High Speed Mid-Wave Infrared Uni-traveling Carrier Photodetector

Mid-wave infrared (MWIR) frequency comb is expected to dramatically improve the precision and sensitivity of molecular spectroscopy. For high resolution application, high speed MWIR photodetector is one of the key components, however, the commercially available high speed MWIR photodetector only has sub-GHz bandwidth currently. In this paper, we demonstrate, for the first time to our knowledge, a high speed mid-wave infrared (MWIR) uni-traveling carrier photodetector based on InAs/GaSb type-II superlattice (T2SL) at room temperature. The device exhibits a cutoff wavelength of 5.6{\mu}m, and 3dB bandwidth of 6.58 GHz for a 20{\mu}m diameter device at 300K. These promising results show the device has potential to be utilized in high speed applications such as frequency comb spectroscopy, free space communication and others. The limitations on the high frequency performance of the photodetectors are also discussed

Passive detection of moving aerial target based on multiple collaborative GPS satellites

Passive localization is an important part of intelligent surveillance in security and emergency applications. Nowadays, Global Navigation Satellite Systems (GNSSs) have been widely deployed. As a result, the satellite signal receiver may receive multiple GPS signals simultaneously, incurring echo signal detection failure. Therefore, in this paper, a passive method leveraging signals from multiple GPS satellites is proposed for moving aerial target detection. In passive detection, the first challenge is the interference caused by multiple GPS signals transmitted upon the same spectrum resources. To address this issue, successive interference cancellation (SIC) is utilized to separate and reconstruct multiple GPS signals on the reference channel. Moreover, on the monitoring channel, direct wave and multi-path interference are eliminated by extensive cancellation algorithm (ECA). After interference from multiple GPS signals is suppressed, the cycle cross ambiguity function (CCAF) of the signal on the monitoring channel is calculated and coordinate transformation method is adopted to map multiple groups of different time delay-Doppler spectrum into the distance−velocity spectrum. The detection statistics are calculated by the superposition of multiple groups of distance-velocity spectrum. Finally, the echo signal is detected based on a properly defined adaptive detection threshold. Simulation results demonstrate the effectiveness of our proposed method. They show that the detection probability of our proposed method can reach 99%, when the echo signal signal-to-noise ratio (SNR) is only −64 dB. Moreover, our proposed method can achieve 5 dB improvement over the detection method using a single GPS satellite

STARFlow: Spatial Temporal Feature Re-embedding with Attentive Learning for Real-world Scene Flow

Scene flow prediction is a crucial underlying task in understanding dynamic scenes as it offers fundamental motion information. However, contemporary scene flow methods encounter three major challenges. Firstly, flow estimation solely based on local receptive fields lacks long-dependency matching of point pairs. To address this issue, we propose global attentive flow embedding to match all-to-all point pairs in both feature space and Euclidean space, providing global initialization before local refinement. Secondly, there are deformations existing in non-rigid objects after warping, which leads to variations in the spatiotemporal relation between the consecutive frames. For a more precise estimation of residual flow, a spatial temporal feature re-embedding module is devised to acquire the sequence features after deformation. Furthermore, previous methods perform poor generalization due to the significant domain gap between the synthesized and LiDAR-scanned datasets. We leverage novel domain adaptive losses to effectively bridge the gap of motion inference from synthetic to real-world. Experiments demonstrate that our approach achieves state-of-the-art performance across various datasets, with particularly outstanding results on real-world LiDAR-scanned datasets. Our code is available at https://github.com/O-VIGIA/StarFlow.Comment: 10 pages, 8 figures, CVPR templat

Highly sensitive label-free colorimetric sensing of nitrite based on etching of gold nanorods

A simple colorimetric method with high sensitivity and selectivity was developed for sensing of nitrite as low as 4.0 mu M by naked eyes, which is based on etching of gold nanorods accompanied by shape changes in aspect ratios (length/width) and a visible color change from bluish green to red and then to colorless with the increase of nitrite

Effects of icariin and quercetin on high glucose-induced neuronal cell apoptosis

Purpose: To study the effects of icariin and quercetin on cell apoptotic changes in neurons induced by elevated glucose condition, and the  mechanism involved. Methods: Neonatal male Sprague Dawley rats (n = 48) weighing 5 – 7 g were used. Neuronal cells were isolated from rat hippocampus and cultured after purification. The cells were randomly assigned to six groups: control, high glucose, icariin, quercetin, serine/threonine-specific protein kinase (Akt) inhibitor, and Akt agonist groups. The Akt inhibitor and agonist used in this study were MK-22062hci and SC79, respectively. The influence of icariin and quercetin on neuronal apoptotic changes were determined flow cytometrically, while their effects on levels of expression of Akt, p-Akt, bax and bcl-2 were determined with Western blotting. Results: Treatment with icariin or quercetin significantly inhibited apoptosis induced by high glucose. The concentrations of Akt, p-Akt, and bcl-2 proteins were markedly upregulated in high glucose group, relative to control (p < 0.05). The corresponding expression of bax was significantly down-regulated in high glucose group, relative to control (p < 0.05). Treatment with icariin or quercetin, or their agonists reversed high glucose-mediated alterations in these protein levels (p < 0.05). Conclusion: Icariin and quercetin inhibit neuronal cell apoptosis induced by high glucose through upregulation of bcl-2 expression and down- regulations of bax expression and Akt-induced protein phosphorylation. Thus, Icariin and quercetin possess potential benefits for the treatment of neurological diseases. Keywords: Apoptosis, High glucose condition, Hippocampal neurons, Icariin, Querceti

Fluorescent sensing of mercury(II) based on formation of catalytic gold nanoparticles

A fluorescence assay for the highly sensitive and selective detection of Hg2+ using a gold nanoparticle (AuNP)-based probewas proposed. The assay was based on the formation of Hg-Au alloys, which accelerated the oxidization of o-phenylenediamine by dissolved oxygen to produce 2,3-diaminophenazine, a fluorescent product.;A fluorescence assay for the highly sensitive and selective detection of Hg2+ using a gold nanoparticle (AuNP)-based probewas proposed. The assay was based on the formation of Hg-Au alloys, which accelerated the oxidization of o-phenylenediamine by dissolved oxygen to produce 2,3-diaminophenazine, a fluorescent product