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  • Biharmonic Riemannian submersions from the product space $M^2 times r$

    分类: 数学 >> 几何与拓扑 提交时间: 2024-02-28

    摘要: In this paper,  we study  biharmonic Riemannian submersions $ pi:M^2 times r to (N^2,h)$ from a product manifold onto a surface and obtain some local characterizations of such biharmonic maps. Our results show that when the target surface is flat, then a proper biharmonic Riemannian submersion $ pi:M^2 times r to (N^2,h)$ is locally a projection of a special twisted product, and when the target surface is non-flat, $ pi$ is locally a  special map between two warped product spaces with a warping function that solves a single ODE. As a by-product, we also prove that there is a unique proper biharmonic Riemannian submersion $H^2 times r to r^2$ given by the projection of a warped product.

  • 上海激光电子伽马源的建设与试运行

    分类: 物理学 >> 核物理学 提交时间: 2024-02-28

    摘要: 介绍了上海光源线站工程之一的上海激光电子伽马源 (Shanghai Laser Electron Gamma Source, SLEGS)光束线站的建设与试运行情况,在SLEGS伽马源装置上可以开展核物理、核天体物理等基础研究、开展伽马辐照,伽马成像及伽马活化等应用研究。SLEGS光束线站在2021年12月通过工艺验收,2022年10月进入到试运行阶段,2023年9月对用户开放运行。SLEGS是国际上首台采用变换碰撞角度连续改变伽马束能量,具有最好的能量扫描精度、流强密度以及高效的能量调节能力。试运行阶段SLEGS光束线站重点解决了伽马束能谱和流强的在线监测问题,主要完成了平坦效率谱仪(FED)测量光中子截面的实验方法学研究,以及开展了伽马成像、伽马活化,正电子产生等应用平台的拓展和研究。随着逆康普顿散射技术的发展和应用需求的增加,未来短脉冲、高极化、高通量以及小型化的激光康普顿散射光源将会迎来更好的发展机遇,将在核物理、天体物理、粒子物理,极化物理,以及航空航天,医学检测,能源开发等伽马源应用研究领域发挥重要的作用。

  • Construction of Gamma Activation Experimental Platform for Shanghai Laser Electron Gamma Source

    分类: 物理学 >> 核物理学 提交时间: 2024-02-28

    摘要: 上海激光电子伽马源(Shanghai Laser Electron Gamma Source,SLEGS)是通过激光与电子逆康普顿散射产生准单能、能量连续可调的兆电子伏伽马束,是目前国际上唯一一台可连续变换碰撞角度的激光康普顿散射(Laser Compton Scattering,LCS)伽马源装置。伽马活化是研究材料特性的有效手段之一,本文介
    绍了上海激光电子伽马源的伽马活化平台情况、包括在线活化过程,离线低本底测量,高纯锗(High Purity Germanium,HPGe)探测器的能量效率刻度等。目前的简易低本底屏蔽使得测量系统本底计数率降低到约 5.2cps/(60 keV-3 MeV 能区)。SLEGS 伽马源的活化平台为开展伽马活化测量研究提供了有利条件,未来在核物理、核天体物理、医学应用、材料科学和环境科学等领域的研究将会发挥重要的作用。

  • 基于单极感应问题的力线与场概念的实验研究

    分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2024-02-27

    摘要: 本文通过线圈与磁体相对运动实验,以及对诸多电磁相互作用案例分析研究表明在单极感应问题上,韦伯当年的观点是正确的。另外,本文的实验分析同时表明与场的概念相比较,力线的概念对解释电磁相互作用同样起重要作用。

  • 老年遗忘型轻度认知障碍执行功能的神经机制及数字干预研究

    分类: 心理学 >> 认知心理学 提交时间: 2024-02-27

    摘要: 阿尔茨海默病具有极高的发病率和致死率。遗忘型轻度认知障碍(Amnestic Mild Cognitive Impairment, aMCI)作为临床前驱期,探究其形成和发展机制有助于预防阿尔茨海默病的发生。现有研究显示,多个执行域缺陷与aMCI记忆衰退密切相关,但尚未回答何种执行域是关键致病因子、关键干预治疗靶标等科学问题。为突破以往研究将执行功能视作整体抑或割裂元素的局限性,本研究拟从执行功能结构全貌着眼,在提出aMCI执行功能与记忆损害关系假说的基础上,利用脑电技术系统考察aMCI抑制、刷新和转换三种执行功能子成分的时域、时频和动态脑网络特征;并结合三维卷积神经网络筛选、识别执行功能缺陷的特异性神经靶标,探索将抑制域相关神经标记物加入aMCI早期识别的可能性;最后,通过纵向因果设计分析不同靶向数字干预对aMCI患者的训练效果及神经基础,以揭示抑制域相关额顶控制网络在干预中的重要作用。本研究有望从计算认知神经视角阐明抑制是aMCI执行功能缺损和干预的认知新靶点,进而为aMCI早期识别和制定精准化诊疗方案提供循证依据。

  • 一种高计数率的能损探测器方案研究

    分类: 物理学 >> 核物理学 分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2024-02-27

    摘要: 正在建设中的强流重离子加速器装置 HIAF 配备了一条先进的放射性束流线 HFRS,建成后将为中国 高能放射性核束物理研究提供新的机遇。HFRS 的特点是流强极高 (初级束流强度 1 × 1011 ppp),这对用于粒 子鉴别的能损探测器提出了非常高的计数率要求。传统的能损探测器对信号处理一般依次采用电荷灵敏前放、 主放、ADC 的技术路线。该方案存在电子学响应速度较慢、灵活性较差、难以处理高计数率下信号堆积严重 等问题。我们对此提出一种新的适用于高计数率的能损探测器方案:以耐辐照的多次取样电离室为能损探测 器,优化结构和读出方式提高探测器响应速度,使用快电荷灵敏前放对能损探测器信号初步放大后、直接用 波形数字化仪采集波形再进行后续数字算法处理。并利用放射源和束流对该方案进行了验证测试。利用 3 组 分 𝛼 源测试时,对采集的波形使用数字成形算法处理,能量分辨率(FWHM)可达 1.31%。在 RIBLL2 提供 300 MeV/u 的 56Fe 束流测试中,采用时间常数 𝜏f = 2 𝜇𝑠 的快电荷灵敏前放在计数率接近 1 MHz 时仍未发生明显堆积。

  • Ⅲ期胃癌D2根治术后辅助放化疗患者长期预后的影响因素:基于10年随访数据

    分类: 医学、药学 >> 临床医学 提交时间: 2024-02-27 合作期刊: 《中国全科医学》

    摘要: 背景  局部进展期胃癌主要包括Ⅲ期胃癌,以综合治疗为主,患者术后复发是影响患者预后的关键因素。目的  探究Ⅲ期胃癌D2根治术后辅助放化疗患者长期预后的影响因素。方法  选取2009年1月—2014年12月在复旦大学附属中山医院放疗科行D2根治术后辅助放化疗的胃癌患者为研究对象,病理结果根据国际癌症联合会(UICC)和美国肿瘤联合会(AJCC)第八版胃癌TNM分期系统进行分期,明确诊断Ⅲ期胃癌。术后所有患者在第1年每3个月随访1次,之后2年内每6个月随访1次,而后每年随访1次。随访截止日期为2021-12-15。采用Log-rank检验比较生存率的差异,采用Cox比例风险回归分析探究患者总生存时间(OS)和无病生存时间(DFS)的影响因素,列线图预测临床病理特征对预后的影响,Kaplan-Meier法比较不同pTNM分期、年龄、转移淋巴结率(LNR)、胃切除方式患者生存差异。结果  共纳入行术后辅助放疗的Ⅲ期胃癌患者135例,中位随访时间10.48年。5年内复发70例,死亡62例,5年无病生存率、总生存率分别为48.1%(65/135)、54.1%(73/135);10年内复发74例,死亡74例,10年无病生存率、总生存率均为45.2%。Log-rank检验结果显示,不同pTNM分期、pT分期、LNR、癌结节、肿瘤位置、胃切除方式患者5年生存率比较,差异有统计学意义(P<0.05)。不同pTNM分期、pT分期、LNR、神经浸润、胃切除方式患者10年生存率比较,差异有统计学意义(P<0.05)。多因素Cox比例风险回归分析结果显示,pTNM分期(ⅢA期,OS:HR=0.40,95%CI=0.19~0.83;DFS:HR=0.40,95%CI=0.19~0.92)、LNR(>50%,OS:HR=1.74,95%CI=1.03~2.94;DFS:HR=1.87,95%CI=1.73~1.02)、胃切除术方式(全胃切除术,OS:HR=2.07,95%CI=1.22~3.50;DFS:HR=2.02,95%CI=1.20~3.41)是Ⅲ期胃癌D2根治术后辅助放化疗患者OS和DFS的独立影响因素(P<0.05),年龄(≤40岁,HR=2.19,95%CI=1.06~4.53)是Ⅲ期胃癌D2根治术后辅助放化疗患者OS的独立影响因素(P<0.05)。另外,列线图表明年龄、pTNM分期、LNR、胃切除术方式对Ⅲ期胃癌D2根治术后辅助放化疗患者预后有预测作用。胃癌术后患者复发情况:10例(7.4%)局部复发(放射野内吻合口和淋巴结的复发),35例(25.9%)患者出现腹、盆腔播散种植,37例(27.4%)患者出现了远处转移(包括肺、肝、骨、脑等脏器);部分患者发现了2种类型以上的复发。不同pTNM分期、年龄、LNR、胃切除方式的Ⅲ期胃癌患者术后生存曲线比较,差异有统计学意义(P<0.05)。结论  大部分Ⅲ期胃癌D2根治术后辅助放化疗患者复发或死亡主要在5年内。pTNM分期、LNR和胃切除方式是这类患者预后的主要影响因素。

  • Atomistic study on the microscopic mechanism of grain boundary embrittlement induced by small dense helium bubbles in iron

    分类: 物理学 >> 核物理学 分类: 核科学技术 >> 核聚变工程技术 提交时间: 2024-02-27

    摘要: The helium bubbles induced by 14 MeV neutron irradiation can cause intergranular fractures in reduced activation ferritic martensitic (RAFM) steel, which is a candidate structural material for fusion reactors. In order to elucidate the susceptibility of different grain boundaries (GBs) to helium-induced embrittlement, the tensile fracture processes of 10 types of GBs with and without helium bubbles in body-centered cubic (bcc) iron at the relevant service temperature of 600 K were investigated via molecular dynamics methods. The results indicate that in the absence of helium bubbles, the GBs studied here can be classified into two distinct categories: brittle GBs and ductile GBs. The atomic scale analysis shows that the plastic deformation of ductile GB at high temperatures originates from complex plastic deformation mechanisms, including the Bain/Burgers path phase transition and deformation twinning, in which the Bain path phase transition is the most dominant plastic deformation mechanism. However, the presence of helium bubbles severely inhibits the plastic deformation channels of the GBs, resulting in a significant decrease in elongation at fractures. For bubble-decorated GBs, the ultimate tensile strength increases with the increase of the misorientation angle. Interestingly, the coherent twin boundary Ʃ3{112} was found to maintain relatively high fracture strength and maximum failure strain under the influence of helium bubbles.

  • Study on the Pharmacological Mechanism of the Xihuang Pill and its Treatment of Breast Cancer Based on Nontargeted Metabonomics

    分类: 医学、药学 >> 中医学与中药学 提交时间: 2024-02-26

    摘要: Objective. To study the main differential metabolites of Xihuang Pill (XHP) in rat serum and the mechanism of related pathways of metabolites on breast cancer. Method. Qualitative and quantitative analysis of metabolites in XHP drug serum group and blank serum group by liquid chromatography-mass spectrometry (LC-MS) technology. And using sample correlation heat map and multivariate statistical analysis methods to compare the metabolic differences between the two groups. The metabolites were analyzed by cluster analysis, Variable Importance in Projection (VIP) analysis, Kyoto Encyclopedia of genes and Genomes (KEGG) compound classification and KEGG functional and enrichment topology analysis. Result. LC-MS technology identified a total of 765 metabolites in the XHP drug serum group; a total of 697 metabolites in the blank serum group. VIP analysis screened the top 30 serum differential metabolites that were significantly different between the two groups, such as Abscisic acid, Quillaic acid, 2,2-Bis(4-hydroxyphenyl)-1-propanol, Corey PG-Lactone Diol, (S)-Naproxen and so on. KEGG compound classification showed that most of the metabolites in XHP were classified as phospholipids and amino acids, steroid hormones and carboxylic acids . KEGG functional pathways main involved are Lipid metabolism, Amino acid metabolism, Cancer: overview. KEGG enrichment and topology analysis, mainly involved in steroid hormone biosynthesis pathway and beta-alanine metabolism pathway. Conclusion. The main differential metabolite of XHP in rat serum may be Abscisic acid. XHP may exert its pharmacological effect on breast cancer by regulating steroid hormone biosynthesis pathway to regulate estrogen and progesterone levels and beta-alanine metabolism pathway to induce cancer cell apoptosis.

  • Recent Progress on Halo Nuclei in Relativistic Density Functional Theory

    分类: 物理学 >> 核物理学 提交时间: 2024-02-26

    摘要: Since the discovery of the halo nucleus 11Li in 1985, halo phenomena in exotic nuclei have always been an important frontier in nuclear physics research. The relativistic density functional theory has achieved great success in the study of halo nuclei, e.g., the self-consistent description of halo nucleus 11Li and the microscopic prediction of deformed halo nuclei. This paper introduces some recent progresses, including the investigation of halo nucleus 37Mg and the prediction of the N = 28 shell collapse and a deformed halo in the new isotope 39Na based on the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc), as well as the exploration of triaxially deformed halo nuclei by the newly developed triaxial relativistic Hartree-Bogoliubov theory in continuum (TRHBc).

  • 社会等级的进阶路径及其演化:来自比较研究的启示

    分类: 心理学 >> 心理学其他学科 提交时间: 2024-02-26

    摘要: 社会等级是一个动态演化的多维系统,其获取可分为三大路径。支配路径强调借助攻击与威胁获取资源,在激烈的性选择压力下演化而来。能力路径突出知识/技能对获取地位的作用,源于技术性觅食所产生的文化学习需要。与前两种路径不同,以心理利他为特征的美德路径为人类社会所独有。它是文化演化的产物,其存在是为了解决大规模集体行动的问题。三种路径在存在范围、行为模式和结果、演化动因以及情感介质等方面存在差异。未来研究可进一步澄清不同动物群体性选择模式与支配等级的关系,结合多个学科考察人类能力路径演化的特殊环境,并探究美德路径的生物性基础。

  • 贫困经历下稀缺心态对儿童执行功能的影响及其机制

    分类: 心理学 >> 发展心理学 提交时间: 2024-02-26

    摘要: 在乡村振兴的时代背景下如何全面有效地衡量脱贫后的生活环境、准确掌握贫困经历及其变化对儿童发展的负面影响和内在机制成为当下的重要科学议题。考虑到儿童成长过程中贫困条件的交叠累积性反应,有更多潜在的贫困从属条件需要重视,且儿童在经历贫困后如何加工理解相关信息对其发展有重要影响。本研究聚焦我国有贫困经历的学龄儿童,以稀缺理论为切入点,旨在构建适用于当前背景的多维贫困模型,并从注意模式和神经活动解释稀缺心态影响贫困儿童执行功能的作用机制,为有贫困经历儿童的认知发展提供新的干预视角,更好助力我国乡村儿童的健康发展。

  • Studies of an Event Building algorithm of the readout system for the twin TPCs in HFR

    分类: 物理学 >> 核物理学 提交时间: 2024-02-26

    摘要: The High Energy Fragment Separator (HFRS), which is currently under construction, is a leading international radioactive beam device. Multiple sets of position-sensitive Twin Time Projection Chamber (TPC)
    detectors are distributed on HFRS for particle identification and beam monitoring. The twin TPCs’ readout
    electronics system operates in a trigger-less mode due to its high counting rate, leading to a challenge of handling large amounts of data. To address this problem, we introduced an event-building algorithm. This algorithm
    employs a hierarchical processing strategy to compress data during transmission and aggregation. In addition,
    it reconstructs twin TPCs’ events online and stores only the reconstructed particle information, which significantly reduces the burden on data transmission and storage resources. Simulation studies demonstrated that the
    algorithm accurately matches twin TPCs’ events and reduces more than 98% of the data volume at a counting
    rate of 500 kHz/channel.
     

  • 基于大模型知识蒸馏的专利技术功效词自动抽取方法研究:以车联网V2X领域为例

    分类: 图书馆学、情报学 >> 情报学 提交时间: 2024-02-26

    摘要: [目的]本文旨在提高专利技术功效自动化提取的准确度。[方法]使用ChatGPT作为教师模型(Teacher-model),ChatGLM3作为学生模型(Student-model),通过知识蒸馏,将ChatGPT生成的训练数据微调ChatGLM3,得到多个技术词抽取模型和功效词抽取模型。采用多个技术词抽取模型分别从专利的摘要、第一权利要求和技术功效语段中抽取技术词,并采用功效词抽取模型从技术功效语段中抽取功效词。[结果]微调后的多个技术词抽取模型和功效词抽取模型相较于ChatGPT,在抽取技术词和功效词时呈现准确率高、召回率低的特点,第一权利要求的ChatGLM3微调模型的准确率和F1值最高,分别为0.734和0.724。功效词抽取模型抽取的功效词的准确率为0.649,大于商业工具标注功效词的准确率0.53。[局限]本研究的技术领域和专利语言单一,验证数据量偏小,数据清洗规则还有待于继续优化。[结论]本研究方案通过知识蒸馏操作,提升了大语言模型自动化抽取技术功效的准确性。同时,本研究能够支持从专利文本中挖掘前沿创新技术、热点技术,支撑更高质量的智能化专利分析。

  • 国产电能表融入国际高端市场的思考

    分类: 工程与技术科学 >> 计量学 分类: 工程与技术科学 >> 仪器仪表技术 提交时间: 2024-02-26

    摘要: 高端电表出口是未来几年电表产业发展的期望。本文将按近几年中国高端电能计量技术的创新成果;借鉴国际电表设计经验,深化国产高端电表产品开发;组建高端电表出口联盟的建议3项专题进行叙述,提出高端电表如何融入国际高端市场的思考与建议,供研究中国表计行业发展的参考。

  • 窄带载波自动抄表系统设计研究

    分类: 工程与技术科学 >> 计量学 分类: 工程与技术科学 >> 仪器仪表技术 提交时间: 2024-02-26

    摘要: 主要介绍了国网在2010-2014年间将完成的用电信息采集系统建设,特别关注了本地窄带载波通信方式的应用和问题。文章还提到了合作开展本地窄带载波自动抄表系统工程设计与管理方法的研究,并强调了这是一项复杂且需要大量投资的民心工程。前期工作研究借鉴了低压电力线窄带载波通信系统性能评估体系的经验,并提出了一系列创新性的建设策略。同时,文章也指出了国网用电信息采集系统企业标准在制定过程中存在的一些失策,如未将居民用户的本地窄带载波自动抄表系统技术瓶颈作为研究重点,以及标准中的一些问题和不足。这段文字主要围绕“国网用电信息采集系统建设”和“本地窄带载波通信方式的应用与问题”展开,同时涉及了前期工作研究、创新性建设策略和标准制定失策等方面的内容。

  • HIRFL-CSR 外靶实验终端 Veto 探测器的刻度

    分类: 核科学技术 >> 核探测技术与核电子学 分类: 物理学 >> 核物理学 提交时间: 2024-02-26

    摘要: 使用宇宙射线对兰州重离子加速器冷却储存环 (HIRFL-CSR) 外靶实验终端 (ETF) 的 Veto 探测器开展了
    刻度工作,工作主要分为位置刻度与时间刻度两部分。位置刻度可给出粒子在探测器上的击中位置,时间刻
    度则能为粒子在探测器上击中时刻的探测建立统一标准。这些信息是剔除入射到中子墙探测器的带电粒子事
    件的依据,可为中子墙探测器物理目标的实现提供重要支持。在刻度过程中,得到了 Veto 探测器的位置分辨
    半高全宽 (FWHM) 为 2.53 cm,所有单元条时间归一后的时间分辨 FWHM 为 1.09 ns。

  • Design and test for the CEPC muon subdetector based on extruded scintillator and SiPM

    分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2024-02-25

    摘要:
    A combination of scintillator, wavelength shifting (WLS) fiber, and silicon photomultiplier (SiPM) shows excellent performance in the `KL and μ detector (KLM)' of the Belle II experiment. We describe the R&D for a similar detection technology with a new scintillator and SiPM, which can be implemented for a muon detector for the proposed CEPC experiment and the upgrade of KLM in Belle II. The R&D contains the study of the performance of a new scintillator with a length of 150 cm, the NDL SiPM with a sensitive surface of 3 mm × 3 mm or the Hamamatsu MPPC with a sensitive surface of 1.3 mm × 1.3 mm, the construction of a detector strip, and the methods to achieve excellent light collection. The cosmic ray tests show good photon collections by NDL SiPM or MPPC, efficiencies well above 90% with a threshold of 8 p.e., and time resolutions of better than 1.7 ns for the hits at the far end of a scintillator strip. The performance shows a good option for an excellent muon detector for CEPC and the possible upgrade of Belle II KLM.

  • Reevaluating GPR30: A Paradigm Shift from Estrogen Receptor to Unique Hydrophilic Ligand Activation

    分类: 药物科学 >> 结构生物学 提交时间: 2024-02-24

    摘要: The orphan receptor GPR30, previously classified as a G protein-coupled estrogen receptor (GPER), has been a subject of debate regarding its ligand specificity. Through an integrative approach combining structure elucidation, biochemical binding, and cell signaling assays, we demonstrate that estrogen does not directly bind to or activate GPR30. Cryo-EM structures of GPR30 reveal an unexpected hydrophilic ligand-binding pocket, with striking differences from classical hydrophobic steroid-binding sites, inconsistent with estrogen binding. We further confirmed hydrophilic agonists like Lys05 as true activators of GPR30, providing structural insights into their binding mechanism and receptor activation. Our findings necessitate a paradigm shift in defining GPR30's role in estrogen signaling, indicating that its activation occurs through mechanisms independent of estrogen binding. This study opens new avenues for developing targeted GPR30 ligands and reinterpreting its role in estrogen-mediated processes.

  • Isotopic dependence of the yield ratios of light fragments from different projectiles and their unified neutron skin thicknesses

    分类: 物理学 >> 核物理学 提交时间: 2024-02-24

    摘要: The yield ratios of neutron-proton (R(n/p)) and 3H-3He (R(3H/3He)) with reduced rapidity from 0 to 0.5 were simulated for 50 MeV/u even-even 36-56Ca + 40Ca, even-even 48-78Ni + 58Ni and 100-139Sn (every third isotopes) + 112Sn at full reduced impact parameters using the isospin-dependent quantum molecular dynamics (IQMD) model. The neutron and proton density distributions and root-mean-square radii of the reaction systems were obtained using the Skyrme-Hartree-Fock model, which was used for the phase space initialization of the projectile and target in IQMD. We defined the unified neutron skin thickness as ΔRnp=2>n1/2-2>p1/2, which was negative for neutron-deficient nuclei. The unified ΔRnp values for nuclei with the same relative neutron excess from different isotopic chains were nearly equal, except for extreme neutron-rich isotopes, which is a type of scaling behavior. The yield ratios of the three isotopic chains-induced reactions, which dependent on the reduced impact parameter and the unified neutron skin thickness, were studied. The results show that both R(n/p) and R(3H/3He) decreased with a reduced impact parameter for extreme neutron-deficient isotopes; however, they increased with reduced impact parameters for extreme neutron-rich isotopes, and increased with the ΔRnp of the projectiles for all reduced impact parameters. In addition, a scaling phenomena was observed between ΔRnp and the yield ratios in peripheral collisions from different isotopic chain projectiles (except for extreme neutron-rich isotopes). Thus, R(n/p) and R(3H/3He) from peripheral collisions were suggested as experimental probes for extracting the neutron or proton skin thicknesses of non-extreme neutron-rich nuclei from different isotopic chains.