Spontaneous Polarisation Build up in a Room Temperature Polariton Laser

We observe the build up of strong (~50%) spontaneous vector polarisation in emission from a GaN-based polariton laser excited by short optical pulses at room temperature. The Stokes vector of emitted light changes its orientation randomly from one excitation pulse to another, so that the time-integrated polarisation remains zero. This behaviour is completely different to any previous laser. We interpret this observation in terms of the spontaneous symmetry breaking in a Bose-Einstein condensate of exciton-polaritons

Methane and Nitrogen Abundances On Pluto and Eris

We present spectra of Eris from the MMT 6.5 meter telescope and Red Channel Spectrograph (5700-9800 angstroms; 5 angstroms per pix) on Mt. Hopkins, AZ, and of Pluto from the Steward Observatory 2.3 meter telescope and Boller and Chivens spectrograph (7100-9400 angstroms; 2 angstroms per pix) on Kitt Peak, AZ. In addition, we present laboratory transmission spectra of methane-nitrogen and methane-argon ice mixtures. By anchoring our analysis in methane and nitrogen solubilities in one another as expressed in the phase diagram of Prokhvatilov and Yantsevich (1983), and comparing methane bands in our Eris and Pluto spectra and methane bands in our laboratory spectra of methane and nitrogen ice mixtures, we find Eris' bulk methane and nitrogen abundances are about 10% and about 90%, and Pluto's bulk methane and nitrogen abundances are about 3% and about 97%. Such abundances for Pluto are consistent with values reported in the literature. It appears that the bulk volatile composition of Eris is similar to the bulk volatile composition of Pluto. Both objects appear to be dominated by nitrogen ice. Our analysis also suggests, unlike previous work reported in the literature, that the methane and nitrogen stoichiometry is constant with depth into the surface of Eris. Finally, we point out that our Eris spectrum is also consistent with a laboratory ice mixture consisting of 40% methane and 60% argon. Although we cannot rule out an argon rich surface, it seems more likely that nitrogen is the dominant species on Eris because the nitrogen ice 2.15 micron band is seen in spectra of Pluto and Triton.Comment: The manuscript has 44 pages, 15 figures, and four tables. It will appear in the Astrophysical Journa

Temporal change in maternal dietary intake during pregnancy and lactation between and within 2 pregnancy cohorts assembled in the United Kingdom

Background: The association between maternal and infant dietary exposures and risk of allergic disease development is an area of considerable scientific uncertainty. Objective: This study aims to compare dietary habits during pregnancy and lactation in two pre-birth cohorts from the same location approximately 10 years apart, a timeframe characterised by changes in government dietary advice. Methods: The FAIR cohort is an unselected birth cohort born between 2001-2002. The 3rd generation cohort was born between 2010-2018. Both cohorts were established on the Isle of Wight (UK) to investigate prevalence of allergic diseases. Nutrition and allergy data was collected prospectively from recruitment and throughout the infant’s early life. Here we present dietary data collected in the third trimester of pregnancy and at three months of age. Differences between cohorts were tested using t-tests, Wilcoxon rank sum tests, chi-squared and Fisher’s exact tests. Results: Data was available for 1331 participants (969 FAIR and 362 3rd generation). The proportion of mothers that reported excluding peanuts during pregnancy was significantly lower for the 3rd generation compared to the FAIR cohort (16.0% vs. 55.6%, p < 0.01). Cohort membership, primiparity, and maternal education were significantly associated with excluding peanuts during pregnancy (p < 0.01). The proportion of mothers who reported excluding any foods during breastfeeding was significantly lower for the 3rd generation compared to the FAIR cohort (22.8% vs. 43.4%, p < 0.01). Conclusion: Maternal exclusion of peanut during pregnancy was lower for mothers giving birth between 2012-2018, compared to mothers giving birth between 2001-2002

Optical spectroscopy of the large Kuiper Belt objects 136472 (2005 FY9) and 136108 (2003 EL61).

We present high signal precision optical reflectance spectra of the large Kuiper Belt objects 2005 FY9 and 2003 EL61. The spectrum of 2005 FY9 exhibits strong CH4 ice bands. A comparison between the spectrum and a Hapke model indicates that the CH4 bands are shifted 3.25 ± 2.25 Å relative to pure CH4 ice, suggesting the presence of another ice component on the surface of 2005 FY9, possibly N2 ice, CO ice, or Ar. The spectrum of 2003 EL61 is remarkably featureless. There is a hint of an O2 ice band at 5773 Å; however, this feature needs to be confirmed by future spectroscopic observations of 2003 EL61 with a higher continuum signal precision sufficient to detect a second, weaker O2 ice band at 6275 Å. [on SciFinder(R)