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Development of Saddlepoint Methodologies for Sparse Sample Multiple Parameter Generalized Linear Models and Correlated Data Scenarios
Get PDFParameter estimation using maximum likelihood techniques may be biased when sample sizes are small, event rates are low, or otherwise sparse counts exist in a parametric model. This in turn may lead researchers to draw invalid statistical conclusions when conventional methods are utilized. The saddlepoint approximation has potential to lessen the degree of bias in sparse data conditions through its use of moments beyond the mean and variance, which allows for more accurate approximations using a smaller number of observations. We propose two novel saddlepoint methods for use in practical analysis scenarios, as an alternative to maximum likelihood estimation. First, we develop a multivariate saddlepoint approximation for use in generalized linear models that allows for estimation and hypothesis testing of multiple model parameters simultaneously using the saddlepoint approach. Second, we develop a saddlepoint approximation method for use in clustered data scenarios. We demonstrate these methods to be suitable alternatives in small sample and sparse data conditions
The Desert Shall Rejoice: LDS Relational Values and Multispecies Justice in the Intermountain West
Get PDFIn the American West, climate change is shifting weather and climate patterns in ways that may dramatically change lands, livelihoods, and communities. In the face of these threats, conservationists and local communities must work collaboratively to ensure that environmental and human communities are healthy enough to weather approaching shifts. Church of Jesus Christ of Latter-day Saint (LDS) values, practices, and histories strongly influence the Intermountain West, yet there is little research on LDS environmental values and perceptions. This study seeks to answer questions that work in this gap. It documents the knowledge and values of communities in the Intermountain West in two LDS-dominated contexts: 1) in a small, collaborative, rural conservation project led by the Northwestern Band of the Shoshone Nation in a watershed dominated by white, LDS producers, and 2) among LDS individuals residing in mostly urban and suburban areas across the Great Salt Lake Watershed. This research describes the values that link LDS communities to land and water, identifying tools and frameworks that might support ecological well-being in these communities during a time of dramatic climatic change in the West. I build on existing work to share an “Agricultural Transformation Typology” that can be used by extension agents and others working with rural producers to contribute to climate adaptation on private lands in the face of projected ecological shifts. I also describe LDS perspectives on rights- and justice-based approaches to environmental problems in the watershed, especially related to the declining Great Salt Lake. I examine LDS doctrines, histories, and current perceptions in the Great Salt Lake Watershed to do this. I then explore a “Mormon multispecies ethic” to increase understanding and potential areas for collaboration between conservationists and LDS communities in the Intermountain West
Effects of Plant Biostimulants on Onion Growth and Production Under Greenhouse and Field Conditions
Get PDFThe escalating impact of climate change on agricultural production underscores the need to investigate sustainable crop enhancement methods. This research explores the use of plant biostimulants to grow onion (Allium cepa L.) under varying environmental conditions. In the initial germination and greenhouse screening, seven biostimulants were tested on ‘Vaquero’ onion seeds: three bacterial products (Continuum, Spectrum DS, and Tribus Original), two mycorrhizal products (Mighty Mycorrhizae and Myco Apply), one seaweed extract product (Seaweed), and one product containing humic acid (Huma Pro 16). Mighty Mycorrhizae, Continuum, and Myco Apply supported faster germination, while seeds treated with Spectrum and Seaweed took longer. The speed and uniformity of germination showed limited difference across the applied biostimulants. In the greenhouse test, cluster analysis identified Huma Pro 16 (humic) and Spectrum DS (spectrum) as the most effective biostimulants based seedling emergence, leaf area, and biomass. Following this, field trials were conducted with four onion cultivars: ‘Bridewhite’ (white), ‘Marenge’ (red), ‘Walla Walla’(sweet), and ‘Vaquero’(yellow), subjected to water [ conditions simulating Drought (75% reference evapotranspiration, ETr) or Wet (100% ETr)] or nitrogen [reduced (-N:100 lbs·ac-1) or recommended (+N:150 lbs·ac-1)] treatments. ‘Vaquero’ onions performed better under both water and nitrogen treatments. The total yield of ‘Vaquero’ onions was higher under Control Wet (no biostimulant), Humic Wet, and Spectrum Wet treatments compared with ‘Walla Walla’ onions which had lower yield under Spectrum Drought and Wet treatments. Similarly, under nitrogen treatments, ‘Vaquero’ onions produced the highest yield under Humic -N, Humic +N, and Spectrum +N compared with ‘Marenge’ onions under Control -N and Humic +N and ‘Walla Walla’ onions under Humic and Spectrum treatments. Although biostimulants, water or nitrogen treatments did not affect onion storage after harvest, ‘Walla Walla’ onions experienced the highest yield loss and rot, while ‘Vaquero’ had the lowest loss and more single centered bulbs across treatments. Biostimulant effectiveness varied by cultivar, water availability, and nutrient levels, highlighting the need for further research to optimize their use in onion growth and production under adverse environmental conditions
A Survey of Master\u27s Qualifying Exam Practices and Content in Real Analysis
Get PDFGraduate programs in mathematics are intended to develop experts in mathematics. As part of a graduate program, many students are expected to engage in a qualifying examination that can serve myriad purposes. This dissertation investigates real analysis qualifying examinations at the master\u27s level through a nation-wide survey of institutions in the Association of Public and Land-Grant Universities (APLU). This study reveals the practices in administration of real analysis qualifying exams, institutions reported offering traditional, pencil-and-paper exams and generally asked students to prepare individually using previously administered exams. The survey results show that approximately two in three APLU institutions offering master\u27s degrees in mathematics assess real analysis in some form, including traditional exams or coursework. When a qualifying exam is given, the majority of institutions offer students two exam attempts to pass. Furthermore, the content of qualifying exams was studies. Results showed that exam items fell into one of two areas: Advanced Calculus and Real Analysis (i.e., measure theory), with further sub-areas defined based on an analysis of textbooks in-use. Of the sample of qualifying exams from nine institutions, five institutions emphasized Advanced Calculus, three emphasized Real Analysis and one had a roughly even ratio of Advanced Calculus and Real Analysis content. The content analysis was validated using three coders. This dissertation offers a framework connecting the memory demands on the student required to transfer from the task to the solution. Coders applied this framework and results show over half of the items required a high level of memory demands, or transfer, and approximately 15% required simple knowledge-level understanding. Data about content and transfer levels of exam items are contained in this dissertation
Bugs Pay for Days of Steady Reservoir Releases to Reduce Hydropeaking Ecosystem Conflict
Get PDFSteady low reservoir releases increase downstream primary and aquatic invertebrate (bugs) production. These releases also reduce hydropeaking value, raise costs for hydropower customers, and reduce funds to maintain infrastructure and repay loans. This study quantifies the win-lose tradeoff between hydropeaking value and days per month of steady low releases at Glen Canyon Dam, Arizona. We estimate win-lose tradeoffs for monthly release volumes of 0.71 to 0.95 million acre-feet from March to October 2018 and 0 to 31 days. Conservative estimates indicate that steady low releases on eight weekend days per summer month in 2018 reduced monthly hydropeaking value by 850,000. We used results to design a financial instrument that gives ecosystem managers a budget to choose days of steady low releases and pay hydropower producers for lost value. One option to reduce costs is shifting days of steady low releases to spring/fall months. Next steps include discussing the proposed instrument with more U.S. Federal agencies, conducting more flow experiments, and monitoring how timing and more steady low flow days per month affect bug production. Managers may extend to other experimental releases that mobilize sediment, build sand bars, or disadvantage non-native fish
Age-Based Variations in Frequent Emergency Department (ED) Use Among Older Adults: An Analysis Using the New York University–Johns Hopkins University Emergency Department Algorithm (NYU/JHU-EDA)
Get PDFPopulation aging impacts the utilization of health services, especially in Emergency Departments (EDs). A rising share of older adults in the US report ED use, especially frequent ED use, defined as ≥ 4 visits annually. Prior works have examined frequent utilization of EDs among geriatric populations, but no study has focused on age-based trends or examined type of ED care sought by different age groups. Thus, using the 2017-2019 State Emergency Department Databases (SEDD), we examined how types of ED care influenced frequent ED utilization among geriatric patients in Maryland across the three age groups of youngest-old (65–74), middle-old (75–84), and oldest-old (85 and above), after controlling for covariates. Types of ED care included emergent, primary-care-sensitive conditions (PCSC), injuries, and behavioral conditions which were identified using the New York University–Johns Hopkins University Emergency Department Algorithm. Over the study period, frequent geriatric users made up 13.86% and 3.68% of all ED visits and ED patients respectively. The probabilities for being a frequent user was the lowest for nonsevere injuries (2.3%–2.7%) and the highest for care related to alcohol, drug, and psychological disorders (ADP: 5.0%–8.7%). The youngest-old and middle-old had a higher predicted probability of visiting the ED frequently for PCSC (4.1%) compared to the oldest-olds (3.8%). The youngest-old had the highest predicted probability of visiting the ED frequently for ADP (8.7%), while the oldest-old reported the highest predicted probability of visiting the ED frequently for severe injuries (3.7%). These findings are critical to healthcare stakeholders to better understand the heterogeneous medical needs of the different older adult age groups
On the Connection Between Sport and Morality: Does Russell’s ‘Continuity Thesis’ Hold Water?
No full textThe connection between sport and morality is a key focus of J. S. Russell’s scholarly work. He rejects the ‘separation thesis’, which claims that sport has a significant degree of autonomy and thus its own set of values separate from those of society. Instead, he supports the ‘continuity thesis,’ which suggests that the moral values at the heart of sport reflect more basic moral values found outside its boundaries. Therefore, for Russell, individuals involved in sport do not leave ordinary morality to enter a separate sporting one. Rather, they engage in a social practice whose core moral principles are extensions of broader morality. In this paper, we challenge Russell’s defense of the continuity thesis by analyzing his writings on the role of play in sport and the value of dangerous sport. The opening section reviews the separation and continuity theses. Next, we critique Russell’s defense of the continuity thesis, presenting him with two options outlined in the following section. One option is to more effectively explain how his defense of the continuity thesis aligns with the moral exceptionalism he supports for play and dangerous sports, as well as the actions and valuations they foster and legitimize. The second option is to consider whether, in some cases, certain values are discontinuous with and therefore do not simply express, reflect, or reinforce general moral ideals and commitments outside sport. In that section, we also propose an alternative to the dyadic conceit—the ‘separanuity thesis’—to clarify the link between sport and morality, and we encourage Russell to reflect on it in light of our examination of his work. We close by outlining how his discussion of risk and play affirms our proposal
The Renovated Aperture Area Measurement Facility at the National Institute of Standards and Technology (NIST)
No full textApertures with precisely known area are used in radiometry and photometry to define the optical phase space into which radiant flux is emitted or received. For example, solid angle, needed for the realization of the Candela, is realized with apertures of known area. Another common application is the measurement of irradiance, the radiant flux received at a surface per unit area (or its photometric analog illuminance), which requires an aperture with known area to be placed in front of an optical radiation sensor.
Beginning in the 1990s the National Institute of Standards and Technology (NIST) has developed improved methods for the measurement of radiometric aperture areas to meet the need for aperture area measurements with combined relative standard uncertainties of about 10^4 or lower. At that time a custom optical coordinate measuring machine was constructed at NIST for absolute aperture area measurements that are directly traceable to the length unit meter of the International System of Units (SI). This aperture area measurement (AAM) system consists of a planar air bearing stage with laser interferometer position feedback on both motion axes that is used to precisely locate the edge of an aperture in the focal plane of a high-magnification optical microscope. Aperture areas are calculated from aperture edge points measured along the full lengths of the aperture edges. NIST has provided aperture area calibrations since the early 2000s using the AAM system.
During a recent renovation of the AAM instrument, several components that had become obsolete were updated, including the optical microscope, the camera, and parts of the illumination system. The operating software for the AAM instrument and the software for data analysis was also replaced to take advantage of improved and more widely available algorithms for image processing. My presentation will describe the renovated AAM instrument, the revised traceability of aperture area measurements to the SI, and I will outline the potential for further improvements of the AAM instrument at NIST in the future
Spectral Quantum Efficiency Calibration of Mid-Infrared Single Photon Detectors
No full textSuperconducting Nanowire Single Photon Detectors (SNSPDs) can count individual photon hits with a very high efficiency, a very low dark count rate, and very fine time resolution. Since the output is naturally digital, they are an especially promising technology for space missions including NASA’s Origins Space Telescope and Large Interferometer For Exoplanets (LIFE). Over the past 5 years, significant progress has been made in the development of SNSPDs that can sense lower energy photons such as those in the mid-infrared, but the quantum efficiency of these devices remains poorly quantified. The Low Background Infrared (LBIR) facility at NIST has a cryogenic system that can reach 300 mK that is being developed as a test platform for spectral quantum efficiency calibrations of SNSPDs in the wavelength range of 3 μm to 25 μm. The system will include a mirror that can flip between the SNSPD under test and a reference Blocked- Impurity-Band (BIB) detector. The photon source is currently a laser fed through an optical fiber, but a future upgrade to the system will interface it to a second cryogenic chamber containing a source of the operator’s choosing