28,894 research outputs found
Scaling of the Thue-Morse diffraction measure
We revisit the well-known and much studied Riesz product representation of the Thue-Morse diffraction measure, which is also the maximal spectral measure for the corresponding dynamical spectrum in the complement of the pure point part. The known scaling relations are summarised, and some new findings are explained
Twisted CFT and bilayer Quantum Hall systems
We identify the impurity interactions of the recently proposed CFT
description of a bilayer Quantum Hall system at filling nu =m/(pm+2) in Mod.
Phys. Lett. A 15 (2000) 1679. Such a CFT is obtained by m-reduction on the one
layer system, with a resulting pairing symmetry and presence of quasi-holes.
For the m=2 case boundary terms are shown to describe an impurity interaction
which allows for a localized tunnel of the Kondo problem type. The presence of
an anomalous fixed point is evidenced at finite coupling which is unstable with
respect to unbalance and flows to a vacuum state with no quasi-holes.Comment: 15 pages, 1 figure, Late
Air pollutant levels in air-conditioned and naturally ventilated museums: a pilot study
An air-conditioned and a naturally ventilated museum in a highly polluted part of London were compared for effectiveness of pollution control. Nitrogen dioxide, sulphur dioxide and hydrogen sulphide concentrations were measured inside and outside using diffusion tubes. Airborne particles were measured using a Grimm laser counting device. It was found that the benefits normally attributed to air-conditioning with filtration were not as great as might be thought. Only nitrogen dioxide and particle levels were significantly lower in the air-conditioned museum than in the naturally ventilated museum
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