Search for dissertations about: "DDA"

Showing result 1 - 5 of 15 swedish dissertations containing the word DDA.

2. 1. Significance of N2 fixing planktonic symbioses for open ocean ecosystems

   Author : Marcus Stenegren; Rachel A. Foster; Agneta Andersson; Stockholms universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; nitrogen fixation; diazotrophs; symbiosis; DDA; cyanobacteria; qPCR; piecewise SEM; microarray; tropics; subtropics; marine; open ocean; Richelia; Calothrix; Marine Ecology; marin ekologi;

   Abstract : Di-nitrogen (N2) fixers, also called diazotrophs, are able to reduce atmospheric N2 into bioavailable nitrogen, giving them an advantage in open ocean regions with low dissolved inorganic nitrogen concentrations. The focus of this thesis are three lineages of symbiotic heterocystous filamentous types (het-1, het-2 and het-3), that associate with several genera of microalgae called diatoms (collectively referred to as Diatom Diazotroph Associations, DDAs). READ MORE

4. 2. Numerical Simulations of Plasmonic Nanostructures

   Author : Joan Alegret; Chalmers tekniska högskola; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; nanoholes; DDA; Green s tensor; nanostructures; surface plasmons;

   Abstract : This thesis focuses on the study of metallic nanostructures that support plasmons. Special emphasis is devoted to two specific numerical methods that allow us to predict plasmon characteristics: the discrete dipole approximation (DDA) and the Green's tensor (GT) method. READ MORE

5. 3. Simulations of directionality effects and optical forces in plasmonic nanostructures

   Author : Vladimir Miljkovic; Chalmers tekniska högskola; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Comsol multiphysics; optical forces; nanoparticles; nanowires; DDA; surface plasmons; Green’s function; Mie theory;

   Abstract : With the rapid development of nanoscience and nanotechnology, surface plasmonics based on metal nanoparticles and nanostructures gain increasing interest, not only for fundamental scientific studies, but also for optical and sensor applications. At the nanoscale, the physical and chemical properties of metal particles, especially their optical properties, strongly depend on size and shape, as well as on the surrounding media and structures. READ MORE

6. 4. Environmental conditions governing the distributions of symbiotic and free-living diazotrophic cyanobacteria in two tropical open oceans

   Author : Marcus Stenegren; Rachel Foster; Bethany Jenkins; Stockholms universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Nitrogen fixation; Diazotroph; Cyanobacteria; Symbiosis; DDA; Richelia; Marine Ecology; marin ekologi;

   Abstract : Di-nitrogen (N2) fixation plays a crucial role in oceanic carbon and nitrogen cycles and is important for marine biogeochemistry on regional and global scales. N2-fixing (diazotrophs) cyanobacteria are considered to contribute the most to marine nitrogen fixation, and thereby fuel the surrounding phytoplankton communities with bioavailable ammonia. READ MORE

7. 5. Development of Differential Die-Away Instrument for Characterization of Swedish Spent Nuclear Fuel

   Author : Tomas Martinik; Sophie Grape; Peter Jansson; Göran Ericsson; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES;

   Abstract : The Next Generation Safeguards Initiative Spent Fuel (NGSI-SF) project was established in 2009 by the U.S. Departmentof Energy with main objective to investigate, and potentially develop and test new technologies for spent nuclearfuel (SNF) characterization. READ MORE