1925 research outputs found
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Birkhoff polynomial interpolation with applications to differential equations
Get PDFAn error formula for Birkhoff interpolation of functions on R^s is developed. Some applications of the error formula to Birkhoff quadrature methods and finite difference methods are presented. In one dimension, the formula is used to find optimal placements of interpolation nodes that maximize the local rate of convergence of the interpolating polynomial to the interpolated function. An application of Birkhoff interpolation in approximating solutions of first order initial value problems is noted
Geospatial applications in southwest archaeology: an environmental suitability model for prehistoric surface pueblos
Get PDFGeospatial technologies in archaeology facilitate the interpretation of spatial context of both historic and prehistoric material culture as it is often expressed in both time and space. The primary focus of this research was to develop an environmental suitability model in ArcGIS Pro to determine high probability areas for prehistoric habitation sites primarily focusing on small, medium, and large masonry surface rooms within the Pleasant Valley Ranger District in the Tonto National Forest. By integrating decades of archaeological site records into a unified geodatabase, this research demonstrated viable data collection and organizational methods suitable for future comparative geospatial and statistical analysis of large archaeological datasets. The framework established for this research consisted of three main tasks: data collection; data coding, and spatial modeling. The integration of these three main tasks and the implementation of spatial operators such as containment, intersection, and proximity resulted in the identification of significant relationships between geology, biotic communities, and elevation and the locality of masonry surface pueblos
The role of detention officers at recreation time among women incarcerated in a southwest county jail
Get PDFThere are about a quarter million women incarcerated in the U.S. While incarcerated, many women deal with mental and physical health issues and inadequate access to healthcare services. One well-being program offered in most jail and prison settings is recreation time, a time for people incarcerated to exercise. Exercise and time outdoors can contribute to positive health outcomes, including alleviating depression. Women incarcerated value recreation time for fresh
air, natural light, mental health benefits, and opportunity to exercise. However, a large portion do not attend recreation time and often face a variety of barriers to their attendance. Among the factors that influence women’s rec-time attendance are detention officers (DOs). Further research is needed to explore DOs’ role at recreation time. Using two cross-sectional questionnaires at the Coconino County Detention Facility, this study explored and compared women’s and DOs’perspectives on DO-related factors influencing recreation time among women incarcerated. The results indicated that the DOs have a limited role at recreation time, which was primarily as a neutral and impersonal facilitator. While DOs and women shared similar views on the women’s attendance of recreation time and the DOs’ role as a recreation time facilitator, they had differing
views about whether DOs could impact whether women attended recreation time and the barriers that women face in accessing it. Women incarcerated indicated the various types of roles DOs have at recreation time and offered recommendations for the jail and DOs about how to improve the program
The effect of series elasticity on the force-length relationship of skeletal muscle
Get PDFSkeletal muscle contains molecular motors that allow for voluntary movement in vertebrate organisms. It has been widely accepted that skeletal muscle has a narrow range of operating lengths that provide peak force and that this force-length relationship is dictated by the amount of overlap of thick and thin myofilaments. However, much remains unknown about the molecular mechanics of skeletal muscle. This is especially true in dynamic movement, where the isometric force-length relationship tends to fall short in accurately predicting optimum length, the length at which peak force is produced. When attempting to predict in vivo muscle behavior with the isometric force-length relationship, systematic errors may occur due to varying activation levels, active length changes, and lack of structural homogeneity between organisms and within an organism. To elucidate a potential mechanism for observed experimental shifts in optimum length with varying activation levels, experiments were performed on muscles with parallel fiber orientation that were sutured to an external in-series artificial elastic component with considerable compliance. These muscles were attached to a stationary clamp on one side and a force-measuring ergometer on the other. Maximal contractions were elicited at a wide range of starting lengths both with and without the artificial tendon and force-length graphs were constructed. Optimum length with an artificial tendon and resultant shortening decreases to approximately 89.26 ± 5.21% compared to the optimum length of purely isometric contractions. This lends support to the hypothesis that a purely mechanical mechanism driven by shortening may be responsible for the majority of the shifts in optimum length and that, similar to observations in experiments with varying activation levels, this shift may not be driven solely by the length dependence of calcium sensitivity
Implications of Chinese overseas mining operations for community-level social conflicts
Get PDFIn the context of increasing foreign mining activities and their impacts, and the growing number of social conflicts resulting from mining operations, this dissertation investigates whether Chinese multinational corporation (MNC) investment is positively associated with social conflict, and if so, whether that relationship is a result of MNC practices, and/or other factors. Broadly speaking, scholars paint a picture in which China’s political regime together with its national culture and its economic development path influence Chinese extractive MNCs’ activities abroad and might contribute to more social conflict. At the same time, scholars writing on extractive conflicts have argued that conflicts result from companies’ inadequate performances, especially regarding community engagement practices. That is, in this second view, social conflict is due to mistakes that any company could make; that is, there is no “Chinese way” of operating abroad. The dissertation thus engages the following research questions: How do Chinese firms affect socio-environmental conflict around extraction? Why? To what extent do firm practices explain variation in conflict? Through quantitative and Geographical Information System (GIS) analysis and comparative case studies, this dissertation finds that firms with better social responsibility performance generate less conflict and Chinese firms do not confront more conflict than other foreign-owned firms. This finding has theoretical contributions as the results that Chinese mining MNCs do not perform worse threaten to falsify much of what has been discussed about Chinese mining firms, that they behave worse and cause conflict. Given the prominence of Chinese firms in mining globally, the study’s focus on Chinese MNC mining projects contributes to our understanding of extractive conflict, with implications for the trajectory of extractive sectors and, in turn, alternative or sustainable development options
Pollinator species distributions and interaction networks across local environmental gradients to continental scales
No full textInsect pollinator species are critical for angiosperm reproduction and maintenance of human food crop populations. Insect pollination networks are complex webs of overlapping links, and mutualistic associations between these pollinators and their host plants are imperative for network stability and robustness in the face of ecosystem perturbation. Even slight changes in the structure of mutualistic associations can affect the underlying topological features of pollination systems. While pollinator and plant species richness, abundance, or overall composition of plant-pollinator interactions may shift organically over time (seasons, months) and space (environmental gradients), warming temperatures are already causing unanticipated changes in plant-pollinator communities on local scales. My dissertation focuses on the local pollination networks of the San Francisco Peaks in northern Arizona. In Chapter Two, I evaluate how species richness, abundance, and critical network properties change across three life zones (vegetation zones) of this unique elevational gradient. I also determine the critical generalist pollinator species responsible for community stability in the highest elevation life zone. In Chapter Three, I evaluate the impacts of short-term drought on the plant-pollinator communities of the San Francisco Peaks. Specifically, in the 2017-2018 winter and spring seasons, Flagstaff experienced especially dry conditions, with very minimal precipitation and a significant 43-day period in spring with no rainfall. This allowed for a unique opportunity to compare year-to-year differences in species richness, abundance, and timing of flowering/foraging periods across seasons. I also examine the potential shift in pollinator species generalization (diet breadth) in the dry year and how this may vary across life zones. However, to predict the impacts of global change on insect pollinator species diversity and distribution, studies must also be conducted at regional and global scales. In Chapter Four, I perform large-scale analyses of current USA bee data completeness using 1.923 million occurrence records for the contiguous United States. I determine clear sampling biases for certain taxa and geographic locations as well as identify undersampled areas that are likely hotspots for bee diversity. Additionally, I show that even if we were to digitize the remaining ~6 million collected-yet-undigitized bee specimens in institutions, this would not be sufficient to fill gaps, underscoring the need for more strategic sampling and monitoring programs. I conclude this dissertation by highlighting how understanding insect pollinator species distributions and their mutualistic associations is fundamental for pollinator conservation, and that this holds true across local, regional, and global scales
Comparing environmental DNA and microscope identification for assessments of macroinvertebrate biodiversity in northern Arizona
Get PDFIn the arid southwestern region of the United States, increased temperatures and more variable precipitation associated with climate change will change the biodiversity and productivity of small water bodies such as ponds and wetlands. Ponds are isolated and closed systems, the lack of water flow allows DNA to accumulate within these systems, which makes ponds an excellent system to use environmental DNA (eDNA). This study compared the frequency and richness of invertebrates found in eight stock ponds in 2019 by eDNA and community sampling followed by microscope identifications. To target kingdom Animalia and phylum Arthropoda, eDNA was sequenced for the cytochrome oxidase I (COI) mitochondrial marker using BR5 and F230 primers. Environmental DNA metabarcoding for ponds resulted in higher richness than microscope identification (p-value=0.0024). However, when eDNA sequences with low resolution taxonomic identifications (e.g., only to phylum) were removed from the dataset, microscope richness was higher (p-value= 0.03). Further development of sampling and data processing workflows, and comprehensive reference sequence databases for regional species would help the utility of eDNA as an identification method in this region. Coupling eDNA with microscope identification could provide the information to determine stock pond biodiversity the most accurately, which can function as a proxy for pond secondary productivity. By integrating microscope and eDNA methods, managers can more efficiently identify which ponds are priority to maintain with their limited resources
Food perceptions of black and brown community members are bigger than the map in San diego, California
Get PDFA relationship between food, health and economics can be traced back to the beginning of colonization and unfortunately these relationships are still heavily prevalent in Black and Brown communities in the United States. The United States had multiple changes in agricultural and economic policies in the twentieth century, which begs the question, what are the perspectives of marginalized groups who may have noticed the food regime changes over the decades? From May 2022 through August 2022, fifteen participants, ages 18 and older were interviewed on their perspectives on food insecurity in Black and Brown communities in San Diego, California. In Chapter One, I explored the history of United States political economics and how these policies effect U.S. food systems today. I, also, observed the policy effects on independent grocers and major chain grocers and how these policies effect consumers without them knowing. Many independent grocers had hidden butcher shops in their stores but had a lay out of a 7-Eleven than a grocery store. Many of the stores sold generic brand names from larger retail chains. In Chapter Two, I focused on where my participants preferred to grocery shop and if their health influenced changes to their eating habits. My participants were very specific about the stores they liked to frequent but felt like it was within their community despite to being in an adjacent city. One of my participants was healthy but noted simple health swaps to avoid a health predisposition. In Chapter Three, I focused on the growth of community gardens and farmer’s markets in Black and Brown communities and how community members benefit from having these options. I personally observed youth cultivating and selling their own produce to learn growing and business skills for them to take into the future. This study would add to the growing anthology of food equality research happening in anthropology by adding discourse from Black and Brown communities from San Diego, California
Identifying candidate loci for drought tolerance in Douglas-fir
Get PDFDouglas-fir (Pseudotsuga menziesii) is an economically and ecologically important conifer species native to North America that is currently experiencing an increase in drought conditions due to climate change. Two varieties of Douglas-fir are widely recognized: coastal (var.menziesii) and interior (var. glauca). These two varieties hybridize to produce coastal x interior
inter-varietal hybrids. This work aims to utilize newly developed genetic resources to analyze population structure and understand the genetic basis of drought tolerance in natural populations of Douglas-fir. This study uses an annotated reference genome, genome-wide single nucleotide polymorphisms (SNPs) molecular markers, and physiological measurements in greenhouse seedlings to gain insight into population structure, and to test for associations between phenotypic and environmental data. This work explores the genetic basis of drought tolerance by identifying candidate genes that are significantly associated with water-use efficiency (WUE) (inferred from carbon isotope ratios), photosynthetic rates (inferred from % nitrogen), osmolality, stomatal density, stomatal rows, and heights at 4, 25, 37 and 48 months. Further, population structure was analyzed to confirm genetic varieties and to understand how candidate
genes are distributed across the species’ geographic range. Lastly, a drought experiment was implemented on Douglas-fir seedlings to understand the physiological response to drought stress and expand upon previous work that was only conducted on well-watered seedlings. The results of our population structure analysis indicate four genetic clusters: coastal, hybrid, interior north, and interior south. Our results identified 402 unique SNPs associated with drought tolerance that map to 337 unique genes. Due to the absence of a chromosome-scale reference genome and linkage map in Douglas-fir, candidate loci were located only in scaffolds and not in chromosomes. A trade-off was found between tree height at 48 months old and percent nitrogen in well-watered conditions. Percent nitrogen is indicative of photosynthetic capacity; therefore, our results indicate a trade-off between tree height and photosynthetic capacity. This likely arises from the nitrogen budget where plants can either use their nitrogen for the production of cell walls or for photosynthesis. Results from the drought experiment indicates increased WUE in hybrids compared to the pure varieties when placed under drought stress due to an increase in δ13C. Plants will often avoid drought stress by closing their stomata to avoid transpiration. Hybrid individuals, having an increased δ13C under drought conditions, are likely closing their stomata and dealing with the 13C that accumulates as they use 12C for photosynthesis. Drought stress and the use of 13C for photosynthesis can produce reactive oxygen species (ROS). Therefore, hybrid individuals may have a better molecular and physiological response for dealing with drought conditions and ROS. Further, plants will store solutes as a method of holding onto the available water within their cells, this is referred to as osmotic potential. However, there was no significant difference in osmotic potential under well-watered or drought conditions in this study. Future studies should increase the sample size of osmotic potential under well-watered and drought conditions to further understand physiological and genetic responses to drought
Adult learner approach to transformational change: an interpretive phenomenological analysis
Get PDFThis qualitative study was an exploration of the lived experiences of adult learners (over age 24) enrolled in graduate teacher preparation programs and their distinct needs and expectations related to program entry, persistence, and completion. Five graduate teacher preparation degree-seeking study participants openly shared their respective academic and lived experiences. With a theoretical framework comprised of Knowles’ andragogy theory and Vygotsky’s theory of social constructivism, an inductive approach to data analysis facilitated condensing extensive and varied raw data to code-listed categories and themes. Interpretive phenomenological analysis was appropriate to show how adult learners make sense of their academic and lived experiences and the efforts they made to conquer challenges during program entry, persistence, and completion. Several themes emerged aligned to the research question and subquestion: How do adult learners make sense of their academic and lived experiences as they enter, persist, and complete their graduate teacher preparation program? and, How do adult learners engage and negotiate the university experience to meet their needs and expectations? This study contributed to the literature on how adult learners engage and negotiate their experience in graduate teacher preparation to make sense of met and unmet needs