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Steepness as a probe in weak lensing cosmological studies

Lecturer: 
Zuhui Fan, Peking University
Lecturer description: 

 Zuhui Fan received her Ph.D. in 1995 from University of Washington in Seattle, U.S.A..  From 1996 to 2002, she was a visiting scientist and a postdoc fellow in University of Chicago and Taiwan University/ASIAA, Taiwan, respectively. From 2002 to 2018, she was a professor at Department of Astronomy, School of Physics, Peking University. In Nov. 2018, she moved to the South-Western Institute for Astronomy Research at Yunnan University. She is now a professor there. Her research interest is in cosmology, particularly in weak lensing cosmological studies in the recent years.

Place: 
Room 111, Physics Building
date: 
Wed, 2019-06-12 15:00 - 16:00

Weak lensing (WL) effects arise from the gravitational light deflection by large-scale structures, and thus are powerful tools to probe the nature of the dark universe. Their signals are dominantly from relatively small-scale nonlinear structures, and therefore possess significant non-Gaussianity. Statistical analyses of WL effects thus need to be multi approaches. In this presentation, motivated by the recent machine learning results, I will talk about the use of WL steepness as a cosmological probe by presenting our theoretical model and the comparisons with numerical simulations.

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Quantitative Studies of Bacteria Chemotaxis Behavior

Lecturer: 
Qi Ouyang, Peking University
Lecturer description: 

欧阳颀,中国科学院院士。北京大学博雅讲席教授。现任北京大学物理学院副院长,学术委员会主任;北京大学理论生物学中心副主任,北京大学前沿交叉学科研究院理论生物学中心学术委员会主任。

1982年于清华大学化学与化学工程系获学士学位;1989年于法国波尔多第一大学获博士学位。1989年到1995年在美国得克萨斯州立大学奥斯汀分校非线性动力学中心做博士后研究员及研究员。1995年到1996年在法国尼斯非线性中心做客座研究员。1996年到1998年在美国日本电气公司研究中心做研究科学家。1998年受聘于北京大学物理学院,任教授。同年被评为第一届长江特聘教授。

研究方向:非线性动力学、斑图动力学、生物物理、定量系统生物学、生物调控网络动力学,生物微流体技术,合成生物学与冷冻电镜结构生物学。

学术成就:欧阳颀实验室主要应用非线性动力学、复杂系统理论与统计物理的概念与研究方法探索生物控制网络的特性,包括网络拓扑学特性,网络动力学特性,网络功能特性,以及三种特性之间的相互制约关系。并试图将研究中所总结的规律应用到合成生物学领域,开展以理性设计为原则的合成生物学研究。近年来涉足冷冻电镜结构生物学研究并取的重要成果。

Place: 
Room 203, New Physics Building
date: 
Wed, 2019-06-19 15:00 - 16:00

Most biological organisms have the ability to sense their chemical environment and direct their motion toward attractants and away from repellents. This chemotactic behavior has been studied intensively in recent years. Among them, bacteria E. Coli. Chemotaxis is one of the best-studied systems in biology; it serves as an ideal model system in quantitative biology. In this talk, we will report our quantitative studies in recent years on E. Coli. chemotactic behavior under different spatiotemporal varying environments using both experimental and theoretical methods.

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First Light at the Epoch of Reionization

Lecturer: 
Lifan Wang, Texas A&M University
Lecturer description: 

My colleagues and I are endeavoring to build an astronomical observatory at Dome A, the highest point in Antarctica. We hope to set up a number of telescopes in the coming years to study the mysterious dark energy in the universe.My research interests include also spectropolarimetry observations of supernovae. The supernovae I study are so far away that even the largest telescopes in the world cannot resolve their shapes through direct imaging. Spectropolarimetry is a technique that enables geometric structures of supernovae to be studied.Most recently I am working on finding supernovae at redshifts above 4.

Place: 
Room 111, Physics Building
date: 
Wed, 2019-06-05 15:00 - 16:00

A major scientific goal of the James Web Space Telescope (JWST) is to probe the epoch of reionization of the Universe at z above 6, and up to 20 and beyond. At these redshifts, galaxies are just beginning to form and the observable objects are early black holes, supernovae, and cosmic infrared background. The JWST has the necessary sensitivity to observe these targets individually, but a wide field survey is needed to discover these black holes and supernovae and to cover the area large enough for cosmic infrared background to be reliably studied.

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原子尺度研究量子材料的电子结构:应力和杂质的调制作用

Lecturer: 
尹艺,浙江大学
Lecturer description: 

尹艺,浙江大学物理系教授,2002年本科毕业于中国科学技术大学物理系,2009年博士毕业于哈佛大学物理系,2009-2012年在UCSB从事博士后研究,2012年底加入浙江大学物理系。主要研究方向为低温扫描隧道显微镜以及超导量子计算和量子模拟。

Place: 
Room 111, Physics Building
date: 
Wed, 2019-05-29 15:30 - 16:30

低温扫描隧道显微镜(STM)是在原子尺度研究材料电子结构的重要工具,一方面我们可以测量直接得到相关材料在费米面附近的电子态密度能谱,另一方面STM原子分辨的功能可以帮助我们研究在微观原子尺度杂质和应力对电子结构的调制作用。这个报告中我将讨论1T-TaS2材料中的局域应力破坏莫特绝缘态从而演化到金属态的连续过程,FeSe材料中不同杂质的能谱和杂质种类分析,ZrSiSe和ZrSiS两种拓扑材料中单原子杂质得到的准粒子激发图样来分析拓扑能带的方法和结果。这几种不同量子材料的例子展示了STM在广泛的材料电子结构研究中的重要作用。

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非线性光学超构表面

Lecturer: 
李贵新,材料科学与工程系、量子科学与工程研究院,南方科技大学
Lecturer description: 

李贵新,副教授,材料科学与工程系、量子科学与工程研究院,南方科技大学。第12批“青年千人计划”入选者。于2009 年毕业于香港浸会大学物理系并取得博士学位,2016 年10 月回国加入南方科技大学,2009-2016年于香港浸会大学、英国伯明翰大学物理系、德国帕德博恩大学物理系从事研究工作,任博士后、研究助理教授等职位。研究领域为光学超构材料、超构表面、纳米光学、非线性光学等。在包括《自然-物理学》、《自然-材料学》、《自然综述-材料学》、《自然-纳米技术》、《自然-通讯》、《物理评论快报》等期刊发表研究论文50余篇,获美国专利授权5项。

Place: 
Room 111, Physics Building
date: 
Mon, 2019-05-27 15:45 - 16:45
光学超构表面是一种能够对电磁场在亚波长尺度上进行调控的超薄人工界面。其理念源于三维超构材料、形貌类似传统的二元光学结构器件。超构表面的重要性不仅在于概念上的新颖,更在于其在光学、材料、物理等领域的重要性。在此,我们将讨论光的自旋角动量(在光-超构界面相互作用过程中的演化及如何利用光的几何相位设计高效率的全息光学元件。例如,通过设计过高反射率超构表面,可实现连续相位梯度、广角、宽光谱及高效率的全息成像。此项技术在三维显示、防伪、激光光束整形等领域具有重要应用前景。 
在非线性光学领域,我们利用表面等离激元共振增强效应,设计出对圆偏振光响应的非线性超构表面,从理论和实验上揭示了非线性光学倍频、三倍频与超构单元的旋转对称性之间的选择定则。在此基础上,我们在超构表面上发现并实验验证了非线性Berry贝里几何相位。利用非线性光学Berry相位的原理,可以在亚波长尺度上通过简单旋转超构功能基元的方向,进而可实现非线性谐波的相位从0-2π的连续可调。
 
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免疫细胞与肿瘤细胞相互作用的单细胞动力学机制

Lecturer: 
史珏,香港浸会大学
Lecturer description: 

史珏,现任香港浸会大学物理系副教授。本科毕业于中山大学物理系,并在美国密歇根大学安娜堡分校获得生物物理学博士学位。随后在哈佛大学医学院系统生物学系从事抗癌药物、细胞动力学响应机制的博士后研究。专长于活体细胞荧光显微成像以及在单细胞水平上测量与分析网络及细胞动态机制,近期成果发表在Science Advances, Nature Communications, Cancer Research等国际一流期刊。

Place: 
Room 111, Physics Building
date: 
Wed, 2019-05-15 15:00 - 16:00

免疫细胞具有检测和杀灭人体内癌变细胞的功能,因而免疫疗法是现今癌症治疗研发的重要方向。虽然免疫细胞的激活以及其促进癌变细胞凋亡的分子机制在很大程度上已知,但对于这一过程的定量动力学特征及其调控,我们还知之甚少。传统测量免疫细胞与肿瘤细胞相互作用的实验都只能观测在整体平均水平上的细胞相互作用,因而无法研究这一重要过程的瞬态动力学特征以及这一过程的特异性。因此,我们研究小组建立了新颖的单细胞显微成像平台,在单细胞水平定量测定与分析在特定环境下免疫细胞与肿瘤细胞相互作用的动力学机制。本报告将以自然杀伤细胞(Natural Killer cell)与肿瘤细胞株的实时动态相互作用为例,介绍我们的单细胞成像实验结果,以及利用深度学习从海量样本中识别和跟踪每一个免疫细胞的运动和变化, 进而提取统计特征量,建立免疫细胞在与肿瘤细胞相互作用下的动力学统计模型的理论分析。我们的研究结果不但显著提升了对自然杀伤细胞杀灭肿瘤细胞机理的认识,特别是关于自然杀伤细胞的杀伤性是如何因应肿瘤细胞的不同而变化这一重要机制性问题, 并且找到了与动力学和多样性特征相关的关键细胞调控分子和调控通路。而我们所发展的实验及理论相结合的综合研究手段也将适用于研究其它细胞相互作用的定量动力学机制,例如分析巨噬细胞和T细胞的动态功能。

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类星体的外流

Lecturer: 
王挺贵,中国科学技术大学
Lecturer description: 

1985年本科毕业于杭州大学物理系,1992年中国科学技术大学天文系获博士学位。 1992成为中国科学技术大学讲师,1995年升为副教授,2000年至今为该校教授。曾先后在欧洲空间局紫外探险者天文台、德国马普地外物理所、日本理化学研究所学习与工作访问。主要研究兴趣在活动星系核、黑洞潮汐撕裂恒星事件等。

Place: 
Room 111, Physics Building
date: 
Wed, 2019-05-08 15:00 - 16:00

活动星系核反馈一直被认为在星系形成演化扮演重要角色,塑造出今天星系中心的超大质量黑洞与星系的紧密关系,类星体的高速外流是反馈过程主要选项之一。在观测上类星体的高速外流表现为蓝移的宽吸收线。尽管宽吸收线现象发现已经40多年,这些高速外流的性质、它们怎么产生以及它们能否影响甚至决定星系与黑洞自身的演化一直没有定论。近年来传统通过激发态吸收线诊断方法在较窄速度的外流性质取得了重要进展,但该方法只适合较窄的吸收线,对大部分宽吸收线并不适用。 我们另寻途径从吸收线光变的方面推断类星体外流的性质,发现类星体宽吸收线外流的功率可足以影响整个星系的演化。

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Ultimate precision Standard Model tests: the muon magnetic moment

Lecturer: 
Michel Davier, Université Paris-Sud 11
Lecturer description: 
Professor Michel Davier obtained his PhD from Université Paris-Sud 11, Orsay, France in 1969. He designed and built experiments at a numerous laboratories including LAL(Orsay, France), SLAC(Stanford, US), DESY(Hamburg, Germany), CERN(Geneva, Switzerland), Virgo Observatory(Pisa, Italy). His research covers both phenomenology studies and theoretical work. Moreover, he has published more than 1,500 papers and several books. From 1985 to 1994 Professor Davier was director of Laboratoire de l’Accélérateur Linéaire (Orsay). He was also the co-founder of FCPPL(the France China Particle Physics Laboratory). He has been on multiple advisory committees in worldwide institutes including SLAC, CERN, KEK, IHEP, etc. He is elected member of the French Academy of Sciences, and was awarded with various prestigious prizes, such as Lagarrigue Prize (LAL and French Physical Society, etc.
 
Place: 
Room 111, Physics Building
date: 
Wed, 2019-04-24 15:00 - 16:00

While the Standard Model of particle physics has been completely validated by experiment, several experimental facts and theoretical arguments suggest that it cannot be the final theory. The standard approach for discovering physics beyond the Standard Model is followed at the energy frontier explored at the LHC with so far no new finding. Another way is to carry high precision measurements at lower energies, such as in the B-factories. We shall discuss her an extreme case through an ultra precise comparison of the measured of the muon magnetic anomaly and its standard prediction.

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Log-peoriodic Quantum Oscillations in Topological Materials and Recent Achievements in 2D Crystalline Superconductors

Lecturer: 
Jian Wang, International Center for Quantum Materials, School of Physics, Peking University
Lecturer description: 

Jian Wang, Changjiang Distinguished Professor of China's Ministry of Education, received his bachelor’s degree in Physics from Shandong University in 2001, and PhD degree in condensed matter physics from Institute of Physics, Chinese Academy of Sciences in 2007. From 2006 to 2011, he worked as a Postdoc and Research Associate at Penn State University, USA. He became a Professor at Peking University in 2017. He was selected to Changjiang Distinguished Professor of China's Ministry of Education in 2016 and Chief Scientist for National Key R&D Program of China in 2018. He won Sir Martin Wood China Prize in 2015. His current research interests are qauntum transport properties of low dimensional superconductors and topological materials. Jian Wang with collaborators discovered log-periodic quantum oscillations in a solid state system, quantum Griffiths singularity in 2D superconductors, tip-induced unconventional superconductivity in topological materials, interface-modulated Ising superconductivity, as well as for the first time demonstrated high Tc in one unit cell thick FeSe films by direct transport and Meissner evidences, revealed eletron-electron interaction in topological materials, and studied the heterostructures of topological/ferromagnetic materials and superconductors etc as one of the pioneers. In recent years, he has authored more than 70 papers including Science, Science Advances, Nature Materials, Nature Physics, Nature Nanotechnology, Nature Communications, PNAS, Physical Review X, Physical Review Letters, Nano Letters, JACS, Advanced Materials etc. Jian Wang’s lab at Peking University possesses low temperature scanning tunneling microcopy/spectroscopy-molecular beam epitaxy combined ultrahigh vacuum system, ultralow temperature-high magnetic field measurement system etc.

 

Place: 
Room 111, Physics Building
date: 
Wed, 2019-04-17 15:00 - 16:00

 It is well known that there are two classes of quantum oscillations. One is magnetic field B periodic oscillations, such as Aharonov-Bohm effect for mesoscopic system and Little Parks oscillations for superconducting systems. The other one is 1/B periodic Shubnikov-deHaas and deHaas van-Alphen oscillations from quantized Landau levels. We discover a new class of quantum oscillations beyond quantum limit in topological materials by magnetoresistance measurements up to ultrahigh magnetic field, which show exotic log B periodic oscillations, i.e. discrete scale invariance [1].

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新奇二维电子材料的计算设计

Lecturer: 
赵纪军,大连理工大学物理学院,三束材料改性教育部重点实验室
Lecturer description: 

赵纪军, 1992年南京大学强化部本科毕业,1996年南京大学博士毕业。1997至2005年期间,先后在意大利国际理论物理中心、美国北卡大学、华盛顿州立大学担任博士后、研究助理教授、研究员。2006年起任大连理工大学教授,2014年起任三束材料改性教育部重点实验室主任,2017年起任物理学院院长;担任Advances in Physics X等七个国际期刊编委。主要研究领域为低维凝聚态物理、计算材料学。发表SCI论文400多篇,总引用15000余次,H因子62,入选爱思维尔中国高被引学者。享受国务院政府特殊津贴,获国家自然科学二等奖1项、省部级科技奖5项,入选万人计划领军人才、长江学者特聘教授。

 

Place: 
Room 111, Physics Building
date: 
Wed, 2019-04-10 15:00 - 16:00

在二维材料的研究中,由第一性原理出发的计算材料设计发挥着重要的作用。针对未来的微电子学、自旋电子学、拓扑材料及器件应用,考虑到实验上合成的可能性,利用表面功能化、双面不对称Janus结构、应变等调控手段,本课题组近年来基于第一性原理计算,设计一系列新奇的二维电子、磁性和拓扑材料。在报告中将介绍几类代表性体系的研究进展:1)具有高载流子迁移率和高稳定性的二维单层半导体如18种二维氧化物、d-Cu2S、GeAsSe和SnSbTe;2)具有接近或高于室温的居里温度二维铁磁材料如ScCl、LaBr2、CrSBr、CrSCl、CrSeBr;3)具有高居里温度的单层铁磁材料如MnB及其功能化衍生物;4)具有优异压电特性的第四主族单硫化物Janus单层结构;5)作为二维拓扑绝缘体的第三主族单硫化物单层氧化物;6)应变下氢或卤素原子功能化的SbAs单层结构作为自旋-谷耦合狄拉克半金属。

 

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