30,923 research outputs found
Mesoscopic Kondo effect of a quantum dot embedded in an Aharonov-Bohm ring with intradot spin-flip scattering
We study the Kondo effect in a quantum dot embedded in a mesoscopic ring
taking into account intradot spin-flip scattering . Based on the finite-
slave-boson mean-field approach, we find that the Kondo peak in the density of
states is split into two peaks by this coherent spin-flip transition, which is
responsible for some interesting features of the Kondo-assisted persistent
current circulating the ring: (1) strong suppression and crossover to a sine
function form with increasing ; (2) appearance of a "hump" in the
-dependent behavior for odd parity. -induced reverse of the persistent
current direction is also observed for odd parity.Comment: 7 pages,6 figures, to be published by Europhys. Let
Bone growth as the main determinant of mouse digit tip regeneration after amputation
Regeneration is classically demonstrated in mammals using mice digit tip. In this study, we compared different amputation plans and show that distally amputated digits regrow with morphology close to normal but fail to regrow the fat pad. Proximally amputated digits do not regrow the phalangeal bone, but the remaining structures (nail, skin and connective tissue), all with intrinsic regenerative capacity, re-establishing integrity indistinguishably in distally and proximally amputated digits. Thus, we suggest that the bone growth promoted by signals and progenitor cells not removed by distal amputations is responsible for the re-establishment of a drastically different final morphology after distal or proximal digit tip amputations. Despite challenging the use of mouse digit tip as a model system for limb regeneration in mammals, these findings evidence a main role of bone growth in digit tip regeneration and suggest that mechanisms that promote joint structures formation should be the main goal of regenerative medicine for limb and digit regrowth9CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP460664/2014-02012/09602-0; 2019/09870-
Fourier Eigenfunctions, Uncertainty Gabor Principle and Isoresolution Wavelets
Shape-invariant signals under Fourier transform are investigated leading to a
class of eigenfunctions for the Fourier operator. The classical uncertainty
Gabor-Heisenberg principle is revisited and the concept of isoresolution in
joint time-frequency analysis is introduced. It is shown that any Fourier
eigenfunction achieve isoresolution. It is shown that an isoresolution wavelet
can be derived from each known wavelet family by a suitable scaling.Comment: 6 pages, XX Simp\'osio Bras. de Telecomunica\c{c}\~oes, Rio de
Janeiro, Brazil, 2003. Fixed typo
Topological Line Defects around Graphene Nanopores for DNA Sequencing
Topological line defects in graphene represent an ideal way to produce highly
controlled structures with reduced dimensionality that can be used in
electronic devices. In this work we propose using extended line defects in
graphene to improve nucleobase selectivity in nanopore-based DNA sequencing
devices. We use a combination of QM/MM and non-equilibrium Green's functions
methods to investigate the conductance modulation, fully accounting for solvent
effects. By sampling over a large number of different orientations generated
from molecular dynamics simulations, we theoretically demonstrate that
distinguishing between the four nucleobases using line defects in a
graphene-based electronic device appears possible. The changes in conductance
are associated with transport across specific molecular states near the Fermi
level and their coupling to the pore. Through the application of a specifically
tuned gate voltage, such a device would be able to discriminate the four types
of nucleobases more reliably than that of graphene sensors without topological
line defects.Comment: 6 figures and 6 page
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