Capillary acquisition devices for high-performance vehicles: Executive summary

Technology areas critical to the development of cryogenic capillary devices were studied. Passive cooling of capillary devices was investigated with an analytical and experimental study of wicking flow. Capillary device refilling with settled fluid was studied using an analytical and experimental program that resulted in successful correlation of a versatile computer program with test data. The program was used to predict Centaur D-1S LO2 and LH2 start basket refilling. Comparisons were made between the baseline Centaur D-1S propellant feed system and feed system alternatives including systems using capillary devices. The preferred concepts from the Centaur D-1S study were examined for APOTV and POTV vehicles for delivery and round trip transfer of payloads between LEO and GEO. Mission profiles were determined to provide propellant usage timelines and the payload partials were defined

Vacuum field energy and spontaneous emission in anomalously dispersive cavities

Anomalously dispersive cavities, particularly white light cavities, may have larger bandwidth to finesse ratios than their normally dispersive counterparts. Partly for this reason, their use has been proposed for use in LIGO-like gravity wave detectors and in ring-laser gyroscopes. In this paper we analyze the quantum noise associated with anomalously dispersive cavity modes. The vacuum field energy associated with a particular cavity mode is proportional to the cavity-averaged group velocity of that mode. For anomalously dispersive cavities with group index values between 1 and 0, this means that the total vacuum field energy associated with a particular cavity mode must exceed $\hbar \omega/2$. For white light cavities in particular, the group index approaches zero and the vacuum field energy of a particular spatial mode may be significantly enhanced. We predict enhanced spontaneous emission rates into anomalously dispersive cavity modes and broadened laser linewidths when the linewidth of intracavity emitters is broader than the cavity linewidth.Comment: 9 pages, 4 figure

Laser-controlled fluorescence in two-level systems

The ability to modify the character of fluorescent emission by a laser-controlled, optically nonlinear process has recently been shown theoretically feasible, and several possible applications have already been identified. In operation, a pulse of off-resonant probe laser beam, of sufficient intensity, is applied to a system exhibiting fluorescence, during the interval of excited- state decay following the initial excitation. The result is a rate of decay that can be controllably modified, the associated changes in fluorescence behavior affording new, chemically specific information. In this paper, a two-level emission model is employed in the further analysis of this all-optical process; the results should prove especially relevant to the analysis and imaging of physical systems employing fluorescent markers, these ranging from quantum dots to green fluorescence protein. Expressions are presented for the laser-controlled fluorescence anisotropy exhibited by samples in which the fluorophores are randomly oriented. It is also shown that, in systems with suitably configured electronic levels and symmetry properties, fluorescence emission can be produced from energy levels that would normally decay nonradiatively. © 2010 American Chemical Society

Recent bean leaf beetle and bean pod mottle virus research

Soybean growers face a dilemma when considering management options for bean leaf beetles and bean pod mottle virus. Rayda Krell recently completed a research program at Iowa State University that focused on immediate solutions for this pest problem. This article summarizes her research from which we suggest some short-term management options

Revisiting an integrated approach to bean leaf beetle and bean pod mottle virus management

This article originally appeared in the 2005 ICM newsletter. However, the significance of the bean leaf beetle and bean pod mottle virus has not diminished in recent years. There is still the potential of economic damage from either or both pests. We have recently completed a three-year study that examines the complex issues of managing these two pests, but the data are still being analyzed. We also have identified potential field tolerance to virus disease. Growers are encouraged to query seed dealers regarding tolerance of varieties to virus disease. Ultimately, this will likely be the best management tool for disease control. In the meantime, we give you our best recommendations as we understand the situation in Iowa

Management decisions for bean leaf beetles and bean pod mottle virus

Yogi Berra said, If you come to a fork in the road, take it. Many soybean producers will be at that fork in a couple of weeks, trying to decide whether or not to spray overwintered bean leaf beetles, and determining how to manage bean pod mottle virus. The dilemma is that some overwintered bean leaf beetles may transmit bean pod mottle virus and not knowing where in Iowa the problem is most likely to occur, what percentage of beetles are transmitting the virus, or when to spray can greatly complicate management decisions

Evaluation of Management Tactics for Bean Leaf Beetles and Bean Pod Mottle Virus in Soybean

An increase in bean leaf beetles has caused an increase in bean pod mottle virus - a yield robbing plant pathogen in Iowa soybeans. The incidence of bean pod mottle virus is often positively correlated with bean leaf beetle populations. For example, the greatest increase in bean pod mottle virus infection occurs after the first generation of bean leaf beetles reaches peak population density (late July). However, soybeans are most affected when soybeans are infected as seedlings

Seed treatments in soybean: Managing bean leaf beetles

To date, our recommendation for the chemical control of bean leaf beetles and bean pod mottle virus has been for an early and a mid-season application of a pyrethroid insecticide (e.g., Asana®, Mustang®, or Warrior®). These insecticide applications should be timed such that fields are treated as soon as bean leaf beetles are first detected in the field (the early-season application) and again when the first generation emerges in early July (the mid-season application). These applications have been shown to improve yield and seed quality under high disease and beetle pressure