White Rabbit技术在时敏领域应用综述

White Rabbit同步技术是传统PTP(IEEE1588v2)协议的扩展,增加了皮秒级时间戳、频率相位同步、稳定传输时延等功能,在时频/数据一体化传输方面性能卓越。针对White Rabbit在时间敏感领域的应用现状,归纳了时间频率传递、精准时间戳标记、射频信号分布传输、定时触发控制等应用方式,详细介绍了各类具体应用的实现方法和性能指标。通过分析当前采用的增强手段和未来发展趋势,展望该技术在各领域广泛的应用前景。

White Rabbit Leaping Toward a New Field

You may still remember the story about the race between the big white rabbit and little tortoise, in which the over-proud rabbit lost. However, the White Rabbit toffees produced by the Shanghai Guansheng Yuan (Group) Co., Ltd. are famous-brand products in China. This White Rabbit not only is the cham-

A real-time calibration method based on time-to-digital converter for accelerator timing system

The high-intensity heavy-ion accelerator facility(HIAF)is a scientific research facility complex composed of multiple cas-cade accelerators of different types,which pose a scheduling problem for devices distributed over a certain range of 2 km,involving over a hundred devices.The white rabbit,a technology-enhancing Gigabit Ethernet,has shown the capability of scheduling distributed timing devices but still faces the challenge of obtaining real-time synchronization calibration param-eters with high precision.This study presents a calibration system based on a time-to-digital converter implemented on an ARM-based System-on-Chip(SoC).The system consists of four multi-sample delay lines,a bubble-proof encoder,an edge controller for managing data from different channels,and a highly effective calibration module that benefits from the SoC architecture.The performance was evaluated with an average RMS precision of 5.51 ps by measuring the time intervals from 0 to 24,000 ps with 120,000 data for every test.The design presented in this study refines the calibration precision of the HIAF timing system.This eliminates the errors caused by manual calibration without efficiency loss and provides data support for fault diagnosis.It can also be easily tailored or ported to other devices for specific applications and provides more space for developing timing systems for particle accelerators,such as white rabbits on HIAF.

Ⅱ型糖尿病兔大脑皮质和海马神经元的神经丝蛋白表达(英文)

Objective:To investigate the morphological changes of the neuronal neurites in diabetic rabbit brain. Methods: Twenty- four New Zealand White rabbits were divided into 2 groups: control group and type Ⅱ diabetic group induced by high - carbohydrate and high- fat diet. The levels of blood sugar and insulin were detected at week 0(w0), w4, w8, w13, w18, w23 and w28. Brain tissue was stained by Nissl staining and immunolistochemistry with a specific antibody to neurofilament proteins. Result: In diabetic rabbits, the amount of large pyramidal neuron was significantly reduced, and neuronal neurites became swollen, whorled, disrupted and changed in caliber. In hippocampus CA1 region neurofilament staining was very weak. Conclusion: Neurotoxicity of chronic hyperglycemia might be relevant to vascular chronic complications, which affected the expression of NF and led to neurophysiological and structural changes in the brain of rabbits with type Ⅱ diabetes.

Production of Rabbit Polyclonal Antibody Using hAPOA1 Protein Expressed in Prokaryotic Cells

The open reading frame （ORF） of hAPOA1 was inserted into the prokaryotic expression vector pGEX-4T-1 to construct the recombinant plasmid pGEX- 4T-I-hAPOA1, which was then transformed into Escherichia coil strain BL21. The expression of target fusion protein was induced with isopropyl β-D-l-thiogalacto- pyranoside （IPTG）. The purified fusion protein in inclusion bodies was used to immunize New Zealand white rabbits to prepare hAPOA1 antiserum and the antibody titer was detected with indirect enzyme-linked immunosorbent assay （ID-EL1SA）. ID-ELISA and Western Blot proved that rabbit polyclonal antibody with a high titer of 1 ： 40 000 was produced, which may bring considerable economic benefits.

面向5G网络应用的精确时间同步协议测试与分析

随着5G的普及和基站建设,对基站间时间同步精度提出了更高的要求.目前,精确时间同步协议(PTP)只能达到几十纳秒,且频率分布效果差,将其结合同步以太网(SyncE)技术后可以实现网络上所有时钟的频率与时钟源同步.WR(White Rabbit)技术在PTP+SyncE的基础上加入了全数字双混频鉴相器(DDMTD),对节点间相位差进行调整补偿,消除由相位噪声长时间累积引起的不同步,动态实现了整个网络节点的时钟同步.本文分别介绍了将SyncE与PTP结合的同步方法和WR同步方法的原理及实现过程,最后构建实验平台验证同步过程,测试证明可以分别达到百皮秒和几十皮秒的抖动,同步精度分别能达到纳秒和亚纳秒级别.

观察性健康数据科学和信息学组织实用工具简介

运用真实世界大数据进行药品不良反应主动监测受到了国内外学者的高度关注。其中如何实现多个形式不一数据库之间的数据整合,仍然是发挥大数据优势对药品不良反应进行主动监测时存在的一个巨大的挑战。本文旨在通过介绍观察性健康数据科学和信息学(OHDSI)组织的几种工具软件,为我国开展药品不良反应主动监测的数据整合提供思路及方向。

全数字双混频鉴相技术亚稳态抑制方法研究

全数字双混频鉴相技术(DDMTD)是一种高精度的相位检测技术,在White Rabbit中主要负责完成两路同周期信号的高精度相位差检测。在全数字双混频鉴相技术中,可以根据实际功能进行功能模块划分,信号采样放大模块中通常使用D触发器将输入信号的周期进行采样放大,但会存在明显的亚稳态问题。本文主要通过改进DDMTD中信号采样放大模块的设计方案来降低亚稳态对鉴相结果的影响,减小DDMTD相位差检测误差。实验采用40 MHz信号进行测试实验,经过原方案与改进方案的结果比对可以得出改进方案对于信号边沿毛刺问题的改善有着明显效果。

上海软X射线自由电子激光装置束线站定时系统

上海软X射线自由电子激光装置由活细胞结构与功能成像等线站工程和软X射线自由电子激光用户装置共同构成,两个项目同步建设,有机衔接,包含两条光束线和5个实验站。为了向束线站各类设备提供稳定且精确的触发信号,基于WRTD分布式架构,使用WR交换机及光纤构成的网络,实现了长距离多节点之间的频率锁相及纳秒级时间同步,通过扇出模块最后输出延时和脉宽可调的触发信号。整个系统集成在EPICS框架中,可以通过PyDM界面对系统进行监测和控制。目前该系统稳定运行,抖动在100 ps量级,为束线站顺利通过工艺测试、实验站取得首批实验数据,提供了重要支持。

Using single wavelength light to improve the synchronization accuracy of the White Rabbit system

We demonstrate a new synchronization method for the White Rabbit system. Signals are transmitted in a single mode fiber in both directions with the same light wavelength. Without the complex calibration process of the fiber asymmetry parameter, the new method reduces the effect of chromatic dispersion and improves the synchronization accuracy. The experiment achieves timing synchronization accuracy below 200 ps over 50 km fiber constructed by different companies＇ fiber spools. The proposed method would make White Rabbit technology immune to the chromatic dispersion of fiber links and can be applied to long distance synchronization.

The novel transmission scheme with CAT Ethernet cable and SFP for White Rabbit

Background White Rabbit(WR)is a deterministic Ethernet-based network for general-purpose data transfer and subnanosecond time synchronization in large distributed systems.WR has been used in Large Hadron Collider and Large High-Altitude Air Shower Observatory for physics experiment.Purpose WR mainly uses the optical fiber for data transmission between WR devices.Commercial off-the-shelf Direct Attach Cable is not suitable for WR network at 100m level distance.Considering the lower cost of Category(CAT)Ethernet cable compared to optical fiber and the demand of remote power supply in distributed system at 100m level length,we developed a novel transmission scheme with CAT Ethernet cable for WR.Methods The novel transmission scheme uses the CAT Ethernet cable and small form-factor pluggable connector which is compatible with the optical links.This scheme only uses two pairs of twisted lines in the CAT Ethernet cable for data uplink and downlink.The other two pairs of twisted lines are used for remote power supply.Results and conclusion The novel transmission scheme could use the CAT Ethernet cable to complete remote power supply and time synchronization with expected time offset of less than 100 ps and standard deviation of less than 20 ps in the WR distributed system.The distance of distributed nodes could be 80m with one CAT 7 Ethernet cable or 150m with relay transceiver connecting two CAT 7 Ethernet cables.In the short-distance scenarios,the novel transmission scheme has lower cost than the optical fiber and additional power supply function.

Therapeutic efficiency of tissue-engineered human corneal endothelium transplants on rabbit primary corneal endotheliopathy

To evaluate the therapeutic efficiency of tissue-engineered human corneal endothelia (TE-HCEs) on rabbit primary corneal endotheliopathy (PCEP),TE-HCEs reconstructed with monoclonal human corneal endothelial cells (mcHCECs) and modified denuded amniotic membranes (mdAMs) were transplanted into PCEP models of New Zealand white rabbits using penetrating keratoplasty.The TE-HCEs were examined using diverse techniques including slit-lamp biomicroscopy observation and pachymeter and tonometer measurements in vivo,and fluorescent microscopy,alizarin red staining,paraffin sectioning,scanning and transmission electron microscopy observations in vitro.The corneas of transplanted eyes maintained transparency for as long as 200 d without obvious edema or immune rejection.The corneal thickness of transplanted eyes decreased gradually after transplanting,reaching almost the thickness of normal eyes after 156 d,while the TE-HCE non-transplanted eyes were turbid and showed obvious corneal edema.The polygonal corneal endothelial cells in the transplanted area originated from the TE-HCE transplant.An intact monolayer corneal endothelium had been reconstructed with the morphology,cell density and structure similar to those of normal rabbit corneal endothelium.In conclusion,the transplanted TE-HCE can reconstruct the integrality of corneal endothelium and restore corneal transparency and thickness in PCEP rabbits.The TE-HCE functions normally as an endothelial barrier and pump and promises to be an equivalent of HCE for clinical therapy of human PCEP.

Prototype of readout electronics for the LHAASO KM2A electromagnetic particle detectors

The KM2A （one kilometer square extensive air shower array） is the largest detector array in the LHAASO （Large High Altitude Air Shower Observatory） project. The KM2A consists of 5242 EDs （Electromagnetic particle Detectors） and 1221 MDs （Muon Detectors）. The EDs are distributed and exposed in the wild. Two channels, anode and dynode, are employed for the PMT （photomultiplier tube） signal readout. The readout electronics designed in this paper aims at accurate charge and arrival time measurement of the PMT signals, which cover a large amplitude range from 20 P.E. （photoelectrons） to 2x105 P.E. By using a ＂trigger-less＂ architecture, we digitize signals close to the PMTs. All digitized data is transmitted to DAQ （Data Acquisition） via a simplified White Rabbit protocol. Compared with traditional high energy experiments, high precision of time measurement over such a large area and suppression of temperature effects in the wild become the key techniques. Experiments show that the design has fulfilled the requirements in this project.

Anti-glaucoma potential of Heliotropium indicum Linn in experimentally-induced glaucoma

Background:Heliotropium indicum is used as a traditional remedy for hypertension in Ghana.The aim of the study was to evaluate the anti-glaucoma potential of an aqueous whole plant extract of H.indicum to manage experimentally-induced glaucoma.Methods:The percentage change in intraocular pressure(IOP),after inducing acute glaucoma(15 mLkg^(−1) of 5%dextrose,i.v.),in New Zealand White rabbits pretreated with Heliotropium indicum aqueous extract(HIE)(30–300 mgkg^(−1)),acetazolamide(5 mgkg^(−1)),and normal saline(10 mLkg^(−1))per os were measured.IOPs were also monitored in chronic glaucoma in rabbits(induced by 1%prednisolone acetate drops,12 hourly for 21 days)after treatments with the same doses of HIE,acetazolamide,and normal saline for 2 weeks.The anti-oxidant property of the extract was assessed by assaying for glutathione levels in the aqueous humour.Glutamate concentration in the vitreous humour was also determined using ELISA technique.Histopathological assessment of the ciliary bodies was made.Results:The extract significantly reduced intraocular pressure(p≤0.05–0.001)in acute and chronic glaucoma,preserved glutathione levels and glutamate concentration(p≤0.01–0.001).Histological assessment of the ciliary body showed a decrease in inflammatory infiltration in the extract and acetazolamide-treated group compared with the normal saline-treated group.Conclusion:The aqueous whole plant extract of Heliotropium indicum has ocular hypotensive,anti-oxidant and possible neuro-protective effects,which therefore underscore its plausible utility as an anti-glaucoma drug with further investigation.

LHAASO KM2A distributed long-distance data transmission

Background The large high-altitude air shower observatory(LHAASO)is being built near Daocheng(4410 m a.s.l.)in the Sichuan province of China.Its main instrument is the one-kilometer square extensive air shower array(KM2A)which will comprise nearly 7000 detectors.The system adopts a distributed architecture where each detector has local front-end electronics for signal digitization and transmission.White Rabbit(WR)is the communication protocol used within KM2A to reach the required 1-ns synchronization accuracy between detectors.Purpose To provide data transport and synchronization over the same network.Methods We have developed a firmware implementation of the TCP/IP protocol in Verilog hardware description language that can be coupled with a WR intellectual property core.Results LHAASO KM2A distributed data and clock synchronization network meets the high requirement of the array for reliable data transmission and clock synchronization.Conclusion The data transmission method based on the TCP/IP protocol suite and WR can be run in Xilinx Spartan6 FPGA with low resource needs,which greatly expand its application field.