104 research outputs found
Individual, Family, and Neighborhood Characteristics and Children\u27s Food Insecurity
A growing body of work documents the influence of neighborhood environments on child health and well-being. Food insecurity is likely linked to neighborhood characteristics via mechanisms of social disadvantage, including access to and availability of healthy foods and the social cohesion of neighbors. In this paper, we utilize restricted, geo-coded data from the Early Childhood Longitudinal Study, which allows us to link individual children with their neighborhood\u27s census characteristics, to assess how the neighborhoods of food secure and food insecure children differ at both the kindergarten level and in third grade. The average food insecure child lives in a neighborhood with a higher proportion of black and Hispanic residents, a higher proportion of residents living in poverty, and a higher proportion of foreign-born and linguistically isolated residents. After accounting for individual and household-level characteristics, children living in neighborhoods with a high proportion of Hispanic and foreign-born residents have a significantly increased risk of food insecurity compared to children living in neighborhoods which are predominantly white and have high socioeconomic status. We argue that interventions which take neighborhood context into account may be most efficacious for curbing child food insecurity
Improved coastal boundary condition for surface water waves
Abstract Surface water waves in coastal waters are commonly modeled using the mild slope equation. One of the parameters in the coastal boundary condition for this equation is the direction at which waves approach a coast. Three published methods of estimating this direction are examined, and it is demonstrated that the wave fields obtained using these estimates deviate significantly from the corresponding analytic solution. A new method of estimating the direction of approaching waves is presented and it is shown that this method correctly reproduces the analytic solution. The ability of these methods to simulate waves in a rectangular harbor is examined
A massively parallel GPU-accelerated model for analysis of fully nonlinear free surface waves
Hybridizable discontinuous Galerkin p-adaptivity for wave problems
A p-adaptive Hybridizable Discontinuous Galerkin (HDG) method is presented for the solution of wave problems.
The HDG method allows to drastically reduce the coupled degrees of freedom of the computation seeking for an approximation of
the solution that is defined only on the edges of the mesh. The particular choice of the numerical fluxes driven by the hybridization
technique allows to obtain an optimally converging solution not only for the primal unknown but also for its derivative. This
characteristic allows to perform a post-process of the solution that provides a super-convergent solution.
The discontinuous character of the solution provides an optimal framework for a p-adaptive technique. The post-processed solution
of the HDG method is used to construct a cheap and reliable error estimator that drives an element by element modification
of the approximation degree.
The proposed p-adaptive HDG method is compared with high-order CG computation with static condensation of the interior
nodes. A challenging problem is considered for the comparison: a non-homogeneous scattering problem in an open domain.Peer ReviewedPostprint (published version
DG-FEM solution for nonlinear wave-structure interaction using Boussinesq-type equations
We present a high-order nodal Discontinuous Galerkin Finite Element Method (DG-FEM) solution based on a set of highly accurate Boussinesq-type equations for solving general water-wave problems in complex geometries. A nodal DG-FEM is used for the spatial discretization to solve the Boussinesq equations in complex and curvilinear geometries which amends the application range of previous numerical models that have been based on structured Cartesian grids. The Boussinesq method provides the basis for the accurate description of fully nonlinear and dispersive water waves in both shallow and deep waters within the breaking limit. To demonstrate the current applicability of the model both linear and mildly nonlinear test cases are considered in two horizontal dimensions where the water waves interact with bottom-mounted fully reflecting structures. It is established that, by simple symmetry considerations combined with a mirror principle, it is possible to impose weak slip boundary conditions for both structured and general curvilinear wall boundaries while maintaining the accuracy of the scheme. As is standard for current high-order Boussinesq-type models, arbitrary waves can be generated and absorbed in the interior of the computational domain using a flexible relaxation technique applied on the free surface variables. (c) 2007 Elsevier B.V. All rights reserved
Biofouling by Saccostrea cucullata - a major threat to mangroves of Vasishthi Estuary, Maharashtra
1155-1161Present work reports heavy biofouling by Saccostrea cucullata on mangroves of the Vasishthi Estuary. High heavy metal concentrations in the estuary could be the cause of proliferation of these oyster species. Field observations suggest physiological impairment of mangroves due to oyster biofouling, damaging their capacity to accrue sediments. Thus, biofouling by S. cucullata is not only a major threat to the mangrove forests in the Vasishthi Estuary, but also to the tidal flats which are a haven for diverse benthic community, organic carbon sinks and natural adsorbents of pollutants
Sundaas Story: A Mixed-Methods Study of Household Sanitation Provisioning in Urban Informal Housing in India
The aims of this research were to examine sanitation insecurity in urban informal housing through the lens of the built environment, social disparities, and health implications. While the Millennium Development Goals for halving the global proportion of people without access to safe drinking water were met ahead of schedule, progress fell short for sanitation, creating new objectives for the Sustainable Development Goals to be met in 2030. Much research in the Global South is dedicated to community-level sanitation promotion, but often presumes a rural rather than urban setting. Urban informal housing settings constitute a unique challenge due to the range of population sizes, tenure uncertainty, and location on potentially hazardous landscapes. In addition, while social scientific work theorizes the relationship between urban planning priorities and infrastructure inequalities, less work focuses on the social and environmental dynamics that shape sanitation within poor communities.
Using quantitative, qualitative, and spatial data analyses, I examine: 1) whether demand for a household toilet is associated with the built environment; 2) socio-spatial processes that are enmeshed in daily sanitation decision-making among women householders; and 3) whether women’s defecation and urination avoidance strategies (“holding it”) correspond to the availability of a household toilet as opposed to shared facilities. The research occurred through a partnership with an NGO that has been engaged in sanitation and housing in urban slums in Maharashtra, India for more than two decades.
In synthesizing results, I argue that sanitation demand must be understood through daily sanitation journeys, which are enmeshed within social inequalities, ambiguity over shared infrastructure, and housing insecurity. These themes are shaped by the social and built environment. First, household size, home ownership, individual household water sources, and open defecation avoidance are significantly associated with sanitation demand. Second, intra-community tensions play a major role in the lack of clarity over management of shared water and sanitation infrastructure. This, alongside gender imbalances and fear of violence, shape how women seek out daily sanitation, particularly around where and when to go to the bathroom. Toilets also present the potential for formalization and upward mobility for residents, but housing insecurity and the threat of eviction complicate the decision to build a toilet. Finally, the provision of a household toilet corresponds to a major reduction in avoidance behaviors among female primary respondents. Respondents who report community toilets as unsafe are much more likely to engage in bathroom avoidance behavior, especially if their household is water-insecure.
These findings have bearings for research and policy regarding sanitation and poor urban populations. First, I shed new light on sanitation and gender inequity, especially the issue of women routinely avoiding defecation, a practice whose health implications have not been studied. Secondly, my findings suggest that sanitation promotion activities that approach the community as a single unit that will work together to solve open defecation and to manage shared facilities whose management is unclear may not be successful. Thirdly, housing insecurity constitutes a major site of tension for residents of informal settlements, and planning priorities must engage with housing insecurity alongside the provision of sanitation infrastructure overall
Peak flow estimation by method of maximum likehood: Technical memorandum HLO 2, March 1962
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