scholarly journals How disease risk awareness modulates transmission: coupling infectious disease models with behavioural dynamics

2022 ◽  
Vol 9 (1) ◽  
Author(s):  
Jaime Cascante-Vega ◽  
Samuel Torres-Florez ◽  
Juan Cordovez ◽  
Mauricio Santos-Vega
Keyword(s):  
Steady State ◽  
Disease Risk ◽  
Mechanistic Model ◽  
Transmission Dynamics ◽  
Sis Model ◽  
Final Fraction ◽  
Adaptive Behaviours ◽  
Parameter Dependent ◽  
Behavioural Dynamics ◽  
Theory Framework

Epidemiological models often assume that individuals do not change their behaviour or that those aspects are implicitly incorporated in parameters in the models. Typically, these assumptions are included in the contact rate between infectious and susceptible individuals. However, adaptive behaviours are expected to emerge and play an important role in the transmission dynamics across populations. Here, we propose a theoretical framework to couple transmission dynamics with behavioural dynamics due to infection awareness. We modelled the dynamics of social behaviour using a game theory framework, which is then coupled with an epidemiological model that captures the disease dynamics by assuming that individuals are aware of the actual epidemiological state to reduce their contacts. Results from the mechanistic model show that as individuals increase their awareness, the steady-state value of the final fraction of infected individuals in a susceptible-infected-susceptible (SIS) model decreases. We also incorporate theoretical contact networks, having the awareness parameter dependent on global or local contacts. Results show that even when individuals increase their awareness of the disease, the spatial structure itself defines the steady state.

scholarly journals How disease risk awareness modulates transmission: coupling infectious disease models with behavioral dynamics

2021 ◽  
Author(s):  
Jaime Cascante-Vega ◽  
Samuel Torres-Florez ◽  
Juan Cordovez ◽  
Mauricio Santos-Vega
Keyword(s):  
Steady State ◽  
Disease Risk ◽  
Mechanistic Modeling ◽  
Transmission Dynamics ◽  
Epidemiological Models ◽  
Response Dynamics ◽  
Modeling Framework ◽  
Sis Model ◽  
Behavioral Dynamics ◽  
General Terms

Epidemiological models often assume that individuals do not change their behavior or that those aspects are implicitly incorporated in parameters in the models. Typically these assumption is included in the contact rate between infectious and susceptible individuals. For example models incorporate time variable contact rates to account for the effect of behavior or other interventions than in general terms reduce transmission. However, adaptive behaviors are expected to emerge and to play an important role in the transmission dynamics across populations. Here, we propose a theoretical framework to couple transmission dynamics with behavioral dynamics due to infection awareness. We first model the dynamics of social behavior by using a game theory framework. Then we coupled the model with an epidemiological model that captures the disease dynamics by assuming that individuals are more aware of that epidemiological state (i.e. fraction of infected individuals) and reduces their contacts. Our results from a mechanistic modeling framework show that as individuals increase their awareness the steady-state value of the final fraction of infected individuals in a susceptible-infected-susceptible (SIS) model decreases. We also extend our results to a spatial framework, incorporating a spatially-defined theoretical contact network (social network) and we made the awareness parameter dependent on a global or local contact structure. Our results show that even when individuals increase their awareness of the disease, the spatial structure itself defines the steady state solution of the system, in which more connected networks (networks with random or constant degree distributions) results in a population with no change in their behavior. Our work then shows that explicitly incorporating dynamics about the behavioral response dynamics might significantly change the predicted course of the epidemic and therefore highlights the importance of accounting for this source of variation in the epidemiological models.

The top-heavy shape of authoritarian bureaucracy: evidence from Russia and China

2021 ◽  
pp. 002085232110588
Author(s):  
Tao Li ◽  
Zhenyu M. Wang
Keyword(s):  
Steady State ◽  
Soviet Union ◽  
Rent Seeking ◽  
Tournament Theory ◽  
The Soviet Union ◽  
Long Run ◽  
Public Sector Reforms ◽  
Micro Level ◽  
Heavy Structure ◽  
Theory Framework

The prevalence of top-heavy bureaucracies in non-democracies cannot be explained by the theories of Parkinson, Tullock, Niskanen, or Simon or by classical managerial theories. When bureaucracy positions carry rents, the competition for promotion becomes a rent-seeking process. Borrowing the career-tournament theory framework from managerial scholarship, we argue that top-heavy bureaucracy resembles a tournament with too many finalists. When rent is centralized at the top (i.e. power centralization), as is the case in many non-democracies, the optimal bureaucracy should be top-heavy, accommodating and encouraging relatively more finalists at the top to compete for the final big prize. We provide suggestive evidence by analyzing ministry organizations in China (1993–2014) and Russia (2002–2015). After some fluctuations, the shape of Russian ministries eventually converged with that of China. In the steady state, their ministry shapes are far more top-heavy than what is prescribed by managerial theories. At the micro-level, ministry power centralization, measured by the perceived influence of the ministers, is correlated with ministry top-heaviness in Russia. Points for practitioners Our theory suggests that a top-heavy authoritarian bureaucratic structure naturally follows from a back-loaded sequential career tournament and an effort-maximizing bureaucratic leader. Our findings also suggest that Chinese and Russian ministries both converge to a highly top-heavy structure in the long run. We demonstrate that the top-heavy structure first arose during the planned-economy experiment in the Soviet Union. Our research sheds new light on public-sector reforms that aim to reduce bureaucracy top-heaviness in autocracies.

scholarly journals LYMESIM 2.0: An Updated Simulation of Blacklegged Tick (Acari: Ixodidae) Population Dynamics and Enzootic Transmission of Borrelia burgdorferi (Spirochaetales: Spirochaetaceae)

2020 ◽  
Vol 57 (3) ◽  
pp. 715-727 ◽  
Author(s):  
Holly Gaff ◽  
Rebecca J Eisen ◽  
Lars Eisen ◽  
Robyn Nadolny ◽  
Jenna Bjork ◽  
...  
Keyword(s):  
New York ◽  
Borrelia Burgdorferi ◽  
Mechanistic Model ◽  
The United States ◽  
Sensu Stricto ◽  
Tick Control ◽  
Pathogen Transmission ◽  
Transmission Dynamics ◽  
Complex Nature ◽  
Tick Population

Abstract Lyme disease is the most commonly reported vector-borne disease in the United States, and the number of cases reported each year continues to rise. The complex nature of the relationships between the pathogen (Borrelia burgdorferi sensu stricto), the tick vector (Ixodes scapularis Say), multiple vertebrate hosts, and numerous environmental factors creates challenges for understanding and predicting tick population and pathogen transmission dynamics. LYMESIM is a mechanistic model developed in the late 1990s to simulate the life-history of I. scapularis and transmission dynamics of B. burgdorferi s.s. Here we present LYMESIM 2.0, a modernized version of LYMESIM, that includes several modifications to enhance the biological realism of the model and to generate outcomes that are more readily measured under field conditions. The model is tested for three geographically distinct locations in New York, Minnesota, and Virginia. Model-simulated timing and densities of questing nymphs, infected nymphs, and abundances of nymphs feeding on hosts are consistent with field observations and reports for these locations. Sensitivity analysis highlighted the importance of temperature in host finding for the density of nymphs, the importance of transmission from small mammals to ticks on the density of infected nymphs, and temperature-related tick survival for both density of nymphs and infected nymphs. A key challenge for accurate modeling of these metrics is the need for regionally representative inputs for host populations and their fluctuations. LYMESIM 2.0 is a useful public health tool that downstream can be used to evaluate tick control interventions and can be adapted for other ticks and pathogens.

Active vibration control of a blade element with uncertainty modeling in PZT actuator force

2019 ◽  
Vol 25 (21-22) ◽  
pp. 2721-2732
Author(s):  
Selim Sivrioglu ◽  
Fevzi Cakmak Bolat ◽  
Ercan Erturk
Keyword(s):  
Steady State ◽  
Active Vibration Control ◽  
State Space Model ◽  
Uncertainty Modeling ◽  
Aerodynamic Load ◽  
Mixed Norm ◽  
Multi Objective ◽  
Dependent Part ◽  
Parameter Dependent ◽  
Blade Element

The aim of this research is to attenuate the vibrations of a blade structure with an attached piezoelectric actuator using robust multi-objective control. The force obtained from a piezoelectric patch loading has uncertainties due to the complicated shape (airfoil) of the blade element. A parameter-dependent model of the force equation is developed to understand the possible variation range of the actuation force. The modal analysis of the blade is performed to find vibration mode frequencies, and an aerodynamic load is generated experimentally to create steady-state vibration on the blade. A state-space model is obtained by considering certain vibration modes and the parameter-dependent part of the force in the input vector is taken outside of the plant model. The robust stability filter is modified with parameter dependency to have a cluster of the filter. Two different multi-objective controllers are designed with different design objectives. The designed controllers are implemented in experiments and performances of the controllers are compared using frequency and time domain responses. It is shown that the flexible blade vibrations are successfully suppressed with the proposed mixed norm robust controllers under the effect of steady-state aerodynamic disturbance with different air speeds. It is observed in experimental results that the performances of the [Formula: see text] controller are better than the [Formula: see text] controller.

Low-Dimensional Modeling of Transient Two-Phase Flow in Pipelines

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
Amine Meziou ◽  
Majdi Chaari ◽  
Matthew Franchek ◽  
Rafik Borji ◽  
Karolos Grigoriadis ◽  
...  
Keyword(s):  
Steady State ◽  
Multiphase Flow ◽  
Transmission Line ◽  
Transmission Lines ◽  
Mechanistic Model ◽  
Phase Flow ◽  
Liquid Holdup ◽  
Two Phase ◽  
Low Dimensional ◽  
State Pressure

Presented are reduced-order models of one-dimensional transient two-phase gas–liquid flow in pipelines. The proposed model is comprised of a steady-state multiphase flow mechanistic model in series with a transient single-phase flow model in transmission lines. The steady-state model used in our formulation is a multiphase flow mechanistic model. This model captures the steady-state pressure drop and liquid holdup estimation for all pipe inclinations. Our implementation of this model will be validated against the Stanford University multiphase flow database. The transient portion of our model is based on a transmission line modal model. The model parameters are realized by developing equivalent fluid properties that are a function of the steady-state pressure gradient and liquid holdup identified through the mechanistic model. The model ability to reproduce the dynamics of multiphase flow in pipes is evaluated upon comparison to olga, a commercial multiphase flow dynamic code, using different gas volume fractions (GVF). The two models show a good agreement of the steady-state response and the frequency of oscillation indicating a similar estimation of the transmission line natural frequency. However, they present a discrepancy in the overshoot values and the settling time due to a difference in the calculated damping ratio. The utility of the developed low-dimensional model is the reduced computational burden of estimating transient multiphase flow in transmission lines, thereby enabling real-time estimation of pressure and flow rate.

scholarly journals Mechanisms of blood homeostasis: lineage tracking and a neutral model of cell populations in rhesus macaque

2015 ◽  
Author(s):  
Sidhartha Goyal ◽  
Sanggu Kim ◽  
Irvin S. Y. Chen ◽  
Tom Chou
Keyword(s):  
Steady State ◽  
Size Distribution ◽  
Peripheral Blood ◽  
Viral Vector ◽  
Rhesus Macaques ◽  
Mechanistic Model ◽  
Neutral Theory ◽  
Intrinsic Variability ◽  
Clone Size ◽  
Hematopoietic Stem

How a potentially diverse population of hematopoietic stem cells (HSCs) differentiates and proliferates to supply more than 1011mature blood cells every day in humans remains a key biological question. We investigated this process by quantitatively analyzing the clonal structure of peripheral blood that is generated by a population of transplanted lentivirus-marked HSCs in myeloablated rhesus macaques. Each transplanted HSC generates a clonal lineage of cells in the peripheral blood that is then detected and quantified through deep sequencing of the viral vector integration sites (VIS) common within each lineage. This approach allowed us to observe, over a period of 4-12 years, hundreds of distinct clonal lineages. Surprisingly, while the distinct clone sizes varied by three orders of magnitude, we found that collectively, they form a steady-state clone size-distribution with a distinctive shape. Our concise model shows that slow HSC differentiation followed by fast progenitor growth is responsible for the observed broad clone size distribution. Although all cells are assumed to be statistically identical, analogous to a neutral theory for the different clone lineages, our mathematical approach captures the intrinsic variability in the times to HSC differentiation after transplantation. Steady-state solutions of our model show that the predicted clone size-distribution is sensitive to only two combinations of parameters. By fitting the measured clone size-distributions to our mechanistic model, we estimate both the effective HSC differentiation rate and the number of active HSCs.

scholarly journals Mass balance, grade, and adjustment timescales in bedrock channels

2020 ◽  
Vol 8 (1) ◽  
pp. 103-122 ◽  
Author(s):  
Jens Martin Turowski
Keyword(s):  
Steady State ◽  
Mass Balance ◽  
Mechanistic Model ◽  
Channel Width ◽  
Bedrock Rivers ◽  
Channel Incision ◽  
Bedrock Channel ◽  
Lateral Incision ◽  
Lateral Erosion ◽  
Bedrock Channels

Abstract. Rivers are dynamical systems that are thought to evolve towards a steady-state configuration. Then, geomorphic parameters, such as channel width and slope, are constant over time. In the mathematical description of the system, the steady state corresponds to a fixed point in the dynamic equations in which all time derivatives are equal to zero. In alluvial rivers, steady state is characterized by grade. This can be expressed as a so-called order principle: an alluvial river evolves to achieve a state in which sediment transport is constant along the river channel and is equal to transport capacity everywhere. In bedrock rivers, steady state is thought to be achieved with a balance between channel incision and uplift. The corresponding order principle is the following: a bedrock river evolves to achieve a vertical bedrock incision rate that is equal to the uplift rate or base-level lowering rate. In the present work, considerations of process physics and of the mass balance of a bedrock channel are used to argue that bedrock rivers evolve to achieve both grade and a balance between channel incision and uplift. As such, bedrock channels are governed by two order principles. As a consequence, the recognition of a steady state with respect to one of them does not necessarily imply an overall steady state. For further discussion of the bedrock channel evolution towards a steady state, expressions for adjustment timescales are sought. For this, a mechanistic model for lateral erosion of bedrock channels is developed, which allows one to obtain analytical solutions for the adjustment timescales for the morphological variables of channel width, channel bed slope, and alluvial bed cover. The adjustment timescale to achieve steady cover is of the order of minutes to days, while the adjustment timescales for width and slope are of the order of thousands of years. Thus, cover is adjusted quickly in response to a change in boundary conditions to achieve a graded state. The resulting change in vertical and lateral incision rates triggers a slow adjustment of width and slope, which in turn affects bed cover. As a result of these feedbacks, it can be expected that a bedrock channel is close to a graded state most of the time, even when it is transiently adjusting its bedrock channel morphology.

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