| 11. |
- Rosvall, Martin, et al.
(författare)
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Modeling self-organization of communication and topology in social networks
- 2006
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Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - 1063-651X .- 1095-3787. ; 74:1, s. 016108-
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Tidskriftsartikel (refereegranskat)abstract
- This paper introduces a model of self-organization between communication and topology in social networks, with a feedback between different communication habits and the topology. To study this feedback, we let agents communicate to build a perception of a network and use this information to create strategic links. We observe a narrow distribution of links when the communication is low and a system with a broad distribution of links when the communication is high. We also analyze the outcome of chatting, cheating, and lying, as strategies to get better access to information in the network. Chatting, although only adopted by a few agents, gives a global gain in the system. Contrary, a global loss is inevitable in a system with too many liars.
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| 12. |
- Rosvall, Martin, et al.
(författare)
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Navigating networks with limited information
- 2005
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Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - : American Physical Society. - 1063-651X .- 1095-3787. ; 71:6, s. 066111-
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Tidskriftsartikel (refereegranskat)abstract
- We study navigation with limited information in networks and demonstrate that many real-world networks have a structure which can be described as favoring communication at short distance at the cost of constraining communication at long distance. This feature, which is robust and more evident with limited than with complete information, reflects both topological and possibly functional design characteristics. For example, the characteristics of the networks studied derived from a city and from the Internet are manifested through modular network designs. We also observe that directed navigation in typical networks requires remarkably little information on the level of individual nodes. By studying navigation or specific signaling, we take a complementary approach to the common studies of information transfer devoted to broadcasting of information in studies of virus spreading and the like.
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| 13. |
- Rosvall, Martin, 1978-, et al.
(författare)
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Network models of phage-bacteria coevolution
- 2006
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Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - 1063-651X .- 1095-3787. ; 74, s. 066105-
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Tidskriftsartikel (refereegranskat)abstract
- Bacteria and their bacteriophages are the most abundant, widespread, and diverse groups of biological entities on the planet. In an attempt to understand how the interactions between bacteria, virulent phages, and temperate phages might affect the diversity of these groups, we developed a stochastic network model for examining the coevolution of these ecologies. In our approach, nodes represent whole species or strains of bacteria or phages, rather than individuals, with “speciation” and extinction modeled by duplication and removal of nodes. Phage-bacteria links represent host-parasite relationships and temperate-virulent phage links denote prophage-encoded resistance. The effect of horizontal transfer of genetic information between strains was also included in the dynamical rules. The observed networks evolved in a highly dynamic fashion but the ecosystems were prone to collapse (one or more entire groups going extinct). Diversity could be stably maintained in the model only if the probability of speciation was independent of the diversity. Such an effect could be achieved in real ecosystems if the speciation rate is primarily set by the availability of ecological niches.
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| 14. |
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| 15. |
- Rosvall, Martin, 1978-, et al.
(författare)
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Networks and our limited information horizon
- 2007
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Ingår i: International Journal of Bifurcation and Chaos in Applied Sciences and Engineering. - Singapore : World Scientific. - 0218-1274. ; 17:7, s. 2509-2515
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we quantify our limited information horizon, by measuring the information necessary to locate specific nodes in a network. To investigate different ways to overcome this horizon, and the interplay between communication and topology in social networks, we let agents communicate in a model society. Thereby they build a perception of the network that they can use to create strategic links to improve their standing in the network. We observe a narrow distribution of links when the communication is low and a network with a broad distribution of links when the communication is high.
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| 16. |
- Rosvall, Martin, 1978-, et al.
(författare)
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Reinforced communication and social navigation generate groups in model networks
- 2009
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Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - 1063-651X .- 1095-3787. ; 79:2, s. 026111-026118
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Tidskriftsartikel (refereegranskat)abstract
- To investigate the role of information flow in group formation, we introduce a model of communication and social navigation. We let agents gather information in an idealized network society and demonstrate that heterogeneous groups can evolve without presuming that individuals have different interests. In our scenario, individuals’ access to global information is constrained by local communication with the nearest neighbors on a dynamic network. The result is reinforced interests among like-minded agents in modular networks; the flow of information works as a glue that keeps individuals together. The model explains group formation in terms of limited information access and highlights global broadcasting of information as a way to counterbalance this fragmentation. To illustrate how the information constraints imposed by the communication structure affects future development of real-world systems, we extrapolate dynamics from the topology of four social networks.
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| 17. |
- Rosvall, Martin, 1978-, et al.
(författare)
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Searchability of networks
- 2005
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Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - : American Physical Society. - 1063-651X .- 1095-3787. ; 72:4, s. 046117-046125
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the searchability of complex systems in terms of their interconnectedness. Associating searchability with the number and size of branch points along the paths between the nodes, we find that scale-free networks are relatively difficult to search, and thus that the abundance of scale-free networks in nature and society may reflect an attempt to protect local areas in a highly interconnected network from nonrelated communication. In fact, starting from a random node, real-world networks with higher order organization like modular or hierarchical structure are even more difficult to navigate than random scale-free networks. The searchability at the node level opens the possibility for a generalized hierarchy measure that captures both the hierarchy in the usual terms of trees as in military structures, and the intrinsic hierarchical nature of topological hierarchies for scale-free networks as in the Internet.
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| 18. |
- Rosvall, Martin, et al.
(författare)
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Self-assembly of information in networks
- 2006
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Ingår i: Europhysics letters. - : IOP Publishing. - 0295-5075 .- 1286-4854. ; 74:6, s. 1109-1115
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Tidskriftsartikel (refereegranskat)abstract
- We model self-assembly of information in networks to investigate necessary conditions for building a global perception of a system by local communication. Our approach is to let agents chat in a model system to self-organize distant communication pathways. We demonstrate that simple local rules allow agents to build a perception of the system, that is robust to dynamical changes and mistakes. We find that messages are most effectively forwarded in the presence of hubs, while transmission in hub-free networks is more robust against misinformation and failures.
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| 19. |
- Rosvall, Maria, et al.
(författare)
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Similar support for three different life course socioeconomic models on predicting premature cardiovascular mortality and all-cause mortality
- 2006
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Ingår i: BMC Public Health. - : Springer Science and Business Media LLC. - 1471-2458. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Background: There are at least three broad conceptual models for the impact of the social environment on adult disease: the critical period, social mobility, and cumulative life course models. Several studies have shown an association between each of these models and mortality. However, few studies have investigated the importance of the different models within the same setting and none has been performed in samples of the whole population. The purpose of the present study was to study the relation between socioeconomic position (SEP) and mortality using different conceptual models in the whole population of Scania. Methods: In the present investigation we use socioeconomic information on all men (N = 48,909) and women ( N = 47,688) born between 1945 and 1950, alive on January, 1(st), 1990, and living in the Region of Scania, in Sweden. Focusing on three specific life periods (i.e., ages 10 - 15, 30 - 35 and 40 - 45), we examined the association between SEP and the 12-year risk of premature cardiovascular mortality and all-cause mortality. Results: There was a strong relation between SEP and mortality among those inside the workforce, irrespective of the conceptual model used. There was a clear upward trend in the mortality hazard rate ratios (HRR) with accumulated exposure to manual SEP in both men ( p for trend < 0.001 for both cardiovascular and all-cause mortality) and women ( p for trend = 0.01 for cardiovascular mortality) and ( p for trend = 0.003 for all-cause mortality). Inter- and intragenerational downward social mobility was associated with an increased mortality risk. When applying similar conceptual models based on workforce participation, it was shown that mortality was affected by the accumulated exposure to being outside the workforce. Conclusion: There was a strong relation between SEP and cardiovascular and all-cause mortality, irrespective of the conceptual model used. The critical period, social mobility, and cumulative life course models, showed the same fit to the data. That is, one model could not be pointed out as "the best" model and even in this large unselected sample it was not possible to adjudicate which theories best describe the links between life course SEP and mortality risk.
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| 20. |
- Rosvall, Maria, et al.
(författare)
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The association between socioeconomic position, use of revascularization procedures and five-year survival after recovery from acute myocardial infarction
- 2008
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Ingår i: BMC Public Health. - : Springer Science and Business Media LLC. - 1471-2458. ; 8:44
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Tidskriftsartikel (refereegranskat)abstract
- Background: Patients living under better socioeconomic circumstances often receive more active treatments after an acute myocardial infarction ( AMI) compared to less affluent patients. However, most previous studies were performed in countries with less comprehensive coverage for medical services. In this Swedish nation- wide longitudinal study we wanted to evaluate long- term survival after AMI in relation to socioeconomic position ( SEP) and use of revascularization. Methods: From the Swedish Myocardial Infarction Register we identified all 45 to 84- year- old patients ( 16,041 women and 30,366 men) alive 28 days after their first AMI during the period 1993 to 1996. We obtained detailed information on the use of revascularization, cumulative household income from the 1975 and 1990 censuses and 5- year survival after the AMI. Results: Patients with the highest cumulative income ( adding the values of the quartile categories of income in 1975 and 1990) underwent a revascularization procedure within one month after their first AMI two to three times as often as patients with the lowest cumulative income and had half the risk of death within five years. The socioeconomic differences in the use of revascularization procedures could not be explained by differences in co- morbidity or type of hospital at first admission. Patients who underwent revascularization showed a similar lowered mortality risk in the different income groups, while there were strong socioeconomic differences in long- term mortality among patients who did not undergo revascularization. Conclusion: This nationwide Swedish study showed that patients with high income had a better long- term survival after recovery from their AMI compared to patients with low income. Furthermore, even though the use of revascularization procedures is beneficial, low SEP groups receive it less often than high SEP groups.
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