scholarly journals Optimal Lockdown Strategies: All about Time

2021 ◽  
Author(s):  
Anagh Pathak ◽  
Varun Madan Mohan ◽  
Arpan Banerjee
Keyword(s):  
Large Scale ◽  
Economic Cost ◽  
Mitigation Strategies ◽  
Disease Spread ◽  
Small Scale ◽  
Mass Model ◽  
Agent Based ◽  
Effective Reduction ◽  
Limiting Case ◽  
Infection Spread

Abstract Lockdowns are disease mitigation strategies that aim to contain the spread of an infection by restricting the interactions of its carriers. Lockdowns can thus have a considerable economic cost, which makes the identification of optimal lockdown windows that minimize both infection spread and economic disruption imperative. A well-known feature of complex dynamical systems is their sensitivity to the timing of external inputs. Hence, we hypothesized that the timing and duration of lockdowns should dictate lockdown outcomes. We demonstrate this concept computationally from two perspectives - Firstly, a stochastic "small-scale" Agent Based Model (ABM) of a Susceptible-Infected-Recovered (SIR) disease spread and secondly, a deterministic "large-scale" perspective using a multi-group SIR mass model with parameters determined from the SARS-CoV2 data in India. Lockdowns were implemented as an effective reduction of interaction probabilities in both models. This allowed us to evaluate the parametric variations of lockdown intensity and duration onto the dynamical properties of the infection spread over different connection topologies. We definitively show that the lockdown outcomes in both the stochastic small-scale and deterministic large-scale perspectives depend sensitively on the timing of its imposition and that it is possible to minimize lockdown duration while limiting case loads to numbers below hospitalization thresholds.

scholarly journals Finite Symmetries in Agent-Based Epidemic Models

2019 ◽  
Vol 24 (2) ◽  
pp. 44 ◽  
Author(s):  
Gilberto M. Nakamura ◽  
Ana Carolina P. Monteiro ◽  
George C. Cardoso ◽  
Alexandre S. Martinez
Keyword(s):  
Population Size ◽  
Transition Matrix ◽  
Large Scale ◽  
Initial Conditions ◽  
Disease Outbreaks ◽  
Epidemic Models ◽  
Small Scale ◽  
Stochastic Effects ◽  
Agent Based ◽  
Computational Performance

Predictive analysis of epidemics often depends on the initial conditions of the outbreak, the structure of the afflicted population, and population size. However, disease outbreaks are subjected to fluctuations that may shape the spreading process. Agent-based epidemic models mitigate the issue by using a transition matrix which replicates stochastic effects observed in real epidemics. They have met considerable numerical success to simulate small scale epidemics. The problem grows exponentially with population size, reducing the usability of agent-based models for large scale epidemics. Here, we present an algorithm that explores permutation symmetries to enhance the computational performance of agent-based epidemic models. Our findings bound the stochastic process to a single eigenvalue sector, scaling down the dimension of the transition matrix to o ( N 2 ) .

scholarly journals Epidemic Spreading in Urban Areas Using Agent-Based Transportation Models

2019 ◽  
Vol 11 (4) ◽  
pp. 92 ◽  
Author(s):  
Jürgen Hackl ◽  
Thibaut Dubernet
Keyword(s):  
Urban Areas ◽  
Large Scale ◽  
Human Mobility ◽  
Urban Setting ◽  
Disease Spread ◽  
Model Parameters ◽  
Epidemic Spreading ◽  
Agent Based ◽  
Spread Model ◽  
Spread Dynamics

Human mobility is a key element in the understanding of epidemic spreading. Thus, correctly modeling and quantifying human mobility is critical for studying large-scale spatial transmission of infectious diseases and improving epidemic control. In this study, a large-scale agent-based transport simulation (MATSim) is linked with a generic epidemic spread model to simulate the spread of communicable diseases in an urban environment. The use of an agent-based model allows reproduction of the real-world behavior of individuals’ daily path in an urban setting and allows the capture of interactions among them, in the form of a spatial-temporal social network. This model is used to study seasonal influenza outbreaks in the metropolitan area of Zurich, Switzerland. The observations of the agent-based models are compared with results from classical SIR models. The model presented is a prototype that can be used to analyze multiple scenarios in the case of a disease spread at an urban scale, considering variations of different model parameters settings. The results of this simulation can help to improve comprehension of the disease spread dynamics and to take better steps towards the prevention and control of an epidemic.

scholarly journals Discovering the opposite shore: How did hominins cross sea straits?

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0252885
Author(s):  
Ericson Hölzchen ◽  
Christine Hertler ◽  
Ana Mateos ◽  
Jesús Rodríguez ◽  
Jan Ole Berndt ◽  
...  
Keyword(s):  
Large Scale ◽  
Scale Effects ◽  
Small Scale ◽  
Behavioral Models ◽  
Comprehensive Understanding ◽  
Agent Based ◽  
Continental Scale ◽  
Water Barrier ◽  
Sea Straits ◽  
Scale Models

Understanding hominin expansions requires the comprehension of movement processes at different scales. In many models of hominin expansion these processes are viewed as being determined by large-scale effects, such as changes in climate and vegetation spanning continents and thousands or even millions of years. However, these large-scale patterns of expansions also need to be considered as possibly resulting from the accumulation of small-scale decisions of individual hominins. Moving on a continental scale may for instance involve crossing a water barrier. We present a generalized agent-based model for simulating the crossing of a water barrier where the agents represent the hominin individuals. The model can be configured to represent a variety of movement modes across water. Here, we compare four different behavioral scenarios in conjunction with a set of water barrier configurations, in which agents move in water by either paddling, drifting, swimming or rafting. We introduce the crossing-success-rate (CSR) to quantify the performance in water crossing. Our study suggests that more focus should be directed towards the exploration of behavioral models for hominins, as directionality may be a more powerful factor for crossing a barrier than environmental opportunities alone. A prerequisite for this is to perceive the opposite shore. Furthermore, to provide a comprehensive understanding of hominin expansions, the CSR allows for the integration of results obtained from small-scale simulations into large-scale models for hominin expansion.

scholarly journals Estimating cost-benefit of quarantine length for COVID-19 mitigation

2020 ◽  
Author(s):  
Andreas Eilersen ◽  
Kim Sneppen
Keyword(s):  
Short Duration ◽  
Disease Transmission ◽  
Social Groups ◽  
Cost Benefit ◽  
Relative Effect ◽  
Mitigation Strategies ◽  
Disease Spread ◽  
Social Contacts ◽  
Agent Based ◽  
The Cost

ABSTRACTBackgroundThe international community has been put in an unprecedented situation by the COVID-19 pandemic. Creating models to describe and quantify alternative mitigation strategies becomes increasingly urgent.MethodsIn this study, we propose an agent-based model of disease transmission in a society divided into closely connected families, workplaces, and social groups. This allows us to discuss mitigation strategies, including targeted quarantine measures.ResultsWe find that workplace and more diffuse social contacts are roughly equally important to disease spread, and that an effective lockdown must target both. We examine the cost-benefit of replacing a lockdown with tracing and quarantining contacts of the infected. Quarantine can contribute substantially to mitigation, even if it has short duration and is done within households. When reopening society, testing and quarantining is a strategy that is much cheaper in terms of lost workdays than a long lockdown of workplaces.ConclusionsA targeted quarantine strategy is quite efficient with only 5 days of quarantine, and its relative effect increases when supplemented with other measures that reduce disease transmission.

AN AGENT-BASED MODEL OF HUMAN DISPERSALS AT A GLOBAL SCALE

2013 ◽  
Vol 16 (04n05) ◽  
pp. 1350023 ◽  
Author(s):  
SIMONE CALLEGARI ◽  
JOHN DAVID WEISSMANN ◽  
NATALIE TKACHENKO ◽  
WESLEY P. PETERSEN ◽  
GEORGE LAKE ◽  
...  
Keyword(s):  
Population Dynamics ◽  
High Performance ◽  
Large Scale ◽  
Global Scale ◽  
Small Scale ◽  
Emergent Properties ◽  
Agent Based ◽  
Human Dispersal ◽  
Model Hierarchy ◽  
Empirical Context

In this paper, we report on the theoretical foundations, empirical context and technical implementation of an agent-based modeling (ABM) framework, that uses a high-performance computing (HPC) approach to investigate human population dynamics on a global scale, and on evolutionary time scales. The ABM-HPC framework provides an in silico testbed to explore how short-term/small-scale patterns of individual human behavior and long-term/large-scale patterns of environmental change act together to influence human dispersal, survival and extinction scenarios. These topics are currently at the center of the Neanderthal debate, i.e., the question why Neanderthals died out during the Late Pleistocene, while modern humans dispersed over the entire globe. To tackle this and similar questions, simulations typically adopt one of two opposing approaches, top-down (equation-based) and bottom-up (agent-based) models of population dynamics. We propose HPC technology as an essential computational tool to bridge the gap between these approaches. Using the numerical simulation of worldwide human dispersals as an example, we show that integrating different levels of model hierarchy into an ABM-HPC simulation framework provides new insights into emergent properties of the model, and into the potential and limitations of agent-based versus continuum models.

Electrorheological Dampers, Part II: Testing and Modeling

1996 ◽  
Vol 63 (3) ◽  
pp. 676-682 ◽  
Author(s):  
H. P. Gavin ◽  
R. D. Hanson ◽  
F. E. Filisko
Keyword(s):  
Steady Flow ◽  
Electric Fields ◽  
Curve Fitting ◽  
Material Properties ◽  
Large Scale ◽  
Modeling Technique ◽  
Small Scale ◽  
Multiple Dimensions ◽  
Strong Electric Fields ◽  
Limiting Case

Electrorheological (ER) materials develop yield stresses on the order of 5–10 kPa in the presence of strong electric fields. Viscoelastic and yielding material properties can be modulated within milli-seconds. An analysis of flowing ER materials in the limiting case of fully developed steady flow results in simple approximations for use in design. Small-scale experiments show that these design equations can be applied to designing devices in which the flow is unsteady. More exact models of ER device behavior can be determined using curve-fitting techniques in multiple dimensions. A previously known curve-fitting technique is extended to deal with variable electric fields. Experiments are described which illustrate the potential for ER devices in large-scale damping applications and the accuracy of the modeling technique.

scholarly journals Cost–benefit of limited isolation and testing in COVID-19 mitigation

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Andreas Eilersen ◽  
Kim Sneppen
Keyword(s):  
Short Duration ◽  
Disease Transmission ◽  
Social Groups ◽  
Cost Benefit ◽  
Mitigation Strategies ◽  
Disease Spread ◽  
Agent Based Model ◽  
Social Contacts ◽  
Agent Based ◽  
The Cost

Abstract The international community has been put in an unprecedented situation by the COVID-19 pandemic. Creating models to describe and quantify alternative mitigation strategies becomes increasingly urgent. In this study, we propose an agent-based model of disease transmission in a society divided into closely connected families, workplaces, and social groups. This allows us to discuss mitigation strategies, including targeted quarantine measures. We find that workplace and more diffuse social contacts are roughly equally important to disease spread, and that an effective lockdown must target both. We examine the cost–benefit of replacing a lockdown with tracing and quarantining contacts of the infected. Quarantine can contribute substantially to mitigation, even if it has short duration and is done within households. When reopening society, testing and quarantining is a strategy that is much cheaper in terms of lost workdays than a long lockdown. A targeted quarantine strategy is quite efficient with only 5 days of quarantine, and its effect increases when testing is more widespread.

scholarly journals MARKET DIMENSIONALITY AND THE PROLIFERATION OF SMALL-SCALE FIRMS

2008 ◽  
Vol 11 (02) ◽  
pp. 231-247 ◽  
Author(s):  
CÉSAR GARCÍA-DÍAZ ◽  
ARJEN VAN WITTELOOSTUIJN ◽  
GÁBOR PÉLI
Keyword(s):  
Product Differentiation ◽  
Price Discrimination ◽  
Product Space ◽  
Large Scale ◽  
Small Degree ◽  
High Dimensionality ◽  
Small Scale ◽  
Two Dimensional ◽  
Agent Based ◽  
Alternative Approach

We build an agent-based computational model to study how the changing number of active product variants in a two-dimensional product space affects the performance of different firm types (i.e. large-scale and small-scale enterprises). We use an alternative approach to measure product space dimensionality, considering that dimensions may be a fraction of the Euclidean measure. The results confirm that high dimensionality gives advantage to small-scale firms. Additionally, we find that large-scale firms may also benefit from initial increasing dimensionality, since it allows a small degree of product differentiation and price discrimination.

scholarly journals Original Research Article Financial Risk Threshold Determination in Broiler Enterprise in Delta State, Nigeria

2013 ◽  
Vol 46 (4) ◽  
pp. 111-117 ◽  
Author(s):  
Felix Odemero Achoja
Keyword(s):  
Linear Programming ◽  
Financial Risk ◽  
Large Scale ◽  
Threshold Model ◽  
Mitigation Strategies ◽  
Series Data ◽  
Small Scale ◽  
Original Research ◽  
Poultry Industry ◽  
Risk Threshold

Abstract Increasing concern about the problem of risk associated with poultry business has highlighted the need for its comprehensive understanding. A clear knowledge of financial risk in broiler enterprise will pave the way to efficient mitigation strategies among broiler producers. This study investigates financial risk programming, and threshold analysis in broiler enterprises in Delta State, Nigeria. Probabilistic (multi-stage) sampling procedure was adopted in selecting 200 broiler farmers for the study. Structured questionnaire was used to collect 6 years time series data (2004-2009) from the respondents. Collected data were analyzed using descriptive statistics, QSB version of linear programming model, and threshold model. The results of the study showed that broiler enterprise is profitable with optimum net profit of N47,925 and N357,558 per small scale and large scale producers, respectively. An optimum profit of N389.9 per bird was earned by broiler producers. The output of QSB version of linear programming showed that at the stocking rate of 20, 692 birds, financial risk is optimized at 15%. The threshold regression model revealed that the broiler enterprise in the study area generally operated below the risk threshold. Simple regression indicated that expected return is positively and significantly (P < 0.05) related with financial risk. Incorporating financial risk as a constraint in the broiler farm plan is a useful contribution that will enhance efficient farm planning. The optimal return and financial risk threshold provided in this study will improve the confidence level of stakeholders in poultry industry such as current and potential investors, insurance institution and institutional lenders. This will translate to growth in the broiler subsector of the poultry industry in Delta State

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