21 research outputs found
Coulomb correlations of a few body system of spatially separated charges
A Hartree-Fock and Hartree-Fock-Bogoliubov study of a few body system of
spatially separated charge carriers was carried out. Using these variational
states, we compute an approximation to the correlation energy of a finite
system of electron-hole pairs. This energy is shown as a function of the
Coulomb coupling and the interplane distance. We discuss how the correlation
energy can be used to theoretically determine the formation of indirect
excitons in semiconductors which is relevant for collective phenomena such as
Bose-Einstein condensation (BEC).Comment: Conference EDISON16 (2009), 4 page
Many-body mobility edge due to symmetry-constrained dynamics and strong interactions
We provide numerical evidence combined with an analytical understanding of the many-body mobility edge for
the strongly anisotropic spin-1/2 XXZ model in a random magnetic field. The system dynamics can be understood
in terms of symmetry-constrained excitations about parent states with ferromagnetic and antiferromagnetic short
range order. These two regimes yield vastly different dynamics producing an observable, tunable many-body
mobility edge. We compute a set of diagnostic quantities that verify the presence of the mobility edge and discuss
how weakly correlated disorder can tune the mobility edge further
Magnetic phases of bosons with synthetic spin-orbit coupling in optical lattices
We investigate magnetic properties in the superfluid and Mott-insulating
states of two-component bosons with spin-orbit (SO) coupling in 2D square
optical lattices. The spin-independent hopping integral and SO coupled one
are fitted from band structure calculations in the continuum, which
exhibit oscillations as increasing SO coupling strength. The magnetic
superexchange model is derived in the Mott-insulating state with one-particle
per-site, characterized by the Dzyaloshinsky-Moriya (DM) interaction. In the
limit of , we find a spin spiral Mott state whose pitch value
is the same as that in the incommensurate superfluid state, while in the
opposite limit , the ground state can be found by a dual
transformation to the limit.Comment: 4.2 page
Antibody response to sand fly saliva is a marker of transmission intensity but not disease progression in dogs naturally infected with Leishmania infantum
BACKGROUND: Antibody responses to sand fly saliva have been suggested to be a useful marker of exposure to sand fly bites and Leishmania infection and a potential tool to monitor the effectiveness of entomological interventions. Exposure to sand fly bites before infection has also been suggested to modulate the severity of the infection. Here, we test these hypotheses by quantifying the anti-saliva IgG response in a cohort study of dogs exposed to natural infection with Leishmania infantum in Brazil. METHODS: IgG responses to crude salivary antigens of the sand fly Lutzomyia longipalpis were measured by ELISA in longitudinal serum samples from 47 previously unexposed sentinel dogs and 11 initially uninfected resident dogs for up to 2 years. Antibody responses were compared to the intensity of transmission, assessed by variation in the incidence of infection between seasons and between dogs. Antibody responses before patent infection were then compared with the severity of infection, assessed using tissue parasite loads and clinical symptoms. RESULTS: Previously unexposed dogs acquired anti-saliva antibody responses within 2 months, and the rate of acquisition increased with the intensity of seasonal transmission. Over the following 2 years, antibody responses varied with seasonal transmission and sand fly numbers, declining rapidly in periods of low transmission. Antibody responses varied greatly between dogs and correlated with the intensity of transmission experienced by individual dogs, measured by the number of days in the field before patent infection. After infection, anti-saliva antibody responses were positively correlated with anti-parasite antibody responses. However, there was no evidence that the degree of exposure to sand fly bites before infection affected the severity of the infection. CONCLUSIONS: Anti-saliva antibody responses are a marker of current transmission intensity in dogs exposed to natural infection with Leishmania infantum, but are not associated with the outcome of infection