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Tracking moving magnetic features in the photosphere

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Science China(Physics,Mechanics & Astronomy) 2009年第11期52卷 1737-1748页

作者： BCHNER Jrg max-planck-institut fr Sonnensystemforschung

This research aims for an objective identification, tracking, and a statistical analysis of the Moving Magnetic features (MMfs) around sunspots using SOHO/MDI high-resolution magnetograms. To this end, we develop a computerized tracking program and study the motion and magnetism of the outflows of MMfs around 26 sunspots. Our method locates 4-27 MMfs per hour, with higher counts for large sunspots. We differentiate MMfs into type α that have a polarity opposite to the parent sunspots, and type β that share the sunspot's polarity. These sunspots' MMf subsets exhibit a wide range of central tendencies which have distinctive correlations with the sunspots. In general, α-MMfs emerge farther from the sunspot, carry less flux, and move faster than β-MMfs. The typical α/β-MMfs emerge at 2.2 - 8.1/0.1 - 3.2 Mm outside the penumbra limb, with lifetimes of 1.1 - 3.1/1.3 - 2.0 h. They are 1.1 - 6.6/1.4 - 3.6 Mm2 in area and carry 1.4 - 12.5/4.8 - 11.4 ×1018 Mx of flux. They travel a distance of 2.7 - 5.9/2.8 - 3.6 Mm with the speed of 0.5 - 0.9/0.4 - 0.7 km/s. Compared to the α-MMfs produced by large sunspots, those of small spots are smaller. They emerge closer to sunspot, move farther, live longer, and carry less flux. β-MMfs show much less correlation with the sunspots. The flux outflow carried by the MMfs ranges from 0.2 to 8.3 × 1019Mx· h-1 and does not show obvious correlation with the sunspots' evolution. The frequency distributions of the MMfs' distance traveled, area, and flux are exponential. This suggests the existence of numerous small, weak, and short-timescale magnetic objects which might contribute to the sunspot flux outflow.

关键词： sun activity magnetic fields photosphere sunspots moat moving magnetic features

Intrinsic tunneling study of underdoped Bi_2Sr_(2-x)La_xCuO_(6+δ) superconductors

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Chinese Physics B 2011年第11期20卷 469-472页

作者：任建坤任育峰田野于海峰郑东宁赵士平林成天 Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of Sciences max-planck-institut fr festkrperforschung

We report on a tunneling study of underdoped submicron Bi2Sr2_xLasCuO_6＋δ （La-Bi2201） intrinsic Josephson junctions （IJJs）, whose self-heating is sufficiently suppressed. The tunneling spectra are measured from 4.2 K up to the pseudogap opening temperature of T＊ = 260 K. The gap value found from the spectral peak position is about 35 meV and has a weak temperature dependence both below and above the superconducting transition temperature of Tc = 29 K. Since the superconducting gap should have a value of 10-15 meV, our results indicate that the pseudogap （～35 meV） plays an important role in the underdoped La-Bi2201 intrinsic tunneling spectroscopy down to the lowest temperature of 4.2 K. However, the contribution of the superconducting gap can be separated by normalizing the spectra to the one near and above Tc, which shows that the IJJs can be a useful tool for the study of the electronic properties of the La-Bi2201 cuprate superconductors.

关键词： Bi2Sr2_xLasCuO_6+δ intrinsic Josephson junctions tunneling spectra superconductinggap pseudogap

Like a G6-nal:transcriptional control of G-protein coupled receptors during oligodendroglial development

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Neural Regeneration Research 2025年第7期20卷 2001-2002页

作者： Tim Aberle Michael Wegner institut für Biochemie Friedrich-Alexander-Universität Erlangen-NürnbergErlangenGermany

Multilayered control of myelination:Quick,saltatory conduction of action potentials along nerve fibers requires the electrical insulation of axons by myelinating *** the central nervous system,this role is taken up by *** are marked by the expression of the lineage determinants Sox10 and Olig2 and arise from oligodendrocyte precursor cells(OPCs)during embryonal *** the majority of OPCs differentiate into mature oligodendrocytes when nearby axonal segments require myelination,a small subpopulation of OPCs persist as a progenitor ***,the timing of myelination and maintenance of the OPC pool both need to be precisely *** transcription factors either positively or negatively affect oligodendrocyte differentiation and maintenance of the OPC pool as components of a complex gene regulatory network(reviewed in Sock and Wegner,2021).Network activity is additionally influenced by extracellular signaling molecules that bind to receptors on the oligodendroglial cell surface and activate intracellular signaling *** the receptors are linked to the network is poorly understood so far,but pivotal to understanding the overall regulation of central nervous system(CNS)myelination in response to environmental *** insights were recently gained for Gpr37(Schmidt et al.,2024),a G-protein coupled receptor(GPCR)with known relevance in differentiating oligodendrocytes(Yang et al,2016).

关键词： gained insulation conduction

CWA formalizations in Multi-Valued Logics

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Journal of Computer Science & Technology 2001年第3期16卷 263-269页

作者：吴尽昭 max-planck-institut für Informatik Saarbrücken Germany

To enhance the expressive power and the declarative ability of a deductive database, various CWA (Closed World Assumption) formalizations including the naive CWA, the generalized CWA and the careful CWA are extended to multi-valued logics. The basic idea is to embed logic formulas into some polynomial ring. The extensions can be applied in a uniform manner to any finitely multi-valued logics. Therefore they are also of computational significance.

关键词： CWA formalization multi-valued logic polynomial form query evaluation

Mock catalogues for large surveys:Lessons from Gaia and implications for CSST

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Science China(Physics,Mechanics & Astronomy) 2023年第11期66卷 239-240页

作者： Tristan Cantat-Gaudin max-planck-institut für Astronomie Heidelberg69117Germany

Experience in large stellar surveys,such as Gaia,has shown that synthetic catalogues are very useful for preparing the data and evaluating scientific results(see the Gaia Universe model snapshot,ref.[1],as an example).This experience holds especially for complex datasets that provide not only positions and apparent magnitudes,but also proper motions,multi-band photometry,and spectroscopy.

关键词： spectroscopy survey holds

The role of Ca,Al and Zn on room temperature ductility and grain boundary cohesion of magnesium

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Journal of Magnesium and Alloys 2021年第5期9卷 1536-1551页

作者： Supriya Nandy Shao-Pu Tsai Leigh Stephenson Dierk Raabe Stefan Zaefferer max-planck institut für Eisenforschung Düsseldorf 40237Germany

It is know from literature that small additions(<1 wt%)of Ca,Al and Zn significantly improve the intrinsic ductility of *** exact role of each element,both qualitatively and quantitatively,and their combined effects,h... 详细信息

It is know from literature that small additions(f Ca,Al and Zn significantly improve the intrinsic ductility of *** exact role of each element,both qualitatively and quantitatively,and their combined effects,however,are poorly *** we achieved a much clearer view on the quantitative role of each element with respect to ductility improvement and on the collaborative effect,particularly of Ca and Zn in *** of our findings and conclusions are in disagreement with data and interpretation found in *** different alloys,namely,Mg-0.1 Ca,Mg-0.1 Ca-1 Al,Mg-0.05 Ca-1 Al,Mg-0.1 Ca-2 Al-1 Zn(all are in wt%)were selected for this *** alloys were treated such that *** grain sizes and textures were *** largely excludes the effect of extrinsic factors on ***-guided slip trace analyses reveal that the addition of Ca eases activation of prismatic and pyramidal II slip *** in-situ deformation experiments in SEM and atom probe tomography observations of grain boundaries direct evidence is given for the individual and synergetic effects of Ca and Zn on grain boundary cohesion as an important contribution to improve the ductility of these *** conclude that Ca reduces the slip anisotropy and ameliorates ductility,however,the weak grain boundary cohesion in the Mg-0.1 wt%Ca alloy limits the material’s tensile *** addition of Zn alters the Ca segregation at the grain boundaries and helps to retain their cohesive strength,an effect which thus enables higher ductility and *** further addition of Al primarily improves the *** results show that the balanced influence of reduced slip anisotropy on the one hand and increased grain boundary cohesion on the other hand allow to design a high strength high ductility rare-earth free Mg alloy.

关键词： Magnesium–Calcium–Zinc alloys Ductility Slip system determination grain boundary cohesion

Models and observations of sunspot penumbrae

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Science China(Physics,Mechanics & Astronomy) 2009年第11期52卷 1670-1677页

作者： BORRERO Juan Manuel max planck institut fr Sonnensystemforschung Max Planck Strasse 2 D 37191 Katlenburg-Lindau Germany

The mysteries of sunspot penumbrae have been under an intense scrutiny for the past 10 years. During this time, some models have been proposed and refuted, while the surviving ones had to be modified, adapted and evolved to explain the ever-increasing array of observational constraints. In this contribution I will review two of the present models, emphasizing their contributions to this field, but also pinpointing some of their inadequacies to explain a number of recent observations at very high spatial resolution (0.32 ). To help explaining these new observations I propose some modifications to each of those models. These modifications bring those two seemingly opposite models closer together into a general picture that agrees well with recent 3D magneto-hydrodynamic simulations.

关键词： sunspots magnetic fields spectropolarimetry magnetohydrodynamics

The current status and future development of high-temperature conventional superconductivity

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National Science Review 2024年第7期11卷 18-20页

作者： Mikhail I.Eremets High Pressure Chemistry and Physics Group Max-Planck-Institut für Chemie

This survey highlights key advancements in high-temperature superconductivity in hydrogen-rich materials, emphasizing the robust evidence and reproducibility of superconductivity under challenging experimental conditions of megabar pressures. In the near future, achieving room-temperature superconductivity is highly probable, and the field is expected to transition towards near-ambient-pressure superconductivity.

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Crystal structure evolution of complex metal aluminum hydrides upon hydrogen release

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Journal of Energy Chemistry 2020年第3期29卷 133-143页

作者： Claudia Weidenthaler max-planck-institut für Kohlenforschung 45470 Mülheim an der RuhrGermany

Complex aluminum hydrides have been widely studied as potential hydrogen storage materials but also,for some time now, for electrochemical applications. This review summarizes the crystal structures of alkali and alkaline earth aluminum hydrides and correlates structure properties with physical and chemical properties of the hydride compounds. The crystal structures of the alkali metal aluminum hydrides change significantly during the stepwise dehydrogenation. The general pathway follows a transformation of structures built of isolated [AlH4]- tetrahedra to structures built of isolated [Al H6]3- *** crystal structure relations in the group of alkaline earth metal aluminum hydrides are much more complicated than those of the alkali metal aluminum hydrides. The structures of the alkaline earth metal aluminum hydrides consist of isolated tetrahedra but the intermediate structures exhibit chains of cornershared octahedra. The coordination numbers within the alkali metal group increase with cation sizes which goes along with an increase of the decomposition temperatures of the primary hydrides. Alkaline earth metal hydrides have higher coordination numbers but decompose at slightly lower temperatures than their alkali metal counterparts. The decomposition pathways of alkaline metal aluminum hydrides have not been studied in all cases and require future research.

关键词： Complex aluminum hydrides Hydrogen storage Crystal structure