261 research outputs found
Optical Diode Based on Two-Dimensional Photonic Crystal
The integrated optical diodes have been a thriving research theme due to their potential on-chip applications in photonic circuits for all-optical computing and information processing. Analogous to electronic counterparts, the unidirectional light propagation is characterized by the high contrast between forward and backward transmissions. In this chapter, we demonstrate the proposed schemes and designs for reciprocal and nonreciprocal optical diodes based on two-dimensional (2D) photonic crystal (PhC). The reciprocal devices are built by linear and passive PhC, and the spatial asymmetric mode conversion is utilized to achieve the unidirectionality. The presented nonreciprocal optical diodes rely on the optical nonlinearity of cavity. New 2D PhC optical diodes with high contrast ratio, low insertion loss, large operational bandwidth, small device footprint, and ease of fabrication are highly desirable and still pursued
Quantum Dynamics of a Microwave Driven Superconducting Phase Qubit Coupled to a Two-Level System
We present an analytical and comprehensive description of the quantum
dynamics of a microwave resonantly driven superconducting phase qubit coupled
to a microscopic two-level system (TLS), covering a wide range of the external
microwave field strength. Our model predicts several interesting phenomena in
such an ac driven four-level bipartite system including anomalous Rabi
oscillations, high-contrast beatings of Rabi oscillations, and extraordinary
two-photon transitions. Our experimental results in a coupled qubit-TLS system
agree quantitatively very well with the predictions of the theoretical model.Comment: 6 pages, 3 figure
Epothilone B Benefits Nigral Dopaminergic Neurons by Attenuating Microglia Activation in the 6-Hydroxydopamine Lesion Mouse Model of Parkinson’s Disease
Parkinson’s disease (PD) is characterized by loss of dopamine (DA) neurons in the substantia nigra pars compacta (SNc) and a subsequent reduction in striatal DA levels. Recent studies have shown that systemic administration of subtoxic doses of epothilone B (EpoB), a microtubule stabilizing agent, enhances axonal regeneration. However, the underlying alterations in cellular mechanisms remain undetermined. In the present study, we investigated the neuroprotective effects of EpoB on DA neurons in mouse model of PD induced by 6-hydroxyDA (6-OHDA) and in vitro. The results indicated that EpoB improved behavioral deficits, protected the nigrostriatal dopaminergic projections and restored DA level in the striatum of mice exposed to 6-OHDA. Meanwhile, EpoB attenuated microglia activation in the SNc of PD mice. Furthermore, EpoB treatment ameliorated 6-OHDA induced cytotoxicity to MN9D dopaminergic cells in a co-culture transwell system of BV2/MN9D cells, and redistributed the cytoskeleton of microglial BV2 and caused the morphological transition, inhibited the polarization to the M1 phenotype by suppressing expression of pro-inflammatory factors including interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α. Overall, our study suggested that EpoB treatment protects nigral DA neurons and projections through limiting the cytotoxicity of activated microglia in 6-OHDA lesioned mice
Power allocation for cache-aided small-cell networks with limited backhaul
Cache-aided small-cell network is becoming an effective method to improve the transmission rate and reduce the backhaul load. Due to the limited capacity of backhaul, less power should be allocated to users whose requested contents do not exist in the local caches to maximize the performance of caching. In this paper, power allocation is considered to improve the performance of cache-aided small-cell networks with limited backhaul, where interference alignment (IA) is utilized to manage interferences among users. Specifically, three power allocation algorithms are proposed. First, we come up with a power allocation algorithm to maximize the sum transmission rate of the network, considering the limitation of backhaul. Second, in order to have more users meet their rate requirements, a power allocation algorithm to minimizing the average outage probability is also proposed. In addition, in order to further improve the users’ experience, a power allocation algorithm that maximizes the average satisfaction of all the users is also designed. Simulation results are provided to show the effectiveness of the three proposed power allocation algorithms for cache-aided small-cell networks with limited backhaul
An End-to-End Network for Co-Saliency Detection in One Single Image
As a common visual problem, co-saliency detection within a single image does
not attract enough attention and yet has not been well addressed. Existing
methods often follow a bottom-up strategy to infer co-saliency in an image,
where salient regions are firstly detected using visual primitives such as
color and shape, and then grouped and merged into a co-saliency map. However,
co-saliency is intrinsically perceived in a complex manner with bottom-up and
top-down strategies combined in human vision. To deal with this problem, a
novel end-to-end trainable network is proposed in this paper, which includes a
backbone net and two branch nets. The backbone net uses ground-truth masks as
top-down guidance for saliency prediction, while the two branch nets construct
triplet proposals for feature organization and clustering, which drives the
network to be sensitive to co-salient regions in a bottom-up way. To evaluate
the proposed method, we construct a new dataset of 2,019 nature images with
co-saliency in each image. Experimental results show that the proposed method
achieves a state-of-the-art accuracy with a running speed of 28fps
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