872 research outputs found

    Analysis of the vertices ρNN\rho NN, ρΣΣ\rho\Sigma\Sigma and ρΞΞ\rho\Xi\Xi with light-cone QCD sum rules

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    In this article, we calculate the strong coupling constants of the ρNN\rho NN, ρΣΣ\rho\Sigma\Sigma and ρΞΞ\rho\Xi\Xi in the framework of the light-cone QCD sum rules approach. The strong coupling constants of the meson-baryon-baryon are the fundamental parameters in the one-boson exchange model which describes the baryon-baryon interactions successfully. The numerical values are in agreement with the existing calculations in part. The electric and magnetic F/(F+D)F/(F+D) ratios deviate from the prediction of the vector meson dominance theory, the SU(3) symmetry breaking effects are very large.Comment: 19 pages, 6 figures, revised version, add more discussions(Correct writing errors

    Tumor necrosis factor–Α contributes to below-level neuropathic pain after spinal cord injury

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    Objective Our objective was to elucidate the mechanisms responsible for below-level pain after partial spinal cord injury (SCI). Methods We used lateral hemisection to model central neuropathic pain and herpes simplex viral (HSV) vector–mediated transfer of the cleaved soluble receptor for tumor necrosis factor–Α (TNF-Α) to evaluate the role of TNF-Α in the pathogenesis of below-level pain. Results We found activation of microglia and increased expression of TNF-Α below the level of the lesion in the lumbar spinal cord after T13 lateral hemisection that correlated with emergence of mechanical allodynia in the hind limbs of rats. Lumbar TNF-Α had an apparent molecular weight of 27kDa, consistent with the full-length transmembrane form of the protein (mTNF-Α). Expression of the p55 TNF soluble receptor (sTNFRs) by HSV-mediated gene transfer resulted in reduced pain behavior and a decreased number of ED1-positive cells, as well as decreased phosphorylation of the p38 MAP kinase (p-p38) and diminished expression of mTNF-Α in the dorsal horn. Interpretation These results suggest that expression of mTNF-Α after injury is related to development of pain, and that reverse signaling through mTNF-Α by sTNFR at that level reduces cellular markers of inflammatory response and pain-related behavior. Ann Neurol 2006;59:843–851Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50655/1/20855_ftp.pd

    Analysis of the X(1835)X(1835) as a baryonium state with Bethe-Salpeter equation

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    In this article, we take the X(1835) as a pseudoscalar baryonium state, and calculate the mass spectrum of the baryon-antibaryon bound states ppˉp\bar{p}, ΣΣˉ\Sigma\bar{\Sigma}, ΞΞˉ\Xi\bar{\Xi}, and ΛΛˉ\Lambda\bar{\Lambda} in the framework of the Bethe-Salpeter equation with a phenomenological potential. The numerical results indicate the ppˉp\bar{p}, ΣΣˉ\Sigma\bar{\Sigma} and ΞΞˉ\Xi\bar{\Xi} bound states maybe exist, and the X(1835)X(1835) can be tentatively identified as the ppˉp\bar{p} bound state.Comment: 7 pages, 1 figure, published versio

    Radiative decays of the (0+,1+)(0^+,1^+) strange-bottom mesons

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    In this article, we assume that the (0+,1+)(0^+,1^+) strange-bottom mesons are the conventional bsˉb\bar{s} mesons, and calculate the electromagnetic coupling constants dd, g1g_1, g2g_2 and g3g_3 using the light-cone QCD sum rules. Then we study the radiative decays Bs0BsγB_{s0}\to B_s^* \gamma, Bs1BsγB_{s1}\to B_s \gamma, Bs1BsγB_{s1}\to B_s^* \gamma and Bs1Bs0γB_{s1}\to B_{s0} \gamma, and observe that the widths are rather narrow. We can search for the (0+,1+)(0^+,1^+) strange-bottom mesons in the invariant Bsπ0B_s \pi^0 and Bsπ0B^*_s \pi^0 mass distributions in the strong decays or in the invariant BsγB_s^*\gamma and BsγB_s\gamma mass distributions in the radiative decays.Comment: 16 pages, 4 figures, revised versio

    Evolutionary prisoner's dilemma game with dynamic preferential selection

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    We study a modified prisoner's dilemma game taking place on two-dimensional disordered square lattices. The players are pure strategists and can either cooperate or defect with their immediate neighbors. In the generations each player update its strategy by following one of the neighboring strategies with a probability dependent on the payoff difference. The neighbor selection obeys a dynamic preferential rule, i.e., the more frequently a neighbor's strategy was adopted by the focal player in the previous rounds, the larger probability it will be chosen to refer to in the subsequent rounds. It is found that cooperation is substantially promoted due to this simple selection mechanism. Corresponding analysis is provided by the investigations of the distribution of players' impact weights, persistence, and as well as correlation function.Comment: 7 pages, 5 figure

    Transitions To the Long-Resident State in coupled chaotic oscillators

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    The behaviors of coupled chaotic oscillators before complete synchronization were investigated. We report three phenomena: (1) The emergence of long-time residence of trajectories besides one of the saddle foci; (2) The tendency that orbits of the two oscillators get close becomes faster with increasing the coupling strength; (3) The diffusion of two oscillator's phase difference is first enhanced and then suppressed. There are exact correspondences among these phenomena. The mechanism of these correspondences is explored. These phenomena uncover the route to synchronization of coupled chaotic oscillators.Comment: 3 pages, 5 figure

    Developments of a 2D Position Sensitive Neutron Detector

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    Chinese Spallation Neutron Source (CSNS), one project of the 12th five-year-plan scheme of China, is under construction in Guangdong province. Three neutron spectrometers will be installed at the first phase of the project, where two-dimensional position sensitive thermal neutron detectors are required. Before the construction of the neutron detector, a prototype of two-dimensional 200 mmx200 mm Multi-wire Proportional Chamber (MWPC) with the flowing gas of Ar/CO2 (90/10) has been constructed and tested with the 55Fe X-Ray using part of the electronics in 2009, which showed a good performance. Following the test in 2009, the neutron detector has been constructed with the complete electronics and filled with the 6atm.3He + 2.5atm.C3H8 gas mixture in 2010. The neutron detector has been primarily tested with an Am/Be source. In this paper, some new developments of the neutron detector including the design of the high pressure chamber, the optimization of the gas purifying system and the gas filling process will be reported. The results and discussion are also presented in this paper.Comment: 5 page

    A study of the inclusion complex formed between cucurbit[8]uril and isonicotinic acid

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    The complexation between cucurbit[8]uril, Q[8], and isonicotinic acid has been studied using 1H NMR spectroscopy, UV–Vis absorption spectroscopy, Raman spectroscopy and single crystal X-ray diffraction. The results revealed that the 2:1 inclusion complex (4-PA)2@Q[8]·25H2O is formed, with two guests simultaneously encapsulated in the hydrophobic cavity; the mean planes of the guests are 3.535 Å apart. Graphical abstract: [Figure not available: see fulltext.

    Reanalysis of the (0^+,1^+) states B_{s0} and B_{s1} with QCD sum rules

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    In this article, we calculate the masses and decay constants of the PP-wave strange-bottomed mesons Bs0B_{s0} and Bs1B_{s1} with the QCD sum rules, and observe that the central values of the masses of the Bs0B_{s0} and Bs1B_{s1} are smaller than the corresponding BKBK and BKB^*K thresholds respectively, the strong decays Bs0BKB_{s0}\to BK and Bs1BKB_{s1}\to B^*K are kinematically forbidden. They can decay through the isospin violation precesses Bs0BsηBsπ0B_{s0}\to B_s\eta\to B_s\pi^0 and Bs1BsηBsπ0B_{s1}\to B_s^*\eta\to B_s^*\pi^0. The bottomed mesons Bs0B_{s0} and Bs1B_{s1}, just like their charmed cousins Ds0(2317)D_{s0}(2317) and Ds1(2460)D_{s1}(2460), maybe very narrow.Comment: 9 pages, 5 figures, 4-versio
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