2,730 research outputs found
Oriented Quantum Algebras and Invariants of Knots and Links
In GT/0006019 oriented quantum algebras were motivated and introduced in a
natural categorical setting. Invariants of knots and links can be computed from
oriented quantum algebras, and this includes the Reshetikhin-Turaev theory for
Ribbon Hopf algebras. Here we continue the study of oriented quantum algebras
from a more algebraic perspective, and develop a more detailed theory for them
and their associated invariants.Comment: LAteX document, 45 pages, 17 figure
The Molecular Interstellar Medium in Ultraluminous Infrared Galaxies
We present CO observations of a large sample of ultraluminous IR galaxies out
to z = 0.3. Most of the galaxies are interacting, but not completed mergers.
All but one have high CO(1-0) luminosities, log(Lco [K-km/s-pc^2]) = 9.92 +/-
0.12. The dispersion in Lco is only 30%, less than that in the FIR luminosity.
The integrated CO intensity correlates Strongly with the 100 micron flux
density, as expected for a black body model in which the mid and far IR
radiation are optically thick. We use this model to derive sizes of the FIR and
CO emitting regions and the enclosed dynamical masses. Both the IR and CO
emission originate in regions a few hundred parsecs in radius. The median value
of Lfir/Lco = 160 Lsun/(K-km/s-pc^2), within a factor of two of the black body
limit for the observed FIR temperatures. The entire ISM is a scaled up version
of a normal galactic disk with densities a factor of 100 higher, making even
the intercloud medium a molecular region. Using three different techniques of
H2 mass estimation, we conclude that the ratio of gas mass to Lco is about a
factor of four lower than for Galactic molecular clouds, but that the gas mass
is a large fraction of the dynamical mass. Our analysis of CO emission reduces
the H2 mass from previous estimates of 2-5e10 Msun to 0.4-1.5e10 Msun, which is
in the range found for molecular gas rich spiral galaxies. A collision
involving a molecular gas rich spiral could lead to an ultraluminous galaxy
powered by central starbursts triggered by the compression of infalling
preexisting GMC's.Comment: 34 pages LaTeX with aasms.sty, 14 Postscript figures, submitted to
ApJ Higher quality versions of Figs 2a-f and 7a-c available by anonymous FTP
from ftp://sbast1.ess.sunysb.edu/solomon/
Magnetic Monopoles, Electric Neutrality and the Static Maxwell-Dirac Equations
We study the full Maxwell-Dirac equations: Dirac field with minimally coupled
electromagnetic field and Maxwell field with Dirac current as source. Our
particular interest is the static case in which the Dirac current is purely
time-like -- the "electron" is at rest in some Lorentz frame. In this case we
prove two theorems under rather general assumptions. Firstly, that if the
system is also stationary (time independent in some gauge) then the system as a
whole must have vanishing total charge, i.e. it must be electrically neutral.
In fact, the theorem only requires that the system be {\em asymptotically}
stationary and static. Secondly, we show, in the axially symmetric case, that
if there are external Coulomb fields then these must necessarily be
magnetically charged -- all Coulomb external sources are electrically charged
magnetic monopoles
Factorizable ribbon quantum groups in logarithmic conformal field theories
We review the properties of quantum groups occurring as Kazhdan--Lusztig dual
to logarithmic conformal field theory models. These quantum groups at even
roots of unity are not quasitriangular but are factorizable and have a ribbon
structure; the modular group representation on their center coincides with the
representation on generalized characters of the chiral algebra in logarithmic
conformal field models.Comment: 27pp., amsart++, xy. v2: references added, some other minor addition
Small animal disease surveillance: respiratory disease 2017
This report focuses on surveillance for respiratory disease in companion animals. It begins with an analysis of data from 392 veterinary practices contributing to the Small Animal Veterinary Surveillance Network (SAVSNET) between January and December 2017.
The following section describes canine respiratory coronavirus infections in dogs, presenting results from laboratory-confirmed cases across the country between January 2010 and December 2017. This is followed by an update on the temporal trends of three important syndromes in companion animals, namely gastroenteritis, pruritus and respiratory disease, from 2014 to 2017.
A fourth section presents a brief update on Streptococcus equi subspecies zooepidemicus in companion animals. The final section summarises some recent developments pertinent to companion animal health, namely eyeworm (Thelazzia callipaeda) infestations in dogs imported to the UK and canine influenza virus in the USA and Canada
Molecular Gas in the Spectacular Ring Galaxy NGC 1144
We have detected extremely wide (1100 km/s) CO(1-0) emission from NGC 1144,
an interacting, luminous infrared galaxy that is the dominant component of the
Arp 118 system. The observations show that NGC 1144 is one of the most CO
luminous galaxies in the local universe, with a CO luminosity twice that of Arp
220. Maps with the IRAM interferometer show that the CO is not in or very near
the Seyfert 2 nucleus, but in the 20 kpc diameter ring that extends halfway
between NGC 1144 and the elliptical galaxy NGC 1143. The greatest gas
concentration, with 40% of the CO luminosity, is in the southern part of the
ring, in NGC 1144. Another 15% of the CO luminosity comes from the dominant 10
m source, a giant extranuclear HII region. The ring of molecular gas, the
off-center nucleus, the ring extending halfway to the intruder, and the
velocity of the intruder nearly equal to the escape velocity all show that Arp
118 is a ring galaxy produced by a collision of a massive spiral with an
elliptical. The most spectacular property is the velocity range, which in Arp
118 is 2 to 3 times higher than in a typical ring galaxy. Arp 118 is a rare
example of a very luminous extended starburst with a scale of about 5-10 kpc,
and a luminosity of 3 .Comment: AAS Latex with postscript figures. Note that two negative signs ("-")
in Declination were missed from Fig. 2. ApJ Letters (in press
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