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Open Access Publications from the University of California

Scholarly Works (5 results)

  • Article
  • Peer Reviewed
Lawrence Berkeley National Laboratory (2009)
    Cover page: Three-fold diffraction symmetry in epitaxial graphene and the SiC substrate
    • Article
    • Peer Reviewed
    Lawrence Berkeley National Laboratory (2010)
      Cover page: Quasi-Freestanding multilayer graphene films on the carbon face of SiC
      • Article
      • Peer Reviewed
      UC San Francisco Previously Published Works (1992)

      Background

      The use of smokeless tobacco (ST), which has increased in popularity over the past 2 decades, results in considerable systemic exposure to nicotine. Nicotine might contribute to atherosclerosis by an effect on cardiovascular risk factors.

      Methods

      The effects of ST use on cardiovascular risk factors and cotinine and nicotine levels were studied in 1061 professional baseball players during spring training in 1988 and 1989.

      Results

      Of the study participants 477 (45%) were users. ST use was more common among Whites (55%) than among Blacks (29%) or Hispanics (21%), and users reported heavier consumption of alcohol (p less than .001) and had higher mean serum caffeine levels (p less than .001) than nonusers. ST users did not differ from nonusers in adjusted levels of systolic and diastolic blood pressure, pulse, and total or HDL-cholesterol. Among ST users, participants using snuff had higher mean serum cotinine levels than those who used chewing tobacco (p less than .001). There was no association between serum cotinine levels and adjusted levels of any cardiovascular risk factor studied. However, higher diastolic blood pressures were associated with higher mean serum nicotine levels (p = .02).

      Conclusions

      Smokeless tobacco use has at most a modest effect on cardiovascular risk factors in young physically fit men.
        Creative Commons 'BY-NC-SA' version 4.0 license
        • Article
        • Peer Reviewed
        UC Santa Barbara Previously Published Works (2008)

        Many nearshore fish and invertebrate populations are overexploited even when apparently coherent management structures are in place. One potential cause of mismanagement may be a poor understanding and accounting of stochasticity, particularly for stock recruitment. Many of the fishes and invertebrates that comprise nearshore fisheries are relatively sedentary as adults but have an obligate larval pelagic stage that is dispersed by ocean currents. Here, we demonstrate that larval connectivity is inherently an intermittent and heterogeneous process on annual time scales. This stochasticity arises from the advection of pelagic larvae by chaotic coastal circulations. This result departs from typical assumptions where larvae simply diffuse from one site to another or where complex connectivity patterns are created by transport within spatially complicated environments. We derive a statistical model for the expected variability in larval settlement patterns and demonstrate how larval connectivity varies as a function of different biological and physical processes. The stochastic nature of larval connectivity creates an unavoidable uncertainty in the assessment of fish recruitment and the resulting forecasts of sustainable yields.

          Cover page: The stochastic nature of larval connectivity among nearshore marine populations.
          • Article
          • Peer Reviewed
          Faculty Publications (2009)
          Phytoplankton photosynthesis links global ocean biology and climate-driven fluctuations in the physical environment. These interactions are largely expressed through changes in phytoplankton physiology, but physiological status has proven extremely challenging to characterize globally. Phytoplankton fluorescence does provide a rich source of physiological information long exploited in laboratory and field studies, and is now observed from space. Here we evaluate the physiological underpinnings of global variations in satellite-based phytoplankton chlorophyll fluorescence. The three dominant factors influencing fluorescence distributions are chlorophyll concentration, pigment packaging effects on light absorption, and light-dependent energy-quenching processes. After accounting for these three factors, resultant global distributions of quenching-corrected fluorescence quantum yields reveal a striking consistency with anticipated patterns of iron availability. High fluorescence quantum yields are typically found in low iron waters, while low quantum yields dominate regions where other environmental factors are most limiting to phytoplankton growth. Specific properties of photosynthetic membranes are discussed that provide a mechanistic view linking iron stress to satellite-detected fluorescence. Our results present satellite-based fluorescence as a valuable tool for evaluating nutrient stress predictions in ocean ecosystem models and give the first synoptic observational evidence that iron plays an important role in seasonal phytoplankton dynamics of the Indian Ocean. Satellite fluorescence may also provide a path for monitoring climate-phytoplankton physiology interactions and improving descriptions of phytoplankton light use efficiencies in ocean productivity models.
            Cover page: Satellite-detected fluorescence reveals global physiology of ocean phytoplanktonCreative Commons 'BY' version 4.0 license
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