4,497 research outputs found
Parity-time electromagnetic diodes in a two-dimensional nonreciprocal photonic crystal
We propose a kind of electromagnetic (EM) diode based on a two-dimensional nonreciprocal gyrotropic photonic crystal. This
periodic microstructure has separately broken symmetries in both parity
(P) and time-reversal (T) but obeys parity-time (PT) symmetry. This
kind of diode could support bulk one-way propagating modes either for
group velocity or phase velocity with various types of negative and
positive refraction. This symmetry-broken system could be a platform to
realize abnormal photoelectronic devices, and it may be analogous to an
electron counterpart with one-way features
The collective motion of self-propelled particles affected by the spatial-dependent noise
We study the collective motion of self-propelled particles affected by the
spatial-dependent noise based on the Vicsek rules. Only the particles inside
the special region will affected by noise. The consideration of the
spatial-dependent noise is closer to reality because of the complexity of the
environment. Interestingly, we find that there exists an optimal amplitude of
noise to adjust the average motional direction of the system. Particular
orientation of the noisy region makes the motional direction of the system
parallel to the orientation of the noisy region. The adjustment of the motional
direction of the system also depends on the shape, the proportion and the
spatial distribution of the noisy region. Our findings may inspire the capture
of the key features of collective motion underlying various phenomena.Comment: 12 pages, 6 figures, 39 reference
Olmesartan restores the protective effect of remote ischemic perconditioning against myocardial ischemia/reperfusion injury in spontaneously hypertensive rats
OBJECTIVES: Remote ischemic perconditioning is the newest technique used to lessen ischemia/reperfusion injury. However, its effect in hypertensive animals has not been investigated. This study aimed to examine the effect of remote ischemic perconditioning in spontaneously hypertensive rats and determine whether chronic treatment with Olmesartan could influence the effect of remote ischemic perconditioning. METHODS: Sixty rats were randomly divided into six groups: vehicle-sham, vehicle-ischemia/reperfusion injury, vehicle-remote ischemic perconditioning, olmesartan-sham, olmesartan-ischemia/reperfusion and olmesartan-remote ischemic perconditioning. The left ventricular mass index, creatine kinase concentration, infarct size, arrhythmia scores, HIF-1α mRNA expression, miR-21 expression and miR-210 expression were measured. RESULTS: Olmesartan significantly reduced the left ventricular mass index, decreased the creatine kinase concentration, limited the infarct size and reduced the arrhythmia score. The infarct size, creatine kinase concentration and arrhythmia score during reperfusion were similar for the vehicle-ischemia/reperfusion group and vehicle-remote ischemic perconditioning group. However, these values were significantly decreased in the olmesartan-remote ischemic perconditioning group compared to the olmesartan-ischemia/reperfusion injury group. HIF-1α, miR-21 and miR-210 expression were markedly down-regulated in the Olmesartan-sham group compared to the vehicle-sham group and significantly up-regulated in the olmesartan-remote ischemic perconditioning group compared to the olmesartan-ischemia/reperfusion injury group. CONCLUSION: The results indicate that (1) the protective effect of remote ischemic perconditioning is lost in vehicle-treated rats and that chronic treatment with Olmesartan restores the protective effect of remote ischemic perconditioning; (2) chronic treatment with Olmesartan down-regulates HIF-1α, miR-21 and miR-210 expression and reduces hypertrophy, thereby limiting ischemia/reperfusion injury; and (3) recovery of the protective effect of remote ischemic perconditioning is related to the up-regulation of HIF-1α, miR-21 and miR-210 expression
ab-plane tilt angles in REBCO conductors
Critical current (Ic) of REBCO tapes is strongly aniso-tropic with respect to
the orientation of the magnetic field. Usually, Ic is at maximum when the
ab-plane of the REBCO crystal is parallel to the magnetic field. In commercial
REBCO tapes, it is commonly assumed that the ab-plane is coincide with the tape
plane. While in fact, the ab-plane is near but slightly tilted from the tape
plane in the transverse direction. To accurately measure Ic as a function of
the field angle {\theta} , which is defined as the angle between ab-plane and
the magnetic field direction, and to design and fabricate REBCO mag-net coils
based on the measured Ic(angle), it is important to measure the tilt angle. In
this work, we used x-ray diffraction (XRD) to measure the tilt angles at room
temperature for a large number of REBCO conductors made by SuperPower Inc.
Transmission electron mi-croscopy (TEM) was also used to investigate the origin
of this tilt. The measured data are presented, and the measurement uncer-tainty
is discussed.Comment: 4 pages, 7 figure
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