Doctor of Philosophy

dissertationThe need for position and orientation information in a wide variety of applications has led to the development of equally varied methods for providing it. Amongst the alternatives, inertial navigation is a solution that o ffers self-contained operation and provides angular rate, orientation, acceleration, velocity, and position information. Until recently, the size, cost, and weight of inertial sensors has limited their use to vehicles with relatively large payload capacities and instrumentation budgets. However, the development of microelectromechanical system (MEMS) inertial sensors now o ers the possibility of using inertial measurement in smaller, even human-scale, applications. Though much progress has been made toward this goal, there are still many obstacles. While operating independently from any outside reference, inertial measurement su ers from unbounded errors that grow at rates up to cubic in time. Since the reduced size and cost of these new miniaturized sensors comes at the expense of accuracy and stability, the problem of error accumulation becomes more acute. Nevertheless, researchers have demonstrated that useful results can be obtained in real-world applications. The research presented herein provides several contributions to the development of human-scale inertial navigation. A calibration technique allowing complex sensor models to be identified using inexpensive hardware and linear solution techniques has been developed. This is shown to provide significant improvements in the accuracy of the calibrated outputs from MEMS inertial sensors. Error correction algorithms based on easily identifiable characteristics of the sensor outputs have also been developed. These are demonstrated in both one- and three-dimensional navigation. The results show significant improvements in the levels of accuracy that can be obtained using these inexpensive sensors. The algorithms also eliminate empirical, application-specific simplifications and heuristics, upon which many existing techniques have depended, and make inertial navigation a more viable solution for tracking the motion around us

The High-Affinity E. coli Methionine ABC Transporter: Structure and Allosteric Regulation

The crystal structure of the high-affinity Escherichia coli MetNI methionine uptake transporter, a member of the adenosine triphosphate (ATP)–binding cassette (ABC) family, has been solved to 3.7 angstrom resolution. The overall architecture of MetNI reveals two copies of the adenosine triphosphatase (ATPase) MetN in complex with two copies of the transmembrane domain MetI, with the transporter adopting an inward-facing conformation exhibiting widely separated nucleotide binding domains. Each MetI subunit is organized around a core of five transmembrane helices that correspond to a subset of the helices observed in the larger membrane-spanning subunits of the molybdate (ModBC) and maltose (MalFGK) ABC transporters. In addition to the conserved nucleotide binding domain of the ABC family, MetN contains a carboxyl-terminal extension with a ferredoxin-like fold previously assigned to a conserved family of regulatory ligand-binding domains. These domains separate the nucleotide binding domains and would interfere with their association required for ATP binding and hydrolysis. Methionine binds to the dimerized carboxyl-terminal domain and is shown to inhibit ATPase activity. These observations are consistent with an allosteric regulatory mechanism operating at the level of transport activity, where increased intracellular levels of the transported ligand stabilize an inward-facing, ATPase-inactive state of MetNI to inhibit further ligand translocation into the cell

Are megaquakes clustered?

We study statistical properties of the number of large earthquakes over the past century. We analyze the cumulative distribution of the number of earthquakes with magnitude larger than threshold M in time interval T, and quantify the statistical significance of these results by simulating a large number of synthetic random catalogs. We find that in general, the earthquake record cannot be distinguished from a process that is random in time. This conclusion holds whether aftershocks are removed or not, except at magnitudes below M = 7.3. At long time intervals (T = 2-5 years), we find that statistically significant clustering is present in the catalog for lower magnitude thresholds (M = 7-7.2). However, this clustering is due to a large number of earthquakes on record in the early part of the 20th century, when magnitudes are less certain.Comment: 5 pages, 5 figure

Development and Test of Highly Autonomous Unmanned Aerial Vehicles

Published in Journal of Aerospace Computing, Information, and Communication, Vol. 1, Issue 12, December 2004.This paper describes the design, development, and testing of Unmanned Aerial Vehicles (UAV) with highly automated search capabilities. Here, systems are able to respond on their own in the presence of considerable uncertainty utilizing an image processor, tracker/mapper, mission manager, and trajectory generation; and are used to complete a realistic benchmark reconnaissance mission. Subsequent to the selection of the search area, all functions are automated and human operator assistance is not required. The applications of these capabilities include reduction of operator workload in operational UAV systems, new UAV or guided-munition missions conducted without the assistance or availability of human operators, or the enhancement/augmentation of human search capabilities. The resulting system was able to search the 15-building village automatically with speed comparable to a human operator searching on foot or with a conventional remotely piloted vehicle. It was successful in 6 of 7 actual flights over the McKenna Military Operations in Urban Terrain test site over two different days and a variety of lighting conditions and choice of desired building

The In-Feed Antibiotic Carbadox Induces Phage Gene Transcription in the Swine Gut Microbiome

Carbadox is a quinoxaline-di-N-oxide antibiotic fed to over 40% of young pigs in the United States that has been shown to induce phage DNA transduction in vitro; however, the effects of carbadox on swine microbiome functions are poorly understood. We investigated the in vivo longitudinal effects of carbadox on swine gut microbial gene expression (fecal metatranscriptome) and phage population dynamics (fecal dsDNA viromes). Microbial metagenome, transcriptome, and virome sequences were annotated for taxonomic inference and gene function by using FIGfam (isofunctional homolog sequences) and SEED subsystems databases. When the beta diversities of microbial FIGfam annotations were compared, the control and carbadox communities were distinct 2 days after carbadox introduction. This effect was driven by carbadox-associated lower expression of FIGfams (n = 66) related to microbial respiration, carbohydrate utilization, and RNA metabolism (q \u3c 0.1), suggesting bacteriostatic or bactericidal effects within certain populations. Interestingly, carbadox treatment caused greater expression of FIGfams related to all stages of the phage lytic cycle 2 days following the introduction of carbadox (q ≤0.07), suggesting the carbadox-mediated induction of prophages and phage DNA recombination. These effects were diminished by 7 days of continuous carbadox in the feed, suggesting an acute impact. Additionally, the viromes included a few genes that encoded resistance to tetracycline, aminoglycoside, and beta-lactam antibiotics but these did not change in frequency over time or with treatment. The results show decreased bacterial growth and metabolism, prophage induction, and potential transduction of bacterial fitness genes in swine gut bacterial communities as a result of carbadox administration

Population Structure and Spatial Pattern in the Dioecious Shrub Ceratiola ericoides

The dioecious shrub Ceratiola ericoides (Florida rosemary) dominates xeric, infrequently burned Florida scrub vegetation, often to the near-exclusion of other woody species. We studied the spatial pattern, age, sex and size structure of four populations in Florida, USA: two coastal scrub populations subject to recurrent local disturbances due to sand movement, and two inland scrub populations in sites periodically burned by stand-replacing fires. The age structure of individual genets was estimated from node counts and used to describe the age structure of the populations. The sex ratio of males to females was not significantly different from 1:1, except within a female- biased coastal population subject to frequent sand movement. Node counts indicated that the mean age for reproductive individuals was 15 - 16 yr for the inland populations and 13 - 16 yr for the coastal populations. In all sites, there was no difference in mean age between males and females. Vegetative reproduction was uncommon except for the least-disturbed coastal population where 72 % of the reproductive individuals originated through layering. Individuals were generally randomly dispersed at the coastal sites, whereas significant aggregation of males and females occurred in the inland sites where the populations were initiated following fire. Seedling recruitment was continuous in the disturbed coastal scrub site, where 35 % of the individuals were juveniles. Most juveniles were dispersed from 0.5 to 0.75 m around females. At one of the inland sites, where juveniles comprised 11 % of the population, juveniles were clustered at 0.25 to 5.75 m around females. Coastal populations were all-aged, while inland populations were uneven-aged. Recruitment appears to follow periods of disturbance; infrequent fire in the inland populations and continuous sand movement on the coast are factors initiating recruitment

Use of Risk Models to Predict Death in the Next Year Among Individual Ambulatory Patients With Heart Failure

Importance: The clinical practice guidelines for heart failure recommend the use of validated risk models to estimate prognosis. Understanding how well models identify individuals who will die in the next year informs decision making for advanced treatments and hospice. Objective: To quantify how risk models calculated in routine practice estimate more than 50% 1-year mortality among ambulatory patients with heart failure who die in the subsequent year. Design, Setting, and Participants: Ambulatory adults with heart failure from 3 integrated health systems were enrolled between 2005 and 2008. The probability of death was estimated using the Seattle Heart Failure Model (SHFM) and the Meta-Analysis Global Group in Chronic Heart Failure (MAGGIC) risk calculator. Baseline covariates were collected from electronic health records. Missing covariates were imputed. Estimated mortality was compared with actual mortality at both population and individual levels. Main Outcomes and Measures: One-year mortality. Results: Among 10930 patients with heart failure, the median age was 77 years, and 48.0% of these patients were female. In the year after study enrollment, 1661 patients died (15.9% by life-table analysis). At the population level, 1-year predicted mortality among the cohort was 9.7% for the SHFM (C statistic of 0.66) and 17.5% for the MAGGIC risk calculator (C statistic of 0.69). At the individual level, the SHFM predicted a more than 50% probability of dying in the next year for 8 of the 1661 patients who died (sensitivity for 1-year death was 0.5%) and for 5 patients who lived at least a year (positive predictive value, 61.5%). The MAGGIC risk calculator predicted a more than 50% probability of dying in the next year for 52 of the 1661 patients who died (sensitivity, 3.1%) and for 63 patients who lived at least a year (positive predictive value, 45.2%). Conversely, the SHFM estimated that 8496 patients (77.8%) had a less than 15% probability of dying at 1 year, yet this lower-risk end of the score range captured nearly two-thirds of deaths (n = 997); similarly, the MAGGIC risk calculator estimated a probability of dying of less than 25% for the majority of patients who died at 1 year (n = 914). Conclusions and Relevance: Although heart failure risk models perform reasonably well at the population level, they do not reliably predict which individual patients will die in the next year

Prospecting in ultracool dwarfs : Measuring the metallicities of mid- and late-m dwarfs

© 2014. The American Astronomical Society. All rights reserved.Metallicity is a fundamental parameter that contributes to the physical characteristics of a star. The low temperatures and complex molecules present in M dwarf atmospheres make it difficult to measure their metallicities using techniques that have been commonly used for Sun-like stars. Although there has been significant progress in developing empirical methods to measure M dwarf metallicities over the last few years, these techniques have been developed primarily for early- to mid-M dwarfs. We present a method to measure the metallicity of mid- to late-M dwarfs from moderate resolution (R ∼ 2000) K-band (≃ 2.2 μm) spectra. We calibrate our formula using 44 wide binaries containing an F, G, K, or early-M primary of known metallicity and a mid- to late-M dwarf companion. We show that similar features and techniques used for early-M dwarfs are still effective for late-M dwarfs. Our revised calibration is accurate to ∼0.07 dex for M4.5-M9.5 dwarfs with -0.58 <[Fe/H] <+0.56 and shows no systematic trends with spectral type, metallicity, or the method used to determine the primary star metallicity. We show that our method gives consistent metallicities for the components of M+M wide binaries. We verify that our new formula works for unresolved binaries by combining spectra of single stars. Lastly, we show that our calibration gives consistent metallicities with the Mann et al. study for overlapping (M4-M5) stars, establishing that the two calibrations can be used in combination to determine metallicities across the entire M dwarf sequence.Peer reviewe

Assisted reproductive technology in the USA: is more regulation needed?

The regulation of assisted reproductive technologies is a contested area. Some jurisdictions, such as the UK and a number of Australian states, have comprehensive regulation of most aspects of assisted reproductive technologies; others, such as the USA, have taken a more piecemeal approach and rely on professional guidelines and the general regulation of medical practice to govern this area. It will be argued that such a laissez-faire approach is inadequate for regulating the complex area of assisted reproductive technologies. Two key examples, reducing multiple births and registers of donors and offspring, will be considered to illustrate the effects of the regulatory structure of assisted reproductive technologies in the USA on practice. It will be concluded that the regulatory structure in the USA fails to provide an adequate mechanism for ensuring the ethical and safe conduct of ART services, and that more comprehensive regulation is required

Twenty questions about design behavior for sustainability, report of the International Expert Panel on behavioral science for design

How behavioral scientists, engineers, and architects can work together to advance how we all understand and practice design—in order to enhance sustainability in the built environment, and beyond.https://www.nature.com/documents/design_behavior_for_sustainability.pdfPublished versio