171 research outputs found
Systematic chemotherapy of febrile cases : a substitute strategy for malaria control in rural areas of Africa
Negative-index media for matter-wave optics
We consider the extension of optical meta-materials to matter waves. We show
that the generic property of pulsed comoving magnetic fields allows us to
fashion the wave-number dependence of the atomic phase shift. It can be used to
produce a transient negative group velocity of an atomic wave packet, which
results into a negative refraction of the matter wave. Application to slow
metastable argon atoms Ar*(3P2) shows that the device is able to operate either
as an efficient beam splitter or an atomic meta-lens. Implications of
"meta-media" in atom optics are considered.Comment: 4 pages, 4 figures, submitted at PRL 4 November 200
Anisotropic Atom-Surface Interactions in the Casimir-Polder Regime
The distance-dependence of the anisotropic atom-wall interaction is studied.
The central result is the 1/z^6 quadrupolar anisotropy decay in the retarded
Casimir-Polder regime. Analysis of the transition region between non-retarded
van der Waals regime (in 1/z^3) and Casimir-Polder regime shows that the
anisotropy cross-over occurs at very short distances from the surface, on the
order of 0.03 Lambda, where Lambda is the atom characteristic wavelength.
Possible experimental verifications of this distance dependence are discussed.Comment: 5 pages, 2 figure
Etude de la sensibilité de Plasmodium falciparum à la chloroquine par les épreuves in vivo, dans une zone de savane arbustive de Haute-Volta à paludisme hyperendémique : fiabilité de l'épreuve in vivo de 28 jours en zone de transmission continue
Influence de deux stratégies médicamenteuses par chloroquine (prophylaxie et thérapie des accès fébriles) sur la transmission du paludisme
Jail fever (epidemic typhus) outbreak in Burundi.
We recently investigated a suspected outbreak of epidemic typhus in a jail in Burundi. We tested sera of nine patients by microimmunofluorescence for antibodies to Rickettsia prowazekii and Rickettsia typhi. We also amplified and sequenced from lice gene portions specific for two R. prowazekii proteins: the gene encoding for citrate synthase and the gene encoding for the rickettsial outer membrane protein. All patients exhibited antibodies specific for R. prowazekii. Specific gene sequences were amplified in two lice from one patient. The patients had typical clinical manifestations, and two died. Molecular techniques provided a convenient and reliable means of examining lice and confirming this outbreak. The jail-associated outbreak predates an extensive ongoing outbreak of louse-borne typhus in central eastern Africa after civil war and in refugee camps in Rwanda, Burundi (1), and Zaire
INTERFERENTIAL MONOCHROMATOR FOR NEUTRAL ATOMS
Abstract When a so called "co-moving" magnetic field -i.e. a field moving at a velocity close to the atom ones -is used as a phase shifter in a Stern-Gerlach atom interferometer the resulting accumulated phase shift takes non negligible values for only those atomic velocities which are close to that of the field. The interferometer is then an adjustable interferential velocity filter. This effect has been demonstrated by means of a time-of-flight measurement on a metastable hydrogen atom beam the velocity distribution of which is wide (δv/v = 1). By scanning the field velocity, the velocity distribution of a continuous H* beam is readily obtained. Extension to accelerated magnetic fields and their application to gravimetry are proposed
Dynamics of evanescent matter waves in negative-index media
International audiencenumbers: 03.75.-b Matter Waves 03.75.Be Atom and Neutron Optics 37.10.Gh Atom Traps and Guides 42.25.-p Wave Optics ABSTRACT Semi-evanescent and evanescent matter-waves produced by an atom wave packet impinging a repulsive barrier can be back-refracted and reconstructed by the application of negative-index " comoving " potential pulses. One shows that those collapses and revivals generate a matter wave confined on both sides of the barrier border (" surface matter wave ") and should be observable via the retardation of atom reflection from the barrier interface. This property, joined to the possibility recently demonstrated of inducing negative refraction of atom waves, makes such potentials a matter-wave counterpart of negative-index materials or " meta materials " well-known in light optics
Action principle formulation for motion of extended bodies in General Relativity
We present an action principle formulation for the study of motion of an
extended body in General Relativity in the limit of weak gravitational field.
This gives the classical equations of motion for multipole moments of arbitrary
order coupling to the gravitational field. In particular, a new force due to
the octupole moment is obtained. The action also yields the gravitationally
induced phase shifts in quantum interference experiments due to the coupling of
all multipole moments.Comment: Revised version derives Octupole moment force. Some clarifications
and a reference added. To appear in Phys. Rev.
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