Polar plasmas as observed by Dynamics Explorers 1 and 2

Plasma measurements from the Dynamics Explorer 1 and 2 satellites were used to characterize the polar cap environment. Analysis of numerous polar-cap passes indicate that, in general, three major regimes of plasma exist: (1) polar rain--electrons with magnetosheath-like energy spectra but much lower densities, most intense near the cusp and weakening toward the central polar cap; (2) polar wind--low energy upward flowing ions with both field-aligned and conical distributions; and (3) acceleration events--sporadic events consistent with the acceleration of electrons and positive ions by parallel electric fields. (1) to (3) were observed at high altitudes by Dynamics Explorer 1, while (1) and (3) were also observed at low altitudes by Dynamics Explorer 2. The plasma parameters associated with these plasma regimes are presented and discussed in terms of source and acceleration mechanisms

The role of pathogen shedding in linking within- and between-host pathogen dynamics

A model linking within- and between-host pathogen dynamics via pathogen shedding (emission of pathogens throughout the course of infection) is developed, and several aspects of host availability and co-infection are considered. In this model, the rate of pathogen shedding affects both the pathogen population size within a host (also affecting host mortality) and the rate of infection of new hosts. Our goal is to ascertain how the rate of shedding is likely to evolve, and what factors permit coexistence of alternative shedding rates in a pathogen population. For a constant host population size (where an increase in infected hosts necessarily decreases susceptible hosts), important differences arise depending on whether pathogens compete only for susceptible (uninfected) hosts, or whether co-infection allows for competition for infected hosts. With no co-infection, the pathogen type that can persist with the lowest number of susceptible hosts will outcompete any other, which under the assumptions of the model is the pathogen with the highest basic reproduction number. This is often a pathogen with a relatively high shedding rate (s). If within-host competition is allowed, a trade-off develops due to the conflicting effects of shedding on within- and between-host pathogen dynamics, with within-host competition favoring clones with low shedding rates while between-host competition benefits clones with higher shedding rates. With within-host competition for the same host cells, low shedding rate clones should eliminate high-s clones in a co-infected host, if equilibrium is reached. With co-infection, but no within-host competition, pathogen clones still interact by affecting the mortality of co-infected hosts; here, coexistence is more likely. With co-infection, two clones can coexist if one is the superior competitor for uninfected hosts and the other for co-infected hosts

Modeling Soil Erosion with Emphasis on Steep Slopes and the Rilling Process

A soil erosion model, known as KYERMO, was developed for use in soil erosion research. The model was written in Microsoft FORTRAN, which is a subset of the ANSI FORTRAN 77 standard, allowing the model to be run on an IBM-PC as well as a mainframe computer. The model structure consisted of many interrelated subroutines which facilitated model development, testing, and future expansion. A sensitivity analysis of the detachment component was performed, examining the number of rills, the number of space and time steps, and the detachment parameters. This analysis indicated that the model performed as expected for the detachment limiting case. Field plots for the collection of justification data were designed and constructed on steep slopes (28 and 30.5 percent). Their surfaces were shaped to provide controlled rill patterns. Rainfall was applied through use of an irrigation nozzle rainfall simulator. The field simulations included initial full plot (22.1 m) runs on unrilled surfaces with two and six rill watersheds, full plot runs on established surfaces, and half plot runs on established surfaces. Eight field simulations were conducted. Measured or sampled quantities included runoff rate, delivered sediment concentration, delivered sediment size distribution, rainfall intensity, soil moisture content, plot surface shape, and rill cross-sections. Each of the field erosion events was simulated using KYERMO. Hydrologic parameters were fitted to provide the proper runoff characteristics to allow justification of the erosion component of the model. The detachment parameters were initially set using parameters and relationships from the literature. Prediction was comparable to that reported by other researchers. The detachment parameters were then fitted individually to gain insights about their effects. The resultant values were then considered in light of plot characteristics. These analyses indicated that a more complete knowledge of the rill bed particle size distribution could be used to increase accuracy and that soil structure changes due to tillage should be considered. The detachment rate was found to be the limiting factor rather than the sediment transport rate

Neurosequential Model of Therapeutics in a Therapeutic Preschool: Implications for Work with Children with Complex Neuropsychiatric Problems

The two studies presented examine the use of the Neurosequential Model of Therapeutics on the social-emotional development and behavior of 28 children participating in a therapeutic preschool program. Results from these studies indicate that the use of the Neurosequential Model of Therapeutics approach to determine the nature, timing, and “dose” of developmentally appropriate activities and interventions within the context of a therapeutic preschool did improve the social-emotional development of the participating children. Interventions and activities were provided in the context of Filial Play Therapy as part of the therapeutic preschool environment. Six-month and 12-month follow-ups suggest gains in social-emotional development and behavior were retained. Implications for future use are discussed

Modeling Erosion on Long Steep Slopes with Emphasis on the Rilling Process

A model of soil erosion, known as KYERMO, is presented which emphasizes those processes which are important on steep slopes. Particular emphasis is placed on modeling rill development and geometry since this is the least understood process in erosion mechanics. The model requires an input rill pattern. Rainfall inputs to the model require the use of breakpoint rainfall and kinetic energy. Surface storage is calculated based on random roughness data of Linden (1979). Infiltration is modeled by use of the two layer Green-Ampt-Mein-Larson model as proposed by Moore and Eigel (1981). Runoff is related to rainfall excess and surface storage by the exponential, relationship of Thelin and Keifer (1960). Erosion is modeled separately as rill and interrill erosion. Interrill erosion is modeled by evaluating raindrop splash and interrill transport capacity. Raindrop splash is predicted by using the Bubenzer and Jones (1971) equation which requires kinetic energy, rainfall intensity, and percent clay. In terr ill transport capacity is modeled by either the Yalin (1963) or Yang (1973) equation depending on user preference. The rate of delivery of soil to a rill is a minimum of either the transport rate or splash rate. Rill detachment capacity is calculated using the shear excess equation of Foster (1982). Transport capacity is calculated from either the Yalin (1963) or Yang ( 1973) depending on user preference. The distribution of detachment around the rill boundary is calculated as a function of the shear distribution. Shear is distributed by using a modification of the area method of Lundgren and Jonsson (1964). Rill wall sloughing is calculated by using the procedure of Wu et al. (1982) which uses a critical wall angle. Flow routing in rills is calculated by using the kinematic routing procedures of Brakensiek (1966). Data is presented showing that predictions made with model components are reasonable. A limited sensitivity analysis with the model shows that predictions follow the trends that one would expect