Showing papers by "Jie Zhang published in 2008"

Expected Performance of the ATLAS Experiment - Detector, Trigger and Physics

Abstract: A detailed study is presented of the expected performance of the ATLAS detector. The reconstruction of tracks, leptons, photons, missing energy and jets is investigated, together with the performance of b-tagging and the trigger. The physics potential for a variety of interesting physics processes, within the Standard Model and beyond, is examined. The study comprises a series of notes based on simulations of the detector and physics processes, with particular emphasis given to the data expected from the first years of operation of the LHC at CERN.

Palonosetron exhibits unique molecular interactions with the 5-HT3 receptor.

Abstract: BACKGROUND:Palonosetron is a 5-HT3-receptor antagonist (5-HT3-RA) that has been shown to be superior to other 5-HT3-RAs in phase III clinical trials for the prevention of acute, delayed, and overall chemotherapy-induced nausea and vomiting The improved clinical efficacy of palonosetron may be due,

Interference avoidance and dynamic frequency planning for WiMAX femtocells networks

Abstract: Femtocells have been recently proposed as a potential good solution to increase not only indoor radio coverage, but also system capacity. In this paper, a framework for radio coverage prediction and system level simulation for WiMAX macrocell/femtocell scenarios is presented. Furthermore, the feasibility of the co-channel deployment of WiMAX femtocell in an existing WiMAX macrocell network is investigated, and a method for interference avoidance based on DFP (dynamic frequency planning) is proposed. The resulting impact of DFP in a macrocell/femtocell scenario compared with other frequency assignment strategies is analyzed. Experimental evaluations carried out using our framework show the boost in the system capacity when using DFP and femtocells.

Measurements of e+e-→K+K-η, K+K-π0, and Ks0K±π cross sections using initial state radiation events

Abstract: This paper reports measurements of processes: e+e-→γKS0K±π∓, e+e-→γK+K-π0, e+e-→γϕη, and e+e-→γϕπ0. The initial-state radiated photon allows to cover the hadronic final state in the energy range from thresholds up to ≈4.6 GeV. The overall size of the data sample analyzed is 232 fb-1, collected by the BABAR detector running at the PEP-II e+e- storage ring. From the Dalitz plot analysis of the KS0K±π∓ final state, moduli, and relative phase of the isoscalar and the isovector components of the e+e-→KK*(892) cross section are determined. Parameters of ϕ and ρ recurrences are also measured, using a global fitting procedure which exploits the interconnection among amplitudes, moduli, and phases of the e+e-→KS0K±π∓, K+K-π0, ϕη final states. The cross section for the OZI-forbidden process e+e-→ϕπ0, and the J/ψ branching fractions to KK*(892) and K+K-η are also measured.

Observation of Y(3940) -> J/psi omega in B -> J/psi omega K at BABAR

Abstract: We present a study of the decays B;{0,+}-->J/psiomegaK;{0,+} using 383x10;{6} BB[over ] events obtained with the BABAR detector at PEP-II. We observe Y(3940)-->J/psiomega, with mass 3914.6_{-3.4};{+3.8}(stat)+/-2.0(syst) MeV/c;{2}, and width 34_{-8};{+12}(stat)+/-5(syst) MeV. The ratio of B0 and B+ decay to YK is 0.27_{-0.23};{+0.28}(stat)-0.01+0.04(syst), and the relevant B0 and B+ branching fractions are reported.

Preparation of Au/TiO2 catalysts from Au(I)–thiosulfate complex and study of their photocatalytic activity for the degradation of methyl orange

Abstract: Gold loaded on TiO 2 (Au/TiO 2 ) catalysts were prepared using Au(I)–thiosulfate complex (Au(S 2 O 3 ) 2 3− ) as the gold precursor for the first time. The samples were characterized by UV–vis diffuse reflectance spectra, X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic absorption flame emission spectroscopy (AAS), and X-ray photoelectron spectroscopy (XPS) methods. Using Au(S 2 O 3 ) 2 3− as gold precursor, ultra-fine gold nanoparticles with a highly disperse state can be successfully formed on the surface of TiO 2 . The diameter of Au nanoparticles increases from 1.8 to 3.0 nm with increasing the nominal Au loading from 1% to 8%. The photocatalytic activity of Au/TiO 2 catalysts was evaluated from the analysis of the photodegradation of methyl orange (MO). With the similar Au loading, the catalysts prepared with Au(S 2 O 3 ) 2 3− precursor exhibit higher photocatalytic activity for methyl orange degradation when compared with the Au/TiO 2 catalysts prepared with the methods of deposition–precipitation (DP) and impregnation (IMP). The preparation method has decisive influences on the morphology, size and number of Au nanoparticles loaded on the surface of TiO 2 and further affects the photocatalytic activity of the obtained catalysts.

Study of resonances in exclusive B decays to D̄(*)D(*)K

Abstract: We present a study of resonances in exclusive decays of $B$ mesons to $\bar{D}^{(*)} D^{(*)} K$. We report the observation of the decays $B \to \Dbar^{(*)} D^+_{s1}(2536)$ where the $D^+_{s1}(2536)$ is reconstructed in the $D^{*0}K^+$ and $D^{*+} K^0_S$ decay channels. We report also the observation of the decays $B \to \psi(3770) K$ where the $\psi(3770)$ decays to $\Dbar^0 D^0$ and $D^- D^+$. In addition, we present the observation of an enhancement for the $\Dbar^{*0} D^0$ invariant mass in the decays $B \to \Dbar^{*0} D^0 K$, at a mass of $(3875.1 {}^{+0.7}_{-0.5} \pm 0.5)$ MeV/$c^2$ with a width of $(3.0 {}^{+1.9}_{-1.4} \pm 0.9)$ MeV (the first errors are statistical and the second are systematic). Branching fractions and spin studies are shown for the three resonances. The results are based on 347 fb$^{-1}$ of data collected with the BaBar detector at the PEP-II $B$ factory.

Multiuser scheduling on the downlink of an LTE cellular system

Abstract: The challenge of scheduling user transmissions on the downlink of a long-term evolution (LTE) cellular communication system is addressed. In particular, a novel optimalmultiuser scheduler is proposed. Numerical results show that the system performance improves with increasing correlation among OFDMA subcarriers. It is found that only a limited amount of feedback information is needed to achieve relatively good performance. A suboptimal reduced-complexity scheduler is also proposed and shown to provide good performance. The suboptimal scheme is especially attractive when the number of users is large, in which case the complexity of the optimal scheme is high.

Measurement of the B→Xsγ branching fraction and photon energy spectrum using the recoil method

Abstract: We present a measurement of the branching fraction and photon-energy spectrum for the decay B -> X-s gamma using data from the BABAR experiment. The data sample corresponds to an integrated luminosity of 210 fb(-1), from which approximately 680 000 B (B) over bar events are tagged by a fully reconstructed hadronic decay of one of the B mesons. In the decay of the second B meson, an isolated high-energy photon is identified. We measure B(B -> X-s gamma) = (3.66 +/- 0.85(stat) +/- 0.60(syst)) x 10(-4) for photon energies E-gamma above 1.9 GeV in the B rest frame. From the measured spectrum we calculate the first and second moments for different minimum photon energies, which are used to extract the heavy-quark parameters m(b) and mu(2)(pi). In addition, measurements of the direct CP asymmetry and isospin asymmetry are presented.

Access methods to WiMAX femtocells: A downlink system-level case study

Abstract: Over the last two years, GSM and UMTS femtocell access points have been proposed as a solution to the poor indoor coverage problem experienced in certain areas. Research on these devices has shown that femtocells will not only increase indoor system coverage, but also system capacity. Femtocells will allow new services and business models to be offered to indoor users. Almost parallely, the WiMAX standard has emerged as a potential candidate technology for the future wireless networks. WiMAX femtocells are currently under development and will therefore play an important role in the world of indoor broadband wireless access. However, several aspects of this new technology, such as the access method and interference avoidance techniques play a crucial role in the amount of interference caused to co-channel deployed macrocells. This paper provides a framework for the study of WiMAX macro-femtocell hybrid scenarios. An in-depth description of the necessary radio coverage prediction and system-level simulation for this kind of scenarios is introduced. Simulations and numerical results for two different types of access methods (public and private) in the downlink are also presented.

Observation of the semileptonic decays B→D*τ-ν̄τ and evidence for B→Dτ-ν̄τ

Abstract: We present measurements of the semileptonic decays B--->D0tau-nutau, B--->D*0tau-nutau, B0-->D+tau-nutau, and B0-->D*+tau-nutau, which are potentially sensitive to non-standard model amplitudes. The data sample comprises 232x10(6) Upsilon(4S)-->BB decays collected with the BABAR detector. From a combined fit to B- and B0 channels, we obtain the branching fractions B(B-->Dtau-nutau)=(0.86+/-0.24+/-0.11+/-0.06)% and B(B-->D*tau-nutau)=(1.62+/-0.31+/-0.10+/-0.05)% (normalized for the B0), where the uncertainties are statistical, systematic, and normalization-mode-related.

Exclusive branching-fraction measurements of semileptonic τ decays into three charged hadrons, into φπ-ντ, and into φk-ντ

Abstract: Using a data sample corresponding to an integrated luminosity of 342 fb(-1) collected with the BABAR detector at the SLAC PEP-II electron-positron storage ring operating at a center-of-mass energy near 10.58 GeV, we measure B(tau(-)->pi(-)pi(-)pi(+)nu(tau)(ex.K-S(0)))=(8.83 +/- 0.01 +/- 0.13)%, B(tau(-)-> K-pi(-)pi(+)nu(tau)(ex.K-S(0)))=(0.273 +/- 0.002 +/- 0.009)%, B(tau(-)-> K-pi K--(+)nu(tau))=(0.1346 +/- 0.0010 +/- 0.0036)%, and B(tau(-)-> K-K-K+nu(tau))=(1.58 +/- 0.13 +/- 0.12)x10(-5), where the uncertainties are statistical and systematic, respectively. These include significant improvements over previous measurements and a first measurement of B(tau(-)-> K-K-K+nu(tau)) in which no resonance structure is assumed. We also report a first measurement of B(tau(-)->phi pi(-)nu(tau))=(3.42 +/- 0.55 +/- 0.25)x10(-5), a new measurement of B(tau(-)->phi K-nu(tau))=(3.39 +/- 0.20 +/- 0.28)x10(-5) and a first upper limit on B(tau(-)-> K-K-K+nu(tau)(ex.phi)).

Search for CP violation in the decays D0→K-K+ and D0→π-π+

Abstract: We measure time-integrated CP-violating asymmetries of neutral charmed mesons in the modes D0 --> K(-) K(+) and D0 --> pi(-) pi(+) with the highest precision to date by using D0 --> K(-) pi(+) decays to correct detector asymmetries. An analysis of 385.8 fb(-1) of data collected with the BABAR detector yields values of a(CP)(KK)=(0.00+/-0.34(stat)+/-0.13(syst))% and a(CP)(pipi)=(-0.24+/-0.52(stat)+/-0.22(syst))%, which agree with standard model predictions.

Study of excited charm-strange baryons with evidence for new baryons Ξc(3055)+ and Ξc(3123)+

Abstract: We present a study of excited charm-strange baryon states produced in e{sup +}e{sup -} annihilations at or near a center-of-mass energy of 10.58 GeV, in a data sample with an integrated luminosity of 384 fb{sup -1} recorded with the BABAR detector at the PEP-II e+e storage rings at the Stanford Linear Accelerator Center. We study strong decays of charm-strange baryons to {Lambda}{sub c}{sup +}K{sub S}{sup 0}, {Lambda}{sub c}{sup +}K{sup -}, {Lambda}{sub c}{sup +}K{sup -}{pi}{sup +}, {Lambda}{sub c}{sup +}K{sub S}{sup 0}{pi}{sup -}, {Lambda}{sub c}{sup +}K{sub S}{sup 0}{pi}{sup -}{pi}{sup +}, {Lambda}{sub c}{sup +}K{sup -}{pi}{sup -}{pi}{sup +}. This study confirms the existence of the states {Xi}{sub c}(2980){sup +}, {Xi}{sub c}(3077){sup +}, and {Xi}{sub c}(3077){sup -}, with a more accurate determination of the {Xi}{sub c}(2980){sup +} mass and width. We also present evidence for two new states, {Xi}{sub c}(3055){sup +} and {Xi}{sub c}(3123){sup +}, decaying through the intermediate resonant modes {Sigma}{sub c}(2455){sup ++}K{sup -} and {Sigma}{sub c}(2520){sup ++}K{sup -}, respectively. For each of these baryons, we measure the yield in each final state, determine the statistical significance, and calculate the product of the production cross-section and branching fractions. We also measure the masses and widths of these excited charm-strange baryons.

Search for B+→τ+ν decays with hadronic B tags

Abstract: We present a search for the decay B{sup +}{yields}{tau}{sup +}{nu} using 383x10{sup 6} BB pairs collected at the {upsilon}(4S) resonance with the BABAR detector at the SLAC PEP-II B Factory. We select a sample of events with one completely reconstructed tag B in a hadronic decay mode (B{sup -}{yields}D{sup (*)0}X{sup -}), and examine the rest of the event to search for a B{sup +}{yields}{tau}{sup +}{nu} decay. We identify the {tau} lepton in the following modes: {tau}{sup +}{yields}e{sup +}{nu}{nu}, {tau}{sup +}{yields}{mu}{sup +}{nu}{nu}, {tau}{sup +}{yields}{pi}{sup +}{nu}, and {tau}{sup +}{yields}{pi}{sup +}{pi}{sup 0}{nu}. We find a 2.2{sigma} excess in data and measure a branching fraction of B(B{sup +}{yields}{tau}{sup +}{nu})=(1.8{sub -0.8}{sup +0.9}(stat.){+-}0.4(bkg. syst.){+-}0.2(other syst.))x10{sup -4}. We calculate the product of the B meson decay constant f{sub B} and |V{sub ub}| to be f{sub B}{center_dot}|V{sub ub}|=(10.1{sub -2.5}{sup +2.3}(stat.){sub -1.5}{sup +1.2}(syst.))x10{sup -4} GeV.

Using Incompletely Cooperative Game Theory in Wireless Sensor Networks

Abstract: In WSNs, energy conservation is the primary goal, while throughput and delay are less important. So used energy is traded for throughput and delay. In this paper, a novel concept of incompletely cooperative game theory is used in WSNs to simultaneously achieve all the goals. In the game, each node adjusts its equilibrium strategy to the estimated game state. After discussing the utility function of the game, the equilibrium strategy for the game in WSNs is presented, Moreover, a simplified game-theoretic MAC protocol (G-MAC) is provided for WSNs, by using an auto degressive backoff mechanism, which is easy to be implemented. Simulation results show that the incompletely cooperative game can increase system throughput, and decrease delay and packet-loss-rate, while still maintaining reasonable energy consumption, and that G-MAC supports the game effectively.

Using Incompletely Cooperative Game Theory in Wireless Mesh Networks

Abstract: Recently, game theory has become a useful and powerful tool in research on wireless mesh networks. In this article the authors present a novel concept of incompletely cooperative game theory and use it to improve the performance of MAC protocols in WMNs. In this game, first, each node estimates the current game state (e.g., the number of competing nodes). Second, the node adjusts its equilibrium strategy by tuning its local contention parameters (e.g., the minimum contention window) to the estimated game state. Finally, the game is repeated several times to get the optimal performance. To use the game effectively in WMNs, the authors present a hybrid CSMA/CA protocol by integrating a proposed virtual CSMA/CA and the standard CSMA/CA protocol. When a node has no packet to send, it contends for the channel in virtual CSMA/CA mode. In this way the node can estimate the game state and obtain the optimal strategy. When a node has packets to send, it contends for the channel in standard CSMA/CA mode with the optimal strategy obtained in virtual CSMA/CA mode, switching smoothly from virtual to standard CSMA/CA mode. At the same time, the node keeps adjusting its strategy to the variable game state. In addition, the authors propose a simplified game-theoretic MAC protocol (G-CSMA/CA) by designing an auto degressive backoff mechanism based on the incompletely cooperative game. G-CSMA/CA can easily be implemented in mesh nodes. Finally, simulation results show that the incompletely cooperative game can increase system throughput, decrease delay, jitter, and packet loss rate, and support the game effectively.

Search for CPT and lorentz violation in B0-B̄0 oscillations with dilepton events

Abstract: We report results of a search for CPT and Lorentz violation in B{sup 0}-{bar B}{sup 0} oscillations using inclusive dilepton events from 232 million {Upsilon}(4S) {yields} B{bar B} decays recorded by the BABAR detector at the PEP-II B Factory at SLAC. We find 2.8{sigma} significance, compatible with no signal, for variations in the complex CPT violation parameter z at the Earth's sidereal frequency and extract values for the quantities {Delta}a{sub {mu}} in the general Lorentz-violating standard-model extension. The spectral powers for variations in z over the frequency range 0.26 year{sup -1} to 2.1 day{sup -1} are also compatible with no signal.

Determination of the form factors for the decay B0→D*-l+νl and of the CKM matrix element |Vcb|

Abstract: We present a combined measurement of the Cabibbo-Kobayashi-Maskawa matrix element vertical bar V-cb vertical bar and of the parameters rho(2), R-1(1), and R-2(1), which fully characterize the form factors for the B-0 -> D*(-)center dot(+)nu(center dot) decay in the framework of heavy-quark effective field theory. The results, based on a selected sample of about 52 800 B-0 -> D*(-)center dot(+)nu(center dot) decays, recorded by the BABAR detector, are rho(2)=1.157 +/- 0.094 +/- 0.027, R-1(1)=1.327 +/- 0.131 +/- 0.043, R-2(1)=0.859 +/- 0.077 +/- 0.021, and F(1)vertical bar V-cb vertical bar=(34.7 +/- 0.4 +/- 1.0)x10(-3). The first error is the statistical and the second is the systematic uncertainty. Combining these measurements with the previous BABAR measurement of the form factors, which employs a different fit technique on a partial sample of the data, we improve the statistical precision of the result, rho(2)=1.191 +/- 0.048 +/- 0.028, R-1(1)=1.429 +/- 0.061 +/- 0.044, R-2(1)=0.827 +/- 0.038 +/- 0.022, and F(1)vertical bar V-cb vertical bar=(34.4 +/- 0.3 +/- 1.1)x10(-3). Using lattice calculations for the axial form factor F(1), we extract vertical bar V-cb vertical bar=(37.4 +/- 0.3 +/- 1.2 +/-(1.2)(1.4))x10(-3), where the third error is due to the uncertainty in F(1). We also present a measurement of the exclusive branching fraction, B=(4.69 +/- 0.04 +/- 0.34)%.

Preparation and characterization of magnetic TiO2/ZnFe2O4 photocatalysts by a sol–gel method

Abstract: A magnetic TiO2/ZnFe2O4 photocatalyst was prepared by a sol-gel method, and X-ray diffraction (XRD), magnetic and photocatalytic properties analysis were employed to characterize this photocatalyst. The XRD results show that ZnFe2O4 can prevent the transformation of titania from anatase to rutile. The magnetic properties analysis indicates that TiO2/ZnFe2O4 is of large saturation magnetization value and low coercivity. The photocatalytic experimental results show that TiO2/ZnFe2O4=3 and 4 are superior in photocatalytic reactivity to other proportions. TEM shows that TiO2/ZnFe2O4 has a fine core-shell fabric. After being used for four times during the photocatalytic reaction, the TiO2/ZnFe2O4 nanoparticles have good photocatalytic stability.

Search for lepton flavor violating decays τ±→l± ω

Abstract: A search for lepton flavor violating decays of a {tau} to a lighter-mass charged lepton and an {omega} vector meson is performed using 384.1 fb{sup -1} of e{sup +}e{sup -} annihilation data collected with the BABAR detector at the Stanford Linear Accelerator Center PEP-II storage ring. No signal is found, and the upper limits on the branching ratios are determined to be {beta}({tau}{sup {+-}} {yields} e{sup {+-}}{omega}) < 1.1 x 10{sup -7} and {beta}({tau}{sup {+-}} {yields} {mu}{sup {+-}}{omega}) < 1.0 x 10{sup -7} at 90% confidence level.

Morphological variety of the soft palate in normal individuals: a digital cephalometric study

Abstract: Objectives: The literature describes the morphology of the soft palate as being of only one kind and ignores its diversity, but in our clinical work we discovered that the morphology of the soft palate has a variable presentation on lateral cephalometry. The aim of our study was to investigate the variation of the velar morphology. Methods: In this study, the sample comprised 200 normal subjects whose ages ranged from 5–48 years (mean 19.37 years). The morphology of the soft palate on lateral cephalometry was examined and classified into six types. The dimensional differences of the soft palate between each pair of types and the differences in proportion to different age and gender groups were also studied. Results: The morphology of the soft palate was classified into six types. There was a significant difference between the pre-adult and adult groups and also between male and female groups in proportion to velar type. The velar length in Type 3 was significantly shorter than in all other types apart fro...

Community of extremely halophilic bacteria in historic Dagong Brine Well in southwestern China

Abstract: The Dagong Brine Well, the earliest man-made brine well in record, located in Zigong, Sichuan, China, had the construction and facilities mainly made of bamboo, wood and stone that are eroded easily by halophiles colonizing in the brine of the well. To better preserve this historic placemark, we initiated an investigation on the microbial community and the diversity of the halophilic bacteria in the brine of Dagong well for the first time. A total of 112 aerobic halophile strains were isolated and characterized according to their phenotype, cellular fatty acids composition and 16S rRNA. Furthermore, the intra specific phylogeny of closely related strains was also screened by PCR fragment length polymorphism of 16S–23S ribosomal RNA intergenic spacer regions (ISR). The result showed that the halophilic isolates found in current study were closely related to the following genera: Planococcus, Halomonas, Halobacillus, Oceanobacillus and Virgibacillus, a lineage of the domain Bacteria. Halomonas and Halobacillus were the dominant genera as represents 27% and 40% of the total isolates, respectively. The distribution of other genera was as follows: Oceanobacillus (18%), Virgibacillus (10%) and Planococcus (5%). The ISR analysis disclosed variation of banding pattern in some isolates related to Oceanobacillus and Halobacillus which was observed with phenotypic and physiological characterizations as well. It was clear that these halophiles have adapted to the special man-made hypersaline environment by the basic physiological evolution during phylogenesis and thus resulted in phenotypic and genotypic diversity in the Dagong Brine Well.