263 research outputs found
Stents and Vascular Woundhealing
For many years, percutaneous trans luminal coronary angioplasty (PTCA) has been
used to treat diseased, llanowed vessels. While it has been a great success in improving
patient outcome, the teciUlique is not free from complications: restenosis, dissections and
abmpt closures are serious complications of the technique, necessitating repeat
revascularization or surgery. ExpeIimental animal studies suggested that the results of PTCA
could be improved by scaffolding the intemal wall of the artery with a stent, an idea first
proposed in 1912 by Carre. In the late 1960's Dotter gave new impetus to this idea, and in
1986 the first human coronary stent implantation followed.
Initial stent implantations were associated with high thrombosis rates and results of
stent trials were greeted cautiously or even skeptically by some. In 1994 however, the results
of the European BENES TENT and American STRESS trials were published. In these trials
restenosis rates after balloon angiopiasty or Palmaz-Schatz stent implantation were
compared, and showed significant reductions in restenosis rates after stenting (BENESTENT:
22%; STRESS: 32%) compared to angioplasty alone (BENESTENT: 32%; STRESS: 42%).
These landmark trials heralded the start of an exponential growth in the use of endovascular
stents, such that today, stenting has become accepted as a standard therapeutic modality in
interventional cardiology.
Current clinical indications for the use ofstents include: (1) the primary reduction in
restenosis in de novo focal lesions in vessels greater then 3.0 mm in diameter, (2) focal
lesions in saphenous vein grafts and (3) the treatment of abmpt or threatened vessel closure
during angioplasty. However, as the variety and sophistication of stenting devices improves,
new applications are being found. Currently there are more than 55 standard or customized
stent types available for use in the coronary system manufactured by more than 30 different
companies
The effect of tidal flow directionality on tidal turbine performance characteristics
With many Tidal Energy Conversion (TEC) devices at full scale prototype stage there are two distinct design groups for Horizontal Axis Tidal Turbines (HATTs). Devices with a yaw mechanism allowing the turbine to always face into the flow, and devices with blades that can rotate through 180° to harness a strongly bi-directional flow. As marine turbine technology verges on the realm of economic viability this paper reveals the performance of Cardiff University's concept tidal turbine with its support structure either upstream or downstream and with various proximities between the rotating plane of the turbine and its support stanchion. Through the use of validated Computational Fluid Dynamics (CFD) modelling this work shows the optimal proximity between rotor plane and stanchion as well as establishing, in the given context, the use of a yaw mechanism to be superior to a bi-directional system from a performance perspective
Energy Level Statistics of the U(5) and O(6) Symmetries in the Interacting Boson Model
We study the energy level statistics of the states in U(5) and O(6) dynamical
symmetries of the interacting boson model and the high spin states with
backbending in U(5) symmetry. In the calculations, the degeneracy resulting
from the additional quantum number is eliminated manually. The calculated
results indicate that the finite boson number effect is prominent. When
has a value close to a realistic one, increasing the interaction strength of
subgroup O(5) makes the statistics vary from Poisson-type to GOE-type and
further recover to Poisson-type. However, in the case of , they
all tend to be Poisson-type. The fluctuation property of the energy levels with
backbending in high spin states in U(5) symmetry involves a signal of shape
phase transition between spherical vibration and axial rotation.Comment: 38 pages, 13 figure
Enhanced T cell responses induced by a necrotic dendritic cell vaccine, expressing HCV NS3
A vaccine that induces potent, broad and sustained cell-mediated immunity, resulting in effective memory has the potential to restrict hepatitis C (HCV) virus infection. Early, multi-functional CD4+ and CD8+ T cell responses against non-structural protein 3 (NS3) have been associated with HCV clearance. Necrotic cells generate strong immune responses and represent a major antigenic source used by dendritic cells (DC) for processing and presentation, but there is conflicting evidence as to their immunogenicity in vaccination. Immunization with DC loaded with viral antigens has been done in the past, but to date the immunogenicity of live vs. necrotic DC vaccines has not been investigated. We developed a DC2.4 cell line stably expressing HCV NS3, and compared the NS3-specific responses of live vs. necrotic NS3 DC. Vaccination of mice with necrotic NS3 DC increased the breadth of T-cell responses and enhanced the production of IL-2, TNF-α, and IFN-γ by effector memory CD4+ and CD8+T cells, compared to mice vaccinated with live NS3 DC. A single dose of necrotic NS3 DC vaccine induced a greater influx and activation of cross-presenting CD11c+ CD8α+ DC and necrosis-sensing Clec9A+ DC in the draining lymph nodes. Furthermore, using a hydrodynamic challenge model necrotic NS3 DC vaccination resulted in enhanced clearance of NS3-positive hepatocytes from the livers of vaccinated mice. Taken together, the data demonstrate that necrotic DC represent a novel and exciting vaccination strategy capable of inducing broad and multifunctional T cell memory.Zelalem A. Mekonnen, Makutiro G. Masavuli, Wenbo Yu, Jason Gummow, Dawn M. Whelan, Zahraa Al-Delfi ... et al
A First Search for coincident Gravitational Waves and High Energy Neutrinos using LIGO, Virgo and ANTARES data from 2007
We present the results of the first search for gravitational wave bursts
associated with high energy neutrinos. Together, these messengers could reveal
new, hidden sources that are not observed by conventional photon astronomy,
particularly at high energy. Our search uses neutrinos detected by the
underwater neutrino telescope ANTARES in its 5 line configuration during the
period January - September 2007, which coincided with the fifth and first
science runs of LIGO and Virgo, respectively. The LIGO-Virgo data were analysed
for candidate gravitational-wave signals coincident in time and direction with
the neutrino events. No significant coincident events were observed. We place
limits on the density of joint high energy neutrino - gravitational wave
emission events in the local universe, and compare them with densities of
merger and core-collapse events.Comment: 19 pages, 8 figures, science summary page at
http://www.ligo.org/science/Publication-S5LV_ANTARES/index.php. Public access
area to figures, tables at
https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=p120000
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