Tunable superluminal propagation at spectral hole-burning regions in magneto-optical atomic medium

In the context of spectral hole-burning, normal dispersion with subluminal propagation is usually observed in the spectral hole-burning depth region. However, anomalous dispersion can occur in the continuous absorption peak region, which leads to superluminal light propagation. In this paper, we report an unusual behavior of dispersion at discontinued absorption kink regions. We demonstrate both normal dispersion at the kink absorption region and anomalous dispersion at the spectral hole-burning depth region. The unusual dispersion leads to a positive group index in the absorption kink region and a negative group index in the spectral hole-burning depth region. The spectral hole-burning is due to variation of magnetization rather than the molecular distribution. The outcomes of our work offer promising applications in communication technologies and storage devices

Hardware-algorithm collaborative computing with photonic spiking neuron chip based on integrated Fabry-P\'erot laser with saturable absorber

Photonic neuromorphic computing has emerged as a promising avenue toward building a low-latency and energy-efficient non-von-Neuman computing system. Photonic spiking neural network (PSNN) exploits brain-like spatiotemporal processing to realize high-performance neuromorphic computing. However, the nonlinear computation of PSNN remains a significant challenging. Here, we proposed and fabricated a photonic spiking neuron chip based on an integrated Fabry-P\'erot laser with a saturable absorber (FP-SA) for the first time. The nonlinear neuron-like dynamics including temporal integration, threshold and spike generation, refractory period, and cascadability were experimentally demonstrated, which offers an indispensable fundamental building block to construct the PSNN hardware. Furthermore, we proposed time-multiplexed spike encoding to realize functional PSNN far beyond the hardware integration scale limit. PSNNs with single/cascaded photonic spiking neurons were experimentally demonstrated to realize hardware-algorithm collaborative computing, showing capability in performing classification tasks with supervised learning algorithm, which paves the way for multi-layer PSNN for solving complex tasks.Comment: 10 pages, 8 figure

Adaptive polarization photoacoustic computed tomography for biological anisotropic tissue imaging

Most photoacoustic computed tomography (PACT) systems usually ignore the anisotropy of the tissue absorption coefficient, which will lead to the lack of information in reconstructed images. In this work, the effect is addressed of the possible optical absorption anisotropy of tissue on PACT images. The functional relationship is derived between the photoacoustic response and the polarization angle of the excitation light. An adaptive polarized light photoacoustic imaging (AP-PACT) approach is proposed and shown to make up for the lack of imaging information and achieve optimal image contrast when imaging samples with anisotropic optical absorption, by utilizing the standard deviation of photoacoustic response as the feedback signal in an adaptive data acquisition process. The method is implemented both on phantom and in vitro experiments, which show that AP-PACT can recover anisotropic absorption-related information from reconstructed images and thus significantly improve their quality

A novel heterozygous variant of FOXJ1 in a Chinese female with primary ciliary dyskinesia and hydrocephalus: A case report and literature review

Abstract Background Primary ciliary dyskinesia (PCD) is a type of ciliary dyskinesia that is usually caused by autosomal recessive inheritance and can manifest as recurrent respiratory infections, bronchiectasis, infertility, laterality defects, and chronic otolaryngological disease. Although ependymal cilia, which affect the flow of cerebrospinal fluid in the central nervous system, have much in common with respiratory cilia in terms of structure and function, hydrocephalus is rarely associated with PCD. Recently, variants of Forkhead box J1 (FOXJ1) have been found to cause PCD combined with hydrocephalus in a de novo, autosomal dominant inheritance pattern. Methods We performed DNA extraction, whole‐exome sequencing (WES) analysis, and mutation analysis of FOXJ1 and analyzed the patient's clinical and genetic data. Results The patient was a 4‐year‐old female exhibiting normal growth and development. At 3 years and 2 months of age, the patient experienced hand shaking and weakness in the lower limbs. Cardiac ultrasonography showed a right‐sided heart, and cranial magnetic resonance imaging showed obstructive hydrocephalus. The nasal nitric oxide level was 54 nL/min. WES indicated a de novo, heterozygous variant of FOXJ1, c.734–735 ins20. This variant was novel, not included in the Human Gene Mutation and Genome Aggregation Database, and likely pathogenic according to the American College of Medical Genetics and Genomics, causing earlier termination of amino acid translation. The patient underwent a neuroendoscopic third ventriculostomy after the diagnosis of obstructive hydrocephalus. Six months after the operation, the patient's motor deficits had improved. Conclusion This is the first report of a de novo, autosomal dominant pattern of FOXJ1 causing PCD combined with hydrocephalus in China. The patient's clinical symptoms were similar to those previously reported. WES confirmed that a novel variant of FOXJ1 was the cause of the PCD combined with hydrocephalus, expanding the spectrum of the genotypes associated with this condition. Physicians should be aware of the correlation of hydrocephalus and PCD and test for FOXJ1 variants

Hardware-algorithm collaborative computing with photonic spiking neuron chip based on integrated Fabry–Pérot laser with saturable absorber

No abstract available