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Open Access Publications from the University of California

Scholarly Works (6 results)

  • Article
LBL Publications (1976)
    Cover page: SUPERCONDUCTORS BY POWDER METALLURGY TECHNIOUES
    • Article
    LBL Publications (1969)
      Cover page: METALLOGRAPHY APPLIED TO MATERIAL SELECTION AND PROCESS DESIGN - A CASE HISTORY
      • Article
      LBL Publications (1965)
        Cover page: A TECHNIQUE FOR EXTRUSION FORMING OF BRITTLE AND REFRACTORY COMPOSITIONS
        • Thesis
        • Peer Reviewed
        UC San Francisco Electronic Theses and Dissertations (2013)

        Methicillin-resistant Staphylococcus aureus (MRSA) is a staphylococcal bacterium that is resistant to beta-lactam antibiotics. Today, MRSA accounts for 50-70% of the nosocomial S. aureus infections acquired in healthcare facilities. MRSA contaminated surfaces and MRSA colonized human carriers can act as reservoirs for transmission, and dental clinics may serve as a source of disease transmission in the community.

        Objective: Survey an 18 chair university-based periodontal clinic for MRSA contamination among hard environmental surfaces, dental unit water lines (DUWLs), aerosols, and human carriers.

        Methods: (1) Hard environmental surface contamination. 18 air-water syringes (AWS) from the assistant's rack were swabbed, incubated for 24 hours, and streaked onto a selective chromogenic medium that detects MRSA (CMRSAII). (2) DUWL contamination. The Millipore heterotrophic plate count sampler was used to sample water from the 18 DUWLs. Following a 48-hour incubation, grown colonies were inoculated on the CMRSAII plates. (3) Dental procedure aerosol contamination. The Millipore M Air T Tester was used to collect 1000L of aerosol during ultrasonic scaling procedures or surgical procedures using highspeed handpieces. After a 24-hour incubation, colonies morphologically consistent with S. aureus were picked, sub-cultured, and swabbed onto CMRSAII plates. (4) Human carriers. 30 healthy volunteers were recruited among the periodontal residents, staff, and faculty (IRB#12-08736). Specimens were obtained from the anterior nares, incubated overnight, then triple streaked onto CMRSAII plates.

        Results: (1) The AWS swabs yielded no MRSA colonies at 24 or 48 hours. (2) No MRSA were detected in the DUWLs. (3) 21 aerosol samples were taken during periodontal procedures using ultrasonics or dental handpieces. No MRSA were detected. (4) 30 samples from the anterior nares were collected and no MRSA were detected. Four individuals had Methicillin-resistant coagulase-negative staphylococci.

        Conclusion: This study did not detect MRSA in the university-based periodontal clinic on environmental surfaces, DUWLs, aerosols, or human carriers. The literature so far, in conjunction with the data from this study, collectively suggests that the occupational risk of MRSA infection in a dental setting is probably minimal.

          Cover page: Surveillance of Methicillin-Resistant Staphylococcus Aureus in a Periodontal Clinic
          • Article
          • Peer Reviewed
          UCLA Previously Published Works (2022)
          ATHENA has been designed as a general purpose detector capable of delivering the full scientific scope of the Electron-Ion Collider. Careful technology choices provide fine tracking and momentum resolution, high performance electromagnetic and hadronic calorimetry, hadron identification over a wide kinematic range, and near-complete hermeticity. This article describes the detector design and its expected performance in the most relevant physics channels. It includes an evaluation of detector technology choices, the technical challenges to realizing the detector and the R&D required to meet those challenges.
            Creative Commons 'BY-NC-ND' version 4.0 license
            • Article
            • Peer Reviewed
            UC San Diego Previously Published Works (2015)
            The Muller F element (4.2 Mb, ~80 protein-coding genes) is an unusual autosome of Drosophila melanogaster; it is mostly heterochromatic with a low recombination rate. To investigate how these properties impact the evolution of repeats and genes, we manually improved the sequence and annotated the genes on the D. erecta, D. mojavensis, and D. grimshawi F elements and euchromatic domains from the Muller D element. We find that F elements have greater transposon density (25-50%) than euchromatic reference regions (3-11%). Among the F elements, D. grimshawi has the lowest transposon density (particularly DINE-1: 2% vs. 11-27%). F element genes have larger coding spans, more coding exons, larger introns, and lower codon bias. Comparison of the Effective Number of Codons with the Codon Adaptation Index shows that, in contrast to the other species, codon bias in D. grimshawi F element genes can be attributed primarily to selection instead of mutational biases, suggesting that density and types of transposons affect the degree of local heterochromatin formation. F element genes have lower estimated DNA melting temperatures than D element genes, potentially facilitating transcription through heterochromatin. Most F element genes (~90%) have remained on that element, but the F element has smaller syntenic blocks than genome averages (3.4-3.6 vs. 8.4-8.8 genes per block), indicating greater rates of inversion despite lower rates of recombination. Overall, the F element has maintained characteristics that are distinct from other autosomes in the Drosophila lineage, illuminating the constraints imposed by a heterochromatic milieu.
              Cover page: Drosophila Muller F Elements Maintain a Distinct Set of Genomic Properties Over 40 Million Years of Evolution
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