4,643 research outputs found
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
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
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
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