575 research outputs found
Improving Whole Slide Segmentation Through Visual Context - A Systematic Study
While challenging, the dense segmentation of histology images is a necessary
first step to assess changes in tissue architecture and cellular morphology.
Although specific convolutional neural network architectures have been applied
with great success to the problem, few effectively incorporate visual context
information from multiple scales. With this paper, we present a systematic
comparison of different architectures to assess how including multi-scale
information affects segmentation performance. A publicly available breast
cancer and a locally collected prostate cancer datasets are being utilised for
this study. The results support our hypothesis that visual context and scale
play a crucial role in histology image classification problems
Transport properties for a Luttinger liquid wire with Rashba spin-orbit coupling and Zeeman splitting
We study the transport properties for a Luttinger-liquid (LL) quantum wire in
the presence of both Rashba spin-orbit coupling (SOC) and a weak external
in-plane magnetic field. The bosonized Hamiltonian of the system with an
externally applied longitudinal electric field is established. And then the
equations of motion for the bosonic phase fields are solved in the Fourier
space, with which the both charge and spin conductivities for the system are
calculated analytically based on the linear response theory. Generally, the ac
conductivity is an oscillation function of the strengths of electron-electron
interaction, Rashba SOC and magnetic field, as well as the driving frequency
and the measurement position in the wire. Through analysis with some examples
it is demonstrated that the modification on the conductivity due to
electron-electron interactions is more remarkable than that due to SOC, while
the effects of SOC and Zeeman splitting on the conductivity are very similar.
The spin-polarized conductivities for the system in the absence of Zeeman
effect or SOC are also discussed, respectively. The ratio of the spin-polarized
conductivities is dependent of the
electron-electron interactions for the system without SOC, while it is
independent of the electron-electron interactions for the system without Zeeman
splitting.Comment: 10 pages, 8 figure
Spin-polarized electric currents in quantum transport through tubular two-dimensional electron gases
Scattering theory is employed to derive a Landauer-type formula for the spin
and the charge currents, through a finite region where spin-orbit interactions
are effective. It is shown that the transmission matrix yields the spatial
direction and the magnitude of the spin polarization. This formula is used to
study the currents through a tubular two-dimensional electron gas. In this
cylindrical geometry, which may be realized in experiment, the transverse
conduction channels are not mixed (provided that the spin-orbit coupling is
uniform). It is then found that for modest boundary scattering, each step in
the quantized conductance is split into two, and the new steps have a non-zero
spin conductance, with the spin polarization perpendicular to the direction of
the current.Comment: 6 pages, 5 figure
Interplay of spin-orbit coupling and Zeeman splitting in the absorption lineshape of 2D fermions
We suggest that electron spin resonance (ESR) experiment can be used as a
probe of spinon excitations of hypothetical spin-liquid state of frustrated
antiferromagnet in the presence of asymmetric Dzyaloshinskii-Moriya (DM)
interaction. We describe assumptions under which the ESR response is reduced to
the response of 2D electron gas with Rashba spin-orbit coupling. Unlike
previous treatments, the spin-orbit coupling, \Delta_{SO}, is not assumed small
compared to the Zeeman splitting, \Delta_Z. We demonstrate that ESR response
diverges at the edges of the absorption spectrum for ac magnetic field
perpendicular to the static field. At the compensation point,
\Delta_{SO}\approx \Delta_Z, the broad absorption spectrum exhibits features
that evolve with temperature, T, even when T is comparable to the Fermi energy.Comment: 11 pages, 6 figure
Multidimensional Instability and Dynamics of Spin Avalanches in Crystals of Nanomagnets
We obtain a fundamental instability of the magnetization-switching fronts in superparamagnetic and ferromagnetic materials such as crystals of nanomagnets, ferromagnetic nanowires, and systems of quantum dots with large spin. We develop the instability theory for both linear and nonlinear stages. By using numerical simulations we investigate the instability properties focusing on spin avalanches in crystals of nanomagnets. The instability distorts spontaneously the fronts and leads to a complex multidimensional front dynamics. We show that the instability has a universal physical nature, with a deep relationship to a wide variety of physical systems, such as the Darrieus-Landau instability of deflagration fronts in combustion, inertial confinement fusion, and thermonuclear supernovae, and the instability of doping fronts in organic semiconductors
Suppression of spin-orbit effects in 1D system
We report the absence of spin effects such as spin-galvanic effect, spin
polarization and spin current under static electric field and
inter-spin-subband absorption in 1D system with spin-orbit interaction of
arbitrary form. It was also shown that the accounting for the direct
interaction of electron spin with magnetic field violates this statement.Comment: 8 pages, 1Figur
Hartree-Fock ground state of the two-dimensional electron gas with Rashba spin-orbit interaction
We search for the uniform Hartree-Fock ground state of the two-dimensional
electron gas formed in semiconductor heterostructures including the Rashba
spin-orbit interaction. We identify two competing quantum phases: a
ferromagnetic one with partial spin polarization in the perpendicular direction
and a paramagnetic one with in-plane spin. We present a phase diagram in terms
of the relative strengths of the Rashba to the Coulomb interaction and the
electron density. We compare our theoretical description with existing
experimental results obtained in GaAs-AlGaAs heterostructures.Comment: 5 pages, 2 figure
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