8,142 research outputs found
Pre-Equilibrium Evolution of QCD Plasma :An Appraisal
We discuss, in this review, the existing models for the production of QGP in
Relativistic Heavy Ion Collisions. We shall try to give a brief description of
the models available for the pre-equilibrium production of QGP, ranging from
soft process dominated QCD regime to the pQCD dominated regime. We also present
the estimates for the initial energy density, the temperature and the
thermalisation time -- available from each of these studies. Finally, we shall
address the questions regarding thermalisation, color equilibration and
chemical equilibration of the produced QGP in different experimental
facilities.Comment: 15 pages, Latex, 3 figure
Renormalisation Group Improved Thermal Coupling Constant In An External Field
Starting from renormalised Effective Lagrangian, in the presence of an
external Chromo-Electric field at finite temperature, the expression for
thermal coupling constant () as a function of
temperature and external field is derived, using finite temperature two
parameter renormalisation group equation of Matsumoto, Nakano and Umezawa. For
some values of the parameters, the coupling constant is seen to be approaching
a value .Comment: 12 pages, Latex, 2 figure
Controlled engineering of spin polarized transport properties in a zigzag graphene nanojunction
We investigate a novel way to manipulate the spin polarized transmission in a
two terminal zigzag graphene nanoribbon in presence of Rashba spin-orbit (SO)
interaction with circular shaped cavity engraved into it. A usual technique to
control the spin polarized transport behaviour of a nanoribbon can be achieved
by tuning the strength of the SO coupling, while we show that an efficient
engineering of the spin polarized transport properties can also be done via
cavities of different radii engraved in the nanoribbon. Simplicity of the
technique in creating such cavities in the experiments renders an additional
handle to explore transport properties as a function of the location of the
cavity in the nanoribbon. Further, a systematic assessment of the interplay of
the Rashba interaction and the dimensions of the nanoribbon is presented. These
results should provide useful input to the spintronic behaviour of such
devices. In addition to the spin polarization, we have also included an
interesting discussion on the charge transmission properties of the nanoribbon,
where, in absence of any SO interaction a metal-insulator transition induced by
the presence of a cavity is observed.Comment: 7 pages, 9 figures (Accepted in Europhysics Letters
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Large-scale changes in cortical dynamics triggered by repetitive somatosensory electrical stimulation.
BackgroundRepetitive somatosensory electrical stimulation (SES) of forelimb peripheral nerves is a promising therapy; studies have shown that SES can improve motor function in stroke subjects with chronic deficits. However, little is known about how SES can directly modulate neural dynamics. Past studies using SES have primarily used noninvasive methods in human subjects. Here we used electrophysiological recordings from the rodent primary motor cortex (M1) to assess how SES affects neural dynamics at the level of single neurons as well as at the level of mesoscale dynamics.MethodsWe performed acute extracellular recordings in 7 intact adult Long Evans rats under ketamine-xylazine anesthesia while they received transcutaneous SES. We recorded single unit spiking and local field potentials (LFP) in the M1 contralateral to the stimulated arm. We then compared neural firing rate, spike-field coherence (SFC), and power spectral density (PSD) before and after stimulation.ResultsFollowing SES, the firing rate of a majority of neurons changed significantly from their respective baseline values. There was, however, a diversity of responses; some neurons increased while others decreased their firing rates. Interestingly, SFC, a measure of how a neuron's firing is coupled to mesoscale oscillatory dynamics, increased specifically in the δ-band, also known as the low frequency band (0.3- 4 Hz). This increase appeared to be driven by a change in the phase-locking of broad-spiking, putative pyramidal neurons. These changes in the low frequency range occurred without a significant change in the overall PSD.ConclusionsRepetitive SES significantly and persistently altered the local cortical dynamics of M1 neurons, changing both firing rates as well as the SFC magnitude in the δ-band. Thus, SES altered the neural firing and coupling to ongoing mesoscale dynamics. Our study provides evidence that SES can directly modulate cortical dynamics
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