358 research outputs found
Galois action on knots I: Action of the absolute Galois group
Our aim of this and subsequent papers is to enlighten (a part of, presumably) arithmetic structures of knots. This paper introduces a notion of profinite knots which extends topological knots and shows its various basic properties. Particularly an action of the absolute Galois group of the rational number field on profinite knots is rigorously established, which is attained by our extending the action of Drinfel0d’s Grothendieck–Teichmüller group on profinite braid groups into on profinite knots
Synthesis of nanoparticulate anatase and rutile crystallites at low temperatures in the Pluronic F127 microemulsion system
A low-temperature synthesis method for preparing nanosized TiO(2) crystallites has been developed based on a Pluronic F127 microemulsion system. Both anatase and rutile polymorphs can be prepared, and there exists a temperature window between 40 and 50 degrees C where the formation of rutile is favored over anatase. At 60 degrees C and above, anatase is kinetically favored and only very slowly transforms to rutile at 60 degrees C. The results differ from previous observations regarding formation kinetics and temperature range for rutile formation as well as in the microscopic aggregation of the formed nanoparticles. This development of a low-temperature synthesis of crystalline titania nanoparticles within the Pluronic block copolymer system is an important and enabling step toward devising a direct synthesis route for the formation of ordered mesoporous and crystalline titania
M. Kontsevich's graph complex and the Grothendieck-Teichmueller Lie algebra
We show that the zeroth cohomology of M. Kontsevich's graph complex is
isomorphic to the Grothendieck-Teichmueller Lie algebra grt_1. The map is
explicitly described. This result has applications to deformation quantization
and Duflo theory. We also compute the homotopy derivations of the Gerstenhaber
operad. They are parameterized by grt_1, up to one class (or two, depending on
the definitions). More generally, the homotopy derivations of the (non-unital)
E_n operads may be expressed through the cohomology of a suitable graph
complex. Our methods also give a second proof of a result of H. Furusho,
stating that the pentagon equation for grt_1-elements implies the hexagon
equation
Chandra observation of the central galaxies in A1060 cluster of galaxies
Chandra observation of the central region of the A1060 cluster of galaxies
resolved X-ray emission from two giant elliptical galaxies, NGC 3311 and NGC
3309. The emission from these galaxies consists of two components, namely the
hot interstellar medium (ISM) and the low-mass X-ray binaries (LMXBs). We found
the spatial extent of the ISM component was much smaller than that of stars for
both galaxies, while the ratios of X-ray to optical blue-band luminosities were
rather low but within the general scatter for elliptical galaxies. After
subtracting the LMXB component, the ISM is shown to be in pressure balance with
the intracluster medium of A1060 at the outer boundary of the ISM. These
results imply that the hot gas supplied from stellar mass loss is confined by
the external pressure of the intracluster medium, with the thermal conduction
likely to be suppressed. The cD galaxy NGC 3311 does not exhibit the extended
potential structure which is commonly seen in bright elliptical galaxies, and
we discuss the possible evolution history of the very isothermal cluster A1060.Comment: 12 pages, 7 figures, Latex2e(emulateapj5), accepted in Ap
Detection of an X-Ray Hot Region in the Virgo Cluster of Galaxies with ASCA
Based on mapping observations with ASCA, an unusual hot region with a spatial
extent of 1 square degree was discovered between M87 and M49 at a center
coordinate of R. A. = 12h 27m 36s and Dec. = (J2000). The X-ray
emission from the region has a 2-10 keV flux of ergs
s cm and a temperature of keV, which is
significantly higher than that in the surrounding medium of keV. The
internal thermal energy in the hot region is estimated to be ergs with a gas density of cm. A power-law
spectrum with a photon index is also allowed by the data. The hot
region suggests there is an energy input due to a shock which is probably
caused by the motion of the gas associated with M49, infalling toward the M87
cluster with a velocity km s.Comment: 12 pages, 3 figures, accepted to ApJ
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