SUBJECTIVE PRODUCTION FUNCTION PARAMETERS AND RISK: WHEAT PRODUCTION IN TUNISIA

This paper focuses on the problem of decision making when the parameters of the underlying technology are either unknown or are not known with certainty by producers. This problem is considered within the context of Tunisian durum wheat production in Northern Tunisia where farmers ability to accurately perceive the input-output characteristics of both old and new varieties is important to increasing allocative efficiency, decreasing subject risk and encouraging the adoption of high yielding varieties under uncertain climatic conditions.Crop Production/Industries,

Wheat, Allocative Error and Risk: Northern Tunisia

Crop Production/Industries,

External impacts on internal dynamics: Effects of paleoclimatic and demographic variability on acorn exploitation along the Central California coast

book chapterResearch into human-environment interaction in California prehistory often focuses on either the internal dynamics of adaptive decisions or the external impacts of environmental change. While both processes were surely driving prehistoric variability, integrating these approaches is not altogether straightforward. Here we outline an inclusive approach examining the exploitation of acorn habitats in Central California. Acorns were critically important to many ethnographic groups in Native California, but the intensive use of acorns appears to be a Late Holocene phenomenon. Most research approaches the increased reliance on acorns as a process governed by internal dynamics linked to demographically-driven resource intensification, but there are strong reasons to believe that climatic variability also structured acorn use. Here we link internal and external human-environmental dynamics through a formal behavioral ecological model. This model provides clear predictions that can be used to identify departures from expected internal dynamics linked to external factors driven by paleoenvironmental change. Results show that prehistoric occupation along the central California coast shifts into interior oak-dominated regions with increasing population densities, consistent with model expectations of internally-driven resource intensification. However, acorn use is also affected by climate: foragers are less likely to live in productive acorn habitats during periods of drought. These findings show that neither internal nor external patterns can completely account for variability in prehistoric decisions, but that integrating these through formal ecological models can provide insights into the external impacts on internal dynamics that structure broad patterns in prehistory

Environmental productivity predicts migration, demographic, and linguistic patterns in prehistoric California

Global patterns of ethnolinguistic diversity vary tremendously. Some regions show very little variation even across vast expanses, whereas others exhibit dense mosaics of different languages spoken alongside one another. Compared with the rest of Native North America, prehistoric California exemplified the latter. Decades of linguistic, genetic, and archaeological research have produced detailed accounts of the migrations that aggregated to build California’s diverse ethnolinguistic mosaic, but there have been few have attempts to explain the process underpinning these migrations and why such a mosaic did not develop elsewhere. Here we show that environmental productivity predicts both the order of migration events and the population density recorded at contact. The earliest colonizers occupied the most suitable habitats along the coast, whereas subsequent Mid–Late Holocene migrants settled in more marginal habitats. Other Late Holocene patterns diverge from this trend, reflecting altered dynamics linked to food storage and increased sedentism. Through repeated migration events, incoming populations replaced resident populations occurring at lower densities in lower-productivity habitats, thereby resulting in the fragmentation of earlier groups and the development of one of the most diverse ethnolinguistic patterns in the Americas. Such a process may account for the distribution of ethnolinguistic diversity worldwide

Trans-Holocene Marine Mammal Exploitation on San Clemente Island, California: A Tragedy of the Commons Revisited

Occupied from ca. 7040 B.C. to AD. 1400, the Eel Point Site (CA-SCLI-43) on San Clemente Island, California represents one of the longest sequences of near-continuous marine resource exploitation on the west coast of North America. Faunal remains suggest transitions from heavy exploitation of fur seals and sea lions during the early Holocene, to increased hunting of cetaceans at mid-Holocene, to a focus on sea otters and fish during the late Holocene. These trends are consistent with patterns of overexploitation and economic intensification on the California and Oregon mainland, but they also suggest watercraft-based hunting earlier on the island than elsewhere. Fur seal and sea lion bones mainly represent females and juveniles, indicating that exploitation of island rookeries was guided more by self-interest than by principles of game conservation. Two intervals of temporary site abandonment, ca. 6150-3970 B.C. and AD. 1020-1400, were both followed by periods of increased marine mammal exploitation and may reflect intervals during which marine mammal populations rebounded. Broad-scale diachronic trends in the zooarchaeological remains do not correlate with flux in paleo-sea temperatures and are best interpreted as products of overhunting and increased use of watercraft over time

Ohio Livestock Waste Management Guide

PDF pages: 3

Study of fuel cells using storable rocket propellants Final report, 28 Jan. 1964 - 29 Jan. 1965

Fuel cells using storable rocket propellants for reactant

Is Your Neighborhood Designed to Support Physical Activity? A Brief Streetscape Audit Tool.

INTRODUCTION:Macro level built environment factors (eg, street connectivity, walkability) are correlated with physical activity. Less studied but more modifiable microscale elements of the environment (eg, crosswalks) may also affect physical activity, but short audit measures of microscale elements are needed to promote wider use. This study evaluated the relation of a 15-item neighborhood environment audit tool with a full version of the tool to assess neighborhood design on physical activity in 4 age groups. METHODS:From the 120-item Microscale Audit of Pedestrian Streetscapes (MAPS) measure of street design, sidewalks, and street crossings, we developed the 15-item version (MAPS-Mini) on the basis of associations with physical activity and attribute modifiability. As a sample of a likely walking route, MAPS-Mini was conducted on a 0.25-mile route from participant residences toward the nearest nonresidential destination for children (n = 758), adolescents (n = 897), younger adults (n = 1,655), and older adults (n = 367). Active transportation and leisure physical activity were measured with age-appropriate surveys, and accelerometers provided objective physical activity measures. Mixed-model regressions were conducted for each MAPS item and a total environment score, adjusted for demographics, participant clustering, and macrolevel walkability. RESULTS:Total scores of MAPS-Mini and the 120-item MAPS correlated at r = .85. Total microscale environment scores were significantly related to active transportation in all age groups. Items related to active transport in 3 age groups were presence of sidewalks, curb cuts, street lights, benches, and buffer between street and sidewalk. The total score was related to leisure physical activity and accelerometer measures only in children. CONCLUSION:The MAPS-Mini environment measure is short enough to be practical for use by community groups and planning agencies and is a valid substitute for the full version that is 8 times longer