Fredrik Liljeros


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Arbetar vid Sociologiska institutionen
Besöksadress Universitetsvägen 10 B, plan 9
Rum B 951
Postadress Sociologiska institutionen 106 91 Stockholm


I urval från Stockholms universitets publikationsdatabas
  • 2014. Jan Albert (et al.). Scandinavian Journal of Infectious Diseases 46 (10), 673-677

    The modern medical treatment of HIV with antiretroviral therapy (ART) has drastically reduced the morbidity and mortality in patients infected with this virus. ART has also been shown to reduce the transmission risk from individual patients as well as the spread of the infection at the population level. This position statement from the Public Health Agency of Sweden and the Swedish Reference Group for Antiviral Therapy is based on a workshop organized in the fall of 2012. It summarizes the latest research and knowledge on the risk of HIV transmission from patients on ART, with a focus on the risk of sexual transmission. The risk of transmission via shared injection equipment among intravenous drug users is also examined, as is the risk of mother-to-child transmission. Based on current knowledge, the risk of transmission through vaginal or anal intercourse involving the use of a condom has been judged to be minimal, provided that the person infected with HIV fulfils the criteria for effective ART. This probably also applies to unprotected intercourse, provided that no other sexually transmitted infections are present, although it is not currently possible to fully support this conclusion with direct scientific evidence. ART is judged to markedly reduce the risk of blood-borne transmission between people who share injection equipment. Finally, the risk of transmission from mother to child is very low, provided that ART is started well in advance of delivery.

  • 2016. Jens Malmros, Fredrik Liljeros, Tom Britton. Journal of Applied Probability 53 (2), 518-540

    Respondent-driven sampling (RDS) is frequently used when sampling from hidden populations. In RDS, sampled individuals pass on participation coupons to at most c of their acquaintances in the community (c = 3 being a common choice). If these individuals choose to participate, they in turn pass coupons on to their acquaintances, and so on. The process of recruiting is shown to behave like a new Reed-Frost-type network epidemic, in which `becoming infected' corresponds to study participation. We calculate R-0, the probability of a major `outbreak', and the relative size of a major outbreak for c < infinity in the limit of infinite population size and compare to the standard Reed-Frost epidemic. Our results indicate that c should often be chosen larger than in current practice.

  • 2011. Paul D. Whitehead, Fredrik Liljeros. The journal of the American Academy of Psychiatry and the Law 39 (1), 93-99

    Regulations that govern oversight of seclusion and/or restraint episodes (SREs) in the United States are relatively uniform and may assume that such events are normally distributed within the population generating them. This study illustrates that the distribution of patients who required one or more SREs within one state psychiatric hospital setting is heavy-tailed-that is, a small group of patients generated a disproportionate majority of the events: 20 percent of patients with the most SREs accounted for approximately 75 percent of the total number of SREs; 10 percent of patients accounted for 61 percent, and 1 percent of patients accounted for 21 percent. Characteristic features of heavy-tailed distributions are described and discussed in relation to the feasibility of eliminating SREs in mental health settings and the governance of SREs by uniform regulations. Attempts are made to model and subtype the distribution, and commentary is made as to potential clinical and policy relevance of the findings.

  • 2007. Birgitte Freiesleben de Blasio, Åke Svensson, Fredrik Liljeros. Proc Natl Acad Sci U S A 104 (26), 10762-7
  • 2001. Fredrik Liljeros (et al.). Nature 411 (6840), 907-8
  • 2009. Diego Rybski (et al.). Proceedings of the National Academy of Sciences of the United States of America 106 (31), 12640-5

    Even though people in our contemporary technological society are depending on communication, our understanding of the underlying laws of human communicational behavior continues to be poorly understood. Here we investigate the communication patterns in 2 social Internet communities in search of statistical laws in human interaction activity. This research reveals that human communication networks dynamically follow scaling laws that may also explain the observed trends in economic growth. Specifically, we identify a generalized version of Gibrat's law of social activity expressed as a scaling law between the fluctuations in the number of messages sent by members and their level of activity. Gibrat's law has been essential in understanding economic growth patterns, yet without an underlying general principle for its origin. We attribute this scaling law to long-term correlation patterns in human activity, which surprisingly span from days to the entire period of the available data of more than 1 year. Further, we provide a mathematical framework that relates the generalized version of Gibrat's law to the long-term correlated dynamics, which suggests that the same underlying mechanism could be the source of Gibrat's law in economics, ranging from large firms, research and development expenditures, gross domestic product of countries, to city population growth. These findings are also of importance for designing communication networks and for the understanding of the dynamics of social systems in which communication plays a role, such as economic markets and political systems.

  • 2007. Fredrik Liljeros, Petter Holme, Johan Giesecke. Mathematical Population Studies 14 (4), 269-284
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Senast uppdaterad: 22 maj 2017

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