An Yb-fiber frequency comb phase-locked to microwave standard and optical reference

We present a fully stabilized Yb-fiber frequency comb locked to a microwave standard and an optical reference separately. The carrier-envelope offset frequency is generated by a standard f–2f interferometer with 40 dB signal-tonoise ratio. The offset frequency and the repetition rate are stabilized simultaneously to the radio frequency reference for more than 30 hours, and the fractional Allan deviation of the comb is the same as the microwave standard of 10^(-12) at 1 s.Alternatively, the comb is locked to an ultra-stable optical reference at 972 nm using an intracavity electro-optic modulator,exhibiting a residual integrated phase noise of 458 mrad(1 Hz–10 MHz) and an in-loop tracking stability of 1.77× 10^(-18) at 1 s, which is significantly raised by six orders comparing to the case locked to the microwave frequency standard.

Monolithic 0–f Scheme-Based Frequency Comb Directly Driven by a High-Power Ti:Sapphire Oscillator

A monolithic O-f scheme-based femtosecond optical frequency comb directly driven by a high-power Ti:sapphire laser oscillator is demonstrated.The spectrum covering from 650 nm to 950 nm is generated from the Ti:sapphire oscillator with a repetition rate of 170 MHz.The average output power up to 630 mW is delivered under the pump power of 4.5 W.A 44-dB signal-to-noise ratio(SNR)of the carrier-envelope phase offset(CEO)beat note is achieved under the resolution of 100 kHz and is long-term stabilized to a reference source at 20 MHz.The integrated phase noise(IPN)in the range from 1 Hz to 1 MHz is calculated to be 138 mrad,corresponding to the timing jitter of 63 as at the central wavelength of 790 nm.

Gastrointestinal bleeding caused by jejunal angiosarcoma: A case report

BACKGROUND Angiosarcoma is a rare disease with a poor prognosis.Its occurrence in the small intestine is low,and gastrointestinal bleeding caused by small intestinal angiosarcoma is unusual.CASE SUMMARY Here,we report the case of a 57-year-old man who presented with hematochezia for 1 mo.The patient had a medical history of chronic viral hepatitis B for 15 years.The causes of gastrointestinal bleeding were initially diagnosed as esophagogastric variceal bleeding or portal hypertensive gastropathy before endoscopy.However,after a complicated diagnostic and therapeutic process,including gastroendoscopy,colonoscopy,contrast-enhanced computed tomographic(CT),positron emission computed tomography/CT,capsule endoscopy,and pathological and immunohistochemical examinations,small intestinal angiosarcoma was diagnosed.Arrest of bleeding was achieved after surgical treatment.Furthermore,the patient had lung cancer with bone and adrenal metastases.At the follow-up 10 mo after the operation,the patient was alive.CONCLUSION Gastroenterologists should maintain strong vigilance to small intestinal angiosarcoma,which is necessary for the early identification of this infrequent but fatal disease.

慢性疼痛及其诱发负面情绪的神经环路及电针调节机制

Chronic pain is a common clinical condition that is frequently linked to negative emotions such as anxiety and depression.Electroacupuncture(EA) has been shown to have beneficial therapeutic effects in analgesia and the reduction of pain-induced negative emotions,and promising results have been obtained in the study of its neural circuit mechanism.Optogenetics,chemogenetics,neurocircuit tracing,functional magnetic resonance imaging(fMRI),and conditional gene knockdown experiments have shown that EA activates parvalbumin(PV) interneurons in the anterior cingulate cortex(ACC),inhibits Protein kinase Mzeta-glutamate receptor(PKMzeta-GluR1) signaling pathway in ACC,and upregulates the expression of the neuropeptide S/neuropeptide S receptor(NPS/NPSR) system in ACC to alleviate pain and pain-induced anxiety.EA activates endogenous cannabinoid receptors 1(CB1Rs),inhibits y-aminobutyric acid(^(GABA))-ergic neurons and activates glutamatergic neurons in the ventrolateral periaqueductal gray(vlPAG) to exert an analgesic effect,while EA exerts an anxiolytic effect by downregulating CB1R in ^(GABA)ergic neurons in the ventral hippocampus(vHPC).EA relieves only pain-induced anxiety but not pain through inhibiting the rostral anterior cingulate cortex(rACC)Glu-thalamus circuit.By inhibiting the medial prefrontal cortex(mPFC)Glu-vlPAC^(GABA)circuit,EA relieves only pain but not pain-induced anxiety.EA activated dopamine receptor D1(DRD1) or inhibited dopamine receptor D2(DRD2) in the basolateral amygdala(BLA) to alleviate anxiety-like behaviors.Taken together,these findings would offer a novel theoretical framework for a thorough investigation of theoretical studies and clinical promotion of EA analgesic mechanisms.

觉华岛海域人工鱼礁生态系统能量传递与功能研究

人工鱼礁是海洋牧场建设的重要组成部分,阐明其系统结构特征及能量流动规律是评估人工鱼礁资源养护和生态修复的重要基础。本文以辽东湾觉华岛海域人工鱼礁生态系统为研究对象,基于2019年春、夏、秋季的生物资源调查,通过稳定同位素技术和生态通道(Ecopath)模型构建了该人工鱼礁系统的生态通道模型,揭示了人工鱼礁建设的生态修复效果。研究结果显示,该生态系统以牧食食物链占主导,营养级为1~4.10,最高营养级为鲬,关键种为日本蟳。系统总能量传递效率为6.28%,35.08%的能量未进一步利用,流入碎屑。总初级生产/总呼吸为2.98,显示该系统为自养演替;联结指数为0.28,系统杂食指数为0.32,Finn’s循环指数为6.08%,平均能流路径长度为2.49,说明该系统的生态系统规模、物质再循环率、复杂度及稳定性均较高,但仍处于发育阶段,距离成熟系统仍有一定差距。