scholarly journals Social interactions, residential segregation and the dynamics of tipping

2021 ◽  
Author(s):  
Trevor Kollmann ◽  
Simone Marsiglio ◽  
Sandy Suardi ◽  
Marco Tolotti
Keyword(s):  
Social Interactions ◽  
Residential Segregation ◽  
Ethnic Composition ◽  
Policy Implications ◽  
Dynamics Model ◽  
Net Benefit ◽  
Exogenous Shocks ◽  
Population Dynamics Model ◽  
Migration Flows

AbstractWe develop an analytically tractable population dynamics model of heterogeneous agents to characterize how social interactions within a neighborhood determine the dynamic evolution of its ethnic composition. We characterize the conditions under which integration or segregation will occur, which depends on the majority’s social externality parameter and net benefit from leaving, and the minority’s leaving probability. Minority segregation may result from the process of tipping, which may arise from three possible channels: two are related to exogenous shocks (migration flows and changes in tipping points) and one is related to the endogenous probabilistic features of our framework (endogenous polarization). This characterization of integration and segregation conditions yields interesting policy implications for social and urban planning policies to mitigate segregation.

scholarly journals A random effects population dynamics model based on proportions-at-age and removal data for estimating total mortality

2012 ◽  
Vol 69 (11) ◽  
pp. 1881-1893 ◽  
Author(s):  
Verena M. Trenkel ◽  
Mark V. Bravington ◽  
Pascal Lorance
Keyword(s):  
Population Dynamics ◽  
Random Effects ◽  
Fixed Effects ◽  
Random Effect ◽  
Total Mortality ◽  
Estimation Bias ◽  
Effective Sample Size ◽  
Dynamics Model ◽  
Population Dynamics Model ◽  
Study Parameter

Catch curves are widely used to estimate total mortality for exploited marine populations. The usual population dynamics model assumes constant recruitment across years and constant total mortality. We extend this to include annual recruitment and annual total mortality. Recruitment is treated as an uncorrelated random effect, while total mortality is modelled by a random walk. Data requirements are minimal as only proportions-at-age and total catches are needed. We obtain the effective sample size for aggregated proportion-at-age data based on fitting Dirichlet-multinomial distributions to the raw sampling data. Parameter estimation is carried out by approximate likelihood. We use simulations to study parameter estimability and estimation bias of four model versions, including models treating mortality as fixed effects and misspecified models. All model versions were, in general, estimable, though for certain parameter values or replicate runs they were not. Relative estimation bias of final year total mortalities and depletion rates were lower for the proposed random effects model compared with the fixed effects version for total mortality. The model is demonstrated for the case of blue ling (Molva dypterygia) to the west of the British Isles for the period 1988 to 2011.

A microbial treatment population dynamics optimization approach

2021 ◽  
pp. 1-15
Author(s):  
Jinding Gao
Keyword(s):  
Population Dynamics ◽  
Information Exchange ◽  
Information Diffusion ◽  
Optimization Problems ◽  
Microbial Control ◽  
Function Optimization ◽  
Optimization Approach ◽  
Dynamics Model ◽  
Population Dynamics Model ◽  
Number Of Individuals

In order to solve some function optimization problems, Population Dynamics Optimization Algorithm under Microbial Control in Contaminated Environment (PDO-MCCE) is proposed by adopting a population dynamics model with microbial treatment in a polluted environment. In this algorithm, individuals are automatically divided into normal populations and mutant populations. The number of individuals in each category is automatically calculated and adjusted according to the population dynamics model, it solves the problem of artificially determining the number of individuals. There are 7 operators in the algorithm, they realize the information exchange between individuals the information exchange within and between populations, the information diffusion of strong individuals and the transmission of environmental information are realized to individuals, the number of individuals are increased or decreased to ensure that the algorithm has global convergence. The periodic increase of the number of individuals in the mutant population can greatly increase the probability of the search jumping out of the local optimal solution trap. In the iterative calculation, the algorithm only deals with 3/500∼1/10 of the number of individual features at a time, the time complexity is reduced greatly. In order to assess the scalability, efficiency and robustness of the proposed algorithm, the experiments have been carried out on realistic, synthetic and random benchmarks with different dimensions. The test case shows that the PDO-MCCE algorithm has better performance and is suitable for solving some optimization problems with higher dimensions.

UNDERSTANDING THE HOUSEHOLD CONSUMPTION BEHAVIOR IN URBAN CHINA

2015 ◽  
Vol 60 (05) ◽  
pp. 1550062 ◽  
Author(s):  
JIN XU ◽  
DONGMIN KONG
Keyword(s):  
Loss Aversion ◽  
Liquidity Constraints ◽  
Early Period ◽  
Urban China ◽  
Policy Implications ◽  
Consumption Pattern ◽  
Consumption Behavior ◽  
Urban Households ◽  
Province Level

Using the panel urban households’ aggregate data at the province level in China, this paper attempts to identify the source of the rejection of permanent income hypothesis (PIH) in urban households’ consumption. We introduce liquidity constraints, myopia and loss aversion into testable hypotheses and document that: First, the PIH fails in urban China and the consumption is consistent with the liquidity constraints. Second, in regions with the high and moderate economic levels, the consumption behaviors show liquidity constraints in the early period of market-oriented economic reforms (i.e., 1980s). However, with time, the consumption pattern changed to myopia. Third, in region with low economic level, the reverse is observed: a period of myopia gave way to a period of liquidity constraints. Our results suggest that neither myopia nor liquidity constraints are an adequate characterization of consumption in different regions of urban China, and offer clear policy implications for governments who are concerned with boosting the household income and expanding domestic demand.

scholarly journals Do Black Lives Matter in the American Public’s Mitigation Responses to the Covid-19 Pandemic? A Cross-Sectional Analysis of Mask Wearing and Racial/ethnic Disparities in Deaths from COVID-19 in the United States

2021 ◽  
Author(s):  
Berkeley Franz ◽  
Adrienne Milner ◽  
Jomills H. Braddock
Keyword(s):  
Public Health ◽  
Residential Segregation ◽  
Ethnic Disparities ◽  
The United States ◽  
Ethnic Composition ◽  
Cross Sectional ◽  
Public Health Challenges ◽  
History Of ◽  
Sectional Analysis ◽  
Racial Ethnic

Abstract Background: Anti-black and anti-Hispanic attitudes in the U.S. must be included in efforts to understand resistance to public health measures, such as mask wearing, during the COVID-19 pandemic. Focusing on the structural and individual context of racism will enable us to improve public health and better prepare for future public health challenges. The purpose of this study was to determine the relationship between mask usage, racial segregation, and racial disparities in COVID-19 deaths.Methods: We used linear regression to assess whether the racial/ethnic composition of deaths and residential segregation predicted Americans’ decisions to wear masks in July 2020. Results: After controlling for mask mandates, mask usage increased when the White death rates relative to Black and Hispanic rates increased. Conclusions: Mask wearing may be shaped by an insensitivity to Black and Hispanic deaths and a corresponding unwillingness to engage in health protective behaviors. The broader history of systemic racism and residential segregation may also explain why white Americans do not wear masks or perceive themselves to be at risk when communities of color are disproportionately affected by COVID-19.

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