Keele University

About: Keele University is a education organization based out in Newcastle-under-Lyme, United Kingdom. It is known for research contribution in the topics: Population & Stars. The organization has 11318 authors who have published 26323 publications receiving 894671 citations. The organization is also known as: Keele University.

Aragonite-Calcite Relationships in Speleothems (Grotte De Clamouse, France): Environment, Fabrics, and Carbonate Geochemistry

Abstract: In Grotte de Clamouse (France), aragonite forms in a variety of crystal habits whose properties reflect the conditions of formation. Prolonged degassing and evaporation yield needle aragonite, which is more enriched in 18O and 13C than aragonite ray crystals, which form near isotopic equilibrium. At present, aragonite ray crystals form at the tops of stalagmites at very low discharge (0.00035 ml/ min), and when fluid Mg/Ca ratio is > 1.1. Temperature and evaporation do not seem to have a significant role in their formation. The presence of aragonite in stalagmites should be indicative of a decrease in drip rate related to either dry climate conditions or local hydrology. Fossil aragonite was in part replaced by calcite in a time frame 13C signal and U content), and preserved aragonite relicts (up to 16 weight %). The isotope signal of different aragonite habits may reflect conditions of formation rather than climate parameters. The real extent of aragonite-to-calcite transformation may be underestimated when replacement calcite inherits both textural and chemical properties of the precursor.

Computer-simulation studies of intrinsic defects in LiNbO3 crystals

Abstract: We have performed an atomistic simulation study of the defect structure of ${\mathrm{LiNbO}}_{3}$ crystals resulting from ${\mathrm{Li}}_{2}$O deficiency and reduction treatments. ${\mathrm{Li}}_{2}$O excess is found to be unlikely in ${\mathrm{LiNbO}}_{3}$ crystals. It is shown that oxygen vacancies are not the dominant intrinsic defect species in ${\mathrm{LiNbO}}_{3}$. Important defects are (${\mathrm{Nb}}_{\mathrm{Li}{}^{4\mathrm{up}20.{\mathrm{V}}_{\mathrm{Nb}{}^{5\mathcal{'}})\mathcal{'}}}}$ and isolated ${\mathrm{Nb}}_{\mathrm{Li}{}^{4\mathrm{up}20.}}$ antisites. Small regions of ${\mathrm{LiNbO}}_{3}$ with ilmenite-like cation-stacking sequence are likely to occur; thus (${\mathrm{Nb}}_{\mathrm{Li}{}^{4\mathrm{up}20.{\mathrm{V}}_{\mathrm{Nb}{}^{5\mathcal{'}})\mathcal{'}}}}$ defects in ${\mathrm{LiNbO}}_{3}$ should be interpreted as Li vacancies within ilmenite-like crystal regions. Li Frenkel disorder is energetically favorable. Finally we study charge\char21{}self-trapping centers, i.e., polarons and bipolarons.

WASP-19b: The Shortest Period Transiting Exoplanet Yet Discovered

Abstract: We report on the discovery of a new extremely short period transiting extrasolar planet, WASP-19b. The planet has mass M pl = 1.15 ± 0.08 MJ , radius R pl = 1.31 ± 0.06 RJ , and orbital period P = 0.7888399 ± 0.0000008 days. Through spectroscopic analysis, we determine the host star to be a slightly super-solar metallicity ([M/H] = 0.1 ± 0.1 dex) G-dwarf with T eff = 5500 ± 100 K. In addition, we detect periodic, sinusoidal flux variations in the light curve which are used to derive a rotation period for the star of P rot = 10.5 ± 0.2 days. The relatively short stellar rotation period suggests that either WASP-19 is somewhat young (~ 600 Myr old) or tidal interactions between the two bodies have caused the planet to spiral inward over its lifetime resulting in the spin-up of the star. Due to the detection of the rotation period, this system has the potential to place strong constraints on the stellar tidal quality factor, Q' s , if a more precise age is determined.

Clinical diagnosis of Achilles tendinopathy with tendinosis.

Abstract: OBJECTIVE: To evaluate sensitivity, specificity, reproducibility, and predictive value of palpation of the painful arc sign and of the Royal London Hospital test in 10 patients with Achilles tendinopathy and in 14 asymptomatic subjects. DESIGN: Test-retest study. SETTING: University teaching hospital. PARTICIPANTS: Ten male athletes on the waiting list for exploration of one of their Achilles tendons for tendinopathy of the main body of the tendon attended a special clinic. Each was invited to bring at least one athlete of the same sex in the same discipline aged within 2 years of themselves with no history and no symptoms of Achilles tendinopathy. A total of 14 controls were thus recruited. MAIN OUTCOME MEASURES: Pain and tenderness following performance of palpation, the painful arc sign, and the Royal London Hospital test. RESULTS: There were no statistically significant differences at the 5% level among the effects of investigator or between morning and afternoon measurements for any of the three measurement methods. There was no evidence of a difference of the three assessment methods (p > 0.05). When the three methods were combined, the overall sensitivity was 0.586 (confidence interval [CI], 0.469-0.741), and the overall specificity was 0.833 (CI, 0.758-0.889). CONCLUSIONS: In patients with tendinopathy of the Achilles tendon with a tender area of intratendinous swelling that moves with the tendon and whose tenderness significantly decreases or disappears when the tendon is put under tension, a clinical diagnosis of tendinopathy can be formulated, with a high positive predictive chance that the tendon will show ultrasonographic and histologic features of tendinopathy.