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General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Abstract Hutchinson's paradox of the plankton inspired many studies on the mechanisms of species coexistence. Recent laboratory experiments showed that partitioning of white light allows stable coexistence of red and green picocyanobacteria. Here, we investigate to what extent these laboratory findings can be extrapolated to natural waters. We predict from a parameterized competition model that the underwater light colour of lakes and seas provides ample opportunities for coexistence of red and green phytoplankton species. To test this prediction, we sampled picocyanobacteria of 70 aquatic ecosystems, ranging from clear blue oceans to turbid brown peat lakes. As predicted, red picocyanobacteria dominated in clear waters, whereas green picocyanobacteria dominated in turbid waters. We found widespread coexistence of red and green picocyanobacteria in waters of intermediate turbidity. These field data support the hypothesis that niche differentiation along the light spectrum promotes phytoplankton biodiversity, thus providing a colourful solution to the paradox of the plankton

APPLICATION OF AMORPHOUS SILICON BUFFER LAYERS TO INTERDIGITATED BACK CONTACTED SILICON HETEROJUNCTION SOLAR CELLS

We investigate different sets of deposition conditions of a Si H i layers used as buffer layers in both side contacted solar cells regarding the applicability to lt;100 gt; oriented surfaces. In accordance with other authors, we find that the passivation quality is very sensitive to the crystal orientation depending on the deposition conditions. Based on the observation of the annealing behavior we attribute a low passivation quality to low quality epitaxial growth. Varying the pressure in the chamber as well as the hydrogen flow and the deposition temperature we identify appropriate deposition conditions for reaching high Voc values on lt;100 gt; oriented surfaces present in our back contacted silicon heterojunction solar cells. It is shown that the Voc potential of emitter and back surface field layers significantly increases upon inclusion of the chosen buffer layers on symmetric lifetime samples. Including the buffer layers in emitter and back surface field layers in interdigitated back contacted solar cells, systematic improvement of the Voc can be observed, whereas the values lack behind expected values by about 50mV. We demonstrate that the contact layer consisting of aluminum is one source for masking the Voc potential of the intrinsic buffer layer

Magnetic phase diagram of the frustrated spin chain compound linarite PbCuSO4 OH 2 as seen by neutron diffraction and 1H NMR

We report on a detailed neutron diffraction and 1H NMR study on the frustrated spin 1 2 chain material linarite, PbCuSO4 OH 2, where competing ferromagnetic nearest neighbor and antiferromagnetic next nearestneighbor interactions lead to frustration. From the magnetic Bragg peak intensity studied down to 60 mK, the magnetic moment per Cu atom is obtained within the whole magnetic phase diagram for H b axis. Further, we establish the detailed configurations of the shift of the SDW propagation vector in phase V with field and temperature. Finally, combining our neutron diffraction results with those from a low temperature high field NMR study, we find an even more complex phase diagram close to the quasisaturation field suggesting that bound two magnon excitations are the lowest energy excitations close to and in the quasisaturation regime. Qualitatively and semiquantitatively, we relate such behavior to XYZ exchange anisotropy and contributions from the Dzyaloshinsky Moriya interaction to affect the magnetic properties of linarite