19,554 research outputs found
Modelling Australian Domestic and International Inbound Travel: a Spatial-Temporal Approach
In this paper Australian domestic and international inbound travel are modelled by an anisotropic dynamic spatial lag panel Origin-Destination (OD) travel flow model. Spatial OD travel flow models have traditionally been applied in a single cross-sectional context, where the spatial structure is assumed to have reached its long run equilibrium and temporal dynamics are not explicitly considered. On the other hand, spatial effects are rarely accounted for in traditional tourism demand modelling. We attempt to address this dichotomy between spatial modelling and time series modelling in tourism research by using a spatial-temporal model. In particular, tourism behaviour is modelled as travel flows between regions. Temporal dependencies are accounted for via the inclusion of autoregressive components, while spatial autocorrelations are explicitly accounted for at both the origin and the destination. We allow the strength of spatial autocorrelation to exhibit seasonal variations, and we allow for the possibility of asymmetry between capital-city neighbours and non-capital-city neighbours. Significant spatial dynamics have been uncovered, which lead to some interesting policy implications.Tourism demand, Dynamic panel models, Travel flow model.
Spatial econometric methods for modeling origin destination flows
Spatial interaction models of the gravity type are used in conjunction with sample
data on flows between origin and destination locations to analyse international and
interregional trade, commodity, migration and commuting patterns. The focus is
on the classical log-normal model version and spatial econometric extensions that
have recently appeared in the literature. These new models replace the conventional
assumption of independence between origin-destination flows with formal
approaches that allow for spatial dependence in flow magnitudes. The paper also
discusses problems that arise in applied practice when estimating (log-normal)
spatial interaction models. (authors' abstract
Knowledge Spillovers across Europe. Evidence from a Poisson Spatial Interaction Model with Spatial Effects
This paper investigates the impact of knowledge capital stocks on total
factor productivity through the lens of the knowledge capital model proposed by
Griliches (1979), augmented with a spatially discounted cross-region knowledge
spillover pool variable. The objective is to shift attention from firms and
industries to regions and to estimate the impact of cross-region knowledge
spillovers on total factor productivity (TFP) in Europe. The dependent variable is
the region-level TFP, measured in terms of the superlative TFP index suggested
by Caves, Christensen and Diewert (1982). This index describes how efficiently
each region transforms physical capital and labour into output. The explanatory
variables are internal and out-of-region stocks of knowledge, the latter capturing
the contribution of cross-region knowledge spillovers. We construct patent stocks
to proxy regional knowledge capital stocks for N=203 regions over the 1997-
2002 time period. In estimating the effects we implement a spatial panel data
model that controls for the spatial autocorrelation due to neighbouring regions
and the individual heterogeneity across regions. The findings provide a fairly
remarkable confirmation of the role of knowledge capital contributing to
productivity differences among regions, and add an important spatial dimension
to the discussion, by showing that productivity effects of knowledge spillovers
increase with geographic proximity. (authors' abstract
Characterising two-pathogen competition in spatially structured environments
Different pathogens spreading in the same host population often generate
complex co-circulation dynamics because of the many possible interactions
between the pathogens and the host immune system, the host life cycle, and the
space structure of the population. Here we focus on the competition between two
acute infections and we address the role of host mobility and cross-immunity in
shaping possible dominance/co-dominance regimes. Host mobility is modelled as a
network of traveling flows connecting nodes of a metapopulation, and the
two-pathogen dynamics is simulated with a stochastic mechanistic approach.
Results depict a complex scenario where, according to the relation among the
epidemiological parameters of the two pathogens, mobility can either be
non-influential for the competition dynamics or play a critical role in
selecting the dominant pathogen. The characterisation of the parameter space
can be explained in terms of the trade-off between pathogen's spreading
velocity and its ability to diffuse in a sparse environment. Variations in the
cross-immunity level induce a transition between presence and absence of
competition. The present study disentangles the role of the relevant biological
and ecological factors in the competition dynamics, and provides relevant
insights into the spatial ecology of infectious diseases.Comment: 30 pages, 6 figures, 1 table. Final version accepted for publication
in Scientific Report
Measuring and mitigating behavioural segregation using Call Detail Records
The overwhelming amounts of data we generate in our daily routine and in social networks has been crucial for the understanding of various social and economic factors. The use of this data represents a low-cost alternative source of information in parallel to census data and surveys. Here, we advocate for such an approach to assess and alleviate the segregation of Syrian refugees in Turkey. Using a large dataset of mobile phone records provided by Turkey's largest mobile phone service operator, Türk Telekom, in the frame of the Data 4 Refugees project, we define, analyse and optimise inter-group integration as it relates to the communication patterns of two segregated populations: refugees living in Turkey and the local Turkish population. Our main hypothesis is that making these two communities more similar (in our case, in terms of behaviour) may increase the level of positive exposure between them, due to the well-known sociological principle of homophily. To achieve this, working from the records of call and SMS origins and destinations between and among both populations, we develop an extensible, statistically-solid, and reliable framework to measure the differences between the communication patterns of two groups. In order to show the applicability of our framework, we assess how house mixing strategies, in combination with public and private investment, may help to overcome segregation. We first identify the districts of the Istanbul province where refugees and local population communication patterns differ in order to then utilise our framework to improve the situation. Our results show potential in this regard, as we observe a significant reduction of segregation while limiting, in turn, the consequences in terms of rent increase
A model of meta-population dynamics for North Sea and West of Scotland cod - the dynamic consequences of natal fidelity
It is clear from a variety of data that cod (Gadus morhua) in the North Sea do not constitute a homogeneous population that will rapidly redistribute in response to local variability in exploitation. Hence, local exploitation has the potential to deplete local populations, perhaps to the extent that depensation occurs and recovery is impossible without recolonisation from other areas, with consequent loss of genetic diversity. The oceanographic, biological and behavioural processes which maintain the spatial population structures are only partly understood, and one of the key unknown factors is the extent to which codexhibit homing migrations to natal spawning areas. Here, we describe a model comprising 10 interlinked demes of cod in European waters, each representing groups of fish with a common natal origin. The spawning locations of fish in each deme are governed by a variety of rules concerning oceanographic dispersal, migration behaviour and straying. We describe numerical experiments with the model and comparisons with observations, which lead us to conclude that active homing is probably not necessary to explain some of the population structures of European cod. Separation of some sub-populations is possible through distance and oceanographic processes affecting the dispersal of eggs and larvae. However, other evidence suggests that homing may be a necessary behaviour to explain the structure of other sub-populations. Theconsequences for fisheries management of taking into account spatial population structuring are complicated. For example, recovery or recolonisation strategies require consideration not only of mortality rates in the target area for restoration, but also in the source areas for the recruits which may be far removed depending on the oceanography. The model has an inbuilt capability to address issues concerning the effects of climate change, including temperature change, on spatial patterns of recruitment, development and population structure in cod
Measuring spatial separation processes through the minimum commute : the case of Flanders
The average distance covered by individual commuting trips increases year after year, regardless of the travel mode. The causes of this phenomenon are diverse. Although increasing prosperity is often invoked as the main reason, the discipline of spatial planning also points to the relevance of land-use policies that enable processes of suburbanization and sprawl. By calculating time series of spatially disaggregated theoretical minimum commuting distances, this paper offers a method to identify and quantify the process of spatial separation between the housing market and the job market. We identify the detected spatial separation as one of the possible indicators for the contribution of spatial processes to the growth of traffic.
In the case study area of Flanders and Brussels (Belgium), it is found that over time the minimum commuting distance increased in many municipalities, especially where population is growing faster than job supply, or where traditionally high concentrations of employment still increase. Decreases are noticed in suburban areas that are getting a more urban character by acquiring a considerable functional mix. For the study area in its entirety, we do indeed register an increasing spatial separation between home and work locations. However, this separation evolves less rapidly than the increase in commuting distances itself.
Regarding the methodology, we find that the use of municipalities as a spatial entity is suitable for grasping regional transformations of the economy and intermunicipal forms of suburbanization and peri-urbanization. However, a similar methodology, applied at a more detailed geographical scale, could be used to detect processes of sprawl in the morphological sense
A Spatial Agent-Based Model of N-Person Prisoner's Dilemma Cooperation in a Socio-Geographic Community
The purpose of this paper is to present a spatial agent-based model of N-person prisoner's dilemma that is designed to simulate the collective communication and cooperation within a socio-geographic community. Based on a tight coupling of REPAST and a vector Geographic Information System, the model simulates the emergence of cooperation from the mobility behaviors and interaction strategies of citizen agents. To approximate human behavior, the agents are set as stochastic learning automata with Pavlovian personalities and attitudes. A review of the theory of the standard prisoner's dilemma, the iterated prisoner's dilemma, and the N-person prisoner's dilemma is given as well as an overview of the generic architecture of the agent-based model. The capabilities of the spatial N-person prisoner's dilemma component are demonstrated with several scenario simulation runs for varied initial cooperation percentages and mobility dynamics. Experimental results revealed that agent mobility and context preservation bring qualitatively different effects to the evolution of cooperative behavior in an analyzed spatial environment.Agent Based Modeling, Cooperation, Prisoners Dilemma, Spatial Interaction Model, Spatially Structured Social Dilemma, Geographic Information Systems
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