Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

DB: Quality and outcome determination in health care and orthopaedics: evolution and current structure

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Determination of alpha-s for b quarks at the Z0 resonance

The strong coupling constant for b quarks has been determined, and its flavour independence, as predicted by QCD, investigated. The analysis involved events with lepton candidates selected from approximately 356 000 hadronic decays of the Z0, collected by the DELPHI detector at LEP in 1990 and 1991. A method based on a direct comparison of the three-jet fraction in a b enriched sample, selected by requiring leptons with large momenta, to that of the entire hadronic sample, illustrated the significant effect of the b quark mass on the multi-jet cross section, and verified the flavour independence of the strong coupling constant to an accuracy of ±6%. A second procedure based on a fit to the momentum and transverse momentum spectra of the lepton candidates in both two-jet and three (or more)-jet event samples simultaneously determined the b content in each, and, using second order QCD calculations, gave an absolute measurement of αs for b quarks of 0.118±0.004 (stat.)±0.003 (syst.)±0.008 (scale). A comparison with αs for all quark flavours, as measured from the three-jet fraction in all hadronic events, further allowed the coupling strength for b quarks to be expressed in terms relative to that for udsc quarks, thereby cancelling certain common systematic uncertainties, and yielded View the MathML source

A STUDY OF THE DECAYS OF TAU LEPTONS PRODUCED ON THE Z-RESONANCE AT LEP

From the analysis of a data sample corresponding to an integrated luminosity of 4.63 pb-1 taken during the 1990 run of LEP at centre of mass energies between 88.2 GeV an 94.2 GeV, the tau decays {Mathematical expression} and their charge conjugates have been studied. The following branching ratios have been measured; {Mathematical expression}, {Mathematical expression}, Br(τ- → π- (K-)vτ)=11.9±0.7±0.7%, BR (τ- → ρ- vτ)= 22.4±0.8±1.3%, in good agreement with world averages. The measured electronic and muonic branching ratios lead to a measurement of the strong coupling constant, αs (mτ) = 0.26-0.12+0.09. Extrapolating the αs value from mτ to mZ yields αs (mZ) = 0.109-0.028+0.012. The average polarization Pτ of taus produced in Z → τs τs decays has also been measured using the above decay modes. The weighted mean of the polarizations obtained from the four decay modes is Pτ=-0.24±0.07. This value of Pτ gives, in the improved Born approximation, a ratio between the axial and vector coupling constants of the tau of υτ/aτ = 0.12 ± 0.04, and hence a value of the effective electroweak mixing parameter sin2 θW(mZ2). © 1992 Springer-Verlag

Measurement of Inclusive Production of Light Meson Resonances in Hadronic Decay of the Z0

A study of inclusive production of the meson resonances ρ0, K*0(892), f0(975) and f2(1270) in hadronic decays of the Z0 is presented. The measured mean meson multiplicity per hadronic event is 0.83 ± 0.14 for the ρ0, 0.64 ± 0.24 for the K*0(892), 0.10 ± 0.04 for the f0(975) in the momentum range p > 0.05pbeam (xp > 0.05) and 0.11 ± 0.05 for the f2(1270) for xp > 0.1. These values and the corresponding differential cross sections (1/σhadr) dσ/dxp for the vector mesons are in good agreement with the predictions of the JETSET 7.3 PS and HERWIG 5.4 models. The f2(1270) production is overestimated by HERWIG but its xp-shape is correctly reproduced. The measured ratios of the production cross sections σ(f2(1270))/σ(ρ0) = 0.22 ± 0.08 and σ(f2(1270))/σ(f0(975)) = 3-1 +7 for xp > 0.1 are consistent with the results obtained in hadronic reactions.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe

A Measurement of D meson production in Z0 hadronic decays

A study of the fragmentation properties of charm and bottom quarks into D mesons is presented. From 263 700 Z0 hadronic decays collected in 1991 with the DELPHI detector at the LEP collider, D0, D+ and D*+ are reconstructed in the modes K-π+, K-π+K+ and D0π+ followed by D0→K-π+, respectively. The fractional decay widths {Mathematical expression} are determined, and first results are presented for the production of D mesons from {Mathematical expression} and {Mathematical expression} events separately. The average energy fraction of D*± in charm quark fragmentation is found to be 〈XE(D*)〉c=0.487± 0.015 (stat)±0.005 (sys.). Assuming that the fraction of Ds and charm-baryons produced at LEP is similar to that around 10 GeV, the Z0 partial width into charm quark pairs is determined to be Γc/Γh=0.187±0.031 (stat)±0.023 (sys). The probability for a b quark to fragment into {Mathematical expression} or b-baryons is inferred to be 0.268±0.094 (stat)±0.100 (sys) from the measured probability that it fragments into a {Mathematical expression} or B-. © 1993 Springer-Verlag.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe