Alternative Impact Metrics: UK Faculty Evaluation

Dr. Derek Lane discusses metrics for research assessment and faculty evaluation at the University of Kentucky. The above video is available for download in mp4 format by clicking the relevant link listed under the additional files shown below. The slide deck is available by clicking the Download button on the right

Potential Interactions of Early Season Herbicides and Insecticides in Cotton: Thrips Control and Plant Health

Cotton growth early in the season is affected by damaging levels of thrips in many production fields in Arkansas. During this time, insecticides used to control thrips and herbicides used to control weeds are often present at the same time on the cotton plant. This research explores how various combinations of herbicides and insecticides influence thrips numbers and cotton plant growth parameters early in the growing season. Pathways evaluated included interactions between preemergence herbicides and insecticide seed treatments and interactions between common tank-mixed foliar herbicides and selected foliar insecticides. No interactions in thrips control or plant growth were observed when using preemergence herbicides in combination with insecticide seed treatments. However, efficacy varied between chosen insecticide seed treatments and it may be concluded that in this experiment imidacloprid seed treatments exhibited greater control of thrips numbers than thiamethoxam seed treatments. There were isolated herbicide-insecticide interactions affecting plant growth parameters, but overall the co-application of tested herbicides and insecticides offer cotton producers the ability to integrate thrips and weed control without loss of thrips efficacy or negative impact on plant growth. Herbicide-insecticide interactions examined in this study suggested that pesticide combinations present on the cotton plant simultaneously, early in the season, have no significant interaction which may affect thrips control and early season cotton plant growth

Resonance production in quark and gluon jets

The formation of hadrons from free quarks and gluons is poorly understood and can not be fully explained by current theories. This hadronization process is described using phenomenological models, each reflecting possible scenarios for the QCD dynamics. Electron-positron annihilation at the Z0 resonance provides an ideal environment in which to study hadron production because of the combination of high event rates and clean final states due to the absence of beam and target remnants. Using the particle identification capabilities of the DELPHI detector at the Large Electron-Positron collider (LEP), it is possible to differentiate the production of different hadron species in the final state. This information allows the study of details of the transition from quarks and qluons to stable hadrons. This thesis investigates the hadronization process by comparing the production of f and K*0 particles produced in quark jets versus those produced in gluon jets at the Z0

Electrical processes in heavy rain in the tropics

The thesis is based on research carried out in Sierra Leone over a period of several years. An asymmetric field mill and a 'wide-angle' shielded receiver have been developed for the measurement of electric field and precipitation current in tropical thunderstorms. A detailed field-mill theory is presented which analyses the effects of leakage currents, inadequate grounding, contact potentials, conduction current, 'pick-up' of fluctuating electric fields and noise in the amplifier. Principles are deduced for the optimum design of a precision field mill using either a phase sensitive detector or an asymmetric signal. Measurements of precipitation current and its response to step changes in the field show that turbulent diffusion of splash droplets probably constitutes an important, even dominant, electrical process in heavy rain. The response of precipitation current to a lightning flash, averaged over many flashes, is large and has a delay of a few seconds. From the analysis of various models considered as a mechanism to explain the results it is deduced that charge carried on splash droplets is being diffused upwards by turbulence, transported by wind and is itself precipitating into the rain receiver. An experiment was performed to measure the electric current due to evaporation. The results show that the current due to evaporation in the presence of an electric field is much smaller than that due to conduction in air. The observation of a 'warm' thunderstorm cloud is reported. A project was developed to make visual and electrical measurements simultaneously on the same cloud. A time lapse film of tropical clouds, together with some electric field measurements beneath them, are used to discuss the flow pattern associated with a tropical thunderstorm and the mechanism by which it becomes charged. Appendices include an analysis of the shielding effect of a vertical rod at ground potential, the description of some further instrumentation, including a data processing system designed by the author which uses a novel but effective method of detecting the occurrence of the peak of a signal, more detailed mathematical derivations of equations used in the main text and a filming schedule for the time-lapse photography

Efficient, transparent, and comprehensive runtime code manipulation

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (p. 293-306).This thesis addresses the challenges of building a software system for general-purpose runtime code manipulation. Modern applications, with dynamically-loaded modules and dynamically-generated code, are assembled at runtime. While it was once feasible at compile time to observe and manipulate every instruction--which is critical for program analysis, instrumentation, trace gathering, optimization, and similar tools--it can now only be done at runtime. Existing runtime tools are successful at inserting instrumentation calls, but no general framework has been developed for fine-grained and comprehensive code observation and modification without high overheads. This thesis demonstrates the feasibility of building such a system in software. We present DynamoRIO, a fully-implemented runtime code manipulation system that supports code transformations on any part of a program, while it executes. DynamoRIO uses code caching technology to provide efficient, transparent, and comprehensive manipulation of an unmodified application running on a stock operating system and commodity hardware. DynamoRIO executes large, complex, modern applications with dynamically-loaded, generated, or even modified code. Despite the formidable obstacles inherent in the IA-32 architecture, DynamoRIO provides these capabilities efficiently, with zero to thirty percent time and memory overhead on both Windows and Linux. DynamoRIO exports an interface for building custom runtime code manipulation tools of all types. It has been used by many researchers, with several hundred downloads of our public release, and is being commercialized in a product for protection against remote security exploits, one of numerous applications of runtime code manipulation.by Derek L. Bruening.Ph.D

Systematic testing of multithreaded Java programs

Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.Includes bibliographical references (p. 149-150).Derek L. Bruening.M.Eng

Simulations of the temporal and spatial resolution for a compact time-resolved electron diffractometer

A novel compact electron gun for use in time-resolved gas electron diffraction experiments has recently been designed and commissioned. In this paper we present and discuss the extensive simulations that were performed to underpin the design in terms of the spatial and temporal qualities of the pulsed electron beam created by the ionisation of a gold photocathode using a femtosecond laser. The response of the electron pulses to a solenoid lens used to focus the electron beam has also been studied. The simulated results show that focussing the electron beam affects the overall spatial and temporal resolution of the experiment in a variety of ways, and that factors that improve the resolution of one parameter can often have a negative effect on the other. A balance must, therefore, be achieved between spatial and temporal resolution. The optimal experimental time resolution for the apparatus is predicted to be 416 fs for studies of gas-phase species, while the predicted spatial resolution of better than 2 nm-1 compares well with traditional time-averaged electron diffraction set-ups

Projective Normality and Ehrhart Unimodality for Weighted Projective Space Simplices

Within the intersection of Ehrhart theory, commutative algebra, and algebraic geometry lie lattice polytopes. Ehrhart theory is concerned with lattice point enumeration in dilates of polytopes; lattice polytopes provide a sandbox in which to test many conjectures in commutative algebra; and many properties of projectively normal toric varieties in algebraic geometry are encoded through corresponding lattice polytopes. In this article we focus on reflexive simplices and work to identify when these have the integer decomposition property (IDP), or equivalently, when certain weighted projective spaces are projectively normal. We characterize the reflexive, IDP simplices whose associated weighted projective spaces have one projective coordinate with weight fixed to unity and for which the remaining coordinates can assume one of three distinct weights. We show that several subfamilies of such reflexive simplices have unimodal $h^\ast$-polynomials, thereby making progress towards conjectures and questions of Stanley, Hibi-Ohsugi, and others regarding the unimodality of their $h^\ast$-polynomials. We also provide computational results and introduce the notion of reflexive stabilizations to explore the (non-)ubiquity of reflexive simplices that are simultaneously IDP and $h^\ast$-unimodal

Computational Based Investigation of Lattice Cell Optimization under Uniaxial Compression Load

Structural optimization is a methodology used to generate novel structures within a design space by finding a maximum or minimum point within a set of constraints. Topology optimization, as a subset of structural optimization, is often used as a means for light-weighting a structure while maintaining mechanical performance. This article presents the mathematical basis for topology optimization, focused primarily on the Bi-directional Evolutionary Structural Optimization (BESO) and Solid Isotropic Material with Penalization (SIMP) methodologies, then applying the SIMP methodology to a case study of additively manufactured lattice cells. Three lattice designs were used: the Diamond, I-WP, and Primitive cells. These designs are all based on Triply Periodic Minimal Surfaces (TPMS). Individual lattice cells were subjected to a uniaxial compression load, then optimized for these load conditions. The optimized cells were then compared to the base cell designs, noting changes in the stress field response, and the maximum and minimum stress values. Overall, topology optimization proved its utility under this loading condition, with each cell seeing a net gain in performance when considering the volume reduction. The I-WP lattice saw a significant stress reduction in conjunction with the mass and volume reduction, marking a notable increase in cell performance