6,081 research outputs found
Molecular Diagnostic Tests for Microsporidia
The Microsporidia are a ubiquitous group of eukaryotic obligate intracellular parasites which were recognized over 100 years ago with the description of Nosema bombycis, a parasite of silkworms. It is now appreciated that these organisms are related to the Fungi. Microsporidia infect all major animal groups most often as gastrointestinal pathogens; however they have been reported from every tissue and organ, and their spores are common in environmental sources such as ditch water. Several different genera of these organisms infect humans, but the majority of infections are due to either
Enterocytozoon bieneusi or Encephalitozoon species. These pathogens can be difficult to diagnose, but significant progress has been made in the last decade in the development of molecular diagnostic reagents for these organisms. This report reviews the molecular diagnostic tests that have been described for the identification of the microsporidia that infect humans
Anisotropic elasticity in confocal studies of colloidal crystals
We consider the theory of fluctuations of a colloidal solid observed in a
confocal slice. For a cubic crystal we study the evolution of the projected
elastic properties as a function of the anisotropy of the crystal using
numerical methods based on the fast Fourier transform. In certain situations of
high symmetry we find exact analytic results for the projected fluctuations.Comment: 6 pages, 7 figure
Truncated correlations in video microscopy of colloidal solids
Studies by video microscopy on fluctuating colloids measure the real-space
cross-correlations in particle motion. This set of correlations is then treated
as a matrix, in order to study the spectrum and mode structure. We show that in
general the modes are modified by the truncation of the full real-space
correlations. We perform a theoretical analysis of the truncation, find the
boundary conditions imposed by the truncation, and propose practical windowing
strategies to eliminate artefacts. We study the problem from various
perspectives, to compile a survey for experimentalists.Comment: 11 pages, 9 figure
Order-by-disorder in the antiferromagnetic Ising model on an elastic triangular lattice
Geometrically frustrated materials have a ground-state degeneracy that may be
lifted by subtle effects, such as higher order interactions causing small
energetic preferences for ordered structures. Alternatively, ordering may
result from entropic differences between configurations in an effect termed
order-by-disorder. Motivated by recent experiments in a frustrated colloidal
system in which ordering is suspected to result from entropy, we consider in
this paper, the antiferromagnetic Ising model on a deformable triangular
lattice. We calculate the displacements exactly at the microscopic level, and
contrary to previous studies, find a partially disordered ground state of
randomly zigzagging stripes. Each such configuration is deformed differently
and thus has a unique phonon spectrum with distinct entropy, thus lifting the
degeneracy at finite temperature. Nonetheless, due to the free-energy barriers
between the ground-state configurations, the system falls into a disordered
glassy state.Comment: Accepted to PNA
A new vesicular compartment in Encephalitozoon cuniculi
Abstract The microsporidia are emerging human and veterinary pathogens known to infect every tissue type and organ system. Their infectious spore possesses a number of peculiar organelles, including the diagnostic polar tube. In a proteomics-driven effort to find novel components of this organelle in the human-pathogenic species Encephalitozoon cuniculi, we unexpectedly discovered a protein which localizes to punctate structures consistent with the appearance of relic mitochondria, or mitosomes. However, this novel protein did not colocalize with ferredoxin, a mitochondrial ironesulfur cluster protein which shows a similar localization pattern by light microscopy. The distribution pattern of this protein thus suggests either a novel vesicular compartment that is similar to mitosomes in size and distribution, the presence of subdomains or branching architecture within mitosomes, or heterogeneity in the protein composition of E. cuniculi mitosomes
Constraints on the χ_(c1) versus χ_(c2) polarizations in proton-proton collisions at √s = 8 TeV
The polarizations of promptly produced χ_(c1) and χ_(c2) mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at √s=8 TeV. The χ_c states are reconstructed via their radiative decays χ_c → J/ψγ, with the photons being measured through conversions to e⁺e⁻, which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the χ_(c2) to χ_(c1) yield ratio as a function of the polar or azimuthal angle of the positive muon emitted in the J/ψ → μ⁺μ⁻ decay, in three bins of J/ψ transverse momentum. While no differences are seen between the two states in terms of azimuthal decay angle distributions, they are observed to have significantly different polar anisotropies. The measurement favors a scenario where at least one of the two states is strongly polarized along the helicity quantization axis, in agreement with nonrelativistic quantum chromodynamics predictions. This is the first measurement of significantly polarized quarkonia produced at high transverse momentum
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