scholarly journals Spatial approach to analyzing dynamics of racial diversity in large U.S. cities: 1990–2000–2010

2021 ◽  
Author(s):  
Anna Dmowska ◽  
Tomasz Stepinski
Keyword(s):  
Social Change ◽  
Temporal Dynamics ◽  
Temporal Evolution ◽  
Racial Diversity ◽  
Racially Diverse ◽  
Aggregation Index ◽  
Large Cities ◽  
Spatial Approach ◽  
Spatio Temporal ◽  
Diversity Dynamics

Over the last several decades large U.S. cities became increasingly racially diverse. Understanding spatio-temporal dynamics of this significant social change and identifying its broad trends is important for numerous stakeholders. High resolution population grids, which recently become available for the entire conterminous U.S. and for three-time points from 1990 to 2010, are an ideal dataset for analyzing dynamics of racial diversity. Their value to diversity analysis has been already demonstrated at the level of the entire U.S. as well as at the level of an individual city.In this paper, we demonstrate their value for performing a survey aimed at synthesizing diversity dynamics from different cities in order to identify prevalent nationwide trends. Our survey consists of 41 large cities. 1990-2000-2010 snapshots of racial conditions at each city are provided by respective grids in which each cell is assigned one of nine possible diversity/dominant race categories. All cells with the same diversity label constitute a zone which we refer to as community and measure using a percentage of landscape (PLAND) and an aggregation index (AI) metrics. The inclusion of the AI metric makes it possible to determine not only whether a given community grows or shrinks but also whether it’s merging or fragmenting. We analyze spatio-temporal evolution of communities by tracking changes in the pairs of the values of these metrics. To simplify we categorize these changes into eight categories resulting in 64 possible change trajectories for each community. Trajectories are histogrammed to reveal the variety of scarcity of possible modes of change. Frequent trajectories are identified with broad trends. Eight such trends are identified, they represent the most prevalent racial dynamics in the U.S. during the decades of 1990-2010. Two trends correspond to the decay of whites-only and blacks-only communities. The remaining six trends correspond to the expansion of Hispanics, Asian, and racially diverse communities. Trends do not show regional dependence, they truly reflect profound social change occurring across the entire U.S.

scholarly journals Spatio-temporal Dynamics of Perfusion during Transient Focal Ischemia: Sequential Experimental PET in Cats

Stroke ◽  
2001 ◽  
Vol 32 (suppl_1) ◽  
pp. 355-355
Author(s):  
Rudolf Graf ◽  
Klaus Wienhard ◽  
Christian Dohmen ◽  
Toshiaki Fujita ◽  
Wolf-Dieter Heiss
Keyword(s):  
Temporal Dynamics ◽  
Temporal Evolution ◽  
Oxygen Metabolism ◽  
Focal Ischemia ◽  
Mca Occlusion ◽  
Positron Emission ◽  
Ischemic Episode ◽  
Spatio Temporal ◽  
Regional Dysfunction ◽  
Transient Focal Ischemia

P88 Objective: We studied the temporal evolution of regional dysfunction in transient focal ischemia using sequential positron emission tomography (PET), with special emphasis on postischemic hyperperfusion. Methods: Cerebral blood flow (CBF), oxygen metabolism (CMRO 2 ), and oxygen extraction (OEF) were repeatedly measured before and up to 24 hours after 60 min middle cerebral artery (MCA) occlusion in 16 halothane anesthetized cats. PET results were compared to final histopathologic outcome. Results: In all animals, CBF decreased in the ischemic territory below 45% of preischemic controls. Recirculation was partially successful in 3 cats, and hypoperfused regions persisted resulting in gross infarction. 3 major types of hyperperfusion evolved in the other cats: 1. In 5 cats, hyperperfusion covering large parts of the MCA territory persisted throughout the experiment. During ischemia, CBF reduction was severe, and OEF increases were restricted to the surrounding of subsequently hyperperfused regions. At the final stage, large infarcts were observed. 2. In 6 cats, hyperperfusion was transient and often followed by hypoperfusion in parts of previously hyperperfused regions. During MCA occlusion, CBF reduction was more gradual, and OEF elevations covered not only the surroundings but partially also subsequently hyperperfused zones. Infarcts were normally restricted to the center of hyperperfused regions, or did not develop. 3. In 2 cats, hyperperfused regions grew progressively over time. In this type, CBF reduction was also more gradual, OEF increases were widely distributed in the ischemic territory, and infarcts were small. Conclusion: Sequential experimental PET revealed variable spatio-temporal patterns of postischemic perfusion following transient MCAO in cats. Regions with continued hyperperfusion have a particularly bad outcome, as have those with continued incomplete recirculation. Transient postischemic hyperperfusion, however, may be beneficial in zones with subcritical CBF reduction or spontaneous partial reperfusion during the ischemic episode.

Turbulent Spatio-Temporal Dynamics in Reacting-Diffusing Systems: Results for a Soluble Model

1978 ◽  
Vol 33 (5) ◽  
pp. 588-596
Author(s):  
P. Ortoleva ◽  
M. DelleDonne
Keyword(s):  
Temporal Dynamics ◽  
Temporal Evolution ◽  
Three Dimensional ◽  
Reaction Diffusion ◽  
Type Systems ◽  
Model Systems ◽  
Dimensional Manifold ◽  
Perturbation Scheme ◽  
Diffusion Type ◽  
Spatio Temporal

A class of soluble three "species" reaction-diffusion type systems is presented Exact solutions are obtained which show turbulent spatio-temporal evolution All homogeneous evolution tends asymptotically toward an attractor which is shown to be a two layered two dimensional manifold in the three dimensional species space. Sustained aperiodic spatio-temporal solutions are also found.By considering particular model systems we show that turbulent solutions may exit as finite amplitude instabilities or as bifurcations which are aperiodic arbitrarily close to the bifurcation point and hence do not arise as a transition starting out essentially periodically.A perturbation scheme is used to show that d parameter families of spatio-temporal evolution are admitted by more general systems with attracting d dimensional manifolds in the homogeneous chemical kinetics

Spatial and temporal dynamics of Pacific capelin Mallotus catervarius in the Gulf of Alaska: implications for ecosystem-based fisheries management

2020 ◽  
Vol 637 ◽  
pp. 117-140 ◽  
Author(s):  
DW McGowan ◽  
ED Goldstein ◽  
ML Arimitsu ◽  
AL Deary ◽  
O Ormseth ◽  
...  
Keyword(s):  
Temporal Dynamics ◽  
Marine Ecosystem ◽  
Gulf Of Alaska ◽  
Data Series ◽  
Limited Information ◽  
Important Species ◽  
Multiple Data ◽  
Spatial And Temporal Dynamics ◽  
Spawning Areas ◽  
Spatio Temporal

Pacific capelin Mallotus catervarius are planktivorous small pelagic fish that serve an intermediate trophic role in marine food webs. Due to the lack of a directed fishery or monitoring of capelin in the Northeast Pacific, limited information is available on their distribution and abundance, and how spatio-temporal fluctuations in capelin density affect their availability as prey. To provide information on life history, spatial patterns, and population dynamics of capelin in the Gulf of Alaska (GOA), we modeled distributions of spawning habitat and larval dispersal, and synthesized spatially indexed data from multiple independent sources from 1996 to 2016. Potential capelin spawning areas were broadly distributed across the GOA. Models of larval drift show the GOA’s advective circulation patterns disperse capelin larvae over the continental shelf and upper slope, indicating potential connections between spawning areas and observed offshore distributions that are influenced by the location and timing of spawning. Spatial overlap in composite distributions of larval and age-1+ fish was used to identify core areas where capelin consistently occur and concentrate. Capelin primarily occupy shelf waters near the Kodiak Archipelago, and are patchily distributed across the GOA shelf and inshore waters. Interannual variations in abundance along with spatio-temporal differences in density indicate that the availability of capelin to predators and monitoring surveys is highly variable in the GOA. We demonstrate that the limitations of individual data series can be compensated for by integrating multiple data sources to monitor fluctuations in distributions and abundance trends of an ecologically important species across a large marine ecosystem.

Spatio-temporal evolution and dynamic origin of Jurassic-Cretaceous magmatism in the South China Block

2021 ◽  
Vol 217 ◽  
pp. 103605
Author(s):  
Xianzhi Cao ◽  
Nicolas Flament ◽  
Sanzhong Li ◽  
R. Dietmar Müller
Keyword(s):  
South China ◽  
Temporal Evolution ◽  
South China Block ◽  
The South ◽  
Spatio Temporal ◽  
Cretaceous Magmatism
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