Design of prototype charged particle fog dispersal unit

The unit was designed to be easily modified so that certain features that influence the output current and particle size distribution could be examined. An experimental program was designed to measure the performance of the unit. The program described includes measurements in a fog chamber and in the field. Features of the nozzle and estimated nozzle characteristics are presented

Doctor of Philosophy

dissertationGrounded in poststructural feminist theory and feminist race theories, this qualitative study explores the education trajectories of three Women of Color for insights into their persistence to and in higher education. Specifically, through narrative analysis of the participants' authoring and re-authoring of their student subjectivities, this research investigates the relationship between lived experiences, complex identities, and education decision-making. Data were generated in a university class that employed (post)critical feminist pedagogy to center education experiences of underrepresented students. Data included participants' education histories, journals, and class assignments, participant interviews, and classroom observations. Findings illustrate how attending to students' situated contexts and lived experiences provides better understandings of persistence to and engagement with higher education. The three case studies presented point to the necessity of understanding the role families play in persistence to higher education in more complex ways to build upon the multiple forms of capital and support that families provide in students' trajectories to higher education. A second finding was that histories of participation in earlier schooling, specifically experiences with racism, sexism and classism, created challenges to engaging with education. Findings showcase the agency with which participants drew upon lived in re-authoring themselves to persist with and in higher education

Variability of ammonium and nitrate in disturbed and undisturbed forest soils

Non-Peer ReviewedThe spatial distribution of NH4+- and N03--N in forest soils, as affected by site disturbance, was studied at the landscape-scale. A sampling grid, consisting of 169 points, was established at an undisturbed site located in Prince Albert National Park. Additional grids, consisting of 36 and 49 sampling points, were established at a burned and a clear-cut site, respectively. Similar levels of inorganic-N at the undisturbed and disturbed sites suggests that management practices had little effect on the availability of inorganic-N. Similarly, the spatial distribution of inorganic-N was not related to landform element complexes, suggesting that hydrologic processes were not the primary factor controlling the distribution of inorganic-N at the scale studied. The occurrence of NH4+ -N as the dominant inorganic-N form suggests that nitrification was strictly limited in these forest soils. This contrasts agricultural soils in which nitrification often proceeds swiftly in the presence of NH4+-N

Accretion Signatures from Massive Young Stellar Objects

High resolution (lambda / Delta-lambda = 50,000) K-band spectra of massive, embedded, young stellar objects are presented. The present sample consists of four massive young stars located in nascent clusters powering Galactic giant H II regions. Emission in the 2.3 micron 2--0 vibrational--rotational bandhead of CO is observed. A range of velocity broadened profiles seen in three of the objects is consistent with the emission arising from a circumstellar disk seen at various inclination angles. Br gamma spectra of the same spectral and spatial resolution are also presented which support an accretion disk or torus model for massive stars. In the fourth object, Br emission suggesting a rotating torus is observed, but the CO profile is narrow, indicating that there may be different CO emission mechanisms in massive stars and this is consistent with earlier observations of the BN object and MWC 349. To--date, only young massive stars of late O or early B types have been identified with clear accretion disk signatures in such embedded clusters. Often such stars are found in the presence of other more massive stars which are revealed by their photospheric spectra but which exhibit no disk signatures. This suggests the timescale for dissipating their disks is much faster than the less massive OB stars or that the most massive stars do not form with accretion disks.Comment: 28 pages, 10 Figures, accepted for publication in the Astrophysical Journa

Neurophysiological processing of emotion and parenting interact to predict inhibited behavior: an affective-motivational framework

Although inhibited behavior problems are prevalent in childhood, relatively little is known about the intrinsic and extrinsic factors that predict a child\u27s ability to regulate inhibited behavior during fear- and anxiety-provoking tasks. Inhibited behavior may be linked to both disruptions in avoidance-related processing of aversive stimuli and in approach-related processing of appetitive stimuli, but previous findings are contradictory and rarely integrate consideration of the socialization context. The current exploratory study used a novel combination of neurophysiological and observation-based methods to examine whether a neurophysiological measure sensitive to approach- and avoidance-oriented emotional processing, the late positive potential (LPP), interacted with observed approach- (promotion) and avoidance- (prevention) oriented parenting practices to predict children\u27s observed inhibited behavior. Participants were 5- to 7-year-old (N = 32) typically-developing children (M = 75.72 months, SD = 6.01). Electroencephalography was continuously recorded while children viewed aversive, appetitive, or neutral images, and the LPP was generated to each picture type separately. Promotion and prevention parenting were observed during an emotional challenge with the child. Child inhibited behavior was observed during a fear and a social evaluation task. As predicted, larger LPPs to aversive images predicted more inhibited behavior during both tasks, but only when parents demonstrated low promotion. In contrast, larger LPPs to appetitive images predicted less inhibited behavior during the social evaluative task, but only when parents demonstrated high promotion; children of high promotion parents showing smaller LPPs to appetitive images showed the greatest inhibition. Parent-child goodness-of-fit and the LPP as a neural biomarker for emotional processes related to inhibited behavior are discussed

Epidemiology and integrated control of Potato Late Blight in Europe

Phytophthora infestans, the causal agent of late blight, is a major threat to potato production in northwestern Europe. Before 1980, the worldwide population of P. infestans outside Mexico appeared to be asexual and to consist of a single clonal lineage of A1 mating type characterized by a single genotype. It is widely believed that new strains migrated into Europe in 1976 and that this led to subsequent population changes including the introduction of the A2 mating type. The population characteristics of recently collected isolates in NW Europe show a diverse population including both mating types, sexual reproduction and oospores, although differences are observed between regions. Although it is difficult to find direct evidence that new strains are more aggressive, there are several indications from experiments and field epidemics that the aggressiveness of P. infestans has increased in the past 20 years. The relative importance of the different primary inoculum sources and specific measures for reducing their role, such as covering dumps with plastic and preventing seed tubers from becoming infected, is described for the different regions. In NW Europe, varieties with greater resistance tend not to be grown on a large scale. From the grower’s perspective, the savings in fungicide input that can be achieved with these varieties are not compensated by the higher (perceived) risk of blight. Fungicides play a crucial role in the integrated control of late blight. The spray strategies in NW Europe and a table of the specific attributes of the most important fungicides in Europe are presented. The development and use of decision support systems (DSSs) in NW Europe are described. In The Netherlands, it is estimated that almost 40% of potato growers use recommendations based on commercially available DSS. In the Nordic countries, a new DSS concept with a fixed 7-day spray interval and a variable dose rate is being tested. In the UK, commercially available DSSs are used for c. 8% of the area. The validity of Smith Periods for the new population of P. infestans in the UK is currently being evaluated