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seventy-five years of masting and rodent population peaks in Norway: Why do wood mice not follow the rules?

Integrative Zoology 2016年第5期11卷 388-402页

作者： vidar selås Department of Ecology and Natural Resource Management Norwegian University of Life SciencesÅsNorway

Wood mouse(Apodemus sylvaticus)populations are expected to show a peak in autumn in the year after a mast year of sessile oak(Quercus petraea),because stored acorns increase winter *** Aust-Agder,south Norway,only 16 of 34 mast years from 1939-2014 were followed by a year with a peak in the wood mouse *** many of the remaining instances,there rather was a minor peak 2 or 3 years after the *** multiple logistic regression models,the probability of a wood mouse population peak after a mast year of sessile oak was positively related to a snow-corrected temperature index of the previous winter and negatively to a small rodent population index of the previous *** present study thus supports the hypothesis that longer periods with snow-free ground and subzero temperatures negatively affect wood mouse winter ***cause it may be difficult for wood mice to survive on a diet consisting of acorns alone,the negative relationship with the rodent population index of the previous year is most likely caused by an over-exploitation of necessary alternative food resources,such as other plant seeds and *** acorns not utilized during one winter are assumed to benefit wood mice in a succeeding winter,giving a delayed population peak relative to the mast year.

关键词： acorns masting seed production winter temperature wood mouse

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A unified field theory of topological defects and non-linear local excitations

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npj Computational Materials 2023年第1期9卷 1092-1104页

作者： vidar skogvoll Jonas Rønning Marco salvalaglio Luiza Angheluta PoreLab Njord CentreDepartment of PhysicsUniversity of OsloP.O.Box 10480316 OsloNorway Institute of scientific Computing TU Dresden01062 DresdenGermany Dresden Center for Computational Materials science TU Dresden01062 DresdenGermany

Topological defects and smooth excitations determine the properties of systems showing collective *** introduce a generic non-singular field theory that comprehensively describes defects and excitations in systems with O(n)broken rotational *** this formalism,we explore fast events,such as defect nucleation/annihilation and dynamical phase transitions where the interplay between topological defects and non-linear excitations is particularly *** highlight its versatility,we apply this formalism in the context of Bose-Einstein condensates,active nematics,and crystal lattices.

关键词： excitation topological theory

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Apochromatic X-ray focusing

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Light(science & Applications) 2023年第7期12卷 1301-1308页

作者： Umut T.sanli Griin Rodgers Marie-Christine Zdoraol Peng Qio Jan Garrevoet Ken vidar Falch Bert Muller Christian David Joan Vila-Comamala Paul scherrer Institute Laboratory for X-ray Nanoscience and TechnologiesForschungsstrasse 1115232 ViligenSwitzerland Biomaterials science Center Department of Biomedical EngineeringUniversity of BaselHegenheimermattweg 167 B4123 AllschwilSwitzerland Deutsches Elektronen-synchrotron DEsY Notkestr.8522607 HamburgGermany

Achromatic doublets are combinations of two individual lenses designed to focus different wavelengths of light in the same *** optics are improved versions of the achromatic schemes which extend the wavelength range *** achromatic and apochromatic optics are well-established for visible ***,X-ray achromatic lenses did not exist until very recently,and X-ray apochromatic lenses have never been experimentally ***,we create an X-ray apochromatic lens system using an appropriate combination of a Fresnel zone plate and a diverging compound refractive lens with a tuned separation *** energy-dependent performance of this apochromat was characterized at photon energies between 6.5 and 13.0 keV by ptychographic reconstruction of the focal spot and scanning transmission X-ray microscopy of a resolution test *** apochromat delivered a reconstructed focal spot size of 940×740 nm^(2).The apochromatic combination shows a four-fold improvement in the chromatic aberration correction range compared to an achromatic doublet ***,apochromatic X-ray optics have the potential to increase the focal spot intensity for a wide variety of X-ray applications.

关键词： chromatic optics correction

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Hofstadter butterfly的新拓扑相

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物理 2021年第4期50卷 271-271页

作者：朱星(编译) vidar Gudmundsson 北京大学不详

许多材料表现出拓扑相。大多数情况下,这种稳定拓扑物态来源于复杂能带的自旋—轨道耦合。但是,对一个在强磁场下的二维晶格而言,简单的能带结构也可以出现拓扑效应。这种磁致的拓扑相源自磁场和晶格的竞争,具有像蝴蝶翅膀一样的分形结... 详细信息

许多材料表现出拓扑相。大多数情况下,这种稳定拓扑物态来源于复杂能带的自旋—轨道耦合。但是,对一个在强磁场下的二维晶格而言,简单的能带结构也可以出现拓扑效应。这种磁致的拓扑相源自磁场和晶格的竞争,具有像蝴蝶翅膀一样的分形结构,是Douglas Hofstadter在1976年提出来的,因此也称Hofstadter butterfly。

关键词：蝴蝶翅膀分形结构能带结构二维晶格拓扑

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