High power,widely tunable femtosecond MgO:PPLN optical parametric oscillator

We demonstrate a high power,widely tunable femtosecond MgO-doped periodically poled lithium niobate(MgO:PPLN)optical parametric oscillator(OPO)at 151 MHz,pumped by a Kerr-lens mode-locked Yb:KGW laser.With a maximum pump power of 7 W,the OPO is capable of delivering as high as 2.2 W of the signal centered around 1500 nm with tunable signal spectrum ranges of 1377 nm-1730 nm at an extraction efficiency of 31.4%,which exhibits a long-term passive power stability better than 0.71%rms over 4 h.The maximum idler bandwidths of 185 nm at 3613 nm are obtained across the idler tuning ranges of 2539 nm-4191 nm.By compensating intracavity dispersion,the signal has the shortest pulse duration of 170 fs at 1428 nm.

Does conflict matter in the success of mass collaboration? Investigating antecedents and consequence of conflict in Wikipedia

Purpose: Web2.0 has facilitated the emergence of mass collaboration. Being a new model of virtual collaboration, mass collaboration has distinct characteristics such as self-organized voluntary participation and many-to-many communications mechanism. Behind the sparking achievements, mass collaboration systems are suffering from high coordination cost, reflecting intense conflict among the participants. This study explains how conflict interacts with its antecedents(participation and task complexity) and decedent(group performance) related to the mass collaboration process.Design/methodology/approach: Theoretical model is built upon literatures. Twenty-six measurable items, including social network indices used to reflect conflicts(e.g., density and degree), are extracted from Wikipedia database. The structural equation modeling is used to validate the proposed model.Findings: Participation increases task complexity, conflict and performance; task complexity and conflict increase group performance, but task complexity decreases conflict.Research limitations: This study is limited to one mass collaboration platform, other contexts can cause variance in the result. More characteristics of conflict network(e.g., self-loop)should be taken into consideration in future studies.Practical implications: Conflict management is critical to mass collaboration, and functions that increase the awareness of conflict may motivate users to participant, resulting better group performance.Originality/value: Few studies have investigated the consequences of conflict in mass collaboration context. Meanwhile, limited number of social network studies build network based on negative link. Moreover, most of extant studies on Wiki are descriptive researches without theoretical model. This study builds a theoretical model and incorporates social network approach to explore the influence of conflict.

Virtual simulation experiment of the design and manufacture of a beer bottle-defect detection system

Background Machine learning-based beer bottle-defect detection is a complex technology that runs automatically;however,it consumes considerable memory,is expensive,and poses a certain danger when training novice operators.Moreover,some topics are difficult to learn from experimental lectures,such as digital image processing and computer vision.However,virtual simulation experiments have been widely used to good effect within education.A virtual simulation of the design and manufacture of a beer bottle-defect detection system will not only help the students to increase their image-processing knowledge,but also improve their ability to solve complex engineering problems and design complex systems.Methods The hardware models for the experiment(camera,light source,conveyor belt,power supply,manipulator,and computer)were built using the 3DS MAX modeling and animation software.The Unreal Engine 4(UE4)game engine was utilized to build a virtual design room,design the interactive operations,and simulate the system operation.Results The results showed that the virtual-simulation system received much better experimental feedback,which facilitated the design and manufacture of a beer bottle-defect detection system.The specialized functions of the functional modules in the detection system,including a basic experimental operation menu,power switch,image shooting,image processing,and manipulator grasping,allowed students(or virtual designers)to easily build a detection system by retrieving basic models from the model library,and creating the beer-bottle transportation,image shooting,image processing,defect detection,and defective-product removal.The virtual simulation experiment was completed with image processing as the main body.Conclusions By mainly focusing on bottle mouth defect detection,the detection system dedicates more attention to the user and the task.With more detailed tasks available,the virtual system will eventually yield much better results as a training tool for image processing education.In addition,a novel visual perception-thinking pedagogical framework enables better comprehension than the traditional lecture-tutorial style.

蛹虫草线粒体DNA与细胞核DNA进化关系的比较

【目的】分析蛹虫草是否存在核内线粒体DNA片段,比较蛹虫草线粒体DNA与细胞核DNA的碱基变异程度及所反映的菌株间的系统发育关系。【方法】通过本地BLAST或LAST对蛹虫草线粒体基因组和核基因组进行序列相似性搜索;从10个已知线粒体基因组的蛹虫草菌株中分别扩增7个细胞核蛋白编码基因片段,并与其在14个线粒体蛋白编码基因上的碱基变异情况进行比较。【结果】蛹虫草核基因组中存在5处较短的核内线粒体DNA片段,总长只有278bp。蛹虫草核DNA的变异频率整体上高于线粒体DNA。核DNA和线粒体DNA所反映的蛹虫草菌株间的系统发育关系存在显著差异。【结论】蛹虫草线粒体DNA与核DNA间不存在长片段的基因交流,二者变异频率不同,所反映的蛹虫草菌株间的系统发育关系也有差异。本研究增加了对蛹虫草线粒体与细胞核DNA进化关系的认识。

扫描电化学显微镜在生物医学领域的应用研究进展

研究病变细胞和组织的异常表现可为理解重大疾病发生发展的病理机理和新型药物筛选提供重要参考.扫描电化学显微镜(Scanning electrochemical microscopy,SECM)是一种基于电化学原理的扫描探针显微镜,通过记录探针在样品表面扫描时的电流或电位等信息,对活细胞的形态和多种化学信息进行原位、实时、精准表征.近10年来,SECM在重大疾病相关的细胞、细胞球和微组织层次的应用研究得到快速发展.本文从与疾病相关的SECM研究角度入手,分别从单细胞、细胞球和微组织层次小结SECM近10年来在生物医学领域的应用研究进展.首先介绍SECM的仪器组成、探针种类和工作模式,其次分别介绍SECM在神经细胞、心肌细胞和肿瘤细胞的应用进展,之后介绍SECM近期在细胞球和微组织的最新应用,最后提出并展望SECM技术在生物医学领域进一步应用所面临的挑战和发展方向.

Electron-ion collider in China

Lepton scattering is an established ideal tool for studying inner structure of small particles such as nucleons as well as nuclei.As a future high energy nuclear physics project,an Electron-ion collider in China(EicC)has been proposed.It will be constructed based on an upgraded heavy-ion accelerator,High Intensity heavy-ion Accelerator Facility(HIAF)which is currently under construction,together with a new electron ring.The proposed collider will provide highly polarized electrons(with a po-larization of 80%)and protons(with a polarization of 70%)with variable center of mass energies from 15 to 20 GeV and the luminosity of(2–3)×1033 cm^(−2)·s^(−1).Polarized deuterons and Helium-3,as well as unpolarized ion beams from Carbon to Uranium,will be also available at the EicC.The main foci of the EicC will be precision measurements of the structure of the nucleon in the sea quark region,including 3D tomography of nucleon;the partonic structure of nuclei and the parton interaction with the nuclear environment;the exotic states,especially those with heavy flavor quark contents.In addition,issues fundamental to understanding the origin of mass could be addressed by measurements of heavy quarkonia near-threshold production at the EicC.In order to achieve the above-mentioned physics goals,a hermetical detector system will be constructed with cutting-edge technologies.This document is the result of collective contributions and valuable inputs from experts across the globe.The EicC physics program complements the ongoing scientific programs at the Jefferson Laboratory and the future EIC project in the United States.The success of this project will also advance both nuclear and particle physics as well as accelerator and detector technology in China.

新型带虚点的径向基函数微分求积法及其在薄板弯曲中的应用

论文提出了新型带虚点的径向基函数微分求积法,并将其应用于模拟薄板弯曲问题.带虚点的径向基函数微分求积法是一种基于传统径向基函数微分求积法的新型无网格方法,传统方法只将中心点放在计算域内,而该方法扩展了中心点的区域,使其既位于计算域内又位于计算域外,在不增加计算量和存储量的基础上,显著提高计算精度.论文首次尝试将此方法应用于求解薄板弯曲问题,并与解析解和传统方法进行对比,验证了此方法的优越性.

Core fungal species strengthen microbial cooperation in a food-waste composting process

In ecosystem engineering research,the contribution of microbial cooperation to ecosystem function has been emphasized.Fungi are one of the predominant decomposers in composting,but thus far,less attention has been given to fungal than to bacterial cooperation.Therefore,network and cohesion analyses were combined to reveal the correlation between fungal cooperation and organic matter(OM)degradation in ten composting piles.Positive cohesion,reflecting the cooperation degree,was positively linked to the degradation rate of OM.From the community perspective,core species(i.e.,Candida tropicalis,Issatchenkia orientails,Kazachstania exigua,and Dipodascus australiensis)with high occurrence frequency and abundance were the key in regulating positive cohesion.These species were highly relevant to functional genera associated with OM degradation in both fungal and bacterial domains.Therefore,focusing on these core fungal species might be an appropriate strategy for targeted regulation of functional microbes and promotion of degradation rates.

The construction of answer quality evaluation index for social search: An empirical study on social Q&A system

SQA(Social Question and Answering)is one of the typical applications of social search in Web2.0 era.SQA sites take advantage of the wisdom of crowds and produce a mass of questions and answers every day.In a new generation of Internet UGC(User-Generated Content)environment,SQA has a profound effect on the way of information seeking by users.To better understand