Formation of liquid menisci in flexible nanochannels

This paper describes the elasto-capillary formation of menisci at the liquid-air interface in nanochannels that are covered with flexible capping membranes. The equilibrium between the capillary pressure in the fluid and the membrane bending results in a very peculiar shape of the meniscus. We present an analytical description of these meniscus hapes and show that the protrusion length of the meniscus along the channel is an accurate measure for the deflection of the nanochannels

OPPORTUNITY COSTS, SHARE LEASING, AND PREVENTED PLANTING CLAIMS IN CROP INSURANCE

This paper determines whether the opportunity costs of share leasing and the share amounts of farmers/tenants affect the likelihood of submitting a prevented planting claim. Results from our probit analysis shows that lower opportunity costs of share leasing and higher farmer/tenant share amount can increase the probability of submitting a prevented planting. These results have potential implications for setting prevented planting buy-up rates and crop insurance compliance procedures.Risk and Uncertainty,

Elastocapillary filling of deformable nanochannels

The capillary filling speed of wetting liquids of varying viscosity and surface tension in hydrophilic nanochannels with an elastic capping layer has been analyzed. The channels, with a height just below 80 nm, are suspended by a thin flexible membrane that easily deforms due to the negative pressure which develops behind the moving meniscus. In the elastocapillary filling of the channels, two opposite effects compete: the decreased cross channel sections increase the flow resistance, while the Laplace pressure that acts as the driving force becomes more negative due to the increased meniscus curvature. Although the meniscus position shows a square root of time behavior as described by the Washburn relation, the net result of the induced bending of the membranes is a definite increase of the filling speed. We propose a relatively straightforward model for this elastocapillary process and present experimental results of the filling speed of ethanol, water, cyclohexane and acetone that are found to be in good agreement with the presented model, for membrane deflections of up to 80 percent of the original channel height

The Impact of Labor Constraints on the Farm Performance

Stricter immigration policies that affect an estimated 12 million unauthorized immigrants, 40% of whom are hired as farm workers, can potentially leave the highly labor-dependent organic farms more economically vulnerable. The displacement of unauthorized immigrants will expectedly create labor shortages. This study analyzes the impact of hiring constraints and changes in farm labor market conditions (due to stricter immigration policies) on the technical efficiency and financial performance of organic and conventional farms. A production function approach is used to analyze survey data that has a mix of organic and conventional farms in the Southeast region. Adjustment strategies to deal with labor shortage and providing workers with nonwage incentives have been determined to be an important determinant of farm income. Among the strategies, adjustment of wage and nonwage benefits were found to be the most effective but a combination of strategies is the most preferred approach to deal with labor shortage. Furthermore, we found productivity difference between farmers with labor shortage adjustment strategies and those who do not.Agricultural Finance, Production Economics, Productivity Analysis,

The asymmetric profile of the H76 alpha line emission from MWC349

MWC349 is an emission-line star found by Merrill, Humason and Burwell (1932). Braes, Habing and Schoenmaker (1972) discovered that it is a strong radio source. The radio emission originates in a massive ionized wind that is expanding with a velocity of about 50 km s(-1). Its continuum spectrum fits well a nu(0.6) power law from the cm wavelengths to the far-IR. Radio recombination line emission from the envelope of MWC349 was first detected by Altenhoff, Strittmatter and Wendker (1981). We have obtained good signal-to-noise ratio, Very Large Array observations of the H76 alpha radio recombination line from the ionized wind of MWC349. Our data reveal that the profile is markedly asymmetric, with a steep rise on the blue side. This asymmetry could be due to non-LTE effects in the formation and transfer of the line or to intrinsic asymmetries in the envelope. Our analysis suggests that most probably the peculiar profile is caused by a non-LTE enhancement of the line emission from the side of the envelope nearer to the observer. This asymmetry has the opposite sense than that observed in optical and IR recombination lines, where a different effect (absorption of the stellar continuum by the gas in the wind between the star and the observer) is known to be dominant, leading to the classic P Cygni profile. We propose that the profiles of the radio recombination lines from ionized stellar winds will have this characteristic shape, while optical and IR recombination lines are characterized by P Cygni-like profiles. Unfortunately, at present the detection of radio recombination lines from ionized stellar winds is only feasible for MWC349 and a few other objects

A Farm-level Approach to the Methyl Bromide Phase-out: Identifying Alternatives and Maximizing Net Worth Using Stochastic Dominance and Optimization Procedures.

Alternative fumigant and herbicide systems for Georgia's pepper farms are analyzed relative to soon-to-be phased-out methyl bromide system. Stochastic dominance analyses identify two alternatives exceeding MeBr's yield and financial efficiency. A programming model using simulation-optimization techniques provides important implications on the pepper farms' economic viability under these alternative systems.Crop Production/Industries,