Biomedical subjects

X B Ma

Publications and source records attributed to X B Ma.

7 recordsLinked to original sources

PubMed2006

Search for invisible decays of eta and eta' in J/psi --> phi eta and phi eta'.

Using a data sample of 58 x 10(6) J/psi decays collected with the Beijing Spectrometer II detector at the Beijing Electron Positron Collider, searches for invisible decays of eta and eta' in J/psi to phi eta and phi eta' are performed. The phi signals, which are reconstructed in K+K- final states, are used to tag the eta and eta' decays. No signals are found for the invisible decays of either eta or eta', and upper limits at the 90% confidence level are determined to be 1.65 x 10(-3) for the ratio B(eta-->invisible)/B(eta --> gamma gamma) and 6.69 x 10(-2) for B(eta' --> invisible)/B(eta' --> gammagamma). These are the first searches for eta and eta' decays into invisible final states.

Journal Article↗

PubMed2006

Observation of a broad 1-- resonant structure around 1.5 GeV/c2 in the K+K- mass spectrum in J/psi-->K+K-pi0.

A broad peak is observed at low K+K- invariant mass in J/psi-->K+K-pi(0) decays found in a sample of 5.8x10(7) J/psi events collected with the BESII detector. The statistical significance of the broad resonance is much larger than 5sigma. A partial wave analysis shows that the J;{PC} of this structure is 1--. Its pole position is determined to be [1576(-55)(+49)(stat)-91+98(syst)] MeV/c(2)-i/2[818(-23)(+22)(stat)-133+64(syst)] MeV/c(2). These parameters are not compatible with any known meson resonances.

Journal Article↗

PubMed2006

Measurements of the branching fractions for psi(3770)-->D(0)D[over ](0), D+D-, DD[over ], and the resonance parameters of psi(3770) and psi(2S).

We measure the branching fractions for psi(3770)-->D(0)D[over ](0), D+D-, DD[over ], and non-DD[over ] to be (46.7+/-4.7+/-2.3)%, (36.9+/-3.7+/-2.8)%, (83.6+/-7.3+/-4.2)%, and (16.4+/-7.3+/-4.2)%, respectively. The resonance parameters of psi(3770) and psi(2S) are measured to be M_(psi(3770))=3772.2+/-0.7+/-0.3 MeV, Gamma_(psi(3770))(tot)=26.9+/-2.4+/-0.3 MeV, and Gamma_(psi(3770))(ee)=251+/-26+/-11 eV; M_(psi(2S))=3685.5+/-0.0+/-0.3 MeV, Gamma_(psi(2S))(tot)=331+/-58+/-2 keV, and Gamma_(psi(2S))(ee)=2.330+/-0.036+/-0.110 keV. We also measure the light hadron R value to be R(uds)=2.262+/-0.054+/-0.109 in the energy region from 3.660 to 3.872 GeV.

Journal Article↗

PubMed2006

Observation of a near-threshold enhancement in the omega(phi) mass spectrum from the doubly OZI-suppressed decay J/psi-->gamma(omega)phi.

An enhancement near threshold is observed in the omega(phi) invariant mass spectrum from the doubly Okubo-Zweig-Iizuka-suppressed decays of J/psi-->gamma(omega)phi, based on a sample of 5.8 x 10(7) J/psi events collected with the BESII detector. A partial wave analysis shows that this enhancement favors JP=0+, and its mass and width are M=1812(+19)(-26)(stat)+/-18(syst) MeV/c2 and Gamma=105+/-20(stat)+/-28(syst) MeV/c2. The product branching fraction is determined to be B(J/psi-->gammaX)B(X-->omega(phi))=[2.61+/-0.27(stat)+/-0.65(syst)]x10(-4).

Journal Article↗

PubMed2006

Differential gene expression profiling in aggressive bladder transitional cell carcinoma compared to the adjacent microscopically normal urothelium by microdissection-SMART cDNA PCR-SSH.

Identifying novel and known genes that are differentially expressed in aggressive bladder transitional cell carcinoma (BTCC) has important implications in understanding the biology of bladder tumorigenesis and developing new diagnostic and therapeutic agents. In this study we identified the differential gene expression profiles comparing tumor to the adjacent microscopically normal mucosa by manual microdissection on frozen sections. The RNAs extracted from microdissected tissues were amplified by SMART cDNA PCR technology to generate forward subtractive cDNA library by suppressive subtractive hybridization (SSH). We obtained 376 positive clones, one hundred clones of aggressive BTCC subtracted cDNA library were selected at random and inserts were reamplified by PCR. After differential screening by reverse dot blotting, 73 positive clones, that contend inserts putatively upregulated in aggressive BTCC, were further analysed by DNA sequencing, GenBank and EST database searching. Sequencing results showed that 66 clones stand for 23 known genes and 7 clones for three new EST (Genbank number: DN236875, DN236874 and DN236873). In conclusion, microdissection-SMART cDNA PCR-SSH allowed for an efficient way to identify aggressive BTCC-specific differential expressed genes that may potentially be involved in the carcinogenesis and/or progression of aggressive BTCC. These differentially expressed genes may be of potential utility as therapeutic and diagnostic targets for aggressive BTCC.

Carcinoma, Transitional Cell↗

PubMed2005

Observation of a resonance in Chi(1835) in J/psi --> gammapi+ pi- eta-.

The decay channel J/psi --> gamma(pi)(+)pi(-)eta is analyzed using a sample of 5.8 x 10(7) J/psi events collected with the BESII detector. A resonance, the Chi(1835), is observed in the pi(+)pi(-)eta invariant-mass spectrum with a statistical significance of 7.7 sigma. A fit with a Breit-Wigner function yields a mass M = 1833.7 +/- 6.1(stat) +/- 2.7(syst) MeV/c(2), a width Tau = 67.7 +/- 20.3(stat) +/- 7.7(syst) MeV/c(2), and a product branching fraction B(J/psi --> gammaChi) . B(Chi --> pi(+)pi(-)eta) = [2.2 +/- 0.4(stat) +/- 0.4(syst)] x 10(-4). The mass and width of the Chi(1835) are not compatible with any known meson resonance. Its properties are consistent with expectations for the state that produces the strong pp mass threshold enhancement observed in the J/psi --> gammapp process at BESII.

Journal Article↗

PubMed1995

Superior extension of the parascapular free flap for cervical burn scar contracture.

A newly designed superior extension of the parascapular free flap and its free transfer clinically for the repair of 11 cases of cervical burn scar contracture without any loss are presented. The flap sizes ranged from 16 x 7 cm to 32 x 11 cm. Based on the anatomic distribution of the circumflex scapular vessels, the flap in the scapular territory can be taken much longer and wider than before. There is less tension in this vertically oriented flap than in the horizontally oriented flap in obtaining primary closure. This method extends the application of the scapular territory as a donor site for free flaps.

Adolescent↗