702 research outputs found
Clinical report and literature review of female idiopathic hypogonadism with diabetes mellitus
通过报道1例女性特发性低促性腺激素性性腺功能减退症合并糖尿病患者,结合现代医学临床循证的方法和查阅相关文献,以期为特发性低促性腺激素性性腺功能减退症合并糖尿病的诊断和治疗提供思路。1 cases of female idiopathic hypogonadotropic hypogonadism in patients with diabetes mellitus was reported in the paper in order to provide ideas for idiopathic hypogonadotropic hypogonadism with diabetes diagnosis and treatment, based on modern clinical medicine and evidence-based literatures
Crossover between Weak Antilocalization and Weak Localization of Bulk States in Ultrathin Bi2Se3 Films
We report transport studies on the 5 nm thick Bi2Se3 topological insulator
films which are grown via molecular beam epitaxy technique. The angle-resolved
photoemission spectroscopy data show that the Fermi level of the system lies in
the bulk conduction band above the Dirac point, suggesting important
contribution of bulk states to the transport results. In particular, the
crossover from weak antilocalization to weak localization in the bulk states is
observed in the parallel magnetic field measurements up to 50 Tesla. The
measured magneto-resistance exhibits interesting anisotropy with respect to the
orientation of B// and I, signifying intrinsic spin-orbit coupling in the
Bi2Se3 films. Our work directly shows the crossover of quantum interference
effect in the bulk states from weak antilocalization to weak localization. It
presents an important step toward a better understanding of the existing
three-dimensional topological insulators and the potential applications of
nano-scale topological insulator devices
SKA sensitivity for possible radio emission from dark matter in Omega Centauri
Omega Centauri, the largest known globular cluster in the Milky Way, is
believed to be the remains of a dwarf galaxy's core. Giving its potential
abundance of dark matter (DM), it is an attractive target for investigating the
nature of this elusive substance in our local environment. Our study
demonstrates that by observing Omega Centauri with the SKA for 1000 hours, we
can detect synchrotron radio or Inverse Compton (IC) emissions from the DM
annihilation products. It enables us to constrain the cross-section of DM
annihilation down to for DM mass from several
to , which is much stronger compared with other
observations. Additionally, we explore the axion, another well-motivated DM
candidate, and provide stimulated decay calculations. It turns out that the
sensitivity can reach for
.Comment: 19 pages, 8 figure
Electron interaction-driven insulating ground state in Bi2Se3 topological insulators in the two dimensional limit
We report a transport study of ultrathin Bi2Se3 topological insulators with
thickness from one quintuple layer to six quintuple layers grown by molecular
beam epitaxy. At low temperatures, the film resistance increases
logarithmically with decreasing temperature, revealing an insulating ground
state. The sharp increase of resistance with magnetic field, however, indicates
the existence of weak antilocalization, which should reduce the resistance as
temperature decreases. We show that these apparently contradictory behaviors
can be understood by considering the electron interaction effect, which plays a
crucial role in determining the electronic ground state of topological
insulators in the two dimensional limit.Comment: 4 figure
Quantum phase transition of light in a 1-D photon-hopping-controllable resonator array
We give a concrete experimental scheme for engineering the
insulator-superfluid transition of light in a one-dimensional (1-D) array of
coupled superconducting stripline resonators. In our proposed architecture, the
on-site interaction and the photon hopping rate can be tuned independently by
adjusting the transition frequencies of the charge qubits inside the resonators
and at the resonator junctions, respectively, which permits us to
systematically study the quantum phase transition of light in a complete
parameter space. By combining the techniques of photon-number-dependent qubit
transition and fast read-out of the qubit state using a separate low-Q
resonator mode, the statistical property of the excitations in each resonator
can be obtained with a high efficiency. An analysis of the various decoherence
sources and disorders shows that our scheme can serve as a guide to coming
experiments involving a small number of coupled resonators.Comment: 7 pages, 4 figure
Room-temperature ammonia sensor based on ZnO nanorods deposited on ST-cut quartz surface acoustic wave devices
Using a seed layer-free hydrothermal method, ZnO nanorods (NRs) were deposited on ST-cut quartz surface acoustic wave (SAW) devices of ammonia sensing at room-temperature. For a comparison, a ZnO film layer of 30 nm thick was also coated onto ST-cut quartz SAW device using a sol–gel and spin-coating technique. The ammonia sensing results showed that the sensitivity, repeatability and stability of the ZnO NRs coated SAW device were superior to those of the ZnO film coated SAW device due to the large surface-to-volume ratio of the ZnO NRs
Even-Odd Layer-Dependent Anomalous Hall Effect in Topological Magnet MnBi2Te4 Thin Films
A central theme in condensed matter physics is to create and understand the
exotic states of matter by incorporating magnetism into topological materials.
One prime example is the quantum anomalous Hall (QAH) state. Recently, MnBi2Te4
has been demonstrated to be an intrinsic magnetic topological insulator and the
QAH effect was observed in exfoliated MnBi2Te4 flakes. Here, we used molecular
beam epitaxy (MBE) to grow MnBi2Te4 films with thickness down to 1 septuple
layer (SL) and performed thickness-dependent transport measurements. We
observed a non-square hysteresis loop in the antiferromagnetic state for films
with thickness greater than 2 SL. The hysteresis loop can be separated into two
AH components. Through careful analysis, we demonstrated that one AH component
with the larger coercive field is from the dominant MnBi2Te4 phase, while the
other AH component with the smaller coercive field is from the minor Mn-doped
Bi2Te3 phase in the samples. The extracted AH component of the MnBi2Te4 phase
shows a clear even-odd layer-dependent behavior, a signature of
antiferromagnetic thin films. Our studies reveal insights on how to optimize
the MBE growth conditions to improve the quality of MnBi2Te4 films, in which
the QAH and other exotic states are predicted.Comment: 23 pages, 4 figures, comments are welcom
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