327 research outputs found
A Model for Coherent Scattering of Electromagnetic Waves from Spacially Bounded Plasmawaves
Bacterial communities potentially involved in iron-cycling in Baltic Sea and North Sea sediments revealed by pyrosequencing
Immunogenic Mycobacterium africanum Strains Associated with Ongoing Transmission in The Gambia
In West Africa, Mycobacterium tuberculosis strains co-circulate with M. africanum, and both pathogens cause pulmonary tuberculosis in humans. Given recent findings that M. tuberculosis T-cell epitopes are hyperconserved, we hypothesized that more immunogenic strains have increased capacity to spread within the human host population. We investigated the relationship between the composition of the mycobacterial population in The Gambia, as measured by spoligotype analysis, and the immunogenicity of these strains as measured by purified protein derivative-induced interferon-γ release in ELISPOT assays of peripheral blood mononuclear cells. We found a positive correlation between strains with superior spreading capacity and their relative immunogenicity. Although our observation is true for M. tuberculosis and M. africanum strains, the association was especially pronounced in 1 M. africanum sublineage, characterized by spoligotype shared international type 181, which is responsible for 20% of all tuberculosis cases in the region and therefore poses a major public health threat in The Gambia
Turbulent particle transport in magnetized fusion plasma
The understanding of the mechanisms responsible for particle transport is of
the utmost importance for magnetized fusion plasmas. A peaked density profile
is attractive to improve the fusion rate, which is proportional to the square
of the density, and to self-generate a large fraction of non-inductive current
required for continuous operation. Experiments in various tokamak devices (AUG,
DIII-D, JET, TCV, TEXT, TFTR) have indicated the existence of an anomalous
inward particle pinch. Recently, such an anomalous pinch has been unambiguously
identified in Tore Supra very long discharges, in absence of toroidal electric
field and of central particle source, for more than 4 minutes [1]. This
anomalous particle pinch is predicted by a quasilinear theory of particle
transport [2], and confirmed by non-linear turbulence simulations [3] and
general considerations based on the conservation of motion invariants [4].
Experimentally, the particle pinch is found to be sensitive to the magnetic
field gradient in many cases [5, 6, 7, 8], to the temperature profile [5, 9]
and also to the collisionality that changes the nature of the microturbulence
[10, 11, 12]. The consistency of some of the observed dependences with the
theoretical predictions gives us a clearer understanding of the particle pinch
in tokamaks, allowing us to predict more accurately the density profile in
ITER.Comment: 12th International Congress on Plasma Physics, 25-29 October 2004,
Nice (France
Yucatan Throughflow - Cruise No. M94, March 12 – March 26, 2013, Balboa (Panama) – Kingston (Jamaica)
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