Sustainable preservation: language choice in complex multilingual settings

Track 4. Language and Sustainable Development Empowerment of Indigenous CommunitiespostprintThe International Conference on Language, Education and the Millennium Development Goals (MDGs), Bangkok, Thailand, 9-11 November 2010

Intestinal Immunity to the Commensal Bacterium Akkermansia muciniphila

Intestinal immunity plays critical roles in maintaining host health. Despite the abundance of foreign antigens and activated lymphocytes in the intestine, only a few commensal bacteria that induce cognate adaptive immune responses during homeostasis have been identified. In this dissertation, I reveal that Akkermansia muciniphila, an intestinal bacterium associated with beneficial effects on host metabolism and cancer immunotherapy, induces cognate T-dependent immunoglobulin G1 (IgG1) and IgA antibody responses and antigen-specific T cell responses during homeostasis. In contrast to the select few examples of previously characterized mucosal responses to commensal bacteria, T cell responses to A. muciniphila are limited to T follicular helper cells in the Peyer’s patches in a gnotobiotic setting, without appreciable induction of other T helper fates or migration to the lamina propria. However, A. muciniphila-specific responses are context-dependent, and adopt other T helper fates in the setting of a conventional microbiota. These findings suggest that contextual signals influence T cell immunity to the microbiota and modulate host immune function during homeostasis. Interestingly, T cells specific to A. muciniphila expand dramatically in a novel (but still uncharacterized) genetic mouse model of intestinal inflammation, suggesting that this bacterium may become a major mucosal antigen when homeostasis is disrupted. If so, T cell immunity to A. muciniphila may play critical roles during infection and inflammatory bowel diseases

Static magnetic order in metallic K0.49_{0.49}CoO2_{2}

By means of muon spin spectroscopy, we have found that K$_{0.49}$CoO$_2$ crystals undergo successive magnetic transitions from a high-T paramagnetic state to a magnetic ordered state below 60 K and then to a second ordered state below 16 K, even though K_{0.49}CoO_2 is metallic at least down to 4 K. An isotropic magnetic behavior and wide internal-field distributions suggest the formation of a commensurate helical spin density wave (SDW) state below 16 K, while a linear SDW state is likely to exist above 16 K. It was also found that K_{0.49}CoO_2 exhibits a further transition at 150 K presumably due to a change in the spin state of the Co ions. Since the T dependence of the internal-field below 60 K was similar to that for Na_{0.5}CoO_2, this suggests that magnetic order is more strongly affected by the Co valence than by the interlayer distance/interaction and/or the charge-ordering.Comment: 4 pages, 5 figures, accepted for publication in Phys. Rev. Let

The magnetic structure of the zigzagzigzag chain family Nax_{x}Ca1−x_{1-x}V2_2O4_4 determined by muon-spin rotation

We present muon-spin rotation measurements on polycrystalline samples of the complete family of the antiferromagnetic (AF) $zigzag$ chain compounds, Na$_x$Ca$_{1-x}$V$_2$O$_4$. In this family, we explore the magnetic properties from the metallic NaV$_2$O$_4$ to the insulating CaV$_2$O$_4$. We find a critical $x_c(\sim0.833)$ which separates the low and high Na-concentration dependent transition temperature and its magnetic ground state. In the $x<x_c$ compounds, the magnetic ordered phase is characterized by a single homogenous phase and the formation of incommensurate spin-density-wave order. Whereas in the $x>x_c$ compounds, multiple sub-phases appear with temperature and $x$. Based on the muon data obtained in zero external magnetic field, a careful dipolar field simulation was able to reproduce the muon behavior and indicates a modulated helical incommensurate spin structure of the metallic AF phase. The incommensurate modulation period obtained by the simulation agrees with that determined by neutron diffraction.Comment: 7 pages, 7 figures, accepted for publication in PR