Modelling collective foraging by means of individual behaviour rules in honey-bees

An individual-oriented model is constructed which simulates the collective foraging behaviour of a colony of honey-bees, Apis mellifera. Each bee follows the same set of behavioural rules. Each rule consists of a set of conditions followed by the behavioural act to be performed if the conditions are fulfilled. The set of conditions comprises the state of external information available to the bee (e.g. the dancing of other bees) and internal information variables (like memorised location of a food source and homing motivation). The rules are partly observational (i.e. they capture the observable regularities between the present external information and the individual bee's behaviour), and partly involve hypothesised internal-state variables (e.g. abandoning tendency and homing motivation), because no observ- able (physiological) aspect has as yet been detected in the bee which correlates with changes in the internal moti- vation. Our aim is to obtain a set of rules that is nec- essary and sufficient for the generation of the collective foraging behaviour observed in real bees. We simulated an experiment performed by Seeley et al. in which a colony of honey-bees chooses between two nectar sources of different profitabilities which are switched at intervals. A good fit between observed and simulated collective forager patterns was obtained when the model included rules in which the bees (1) relied on the infor- mation acquired from previous fiights to a source (e.g. profitability and time of day when the source was found), (2) used positional information obtained by at- tending recruitment dances and (3) did not abandon a (temporarily) deteriorated source too fast or too slowly. The significance of the following issues is discussed: the role of internal and external information, source prof- itability, the spatial precision of the dance communica- tion, the ability to search for a source after the source position has been transmitted, the tendency to abandon a deteriorated source, and the concepts of scout, recruit, (un)employed forager, and foraging history

Symmetry breaking in collective honeybee foraging: a simulation study

Symmetry breaking is the phenomenon that the numbers of foragers exploiting two equally profitable food sources will diverge. This phenomenon has been investigated in ants [1,4,5], but hardly in honeybees. It is even not clear whether in honeybees symmetry breaking can occur [3, p.190]. We present results of an individual-oriented simulation model showing that under specific circumstances symmetry breaking in the numbers of honeybee workers exploiting two or four identical nectar sources can occur. We studied factors that influence the occurrence of symmetry breaking, which include: size of the forager pool, number of bees initially exploiting the sources, and size of the flower patch. This study is part of an ongoing study which aims at developing an individual-oriented simulation model capturing the necessary and sufficient behavioural rules to generate the collective foraging patterns observed in bee

Exploration and exploitation of food sources by social insect colonies: a revision of the scout-recruit concept

Social insect colonies need to explore and exploit multiple food sources simultaneously and efficiently. At the individual level, this colony-level behaviour has been thought to be taken care of by two types of individual: scouts that independently search for food, and recruits that are directed by nest mates to a food source. However, recent analyses show that this strict division of labour between scouts and recruits is untenable. Therefore, a modified concept is presented here that comprises the possible behavioural states of an individual forager (novice forager, scout, recruit, employed forager, unemployed experienced forager, inspector and reactivated forager) and the transitions between them. The available empirical data are reviewed in the light of both the old and the new concept, and probabilities for the different transitions are derived for the case of the honey-bee. The modified concept distinguishes three types of foragers that may be involved in the exploration behaviour of the colony: novice bees that become scouts, unemployed experienced bees that scout, and lost recruits, i.e. bees that discover a food source other than the one to which they were directed to by their nest mates. An advantage of the modified concept is that it allows for a better comparison of studies investigating the different roles performed by social insect foragers during their individual foraging histories

The new modelling method in urban development : case study in Rotterdam

Land-use transition, energy consumption, and temperature fluctuation are the three dominant topics we have investigated in this research. In the last century, 38 heat waves occurred in Europe, of which eleven were after 1900 and six after 2000 (IPCC, 2007). Local-climate changes due to urbanization are epitomized by the urban heat island (UHI), which mainly focuses on the interaction of land use and temperature. However, energy is also an important issue when we investigate the sustainable urban development. This research detects correlations between land-use transition, energy consumption, and temperature fluctuation in the Rotterdam area from 1996 till now. We use a series of maps to illustrate the relationship of temperature fluctuation and energy consumption. These two variables are linked via land-use maps. From the data set, the spatial parameters are estimated that have a significant effect on the correlation between temperature fluctuation and energy consumption. Finally we draw conclusions on the Rotterdam 2050 city scenario, taking the found spatial parameters into consideration

Measuring Regional Sustainability by a Coordinated Development Model of Economy, Society, and Environment: A Case Study of Hubei Province

AbstractRegional sustainability concerns a complex system that mainly consists of three subsystems, being the economy, society, and the environment. A complex system involves intensive interactions and correlations among its components. Therefore, the way how these components are organized to work together efficiently is of great significance to the development of a complex system. For that reason, measuring regional sustainability should not only focus on changes in each subsystem individually, but also consider the interactions and relationships among the subsystems. In this paper, we apply a modified method to assess coordinated development, which highlights the simultaneous promotions of economic grow, social well-being, and environment al conservation. By introducing the model of coordinated development, we evaluate the sustainable development of Hubei province which is a typical region in Central China. The result shows that Hubei performed poorly in coordinated development. Although the coordinated development index was consistently increasing, the speed was very slow. In a detailed analysis of the economic, societal, and environmental subsystems in Hubei, the shortage of an economic driving force was found the main cause of the poor development of Hubei Province

The new modelling method in urban development : case study in Rotterdam

Land-use transition, energy consumption, and temperature fluctuation are the three dominant topics we have investigated in this research. In the last century, 38 heat waves occurred in Europe, of which eleven were after 1900 and six after 2000 (IPCC, 2007). Local-climate changes due to urbanization are epitomized by the urban heat island (UHI), which mainly focuses on the interaction of land use and temperature. However, energy is also an important issue when we investigate the sustainable urban development. This research detects correlations between land-use transition, energy consumption, and temperature fluctuation in the Rotterdam area from 1996 till now. We use a series of maps to illustrate the relationship of temperature fluctuation and energy consumption. These two variables are linked via land-use maps. From the data set, the spatial parameters are estimated that have a significant effect on the correlation between temperature fluctuation and energy consumption. Finally we draw conclusions on the Rotterdam 2050 city scenario, taking the found spatial parameters into consideration

Land Use Spatial Optimization Using Accessibility Maps to Integrate Land Use and Transport in Urban Areas

The scarcity of urban land resources requires a well-organized spatial layout of land use to better accommodate human activities, however, as a widely accepted concept, the integration of land use and transport is not given due consideration in land use spatial optimization (LUSO). This paper aims to integrate land use and transport in LUSO to support urban land use planning. Maximizing accessibility fitness, which follows the underlying logic between land use types and transport characteristics, is introduced into multi-objective land use spatial optimization (MOLUSO) modelling to address transport considerations, together with widely-used objectives such as maximizing compactness, compatibility, and suitability. The transport characteristics, in this study, are identified by driving accessibility, cycling accessibility, and walking accessibility. Accessibility maps, which quantify and visualize the spatial variances in accessibility fitness for different land use types, are developed based on the empirical results of the relationship between land use types and transport characteristics for LUSO and addressing policy issues. The 4-objective LUSO model and a corresponding non-dominated sorting genetic algorithm (NSGA-II) based optimization method constitute a prototype decision support system (DSS) for urban land use planning. Decision-makers (e.g., planning departments) can choose an ideal solution to accommodate urban development needs from a set of Pareto-optimal alternatives generated by the DSS. The approaches to creating accessibility maps and MOLUSO modelling are demonstrated by the case study of Eindhoven, the Netherlands. This study advocates limited changes to the current land use pattern in urban planning, and the LUSO emphasizes urban renewal and upgrading rather than new town planning.</p

An experimental evaluation of the consistency of competitive ability and agonistic dominance in different social contexts in captive bonobos

Bonobos have been described as a relatively egalitarian and female dominant species. The exact nature and quality of their dominance relationships and the existence of female dominance are current topics of dispute. We investigated the consistency across social contexts, the stability in time, and the degree of expression of the competitive feeding ability and agonistic dominance in a captive group of bonobos. First, we examined whether the competitive feeding ranks and agonistic ranks differed in different dyadic contexts, triadic contexts and the whole group context. For some pairs of animals the dominance relationships with respect to competitive feeding altered with different group compositions. The agonistic dominance relationships changed accordingly. The competitive feeding ranks and agonistic ranks in the experiments correlated strongly with each other. The alpha position was occupied by a female, but not all females outranked all males. We suggest that females can profit from each others presence to gain inter-sexual dominance. Second, although the agonistic rank order in the whole group remained the same over at least five years, some dyadic competitive feeding ranks changed over time, resulting in a stronger female intersexual dominance. Third, the degree of expression of the behaviors used to quantify dyadic competitive and agonistic dominance was not high, in line with the popular egalitarian epithet. Notwithstanding its low consistency across contexts, the dominance hierarchy in the whole group has a strong predictive value for other social relationships such as grooming. Given this strong effect of rank on other behaviours and given the strong dependency of rank on social context, the choice of the right party members may be a crucial factor in the fission-fusion processes of free-ranging bonobos

The pivotal role of rank in grooming and support behaviour in a captive group of bonobos (Pan paniscus)

We investigated dyadic grooming relationships in a captive group of bonobos (Pan paniscus) and questioned what social function grooming fulfils in the market of services and favors. Hereto we examined which of two theoretical models - grooming for support (Seyfarth, 1977, 1980) or grooming according to the similarity principle (de Waal & Luttrell, 1986) - best accounted for the observed grooming distribution. Similarity in traits did not correlate with increased grooming or close proximity among the individuals. Therefore, the similarity hypothesis was rejected. Seyfarths model of rank-related grooming was largely confirmed. The animals distributed their grooming according to the rank of the receivers. We found an exchange between grooming and receipt of support. There was more grooming up than down the hierarchy. However, not all predictions about rank-related competition over grooming were confirmed. We found that dyadic grooming reciprocity indeed increased with decreasing rank distance. Yet, there was no increase of grooming within the dyad with decreasing rank distance and high ranking individuals were not competed over at the highest rates. The observed correlation between grooming and support received represents an important fit with Seyfarths prediction, but does not allow for conclusions about underlying causal processes. Other causal explanations, besides the groom to receive support hypothesis, that could explain a similar correlation are discussed

The StatCan Dialogue Dataset: Retrieving Data Tables through Conversations with Genuine Intents

We introduce the StatCan Dialogue Dataset consisting of 19,379 conversation turns between agents working at Statistics Canada and online users looking for published data tables. The conversations stem from genuine intents, are held in English or French, and lead to agents retrieving one of over 5000 complex data tables. Based on this dataset, we propose two tasks: (1) automatic retrieval of relevant tables based on a on-going conversation, and (2) automatic generation of appropriate agent responses at each turn. We investigate the difficulty of each task by establishing strong baselines. Our experiments on a temporal data split reveal that all models struggle to generalize to future conversations, as we observe a significant drop in performance across both tasks when we move from the validation to the test set. In addition, we find that response generation models struggle to decide when to return a table. Considering that the tasks pose significant challenges to existing models, we encourage the community to develop models for our task, which can be directly used to help knowledge workers find relevant tables for live chat users.Comment: Accepted at EACL 202