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Structure of tropopause polar vortices represented from the atmospheric profiles of satellite observations
Get PDFTropopause polar vortices (TPVs) are sub-synoptic tropopause disturbances commonly found poleward of the polar jet stream. Their roles in cyclogenesis and linkages to mid-latitude weather make them relevant to the improvement of numerical weather prediction. Previous TPV studies have been mostly model-based, whereas observational studies are limited. The purpose of this study is to characterize the three-dimensional composite temperature and water vapor structure of TPVs using retrieved atmospheric quantities from the Atmospheric Infrared Sounder (AIRS) and to verify these results with the TPV structure documented in previous model-based and observational studies. The composite structure of AIRS-observed TPVs averaged over a one-year period exhibits a cold (warm) temperature anomaly and a positive (negative) relative humidity anomaly in the troposphere (lower stratosphere). TPV composites also reveal dry mixing ratio anomalies throughout the troposphere and lower stratosphere, and that the percent decrease in mixing ratio is largest at the tropopause at the vortex center. This study thus confirms TPV structure previously characterized in models and surface-based observations. This illustrates the potential usefulness that hyperspectral atmospheric profilers on polar-orbiting satellites have in representing TPVs over the high latitudes where observational data is scarce
A Study of Student Trust in Teachers in a Suburban School District
Get PDFThe formations, differences, and effects of student trust were examined in a midsized suburban school district where a sample of 1086 fourth, fifth, and sixth grade students were surveyed. Four research questions guided the study: Which facets of trust received the highest endorsements from students in relation to student trust in teachers? Are there differences in student trust in teachers by school? By grade level? What is the relationship between student trust and instructional styles of teachers? What is the relationship between student trust and engagement in school? Descriptive and summary analyses were performed on data to examine the relationship between the facets of trust, instructional styles of teachers, and student engagement. Evidence yielded the following claims: Students perceived teachers as being more benevolent, reliable, and competent than open and honest; Instructional styles experienced as supportive of student autonomy and competence were related to student trust in teachers; and student trust in teachers had a strong relationship with student engagement
The dynamics of mature and emerging freshwater conservation programs
Get PDFConservation programs range from small, place-based initiatives to large, bureaucracy-heavy systems. The dynamics of these programs vary greatly. New initiatives may experience exponential growth, but participation and spending in mature programs may rise and fall in response to a number of factors. Here, we analyze historical patterns of participation and spending across five freshwater conservation programs in the United States. Our analysis highlights fundamental differences between emerging programs, which may experience exponential or logistic growth, and mature programs with slower growth, in which changes in participation may be driven by a number of internal and exogenous factors. We propose that changes in the number and spatial distribution of conservation projects are associated with four key factors: changes in legislation that open new funding streams; shifting priorities of actors; changes in the policies or management of a program that align it with new funding opportunities; and increases in individuals’ willingness to participate in a program as it grows. These programmatic shifts represent windows of opportunity for strategically reorienting conservation programs to leverage newly-available resources. Given that large, mature conservation programs support biodiversity and ecosystem services worldwide, comparison of their dynamics with those of emerging programs may reveal key opportunities for maximizing the benefits of investments in these programs.SW was supported by a Nancy L. Mergler Dissertation Completion Fellowship at OU. Financial support was provided by the University of Oklahoma Libraries’ Open Access Fund.Ye
Gendered effects of sanctions on manufacturing employment: Evidence from Iran
Get PDFInternational sanctions have significant economic effects with long-lasting negative consequences for human development. However, academic research on the gendered effects of sanctions is scarce. In fact, most work on sanctions has been either gender neutral or gender blind. This article examines the labor market effects of economic and noneconomic sanctions, imposed by the United States and the United Nations, on male and female employment in manufacturing industries in Iran. The empirical analysis is based on four-digit industry-level employment data from 102 manufacturing industries between 1995 and 2014. Our main findings suggest that international sanctions have disproportionate effects on male and female employment. In particular, we find that sanctions hurt female employment significantly more than male employment. This effect is further compounded in industries that are more capital intensive, where labor compensation has a relatively low share in value added. Furthermore, in industries with relatively high reliance on imported inputs, female employment suffers more from sanctions.This is the peer reviewed version of the following article: Demir, Firat, and Saleh S. Tabrizy. "Gendered effects of sanctions on manufacturing employment: Evidence from Iran." Review of Development Economics (2022). It has been published in final form at https://doi.org/10.1111/rode.12917. This article may be used for noncommercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.The authors received funding from the University of Oklahoma College of Arts and Sciences Senior Faculty Summer Fellowship; University of Oklahoma Libraries; Fulbright Commission, and Carnegie Corporation of New York. Grant Number: G-20-57642.Ye
Effect of Water on Catalytic Reactions over Brønsted Zeolites
No full textWater is present in both conventional chemical transformations and conversion of renewable emerging feedstocks such as biomass and plastic waste. Solid acids and zeolites, in particular, have been one of the most common industrial heterogeneous catalysts for decades. Interestingly, the interactions of water with reaction intermediates and framework protons in Brønsted zeolites give rise to various catalytic effects. In the first part, the role of water in the acylation of a phenolic compound with a carboxylic acid representing the upgrading reaction of lignocellulosic biomass has been revealed. The bulky intermediate ester is an active acylating agent but diffuses slowly in MFI pores, which can be manipulated by co-feeding water. In the second part, the effect of water on the conversion of a non-polar hydrocarbon was studied. The presence of a sufficient concentration of water inside the zeolite pores enables the formation of hydrated hydronium ions, which enhances the cumene dealkylation due to entropic gain of the reaction transition state. Finally, the influence of water on the dehydration of a diol representing polar polymers in multilayer polymer films in the presence of a competitive polar aprotic solvent was investigated. The change in the adsorption states of the reaction intermediate and solvent molecules on framework Brønsted acid sites versus hydrated hydronium ions alleviates the inhibition effect of solvent and improves the dehydration of polyols
Moisture-wicking properties of fabric and their effect on blood and the angle of impact
Get PDFThe use of angle of impact calculations within bloodstain pattern analysis is limited to researched surface types which currently include smooth, non-porous materials and cotton. The purpose of this study was to determine if the existing equation for angle of impact could accurately be applied to moisture-wicking polyester. This study used posterboard as a control and tested three different polyester fabrics (100% polyester, 80% polycotton, and 20% polycotton). Bovine blood was dropped onto each of the four surfaces at 10° increments from 10° to 90°. The resulting stains were measured with digital calipers used in conjunction with drafting dividers. The measurements were analyzed using ANOVA and Tukey’s multiple comparisons test to determine and evaluate the significant differences between the surface types and the actual angles. The results showed that polyester significantly affected the ability to calculate angle of impact to within ±5°. The wicking property of polyester distorted the stains disproportionately so the angle of impact calculations were inaccurate at some angles. All three polyester samples had accurate calculations from 10° to 40°, but outside of that range, calculations were inconsistent and inaccurate. This information broadens the understanding of bloodstain analysis and can assist analysts in understanding the weight of their findings
Funnel-Shaped Floating Vessel Oil Skimmer with Joule Heating Sorption Functionality
Get PDFThis article belongs to the Special Issue Artificial Intelligence Enhanced Design of Polymer Materials and Manufacturing.Floating vessel-type oil collecting devices based on sorbent materials present potential solutions to oil spill cleanup that require a massive amount of sorbent material and manual labor. Additionally, continuous oil extraction from these devices presents opportunities for highly energy-efficient oil skimmers that use gravity as the oil/water separation mechanism. Herein, a sorbent-based oil skimmer (SOS) is developed with a novel funnel-shaped sorbent and vessel design for efficient and continuous extraction of various oils from the water surface. A carbon black (CB) embedded polydimethylsiloxane (PDMS) sponge material is characterized and used as the sorbent in the SOS. The nanocomposite sponge formulation is optimized for high reusability, hydrophobicity, and rapid oil absorption. Joule heating functionality of the sponge is also explored to rapidly absorb highly viscous oils that are a significant challenge for oil spill cleanup. The optimized sponge material with the highest porosity and 15 wt% CB loading is tested in the SOS for large-scale oil spill extraction tests and shows effective cleaning of oil spilled on the water surface. The SOS demonstrates a high maximum extraction rate of 200 mL/min for gasoline and maintains a high extraction rate performance upon reuse when the sponge funnel is cleaned and dried.Open Access fees paid for in whole or in part by the University of Oklahoma LibrariesYe
Outlawing and becoming native in the colonization of Yosemite National Park: a cultural-ecological perspective
Get PDFSince the 1980s, Environmental historians have produced research disproving the myth of pristine wilderness. Yet, few environmental historians have focused their research efforts on considering how such a myth may have affected specific environments throughout time. I look at the birth of Yosemite National Park and consider the role pristine wilderness may have had as it influenced the way people interact, live, and manage the land and resources within the park's boundaries. Most importantly, perhaps, I consider the role the wilderness idea played in removing Indigenous people from the valley, and the ecological consequences of that process. This research makes use of the works of prominent anthropologists and archeologists, primary documents such as meeting notes, publications, and superintendent reports from late nineteenth-century Yosemite management, as well as the writings andilkin imagery created by iconic figures that made the wilderness of Yosemite a global phenomenon.
Additionally, while appreciating the value of indigeneity as an ethnicity, some forward-thinking social scientists, both Native American and not, argue that self-nativization in regards to a person's role in their environment, or becoming a local, is necessary to restore our ailing ecosystems. In this regard, this thesis finds the process of self-nativeization, or becoming local, was a natural evolution for new settlers and colonizers in Yosemite in the late nineteenth century due to key environmental factors. Despite the government's repeated attempts to restrict and even make any type of nativization or localization illegal within the park, worldviews belonging to new inhabitants evolved during the process of colonizing Yosemite in the late nineteenth century. This detachment from empire to colonial actor reveals that the wilderness idea was more a product of the American colonial empire rather than a strict belief of individual inhabitants and new settlers of Yosemite
Innovative Growth Techniques and Heterogeneous Structures for PbSe-Based MWIR Photodetectors
Get PDFLead-chalcogenide semiconductor materials such as PbSe are an attractive class of narrow band-gap semiconductors due to their unique optical and electrical properties, finding their way into numerous mid-wave infrared (MWIR) optoelectronic and topological device applications. While PbSe is a mature material system with research efforts dating back almost a century, the full potential of its physical properties has yet to be realized in fabricated devices. Much of the difficulty lies in the unique bonding nature and crystal structure of PbSe films, which gives both advantageous MWIR optoelectrical properties along with a limited selection of suitable substrates for high-quality growth. Further, PbSe homojunction devices on dissimilar substrates face issues with doping, where diffusion of PbSe dopants through defect channels inhibit the formation of an abrupt junction resulting in degraded device performance. Further, p-n heterojunction formation with PbSe is difficult due to the small bandgap of PbSe, resulting in a shortlist of suitable materials with the corresponding band alignment to form a type-II heterojunction. Even for material systems that share a suitable band alignment, issues often arise with dissimilar crystallinity, lattice constant, and thermal expansion coefficient. The dissimilarity between these films introduces large stress/ strain relations at the interface, resulting in the formation of cracks or dislocations which ruin the interface and bulk electrical properties. For these reasons, PbSe-based MWIR devices have been surpassed by more competitive material systems such as II-VI HgCdTe, and Sb-based type-II superlattices.
In this work, new methods for improving PbSe film quality are explored, along with the growth and design of new heterogeneous structures and MWIR photodetectors which may improve the PbSe-based MWIR sensing platform. Presented here will be a new approach for creating heterogeneous material structures with PbSe by molecular beam epitaxy (MBE). Demonstration of a new heterogenous p-n junction structure between mismatched germanium substrates and epitaxial lead selenide thin-films will be introduced utilizing a vicinal growth surface. Extending from this, epitaxial PbSe films with enhanced surface morphology will also be demonstrated on vicinal silicon substrates, showcasing record low surface defect densities compared to traditional growth on nominal silicon. Regarding the former, germanium will also serve as an active layer in the formation of a p-n heterojunction structure due to its suitable type-II band alignment with PbSe. However, large differences in lattice constant and thermal expansion coefficient will need to be addressed to form such a structure. These challenges are tackled by optimizing the surface kinetics of PbSe adatoms through high-temperature surface treatment, along with utilizing misfit accommodation steps induced by the periodic atomic step edges from the high degree of vicinal miscut of the germanium growth surface. Further, different structures and device applications of PbSe-based material systems will be explored, including the growth of a new PbOSe complex oxide thin-film via oxygen-plasma assisted MBE deposition. Fabrication of a single phase (cubic) all-epitaxial n-CdSe/p-PbSe heterojunction structure with room temperature MWIR detection capabilities will also be presented, along with the fabrication of MWIR transparent contacts using cadmium oxide thin-films for enhanced photodetector device design. The combined results of these efforts provide multiple avenues for the development of state-of-the-art MWIR PbSe-based photodetectors, enabling future commercial MWIR sensing capabilities with reduced size, weight, power consumption, and cost
Integration of silica-based materials within a dye-sensitized solar cell
Get PDFDye-sensitized solar cells (DSSC) are a potential model to help aid in potential steps in solar energy efficiency and progress. However, measures taken have resulted in costly methods and a lack of supply in various materials, such as dyes, electrolytes, sealants, and glass – adjustments. The research team, led by Dr. Bidlack, has tackled various parts of the DSSC model to determine potential avenues of research and progress; the most recent method involving integrating silica or silica-heavy materials into a cell and evaluating its effect over time. For solar cells, light interactions are key to exciting electrons that eventually carry energy through the gradients within. We suggested that if light reactions could be utilized within a cell, an increase in potential light "hits" may increase the overall values of our previous models. The treatments groups for our silica-integrated cells included diatomaceous earth, phytoplankton, and horsetail extract; along with two control groups without treatments. Reasons for these chosen groups were to use non-costly materials and readily available materials that various countries and cities could obtain without major losses, as well as replacing methods and materials that bring could harm the environment from several angles. A general linear model (GLM) and ANOVA compared treatment groups with least significant differences in various combinations and variables. Data from three trials suggested that treatments with either horsetail or diatomaceous earth responded similarly across a ten-day period, and the physical influence of such materials. Horsetail-based devices had an average voltage of 155.71 mV and diatomaceous-earth cells reported an average of 138.75 mV during light intervals. Control cells without modification had averages of 63 mV (with dye) and 22 mV (no-dye). Our results suggested promising and interesting effects with silica-based resources along with potential ventures with these and similar materials. Light absorption and voltage may be enhanced by both silica, chlorophyll, and the physical nature of such materials. An experiment of this design has not been published and we believe that meaningful steps were taken with the progress in this research