20 research outputs found
Measurement of the Charged Multiplicities in b, c and Light Quark Events from Z0 Decays
Average charged multiplicities have been measured separately in , and
light quark () events from decays measured in the SLD experiment.
Impact parameters of charged tracks were used to select enriched samples of
and light quark events, and reconstructed charmed mesons were used to select
quark events. We measured the charged multiplicities:
,
, from
which we derived the differences between the total average charged
multiplicities of or quark events and light quark events: and . We compared
these measurements with those at lower center-of-mass energies and with
perturbative QCD predictions. These combined results are in agreement with the
QCD expectations and disfavor the hypothesis of flavor-independent
fragmentation.Comment: 19 pages LaTex, 4 EPS figures, to appear in Physics Letters
Macroinvertebrates inhabiting the tank leaf terrestrial and epiphyte bromeliads at Reserva Adolpho Ducke, Manaus, Amazonas
The aim of this work was to investigate the diversity of macroinvertebrates and also verify if the abundance and diversity of Diptera were influenced by the abiotic factors. The samples were collected from the epiphytic and terrestrial bromeliads G. brasiliensis (1 and 3m) in wet and dry seasons at Reserva Adolpho Ducke analyzed total of 144 samples were analyzed from a total of 15,238 individuals collected. These conatined 14,097 insects and, among these, 8,258 were immature Diptera, represented by eight most abundant families: Chironomidae, Ceratopogonidae and Culicidae. The relationship of Diptera diversity was influenced by the seasons and stratifications (p= 0.01); the abundance was influenced by the volume of water (p= 0.02) and the relationship between the season and volume of water in the terrestrial bromeliads was significant (p= 0.01). This study represented the first contribution to knowledge of community of macroinvertebrates associated to bromeliads G. brasiliensis in Central Amazon
A Study of J/psi-->gamma gamma V(rho,phi) Decays with the BESII Detector
Using a sample of events collected with the BESII
detector, radiative decays , where or ,
are studied. A resonance around 1420 MeV/c (X(1424)) is observed in the
mass spectrum. Its mass and width are measured to be MeV/c and MeV/c,
respectively, and its branching ratio is determined to be . A
search for yields a 95% C.L. upper limit .Comment: 10 pages, 5 figures, submitted to PL
Characterization of a surface membrane molecule expressed by natural killer cells in most inbred mouse strains: monoclonal antibody C9.1 identifies an allelic form of the 2B4 antigen
A newly generated monoclonal antibody (mAb C9.1) described in this study identifies a surface membrane molecule that is involved in the lytic programme of activated natural killer (NK) cells. This conclusion is based on the facts that, first, this antigen was expressed on the vast majority of surface immunoglobulin (sIg)− CD3− CD4− CD8− spleen lymphocytes, albeit it was also present on minor subsets of sIg+ B (≈7%) and CD3+ T (≈2%) lymphocytes; second, that all splenic NK activity was contained within the C9.1+ cell population, and was almost totally abolished by treatment of spleen cells with mAb C9.1 and complement; third, that mAb C9.1 was capable of increasing interleukin-2-cultured and in vivo polyinosinic:polycytidylic acid-activated, NK cell-mediated, antibody-redirected lysis, but not freshly isolated NK cell-mediated killing. Furthermore, the strain distribution of the C9.1 antigen was shown to be antithetical to that of the 2B4 antigen already described as a molecule associated with major histocompatibility complex-unrestricted killing mediated by activated NK cells. The gene encoding C9.1 antigen was linked to the Akp1 isozyme locus on chromosome 1 close to the 2B4 gene. Although C9.1 and 2B4 were monomeric glycoproteins of 78 000 MW and 66 000 MW, respectively, removal of N-linked sugars from both antigens by endoglycosidase F yielded identical protein backbones of 38 000 MW. Thus, all of these results suggest that mAb C9.1 recognizes an allelic form of the 2B4 antigen. However, the detection of mAb C9.1-reactive antigen on a minor subset of B cells may suggest a possible reactivity of mAb C9.1 with some product of other members of the 2B4 family genes