Comment on: Diffusion through a slab

Mahan [J. Math. Phys. 36, 6758 (1995)] has calculated the transmission coefficient and angular distribution of particles which enter a thick slab at normal incidence and which diffuse in the slab with linear anisotropic, non-absorbing, scattering. Using orthogonality relations derived by McCormick & Kuscer [J. Math. Phys. 6, 1939 (1965); 7, 2036 (1966)] for the eigenfunctions of the problem, this calculation is generalised to a boundary condition with particle input at arbitrary angles. It is also shown how to use the orthogonality relations to relax in a simple way the restriction to a thick slab.Comment: 3 pages, LaTeX, uses RevTe

The type three secreted effector SipC regulates the trafficking of PERP during Salmonella infection

Salmonella enterica Typhimurium employs type III secreted effectors to induce cellular invasion and pathogenesis. We previously reported the secreted effector SipA is in part responsible for inducing the apical accumulation of the host membrane protein PERP, a host factor we have shown is key to the inflammatory response induced by Salmonella. We now report that the S. Typhimurium type III secreted effector SipC significantly contributes to PERP redistribution to the apical membrane surface. To our knowledge, this is the first report demonstrating a role for SipC in directing the trafficking of a host membrane protein to the cell surface. In sum, facilitation of PERP trafficking appears to be a result of type III secreted effector-mediated recruitment of vesicles to the apical surface. Our study therefore reveals a new role for SipC, and builds upon previous reports suggesting recruitment of vesicles to the cell surface is important for Salmonella invasion

Salmonella Pathogenesis and Processing of Secreted Effectors by Caspase-3

The enteric pathogen Salmonella enterica serovar Typhimurium causes food poisoning resulting in gastroenteritis. The S. Typhimurium effector Salmonella invasion protein A (SipA) promotes gastroenteritis by functional motifs that trigger either mechanisms of inflammation or bacterial entry. During infection of intestinal epithelial cells, SipA was found to be responsible for the early activation of caspase-3, an enzyme that is required for SipA cleavage at a specific recognition motif that divided the protein into its two functional domains and activated SipA in a manner necessary for pathogenicity. Other caspase-3 cleavage sites identified in S. Typhimurium appeared to be restricted to secreted effector proteins, which indicates that this may be a general strategy used by this pathogen for processing of its secreted effectors

Are Pileated Woodpeckers Attracted to Red-Cockaded Woodpecker Cavity Trees?

Pileated Woodpeckers (Dryocopus pileatus) cause damage to Red-cockaded Woodpecker (Picoides borealis) cavity trees in the form of cavity enlargement or other excavations on the surface of the pine tree. However, it is not known whether Pileated Woodpeckers excavate more frequently on Red-cockaded Woodpecker cavity trees than on noncavity trees or how stand structure is related to the frequency of Pileated Woodpecker excavation. Also, it is unclear whether the cavity itself provides the stimulus to Pileated Woodpeckers to excavate or whether the presence of Red-cockaded Woodpeckers and their activities are attracting them. We surveyed all of the Red-cockaded Woodpecker cavity trees (n = 202) and 110 control trees in the loblolly (Pinus taeda)-shortleaf (P. echinata) pine habitat on the Angelina National Forest for recent Pileated Woodpecker excavation and found that approximately 7.4% of all cavity trees were damaged while no control trees showed any evidence of Pileated Woodpecker damage. The rate of Pileated Woodpecker excavation was negatively associated with hardwood midstory height and density. Pileated Woodpeckers appeared to focus most of their excavations on Red-cockaded Woodpeckers cavity entrances. WC suggest that Pileated Woodpeckers may be attracted to Red-cockaded Woodpecker cavity trees. especially the cavity, and that midstory removal used to improve Red-cockaded Woodpecker habitat may increase the incidence of damage to the cavity trees by Pileated Woodpeckers in the current fragmented landscape

An unusually large number of eggs laid by a breeding red-cockaded woodpecker female

The Red-cockaded Woodpecker (Picoides borealis) is a cooperatively breeding species that typically uses a single cavity for nesting (Ligon 1970, Walters et al. 1988). A single tree, or aggregation of cavity trees, termed the cluster, is inhabited by a group of woodpeckers that includes a single breeding pair and up to several helpers, which are typically male offspring of previous breeding seasons (Ligon 1970, Lennartz et al. 1987). Each group of Red-cockaded Woodpeckers usually produces one nest per breeding season, but will often nest again during the same breeding season if the first nest fails. Double clutching and double brooding (where both nests are successful) are known to occur in Red-cockaded Woodpeckers in the southern and northern portion of the species\u27 range (LaBranche et al. 1994, Franzreb 1997, Phillips et al. 1998)

Delayed reproduction of translocated Red-cockaded Woodpeckers.

Twelve pairs of Red-cockaded Woodpeckers were translocated to the Angelina National Forest. Five breeding pairs produced eggs/nestlings within the first breeding season after translocation. Clutch initiation dates for all five pairs were later than those of resident breeders. The observed delay in reporductive timing by translocated woodpeckers may have resulted from a variety of factors