1,377 research outputs found
Solar energy and the aeronautics industry
An introduction to the physical aspects of solar energy, incidental energy and variations in solar flux is presented, along with an explanation of the physical principles of obtaining solar energy. The history of the application of solar energy to aeronautics, including the Gossamer Penguin and the Solar Challenger is given. Finally, an analysis of the possibilities of using a reaction motor with hybrid propulsion combining solar energy with traditional fuels as well as calculations of the proposed cycle and its mode of operation are given
Stopping light in two dimensional quasicrystalline waveguides
The introduction of defects in photonic lattices generally allows to control the localization and the propagation of light. While point defects are conventionally used in order to obtain localized photonic states, linear defects are introduced for waveguiding EM waves. In this work we demonstrate the possibility of obtaining localized states also in a waveguiding configuration, by using quasicrystalline lattices. This result opens a new range of possibilities in designing optical circuits, in which the localization- propagation switch is easly obtainable by mechanical or opto-electric methods
New insight into cataract formation -- enhanced stability through mutual attraction
Small-angle neutron scattering experiments and molecular dynamics simulations
combined with an application of concepts from soft matter physics to complex
protein mixtures provide new insight into the stability of eye lens protein
mixtures. Exploring this colloid-protein analogy we demonstrate that weak
attractions between unlike proteins help to maintain lens transparency in an
extremely sensitive and non-monotonic manner. These results not only represent
an important step towards a better understanding of protein condensation
diseases such as cataract formation, but provide general guidelines for tuning
the stability of colloid mixtures, a topic relevant for soft matter physics and
industrial applications.Comment: 4 pages, 4 figures. Accepted for publication on Phys. Rev. Let
Passage-time statistics of superradiant light pulses from Bose-Einstein condensates
We discuss the passage-time statistics of superradiant light pulses generated
during the scattering of laser light from an elongated atomic Bose-Einstein
condensate. Focusing on the early-stage of the phenomenon, we analyze the
corresponding probability distributions and their scaling behaviour with
respect to the threshold photon number and the coupling strength. With respect
to these parameters, we find quantities which only vary significantly during
the transition between the Kapitza Dirac and the Bragg regimes. A possible
connection of the present observations to Brownian motion is also discussed.Comment: Close to the version published in J. Phys.
Mesoscopic Phase Fluctuations: General Phenomenon in Condensed Matter
General conditions for the occurrence of mesoscopic phase fluctuations in
condensed matter are considered. The description of different thermodynamic
phases, which coexist as a mixture of mesoscopically separated regions, is
based on the {\it theory of heterophase fluctuations}. The spaces of states,
typical of the related phases, are characterized by {\it weighted Hilbert
spaces}. Several models illustrate the main features of heterophase condensed
matter.Comment: 23 pages, Latex, no figure
Åndelig dannelse og vejledning - et udsnit af mulige rammebetingelser
Artiklen beskæftiger sig med nogle af rammebetingelserne – de kulturelle, samfundsmæssige og teologiske – for åndelig dannelse og vejledning. Den ofte belastede identitet og tydelige åndelige længsel – styret eller formet af den nye subjektivitet – har brug for eksistentielle tolkningsrum. Både teologi og kirke skal vove at tolke og navngive det navneløse, også den løse tro og det kaosprægede i den flydende modernitet. Den kristne teologi har adkomst til mange rige resurser og traditioner. Disse resurser kan være menneskelivets hukommelse – og verdens ‘hardisk’. Troen, livet og tjenesten formes og dannes i tæt forbindelse med disse kilder. Og kirken er som fællesskab et unikt og konkret resursested, hvis det også fungerer som åbent grænseområde. Grænsefællesskabet er fyldt med håb og muligheder for de åndeligt søgende. At leve med Gud i en kærlighedsrelation kan ikke læres med hovedet. Det må erfares i hjertet
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