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In this dissertation, we will discuss two different holographic constructions. First, we construct a Penrose limit for the type IIB AdS6 � S2 � Σ solutions of [1, 2, 3]. These solutions are dual to 5d SCFT which can often be described in terms of long quiver gauge theories. The resulting plane wave spacetime takes a universal form and the worldsheet action of the Green-Schwarz string is quadratic in the light cone gauge allowing us to obtain the spectrum of string excitation.Next, we present a solution of d = 7 N = 4 gauged supergravity which is dual to co- dimension 2 defect living in a six-dimensional SCFT. Regularity conditions are satisfied by a one parameter family of solutions. We then uplift these to eleven dimensions where they can be understood as Lin-Lunin-Maldacena solutions. Using their electrostatic formulation, we find an infinite family of regular solutions describing holographic defects. We compute holographic observables in both the seven-dimensional and eleven-dimensional theories.

In this note we present a solution of $N=4,d=7$ gauged supergravity which is holographically dual to a co-dimension two defect living in a six dimensional SCFT. The solution is obtained by double analytic continuation of a two charge supersymmetric black hole solution. The condition that no conical deficits are present in the bulk and on the boundary is satisfied by a one parameter family of solutions for which some holographic observables are computed., 17 pages, PDFLaTeX, 2 figures, v2 reference added

Supplemental material, sj-docx-2-jpe-10.1177_0739456X231163755 for Transitions into and out of Car Ownership among Low-Income Households in the United States by Nicholas J. Klein, Rounaq Basu and Michael J. Smart in Journal of Planning Education and Research

Supplemental material, sj-docx-1-jpe-10.1177_0739456X231163755 for Transitions into and out of Car Ownership among Low-Income Households in the United States by Nicholas J. Klein, Rounaq Basu and Michael J. Smart in Journal of Planning Education and Research

Cities are currently struggling with how to regulate new micromobility modes, including e-scooters and dockless bikeshare. Cities are particularly concerned about micromobility parking regulations, which have implications for both traveler safety and mobility. We ask two research questions: 1. How often and for how long are scooters, bicycles, and motor vehicles improperly parked? 2. What are the approximate impacts of improper parking on other travelers, in terms of frequency, duration, and characteristics? In addition to answering the current and pressing need to understand parking on city sidewalks and streets, this project has the potential to influence long-range planning as cities adapt parking for a new era of urban transportation.

The purpose of this project is to analyze public views about transportation policy and potential reforms. We ask the following research questions: (1) What are common “legitimizing narratives” or beliefs about transportation? (2) How widespread is support for or opposition to changing the transportation status quo? (3) How malleable are views—particularly opposing views—about congestion and transportation funding?

Study Information Experiment: Can Information Change Opinions even after 6 months Hypothesis 1: Views about transportation funding and congestion mitigation policy become more favorable after reading refutation texts during an online experiment six months earlier. Design Plan Study design We previously conducted a mixed subject experiment with two factors (congestion and finance refutation texts). In this study, we are inviting the same participants to answer a subset of questions relating to our experiment Randomization We randomize—using the built-in Qualtrics randomization function—the order of survey questions assessing support or opposition to changing the transportation status quo. We also randomized the order of answer options (responses) to these questions. Sampling Plan Existing Data We have already conducted the initial survey but have not yet conducted the follow-up survey. Data collection procedures We are recruiting participants who completed valid responses in our October 2020 survey via an online opt-in survey panel. We will be contracting the same participants via Prolific.co. Participants will be paid $2 per survey to participate in the survey. Sample size Our target sample size is 599 respondents, the same number who participated in our October 2020 survey. However, we expect fewer will elect to participate in our survey. As of April 10th, 2021, 508 of these respondents were active on Prolific.co in the past 90 days. Power Analysis for 6-mo follow-up In the previous analysis, we had >80% power at alpha = 0.05, given our study design and the prevalence of the policy preferences we examined. This was especially true for the topic of induced demand, since the log-odds of the refutation text were so high and the pre-existing prevalence of alternatives to road building was fairly low. Effect sizes are likely to decline over 6 months, as are the number of eligible respondents, both of which will lead to lower statistical power. Currently 500 respondents are still available on the Prolific platform of our original sample. For the topic of transportation finance, if the effect size dropped by half from the effect size estimated from the immediate post-refutation text question, we would have: 81% statistical power (alpha = 0.05) with a sample size of 500 68% statistical power (alpha = 0.05) with a sample size of 400 53% statistical power (alpha = 0.05) with a sample size of 300 For the topic of induced demand / congestion, if the effect size dropped by half, we would have: 91% statistical power (alpha = 0.05) with a sample size of 500 76% statistical power (alpha = 0.05) with a sample size of 400 57% statistical power (alpha = 0.05) with a sample size of 300 We are therefore likely to have low statistical power for both topics, and especially for the gas tax. These numbers are all based on the effect sizes dropping by half, so the actual mileage may vary. Stopping rule We plan to leave the survey open for one month. Variables Measured variables Questions about preferred transportation policies for transportation finance and addressing congestions 7 questions Questions about transportation facts: 2 questions about transportation in the US with a correct answer rather than opinion-based Demographic questions Age: birth year Analysis Plan Statistical models For the experiment, we will estimate a Bayesian ordinal logit model with proportional odds, with policy agreement as the dependent variable and the treatment and all of the covariates included as independent variables. We will include person-specific varying effects to account for different response patterns by individual (e.g. some individuals may be more likely to use the full agree/disagree scale, others may be more likely to agree). Data exclusion We will exclude individual responses under the following conditions: Respondents who did not participate in our earlier survey Respondents that completed the survey too fast (3 SD outside the mean). Respondents that completed the refutation text portions too fast (3 SD outside the mean). Responses where the year born in our follow-up survey is different from the response in the initial survey Missing data We include a "force response" for all of the survey questions.

Supplemental material, sj-docx-1-jpe-10.1177_0739456X221097840 for Are Transportation Planning Views Shared by Engineering Students and the Public? by Kelcie Ralph, Nicholas J. Klein, Calvin Thigpen and Anne Brown in Journal of Planning Education and Research

New transportation options like ride-hail can expand accessibility without the costs of car ownership. Ride-hail’s potential is particularly salient for lower-income and zero-car households. We used interviews and a national (U.S.) survey to examine how and why lower-income travelers in the United States use ride-hail. Survey and interview responses provided a temporal snapshot and thus reflect, in part, travel challenges specific to COVID-19. Findings suggest that lower-income travelers, particularly those without personal cars, use ride-hail in ways distinct from those typically reported in broader travel surveys. Individuals without cars are more likely to use ride-hail, and use it more often, compared with people with cars, particularly to fill spatial and temporal gaps in public transit service and to access medical care and groceries. Costs and price unpredictability remain significant barriers limiting travelers’ use of ride-hail services. This research demonstrates a latent need for car access among lower-income travelers. Substantial gaps in alternative modes pose challenges for travelers seeking reliable and timely transportation. Planners should invest in transit, biking, and walking to provide robust alternatives to car ownership. Such investments, however, take time. In the meantime, cities and agencies should consider subsidizing ride-hail trips to bridge existing gaps in the transportation network.