79717 research outputs found
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Non-Linear Terahertz Pump-Probe Study on the Photoconductivity of Multilayer MoS2
No full textThis thesis investigates the ultrafast photoconductive response of multilayer molybdenum disulfide (MoS2) under high intensity terahertz (THz) excitation. Intense, single cycle THz pulses are generated using optical rectification in a Mg:Li:NbO3 crystal pumped by a fem tosecond Ti:sapphire laser. We then conducted THz pump-probe experiments using optical pump wavelengths of 400nm and 800nm to study carrier dynamics. Time-resolved mea surements reveal that carrier recombination mechanisms may depend on the optical-pump f luence and THz field strength. Optical excitation induces non-linear THz absorption in MoS2, increasing at higher THz field strength. Conductivity and normalized transmittance show that absorption of THz at lower THz frequencies is more pronounce
Blindsight, Visual Indexing, and Bergsonian Perception
No full textThis thesis defends Henri Bergson’s philosophy of memory and encourages the ongoing return to Bergson. I contend that Bergson’s writings have been insufficiently considered in contemporary philosophy of mind and that current work in cognitive science supports significant portions of his Matter and Memory, first published over a century ago. I defend two specific claims which Bergson makes as being empirically plausible and valuable to theoretical efforts. First, I examine Bergson’s argument that, while lesions to the brain might impede their bodily instantiation, memories themselves are not necessarily destroyed by neurological damage. I then consider current blindsight literature, arguing that the interpretation of blindsight as a form of qualitatively degraded consciousness is wholly compatible with Bergson and corroborates this key section of Matter and Memory. Secondly, I examine Bergson’s argument that perception, action, and memory are necessarily unified in their relation to objects of the world in relation to Zenon Pylyshyn’s theory of visual indexing. After considering criticisms of Pylyshyn, I defend a modified theory which aligns with Bergson’s proposal. I conclude that Bergson’s work in Matter and Memory should be considered relevant to ongoing work in the philosophy of mind, particularly in areas of perception and memory.Keywords: Philosophy, blindsight, Henri Bergson, memory, visual indexing, cognitive scienc
Computer science is like a man : the analogical domain as an inclusive pedagogical tool in computer science education
No full textDiversity within computer science education is a persistent problem. Statistics consistently demonstrate the prevalence of a lack of female representation. To address the cascading effects of this issue, inclusivity within educational examples must be considered. Research regarding pedagogical tools highlights the value of using analogy and examples in the classroom environment. Increasing the inclusivity of analogy further impacts the waterfall effect of this problem. Changing the analogical domain of analogy to better reflect the backgrounds of students helps to engage a more diverse population of students and strengthen their ability to connect to course content. This thesis suggests the implementation of the Outlining Programming Analogy Layout (OPAL) framework in facilitating the adaptation of analogical domains to be more inclusive. By using OPAL, it is possible to account for diverse student backgrounds, prior experiences, and knowledge to make the classroom more inclusive to women. Inclusive analogical domain is proposed as the method of building connection between students and dismantling social limitations within the technology industry.Keywords: analogy, pedagogy, computer science education, inclusivity, OPAL framewor
The microclimate of downed wood in mixed conifer forests of western Oregon
No full textDowned wood plays many key roles in forest ecosystems. It provides habitat for diverse organisms and modifies temperature and moisture conditions on the forest floor. As part of a larger project analyzing the relationship between salamanders and downed wood as a post-fire refugia, this study measured downed wood-related microclimate variability at 30 sites along a latitudinal across Oregon. Each site was set up with three pairs of sensors. One sensor in each pair was placed in downed wood and the other in adjacent interspace zones to log temperature and humidity every four hours for a nine-month period. A mixed effects model was used to determine whether minimum, average, or maximum temperature and humidity differed by sensor location, by latitudinal zone ([north, central, south] or the location*zone interaction), or by week of the year or elevation. Weekly average interspace temperature of 12.3oC was observed, slightly higher than the average in-wood temperatures of 11.6oC. Interspace locations experienced weekly maximum temperatures 6.5oC higher and minimum weekly temperatures 3.1oC lower than in-wood sensors across the study. The weekly average interspace relative humidity of 86.2% was much lower than the average in-wood relative humidity of 98.7%, with interspace sensors ranging from 61-98% humidity weekly while the in-wood relative humidity only ranged from 97-99%. Week of the year was one of the key drivers in both relative humidity and temperature, while elevation was only a driver of temperature. The temperature and humidity buffering by downed wood were most prominent in the hotter, drier southern latitudinal zone of the study. The significant temperature and humidity buffering occurring in downed wood of the Western Cascades acts as crucial refugia for climate sensitive species, which should be considered by land managers as they decide what quantities of downed wood should be preserved in our forests.Keywords: Downed Woody Debris, Habitat Ecology, Microclimate Refugia, Post-Fire Refugi
A reverse genetics approach to identify genes affecting H3K27 methylation levels in Fusarium graminearum
No full textHistone H3 lysine 27 trimethylation (H3K27me3) is a conserved chromatin modification involved in reversible gene silencing through the formation of facultative heterochromatin. H3K27me3 is established by Polycomb Repressive Complex 2 (PRC2), a protein complex comprised of the lysine methyltransferase, Kmt6, an allosteric activator, Eed, and a putative targeting protein, Suz12. Although facultative heterochromatin is essential for proper development in many eukaryotes, the mechanisms by which H3K27me3 is distributed and maintained are not well understood. In this study, we sought to identify additional genes involved in the regulation of facultative heterochromatin in the filamentous fungus Fusarium graminearum. Targeted deletion or point mutation of candidate genes revealed a variety of phenotypes, including defects in morphology, asexual reproduction, and secondary metabolism comparable to kmt6 deletion strains. ChIP-seq data determined that proteins encoded by some of these genes impact local, not global, distribution of H3K27me3 and H3K4me2, a histone modification correlated with active transcription. Future work will use RNA isolated from these strains to assess global changes in transcription. This RNA sequencing (RNA-seq) and follow-up studies on phenotypes mentioned above will aid in the understanding of each of these genes in the regulation of transcription by chromatin proteins.Keywords: Epigenetics, Chromatin modification, PRC2, H3K27me3, Gene silencin
Beyond the means : a review of the shortcomings of traditional design processes and a case study on applying inclusive methodologies to an engineering capstone
No full textTraditional engineering and product design processes often fail to address the unique needs of disabled users. Typical methodologies prioritize functional goals and designing for the “average user,” overlooking the emotional and experiential desires of users with disabilities. This thesis dissects and critiques the limitations of traditional processes and explores the benefits of co-creation in design. How designing with, not for, those with disabilities can lead to more inclusive and empowered individuals. In the thesis, a key case study on an adaptive skateboarding system that was developed by an engineering capstone team at OSU-Cascades highlights further the shortcomings of traditional design processes and successful inclusive design methodologies. Robert, a young boy with Cerebral Palsy and a dream to skateboard, was the center of the project. Him and his support team helped guide the team to achieve both functional and emotional goals within the project. Ultimately, this thesis aims to encourage a shift in industry, from designing for disabled users as an afterthought to designing with them in every applicable area.Keywords: Inclusive design, Human-centered Engineering, Adaptive technology, Mechanical Engineering for Accessibilit
Where the flowers grow : a graphic exploration of climate change
No full text"Where the Flowers Grow" provides commentary on climate change through a post-post-apocalyptic lens in the format of a graphic novel. It explores a world in which climate change was allowed to continue, resulting in the death of most of humanity and the near-total destruction of human records. In this world, flowers have become infectious and spread through inhaled or otherwise consumed pollen. Each infection is unique, but all are deadly. The story takes place a hundred years after the apocalypse and follows three characters: Toss, an exhausted mechanic infected by the most dangerous flower in North America; Eve, a medic determined to save everyone and everything she can; and her wife, Roh, a scavenger with overprotective tendencies. This thesis includes the prologue and first act of the graphic novel, highlighting the world and characters. Later chapters will see them join forces to cure Toss’s infection and find the source of the apocalypse. This thesis is composed of two main parts: the graphic novel itself and a sample of an in-world field journal containing illustrations of various flowers with relevant information about their disease behaviors.Keywords: graphic novel, climate change, flower
Who gives a hoot about owls? An examination of public responses to a lethal wildlife management plan
No full textThe Endangered Species Act (ESA) requires federal agencies take actions to preserve listed species such as the Northern spotted owl (Strix occidentalis). Acting on these requirements, the U.S. Fish and Wildlife Service (USFWS) has proposed a plan to cull non-native barred owls (Strix varia) that threaten remaining spotted owl populations. Most public comments on a draft Environmental Impact Statement (EIS) released by USFWS opposed the culling plan. This paper uses framing analysis to examine the reasoning behind support and dissent for the management plan. Those opposed to the plan expressed moral and practical concerns and a desire to focus conservation efforts on habitat restoration. Those who supported the management plan were driven by a desire to protect native ecosystems. These results suggest that wildlife managers should highlight the ecosystems and species that lethal management plans will benefit and address the controversial aspects of lethal wildlife management.Keywords: Wildlife Management, Public Comments, Northern Spotted Owl, Barred Owl, Endangered Species Ac
Community perspectives on sexual and reproductive health education for caregivers in rural Botswana
No full textAdolescents in Botswana are particularly vulnerable to sexually transmitted infections, sexual assault, and other negative sexual and reproductive health (SRH) outcomes. One of the most powerful tools against these risks is health education and promotion. While adolescent SRH education is becoming more widespread across Botswana, caregivers, including parents, have limited SRH education or involvement in SRH discussions with their children and adolescents. There is considerable evidence to suggest that SRH discussions between caregivers and adolescents are protective against adolescent SRH risks. This research, as part of the Botswana Global Health Initiative’s ongoing work in Botswana, sought to discover the benefits of and challenges with providing caregiver SRH education in rural Botswana. The study used community based participatory research to understand community members’ SRH knowledge, beliefs, and norms. Participants of this study revealed that limited SRH education and culturally reinforced stigma regarding sexuality make SRH discussions challenging in this community. However, there seems to be a growing interest among caregivers in rural Botswana to be actively involved in SRH education and engage in informed conversations with their children and youth. The findings of this study will be used to refine a community-based SRH education curriculum for caregivers in rural Botswana.Keywords: Botswana, sexual and reproductive health (SRH), community-based participatory research, global healt
Examining the effects of outsourcing on tax avoidance
No full textCurrent literature extensively documents the determinants of tax avoidance and the outcomes of outsourcing, but relatively less is known about how outsourcing and tax avoidance interact. This paper aims to bridge this gap by examining if the presence of outsourcing is associated with reduced cash effective tax rates (Cash ETRs) or GAAP ETRs. Using hand-collected outsourcing data, I ran regressions for Cash and GAAP ETRs, controlling for three indicators of outsourcing—contract research organization usage, contract manufacturing organization usage, and extensive outsourcing (engaging both). I further conducted cross-sectional analyses on profitability and size to examine how sample characteristics influence the observed effect of outsourcing. Ultimately, there is insufficient evidence to claim that outsourcing positively influences tax avoidance. While my initial analysis shows outsourcing as a significant, negative predictor of ETRs, the cross-sectional analyses on profitability and profitability-size are statistically insignificant. Further analysis on the effects of outsourcing on future ROAs show that outsourcing reduces ROAs at the 1-, 3-, 5-, and 10-year mark. These results highlight limitations in this study’s sample size and present the opportunity for future research by increasing the size and robustness of the sample or introducing alternative channels for outsourcing to influence tax planning.Keywords: corporate taxation, outsourcin