Endre søk
Begrens søket
1 - 43 of 43
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1. Albert, Jan
    et al.
    Berglund, Torsten
    Gisslen, Magnus
    Groon, Peter
    Sonnerborg, Anders
    Tegnell, Anders
    Alexandersson, Anders
    Berggren, Ingela
    Blaxhult, Anders
    Brytting, Maria
    Carlander, Christina
    Carlson, Johan
    Flamholc, Leo
    Follin, Per
    Haggar, Axana
    Hansdotter, Frida
    Josephson, Filip
    Karlström, Olle
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Naver, Lars
    Pettersson, Karin
    Johansson, Veronica Svedhem
    Svennerholm, Bo
    Tunback, Petra
    Widgren, Katarina
    Risk of HIV transmission from patients on antiretroviral therapy: A position statement from the Public Health Agency of Sweden and the Swedish Reference Group for Antiviral Therapy2014Inngår i: Scandinavian Journal of Infectious Diseases, ISSN 0036-5548, E-ISSN 1651-1980, Vol. 46, nr 10, s. 673-677Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    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.

  • 2. Bengtsson, Linus
    et al.
    Lu, Xin
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen. The Institute for Futures Studies, Sweden.
    Thanh, Hoang Huy
    Thorson, Anna
    Strong propensity for HIV transmission among men who have sex with men in Vietnam: behavioural data and sexual network modelling2014Inngår i: BMJ Open, ISSN 2044-6055, E-ISSN 2044-6055, Vol. 4, nr 1, artikkel-id e003526Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objectives Survey data from men who have sex with men (MSM) in Asian cities indicate ongoing and drastic increases in HIV prevalence. It is unknown which behavioural factors are most important in driving these epidemics. We aimed to analyse detailed sexual behaviour data among MSM in Vietnam and to model HIV transmission using improved assumptions on sexual network structure. Setting Vietnam. Participants Internet-using men who had ever had sex (any type) with a man, aged 18years and living in Vietnam. The study was cross-sectional, population-based and performed in 2012, using online respondent-driven sampling. The Internet-based survey instrument was completed by 982 participants, of which 857 were eligible. Questions included sociodemography and retrospective sexual behaviour, including number of unprotected anal sex (UAS) acts per partner. Primary and secondary outcome measures Estimated basic reproductive number over 3months as a function of transmission risk per UAS act; frequency distributions of number of UAS partners and UAS acts during last 3months. Results 36% (CI 32% to 42%) reported UAS at least once during the last 3months. 36% (CI 32% to 41%) had ever taken an HIV test and received the result. UAS partner numbers and number of UAS acts were both highly skewed and positively correlated. Using a weighted configuration model, taking into account partner numbers, frequency of UAS and their correlations, we estimated the basic reproductive number (R0) over 3months. The results indicated rapid transmission over a wide range of values of per-act transmissibility. Conclusions Men with multiple partners had unexpectedly high UAS frequency per partner, paired with low HIV testing rates. The study highlights the importance of collecting data on frequency of UAS acts and indicates the need to rapidly scale-up HIV prevention services and testing opportunities for MSM in Vietnam.

  • 3. Bengtsson, Linus
    et al.
    Lu, Xin
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Nguyen, Quoc Cuong
    Camitz, Martin
    Hoang, Nguyen Le
    Nguyen, Tuan Anh
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Thorson, Anna
    Implementation of Web-Based Respondent-Driven Sampling among Men Who Have Sex with Men in Vietnam2012Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, nr 11, s. e49417-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objective: Lack of representative data about hidden groups, like men who have sex with men (MSM), hinders an evidence-based response to the HIV epidemics. Respondent-driven sampling (RDS) was developed to overcome sampling challenges in studies of populations like MSM for which sampling frames are absent. Internet-based RDS (webRDS) can potentially circumvent limitations of the original RDS method. We aimed to implement and evaluate webRDS among a hidden population. Methods and Design: criteria were men, aged 18 and above, who had ever had sex with another man and were living in Vietnam. Participants were invited by an MSM friend, logged in, and answered a survey. Participants could recruit up to four MSM friends. We evaluated the system by its success in generating sustained recruitment and the degree to which the sample compositions stabilized with increasing sample size. Results: Twenty starting participants generated 676 participants over 24 recruitment waves. Analyses did not show evidence of bias due to ineligible participation. Estimated mean age was 22 years and 82% came from the two large metropolitan areas. 32 out of 63 provinces were represented. The median number of sexual partners during the last six months was two. The sample composition stabilized well for 16 out of 17 variables. Conclusion: Results indicate that webRDS could be implemented at a low cost among Internet-using MSM in Vietnam. WebRDS may be a promising method for sampling of Internet-using MSM and other hidden groups.

  • 4.
    Boman, Magnus
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Ghaffar, Asim
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Stenhem, Mikael
    Social network visualization as a contract tracing tool2006Inngår i: Proceedings First International Work Shop on Agent Technology for Disaster Management, Nick Jennings , 2006, s. 131-133Konferansepaper (Fagfellevurdert)
  • 5.
    Britton, Tom
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Matematiska institutionen.
    Deijfen, Maria
    Stockholms universitet, Naturvetenskapliga fakulteten, Matematiska institutionen.
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    A weighted configuration model and inhomogeneous epidemics2011Inngår i: Journal of statistical physics, ISSN 0022-4715, E-ISSN 1572-9613, Vol. 145, s. 1368-1384Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A random graph model with prescribed degree distribution and degree dependent

    edge weights is introduced. Each vertex is independently equipped with a random number

    of half-edges and each half-edge is assigned an integer valued weight according to a distribution

    that is allowed to depend on the degree of its vertex. Half-edges with the same weight

    are then paired randomly to create edges. An expression for the threshold for the appearance

    of a giant component in the resulting graph is derived using results on multi-type branching

    processes. The same technique also gives an expression for the basic reproduction number

    for an epidemic on the graph where the probability that a certain edge is used for transmission

    is a function of the edge weight (reflecting how closely ‘connected’ the corresponding

    vertices are). It is demonstrated that, if vertices with large degree tend to have large (small)

    weights on their edges and if the transmission probability increases with the edge weight,

    then it is easier (harder) for the epidemic to take off compared to a randomized epidemic

    with the same degree and weight distribution. A recipe for calculating the probability of a

    large outbreak in the epidemic and the size of such an outbreak is also given. Finally, the

    model is fitted to three empirical weighted networks of importance for the spread of contagious

    diseases and it is shown that

    R0

    can be substantially over- or underestimated if the

    correlation between degree and weight is not taken into account.

  • 6. Britton, Tom
    et al.
    Nordvik, Monica K
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Modelling sexually transmitted infections: the effect of partnership activity and number of partners on R0.2007Inngår i: Theor Popul Biol, ISSN 0040-5809, Vol. 72, nr 3, s. 389-99Artikkel i tidsskrift (Fagfellevurdert)
  • 7.
    Britton, Tom
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Matematiska institutionen.
    Nordvik, Monica
    Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Liljeros, Fredrik
    Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Modelling sexually transmitted infections: the effect of2007Inngår i: Theor. Pop Biol., Vol. 17, s. 389-399Artikkel i tidsskrift (Fagfellevurdert)
  • 8. Chen, Y
    et al.
    paul, G
    Cohen, R
    Havlin, S
    Borgatti, S
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Percolation theory and fragmentation measures in social networks2007Inngår i: Physica A, Vol. 378, nr 1, s. 11-19Artikkel i tidsskrift (Fagfellevurdert)
  • 9. Chen, Y
    et al.
    Paul, G
    Havlin, S
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Stanley, H. E.
    Finding a better immunization strategy2008Inngår i: Phys Rev Lett, Vol. 101, nr 5Artikkel i tidsskrift (Fagfellevurdert)
  • 10. Chen, Yiping
    et al.
    Paul, Gerald
    Cohen, Reuven
    Havlin, Shlomo
    Borgatti, Stephen P
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Stanley, H Eugene
    Percolation theory applied to measures of fragmentation in social networks.2007Inngår i: Phys Rev E Stat Nonlin Soft Matter Phys, ISSN 1539-3755, Vol. 75, nr 4 Pt 2, s. 046107-Artikkel i tidsskrift (Fagfellevurdert)
  • 11. de Blasio, Birgitte Freiesleben
    et al.
    Svensson, Åke
    Stockholms universitet, Naturvetenskapliga fakulteten, Matematiska institutionen.
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Preferential attachment in sexual networks.2007Inngår i: Proc Natl Acad Sci U S A, ISSN 1091-6490, Vol. 104, nr 26, s. 10762-7Artikkel i tidsskrift (Fagfellevurdert)
  • 12.
    Edling, Christofer
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Liljeros, FredrikStockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Ett delat samhälle: makt, intersektionalitet och social skiktning2010Collection/Antologi (Annet vitenskapelig)
    Abstract [sv]

    Sociologin har ända sedan ämnets grundande sysslat med samma problemställning: Hur ska vi förstå samhällets sociala ojämlikhet och hur påverkar den människors livschanser? Men trots denna gemensamma kärna, finns det inom sociologin en mångfald av teoretiska perspektiv, metodologiska ansatser och olika sätt att se samhället. I denna antologi visar författarna att sociologins pluralism inte ska ses som en svaghet, utan snarare som en tillgång som berikar ämnet. De vill ge en inblick i sociologins djup och bredd – och på så sätt inspirera till fortsatt sociologiskt tänkande!

  • 13.
    Edling, Christofer
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Social skiktning2010Inngår i: Ett delat samhälle: makt, intersektionalitet och social skiktning / [ed] Christofer Edling, Fredrik Liljeros, Malmö: Liber , 2010, s. 8-30Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 14. Gallos, Lazaros K
    et al.
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Argyrakis, Panos
    Bunde, Armin
    Havlin, Shlomo
    Improving immunization strategies.2007Inngår i: Phys Rev E Stat Nonlin Soft Matter Phys, ISSN 1539-3755, Vol. 75, nr 4 Pt 2, s. 045104-Artikkel i tidsskrift (Fagfellevurdert)
  • 15. Gallos, Lazaros K.
    et al.
    Rybski, Diego
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Havlin, Shlomo
    Makse, Hernan A.
    How People Interact in Evolving Online Affiliation Networks2012Inngår i: PHYSICAL REVIEW X, ISSN 2160-3308, Vol. 2, nr 3, s. 031014-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The study of human interactions is of central importance for understanding the behavior of individuals, groups, and societies. Here, we observe the formation and evolution of networks by monitoring the addition of all new links, and we analyze quantitatively the tendencies used to create ties in these evolving online affiliation networks. We show that an accurate estimation of these probabilistic tendencies can be achieved only by following the time evolution of the network. Inferences about the reason for the existence of links using statistical analysis of network snapshots must therefore be made with great caution. Here, we start by characterizing every single link when the tie was established in the network. This information allows us to describe the probabilistic tendencies of tie formation and extract meaningful sociological conclusions. We also find significant differences in behavioral traits in the social tendencies among individuals according to their degree of activity, gender, age, popularity, and other attributes. For instance, in the particular data sets analyzed here, we find that women reciprocate connections 3 times as much as men and that this difference increases with age. Men tend to connect with the most popular people more often than women do, across all ages. On the other hand, triangular tie tendencies are similar, independent of gender, and show an increase with age. These results require further validation in other social settings. Our findings can be useful to build models of realistic social network structures and to discover the underlying laws that govern establishment of ties in evolving social networks.

  • 16.
    Halvarsson, Veronika
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Ström, Sara
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    The prescription of oral contraceptives and its relation to the incidence of chlamydia and abortion in Sweden 1997-20052012Inngår i: Scandinavian Journal of Public Health, ISSN 1403-4948, E-ISSN 1651-1905, Vol. 40, nr 1, s. 85-91Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aims: The aim of this study is to examine the association between the prescription of oral contraceptives and the incidence of chlamydia, and between the prescription of oral contraceptives and the number of abortions in a population-based ecological study. Methods: For this study we used register data from the Swedish Institute for Infectious Disease Control (chlamydia incidence), the Swedish National Board of Health and Welfare (number of abortions), Statistics Sweden (population data), and Apoteket (Swedish pharmacy) (prescriptions for oral contraceptives). We conducted ordinary least squares regression analysis of the association between chlamydia or abortions and the prescription of oral contraceptives. Results: The prescription of oral contraceptives has a positive association on both the incidence of chlamydia and the numbers of abortion. Our best model predicts that prescription of 100 yearly doses of oral contraceptives increase the abortions by 3.3 cases among 16-year-old women and 0.7 cases among 29-year-old women, while cases of chlamydia increase by 6.7 among 16-year-old women and 1.5 among 29-year-old women. Conclusions: Our findings indicate that the use of oral contraceptives among young people and young adults is positively associated with the chlamydia incidence and the abortion rate in these populations in Sweden.

  • 17.
    Hansson, Disa
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Matematiska institutionen.
    Fridlund, Veronika
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Stenqvist, Karin
    Britton, Tom
    Stockholms universitet, Naturvetenskapliga fakulteten, Matematiska institutionen.
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Inferring individual sexual action dispositions from egocentric network data on dyadic sexual outcomes2018Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 13, nr 11, artikkel-id e0207116Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper we present a family of models that allows us to estimate egos' unobserved action dispositions from a joint behavioural outcome of a dyadic social interaction process of both egos' and alters' action dispositions. The method is put to test on a data set containing two different types of dyadic activities of high relevance for the spread of sexually transmitted infections (STI), condom use and anal sex. The data consists of individuals older than 15 years old who visited one of the nine youth clinics in the Vastra Gotaland region of Sweden between February 2010 and March 2011 for STI testing. This is hence a group of special interest for STI interventions. We cannot find any difference in condom disposition between women and men. Condoms are initially used more often in less risky types of relationships, especially if the partner ends up as a main partner. When studying the disposition towards anal sex we do however find a difference between men and women. Women are more against practising anal sex than men while the majority of men are neutral towards anal sex.

  • 18.
    Holme, Petter
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Birth and death of links control disease spreading in empirical contact networks2014Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 4, s. 4999-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigate what structural aspects of a collection of twelve empirical temporal networks of human contacts are important to disease spreading. We scan the entire parameter spaces of the two canonical models of infectious disease epidemiology-the Susceptible-Infectious-Susceptible (SIS) and Susceptible-Infectious-Removed (SIR) models. The results from these simulations are compared to reference data where we eliminate structures in the interevent intervals, the time to the first contact in the data, or the time from the last contact to the end of the sampling. The picture we find is that the birth and death of links, and the total number of contacts over a link, are essential to predict outbreaks. On the other hand, the exact times of contacts between the beginning and end, or the interevent interval distribution, do not matter much. In other words, a simplified picture of these empirical data sets that suffices for epidemiological purposes is that links are born, is active with some intensity, and die.

  • 19. Holme, Petter
    et al.
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Edling, Christofer R
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Kim, Beom Jun
    Network bipartivity.2003Inngår i: Phys Rev E Stat Nonlin Soft Matter Phys, ISSN 1539-3755, Vol. 68, nr 5 Pt 2, s. 056107-Artikkel i tidsskrift (Annet vitenskapelig)
  • 20. Kitsak, Maksim
    et al.
    Gallos, Lazaros K.
    Havlin, Shlomo
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Muchnik, Lev
    Stanley, H. Eugene
    Makse, Hernan A.
    Identification of influential spreaders in complex networks2010Inngår i: Nature Physics, ISSN 1745-2473, E-ISSN 1745-2481, Vol. 6, nr 11, s. 888-893Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Networks portray a multitude of interactions through which people meet, ideas are spread and infectious diseases propagate within a society(1-5). Identifying the most efficient 'spreaders' in a network is an important step towards optimizing the use of available resources and ensuring the more efficient spread of information. Here we show that, in contrast to common belief, there are plausible circumstances where the best spreaders do not correspond to the most highly connected or the most central people(6-10). Instead, we find that the most efficient spreaders are those located within the core of the network as identified by the k-shell decomposition analysis(11-13), and that when multiple spreaders are considered simultaneously the distance between them becomes the crucial parameter that determines the extent of the spreading. Furthermore, we show that infections persist in the high-k shells of the network in the case where recovered individuals do not develop immunity. Our analysis should provide a route for an optimal design of efficient dissemination strategies.

  • 21. Lee, Sungmin
    et al.
    Rocha, Luis E. C.
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Holme, Petter
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Exploiting Temporal Network Structures of Human Interaction to Effectively Immunize Populations2012Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, nr 5, s. e36439-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Decreasing the number of people who must be vaccinated to immunize a community against an infectious disease could both save resources and decrease outbreak sizes. A key to reaching such a lower threshold of immunization is to find and vaccinate people who, through their behavior, are more likely than average to become infected and to spread the disease further. Fortunately, the very behavior that makes these people important to vaccinate can help us to localize them. Earlier studies have shown that one can use previous contacts to find people that are central in static contact networks. However, real contact patterns are not static. In this paper, we investigate if there is additional information in the temporal contact structure for vaccination protocols to exploit. We answer this affirmative by proposing two immunization methods that exploit temporal correlations and showing that these methods outperform a benchmark static-network protocol in four empirical contact datasets under various epidemic scenarios. Both methods rely only on obtainable, local information, and can be implemented in practice. For the datasets directly related to contact patterns of potential disease spreading ( of sexually-transmitted and nosocomial infections respectively), the most efficient protocol is to sample people at random and vaccinate their latest contacts. The network datasets are temporal, which enables us to make more realistic evaluations than earlier studies-we use only information about the past for the purpose of vaccination, and about the future to simulate disease outbreaks. Using analytically tractable models, we identify two temporal structures that explain how the protocols earn their efficiency in the empirical data. This paper is a first step towards real vaccination protocols that exploit temporal-network structure-future work is needed both to characterize the structure of real contact sequences and to devise immunization methods that exploit these.

  • 22.
    Liljeros, Fredrik
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Edling, Christofer
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Amaral, L A
    Stanley, H E
    Aberg, Y
    The web of human sexual contacts.2001Inngår i: Nature, ISSN 0028-0836, Vol. 411, nr 6840, s. 907-8Artikkel i tidsskrift (Annet vitenskapelig)
  • 23.
    Liljeros, Fredrik
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Edling, Christofer
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Nunes Amaral, Luis A
    Sexual networks: implications for the transmission of sexually transmitted infections.2003Inngår i: Microbes Infect, ISSN 1286-4579, Vol. 5, nr 2, s. 189-96Artikkel i tidsskrift (Annet vitenskapelig)
  • 24.
    Liljeros, Fredrik
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Holme, Petter
    Giesecke, Johan
    The contact network of inpatients in a regional healthcare system. A longitudinal case study2007Inngår i: Mathematical Population Studies, Vol. 14, nr 4, s. 269-284Artikkel i tidsskrift (Fagfellevurdert)
  • 25.
    Lu, Xin
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Bengtsson, Linus
    Britton, Tom
    Stockholms universitet, Naturvetenskapliga fakulteten, Matematiska institutionen.
    Camitz, Martin
    Kim, Beom Jun
    Thorson, Anna
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    The sensitivity of respondent-driven sampling2012Inngår i: Journal of the Royal Statistical Society: Series A (Statistics in Society), ISSN 0964-1998, E-ISSN 1467-985X, Vol. 175, nr 1, s. 191-216Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Researchers in many scientific fields make inferences from individuals to larger groups. For many groups, however, there is no list of members from which to draw a random sample. Respondent-driven sampling (RDS) is a relatively new sampling methodology that circumvents this difficulty by using the social networks of the groups under study. The RDS method has been shown to provide unbiased estimates of population proportions given certain conditions. The method is now widely used in human immunodeficiency virus related studies among high risk populations globally. We test the RDS methodology by simulating RDS studies on the social networks of a large Lesbian, gay, bisexual and transgender Web community. The robustness of the RDS method is tested by violating, one by one, the conditions under which the method provides unbiased estimates. Simulations indicate that the bias is large if networks are directed or respondents choose to invite people on the basis of characteristics that are correlated with the study outcomes. The bias and variance increase if participants invite close as opposed to more distant friends whereas sampling in denser networks sharply reduces variance. However, the RDS method shows strong resistance to sampling without replacement, low response rates and certain errors in the participants reporting of their network sizes, as well as the selection criteria of seeds. The effects of network structure and the number of seeds and coupons are also discussed.

  • 26.
    Lu, Xin
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen. Karolinska Institutet, Sweden; National University of Defense Technology, China.
    Malmros, Jens
    Stockholms universitet, Naturvetenskapliga fakulteten, Matematiska institutionen.
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Britton, Tom
    Stockholms universitet, Naturvetenskapliga fakulteten, Matematiska institutionen.
    Respondent-driven sampling on directed networks2013Inngår i: Electronic Journal of Statistics, ISSN 1935-7524, E-ISSN 1935-7524, Vol. 7, s. 292-322Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Respondent-driven sampling (RDS) is a widely used method for generating chain-referral samples from hidden populations. It is an extension of the snowball sampling method and can, given that some assumptions are met, generate unbiased population estimates. One key assumption, not likely to be met, is that the acquaintance network in which the recruitment process takes place is undirected, meaning that all recruiters should have the potential to be recruited by the person they recruit. Using a mean-field approach, we develop an estimator which is based on prior information about the average indegrees of estimated variables. When the indegree is known, such as for RDS studies over internet social networks, the estimator can greatly reduce estimate error and bias as compared with current methods; when the indegree is not known, which is most common for interview-based RDS studies, the estimator can through sensitivity analysis be used as a tool to account for uncertainties of network directedness and error in self-reported degree data. The performance of the new estimator, together with previous RDS estimators, is investigated thoroughly by simulations on networks with varying structures. We have applied the new estimator on an empirical RDS study for injecting drug users in New York City.

  • 27.
    Malmros, Jens
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Matematiska institutionen.
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Britton, Tom
    Stockholms universitet, Naturvetenskapliga fakulteten, Matematiska institutionen.
    Respondent-driven sampling and an unusual epidemic2016Inngår i: Journal of Applied Probability, ISSN 0021-9002, E-ISSN 1475-6072, Vol. 53, nr 2, s. 518-540Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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.

  • 28. Min, Byungjoon
    et al.
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen. Institute for Futures Study, Stockholm, Sweden.
    Makse, Hernan A.
    Finding Influential Spreaders from Human Activity beyond Network Location2015Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, nr 8, artikkel-id e0136831Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Most centralities proposed for identifying influential spreaders on social networks to either spread a message or to stop an epidemic require the full topological information of the network on which spreading occurs. In practice, however, collecting all connections between agents in social networks can be hardly achieved. As a result, such metrics could be difficult to apply to real social networks. Consequently, a new approach for identifying influential people without the explicit network information is demanded in order to provide an efficient immunization or spreading strategy, in a practical sense. In this study, we seek a possible way for finding influential spreaders by using the social mechanisms of how social connections are formed in real networks. We find that a reliable immunization scheme can be achieved by asking people how they interact with each other. From these surveys we find that the probabilistic tendency to connect to a hub has the strongest predictive power for influential spreaders among tested social mechanisms. Our observation also suggests that people who connect different communities is more likely to be an influential spreader when a network has a strong modular structure. Our finding implies that not only the effect of network location but also the behavior of individuals is important to design optimal immunization or spreading schemes.

  • 29.
    Mondani, Hernan
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Holme, Petter
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen. Sungkyunkwan University, South Korea; Umeå University, Sweden; Institute for Future Studies, Sweden.
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen. Institute for Future Studies, Sweden.
    Fat-Tailed Fluctuations in the Size of Organizations: The Role of Social Influence2014Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, nr 7, artikkel-id e100527Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Organizational growth processes have consistently been shown to exhibit a fatter-than-Gaussian growth-rate distribution in a variety of settings. Long periods of relatively small changes are interrupted by sudden changes in all size scales. This kind of extreme events can have important consequences for the development of biological and socio-economic systems. Existing models do not derive this aggregated pattern from agent actions at the micro level. We develop an agent-based simulation model on a social network. We take our departure in a model by a Schwarzkopf et al. on a scale-free network. We reproduce the fat-tailed pattern out of internal dynamics alone, and also find that it is robust with respect to network topology. Thus, the social network and the local interactions are a prerequisite for generating the pattern, but not the network topology itself. We further extend the model with a parameter delta that weights the relative fraction of an individual's neighbours belonging to a given organization, representing a contextual aspect of social influence. In the lower limit of this parameter, the fraction is irrelevant and choice of organization is random. In the upper limit of the parameter, the largest fraction quickly dominates, leading to a winner-takes-all situation. We recover the real pattern as an intermediate case between these two extremes.

  • 30.
    Nordvik, Monica K
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Osterlund, Anders
    Herrmann, Björn
    Spatial bridges and the spread of Chlamydia: the case of a county in Sweden.2007Inngår i: Sex Transm Dis, ISSN 0148-5717, Vol. 34, nr 1, s. 47-53Artikkel i tidsskrift (Fagfellevurdert)
  • 31. Pei, Sen
    et al.
    Morone, Flaviano
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Makse, Hernán
    Shaman, Jeffrey L.
    Inference and control of the nosocomial transmission of methicillin-resistant Staphylococcus aureus2018Inngår i: eLIFE, E-ISSN 2050-084X, Vol. 7, artikkel-id e40977Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Methicillin-resistant Staphylococcus aureus (MRSA) is a continued threat to human health in both community and healthcare settings. In hospitals, control efforts would benefit from accurate estimation of asymptomatic colonization and infection importation rates from the community. However, developing such estimates remains challenging due to limited observation of colonization and complicated transmission dynamics within hospitals and the community. Here, we develop an inference framework that can estimate these key quantities by combining statistical filtering techniques, an agent-based model, and real-world patient-to-patient contact networks, and use this framework to infer nosocomial transmission and infection importation over an outbreak spanning 6 years in 66 Swedish hospitals. In particular, we identify a small number of patients with disproportionately high risk of colonization. In retrospective control experiments, interventions targeted to these individuals yield a substantial improvement over heuristic strategies informed by number of contacts, length of stay and contact tracing.

  • 32.
    Rocha, L.E.C..
    et al.
    Umeå universitet. Institutionen för fysik.
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Holme, Petter
    Sungkyunkwan University. South Korea. partment of Energy Science.
    Information dynamics shape the sexual networks of Internet-mediated prostitution2010Inngår i: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 107, nr 13, s. 5706-5711Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Like many other social phenomena, prostitution is increasingly coordinated over the Internet. The online behavior affects the offline activity; the reverse is also true. We investigated the reported sexual contacts between 6,624 anonymous escorts and 10,106 sex buyers extracted from an online community from its beginning and six years on. These sexual encounters were also graded and categorized (in terms of the type of sexual activities performed) by the buyers. From the temporal, bipartite network of posts, we found a full feedback loop in which high grades on previous posts affect the future commercial success of the sex worker, and vice versa. We also found a peculiar growth pattern in which the turnover of community members and sex workers causes a sublinear preferential attachment. There is, moreover, a strong geographic influence on network structure-the network is geographically clustered but still close to connected, the contacts consistent with the inverse-square law observed in trading patterns. We also found that the number of sellers scales sublinearly with city size, so this type of prostitution does not, comparatively speaking, benefit much from an increasing concentration of people.

  • 33. Rocha, Luis E. C.
    et al.
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Holme, Petter
    Simulated Epidemics in an Empirical Spatiotemporal Network of 50,185 Sexual Contacts2011Inngår i: PloS Computational Biology, ISSN 1553-734X, E-ISSN 1553-7358, Vol. 7, nr 3, s. e1001109-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sexual contact patterns, both in their temporal and network structure, can influence the spread of sexually transmitted infections (STI). Most previous literature has focused on effects of network topology; few studies have addressed the role of temporal structure. We simulate disease spread using SI and SIR models on an empirical temporal network of sexual contacts in high-end prostitution. We compare these results with several other approaches, including randomization of the data, classic mean-field approaches, and static network simulations. We observe that epidemic dynamics in this contact structure have well-defined, rather high epidemic thresholds. Temporal effects create a broad distribution of outbreak sizes, even if the per-contact transmission probability is taken to its hypothetical maximum of 100%. In general, we conclude that the temporal correlations of our network accelerate outbreaks, especially in the early phase of the epidemics, while the network topology (apart from the contact-rate distribution) slows them down. We find that the temporal correlations of sexual contacts can significantly change simulated outbreaks in a large empirical sexual network. Thus, temporal structures are needed alongside network topology to fully understand the spread of STIs. On a side note, our simulations further suggest that the specific type of commercial sex we investigate is not a reservoir of major importance for HIV.

  • 34. Rocha, Luis E. C.
    et al.
    Thorson, Anna E.
    Lambiotte, Renaud
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen. Stockholm Univ, Stockholm, Sweden.
    Respondent-driven sampling bias induced by community structure and response rates in social networks2017Inngår i: Journal of the Royal Statistical Society: Series A (Statistics in Society), ISSN 0964-1998, E-ISSN 1467-985X, Vol. 180, nr 1, s. 99-118Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sampling hidden populations is particularly challenging by using standard sampling methods mainly because of the lack of a sampling frame. Respondent-driven sampling is an alternative methodology that exploits the social contacts between peers to reach and weight individuals in these hard-to-reach populations. It is a snowball sampling procedure where the weight of the respondents is adjusted for the likelihood of being sampled due to differences in the number of contacts. The structure of the social contacts thus regulates the process by constraining the sampling within subregions of the network. We study the bias induced by network communities, which are groups of individuals more connected between themselves than with individuals in other groups, in the respondent-driven sampling estimator. We simulate different structures and response rates to reproduce real settings. We find that the prevalence of the estimated variable is associated with the size of the network community to which the individual belongs and observe that low degree nodes may be undersampled if the sample and the network are of similar size. We also find that respondent-driven sampling estimators perform well if response rates are relatively large and the community structure is weak, whereas low response rates typically generate strong biases irrespectively of the community structure.

  • 35.
    Rostami, Amir
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen. Institute for Futures Studies, Sweden.
    Mondani, Hernan
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen. Institute for Futures Studies, Sweden.
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Edling, Christofer
    Criminal organizing applying the theory of partial organization to four cases of organized crime2018Inngår i: Trends in Organized Crime, ISSN 1084-4791, E-ISSN 1936-4830, Vol. 21, nr 4, s. 315-342Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We explore how the idea of partial organization can provide insights in the study of organized crime. Studying criminal organizing with a theoretical framework used for other social organizing phenomena can help us see the interplay between different forms of criminal collaboration under a single analytical lens, and start a discussion on whether criminal organizing is intrinsically different from other types of social organizing. We analyze four cases of criminal collaboration in Sweden between 1990 and 2015: the Syriac mafia, the Hells Angels Mc Sweden, the street gang Werewolf Legion, and the Hallunda robbery. While the outlaw motorcycle gang, and to a certain extent the street gang, are complete organizations, the mafia is based around and heavily parasitic on other institutions. We have also shown that time-bounded projects are found in the criminal context, with these emerging from strong network relations. Our results show that most of the elements of criminal organizing are not formalized and that partial organization is at least as important and powerful as complete organization.

  • 36. Rybski, D.
    et al.
    Buldyrev, S. V.
    Havlin, S.
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Makse, H. A.
    Communication activity in social networks: growth and correlations2011Inngår i: European Physical Journal B: Condensed Matter Physics, ISSN 1434-6028, E-ISSN 1434-6036, Vol. 84, nr 1, s. 147-159Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigate the timing of messages sent in two online communities with respect to growth fluctuations and long-term correlations. We find that the timing of sending and receiving messages comprises pronounced long-term persistence. Considering the activity of the community members as growing entities, i.e. the cumulative number of messages sent (or received) by the individuals, we identify non-trivial scaling in the growth fluctuations which we relate to the long-term correlations. We find a connection between the scaling exponents of the growth and the long-term correlations which is supported by numerical simulations based on peaks over threshold. In addition, we find that the activity on directed links between pairs of members exhibits long-term correlations, indicating that communication activity with the most liked partners may be responsible for the long-term persistence in the timing of messages. Finally, we show that the number of messages, M, and the number of communication partners, K, of the individual members are correlated following a power-law, K similar to M (lambda) , with exponent lambda a parts per thousand 3 / 4.

  • 37. Rybski, Diego
    et al.
    Buldyrev, Sergey V.
    Havlin, Shlomo
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen. Institute for Futures Studies, Sweden.
    Makse, Hernán A.
    Communication activity in a social network: relation between long-term correlations and inter-event clustering2012Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 2, artikkel-id 560Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Human communication in social networks is dominated by emergent statistical laws such as non-trivial correlations and temporal clustering. Recently, we found long-term correlations in the user's activity in social communities. Here, we extend this work to study the collective behavior of the whole community with the goal of understanding the origin of clustering and long-term persistence. At the individual level, we find that the correlations in activity are a byproduct of the clustering expressed in the power-law distribution of inter-event times of single users, i.e. short periods of many events are separated by long periods of no events. On the contrary, the activity of the whole community presents long-term correlations that are a true emergent property of the system, i.e. they are not related to the distribution of inter-event times. This result suggests the existence of collective behavior, possibly arising from nontrivial communication patterns through the embedding social network.

  • 38. Rybski, Diego
    et al.
    Buldyrev, Sergey V
    Havlin, Shlomo
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Makse, Hernán A
    Scaling laws of human interaction activity2009Inngår i: Proceedings of the National Academy of Sciences of the United States of America, ISSN 1091-6490, Vol. 106, nr 31, s. 12640-5Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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.

  • 39. Strömdahl, Susanne
    et al.
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Ekéus Thorson, Anna
    Ingemarsdotter Persson, Kristina
    Forsberg, Birger C.
    HIV testing and prevention among foreign-born Men Who have Sex with Men: an online survey from Sweden2017Inngår i: BMC Public Health, ISSN 1471-2458, E-ISSN 1471-2458, Vol. 17, artikkel-id 139Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: There is an increasing trend toward international migration worldwide. With it comes a challenge for public health and public funded health care systems to meet the migrating population's health needs. Men who have sex with men are a key population for HIV, contributing an estimated 42% of new HIV cases in Europe in 2013. HIV monitoring data suggest that foreign-born MSM are not only exposed to a high risk of HIV before migration but also while living in Sweden. The aim of this study is to examine HIV testing prevalence and uptake of HIV prevention interventions among foreign-born MSM living in Sweden.

    Methods: A web survey available in English and Swedish was conducted from October 1 to October 30, 2013 via a Scandinavian Web community for Lesbian, Gay, Bisexual, Transgender and Intergender people. The web survey included modules on sociodemographics, condom use, sexual risk behaviour and HIV/STI testing experience. 244 eligible MSM participants born abroad and living in Sweden participated in the study. Descriptive and inferential analysis was performed.

    Results: Half of the foreign-born MSM participants in this study had been tested for HIV during the last 12 months. Participants who had lived in Sweden less than or equal to 5 years were more likely to have been tested for HIV during the last 12 months. Having talked about HIV/STI with a prevention worker during the past year was associated with having been tested for HIV. Requested services among the majority of participants were HIV rapid test, anonymous HIV testing, HIV/STI testing outside of the health care setting and MSM-friendly clinics.

    Conclusion: Efforts are needed to promote HIV testing among foreign-born MSM. Peer outreach, individual and group counselling may be preferred interventions to do so. In addition, it is critically important to increase HIV testing among foreign-born MSM who have lived in Sweden for more than five years. Further research should explore if scale up of implementation of requested services may increase frequency of HIV testing and detection of new cases linked to treatment among foreign-born MSM living in Sweden.

  • 40. Strömdahl, Susanne
    et al.
    Lu, Xin
    Bengtsson, Linus
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Thorson, Anna
    Implementation of Web-Based Respondent Driven Sampling among Men Who Have Sex with Men in Sweden2015Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, nr 10, artikkel-id e0138599Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background Respondent driven sampling (RDS) was designed to study 'hidden' populations, for which there are no available sampling frame. RDS has been shown to recruit far into social networks of the study population and achieve unbiased estimates when certain assumptions are fulfilled. Web-based respondent driven sampling (WebRDS) has been implemented among MSM in Vietnam and produced a sufficient sample of MSM. In order to see if WebRDS could work in a 'hidden' population in a high-income setting, we performed a WebRDS among MSM in Sweden to study a sensitive topic, sexual risk behaviour for HIV/STI and Internet use. Methods A cross-sectional survey was implemented between July 11, 2012 and January 21, 2013 by using a WebRDS software. Men, fifteen years old or above, who reported having ever had sex with another man were included. The web-survey explored sociodemographics, sexual risk behaviour for HIV/STI and Internet use. Results The WebRDS process created a sample of 123 eligible respondents. The mean age among participants was 32 years old. All respondents reported having had unprotected anal intercourse (UAI) with at least one regular and one casual sex partner during the last 12 months. On average participants reported having had UAI with three casual sexual partners and in total having had seven casual sex partners during the last 12 months. Conclusion The WebRDS produced a sample of Internet-using MSM in Sweden who all reported sexual risk behaviour for HIV/STI during the last 12 months. It holds promise for future online studies among MSM and a possibility to reach MSM at risk for HIV/STI with interventions or information. Some challenges were found including short recruitment chains, and further research need to address how to optimize WebRDS online recruitment methods in high income settings.

  • 41. Tumminello, Michele
    et al.
    Edling, Christofer
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen. Institute for Futures Studies, Sweden.
    Mantegna, Rosario N.
    Sarnecki, Jerzy
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Kriminologiska institutionen.
    The Phenomenology of Specialization of Criminal Suspects2013Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, nr 5, artikkel-id e64703Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A criminal career can be either general, with the criminal committing different types of crimes, or specialized, with the criminal committing a specific type of crime. A central problem in the study of crime specialization is to determine, from the perspective of the criminal, which crimes should be considered similar and which crimes should be considered distinct. We study a large set of Swedish suspects to empirically investigate generalist and specialist behavior in crime. We show that there is a large group of suspects who can be described as generalists. At the same time, we observe a non-trivial pattern of specialization across age and gender of suspects. Women are less prone to commit crimes of certain types, and, for instance, are more prone to specialize in crimes related to fraud. We also find evidence of temporal specialization of suspects. Older persons are more specialized than younger ones, and some crime types are preferentially committed by suspects of different ages.

  • 42. Villani, Antonella
    et al.
    Frigessi, Arnoldo
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen. Sweden, Institute for Future Studies, Sweden.
    Nordvik, Monica K.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen. Mid Sweden University, Sweden.
    de Blasio, Birgitte Freiesleben
    A Characterization of Internet Dating Network Structures among Nordic Men Who Have Sex with Men2012Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, nr 7, artikkel-id e39717Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: The Internet has become an important venue for seeking sexual partners and may facilitate transmission of sexually transmitted infections. Methods: We examined a 64-day data log of flirt messages expressing sexual interest among MSM within the Qruiser. com community. We used logistic regression to analyze characteristics of MSM sending and receiving flirt messages and negative binomial regression to examine individual activity and popularity. The structural properties, including the core structure of the flirt network, were analyzed. Results: The MSM population consisted of approximately 40% homosexuals and 37% bisexuals, while the remaining 23% included men who identified as heterosexual but searched for sex with men and experimental. MSM were more likely to send flirt messages if they were homosexual and aged 40+ years; young people aged, 30 years were more likely to receive a flirt. Possession of a webcam was strongly associated with both sending flirt messages and being a flirt target. The distributions of flirts sent (max k(out) = 2162) and received (max k(in) = 84) were highly heterogeneous. Members in central cores were more likely homosexuals, singles, and aged 31-40 years. The probability of a matched flirt (flirt returned from target) increased from 1% in the outer core to 18% in the central core (core size = 4). Discussion: The flirt network showed high degree heterogeneity similar to the structural properties of real sexual contact networks with a single central core. Further studies are needed to explore use of webcam for Internet dating.

  • 43. Whitehead, Paul D.
    et al.
    Liljeros, Fredrik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    Heavy-Tailed Distribution of Seclusion and Restraint Episodes in a State Psychiatric Hospital2011Inngår i: The journal of the American Academy of Psychiatry and the Law, ISSN 1093-6793, E-ISSN 1943-3662, Vol. 39, nr 1, s. 93-99Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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.

1 - 43 of 43
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf