Avancerad sökning

Visar resultat 1 - 5 av 99 avhandlingar som matchar ovanstående sökkriterier.

1. 1. Seed dormancy and germination in an ecological context : comparative studies of annual weeds

   Författare :Laila Karlsson; Per Milberg; Ken Thompson; Linköpings universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Asteraceae; Bidens; Compositae; deadnettle; Galinsoga; germination timing; Guizotia; evolution; Labiatae; Lamiaceae; Lamium; morphophysiological dormancy; Papaveraceae; Papaver; Parthenium; physiological dormancy; poppy; summer annual; Tagetes; Verbesina; winter annual; Biology; Biologi;

   Sammanfattning : Germination ecology studies, i.e. studies of interactions between characteristics of the seeds and environmental circumstances, provide understanding of spatial and temporal patterns of emergence of wild species, as weeds in the field. A large number of species have seed dormancy, i. LÄS MER

3. 2. Indirect effects of unemployment and low earnings : Crime and children's school performance

   Författare :Anna Nilsson; Jonas Agell; Rudolf Winter-Ebmer; Stockholms universitet; []
   Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; Economics; Nationalekonomi;

   Sammanfattning : This thesis consists of three self-contained essays that consider indirect effects of unemployment and low earnings on crime and children’s school performance. The first essay, Crime, unemployment and labor market programs in turbulent times (joint with Jonas Agell), investigates the effect of unemployment and participation in labor market programs, in general and among youth, on Swedish crime rates using a new panel data set for Swedish municipalities for the period 1996-2000. LÄS MER

4. 3. Winter Road Maintenance using Renewable Thermal Energy

   Författare :Josef Johnsson; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Hydronic pavements; borehole thermal energy storage; winter road maintenance; BRIDGESIM; numerical simulations; BTES; renewable energy;

   Sammanfattning : Winter road maintenance is costly but it is inevitable since it is necessary to keep roads accessible and safe during winter. Current winter road maintenance methods use annually 600 000 tons of salt, in the Nordic countries. The salt ends up in the environment along the roads and results in environmental challenges. LÄS MER

5. 4. The effects of temperature on avian physiology, behavior and development

   Författare :Andreas Nord; Evolutionär ekologi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; clutch size; Cyanistes caeruleus; ecological immunology; energy expenditure; fever; Ficedula hypoleuca; heterothermy; hypothermia; incubation; life history; metabolic rate; Parus major; RMR; Taeniopygia guttata; temperature; winter;

   Sammanfattning : Temperature is a property of profound matter in all aspects of animal life, affecting both individual energy budgets and the environments in which animals reside. Thus, a proper understanding of the effects of temperature variation is instrumental in understanding not only animal form and function, but also the structure and dynamics of wild populations. LÄS MER

7. 5. Sphagnum limits : Physiology, morphology and climate

   Författare :Charles Campbell; Håkan Rydin; Gustaf Granath; Sebastian Sundberg; Bengt-Gunnar Jonsson; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Sphagnum; ecology; bryophyte; winter; species distribution models; low temperature; plant structure; water economy; Biology with specialization in Ecological Botany; Biologi med inriktning mot ekologisk botanik;

   Sammanfattning : Sphagnum is the most important plant genus in terms of terrestrial carbon cycling. It and the habitats it creates store an equivalent of ~68% of the CO2 in the atmosphere. The genus has little dispersal limitation and the mire habitats are functionally similar at global scales. LÄS MER