A vapor barrier for cold testing printed circuit cards

Cold testing method prevents formation of frost on printed circuit boards and part holders during testing at sub-zero temperatures. Freon permits rapid attainment of the required testing temperature

EXPLAINING THE ADOPTION AND DISADOPTION OF SUSTAINABLE AGRICULTURE: THE CASE OF COVER CROPS IN NORTHERN HONDURAS

Although technology adoption has been the subject of a great deal of economic research, that focused on the economics of adoption of low-input "sustainable" systems has been much more limited and recent. This paper attempts to explain the recent decline in the use of cover crops using in maize farming in the Department of Atlantida, Honduras. In the early 1970's, farmers in the region began rotating maize with the velvetbean (mucuna ssp.), a system learned from Guatemalan immigrants. Tohe mucuna-maize system decreased the labor required for maize farming even as it increased yields, prevented erosion, and conferred a variety of other agronomic benefits. By 1992, estimates show that the system had diffused among more than 60% of farmers in the Department. Both due to this widespread dissemination, and the fact that diffusion was largely spontaneous (unassisted by extensions and NGOs), the maize-mucuna system has become a widely acknowledged "success story" of sustainable agriculture diffusion. However, recent anecdotal evidence, confirmed by the survey research reported here, shows that by the late 1990s, use of the system had begun to decline sharply. Various hypotheses about the cause of this decline were investigated in this research, including whether the abandonment of the mucuna-maize system is attributable to a generalized decline in maize cultivation, changes in land tenure and distribution, a burgeoning cattle industry, infrastructural improvements, widespread infestations of noxious weed (rottboellia cochinchinensis), or limitations in farmer management. Modeling techniques evaluated two land-use decisions: whether to adopt mucuna-maize and the contingent decision of whether to abandon the system, once adopted. Bivariate probit analysis is used in the econometric analysis. Descriptive statistics and econometric results indicate that age, level of income from non-maize sources, the presence of rottboellia, and access to a road or highway are significantly related to the abandonment of overcropping. Meanwhile, greater dedication to maize, diversification into high value crops, greater experience with the system, and annual reseeding of mucuna are associated with continued use of the mucuna-maize rotation. The empirical results overall demonstrate that the phenomenon of maize-muchuna adoption and abandonment is a highly complex process. The results have policy implications for the "farmer to farmer" model of extension as well as the promotion of mucuna-maize as a sustainable agriculture technique. In the first case, less emphasis on diffusion and greater attention to farmer-to-farmer teaching of crop system dynamics may be important for the durability of cover crop systems. Regarding the second, cover crop species like mucuna should not be viewed as "silver bullet" solution to sustaining low-input agriculture: indeed, exclusive rotation of mucuna with maize may eliminate critical sources of plant and animal species diversity, ultimately undermining the system itself.International development, Sustainable agriculture, Adoption, Disadoption, Farmer management, Crop Production/Industries,

Entanglement in quantum catastrophes

We classify entanglement singularities for various two-mode bosonic systems in terms of catastrophe theory. Employing an abstract phase-space representation, we obtain exact results in limiting cases for the entropy in cusp, butterfly, and two-dimensional catastrophes. We furthermore use numerical results to extract the scaling of the entropy with the non-linearity parameter, and discuss the role of mixing entropies in more complex systems.Comment: 7 pages, 3 figure

Perspectives on radioactive waste disposal: A consideration of economic efficiency and intergenerational equity

There are both internal and external pressures on the U.S. Department of Energy to reduce the estimated costs of isolating radioactive waste, $19 billion for transuranic waste at Waste Isolation Pilot Plant (WIPP) and$57 billion for high level waste at Yucca Mountain. The question arises whether economic analyses would add to the decision-making process to reduce costs yet maintain the same level of radiological protection. This paper examines the advantages and disadvantages of using cost-benefit analysis (CBA), a tool used to measure economic efficiency as an input for these decisions. Using a comparative research approach, we find that CBA analyses appear particularly applicable where the benefits and costs are in the near term. These findings can help policymakers become more informed on funding decisions and to develop public confidence in the merits of the program for waste disposal

Supernova Constraints and Systematic Uncertainties from the First Three Years of the Supernova Legacy Survey

We combine high-redshift Type Ia supernovae from the first three years of the Supernova Legacy Survey (SNLS) with other supernova (SN) samples, primarily at lower redshifts, to form a high-quality joint sample of 472 SNe (123 low-z, 93 SDSS, 242 SNLS, and 14 Hubble Space Telescope). SN data alone require cosmic acceleration at >99.999% confidence, including systematic effects. For the dark energy equation of state parameter (assumed constant out to at least z = 1.4) in a flat universe, we find w = –0.91^(+0.16)_(–0.20)(stat)^(+0.07)_(–0.14)(sys) from SNe only, consistent with a cosmological constant. Our fits include a correction for the recently discovered relationship between host-galaxy mass and SN absolute brightness. We pay particular attention to systematic uncertainties, characterizing them using a systematic covariance matrix that incorporates the redshift dependence of these effects, as well as the shape-luminosity and color-luminosity relationships. Unlike previous work, we include the effects of systematic terms on the empirical light-curve models. The total systematic uncertainty is dominated by calibration terms. We describe how the systematic uncertainties can be reduced with soon to be available improved nearby and intermediate-redshift samples, particularly those calibrated onto USNO/SDSS-like systems

Effect of ageing on phase evolution and mechanical properties of a high tungsten super-duplex stainless steel

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