Reed Digital Collections (Reed College)
Not a member yet
8045 research outputs found
Sort by
A Study of Borel Probability Measures on ℝ That Aren’t Absolutely Continuous With Respect to Lebesgue Measu
No full texthttps://rdc.reed.edu/v1/resources/03cd4d74-c9f4-4e8c-b355-371e2cb837a8/thumb/128.jpgThis thesis is about the probability measures (probability distributions) on ℝ that are not absolutely continuous with respect to Lebesgue measure, as well as the mathematics behind which probabilities do and do not meet this condition. Typically, probability courses focus on so-called continuous and discrete probability distributions. However, we will see that there are three types of probabilities on ℝ, discrete, singular, and absolutely continuous. In an undergraduate probability course, singular distributions are left out, and so-called continuous distributions is actually absolutely continuous. In this paper, we will justify many properties that each of these three types of probabilities have, and provide many examples with a focus on the probability measures that are often neglected
Quantification of Douglas-fir Traumatic Resin Ducts as a Dendroecological and Forest Health Tool in the Klamath Mountains, OR, USA
No full texthttps://rdc.reed.edu/v1/resources/fde04dd9-eb46-45d2-ac1a-72d960caf087/thumb/128.jpgThe forests of Southwest Oregon are experiencing recent, widespread patterns of decline and dieback of coastal Douglas-fir, Pseudotsuga menziesii var. menziesii (PSME). The coastal Douglas-fir is the dominant tree species of the characteristically dry, low to mid elevation, Klamath ecoregion. Recent PSME dieback is attributable to increases in stand density due to a history of active fire suppression allowing PSME to expand beyond historic niches and encroach into ecosystems that have been historically inhospitable to this species. Within these areas, climate change driven decline and mortality such as drought and increased bark beetle activity, have been cited as possible decline mechanisms. Detailed, mechanistic studies of the decline have yet to be understood, thus limiting our understanding of the predisposing, inciting, and contributing factors of tree mortality. Traumatic resin ducts (TRDs) are induced by beetle attack and are a defense trait that kills and flushes the beetle out of the tree. However, resin ducts are not well understood, and even less is known about resin duct formation in PSME. Understanding resin duct formation as an ecophysiological defense trait could help inform how PSME mortality is occurring in the Klamath ecoregion. Despite growing interest in the ecophysiological role of resin ducts, important gaps remain. Moreover, while observational studies have made strides in correlating resin duct traits with survival outcomes, few have quantitatively assessed specific characteristics of PSME TRDs. Here, I investigate the potential of resin duct metrics as proxies for tree resilience, particularly in the context of observed PSME dieback in southern Oregon. My findings suggest continued research into the formation of TRDs in PSME may help unpack the complex drivers of tree decline in the Klamath region
Insight or Inference? A Modern Look at Transitive Inference in Rats
No full texthttps://rdc.reed.edu/v1/resources/8f5a02d4-ac77-40fe-a3f4-f1ce5a5d8a44/thumb/128.jpgWhen a person is asked about the ranking order of multiple objects without being allowed to see the full list, such as by being asked to select which of two items they think is higher in the list, they can eventually deduce the ranking order of the full list using a cognitive tool called transitive inference (TI). Davis (1992, 1996) reported that Long-Evans rats (Rattus norvegicus) are also capable of TI. However, an experiment using a comparable paradigm has not been replicated for the past thirty years. This thesis replicates and extends Davis’ work and modernizes it. A more sophisticated apparatus, in addition to more consistent record-keeping, ensures that my results can generalize to all Long-Evans rats. Keeping previous research in mind, I predicted that the rats I studied would be capable of TI. I injected the rats with saline and with Exendin-4 (Ex-4) over the course of five weeks and found that the rats were capable of TI when they were injected with saline and tentatively capable of TI when they were injected with Ex-4. This research confirms Davis’ results: rats are capable of TI. It also modernizes the methods of taking and analyzing the data
How are Tumor Associated Macrophages Promoting the Exclusion of Cytotoxic T-cells in the Cancer Stem Cell Niche of Squamous Cell Carcinoma? An Experimental and Theoretical Study of Onco-Immunology
No full texthttps://rdc.reed.edu/v1/resources/282c1695-caaf-4c18-b71d-ccdb1cc18e75/thumb/128.jpgThe second most common type of skin cancer, Squamous Cell Carcinoma (SCC), has over 1 million cases diagnosed annually in the United States alone. While the prognosis of SCC is typically favorable, recurruring tumors do so quickly, typically within 2 years of cancer treatment (Khan et al., 2018). This notably fast recurrance rate has been associated with a small subtype of cancer cells — Cancer Stem Cells (CSCs) (Oshimori 2015). CSCs are characterized by quiescence (dormancy), drug resistance, immune evasion, and location with a specialized tumor sub-microenvironment. Located at the tumor-stroma interface, this CSC niche is established later in tumor progression by a paracrine signaling loop between CSCs and FcεRIα+ macrophages, resulting in its characteristic high TGF-β levels and exclusion of CD8+ T cells (Taniguchi 2020). At Oregon Health and Science University’s Oshimori Lab, research preliminary to this project identified an inverse relationship between CD8+ T-cells and IL-33-responding macrophages throughout tumor progression. CD8+ T cell count increases throughout tumor progression, until niche macrophages become present, at which point the CD8+ T cell population drops. CD8+ T cell infiltration of tumors is associated with better prognosis, as a primary immune function of CD8+ T cells is the identification and killing of cancer cells (Jochems 2011). The exclusion of CD8+ T cells allows for immune evasion, leading to advanced tumor invasion and metastasis. For this thesis, the relationship between CD8+ T cells and FcεRIα+ macrophages was replicated by invitro cell culturing and explored through flow cytometric analysis. Preliminary work identified a significant reduction of CD44 expression — a T cell activation marker — expression in CD8+ T cells after incubation with FcεRIα+ macrophages, which was further confirmed by this Thesis. However, while reduced CD44 expression implies a reduction in activation, it could also be the result of Proteolysis of CD44 —proteases snip CD44 proteins off the cell surface to initiate cell signalling (De Falco 2012). Also within this thesis project, a new flow panel with additional T cell markers was successfully developed with the intention to confirm whether CD8+ T cells are experiencing inactivation by IL-33 macrophages. Unfortunately, no additional T cell markers had data that implied CD8+ T cells of IL-33 Co-cultures have significantly different expression levels from other sample types. However, that data is from one round of flow cytometry, and repeated experimentation must be performed before making any conclusions
Bacteria in the Mix: Exploring Microbial Recycling of Post-Consumer Plastic Waste
No full texthttps://rdc.reed.edu/v1/resources/26f35a83-9eed-46d7-b7e1-6c17bd570c70/thumb/128.jpgPlastic waste is a pervasive and complex global challenge. Recycling and waste management facilities are ill-equipped to handle the mixed plastics that result from single-stream post-consumer waste collection. This thesis explores the potential for biological recycling as an alternate option to mechanical recycling for processing mixed waste streams. The research involves a microbial consortium consisting of two Bacillus and three Pseudomonas strains. Liquid chromatography mass spectrometry, performance liquid chromatography, and gas chromatography mass spectrometry were all used to evaluate the consortium’s ability to degrade polyethylene terephthalate (PET) in the presence of other plastic types, specifically high-density polyethylene (HDPE), lowdensity polyethylene (LDPE), polypropylene (PP), and polystyrene (PS). The quantification of PET metabolites bis(2-hydroxyethyl) terephthalate (BHET), mono(2-hydroxyethyl) terephthalic acid (MHET), and terephthalic acid (TPA) suggested that PET degradation can continue unhindered in mixed plastic environments. The other plastic types saw no additional degradation when the bacteria were added illustrating selective degradation of PET. These results contribute to the evolving literature on bacterial recycling and provide a foundation for exploring the feasibility of using microbes to address the current struggles with mixed plastic waste
The Book of (Neuro)genesis: Exploring Interactions Among BMP, MAPK, and RA Signaling Pathways During Eye Development
No full texthttps://rdc.reed.edu/v1/resources/b16b654c-bcd0-4c30-b7b8-346639f686f2/thumb/128.jpgRegulation of neurogenesis is key for all growing tissues of the nervous system. Eye development exhibits stereotypical timing of proliferation and differentiation across vertebrate animals like humans and zebrafish. Within vertebrates, eye development starts after the neural folds come together to create a regionalized neural tube. In the forebrain, the optic vesicles emerge. After extensive morphogenesis, coordinated with cell proliferation and differentiation, the retina forms. In the dorsal retina, one of the last places where neuron development occurs in the eye, multiple signaling pathways are thought to control neurogenesis. The BMP (Bone Morphogenic Protein), MAPK (Mitogen Activated Protein Kinase), and RA (Retinoic Acid) pathway are active in the dorsal retina. When these pathways are disrupted, it can lead to dysregulation of dorsal retina growth. Compared to wildtype embryos, gdf6a -/- mutant (bmp13 knockout) embryos have phenotypic differences such as ventrally displaced retinas and smaller eyes. In this study, I analyzed the BMP, MAPK, and RA signaling pathway to see how RA pathway activity varied in the dorsal retina using the 12xRARE:mEOS transgenic reporter in gdf6a mutants and wildtype zebrafish embryos. Specifically, I used laser scanning confocal microscopy to take time-lapse movies of mutant and wildtype embryos to observe RA expression over the course of 48 hours. Additionally, I conducted pharmacological manipulations and immunostaining providing evidence that both BMP and MAPK are required for RA expression. The results suggest that without BMP, MAPK is downregulated, which in turn leads to undetectable RA pathway activity. When MAPK is inhibited, there is a significant reduction in RA expression compared to wildtype embryos. These data, combined with additional information about cell cycle progression in the dorsal retina, leads us to believe that sequential, interconnected activation of BMP, MAPK, and RA pathway may regulate retinal neuron progenitor cell cycle differentiation
한지 [Hanji]
No full texthttps://rdc.reed.edu/v1/resources/9126567e-092d-415d-b1ff-14974c970387/thumb/128.jp
Is Seeing, Perceiving? A Look at Visual Awareness Using Dichoptic Color Fusion
No full texthttps://rdc.reed.edu/v1/resources/ba29769a-5014-4171-a177-fc88ba083490/thumb/128.jpgUnderstanding the neural correlates of visual awareness remains a central challenge in cognitive neuroscience. This thesis developed a novel “No-Event” Dichoptic Color Fusion (DCF) paradigm to isolate visual awareness while minimizing other confounding perceptual changes. In the No Event condition, the stimulus is the only visual element that changes during stimulus onset, in contrast to traditional DCF studies where both the stimulus and the background change with stimulus onset. Participants (n = 6) completed a visual discrimination task using gabors presented at individually calibrated contrast levels (invisible, threshold, and visible), while event-related potentials were recorded using EEG. Behavioral results showed above-chance discrimination across all contrast levels, with higher accuracy and subjective awareness in the No Event condition. ERP analyses focused on the Visual Awareness Negativity (VAN) and P3 components. The VAN increased in amplitude with contrast and was more pronounced in the No Event condition, while the P3 was present in both conditions and scaled with contrast, but did not differ much by condition. These results support a layered model of visual awareness, with early sensory processing reflected in the VAN and later evaluative processes in the P3. The findings align most closely with Recurrent Processing Theory, while offering partial support for Global Workspace Theory. This work highlights the utility of the new No-Event DCF design in isolating the neural mechanisms associated with visual awareness
Language-Independent Concept Spaces Found in Large Language Models
No full texthttps://rdc.reed.edu/v1/resources/39d4359b-28ce-4e9c-a6e4-4ba5db64c767/thumb/128.jpgN/
To Reap What Was Sown
No full texthttps://rdc.reed.edu/v1/resources/7ad6350e-2787-4415-9432-b618bb4a14bd/thumb/128.jp