13,530 research outputs found
Cheap Food Policy: Fact or Rhetoric?
The term "cheap food policy" has frequently been used as a descriptor for U.S. commodity programs by those who contend these payments to farmers ultimately result in lower food costs for consumers. More recently, farm policy has been criticized for contributing to the obesity problem in the U.S. by making large quantities of fattening foods widely available and relatively inexpensive. This paper econometrically evaluates the impact of direct government payments to farmers from 1960-1999 on the proportion of disposable income consumers spend on food. The model finds the payments do not significantly affect the affordability of food.Agricultural and Food Policy,
FARM PROGRAM PAYMENTS AND ECONOMIES OF SCALE
Economies of scale are investigated and the impacts of farm payment limitations for producers of cotton and soybeans in Mississippi are evaluated. Limits proposed by the Senate following the recent farm bill debate are overlaid on estimates of the scale economies for the cost of producing these crops to determine the different impacts on farm efficiency and welfare benefits.Agricultural and Food Policy,
Effect of Phenolic Matrix Microcracking on the Structural Response of a 3-D Woven Thermal Protection System
The effect of microcracking in the phenolic matrix of a three-dimensional woven thermal protection system (TPS) and the resulting material stiffness reduction was studied via a comparison of finite element analysis results from a linear analysis and an iterative linear analysis. A TPS is necessary to protect space vehicles from the aerodynamic heating of planetary entry. The Heatshield for Extreme Entry Environment Technology (HEEET) project has developed a TPS for use in high heat-flux and pressure missions. The material is a dual-layer continuous dry weave, which is then infiltrated with a low-density phenolic resin matrix to form a rigid ablator. The phenolic resin matrix does not have structural load transfer requirements, and testing has shown that the phenolic resin can fully satisfy thermal requirements when the matrix contains microcracks. Due to high stresses in the through-the-thickness direction of the material, phenolic microcracks may form in the matrix material, which would result in a reduction of stiffness. An exploratory study was conducted to determine if reduction in material stiffness would change the load paths and/or decrease the structural margins. A comparison was performed between a linear finite element analysis that did not take into account phenolic microcracking and an iterative linear finite element analysis that accounted for propagation of phenolic microcracking. Four subcases using varying assumptions were analyzed and the results indicate that the assumed strength at which the phenolic microcracking propagates was the critical parameter for determining the extent of microcracking in the phenolic matrix. Phenolic microcracking does not have an adverse effect on the structural response of the test article and is not a critical failure
Can the mid-Holocene provide suitable models for rewilding the landscape in Britain?
Palaeoecologists have been encouraging us to think about the relevance of the Holocene fossil record for nature conservation for many years (e.g. Buckland 1993) but this information seems slow to filter through to the conservation community. Indeed, Willis et al. (2005) report
that recently published biodiversity reports and policy documents rarely look back more than 50 years and may ignore the historical context entirely. This has been a lost opportunity for understanding ecological systems. Many natural processes occur over timescales that confound our attempts to understand them, so the vast temporal
perspective provided by palaeoecological studies
can provide important guidance for nature conservation
(Willis & Birks 2006).
However, accurate vegetation mapping is difficult enough in modern landscapes (Cherrill & McLean 1999), so the challenge of describing prehistoric environments is immeasurably greater.
Nevertheless, pioneering work in the mid 20th century showed that pollen and spores extracted from peat bogs were so perfectly preserved thatthey could be used to demonstrate sequences of vegetation change since the last glaciation
(Godwin 1956). Since then, the science has
burgeoned: ancient deposits of beetles, snails,
fungal spores and plant macrofossils add to the
picture, as does the chemistry of ancient lake sediments
(Bell & Walker 2004).
Many questions still remain to be answered by this fascinating research and one aspect has received considerable attention in the last decade.
This concerns the nature of the ‘primeval’ landscapes,
in other words our understanding of natural systems prior to significant human impact. The debate was kindled by a thesis by the Dutch forest ecologist Frans Vera in 2000 (see also Vera & Buissink 2007). Vera effectively challenged established views about the primeval landscapes and argued that the refutation, and the resulting alternative landscape models, had critical importance
for modern conservation practice.
Vera’s thesis is focused on the pre-Neolithic (ca 8000-5000bp) landscape in the lowlands of central and western Europe, with the assumption that this period represents an almost pristine or ‘natural’ state which should provide a suitable conservation benchmark. Vera contends (i) that
this landscape was not closed woodland but a relatively
open park-like mosaic of wood and grassland,and (ii) that large wild herbivores were an essential driving force behind woodland-grassland vegetation cycles. The advocacy in his argument and the timing of the publication, when grazingwas seen as increasingly important in conservation
in Europe, have combined to raise the profile
of this issue. If Vera is correct, the open park-like
landscapes were inherited rather than created by
people; this may have implications for conservation
practice in Europe.
The adoption of Vera’s ideas into conservation
management plans in the UK (see Box 1) gives an
indication of the influence that this work has had.
Indeed, Vera’s ideas have been described as a ‘challenge
to orthodox thinking’ (Miller 2002) and considerable debate has been stimulated centering
on the ecological validity of Vera’s hypothesis
and its relevance for modern conservation.
In this article, we attempt to address these issues
on the basis of results from a literature review,
web-debate and discussions with Dutch and British
ecologists, prepared for English Nature with a
view to informing conservation strategies (Hodder
& Bullock 2005a)
MEASUREMENT OF PRICE RISK IN REVENUE INSURANCE: IMPLICATIONS OF DISTRIBUTIONAL ASSUMPTIONS
A variety of crop revenue insurance programs have recently been introduced. A critical component of revenue insurance contracts is quantifying the risk associated with stochastic prices. Forward-looking, market-based measures of price risk which are often available in form of options premia are preferable. Because such measures are not available for every crop, some current revenue insurance programs alternatively utilize historical price data to construct measures of price risk. This study evaluates the distributional implications of alternative methods for estimating price risk and deriving insurance premium rates. A variety of specification tests are employed to evaluate distributional assumptions. Conditional heteroskedasticity models are used to determine the extent to which price distributions may be characterized by nonconstant variances. In addition, these models are used to identify variables which may be used for conditioning distributions for rating purposes. Discrete mixtures of normals provide flexible parametric specifications capable of recognizing the skewness and kurtosis present in commodity pricesRisk and Uncertainty,
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