检索结果-南通市图书馆

The Origin of the Flat Rotation Curves in Spiral Galaxies: The Hidden Roles of Glitching SMDEOs and Emission of Gravitational Waves

引用

Journal of Modern Physics 2024年第10期15卷 1523-1542页

作者： Ahmad A. Hujeirat peter Berczik Interdisciplinary Center for Scientific Computing Faculty of Physics and Astronomy University of Heidelberg Heidelberg Germany Main Astronomical Observatory Kyiv Ukraine

Supermassive DEOs (SMDEOs) are cosmologically evolved objects made of irreducible incompressible supranuclear dense superfluids: The state we consider to govern the matter inside the cores of massive neutron stars. These cores are practically trapped in false vacua, rendering their detection by outside observers impossible. Based on massive parallel computations and theoretical investigations, we show that SMDEOs at the centres of spiral galaxies that are surrounded by massive rotating torii of normal matter may serve as powerful sources for gravitational waves carrying away roughly 1042 erg/s. Due to the extensive cooling by GWs, the SMDEO-Torus systems undergo glitching, through which both rotational and gravitational energies are abruptly ejected into the ambient media, during which the topologies of the embedding spacetimes change from curved into flatter ones, thereby triggering a burst gravitational energy of order 1059 erg. Also, the effects of glitches found to alter the force balance of objects in the Lagrangian-L1 region between the central SMDEO-Torus system and the bulge, enforcing the enclosed objects to develop violent motions, that may explain the origin of the rotational curve irregularities observed in the innermost part of spiral galaxies. Our study shows that the generated GWs at the centres of galaxies, which traverse billions of objects during their outward propagations throughout the entire galaxy, lose energy due to repeatedly squeezing and stretching the objects. Here, we find that these interactions may serve as damping processes that give rise to the formation of collective forces f∝m(r)/r, that point outward, endowing the objects with the observed flat rotation curves. Our approach predicts a correlation between the baryonic mass and the rotation velocities in galaxies, which is in line with the Tully-Fisher relation. The here-presented self-consistent approach explains nicely the observed rotation curves without invoking dark matter or mo

关键词： General Relativity: Black Holes Neutron Stars Quantum Fields: QCD Condensed Matter Incompressibility Superfluidity Cosmology: Galaxy Formation Spiral Galaxies Dark Matter Rotation Curves

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

人工智能支持的知识导图设计与地理教学备课

引用

地理教学 2024年第13期 12-17页

作者：崔羽 peter Reimann 南京师范大学江苏南京210023 悉尼大学澳大利亚悉尼2006

本研究利用人工智能的一种自然语言处理技术——语义网络技术,采用学习科学领域中基于设计的研究方法,设计了一款由语义数据库支持的知识导图应用程序,并将其应用于地理教学中。本文以地理学中的水圈知识为例,介绍了学生作为同伴导师设... 详细信息

本研究利用人工智能的一种自然语言处理技术——语义网络技术,采用学习科学领域中基于设计的研究方法,设计了一款由语义数据库支持的知识导图应用程序,并将其应用于地理教学中。本文以地理学中的水圈知识为例,介绍了学生作为同伴导师设计的知识导图形式的备课教案,并阐释了学生导师通过同伴教学备课,实现知识学习和认知提升的理论依据。本研究引入人工智能技术支持的地理教学增强知识导图,作为一种创新策略,旨在促进学生导师的个体学习,同时为集体知识建设做出贡献。

关键词：人工智能语义技术知识导图地理教学备课教案

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Inbreeding and genetic load in a pair of sibling grouse species:Tetrastes sewersowi and ***

引用

Avian Research 2024年第2期15卷 265-270页

作者： Kai Song Tom van der Valk Bin Gao peter Halvarsson Yun Fang Wendong Xie Siegfried Klaus Zhiming Han Yue-Hua Sun Jacob Hoglund Key Laboratory of Animal Ecology and Conservation Biology Institute of ZoologyChinese Academy of SciencesBeijing100101China Animal Ecology Department of Ecology and GeneticsUppsala UniversityNorbyvagen 18DUppsala75236Sweden Department of Cell and Molecular Biology Uppsala75273Sweden Unit of Parasitology Department of Biomedicine and Veterinary Public HealthSwedish University of Agricultural SciencesPO Box 7036Uppsala75007Sweden Lindenhohe 5 JenaD-07749Germany The State Key Laboratory of Reproductive Biology Institute of ZoologyChinese Academy of SciencesBeijing100101China

Genetic load and inbreeding are recognized as important factors to be considered in conservation *** levels of both can increase the risk of population extinction by negatively impacting fitness-related characters in many species of plants and animals,including humans(inbreeding depression).Genomic tech-niques are increasingly used in measuring and understanding genetic load and inbreeding and their importance in evolution and *** used whole genome resequencing data from two sibling grouse species in subarctic Eurasia to quantify *** found a large range of inbreeding measured as FROH(fraction of runs of homozygosity)in individuals from different populations of Chinese Grouse(Tetrastes sewerzowi)and Hazel Grouse(***).FROH estimated from genome-wide runs of homozygosity(ROH)ranged from 0.02 to 0.24 among Chinese Grouse populations and from 0.01 to 0.44 in Hazel *** from a population of Chinese Grouse residing in the Qilian mountains and from the European populations of Hazel Grouse(including samples from Sweden,Germany and Northeast Poland)were the most inbred(FROH ranged from 0.10 to 0.23 and 0.11 to 0.44,respectively).These levels are comparable to other highly inbred populations of *** Grouse from northern China and Chinese Grouse residing in the Qinghai-Tibetan Plateau showed relatively lower inbreeding *** of the ratio between deleterious missense mutations and synonymous mutations revealed higher levels in Chinese Grouse as compared to Hazel *** results are possibly explained by higher fixation rates,mutational melt down,in the range-restricted Chinese Grouse compared to the wide-ranging Hazel ***,when we compared the relatively more severe class of loss-of-function muta-tions,Hazel Grouse had slightly higher levels than Chinese Grouse,a result which may indicate that purifying selection(purging)has been more efficient in Chinese Grouse on this class of mutations.

关键词： Genetic load Inbreeding Purifying selection Qinghai-Tibetan Plateau ROH Tetrastes

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Achieving strength-ductility synergy in novel paramagnetic Fe-based medium-entropy alloys through deep cryogenic deformation

引用

Rare Metals 2024年第9期43卷 4493-4507页

作者： Hu-Wen Ma Yan-Chun Zhao Li Feng Tian-Zeng Liu Zhi-Qi Yu Bo Jin Wang-Chun Duan peter K.Liaw Dong Ma State Key Laboratory of Advanced Processing and Recycling of Non-Ferrous Metals Lanzhou University of TechnologyLanzhou 730050China Wenzhou Pump and Valve Engineering Research Institute Lanzhou University of TechnologyWenzhou 325105China Iron and Steel Research Institute Jiuquan Iron and Steel CorporationJiayuguan 735100China Lanzhou Resources and Environment Voc-Tech University Lanzhou 730123China Department of Materials Science and Engineering The University of TennesseeKnoxvilleTN 37996-2200USA Neutron Science Center Songshan Lake Materials LaboratoryDongguan 523808China

Cryogenic pre-deformation treatment has been widely used to effectively improve the comprehensive mechanical properties of steels and novel ***,the dislocation evolution and phase transformation induced by different degrees of deep cryogenic deformation are not yet fully *** this study,the effects of multiple cryogenic pre-treatments on the mechanical properties and deformation mechanisms of a paramagnetic Fe_(63.3)Mn_(14-)Si_(9.1)Cr_(9.8)C_(3.8)medium-entropy alloy(MEA)were investigated,leading to the discovery of a pretreated MEA that exhibits exceptional mechanical properties,including a fracture strength of 3.0 GPa,plastic strain of 26.1%and work-hardening index of *** addition,X-ray diffraction(XRD)and transmission electron microscopy(TEM)analyses revealed that multiple cryogenic pre-deformation treatments significantly increased the dislocation density of the MEA(from 9×10^(15)to 4×10^(16)m^(-2)after three pretreatments),along with a transition in the dislocation type from predominantly edge dislocations to mixed dislocations(including screw-and edge-type dislocations).Notably,this pretreated MEA retained its paramagnetic properties(μ_(r)<1.0200)even after *** calculations showed that cryogenic pretreatment can significantly reduce the stacking fault energy of the MEA by a factor of approximately four(i.e.,from 9.7 to2.6 m J·m^(-2)),thereby activating the synergistic effects of transformation-induced plasticity,twinning-induced plasticity and dislocation strengthening *** synergistic effects lead to simultaneous strength and ductility enhancement of the MEA.

关键词： Deep cryogenic transformation Iron-based medium-entropy alloys Dislocation evolution Phase transformation Stacking fault energy

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

深度神经网络结合迁移学习和基因遗传算法加速金属团簇结构全局优化

引用

Chinese Journal of Chemical Physics 2024年第2期37卷 321-329,I0010-I0021,I0104页

作者：杨祁李子玉 peter L.Rodriguez-Kesslerbr 何圣贵中国科学院化学研究所动态与稳态结构化学国家重点实验室北京100190 墨西哥光学研究中心瓜纳华托37150 中国科学院大学北京100049 北京分子科学国家研究中心中国科学院分子科学科教融合卓越创新中心北京100190

在团簇科学中,搜索金属团簇的全局最小能量结构具有重要的意义.最近,深度神经网络结合迁移学习的全局优化方法被开发出来,以提高金属团簇结构的优化效率,该方法可以大幅减少训练深度神经网络所需的样本数量.为了进一步提高势能面的采样... 详细信息

在团簇科学中,搜索金属团簇的全局最小能量结构具有重要的意义.最近,深度神经网络结合迁移学习的全局优化方法被开发出来,以提高金属团簇结构的优化效率,该方法可以大幅减少训练深度神经网络所需的样本数量.为了进一步提高势能面的采样效率和深度神经网络结合迁移学习的全局优化方法的全局搜索能力,本文提出了一种将基因遗传算法嵌入到深度神经网络结合迁移学习中的全局优化方法.在Pt_(n)(n=9-15)团簇的全局优化中,该方法只需要深度神经网络结合迁移学习的全局优化方法一半的样本数量就能优化得到全局最优结构,同时节省了约70%~80%的计算成本,这表明全局搜索能力的显著提升。在Pt_(14)团簇势能面上的采样结果显示,该方法搜索到低能量的样本(占比25%)比深度神经网络结合迁移学习方法的样本(占比<1%)更多.在Pt_(16)和Pt_(17)团簇的全局最优结构搜索中,本文报道了文献中尚未报道的新结构,证明本论文建立的方法的可行性和先进性.

关键词：全局优化深度神经网络迁移学习基因遗传算法金属团簇铂

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

核物质中张量力效应的相对论第一性原理研究

引用

Science Bulletin 2024年第14期69卷 2166-2169页

作者：王锶博童辉王宸璨赵强 peter Ring 孟杰 Department of Physics and Chongqing Key Laboratory for Strongly Coupled Physics Chongqing UniversityChongqing 401331China Helmholtz Institute for Radiation and Nuclear Physics University of BonnBonn D-53115Germany School of Physics and Astronomy Sun Yat-sen UniversityZhuhai 519082China Center for Exotic Nuclear Studies Institute for Basic ScienceDaejeon 34126South Korea Department of Physics Technical University of MunichGarching D-85747Germany State Key Laboratory of Nuclear Physics and Technology School of PhysicsPeking UniversityBeijing 100871China

As a crucial ingredient of the nucleon-nucleon(NN)interaction,the tensor force has an important impact on the structural and dynamical properties of the nuclear many-body system,particularly the properties of exotic nuclei far away from the stability,which are crucial for understanding the nucleosynthesis in nuclear *** efforts have been devoted to studying the influence of the tensor force in the effective NN interaction in the nuclear medium within the configuration interaction shell model[1]and the density functional theories(DFTs)[2].Due to the difference of modeling the effective NN interaction and the difficulty of determining the tensor-force strengths in finite nuclei,the tensorforce effects in nuclear physics still need to be fully settled.

关键词：张量力核物质 tensor

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

China, Malaysia, and an Emerging New World Order

引用

China Report ASEAN 2024年第7期9卷 32-33页

作者： peter T C Chang Institute of China Studies University of Malaya

The strong relationship between China and Malaysia can be a catalyst for advancing a more stable and representative world *** leveraging their close ties,both nations can collaborate on diplomatic initiatives,economic... 详细信息

关键词： order stability catalyst

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Organochlorides Mediate Oxidation Reactions Induced by Low Dose Ionizing Radiation

引用

CCS Chemistry 2024年第7期6卷 1712-1720页

作者： Juncheng Liu Tobias G.Brevé Bing Xu peter-Leon Hagedoorn Antonia G.Denkova Rienk Eelkema Department of Radiation Science and Technology Delft University of Technology2629 JB Delft Department of Chemical Engineering Delft University of Technology2629 HZ Delft Department of Biotechnology Delft University of Technology2629 HZ Delft

The controlled release of drugs using local ionizing radiation presents a promising approach for targeted cancer treatment,particularly when applied in concurrent *** these approaches,radiation-generated reactive species often play an important ***,the reactive species that can be used to trigger release have low yield and lack ***,we demonstrate the generation of highly oxidative species when aqueous solutions containing low concentrations of organochlorides(such as chloroform)are irradiated with ionizing radiation at therapeutically relevant *** reactive species were identified as peroxyl radicals,which formed in a reaction cascade between organochlorides and aqueous *** employed stilbene-based probes to investigate the oxidation process,showing double bond oxidation and *** translate this reactivity into a radiation-sensitive material,we synthesized a micelle-forming amphiphilic block copolymer that has stilbene as the linker between two *** exposure to ionizing radiation,the oxidation of stilbene led to the cleavage of the polymer,which induces the dissociation of the block-copolymer micelles and the release of loaded drugs.

关键词： drug delivery micelles radiation chemistry reactive oxygen species ionizing radiation reaction mechanisms

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Thin-Shell Wormholes Admitting Conformal Motions in Spacetimes of Embedding Class One

引用

International Journal of Astronomy and Astrophysics 2024年第3期14卷 162-171页

作者： peter K. F. Kuhfittig Department of Mathematics Milwaukee School of Engineering Milwaukee USA

This paper discusses the feasibility of thin-shell wormholes in spacetimes of embedding class one admitting a one-parameter group of conformal motions. It is shown that the surface energy density σis positive, while the surface pressure is negative, resulting in , thereby signaling a violation of the null energy condition, a necessary condition for holding a wormhole open. For a Morris-Thorne wormhole, matter that violates the null energy condition is referred to as “exotic”. For the thin-shell wormholes in this paper, however, the violation has a physical explanation since it is a direct consequence of the embedding theory in conjunction with the assumption of conformal symmetry. These properties avoid the need to hypothesize the existence of the highly problematical exotic matter.

关键词： Thin-Shell Wormholes Conformal Symmetry Embedding Class One Exotic Matter

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Macroscopic Traversable Wormholes: Minimum Requirements

引用

International Journal of Astronomy and Astrophysics 2024年第3期14卷 230-243页

作者： peter K. F. Kuhfittig Department of Mathematics Milwaukee School of Engineering Milwaukee USA

While wormholes are just as good a prediction of Einstein’s theory as black holes, they are subject to severe restrictions from quantum field theory. To allow for the possibility of interstellar travel, a macroscopic wormhole would need to maintain sufficiently low radial tidal forces. It is proposed in this paper that the assumption of zero tidal forces, i.e., the limiting case, is sufficient for overcoming the restrictions from quantum field theory. The feasibility of this approach is subsequently discussed by 1) introducing the additional conditions needed to ensure that the radial tidal forces can indeed be sufficiently low and 2) by viewing traversable wormholes as emergent phenomena, thereby increasing the likelihood of their existence.

关键词： Morris-Thorne Wormholes Traversability Minimum Requirements Stability Compatibility with Quantum Field Theory

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：