人工智慧与慧眼卫星—李惕碚院士 | 本周物理学术讲座

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人工智慧与慧眼卫星—李惕碚院士 | 本周物理学术讲座

2018 年 1 月 23 日 中国物理学会期刊网

1人工智慧与慧眼卫星

报告人：李惕碚院士，中科院高能物理所

时间：1月26日（周五）9:00

单位：中科院高能物理研究所

地点：化学楼C305

我国学者于上世纪90年代初建立直接解调方法，用非成像探测器实现高精度成像，并据此提出了研制空间硬X射线调制望远镜HXMT的建议。三代学者历经25年的努力，终于成功发射我国首颗X射线天文卫星“慧眼”。报告人2000-2015年任HXMT预先研究、背景型号和工程项目的首席科学家，他将结合人工智能的发展回顾慧眼卫星的历程，并讨论我国在宽容自主创新和抓住发展机遇方面存在的问题。

李惕碚院士 简介：高能天体物理学家 1939年6月12日生于重庆北碚，籍贯湖南攸县。1963年毕业于清华大学工程物理系。1997年当选为中国科学院院士。中国科学院高能物理研究所研究员，粒子天体物理重点实验室学术委员会主任清华大学教授，清华大学天体物理中心主任。“973”国家重点基础研究发展规划“天体高能辐射的空间观测与研究”项目首席科学家。

在宇宙线和高能天体物理实验研究与数据分析等方面取得重要成果。在国内倡议和组织开拓了高能天体物理的实验研究。提出了银河系g射线源的统计模型并获国际共识。建立了寻找超高能天体的计算公式，已成为宇宙线和高能天体物理数据分析的一个标准方法。建立了对象重建的直接解调方法和研究快速变化现象的时域谱方法，获得日益广泛的应用。

2Towards Precision Personalized Medicine: Point of Care (POC) Systems, Organ on a Chip for Ultra-Sensitive Quantitative Detection of Biomarkers in Physiological fluids

报告人：V. Renugopalakrishnan，Northeastern University and Harvard Medical School

时间：1月23日（周二）15:00

单位：中科院物理研究所

地点：M楼236会议室

Rapid, accurate, continuous, and quantitative measurement of biomarkers from body fluids are critical for non-invasive assessment of clinical status of various metabolic disorders to improve disease management and clinical progress. The goal of this Bioengineering Consortium is to develop multiplexed sensors that use a drop of blood or urine (> 10 micro L) and quantify more than one clinically important analyte simultaneously and answer specific questions for diagnosis or research. The small sample size means that the devices can be used at the bedside, home, or laboratory. The proposed multiplexed sensor makes several measurements simultaneously which are analyzed together to determine a specific result with greater precision than a single sensor and more efficiently than a series of individual tests. We have found several clinical research programs that are extremely interested in this approach, even though it is different than the standard model for clinical care where physicians rely on data collected from a list of separate individual tests to determine a diagnosis. Personalized, Precision Medicine requires extremely sensitive POC devices and systems. The fundamental technology proposed for the multiplexed sensor platform is a new electronic biosensor platform technology based on two-dimensional (2D) atomically layered materials (such as graphene, doped graphene and molybdenum disulphide- MoS2) in combination with high sensitivity electrical impedance spectroscopic (FET) readout. These 2D-FET sensors combine the exceptional electrical properties of emerging atomically thin planar nanomaterials, the selectivity of proteins and other targets, and low-cost fabrication to offer new diagnostic tools with much greater precision. Organ on a Chip, Pancreas, are embedded in flexible polymeric sheets, wearable, screen printable for large scale manufacturing. The Bioenginering Consortium has demonstrated biosensors that use enzymes, antibodies, and single-stranded mRNAs and microRNAs for molecular recognition and sensing. These sensors will be evaluated at Children’s Hospital in Boston, Mayo Clinic, Brigham and Women’s Hospital with the collaboration of clinical collaborators and physicians.

3The Dawn of Star Formation: revealing the initial conditions for massive star formation throughout the Milky Way

报告人：Ke Wang，the European ALMA Regional Center

时间：1月23日（周二）16:00

单位：北京大学科维理天文与天体物理研究中心

地点：KIAA-PKU Auditorium

Star formation sets the conditions for the formation of planets and origin of life. On large scales, massive stars drive the evolution of galaxies. The formation of massive stars is a fundamentally importantyet unresolved problem in astrophysics. In particular, the initial conditions are not well known due to a lack of in-depth observations. This has led to different assumed initial conditions in debating theoretical models. Thanks to recent multi-wavelength surveys, it is finally feasible to make a Galaxy-wide census of massive clumps (precursors to high-mass star clusters) using high-resolution deep ALMA observations. I present our series studies on infrared dark clouds (IRDCs) that pioneered in characterizing the earliest stages during massive star formation. Built on these, I show how our carefully designed ALMA surveys of starless IRDCs can uncover deeply embedded core populations for robust cross comparison, and thereby can single out the truly initial conditions across the Galaxy. In the next 5-10 years, we expect that these combined efforts will give definitive answers to key questions in high-mass star formation, and motivate the next generation of star formation models.

4Thin film deposition and high-field transport properties of Fe-based superconductors

报告人： Jens Hänisch，Karlsruhe Institute of Technology

时间：1月24日（周三）10：00

单位：中科院物理所

地点：M236会议室

The Fe-based superconductors (FBS) are very interesting materials both for basic research as well as in view of potential applications. FBS are unconventional, anisotropic, partially quantum-critical, multi-band superconductors, and all of these characteristics reflect to some extend in the electrical transport properties. They usually show very high upper critical fields and concurrent high irreversibility fields at low temperatures. This opens the possibility of high in-field critical current densities Jc, interesting especially for high-field applications.

Three crystallographic systems of FBS, namely the ‘11’ chalcogenides Fe(Se,Te), the ‘122’ pnictides BaFe2As2 with different kinds of doping, and the ‘1111’ oxypnictides REFeAs(O,F) (RE Sm, Nd), differing in critical temperature Tc and complexity of crystal structure, are often regarded for applications and readily prepared as thin films by pulsed laser deposition (PLD) or molecular beam epitaxy (MBE) on single-crystalline and technical substrates. Pauli limitation and multi-band effects lead to a strong temperature-dependent anisotropy of Hc2, which is furthermore different from the penetration depth anisotropy. This has to be taken into account for microscopic explanations of the Jc anisotropy. Short coherence lengths (similar to the cuprates) necessitate reasonably sharp textures (where nonetheless grain boundaries are pinning-active) and a complex landscape of nanoscale pinning centers for high current densities.

In this presentation, relationships among the three aforementioned systems (and others, such as LiFeAs and the intercalated systems), characteristics of their preparation as thin films, as well as their high-field transport properties will be discussed, mainly on the basis of selected examples of our group’s investigations in Fe-based superconducting thin films of the past 10 years.

5Chaotic Scattering in Quantum Systems With and Without Time-Reversal Invariance

报告人：Barbara Dietz，Lanzhou University

时间：1月24日（周三）15:30

单位：中科院理论物理研究所

地点：ITP New Building 6420

We present our theoretical results obtained from the random-matrix approach to quantum chaotic scattering for systems with partially violated time-reversal (T) invariance. They were tested most precisely in measurements of scattering amplitudes of a chaotic microwave resonator in the regime of isolated and overlapping resonances. Below a certain excitation frequency the resonator simulates a quantum billiard, whose eigenvalues manifest themselves in the spectra as resonances with average spacing d and width Γ. Violation of T invariance is achieved with a magnetized ferrite inside the cavity. The experimental observables are complex scattering (S)-matrix elements, measured for the resonator with and without T invariance as a function of frequency. Particular emphasis is given to S-matrix correlation functions in the regime of weakly overlapping resonances, i.e., Γ /d < 1, and their comparison to results from the theory of chaotic scattering developed in nuclear reaction theory. We also present results on the distribution of the S-matrix elements and higher order correlation functions. Here, a focus is the transition from the regime of weakly overlapping resonances to the Ericson regime, i.e., from non-exponential to exponential decay of the system of resonances.

6Relativistic Fermions in a Magnetic Field: From Quantum Hall Effect in Graphene to Chiral Asymmetry in QED

报告人：夏丽芳，Arizona State University

时间：1月25日（周四）10:00

单位：北京师范大学物理系

地点：物理楼106

In the first part of my work, we use the generalized Landau-level representation to study the effect of screening on the properties of the graphene quantum Hall states with integer filling factors. The analysis is performed in the low-energy Dirac model in the mean-field approximation, in which the long-range Coulomb interaction is modified by the one-loop static screening effects. The solutions demonstrate that static screening leads to a substantial suppression of the gap parameters in the quantum Hall states with a broken U(4) flavor symmetry. The results of the temperature dependence of the energy gaps mimic well the temperature dependence of the activation energies measured in experiment. The Landau-level running of the quasiparticle dynamical parameters could be tested via optical studies of the integer quantum Hall states.

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