On phase behavior and dynamical signatures of charged colloidal platelets

We investigate the competition between anisotropic excluded-volume and repulsive electrostatic interactions in suspensions of thin charged colloidal discs, by means of Monte-Carlo simulations and dynamical characterization of the structures found. We show that the original intrinsic anisotropy of the electrostatic potential between charged platelets, obtained within the non-linear Poisson-Boltzmann formalism, not only rationalizes the generic features of the complex phase diagram of charged colloidal platelets such as Gibbsite and Beidellite clays, but also predicts the existence of novel structures. In addition, we find evidences of a strong slowing down of the dynamics upon increasing density.Comment: 6 pages, 6 Figure

The Case for Adopting the Species Complex Nomenclature for the Etiologic Agents of Cryptococcosis

Cryptococcosis is a potentially lethal disease of humans/animals caused by Cryptococcus neoformans and Cryptococcus gattii. Distinction between the two species is based on phenotypic and genotypic characteristics. Recently, it was proposed that C. neoformans be divided into two species and C. gattii into five species based on a phylogenetic analysis of 115 isolates. While this proposal adds to the knowledge about the genetic diversity and population structure of cryptococcosis agents, the published genotypes of 2,606 strains have already revealed more genetic diversity than is encompassed by seven species. Naming every clade as a separate species at this juncture will lead to continuing nomenclatural instability. In the absence of biological differences between clades and no consensus about how DNA sequence alone can delineate a species, we recommend using Cryptococcus neoformans species complex and C. gattii species complex as a practical intermediate step, rather than creating more species. This strategy recognizes genetic diversity without creating confusion

The Case for Adopting the Species Complex Nomenclature for the Etiologic Agents of Cryptococcosis

Cryptococcosis is a potentially lethal disease of humans/animals caused by Cryptococcus neoformans and Cryptococcus gattii. Distinction between the two species is based on phenotypic and genotypic characteristics. Recently, it was proposed that C. neoformans be divided into two species and C. gattii into five species based on a phylogenetic analysis of 115 isolates. While this proposal adds to the knowledge about the genetic diversity and population structure of cryptococcosis agents, the published genotypes of 2,606 strains have already revealed more genetic diversity than is encompassed by seven species. Naming every clade as a separate species at this juncture will lead to continuing nomenclatural instability. In the absence of biological differences between clades and no consensus about how DNA sequence alone can delineate a species, we recommend using Cryptococcus neoformans species complex and C. gattii species complex as a practical intermediate step, rather than creating more species. This strategy recognizes genetic diversity without creating confusion

A population of Langerin-positive dendritic cells in murine Peyer\u27s patches involved in sampling beta-glucan microparticles

Glucan particles (GPs) are 2-4 mum hollow, porous shells composed of 1,3-beta-D-glucan that have been effectively used for oral targeted-delivery of a wide range of payloads, including small molecules, siRNA, DNA, and protein antigens. While it has been demonstrated that the transepithelial transport of GPs is mediated by Peyer\u27s patch M cells, the fate of the GPs once within gut-associated lymphoid tissue (GALT) is not known. Here we report that fluorescently labeled GPs administered to mice by gavage accumulate in CD11c+ DCs situated in Peyer\u27s patch sub-epithelial dome (SED) regions. GPs appeared in DCs within minutes after gavage and remained within the SED for days afterwards. The co-administration or sequential administration of GPs with differentially labeled GPs or poly(lactic-co-glycolic acid) nanoparticles demonstrated that the SED DC subpopulation in question was capable of internalizing particles of different sizes and material compositions. Phenotypic analysis identified the GP-containing DCs as being CD8alpha- and CD11blo/-, suggesting they are the so-called myeloid and/or double negative (DN) subset(s) of PP DCs. A survey of C-type lectin receptors (CLRs) known to be expressed by leukocytes within the intestinal mucosa revealed that GP-containing SED DCs were positive for Langerin (CD207), a CLR with specificity for beta-D-glucan and that has been shown to mediate the internalization of a wide range of microbial pathogens, including bacteria, viruses and fungi. The presence of Langerin+ DCs in the SED as determined by immunofluorescence was confirmed using Langerin E-GFP transgenic mice. In summary, our results demonstrate that following M cell-mediated transepithelial transport, GPs (and other micro/nanoparticles) are sampled by a population of SED DCs distinguished from other Peyer\u27s patch DC subsets by their expression of Langerin. Future studies will be aimed at defining the role of Langerin in antigen sampling and antigen presentation within the context of the GALT

Chord distribution functions of three-dimensional random media: Approximate first-passage times of Gaussian processes

The main result of this paper is a semi-analytic approximation for the chord distribution functions of three-dimensional models of microstructure derived from Gaussian random fields. In the simplest case the chord functions are equivalent to a standard first-passage time problem, i.e., the probability density governing the time taken by a Gaussian random process to first exceed a threshold. We obtain an approximation based on the assumption that successive chords are independent. The result is a generalization of the independent interval approximation recently used to determine the exponent of persistence time decay in coarsening. The approximation is easily extended to more general models based on the intersection and union sets of models generated from the iso-surfaces of random fields. The chord distribution functions play an important role in the characterization of random composite and porous materials. Our results are compared with experimental data obtained from a three-dimensional image of a porous Fontainebleau sandstone and a two-dimensional image of a tungsten-silver composite alloy.Comment: 12 pages, 11 figures. Submitted to Phys. Rev.

Nuclear forward scattering in particulate matter: dependence of lineshape on particle size distribution

In synchrotron Moessbauer spectroscopy, the nuclear exciton polariton manifests itself in the lineshape of the spectra of nuclear forward scattering (NFS) Fourier-transformed from time domain to frequency domain. This lineshape is generally described by the convolution of two intensity factors. One of them is Lorentzian related to free decay. We derived the expressions for the second factor related to Frenkel exciton polariton effects at propagation of synchrotron radiation in Moessbauer media. Parameters of this Frenkelian shape depend on the spatial configuration of Moessbauer media. In a layer of uniform thickness, this factor is found to be a simple hypergeometric function. Next, we consider the particles spread over a 2D surface or diluted in non-Moessbauer media to exclude an overlap of ray shadows by different particles. Deconvolving the purely polaritonic component of linewidths is suggested as a simple procedure sharpening the experimental NFS spectra in frequency domain. The lineshapes in these sharpened spectra are theoretically expressed via the parameters of the particle size distributions (PSD). Then, these parameters are determined through least-squares fitting of the line shapes.Comment: 13 pages, 12 figure

Visual and refractive outcomes following implantation of a new trifocal intraocular lens.

BACKGROUND: Independence from all optical aids, and freedom from unwanted symptoms, following cataract and lens surgery remains the ultimate goal of both patient and surgeon. The development of trifocal IOL technology provides an ever-increasing range of options. The purpose of our study is to understand the predictability, safety and efficacy of a new trifocal intraocular lens (IOL) following cataract or refractive lens exchange (RLE) surgery. METHODS: This was a retrospective consecutive case series of patients undergoing cataract extraction or RLE followed by implantation of the Alcon IQ Panoptix IOL. Pre and postoperative refractive and visual parameters were recorded and evaluated. As the cohort followed a normal distribution, standard parametric tests were used. Paired t-test was used to compare the difference between target and postoperative refractive errors. The incidence of intraoperative and postoperative complications was also reported. RESULTS: The IOL was implanted in 66 eyes of 33 patients. Mean postoperative spherical equivalent (SE) refraction was -0.08 ± 0.25 dioptres (D). This was not significantly different from the target refraction (p = 0.841). Sixty-five percent of patients were within ± 0.25 D of the target SE refraction with 100% within ± 0.50 D of intended correction. Mean postoperative uncorrected distance visual acuity (UDVA) was 0.01 ± 0.10 LogMAR. All patients achieved an unaided distance acuity of 20/40 or better postoperatively. Binocularly, 100% saw 0.20 LogMAR or better at near without correction and 88.9% achieved this level for uncorrected intermediate visual acuity. No intraoperative complications were noted. Five patients complained of moderate haloes in the early postoperative period. CONCLUSION: The AcrySof IQ Panoptix IOL provides functional uncorrected visual acuity at distance, intermediate and near positions. Our results remain equivalent with existing trifocal IOL outcomes and provide surgeons with a further IOL alternative for the patient motivated to obtain true spectacle independence. Surgeons should consider individual reading and working requirements when counselling patients preoperatively to optimise postoperative patient satisfaction

Towards deterministic equations for Levy walks: the fractional material derivative

Levy walks are random processes with an underlying spatiotemporal coupling. This coupling penalizes long jumps, and therefore Levy walks give a proper stochastic description for a particle's motion with broad jump length distribution. We derive a generalized dynamical formulation for Levy walks in which the fractional equivalent of the material derivative occurs. Our approach will be useful for the dynamical formulation of Levy walks in an external force field or in phase space for which the description in terms of the continuous time random walk or its corresponding generalized master equation are less well suited