133 research outputs found
Time-dependent energetic proton acceleration and scaling laws in ultra-intense laser pulses interactions with thin foils
A two-phase model, where the plasma expansion is an isothermal one when laser
irradiates and a following adiabatic one after laser ends, has been proposed to
predict the maximum energy of the proton beams induced in the ultra-intense
laser-foil interactions. The hot-electron recirculation in the ultra-intense
laser-solid interactions has been accounted in and described by the
time-dependent hot-electron density continuously in this model. The dilution
effect of electron density as electrons recirculate and spread laterally has
been considered. With our model, the scaling laws of maximum ion energy have
been achieved and the dependence of the scaling coefficients on laser
intensity, pulse duration and target thickness have been obtained. Some
interesting results have been predicted: the adiabatic expansion is an
important process of the ion acceleration and cannot be neglected; the whole
acceleration time is about 10-20 times of laser pulse duration; the larger the
laser intensity, the more sensitive the maximum ion energy to the change of
focus radius, and so on.Comment: 15 pages, 4 figures, submitted to PR
Gate defined quantum dot realized in a single crystalline InSb nanosheet
Single crystalline InSb nanosheet is an emerging planar semiconductor
material with potential applications in electronics, infrared optoelectronics,
spintronics and topological quantum computing. Here we report on realization of
a quantum dot device from a single crystalline InSb nanosheet grown by
molecular-beam epitaxy. The device is fabricated from the nanosheet on a
Si/SiO2 substrate and the quantum dot confinement is achieved by top gate
technique. Transport measurements show a series of Coulomb diamonds,
demonstrating that the quantum dot is well defined and highly tunable. Tunable,
gate-defined, planar InSb quantum dots offer a renewed platform for developing
semiconductor-based quantum computation technology.Comment: 12 pages, 4 figure
Multi-organ Segmentation via Co-training Weight-averaged Models from Few-organ Datasets
Multi-organ segmentation has extensive applications in many clinical
applications. To segment multiple organs of interest, it is generally quite
difficult to collect full annotations of all the organs on the same images, as
some medical centers might only annotate a portion of the organs due to their
own clinical practice. In most scenarios, one might obtain annotations of a
single or a few organs from one training set, and obtain annotations of the the
other organs from another set of training images. Existing approaches mostly
train and deploy a single model for each subset of organs, which are memory
intensive and also time inefficient. In this paper, we propose to co-train
weight-averaged models for learning a unified multi-organ segmentation network
from few-organ datasets. We collaboratively train two networks and let the
coupled networks teach each other on un-annotated organs. To alleviate the
noisy teaching supervisions between the networks, the weighted-averaged models
are adopted to produce more reliable soft labels. In addition, a novel region
mask is utilized to selectively apply the consistent constraint on the
un-annotated organ regions that require collaborative teaching, which further
boosts the performance. Extensive experiments on three public available
single-organ datasets LiTS, KiTS, Pancreas and manually-constructed
single-organ datasets from MOBA show that our method can better utilize the
few-organ datasets and achieves superior performance with less inference
computational cost.Comment: Accepted by MICCAI 202
Modeling Multi-wavelength Pulse Profiles of Millisecond Pulsar PSR B1821-24
PSR B182124 is a solitary millisecond pulsar (MSP) which radiates
multi-wavelength pulsed photons. It has complex radio, X-ray and -ray
pulse profiles with distinct peak phase-separations that challenge the
traditional caustic emission models. Using the single-pole annular gap model
with suitable magnetic inclination angle () and viewing angle
(), we managed to reproduce its pulse profiles of three
wavebands. It is found that the middle radio peak is originated from the core
gap region at high altitudes, and the other two radio peaks are originated from
the annular gap region at relatively low altitudes. Two peaks of both X-ray and
-ray wavebands are fundamentally originated from annular gap region,
while the -ray emission generated from the core gap region contributes
somewhat to the first -ray peak. Precisely reproducing the
multi-wavelength pulse profiles of PSR B182124 enables us to understand
emission regions of distinct wavebands and justify pulsar emission models.Comment: Accepted for publication in Ap
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