Diffuse Atomic and Molecular Gas in the Interstellar Medium of M82 toward SN 2014J

We present a comprehensive analysis of interstellar absorption lines seen in moderately-high resolution, high signal-to-noise ratio optical spectra of SN 2014J in M82. Our observations were acquired over the course of six nights, covering the period from ~6 days before to ~30 days after the supernova reached its maximum B-band brightness. We examine complex absorption from Na I, Ca II, K I, Ca I, CH+, CH, and CN, arising primarily from diffuse gas in the interstellar medium (ISM) of M82. We detect Li I absorption over a range in velocity consistent with that exhibited by the strongest Na I and K I components associated with M82; this is the first detection of interstellar Li in a galaxy outside of the Local Group. There are no significant temporal variations in the absorption-line profiles over the 37 days sampled by our observations. The relative abundances of the various interstellar species detected reveal that the ISM of M82 probed by SN 2014J consists of a mixture of diffuse atomic and molecular clouds characterized by a wide range of physical/environmental conditions. Decreasing N(Na I)/N(Ca II) ratios and increasing N(Ca I)/N(K I) ratios with increasing velocity are indicative of reduced depletion in the higher-velocity material. Significant component-to-component scatter in the N(Na I)/N(Ca II) and N(Ca I)/N(Ca II) ratios may be due to variations in the local ionization conditions. An apparent anti-correlation between the N(CH+)/N(CH) and N(Ca I)/N(Ca II) ratios can be understood in terms of an opposite dependence on gas density and radiation field strength, while the overall high CH+ abundance may be indicative of enhanced turbulence in the ISM of M82. The Li abundance also seems to be enhanced in M82, which supports the conclusions of recent gamma-ray emission studies that the cosmic-ray acceleration processes are greatly enhanced in this starburst galaxy.Comment: 32 pages, 6 figures, accepted to ApJ; added table giving single-epoch equivalent widths; improved discussion regarding the lack of temporal variations; improved analysis of the Li I regio

OH+ in Diffuse Molecular Clouds

Near ultraviolet observations of OH+ and OH in diffuse molecular clouds reveal a preference for different environments. The dominant absorption feature in OH+ arises from a main component seen in CH+ (that with the highest CH+/CH column density ratio), while OH follows CN absorption. This distinction provides new constraints on OH chemistry in these clouds. Since CH+ detections favor low-density gas with small fractions of molecular hydrogen, this must be true for OH+ as well, confirming OH+ and H2O+ observations with the Herschel Space Telescope. Our observed correspondence indicates that the cosmic ray ionization rate derived from these measurements pertains to mainly atomic gas. The association of OH absorption with gas rich in CN is attributed to the need for high enough density and molecular fraction before detectable amounts are seen. Thus, while OH+ leads to OH production, chemical arguments suggest that their abundances are controlled by different sets of conditions and that they coexist with different sets of observed species. Of particular note is that non-thermal chemistry appears to play a limited role in the synthesis of OH in diffuse molecular clouds.Comment: 15 pages, 4 figures, to appear in ApJ Letter

XY checkerboard antiferromagnet in external field

Ordering by thermal fluctuations is studied for the classical XY antiferromagnet on a checkerboard lattice in zero and finite magnetic fields by means of analytical and Monte Carlo methods. The model exhibits a variety of novel broken symmetries including states with nematic ordering in zero field and with triatic order parameter at high fields.Comment: 6 page

Temperature-Dependent X-Ray Absorption Spectroscopy of Colossal Magnetoresistive Perovskites

The temperature dependence of the O K-edge pre-edge structure in the x-ray absorption spectra of the perovskites La(1-x)A(x)MnO(3), (A = Ca, Sr; x = 0.3, 0.4) reveals a correlation between the disappearance of the splitting in the pre-edge region and the presence of Jahn-Teller distortions. The different magnitudes of the distortions for different compounds is proposed to explain some dissimilarity in the line shape of the spectra taken above the Curie temperature.Comment: To appear in Phys. Rev. B, 5 pages, 3 figure

Food Challenge: Serving Up 4-H to Non-Traditional Audiences

This article describes a novel approach for introducing 4-H to non-traditional/diverse audiences using 4-H Food Challenge. Set in a low SES and minority-serving rural school, Food Challenge was presented during the school day to all 7th grade students, with almost half voluntarily participating in an after-school club component. Program design supported school-level STEM enrichment and career development priorities. Topics addressed ranged from food handling/safety to nutrition and cost analysis. Conclusions include a summary of student outcomes and recommendations for school and adult partnerships. Implications for reaching non-traditional 4-H audiences through non-competition formats are discussed

Attacking the Yield Plateau: Assessing the Nutrient Status of Kentucky Alfalfa Stands

Soil and tissue analyses indicated that alfalfa yields may be limited in some cases by soil fertility. Soil pH was below the optimal range in more than 40% of the fields sampled. This may result in decreased nitrogen fixation and nutrient availability. Potassium was reported low in approximately one‐quarter of the sampled stands according to tissue analysis. This was not unexpected since hay production removes large quantities of potash. Sulfur and magnesium were reported low in 13 and 23 percent of stands, respectively. More work is needed to better understand if these two 2023 Kentucky Alfalfa and Stored Forage Conference Proceedings Page Number 76 nutrients are truly limiting alfalfa yield in Kentucky

Yearling Beef Cattle Grazing Diverse Summer Annual Swards

Utilizing summer annuals is often regarded as “a breakeven proposition at best” due to high establishment costs. This study investigated using botanical diversity to increase forage yield or animal performance to improve the economic feasibility of grazing summer annual forages in western Kentucky, USA. Sorghum-sudangrass (Sorghum bicolor x S. bicolor spp. drummondii)-based treatments included a monoculture, a three-species mixture (two grasses, one legume), and a 12-species mixture (five grasses, four legumes, two brassicas, and one forb). Angus-cross yearling beef calves (329, 366, and 297 kg in 2017, 2018, and 2019, respectively) grazed summer annuals in 2017-2019 for an average of 40 days each year without supplementation. Pastures were stocked when forage was approximately 1 m tall and calves were removed when forage was 2-2.5 m tall (seedheads present). In all years, forage dry matter yield was not different between treatments (p \u3e 0.85) and both mixtures were dominated by sorghum-sudangrass. In 2017 (p \u3c 0.03) and 2019 (p \u3c 0.03), calves grazing the 12-species mixture had lower average daily gains (ADG) than the monoculture and 3-species mixture, while there was no difference in 2018 (p \u3e 0.3). Average daily gains were suboptimal for stocker calves in all years (0.75, 0.01, 0.54 kg day-1 in 2017, 2018, and 2019). The extremely low ADG in 2018 was likely a result of stocking pastures late in the season when grasses were at physiological maturity. Additional species increased seed cost but did not contribute significantly to forage production and did not result in increased animal production. Unless greater forage yield or livestock gains are attained, planting mixtures may not provide any economic benefit. However, adjusting seeding rates to favor less dominant species may provide a more accurate representation of species diversity manipulation effects on forage and livestock production

Aging and memory properties of topologically frustrated magnets

The model 2d kagome system (H3O)Fe3(SO4)2(OH)6 and the 3d pyrochlore Y2Mo2O7 are two well characterized examples of low-disordered frustrated antiferromagnets which rather then condensing into spin liquid have been found to undergo a freezing transition with spin glass-like properties. We explore more deeply the comparison of their properties with those of spin glasses, by the study of characteristic rejuvenation and memory effects in the non-stationary susceptibility. While the pyrochlore shows clear evidence for these non-trivial effects, implying temperature selective aging, that is characteristic of a wide hierarchical distribution of equilibration processes, the kagome system does n not show clearly these effects. Rather, it seems to evolve towards the same final state independently of temperature.Comment: submitted for the proceedings of the 46th MMM conference (Seattle, 2001