Cryptosporidium — What is it?

Cryptosporidium is a ubiquitous enteric protozoan pathogen of vertebrates, and although recognised as a cause of disease in humans and domestic animals for over 50 years, fundamental questions concerning its biology and ecology have only recently been resolved. Overwhelming data now confirm that, like its close relatives, Cryptosporidium is a facultatively epicellular apicomplexan that is able to multiply in a host cell-free environment. These data must be considered in the context of the phylogenetic reclassification of Cryptosporidium from a coccidian to a gregarine. Together, they dictate an urgent need to reconsider the biology and behaviour of Cryptosporidium, and perhaps help to explain the parasite's incredible genetic diversity, distribution and host range. Improved imaging technologies have complemented phylogenetic studies in demonstrating the parasite's affinities with gregarine protozoa and have further supported its extracellular developmental capability and potential role as an environmental pathogen. These advances in our understanding of Cryptosporidium as a protozoan pathogen are examined with emphasis on how they may influence control strategies in the future

Luminosity distance and redshift in the Szekeres inhomogeneous cosmological models

The Szekeres inhomogeneous models can be used to model the true lumpy universe that we observe. This family of exact solutions to Einstein's equations was originally derived with a general metric that has no symmetries. In this work, we develop and use a framework to integrate the angular diameter and luminosity distances in the general Szekeres models. We use the affine null geodesic equations in order to derive a set of first-order ordinary differential equations that can be integrated numerically to calculate the partial derivatives of the null vector components. These equations allow the integration in all generality of the distances in the Szekeres models and some examples are given. The redshift is determined from simultaneous integration of the null geodesic equations. This work does not assume spherical or axial symmetry, and the results will be useful for comparisons of the general Szekeres inhomogeneous models to current and future cosmological data.Comment: 14 pages, 1 figure, matches JCAP accepted versio

Dynamics near the Surface Reconstruction of W(100)

Using Brownian molecular dynamics simulation, we study the surface dynamics near the reconstruction transition of W(100) via a model Hamiltonian. Results for the softening and broadening of the surface phonon spectrum near the transition are compared with previous calculations and with He atom scattering data. From the critical behavior of the central peak in the dynamical structure factor, we also estimate the exponent of the power law anomaly for adatom diffusion near the transition temperature.Comment: 8 pages, 8 figures, to appear in Phys. Rev.

Metabolite changes in blood predict the onset of tuberculosis

Immunogenetics and cellular immunology of bacterial infectious disease

Baffin Island Expedition, 1953: A Preliminary Field Report

Contains description and brief summaries of results of the second Baffin Island Expedition of the Arctic Institute of North America, May-Sept. 1953. The 13-man party carried out a program in the Penny Highland region of Cumberland Peninsula, centering on Pangnirtung Pass. Glaciological work on the Penny Icecap and Highway Glacier included studies of glacier physics, seismic work, and meteorological observations on bedrock geology and structure are given. Corrie formation and the geomorphology of Pangnirtung Pass were studied. Specimens of local fauna were collected and biological studies of some species were made. Comparisons of the vegetation of Penny Highland and East and North Greenland were made through extensive plant collections. Eight peaks were climbed and their altitudes determined. A list of 17 new names approved by the Canadian Board on Geographical Names is appended