Evidence for Gluon Recombination in Deep Inelastic Scattering

The pomeron structure function is extracted from the latest H1 data and are subject to a QCD analysis. The result shows evidence for gluon recombination.Comment: 8 pages, 5 figure

Growth allocation and stand structure in Norway spruce stands

This thesis is based on analyses of permanent sample plot data gathered over periods of 10-34 years from an experiment in which a wide range of thinning regimes, and thinnings combined with N-fertilisation, were applied to 25 even-aged Norway spruce (Picea abies (L.) Karst.) stands in southern Sweden (56-63 No). At the start of the experiment, before the first thinning, the dominant height was 12-18 m. The overall objective was to evaluate the extent to which growth allocation along the bole and the stand structure of Picea abies stands can be controlled by different silvicultural regimes. To do this the data were used in four studies to evaluate the impact of: thinning and N-fertilisation on stem form and taper (Study I); different thinning regimes on the removal and growth in the diameter at breast height (DBH) of individual stems (Studies II and III); and the thinning regimes on the growth in mean DBH of four classes of the largest stems by DBH ha 1 (Study IV). The studies (ii) and (iii) form a growth model. In stands subjected to different thinning regimes, one model predicts which individual trees will remain at future points in time and an associated model predicts the future DBH of the remaining stems. Separate models were developed for stands thinned from below, stands thinned from above and unthinned stands. In Study IV the actual and genuine increases in the arithmetic mean DBH of the 100, 200, 300 and 400 largest stems by DBH ha 1 associated with six different thinning regimes in periods up to 35 years were compared to the corresponding stems in unthinned stands. The goals of achieving rapid diameter growth and low stem tapering cannot be attained simultaneously as heavy thinnings cause increased tapering, and thus silvicultural regimes must reflect a compromise between these and other production objectives. Trees in thinned and N-fertilised stands had the same taper as trees in equally thinned, unfertilised stands. Heavy thinnings from below promote high frequencies of thick stems and extra heavy thinnings promote high frequencies of extra thick stems. Thinning from above (or no thinnngs) may be an alternative to thinning from below in situations where a main crop consisting of moderately thick stems would be regarded as a satisfactory outcome. The actual mean DBH of larger stems can be increased, compared to the corresponding stems in unthinned stands, by up to 2.6 mm per year if extra heavy thinnings are carried out. The biological response to thinning of thick stems is influenced by the thinning intensity but not by the thinning method. The variation in DBH increases over time but increases more in stands thinned from above and unthinned stands than in stands thinned from below

Educational Attainment and Family Background

This paper analyses the effect of aspects of family background, such as family income and parental education, on the educational attainment of persons born from 1967 to 1972. Family income is measured at different periods of a child’s life to separate longterm versus short-term effects of family income on educational choices. We find that permanent income matters to a certain degree, and that family income when the child is 0-6 years old is an important explanatory variable for educational attainment later in a child’s life. We find that short-term credit constraints have only a small effect on educational attainment. Long term factors, such as permanent family income and parental education are much more important for educational attainment than are shortterm credit constraints. Public interventions to alleviate the effects of family background should thus also be targeted at a child's early years, the shaping period for the cognitive and non-cognitive skills important later in life.credit constraints; education; Norway; family background

Has Job Stability Decreased in Norway?

A widespread belief in the popular press is that job stability has declined across Western economies over the last 15 years. However, little support for this is found in the empirical literature. We use an extensive employer–employee data set for Norway to analyse changes in job stability in Norway by first presenting descriptive measures of job stability for manufacturing, the public sector and private services. Both descriptive analyses of tenure, hire and separation rates as well as regression-adjusted measures controlling for changes in demographics and the business cycle, indicate a slight decrease in job stability in Norway driven by increased job separation rates. These changes are not equally distributed across sectors or sub-groups of workers. However, we do not find that this tendency towards less stable jobs led to an increase in job-to-unemployment/out of the labour force; rather it was characterized by more job-to-job changes.Job stability; employer-employee data.

Measuring Heterogeneity in the Returns to Education in Norway Using Educational Reforms

The decision to take more education is complex, and is influenced by individual ability, financial constraints, family background, preferences, etc. Such factors, normally unobserved by the researcher, introduce endogeneity and heterogeneity problems into estimating the returns to education. In this paper, these problems are addressed by estimating a comparative advantage model for schooling, in which the returns to education vary at different levels of education. The model requires that instruments must be specified at each level of education, and we suggest that different school reforms in Norway can serve as suitable instruments. In particular, we exploit the staged implementation of a major reform in the comprehensive school system in the 1960s. We find that the returns to education are strongly nonlinear. In particular, we find that the returns to upper secondary school and shorter programs at regional colleges, together with master’s programs at universities, have high returns as measured by wages. Also, we find that the average treatment effect is surprisingly high for medium-length educations (up to two years of college education). This means that increasing the general level of education, which was the intention of the comprehensive school reform of the 1960s and of other school reforms, has the potential to generate a high return in wages, although we do not consider the cost to society. We also find that there is a substantial difference between the average treatment effect and the effect of treatment on the treated for bachelor’s and master’s degrees at universities.Cross-Sectional Models; Spatial Models; Treatment Effect Models; Quantile Regressions; Social Interaction Models (Updated); Analysis of Education