Surface oxidation of liquid Sn

We report the results of an x-ray scattering study that reveals oxidation kinetics and formation of a previously unreported crystalline phase of SnO at the liquid-vapour interface of Sn. Our experiments reveal that the pure liquid Sn surface does not react with molecular oxygen below an activation pressure of \~5.0*10-6 Torr. Above that pressure a rough solid Sn oxide grows over the liquid metal surface. Once the activation pressure has been exceeded the oxidation proceeds at pressures below the oxidation pressure threshold. The observed diffraction pattern associated with the surface oxidation does not match any of the known Sn oxide phases. The data have an explicit signature of the face-centred cubic structure, however it requires lattice parameters that are about 9% smaller than those reported for cubic structures of high-pressure phases of Sn oxides. Keywords: X-ray scattering, diffraction, and reflection; Oxidation; Surface chemical reaction; Surface structure, morphology, roughness, and topography; Tin; Tin oxides; Liquid surfaces; Polycrystalline thin filmsComment: 18 pages, 6 figures, 1 table; Submitted to Surface Scienc

Parent-reported and clinician-observed autism spectrum disorder (ASD) symptoms in children with attention deficit/hyperactivity disorder (ADHD): implications for practice under DSM-5

BACKGROUND: Children with attention deficit/hyperactivity disorder (ADHD) often present with social difficulties, though the extent to which these clearly overlap with symptoms of autism spectrum disorder (ASD) is not well understood. METHODS: We explored parent-reported and directly-observed ASD symptoms on the Autism Diagnostic Interview-Revised (ADI-R) and the Autism Diagnostic Observation Schedule (ADOS) in children referred to ASD-specialty clinics who received diagnoses of either ADHD (n = 48) or ASD (n = 164). RESULTS: Of the ADHD sample, 21 % met ASD cut-offs on the ADOS and 30 % met ASD cut-offs on all domains of the ADI-R. Four social communication ADOS items (Quality of Social Overtures, Unusual Eye Contact, Facial Expressions Directed to Examiner, and Amount of Reciprocal Social Communication) adequately differentiated the groups while none of the items on the ADI-R met the criteria for adequate discrimination. CONCLUSIONS: Results of this work highlight the challenges that clinicians and researchers face when distinguishing ASD from other disorders in verbally fluent, school-age children

City of Toledo Flag, Toledo, Ohio, 1955

A drawing done by Franklin M. Ronk of the City of Toledo's Division of Engineering and Construction showing the exact dimensions of the city flag. The flag has an image of a red blockhouse in the middle and has two blue and one white wide vertical stripes. the flag was adopted by Toledo City Council in January of 1909. Terms associated with the photograph are: flags - Ohio - Toledo | drawings and graphics | City of Toledo (Ohio

Dispersal limitation determines large-scale dark diversity in Central and Northern Europe

Aim Previous studies indicate that many plant species present in a surrounding region are absent from potentially suitable sites (i.e. they constitute dark diversity). However, quantitative analyses are lacking where and why dispersal limitation occurs within species occurrence range at the continental scale. We test if species characteristics related to dispersal limitation, that is, low seed production and short potential dispersal distance, affect the formation of dark diversity at large spatial scales. In addition, we explore how the levels of dispersal limitation are affected by climate, landscape heterogeneity and anthropogenic activity. Location Seven study areas in Central and Northern Europe – Iceland, Finland, Estonia, the British Isles, the Netherlands, Germany and Switzerland. Methods We used data on vascular plant species occurrences in ca. 10 × 10 km grid cells from each study area. To estimate dark diversity for each grid cell, we applied geographical, biogeographical and environmental filters. Seed production was estimated directly (number of seeds per ramet), and indirectly from seed mass. We used several plant traits in combination (e.g. dispersal syndrome and seed characteristics) to estimate potential dispersal distance of seeds. Results Species contributing to dark diversity produced generally fewer seeds and had shorter potential dispersal distances than observed species. Dispersal limitation tended to decrease with increasing environmental stress, human population density and agricultural land use. Main conclusions Many species are absent from potentially suitable sites in Central and Northern Europe because of dispersal limitation, induced by low seed production and short potential dispersal distances. However, strong abiotic stress, biotic resistance and human activities have reduced the importance of dispersal limitation. This knowledge can be considered in the predictions of how changes in climate and land use affect biodiversity in the future