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We propose a set of statistics S q for detecting non-gaussianity in CMBR anisotropy data sets. These statistics are both simple and, according to calculations over a space of linear combinations of three-point functions, nearly optimal at detecting certain types of non-gaussian features. We apply S 3 to the UCSB SP91 experiment and find that the mean of the four frequency channels is by this criterion strongly non-gaussian. Such an observation would be highly unlikely in a gaussian theory with a small coherence angle, such as standard (n = 1, Ω b = .05, h = .5, Λ = 0) inflation. We cannot conclude that the non-gaussianity is cosmological in origin, but if we assume it due instead to foreground contamination or instrumental effects, and remove the points which are clearly responsible for the non-gaussian behavior, the rms of the remaining fluctuations is too small for consistency with standard inflation at high confidence. Further data are clearly needed however, before definitive conclusions may be drawn. We also generalize the ideas behind this statistic to non-gaussian features that might be detected in other experimental schemes.

The oxygen nonstoichiometry in the misfit calcium cobaltite (Ca 2 CoO 3 ) 0.62 (CoO 2 ) has been studied experimentally and by density functional theory (DFT) calculations. The standard oxidation enthalpy ΔH 0 Ox of oxygen deficient (Ca 2 CoO 3 ) 0.62 (CoO 2 ) was measured directly using simultaneous thermogravimetry and differential scanning calorimetry. ΔH 0 Ox was found to be in agreement with the prediction from a previously published defect chemical model based on purely thermogravimetrical analysis. A series of samples with different oxygen vacancy concentration was prepared by annealing in air, followed by rapid quenching. Room-temperature Raman spectroscopy showed a sharp mode at 700 cm −1 decreasing in intensity with increasing vacancy concentration. We discuss this observation as evidence for oxygen vacancies being preferably formed within the central layer of the Ca 2 CoO 3 subsystem. DFT calculations demonstrated that the calculated electronic structure is sensitive to the chosen model of the crystal structure. Still, for all investigated models, the standard formation enthalpy of oxygen vacancies within the Ca 2 CoO 3 moiety was much lower than that for a site within the CoO 2 layer, in agreement with the presented experimental data.

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We investigate the hypothesis that γ-ray-quiet AGN have a larger tendency for jet bending than γ-ray-loud AGN, revisiting the analysis of Tingay, Murphy & Edwards (1998). We perform a statistical analysis using a large sample of 351 radio-loud AGN along with γ-ray identifications from the Fermi Large Area Telescope (LAT). Our results show no statistically significant differences in jet-bending properties between γ-ray-loud and γ-ray-quiet populations, indicating that jet bending is not a significant factor for γ-ray detection in AGN.