29,772 research outputs found
Search for brown-dwarf like secondaries in cataclysmic variables II
We have examined VTL/ISAAC 1-2.5 \umum spectroscopy of a sample of short
orbital period cataclysmic variables which are candidates for harboring
substellar companions. We provide descriptions of the infrared spectrum of
\hbox{EI Psc}, \hbox{V834 Cen}, \hbox{WX Cet}, \hbox{VW Hyi}, \hbox{TY PsA} and
\hbox{BW Scl}. Fitting of the IR spectral energy distribution (SED) was
performed by comparing the observed spectrum with late-type templates.
Absorption features of the secondary star were detected in \hbox{EI Psc} and
\hbox{V834 Cen}, consistent with dwarf secondaries of spectral type K 5 1
and M 8 0.5, respectively. In addition, we report the first detection of
the secondary star in \hbox{VW Hyi}. The SED in this case is well matched by an
L 0 2 type secondary contributing 23 per cent to the overall flux at
= 1.15 \umum. This is a surprising result for a system with a
relatively high mass transfer rate. We discuss the implication of our findings
on the current scenarios for cataclysmic variable star evolution.Comment: accepted for publication in MNRA
Search for the Lepton Flavour Violating Higgs decay H --> tau mu at Hadron Colliders
We study the prospects to detect at hadron colliders the Lepton Flavour
Violating Higgs decay H --> tau mu, which can reach substantial branching
fractions in several extensions of the SM. Among them, the generic two higgs
doublet model can be taken as a representative case where B.R.(H --> tau mu)
can reach values of order 10^-1-10^-2. Bounds on the LFV factor kappa_{tau mu}
of order 0.8-1.7 can be derived at 95% c.l. at Tevatron Run-2 with 4 fb^-1 for
m_H = 110-150 GeV.Comment: 3 pages, 1 figure, uses RevTeX4. Contribution to Snowmass 200
Effects of Bulk Viscosity on Cosmological Evolution
The effect of bulk viscisity on the evolution of the homogeneous and
isotropic cosmological models is considered. Solutions are found, with a
barotropic equation of state, and a viscosity coefficient that is proportional
to a power of the energy density of the universe. For flat space, power law
expansions, related to extended inflation are found as well as exponential
solutions, related to old inflation; also a solution with expansion that is an
exponential of an exponential of the time is found.Comment: 8 pages, latex, no figure
Length-weight relationships of coral reef fishes from the Alacran Reef, Yucatan, Mexico
Length-weight relationships were computed for 42 species of coral reef fishes from 14 families from the Alacran Reef (Yucatan, Mexico). A total of 1 892 individuals was used for this purpose. The fish species were caught by different fishing techniques such as fishhooks, harpoons, gill and trawl nets. The sampling period was from March 1998 to January 2000
In vivo cranial bone strain and bite force in the agamid lizard Uromastyx geyri
In vivo bone strain data are the most direct evidence of deformation and strain regimes in the vertebrate cranium during feeding and can provide important insights into skull morphology. Strain data have been collected during feeding across a wide range of mammals; in contrast, in vivo cranial bone strain data have been collected from few sauropsid taxa. Here we present bone strain data recorded from the jugal of the herbivorous agamid lizard Uromastyx geyri along with simultaneously recorded bite force. Principal and shear strain magnitudes in Uromastyx geyri were lower than cranial bone strains recorded in Alligator mississippiensis, but higher than those reported from herbivorous mammals. Our results suggest that variations in principal strain orientations in the facial skeleton are largely due to differences in feeding behavior and bite location, whereas food type has little impact on strain orientations. Furthermore, mean principal strain orientations differ between male and female Uromastyx during feeding, potentially because of sexual dimorphism in skull morphology
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