Environmental and Occupational Health Sciences Institute
Rutgers University Community RepositoryNot a member yet
58345 research outputs found
Sort by
The external field-programmable analog array: routing external circuit elements with an FPAA to implement arbitrary analog functions
No full textFPGAs, or Field Programmable Gate Arrays, have seen a recent explosion in usage. FPGAs rely on electrically routing digital logic resources to implement any logical function, thus solving any computable problem. The analog relative of the FPGA is the FPAA, or Field Programmable Analog Array. The FPAA has on-board blocks, known as CABs or Configurable Analog Blocks, which it connects and routes to implement its various analog circuits. The FPAA sees usage in many applications, however it is unable to implement any generic analog function; if the correct CAB is missing, there is no way to add it. The way to make the FPAA implement any Analog function is to allow the application to accept external ICs, and then use analog routing to make all connections between elements. This can be then integrated into FPGAs or standard FPAAs to cover any gaps in performance. The scope of this project is to design and physically implement an External FPAA, then analyze the results. As a target application, the Full Bridge Rectifier will be implemented. Due to complexity issues, the board will be optimized for performance in this application.M.S.Includes bibliographical reference
Researcher Pantozzi Prompts Students in Open-Ended Exploration of the Fundamental Theorem of Calculus
No full textThis analytic examines researcher Ralph Pantozzi’s questioning style when posing open-ended tasks to students. This analysis focuses on three female students: Romina, Magda, and Angela, who were former AP Calculus students of Researcher Pantozzi’s and at the time of the observed sessions were juniors in college, over the course of two sessions. The first session took place on June 25, 2003 and the second session occurred on July 24, 2003. Both sessions showcased evolving thoughts and explanations of the Fundamental Theorem of Calculus (FTC). Researcher Pantozzi poses the task, “Why does the Fundamental Theorem of Calculus work?” in the first session. After analyzing the participants’ contributions, he poses a “more directive” task in the second session: “Why is the function g the antiderivative of the function f in the symbolic statement of the Fundamental Theorem of Calculus?” (Pantozzi, 2009, p. 232). The students were encouraged to use any of a wide variety of resources that Researcher Pantozzi made available, including, but not limited to: calculus textbooks, calculators, paper, and the tests they had taken in Researcher Pantozzi’s AP Calculus class several years prior.
Throughout the events, Researcher Pantozzi joins the group to probe the students’ thinking. He uses questioning to elicit summary statements, such as asking for a short phrase for a “bumper sticker” description of the FTC. He challenges their viewpoints by providing counterexamples to elicit higher-order thinking. He encourages the group to explain the FTC to him while he role-plays a hypothetical student. He uses technology, such as Geometer’s Sketchpad, to provide visual representations of the students’ notions, which prompts discussion. His apparent goal is to strengthen the participants’ arguments by quantifying their language and elaborating on questionable terms that they used to refer to concepts.
Event 1- Romina, Magda, and Angela are deciding how to phrase their short “bumper sticker description” of the FTC, in response to Researcher Pantozzi’s task and their progress during the closing minutes of the first session. The students generally agreed on the description, after Romina gave a slight critique to Magda’s choice of language.
Event 2- During the second session, the students are pondering the meaning of the antiderivative. Magda and Researcher Pantozzi engage in dialogue about the open-endedness of the task, leading Magda to discuss with her peers about why she thinks the Power Rule for integration involves increasing the power by one. Researcher Pantozzi interjects to provide counterexamples at this point, which serve as cognitive obstacles for the students as they consider other cases.
Event 3- Researcher Pantozzi prompts discussion as the group expands upon that idea to visually explain why the power is increased by one. This is the first instance where a student, Romina, references the Accumulator Function: “You’re taking the area, so it goes to the next power because it’s like the cumulative function… that’s why it has to be bigger.”
Event 4- Researcher Pantozzi uses Geometer’s Sketchpad to provide an estimate for the definite integral. As the animation is drawn on screen, Angela points out the case of negative area while Romina notes that the “integral increases and then decreases.”
Event 5- Romina asks the group for clarification on language used by Researcher Pantozzi referring to antiderivatives. This leads to a discussion as to whether there is a difference between antiderivatives and integrals.
Event 6- Researcher Pantozzi restates assumptions that can be made about the task, allowing Magda to expand upon her explanation of the “+C” in the antiderivative. Romina and Angela agree with this notion and discuss a hypothetical case where C equals -2.
Event 7- Once the definition of antiderivative is clarified and accepted among the students, Researcher Pantozzi engages in a discussion with Romina about its meaning, in which she states that it is “the opposite of taking the derivative.” This prompts an investigation to uncover why these two seemingly unrelated operations are inverses of one another.
Event 8- The students make the connection between derivatives and antiderivatives clearer by linking them in a discussion about slope and area. They discuss rates at which areas are accumulated on another Geometer’s Sketchpad illustration that Researcher Pantozzi shows them.
Event 9- Researcher Pantozzi listens to Romina’s summarized statements about their progress, questioning her language when it is unclear. He elicits conversation from Magda and Angela who add their thoughts about the underlying construction process that dictates the relationship between derivatives and antiderivatives.
Conclusion
The design of open-ended questions and eliciting students’ contributions can be seen in previous tasks and analytics. In Event 7 of Silber’s (2013) analytic, Robert B. Davis leads a discussion about “ethics and morality.” He elicits a conversation about building a mathematical community and doesn’t reveal his ideas about the problem despite repeated requests from the students. As he explained, “I’m waiting to see if anyone else knows [the secret], maybe I do, maybe I don’t!” When Romina, Angela, and Magda probe Researcher Pantozzi for further clarification on his questions, he directs them to the task at hand and facilitates the discussion in an open-ended manner. This analytic describes Researcher Pantozzi’s responses to the group’s behaviors as he supports a curious and motivated group of students who want to collaborate. Researcher Pantozzi removes himself from the dialogue early on, in order to discourage the notion that he is the holder of the content knowledge. Researcher Pantozzi wants his students to “gain ownership of a mathematical idea [which] involves a process by which the learner takes responsibility for knowing” (Maher et al., 2011, p. 57). Researcher Pantozzi elicits discussion from the three students in order to get them to state terms and concepts in their own voices, making the FTC more meaningful for all of them.
When working in the collaborative mathematical space that Researcher Pantozzi nurtured, there were times when language usage was unclear to certain members of the group. As a natural consequence of group discussion and the journey of mathematical learners, occasionally Researcher Pantozzi and/or one of the students needed to step in to clarify another’s language. Just as Romina worked with Brian, Jeff, Ankur, and the other students on Ankur’s Challenge: “As Romina tried to communicate her ideas so that Jeff would follow, she revised her representations” (Maher & Muter, 2011, p. 94).
The way Researcher Pantozzi facilitated the second session enabled him to prompt the students’ discovery regarding nuances of the FTC. As he noted in his dissertation (Pantozzi, 2009, p. 232), he altered the task design in the second session to be “more directive,” in order to elicit contributions about the FTC that were not discussed in the first session due to its broader design. As discussed in a personal interview with my cooperating teacher, Dr. Jennifer Corboy, who has been teaching calculus for more than twenty years, “Students can really lose important details of the concept if they are not fully exploring that. So for instance, with the FTC, sometimes you get positive and negative areas, things that can cancel out, or if you accumulate backwards it changes the sign, and things like that” (Corboy, 2024). Researcher Pantozzi directed the group towards carefully crafted Geometer’s Sketchpad illustrations to spark a conversation about positive and negative areas, for example, in Event 4. It was important that this discussion was elicited before moving on to other nuances of the FTC in following events.
It appears that the sense of “mathematical ownership” and opportunities for dialogue with others helped Romina gain a deeper, conceptual understanding of the FTC. When she was interviewed six years later, after earning her MBA, as part of the longitudinal study, Romina confidently stated, “But I probably could explain to them The Fundamental Theorem of Calculus and kind of explain to them how all these things happened and worked and visually how everything was represented” (Steffero, 2009). This instance of problem solving, prompted by Researcher Pantozzi’s open-ended tasks, gave Romina “ownership” over the underlying ideas of the FTC. Her experiences working with Magda and Angela made her feel confident in expressing this idea to others.
Overall, Researcher Pantozzi’s design of his tasks led to “durability of understanding” among the students (Uptegrove, 2011, p. 140). After Romina and some other students from the study, such as Mike and Ankur, worked on the Pascal’s Identity exploration in terms of the Pizza Problems, it was determined that “all… were able when prompted to write the formula, and all… were able to provide a cogent explanation of the addition rule” (Uptegrove, 2011, p. 140). As Romina explained in her 2009 interview, one of the only theorems she recalled by name was the FTC. The task design of the FTC group sessions that Researcher Pantozzi facilitated solidified her knowledge of the subject. Reflecting on her experiences in Researcher Pantozzi’s AP Calculus class, along with the two sessions conducted nearly three years later, served to strengthen her conceptual understanding of the topic.
Definitions and Terms
The Fundamental Theorem of Calculus (FTC)
If a function f is continuous on the closed interval [a, b] and F is an antiderivative of f on the interval [a, b], then the integral of f(x) from interval a to b is F(b) – F(a). “Informally, the theorem states that differentiation and (definite) integration are inverse operations, in the same sense that division and multiplication are inverse operations… The Fundamental Theorem of Calculus states that the limit processes (used to define the derivative and definite integral) preserve this inverse relationship” (Larson et al., 1998, p. 274).
Problem Tasks
Task in Session 1 (and Event 1): “Why does the Fundamental Theorem of Calculus work?”
Task in Session 2 (and Events 2 – 9): “Why is the function g the antiderivative of the function f in the symbolic statement of the Fundamental Theorem of Calculus?”
Video Clip References
B45, The fundamental theorem of calculus, Session 1 of 2: Discussing the meaning of the theorem (student view), College, June 25, 2003, raw footage [video]. Retrieved from https://doi.org/doi:10.7282/T3HQ3X26
B47, The fundamental theorem of calculus, Session 2 of 2: Discussing why the antiderivative can be used to calculate the area under a graph (student view), College, July 24, 2003, raw footage [video]. Retrieved from https://doi.org/doi:10.7282/T3HM56MD
References
Corboy, J. (2024, March 16). Personal Communication [Zoom Interview].
Larson, R., Hostetler, R., & Edwards, B. (1998). Calculus of a Single Variable (6th ed.). Boston, MA: Houghton Mifflin.
Maher, C. A. & Muter, E. M. (2011). Responding to Ankur’s Challenge: Co-Construction of Argument Leading to Proof. In Maher, C. A., Powell, A. B., & Uptegrove, E. B. (Eds.). Combinatorics and Reasoning: Representing, Justifying, and Building Isomorphisms (Vol. 47). (pp.89-96). Springer, Dordrecht.
Maher, C. A., Sran, M. K., & Yankelewitz, D. (2011). Building an Inductive Argument. In Maher, C. A., Powell, A. B., & Uptegrove, E. B. (Eds.). Combinatorics and Reasoning: Representing, Justifying, and Building Isomorphisms (Vol. 47). (pp.45-58). Springer, Dordrecht.
Pantozzi, R. (2009). Making Sense of the Fundamental Theorem of Calculus (Doctoral dissertation, Graduate School – New Brunswick, Rutgers, The State University of New Jersey). Available from ProQuest Dissertations. UMI Number: 3373679
Silber, C. (2013, August 21). An Experiential Investigation of Algebraic Ideas Created and Implemented by Robert B. Davis. Retrieved from https://doi.org/doi:10.7282/T3NV9G6H
Steffero, M. (2009, July 15). Romina Interview Reflections (M.B.A. Graduate): Understanding the Ideas [Video]. Retrieved from https://doi.org/doi:10.7282/T3TX3CSV
Uptegrove, E. B. (2011). Representations and Standard Notation. In Maher, C. A., Powell, A. B., & Uptegrove, E. B. (Eds.). Combinatorics and Reasoning: Representing, Justifying, and Building Isomorphisms (Vol. 47). (pp.133-144). Springer, Dordrecht
Communities of care: civic response, mutual aid, and the COVID-19 pandemic
No full textThe COVID-19 pandemic’s overlapping timeline with extreme climate events and socio-political crises signaled an inescapable era of compounding disasters that characterized a new global feeling of precarity. While the United States government stepped up in some equally unprecedented ways, these efforts did little to quell the impact for the most marginalized. Local civic groups and networks scrambled to address these concerns and provide direct and ongoing support in ways the government did not.
This dissertation looks at the civic responses to COVID-19 in New York City, with an emphasis on understanding how existing environmental stewardship groups and emergent mutual aid groups organized to respond to the social vulnerabilities highlighted by the pandemic. It takes a temporal approach in examining the changes in group efforts over the nearly four years since the beginning of the pandemic. Additionally, this work uses a multi-scalar perspective, collecting data on the regional and citywide scale as well as the neighborhood scale to capture hyperlocal dynamics that are absent in many studies. This body of work answers the overarching question: How are civic groups and networks created through, mobilized by, and challenged during crises? In particular, this dissertation looks at the various connections between civic groups and the state, the range of impacts civic and emergent groups have on their communities from incremental to transformational, and the characteristics that support adaptive capacity and sustainability in civic groups, networks, and movement building.
Data for this analysis were collected through a research survey of emergent COVID-19 response groups, multiple phases of in-depth, semi-structured, interviews with members of stewardship groups, mutual aid groups, and community based organizations, and in-person fieldwork with a local mutual aid network. This dissertation comprises four individual papers that together uncover a broad picture of the civic organizing landscape in New York City following the COVID-19 pandemic. The first paper reviews the ways mutual aid responses have shown up in New York City following both Superstorm Sandy and COVID-19, and inquires about the implications of this practice. The second paper studies existing environmental stewardship groups in the context of COVID-19, the past crisis of Superstorm Sandy, and the ongoing crises of systemic racism, to identify some of the tactics and traits that allow existing civic groups to adapt to change and respond to crises. The third paper provides a high-level overview of the landscape of mutual aid groups in post-pandemic New York City, focusing on the ways in which political values guide the groups’ organization and action. The last paper dives deeper into the neighborhood context to understand how one mutual aid group, Crown Heights Mutual Aid, exercises mutual aid praxis, and how this work fits into the wider local civic network. Taken as a whole, this work addresses the need for understanding how the COVID-19 pandemic shaped the shifting landscape of post-disaster civic organizing; how compounding crises impact response networks, what happens as crises evolve, and how new groups interact with and change existing civic networks.
Findings from this research illustrate the wide scope of responses in relation to state entities, from public-private partnerships, to mutual aid groups working “outside of the state”, to networks of civic, private, and public actors. They show how some groups transitioned from rapid pandemic response to prioritizing ongoing issues such as housing injustice and carceral state violence, working toward transformative change. Finally, they indicate that groups learn important lessons in disaster organizing, which they continue to draw from as they face new crises. This dissertation exposes the various civic response networks that emerged following the COVID-19 pandemic; in looking at the efforts of existing civic groups, the emerging grassroots organizing, and the ways these two forms of civic networks intersect, it highlights the power of crisis events to not only galvanize short term altruism, but to create lasting infrastructures for future change.Ph.D.Includes bibliographical reference
Skill acquisition among Kenyan farmers growing African indigenous vegetables post integrated training
No full textKenya's agriculture sector plays a critical role in the country's economy, providing for seventy-five percent of the partial or entire income of the population and contributing thirty-three percent to the nation's Gross Domestic Product (USAID - Kenya, 2019). Within this sector, African Indigenous Vegetables (AIVs) have emerged as a promising crop due to their high nutritional value and adaptability. Despite their potential, there has been a long-term underinvestment in research and development, leading to a lack of awareness about the nutritional benefits of AIVs (Afari-Sefa et al., 2012). This paper examines the impact of a Horticulture Innovation Nutrition Research Program conducted in Kenya on farmers' skill acquisition. Through integrated training programs, farmers are equipped with the necessary knowledge and techniques to enhance AIV productivity, marketability, and consumption. The study employs a theoretical framework focusing on the acquisition of skills and techniques, with data collected through surveys conducted over a five-year period. Statistical analysis will explore the relationship between farmers' acquired skills and demographics, agricultural practices, and observed changes. The findings aim to inform NGOs, farmer associations, and policymakers on targeting specific populations for training programs, thereby enhancing farming practices and contributing to agricultural development in Kenya.M.S.Includes bibliographical reference
Fascist spectralities: haunted imaginaries in Italian and Latin American anti-fascist literature
No full textConsidering the rise of the radical right across the globe, this dissertation focuses on the representation of fascist violence in select works of literature from Italy and Latin America. The corpus includes Ennio Flaiano’s novel Tempo di uccidere (1947), the imaginary biographies La sinagoga degli iconoclasti (1972) by Argentinian-Italian writer Juan Rodolfo Wilcock; the imaginary biographies in La literatura nazi en América, and the novel Estrella distante (both from 1996) written by Chilean writer Roberto Bolaño. Additionally, the study explores a collection of poems, La canción de los presos (1981), written in prison by Hugo Gómez during the Uruguayan dictatorship (1973–1985). Therefore, the study engages with the possibilities offered by each genre, where the intervention of the reader plays a central role as an interpreter. Furthermore, the last section of this study is based on archival research, which led me to intersect various typologies of sources. Interdisciplinarity was a method I adopted when conducting my investigation. Criteria for selecting this corpus, spanning from the 1940s to the 1990s and originating from different cultural and social contexts, include the transhistorical and trans-national essence of fascism. These two features illustrate that fascism traverses time and space with various reinterpretations.
The primary purpose is to examine the literary representation of fascist violence through the notion of haunting, used as a metaphor and analytical tool. I contend that the spectral element allows us to open a dialogue between history and literature. However, fascism in literature requires a different conceptualization in comparison to a historical understanding. In literature, authors reinterpret this phenomenon in ways that depart from what is usually considered fascism in the social sciences.
The literary texts I analyze depict fascism not merely as a thematic element but as violence that takes place in language. To elucidate this argument and investigate the spectral elements appearing in these works, I will rely upon Kristeva’s notion of abjection, which serves as a connecting theme throughout the entire dissertation. For instance, Chapter One explores Flaiano’s novel and his condemnation of Italian colonialism, where abjection is connected to animal symbolism and the representation of evil. Chapter Two, dealing with Wilcock and Bolaño, explores the abject in relation to the authors’ use of black humor to represent fascist violence in language. Chapter Three deals with the collection of poems written during the Uruguayan dictatorship, emphasizing how the prisoners, rendered as abject through their imprisonment and the violence inflicted upon their bodies, re-appropriate this condition, specifically through writing, to regain subjectivity and empowerment. All these explorations aim to offer fresh insights into the interpretation of the fascist phenomenon across various disciplines.Ph.D.Includes bibliographical reference
Assessment of molecular uptake by cells by inducing mechanical stress on the cell membrane
No full textIntracellular delivery of the exogenous material into the cells across the plasma membrane is one of the biggest challenges in biological studies and applications. The most effective techniques are viral-based and non-viral-based, such as electroporation or lipofection. However, these techniques have some limitations, such as immunogenicity and cytotoxicity with the viral-based methods. Non-viral based techniques have low transfection efficiency and low viability. Electroporation can damage the cells. To address these limitations, we have aspired to develop a novel approach to deliver the exogenous material by inducing mechanical stress on the cell membrane via different cell stretching techniques and asses the molecular uptake by cells for different molecules. This study describes the assessment of the uptake of the propidium (PI), FITC-Dextran, or naked DNA into the cells by inducing the mechanical stress on the plasma membrane by the commercially available cell stretching system Flexcell and in another approach, cells are stretched by applying negative pressure using a suction cup. Cells were stretched at 5-20% strain for 90 seconds to 1 hour in combinations of the different conditions and parameters such as cyclic/static stretch, temperature, incubation period following stretch, etc. The uptake of the molecules was examined by fluorescence microscopy. This study also explored the different imaging techniques to visualize the stretched cells in real time and investigate the uptake of molecules in real time. Furthermore, this work explains the fabrication of the PDMS-based device to uniaxially stretch the different biological materials such as fibrin clots, blood clots, 3D cultured cells, and 2D cultured cells. The results suggest that cells did not uptake the exogenous material upon inducing external stress on the plasma membrane. However, these results require us to visualize the cells at the micro level during stretching to understand the effect of stress on the cell and plasma membrane and investigate and understand the role of endocytic pathways in the uptake of material.M.S.Includes bibliographical reference
Resisting the Confederacy
No full textThis essay investigates how contemporary artists Kara Walker, Kerry James Marshall and Kehinde Wiley create artworks responding to the lasting and lingering Confederate memorials, monuments and spaces in the United States. Each artist works within a different medium and context, but each responds to a specific representation of Confederate history. Having grown up in Atlanta, Walker recalls her experience living near the largest Confederate monument in the world, Stone Mountain, and creates her exhibition Go to Hell or Atlanta, Whichever Comes First, drawing upon this. Kerry James Marshall works within the context of the National Cathedral in Washington D.C. and created the Now and Forever windows to replace the stained glass windows that formerly depicted Thomas ‘Stonewall” Jackson and Robert E. Lee with images of African American people engaged in protest. Kehinde Wiley’s Rumors of War looks at the design of existing Confederate monuments while constructing his own monumental version of an anonymous Black man in streetwear straddled on top of a horse. This thesis not only examines how artists Kara Walker, Kerry James Marshall and Kehinde Wiley respond to Confederate monuments erected in America’s past, but also considers what they are saying about America today.M.A.Includes bibliographical reference
Development and integration of models for prediction and analysis of airport pavement friction
No full textThe safety of aircraft operations during landing and takeoff is of paramount importance and intricately connected to the skid resistance of the runway. Skid resistance, a critical factor ensuring adequate braking and traction, emerges as a pivotal element in mitigating potential hazards and optimizing overall aviation safety. However, the efficacy of skid resistance faces substantial challenges in moist conditions. Therefore, the tire-water-pavement interaction needs further investigation and there is a pressing need for in-depth exploration and analysis of interactions among tire, water, and pavement.First, an innovative methodology aimed at developing the physical correlation between aircraft braking performance and friction coefficients measured by ground devices. By incorporating energy dissipation and brush model, this approach facilitates the rapid and precise prediction of aircraft tire friction values under diverse conditions from measurements of ground devices.
To address the efficiency of pavement grooves, an analytical solution is further developed to analyze mechanical interactions between aircraft tire tread rubber and grooved pavement surfaces, resulting in the friction coefficients of grooved pavement. This study validates the method's capacity to predict friction coefficients under various groove configurations, providing essential insights for designing optimized groove patterns that contribute to enhanced skid resistance.
The intricate dynamics of tire-water-pavement interaction are then studied, aiming to determine the deformed tire profile and the effective tire-pavement contact length in the presence of water. An integrated analytical model, incorporating brush model for tire-pavement contact and the flexible ring model for tire deformation, accurately predicts friction coefficients under varying conditions. This approach underscores the significant impact of water depth on the risk of aircraft hydroplaning and overrun, emphasizing the critical role of understanding these interactions in ensuring safe aircraft operations.
As compared to analytical solutions, finite element modeling of tire-water-pavement interaction is studied with computational fluid dynamics. The model calculates the pavement friction coefficients of the runway under thick water film conditions. The results reveal a clear correlation between groove depth, water film depth, and friction coefficients, providing valuable insights for determining groove depth maintenance thresholds under diverse environmental and operational factors.
In summation, this dissertation offers a comprehensive exploration of runway pavement skid resistance, providing valuable insights into aircraft landing safety. By refining methods for predicting friction coefficients, designing effective pavement grooving patterns, understanding tire-water-pavement interactions, and establishing maintenance thresholds based on groove depth considerations, this research contributes to advancing the field and ensuring safer airport operations.Ph.D.Includes bibliographical reference
Miocene paleoceanography at Rockall Plateau site 982
No full textThe Miocene Epoch contains two juxtaposed end-member climate states beginning with the Miocene Climate Optimum (MCO) (17-14.8 Ma), the most recent interval of ice-free or near ice-free conditions, and ending with the abrupt establishment of a permanent East Antarctic Ice Sheet during the Middle Miocene Climate Transition (MMCT) (14.8-12.8 Ma). The North Atlantic plays an important role in global ocean water circulation and Earth’s climate and yet, relatively few sea surface temperature (SSTs) records have been generated for the Miocene in the subpolar North Atlantic. Biomarker (UK’37, TEX86) SST records at subpolar Ocean Drilling Program (ODP) Site 982 (57.5°N) yield SST estimates which indicate that surface waters in the high latitudes remained warm (>20°C) until ⁓8 Ma when 4°C cooling occurred. In contrast, foraminiferal-based estimates from subtropical and transitional DSDP Sites 563, 558, and 608 (33.6-42.8°N) indicate that the largest cooling (4°C) occurred during the MMCT between 14.8-12.8 Ma, recording little to no cooling after 8 Ma. We analyzed planktonic (G. bulloides and G. praebulloides) and benthic foraminifera (P. wuellerstorfi, S. tenuicarinata) from the Early to Late Miocene (20 to 4.5 Ma) at Site 982 for δ 18O and δ 13C to evaluate SSTs, thermocline and deepwater evolutions, and to test the biomarker-based reconstructions of SSTs in the subpolar North Atlantic. Our results show that planktonic foraminifera from Site 982 record a 1.45‰ increase in δ18O values between 15-13.8 Ma, reaching modern values by 11.75 Ma (1.55‰ Modern for G. bulloides). Accounting for ice volume difference using Miller et al. (2020) ice volume estimates, SSTs varied between 15-17°C during the MCO and cooled to 11-13°C with the MMCT, in line with the modern seasonal SSTs in the region (Modern winter 9°C, Modern Summer 13°C). Our benthic foraminiferal δ18O values record a 0.5‰ increase reflecting a 2-3°C deep-water cooling following the MCO. In contrast, the UK’37 and TEX86 based SSTs recorded modest cooling (22°C) through the MCO and subsequent Antarctic Ice sheet growth. Resolving disparities between SST proxies is important because they present two different and possibly incompatible scenarios. The biomarker-based estimates require an asymmetry in cooling with the subpolar North Atlantic maintaining subtropical conditions while the southern subpolar region cooled dramatically. We favor the stable isotope SST reconstruction because 1) the cooling coincides with CO2 decreases and the growth of a large ice sheet on Antarctica and 2) the resulting SST estimates following the MCO are similar to the modern seasonal SSTs over Rockall Plateau (10-13°C) and supports the preferred temperature ranges for the faunal species found in that interval.M.S.Includes bibliographical reference
Regulation of the G2/M cell cycle checkpoint by BRCA1 and RHINO
No full textThe G2/M cell cycle checkpoint reduces the risk of chromosome mutations that drive the onset of cancer by preventing cells with unrepaired DNA damage from entering mitosis. The tumor suppressor protein, BRCA1, and the RAD9, HUS1, and RAD1-interacting nuclear orphan protein 1 (RHINO1) are required for the regulation of the G2/M checkpoint, but the mechanisms by which they act are not fully understood. In this dissertation, the role of BRCA1 and RHINO in the G2/M checkpoint is further elucidated through the use of conditional-knockout mouse models. Our results show that Aurora A kinase, a key protein that promotes the transition into mitosis, remains active after DNA damage in BRCA1-mutant cells. Treating BRCA1-mutant cells with an Aurora A inhibitor rescues the G2/M checkpoint, indicating that it may be possible to restore normal responses to DNA damage in cells that lack functional BRCA1. We also show that RHINO-deficient B cells exhibit a defect in sustaining CHK1 activation after DNA damage, which correlates with a defect in the maintenance of the G2/M checkpoint. Moreover, RHINO-deficient cells exhibit increased genomic instability when treated with the PARP inhibitor, olaparib. Finally, based on an analysis of RHINO expression in cancer patients, we find that RHINO is overexpressed in several cancers and that high RHINO expression correlates with worse patient outcomes. Overall, our results confirm that BRCA1 is required for the G2/M checkpoint activation through regulation of Aurora A, whereas RHINO appears to be more important in maintenance of the G2/M checkpoint. Understanding the mechanism by which these factors regulate cell cycle checkpoints could offer opportunities for future clinical interventions to treat cancer patients with BRCA1 mutations or RHINO overexpression.Ph.D.Includes bibliographical reference