Atopic dermatitis in adults: a population - based study in Finland

Background The prevalence of atopic dermatitis (AD) has increased, but studies in adult or elderly populations are sparse. Methods We investigated 12-month and lifetime prevalences of AD in the Finnish adult population ≥30 years of age and analyzed living environment factors, socioeconomic factors, lifestyle-related factors, and serum vitamin D levels for their associations with AD in a national health examination survey. Results The lifetime prevalence was 21.9% and 12-month prevalence 10.1%. The highest prevalence (lifetime 28.6%, 12-month 15.4%) was seen in subjects 30-39 years of age. Prevalence decreased with age. Subjects with highly educated parents were more likely to have active AD, though there was no effect of higher education in subjects themselves. Younger age and being an ex-smoker were associated with active AD. Female sex and daily smoking increased the risk in subjects 30-49 years of age. There was no dose– response relationship to serum vitamin D levels and no association with the living environment. Conclusions Our data show that the number of adult patients with atopic dermatitis has grown and prevalence numbers of AD in Finnish adults are among the highest reported. Together with the aging of the society, the burden of AD is not limited to childhood.Peer reviewe

Modelling the Population Dynamics and the File Availability in a BitTorrent-Like P2P System with Decreasing Peer Arrival Rate

Abstract. Many measurement studies of P2P file sharing systems sug-gest that the request rate for a file changes over time and the system is thus non-stationary. For this reason we study the population dynam-ics and the availability of a file in a BitTorrent-like file sharing system, when the arrival rate for file requests decreases exponentially. We study the system first by a deterministic fluid model and then by a more de-tailed Markov chain analysis that allows estimating the life time of a single chunk exactly. Simple approximation for the life time is also de-rived. In addition, we simulate the life time of a file consisting multiple chunks in order to verify the analytical results to be applicable also to a more complex system.

On the stability of two-chunk file-sharing systems

We consider five different peer-to-peer file sharing systems with two chunks, with the aim of finding chunk selection algorithms that have provably stable performance with any input rate and assuming non-altruistic peers who leave the system immediately after downloading the second chunk. We show that many algorithms that first looked promising lead to unstable or oscillating behavior. However, we end up with a system with desirable properties. Most of our rigorous results concern the corresponding deterministic large system limits, but in two simplest cases we provide proofs for the stochastic systems also.Comment: 19 pages, 7 figure

Estimation of traffic matrices for LRD traffic

The estimation of traffic matrices in a communications network on the basis of a set of traffic measurements on the network links is a well known problem, for which a number of solutions have been proposed when the traffic does not show dependence over time, as in the case of the Poisson process. However, extensive measurements campaigns conducted on IP networks have shown that the traffic exhibits long range dependence. Here two methods are proposed for the estimation of traffic matrices in the case of long range dependence, their asymptotic properties are studied, and their relative merits are compared

Review on the validity of self-report to assess work-related diseases

Self-report is an efficient and accepted means of assessing population characteristics, risk factors, and diseases. Little is known on the validity of self-reported work-related illness as an indicator of the presence of a work-related disease. This study reviews the evidence on (1) the validity of workers' self-reported illness and (2) on the validity of workers' self-assessed work relatedness of an illness. A systematic literature search was conducted in four databases (Medline, Embase, PsycINFO and OSH-Update). Two reviewers independently performed the article selection and data extraction. The methodological quality of the studies was evaluated, levels of agreement and predictive values were rated against predefined criteria, and sources of heterogeneity were explored. In 32 studies, workers' self-reports of health conditions were compared with the "reference standard" of expert opinion. We found that agreement was mainly low to moderate. Self-assessed work relatedness of a health condition was examined in only four studies, showing low-to-moderate agreement with expert assessment. The health condition, type of questionnaire, and the case definitions for both self-report and reference standards influence the results of validation studies. Workers' self-reported illness may provide valuable information on the presence of disease, although the generalizability of the findings is limited primarily to musculoskeletal and skin disorders. For case finding in a population at risk, e.g., an active workers' health surveillance program, a sensitive symptom questionnaire with a follow-up by a medical examination may be the best choice. Evidence on the validity of self-assessed work relatedness of a health condition is scarce. Adding well-developed questions to a specific medical diagnosis exploring the relationship between symptoms and work may be a good strateg