374 research outputs found
Towards understanding edge localised mode mitigation by resonant magnetic perturbations in MAST
Type-I Edge Localised Modes (ELMs) have been mitigated in MAST through the
application of n = 3, 4 and 6 resonant magnetic perturbations (RMPs). For each
toroidal mode number of the non-axisymmetric applied fields, the frequency of
the ELMs has been increased significantly, and the peak heat flux on the
divertor plates reduced commensurately. This increase in ELM frequency occurs
despite a significant drop in the edge pressure gradient, which would be
expected to stabilise the peeling-ballooning modes thought to be responsible
for type-I ELMs. Various mechanisms which could cause a destabilisation of the
peeling-ballooning modes are presented, including pedestal widening, plasma
rotation braking, three dimensional corrugation of the plasma boundary and the
existence of radially extended lobe structures near to the X-point. This leads
to a model aimed at resolving the apparent dichotomy of ELM control, that is to
say ELM suppression occurring due to the pedestal pressure reduction below the
peeling-ballooning stability boundary, whilst the reduction in pressure can
also lead to ELM mitigation, which is ostensibly a destabilisation of
peeling-ballooning modes. In the case of ELM mitigation, the pedestal
broadening, 3d corrugation or lobes near the X-point degrade ballooning
stability so much that the pedestal recovers rapidly to cross the new stability
boundary at lower pressure more frequently, whilst in the case of suppression,
the plasma parameters are such that the particle transport reduces the edge
pressure below the stability boundary which is only mildly affected by
negligible rotation braking, small edge corrugation or short, broad lobe
structures.Comment: 23 pages, 12 figures. Copyright (2013) United Kingdom Atomic Energy
Authority. This article may be downloaded for personal use only. Any other
use requires prior permission of the author and the American Institute of
Physic
Plasmon Modes and Correlation Functions in Quantum Wires and Hall Bars
We present microscopic derivations of the one-dimensional low-energy boson
effective Hamiltonians of quantum wire and quantum Hall bar systems. The
quantum Hall system is distinguished by its spatial separation of oppositely
directed electrons. We discuss qualitative differences in the plasmon
collective mode dispersions and the ground state correlation functions of the
two systems which are consequences of this difference. The slowly-decaying
quasi-solid correlations expected in a quantum wire are strongly suppressed in
quantum Hall bar systems.Comment: 7 pages, RevTex, 3 figures and 1 table included; references updated
and minor typos correcte
Safety, Immunogenicity, and Protective Efficacy of Intradermal Immunization with Aseptic, Purified, Cryopreserved Plasmodium falciparum Sporozoites in Volunteers Under Chloroquine Prophylaxis
Immunization of volunteers under chloroquine prophylaxis by bites of *Plasmodium falciparum* sporozoite (PfSPZ)–infected mosquitoes induces > 90% protection against controlled human malaria infection (CHMI). We studied intradermal immunization with cryopreserved, infectious PfSPZ in volunteers taking chloroquine (PfSPZ
chemoprophylaxis vaccine [CVac]). Vaccine groups 1 and 3 received 3x monthly immunizations with 7.5 x 10^4
PfSPZ. Control groups 2 and 4 received normal saline. Groups 1 and 2 underwent CHMI (#1) by mosquito bite 60
days after the third immunization. Groups 3 and 4 were boosted 168 days after the third immunization and
underwent CHMI (#2) 137 days later. Vaccinees (11/20, 55%) and controls (6/10, 60%) had the same percentage of
mild to moderate solicited adverse events. After CHMI #1, 8/10 vaccinees (group 1) and 5/5 controls (group 2)
became parasitemic by microscopy; the two negatives were positive by quantitative real-time polymerase chain
reaction (qPCR). After CHMI #2, all vaccinees in group 3 and controls in group 4 were parasitemic by qPCR.
Vaccinees showed weak antibody and no detectable cellular immune responses. Intradermal immunization with up
to 3 x 10^5 PfSPZ-CVac was safe, but induced only minimal immune responses and no sterile protection against Pf
CHMI.
INTRODUCTIO
A randomized feasibility trial comparing four antimalarial drug regimens to induce Plasmodium falciparum gametocytemia in the controlled human malaria infection model
Background: Malaria elimination strategies require a thorough understanding of parasite transmission from human to mosquito. A clinical model to induce gametocytes to understand their dynamics and evaluate transmission-blocking interventions (TBI) is currently unavailable. Here, we explore the use of the well-established Controlled Human Malaria Infection model (CHMI) to induce gametocyte carriage with different antimalarial drug regimens.
Methods: In a single centre, open-label randomised tr
Severe Dengue Is Associated with Consumption of von Willebrand Factor and Its Cleaving Enzyme ADAMTS-13
Severe dengue infections are characterized by thrombocytopenia, clinical bleeding and plasma leakage. Activation of the endothelium, the inner lining of blood vessels, leads to the secretion of storage granules called Weibel Palade bodies (WPBs). We demonstrated that severe dengue in Indonesian children is associated with a strong increase in plasma levels of the WPB constituents von Willebrand factor (VWF), VWF propeptide and osteoprotegerin (OPG). An increased amount of the hemostatic protein VWF was in a hyperreactive, platelet binding conformation, and this was most pronounced in the children who died. VWF levels at enrollment were lower than expected from concurrent VWF propeptide and OPG levels and VWF levels did not correlate well with markers of disease severity. Together, this suggests that VWF is being consumed during severe dengue. Circulating levels of the VWF-cleaving enzyme ADAMTS-13 were reduced. VWF is a multimeric protein and a subset of children had a decrease in large and intermediate VWF multimers at discharge. In conclusion, severe dengue is associated with exocytosis of WPBs with consumption of VWF and low ADAMTS-13 activity levels. This may contribute to the thrombocytopenia and complications of dengue
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