scholarly journals Prioritised Learning in Snowdrift-Type Games

Mathematics ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1945
Author(s):  
Maria Kleshnina ◽  
Sabrina S. Streipert ◽  
Jerzy A. Filar ◽  
Krishnendu Chatterjee
Keyword(s):  
Environmental Conditions ◽  
Mathematical Description ◽  
Stable State ◽  
Strategic Choice ◽  
Free Riders ◽  
Effective Strategies ◽  
Snowdrift Game ◽  
Learning Path ◽  
Behavioural Trait ◽  
Learning Factors

Cooperation is a ubiquitous and beneficial behavioural trait despite being prone to exploitation by free-riders. Hence, cooperative populations are prone to invasions by selfish individuals. However, a population consisting of only free-riders typically does not survive. Thus, cooperators and free-riders often coexist in some proportion. An evolutionary version of a Snowdrift Game proved its efficiency in analysing this phenomenon. However, what if the system has already reached its stable state but was perturbed due to a change in environmental conditions? Then, individuals may have to re-learn their effective strategies. To address this, we consider behavioural mistakes in strategic choice execution, which we refer to as incompetence. Parametrising the propensity to make such mistakes allows for a mathematical description of learning. We compare strategies based on their relative strategic advantage relying on both fitness and learning factors. When strategies are learned at distinct rates, allowing learning according to a prescribed order is optimal. Interestingly, the strategy with the lowest strategic advantage should be learnt first if we are to optimise fitness over the learning path. Then, the differences between strategies are balanced out in order to minimise the effect of behavioural uncertainty.

scholarly journals Fragile coexistence of a global chytrid pathogen with amphibian populations is mediated by environment and demography

2017 ◽  
Vol 284 (1864) ◽  
pp. 20171444 ◽  
Author(s):  
Annemarieke Spitzen-van der Sluijs ◽  
Stefano Canessa ◽  
An Martel ◽  
Frank Pasmans
Keyword(s):  
Environmental Conditions ◽  
Batrachochytrium Dendrobatidis ◽  
Stable State ◽  
Biodiversity Loss ◽  
Environmental Mediation ◽  
Infection Dynamics ◽  
Host Pathogen ◽  
Bombina Variegata ◽  
Population Sizes ◽  
The Individual

Unravelling the multiple interacting drivers of host–pathogen coexistence is crucial in understanding how an apparently stable state of endemism may shift towards an epidemic and lead to biodiversity loss. Here, we investigate the apparent coexistence of the global amphibian pathogen Batrachochytrium dendrobatidis (Bd) with Bombina variegata populations in The Netherlands over a 7-year period. We used a multi-season mark–recapture dataset and assessed potential drivers of coexistence (individual condition, environmental mediation and demographic compensation) at the individual and population levels. We show that even in a situation with a clear cost incurred by endemic Bd, population sizes remain largely stable. Current environmental conditions and an over-dispersed pathogen load probably stabilize disease dynamics, but as higher temperatures increase infection probability, changing environmental conditions, for example a climate-change-driven rise in temperature, could unbalance the current fragile host–pathogen equilibrium. Understanding the proximate mechanisms of such environmental mediation and of site-specific differences in infection dynamics can provide vital information for mitigation actions.

COOPERATION IN THE WELL-MIXED TWO-POPULATION SNOWDRIFT GAME WITH PUNISHMENT ENFORCED THROUGH DIFFERENT MECHANISMS

2017 ◽  
Vol 20 (04n05) ◽  
pp. 1750010 ◽  
Author(s):  
ANDRÉ BARREIRA DA SILVA ROCHA
Keyword(s):  
Initial Conditions ◽  
Nonlinear Differential Equations ◽  
Pure Strategy ◽  
Stable State ◽  
Payoff Matrix ◽  
Globally Asymptotically Stable ◽  
Agent Based ◽  
Evolutionary Pattern ◽  
Snowdrift Game ◽  
Level Of Agreement

I study two mechanisms based on punishment to promote cooperation in the well-mixed two-population snowdrift game (SG). The first mechanism follows a standard approach in the literature and is based on the inclusion of a third additional pure strategy in the payoff matrix of the stage-game. Differently, the second mechanism consists of letting cooperators punish defectors with a given exogenous frequency. In the latter, the pure strategy cooperation is replaced by a mixed strategy in which cooperators randomize between cooperation and punishment against defectors. While both mechanisms share the same result regarding the minimum required level of punishment in order to eliminate defectors in both populations, stability in the mechanism following the second approach is more robust in the sense that extinction of defectors is a globally asymptotically stable state for any interior initial conditions in the phase space. Thus, the second mechanism displays a topologically simpler model but the robustness of the evolutionary equilibrium is improved. Results were obtained analytically through nonlinear differential equations and also using an agent-based simulation. There was a good level of agreement between both approaches with respect to the evolutionary pattern over time and the possible steady-states.

scholarly journals Transportation and Transformation of Arsenic Species at the Intertidal Sediment-Water Interface of Bohai Bay, China

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Xiaoping Yu ◽  
Yafei Guo ◽  
Qin Wang ◽  
Tianlong Deng
Keyword(s):  
Environmental Conditions ◽  
Intertidal Zone ◽  
Stable State ◽  
Arsenic Species ◽  
Intertidal Sediment ◽  
Bohai Bay ◽  
Diffusive Flux ◽  
Water Interface ◽  
Overlying Water ◽  
Vertical Distributions

Arsenic species including arsenite As(III), arsenate As(V), monomethylarsenate (MMA), dimethylarsenate (DMA), and some diagenetic constituents (Fe, Mn, and S2−) in porewaters along with the unstable arsenic species in sediments collected from a typical intertidal zone of Bohai Bay in China were measured. Their vertical distributions were subsequently obtained to reveal the transportation and transformation characteristics of arsenic at the intertidal sediment-water interface (SWI). Results show that the reduction of As(V) by microorganisms occurred in sediments, but the methylation of arsenic by microorganisms was weak in the intertidal zone. The distribution of As(V) was mainly controlled by Mn, whereas As(III) appeared to be more likely controlled by Fe. Arsenic in sediments mainly existed in a stable state, so that only little arsenic could be released from sediments when the environmental conditions at the SWI are changed. As(III) diffused from porewaters to the overlying water while the opposite was true for As(V) at that time when the samples were collected. The total diffusion direction for arsenic across the SWI was from porewaters to the overlying water with a total diffusive flux estimated at 1.23 mg·m−2·a−1.

scholarly journals Exploration on SPOC-based Blended Teaching Strategies in Business English Reading Course

2020 ◽  
Vol 218 ◽  
pp. 04030
Author(s):  
Jinchun Zhang ◽  
Dongshui Zhang
Keyword(s):  
Education Reform ◽  
Language Teachers ◽  
Business English ◽  
Teaching Mode ◽  
Effective Strategies ◽  
English Reading ◽  
Learning Path ◽  
Teaching Content ◽  
Teaching Concept ◽  
Blended Teaching

As the new direction of education reform in the internet era, the SPOC-based blended teaching mode has become increasingly popular in universities, because it can enrich teaching content, diversify learning path, enhance interaction between teachers and learners, and most importantly improve students’ learning enthusiasm and effectiveness. However, due to the lack of substantial knowledge and strategies on SPOC-based teaching concept as well as computer technology, many English teachers cannot conduct SPOC-based blended teaching mode well in their classes even though they have the intention to do it well. Therefore, taking business English reading course as a case study, this paper explores some effective strategies on how to apply SPOC-based blended teaching in English courses, so as to provide useful enlightenment for foreign language teachers in universities and colleges to better conduct blended teaching in their classes in the future.

scholarly journals Development of Strategies to Prevent Third Rail Insulator Failures in Transit Systems

2021 ◽  
Vol 7 (1) ◽  
pp. 58-70
Author(s):  
Behzad Rouhanizadeh ◽  
Sharareh Kermanshachi
Keyword(s):  
Case Studies ◽  
Environmental Conditions ◽  
Preventive Maintenance ◽  
Preventive Strategies ◽  
Transit Systems ◽  
Effective Strategies ◽  
Rail Systems ◽  
Transit Agencies ◽  
In Transit ◽  
Source Of Information

AbstractFailures of third rail insulators, which often impose problems that affect the serviceability of transit systems, rarely have been investigated. This study examines various aspects of third rail systems, identifies causes of insulator failures, and develops and categorizes preventive strategies. To accomplish the goals, the existing literature was reviewed and analyzed to identify various characteristics of third rails and insulators. Then, five transit case studies were analyzed to determine the characteristics of third rails, identify the causes of insulator failures, and evaluate the preventive strategies adopted by transit agencies. The results revealed that local environmental conditions cause degradation of insulators, with dirt build-up being the biggest contributor to failure. Performing maintenance and inspections of insulators at predetermined intervals was also shown to be very effective for preventing failure. The preventive strategies were classified into three categories: regular inspections; preventive maintenance programs; and regulation and safety, with regular inspections being the most frequently adopted. Findings of this study will serve as an appropriate source of information for practitioners who work with third rail systems and will help them adopt effective strategies.

A model of discontinuous change in a three-component community

1985 ◽  
Vol 224 (1234) ◽  
pp. 1-6 ◽  
Keyword(s):  
Mathematical Description ◽  
Stable State ◽  
Nutrient Supply ◽  
Algal Population ◽  
Discontinuous Change ◽  
Component Community

Through the use of a particular mathematical description a model is developed that exhibits discontinuous change. The example uses a nutrient-limited algal population grazed by herbivores, themselves the prey of fish. It shows how, under suitable conditions, a small increase in nutrient supply can totally change the stable state of this ecosystem.

scholarly journals A Further Study of Herd Mortality under Epidemic Conditions

1930 ◽  
Vol 30 (2) ◽  
pp. 240-265 ◽  
Author(s):  
M. Greenwood ◽  
E. M. Newbold ◽  
W. W. C. Topley ◽  
J. Wilson
Keyword(s):  
Environmental Conditions ◽  
Mathematical Description ◽  
Principal Factor ◽  
Physiological Age ◽  
Specific Factor ◽  
Biological Factors ◽  
Active Immunisation ◽  
Mortality Curve ◽  
Zero Line ◽  
The Difference

The results of this investigation may be summarised as follows:1. The qx or cage-age mortality curve of a herd increases rapidly to a maximum and thereafter descends to an approximately constant level which is much above the level of the qx for normal mice of ages within the range of real, physiological, age of animals living in the herds.2. At the latest ages under observation the principal factor of mortality is still the specific factor, so that the advantage produced by selective mortality and active immunisation is brought to a standstill far above the zero line. Exposure in a herd under the conditions of these experiments will not produce an ultimate population fully resistant to the specific factor of infection.3. It is probable that a large proportion, perhaps a majority, of the members of a herd become infected early in herd life, and gradually increase their degree of immunity because variations of environmental conditions, so far as these are measured by the general herd mortality, become less and less influential on the ultimate mortality of the exposed to risk the later the point in time chosen for measurement.4. Study of the form of the age-mortality curve is still proceeding; at present we cannot offer an adequate mathematical description of it which takes due account of the biological factors requiring attention.5. Quite provisionally, we attribute the difference in time of the maxima of the qx curves of Pasteurella and aertrycke epidemics to a difference of average interval between infection and death.

scholarly journals Quality of Life of the Population: Content and Specifics of the Regional Level

2021 ◽  
Vol 10 (525) ◽  
pp. 214-220
Author(s):  
M. M. Bil ◽  
Keyword(s):  
Quality Of Life ◽  
Social Services ◽  
Environmental Conditions ◽  
Stable State ◽  
Well Being ◽  
The State ◽  
Regional Level ◽  
Qualitative Assessment ◽  
Social Infrastructure

The article is aimed at developing the theoretical-applied provisions of the quality of life of the population with the identification of the specifics of assessment and provision at the regional level. Based on accounting the definitions of quality of life operated by international and government structures, domestic and foreign scholars have proposed to understand this category as an indicator of the degree of provision of the population with benefits in both the quantitative and the qualitative assessment, taking into account the environmental conditions and its stability for long-term satisfaction of material, cultural and spiritual needs. As a result of the study, the difference between the concept of quality of life and other evaluative indicators of human activity was identified, namely: standard of living, well-being, human and sustainable development. The quality of life involves the combination of both the quantitative and the qualitative assessment of the degree of provision of benefits and meeting the needs of the population, taking into account the environmental conditions and achieving a stable state along with the properties of resiliency. It is indicated the relativity of the analysis of the quality of life at different levels, and therefore the specifics of its understanding at the global level and at the levels of the State, region, community, household, person are determined. The criteria for assessing the quality of life are systematized, which allows to distinguish the specifics of its provision at the levels of the State and its regions. The main objectives of the policy of ensuring the quality of life of the population are determined in the context of creating an environment of opportunities to motivate the market environment to produce benefits, creating a competitive environment in the conditions of global mobility, ensuring stability, providing high-quality social services and developing social infrastructure. Prospect for further research is to determine the system of mechanisms of regional policy of ensuring the quality of life of the population, the formation and implementation of which in Ukraine requires scientific substantiations in the course of further decentralization.

scholarly journals Holocene and recent aeolian reactivation of the Willandra Lakes lunettes, semi-arid southeastern Australia

The Holocene ◽  
2019 ◽  
Vol 29 (4) ◽  
pp. 606-621 ◽  
Author(s):  
Kathryn E Fitzsimmons ◽  
Caroline Spry ◽  
Nicola Stern
Keyword(s):  
Indigenous People ◽  
Environmental Conditions ◽  
Human Mobility ◽  
Climatic Conditions ◽  
Effective Strategies ◽  
European Settlement ◽  
Southeastern Australia ◽  
Dry Conditions ◽  
Landscape Scales ◽  
Semi Arid

The Willandra Lakes in semi-arid southeastern Australia provide some of the most continuous combined palaeoenvironmental and archaeological records on the continent. These are best preserved within the transverse shoreline (lunette) dunes on their downwind margins. Following final lake retreat c. 15 ka avulsion of the dominant fluvial inflow eastwards, the Willandra lunettes periodically reactivated, experiencing erosion, aeolian redeposition and alluvial sheetwash. These reworked sedimentary archives reflect regional climatic conditions rather than those of the entire catchment. Yet the focus of most study in the region to date has remained on the late Pleistocene. The general paucity of Holocene data has contributed to a perception that people largely abandoned the area in favour of the perennial Murray and Darling Rivers to the south and west. Our study reconstructs past geomorphological conditions and patterns of human mobility in adjacent Lakes Mungo and Durthong over the last c. 15 ka subsequent to final lake retreat, including the most recent 150 years since Europeans established pastoralism in the region. Our data show that Indigenous people did not abandon the area as previously assumed, but developed effective strategies for responding to the changed environmental conditions. Final lake retreat transitioned into a phase of aeolian accumulation c. 15–12 ka, indicating locally dry conditions. Subsequent aeolian reactivation peaked during arid phases experiencing less rainfall in the early Holocene and twice in the most recent 1000 years prior to European settlement in the area. Alluvial sheetwash was deposited onto lake floors during the mid-Holocene, and again in the early decades of European settlement. Aeolian reactivation, likely driven by European pastoral activities, increases in the most recent 150 years. Our study underscores the necessity of integrating geomorphological and archaeological investigations over landscape scales in order to optimise our understanding of interactions between people and their environment through time.

Vibration Isolator System for Electron Microscope

1990 ◽  
Vol 48 (1) ◽  
pp. 182-183
Author(s):  
K. Ohi ◽  
M. Mizuno ◽  
T. Kasai ◽  
Y. Ohkura ◽  
K. Mizuno ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Magnetic Fields ◽  
Environmental Conditions ◽  
Vibration Isolator ◽  
Air Conditioners ◽  
Vibration Isolators ◽  
Large Size ◽  
Electron Microscopes

In recent years, with electron microscopes coming into wider use, their installation environments do not necessarily give their performance full play. Their environmental conditions include air-conditioners, magnetic fields, and vibrations. We report a jointly developed entirely new vibration isolator which is effective against the vibrations transmitted from the floor.Conventionally, large-sized vibration isolators which need the digging of a pit have been used. These vibration isolators, however, are large present problems of installation and maintenance because of their large-size.Thus, we intended to make a vibration isolator which1) eliminates the need for changing the installation room2) eliminates the need of maintenance and3) are compact in size and easily installable.

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