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991.
Armando Valenzuela Peraza David Calderón Guzmán Norma Osnaya Brizuela Maribel Ortiz Herrera Hugo Juárez Olguín Miroslava Lindoro Silva Belén Juárez Tapia Gerardo Barragán Mejía 《BMC neuroscience》2018,19(1):71
Background
Neurological disorders suggest that the excitotoxicity involves a drastic increase in intracellular Ca2+ concentrations and the formation of reactive oxygen species. The presence of these free radicals may also affect the dopaminergic system. The aim of this work was to determine if riboflavin (B2) and pyridoxine (B6) provide protection to the brain against free radicals generated by 3-nitropropionic acid (3-NPA) by measuring the levels of dopamine (DA) and selected oxidative stress markers.Methods
Male Fisher rats were grouped (n?=?6) and treated as follows: group 1, control (NaCl 0.9%); group 2, 3-NPA (20 mg/kg); group 3, B2 (10 mg/kg); group 4, B2 (10 mg/kg)?+?3-NPA (20 mg/kg); group 5, B6 (10 mg/kg) and group 6, B6?+?3-NPA. All treatments were administered every 24 h for 5 days by intraperitoneal route. After sacrifice, the brain was obtained to measure DA, GSH, and lipid peroxidation, Ca2+, Mg2+, ATPase and H2O2.Main findings
Levels of dopamine increased in cortex, striatum and cerebellum/medulla oblongata of animals that received 3-NPA alone. The lipid peroxidation increased in cortex, striatum, and cerebellum/medulla oblongata, of animals treated with B2 vitamin alone. ATPase dependent on Ca+2, Mg+2 and H2O2 increased in all regions of animals that received 3-NPA alone.Conclusion
The results confirm the capacity of 3-NPA to generate oxidative stress. Besides, the study suggests that B2 or B6 vitamins restored the levels of DA and reduced oxidative stress in brain of rats. We believe that these results would help in the study of neurodegenerative diseases.992.
Motivated by interest in the geometry of high intensity events of turbulent flows, we examine the spatial correlation functions of sets where turbulent events are particularly intense. These sets are defined using indicator functions on excursion and iso-value sets. Their geometric scaling properties are analysed by examining possible power-law decay of their radial correlation function. We apply the analysis to enstrophy, dissipation and velocity gradient invariants Q and R and their joint spatial distributions, using data from a direct numerical simulation of isotropic turbulence at Reλ ≈ 430. While no fractal scaling is found in the inertial range using box-counting in the finite Reynolds number flow considered here, power-law scaling in the inertial range is found in the radial correlation functions. Thus, a geometric characterisation in terms of these sets’ correlation dimension is possible. Strong dependence on the enstrophy and dissipation threshold is found, consistent with multifractal behaviour. Nevertheless, the lack of scaling of the box-counting analysis precludes direct quantitative comparisons with earlier work based on multifractal formalism. Surprising trends, such as a lower correlation dimension for strong dissipation events compared to strong enstrophy events, are observed and interpreted in terms of spatial coherence of vortices in the flow. 相似文献
993.
Chabé J Lignier H Cavalcante H Delande D Szriftgiser P Garreau JC 《Physical review letters》2006,97(26):264101
We study the destruction of dynamical localization experimentally observed in an atomic realization of the kicked rotor by a deterministic Hamiltonian perturbation, with a temporal periodicity incommensurate with the principal driving. We show that the destruction is gradual, with well-defined scaling laws for the various classical and quantum parameters, in sharp contrast to predictions based on the analogy with Anderson localization. 相似文献
994.
van Ingen H Vuister GW Tessari M 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2002,156(2):258-261
Many heteronuclear NMR experiments employ decoupling to collapse the heteronuclear multiplet, using decoupling schemes with a periodic phase modulation like WALTZ, MLEV, or GARP. Because of the periodic nature of these schemes, cycling sidebands are generated, whose intensity can be strongly reduced by decoupling asynchronously. We show that the most common implementation of asynchronous decoupling on modern spectrometers is such that the cycling sidebands are subjected to a periodic modulation. For multidimensional experiments, this results in ridges that can seriously compromise the quality of the spectrum. Based on our model, the artifact in a 2D [(1)H]-(15)N NOE equilibrium experiment is simulated and it is shown that the artifact can be prevented by using synchronous decoupling. 相似文献
995.
Controllability of a system of parabolic equations with non-diagonal diffusion matrix 总被引:1,自引:0,他引:1
In this paper we give a necessary and sufficient algebraic conditionfor the approximate controllability of the following systemof parabolic equations with Dirichlet boundary condition: {zt = D z + b1(x)u1 + ··· + bm(x)um, t 0, z n, z = 0, on where is a sufficiently smooth bounded domain in N, bi L2(;n), the control functions ui L2(0, t1; ); i = 1, 2, ..., mand D is an n x n non-diagonal matrix whose eigenvalues aresemi-simple with positive real part. This algebraic conditionis checkable since it is given in terms of the nj x m matricesDPj and PjB, i.e. Rank [PjBDPjBD2PjB··· Dnj1 PjB]= nj, where PjBu = Pjb1u1 + ··· + Pjbmum. Finally,this result can be applied to those systems of partial differentialequations that can be rewritten as a diffusion system (see deOliveira, 1998). 相似文献
996.
We report for the first time on rich and tunable transport phenomena in closed-packed arrays of PbSe colloidal nanocrystals (NCs) in the form of thin films. As the interdot coupling is increased, the system evolves from an insulating regime dominated by Coulomb blockade to a semiconducting regime, where hopping conduction is the dominant transport mechanism. The observed phenomena can be interpreted using the framework established mainly in the context of transport measurements in metallic quantum dots and disordered semiconductors. 相似文献
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Hugo Tschirky und Walter Hälg 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1966,17(3):486
Ohne Zusammenfassung 相似文献