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18
2025/07
“丝绸之路”沿线国家农业科教合作概况及展望
“丝绸之路”沿线国家农业科教合作概况及展望
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18
2025/07
LAZYs基因调控水稻分蘖角度的分子机制
LAZYs基因调控水稻分蘖角度的分子机制
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15
2025/07
Codes, groups and designs
Theadjacency code of a rank three group contains PBIBDs by construction. When weare lucky we obtain a BIBD also known as 2-design. This is the casefor instance of the one point stabilizer of PSL(2,41) in its action onthe binary QR(41). When we are even luckyer we obtain a 3-design inthe extended code. This is the case of the XQR(41) in length 42. Byconsidering known families of rank 3 groups we obtain in that way 111 2-designand nine 3-designs. The supporting codes are constructed by modularrepresentation theory. ( joint works with Bonnecaze and with Rodrigues). Anothergroup action method applies to isodual ternary codes the automorphism group ofwhich admits two orbits on triples (joint work with Shi and Liu.) Interestingexamples are provided by Generalized Quadratic Residue codes, a family ofabelian codes discussed by van Lint and MacWilliams. Since none of thediscussed designs can be explained by the Assmus-Mattson theorem ortransitivity arguments, all of this work is based on computer calculationsin Magma. Recently a theoretical explanation of the designs in the weight10 codewords of the XQR(41) was provided by Munemasa based on harmonic weightenumerators.
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15
2025/07
Banach Spaces with the Ball Covering Property
A Banach space is said to have the ball coveringproperty if its unit sphere can be covered by countably many open balls off theorigin. The ball covering property is a property that has close relationshipswith the topological properties and geometric properties of Banach spaces. Inthis talk, we will give a review of the historical literature and present somerecent advances on this topic. Open problems will be proposed, and approacheswill be discussed.
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14
2025/07
Projected Sobolev gradient flows and its application to compute ground state of ultracold dipolar fermi gas
We first provide an overview of gradient flow for minimization problem. Then we note that the ground state for the ultracold fermi gas with dipole-dipole interaction is a functional minimization problem based on density functional theory (DFT). We extend the recent work on Sobolev gradient flow for the Gross-Pitaevskii eigenvalue problem, and present continuous projected Sobolev gradient flows for computing the DFT-based ground state solution of ultracold dipolar fermi gas. We prove that the gradient flows have the properties of orthonormal preserving and energy diminishing, which is desirable for the computation of the ground state solution. Many numerical technique for partial differential equation can be used to discretize the time-dependant projected Sobolev gradient flows, which may be an advantage of the method. We propose an efficient and accurate numerical scheme – semi-implicit Euler method in time and Fourier spectral method in space for discretizing these projected Sobolev gradient flows and use them to find the ground states of the fermi gas numerically. Extensive numerical examples in three dimensions for ground states are reported to demonstrate the power of the numerical methods and to discuss the physics of dipolar fermi gas at very low temperature.
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09
2025/07
氦离子显微镜的原理与应用
氦离子显微镜的原理与应用。包括发展历史与工作原理、应用方向、总结展望。
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18
2025/07
人类世中的鸟类多样性保护
人类世中的鸟类多样性保护
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13
2025/07
Dietary isothiocyanates derived from glucosinolates in cruciferous vegetables and cancer management
Dietary isothiocyanates derived from glucosinolates in cruciferous vegetables and cancer management
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09
2025/07
国家科研体制的全新尝试——中科院数学院的成立
1998年中国科学院数学与系统科学研究院成立，不仅是我国数学史上的一个重要事件，也是我国科技史上的一个重要事件。本报告阐述了其成立的背景、成立过程中的主要改革举措以及产生的影响。一方面试图弄清这一事件的完整过程，一方面希望从中获取一些科学发展方面的经验和启示。
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11
2025/07
Groups as the automorphism groups of graphs and digraphs
In 1936, K?nig conjectured that every finite group can be represented as the automorphism group of a finite graph. This was answered in the affirmative by Frucht in 1939. Since then, this problem has been explored under various constraints on the graph. A particularly interesting case arises when the graph is vertex-transitive and has the same order as the group; such a graph is known as a Graphical Regular Representation (GRR). In the 1970s, a series of papers established which groups admit GRRs. In this talk I will first provide an overview of these classic results and then discuss some recent developments, including asymptotic enumeration, GRRs with specific valencies, and new variations of GRRs.
