6,264 research outputs found
The Charm of the Proton and the Production
We propose a two component model for charmed baryon production in
collisions consisting of the conventional parton fusion mechanism and
fragmentation plus quarks recombination in which a valence diquark from
the proton recombines with a -sea quark to produce a . Our
two-component model is compared with the intrinsic charm two-component model
and experimental data.Comment: 6 pages, LaTex, 2 figures included, aipproc.sty included. Talk
presented at Simposio Latino Americano de Fisica de Altas Energias, Merida,
Mexico, November 199
Asymmetry studies in Lambda 0/Lambda 0-bar, Xi-/Xi+ and Omega-/Omega+ production
We present a study on hyperon/anti-hyperon production asymmetries in the
framework of the recombination model. The production asymmetries for Lambda
0/Lambda 0-bar, Xi-/Xi+ and Omega-/Omega+ are studied as a function of x_F.
Predictions of the model are compared to preliminary data on
hyperon/anti-hyperon production asymmetries in 500 GeV/c pi- p interactions
from the Fermilab E791 experiment. The model predicts a growing asymmetry with
the number of valence quarks shared by the target and the produced hyperons in
the x_F < 0 region. In the positive x_F region, the model predicts constant
asymmetries for Lambda 0/Lambda 0-bar and Omega-/Omega+ production and a
growing asymmetry with x_F for Xi-/Xi+. We found a qualitatively good agreement
between the model predictions and data, showing that recombination is a
competitive mechanism in the hadronization process.Comment: One reference correcte
O Percurso da Educação Física na Educação Infantil no Micípio de Vitória/ES.
O Percurso da Educação Física na Educação Infantil no Micípio de Vitória/ES
Paper making potential of Acacia dealbata and Acacia melanoxylon
The pulping and papermaking potential of Acacia dealbata and Acacia melanoxylon were studied using Eucalyptus globulus as a reference. Pulp yield, alkali consumption and delignification in the kraft process, of both species, compare very well with the reference. Pulp yield can be higher than that of E. globulus and the residual lignin content lower after cooking, which is in good agreement with the lower lignin and extractives content of the wood samples used. Pulps produced from Acacia have slightly lower fibre length and coarseness and higher fibre width and wet fibre flexibility than E. globulus pulps. As a consequence of fibre characteristics, the paper produced from Acacia is denser and exhibits higher tensile and burst strength, and lower tear resistance than that from E. globulus, at a given PFI revolution.info:eu-repo/semantics/publishedVersio
Influence of wood basic density on acacia melanoxylon kraft process
Wood density is a complex physical property related to the anatomical structure and the chemical composition of
wood and one of the most important wood quality factors. Sampling was based on a total of 20 trees from four
sites in Portugal that were harvested at a sawmill diameter class of 40 cm and wood discs taken at different
height levels from the base to the top of the tree.
The mean basic density of the Acacia melanoxylon trees measured at 5% height level (near breast height level)
was 516 kg/m3 with a 34 kg/m3 standard deviation. The within-tree axial variation of density was of small
magnitude, but showing higher values at the stem base and top. Site had no influence on the basic density of the
wood. Overall the between tree variation of density was small possibly linked to the narrow genetic diversity of
this introduced exotic species. In the Kraft process we can observe variability between stands and an increase of
the pulp yield, and fiber width and length with the higher level in the tree. The wood basic density is well
correlated with the ISO brightness and well correlated in inverse order with the pulp Yield and fiber width and
length. The kappa number don’t present a great variation with the wood basic density
- …