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A Comparison of Spinal Reflex Function and Morphological Adaptations of the Achilles Tendon Between Individuals Chronically Post-Stroke and Healthy Controls
No full textPurpose/Hypothesis: The hallmark gait deviation in individuals with post-stroke hemiparesis is slow walking speed. Reduction in gait speed after stroke is influenced by decreased propulsive forces, which may likely be related to impaired spinal circuit function and spasticity of the paretic plantarflexors. Chronic muscle tone maladaptations in paretic ankle plantarflexors can result in altered Achilles tendon (AT) morphology, therefore leading to altered mechanical properties, force transmission capabilities and subsequent insufficient propulsive forces during walking. The purpose of this study is to characterize the chronic maladaptations in both the spinal Ia afferent loop excitability and AT morphology after stroke lesions in the brain in individuals with chronic post-stroke hemiparesis.
Materials and Methods: Nineteen non-neurologically impaired individuals and fifteen neurologically impaired individuals participated in this study. Ultrasound imaging was conducted, acquiring two views at three locations along bilateral ATs to measure tendon thickness, cross-sectional area (CSA), and collagen fiber organization. Spinal Ia afferent loop excitability was assessed by measuring the soleus (SOL) H-reflex amplitude. Surface electromyography of the tibial nerve was recorded using surface electrodes on the SOL muscle to obtain a recruitment curve. Peak-to-peak amplitudes of the H-reflexes were averaged, and expressed as Hmax/Mmax. Outcome measurements to assess spasticity and level of function in individuals with post-stroke hemiparesis were also performed. Additionally, all individuals participated in a 10-Meter Walk Test (10MWT) to assess gait speed. One-way ANOVAs with repeated measures and post hoc analyses were conducted to compare the tendon morphology and H-reflex amplitudes of the paretic and non-paretic limbs in individual with post-stroke hemiparesis, as well as the non-impaired limb (right limb) in non-neurologically impaired individuals.
Results: We observed significantly greater thickness of the AT at the calcaneal insertion and midportion, as well as increased collagen fiber disorganization at the calcaneal site of the paretic limbs when compared to non-neurologically impaired limbs. It was also observed that individuals with chronic post-stroke hemiparesis had slower self-selected walking speeds compared to the non-neurologically impaired individuals as measured via the 10MWT (p \u3c 0.05). No significant difference in CSA was found amongst the groups. No statistically significant differences in Hmax/Mmax ratios were found in the paretic legs compared to the non-paretic and non-impaired legs in the paretic limbs of individuals post-stroke.
Conclusion: This study found that tendon thickening and increased collagen fiber disorganization in the insertion site of the AT were present in the paretic limb, which may explain the reduction in propulsive forces needed for adequate gait speed in individuals with post-stroke hemiparesis. Our findings also depict no significant difference in Hmax/Mmax ratio in the paretic limb of individuals with post-stroke hemiparesis compared to non-neurologically impaired individuals. The changes in H-reflex excitability of the paretic plantarflexors and altered morphology observed in the paretic Achilles tendon potentially underlie post-stroke walking deficits. Thus, future rehabilitation programs should consider adopting an integrated approach addressing both neurological and mechanical deficits to restore walking function in individuals chronically post-stroke
Fluid Flow, Mineralization and Deformation in an Oceanic Detachment Fault: Microtextural, Geochemical and Isotopic Evidence From Pyrite at 13°30′N on the Mid-Atlantic Ridge
No full textHydrothermal fluids in ultramafic-hosted hydrothermal systems associated with oceanic detachment faults can be more oxidizing compared to mafic-hosted vent sites. These fluids form a mineral assemblage of pyrite, magnetite and hematite. At 13°30′N on the Mid-Atlantic Ridge, chlorite-quartz breccias recovered from an exposed fault scarp contain pyrite, with abundant magnetite and hematite, indicating that the redox of the fluids was variable. In primary micron-scale zonations in pyrite, Ni, Co, and Se have a decoupled relationship, recording fluctuations in the chemical composition and temperature of hydrothermal fluid as the grains grew. Secondary zonations that erase and overprint primary zonations are limited to the grain margin and permeable regions within the grain core. Secondary zonations formed via two processes: (a) grain dissolution followed by overgrowth, and (b) remobilization of metals during oxidizing fluid flow events. In both instances, Ni and Co have been mobilized and concentrated, and are not lost to the hydrothermal fluid. Superimposed on these features is evidence of grain scale deformation related to periods of fault movement along the detachment surface. Sulfur isotope ratios (δ34S) in pyrite systematically decrease from the grain margin to the grain core, indicating that increased amounts of sulfur were derived from thermochemical sulfate reduction of seawater. Thus, pyrite records the evolution of fluid flow and deformation events during exhumation along the detachment surface from ∼1 to 2 km below the seafloor at the base of the lava pile, with temporal fluctuations in fluid redox identified as an important process in controlling Ni and Co enrichment in pyrite
Discerning Moral Injury
No full textMoral injury is a recently developed psychological construct used to explain trauma that cannot be adequately explained by post-traumatic stress disorder (PTSD). It arises from experiences in which sufferers feel that they have violated deeply held moral beliefs and has multiple negative long term health and professional consequences for individuals affected. In order to better understand moral injury, this study seeks to understand how it is identified in individuals by others and utilizes Christie’s (2018) Ideal Victim Theory and Gray and Wegner’s (2009) Moral Typecasting Theory as a theoretical framework. Participants for this study were 374 undergraduate students at the University of Nevada, Las Vegas. Participants were asked to complete an online questionnaire in order to gauge how they identified moral injury in various contexts and populations. Repeated measures and one-way ANOVAs and a confirmatory factor analysis were used to analyze the data for this sample. Data analysis found that participant identification of moral injury was related by the context, indicators, ACE scores, and the gender presented in the scenarios
Multihalle Pavilion: The Renovation of an Innovative, Experimental Structure From the 1970s
No full textThis article discusses the significance and challenges of renovating a unique 1970s experimental timber building and iconic structure: the Multihalle Pavilion in Mannheim (Germany), which has the world’s first and largest self-supporting wooden grid shell roof structure. Originally conceived as a temporary structure for the 1975 Federal Garden Exposition, Multihalle uses a lattice grid shell structure with gentle curves, remarkably slim profiles, and a translucent roof. The term ‘grid shell’ refers to a doubly curved surface formed from the lattice of timber with uniform spacing in two directions. Furthermore, this was one of the first buildings in Germany whose plan and drawings for components were designed using a computer system, well before the arrival of ubiquitous CAD programs. The purpose of the article is to widely disseminate knowledge about an innovative building and to provide an update on the project and its ongoing renovation efforts, as recently observed by the author during a site visit. The article first discusses the history and significance of the building, its unusual structural solutions, and explains the project’s background. It then reports on the current state of the rescue initiative, the various renovation activities, and concludes with the outcome of a 2019 design competition, which called for new usage concepts to regenerate Multihalle; it produced sustainable and viable options for its redevelopment by conversion into a leisure, sports and cultural complex. A main conclusion is that the innovation and learning derived from the renovation of such an unusual structure are of immense relevance and importance for future projects. The renovation of this experimental building was not without risks and technical challenges, and the fund-raising took longer than initially expected; however, based on its influential contribution to 20th century architecture, it is also an important commitment to the preservation of our cultural heritage from the 1970s
Suburban Sustainability Lessons From History and Environment, Innovations for Tomorrow
No full textThis study explores the re-imagining of outdoor spaces in suburban homes within the context of Las Vegas, utilizing vernacular architecture principles and climate-responsive sustainable solutions to enhance residents’ quality of life. Las Vegas, situated in a desert climate, presents unique challenges in terms of sustainable living and outdoor comfort due to extreme temperatures and limited water resources.
By incorporating vernacular architectural elements and adopting climate-responsive strategies, this study aims to propose innovative approaches to outdoor space design that promote environmental sustainability, cultural identity, and improved well-being for suburban residents. Through an analysis of vernacular architecture, climate data, and sustainable design principles, this thesis offers practical recommendations for optimizing outdoor spaces in suburban homes to better suit the needs of Las Vegas residents while mitigating environmental impact.https://oasis.library.unlv.edu/arch_grad_capstones/1055/thumbnail.jp
Regulation of Embryonic Eye Regrowth in Xenopus Laevis
No full textRegrowth of lost organs and tissues is an amazing ability that some animals possess. For regrowth to be considered full, the organism must regrow the organ or tissue to a state that is structurally and functionally similar to that which was lost. The ability of an organism to regrow lost or damaged tissue varies among animals, both in the mechanisms utilized to achieve regrowth, and in what body parts can be regrown. Potentially even closely related species can vary wildly in regenerative ability. Therefore, regenerative research can look to other tissues and organisms for direction in elucidating the mechanisms through which regrowth is achieved, we must individually determine these mechanisms for each unique organism and tissue.
The Tseng laboratory has determined that the African clawed frog, Xenopus laevis can regrow its embryonic eye. This regrowth is achieved in a period of five days following ablation of the developing optic cup and lens placode at developmental stage 27, and the regrown eye is physiologically indistinguishable from the normally developed eye and is functional. This ability is lost as the animal ages, with mature eyes being incapable of full regrowth. We are interested in determining how the embryonic eye achieves regrowth. What are the signals regulating regrowth and does regrowth recapitulate development of the eye? This dissertation helps to elucidate some of the answers to these larger questions.
Within our model of regrowth, eye development and regrowth are taking place concurrently, creating interesting questions about timings and order of development/regrowth of the ablated eye. Xenopus eye development is well studied, which allows us to compare our regenerative mechanisms to well-known developmental mechanisms and timings. During Xenopus eye development, the retinal cells differentiate in a particular, overlapping order: ganglion cells, horizontal cells, cones, rods, amacrine, bipolar, and finally Müller glial cells. We determined that during eye regrowth, the retinal cells differentiate in this order as well. Additionally, the regrowing eye has a delay in eye formation compared to the normal developing eye (as determined by morphology and molecular markers) for two days, but by the third day post-surgery, it has caught up to the contralateral eye.
We have determined the overall morphology of the eye during regrowth. However we do not know many of the mechanisms regulating regrowth. Previous work in our laboratory determined that inhibition of apoptosis and Pax6 both independently inhibit eye regrowth, but there are likely other regulators at work. My work determined that the Notch signaling pathway is required for regrowth of the Xenopus embryonic eye.
The Notch signaling pathway is a conserved developmental pathway that regulates proliferation and differentiation. The pathway is activated through cell-to-cell signaling, with ligand binding triggering a cleavage of the receptor then acts as a transcription factor in the nucleus. I determined that Notch signaling during eye regrowth is required during the first day of the five-day period. Previous work demonstrated an increased amount of proliferation during that period, and by inhibiting Notch1 signaling during the regrowth period, a significant reduction in mitotic cells observed. It does not seem however that inhibition affects differentiation in the regrowing eye, with Notch1 inhibited eyes showing the general retinal morphology of uninhibited eyes, as well as mature rod and ganglion cells in their appropriate places.
To determine the interaction of Notch with other known regenerative mechanisms, I overexpressed Notch1 during eye regrowth, while blocking V-ATPase activity. The vacuolar V-ATPase is a transmembrane enzyme that is integral to maintaining cell voltage. Membrane voltage is another regulator of regeneration, and V-ATPase is a regulator of Notch signaling in other systems. I demonstrated that overexpression of Notch1 signaling during regrowth is sufficient to rescue V-ATPase inhibition of regrowth, indicating a link between the two pathways in Xenopus laevis embryonic eye regrowth.
I have helped determine the general physiology of the eye during regrowth, as well as determining the necessity and function of Notch signaling. However, there are many questions still remaining regarding embryonic eye regrowth in Xenopus laevis. It is my hope that future generations of scientists utilize this research as a foundation to discover novel mechanisms governing eye regrowth, as well as regrowth of other organs in other systems
Parsing the Plains: Placing Emporia, Kansas in the Great Plains Midwest
No full textThis thesis examines the formation of a region that can be called the Great Plains Midwest. It shows this formation through the city of Emporia, Kansas, which grew in tandem with the region. The thesis also examines Emporia as a case study of the cycle of birth, growth, and stagnation visible across the Great Plains between the 1850s and 1910s. This era traces Emporia from its humble beginnings to a period of population stagnation that followed the Panic of 1893. Three chapters cover Emporia’s agriculture, railroads, and colleges and universities, comparing each to the same elsewhere in both the midwestern and western portions of the Great Plains. An epilogue reflects on Emporia’s legacy from the late nineteenth and early twentieth century and the rise of the Great Plains Midwest. The thesis argues that history, geography, and human-development rather than political or state boundaries, played the largest roles in creating distinctions between the midwestern and western portions of the Great Plains
A Multiple Case Study on Student-Centered Teaching and Educational Equity for Diverse Learners
No full textStudent-centered teaching (SCT) has been the dominant education philosophy in the U.S. K-12 education. However, the definition and practice of SCT have been rooted in western education contexts. Since students in U.S. schools become more and more diverse, it remains unclear how SCT works for diverse learners. This research delved into the perceptions and implementation of SCT by teachers in elementary charter schools, emphasizing their approach in classrooms with diverse learners. The study also aimed to uncover any disparities in how teachers perceived and applied SCT when educating diverse learners compared to non-diverse learners. Guided by critical reflection for transformative learning and Critical Race Theory, this study employed a multiple-case study research design. It included four participating teachers from two charter elementary schools, placing a special emphasis on the charter school context. These teachers were interviewed to gain insights into their perceptions and were observed to assess their teaching practices. The study’s findings indicated that teachers exhibited a predominantly teacher-centered orientation in their understanding of SCT, with their teaching practices primarily reflecting this teacher-centered approach. Importantly, both their perceptions and practices of SCT appeared to overlook the needs of diverse learners within the charter school setting
Nevada’s Care Workforce: Obstacles and Opportunities for Policymakers
No full textThe care economy includes “the paid and unpaid labor and services that support caregiving in all its forms.” This work includes caring for children, the elderly, and those who are ill or have disabilities. Care work is often undervalued, underpaid, and without a fair system of work benefits in place (e.g. contracts, paid leave, workers’ rights) that in many cases falls disproportionately on women and communities of color. In this policy brief, we examine the care economy in Nevada by focusing on three areas of care: (1) child care; (2) elder care; and (3) mental and behavioral health care. In all three areas, Nevada is well below its expected share of the workforce needed to provide these services to our residents. In addition to evaluating the current landscape of Nevada’s care workforce, we offer policy recommendations and actions that can be taken to improve Nevada’s care economy now and in the future
The Role of Full-Time Job Postings for Postsecondary CTE Faculty in Curriculum Design: A Document Analysis
No full textThis study examines job postings for full-time postsecondary Career Technical Education (CTE) faculty to explore job duties. Document analysis was used on the job postings collected on JobsEQ Real-Time Intelligence for CTE instructors in North Carolina. Over a year, 318 job postings were found through specific search terms in JobsEQ, with 205 retained. Discarded postings were due to duplication, not postsecondary CTE, or part-time positions. Examination of job postings revealed six thematic areas that tie to curricular skills: development process, inputs and standards, content of the CTE curriculum for students, uses of curriculum in the CTE instructor’s role, goals, and management of items related to curriculum. Further analysis was performed using the ADDIE instructional model as a lens. This work helps describe how skills for analyzing needs of students and employers, design of instruction, development of instruction, instruction implementation, and evaluation of students and programs relate to the job of CTE instructors and uncovers areas of potential professional development