particle-Hole Symmetric Systems
A criterion to determine the existence of zero-energy edge states is
discussed for a class of particle-hole symmetric Hamiltonians. A ``loop'' in a
parameter space is assigned for each one-dimensional bulk Hamiltonian, and its
topological properties, combined with the chiral symmetry, play an essential
role. It provides a unified framework to discuss zero-energy edge modes for
several systems such as fully gapped superconductors, two-dimensional d-wave
superconductors, and graphite ribbons. A variants of the Peierls instability
caused by the presence of edges is also discussed.Comment: Completely rewritten. Discussions on coexistence of is- or
id_{xy}-wave order parameter near edges in d_{x^{2}-y^{2}}-wave
superconductors are added; 4 pages, 3 figure
Theory of Transport in Ferroelectric Capacitors
The spontaneous order of electric and magnetic dipoles in ferroelectrics and ferromagnets even at high temperatures is both fascinating and useful. Transport of magnetism in the form of spin currents is vigorously studied in spintronics, but the polarization current of the ferroelectric order has escaped attention. We therefore present a time-dependent diffusion theory for heat and polarization transport in a planar ferroelectric capacitor with parameters derived from a one-dimensional phonon model. We predict steady-state Seebeck and transient Peltier effects that await experimental discovery
Thermoelectric Polarization Transport in Ferroelectric Ballistic Point Contacts
We formulate a scattering theory of polarization and heat transport through a ballistic ferroelectric point contact. We predict a polarization current under either an electric field or a temperature difference that depends strongly on the direction of the ferroelectric order and can be detected by its magnetic stray field and associated thermovoltage and Peltier effect
Magnonics vs. Ferronics
Magnons are the elementary excitations of the magnetic order that carry spin,
momentum, and energy. Here we compare the magnon with the ferron, i.e. the
elementary excitation of the electric dipolar order that transports
polarization and heat in ferroelectrics.Comment: Submitted for publication in the Virtual Special Issue (VSI) on
Magnonics of the Journal of Magnetism and Magnetic Materials, in honor of
Prof. Servio Rezende's 80th birthda
Inhomogeneous scalar field solutions and inflation
We present new exact cosmological inhomogeneous solutions for gravity coupled
to a scalar field in a general framework specified by the parameter .
The equations of motion (and consequently the solutions) in this framework
correspond either to low-energy string theory or Weyl integrable spacetime
according to the sign of . We show that different inflationary
behaviours are possible, as suggested by the study of the violation of the
strong energy condition. Finally, by the analysis of certain curvature scalars
we found that some of the solutions may be nonsingular.Comment: LaTex file, 14 page
Excitations of the ferroelectric order
We identify the bosonic excitations in ferroelectrics that carry electric
dipoles from the phenomenological Landau-Ginzburg-Devonshire theory. The
"ferron" quasi-particles emerge from the concerted action of anharmonicity and
broken inversion symmetry. In contrast to magnons, the transverse excitations
of the magnetic order, the ferrons in displacive ferroelectrics are
longitudinal with respect to the ferroelectric order. Based on the ferron
spectrum, we predict temperature dependent pyroelectric and electrocaloric
properties, electric-field-tunable heat and polarization transport, and
ferron-photon hybridization
The effect of passive heating on heat shock protein 70 and interleukin-6: a possible treatment tool for metabolic diseases?
Exercise and physical activity remain the gold standard methods of enhancing and maintaining health and wellbeing. However, in populations that benefit most from exercise, adherence is often poor and alternatives to exercise are important to bring about health improvements. Recent work suggests a role for passive heating (PH) and heat shock proteins (HSP) in improving cardio-metabolic health. The aim of this study was to investigate the expression of HSP70 and IL-6 in response to either exercise (EX) or PH and the subsequent effect on glucose control. Fourteen males volunteered and were categorized lean (BMI 23.5 ± 2.2 Kgm-2) or overweight (29.2 ± 2.7 Kgm-2) and completed 60 minutes of either moderate cycling at a fixed rate of metabolic heat production (EX) or warm water immersion in 40 ̊C water (PH). Extracellular HSP70 increased from baseline in both conditions with no differences between PH (0.98 ± 1.1 ngmL-1) or EX (0.84 ± 1.0 ngmL-1, P=0.814). IL-6 increased following both conditions with a 2 fold increase after PH and 4 fold after EX. Energy expenditure increased by 61.0 ± 14.4 kcal (79%) after PH. Peak glucose concentration after a meal immediately following PH was reduced when compared with EX (6.3 ± 1.4mmolL-1 vs. 6.8 ± 1.2mmolL-1; P<0.05). There was no difference in 24-hour glucose area under the curve between conditions. These data indicate the potential for thermal therapy as a novel treatment and management strategy for type 2 diabetes where adherence, or ability to exercise may be compromised
Localization Properties of Electronic States in Polaron Model of poly(dG)-poly(dC) and poly(dA)-poly(dT) DNA polymers
We numerically investigate localization properties of electronic states in a
static model of poly(dG)-poly(dC) and poly(dA)-poly(dT) DNA polymers with
realistic parameters obtained by quantum-chemical calculation. The randomness
in the on-site energies caused by the electron-phonon coupling are completely
correlated to the off-diagonal parts. In the single electron model, the effect
of the hydrogen-bond stretchings, the twist angles between the base pairs and
the finite system size effects on the energy dependence of the localization
length and on the Lyapunov exponent are given. The localization length is
reduced by the influence of the fluctuations in the hydrogen bond stretchings.
It is also shown that the helical twist angle affects the localization length
in the poly(dG)-poly(dC) DNA polymer more strongly than in the
poly(dA)-poly(dT) one. Furthermore, we show resonance structures in the energy
dependence of the localization length when the system size is relatively small.Comment: 6 pages, 6 figure
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