1,035 research outputs found
Intrinsic anomalous Hall effect across the magnetic phase transition of a spin-orbit-coupled Bose-Einstein condensate
We study theoretically the zero temperature intrinsic anomalous Hall effect
in an experimentally realized 2D spin-orbit coupled Bose gas. For anisotropic
atomic interactions and as the spin-orbit coupling strength increases, the
system undergoes a ground state phase transition from states exhibiting a total
in-plane magnetization to those with a perpendicular magnetization along the
direction. We show that finite frequency, or ac, Hall responses exist in
both phases in the absence of an artificial magnetic field, as a result of
finite inter-band transitions. However, the characteristics of the anomalous
Hall responses are drastically different in these two phases because of the
different symmetries preserved by the corresponding ground states. In
particular, we find a finite dc Hall conductivity in one phase but not the
other. The underlying physical reasons for this are analyzed further by
exploring relations of the dc Hall conductivity to the system's chirality and
Berry curvatures of the Bloch bands. Finally, we discuss an experimental method
of probing the anomalous Hall effect in trapped systems.Comment: 13 pages, 11 figure
Bosonic Weyl excitations induced by -orbital interactions in a cubic optical lattice
Weyl points exist in a fascinating topological state of matter with linear
band crossings analogous to magnetic monopoles. Tremendous efforts have been
devoted to investigate fermionic topological matters with Weyl points in the
single-particle band dispersion. It remains elusive for realizing
interaction-induced Weyl points, especially for bosons. Motivated by recent
experimental progress in ultracold atoms, we propose a scheme to create Weyl
points for Bogoliubov excitations of a bosonic superfluid in a
three-dimensional cubic optical lattice. The unique design of the lattice leads
to interaction-induced time-reversal symmetry breaking for a -orbital
superfluid, which in turn induces Weyl Bogoliubov excitations. Analogous to
Weyl semimetals of electronic systems, the superfluid also support
topologically protected edge modes due to the bulk-boundary correspondence
MiR-1254 inhibits proliferation, migration and invasion of human brain tumour cell lines
Purpose: To investigate the expression of miR-1254 in 5 astrocytoma cell lines, and the mechanism involved.Methods: Total RNA was isolated by RNeasy RNA isolation kit while cDNA was prepared by RevertAid cDNA synthesis kit. The transcripts were analysed by real-time polymerase chain reaction (RT-PCR). Transfection of miR-1254 was carried out using FuGENE HD (Promega). Apoptosis was determined by DAPI, acridine orange (AO)/ethidium bromide (EB) and annexin V/PI double staining. Cell migration and invasion were investigated by wound healing and Martigel invasion assays, respectively. Protein expression was measured by western blotting.Results: Expression of miR-1254 was significantly down-regulated in the astrocytoma cell lines when compared to normal astrocyte cells (p < 0.05). Ectopic expression of miR-1254 in astrocytoma SW 1088 cells inhibited cell proliferation via initiation of apoptosis and cell cycle arrest. Over-expression of miR- 1254 also led to significant decrease in cell migration and invasion of SW 1088 astrocytoma cells (p < 0.05).Conclusion: The results show that the expression of miR-1254 is down-regulated in astrocytoma cell lines, but over-expression of miR-1254 inhibits proliferation of the cell lines via cell cycle arrest and apoptosis. Thus, miR-1254 has promising potential for use in the treatment of brain tumour.Keywords: Brain tumour, Astrocytoma, miR-1254, Apoptosis, Cell migratio
V2PSense: Enabling Cellular-based V2P Collision Warning Service Through Mobile Sensing
The C-V2X (Cellular Vehicle-to-Everything) technology
is developing in full swing. One of its mainstream services
can be the Vehicle-to-Pedestrian (V2P) service. It can protect
pedestrians who are mostly vulnerable on the road. In this
work, we seek to enable a V2P service that can identify which
pedestrians may be nearby a dangerous driving event and then
notify them of warning messages. To enable this V2P service,
there are two major challenges. First, a low-latency V2P message
transport is required for this infrastructure-based service.
Second, the pedestrianās smartphone requires an energy-efficient
outdoor positioning method instead of power-hungry GPS due
to its limited battery life. We thus propose a novel solution,
V2PSense, which trades off positioning precision for energy
savings while achieving low-latency message transport with LTE
high-priority bearers. It does a coarse-grained positioning by
leveraging intermittent GPS information and mobile sensing data,
which includes step count from the pedometer and cellular signal
strength changes. Though the V2PSenseās positioning is not as
precise as the GPS, it can still ensure that all the pedestrians
nearby dangerous spots can be notified. Our results show that
it can achieve the average precision ratio 92.6% for estimating
where the pedestrian is while saving 20.8% energy, compared
with the GPS always-on case.This work was partially supported by the Ministry of Science and Tech-nology, Taiwan, under grant numbers 106-2622-8-009-017 and 106-2218-E-009-018, and by the H2020 collaborative Europe/Taiwan research project 5G-CORAL (grant num. 761586
Fingerprint and multi-component quantitative analyses for quality evaluation of Rhizoma coptidis steamed with rice wine
Purpose: To establish a method for the simultaneous determination of multi-components of Rhizoma coptidis steamed with rice wine (RCRW), and to provide a reference for assessing its standard of quality.
Method: Chromatographic separation was performed on a high performance liquid chromatography (HPLC) system to determine the characteristic fingerprint of RCRW. The mobile phase consisted of acetonitrile (A) and 0.1 % trifluoroacetic acid (B), with gradients of B as follows: 15 - 20 % from 0 ā 30 min; 20 - 25 % from 30 - 50 min; 25 - 35 % for 50 - 60 min, and 35 % for 60 - 70 min.
Results: In the multiple reaction monitoring mode, eight components of RCRW were isolated by HPLCphoto-diode array (PDA) method. A fingerprint of the RCRW was established and 8 peaks were calibrated. The method was further validated in terms of linearity (R2 > 0.9993), precision (relative standard deviation, RSD < 1.51 %); repeatability (RSD < 2.98 %) and stability (RSD < 1.93 %). Mean recovery rate ranged from 96.2 to 103.8 %, while RSD values ranged from 0.92 to 2.88 %.
Conclusion: These results show that HPLC-PDA method is accurate and feasible, and that they provide a reference for further comprehensive and effective quality control of RCRW
Precision Measurement of M1 Optical Clock Transition in Ni12+
Highly charged ions (HCIs) have drawn significant interest in quantum
metrology and in search for new physics. Among these, Ni12+ is considered as
one of the most promising candidates for the next generation of HCI optical
clocks, due to its two E1-forbidden transitions M1 and E2, which occur in the
visible spectral range. In this work, we used the Shanghai-Wuhan Electron Beam
Ion Trap to perform a high-precision measurement of the M1 transition
wavelength. Our approach involved an improved calibration scheme for the
spectra, utilizing auxiliary Ar+ lines for calibration and correction. Our
final measured result of the M1 transition wavelength demonstrates a five-fold
improvement in accuracy compared to our previous findings, reaching the
sub-picometer level accuracy. In combination with our rigorous atomic-structure
calculations to capture the electron correlations and relativistic effects, the
quantum electrodynamic (QED) corrections were extracted. Moreover, comparing
with an estimate of the one-electron QED contributions by using the GRASP2018
package, we found that the present experimental accuracy is high enough for
testing the higher-order QED corrections for such a complex system with four
electrons in the p subshell.Comment: 15 pages, 5 figure
Mobile Edge Computing Platform Deployment in 4G LTE Networks: A Middlebox Approach
This paper has been presented at : USENIX Workshop on Hot Topics in Edge Computing (Hot Edge '18)Low-latency demands for cellular networks have at-tracted much attention. Mobile edge computing (MEC), which deploys a cloud computing platform at the edge closer to mobile users, has been introduced as an enabler of low-latency performance in 4G and 5G networks. In this paper, we propose an MEC platform deployment so-lution in 4G LTE networks using a middlebox approach. It is standard-compliant and transparent to existing cel-lular network components, so they need not be modiļ¬ed. The MEC middlebox sits on the S1 interface, which con-nects an LTE base station to its core network, and does trafļ¬c ļ¬ltering, manipulation and forwarding. It enables the MEC service for mobile users by hosting application servers. Such middlebox approach can save deployment cost and be easy to install. It is different from other stud-ies that require modiļ¬cations on base stations or/and core networks. We have conļ¬rmed its viability through a pro-totype based on the OpenAirInterface cellular platform.We thank our shepherd Weisong Shi for his help, and also thank the anonymous reviewers for their valuable comments on improving this paper. This work was partially supported by the Ministry of Science and Technology, Taiwan, under grant numbers 106-2622-8-009-017 and 106-2218-E-009-018, and by the H2020 collaborative Europe/Taiwan research project 5G-CORAL (grant number 761586)
Protective Effects of Squid Ink Extract Towards Hemopoietic Injuries Induced by Cyclophosphamine
To investigate the protective effects of squid ink in chemotherapy, BALB/c mice were used as animal models of injuries induced by cyclophosphamine, a well known chemotherapeutic drug. The mice were randomly divided into five groups with the same number of males and females in each group. At the end of the experiment, animals were sacrificed to investigate organ indexes and antioxidant ability of the spleen, peripheral blood profile and quantities of bone marrow nucleated cells. Results showed that the hemopoietic function of mice was injured by cyclophosphamine, as indicated by decreases of contents of erythrocytes, leukocytes, hemoglobin and bone marrow nucleated cells (P<0.01), while platelets were not affected (P>0.05), as well as modification of organ indexes (P<0.05) and spleen antioxidant ability (P<0.05 or P<0.01), whereas sepia extract markedly increased the levels of erythrocytes, leukocytes, hemoglobin and bone marrow nucleated cells (P<0.01), but not platelets (P>0.05), and reversed the effects of cyclophosphamine on organ indexes and antioxidant ability of spleen (P<0.01 or P<0.05). In addition, squid ink extract did not change marrow hemopoiesis but improved the antioxidant ability of spleen in the animals. The data suggest that squid ink extract can protect the hemopoietic system from chemotherapeutic injury and could be employed to develop cell-protective drugs for use in clinical treatment of tumours
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