11,979 research outputs found
Hawking radiation, W-infinity algebra and trace anomalies
We apply the "trace anomaly method" to the calculation of moments of the
Hawking radiation of a Schwarzschild black hole. We show that they can be
explained as the fluxes of chiral currents forming a W-infinity algebra. Then
we construct the covariant version of these currents and verify that up to
order 6 they are not affected by any trace anomaly. Using cohomological methods
we show that actually, for the fourth order current, no trace anomalies can
exist. The results reported here are strictly valid in two dimensions.Comment: 22 pages, typos correcte
Hawking Fluxes, Back reaction and Covariant Anomalies
Starting from the chiral covariant effective action approach of Banerjee and
Kulkarni [Phys. Lett. B 659, 827(2008)], we provide a derivation of the Hawking
radiation from a charged black hole in the presence of gravitational back
reaction. The modified expressions for charge and energy flux, due to effect of
one loop back reaction are obtained.Comment: 6 pages, no figures, minor changes and references added, to appear in
Classical and Quantum Gravit
Hawking radiation from the Schwarzschild black hole with a global monopole via gravitational anomaly
Hawking flux from the Schwarzschild black hole with a global monopole is
obtained by using Robinson and Wilczek's method. Adopting a dimension reduction
technique, the effective quantum field in the (3+1)--dimensional global
monopole background can be described by an infinite collection of the
(1+1)--dimensional massless fields if neglecting the ingoing modes near the
horizon, where the gravitational anomaly can be cancelled by the
(1+1)--dimensional black body radiation at the Hawking temperature.Comment: 4 pages, no figure, 3nd revsion with one reference adde
Anomalies and Hawking radiation from the Reissner-Nordstr\"om black hole with a global monopole
We extend the work by S. Iso, H. Umetsu and F. Wilczek [Phys. Rev. Lett. 96
(2006) 151302] to derive the Hawking flux via gauge and gravitational anomalies
of a most general two-dimensional non-extremal black hole space-time with the
determinant of its diagonal metric differing from the unity () and use it to investigate Hawking radiation from the Reissner-Nordstrom
black hole with a global monopole by requiring the cancellation of anomalies at
the horizon. It is shown that the compensating energy momentum and gauge fluxes
required to cancel gravitational and gauge anomalies at the horizon are
precisely equivalent to the -dimensional thermal fluxes associated with
Hawking radiation emanating from the horizon at the Hawking temperature. These
fluxes are universally determined by the value of anomalies at the horizon.Comment: 18 pages, 0 figure. 1 footnote and 4 new reference adde
Effect of Chinese medical herbs- burn liniment on deep second degree burn in rats
Background: Burn Liniment (BL) is a popular traditional Chinese medicine formula consisting five herbal medicines (Flos Lonicerae, Rhizoma Polygoni Cuspidati, Pericarpium Granati,Terminalia chebula Retz. and Galla Chinensis), that has been used in China for centuries to cure burn. This study investigated the healing effect of BL on deep second degree burn wounds in rats.Materials and methods: The animals were divided into four groups including control group, model group,1% silver sulfadiazine (SSD) group and BL group. On days 0,3,7,14 and 21,animal weight, wound area as well as histo-pathological observations of the skin were evaluated in different groups. Serum anti-intercellular adhesion molecule 1(ICAM-1), IL-10 levels and myeloperoxidase (MPO) activity were measured on the 21st day. HPLC chromatography of BL was prepared and concentrations of active constituents were determined. Antibacterial test and toxicological test were also performed.Results: The average wound area of BL treatment group was also significantly smaller than model control rats on days 14 and 21. Serum anti-intercellular adhesion molecule 1(ICAM-1) levels and myeloperoxidase (MPO) activity of BL group decreased significantly than in model rats on day 21 while IL-10 level of BL group increased remarkably than in model rats on the 21st day, showing that BL has strong anti-inflammatory activity on burned rats. The histological studies indicated that inflammatory cells disappeared significantly and were replaced by new granulation tissue, and epithelialization progressed quickly and was treated with BL on the 21st day. Meanwhile, HPLC chromatography of BL was prepared and concentration of Chlorogenic acid, Polydatin and Gallic acid from BL were determined. Antibacterial test revealed that the MIC of BL on Staphyloccocus aureus, Pseudomonas aeruginosa and Escherichia coli were 1.56, 6.25 and 1.56 mg·mL-1 respectively. Toxicological test showed that BL does not induce skin irritation or sensitivity signs and has no acute toxicity reaction.Conclusions: Our study revealed that BL could enhance cutaneous burn wound healing effectively. It also showed strong anti-inflammatory and antibacterial activity in rats.Keywords: Burn Liniment; Deep second degree; Burn wound; Anti-inflammatory; Antibacterial; Toxicological tes
Three-body unitary coupled-channel approach to radiative decays and
Recent BESIII data on radiative decays from
samples should significantly advance our understanding of the controversial
nature of . This motivates us to develop a three-body unitary
coupled-channel model for radiative decays to three-meson final states
of any partial wave (). Basic building blocks of the model are bare
resonance states such as and , and ,
, and two-body interactions that generate resonances such
as , , and . This model reasonably fits
Dalitz plot pseudo data generated from the BESIII's
amplitude for . The experimental
branching ratios of and
relative to that of are simultaneously fitted. Our amplitude is analytically
continued to find three poles, two of which correspond to on
different Riemann sheets of the channel, and the third one for
. This is the first pole determination of and,
furthermore, the first-ever pole determination from analyzing experimental
Dalitz plot distributions with a manifestly three-body unitary coupled-channel
framework. Process-dependent , , and
lineshapes of ,
, and are predicted, and are in
reasonable agreement with data. A triangle singularity is shown to play a
crucial role to cause the large isospin violation of
.Comment: 23 pages, 19 figures; (v2) minor changes, published versio
Back reaction, covariant anomaly and effective action
In the presence of back reaction, we first produce the one-loop corrections
for the event horizon and Hawking temperature of the Reissner-Nordstr\"om black
hole. Then, based on the covariant anomaly cancelation method and the effective
action technique, the modified expressions for the fluxes of gauge current and
energy momentum tensor, due to the effect of back reaction, are obtained. The
results are consistent with the Hawking fluxes of a (1+1)-dimensional blackbody
at the temperature with quantum corrections, thus confirming the robustness of
the covariant anomaly cancelation method and the effective action technique for
black holes with back reaction.Comment: 17 page
Fermions tunnelling from the charged dilatonic black holes
Kerner and Mann's recent work shows that, for an uncharged and non-rotating
black hole, its Hawking temperature can be exactly derived by fermions
tunnelling from its horizons. In this paper, our main work is to improve the
analysis to deal with charged fermion tunnelling from the general dilatonic
black holes, specifically including the charged, spherically symmetric
dilatonic black hole, the rotating Einstein-Maxwell-Dilaton-Axion (EMDA) black
hole and the rotating Kaluza-Klein (KK) black hole. As a result, the correct
Hawking temperatures are well recovered by charged fermions tunnelling from
these black holes.Comment: 16 pages, revised version to appear in Class. Quant. Gra
Enhancing Transport Efficiency by Hybrid Routing Strategy
Traffic is essential for many dynamic processes on real networks, such as
internet and urban traffic systems. The transport efficiency of the traffic
system can be improved by taking full advantage of the resources in the system.
In this paper, we propose a dual-strategy routing model for network traffic
system, to realize the plenary utility of the whole network. The packets are
delivered according to different "efficient routing strategies" [Yan, et al,
Phys. Rev. E 73, 046108 (2006)]. We introduce the accumulate rate of packets,
{\eta} to measure the performance of traffic system in the congested phase, and
propose the so-called equivalent generation rate of packet to analyze the
jamming processes. From analytical and numerical results, we find that, for
suitable selection of strategies, the dual- strategy system performs better
than the single-strategy system in a broad region of strategy mixing ratio. The
analytical solution to the jamming processes is verified by estimating the
number of jammed nodes, which coincides well with the result from simulation.Comment: 6 pages, 3 figure
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