scholarly journals Applications of percolation theory to fungal spread with synergy

2011 ◽  
Vol 9 (70) ◽  
pp. 949-956 ◽  
Author(s):  
Jonathan J. Ludlam ◽  
Gavin J. Gibson ◽  
Wilfred Otten ◽  
Christopher A. Gilligan
Keyword(s):  
Control Strategies ◽  
Model Fitting ◽  
Structured Populations ◽  
Synergistic Interactions ◽  
Non Invasive ◽  
History Of ◽  
Disease Spreading ◽  
Strict Requirement ◽  
Using Data ◽  
The Impact

There is increasing interest in the use of the percolation paradigm to analyse and predict the progress of disease spreading in spatially structured populations of animals and plants. The wider utility of the approach has been limited, however, by several restrictive assumptions, foremost of which is a strict requirement for simple nearest-neighbour transmission, in which the disease history of an individual is influenced only by that of its neighbours. In a recent paper, the percolation paradigm has been generalized to incorporate synergistic interactions in host infectivity and susceptibility, and the impact of these interactions on the invasive dynamics of an epidemic has been demonstrated. In the current paper, we elicit evidence that such synergistic interactions may underlie transmission dynamics in real-world systems by first formulating a model for the spread of a ubiquitous parasitic and saprotrophic fungus through replicated populations of nutrient sites and subsequently fitting and testing the model using data from experimental microcosms. Using Bayesian computational methods for model fitting, we demonstrate that synergistic interactions are necessary to explain the dynamics observed in the replicate experiments. The broader implications of this work in identifying disease-control strategies that deflect epidemics from invasive to non-invasive regimes are discussed.

scholarly journals Methods to infer transmission risk factors in complex outbreak data

2011 ◽  
Vol 9 (68) ◽  
pp. 456-469 ◽  
Author(s):  
Simon Cauchemez ◽  
Neil M. Ferguson
Keyword(s):  
Risk Factors ◽  
Missing Data ◽  
Disease Transmission ◽  
Control Strategies ◽  
Model Fitting ◽  
Structured Populations ◽  
Transmission Risk ◽  
Effective Control ◽  
Reconstruction Methods ◽  
History Of

Data collected during outbreaks are essential to better understand infectious disease transmission and design effective control strategies. But analysis of such data is challenging owing to the dependency between observations that is typically observed in an outbreak and to missing data. In this paper, we discuss strategies to tackle some of the ongoing challenges in the analysis of outbreak data. We present a relatively generic statistical model for the estimation of transmission risk factors, and discuss algorithms to estimate its parameters for different levels of missing data. We look at the problem of computational times for relatively large datasets and show how they can be reduced by appropriate use of discretization, sufficient statistics and some simple assumptions on the natural history of the disease. We also discuss approaches to integrate parametric model fitting and tree reconstruction methods in coherent statistical analyses. The methods are tested on both real and simulated datasets of large outbreaks in structured populations.

scholarly journals The Efficacy of Ethnic Stacking: Military Defection during Uprisings in Africa

2019 ◽  
Vol 5 (4) ◽  
pp. 695-702 ◽  
Author(s):  
Julien Morency-Laflamme ◽  
Theodore McLauchlin
Keyword(s):  
Large Scale ◽  
Armed Forces ◽  
Future Research ◽  
Group Loyalty ◽  
Limited Support ◽  
History Of ◽  
Group Members ◽  
Using Data ◽  
The Cost ◽  
The Impact

Abstract Does ethnic stacking in the armed forces help prevent military defection? Recent research, particularly in Africa and the Middle East, suggests so; by favoring in-groups, regimes can keep in-group soldiers loyal. In-group loyalty comes at the cost of antagonizing members of out-groups, but many regimes gladly run that risk. In this research note, we provide the first large-scale evidence on the impact of ethnic stacking on the incidence of military defection during uprisings from below, using data on fifty-seven popular uprisings in Africa since formal independence. We find clear evidence for the downside: ethnic stacking is associated with more frequent defection if out-group members are still dominant in the armed forces. We find more limited support for the hypothesized payoff. Ethnic stacking may reduce the risk of defection, but only in regimes without a recent history of coup attempts. Future research should therefore trace the solidification of ethnic stacking over time.

scholarly journals Modelling rainfall with a Bartlett–Lewis process: new developments

2020 ◽  
Vol 24 (5) ◽  
pp. 2791-2815
Author(s):  
Christian Onof ◽  
Li-Pen Wang
Keyword(s):  
Model Fitting ◽  
Extreme Rainfall ◽  
Rainfall Time Series ◽  
New Developments ◽  
History Of ◽  
The Difference ◽  
Poisson Cluster ◽  
The Impact ◽  
Analytical Expressions ◽  
Structure Properties

Abstract. The use of Poisson cluster processes to model rainfall time series at a range of scales now has a history of more than 30 years. Among them, the randomised (also called modified) Bartlett–Lewis model (RBL1) is particularly popular, while a refinement of this model was proposed recently (RBL2; Kaczmarska et al., 2014). Fitting such models essentially relies upon minimising the difference between theoretical statistics of the rainfall signal and their observed estimates. The first statistics are obtained using closed form analytical expressions for statistics of the orders 1 to 3 of the rainfall depths, as well as useful approximations of the wet–dry structure properties. The second are standard estimates of these statistics for each month of the data. This paper discusses two issues that are important for the optimal model fitting of RBL1 and RBL2. The first issue is that, when revisiting the derivation of the analytical expressions for the rainfall depth moments, it appears that the space of possible parameters is wider than has been assumed in past papers. The second issue is that care must be exerted in the way monthly statistics are estimated from the data. The impact of these two issues upon both models, in particular upon the estimation of extreme rainfall depths at hourly and sub-hourly timescales, is examined using 69 years of 5 min and 105 years of 10 min rainfall data from Bochum (Germany) and Uccle (Belgium), respectively.

Fluid Tonicity Affects Peritoneal Characteristics Derived by 3-PORE Model

2019 ◽  
Vol 39 (3) ◽  
pp. 243-251 ◽  
Author(s):  
Joanna Stachowska-Pietka ◽  
Jan Poleszczuk ◽  
Josep Teixido-Planas ◽  
Josep Bonet-Sol ◽  
Maria I. Troya-Saborido ◽  
...  
Keyword(s):  
Model Fitting ◽  
Hydraulic Conductance ◽  
Membrane Properties ◽  
Patient Specific ◽  
Model Parameters ◽  
Peritoneal Membrane ◽  
Substantial Impact ◽  
Pore Model ◽  
Using Data ◽  
The Impact

Background It is typically assumed that within short time-frames, patient-specific peritoneal membrane characteristics are constant and do not depend on the initial fluid tonicity and dwell duration. The aim of this study was to check whether this assumption holds when membrane properties are estimated using the 3-pore model (3PM). Methods Thirty-two stable peritoneal dialysis (PD) patients underwent 3 8-hour peritoneal equilibration tests (PETs) with different glucose-based solutions (1.36%, 2.27%, and 3.86%). Temporary drainage was performed at 1 and 4 hours. Glucose, urea, creatinine, sodium, and phosphate concentrations were measured in dialysate and blood samples. Three-pore model parameters were estimated for each patient and each 8-hour PET separately. In addition, model parameters were estimated using data truncated to the initial 4 hours of peritoneal dwell. Results In all cases, model-estimated parameter values were within previously reported ranges. The peritoneal absorption (PA) and diffusive permeability for all solutes except sodium increased with fluid tonicity, with about 18% increase when switching from glucose 2.27% to 3.86%. Glucose peritoneal reflection coefficient and osmotic conductance (OsmCond), and fraction of hydraulic conductance for ultrasmall pores decreased with fluid tonicity (over 40% when switching from glucose 1.36%). Model fitting to the truncated 4-hour data resulted in little change in the parameters, except for PA, peritoneal hydraulic conductance, and OsmCond, for which higher values for the 4-hour dwell were found. Conclusion Initial fluid tonicity has a substantial impact on the 3PM-estimated characteristics of the peritoneal membrane, whereas the impact of dwell duration was relatively small and possibly influenced by the change in the patient's activity.

Disaggregating Mediations: The Impact of Multiparty Mediation

2011 ◽  
Vol 41 (4) ◽  
pp. 859-881 ◽  
Author(s):  
Tobias Böhmelt
Keyword(s):  
Conflict Resolution ◽  
Empirical Analysis ◽  
Third Party ◽  
Multiparty Mediation ◽  
History Of ◽  
Shared Culture ◽  
Using Data ◽  
The Impact ◽  
The Empirical Analysis ◽  
Mediation Effectiveness

This article disaggregates coalitions of third-party mediators and examines their effectiveness in interventions. First, it is argued that there is an inverted U-shaped relationship between the size of a mediating coalition and mediation effectiveness. Secondly, mediators sharing a history of conflict and distrust will transfer their past relationships to a mediation attempt, making it less effective. Consequently, states sharing friendly and co-operative ties with each other are more successful in managing conflicts. Finally, a coalition of mediators that is largely democratic should be more effective due to a shared culture of peaceful conflict resolution, inclusivity and increased communication flows. The empirical analysis using data from the Issues Correlates of War Project for 1965–2000 largely provides support for the theory.

scholarly journals Robustness of local control strategies under modelling uncertainties: the 2004 avian influenza H5N1 outbreak in Thailand

2018 ◽  
Author(s):  
Renata Retkute ◽  
Chris P. Jewell ◽  
Thomas P. Van Boeckel ◽  
Geli Zhang ◽  
Xiangming Xiao ◽  
...  
Keyword(s):  
Avian Influenza ◽  
Control Strategies ◽  
Model Fitting ◽  
Significant Risk ◽  
Disease Outbreaks ◽  
Control Policy ◽  
Poultry Industry ◽  
Epidemic Size ◽  
Hpai H5n1 ◽  
The Impact

AbstractThe Highly Pathogenic Avian Influenza (HPAI) subtype H5N1 virus persists in many countries and has been circulating in poultry, wild birds. In addition, the virus has emerged in other species and frequent zoonotic spillover events indicate that there remains a significant risk to human health. It is crucial to understand the dynamics of the disease in the poultry industry to develop a more comprehensive knowledge of the risks of transmission and to establish a better distribution of resources when implementing control. In this paper, we develop a set of mathematical models that simulate the spread of HPAI H5N1 in the poultry industry in Thailand, utilising data from the 2004 epidemic. The model that incorporates the intensity of duck farming when assessing transmision risk provides the best fit to the spatiotemporal characteristics of the observed outbreak, implying that intensive duck farming drives transmission of HPAI in Thailand. We also extend our models using a sequential model fitting approach to explore the ability of the models to be used in “real time” during novel disease outbreaks. We conclude that, whilst predictions of epidemic size are estimated poorly in the early stages of disease outbreaks, the model accurately predicts the preferred control policy that should be deployed to minimise the impact of the disease.

Origins and Implications of the Apollo 16 Breccia Noble Gas Suite

2021 ◽  
Author(s):  
Mark C. Nottingham ◽  
Natalie M. Curran ◽  
John Pernet-Fisher ◽  
Ray Burgess ◽  
Katherine H. Joy
Keyword(s):  
Solar Wind ◽  
Noble Gas ◽  
Landing Site ◽  
Soil Samples ◽  
Wide Range ◽  
Sector Mass Spectrometer ◽  
History Of ◽  
Using Data ◽  
The Impact ◽  
Solar Wind Composition

<p>The Apollo 16 landing site is dominated by regolith breccias; consolidated regolith palaeo-soils [5,7,8]. Each regolith soil (and, by extension, each regolith breccia) is composed of fragments of rock sourced from different impacts and lithological units [e.g. 2,3]. Because of this, these samples probe the impact history of the lunar surface across a wide range of time. McKay et al. (1986) reported the trapped argon isotope ratios (i.e., <sup>40</sup>Ar/<sup>36</sup>Ar<sub>Tr</sub>) values of regolith breccias and used these values to semi-quantitatively model breccia formation ages [see also 4]. Two groups of regolith breccias were identified at the Apollo 16 landing site: (i) the ‘ancient’ group, lithified immature regolith (i.e., <30 I<sub>s</sub>/FeO), and (ii) a ‘younger’ group that generally have higher levels of maturity. Joy et al. (2011) used the <sup>40</sup>Ar/<sup>36</sup>Ar<sub>Tr</sub> ratios to model that: (i) the ancient samples closed from soils to breccias between ~3.8 and 3.4 Ga, consistent with regolith developed and consolidated after the Imbrium basin-forming event, and during a time of declining basin-forming impacts, and (ii) that the young breccias were assembled in the Eratosthenian period between ~2.5 and 1.7 Ga, providing insight into post-basin bombardment impact processes.</p><p>A third set of regolith breccias identified by Jerde et al. (1987, 1990), (the soil-like breccias), have no reported noble gas or exposure age information. Joy et al. (2011) inferred that these samples were likely consolidated into breccias in the last 2 Ga (based on their I<sub>s</sub>/FeO maturity being similar to the Apollo 16 soils). They, therefore, may extend the current archive of impact and regolith processes into the Eratosthenian and Copernican periods.</p><p>Whole-rock samples were laser step heated and the extracted gases were measured using a Thermo Scientific Helix-MC noble gas magnetic sector mass spectrometer. Preliminary analysis of our data shows these breccias are dominated by a solar wind composition component, with minor spallation and radiogenic contributions. The concentrations of evolved gases suggest the samples are more similar in terms of noble gas budget to the present day Apollo 16 soil samples (based on analysis using data collated by Curran et al. 2020), than the ancient gas-poor Apollo 16 regolith breccias (McKay et al. 1986). Thus, these noble gas data are consistent with the petrological characterisation and Is/FeO classification [5,6] of these breccias being comparable to present day Apollo 16 soil samples. Solar wind composition gas concentrations comparable to present day soil samples suggest these new breccias represent consolidated regolith of comparable maturity, perhaps suggesting these soil-like breccias were formed around the same time period as the ‘younger’ group.</p><p>References: [1] Curran, N.M., et al., 2020, PSS, 182, 104823. [2] Donohue, P.H., et al., 2013, 44<sup>th</sup> LPSC, A#2897.; [3] Fagan, A.L., et al., 2013, GCA, 106, 429-445.; [4] Fagan, A.L., et al., 2014, Earth Moon Planets, 112, 59–71.; [5] Jerde, E.A., et al., 1987, J. Geophys. Res., 92(B4), E526– E536.; [6] Jerde, E.A., et al., 1990, EPSL, 98(1), 90-108.; [7] Joy, K.H., et al., 2011, GCA, 75(22), 7208-7225.; [8] McKay, D.S., et al., (1986), J. Geophys. Res., 91(B4), 277– 303.</p>

scholarly journals Modelling rainfall with a Bartlett–Lewis process: New developments

2019 ◽  
Author(s):  
Christian Onof ◽  
Li-Pen Wang
Keyword(s):  
Model Fitting ◽  
Extreme Rainfall ◽  
Rainfall Time Series ◽  
New Developments ◽  
History Of ◽  
The Difference ◽  
Poisson Cluster ◽  
The Impact ◽  
Analytical Expressions ◽  
Structure Properties

Abstract. The use of Poisson-cluster processes to model rainfall time series at a range of scales now has a history of more than 30 years. Among them, the Randomised (also called modified) Bartlett–Lewis model (RBL1) is particularly popular, while a refinement of this model was proposed recently (RBL2) (Kaczmarska et al., 2014). Fitting such models essentially relies upon minimising the difference between theoretical statistics of the rainfall signal and their observed estimates. The first are obtained using closed form analytical expressions for statistics of order 1 to 3 of the rainfall depths, as well as useful approximations of the wet-dry structure properties. The second are standard estimates of these statistics for each month of the data. This paper discusses two issues that are important for optimal model fitting of the RBL1 and RBL2. The first is that, when revisiting the derivation of the analytical expressions for the rainfall depth moments, it appears that the space of possible parameters is wider than has been assumed in the past papers. The second is that care must be exerted in the way monthly statistics are estimated from the data. The impact of these two issues upon both models, in particular upon the estimation of extreme rainfall depths at hourly and sub-hourly timescales is examined using 69 years of 5-min and 105 years of 10-min rainfall data from Bochum (Germany) and Uccle (Belgium), respectively.

scholarly journals Efecto crítico de la pandemia por covid-19 en el empleo de México

2021 ◽  
Vol 0 (128) ◽  
pp. 27-58
Author(s):  
Fidel Olivera ◽  
◽  
Guillermo Olivera ◽  
Keyword(s):  
Metropolitan Areas ◽  
Formal Employment ◽  
History Of ◽  
Monthly Changes ◽  
Three Stages ◽  
Using Data ◽  
State Size ◽  
The Impact ◽  
Social Security Institute

The cycle of formal employment during 2020, following the Covid-19 pandemic, is analyzed in three stages: paralysis with destruction, interrupted recovery, and relapse. Likewise, using data from the Mexican Social Security Institute on monthly changes to the numbers of insured workers, it was possible to identify the impact of govern-ment management, and trace the history of infection provoked by the disease, in lost or gained employment at each stage. Changes to the numbers of those in employment are illustrated by the economic sector, state, size of economic unit, salary range, sex and age group of the workers. The highest rate of unemployment was in tourism and recre-ational services, the most populous states with dense metropolitan areas, medium and large economic units, among young workers, the very young and those over 60 years old, and those with the worst wages. It is estimated that it will take at least until 2022 for the quality of work to recover and the accumulated deficit to be restored

scholarly journals Parental Alcoholism and Offspring Behavior Problems: Findings in Australian Children of Twins

2009 ◽  
Vol 12 (5) ◽  
pp. 433-440 ◽  
Author(s):  
Mary Waldron ◽  
Nicholas G. Martin ◽  
Andrew C. Heath
Keyword(s):  
Behavior Problems ◽  
Problem Behaviors ◽  
Child Behavior ◽  
Child Behavior Problems ◽  
Internalizing Behavior ◽  
Children Of Twins ◽  
History Of ◽  
Opposite Sex ◽  
Using Data ◽  
The Impact

AbstractWe examine the impact of rearing by an alcoholic parent on risk for child behavior problems using data on 2492 offspring drawn from two ongoing studies of children of female and male same- and opposite-sex twin pairs. Results of regression models predicting child behavior problems from parent and co-twin lifetime history of alcohol use disorder (AUD) provide support for genetic but not environmental transmission of externalizing and a measure of total problem behaviors. Results for internalizing behavior were inconclusive with respect to transmission of risk.

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