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Assessment of Bridge Foundations for Reuse
No full textAbstract: Bridge foundations are increasingly being reused during replacement of obsolete or deteriorated superstructures. The reuse of existing foundations potentially allows for substantial savings in the cost or time of a bridge replacement project. While these savings can be used to enhance the viability of reconstruction project, the reuse of existing foundations presents additional considerations and issues that may require advanced analysis tools to consider. A comprehensive report on the evaluation of existing foundations being considered for reuse has been published as part of this research. This dissertation also presents three tools that have been developed to fill research needs identified during the production of this report. These tools provide methods to: characterize the behavior and properties of foundations; load rate substructures and superstructures in the presence of foundation movement, scour, or deterioration, and; improve empirical equation estimates of driven pile capacity for foundations that have been previously loaded.Thesis (Ph.D.)--Tufts University, 2018.Submitted to the Dept. of Civil Engineering.Advisor: Masoud Sanayei.Committee: Anil Agrawal, Babak Moaveni, Lucy Jen, and Hasan Abedi.Keyword: Engineering
The Effect of Temperature and Variation of Salinity during One Dimensional Compression
No full textAbstract: Understanding the uniaxial compression behavior of soil is important to engineers in the offshore oil and gas industry. Laboratory compression test data is a key parameter to characterizing overpressure zones underground. This research investigates two parameters related to one-dimensional compression behavior through a rigorous laboratory experimental program. First, the effect of temperature on compression behavior is examined using data from ten constant rate of strain tests. Five elevated temperature tests are compared to five room temperature tests in the stress range of 0.1 to 40 MPa to conclude that temperature does not have an effect on compression behavior. Additionally, there is an investigation of how the pore fluid salinity of a specimen changes with compression. The results of twenty-one salinity tests indicate that salinity decreases with compression. Following the experimental program a model is developed to predict the salinity at a given stress level and compared to the collected data.Thesis (M.S.)--Tufts University, 2018.Submitted to the Dept. of Civil Engineering.Advisor: John Germaine.Committee: Laurie Baise, and Richard Plumb.Keyword: Civil engineering
Gaussian Process Regression for CubeSat Data Interpolation with Uncertain Inputs and Multi-channel Outputs
No full textAbstract: With their greatly reduced sizes, low development cost and rapid construction time, CubeSats have emerged as a platform of intense interest for a wide range of applications, including remote sensing. Many applications require the interpolation of irregularly sampled (scattered) sensor data onto a regularly spaced grid for the development of downstream scientific products. This problem is further complicated for the CubeSat platform by two factors. First, there exist potentially significant uncertainties associated with the spatial position of the satellite sensor, which if left unattended, will negatively impact the interpolation performance. Second, instead of collecting a data point from each sampling location, the CubeSat radiometer usually captures data from multiple frequency channels, which turns the scattered data interpolation problem from single output to multi-channel outputs. In this thesis, models and associated algorithms based on the framework of Gaussian Process (GP) Regression are provided to solve both problems. The Optimized Gaussian Process Regression (OGPR) approach provides both estimation of the value on the grid and the geolocation by forming a Maximum A Posterior (MAP) estimation which couples the statistical model for spatial variations in the sensor data field provided by a GP model with a stochastic model for positional uncertainties. For the multi-channel interpolation problem, we propose a Gaussian Process Mixture Model (GPMM) that extends the naive GP model by constructing the covariance matrix as a superposition of Kronecker products between spatial variations for each output channel and weight matrices allowing for mixing across channels. Both approaches are proven to provide superior performance compared with traditional approaches in real data experiments. Although the algorithms that we discuss in this thesis are motivated from the CubeSat application, they can be used in anywhere where the model is applicable.Thesis (Ph.D.)--Tufts University, 2018.Submitted to the Dept. of Electrical Engineering.Advisor: Eric Miller.Committee: William Blackwell, Mai Vu, and Liping Liu.Keyword: Electrical engineering
Epstein-Barr virus persistence: implications for the pathogenesis of endemic Burkitt's and immunosuppression-related B-cell lymphoma
No full textAbstract: The germinal center model (GCM) of Epstein-Barr virus (EBV) persistence proposes that EBV infects and drives naïve B cells through the GC to become resting memory B cells where the virus persists quiescently in a non-pathogenic state for the lifetime of the host. Yet, EBV causes several cancers. First, we asked how simultaneous infection with Plasmodium falciparum malaria and EBV causes the GC B cell-derived endemic Burkitt's lymphoma (eBL), which is the most common childhood cancer in malaria-endemic areas of Africa. eBL is associated with EBV and malaria infections, and accumulated evidence indicates that eBL arises when deregulated expression of activation-induced cytidine deaminase (AID) causes a c-Myc/Ig translocation that in turn activates the c-Myc oncogene in an EBV-infected GC B cell. Previously, we showed that in humans, Plasmodium falciparum malaria causes deregulated expression of AID mRNA in GC B cells, increases the level of GC B cells and dramatically increases the frequency of EBV-infected GC B cells. Here, with the aid of ex vivo tonsillar B cell stimulation assays, we demonstrate that Plasmodium falciparum strongly stimulates AID mRNA and protein, due in part to hemozoin, the metabolic by-product of hemoglobin digestion by the parasite. We conclude that Plasmodium falciparum causes deregulated expression/activity of AID in GC B cells concomitant with an increase in the level of EBV-infected GC B cells. This increases: the risk of the c-Myc/Ig translocation in EBV-infected GC B cells that can tolerate the translocation, and the incidence of eBL. In a second study, we searched for the in vivo precursors of immunosuppression-related/immunoblastic B-cell lymphoma (IL) which occurs in immunosuppressed transplant and HIV patients. IL resembles in vitro EBV- infected B cells driven by EBV to become indefinitely proliferating lymphoblastoid cell lines (LCLs). Using comparative human tonsillar B cell analysis, we demonstrate that EBV-infected marginal zone (MZ) B cells which are GC-independent, are the closest in vivo correlates of LCLs/ILs and hence the plausible in vivo precursors of IL in humans. Taken together, these studies show that there are two pathways of EBV persistence in humans: 1. the GCM and 2. the GC-independent MZ model, and these result in two types of lymphoma: eBL and IL, respectively. EBV-associated malignancies are the consequence of immune-dysregulation that allows EBV-infected cells at specific stages of B cell differentiation to escape immune-surveillance, survive and engender tumorigeneses.Thesis (Ph.D.)--Tufts University, 2018.Submitted to the Dept. of Immunology.Advisor: David Thorley-Lawson.Committee: Joan Mecsas, Honorine Ward, and Thereza Imanishi-Kari.Keyword: Immunology
The use of low-cost Android tablets to train community health workers in Mukono, Uganda, in the recognition, treatment and prevention of pneumonia in children under five: a pilot randomised controlled trial.
No full textBackground: Since 2012, The World Health Organization and UNICEF have advocated for community health workers (CHWs) to be trained in Integrated Community Case Management (iCCM) of common childhood illnesses, such as pneumonia. Despite the effectiveness of iCCM, CHWs face many barriers to accessing training. This pilot study compares traditional training with using locally made videos loaded onto low-cost Android tablets to train CHWs on the pneumonia component of iCCM.Keywords: Community health worker (CHW), Uganda, Pneumonia, mHealth, Mobile technologies, Integrated Community Case Management (iCCM).Springer Open
Obstacles to Estimating Voter ID Laws' Effect on Turnout.
No full textWidespread concern that voter identification laws suppress turnout among racial and ethnic minorities has made empirical evaluations of these laws crucial. But problems with administrative records and survey data impede such evaluations. We replicate and extend Hajnal, Lajevardi, and Nielson's 2017 article, which concludes that voter ID laws decrease turnout among minorities, using validated turnout data from five national surveys conducted between 2006 and 2014. We show that the results of their article are a product of data inaccuracies, the presented evidence does not support the stated conclusion, and alternative model specifications produce highly variable results. When errors are corrected, one can recover positive, negative, or null estimates of the effect of voter ID laws on turnout, precluding firm conclusions. We highlight more general problems with available data for research on election administration, and we identify more appropriate data sources for research on state voting laws' effects
Building consensus through modeling: A framework for the fitness of ideas in classroom science discourse.
No full textA qualifying paper submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Education. Abstract: Scientists use argumentation, critique, and modeling to generate consensus around particular ideas. Students in science classrooms can be supported to engage in similar knowledge-building discourses. However, they often come up with idiosyncratic representations as they participate in these scientific practices. In this paper, we direct our attention to the dynamics of ideas as a lens to examine why certain ideas were taken up in knowledge-building discourses around condensation. Drawing from memetics, we present the Idea Fitness Framework (IFF), which identifies four selection forces that contribute to an idea’s fitness in student modeling discourses. Using microgenetic and sociogenetic examples of how the forces operate in the classroom, we show how IFF operates as a dynamic system that helps to explain how consensus is reached among fifth-grade students in one class engaged in modeling the process of condensation using computational tools
Financial IncEntives for Smoking TreAtment: protocol of the FIESTA trial and FIESTA Oral Microbiome Substudy.
No full textBackground: Smoking is the leading preventable cause of death in the United States, but evidence-based smoking cessation therapy is underutilized. Financial incentive strategies represent an innovative approach for increasing the use of counseling and pharmacotherapy. If effective, they could supplement or supplant resource-intensive policy options, particularly in populations for whom smoking has substantial societal costs. FIESTA (Financial IncEntives for Smoking TreAtment) will randomize hospitalized smokers to receive usual smoking cessation care alone or usual smoking care augmented with financial incentives. We aim to compare the impact of these two strategies on 1) smoking abstinence, 2) use of counseling and nicotine replacement therapy, and 3) quality of life of participants. We also will evaluate the short-term and long-term return on the investment of incentives. The FIESTA Oral Microbiome Substudy will compare the oral microbiome of smokers and nonsmokers to longitudinally assess whether smoking cessation changes oral microbiome composition.Keywords: FIESTA, Smoking cessation, Manhattan VA Hospital, Financial incentives, Veterans.Springer Open
A History of Political Thought: De Administrando Imperio and Six Bookes of a Commonweale.
No full textSummer Scholars poster based on research about Byzantine political theory and work as a research assistant for the Bodin Project. Submitted in partial fulfillment of the grant requirement of the Tufts Summer Scholars Program
Clean Green Driving Machines: Reducing Municipal Vehicle Fuel Consumption.
No full text2018 M.A. in Urban and Environmental Policy and Planning Field Project. Client: Mass Department of Energy Resources, Green Communities Division