TRANSPORTATION COSTS IN ECONOMETRIC MODELS OF STATE AGRICULTURAL SECTORS: THE CASE OF BEEF IN HAWAII

Econometric models designed to show how national policies affect state agricultural sectors often use national prices as proxies for state prices. Consequently, they ignore the influence of freight rates on state production. An application to the Hawaii beef industry demonstrates that both freight rates and national beef prices have important impacts on Hawaii beef prices and production. By using state prices rather than national prices, error from changes in freight rates might be reduced, and the model's capacity for policy analysis might be broadened.Livestock Production/Industries,

Video Evidence That London Infants Can Resettle Themselves Back to Sleep After Waking in the Night, as well as Sleep for Long Periods, by 3 Months of Age

Objective: Most infants become settled at night by 3 months of age, whereas infants not settled by 5 months are likely to have long-term sleep-waking problems. We assessed whether normal infant development in the first 3 months involves increasing sleep-period length or the ability to resettle autonomously after waking in the night. Methods: One hundred one infants were assessed at 5 weeks and 3 months of age using nighttime infrared video recordings and parental questionnaires. Results: The clearest development was in sleep length; 45% of infants slept continuously for 5 hours or more at night at 3 months compared with 10% at 5 weeks. In addition, around a quarter of infants woke and resettled themselves back to sleep in the night at each age. Autonomous resettling at 5 weeks predicted prolonged sleeping at 3 months suggesting it may be a developmental precursor. Infants reported by parents to sleep for a period of 5 hours or more included infants who resettled themselves and those with long sleeps. Three-month olds fed solely breast milk were as likely to self-resettle or have long sleep bouts as infants fed formula or mixed breast and formula milk. Conclusions: Infants are capable of resettling themselves back to sleep in the first 3 months of age; both autonomous resettling and prolonged sleeping are involved in “sleeping through the night” at an early age. Findings indicate the need for physiological studies of how arousal, waking, and resettling develop into sustained sleeping and of how environmental factors support these endogenous and behavioral processes

Consideration of computer limitations in implementing on-line controls

A formal statement of the optimal control problem which includes the interval of dicretization as an optimization parameter, and extend this to include selection of a control algorithm as part of the optimization procedure, is formulated. The performance of the scalar linear system depends on the discretization interval. Discrete-time versions of the output feedback regulator and an optimal compensator, and the use of these results in presenting an example of a system for which fast partial-state-feedback control better minimizes a quadratic cost than either a full-state feedback control or a compensator, are developed

PLANT NUTRIENT DEMAND FUNCTIONS FOR TENNESSEE WITH PRICES OF JOINTLY APPLIED NUTRIENTS

Several studies have estimated plant nutrient demand functions for nitrogen, phosphate, and potash. All included own-price effects but excluded prices of jointly applied nutrients. In this study, nutrient demand functions, which include prices of all three nutrients, are estimated for Tennessee by seemingly unrelated regression. Results suggest that cross-price effects are important in determining plant nutrient demand, at least in the case of Tennessee, and that multicollinearity need not be a hindrance in all cases to including cross-price effects in plant nutrient demand models.Crop Production/Industries,

Probing States in the Mott Insulator Regime

We propose a method to probe states in the Mott insulator regime produced from a condensate in an optical lattice. We consider a system in which we create time-dependent number fluctuations in a given site by turning off the atomic interactions and lowering the potential barriers on a nearly pure Mott state to allow the atoms to tunnel between sites. We calculate the expected interference pattern and number fluctuations from such a system and show that one can potentially observe a deviation from a pure Mott state. We also discuss a method in which to detect these number fluctuations using time-of-flight imaging.Comment: 4 pages, 3 figures. Send correspondence to [email protected]

Reservation Wages, Labour Market Participation and Health

The concept of the reservation wage has played an important role in labour market theory; particularly in models of job search, labour supply and labour market participation. Despite this core theoretical role, there is a scarcity of empirical research which explores the setting of reservation wages at the individual level. In this paper, we focus on the determinants of reservation wages, with a particular focus on health, which has attracted very little attention despite its importance from a policy perspective. We use data for males from 14 waves of the British Household Panel Survey and estimate an endogenous switching model which predicts reservation wages for the unemployed and market wages for the employed. We employ methods to deal with the endogeneity of health, measurement errors in our self reported health variable and selection into economic activity. Our results suggest that health is an important determinant of selection, both into economic activity and into employment (versus unemployment) but that, once these participation effects are accounted for, health is not a significant determinant of either the reservation wage or the market wage. This casts doubt on the results of a number of previous studies that have failed to appropriately account for selection in models of male wages. Our results have important policy implications since they suggest that poor health is a major cause of economic inactivity

Initial Condition Sensitivity of Global Quantities in Magnetohydrodynamic Turbulence

In this paper we study the effect of subtle changes in initial conditions on the evolution of global quantities in two-dimensional Magnetohydrodynamic (MHD) turbulence. We find that a change in the initial phases of complex Fourier modes of the Els\"{a}sser variables, while keeping the initial values of total energy, cross helicity and Alfv\'{e}n ratio unchanged, has a significant effect on the evolution of cross helicity. On the contrary, the total energy and Alfv\'{e}n ratio are insensitive to the initial phases. Our simulations are based on direct numerical simulation using the pseudo-spectral method.Comment: 12 pages LateX, 11 ps figures. Accepted for publication by Physics of Plasma

The gender reservation wage gap: evidence from British panel data

Our findings suggest the existence of a gender reservation wage gap, with a differential of around 10%. The presence of children, particularly pre-school age children, plays an important role in explaining this differential. For individuals without children, the explained component of the differential is only 5%, which might indicate that perceived discrimination in the labour market influences the reservation wage setting of females