3,137 research outputs found
Carotid stenting for irradiation-associated carotid stenosis 3 years after previous carotid endarterectomy
Extracranial carotid stenosis is a known complication of external irradiation to the head and neck region. We report on a patient with previous carotid endarterectomy for irradiation-associated carotid stenosis. This patient developed symptomatic carotid stenosis over the ipsilateral common carotid artery proximal to the previous endarterectomy site 3 years later, and was successfully treated with carotid angioplasty and stenting. This case illustrates the importance of Duplex scan surveillance after carotid endarterectomy for patients with irradiation-associated carotid stenosis. The complimentary role of carotid endarterectomy and carotid angioplasty for managing such a patient is highlighted.published_or_final_versio
Thrombolytic and interventional therapy for acute ischaemic stroke â are we ready in Hong Kong?
Symposium 3 â Symposium on Strokepublished_or_final_versio
Learning to read and spell english words by Chinese students
This study examined the structural relationships between (a) the latent independent constructs of orthographic and lexical knowledge and phonological sensitivity and (b) the effect of these constructs on the latent construct of literacy manifested by reading aloud and spelling regular and exception English words in 156 Cantonese-speaking Chinese students (M age = 10.8 years) who were learning English as a second language in Hong Kong. Three carefully designed and item-analyzed indicators subserved the construct of orthographic and lexical knowledge, and another three indicators subserved the construct of phonological sensitivity. Our hypothesis of greater contribution of word-specific orthographic and lexical knowledge than phonological sensitivity to learning to read and spell English words in these Chinese children was supported by results from multiple regression, principal component analyses and especially by structural equation modeling. The various goodness-of-fit indexes showed the appropriateness of the indicators in measuring the latent constructs as well as the relationships among these constructs.published_or_final_versio
GCNT3 (glucosaminyl (N-acetyl) transferase 3, mucin type)
Review on GCNT3 (glucosaminyl (N-acetyl) transferase 3, mucin type), with data on DNA, on the protein encoded, and where the gene is implicated
Self-Assembly of 4-sided Fractals in the Two-handed Tile Assembly Model
We consider the self-assembly of fractals in one of the most well-studied
models of tile based self-assembling systems known as the Two-handed Tile
Assembly Model (2HAM). In particular, we focus our attention on a class of
fractals called discrete self-similar fractals (a class of fractals that
includes the discrete Sierpi\'nski carpet). We present a 2HAM system that
finitely self-assembles the discrete Sierpi\'nski carpet with scale factor 1.
Moreover, the 2HAM system that we give lends itself to being generalized and we
describe how this system can be modified to obtain a 2HAM system that finitely
self-assembles one of any fractal from an infinite set of fractals which we
call 4-sided fractals. The 2HAM systems we give in this paper are the first
examples of systems that finitely self-assemble discrete self-similar fractals
at scale factor 1 in a purely growth model of self-assembly. Finally, we show
that there exists a 3-sided fractal (which is not a tree fractal) that cannot
be finitely self-assembled by any 2HAM system
Inspection of Computed Tomography (CT) Data and Finite Element (FE) Simulation of Additive Manufactured (AM) Components
This is the author accepted manuscript. The final version is available from the publisherOne of the challenges of working with Additive Manufactured (AM) metal parts involves checking accuracy and
reliability before production. Techniques used Computed Tomography (CT) scans, 3D image processing, and
Finite Element (FE) simulation help detect problems prior to costly faults. A workflow has been developed by
Synopsys, ANSYS, North Star Imaging, and the University of Pittsburgh to streamline this often-complex
process, with applications to analyzing metal AM-produced lightweight brackets and a component from Moog,
Inc. Software like Synopsys Simplewareâą is used to generate robust models from 3D scans of AM parts to
compare original CAD models with âas-builtâ geometries, and to export a FE mesh for simulation in ANSYS.
This method enables identification of design deviations early in the design process, and how their impact might
be tackled prior to production. For the Moog application, unexpected defects were identified for aerospace parts
to inform future design iteration
Spin and Chirality Effects in Antler-Topology Processes at High Energy Colliders
We perform a model-independent investigation of spin and chirality
correlation effects in the antler-topology processes
at high energy colliders with polarized
beams. Generally the production process
can occur not only through the -channel exchange of vector bosons,
, including the neutral Standard Model (SM) gauge bosons,
and , but also through the - and -channel exchanges of new
neutral states, and , and the -channel
exchange of new doubly-charged states, . The general set of
(non-chiral) three-point couplings of the new particles and leptons allowed in
a renormalizable quantum field theory is considered. The general spin and
chirality analysis is based on the threshold behavior of the excitation curves
for pair production in collisions with
longitudinal and transverse polarized beams, the angular distributions in the
production process and also the production-decay angular correlations. In the
first step, we present the observables in the helicity formalism. Subsequently,
we show how a set of observables can be designed for determining the spins and
chiral structures of the new particles without any model assumptions. Finally,
taking into account a typical set of approximately chiral invariant scenarios,
we demonstrate how the spin and chirality effects can be probed experimentally
at a high energy collider.Comment: 50 pages, 14 figures, 6 tables, matches version published in EPJ
Electronic stress tensor analysis of hydrogenated palladium clusters
We study the chemical bonds of small palladium clusters Pd_n (n=2-9)
saturated by hydrogen atoms using electronic stress tensor. Our calculation
includes bond orders which are recently proposed based on the stress tensor. It
is shown that our bond orders can classify the different types of chemical
bonds in those clusters. In particular, we discuss Pd-H bonds associated with
the H atoms with high coordination numbers and the difference of H-H bonds in
the different Pd clusters from viewpoint of the electronic stress tensor. The
notion of "pseudo-spindle structure" is proposed as the region between two
atoms where the largest eigenvalue of the electronic stress tensor is negative
and corresponding eigenvectors forming a pattern which connects them.Comment: 22 pages, 13 figures, published online, Theoretical Chemistry
Account
Physiology and cell biology of acupuncture observed in calcium signaling activated by acoustic shear wave
This article presents a novel model of acupuncture physiology based on cellular calcium activation by an acoustic shear wave (ASW) generated by the mechanical movement of the needle. An acupuncture needle was driven by a piezoelectric transducer at 100 Hz or below, and the ASW in human calf was imaged by magnetic resonance elastography. At the cell level, the ASW activated intracellular Ca 2+ transients and oscillations in fibroblasts and endothelial, ventricular myocytes and neuronal PC-12 cells along with frequency-amplitude tuning and memory capabilities. Monitoring in vivo mammalian experiments with ASW, enhancement of endorphin in blood plasma and blocking by Gd 3+ were observed; and increased Ca 2+ fluorescence in mouse hind leg muscle was imaged by two-photon microscopy. In contrast with traditional acupuncture models, the signal source is derived from the total acoustic energy. ASW signaling makes use of the anisotropy of elasticity of tissues as its waveguides for transmission and that cell activation is not based on the nervous system. © 2011 The Author(s).published_or_final_versionSpringer Open Choice, 21 Feb 201
The Tevatron at the Frontier of Dark Matter Direct Detection
Direct detection of dark matter (DM) requires an interaction of dark matter
particles with nucleons. The same interaction can lead to dark matter pair
production at a hadron collider, and with the addition of initial state
radiation this may lead to mono-jet signals. Mono-jet searches at the Tevatron
can thus place limits on DM direct detection rates. We study these bounds both
in the case where there is a contact interaction between DM and the standard
model and where there is a mediator kinematically accessible at the Tevatron.
We find that in many cases the Tevatron provides the current best limit,
particularly for light dark matter, below 5 GeV, and for spin dependent
interactions. Non-standard dark matter candidates are also constrained. The
introduction of a light mediator significantly weakens the collider bound. A
direct detection discovery that is in apparent conflict with mono-jet limits
will thus point to a new light state coupling the standard model to the dark
sector. Mono-jet searches with more luminosity and including the spectrum shape
in the analysis can improve the constraints on DM-nucleon scattering cross
section.Comment: 20 pages, 8 figures, final version in JHE
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