13,062 research outputs found
Chiral Magnetic Effect and Chiral Phase Transition
We study the influence of the chiral phase transition on the chiral magnetic
effect. The azimuthal charge-particle correlations as functions of the
temperature are calculated. It is found that there is a pronounced cusp in the
correlations as the temperature reaches its critical value for the QCD phase
transition. It is predicted that there will be a drastic suppression of the
charge-particle correlations as the collision energy in RHIC decreases to below
a critical value. We show then the azimuthal charge-particle correlations can
be the signal to identify the occurrence of the QCD phase transitions in RHIC
energy scan experiments.Comment: 4 pages, 1 figur
Fluctuations and Correlations of Conserved Charges in QCD at Finite Temperature with Effective Models
We study fluctuations of conserved charges including baryon number, electric
charge, and strangeness as well as the correlations among these conserved
charges in the 2+1 flavor Polyakov--Nambu--Jona-Lasinio model at finite
temperature. The calculated results are compared with those obtained from
recent lattice calculations performed with an improved staggered fermion action
at two values of the lattice cutoff with almost physical up and down quark
masses and a physical value for the strange quark mass. We find that our
calculated results are well consistent with those obtained in lattice
calculations except for some quantitative differences for fluctuations related
with strange quarks. Our calculations indicate that there is a pronounced cusp
in the ratio of the quartic to quadratic fluctuations of baryon number, i.e.
, at the critical temperature during the phase
transition, which confirms that is a useful probe
of the deconfinement and chiral phase transition.Comment: 24 pages, 11 figures; final version published in Phys. Rev.
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Experimental and Numerical Investigation on Progressive Collapse Resistance of Post-tensioned Precast Concrete Beam-Column Sub-assemblages
In this paper, four 1/2 scaled precast concrete (PC) beam-column sub-assemblages with high performance connection were tested under push-down loading procedure to study the load resisting mechanism of PC frames subjected to different column removal scenarios. The parameters investigated include the location of column removal and effective prestress in tendons. The test results indicated that the failure modes of unbonded post-tensioned precast concrete (PTPC) frames were different from that of reinforced concrete (RC) frames: no cracks formed in the beams and wide opening formed near the beam to column interfaces. For specimens without overhanging beams, the failure of side column was eccentric compression failure. Moreover, the load resisting mechanisms in PC frames were significantly different from that of RC frames: the compressive arch action (CAA) developed in concrete during column removal was mainly due to actively applied pre-compressive stress in the concrete; CAA will not vanish when severe crush in concrete occurred. Thus, it may provide negative contribution for load resistance when the displacement exceeds one-beam depth; the tensile force developed in the tendons could provide catenary action from the beginning of the test. Moreover, to deeper understand the behavior of tested specimens, numerical analyses were carried out. The effects of concrete strength, axial compression ratio at side columns, and loading approaches on the behavior of the sub-assemblages were also investigated based on validated numerical analysis
Modulation of Neurally Mediated Vasodepression and Bradycardia by Electroacupuncture through Opioids in Nucleus Tractus Solitarius.
Stimulation of vagal afferent endings with intravenous phenylbiguanide (PBG) causes both bradycardia and vasodepression, simulating neurally mediated syncope. Activation of µ-opioid receptors in the nucleus tractus solitarius (NTS) increases blood pressure. Electroacupuncture (EA) stimulation of somatosensory nerves underneath acupoints P5-6, ST36-37, LI6-7 or G37-39 selectively but differentially modulates sympathoexcitatory responses. We therefore hypothesized that EA-stimulation at P5-6 or ST36-37, but not LI6-7 or G37-39 acupoints, inhibits the bradycardia and vasodepression through a µ-opioid receptor mechanism in the NTS. We observed that stimulation at acupoints P5-6 and ST36-37 overlying the deep somatosensory nerves and LI6-7 and G37-39 overlying cutaneous nerves differentially evoked NTS neural activity in anesthetized and ventilated animals. Thirty-min of EA-stimulation at P5-6 or ST36-37 reduced the depressor and bradycardia responses to PBG while EA at LI6-7 or G37-39 did not. Congruent with the hemodynamic responses, EA at P5-6 and ST36-37, but not at LI6-7 and G37-39, reduced vagally evoked activity of cardiovascular NTS cells. Finally, opioid receptor blockade in the NTS with naloxone or a specific μ-receptor antagonist reversed P5-6 EA-inhibition of the depressor, bradycardia and vagally evoked NTS activity. These data suggest that point specific EA stimulation inhibits PBG-induced vasodepression and bradycardia responses through a μ-opioid mechanism in the NTS
Spin Hall effects for cold atoms in a light induced gauge potential
We propose an experimental scheme to observe spin Hall effects with cold
atoms in a light induced gauge potential. Under an appropriate configuration,
the cold atoms moving in a spatially varying laser field experience an
effective spin-dependent gauge potential. Through numerical simulation, we
demonstrate that such a gauge field leads to observable spin Hall currents
under realistic conditions. We also discuss the quantum spin Hall state in an
optical lattice.Comment: 4 pages; The published versio
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