A list of my academic and technical publications, with abstracts and links to the documents themselves, follows. In addition, the page A Nation of Neighborhoods is a summary of my Master’s thesis in human geography, A Nation of Neighborhoods: A Quantitative Understanding of US Neighborhoods and Metropolitan Areas, and a collection of figures of interest at higher resolution than was possible to include in the PDF document itself.
DW Rowlands and Hanna Love, “Mapping Rural America’s Diversity and Demographic Change.” Blog Post. Washington, DC: Brookings Institution Metropolitan Policy Program (2021).
The release of 2020 Census population data provided much-anticipated insight into the demographic trends reshaping our nation, but it also unleashed a wave of predictable headlines touting the demise of “shrinking rural America.” The familiar narrative of “two Americas”—one diverse, metropolitan, and successful and one white, rural, and declining—cropped up once more, often explicitly equating “rural” with “white” or, even more simplistically, with white Trump voters.
While this narrative provides an easy way to think about America in binary terms, it obscures the far more complicated trends shaping rural America: most notably, its growing demographic diversity over the last decade. While it is true that the population of nonmetropolitan[1] America fell by about half a percentage point between 2010 and 2020, the future of rural America is increasingly marked by growing diversity and expanding inequity within and across regions—creating an intricate picture that binary thinking can’t capture.
DW Rowlands and Tracy Hadden Loh, “Reinvesting in Urban Cores Can Revitalize Entire Regions.” Research Report. Washington, DC: Brookings Institution Metropolitan Policy Program (2021).
The United States began the 20th century as a rural nation, evolved into a nation of cities, and ended the century with a suburban majority. The first half of this transition—from a nation of farmers to one of urban workers—was part of a global trend, as economies shifted from agrarian to manufacturing to services. The second half—from a nation of cities to a nation of suburbs—was especially pronounced in the U.S. due to government policies that invested in suburbanization. These policies included federal subsidies for suburban mortgages, tax subsidies that favored sprawl, and the construction of urban highways that destroyed dense neighborhoods of color while speeding suburban commuters to downtown jobs. By dispersing and isolating different people and assets, these policies supersized segregation and left behind a fragile, unjust infrastructure landscape.
In this piece, we analyze urban-to-suburban population shifts over the last 70 years to underscore how wealth and jobs moved out of American cities and left behind segregated, disinvested communities. A solution, we conclude, can be found through a broad coalition of pro-growth as well as racial and environmental justice groups to advance region-wide prosperity through reinvesting in urban cores.
DW Rowlands, “A Nation of Neighborhoods: A Quantitative Understanding of US Neighborhoods and Metropolitan Areas.” M.S. Thesis, University of Maryland, Baltimore County, (2021).
While pedestrian-oriented urban places have been identified as beneficial in a number of fields, including public health and climate change, there is a shortage of quantitative studies of such places covering large geographic areas. This study characterizes neighborhoods in US metropolitan areas based on built environment and density variables derived from the American Community Survey, Longitudinal Employer-Household Dynamics Origin-Destination Employment Statistics, National Land Cover Database, and OpenStreetMaps datasets.
Neighborhoods and metropolitan areas as a whole are typologized based on this data using k-means analysis. The resulting neighborhood and metro area types are analyzed in connection with metro area history, the distributions of residents by race and jobs by income, and qualitative perceptions of density. Finally, the implications of these results for public transportation are discussed, and it is shown that transit commute share in US metro areas is strongly correlated with the number of jobs in dense central business districts.
Thesis Supervisor: Prof. Dillon Mahmoudi, University of Maryland, Baltimore County Department of Geography and Environmental Systems
DW Rowlands and Tracy Hadden Loh, “Retail Revolution: The New Rules of Retail Call for Small Business Empowerment.” Research Report. Washington, DC: Brookings Institution Metropolitan Policy Program (2020).
The full effects of the COVID-19 pandemic on U.S. retail may not be fully clear for months. Many stores and restaurants have closed permanently, but some—especially those located in residential neighborhoods where more people are working from home—may benefit from the changes to people’s routines. What is clear is that that these new and powerful impacts on the sector are coming on top of much longer-term changes in how and where people shop.
Post-pandemic, every metropolitan area—but especially metro areas in the Midwest and the Southeast—will find themselves with surplus retail space in need of major capital investment for adaptive reuse. Short-term strategies to stabilize department-store-anchored malls will not last against long-term trends, and long-standing racial disparities in access to retail will reinforce structural racism at a time when the nation is crying out for racial justice. The industry and policymakers should view this as an opportunity to work together to create new opportunities for housing, institutional uses, and locally empowered retail entrepreneurship.
DW Rowlands. “Understanding Walkable Density.” Research Report. Portland, OR: City Observatory (2020).
Density is one of the most fundamental properties of urban areas: what makes a city different from a suburb, and suburbs different from rural areas is chiefly how many people there are, and how close they are to each other. However, measuring the number of people or jobs per square mile does not reflect the effect of street networks on density as observed by a pedestrian.
Most neighborhoods in American metro areas don’t have ideal street grids, however: winding roads and cul-de-sacs force pedestrians to take indirect trips, and bodies of water, hills, freeways, industrial areas, and superblocks often pose barriers, reducing the number of destinations that can be reached by walking a given distance. In this article, I present a statistic called “Percent Ideal Walkshed” that takes this into account by measuring the fraction of locations within a half mile of the center a block group that are actually within a half-mile walk of it.
John F. Strang, Megan Knauss, Anna van der Miesen, Jenifer K. McGuire, Lauren Kenworthy, Reid Caplan, Andrew Freeman, Eleonora Sadikova, Zosia Zaks, Noor Pervez, Anouk Balleur, DW Rowlands, Ely Sibarium, Laura Willing, Marissa A. McCool, Randall D. Ehrbar, Shannon E. Wyss, Harriette Wimms, Joshua Tobing, John Thomas, Julie Austen, Elyse Pine, April D Griffin, Aron Janssen, Veronica Gomez-Lobo, Abigail Brandt, Colleen Morgan, Haley Meagher, Dena Gohari, Laura Kirby, Laura Russell, Meredith D. Powers, and Laura G. Anthony. “A clinical program for transgender and gender-diverse neurodiverse/autistic adolescents developed through community-based participatory design.” Journal of Clinical Child & Adolescent Psychology (2020): 1-16.
A series of studies report elevated rates of autism and autistic characteristics among gender-diverse youth seeking gender services. Although youth with the co-occurrence present with complex care needs, existing studies have focused on co-occurrence rates. Further, clinical commentaries have emphasized provider-centered interpretations of clinical needs rather than key stakeholder-driven clinical approaches. This study aimed to employ community-based participatory research methodologies to develop a key stakeholder-driven clinical group program.
Autistic/neurodiverse gender-diverse (A/ND-GD) youth (N = 31), parents of A/ND-GD youth (N = 46), A/ND-GD self-advocates (N = 10), and expert clinical providers (N = 10) participated in a multi-stage community-based participatory procedure. Needs assessment data were collected repeatedly over time from A/ND-GD youth and their parents as the youth interacted with one another through ongoing clinical groups, the curriculum of which was developed progressively through the iterative needs assessments.
Separate adolescent and parent needs assessments revealed key priorities for youth (e.g., the importance of connecting with other A/ND-GD youth and the benefit of experiencing a range of gender-diverse role models to make gender exploration and/or gender affirmation more concrete) and parents (e.g., the need for A/ND-related supports for their children as well as provision of an A/ND-friendly environment that fosters exploration of a range of gender expressions/options). Integration and translation of youth and parent priorities resulted in 11 novel clinical techniques for this population.
With generally high acceptability ratings for each component of the group program, this study presents a community-driven clinical model to support broad care needs and preferences of A/ND-GD adolescents.
DW Rowlands. “Xenon Difluoride Etching and Molecular Oxygen Oxidation of Silicon by Reactive Scattering,” M.S. Thesis, Massachusetts Institute of Technology (2015).
While both molecular fluorine (F2) and xenon difluoride (XeF2) fluorinate Si(100)2×1 surfaces at coverages up to one monolayer, fluorine is unable to cleave Si-Si bonds that ultimately leads to etching silicon at coverages above one monolayer (reaction probability 9×10–4) while XeF2 does so readily (reaction probability 0.6). Previous studies have demonstrated that both fluorine and xenon difluoride react with silicon via atom-abstraction mechanisms at low coverages, and that the XeF radicals produced by atom abstraction from xenon difluoride dissociate in the gas phase, producing a source of F radicals that may contribute to Si-Si bond cleavage by formation of multiple F-Si bonds. In addition, it has been shown that van der Waals clusters of F2 with a Xe atom and with a Kr atom have reaction probabilities with silicon at one monolayer of fluorine coverage of roughly 0.9 and 0.04, respectively, suggesting that the effect of mass of the incident gas molecules is important in activating the cleavage of silicon-silicon bonds through a multiple collision process.
A model based on a classical harmonic oscillator linked via a variable damping term to the thermal energy of the lattice is proposed to test the importance of the mass of the gas molecules to energy transfer and the duration of the vibrational excitation of the silicon-silicon lattice bonds. Computer simulations using this model suggest that the mass of the gas molecule does not affect the overall energy transferred to the silicon. However, the heavy mass and the resulting multiple collisions do extend the duration of the silicon excitation and the duration during which the gas molecule is in contact with the vibrationally excited silicon lattice.
The techniques that have been used to study the reactivity of fluorine compounds with silicon are potentially of use to the study of another problem: why triplet molecular oxygen (O2) is able to dissociatively chemisorb across singlet silicon-silicon dimer bonds to form the singlet Si-O product. Several mechanisms, including atom abstraction and non-adiabatic ladder climbing of (O2)2 van der Waals dimers are suggested to explain this reaction and a series of experiments to test the hypothesized mechanisms are proposed.
In addition, a detailed account of the ultra-high-vacuum molecular beam surface scattering apparatus used for these studies is provided, including a detailed description of its operation and maintenance procedures.
Thesis Supervisor: Prof. Sylvia T. Ceyer, MIT Department of Chemistry
DW Rowlands, Michael R. Blair, Jae-Gook Lee, Robert Hefty, & Sylvia T. Ceyer. “Making F2 Heavy: Activated Etching of Si by van der Waals Molecules,” Poster at Gordon Research Conference on Dynamics at Surfaces (2013).
While both molecular fluorine (F2) and xenon difluoride (XeF2) fluorinate Si(100)2×1 surfaces at coverages up to one monolayer, fluorine is unable to cleave Si-Si bonds that ultimately leads to etching silicon at coverages above one monolayer (reaction probability 9×10–4) while XeF2 does so readily (reaction probability 0.6). Experimental work presented here demonstrate that van der Waals clusters of F2 with a Xe atom and with a Kr atom have reaction probabilities with silicon at one monolayer of fluorine coverage of roughly 0.9 and 0.04, respectively, suggesting that the effect of mass of the incident gas molecules is important in activating the cleavage of silicon-silicon bonds through a multiple collision process.
DW Rowlands. “Producing Safe Spin-Polarized Metabolites for Magnetic Resonance Imaging,” B.S. Thesis, California Institute of Technology (2009).
There is significant interest in improved sensitivity and decreased measurement times for nuclear magnetic resonance and magnetic resonance imaging of small molecules, especially those with 13C and 15N spin labels. A source of spin polarizations of order unity is spin-exchange optical pumping, which produces 129Xe with fractional polarization of order unity, about 105 higher than is achieved at equilibrium in high field.
The research presented is the development and testing of components of an apparatus intended to bring target molecules, such as acetic acid, into the close (near 1 nm) contact with hyperpolarized 129Xe atoms as needed to effect rapid equalization of their spin temperatures through dipolar couplings. Specifically, an apparatus has been designed and is being built with the intention of rapidly depositing a gaseous mixture of xenon and the target molecule as a homogeneous solid under a strong magnetic field, then dropping the field strength to allow spin equalization through dipolar couplings followed by rapid production of a liquid sample of the target molecule at room temperature.
Thesis Supervisor: Prof. Daniel P. Weitekamp, Caltech Department of Chemistry
DW Rowlands. “Analysis of Light Pollution Spectra,” High School Senior Thesis, Eleanor Roosevelt High School, Greenbelt, Maryland, (2005).
Light pollution is artificially-produced light which serves no useful purpose. It may be light directed toward places that do not need illumination or light that is directed directly into the sky. There are many different sources of light pollution. One way in which light pollution sources differ is their spectra—different light sources have different spectra and thus alter the night time sky glow in different ways. One can determine the proportions of light pollution produced by different light sources.
Spectra were taken in three directions: Baltimore, MD, Washington, DC, and Annapolis, MD. It should be noted that Laurel and Columbia, MD are in the same general direction as Baltimore and that Bowie, MD is in the same general direction as Annapolis, MD. Spectra of Washington were also taken both in the early evening andaround midnight. Lines produced by sodium, mercury, scandium, thorium, lithium, oxygen, neon, and high-pressure sodium were detected. Sodium D lines and scandium lines were stronger in Baltimore than in any other city, suggesting that low pressure sodium and metal halide lamps are more prevalent there. Mercury and sodium lines increased over the course of the night, suggesting that the proportion of the sky glow produced by mercury vapor and high pressure sodium lamps increases over the course ofthe night. This study showed that the breakdown of light pollution spectra does changeover the course of a night and that different cities do produce different sky glow spectra.
Thesis Supervisor: Dr. Ronald J. Oliverson, NASA-Goddard Space Flight Center