A visual sense of number

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Perceptual Oscillations in Gender Classification of Faces, Contingent on Stimulus History

Perception is a proactive ‘‘predictive’’ process, in which the brain takes advantage of past experience to make informed guesses about the world to test against sensory data. Here we demonstrate that in the judgment of the gender of faces, beta rhythms play an important role in communicating perceptual experience. Observers classified in forced choice as male or female, a sequence of face stimuli, which were physically constructed to be male or female or androgynous (equal morph). Classification of the androgynous stimuli oscillated rhythmically between male and female, following a complex waveform comprising 13.5 and 17 Hz. Parsing the trials based on the preceding stimulus showed that responses to androgynous stimuli preceded by male stimuli oscillated reliably at 17 Hz, whereas those preceded by female stimuli oscillated at 13.5 Hz. These results suggest that perceptual priors for face perception from recent perceptual memory are communicated through frequency-coded beta rhythms

Twitching motility among pathogenic Xylella fastidiosa isolates and the influence of bovine serum albumin on twitching-dependent colony fringe morphology

Fourteen Xylella fastidiosa isolates from grapevines exhibiting Pierce's disease symptoms in California, Texas, and South Carolina were examined for type IV pilus-mediated twitching motility, a phenotype previously observed in a Temecula isolate from California. All isolates except one from South Carolina (SC 19A97) exhibited colonies with a peripheral fringe on PW agar, a feature indicative of twitching motility; however, when individual cells of SC 19A97 were examined at higher magnifications twitching motility was observed. The presence and width of colony peripheral fringes were related to the amount of bovine serum albumin (BSA) present in the medium; no or low levels of BSA (0-1.8 g L−1) permitted development of the widest fringe, whereas higher levels (3.5-6.0 g L−1) severely limited, and in many instances prevented, peripheral fringe development. The growth rate of the wild-type Temecula isolate in PW broth with different concentrations of BSA was similar for all tested concentrations of BSA; however, growth was significantly reduced in medium without BS

Cosmogenic C-14 in Antarctic and non-Antarctic meteorites and lunar samples

We were able to develop measurements of C-14 in meteorites as a useful tool for estimates of terrestrial age. Prior to this accomplishment, only a few measurements of C-14 terrestrial ages had been made. The sample sizes were larger, and there had been no systematic study of the various parameters affecting production of C-14, such as depth dependence, and the production cross sections for C-14 from spallation amounted to a few data points. Presently, C-14 ages are an accepted terrestrial age estimate in the meteorite community, whereas before this work the few data available were difficult to interpret. We have obtained terrestrial ages not only on groups of meteorites from different geographic areas but also information on unique meteorites from particularly interesting groups, such as meteorites originating from the Moon, or SNC meteorites, which many researchers believe are derived from Mars

From solid solution to cluster formation of Fe and Cr in α\alpha-Zr

To understand the mechanisms by which Fe and Cr additions increase the corrosion rate of irradiated Zr alloys, a combination of experimental (atom probe tomography, x-ray diffraction and thermoelectric power measurements) and modelling (density functional theory) techniques are employed to investigate the non-equilibrium solubility and clustering of Fe and Cr in binary Zr alloys. Cr occupies both interstitial and substitutional sites in the {\alpha}-Zr lattice, Fe favours interstitial sites, and a low-symmetry site that was not previously modelled is found to be the most favourable for Fe. Lattice expansion as a function of alloying concentration (in the dilute regime) is strongly anisotropic for Fe additions, expanding the $c$-axis while contracting the $a$-axis. Defect clusters are observed at higher solution concentrations, which induce a smaller amount of lattice strain compared to the dilute defects. In the presence of a Zr vacancy, all two-atom clusters are more soluble than individual point defects and as many as four Fe or three Cr atoms could be accommodated in a single Zr vacancy. The Zr vacancy is critical for the increased solubility of defect clusters, the implications for irradiation induced microstructure changes in Zr alloys are discussed.Comment: 15 pages including figure, 9 figures, 2 tables. Submitted for publication in Acta Mater, Journal of Nuclear Materials (2015

Angoff anchor statements: setting a flawed gold standard?

http://www.mededpublish.org/manuscripts/120

Bisphosphonates alter trabecular bone collagen cross-linking and isomerization in beagle dog vertebra

Changes in organic matrix may contribute to the anti-fracture efficacy of anti-remodeling agents. Following one year of treatment in beagle dogs, bisphosphonates alter the organic matrix of vertebral trabecular bone, while raloxifene had no effect. These results show that pharmacological suppression of turnover alters the organic matrix component of bone. INTRODUCTION: The collagen matrix contributes significantly to a bone's fracture resistance yet the effects of anti-remodeling agents on collagen properties are unclear. The goal of this study was to assess changes in collagen cross-linking and isomerization following anti-remodeling treatment. METHODS: Skeletally mature female beagles were treated for one year with oral doses of vehicle (VEH), risedronate (RIS; 3 doses), alendronate (ALN; 3 doses), or raloxifene (RAL; 2 doses). The middle dose of RIS and ALN and the lower dose of RAL approximate doses used for treatment of post menopausal osteoporosis. Vertebral trabecular bone matrix was assessed for collagen isomerization (ratio of alpha/beta C-telopeptide [CTX]), enzymatic (pyridinoline [PYD] and deoxypyridinoline [DPD]), and non-enzymatic (pentosidine [PEN]) cross-links. RESULTS: All doses of both RIS and ALN increased PEN (+34-58%) and the ratio of PYD/DPD (+14-26%), and decreased the ratio of alpha/beta CTX (-29-56%) compared to VEH. RAL did not alter any collagen parameters. Bone turnover rate was significantly correlated to PEN (R = -0.664), alpha/beta CTX (R = 0.586), and PYD/DPD (R = -0.470). CONCLUSIONS: Bisphosphonate treatment significantly alters properties of bone collagen suggesting a contribution of the organic matrix to the anti-fracture efficacy of this drug class.The authors thank Dr. Keith Condon, Diana Jacob, Mary Hooser, and Lauren Waugh for histological preparation. This work was supported by NIH Grants AR047838 and AR007581 and research grants from The Alliance for Better Bone Health (Procter & Gamble Pharmaceuticals and sanofi-aventis), and Lilly Research Laboratories, as well as an unrestricted grant from Eli Lilly to INSERM. Merck and Co. kindly provided the alendronate. This investigation utilized an animal facility constructed with support from Research Facilities Improvement Program Grant Number C06 RR10601-01 from the National Center for Research Resources, National Institutes of Health

Xylella fastidiosa pil-chp operon is involved in regulating key structural genes of both type I and IV pili

Xylella fastidiosa is the causal agent of Pierce's disease (PD) in grapevines. It has type I and type IV pili, which are both virulence factors involved in the PD-associated processes of motility, aggregation, and biofilm formation. Many questions remain as to how the two pili are regulated. We previously identified a X. fastidiosa pil-chp chemosensory-like cluster as an operon composed of genes pilG-I-J-L-chpB-C. In this study, we deleted pilG (resulting in a ∆pilG-I strain) and pilJ and discovered that both mutants (∆pilG-I and ∆pilJ) had reduced virulence after 24 weeks post-inoculation, whereas ∆chpB and ∆chpC did not. Both ∆pilG-I and ∆pilJ lost motility and were impaired in biofilm formation in rich artificial media and xylem sap. Gene expression was significantly downregulated for representative fimbrial adhesin and motility genes in ∆pilG-I, and to a lesser extent in ∆pilJ. Our data suggest that Pil, but not Chp, proteins are virulence factors, and pilG-I-J are involved in transcriptional regulation of type I and IV pili virulence genes and therefore motility and biofilm formation. To our knowledge, this is the first report of a chemotaxis-like operon involved in the regulation of key structural genes of both type I and type IV pili