Essential metals at the host-pathogen interface : nutritional immunity and micronutrient assimilation by human fungal pathogens

AC and DW are supported by a Sir Henry Dale Fellowship jointly funded by the Wellcome Trust and the Royal Society (Grant Number 102549/Z/13/Z).Peer reviewedPublisher PD

INCIDENTAL AND JOINT CONSUMPTION IN RECREATION DEMAND

A theory for analyzing incidental consumption in a single site recreation demand model is presented. We show that incidental consumption on a recreation trip, such as a visit to see friends or a visit to a second recreation site, can be treated as a complementary good and analyzed using conventional theory. We also show that the analysis applies whether the side trips are incidental or joint. In a simple application we find that failing to account for incidental consumption appears to create little bias in valuing recreation sites.Resource /Energy Economics and Policy,

Power System Transients: Impacts of Non-Ideal Sensors on Measurement-Based Applications

The power system is comprised of thousands of lines, generation sources, transformers, and other equipment responsible for servicing millions of customers. Such a complex apparatus requires constant monitoring and protection schemes capable of keeping the system operational, reliable, and resilient. To achieve these goals, measurement is a critical role in the continued functionality of the power system. However, measurement devices are never completely reliable, and are susceptible to inherent irregularities; imparting potentially misleading distortions on measurements containing high-frequency components. This dissertation analyzes some of these effects, as well as the way they may impact certain applications in the grid that utilize these kinds of measurements. This dissertation first presents background on existing measurement technologies currently in use in the power grid, with extra emphasis placed on point-on-wave (PoW) sensors, those designed to capture oscillographic records of voltage and current signals. Next, a waveform “playback” system, developed at Oak Ridge National Laboratory’s Distributed Energy Communications \& Control (DECC) laboratory was used for comparisons between various line-post-monitor PoW sensors when subjected to different high-frequency current disturbances. Each of the three sensors exhibited unique quirks in these spectral regions, both in terms of harmonic magnitude and phase angle. A goodness-of-fit metric for comparing an ideal reference sensor with the test sensors was adopted from the literature and showed the extremes to which two test sensors vastly under performed when compared to the third. The subsequent chapter analyzes these behaviors under a statistical lens, using kernel density estimation to fit probability density functions (PDFs) to error distributions at specific harmonic frequencies resulting from sensor frequency response distortions. The remaining two chapters of the dissertation are concerned with resultant effects on applications that require high-frequency transient data. First, a detection algorithm is presented, and its performance when subjected to statistical errors inherent in these sensors is quantified. The dissertation culminates with a study on an artificial intelligence (AI) technique for estimating the location of capacitor switching transients, as well as learning prediction intervals that indicate the level of uncertainty present in the data caused by sensor frequency response irregularities

A hierarchical approach to automated identification of anomalous electrical waveforms

Power utilities employ smart\u27\u27 field devices capable of digitally recording electrical waveforms. The relationship between events and their recorded waveforms can be exploited for characterization of the power grid’s state over any period of time and facilitating the impact electrical disturbances have on equipment, subsystems, and systems. Over a period of one month, these devices record approximately 2,000 electrical disturbance waveforms. Currently, analysis of these waveforms is conducted using by-hand approaches; thus, severely limiting the analysis to roughly 2%. The analysis is done hours to days after the events occurred, which negates informed, timely corrective actions. This document presents an automated hierarchical approach capable of identifying specific events using the electrical disturbance waveforms stored using COMmon format for TRAnsient Data Exchange (COMTRADE) files. The developed approach processes a single file in 1.8 seconds and has demonstrated successful identification of 140 events with a success rate of 91%

Towards New Antimalarial Drug: Depolarization of Liposomal Membranes by Aminooxoethylcarbamothioate in the Presence of Fe3+ Ions

Despite the efforts of scientists around the world 409,000 people died of malaria in 2019 alone. According to the WHO 90% of those deaths occurred in Africa. Despite the high number of available treatments, malaria continues to plague many parts of the world. This is due in part to drug resistance developed among mosquito populations as well as limited access to medicines that do work. Furthermore, when traveling to malaria prone areas, pretreatment with a chemoprophylaxis is common practice. However, often the side effects to malaria pretreatment are severe. A new approach to the treatment of malaria is a compound that is only active in the presence of Fe3+ ions and a negative transmembrane potential (Δψ). In the parasitic stage where symptoms of malaria present, plasmodium falciparum invades erythrocytes and increases the concentration of free Fe3+ in the cytosol of red blood cells. The novel compound 2-(naphthalen-1-ylamino)-2-oxoethyl) (2-bromoethyl) carbamothioate is shown to selectively lyse liposomes only under the presence of Fe3+ and a transmembrane diffusion potential. These promising findings suggest a new type of malaria treatment that can depolarize and selectively kill P. falciparum during the erythrocytic cycle

Distributed Collision-Free Motion Coordination on a Sphere: A Conic Control Barrier Function Approach

This letter studies a distributed collision avoidance control problem for a group of rigid bodies on a sphere. A rigid body network, consisting of multiple rigid bodies constrained to a spherical surface and an interconnection topology, is first formulated. In this formulation, it is shown that motion coordination on a sphere is equivalent to attitude coordination on the 3-dimensional Special Orthogonal group. Then, an angle-based control barrier function that can handle a geodesic distance constraint on a spherical surface is presented. The proposed control barrier function is then extended to a relative motion case and applied to a collision avoidance problem for a rigid body network operating on a sphere. Each rigid body chooses its control input by solving a distributed optimization problem to achieve a nominal distributed motion coordination strategy while satisfying constraints for collision avoidance. The proposed collision-free motion coordination law is validated via simulation

AI for Evaluators: Opportunities and Risks

We are all familiar with how computers and smartphones have transformed work and productivity. We now stand at a new threshold with another technology that is predicted to further transform the way we work: Artificial Intelligence (AI).  In this article, we hope to take a sober and practical look at AI from the perspective of professional evaluators. We examine how we might use it, how it might transform the nature of our tasks, what threats it might pose to our field, and what evaluators might do to protect themselves and our society from potential adverse effects of this emerging technology.&nbsp

Effects of Hard-to-Soft Segment Ratios on the Synthesis and Physico-mechanical Properties of Polyurethane Films

Blood-contacting cardiovascular stents often induce a secondary clotting event due to unrestricted enzymatic activities. The use of hemocompatible polyurethane coatings on these implantable devices is one of the most promising methods to reduce device rejection. In this study, four commercial polyurethane films of various thicknesses and compositions were evaluated for their anticoagulation properties. Results suggested that these films exhibited excellent thermal and physico-mechanical properties while capable of increasing contact time with blood plasma by over a thousand-fold as compared to a control surface. Due to the unknown structure and composition of these commercial films, polyurethane samples were synthesized from toluene diisocyanate as the hard segment and polyethylene glycol as the soft segment under various hard-to-soft segment ratios. The synthesized samples were cast into films for testing of their physico-mechanical properties. The effects of the hard-to-soft segment ratios on these properties and the synthesis process were evaluated in order to optimize them for use in anticoagulation coatings

Easier done than said: a sociological analysis of tacit knowledge in railway maintenance systems

An examination of the social construction of rolling contact fatigue of rail, with an analysis of the impact of organisational structure, culture and change on the development and utilisation of codified and tacit knowledge required for rail maintenance decision-making

Knowledge for Equitable Mathematics Teaching: The Case of Latino ELLs in U.S. Schools

This paper reports the exploration of an aspect of knowledge needed for equitable mathematics teaching. Pedagogical Content Knowledge for Teaching Mathematics to English Language Learners (PCK-MELL) was proposed as a theoretical knowledge construct, a subdomain of MKT, and the construct was investigated through a process of survey instrument development and administration. The survey contained items intended to measure teachers’ knowledge of the obstacles encountered by ELLs in math classes, of the resources that ELLs draw upon, and of instructional strategies for teaching ELLs. Analysis of middle school mathematics teachers’ responses (N = 42) offered insights into how to improve the reliability and measurement validity of this sort of instrument, as well as directions for further theory development