25 research outputs found
Specific Heat Study of 1D and 2D Excitations in the Layered Frustrated Quantum Antiferromagnets CsCuClBr
We report an experimental and theoretical study of the low-temperature
specific heat and magnetic susceptibility of the layered anisotropic
triangular-lattice spin-1/2 Heisenberg antiferromagnets
CsCuClBr with = 0, 1, 2, and 4. We find that the ratio
of the exchange couplings ranges from 0.32 to , implying a
change (crossover or quantum phase transition) in the materials' magnetic
properties from one-dimensional (1D) behavior for to
two-dimensional (2D) behavior for behavior. For , realized for = 0, 1, and 4, we find a magnetic contribution to the
low-temperature specific heat, , consistent with spinon
excitations in 1D spin-1/2 Heisenberg antiferromagnets. Remarkably, for =
2, where implies a 2D magnatic character, we also observe
. This finding, which contrasts the prediction of made by standard spin-wave theories, shows that Fermi-like
statistics also plays a significant role for the magnetic excitations in
frustrated spin-1/2 2D antiferromagnets
Modulation of Transcriptional and Inflammatory Responses in Murine Macrophages by the Mycobacterium tuberculosis Mammalian Cell Entry (Mce) 1 Complex
The outcome of many infections depends on the initial interactions between agent and host. Aiming at elucidating the effect of the M. tuberculosis Mce1 protein complex on host transcriptional and immunological responses to infection with M. tuberculosis, RNA from murine macrophages at 15, 30, 60 min, 4 and 10 hrs post-infection with M. tuberculosis H37Rv or Δ-mce1 H37Rv was analyzed by whole-genome microarrays and RT-QPCR. Immunological responses were measured using a 23-plex cytokine assay. Compared to uninfected controls, 524 versus 64 genes were up-regulated by 15 min post H37Rv- and Δ-mce1 H37Rv-infection, respectively. By 15 min post-H37Rv infection, a decline of 17 cytokines combined with up-regulation of Ccl24 (26.5-fold), Clec4a2 (23.2-fold) and Pparγ (10.5-fold) indicated an anti-inflammatory response initiated by IL-13. Down-regulation of Il13ra1 combined with up-regulation of Il12b (30.2-fold), suggested switch to a pro-inflammatory response by 4 hrs post H37Rv-infection. Whereas no significant change in cytokine concentration or transcription was observed during the first hour post Δ-mce1 H37Rv-infection, a significant decline of IL-1b, IL-9, IL-13, Eotaxin and GM-CSF combined with increased transcription of Il12b (25.1-fold) and Inb1 (17.9-fold) by 4 hrs, indicated a pro-inflammatory response. The balance between pro-and anti-inflammatory responses during the early stages of infection may have significant bearing on outcome
Cryogenic vacuum tests of scaled down narrow support elements (NSE) for the W7-X coil system
Ion and electron cyclotron wall conditioning in stellarator and tokamak magnetic field configuration on WEGA
Lateral-size effects and supercurrent blockade at mechanical-controllable break junktions of the heavy-fermion superconductors
Lateral-size effects and supercurrent blockade at mechanical-controllable break junktions of the heavy-fermion superconductors / G. R. Stewart ... - In: Journal of low temperature physics. 110. 1998. S. 873-88
Lateral-Size Effects and Supercurrent Blockade at Mechanical-Controllable Break Junctions of the Heavy-Fermion Superconductors
Lateral-size effects and supercurrent blockade at mechanical-controllable break junktions of the heavy-fermion superconductors / G. R. Stewart ... - In: Journal of low temperature physics. 110. 1998. S. 873-88