Critical Housing Finance Challenges for Policy Makers

Examines barriers for mortgage lending to underserved groups and in distressed neighborhoods, such as risk assessment; financing for multifamily rental markets, such as affordability; and financing for sustainable housing, such as transactional costs

Homeownership Gaps Among Low-Income and Minority Households

Although homeownership rates currently stand at historically high levels for all segments of the U.S. population, large gaps in homeownership rates remain when comparing various groups of the population. As of the third quarter of 2006, the non-Hispanic White (hereafter, White) homeownership rate was 76 percent while African-American and Hispanic homeownership rates were below 50 percent and the Asian homeownership rate was 60 percent. The homeownership gap between African-American and White households was larger in 2006 than it was in 1990, while the homeownership gap between Hispanics and Whites was only slightly smaller in 2006 than it was in 1990. Households with very low incomes had a homeownership rate that was 37 percentage points below the rate for high-income households. These gaps have changed little over the past 50 years. The primary goal of this study is to synthesize what is known about the determinants of gaps in homeownership rates by income status and racial and ethnic status. We first present a conceptual framework for analyzing the determinants of homeownership. We then review the literature that identifies the relative importance of various contributing factors to observed homeownership gaps, separating the factors into those that are observed and those that are part of an unexplained residual that represents unmeasured factors such as discrimination, lack of information about the homebuying and mortgage financing processes, and omitted socioeconomic variables

Capillary pinning and blunting of immiscible gravity currents in porous media

Gravity-driven flows in the subsurface have attracted recent interest in the context of geological carbon dioxide (CO2) storage, where supercritical CO2 is captured from the flue gas of power plants and injected underground into deep saline aquifers. After injection, the CO2 will spread and migrate as a buoyant gravity current relative to the denser, ambient brine. Although the CO2 and the brine are immiscible, the impact of capillarity on CO2 spreading and migration is poorly understood. We previously studied the early time evolution of an immiscible gravity current, showing that capillary pressure hysteresis pins a portion of the macroscopic fluid-fluid interface and that this can eventually stop the flow. Here we study the full lifetime of such a gravity current. Using tabletop experiments in packings of glass beads, we show that the horizontal extent of the pinned region grows with time and that this is ultimately responsible for limiting the migration of the current to a finite distance. We also find that capillarity blunts the leading edge of the current, which contributes to further limiting the migration distance. Using experiments in etched micromodels, we show that the thickness of the blunted nose is controlled by the distribution of pore-throat sizes and the strength of capillarity relative to buoyancy. We develop a theoretical model that captures the evolution of immiscible gravity currents and predicts the maximum migration distance. By applying this model to representative aquifers, we show that capillary pinning and blunting can exert an important control on gravity currents in the context of geological CO2 storage

Stokes at 200: A celebration of the remarkable achievements of Sir George Gabriel Stokes two hundred years after his birth

Sir George Gabriel Stokes PRS was for 30 years an inimitable Secretary of the Royal Society and its President from 1885 to 1890. Two hundred years after his birth, Stokes is a towering figure in physics and applied mathematics; fluids, asymptotics, optics, acoustics among many other fields. At the Stokes200 meeting, held at Pembroke College, Cambridge from 15-18th September 2019, an invited audience of about 100 discussed the state of the art in all the modern research fields that have sprung from his work in physics and mathematics, along with the history of how we have got from Stokes' contributions to where we are now. This theme issue is based on work presented at the Stokes200 meeting. In bringing together people whose work today is based upon Stokes' own, we aim to emphasize his influence and legacy at 200 to the community as a whole. This article is part of the theme issue 'Stokes at 200 (Part 1)'

Stokes at 200 (part 2)

We present the second half of the papers from the Stokes200 symposium celebrating the bicentenary of George Gabriel Stokes. This article is part of the theme issue 'Stokes at 200 (part 2)'

Hydrogen Production From catalytic reforming of greenhouse gases (CO2 and CH4) Over Neodymiun (III) oxide supported Cobalt catalyst

Hydrogen production from CO2 reforming of methane over 20wt%.Co/Nd2O3 has been investigated in a fixed bed stainless steel reactor. The 20wt%.Co/Nd2O3 catalyst was synthesized using wet impregnation method and characterized for thermal stability, textural property, crystallinity, morphology and nature of chemical bonds using techniques such as TGA, XRD, N2 adsorption-desorption, FESEM, EDX and FTIR. The CO2 reforming of methane was performed at feed ratio (CH4:CO2) between 0.1-1 and reaction temperature ranged 973-1023 K. The catalyst displayed good activity towards selectivity and yield of hydrogen as well as CO, a by product. The selectivity and yield of Hydrogen increases with feed ratio and reaction temperature. The 20wt%.Co/Nd2O3 catalyst displayed promising catalytic activity for hydrogen production with the highest yield and selectivity of 32.5% and 17.6% respectively.Keywords: Cobalt; Greenhouse gases; Hydrogen; Reforming;; Neodymium (III)Oxid

Origin of two-band chorus in the radiation belt of Earth.

Naturally occurring chorus emissions are a class of electromagnetic waves found in the space environments of the Earth and other magnetized planets. They play an essential role in accelerating high-energy electrons forming the hazardous radiation belt environment. Chorus typically occurs in two distinct frequency bands separated by a gap. The origin of this two-band structure remains a 50-year old question. Here we report, using NASA's Van Allen Probe measurements, that banded chorus waves are commonly accompanied by two separate anisotropic electron components. Using numerical simulations, we show that the initially excited single-band chorus waves alter the electron distribution immediately via Landau resonance, and suppress the electron anisotropy at medium energies. This naturally divides the electron anisotropy into a low and a high energy components which excite the upper-band and lower-band chorus waves, respectively. This mechanism may also apply to the generation of chorus waves in other magnetized planetary magnetospheres

Modelling intrusions through quiescent and moving ambients

Volcanic eruptions commonly produce buoyant ash-laden plumes that rise through the stratified atmosphere. On reaching their level of neutral buoyancy, these plumes cease rising and transition to horizontally spreading intrusions. Such intrusions occur widely in density-stratified fluid environments, and in this paper we develop a shallow-layer model that governs their motion. We couple this dynamical model to a model for particle transport and sedimentation, to predict both the time-dependent distribution of ash within volcanic intrusions and the flux of ash that falls towards the ground. In an otherwise quiescent atmosphere, the intrusions spread axisymmetrically. We find that the buoyancy-inertial scalings previously identified for continuously supplied axisymmetric intrusions are not realised by solutions of the governing equations. By calculating asymptotic solutions to our model we show that the flow is not self-similar, but is instead time-dependent only in a narrow region at the front of the intrusion. This non-self-similar behaviour results in the radius of the intrusion growing with time \textrm3/4$, rather than \textrm2/3$ as suggested previously. We also identify a transition to drag-dominated flow, which is described by a similarity solution with radial growth now proportional to \textrm5/9$ . In the presence of an ambient wind, intrusions are not axisymmetric. Instead, they are predominantly advected downstream, while at the same time spreading laterally and thinning vertically due to persistent buoyancy forces. We show that close to the source, this lateral spreading is in a buoyancy-inertial regime, whereas far downwind, the horizontal buoyancy forces that drive the spreading are balanced by drag. Our results emphasise the important role of buoyancy-driven spreading, even at large distances from the source, in the formation of the flowing thin horizontally extensive layers of ash that form in the atmosphere as a result of volcanic eruptions

Keratinocyte-specific deletion of SHARPIN induces atopic dermatitis-like inflammation in mice.

Spontaneous mutations in the SHANK-associated RH domain interacting protein (Sharpin) resulted in a severe autoinflammatory type of chronic proliferative dermatitis, inflammation in other organs, and lymphoid organ defects. To determine whether cell-type restricted loss of Sharpin causes similar lesions, a conditional null mutant was created. Ubiquitously expressing cre-recombinase recapitulated the phenotype seen in spontaneous mutant mice. Limiting expression to keratinocytes (using a Krt14-cre) induced a chronic eosinophilic dermatitis, but no inflammation in other organs or lymphoid organ defects. The dermatitis was associated with a markedly increased concentration of serum IgE and IL18. Crosses with S100a4-cre resulted in milder skin lesions and moderate to severe arthritis. This conditional null mutant will enable more detailed studies on the role of SHARPIN in regulating NFkB and inflammation, while the Krt14-Sharpin-/- provides a new model to study atopic dermatitis