Fast and robust generation of city scale urban ground plan

Since the introduction of the concept of Digital Earth, almost every major international city has been re-constructed in the virtual world. A large volume of geometric models describing urban objects has become freely available in public domain via software like Google Earth. Although mostly created for visualization, these urban models can benefit many applications beyond visualization including video games, city scale evacuation plan, traffic simulation and earth phenomenon simulations. However, these urban models are mostly loosely structured and implicitly defined and require tedious manual preparation that usually take weeks if not months before they can be used. In this paper, we present a framework that produces well-defined ground plans from these urban models, an important step in the preparation process. Designing algorithms that can robustly and efficiently handle unstructured urban models at city scale is the main technical challenge. In this work, we show both theoretically and empirically that our method is resolution complete, efficient and numerically stable. Based on our review of the related work, we believe this is the first work that attempts to create urban ground plans automatically from 3D architectural meshes at city level. With the goal of providing greater benefit beyond visualization from this large volume of urban models, our initial results are encouraging.published_or_final_versio

Gut-dependent inflammation and alterations of the intestinal microbiota in individuals with perinatal HIV exposure and different HIV serostatus

Objective: HIV-exposed infected (HEI) and uninfected (HEU) children represent the two possible outcomes of maternal HIV infection. Modifications of the intestinal microbiome have been linked to clinical vulnerability in both settings, yet whether HEI and HEU differ in terms of gut impairment and peripheral inflammation/activation is unknown. Design: We performed a cross-sectional, pilot study on fecal and plasma microbiome as well as plasma markers of gut damage, microbial translocation, inflammation and immune activation in HIV-infected and uninfected children born from an HIV-infected mother. Methods: Fecal and plasma microbiome were determined by means of 16S rDNA amplification with subsequent qPCR quantification. Plasma markers were quantified via ELISA. Results: Forty-seven HEI and 33 HEU children were consecutively enrolled. The two groups displayed differences in fecal beta-diversity and relative abundance, yet similar microbiome profiles in plasma as well as comparable gut damage and microbial translocation. In contrast, monocyte activation (sCD14) and systemic inflammation (IL-6) were significantly higher in HEI than HEU. Conclusion: In the setting of perinatal HIV infection, enduring immune activation and inflammation do not appear to be linked to alterations within the gut. Given that markers of activation and inflammation are independent predictors of HIV disease progression, future studies are needed to understand the underlying mechanisms of such processes and elaborate adjuvant therapies to reduce the clinical risk in individuals with perinatal HIV infection

Grassroots Agency: Participation and Conflict in Buenos Aires Shantytowns seen through the Pilot Plan for Villa 7 (1971–1975)

open access articleIn 1971, after more than a decade of national and municipal policies aimed at the top-down removal of shantytowns, the Buenos Aires City Council approved the Plan Piloto para la Relocalización de Villa 7 (Pilot Plan for the Relocation of Shantytown 7; 1971–1975, referred to as the Pilot Plan hereinafter). This particular plan, which resulted in the construction of the housing complex, Barrio Justo Suárez, endures in the collective memory of Argentines as a landmark project regarding grassroots participation in state housing initiatives addressed at shantytowns. Emerging from a context of a housing shortage for the growing urban poor and intense popular mobilizations during the transition to democracy, the authors of the Pilot Plan sought to empower shantytown residents in novel ways by: 1) maintaining the shantytown’s location as opposed to eradication schemes that relocated the residents elsewhere, 2) formally employing some of the residents for the stage of construction, as opposed to “self-help” housing projects in which the residents contributed with unpaid labor, and 3) including them in the urban and architectural design of the of the new housing. This paper will examine the context in which the Pilot Plan was conceived of as a way of re-assessing the roles of the state, the user, and housing-related professionals, often seen as antagonistic. The paper argues that residents’ fair participation and state intervention in housing schemes are not necessarily incompatible, and can function in specific social and political contexts through multiactor proposals backed by a political will that prioritizes grassroots agency

Detailed Simulations of Atmospheric Flow and Dispersion in Urban Downtown Areas by Computational Fluid Dynamics (CFD) Models - An Application of Five CFD Models to Manhattan

Computational Fluid Dynamics (CFD) model simulations of urban boundary layers have improved so that they are useful in many types of flow and dispersion analyses. The study described here is intended to assist in planning emergency response activities related to releases of chemical or biological agents into the atmosphere in large cities such as New York City. Five CFD models (CFD-Urban, FLACS, FEM3MP, FEFLO-Urban, and Fluent-Urban) have been applied by five independent groups to the same 3-D building data and geographic domain in Manhattan, using approximately the same wind input conditions. Wind flow observations are available from the Madison Square Garden March 2005 (MSG05) field experiment. It is seen from the many side-by-side comparison plots that the CFD models simulations of near-surface wind fields generally agree with each other and with field observations, within typical atmospheric uncertainties of a factor of two. The qualitative results shown here suggest, for example, that transport of a release at street level in a large city could reach a few blocks in the upwind and crosswind directions. There are still key differences seen among the models for certain parts of the domain. Further quantitative examinations of differences among the models and the observations are necessary to understand causal relationships

Transport and dispersion simulation in downtown Oklahoma City and New York City

In this video, we showcase two atmospheric dispersion simulations in an Oklahoma City dataset and a New York City (NYC) dataset. These simulations are created using a robust and efficient framework that generates seamless 3D architectural models from overlapping 2D footprints. These footprints with elevation and height information are commonly used to depict various components of buildings in GIS software such as ESRI ArcGIS and urban model synthesis methods, and usually contain small, sharp, and various (nearly) degenerate artifacts due to machine and human errors. In the first part of the video showing a simulation in Oklahoma City, the location is south of the public library in an area where there is a building currently. Two iso-surfaces of 10-4 and 10-5 ppm are shown in green and the brown clouds. The inflow is a westerly wind with a wind speed of 5 m/s at 10 meters above ground level. In the second part of the video showing a simulation in NYC, the location is the Financial District, Manhattan. The simulation assumed a boundary condition for the inflow of a logarithmic profile of 2 m/s with a velocity at 10 meters from the ground. An iso-surface of 10-5 ppm is shown. The final volume mesh produce contains 333 million tetrahedra, and 59 million points. The total time of the NYC simulation, including the initialization time and dispersion, took approximately two days on a high performance computing system running 2048 cores in a CRAY XK6 nodes. In both simulations, the release is continuous.link_to_subscribed_fulltex

City-scale urban transport and dispersion simulation using geographic information system footprints

A large volume of urban models describing urban objects in major international cities has been re-constructed and become freely and publicly available via software like Arc-Globe and Google Earth. However, these models are mostly created for visualization and are loosely structured. For example, current GIS software such as ESRI ArcGIS and urban model synthesis methods typically use overlapping 2D footprints with elevation and height information to depict various components of buildings. In this paper, we present a robust and efficient framework that generates seamless 3D architectural models from these footprints that usually contain small, sharp, and various (nearly) degenerate artifacts due to machine and human errors. We demonstrate the benefits of the proposed method by showcase an atmospheric dispersion simulation in a New York City (NYC) dataset. Finally, we discuss several examples of visualizing and analyzing the simulated Computational Fluid Dynamics (CFD) data into the GIS for further geospatial analysis.link_to_subscribed_fulltex