Description: The spectra of several high-redshift ( z 〉 6) quasars have shown indications for a Gunn–Peterson (GP) damping wing, suggesting a substantial mean neutral hydrogen fraction ( $\bar{x}_{\rm H\,{\scriptscriptstyle I}}^{\rm IGM}\gtrsim 0.03$ ) in the z 6 intergalactic medium (IGM). However, previous analyses assumed that the IGM was uniformly ionized outside of the quasar’s H  ii region. Here we relax this assumption and model patchy reionization scenarios for a range of IGM and quasar parameters. Compared to uniform reionization, patchy reionization imprints a different average damping wing profile with an associated sightline-to-sightline scatter. We quantify the impact of these differences on the inferred $\bar{x}_{\rm H\,{\scriptscriptstyle I}}^{\rm IGM}$ , by fitting the spectra of three quasars: SDSS J1148+5251 ( z = 6.4189), J1030+0524 ( z = 6.308) and J1623+3112 ( z = 6.247). We find that the best-fitting values of $\bar{x}_{\rm H\,{\scriptscriptstyle I}}^{\rm IGM}$ in the patchy models agree well with the uniform case. More importantly, we confirm that the observed spectra favour the presence of a GP damping wing, with peak likelihoods decreasing by factors of few–10 when the spectra are modelled without a damping wing. We also find that the Lyα absorption spectra, by themselves, cannot distinguish the damping wing in a relatively neutral IGM from a damping wing in a highly ionized IGM, caused either by an isolated neutral patch or by a damped Lyα absorber (DLA). However, neutral patches in a highly ionized universe ( $\bar{x}_{\rm H\,{\scriptscriptstyle I}}^{\rm IGM}\lesssim 10^{-2}$ ) and DLAs with the large required column densities ( $N_{\rm H\,{\small I}}\gtrsim {\rm { few}}\times 10^{20}{\rm { cm}^{-2}}$ ) are both rare. As a result, when we include reasonable prior probabilities for the line of sight (LOS) to intercept either a neutral patch or a DLA at the required distance of ~ 40-60 comoving Mpc away from the quasar, we find strong lower limits on the neutral fraction in the IGM, $\bar{x}_{\rm H\,{\scriptscriptstyle I}}^{\rm IGM}\gtrsim 0.1$ (at 95 per cent confidence). This supports earlier claims that a substantial global fraction of hydrogen in the z 6 IGM is in neutral form.

Description: Bacillus cereus strains harboring a pXO1-like virulence plasmid cause respiratory anthrax-like disease in humans, particularly in welders. We developed mouse models for intraperitoneal as well as aerosol challenge with spores of B. cereus G9241, harboring pBCXO1 and pBC218 virulence plasmids. Compared to wild-type B. cereus G9241, spores with a deletion of the pBCXO1-carried protective antigen gene ( pagA1 ) were severely attenuated, whereas spores with a deletion of the pBC218-carried protective antigen homologue ( pagA2 ) were not. Anthrax vaccine adsorbed (AVA) immunization raised antibodies that bound and neutralized the pagA1 -encoded protective antigen (PA1) but not the PA2 orthologue encoded by pagA2 . AVA immunization protected mice against a lethal challenge with spores from B. cereus G9241 or B. cereus Elc4, a strain that had been isolated from a fatal case of anthrax-like disease. As the pathogenesis of B. cereus anthrax-like disease in mice is dependent on pagA1 and PA-neutralizing antibodies provide protection, AVA immunization may also protect humans from respiratory anthrax-like death.