28,732 research outputs found
Probing the QCD Critical Point with Higher Moments of Net-proton Multiplicity Distributions
Higher moments of event-by-event net-proton multiplicity distributions are
applied to search for the QCD critical point in the heavy ion collisions. It
has been demonstrated that higher moments as well as moment products are
sensitive to the correlation length and directly connected to the thermodynamic
susceptibilities computed in the Lattice QCD and Hadron Resonance Gas (HRG)
model. In this paper, we will present measurements for kurtosis (),
skewness () and variance () of net-proton multiplicity
distributions at the mid-rapidity () and GeV/ for
Au+Au collisions at =19.6, 39, 62.4, 130 and 200 GeV, Cu+Cu
collisions at =22.4, 62.4 and 200 GeV, d+Au collisions at
=200 GeV and p+p collisions at =62.4 and 200 GeV.
The moment products and of net-proton
distributions, which are related to volume independent baryon number
susceptibility ratio, are compared to the Lattice QCD and HRG model
calculations. The and of net-proton
distributions are consistent with Lattice QCD and HRG model calculations at
high energy, which support the thermalization of the colliding system.
Deviations of and for the Au+Au collisions at
low energies from HRG model calculations are also observed.Comment: 10 pages, 8 figures, Proceedings of 27th Winter Workshon on Nuclear
Dynamics. Feb. 6-13 (2011
Exotic mesons from quantum chromodynamics with improved gluon and quark actions on the anisotropic lattice
Hybrid (exotic) mesons, which are important predictions of quantum
chromodynamics (QCD), are states of quarks and anti-quarks bound by excited
gluons. First principle lattice study of such states would help us understand
the role of ``dynamical'' color in low energy QCD and provide valuable
information for experimental search for these new particles. In this paper, we
apply both improved gluon and quark actions to the hybrid mesons, which might
be much more efficient than the previous works in reducing lattice spacing
error and finite volume effect. Quenched simulations were done at
and on a anisotropic lattice using our PC cluster. We
obtain MeV for the mass of the hybrid meson
in the light quark sector, and Mev in the
charm quark sector; the mass splitting between the hybrid meson in the charm quark sector and the spin averaged S-wave charmonium mass
is estimated to be MeV. As a byproduct, we obtain MeV for the mass of a P-wave or
meson and MeV for the mass of a P-wave meson, which are comparable to their experimental value 1426 MeV for the
meson. The first error is statistical, and the second one is
systematical. The mixing of the hybrid meson with a four quark state is also
discussed.Comment: 12 pages, 3 figures. Published versio
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State-of-the-art on research and applications of machine learning in the building life cycle
Fueled by big data, powerful and affordable computing resources, and advanced algorithms, machine learning has been explored and applied to buildings research for the past decades and has demonstrated its potential to enhance building performance. This study systematically surveyed how machine learning has been applied at different stages of building life cycle. By conducting a literature search on the Web of Knowledge platform, we found 9579 papers in this field and selected 153 papers for an in-depth review. The number of published papers is increasing year by year, with a focus on building design, operation, and control. However, no study was found using machine learning in building commissioning. There are successful pilot studies on fault detection and diagnosis of HVAC equipment and systems, load prediction, energy baseline estimate, load shape clustering, occupancy prediction, and learning occupant behaviors and energy use patterns. None of the existing studies were adopted broadly by the building industry, due to common challenges including (1) lack of large scale labeled data to train and validate the model, (2) lack of model transferability, which limits a model trained with one data-rich building to be used in another building with limited data, (3) lack of strong justification of costs and benefits of deploying machine learning, and (4) the performance might not be reliable and robust for the stated goals, as the method might work for some buildings but could not be generalized to others. Findings from the study can inform future machine learning research to improve occupant comfort, energy efficiency, demand flexibility, and resilience of buildings, as well as to inspire young researchers in the field to explore multidisciplinary approaches that integrate building science, computing science, data science, and social science
Transmutation prospect of long-lived nuclear waste induced by high-charge electron beam from laser plasma accelerator
Photo-transmutation of long-lived nuclear waste induced by high-charge
relativistic electron beam (e-beam) from laser plasma accelerator is
demonstrated. Collimated relativistic e-beam with a high charge of
approximately 100 nC is produced from high-intensity laser interaction with
near-critical-density (NCD) plasma. Such e-beam impinges on a high-Z convertor
and then radiates energetic bremsstrahlung photons with flux approaching
10^{11} per laser shot. Taking long-lived radionuclide ^{126}Sn as an example,
the resulting transmutation reaction yield is the order of 10^{9} per laser
shot, which is two orders of magnitude higher than obtained from previous
studies. It is found that at lower densities, tightly focused laser irradiating
relatively longer NCD plasmas can effectively enhance the transmutation
efficiency. Furthermore, the photo-transmutation is generalized by considering
mixed-nuclide waste samples, which suggests that the laser-accelerated
high-charge e-beam could be an efficient tool to transmute long-lived nuclear
waste.Comment: 13 pages, 8 figures, it has been submitted to Physics of Plasm
Improved three-dimensional color-gradient lattice Boltzmann model for immiscible multiphase flows
In this paper, an improved three-dimensional color-gradient lattice Boltzmann
(LB) model is proposed for simulating immiscible multiphase flows. Compared
with the previous three-dimensional color-gradient LB models, which suffer from
the lack of Galilean invariance and considerable numerical errors in many cases
owing to the error terms in the recovered macroscopic equations, the present
model eliminates the error terms and therefore improves the numerical accuracy
and enhances the Galilean invariance. To validate the proposed model, numerical
simulation are performed. First, the test of a moving droplet in a uniform flow
field is employed to verify the Galilean invariance of the improved model.
Subsequently, numerical simulations are carried out for the layered two-phase
flow and three-dimensional Rayleigh-Taylor instability. It is shown that, using
the improved model, the numerical accuracy can be significantly improved in
comparison with the color-gradient LB model without the improvements. Finally,
the capability of the improved color-gradient LB model for simulating dynamic
multiphase flows at a relatively large density ratio is demonstrated via the
simulation of droplet impact on a solid surface.Comment: 9 Figure
Tick-borne encephalitis virus induces chemokine RANTES expression via activation of IRF-3 pathway.
BACKGROUND: Tick-borne encephalitis virus (TBEV) is one of the most important flaviviruses that targets the central nervous system (CNS) and causes encephalitides in humans. Although neuroinflammatory mechanisms may contribute to brain tissue destruction, the induction pathways and potential roles of specific chemokines in TBEV-mediated neurological disease are poorly understood. METHODS: BALB/c mice were intracerebrally injected with TBEV, followed by evaluation of chemokine and cytokine profiles using protein array analysis. The virus-infected mice were treated with the CC chemokine antagonist Met-RANTES or anti-RANTES mAb to determine the role of RANTES in affecting TBEV-induced neurological disease. The underlying signaling mechanisms were delineated using RANTES promoter luciferase reporter assay, siRNA-mediated knockdown, and pharmacological inhibitors in human brain-derived cell culture models. RESULTS: In a mouse model, pathological features including marked inflammatory cell infiltrates were observed in brain sections, which correlated with a robust up-regulation of RANTES within the brain but not in peripheral tissues and sera. Antagonizing RANTES within CNS extended the survival of mice and reduced accumulation of infiltrating cells in the brain after TBEV infection. Through in vitro studies, we show that virus infection up-regulated RANTES production at both mRNA and protein levels in human brain-derived cell lines and primary progenitor-derived astrocytes. Furthermore, IRF-3 pathway appeared to be essential for TBEV-induced RANTES production. Site mutation of an IRF-3-binding motif abrogated the RANTES promoter activity in virus-infected brain cells. Moreover, IRF-3 was activated upon TBEV infection as evidenced by phosphorylation of TBK1 and IRF-3, while blockade of IRF-3 activation drastically reduced virus-induced RANTES expression. CONCLUSIONS: Our findings together provide insights into the molecular mechanism underlying RANTES production induced by TBEV, highlighting its potential importance in the process of neuroinflammatory responses to TBEV infection
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