7,293 research outputs found

    Do dental nonmetric traits actually work as proxies for neutral genomic data? Some answers from continental- and global-level analyses

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    Objectives: Crown and root traits, like those in the Arizona State University Dental Anthropology System (ASUDAS), are seemingly useful as genetic proxies. However, recent studies report mixed results concerning their heritability, and ability to assess variation to the level of genomic data. The aim is to test further if such traits can approximate genetic relatedness, among continental and global samples. Materials and Methods: First, for 12 African populations, Mantel correlations were calculated between mean measure of divergence (MMD) distances from up to 36 ASUDAS traits, and FST distances from >350,000 single nucleotide polymorphisms (SNPs) among matched dental and genetic samples. Second, among 32 global samples, MMD and FST distances were again compared. Correlations were also calculated between them and inter-sample geographic distances to further evaluate correspondence. Results: A close ASUDAS/SNP association, based on MMD and FST correlations, is evident, with rm-values between .72 globally and .84 in Africa. The same is true concerning their association with geographic distances, from .68 for a 36-trait African MMD to .77 for FST globally; one exception is FST and African geographic distances, rm = 0.49. Partial MMD/FST correlations controlling for geographic distances are strong for Africa (.78) and moderate globally (.4). Discussion: Relative to prior studies, MMD/FST correlations imply greater dental and genetic correspondence; for studies allowing direct comparison, the present correlations are markedly stronger. The implication is that ASUDAS traits are reliable proxies for genetic data‚ÄĒa positive conclusion, meaning they can be used with or instead of genomic markers when the latter are unavailable

    Age estimation [editorial].

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    yesAssessing and interpreting dental and skeletal age-related changes in both the living and the dead is of interest to a wide range of disciplines (e.g. see Bittles and Collins 1986) including human biology, paediatrics, public health, palaeodemography, archaeology, palaeontology, human evolution, forensic anthropology and legal medicine. ... This special issue of Annals of Human Biology arises from the 55th annual symposium of the Society for the Study of Human Biology in association with the British Association for Biological Anthropological and Osteoarchaeology held in Oxford, UK, from 9‚Äď11 December 2014. Only a selection of the presentations are included here which encompass some of the major recent advances in age estimation from the dentition and skeleton

    Environments of the Four Tryptophans in the Extracellular Domain of Human Tissue Factor: Comparison of Results from Absorption and Fluorescence Difference Spectra of Tryptophan Replacement Mutants with the Crystal Structure of the Wild-Type Protein

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    The local environments of the four tryptophan residues of the extracellular domain of human tissue factor (sTF) were assessed from difference absorption and fluorescence spectra. The difference spectra were derived by subtracting spectra from single Trp-to-Phe or Trp-to-Tyr replacement mutants from the corresponding spectrum of the wild-type protein. Each of the mutants was capable of enhancing the proteolytic activity of factor Vila showing that the mutations did not introduce major structural changes, although the mutants were more susceptible to denaturation by guanidinium chloride. The difference spectra indicate that the Trp residues are buried to different extents within the protein matrix. This evaluation was compared with the x-ray crystal structure of sTF. There is excellent agreement between predictions from the difference spectra and the environments of the Trp residues observed in the x-ray crystal structure, demonstrating that difference absorption and particularly fluorescence spectra derived from functional single-Trp replacement mutants can be used to obtain information about the local environments of individual Trp residues in multi-tryptophan proteins

    A high-performance track fitter for use in ultra-fast electronics

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    This article describes a new charged-particle track fitting algorithm designed for use in high-speed electronics applications such as hardware-based triggers in high-energy physics experiments. Following a novel technique designed for fast electronics, the positions of the hits on the detector are transformed before being passed to a linearized track parameter fit. This transformation results in fitted track parameters with a very linear dependence on the hit positions. The approach is demonstrated in a representative detector geometry based on the CMS detector at the Large Hadron Collider. The fit is implemented in FPGA chips and optimized for track fitting throughput and obtains excellent track parameter performance. Such an algorithm is potentially useful in any high-speed track-fitting application

    Search for charged Higgs decays of the top quark using hadronic tau decays

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    We present the result of a search for charged Higgs decays of the top quark, produced in ppňČp\bar{p} collisions at ‚ąös=\surd s = 1.8 TeV. When the charged Higgs is heavy and decays to a tau lepton, which subsequently decays hadronically, the resulting events have a unique signature: large missing transverse energy and the low-charged-multiplicity tau. Data collected in the period 1992-1993 at the Collider Detector at Fermilab, corresponding to 18.7¬Ī\pm0.7~pb‚ąí1^{-1}, exclude new regions of combined top quark and charged Higgs mass, in extensions to the standard model with two Higgs doublets.Comment: uuencoded, gzipped tar file of LaTeX and 6 Postscript figures; 11 pp; submitted to Phys. Rev.

    Inclusive jet cross section in pňČp{\bar p p} collisions at s=1.8\sqrt{s}=1.8 TeV

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    The inclusive jet differential cross section has been measured for jet transverse energies, ETE_T, from 15 to 440 GeV, in the pseudorapidity region 0.1‚ȧ‚ą£ő∑‚ą£‚ȧ\leq | \eta| \leq 0.7. The results are based on 19.5 pb‚ąí1^{-1} of data collected by the CDF collaboration at the Fermilab Tevatron collider. The data are compared with QCD predictions for various sets of parton distribution functions. The cross section for jets with ET>200E_T>200 GeV is significantly higher than current predictions based on O(őĪs3\alpha_s^3) perturbative QCD calculations. Various possible explanations for the high-ETE_T excess are discussed.Comment: 8 pages with 2 eps uu-encoded figures Submitted to Physical Review Letter

    Search for the Supersymmetric Partner of the Top-Quark in ppňČp \bar{p} Collisions at s=1.8TeV\sqrt{s} = 1.8 {\rm TeV}

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    We report on a search for the supersymmetric partner of the top quark (stop) produced in ttňČt \bar{t} events using 110pb‚ąí1110 {\rm pb}^{-1} of ppňČp \bar{p} collisions at s=1.8TeV\sqrt{s} = 1.8 {\rm TeV} recorded with the Collider Detector at Fermilab. In the case of a light stop squark, the decay of the top quark into stop plus the lightest supersymmetric particle (LSP) could have a significant branching ratio. The observed events are consistent with Standard Model ttňČt \bar{t} production and decay. Hence, we set limits on the branching ratio of the top quark decaying into stop plus LSP, excluding branching ratios above 45% for a LSP mass up to 40 {\rm GeV/c}2^{2}.Comment: 11 pages, 4 figure

    Measurement of the ttňČproductioncrosssectionint\bar{t} production cross section in p\bar{p}collisionsat collisions at \sqrt{s}$ = 1.8 TeV

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    We update the measurement of the top production cross section using the CDF detector at the Fermilab Tevatron. This measurement uses ttňČt\bar{t} decays to the final states e+őĹe+\nu+jets and őľ+őĹ\mu+\nu+jets. We search for bb quarks from tt decays via secondary-vertex identification or the identification of semileptonic decays of the bb and cascade cc quarks. The background to the ttňČt\bar{t} production is determined primarily through a Monte Carlo simulation. However, we calibrate the simulation and evaluate its uncertainty using several independent data samples. For a top mass of 175 GeV/c2GeV/c^2, we measure ŌÉttňČ=5.1¬Ī1.5\sigma_{t\bar{t}}=5.1 \pm 1.5 pb and ŌÉttňČ=9.2¬Ī4.3\sigma_{t\bar{t}}=9.2 \pm 4.3 pb using the secondary vertex and the lepton tagging algorithms, respectively. Finally, we combine these results with those from other ttňČt\bar{t} decay channels and obtain ŌÉttňČ=6.5‚ąí1.4+1.7\sigma_{t\bar{t}} = 6.5^{+1.7}_{-1.4} pb.Comment: The manuscript consists of 130 pages, 35 figures and 42 tables in RevTex. The manuscript is submitted to Physical Review D. Fixed typo in author lis

    Search for New Particles Decaying to Dijets at CDF

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    We have used 106 pb^-1 of data collected with the Collider Detector at Fermilab to search for new particles decaying to dijets. We exclude at the 95% confidence level models containing the following new particles: axigluons and flavor universal colorons with mass between 200 and 980 GeV/c, excited quarks with mass between 80 and 570 GeV/c^2 and between 580 and 760 GeV/c^2, color octet technirhos with mass between 260 and 480 GeV/c^2, W' bosons with mass between 300 and 420 GeV/c^2, and E_6 diquarks with mass between 290 and 420 GeV/c^2.Comment: 18 pages, 4 figures, 1 table. Submitted to Physical Review D Rapid Communications. Postscript file of paper is also available at http://www-cdf.fnal.gov/physics/pub97/cdf3276_dijet_search_prd_rc.p

    Measurement of Dijet Angular Distributions at CDF

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    We have used 106 pb^-1 of data collected in proton-antiproton collisions at sqrt(s)=1.8 TeV by the Collider Detector at Fermilab to measure jet angular distributions in events with two jets in the final state. The angular distributions agree with next to leading order (NLO) predictions of Quantum Chromodynamics (QCD) in all dijet invariant mass regions. The data exclude at 95% confidence level (CL) a model of quark substructure in which only up and down quarks are composite and the contact interaction scale is Lambda_ud(+) < 1.6 TeV or Lambda_ud(-) < 1.4 TeV. For a model in which all quarks are composite the excluded regions are Lambda(+) < 1.8 TeV and Lambda(-) < 1. 6 TeV.Comment: 16 pages, 2 figures, 2 tables, LaTex, using epsf.sty. Submitted to Physical Review Letters on September 17, 1996. Postscript file of full paper available at http://www-cdf.fnal.gov/physics/pub96/cdf3773_dijet_angle_prl.p
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