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Search Results: 1 - 10 of 46610 matches for " TANG Zhong-bo "
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Buoyancy Regulation and Vertical Distribution of Planktothrix mougeoti in the Simulator Experiments

TANG Zhong-bo,CHU Zhao-sheng,JIN Xiang-can,ZENG Qing-ru,

环境科学 , 2008,
Abstract: The dominance of gas-vacuolated cyanobacteria is often attributed to their buoyancy and buoyancy in response to environmental conditions. Lake simulator experiments (4 m high and 1 m diameter) and pyrex bottle experiments (10 L) were applied to investigate the buoyancy regulation and vertical distribution of Planktothrix mougeotii in eutrophic lakes at 28 degrees C. During light phase, the filaments stratify in the 2-3 m after 8 h light exposure and the biomass at the layer attach maximum after 12 h light exposure. During dark phase, the filaments are tent to migrate to the surface. 20% of filaments migrate to the surface after 12 h and 50% of filaments migrate to the surface after 48 h. The buoyancy regulation under light condition is that filaments stratify in 10 micromol x (m2 x s)(-1) layers, and the filaments above the layer sink down, while those suspended below the layer float up. The amplitude of diel changes in buoyancy is related to photon irradiance, and the change of buoyancy in light 100 micromol x (m2 x s)(-1)]/ dark is higher than its in light 25 micromol x (m2 x s)(-1)]/ dark. Carbohydrate ballasting may be the only mechanism for buoyancy changes in Planktothrix mougeotii filaments during the period.
Photon-tagged heavy meson production in high energy nuclear collisions
Zhong-Bo Kang,Ivan Vitev
Physics , 2011, DOI: 10.1103/PhysRevD.84.014034
Abstract: We study the photon-triggered light and heavy meson production in both p+p and A+A collisions. We find that a parton energy loss approach that successfully describes inclusive hadron attenuation in nucleus-nucleus reactions at RHIC can simultaneously describe well the experimentally determined photon-triggered light hadron fragmentation functions. Using the same framework, we generalize our formalism to study photon-triggered heavy meson production. We find that the nuclear modification of photon-tagged heavy meson fragmentation functions in A+A collision is very different from that of the photon-tagged light hadron case. While photon-triggered light hadron fragmentation functions in A+A collisions are suppressed relative to p+p, photon-triggered heavy meson fragmentation functions can be either enhanced or suppressed, depending on the specific kinematic region. The anticipated smaller energy loss for $b$-quarks manifests itself as a flatter photon-triggered $B$-meson fragmentation function compared to that for the $D$-meson case. We make detailed predictions for both RHIC and LHC energies. We conclude that a comprehensive comparative study of both photon-tagged light and heavy meson production can provide new insights in the details of the jet quenching mechanism.
Quark fragmentation in the $θ$-vacuum
Zhong-Bo Kang,Dmitri E. Kharzeev
Physics , 2010, DOI: 10.1103/PhysRevLett.106.042001
Abstract: The vacuum of Quantum Chromodynamics is a superposition of degenerate states with different topological numbers that are connected by tunneling (the $\theta$-vacuum). The tunneling events are due to topologically non-trivial configurations of gauge fields (e.g. the instantons) that induce local $\p$-odd domains in Minkowski space-time. We study the quark fragmentation in this topologically non-trivial QCD background. We find that even though QCD globally conserves $\p$ and $\cp$ symmetries, two new kinds of $\p$-odd fragmentation functions emerge. They generate interesting dihadron correlations: one is the azimuthal angle correlation $\sim \cos(\phi_1 + \phi_2)$ usually referred to as the Collins effect, and the other is the $\p$-odd correlation $\sim \sin(\phi_1 + \phi_2)$ that vanishes in the cross section summed over many events, but survives on the event-by-event basis. Using the chiral quark model we estimate the magnitude of these new fragmentation functions. We study their experimental manifestations in dihadron production in $e^+e^-$ collisions, and comment on the applicability of our approach in deep-inelastic scattering, proton-proton and heavy ion collisions.
Global fitting of single spin asymmetry: an attempt
Zhong-Bo Kang,Alexei Prokudin
Physics , 2012, DOI: 10.1103/PhysRevD.85.074008
Abstract: We present an attempt of global analysis of Semi-Inclusive Deep Inelastic Scattering (SIDIS) $\ell p^\uparrow \to \ell' \pi X$ data on single spin asymmetries and data on left-right asymmetry $A_N$ in $p^\uparrow p \to \pi X$ in order to simultaneously extract information on Sivers function and twist-three quark-gluon Efremov-Teryaev-Qiu-Sterman (ETQS) function. We explore different possibilities such as node of Sivers function in $x$ or $k_\perp$ in order to explain "sign mismatch" between these functions. We show that $\pi^\pm$ SIDIS data and $\pi^0$ STAR data can be well described in a combined TMD and twist-3 fit, however $\pi^\pm$ BRAHMS data are not described in a satisfactory way. This leaves open a question to the solution of the "sign mismatch". Possible explanations are then discussed.
Single transverse spin asymmetry of prompt photon production
Leonard Gamberg,Zhong-Bo Kang
Physics , 2012, DOI: 10.1016/j.physletb.2012.10.002
Abstract: We study the single transverse spin asymmetry of prompt photon production in high energy proton-proton scattering. We include the contributions from both the direct and fragmentation photons. While the asymmetry for direct photon production receives only the Sivers type of contribution, the asymmetry for fragmentation photons receives both the Sivers and Collins types of contributions. We make a model calculation for quark-to-photon Collins function, which is then used to estimate the Collins asymmetry for fragmentation photons. We find that the Collins asymmetry for fragmentation photons is very small, thus the single transverse spin asymmetry of prompt photon production is mainly coming from the Sivers asymmetry in direct and fragmentation photons. We make predictions for the prompt photon spin asymmetry at RHIC energy, and emphasize the importance of such a measurement.
Effect of low concentration nonionic surfactants on adsorption behavior of parathion-methyl in sediments

YANG Cheng-Jian,ZENG Qing-Ru,YANG Hai-Jun,YANG Bo,TANG Zhong-Bo,
,曾清如,杨海君,杨 波,唐中波

中国生态农业学报 , 2007,
Abstract: By using batch adsorption method,adsorption isotherms of two nonionic surfactants(Brij30,Tween-80)in two sediments were investigated and parathion-methyl adsorption behavior between the sediments and water with or without Brij30 or Tween-80 compared.Results show that the Smodel is appropriate for describing adsorption isotherms of Brij30 and Tween-80 in sediments.Adsorptions of Brij30 and Tween-80 are the results of their adherence or aggregation on sediment mineral matter and partitioning in sediment organic matter.When Brij30,Tween-80 concentrations are lower than CMC,parathion-methyl adsorption on sediments decreases as Brij30 and Tween-80 molecules compete against parathion-methyl molecules for adsorbent bit attainment.However,because Brij30 and Tween-80 surface micelle in the two sediments adsorbs parathion-methyl and surfactants disperse the sediment colloids,the adsorption of parathion-methyl to sediments increases as Brij30,Tween-80 concentrations are higher than CMC.
A Micromechanics Constitutive Model of the Metal Rubber Materials Based on the Radial and Axial Combined Deformation of the Microsprings

PENG Wei,BAI Hong-bai,ZHENG Jian,TANG Xi-nan,LI Guo-zhang,HE Zhong-bo,

实验力学 , 2005,
Abstract: 研究了金属橡胶材料细观本构模型。依据金属橡胶材料变形的主要特征,分析了微弹簧沿轴向和径向变形的规律,分别推导了应力应变关系的解析表达式,由两种微弹簧的组和变形构造了代表性体积单元-微元体。为了反映因铺层引起的工艺各向异性,本构方程中引入了一个新的材料参数铺层比例系数iβ,该参数可以较好地表征细观结构中微弹簧取向的分布状况。在大量试验的基础上,提出了确定铺层系数的实验方法,进而建立了包含金属橡胶材料细观结构信息的本构方程。理论与实验结果比较表明,本文建立的本构模型能较好的反映材料的力学行为。
Sivers asymmetry of Drell-Yan production in small-$x$ regime
Zhong-Bo Kang,Bo-Wen Xiao
Physics , 2012, DOI: 10.1103/PhysRevD.87.034038
Abstract: We study the Sivers single spin asymmetry of the Drell-Yan lepton pair production in the small-$x$ regime. We find that in the corresponding kinematic region the spin asymmetry calculated in the small-$x$ approach is consistent with either the usual transverse-momentum-dependent factorization formalism or the collinear factorization formalism, respectively. We estimate the Sivers asymmetry for both polarized p+p and p+A collisions and argue that the Drell-Yan production is an interesting and unique probe for both the transverse spin physics and the small-$x$ saturation effect.
Nuclear Modification to Parton Distribution Functions and Parton Saturation
Kang, Zhong-Bo;Qiu, Jian-Wei
High Energy Physics - Phenomenology , 2007, DOI: 10.1088/0954-3899/34/8/S54
Abstract: We introduce a generalized definition of parton distribution functions (PDFs) for a more consistent all-order treatment of power corrections. We present a new set of modified DGLAP evolution equations for nuclear PDFs, and show that the resummed $\alpha_s A^{1/3}/Q^2$-type of leading nuclear size enhanced power corrections significantly slow down the growth of gluon density at small-$x$. We discuss the relation between the calculated power corrections and the saturation phenomena.
Low-mass lepton pair production at large transverse momentum
Kang, Zhong-Bo;Qiu, Jian-Wei;Vogelsang, Werner
High Energy Physics - Phenomenology , 2008, DOI: 10.1103/PhysRevD.79.054007
Abstract: We study the transverse momentum distribution of low-mass lepton pairs produced in hadronic scattering, using the perturbative QCD factorization approach. We argue that the distribution at large transverse momentum, $Q_T \gg Q$, with the pair's invariant mass $Q$ as low as $Q \sim \Lambda_{\mathrm{QCD}}$, can be systematically factorized into universal parton-to-lepton pair fragmentation functions, parton distributions, and perturbatively calculable partonic hard parts evaluated at a short distance scale $\sim {\cal O}(1/Q_T)$. We introduce a model for the input lepton pair fragmentation functions at a scale $\mu_0\sim 1$ GeV, which are then evolved perturbatively to scales relevant at RHIC. Using the evolved fragmentation functions, we calculate the transverse momentum distributions in hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions at RHIC. We also discuss the sensitivity of the transverse momentum distribution of low-mass lepton pairs to the gluon distribution.
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