Showing papers by "Yang Li published in 2000"

Gene expression profiling in the human hypothalamus-pituitary-adrenal axis and full-length cDNA cloning.

Abstract: The primary neuroendocrine interface, hypothalamus and pituitary, together with adrenals, constitute the major axis responsible for the maintenance of homeostasis and the response to the perturbations in the environment. The gene expression profiling in the human hypothalamus-pituitary-adrenal axis was catalogued by generating a large amount of expressed sequence tags (ESTs), followed by bioinformatics analysis (http://www.chgc.sh.cn/ database). Totally, 25,973 sequences of good quality were obtained from 31,130 clones (83.4%) from cDNA libraries of the hypothalamus, pituitary, and adrenal glands. After eliminating 5,347 sequences corresponding to repetitive elements and mtDNA, 20,626 ESTs could be assembled into 9,175 clusters (3,979, 3,074, and 4,116 clusters in hypothalamus, pituitary, and adrenal glands, respectively) when overlapping ESTs were integrated. Of these clusters, 2,777 (30.3%) corresponded to known genes, 4,165 (44.8%) to dbESTs, and 2,233 (24.3%) to novel ESTs. The gene expression profiles reflected well the functional characteristics of the three levels in the hypothalamus-pituitary-adrenal axis, because most of the 20 genes with highest expression showed statistical difference in terms of tissue distribution, including a group of tissue-specific functional markers. Meanwhile, some findings were made with regard to the physiology of the axis, and 200 full-length cDNAs of novel genes were cloned and sequenced. All of these data may contribute to the understanding of the neuroendocrine regulation of human life.

Measurement of charge asymmetries in charmless hadronic B meson decays.

Abstract: We search for CP-violating charge asymmetries (alpha(CP)) in the B meson decays to K(+/-)pi(-/+), K(+/-)pi(0), K(0)(S)pi(+/-), K(+/-)eta('), and omega pi(+/-). Using 9.66 million upsilon(4S) decays collected with the CLEO detector, the statistical precision on alpha(CP) is in the range of +/-0.12 to +/-0.25 depending on decay mode. While CP-violating asymmetries of up to +/-0.5 are possible within the standard model, the measured asymmetries are consistent with zero in all five decay modes studied.

Search for D0- D⊭0mixing

Abstract: We have studied the ''wrong-sign'' process D{sup 0}{yields}K{sup +}{pi}{sup -} to search for D{sup 0}-D{sup 0} mixing. The data come from 9.0 fb{sup -1} of e{sup +}e{sup -} collisions at (sq root)(s){approx_equal}10 GeV recorded with the CLEO II.V detector. We measure the relative rate of the wrong-sign process D{sup 0}{yields}K{sup +}{pi}{sup -} to the Cabibbo-favored process D{sup 0}{yields}K{sup +}{pi}{sup -} to be R=(0.332{sup +0.063}{sub -0.065}{+-}0.040 )% . We study D{sup 0}{yields}K{sup +}{pi}{sup -} as a function of decay time to distinguish direct doubly Cabibbo-suppressed decay from D{sup 0}-D{sup 0} mixing. The amplitudes that describe D{sup 0}-D{sup 0} mixing, x{sup '} and y{sup '} , are consistent with zero. At the 95% C.L. and without assumptions concerning charge-parity (CP ) violating parameters, we find (1/2)x{sup '2}<0.041% and -5.8%

Resonant structure ofτ→3ππ0ντandτ→ωπντdecays

Abstract: The resonant structure of the four pion final state in the decay $\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\tau}}3\ensuremath{\pi}{\ensuremath{\pi}}^{0}{\ensuremath{ u}}_{\ensuremath{\tau}}$ has been analyzed using 4.27 million ${\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}}$ pairs collected by the CLEO II experiment at the Cornell Electron Storage Ring. A partial wave analysis of the resonant structure of the $\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\tau}}3\ensuremath{\pi}{\ensuremath{\pi}}^{0}{\ensuremath{ u}}_{\ensuremath{\tau}}$ decay has been performed; the spectral decomposition of the four pion system is dominated by the $\ensuremath{\omega}\ensuremath{\pi}$ and ${a}_{1}\ensuremath{\pi}$ final states. The mass and width of the ${\ensuremath{\rho}}^{\ensuremath{'}}$ resonance have been extracted from a fit to the $\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\tau}}\ensuremath{\omega}\ensuremath{\pi}{\ensuremath{ u}}_{\ensuremath{\tau}}$ spectral function. We have searched for second class currents in the decay $\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\tau}}\ensuremath{\omega}\ensuremath{\pi}{\ensuremath{ u}}_{\ensuremath{\tau}}$ using spin-parity analysis and established an upper limit on the non-vector current contribution.

Expression of tumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) receptors and sensitivity to TRAIL-induced apoptosis in primary B-cell acute lymphoblastic leukaemia cells: Activity of TRAIL in B-cell ALL

Abstract: Because tumour necrosis factor (TNF)‐related apoptosis‐inducing ligand (TRAIL) (Apo2 ligand) preferentially kills malignant cells while sparing normal cells, it may be therapeutically useful against cancers, including those of haematopoietic origin. Although the activity of TRAIL has been studied in tumour cell lines and in a limited number of different primary tumours, its overall activity in a large number of uniform cases of primary tumours is not known. We therefore studied the activity of TRAIL in 29 primary precursor B‐cell acute lymphoblastic leukaemia (ALL) samples. TRAIL was found to have a modest activity as it killed a maximum of 29% of ALL cells within 18 h compared with killing 75% of Jurkat cells. The sensitivity to TRAIL did not correlate with the pattern of TRAIL receptor expression or FLIP expression, as determined by Western blot analysis. The CD40 receptor, which can transduce survival signals in mature malignant B cells, was less frequently expressed on ALL cells, but incubation with an exogenous soluble CD40 ligand trimer did not rescue them from spontaneous apoptosis and did not mediate their resistance to TRAIL. Further, although ALL cells expressed TRAIL protein, they failed to kill target Jurkat cells in a TRAIL‐dependent manner. Our data delineate major biological differences between mature and precursor malignant B cells and suggest a limited therapeutic role for TRAIL as a single agent in primary B‐cell ALL.

The first year of the BABAR experiment at PEP-II

Abstract: The BABAR detector, situated at the SLAC PEP-II asymmetric e^+e^- collider, has been recording data at energies on and around the Upsilon(4S) resonance since May 1999. In this paper, we briefly describe the PEP-II B Factory and the BABAR detector. The performance presently achieved by the experiment in the areas of tracking, vertexing, calorimetry and particle identification is reviewed. Analysis concepts that are used in the various papers submitted to this conference are also discussed.

Exclusive B decays to charmonium final states

Abstract: We report on exclusive decays of B mesons into final states containing charmonium using data collected with the BABAR detector at the PEP-II storage rings. The charmonium states considered here are J/psi, psi(2S), and chi_C1. Branching fractions for several exclusive final states, a measurement of the decay amplitudes for the B0 --> J/psi K* decay, and measurements of the B0 and B+ masses are presented. All of the results we present here are preliminary.

Performance of the Belle silicon vertex detector

Abstract: The performance of the Silicon Vertex Detector (SVD) in the Belle experiment is reviewed based on 6.8 fb/sup -1/ of data taken between October 1999 and July 2000. The main purpose of the SVD is to make precise measurements of the B decay vertex position, which are essential for the observation of CP asymmetries. Excellent vertex resolution and a good detection efficiency are required for the SVD. Basic performance parameters such as signal pulse height, noise, strip yield and intrinsic resolution are reported. The SVD performance parameters which are directly related to physics analysis such as track matching efficiency, impact parameter resolution and vertex resolution are also shown.

A measurement of the charged and neutral B meson lifetimes using fully reconstructed decays

Abstract: Data collected with the BABAR detector at the PEP-II asymmetric B Factory at SLAC are used to study the lifetimes of the B^0 and B^+ mesons. The data sample consists of 7.4 fb-1 collected near the Y(4S) resonance. B^0 and B^+ mesons are fully reconstructed in several exclusive hadronic decay modes to charm and charmonium final states. The B lifetimes are determined from the flight length difference between the two B mesons which are pair-produced in the Y(4S) decay. The preliminary measurements of the lifetimes are tau_B0 = 1.506+/-0.052(stat)+/-0.029(syst) ps, tau_B+ = 1.602+/-0.049(stat)+/-0.035(syst) ps, and of their ratio is tau_B+/tau_B0 = 1.065+/-0.044(stat)+/-0.021(syst)

Measurement of B(Lambda+(c) ---> p K- pi+)

Abstract: The /\c->pKpi yield has been measured in a sample of two-jet continuum events containing a both an anticharm tag (Dbar) as well as an antiproton (e+e- -> Dbar pbar X), with the antiproton in the hemisphere opposite the Dbar. Under the hypothesis that such selection criteria tag e+e- -> Dbar pbar (/\c) X events, the /\c->pkpi branching fraction can be determined by measuring the pkpi yield in the same hemisphere as the antiprotons in our Dbar pbar X sample. Combining our results from three independent types of anticharm tags, we obtain B(/\c->pKpi)=(5.0+/-0.5+/-1.2)%

Measurement of inclusive production of charmonium states in B meson decays

Abstract: We reconstruct the charmonium mesons J/psi, psi(2S) and chi_C1 using a sample of 8.46 x 10^6 B-anti-B events collected by the BABAR detector operating at e^+e^- center of mass energies near the Y(4S) resonance. By measuring rates relative to the branching fraction of the J/psi, we obtain preliminary inclusive B branching fractions of (0.25+/-0.02+/-0.02)% to the psi(2S) and (0.39+/-0.04+/-0.04)% to the chi_C1, and set a 90% confidence level limit of 0.24% on decays through the chi_C2.

Study on Raman spectrum of nanophase anatase

Abstract: The nanophase anatase of different sizes (2-40 nm) were synthesized with chemical precipitation method. Nanophase anatase (2-40 nm), anatase (micron) and natural anatase were investigated by Raman spectrum. The spectra indicate: when the crystalline particles sizes decreased, obvious Raman shifts towards higher frequencies were observed and the intensity of Raman scattering decreased markedly. The shift towards higher frequencies reached max (10 cm-1) at 143 cm-1 comparing 2 nm anatase and natural anatase; when the crystalline particles sizes decreased; the shifts at 515 and 637 cm-1 towards higher frequencies reached max, but while the crystalline particles sizes became smaller, the shifts reached towards lower frequencies; There was no obvious shift at 396 cm-1 with the decreasing of the crystalline particle sizes. These reflect the complexity of nanophase materials structure, that may be caused by flexibility distortion of crystal.

Measurement of branching fractions for two-body charmless B decays to charged pions and kaons at BaBar

Abstract: We present preliminary results of a search for charmless two-body B decays to charged pions and kaons using data collected by the BABAR detector at the Stanford Linear Accelerator Center's PEP-II storage ring. In a sample of 8.8 million produced B-anti-B pairs we measure the branching fractions B(B^0 --> pi^+pi^-) = (9.3^{+2.6}_{-2.3}^{+1.2}_{-1.4}) x 10^{-6} and B(B^0 --> K^+\pi^-) = (12.5^{+3.0}_{-2.6}^{+1.3}_{-1.7}) x 10^{-6}, where the first uncertainty is statistical and the second is systematic. For the decay B^0 --> K^+K^- we find no significant signal and set an upper limit of B(B^0 --> K^+K^-) 6.6 x 10^{-6} at the 90% confidence level.

Measurement of inclusive production of charmonium states in B meson decays

Abstract: We reconstruct the charmonium mesons J/psi, psi(2S) and chi_C1 using a sample of 8.46 x 10^6 B-anti-B events collected by the BABAR detector operating at e^+e^- center of mass energies near the Y(4S) resonance. By measuring rates relative to the branching fraction of the J/psi, we obtain preliminary inclusive B branching fractions of (0.25+/-0.02+/-0.02)% to the psi(2S) and (0.39+/-0.04+/-0.04)% to the chi_C1, and set a 90% confidence level limit of 0.24% on decays through the chi_C2.

Measurement of the time dependence of $B^{0}-\bar B^{0}$ oscillations using inclusive dilepton events

Abstract: A preliminary study of time dependence of B^0-anti-B^0 oscillations using dilepton events is presented. The flavor of the B meson is determined by the charge sign of the lepton. To separate signal leptons from cascade and fake leptons we have used a method which combines several discriminating variables in a neural network. The time evolution of the oscillations is studied by reconstructing the time difference between the decays of the B mesons produced by the Y(4S) decay. With an integrated luminosity of 7.7 fb-1 collected on resonance by BABAR at the PEP-II asymmetric B Factory, we measure the difference in mass of the neutral B eigenstates, Delta_mB0 to be (0.507+/-0.015+/-0.022) x 10^{12} hbar-s^{-1}.

Measurement of branching fractions for two-body charmless B decays to charged pions and kaons at BABAR

Abstract: We present preliminary results of a search for charmless two-body B decays to charged pions and kaons using data collected by the BABAR detector at the Stanford Linear Accelerator Center's PEP-II storage ring. In a sample of 8.8 million produced B-anti-B pairs we measure the branching fractions B(B^0 --> pi^+pi^-) = (9.3^{+2.6}_{-2.3}^{+1.2}_{-1.4}) x 10^{-6} and B(B^0 --> K^+\pi^-) = (12.5^{+3.0}_{-2.6}^{+1.3}_{-1.7}) x 10^{-6}, where the first uncertainty is statistical and the second is systematic. For the decay B^0 --> K^+K^- we find no significant signal and set an upper limit of B(B^0 --> K^+K^-) 6.6 x 10^{-6} at the 90% confidence level.

Measurements of charmless three-body and quasi-two-body B decays

Abstract: We present preliminary results of a search for several exclusive charmless hadronic B decays from electron-positron annihilation data collected by the BABAR detector near the Y(4S) resonance. These include three-body decay modes with final states h^{+/-}h^{-/+}h^{+/-} and h^{+/-}h^{-/+}pi^0, and quasi-two-body decay modes with final states X^0 h and X^0 K0S, where h = pi or K and X^0 = eta^' or omega. We find B(B^0 --> rho^(-/+)pi^(+/-)) = (49+/-13^{+6}_{-5}) x 10^{-6} and B(B^+ --> eta^' K^+) = (62+/-18+/-8) x 10^{-6} and present upper limits for eight other decays.

Study of two-body B decays to kaons and pions: Observation of B ---> pi+ pi-, B ---> K+- pi0, and B ---> K0 pi0 decays

Abstract: We have studied charmless hadronic decays of B mesons into two-body final states with kaons and pions and observe three new processes with the following branching fractions: B(B → ππ) = (4.3 −1.4±0.5)×10 , B(B → Kπ) = (14.6 −5.1−3.3) × 10 , and B(B → Kπ) = (11.6 −2.7−1.3) × 10 . We also update our previous measurements for the decays B → Kπ and B → Kπ.

A Search for B ---> tau nu

Abstract: We report results of a search for $B\\to\\tau\ u$ in a sample of 9.7 million charged $B$ meson decays. The search uses both $\\pi\ u$ and $\\ell\ u\\bar\ u$ decay modes of the $\\tau$, and demands exclusive reconstruction of the companion $\\bar B$ decay to suppress background. We set an upper limit on the branching fraction ${\\cal B}(B\\to \\tau\ u) < 8.4\\times 10^{-4}$ at 90% confidence level. With slight modification to the analysis we also establish ${\\cal B}(B^\\pm\\to K^\\pm\ u\\bar\ u) < 2.4\\times 10^{-4}$ at 90% confidence level.