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A translational approach for modeling the cognitive substrates of depression : identifying biological predictors and neurocognitive interventions for biased cognition
No full texttextMajor Depressive Disorder (MDD) is a pervasive, debilitating condition that affects roughly 16% of Americans in their lifetime. However, treatments for MDD are considered adequate in only 21% of cases. Although biological and cognitive models have significantly added to our understanding of MDD, relatively little work has been undertaken to bridge the two. In particular, the biological factors that contribute to cognitive risk factors for MDD remain largely unknown. This dissertation used a translational approach to identify the specific neurobiological underpinnings of cognitive vulnerability for MDD, with the goal of identifying neurocognitive interventions to help improve treatment outcomes. These results were built on an empirical foundation beginning with the neural substrates of Aaron Beck's cognitive model of depression, and expanded on that literature by identifying genetic factors that predict the onset of maladaptive cognitive biases. Prospective research linking specific cognitive biases to naturalistic change in dysphoric symptoms was incorporated to establish the link between biased information processing and MDD maintenance. Finally, neuroenhancement techniques, such as low-level light therapy (LLLT), were used to augment the neural substrates of attention bias modification (ABM), a form of neurocognitive intervention, in order to optimize the treatment's clinical efficacy. This line of research helps to establish cognitive biases as a causal endophenotype for MDD, explores novel augmentative treatment strategies, and advances our understanding about biomarkers that predict improved clinical outcome.Psycholog
Exploring adaptation with evolutionary activity plots
No full textEvolutionary activity statistics and their visualization are introduced, and their motivation is explained. Examples of their use are described, and their strengths and limitations are discussed. References to more extensive or general accounts of these techniques are provided
High-G unmanned aerial vehicle structure
No full textThesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2000.Includes bibliographical references (p. 135-138).This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.In 1997, the Charles Stark Draper Laboratories commenced a project with the objectives of reducing the risk, cost and time associated with obtaining time critical battlefield reconnaissance data. The Wide Area Surveillance Projective, or WASP, is a small autonomous flyer, which is launched contained in an artillery shell, and then deployed over the battlefield to capture images. The first phase of this project involved identifying and solving the challenges associated with designing a device capable of surviving launch loads of 15,000 g’s. The second phase of WASP is currently addressing the manufacturing and flight control issues. The focus of this thesis is on the structural design and manufacture of the WASP vehicle, particularly the aft fuselage section and the wings. The aft section is not only subjected to high impulsive inertial loads, but its weight (being aft of the center of pressure) has a substantial effect on the controllability of the vehicle. Finite element models of this section as well as test specimens are produced to optimize the design. The wings are required to be stiff aerodynamic surfaces, and are folded along the side of the vehicle so as to take up minimal volume. Several different manufacturing procedures are explored to provide a robust set of wings that match all of the specified requirements. All of these pieces need to be as light as possible; therefore they are manufactured in advanced composite materials.by Seth Stovack Kessler.S.M
Discovery of an optical counterpart to the hyperluminous X-ray source in ESO 243-49
No full textThe existence of black holes of masses similar to 10(2)-10(5)M(circle dot) has important implications for the formation and evolution of star clusters and supermassive black holes. One of the strongest candidates to date is the hyperluminous X-ray source (HLX1), possibly located in the S0- a galaxy ESO 243-49, but the lack of an identifiable optical counterpart had hampered its interpretation. Using the Magellan telescope, we have discovered an unresolved optical source with R = 23.80 +/- 0.25 mag and V = 24.5 +/- 0.3 mag within HLX1's positional error circle. This implies an average X-ray/optical flux ratio similar to 500. Taking the same distance as ESO 243-49, we obtain an intrinsic brightness M-R = -11.0 +/- 0.3 mag, comparable to that of a massive globular cluster. Alternatively, the optical source is consistent with a main-sequence M star in the Galactic halo (for example an M4.4 star at approximate to 2.5 kpc). We also examined the properties of ESO 243-49 by combining Swift/Ultraviolet/Optical Telescope (UVOT) observations with stellar population modelling. We found that the overall emission is dominated by a similar to 5-Gyr-old stellar population, but the UV emission at approximate to 2000 angstrom is mostly due to ongoing star formation at a rate of similar to 0.03M(circle dot) yr(-1). The UV emission is more intense (at least a 9 sigma enhancement above the mean) north-east of the nucleus, in the same quadrant as HLX1. With the combined optical and X-ray measurements, we put constraints on the nature of HLX1. We rule out a foreground star and a background AGN. Two alternative scenarios are still viable. HLX1 could be an accreting intermediate mass black hole in a star cluster, which may itself be the stripped nucleus of a dwarf galaxy that passed through ESO 243-49, an event which might have caused the current episode of star formation. Or, it could be a neutron star in the Galactic halo, accreting from an M4-M5 donor star
Measuring the anomalous precession frequency of the muon in run 2 of the Fermilab muon g-2 experiment
No full textSubmission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2023-12-01The student, Cristina Schlesier, accepted the attached license on 2021-10-11 at 19:40.The student, Cristina Schlesier, submitted this Dissertation for approval on 2021-10-13 at 16:04.This Dissertation was approved for publication on 2021-11-01 at 15:07.DSpace SAF Submission Ingestion Package generated from Vireo submission #17156 on 2022-04-06 at 17:16:41Made available in DSpace on 2022-04-29T21:42:55Z (GMT). No. of bitstreams: 2
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Previous issue date: 2021-11-01Embargo set by: Seth Robbins for item 123319
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Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 123319
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Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemAuthor requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemU of I OnlyThe E989 Muon g −2 Experiment at Fermilab aims to measure the anomalous magnetic moment of the muon, aμ, to an unprecedented precision of 140 parts per billion (ppb). Currently, a 4.2σ discrepancy exists between the experimental value of aμ and the theoretical value given by the Standard Model. The goal of E989 is to either confirm this discrepancy and suggest new physics, or show the discrepancy to be an error. The first result from E989 has been published [1], using data collected during Run 1, which confirms the tension between theory and experiment. A total of 5 runs are planned, increasing the amount of data by roughly a factor of 10. This thesis outlines the history, motivations, and physics of the E989 experiment, and presents a preliminary analysis of data collected during Run 2.
Determining aμ requires a precision measurement of two main quantities: (1) the anomalous precession frequency of muons in a magnetic storage ring and (2) the magnetic field experienced by those muons. The anomalous precession frequency, ωa must be measured with a systematic uncertainty below 70ppb in order for the collaboration to achieve its target precision. The analysis presented here concerns ωa
GNOM v1.0: an optimized steady-state model of the modern marine neodymium cycle
No full text© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Pasquier, B., Hines, S. K., Liang, H., Wu, Y., Goldstein, S. L., & John, S. G. GNOM v1.0: an optimized steady-state model of the modern marine neodymium cycle. Geoscientific Model Development, 15(11), (2022): 4625–4656. https://doi.org/10.5194/gmd-15-4625-2022.Spatially distant sources of neodymium (Nd) to the ocean that carry different isotopic signatures (εNd) have been shown to trace out major water masses and have thus been extensively used to study large-scale features of the ocean circulation both past and current. While the global marine Nd cycle is qualitatively well understood, a complete quantitative determination of all its components and mechanisms, such as the magnitude of its sources and the paradoxical conservative behavior of εNd, remains elusive. To make sense of the increasing collection of observational Nd and εNd data, in this model description paper we present and describe the Global Neodymium Ocean Model (GNOM) v1.0, the first inverse model of the global marine biogeochemical cycle of Nd. The GNOM is embedded in a data-constrained steady-state circulation that affords spectacular computational efficiency, which we leverage to perform systematic objective optimization, allowing us to make preliminary estimates of biogeochemical parameters. Owing to its matrix representation, the GNOM model is additionally amenable to novel diagnostics that allow us to investigate open questions about the Nd cycle with unprecedented accuracy. This model is open-source and freely accessible, is written in Julia, and its code is easily understandable and modifiable for further community developments, refinements, and experiments.This work has been supported by the Simons Foundation (grant no. 426570SP to Seth G. John), the National Science Foundation (grant no. OCE-1736896 to Seth G. John and grant no. OCE-1831415 to Steven L. Goldstein and Sophia K. V. Hines), the Investment in Science Fund at WHOI and the John E. and Anne W. Sawyer Endowed Fund in Support of Scientific Staff (Sophia K. V. Hines), and the Storke Endowment of the Department of Earth and Environmental Sciences, Columbia University (Steven L. Goldstein)
Adaptation in syntactic comprehension: a replication
No full textThe student, Caoimhe Harrington Stack, accepted the attached license on 2016-07-21 at 16:01.The student, Caoimhe Harrington Stack, submitted this Thesis for approval on 2016-07-21 at 16:09.This Thesis was approved for publication on 2016-07-22 at 14:03.DSpace SAF Submission Ingestion Package generated from Vireo submission #10061 on 2016-11-10 at 12:27:38Made available in DSpace on 2016-11-10T18:35:36Z (GMT). No. of bitstreams: 2
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Previous issue date: 2016-07-22Language comprehension requires successfully navigating through a great degree of variability that is encountered on all linguistic levels. One hypothesis of how this variability is successfully dealt with is that listeners can rapidly update their statistical knowledge of how likely a linguistic event is to occur in a specific context. This process, called adaptation, allows listeners to better predict upcoming linguistic input. In previous work, Fine et al. (2013) designed an experiment to test for adaptation to uncommon syntactic structures. Subjects repeatedly encountered temporarily ambiguous RC/MV sentences. They found that subjects who had more exposure to the unexpected RC interpretation of the sentences had an easier time reading RC sentences but a harder time reading MV sentences. They concluded that syntactic adaptation occurs rapidly in unexpected structures and also results in trouble processing previously-expected, alternative structures. However, a power analysis revealed that Fine et al. (2013) ran an underpowered study. This thesis was designed to serve as a replication of Fine et al. (2013) with appropriate power. There was a failure to replicate Fine et al. (2013). The findings suggest instead that syntactic adaptation does not happen as rapidly as previously thought.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2018-08-01Embargo set by: Seth Robbins for item 95400
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Photonic crystal enhancement and tuning of quantum dot emission
No full textThe work presented in this dissertation demonstrates various methods and approaches for photonic crystals (PCs) to enhance the output emission and performance of quantum dots (QDs). We integrate visible wavelength emitting QDs within a polymer-based photonic crystal and excite them using an ultraviolet-emitting LED. The PC design incorporates two interleaved regions, each with distinct periods in orthogonal directions to enable simultaneous resonant coupling of ultraviolet excitation photons to the QDs and visible QD emission at two different wavelengths to efficiently extract photons normal to the PC surface. The combined excitation and extraction enhancements result in a 5.8X increase in the QD output intensity. Further, we demonstrate multiple QD-doped PCs combined on a single surface to optimally couple with distinct populations of QDs, offering a means for blending color output and directionality of multiple wavelengths.
Another replica molded PC is fabricated with embedded QDs in which electrohydrodynamic jet printing is used to control the position of the quantum dots within the device structure. This results in significantly less waste of the QD material and the targeted placement of the quantum dots minimizes any emission outside of the resonant enhancement field, enabling an 8X output enhancement and highly polarized emission from the PC structure.
We demonstrate a method for combining sputtered TiO2 deposition with liquid phase dip-coating of a QD layer that enables precise depth placement of QD emitters within a high-index dielectric film, using a PC slab resonator to demonstrate enhanced emission from the QDs when they are located at a specific depth within the film. The depth of the QDs within the PC is found to modulate the resonant wavelength of the PC as well as the emission enhancement efficiency, as the semiconducting material embedded within the dielectric changes its spatial overlap with the resonant mode.
The first real-time tuning of PC-enhanced QD emission is successfully performed by fabricating QD embedded PCs on the surface of an acoustic MEMs resonator. As the RF modulation deforms the piezoelectric material of the resonator, the surface PC is also deformed. The coupling wavelength of the PC is modulated away from the QD emission wavelength, producing measurable variation in the output intensity of the QD emission. By tailoring the design and fabrication of QD-embedded PCs, significant improvements in device efficiency and production costs can be realized for utilizing QDs in lighting and display applications.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2018-05-01The student, Gloria See, accepted the attached license on 2016-01-22 at 14:20.The student, Gloria See, submitted this Dissertation for approval on 2016-01-22 at 15:00.This Dissertation was approved for publication on 2016-01-29 at 15:17.DSpace SAF Submission Ingestion Package generated from Vireo submission #9045 on 2016-07-07 at 14:15:53Made available in DSpace on 2016-07-07T21:04:18Z (GMT). No. of bitstreams: 2
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Previous issue date: 2016-01-29Embargo set by: Seth Robbins for item 93213
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Surface-mediated mechanisms for defect engineering in zinc oxide
No full textThe technological usefulness of a solid often depends upon the types and concentrations of the defects it contains. In semiconducting metal oxides like zinc oxide, the concentration and diffusion of oxygen point defects, like interstitials and vacancies, play a central role in various physical phenomena, such as gas sensing, bipolar switching, photoluminescence and photocatalysis. Defect engineering in metal oxides aims at manipulating material properties through controlling the defects’ type, concentration, charge, spatial distribution, and mobility.
A specific challenge that inhibits performance improvement in metal oxide devices for microelectronics, photonics, and photocatalysis usages is that bulk oxygen vacancies (VO) are typically numerous and serve as carrier recombination centers or electron current scatterers. One solution suggested by our laboratory is to thermally inject highly mobile charged oxygen interstitials (Oi) through metal oxide surfaces from the gas phase to annihilate VO in the underlying bulk. Developing novel mechanisms to control such diffusion process would be crucial in tailoring material defect chemistry for real life applications. The present work demostrates two special surface-based control mechanisms for this purpose in the case of zinc oxide: near-surface electrostatics and the chemical state of surface active sites.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2018-12-01The student, Ming Li, accepted the attached license on 2016-11-22 at 20:12.The student, Ming Li, submitted this Dissertation for approval on 2016-11-22 at 20:27.This Dissertation was approved for publication on 2016-11-23 at 13:24.DSpace SAF Submission Ingestion Package generated from Vireo submission #10302 on 2017-02-28 at 14:42:01Made available in DSpace on 2017-03-01T17:01:33Z (GMT). No. of bitstreams: 2
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Previous issue date: 2016-11-23Embargo set by: Seth Robbins for item 98701
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On defect CFT and path integral methods for entanglement in quantum field theories
No full textIn the first few chapters of the thesis, we will study defect CFT methods based on the replica trick for characterizing quantum information in quantum field theories. We calculate a coefficient that characterizes the strength of the two point function of the displacement operator in the replica twist defect placed in a holographic CFT, which controls the second order shape dependence of Renyi entropy. We introduce defect CFT methods for calculating correlation functions involving the modular Hamiltonian together with probe operators inserted at lightcone separation. We use these methods to further calculate correlation functions involving modular flows of these probe operators. Tomita-Takesaki theory constrains these correlation functions, which when combined with our defect CFT calculations, provides a proof of the Quantum Null Energy Condition.
In the last few chapters of this thesis, we will calculate entanglement measures for states that are defined by a Euclidean path integral together with a source for an operator inserted in the path integral. We provide a purely Lorentzian formula for the modular Hamiltonians for these states for flat entangling cuts which systematizes the task of writing time-ordered expressions for relative entropy of these states with respect to the vacuum to all orders in the source. We further apply this method to calculate a formula for shape deformed modular Hamiltonian for the vacuum state to all orders in the shape deformation. In the case of null shape deformation, we recover the formula for the vacuum modular Hamiltonian for null cuts. We then calculate the shape deformation of relative entropy and provide evidence for the presence of a shock in the stress tensor expectation value when one performs the Connes cocycle flow of the state.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2023-12-01The student, Srivatsan Balakrishnan, accepted the attached license on 2021-07-16 at 15:10.The student, Srivatsan Balakrishnan, submitted this Dissertation for approval on 2021-07-16 at 15:25.This Dissertation was approved for publication on 2021-07-19 at 10:22.DSpace SAF Submission Ingestion Package generated from Vireo submission #16990 on 2022-04-06 at 17:16:09Made available in DSpace on 2022-04-29T21:41:38Z (GMT). No. of bitstreams: 3
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Previous issue date: 2021-07-19Embargo set by: Seth Robbins for item 123298
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Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 123298
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Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 123298
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Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 123298
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Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemAuthor requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemU of I Onl
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