The Supply Of Community Supported Agriculture

Community Supported Agriculture (CSA) has undergone both a rapid increase in growth and interest over the last two decades.  As such, the amount of literature on the subject has also increased.  However, there are few, if any, theoretical models of supply for CSA memberships (shares) that have been developed from CSA farm data.  This paper uses both survey and anecdotal data from the Roxbury Biodynamic Farm, one of the largest CSA in the United States, to present a theory of supply for CSA membership.  Included in the discussion is the consideration that CSA farms are not profit maximizing and that the farmers (i.e. the suppliers) knowingly take on the responsibilities and earnings associated with a CSA

The Demand For Community Supported Agriculture

Community Supported Agriculture (CSA) has undergone both a rapid increase in growth and interest over the last decade.  As such, the amount of literature on the subject has also increased.  However, there are few, if any, theoretical models of demand on CSA that have been developed from membership data. This paper uses both survey and anecdotal data of members of the Roxbury Biodynamic Farm, the second largest CSA in the United States, to present a theory of demand for CSA membership. Included in the discussion is consideration of the evidence that there is a direct relationship between production method and demand, usually a shibboleth in traditional economic analysis. Further exploration considers the possibility that over time participation influences the very nature of demand for CSA membership, and hypothesizes that this dynamic demand is a necessary but insufficient condition for the sustainability of CSA

A comparison of methods for the measurement of the absorption coefficient in natural waters

In the spring of 1992 an optical closure experiment was conducted at Lake Pend Oreille, Idaho. A primary objective of the experiment was to compare techniques for the measurement of the spectral absorption coefficient and other inherent optical properties of natural waters. Daily averages of absorption coefficients measured using six methods are compared at wavelengths of 456, 488, and 532 nm. Overall agreement was within 40% at 456 nm and improved with increasing wavelength to 25% at 532 nm. These absorption measurements were distributed over the final 9 days of the experiment, when bio-optical conditions in Lake Pend Oreille (as indexed by the beam attenuation coefficient cp(660) and chlorophyll a fluorescence profiles) were representative of those observed throughout the experiment. However, profiles of stimulated chlorophyll a fluorescence and beam transmission showed that bio-optical properties in the lake varied strongly on all time and space scales. Therefore environmental variability contributed significantly to deviations between daily mean absorption coefficients measured using the different techniques

Incidence and Tracking of Escherichia coli O157:H7 in a Major Produce Production Region in California

Fresh vegetables have become associated with outbreaks caused by Escherichia coli O157:H7 (EcO157). Between 1995–2006, 22 produce outbreaks were documented in the United States, with nearly half traced to lettuce or spinach grown in California. Outbreaks between 2002 and 2006 induced investigations of possible sources of pre-harvest contamination on implicated farms in the Salinas and San Juan valleys of California, and a survey of the Salinas watershed. EcO157 was isolated at least once from 15 of 22 different watershed sites over a 19 month period. The incidence of EcO157 increased significantly when heavy rain caused an increased flow rate in the rivers. Approximately 1000 EcO157 isolates obtained from cultures of>100 individual samples were typed using Multi-Locus Variable-number-tandem-repeat Analysis (MLVA) to assist in identifying potential fate and transport of EcO157 in this region. A subset of these environmental isolates were typed by Pulse Field Gel Electrophoresis (PFGE) in order to make comparisons with human clinical isolates associated with outbreak and sporadic illness. Recurrence of identical and closely related EcO157 strains from specific locations in the Salinas and San Juan valleys suggests that transport of the pathogen is usually restricted. In a preliminary study, EcO157 was detected in water at multiple locations in a low-flow creek only within 135 meters of a point source. However, possible transport up to 32 km was detected during periods of higher water flow associated with flooding. During the 2006 baby spinach outbreak investigation, transport was also detected where water was unlikely to be involved. These results indicate that contamination of the environment is a dynamic process involving multiple sources and methods of transport. Intensive studies of the sources, incidence, fate and transport of EcO157 near produce production are required to determine the mechanisms of pre-harvest contamination and potential risks for human illness

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Implications of Water Scarcity for Water Productivity and Farm Labor

Increasing water scarcity causes a variety of pressures on agricultural production given current and growing food demands. This paper seeks to add to our understanding of water scarcity adaptations by explicitly addressing linkages between water scarcity, water productivity, cropping choices, and farm labor. We challenge the widespread claim that tightening foreign (especially Mexican) labor supply will necessarily result in less labor-intensive crop choices. Instead, by linking water scarcity and farm labor through the lens of water productivity we illustrate scenarios under which climate and technological change result in greater future labor demand in agriculture, including temporary and seasonal workers, largely due to water productivity increases resulting from switching to more labor-intensive crops. We conclude that a focus on crop choices is central to understanding changes in water productivity, labor demand, and technological innovations in response to water scarcity