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991.
Raphaël Côte Carlos E. Kenig Frank Merle 《Communications in Mathematical Physics》2008,284(1):203-225
Given g and f = gg′, we consider solutions to the following non linear wave equation :
Under suitable assumptions on g, this equation admits non-constant stationary solutions : we denote Q one with least energy. We characterize completely the behavior as time goes to ±∞ of solutions (u, u
t
) corresponding to data with energy less than or equal to the energy of Q : either it is (Q, 0) up to scaling, or it scatters in the energy space.
Our results include the cases of the 2 dimensional corotational wave map system, with target , in the critical energy space, as well as the 4 dimensional, radially symmetric Yang-Mills fields on Minkowski space, in
the critical energy space.
Centre National de la Recherche Scientifique.
Institut des Hautes études Scientifiques.
The work of R.C. and F.M. has been supported in part by ANR grant ONDE NONLIN, and the work of C.E.K. has been supported in
part by NSF. 相似文献
992.
Rodrigo Vargas 《Journal of statistical physics》2008,133(3):491-511
We establish the existence of two weak coupling regime effective dynamics for an open quantum system of repeated interactions
(vanishing strength and individual interaction duration, respectively). This generalizes known results (Attal and Joye in
J. Stat. Phys. 126:1241–1283, 2007) in that the von Neumann algebras describing the system and the chain element may not be of finite type. Then (but now assuming
that the small system is of finite type), we prove that both effective dynamics capture the long-term behavior of the system:
existence of a unique asymptotic state for them implies the same property for the respective exact dynamics—provided that
the perturbation parameter is sufficiently small. The zero-th order term in a power series expansion in the perturbation parameter
of such an asymptotic state is given by the asymptotic state of the effective dynamics. We conclude by working out the case
in which the small system and the chain element are spins.
Dedicated to Mariana Huerta.
This work was partially funded by Nucleus Millennium Information and Randomness P04-069-F. 相似文献
993.
We report the results of the DC magnetization, neutron powder diffraction and neutron depolarization studies on the spin-chain
compounds Ca3Co2–x
Fe
x
O6 (x = 0, 0.1, 0.2 and 0.4). Rietveld refinement of neutron powder diffraction patterns at room temperature confirms the single-phase
formation for all the compounds in rhombohedral structure with space group Rc. Rietveld refinement also confirms that Fe was doped at the trigonal prism site, 6a (0, 0, 1/4) of Co. The high temperature
magnetic susceptibility obeys the Curie-Weiss law; the value of the paramagnetic Curie temperature (θ
p) decreases as the concentration of iron increases and it becomes negative for x = 0.4. No extra Bragg peak as well as no observable enhancement in the intensity of the fundamental (nuclear) Bragg peaks
has been observed in the neutron diffraction patterns down to 30 K. No depolarization of neutron beam has been observed down
to 3 K confirming the absence of ferro- or ferrimagnetic-like correlation.
相似文献
994.
995.
M. Idrish Miah 《Optical and Quantum Electronics》2008,40(13):1033-1042
We report the experimental observation of the pure anomalous Hall effect (AHE) in nonmagnetic zinc-blende semiconductors without
application of the external magnetic fields. The AHE without any contribution from the ordinary Hall current originates from
nonequilibrium magnetization induced by spin-polarized electrons generated by the circularly polarized light (σ). We measure the pure AHE as a function of the external bias, crystal temperature and pumping σ-photon energy. The results of their dependences are discussed. 相似文献
996.
Alexander J. Silenko 《The European Physical Journal C - Particles and Fields》2008,57(3):595-599
The exact solution of the Corben–Schwinger equations is obtained for spin-1 particles without an anomalous magnetic moment
in a uniform magnetic field. The exact Hamiltonian in the Foldy–Wouthuysen representation is derived. The conservation of
projections of the polarization operator onto four directions is proved. The approximate conservation of projections of this
operator onto the horizontal axes of the cylindrical coordinate system is established. For spin-1 particles with the anomalous
magnetic moment, the Hamiltonian in the Foldy–Wouthuysen representation is deduced within first order terms in the Planck
constant. Dynamics of spin-1 particles with the anomalous magnetic moment and their spins in the strong uniform magnetic field
are calculated. 相似文献
997.
Background
Previous reports of inhibition in the neocortex suggest that inhibition is mediated predominantly through GABAA receptors exhibiting fast kinetics. Within the hippocampus, it has been shown that GABAA responses can take the form of either fast or slow response kinetics. Our findings indicate, for the first time, that the neocortex displays synaptic responses with slow GABAA receptor mediated inhibitory postsynaptic currents (IPSCs). These IPSCs are kinetically and pharmacologically similar to responses found in the hippocampus, although the anatomical specificity of evoked responses is unique from hippocampus. Spontaneous slow GABAA IPSCs were recorded from both pyramidal and inhibitory neurons in rat visual cortex. 相似文献998.
Craig F Ferris Tara Stolberg Praveen Kulkarni Murali Murugavel Robert Blanchard D Caroline Blanchard Marcelo Febo Mathew Brevard Neal G Simon 《BMC neuroscience》2008,9(1):111
Background
With the advent of functional magnetic resonance imaging (fMRI) in awake animals it is possible to resolve patterns of neuronal activity across the entire brain with high spatial and temporal resolution. Synchronized changes in neuronal activity across multiple brain areas can be viewed as functional neuroanatomical circuits coordinating the thoughts, memories and emotions for particular behaviors. To this end, fMRI in conscious rats combined with 3D computational analysis was used to identifying the putative distributed neural circuit involved in aggressive motivation and how this circuit is affected by drugs that block aggressive behavior. 相似文献999.
Narcis Ghisovan Abdellatif Nemri Svetlana Shumikhina Stephane Molotchnikoff 《BMC neuroscience》2008,9(1):60
Background
Visual neurons respond essentially to luminance variations occurring within their receptive fields. In primary visual cortex, each neuron is a filter for stimulus features such as orientation, motion direction and velocity, with the appropriate combination of features eliciting maximal firing rate. Temporal correlation of spike trains was proposed as a potential code for linking the neuronal responses evoked by various features of a same object. In the present study, synchrony strength was measured between cells following an adaptation protocol (prolonged exposure to a non-preferred stimulus) which induce plasticity of neurons' orientation preference. 相似文献1000.