Solvent Deactivation of Mimosa Webworm Larval Webbing (Lepidoptera: Plutellidae)

Untreated larval webbing of the mimosa webworm, Homadaula anisocentra stimulated oviposition. Six-week-old webbing was as active as two-day-old webbing. Stimulatory activity of webbing was lost after rinsing with highly polar solvents, but not after rinsing with nonpolar solvents. Addition of the polar solvent rinses did not induce activity in other substrates nor restore activity to rinsed webbing. No differences in structure were found in a scanning electron microscope examination of unrinsed webbing and webbing rinsed with solvents of varying polarity

Population Matrix Model for American Chestnut (Castanea dentata) and the Implications for Re-introduction

Biodiversity loss is occurring at an unprecedented and alarming rate; we can no longer ignore the effects of humans on the environment and must take action to reduce our impact (Pimm 1995). Restoration of degraded communities and ecosystems can reduce biodiversity loss (Seddon 2007, Armstrong and Seddon 2008). Restoration strategies, sometimes referred to as the “restoration toolbox,” encompass many specific techniques one of which is the reintroduction of individual species (Sodhi and Ehrlich 2010). Re-introductions are the introduction of individuals from a different population of a species to an endemic region of the species, where populations have been eliminated due to natural processes or anthropogenic factors (Sodhi and Ehrlich 2010). Species re-introductions are an important tool in biological conservation; however, they often are unsuccessful or require more resources than expected as it is difficult to predict how a new population will grow (Sarrazin and Barbault 1996, Seddon 2007). California condors (Gymnogyps californianus) and the grey wolf (Canis lupus) are examples of highly successful re-introductions of animal populations (Wilmers 2003, Ralls and Ballou 2004, Ripple 2001). However, there have been few attempts at re-introducing a plant species. Instead plant re-introductions have largely been used only as a part of whole ecosystem restorations. American chestnut (Castanea dentata; chestnut henceforth) offers a potential for intentional plant re-introduction (Jacobs 2007, Jacobs et al. 2013). American chestnut has been called a foundation species in the Eastern United States because it was important for regulating nutrient cycling and decomposition (Ellison 2005), as well as food web dynmaics (Dalgleish & Swihart 2012). Foundation species are unlike keystone species in that they are high in number and widespread, yet similar in that they are important in determining the structure and stability of local ecosystems (Ellison 2005). Trees are often foundation species in forest ecosystems; the presence or absence of specific plant populations have the potential to strongly affect ecosystem structure and health. The American chestnut was a prominent tree in eastern forests from Maine to Georgia in early American history (Jacobs et al. 2013). American chestnut trees impact community and ecosystem processes, such as insect, soil, small mammal, and bird communities, as well as tree composition. In 1905, the fungus Cyphonectria parasitica was accidentally introduced in New York Zoological Garden and quickly spread throughout the range of the American chestnut infecting adult chestnuts of the estimated three to four billion trees in a period of 50 years (Zhang 2013, Welch 2006). The fungus enters chestnut trees through cracks in the bark which are characteristic of older chestnuts or tree wounds, and spreads to the cambium creating cankers that prevents the flow of nutrients (Welch 2006). Restoring American chestnut with a blightresistant chestnut tree has been explored by the American Chestnut Foundation and other researchers since the 1920s. Scientists have experimented with multiple possibilities for creating blight resistance in American chestnut trees including crossbreeding with Asian chestnut trees (primarily Chinese chestnut, Castanea mollissima), infecting trees with a hypovirulent (nonlethal) strains of the blight, C. parasitica, and genetic modification (Jacobs et al. 2013). American chestnut may be important to restoration of forest communities as there is a possibility for the re-introduction of blight resistant chestnut. This is perhaps one of the first opportunities for tree re-introduction and may serve as a model for future plant re-introductions. Monitoring re-introduction projects and modeling the growth of populations are ways to ensure restoration efforts may be achieved. Matrix population models are size structured models that can be used to project population growth rate for re-introduced populations, and offer specific information on what life stages or transitions are the most important for targeting management to enhance population establishment (Morris and Doak 2002). If the population growth rate is declining, it indicates that the population may not be viable without management action or change in environmental factors (Morris and Doak 2002). The rate of decline could be due to many factors. Sensitivity and elasticity values (prospective analysis of matrix models, (Caswell 2001)) can help determine what life stages and transitions are most important to the population growth rate, and thus how to target management strategies. Population models also offer the ability to mathematically experiment with different re-introduction scenarios (Morris and Doak 2002). While significant population monitoring of growth, survival, and reproduction is necessary to create a viable model, population models that advise management can enhance the success of species reintroductions (Morris and Doak 2002). My study creates a matrix population model of a young population of American chestnuts with the goal of informing restoration efforts using blight-resistant, back-crossed American chestnut. My research provides a detailed demographic study for a site just north of the historical range of chestnut experiencing similar annual environmental effects that re-introduced populations in the Northeast may face. The goals of my study are 1) to measure growth, survival, and reproduction of a chestnut population under natural conditions 2) to develop a matrix model that can be used to inform restoration, and 3) to use the model to explore possible restoration scenarios

Dynamic Response of Control Servo System Installed in NAES-Equipped SB2C-5 Airplane (BuAer No. 83135)

Dynamic--response measurements for various conditions of displacement and rate signal input, sensitivity setting, and simulated hinge moment were made of the three control-surface servo systems of an NAES-equipped remote-controlled airplane while on the ground. The basic components of the servo systems are those of the General Electric Company type G-1 autopilot using electrical signal. sources, solenoid-operated valves, and hydraulic pistons. The test procedures and difficulties are discussed, Both frequency and transient-response data, are presented and comparisons are made. The constants describing the servo system, the undamped natural frequency, and the damping ratio, are determined by several methods. The response of the system with the addition of airframe rate signal is calculated. The transfer function of the elevator surface, linkage, and cable system is obtained. The agreement between various methods of measurement and calculation is considered very good. The data are complete enough and in such form that they may be used directly with the frequency-response data of an airplane to predict the stability of the autopilot-airplane combination

The CP-violating asymmetry in \eta\to\pi^+ \pi^- e^+e^-

We study the CP-violating asymmetry {\cal A}_{\rm CP}, which arises, in \eta\to\pi^+\pi^- e^+e^-, from the angular correlation of the e^+ e^- and \pi^+\pi^- planes due to the interference between the magnetic and electric decay amplitudes. With the phenomenologically determined magnetic amplitude and branching ratio as input, the asymmetry, induced by the electric bremsstrahlung amplitude through the CP-violating decay \eta\to\pi^+\pi^-, and by an unconventional tensor type operator, has been estimated respectively. The upper bound of {\cal A}_{\rm CP} from the former is about 10^{-3}, and the asymmetry from the latter might be up to O(10^{-2}). One can therefore expect that this CP asymmetry would be an interesting CP-violating observable for the future precise measurements in the \eta factories.Comment: LaTeX, 6 pages. One reference corrected, and some new references adde

The Synthesis of Optimum Homing Missile Guidance Systems with Statistical Inputs

An analytical approach is presented which is applicable to the optimization of homing navigation guidance systems which are forced to operate in the presence of radar noise. The two primary objectives are to establish theoretical minimum miss distance performance and a method of synthesizing the optimum control system. The factors considered are: (1) target evasive maneuver, (2) radar glint noise, (3) missile maneuverability, and (4) the inherent time-varying character of the kinematics. Two aspects of the problem are considered. In the first, consideration is given only to minimization of the miss distance. The solution given cannot be achieved in practice because the required accelerations are too large. In the second, results are extended to the practical case where the limited acceleration capabilities of the missile are considered by placing a realistic restriction on the mean-square acceleration so that system operation is confined to the linear range. Although the exact analytical solution of the latter problem does not appear feasible, approximate solutions utilizing time-varying control systems can be found. One of these solutions - a range multiplication type control system - is studied in detail. It is shown that the minimum obtainable miss distance with a realistic restriction on acceleration is close to the absolute minimum for unlimited missile maneuverability. Furthermore, it is shown that there is an equivalence in performance between the homing and beam-rider type guidance systems. Consideration is given to the effect of changes in target acceleration, noise magnitude, and missile acceleration on the minimum miss distance