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排序方式: 共有329条查询结果,搜索用时 265 毫秒
321.
Gubbiotti G Madami M Tacchi S Carlotti G Tanigawa H Ono T Giovannini L Montoncello F Nizzoli F 《Physical review letters》2006,97(24):247203
We present a Brillouin light scattering investigation of the eigenmode spectrum of nanometric permalloy rings as a function of the applied magnetic field. In particular, different splitting effects induced by the applied magnetic field on the radial and azimuthal excitations have been observed and explained in terms of either mode localization or symmetry. The dynamical matrix approach has been used to calculate the whole set of eigenvectors and eigenvalues of the system, in both the vortex and saturated states. 相似文献
322.
Oberholzer S Bieri E Schönenberger C Giovannini M Faist J 《Physical review letters》2006,96(4):046804
We investigate a beam-splitter experiment implemented in a normal-conducting fermionic electron gas in the quantum Hall regime. The cross correlations between the current fluctuations in the two exit leads of the three terminal device are found to be negative, zero, or even positive, depending on the scattering mechanism within the device. Reversal of the cross correlation sign occurs due to interaction between different edge states and does not reflect the statistics of the fermionic particles which "antibunch." 相似文献
323.
Modern computer microprocessors are composed of hundreds of millions of transistors that interact through intricate protocols. Their performance during program execution may be highly variable and present aperiodic oscillations. In this paper, we apply current nonlinear time series analysis techniques to the performances of modern microprocessors during the execution of prototypical programs. Our results present pieces of evidence strongly supporting that the high variability of the performance dynamics during the execution of several programs display low-dimensional deterministic chaos, with sensitivity to initial conditions comparable to textbook models. Taken together, these results show that the instantaneous performances of modern microprocessors constitute a complex (or at least complicated) system and would benefit from analysis with modern tools of nonlinear and complexity science. 相似文献
324.
Vincent De Waele Uli Schmidhammer Jean-Raphaël Marqus Hugues Monard Jean-Philippe Larbre Nicolas Bourgeois Mehran Mostafavi 《Radiation Physics and Chemistry》2009,78(12):1099-1101
A single-shot electro-optic (EO) diagnostic has been installed on the ELYSE photocathode RF gun accelerator to monitor the electron bunch at the place and under the conditions of the ps pulse radiolysis experiments. The EO signal is due to the coulombic field of the electron bunch and to a contribution of a free-space THz radiation generated by the same electron pulse. This signal is recorded shot-to-shot at the repetition rate of the accelerator. The jitter of the arrival time of the electron bunch is characterized for the first time with a non-invasive method and is confirmed to be around 1 ps. 相似文献
325.
Lars-Erik Briggner Rene Céolin Julien Giovannini Nathalie Payraudeau Ingemar Wads? 《Journal of Thermal Analysis and Calorimetry》2009,98(1):331-335
In many areas of scientific research and development, for example in the pharmaceutical industry, it is important to prepare
and to characterize crystals of pure organic compounds which are thermodynamically stable. The formation of crystals from
the gas phase is technically less straightforward than crystallisation from solution, but sublimation techniques can have
several important features. In the present paper we report the design and testing of a novel apparatus for small scale sublimation
and fractional deposition of crystals. The instrument has been developed with special reference to the needs in the pharmaceutical
industry. A few mg of the samples are enclosed, under reduced pressure, in thin-walled glass tubes, along which a well defined
temperature gradient can be formed. During an experiment the substance will sublime from the hot end of the glass tube and
crystals will be deposited along the temperature gradient. The applicability of the instrument has been verified by experiments
with several test compounds. Results from experiments with carbamazepine, are reported in some detail. Carbamazepine single
crystals of high quality were obtained and the transition temperature between the triclinic (Form I) and the monoclinic (Form
III) crystal modifications agreed with literature values. 相似文献
326.
We introduce a model of interacting singularities of Navier–Stokes equations, named pinçons. They follow non-equilibrium dynamics, obtained by the condition that the velocity field around these singularities obeys locally Navier–Stokes equations. This model can be seen as a generalization of the vorton model of Novikov that was derived for the Euler equations. When immersed in a regular field, the pinçons are further transported and sheared by the regular field, while applying a stress onto the regular field that becomes dominant at a scale that is smaller than the Kolmogorov length. We apply this model to compute the motion of a pair of pinçons. A pinçon dipole is intrinsically repelling and the pinçons generically run away from each other in the early stage of their interaction. At a late time, the dissipation takes over, and the dipole dies over a viscous time scale. In the presence of a stochastic forcing, the dipole tends to orientate itself so that its components are perpendicular to their separation, and it can then follow during a transient time a near out-of-equilibrium state, with forcing balancing dissipation. In the general case where the pinçons have arbitrary intensity and orientation, we observe three generic dynamics in the early stage: one collapse with infinite dissipation, and two expansion modes, the dipolar anti-aligned runaway and an anisotropic aligned runaway. The collapse of a pair of pinçons follows several characteristics of the reconnection between two vortex rings, including the scaling of the distance between the two components, following Leray scaling . 相似文献
327.
Dr. Suresh Moorthy Dr. Hugues Lambert Dr. Neetha Mohan Thomas Schwarzlose Prof. Werner M. Nau Dr. Elina Kalenius Dr. Tung-Chun Lee 《Angewandte Chemie (International ed. in English)》2023,62(32):e202303491
In the gas phase, thermal activation of supramolecular assemblies such as host–guest complexes leads commonly to noncovalent dissociation into the individual components. Chemical reactions, for example of encapsulated guest molecules, are only found in exceptional cases. As observed by mass spectrometry, when 1-amino-methyl-2,3-diazabicyclo[2.2.2]oct-2-ene (DBOA) is complexed by the macrocycle β-cyclodextrin, its protonated complex undergoes collision-induced dissociation into its components, the conventional reaction pathway. Inside the macrocyclic cavity of cucurbit[7]uril (CB7), a competitive chemical reaction of monoprotonated DBOA takes place upon thermal activation, namely a stepwise homolytic covalent bond cleavage with the elimination of N2, while the doubly protonated CB7⋅DBOA complex undergoes an inner-phase elimination of ethylene, a concerted, electrocyclic ring-opening reaction. These chemical reaction pathways stand in contrast to the gas-phase chemistry of uncomplexed monoprotonated DBOA, for which an elimination of NH3 predominates upon collision-induced activation, as a heterolytic bond cleavage reaction. The combined results, which can be rationalized in terms of organic-chemical reaction mechanisms and density-function theoretical calculations, demonstrate that chemical reactions in the gas phase can be steered chemoselectively through noncovalent interactions. 相似文献
328.
Marieta Constantin Cristofer I. Simionescu Adrian Carpov Eric Samain Hugues Driguez 《Macromolecular rapid communications》1999,20(2):91-94
Copolymers of poly(3‐hydroxyoctanoates) (PHAs) containing repeating units with unsaturated or brominated pendant side chains have been obtained from cultures of Pseudomonas oleovorans grown on mixtures of octanoic acid and undecenoic acid or 11‐bromoundecanoic acid as carbon sources. These polymers, bearing reactive functionalities, have been used to graft acetylated maltosyl units either by anti‐Markovnikov addition to the double bond or SN2 substitution of the halogen. De‐O‐acetylation of the sugar moieties yielded PHAs with new properties. 相似文献
329.
We sketch algebraic and trajectory related controllability results for systems described by boundary coupled partial differential equations of second order in one spatial dimension. Those systems may be described by modules over a Bézout domain ℛℚ generated by particular Mikusinski–Operators with compact support. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献