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Direct and noisy transitions in a model shear flow

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Theoretical & Applied Mechanics Letters 2015年第3期5卷 111-116页

作者： Marina Pausch Bruno Eckhardt fachbereich physik Philipps-Universitat Marburg J.M.Burgerscentrum Delft University of Technology

The transition to turbulence in flows where the laminar profile is linearly stable requires perturbations of finite amplitude. ＂Optimal＂ perturbations are distinguished as extrema of certain functionals, and different functionals give different optima. We here discuss the phase space structure of a 2D simplified model of the transition to turbulence and discuss optimal perturbations with respect to three criteria： energy of the initial condition, energy dissipation of the initial condition, and amplitude of noise in a stochastic transition. We find that the states triggering the transition are different in the three cases, but show the same scaling with Reynolds number.

关键词： Transition to turbulence Shear flows Noise driven Optimal initial conditions

A Phenomenological Extension of the Newtonian Gravity

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International Journal of Astronomy and Astrophysics 2019年第1期9卷 63-70页

作者： Heinz Dehnen fachbereich physik Universit&auml t Konstanz Konstanz Germany

Following the idea of our previous paper we distinguish also in the case of Newtonian gravity as in the electrodynamics between extensive and intensive field quantities. Between both, a “material’’ quantity produced e.g. by vacuum polarisations induced by the gravitational field strength itself is mediated. It acts in such a way that it amplifies the field strength in weak gravitational fields and reduces the field strength in strong gravitational fields following Lenz’s rule. Newton’s gravity is valid only in a very large intermediate range of middle field strength F?, F0? and F1?critical field strengths). In this way dark matter and black holes may be avoidable.

关键词： Flat Rotation Curves MOND Tully-Fisher Law Avoiding Singularities Vacuum-Polarisations Lenz’s Rule

Quantum Impurity Models with Coupled Cluster Method

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Communications in Theoretical Physics 2010年第9期54卷 509-517页

作者： Clive Emary Tobias Brandes Institut für Theoretische physik

We investigate the ground-state properties of the Anderson single impurity model （finite Coulomb impurity repulsion） with the Coupled Cluster Method. We consider different CCM reference states and approximation schemes and make comparison with exact Green＇s function results for the non-interacting model and with Brillouin-Wigner perturbation theory for the full interacting model. Our results show that coupled cluster techniques are well suited to quantum impurity problems.

关键词： strongly correlated electrons Anderson model coupled-cluster method quantum impurity

RAPIDITY DISTRIBUTION IN DIFFERENT MULTIPLICITY INTERVALS

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Chinese Physics Letters 1988年第9期5卷 413-416页

作者： ZHAO Weiqin PAN Jicai Institute of High Energy Physics Academla Sinica Beijing Fachbereich Physik der FU BerlinWest BerlinGermany Huazhong Normal University WuhanChina

Based on the statistical model proposed by the Berliner group,including the assumption of cluster production and considering energy conservation for each fixed total multiplicity n,good fits to the data of the rapidit... 详细信息

关键词： cluster assumption multiplicity

FROM CRYSTALLINE BLOCK SLIPS TO DOMINANCE OF NETWORK STRETCHING——MECHANISMS OF TENSILE DEFORMATION IN SEMI-CRYSTALLINE POLYMERS

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Chinese Journal of Polymer Science 2002年第2期20卷 160-170页

作者： Y. Men Fakultaet Fuer physik Albert-Ludwigs-Universitaet Freiburg 79104

The mechanism of tensile deformation in semi-crystalline polymers was studied based on true stress-strain curvesobtained with the aid of a video-controlled tensile set-up. The deformation is affected by both the crystalline and theamorphous phases. However, the relative weights of the two portions change with the deformation stage. At lowdeformations the coupling and coarse slips of the crystalline blocks dominate the mechanical properties, which allows thesystem to maintain a homogeneous strain distribution in the sample. As the stretching increases, at a critical strain the forcegenerated from entangled fluid portions reaches a critical value to destroy the crystallites. The dominant deformationmechanism then changes into a disaggregation - recrystallization process.

关键词： Semi-crystalline polymer Deformation mechanism Network Mechanical property

Potential Correlations between Unexplained Experimental Observables and Hot Projectile-Like Fragments in Primary Interactions above ECM/u≈ 150 MeV

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World Journal of Nuclear Science and Technology 2013年第4期3卷 155-161页

作者： Eberhard Ganssauge Wolfram Westmeier Reinhard Brandt fachbereich Chemie Philipps-University Marburg Germany fachbereich Chemie Philipps-University Marburg Germany Dr. Westmeier GmbH Ebsdorfergrund Germany fachbereich physik Philipps University Marburg Germany

An enhanced neutron production and an enhanced nuclear destruction due to secondary fragments have been observed in very thick targets irradiated with high energy ions. This enhancement is beyond theoretical calculations and it is an unresolved problem. It is observed only when primary ion interactions exceed an energy threshold (ECM/u ≈ 150 MeV). Investigations using nuclear emulsions for very high-energy nuclear reactions suggest that two distinctly different classes of relativistic projectile-like fragments are emitted in primary interactions: a “cool” channel with a temperature of (T(p)cool ≈ 10 MeV), and a “hot” channel with (T(p)hot ≈ 40 MeV. This second reaction class may induce the above mentioned enhanced reactions of secondary fragments, thus being responsible for unresolved problems. This assumption should be studied in further experiments. Nuclear interactions of secondary particles in thick targets are of interest, in particular in view of radiation protection needs for high energy and high intensity heavy ion accelerators. Many basic ideas of this paper go back to the late Professor E. Schopper (Frankfurt).

关键词： Very High Energy Projectile Hot Projectile Fragments Cool Target Fragments Unresolved Problems

Recent results from NA48/2

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Chinese Physics C 2010年第6期34卷 749-752页

作者： Cristina Morales Morales Institut für physik Universitt Mainz

Recent results on radiative K^± decays from the NA48/2 experiment are reported. From the full NA48/2 data set, about a million K^±→π^±π^γ decays were reconstructed. Based on this sample, the first measurement of the interference between direct photon emission and inner bremsstrahlung in K^±→π^±π^γ decays was performed. Stringent limits on CP violation in this decay were also set. In addition, a precise measurement of the branching fraction of K^±→π^±γγ is presented. This measurement was based on a data sample of more than 1000 event candidates. Also the related decay K^±→π^±e^＋e^-γ has first been observed. Results of the measurement of the decay rate and the decay parameter 5 are summarized.

关键词： radiative K^± decays NA48/2 CP violation

A topology framework for macromolecular complexes and condensates

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Nano Research 2022年第11期15卷 9809-9817页

作者： Maziar Heidari Duane Moes Otto Schullian Barbara Scalvini Alireza Mashaghi Medical Systems Biophysics and Bioengineering Leiden Academic Centre for Drug ResearchFaculty of ScienceLeiden UniversityLeiden 2333CCthe Netherlands fachbereich physik Freie Universität BerlinArnimallee 14Berlin 14195Germany Harvard Medical School Harvard University25 Shattuck StBoston MA 02115USA

Macromolecular assemblies such as protein complexes and protein/RNA condensates are involved in most fundamental cellular *** arrangement of subunits within these nano-assemblies is critical for their biological function and is determined by the topology of physical contacts within and between the subunits forming the *** the spatial arrangement of these interactions is of central importance to understand their functional and stability *** this concept article,we propose a circuit topology-based formalism to define the topology of a complex consisting of linear polymeric chains with interand intrachain *** apply our method to a system of model polymer chains as well as protein *** show that circuit topology can categorize different forms of chain *** multi-chain circuit topology should aid analysis and predictions of mechanistic and evolutionary principles in the design of macromolecular assemblies.

关键词： topology macromolecular complex protein evolution folding

Uncertainty relations for general phase spaces

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Frontiers of physics 2016年第3期11卷 51-60页

作者： Reinhard F. Werner Institut fiir Theoretische physik Leibniz Universitiit Hannover Germany

We describe a setup for obtain!ing uncertainty relations for arbitrary pairs of observables related by a Fourier transform. The physical examples discussed here are the standard position and momentum, number and angle, finite qudit systems, and strings of qubits for quantum information applications. The uncertainty relations allow for an arbitrary choice of metric for the outcome distance, and the choice of an exponent distinguishing, e.g., absolute and root mean square deviations. The emphasis of this article is on developing a unified treatment, in which one observable takes on values in an arbitrary locally compact Abelian group and the other in the dual group. In all cases, the phase space symmetry implies the eciuality of measurement and preparation uncertainty bounds. There is also a straightforward method for determining the optimal bounds.

关键词： uncertainty relations phase space measurement uncertainty