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Open Access Publications from the University of California

Scholarly Works (30 results)

  • Article
LBL Publications (1968)
    Cover page: THE COBWEB DATA REDUCTION SYSTEM
    • Article
    • Peer Reviewed
    UC San Francisco Previously Published Works (2003)

    Purpose: The goal of this project was to compare MRI measures of hippocampal, entorhinal cortex (ERC), and whole brain longitudinal change in cognitively normal elderly controls (C), non-demented subjects with cognitive impairment (CI), and demented (D) subjects. Methods: 16 C, 6 CI, and 7 D subjects of comparable age were studied with MRI twice, at least 1 year apart. Longitudinal change in total brain size was measured by several methods, including computerized segmentation, non-linear warping, and change in the fluid/tissue boundaries between cerebrospinal fluid (CSF) and brain. Change in hippocampal volume was measured by semi-automated methods, and ERC volumes were manually measured. Results: The annual rate of atrophy was greater in D versus C and D versus CI for cortical gray matter (cGM) (P = 0.009 and 0.002), hippocampus (P = 0.0001 and 0.002), and for the change in the fluid/tissue boundary (P = 0.03 and 0.03). The annual rate of atrophy of ERC was greater in both CI and D versus C (P = 0.01 and 0.0002). No significant differences between groups were found using non-linear warping. Conclusions: In CI, the greatest annual rates of atrophy were in ERC, while in D the greatest annual rates of atrophy were in hippocampus and cortex. Progressive ERC atrophy was observed with a greater degree of cognitive impairment, while hippocampal and cortical atrophy were only observed in demented subjects. (C) 2002 Elsevier Science Inc. All rights reserved.

      Cover page: Comparison of methods for measuring longitudinal brain change in cognitive impairment and dementia
      • Article
      • Peer Reviewed
      UC Berkeley Previously Published Works (1992)
      Using an impact-parameter tag to select an enriched sample of Z0bb» events, we have measured the difference between the average charged multiplicity of bb» and all hadronic Z0 decays to be 2.11.8(stat) 0.6(syst) tracks per event. The resulting total (nonleading) charged multiplicity for Z0 bb» events is 23.1(12.0)1.8 0.6 tracks. A comparison of this nonleading multiplicity to hadronic multiplicity data in the range of 10 to 60 GeV supports the hypothesis of flavor-independent hadronic fragmentation, and yields a measurement of the average energy fraction of bottom hadrons in Z0 decays of xEb=0.620.100.04. © 1992 The American Physical Society.
        Cover page: Measurement of the charged multiplicity of events containing bottom hadrons at Ec. m.=91 GeVCreative Commons 'BY' version 4.0 license
        • Article
        • Peer Reviewed
        UC Irvine Previously Published Works (1989)
        We use data from the Mark II experiment at PEP to search for the process B→h0X for mh0 between 50 and 210 MeV/c2. No evidence for the Higgs boson is seen in this mass range. The limit obtained rules out the standard Higgs boson for masses between 70 and 210 MeV/c2 and significantly constrains extensions of the Higgs sector. © 1989.
          Cover page: Search for B-decay to Higgs bosons for Higgs boson masses between 50 and 210 MeV/c2Creative Commons 'BY' version 4.0 license
          • Article
          • Peer Reviewed
          UC Berkeley Previously Published Works (1990)
          A search for pair production of stable charged particles from Z decay has been performed with the Mark II detector at the SLAC Linear Collider. Particle masses are determined from momentum, ionization energy loss, and time-of-flight measurements. A limit excluding pair production of stable fourth-generation charged leptons and stable mirror fermions with masses between the muon mass and 36.3 GeV/c2 is set at the 95% confidence level. Pair production of stable supersymmetric scalar leptons with masses between the muon mass and 32.6 GeV/c2 is also excluded. © 1990 The American Physical Society.
            Cover page: Direct search for pair production of heavy stable charged particles in Z decaysCreative Commons 'BY' version 4.0 license
            • Article
            • Peer Reviewed
            UC Berkeley Previously Published Works (1991)
            We have measured the fraction of bb» events in hadronic Z0 decays, Rbb», using the vertex detector system of the Mark II detector at the SLAC Linear Collider. We tag bb» events by requiring the coincidence of three or more tracks with significant impact parameters. This tag is 50% efficient and results in a sample of 85% purity. We find Rbb»=0.251+0.049+0.030, in good agreement with other measurements and the standard model prediction. © 1991 The American Physical Society.
              Cover page: Measurement of the bb¯ fraction in hadronic Z0 decays with precision vertex detectorsCreative Commons 'BY' version 4.0 license
              • Article
              • Peer Reviewed
              UC Irvine Previously Published Works (1991)
              A precise measurement of the ratio R of the total cross section e+e-hadrons to the pointlike cross section e+e-+- at a center-of-mass energy of 29.0 GeV is presented. The data were taken with the upgraded Mark II detector at the SLAC storage ring PEP. The result is R=3.920.050.09. The luminosity has been determined with three independent luminosity monitors measuring Bhabha scattering at different angular intervals. Recent calculations of higher-order QED radiative corrections are used to estimate the systematic error due to missing higher-order radiative corrections in the Monte Carlo event generators. © 1991 The American Physical Society.
                Cover page: Measurement of the total hadronic cross section in e+e- annihilation at s=29 GeVCreative Commons 'BY' version 4.0 license
                • Article
                • Peer Reviewed
                UC Irvine Previously Published Works (1990)
                Data taken by the Mark II detector at the PEP storage ring was used to measure the rate of dilepton production in multihadronic events produced by e+e- annihilation at √s=29 GeV. We determine the probability that a hadron initially containing a b (b̄) quark decays to a positive (negative) lepton to be 0.17-0.08+0.15, with 90% confidence level limits of 0.06 and 0.38. © 1990.
                  Cover page: A reanalysis of B0-B̄0 mixing in e+e− annihilation at 29 GeVCreative Commons 'BY' version 4.0 license
                  • Article
                  • Peer Reviewed
                  UC Berkeley Previously Published Works (1990)
                  Using isolated leptons reconstructed in the Mark II detector to tag bb events, we measure the fraction of bb events in hadronic Z0 decays to be 0.23-0.09+0.11, in good agreement with the standard-model prediction of 0.22. We find (Zbb)=0.43-0.17+0.21 GeV. © 1990 The American Physical Society.
                    Cover page: Measurement of the bb¯ fraction in hadronic Z decaysCreative Commons 'BY' version 4.0 license
                    • Article
                    • Peer Reviewed
                    UC Berkeley Previously Published Works (1989)
                    We present measurements by the Mark II experiment of the ratios of the leptonic partial widths of the Z boson to the hadronic partial width. The results are ee/had=0.037-0.012+0.016, &=0.053-0.0150.020, and /had=0.066-0.017+0.021, in good agreement with the standard-model prediction of 0.048. From the average leptonic width result, ll/had=0.053-0.009+0.010, we derive had=1.56-0.24+0.28 GeV. We find for the vector coupling constants of the tau and muon v2=0.310.31-0.30+0.43 and v2=0.050.30-0.23+0.34. © 1989 The American Physical Society.
                      Cover page: Measurement of Z decays into lepton pairsCreative Commons 'BY' version 4.0 license
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