10,706 research outputs found
Gentrification and Neighborhood Housing Cycles: Will America’s Future Downtowns Be Rich?
This paper identifies a new factor, the age of the housing stock, that affects where high- and low-income neighborhoods are located in U.S. cities. High-income households, driven by a high demand for housing services, will tend to locate in areas of the city where the housing stock is relatively young. Because cities develop and redevelop from the center outward over time, the location of these neighborhoods varies over the city’s history. The model predicts a suburban location for the rich in an initial period, when young dwellings are found only in the suburbs, while predicting eventual gentrification once central redevelopment creates a young downtown housing stock. Empirical work indicates that if the influence of spatial variation in dwelling ages were eliminated, longstanding central city/suburban disparities in neighborhood economic status would be reduced by up to 50 percent. Model estimates further predict that between 2000 and 2020, central-city/suburban differences in economic status will widen somewhat in smaller cities but narrow sharply in the largest American cities as they become more gentrified.
Gentrification and Neighborhood Housing Cycles: Will America's Future Downtowns be Rich?
This paper identifies a new factor, the age of the housing stock, that affects where high- and low-income neighborhoods are located in U.S. cities. High-income households, driven by a high demand for housing services, will tend to locate in areas of the city where the housing stock is relatively young. Because cities develop and redevelop from the center outward over time, the location of these neighborhoods varies over the city’s history. The model predicts a suburban location for the rich in an initial period, when young dwellings are found only in the suburbs, while predicting eventual gentrification once central redevelopment creates a young downtown housing stock. Empirical work indicates that if the influence of spatial variation in dwelling ages were eliminated, longstanding central city/suburban disparities in neighborhood economic status would be reduced by up to 50 percent. Model estimates further predict that between 2000 and 2020, central-city/suburban differences in economic status will widen somewhat in smaller cities but narrow sharply in the largest American cities as they become more gentrified.spatial expansion of cities, housing cycles, urban expansion
Interactions of technology and society: Impacts of improved airtransport. A study of airports at the grass roots
The feasibility of applying a particular conception of technology and social change to specific examples of technological development was investigated. The social and economic effects of improved airport capabilities on rural communities were examined. Factors which led to the successful implementation of a plan to construct sixty small airports in Ohio are explored and implications derived for forming public policies, evaluating air transportation development, and assessing technology
Regularization of second-order scalar perturbation produced by a point-particle with a nonlinear coupling
Accurate calculation of the motion of a compact object in a background
spacetime induced by a supermassive black hole is required for the future
detection of such binary systems by the gravitational-wave detector LISA.
Reaching the desired accuracy requires calculation of the second-order
gravitational perturbations produced by the compact object. At the point
particle limit the second-order gravitational perturbation equations turn out
to have highly singular source terms, for which the standard retarded solutions
diverge. Here we study a simplified scalar toy-model in which a point particle
induces a nonlinear scalar field in a given curved spacetime. The corresponding
second-order scalar perturbation equation in this model is found to have a
similar singular source term, and therefore its standard retarded solutions
diverge. We develop a regularization method for constructing well-defined
causal solutions for this equation. Notably these solutions differ from the
standard retarded solutions, which are ill-defined in this case.Comment: 14 page
Smooth Inequalities and Equilibrium Inefficiency in Scheduling Games
We study coordination mechanisms for Scheduling Games (with unrelated
machines). In these games, each job represents a player, who needs to choose a
machine for its execution, and intends to complete earliest possible. Our goal
is to design scheduling policies that always admit a pure Nash equilibrium and
guarantee a small price of anarchy for the l_k-norm social cost --- the
objective balances overall quality of service and fairness. We consider
policies with different amount of knowledge about jobs: non-clairvoyant,
strongly-local and local. The analysis relies on the smooth argument together
with adequate inequalities, called smooth inequalities. With this unified
framework, we are able to prove the following results.
First, we study the inefficiency in l_k-norm social costs of a strongly-local
policy SPT and a non-clairvoyant policy EQUI. We show that the price of anarchy
of policy SPT is O(k). We also prove a lower bound of Omega(k/log k) for all
deterministic, non-preemptive, strongly-local and non-waiting policies
(non-waiting policies produce schedules without idle times). These results
ensure that SPT is close to optimal with respect to the class of l_k-norm
social costs. Moreover, we prove that the non-clairvoyant policy EQUI has price
of anarchy O(2^k).
Second, we consider the makespan (l_infty-norm) social cost by making
connection within the l_k-norm functions. We revisit some local policies and
provide simpler, unified proofs from the framework's point of view. With the
highlight of the approach, we derive a local policy Balance. This policy
guarantees a price of anarchy of O(log m), which makes it the currently best
known policy among the anonymous local policies that always admit a pure Nash
equilibrium.Comment: 25 pages, 1 figur
Determine the Potential Drill Utilization Improvements and Rock Fragmentation Requirements Using Directional Drilling in a Coal Mining Overburden Highwall Application
This project analyzed the efficiency of incorporating the use of directional drilling technology into coal overburden blasting. Directional drilling is currently in use in the petroleum industry and it is believed that it will be a valuable asset in the mining industry. This project has shown that directional drilling can be a viable technology for use in the coal overburden removal process resulting in increased drill utilization and potential for cost savings. Future work regarding blasting and geotechnical evaluation should be performed to solidify the concept
Gentrification and Neighborhood Housing Cycles: Will America\u27s Future Downtowns be Rich?
This paper identifies a new factor, the age of the housing stock, that affects where high- and low-income neighborhoods are located in U.S. cities. High-income households, driven by a high demand for housing services, will tend to locate in areas of the city where the housing stock is relatively young. Because cities develop and redevelop from the center outward over time, the location of these neighborhoods varies over the city\u27s history. The model predicts a suburban location for the rich in an initial period, when young dwellings are found only in the suburbs, while predicting eventual gentrification once central redevelopment creates a young downtown housing stock. Empirical work indicates that if the influence of spatial variation in dwelling ages were eliminated, longstanding central city/suburban disparities in neighborhood economic status would be reduced by up to 50 percent. Model estimates further predict that between 2000 and 2020, central-city/suburban differences in economic status will widen somewhat in smaller cities but narrow sharply in the largest American cities as they become more gentrified
On the Bergman representative coordinates
We study the set where the so-called Bergman representative coordinates (or
Bergman functions) form an immersion. We provide an estimate of the size of a
maximal geodesic ball with respect to the Bergman metric, contained in this
set. By concrete examples we show that these estimates are the best possible.Comment: 20 page
Developing new smallpox vaccines.
New stockpiles of smallpox vaccine are required as a contingency for protecting civilian and military personnel against deliberate dissemination of smallpox virus by terrorists or unfriendly governments. The smallpox vaccine in the current stockpile consists of a live animal poxvirus (Vaccinia virus [VACV]) that was grown on the skin of calves. Because of potential issues with controlling this earlier manufacturing process, which included scraping VACV lesions from calfskin, new vaccines are being developed and manufactured by using viral propagation on well-characterized cell substrates. We describe, from a regulatory perspective, the various strains of VACV, the adverse events associated with calf lymph-propagated smallpox vaccine, the issues regarding selection and use of cell substrates for vaccine production, and the issues involved in demonstrating evidence of safety and efficacy
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