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Topology in 1930s America: A Tale of Two Camps
No full textBy the 1930s, two rival camps of topology had evolved in the United States: point-set topology animated by Robert L. Moore at the University of Texas and combinatorial (or algebraic) topology fostered by Oswald Veblen and, especially, Solomon Lefschetz at Princeton. This talk will sketch the contours of the American topological landscape in the decade before the outbreak of World War II and highlight the differences and divisions between the adherents of the two approaches as they jockeyed for influence within the American mathematical research community
Broad-spectrum Activity of Membranolytic Cationic Macrocyclic Peptides Against Multi-drug Resistant Bacteria and Fungi
Get PDFThe emergence of multidrug-resistant (MDR) strains causes severe problems in the treatment of microbial infections owing to limited treatment options. Antimicrobial peptides (AMPs) are drawing considerable attention as promising antibiotic alternative candidates to combat MDR bacterial and fungal infections. Herein, we present a series of small amphiphilic membrane-active cyclic peptides composed, in part, of various nongenetically encoded hydrophilic and hydrophobic amino acids. Notably, lead cyclic peptides 3b and 4b showed broad-spectrum activity against drug-resistant Gram-positive (MIC = 1.5–6.2 µg/mL) and Gram-negative (MIC = 12.5–25 µg/mL) bacteria, and fungi (MIC = 3.1–12.5 µg/mL). Furthermore, lead peptides displayed substantial antibiofilm action comparable to standard antibiotics. Hemolysis (HC50 = 230 µg/mL) and cytotoxicity (\u3e70 % cell viability against four different mammalian cells at 100 µg/mL) assay results demonstrated the selective lethal action of 3b against microbes over mammalian cells. A calcein dye leakage experiment substantiated the membranolytic effect of 3b and 4b, which was further confirmed by scanning electron microscopy. The behavior of 3b and 4b in aqueous solution and interaction with phospholipid bilayers were assessed by employing nuclear magnetic resonance (NMR) spectroscopy in conjunction with molecular dynamics (MD) simulations, providing a solid structural basis for understanding their membranolytic action. Moreover, 3b exhibited stability in human blood plasma (t1/2 = 13 h) and demonstrated no signs of resistance development against antibiotic-resistant S. aureus and E. coli. These findings underscore the potential of these newly designed amphiphilic cyclic peptides as promising anti-infective agents, especially against Gram-positive bacteria
A Multi-Group Public Goods Game Experiment
Get PDFPeople belong to many different groups, and few belong to the same network of groups. Moreover, people routinely reduce their involvement in dysfunctional groups while increasing involvement in those they find more attractive. The net effect can be an increase in overall cooperation and the partial isolation of free-riders, even if free-riders are never punished, excluded, or recognized. We test this conjecture with a multi-good extension of the standard finitely repeated public goods game. Our results from four treatments suggest that the multi-group setting indeed raises overall cooperation and dampens the impact of free-riders
Hair Dye and Relaxer Use among Cisgender Women in Embu and Nakuru Counties, Kenya: Associations with Perceived Risk of Breast Cancer and Other Health Effects
Get PDFDespite widespread use of hair products globally, little is known about the prevalence and patterns of use in populations outside the United States. As some hair products contain endocrine-disrupting chemicals (EDCs) and EDCs have been linked to breast cancer, which is increasing globally, in this study, we addressed key knowledge gaps about hair product use and practices, and perceptions of use among women in two counties in Kenya. Using community-engaged approaches in Embu and Nakuru, Kenya, we recruited women aged 15–50 years to complete a questionnaire that ascertained hair product use in the last 7–14 days, ever using hair dyes and chemical relaxers, and participants’ perceptions or harm around hair product use. In multivariable-adjusted regression models, we evaluated associations between participants’ sociodemographic characteristics and perceptions of hair product use in relation to if they have ever used hair dyes and relaxers. In our sample of 746 women (mean age, 30.4 ± 8.1 years), approximately one-third of participants reported ever using permanent and/or semi-permanent hair dyes, with approximately one-fifth reporting current use. Almost 60% reported ever using chemical relaxers, with a little over one-third reporting current use. Increasing age and having an occupation in the sales and service industry were statistically significant predictors of hair dye use (OR 1.04, 95% CI: 1.02–1.06 and OR 2.05, 95% CI: 1.38–3.03, respectively) and relaxer use (OR 1.03, 95% CI: 1.01–1.06 and OR 1.93, 95% CI: 1.30–2.87). On average, participants reported moderate-to-high levels of concern about exposures and general health effects from using hair products, and relatively high levels of perceived risk of breast cancer related to hair product use. However, in contrast to our hypotheses, we observed mixed evidence regarding whether higher levels of perceived risk were associated with lower odds of ever using hair dyes and relaxers. These findings add new knowledge to the extant literature on hair product use among women in Kenya, where breast cancer incidence rates are increasing. Improving the understanding of patterns of use of specific products and their chemical ingredients—which may be hormone disruptors or carcinogens—and exploring the role of environmental health literacy are critical for developing interventions to reduce potentially harmful exposures found in these products
Visit the Imprisoned: A Heuristic Inquiry into the Experiences of Catholic Detention Ministry Volunteers
Get PDFThere exists a wide breadth of literature in regards to the harmful and dehumanizing impact of incarceration on human development and dignity. Through my years as a volunteer in detention ministry, I have witnessed firsthand these effects particularly on youths who have been incarcerated. My experiences have led me to wonder then, “Why does the prison system still exist to harm people despite the array of research condemning its practices?” Through this pondering, I critiqued the larger systems at play: the prison-industrial complex, the sociopolitical rhetoric of “tough on crime,” and the overall demonization of this population. As a response to this dominant narrative, this study sought to explore the experiences of Catholic detention ministry volunteers. Through a heuristic methodology and with the theoretical underpinnings of Critical Pedagogy, Catholic Social Teaching, Liberation Theology, and Restorative Justice, I gathered data–the reflections, testimonies, and stories–from other volunteers who served as collaborators within this study. I identified four major themes that emerged from the data: (1) God within this context, (2) detention ministry as a classroom, (3) critiques of justice, and (4) solidarity to transformation. The conversations with my collaborators suggested that the experiences of volunteers ultimately shed insight into the lives of those impacted by incarceration as well as put a spotlight on their humanity. This study highlighted the need for rehumanization: transformation within the prison system calls for a shift in perspectives, an altering of attitudes, and a change of heart around the demonization of this vulnerable population
Augmenting Hand and Arm Function for Persons with Hemiparesis
Get PDFBackground. Hand and arm dysfunction due to neural disorders significantly influences quality of life. Activity-based training has been found to improve function. These improvements could be augmented with transcutaneous spinal cord stimulation (tSCS) due to the modulatory effect it has on spinal and supraspinal networks. Objective. The primary aim is to determine if a 4-week training program will improve hand and arm function. The secondary aim is to determine if the addition of tSCS to a second 4-week training session will further improve function. Design. This is a pre-posttest, controlled trial for persons 10-75 years of age, \u3e6 months post stroke or with unilateral cerebral palsy.Methods. Participants will engage in two 4-week training periods, 3x/week for 2 hours/day. The 1st period will include unimanual and bimanual training alone. The 2nd period will be augmented with low frequency tSCS to the C5-T1 spinal region. Stimulation intensity will be based on individual muscle activation during 3 tasks: 1) grip dynamometry; 2) grip-lift; and 3) target pointing. Outcome measures taken before, midway, and after training are: Canadian Occupational Performance Measure (COPM), dexterity, daylong arm use, grip/pinch strength, sensibility, questionnaires, bilateral hand/arm surface electromyography, and Upper Extremity Fugl-Meyer (UEFM). Results: Nine participants have completed the 1st 4-week training period without tSCS. Individual data reveals improvements in the COPM, Grip strength, dexterity, and the UEFM. Findings for other measures after the 1st period are mixed or in process. Conclusion: Preliminary findings from this ongoing study reveal that participants made improvements in most measures. The next phase of the study will determine if the addition of tSCS to training further augments hand and arm function
2nd Place Contest Entry: What\u27s Your Hip-Hop Story? How Authenticity has Simultaneously Fought and Imposed the Commercialization of Rap
Get PDFThis is Heather Ulwick\u27s submission for the 2024 Kevin and Tam Ross Undergraduate Research Prize, which won second place. It contains their essay on using library resources, their bibliography, and a summary of their research project on how authenticity has simultaneously fought and imposed the commercialization of rap music.
Heather is a fourth-year student at Chapman University, majoring in Music. Their faculty mentor is Dr. Jessica Sternfeld
Peacekeeping the Commons: UN Peacekeeping Moderates the Effects of Climate Change on Intercommunal Conflict
Get PDFThe effects of climate change have been increasingly linked to the risk of intercommunal conflict, as climatic shocks have been shown to increase resource scarcity. Policymakers and academics agree that effectively designed institutions are critical variables in preventing and mitigating conflict, particularly in ecologically-fragile areas. However, there is a lack of evidence on the specific ways to strengthen institutions in the face of climate change, especially in conflict-affected settings. We argue that UN Peacekeeping Operations moderate the effects of climate change on intercommunal conflict by strengthening institutions governing common-pool resources (CPRs) to increase cooperation between communities sharing scarce resources. We test our argument by investigating whether local deployments of UN peacekeepers prevent violence between agriculturalist and pastoralist communities during climatic shocks. Our statistical analysis leverages high-resolution data on the timing and location of local deployments of UN peacekeepers, rainfall shocks, and conflict events in Mali between 2014 and 2018–where drought increasingly degrades shared grazing lands and the institutions used to promote their cooperative management. We find that the local deployment of UN peacekeepers mitigates the increased probability of conflict in agriculturalist communities that the onset of drought in neighboring pastoralist communities otherwise generates. Our results provide scholars and policymakers with quantitative insight into effective interventions that help communities experiencing climate-related resource scarcity bolster their CPR institutions and promote cooperation, decreasing intercommunal violence. As climate change continues to progress, understanding the actions that advance intercommunal cooperation in the face of resource scarcity is vital to prevent heightened risk of conflict