Decay estimates for one Aharonov-Bohm solenoid in a uniform magnetic field I: Schr\"odinger equation

This is the first of a series of papers in which we investigate the decay estimates for dispersive equations with Aharonov-Bohm solenoids in a uniform magnetic field. In this first starting paper, we prove the local-in-time dispersive estimates and Strichartz estimates for Schr\"odinger equation with one Aharonov-Bohm solenoid in a uniform magnetic field. The key ingredient is the construction of Schr\"odinger propagator, we provide two methods to construct the propagator. The first one is combined the strategies of \cite{FFFP1} and \cite{GYZZ22, FZZ22}, and the second one is based on the Schulman-Sunada formula in sprit of \cite{stov, stov1} in which the heat kernel has been studied. In future papers, we will continue investigating this quantum model for wave with one or multiple Aharonov-Bohm solenoids in a uniform magnetic field.Comment: 22 page

Decay estimates for one Aharonov-Bohm solenoid in a uniform magnetic field II: wave equation

This is the second of a series of papers in which we investigate the decay estimates for dispersive equations with Aharonov-Bohm solenoids in a uniform magnetic field. In our first starting paper \cite{WZZ}, we have studied the Strichartz estimates for Schr\"odinger equation with one Aharonov-Bohm solenoid in a uniform magnetic field. The wave equation in this setting becomes more delicate since a difficulty is raised from the square root of the eigenvalue of the Schr\"odinger operator $H_{\alpha, B_0}$ so that we cannot directly construct the half-wave propagator. An independent interesting result concerning the Gaussian upper bounds of the heat kernel is proved by using two different methods. The first one is based on establishing Davies-Gaffney inequality in this setting and the second one is straightforward to construct the heat kernel (which efficiently captures the magnetic effects) based on the Schulman-Sunada formula. As byproducts, we prove optimal bounds for the heat kernel and show the Bernstein inequality and the square function inequality for Schr\"odinger operator with one Aharonov-Bohm solenoid in a uniform magnetic field.Comment: 35 pages, comments are welcome

PPCR: Learning Pyramid Pixel Context Recalibration Module for Medical Image Classification

Spatial attention mechanism has been widely incorporated into deep convolutional neural networks (CNNs) via long-range dependency capturing, significantly lifting the performance in computer vision, but it may perform poorly in medical imaging. Unfortunately, existing efforts are often unaware that long-range dependency capturing has limitations in highlighting subtle lesion regions, neglecting to exploit the potential of multi-scale pixel context information to improve the representational capability of CNNs. In this paper, we propose a practical yet lightweight architectural unit, Pyramid Pixel Context Recalibration (PPCR) module, which exploits multi-scale pixel context information to recalibrate pixel position in a pixel-independent manner adaptively. PPCR first designs a cross-channel pyramid pooling to aggregate multi-scale pixel context information, then eliminates the inconsistency among them by the well-designed pixel normalization, and finally estimates per pixel attention weight via a pixel context integration. PPCR can be flexibly plugged into modern CNNs with negligible overhead. Extensive experiments on five medical image datasets and CIFAR benchmarks empirically demonstrate the superiority and generalization of PPCR over state-of-the-art attention methods. The in-depth analyses explain the inherent behavior of PPCR in the decision-making process, improving the interpretability of CNNs.Comment: 10 page

Multipole plasmon resonances in self-assembled metal hollow-nanospheres

MOST of China under the 973 programs [2009CB930704]; National Natural Science Foundation of China [61106118]; Science and Technology Project of Fujian Province of China [2013H0046]; Natural Science Foundation of Fujian Province of China [2011J01362]; Fundamental Research Funds for the Central Universities [2011121026]Recently, multipole plasmonic mode resonances in metal hollow structures, such as dipole, quadrupole, and octupole modes, have been widely investigated by researchers with the aim for potential applications in bio-sensing, fluorescence, nanolasers or nonlinear nano-photonics. Here, in this work, the multipole plasmon resonances in self-assembled metal hollow-nanospheres (HNSs) are theoretically and experimentally demonstrated and the hot spots originating from the higher order mode plasmonic resonance and interparticle coupling effect are proposed to be used for Raman scattering enhancements. Dipole, quadrupole, octupole and hexadecapole mode plasmonic resonances were clearly resolved in the extinction spectra of these Ag HNS arrays showing good agreement with the theoretical simulation results. Strong regular hot spots were obtained around the surface and in the gaps of the Ag HNSs through the higher order mode plasmonic resonances and corresponding interparticle coupling effect between the HNSs. Maximum local field intensity was accomplished by optimizing the size of as well as the coupling distance between the HNSs and then it was applied to SERS sensing. Raman mapping also demonstrated these self-assembled plasmonic cavity arrays to be a stable and uniform SERS-active substrate

Self-organization of 3D triangular GaN nanoislands and the shape variation to hexagonal

We report on the self-organization of large-scale uniform aligned three-dimensional (3D) GaN islands with distinct triangular (0001) and smooth side facets and the shape variations of the (0001) facets from triangular to hexagonal during metalorganic vapor-phase epitaxy (MOVPE) growth of GaN films on Si-rich SiNx patterned sapphire substrates. The triangular island shaping during the recrystallization processes of GaN nucleation layers (NLs) can be attributed to the enhanced diffusion and regrowth anisotropy. The island shape transition from triangular to hexagonal in the early stages of high-temperature growth of GaN epilayers is due to the gas-phase transport dominating growth mechanism and the limited diffusion length of edge adatoms compared with the increased island size

The Effects and Mechanisms of Periplaneta americana Extract Reversal of Multi-Drug Resistance in BEL-7402/5-FU Cells

The present study reports the reversing effects of extracts from P. americana on multidrug resistance of BEL-7402/5-FU cells, as well as a preliminary investigation on their mechanism of action. A methylthiazolyl tetrazolium (MTT) method was applied to determine the multidrug resistance of BEL-7402/5-FU, while an intracellular drug accumulation assay was used to evaluate the effects of a column chromatography extract (PACC) and defatted extract (PADF) from P. americana on reversing multi-drug resistance. BEL-7402/5-FU reflected high resistance to 5-FU; PACC and PADF could promote drug accumulation in BEL-7402/5-FU cells, among which PADF was more effective than PACC. Moreover, results from the immunocytochemical method showed that PACC and PADF could downregulate the expression of drug resistance-associated proteins (P-gp, MRP, LRP); PACC and PADF had no effects on the expression of multidrug resistance-associated enzymes (GST-π), but PACC could increase the expression of multidrug resistance-associated enzymes (PKC). Results of real-time fluorescence quantitative PCR revealed that PACC and PADF were able to markedly inhibit the expression of multidrug resistance-associated genes (MDR1, LRP and MRP1); PACC presented a significant impact on the gene expression of multidrug resistance-associated enzymes, which increased the gene expression of GST-π and PKC. However, PADF had little impact on the expression of multidrug resistance-associated enzymes. These results demonstrated that PACC and PADF extracted from P. americana could effectively reverse MDR in BEL-7402/5-FU cells, whose mechanism was to inhibit the expression of P-gp, MRP, and LRP, and that PADF was more effective in the reversal of MDR than did PACC. In addition, some of extracts from P. americana altered (sometimes increasing) the expression of multidrug resistance-associated enzymes

MOCVD growth of GaN films on Si-rich SiNx nanoislands patterned sapphire - art no 69842V

We intentionally patterned Si-rich SiNX nanoislands on sapphire substrates and found the SiNx significantly influenced the subsequent growth of GaN films. Distinct GaN islands of triangular base were formed caused by the enhanced diffusion and regrowth anisotropy during the annealing processes of GaN nucleation layers. Subsequent growth of GaN epilayers at high temperature with initial low V/III ratios on the nucleated triangular islands resulted in island coarsening and shape variations from triangular to hexagonal due to the dominating gas phase transport growth mechanism and limited diffusion length. Further growth with high V/III ratios eventually resulted in layer-growth with surface roughness of similar to 2.6 A. Both AFM and XRD results showed a significant improvement of the crystalline qualities with estimated threading dislocation (TD) density of about 1 x 10(8) cm(-2) when Si-rich SiNx nanoislands patterning was performed. Photoluminescence measurements showed that the yellow and blue emissions were substantially suppressed

MOCVD growth of GaN films on Si-rich SiNx nanoislands patterned sapphire - art no 69842V

We intentionally patterned Si-rich SiNX nanoislands on sapphire substrates and found the SiNx significantly influenced the subsequent growth of GaN films. Distinct GaN islands of triangular base were formed caused by the enhanced diffusion and regrowth anisotropy during the annealing processes of GaN nucleation layers. Subsequent growth of GaN epilayers at high temperature with initial low V/III ratios on the nucleated triangular islands resulted in island coarsening and shape variations from triangular to hexagonal due to the dominating gas phase transport growth mechanism and limited diffusion length. Further growth with high V/III ratios eventually resulted in layer-growth with surface roughness of similar to 2.6 A. Both AFM and XRD results showed a significant improvement of the crystalline qualities with estimated threading dislocation (TD) density of about 1 x 10(8) cm(-2) when Si-rich SiNx nanoislands patterning was performed. Photoluminescence measurements showed that the yellow and blue emissions were substantially suppressed

Porcine Epidemic Diarrhea Virus Antagonizes Host IFN-λ-Mediated Responses by Tilting Transcription Factor STAT1 toward Acetylation over Phosphorylation To Block Its Activation

ABSTRACT Porcine epidemic diarrhea virus (PEDV) is the main etiologic agent causing acute swine epidemic diarrhea, leading to severe economic losses to the pig industry. PEDV has evolved to deploy complicated antagonistic strategies to escape from host antiviral innate immunity. Our previous study demonstrated that PEDV downregulates histone deacetylase 1 (HDAC1) expression by binding viral nucleocapsid (N) protein to the transcription factor Sp1, inducing enhanced protein acetylation. We hypothesized that PEDV inhibition of HDAC1 expression would enhance acetylation of the molecules critical in innate immune signaling. Signal transducer and activator of transcription 1 (STAT1) is a crucial transcription factor regulating expression of interferon (IFN)-stimulated genes (ISGs) and anti-PEDV immune responses, as shown by overexpression, chemical inhibition, and gene knockdown in IPEC-J2 cells. We further show that PEDV infection and its N protein overexpression, although they upregulated STAT1 transcription level, could significantly block poly(I·C) and IFN-λ3-induced STAT1 phosphorylation and nuclear localization. Western blotting revealed that PEDV and its N protein promote STAT1 acetylation via downregulation of HDAC1. Enhanced STAT1 acetylation due to HDAC1 inhibition by PEDV or MS-275 (an HDAC1 inhibitor) impaired STAT1 phosphorylation, indicating that STAT1 acetylation negatively regulated its activation. These results, together with our recent report on PEDV N-mediated inhibition of Sp1, clearly indicate that PEDV manipulates the Sp1-HDAC1-STAT1 signaling axis to inhibit transcription of OAS1 and ISG15 in favor of its replication. This novel immune evasion mechanism is realized by suppression of STAT1 activation through preferential modulation of STAT1 acetylation over phosphorylation as a result of HDAC1 expression inhibition. IMPORTANCE PEDV has developed sophisticated evasion mechanisms to escape host IFN signaling via its structural and nonstructural proteins. STAT1 is one of the key transcription factors in regulating expression of ISGs. We found that PEDV and its N protein inhibit STAT1 phosphorylation and nuclear localization via inducing STAT1 acetylation as a result of HDAC1 downregulation, which, in turn, dampens the host IFN signaling activation. Our study demonstrates a novel mechanism that PEDV evades host antiviral innate immunity through manipulating the reciprocal relationship of STAT1 acetylation and phosphorylation. This provides new insights into the pathogenetic mechanisms of PEDV and even other coronaviruses