In this research, an agent-based model (ABM) was developed to generate human movement routes betw... more In this research, an agent-based model (ABM) was developed to generate human movement routes between homes and water resources in a rural setting, given commonly available geospatial datasets on population distribution, land cover and landscape resources. ABMs are an object-oriented computational approach to modelling a system, focusing on the interactions of autonomous agents, and aiming to assess the impact of these agents and their interactions on the system as a whole. An A* pathfinding algorithm was implemented to produce walking routes, given data on the terrain in the area. A* is an extension of Dijkstra's algorithm with an enhanced time performance through the use of heuristics. In this example, it was possible to impute daily activity movement patterns to the water resource for all villages in a 75 km long study transect across the Luangwa Valley, Zambia, and the simulated human movements were statistically similar to empirical observations on travel times to the water ...
Computing and Informatics / Computers and Artificial Intelligence, 2003
Inapersistentmulti-agentsystem,itshouldbepossiblefornewagents to beneflt from the accumulated lea... more Inapersistentmulti-agentsystem,itshouldbepossiblefornewagents to beneflt from the accumulated learning of more experienced agents. Parallel reasoning can be applied to the case of newborn animals, and thus the biological literature on social learning may aid in the construction of efiective multi-agent systems. Biologists have looked at both the functions of social learning and the mechanismsthatenableit. Manyresearchershavefocusedonthecognitivelycom- plex mechanism of imitation; we will also
Imitation has been of great interest to students of animal so cial learning, but the power of sim... more Imitation has been of great interest to students of animal so cial learning, but the power of simpler processes has probab ly been underestimated. Six classes of simple mechanisms for gaining information from the behaviour of conspecifics are considered: social facilitation, contagious behaviour, s timulus enhancement, observational learning, learning to copy, and cross-modal matching. Possible examples are given of these
Genetic and Evolutionary Computation Conference, 2001
When using an automatic discovery methodto nd a good strategy in a game, we hopeto nd one that pe... more When using an automatic discovery methodto nd a good strategy in a game, we hopeto nd one that performs well against awide variety of opponents. An appealing notionin the use of evolutionary algorithmsto coevolve strategies is that the populationrepresents a set of dierent strategiesagainst which a player must do well. Implicithere is the idea that dierent playersrepresent dierent \dimensions" of
In the pine forests of Israel, black rats Rattus rattus have hit upon a novel feeding technique. ... more In the pine forests of Israel, black rats Rattus rattus have hit upon a novel feeding technique. They strip the scales from pine cones to obtain th e nutritious seeds inside (Terkel, 1996). The behaviour seems to be socially learned in some way, rather than genetically inherited: Terkel has shown that rat pups will l earn to strip cones if
We review and critique a range of perspectives on thescientific role of individual-based evolutio... more We review and critique a range of perspectives on thescientific role of individual-based evolutionary simulationmodels as they are used within artificial life.We find that such models have the potential to enrichexisting modelling enterprises through their strengthin modelling systems of interacting entities. Furthermore,simulation techniques promise to provide theoreticiansin various fields with entirely new conceptual,as well as methodological, approaches. However,the...
AIDS education and prevention : official publication of the International Society for AIDS Education, 1997
Many commentators have positioned Western gay youth as a high-risk group for HIV infection and ob... more Many commentators have positioned Western gay youth as a high-risk group for HIV infection and obscured important cultural, social, and contextual differences between populations. This study compares risk of HIV transmission factors among 216 young (under 25 years) and 822 older (25 years or over) homosexually active men, recruited through Sydney gay community and other sources. Bivariate and multivariate analyses of survey data that were collected by personal interviews consistently supported our hypothesis of no difference in HIV-related risk factors between young and older men. Although young men in this cohort were more likely to be of unknown serostatus, they were at least as knowledgeable, as attached to gay community, and as precautionary in their sexual behaviors with regular and casual male partners as their older counterparts. Safety campaigns targeting these young gay men should focus, for example, on their lower rates of HIV antibody testing and not be based on a false p...
Philosophical transactions of the Royal Society of London. Series B, Biological sciences, Jan 29, 1997
The vast majority of work in machine vision emphasizes the representation of perceived objects an... more The vast majority of work in machine vision emphasizes the representation of perceived objects and events: it is these internal representations that incorporate the 'knowledge' in knowledge-based vision or form the 'models' in model-based vision. In this paper, we discuss simple machine vision systems developed by artificial evolution rather than traditional engineering design techniques, and note that the task of identifying internal representations within such systems is made difficult by the lack of an operational definition of representation at the causal mechanistic level. Consequently, we question the nature and indeed the existence of representations posited to be used within natural vision systems (i.e. animals). We conclude that representations argued for on a priori grounds by external observers of a particular vision system may well be illusory, and are at best place-holders for yet-to-be-identified causal mechanistic interactions. That is, applying the kn...
To test the safety of the 'negotiated safety' strategy-the strategy of dispensing with co... more To test the safety of the 'negotiated safety' strategy-the strategy of dispensing with condoms within HIV-seronegative concordant regular sexual relationships under certain conditions. Data from recently recruited cohort of homosexually active men (Sydney Men and Sexual Health cohort, n = 1037) are used to revisit negotiated safety. The men were surveyed using a structured questionnaire and questions addressing their sexual relationships and practice their own and their regular partner's serostatus, agreements entered into by the men concerning sexual practice within and outside their regular relationship, and contextual and demographic variables. The findings indicate that a significant number of men used negotiated safety as an HIV prevention strategy. In the 6 months prior to interview, of the 181 men in seroconcordant HIV-negative regular relationships, 62% had engaged in unprotected anal intercourse within their relationship, and 91% (165 men) had not engaged in unp...
Recent advances in proteomic profiling technologies, such as surface enhanced laser desorption io... more Recent advances in proteomic profiling technologies, such as surface enhanced laser desorption ionization mass spectrometry, have allowed preliminary profiling and identification of tumor markers in biological fluids in several cancer types and establishment of clinically useful diagnostic computational models. There are currently no routinely used circulating tumor markers for renal cancer, which is often detected incidentally and is frequently advanced at the time of presentation with over half of patients having local or distant tumor spread. We have investigated the clinical utility of surface enhanced laser desorption ionization profiling of urine samples in conjunction with neural-network analysis to either detect renal cancer or to identify proteins of potential use as markers, using samples from a total of 218 individuals, and examined critical technical factors affecting the potential utility of this approach. Samples from patients before undergoing nephrectomy for clear ce...
... for Adaptive Behavior and Cognition Max Planck Institute for Human Development Lentzeallee 94... more ... for Adaptive Behavior and Cognition Max Planck Institute for Human Development Lentzeallee 94, D-14195 Berlin, Germany noble, tuci, ptodd9mpib ... Newborn rats inherited (with a small chance of mutation) the four-element behavioural strategy of their parent described above ...
In this research, an agent-based model (ABM) was developed to generate human movement routes betw... more In this research, an agent-based model (ABM) was developed to generate human movement routes between homes and water resources in a rural setting, given commonly available geospatial datasets on population distribution, land cover and landscape resources. ABMs are an object-oriented computational approach to modelling a system, focusing on the interactions of autonomous agents, and aiming to assess the impact of these agents and their interactions on the system as a whole. An A* pathfinding algorithm was implemented to produce walking routes, given data on the terrain in the area. A* is an extension of Dijkstra's algorithm with an enhanced time performance through the use of heuristics. In this example, it was possible to impute daily activity movement patterns to the water resource for all villages in a 75 km long study transect across the Luangwa Valley, Zambia, and the simulated human movements were statistically similar to empirical observations on travel times to the water ...
Computing and Informatics / Computers and Artificial Intelligence, 2003
Inapersistentmulti-agentsystem,itshouldbepossiblefornewagents to beneflt from the accumulated lea... more Inapersistentmulti-agentsystem,itshouldbepossiblefornewagents to beneflt from the accumulated learning of more experienced agents. Parallel reasoning can be applied to the case of newborn animals, and thus the biological literature on social learning may aid in the construction of efiective multi-agent systems. Biologists have looked at both the functions of social learning and the mechanismsthatenableit. Manyresearchershavefocusedonthecognitivelycom- plex mechanism of imitation; we will also
Imitation has been of great interest to students of animal so cial learning, but the power of sim... more Imitation has been of great interest to students of animal so cial learning, but the power of simpler processes has probab ly been underestimated. Six classes of simple mechanisms for gaining information from the behaviour of conspecifics are considered: social facilitation, contagious behaviour, s timulus enhancement, observational learning, learning to copy, and cross-modal matching. Possible examples are given of these
Genetic and Evolutionary Computation Conference, 2001
When using an automatic discovery methodto nd a good strategy in a game, we hopeto nd one that pe... more When using an automatic discovery methodto nd a good strategy in a game, we hopeto nd one that performs well against awide variety of opponents. An appealing notionin the use of evolutionary algorithmsto coevolve strategies is that the populationrepresents a set of dierent strategiesagainst which a player must do well. Implicithere is the idea that dierent playersrepresent dierent \dimensions" of
In the pine forests of Israel, black rats Rattus rattus have hit upon a novel feeding technique. ... more In the pine forests of Israel, black rats Rattus rattus have hit upon a novel feeding technique. They strip the scales from pine cones to obtain th e nutritious seeds inside (Terkel, 1996). The behaviour seems to be socially learned in some way, rather than genetically inherited: Terkel has shown that rat pups will l earn to strip cones if
We review and critique a range of perspectives on thescientific role of individual-based evolutio... more We review and critique a range of perspectives on thescientific role of individual-based evolutionary simulationmodels as they are used within artificial life.We find that such models have the potential to enrichexisting modelling enterprises through their strengthin modelling systems of interacting entities. Furthermore,simulation techniques promise to provide theoreticiansin various fields with entirely new conceptual,as well as methodological, approaches. However,the...
AIDS education and prevention : official publication of the International Society for AIDS Education, 1997
Many commentators have positioned Western gay youth as a high-risk group for HIV infection and ob... more Many commentators have positioned Western gay youth as a high-risk group for HIV infection and obscured important cultural, social, and contextual differences between populations. This study compares risk of HIV transmission factors among 216 young (under 25 years) and 822 older (25 years or over) homosexually active men, recruited through Sydney gay community and other sources. Bivariate and multivariate analyses of survey data that were collected by personal interviews consistently supported our hypothesis of no difference in HIV-related risk factors between young and older men. Although young men in this cohort were more likely to be of unknown serostatus, they were at least as knowledgeable, as attached to gay community, and as precautionary in their sexual behaviors with regular and casual male partners as their older counterparts. Safety campaigns targeting these young gay men should focus, for example, on their lower rates of HIV antibody testing and not be based on a false p...
Philosophical transactions of the Royal Society of London. Series B, Biological sciences, Jan 29, 1997
The vast majority of work in machine vision emphasizes the representation of perceived objects an... more The vast majority of work in machine vision emphasizes the representation of perceived objects and events: it is these internal representations that incorporate the 'knowledge' in knowledge-based vision or form the 'models' in model-based vision. In this paper, we discuss simple machine vision systems developed by artificial evolution rather than traditional engineering design techniques, and note that the task of identifying internal representations within such systems is made difficult by the lack of an operational definition of representation at the causal mechanistic level. Consequently, we question the nature and indeed the existence of representations posited to be used within natural vision systems (i.e. animals). We conclude that representations argued for on a priori grounds by external observers of a particular vision system may well be illusory, and are at best place-holders for yet-to-be-identified causal mechanistic interactions. That is, applying the kn...
To test the safety of the 'negotiated safety' strategy-the strategy of dispensing with co... more To test the safety of the 'negotiated safety' strategy-the strategy of dispensing with condoms within HIV-seronegative concordant regular sexual relationships under certain conditions. Data from recently recruited cohort of homosexually active men (Sydney Men and Sexual Health cohort, n = 1037) are used to revisit negotiated safety. The men were surveyed using a structured questionnaire and questions addressing their sexual relationships and practice their own and their regular partner's serostatus, agreements entered into by the men concerning sexual practice within and outside their regular relationship, and contextual and demographic variables. The findings indicate that a significant number of men used negotiated safety as an HIV prevention strategy. In the 6 months prior to interview, of the 181 men in seroconcordant HIV-negative regular relationships, 62% had engaged in unprotected anal intercourse within their relationship, and 91% (165 men) had not engaged in unp...
Recent advances in proteomic profiling technologies, such as surface enhanced laser desorption io... more Recent advances in proteomic profiling technologies, such as surface enhanced laser desorption ionization mass spectrometry, have allowed preliminary profiling and identification of tumor markers in biological fluids in several cancer types and establishment of clinically useful diagnostic computational models. There are currently no routinely used circulating tumor markers for renal cancer, which is often detected incidentally and is frequently advanced at the time of presentation with over half of patients having local or distant tumor spread. We have investigated the clinical utility of surface enhanced laser desorption ionization profiling of urine samples in conjunction with neural-network analysis to either detect renal cancer or to identify proteins of potential use as markers, using samples from a total of 218 individuals, and examined critical technical factors affecting the potential utility of this approach. Samples from patients before undergoing nephrectomy for clear ce...
... for Adaptive Behavior and Cognition Max Planck Institute for Human Development Lentzeallee 94... more ... for Adaptive Behavior and Cognition Max Planck Institute for Human Development Lentzeallee 94, D-14195 Berlin, Germany noble, tuci, ptodd9mpib ... Newborn rats inherited (with a small chance of mutation) the four-element behavioural strategy of their parent described above ...
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