5,476 research outputs found
Occurrence and management of oak in southern Swedish forests
This article describes the current proportions of forest types with oak (Quercus robur and Q. petraea) in southern Sweden, provides an overview of oak distribution over time and reviews literature about oak regeneration relevant for the region. Further we discuss silvicultural possibilities to maintain and promote oak in Scandinavia. In Götaland pure oak forest covers 1% of the forest area and mixed forest types with > 10% oak proportion cover approximately 10% of the area. Common types of mixture are spruce-oak and pine-oak forest. Both mixtures are frequent in mature forest, especially pine-oak. Additionally, about one third of spruce-oak mixtures can be found in medium-aged forest.
Intensive management would be necessary to promote single oak trees in old pine stands or spruce plantations, but the proportion of oak in coniferous forest provides some potential to maintain additional oak trees. The distribution of acorns by Jays, enhanced measures against browsing, and the release of single oak trees from competing tree species could help to maintain more oak trees for nature conservation. However, regarding management of oak for timber production, conventional methods are recommended. Planting after clear cutting of coniferous forest, or short shelter periods after mast years in oak stands, are established methods to regenerate pure oak stands. Another possibility to develop mature oak forest are mixed oak-spruce plantations, as traditionally practised in a small region in southern Sweden. The different approaches of oak management in Sweden were presented in April 2012 on the annual meeting of the section silviculture of DVFFA (German Union of Forest Research Organizations) in Wermsdorf near Leipzig to give an overview and access to recent forest research in Sweden
Recommended from our members
English-medium instruction in European higher education: review and future research.
The purpose of this volume has been to give an account of the status of English as a medium of instruction in various political, geographical and ideological contexts: Northern, Southern, Eastern, Western and Central Europe, regions at different stages of EMI implementation. It is our hope that the preceding chapters have given comparative insights into some of the discussions and issues associated with EMI in European higher education. While contributors have investigated a diverse set of empirical, pedagogical and political issues, many issues remain to be addressed in more detail. In these final few pages of the volume, we briefly review some of the main issues that have arisen in the preceding chapters and the broader EMI literature and propose further directions in methodological approaches, areas, and scopes
Unemployment Duration, Incentives and Institutions - A Micro-Econometric Analysis Based on Scandinavian Data
Based on a combined register database for Norwegian and Swedish unemployment spells, we use the ‘between-countries-variation’ in the unemployment insurance systems to identify causal effects. The elasticity of the job hazard rate with respect to the benefit replacement ratio is around -1.0 in Norway and -0.5 in Sweden. The limited benefit duration period in Sweden has a large positive impact on the hazard rate, despite generous renewal options through participation in labour market programs. Compulsory program participation seems to operate as a ‘stick’, rather than a ‘carrot’, and is therefore an efficient tool for counteracting moral hazard problems in the benefit system.Unemployment spells; unemployment compensation; non-parametric duration analysis.
Recommended from our members
Training the Fetal Immune System Through Maternal Inflammation-A Layered Hygiene Hypothesis.
Over the last century, the alarming surge in allergy and autoimmune disease has led to the hypothesis that decreasing exposure to microbes, which has accompanied industrialization and modern life in the Western world, has fundamentally altered the immune response. In its current iteration, the "hygiene hypothesis" suggests that reduced microbial exposures during early life restricts the production and differentiation of immune cells suited for immune regulation. Although it is now well-appreciated that the increase in hypersensitivity disorders represents a "perfect storm" of many contributing factors, we argue here that two important considerations have rarely been explored. First, the window of microbial exposure that impacts immune development is not limited to early childhood, but likely extends into the womb. Second, restricted microbial interactions by an expectant mother will bias the fetal immune system toward hypersensitivity. Here, we extend this discussion to hypothesize that the cell types sensing microbial exposures include fetal hematopoietic stem cells, which drive long-lasting changes to immunity
Observing Behavior of Fluid Flow through Carbon Nanotube Arrays
This work establishes a platform technique for visualizing fluid transport through Anoidisc Alumina Oxide (AAO) membranes, which can be applied to Carbon Nanotube (CNT) arrays, and allow for the testing of the effects of other parameters on flow. Arrays of CNTs have shown significant promise for delivering biomolecules into cells with high efficiency while maintaining cell viability. In these applications, biomolecules flow through CNT arrays manufactured in our lab using Template-Based Chemical Vapor Deposition. By culturing cells on the opposite side of the array, they can be used to transfect biomolecules into cells. In this research, it was discovered that the transfection rate was dependent on the type of biomolecule being delivered into the cells. It was also inferred that the number of CNTs the cells covered would affect the transfection rate. In order to characterize flow through the CNT arrays, an experiment was designed and conducted to test the effect of changing the number of active CNTs. Preliminary testing showed the occurrence of an unknown error in the CNT array manufacturing process which prevented material from flowing through the CNT arrays. As a result, the study was modified to characterize flow through AAO membranes, which serve as the template for the CNTs. To accomplish this, a flow device was developed which restricted flow to a predefined circular area. Three different diameters were tested 6 mm, 4 mm, and 2 mm. Flow data was taken using fluorescent dye, as it diffused through the AAO into a volume of water on the opposite side, fluorescent intensity would increase. This data was plotted against time and used to model flow for the three tested diameters. The results indicated that the total time for diffusion increased as the diameters decreased. However, the relationship between the number of exposed pores and the flow time were not directly related, meaning the amount of flow through one pore changes with the total number of exposed pores. Testing was also conducted regarding the development of a flow device designed with two distinct flow inlets to the CNT array. This was done to determine the future feasibility of administering two distinct solutions into groups of cells. It was concluded that these devices could successfully be used for that purpose
Characterisation of rag properties and their transport in wastewater pumps:Calibration of a discrete element rag model to simulate clogging effects
- …