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Effects of Climate Change on Range Forage Production in the San Francisco Bay Area  [PDF]
Rebecca Chaplin-Kramer, Melvin R. George
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0057723
Abstract: The San Francisco Bay Area in California, USA is a highly heterogeneous region in climate, topography, and habitats, as well as in its political and economic interests. Successful conservation strategies must consider various current and future competing demands for the land, and should pay special attention to livestock grazing, the dominant non-urban land-use. The main objective of this study was to predict changes in rangeland forage production in response to changes in temperature and precipitation projected by downscaled output from global climate models. Daily temperature and precipitation data generated by four climate models were used as input variables for an existing rangeland forage production model (linear regression) for California’s annual rangelands and projected on 244 12 km x 12 km grid cells for eight Bay Area counties. Climate model projections suggest that forage production in Bay Area rangelands may be enhanced by future conditions in most years, at least in terms of peak standing crop. However, the timing of production is as important as its peak, and altered precipitation patterns could mean delayed germination, resulting in shorter growing seasons and longer periods of inadequate forage quality. An increase in the frequency of extremely dry years also increases the uncertainty of forage availability. These shifts in forage production will affect the economic viability and conservation strategies for rangelands in the San Francisco Bay Area.
The Golden Gate Textile Barrier: Preserving California Bay of San Francisco from a Rising North Pacific Ocean  [PDF]
Richart B. Cathcart,Alexander A. Bolonkin
Physics , 2007,
Abstract: Climate change in California may require construction of a barrier separating the Pacific Ocean from San Francisco Bay and the Sacramento River-San Joaquin River Delta simply because Southern California is remarkably dependent on freshwater exported from the Delta. We offer a new kind of salt barrier, a macroproject built of impermeable textile materials stretched across the Golden Gate beneath the famous bridge. We anticipate it might eventually substitute for a recently proposed San Francisco In-Stream Tidal Power Plant harnessing a 1.7 m tide at the Bay entrance if future climate conditions Statewide is conducive. First-glance physics underpin our macroproject.
Observations of Fallout from the Fukushima Reactor Accident in San Francisco Bay Area Rainwater  [PDF]
Eric B. Norman, Christopher T. Angell, Perry A. Chodash
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0024330
Abstract: We have observed fallout from the recent Fukushima Dai-ichi reactor accident in samples of rainwater collected in the San Francisco Bay area. Gamma ray spectra measured from these samples show clear evidence of fission products – 131,132I, 132Te, and 134,137Cs. The activity levels we have measured for these isotopes are very low and pose no health risk to the public.
Transit Fare Arbitrage: Case Study of San Francisco Bay Area Rapid Transit (BART) System  [PDF]
Asif Haque
Computer Science , 2014,
Abstract: Transit fare arbitrage is the scenario when two or more commuters agree to swap tickets during travel in such a way that total cost is lower than otherwise. Such arbitrage allows pricing inefficiencies to be explored and exploited, leading to improved pricing models. In this paper we discuss the basics of fare arbitrage through an intuitive pricing framework involving population density. We then analyze the San Francisco Bay Area Rapid Transit (BART) system to understand underlying inefficiencies. We also provide source code and comprehensive list of pairs of trips with significant arbitrage gain at github.com/asifhaque/transit-arbitrage. Finally, we point towards a uniform payment interface for different kinds of transit systems.
Prediction of gastrointestinal disease with over-the-counter diarrheal remedy sales records in the San Francisco Bay Area
Michelle L Kirian, June M Weintraub
BMC Medical Informatics and Decision Making , 2010, DOI: 10.1186/1472-6947-10-39
Abstract: Time series models were fit to weekly diarrheal remedy sales and diarrheal illness case counts. Cross-correlations between the pre-whitened residual series were calculated. Diarrheal remedy sales model residuals were regressed on the number of weekly outbreaks and outbreak-associated cases. Diarrheal remedy sales models were used to auto-forecast one week-ahead sales. The sensitivity and specificity of signals, generated by observed diarrheal remedy sales exceeding the upper 95% forecast confidence interval, in predicting weekly outbreaks were calculated.No significant correlations were identified between weekly diarrheal remedy sales and diarrhea illness case counts, outbreak counts, or the number of outbreak-associated cases. Signals generated by forecasting with the diarrheal remedy sales model did not coincide with outbreak weeks more reliably than signals chosen randomly.This work does not support the implementation of syndromic surveillance for gastrointestinal disease with data available though the National Retail Data Monitor.Syndromic surveillance has received much attention as a method for health departments to accelerate the detection of, the reaction to, or the confirmation of disease outbreaks [1,2]. After the publication of reports suggesting that monitoring over-the-counter drug sales might have given advance notice of the 1993 outbreak of cryptosporidiosis in Milwaukee [3-5], federal agencies began to make explicit recommendations that water utilities and health departments consider implementing over-the-counter syndromic surveillance for enhanced waterborne outbreak detection [6-8]. However, the ability of over-the-counter syndromic surveillance to enhance the detection of waterborne disease outbreaks has not been adequately demonstrated [9].In the San Francisco Bay Area, drinking water is provided by the San Francisco Public Utilities Commission (SFPUC) to 2.4 million customers in four counties. Supported by the SFPUC, the San Francisco Department
Phytoplankton communities from San Francisco Bay Delta respond differently to oxidized and reduced nitrogen substrates - even under conditions that would otherwise suggest nitrogen sufficiency  [PDF]
Patricia M. Glibert,Frances P. Wilkerson
Frontiers in Marine Science , 2014, DOI: 10.3389/fmars.2014.00017
Abstract: The effect of equivalent additions of nitrogen (N, 30-40 μM-N) in different forms (ammonium, NH4+, and nitrate, NO3-) under conditions of different light exposure on phytoplankton community composition was studied in a series of four, 5-day enclosure experiments on water collected from the nutrient-rich San Francisco Bay Delta over two years. Overall, proportionately more chlorophyll a and fucoxanthin (generally indicative of diatoms) was produced per unit N taken up in enclosures enriched with NO3- and incubated at reduced (~15% of ambient) light intensity than in treatments with NO3- with high (~60% of ambient) light exposure or with NH4+ under either light condition. In contrast, proportionately more chlorophyll b (generally indicative of chlorophytes) and zeaxanthin (generally indicative of cyanobacteria) was produced in enclosures enriched with NH4+ and incubated under high light intensity than in treatments with low light or with added NO3- at either light level. Rates of maximal velocities (Vmax) of uptake of N substrates, measured using 15N tracer techniques, in all enclosures enriched with NO3- were higher than those enriched with NH4+. Directionality of trends in enclosures were similar to phytoplankton community shifts observed in transects of the Sacramento River to Suisun Bay, a region in which large changes in total N quantity and form occur. These data substantiate the growing body of experimental evidence that dichotomous microbial communities develop when enriched with the same absolute concentration of oxidized vs. reduced N forms, even when sufficient N nutrient was available to the community prior to the N inoculations.
Escape to Alcatraz: evolutionary history of slender salamanders (Batrachoseps) on the islands of San Francisco Bay
I?igo Martínez-Solano, Robin Lawson
BMC Evolutionary Biology , 2009, DOI: 10.1186/1471-2148-9-38
Abstract: There was a high degree of congruence in the results of analyses of nucleotide and allozyme data, both of which strongly support the hypothesis that, for the majority of the islands, salamanders are descended from hilltop populations that became isolated with the formation of the Bay ca. 9,000 years ago. There are two exceptions (Alcatraz and Yerba Buena) where the evidence suggests that salamander populations are wholly or in part, the result of anthropogenic introductions.Comparison of the molecular data and the interpretations drawn therefrom with an earlier morphological study of many of the same salamander populations show some of the same evolutionary trends.In spite of marked differences between the evolutionary rates of the two kinds of molecular markers, both indicate distinctive and similar patterns of population structure for B. attenuatus in the San Francisco Bay Area and its islands. With the two noted exceptions, it is clear that most island populations were established prior to the 9,000 years since the formation of the Bay. Results of coalescence-based analyses suggest that for most island populations the mtDNA lineages from which they were derived date from the Pleistocene.It can be said that, based on observed values of genetic diversity, the last 9,000 years of evolution on these islands have been characterized by relative stability, with the occasional extinction of some haplotypes or alleles that were formerly shared between island and mainland populations but overall maintaining high levels of variation (with the exception of Alcatraz). In contrast, there is some evidence for rapid morphological changes between populations in some islands and their closest mainland counterparts. This pattern of rapid morphological divergence (e. g., resulting from founder effects) is similar to that observed in other studies about recent colonization of island habitats.Islands have long been the subjects of both theoretical and empirical studies in Evolutionary
The Conservation Contributions of Conservation Easements: Analysis of the San Francisco Bay Area Protected Lands Spatial Database
Adena R. Rissman,Adina M. Merenlender
Ecology and Society , 2008,
Abstract: Conservation easements have emerged as an important tool for land trusts and government agencies aiming to conserve private land in the United States. Despite the increase in public investment in conservation easement acquisitions, little is known about their conservation outcomes, particularly at a landscape scale. The nine-county San Francisco Bay Area exemplifies a complex conservation context: 190 organizations hold 24% of the land base in some type of protection status. Using a detailed protected lands database, we compared the contributions of conservation easements and fee-simple protected areas to ecological, agricultural, and public recreation benefits. We found that conservation easements were more likely to conserve grasslands, oak woodlands, and agricultural land, whereas fee-simple properties were more likely to conserve chaparral and scrub, redwoods, and urban areas. Conservation easements contributed to open space connectivity but were unlikely to be integrated into local land-use plans or provide public recreation. In particular, properties held by land trusts were less likely to allow for public recreation than were public lands. Conservation easements held by land trusts and special districts complemented fee-simple lands and provided greater conservation of some ecological communities and agricultural lands than fee-simple properties. Spatial databases of protected areas that include conservation easements are necessary for conservation planning and assessment.
Trends in the sediment yield of the Sacramento River, California, 1957 - 2001
Scott A. Wright,David H. Schoellhamer
San Francisco Estuary and Watershed Science , 2004,
Abstract: Human activities within a watershed, such as agriculture, urbanization, and dam building, may affect the sediment yield from the watershed. Because the equilibrium geomorphic form of an estuary is dependent in part on the sediment supply from the watershed, anthropogenic activities within the watershed have the potential to affect estuary geomorphology. The Sacramento River drains the northern half of California s Central Valley and is the primary source of sediment to San Francisco Bay. In this paper, it is shown that the delivery of suspended-sediment from the Sacramento River to San Francisco Bay has decreased by about one-half during the period 1957 to 2001. Many factors may be contributing to the trend in sediment yield, including the depletion of erodible sediment from hydraulic mining in the late 1800s, trapping of sediment in reservoirs, riverbank protection, altered land-uses (such as agriculture, grazing, urbanization, and logging), and levees. This finding has implications for planned tidal wetland restoration activities around San Francisco Bay, where an adequate sediment supply will be needed to build subsided areas to elevations typical of tidal wetlands as well as to keep pace with projected sea-level rise. In a broader context, the study underscores the need to address anthropogenic impacts on watershed sediment yield when considering actions such as restoration within downstream depositional areas.
Anal Cancer Incidence and Survival: Comparing the Greater San-Francisco Bay Area to Other SEER Cancer Registries  [PDF]
E. Susan Amirian, Paul A. Fickey, Michael E. Scheurer, Elizabeth Y. Chiao
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0058919
Abstract: The incidence of squamous cell carcinoma of the anus, anal canal, and anorectum (SCCA) has increased over time. However, there are still no national guidelines on screening for SCCA among high-risk populations. Providers at University of California, San Francisco have been at the forefront of providing anal dysplasia screening. To determine whether such a screening program allows for earlier detection of abnormalities and consequently, improves patient survival, we conducted an ecological study using data from the Surveillance, Epidemiology, and End Results (SEER) program to compare the San Francisco-Oakland catchment area (SF-O) to other SEER sites where routine screening has not been as accessible. Cox regression models were utilized to assess the impact of residing in the SF-O region, versus other SEER sites, on cause-specific mortality hazard. Logistic regression was used to determine if site was associated with the probability of having an in situ versus invasive tumor among SCCA cases. All analyses were stratified on calendar time (1985–1995 and 1996–2008) to compare differences pre- and post- highly active anti-retroviral therapy. Among SCCA cases, being reported by the SF-O registry was associated with a four fold higher probability of having an in situ tumor (rather than an invasive tumor) [95% CI: 3.48–4.61], compared to sites outside of California, between 1996 and 2008. Cases reported from the SF-O region between 1996 and 2008 had a 39% lower mortality risk than those reported from registries outside California (95% CI: 0.51–0.72). However, there was no decrease in the rate of invasive SCCA over this period. This is the first ecological study to evaluate whether access to anal cancer screening programs may help improve patient survival by allowing for earlier detection of lesions. Our results imply that routine screening programs may help detect SCCA at an earlier stage and thus, potentially impact patient survival.
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