Effect of nutrients and inoculum quantity on Pythium ultimum infection of cotton hypocotyls

Seedling disease, caused by Pythium ultimum Trow., is one of the most destructive disease of cotton in Tennessee. The objective of this study was to evaluate the effect of the nutritional status of the pathogen on infection and disease development. The nutritional status of Pythium ultimum mycelium used to inoculate cotton hypocotyls was varied by inoculating the pathogen on agar media containing various concentrations of nutrients. Sucrose, nitrate-nitrogen, ammonium-nitrogen and potassium in agar media were found to significantly affect vegetative growth and pathogenicity. Disease was more severe when inocula were grown on media with medium to high levels of these materials than when grown on media with low levels. Magnesium and phosphate at low or high levels in agar media did not affect pathogenicity . The pathogen grown on a nitrate-nitrogen medium produced significantly more severe disease than when grown on an ammonium-nitrogen medium. Light transmission through blended agar cultures was used as a measure of inoculum quantity. There was a significant positive correlation among three factors: levels of sucrose, nitrogen, or potassium in the culture media, inoculum quantity, and disease severity. In liquid media, Pythium ultimum became progressively more virulent as the concentration of nitrogen or sucrose was increased, but the weight of the hyphae increased sharply to a maxium at low to median levels of these nutrients. Nitrogen or carbohydrate deficient hyphae produced as much disease as did non-deficient hyphae, provided that the quantities of inocula were similar. These results emphasize that sources of nutrients and the capacity of the pathogen to utilize these materials are important considerations in understanding disease development in nature

A RISK PROGRAMMING APPROACH TO DESIGNING CONTRACTS TO REDUCE NITRATE LEACHING

As contractual agriculture expands, contract design offers a non-regulatory opportunity to reduce non-point source pollution. A risk programming analysis of seed corn contract designs illustrates a tractable empirical principal-agent model, and shows that grower risk preferences affect contract acceptability and efficiency at reducing nitrate leaching.Environmental Economics and Policy, Risk and Uncertainty,

Fair trade in insurance industry: Premium determination of Taiwan automobile insurance

This paper examines premium determination of voluntary automobile insurance policy and risk classification under a heavily regulated rating system in Taiwan. We investigate the distribution of actual premium and pure premium, based on unique data to test if premium reflect appropriate gender-age factor. The reasonableness of loading and the difference in driving exposure between policyholder and driver are investigated for three different types of policy. An adjustment of gender-age premium coefficients is called for

Star Formation in the LMC: Gravitational Instability and Dynamical Triggering

Evidence for triggered star formation is difficult to establish because energy feedback from massive stars tend to erase the interstellar conditions that led to the star formation. Young stellar objects (YSOs) mark sites of {\it current} star formation whose ambient conditions have not been significantly altered. Spitzer observations of the Large Magellanic Cloud (LMC) effectively reveal massive YSOs. The inventory of massive YSOs, in conjunction with surveys of interstellar medium, allows us to examine the conditions for star formation: spontaneous or triggered. We examine the relationship between star formation and gravitational instability on a global scale, and we present evidence of triggered star formation on local scales in the LMC.Comment: 6 pages, 6 figures, IAU Symposium 237, Triggered Star Formation in a Turbulent Medium, eds. Elmegreen and Palou

Ultracold molecules: vehicles to scalable quantum information processing

We describe a novel scheme to implement scalable quantum information processing using Li-Cs molecular state to entangle $^{6}$Li and $^{133}$Cs ultracold atoms held in independent optical lattices. The $^{6}$Li atoms will act as quantum bits to store information, and $^{133}$Cs atoms will serve as messenger bits that aid in quantum gate operations and mediate entanglement between distant qubit atoms. Each atomic species is held in a separate optical lattice and the atoms can be overlapped by translating the lattices with respect to each other. When the messenger and qubit atoms are overlapped, targeted single spin operations and entangling operations can be performed by coupling the atomic states to a molecular state with radio-frequency pulses. By controlling the frequency and duration of the radio-frequency pulses, entanglement can either be created or swapped between a qubit messenger pair. We estimate operation fidelities for entangling two distant qubits and discuss scalability of this scheme and constraints on the optical lattice lasers

Recurrence and the shadowing property

AbstractIn this paper, we study the relationship between the recurrent set and the shadowing property. We give a necessary condition for a homeomorphism restricted to its nonwandering set to have the shadowing property. Also, we consider a condition for an arbitrary homeomorphism to be a nonwandering homeomorphism. Finally, we consider homeomorphisms which cannot have the shadowing property