2,379 research outputs found
Impending carotid blowout stabilization using an LT-D tube
Adequate stabilization of a patient presenting with a carotid blowout is one of the most challenging issues an on-call ENT surgeon can be confronted with. Reducing the bleeding and securing the airway are essential before more definitive management. We present the case of a 72-year-old patient with head and neck cancer who arrived at the emergency room with a carotid blowout and who was successfully stabilized using a King LT-D ventilation tube
"Barber pole turbulence" in large aspect ratio Taylor-Couette flow
Investigations of counter-rotating Taylor-Couette flow (TCF) in the narrow
gap limit are conducted in a very large aspect ratio apparatus. The phase
diagram is presented and compared to that obtained by Andereck et al. The
spiral turbulence regime is studied by varying both internal and external
Reynolds numbers. Spiral turbulence is shown to emerge from the fully turbulent
regime via a continuous transition appearing first as a modulated turbulent
state, which eventually relaxes locally to the laminar flow. The connection
with the intermittent regimes of the plane Couette flow (pCf) is discussed
Large-N estimates of universal amplitudes of the CP^{N-1} theory and comparison with the JQ model
We present computations of certain finite-size scaling functions and
universal amplitude ratios in the large-N limit of the CP^{N-1} field theory.
We pay particular attention to the uniform susceptibility, the spin stiffness
and the specific heat. Field theoretic arguments have shown that the
long-wavelength description of the phase transition between the Neel and
valence bond solid states in square lattice S=1/2 anti-ferromagnets is expected
to be the non-compact CP^1 field theory. We provide a detailed comparison
between our field theoretic calculations and quantum Monte Carlo data close to
the Neel -VBS transition on a S=1/2 square-lattice model with competing
four-spin interactions (the JQ model).Comment: 15 page
The Minimal Moose for a Little Higgs
Recently a new class of theories of electroweak symmetry breaking have been
constructed. These models, based on deconstruction and the physics of theory
space, provide the first alternative to weak-scale supersymmetry with naturally
light Higgs fields and perturbative new physics at the TeV scale. The Higgs is
light because it is a pseudo-Goldstone boson, and the quadratically divergent
contributions to the Higgs mass are cancelled by new TeV scale ``partners'' of
the {\em same} statistics. In this paper we present the minimal theory space
model of electroweak symmetry breaking, with two sites and four link fields,
and the minimal set of fermions. There are very few parameters and degrees of
freedom beyond the Standard Model. Below a TeV, we have the Standard Model with
two light Higgs doublets, and an additional complex scalar weak triplet and
singlet. At the TeV scale, the new particles that cancel the 1-loop quadratic
divergences in the Higgs mass are revealed. The entire Higgs potential needed
for electroweak symmetry breaking--the quartic couplings as well as the
familiar negative mass squared--can be generated by the top Yukawa coupling,
providing a novel link between the physics of flavor and electroweak symmetry
breaking.Comment: 15 pages. References added. Included clarifying comments on the
origin of quartic couplings, and on power-counting. More elegant model for
generating Higgs potential from top Yukawa coupling presente
Spatiotemporal chaos induces extreme events in an extended microcavity laser
Extreme events such as rogue wave in optics and fluids are often associated
with the merging dynamics of coherent structures. We present experimental and
numerical results on the physics of extreme events appearance in a spatially
extended semiconductor microcavity laser with intracavity saturable absorber.
This system can display deterministic irregular dynamics only thanks to spatial
coupling through diffraction of light. We have identified parameter regions
where extreme events are encountered and established the origin of this
dynamics in the emergence of deterministic spatiotemporal chaos, through the
correspondence between the proportion of extreme events and the dimension of
the strange attractor
FITTING BOLE-VOLUME EQUATIONS TO SPATIALLY CORRELATED WITHIN-TREE DATA
Equations to predict the volume of an individual tree bole between stump height and the height at which its diameter has tapered to a specified minimum are common in forestry. When fitting such a regression equation, a sample of trees which span the range of sizes needed for eventual application of the equation is selected. Bole diameter is measured at ascending heights on the bole. Each tree, therefore, contributes multiple measurements to the data fitted to the equation. In contrast to past practice, we model these data in a manner which accounts for the likely spatial correlation among measurements within a tree. The resulting mixed-effects nonlinear model is fitted by REML and also by generalized estimating equations (GEE). Results from the two approaches are nearly identical, which suggests that the computationally less demanding GEE may be acceptable as a routine alternative to a fully parameterized approach
Phenomenology of Electroweak Symmetry Breaking from Theory Space
Recently, a new class of realistic models for electroweak symmetry breaking
have been constructed, without supersymmetry. These theories have naturally
light Higgs bosons and perturbative new physics at the TeV scale. We describe
these models in detail, and show that electroweak symmetry breaking can be
triggered by a large top quark Yukawa coupling. A rich spectrum of particles is
predicted, with a pair of light Higgs doublets accompanied by new light weak
triplet and singlet scalars. The lightest of these new scalars is charged under
a geometric discrete symmetry and is therefore stable, providing a new
candidate for WIMP dark matter. At TeV energies, a plethora of new heavy
scalars, gauge bosons and fermions are revealed, with distinctive quantum
numbers and decay modes.Comment: 22 pages, latex, 6 figures. Numerical results corrected,
clarifications added, conclusions unchange
- …