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This article explores the change over time of boys’ and girls’ attitudes towards biology, physics and chemistry. We use data from the TIMSS studies for grade 8 in Sweden to investigate how the attitudes for high- and low performing pupils have changed between 1995 and 2007. The attitude is measured by four questions from the student questionnaire in the TIMSS study. The results indicate that there have been some changes in attitudes between 1995 and 2007. High-achieving pupils and especially boys have a more negative attitude towards all three subjects, biology, physics and chemistry, in 2007 compared to 1995. The low-achieving students think that they are performing better in all three subjects 2007 compared to 1995. The difference between the group that are most positive to physics and chemistry and the least positive group has diminished between the two years. The results are discussed in relation to the changes in Swedish schools during the period.

Background and Purpose: The European Cooperative Acute Stroke Study (ECASS) III trial and Safe Implementation of Thrombolysis in Stroke–International Stroke Thrombolysis Register (SITS-ISTR) data were published in 2008. Riks-Stroke, the Swedish Stroke Register, was used to explore how thrombolysis in the 3- to 4.5-hour window has been spread in different hospitals and patient groups and what effects this has had on treatment within 3 hours.

Methods: All 76 hospitals in Sweden admitting patients with acute stroke participate in Riks-Stroke. During the study period, January 2003 to June 2010, 92 150 18- to 80-year-old patients were hospitalized for acute ischemic stroke.

Results: After the publication of the ECASS III results in the third quarter of 2008, thrombolysis in the 3- to 4.5-hour window increased from 0.5% before publication to 2.1% in 2010. Thrombolysis in the 3- to 4.5-hour window spread somewhat faster in men than women (P=0.04) but at a similar rate in different age groups. The use of thrombolysis within 3 hours after onset of symptoms increased successively from 0.9% in 2003 to 6.6% in late 2008 and then it stabilized at 6%. The median time from arrival to the hospital to start of treatment remained unchanged at 66 to 69 minutes before and after 2008 (P=0.06).

Conclusions: Since the end of 2008, there has been a rapid nationwide dissemination of thrombolysis in the 3- to 4.5-hour window, whereas rates in the <3-hour window have leveled off. The extended time window has not affected door-to-needle time.

Causality is an important but complicated issue, not only within social sciences in general but also within economic and historical demography. Here we are dealing with two different, but related, problems of causality. The first is to what extent the impact of food prices on mortality is biased when selecting on years with mortality crises. The second concerns the problem of mixing factors that directly and indirectly have an impact on mortality. Dealing with the first problem, we compare the effects of food prices on child and adult mortality when selecting on mortality crises with a standard approach without selection. When dealing with the second problem we use the additive hazards model, in combination with dynamic path analysis, which allows for investigating the mediating effect of intermediate covariates in a causal framework. We use individual level data from the Scanian Economic Demographic Database for five rural parishes for the period 1766 to 1865. Data on food prices refers to the local area of these parishes. The statistical analyses are performed in the R statistical computing environment, especially with the aid of the package eha. The main findings are that selecting on mortality crises created a large bias in the direction of overestimating the impact of food prices and that that the direct effects of food prices are dominating.

Childhood T1D increased dramatically and shifted to a younger age at onset the first 22 years of the study period. We report a reversed trend, starting in 2000, indicating a change in nongenetic risk factors affecting specifically young children.

Forest quantification methods have evolved from a simple graphical approach to complex regression models with stochastic structural components. Currently, mixed effects models methodology is receiving attention in the forestry literature. However, the review work (Paper I) indicates a tendency to overlook appropriate covariance structures in the NLME modeling process.

A nonlinear mixed effects modeling process is demonstrated in Paper II using Cupressus lustanica tree merchantable volume data and compared several models with and without covariance structures. For simplicity and clarity of the nonlinear mixed effects modeling, four phases of modeling were introduced. The nonlinear mixed effects model for C. lustanica tree merchantable volume with the covariance structures for both the random effects and within group errors has shown a significant improvement over the model with simplified covariance matrix. However, this statistical significance has little to explain in the prediction performance of the model.

In Paper III, using several performance indicator statistics, tree taper models were compared in an effort to propose the best model for the forest management and planning purpose of the C. lustanica plantations. Kozak's (1988) tree taper model was found to be the best for estimating C. lustanica taper profile.

Based on the Kozak (1988) tree taper model, a Ds optimal experimental design study is carried out in Paper IV. In this study, a Ds-optimal (sub) replication free design is suggested for the Kozak (1988) tree taper model.

In this work, we study Ds-optimal design for Kozak's tree taper model. The approximate Ds-optimal designs are found invariant to tree size and hence create a ground to construct a general replication-free Ds-optimal design. Even though the designs are found not to be dependent on the parameter value p of the Kozak's model, they are sensitive to the stimes1 subset parameter vector values of the model. The 12 points replication-free design (with 91% efficiency) suggested in this study is believed to reduce cost and time for data collection and more importantly to precisely estimate the subset parameters of interest.

This paper is focusing, first, on the very concept of aging, what does it mean for a population, and what does it mean to an individual. Second, on the individual level, is longevity clustered within certain families (family trees)?