55,721 research outputs found
Accounting for Multiplicity in Calculating Eta Earth
Using the updated exoplanet population parameters of our previous study,
which includes the planetary radius updates from Gaia DR2 and an inferred
multiplicity distribution, we provide a revised calculation.
This is achieved by sampling planets from our derived population model and
determining which planets meet our criterion for habitability. To ensure robust
results, we provide probabilities calculated over a range of upper radius
limits. Our most optimistic criterion for habitability provides an
value of . We also
consider the effects of multiplicity and the number of habitable planets each
system may contain. Our calculation indicates that of GK dwarfs
have more than one planet within their habitable zone. This optimistic
habitability criterion also suggests that of solar-like stars
will harbor 5 or more habitable planets. These tightly packed highly habitable
system should be extremely rare, but still possible. Even with our most
pessimistic criterion we still expect that of solar-like stars
harbor more than one habitable planet.Comment: 7 pages, 1 figure; Accepted for publication in MNRA
Abelian homotopy Dijkgraaf-Witten theory
We construct a version of Dijkgraaf-Witten theory based on a compact abelian
Lie group within the formalism of Turaev's homotopy quantum field theory. As an
application we show that the 2+1-dimensional theory based on U(1) classifies
lens spaces up to homotopy type.Comment: 23 pages, 1 figur
Thermo electronic laser energy conversion
The thermo electronic laser energy converter (TELEC) is described and compared to the Waymouth converter and the conventional thermionic converter. The electrical output characteristics and efficiency of TELEC operation are calculated for a variety of design variables. Calculations and results are briefly outlined. It is shown that the TELEC concept can potentially convert 25 to 50 percent of incident laser radiation into electric power at high power densities and high waste heat rejection temperatures
Effect of feeding fermentable fibrerich feedstuffs on meat quality with emphasis on chemical and sensory boar taint in entire male and female pigs
Skatole, androstenone and other compounds such as indole cause boar taint in entire male pork. However, female pigs also produce skatole and indole. The purpose of this experiment was to minimise boar taint and increase overall impression of sensory quality by feeding entire male and female pigs with fibrerich feedstuffs. The pigs have been fed three organic diets for either 1 or 2 weeks prior to slaughter of which two diets contained different fermentable fibre-rich feedstuffs – 10–13.3% dried chicory roots or
25% blue lupines. These two treatments were compared with pigs fed with an organic control diet for either 1 or 2 weeks prior to slaughter. Lupines significantly reduced skatole in blood and backfat for both genders after 1 week. Moreover, lupines showed negative impact on growth rate and feed conversion whilst chicory showed no significant differences in this respect. However, the indole concentration was significantly lower in chicory than lupine fed pigs. From a sensory perspective, chicory and lupine feeding reduced boar taint since odour and flavour of manure related to skatole and urine associated to androstenone were minimised. The level of boar taint in the entire male pigs was most effectively reduced after 14 days by both fibre-rich feeds while lupine had the largest influence on ‘‘boar” taint reduction in female pigs
Co- and counter-helicity interaction between two adjacent laboratory prominences
The interaction between two side-by-side solar prominence-like plasmas has been studied using a four-electrode magnetized plasma source that can impose a wide variety of surface boundary conditions. When the source is arranged to create two prominences with the same helicity (co-helicity), it is observed that helicity transfer from one prominence to the other causes the receiving prominence to erupt sooner and faster than the transmitting prominence. When the source is arranged to create two prominences with opposite helicity (counter-helicity), it is observed that upon merging, prominences wrap around each other to form closely spaced, writhing turns of plasma. This is followed by appearance of a distinct bright region in the middle and order of magnitude higher emission of soft x rays. The four-electrode device has also been used to change the angle of the neutral line and so form more pronounced S-shapes
Dissipation Layers in Rayleigh-B\'{e}nard Convection: A Unifying View
Boundary layers play an important role in controlling convective heat
transfer. Their nature varies considerably between different application areas
characterized by different boundary conditions, which hampers a uniform
treatment. Here, we argue that, independent from boundary conditions,
systematic dissipation measurements in Rayleigh-B\'enard convection capture the
relevant near-wall structures. By means of direct numerical simulations with
varying Prandtl numbers, we demonstrate that such dissipation layers share
central characteristics with classical boundary layers, but, in contrast to the
latter, can be extended naturally to arbitrary boundary conditions. We validate
our approach by explaining differences in scaling behavior observed for no-slip
and stress-free boundaries, thus paving the way to an extension of scaling
theories developed for laboratory convection to a broad class of natural
systems
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