Raccoon (Procyon lotor) Activity is Better Predicted by Water Availability than Land Cover in a Moderately Fragmented Landscape

Citation: Heske, E. J., & Ahlers, A. A. (2016). Raccoon (Procyon lotor) Activity is Better Predicted by Water Availability than Land Cover in a Moderately Fragmented Landscape. Northeastern Naturalist, 23(3), 352-363. doi:10.1656/045.023.0302Citation: Heske, E., and Ahlers, A. (2016). Raccoon (Procyon lotor) Activity is Better Predicted by Water Availability than Land Cover in a Moderately Fragmented Landscape. Northeastern Naturalist, 23(3), 352-363. https://doi.org/10.1656/045.023.0302Procyon lotor (Raccoon) is a habitat and dietary generalist that reaches its greatest population densities in heterogeneous, moderately fragmented landscapes. Even within such landscapes, a variety of natural and anthropogenic habitat variables can influence the local activity of Raccoons, and therefore their potential impact as nest predators. We examined Raccoon activity at 34 baited track-stations over 3 summers in forested ravines in the Shawnee National Forest (SNF), IL. We found that the dependability of water at a survey site was the best predictor of Raccoon activity, overshadowing any potential influences of land cover in the surrounding landscape. Landscape-level effects on Raccoon population size and density are likely widespread throughout moderately fragmented regions like the SNF, but variation in local activity can be predicted by the distribution of critical resources (e.g., water, den sites)

Assignment of the crystal structure to the aza-pinacol coupling product by X-ray diffraction and density functional theory modeling

Aza-pinacol coupling of N-benzyl-1-phenylmethanimine using Zn dust affords a mixture of R,S- or R,R-diastereomers in a 1:1 ratio. The R,S-diastereomer is solid with an m.p. of 135 °C, while the R,R-diastereomer is liquid at room temperature. The configuration of stereocenters was determined by combining X-ray powder diffraction and density functional theory (DFT) modeling

Local electronic structure of the peptide bond probed by resonant inelastic soft X-ray scattering.

The local valence orbital structure of solid glycine, diglycine, and triglycine is studied using soft X-ray emission spectroscopy (XES), resonant inelastic soft X-ray scattering (RIXS) maps, and spectra calculations based on density-functional theory. Using a building block approach, the contributions of the different functional groups of the peptides are separated. Cuts through the RIXS maps furthermore allow monitoring selective excitations of the amino and peptide functional units, leading to a modification of the currently established assignment of spectral contributions. The results thus paint a new-and-improved picture of the peptide bond, enhance the understanding of larger molecules with peptide bonds, and simplify the investigation of such molecules in aqueous environment

IRAS04496-6958: A luminous carbon star with silicate dust in the Large Magellanic Cloud

We describe ISO observations of the obscured Asymptotic Giant Branch (AGB) star IRAS04496-6958 in the Large Magellanic Cloud (LMC). This star has been classified as a carbon star. Our new ISOCAM CVF spectra show that it is the first carbon star with silicate dust known outside of the Milky Way. The existence of this object, and the fact that it is one of the highest luminosity AGB stars in the LMC, provide important information for theoretical models of AGB evolution and understanding the origin of silicate carbon stars.Comment: 4 pages, 3 figures, accepted for publication in A&A Letter

Nutritional Quality of Leaves and Unripe Fruit Consumed as Famine Foods by the Flying Foxes of Samoa

Many tropical herbivores alter their diets throughout the year in response to different levels of food availability. Fruit bats, including Pteropus samoensis Peale and Pteropus tonganus Quoy & Gaimard, are phytophagous species that may increase their consumption of foods such as unripe fruit and leaves in periods of low fruit diversity and volume. These periods include the tropical dry season or following the frequent hurricanes that batter the Samoan Archipelago. We examined the nutritional composition of leaves and immature fruits and compared the levels of organic and mineral nutrients with those of ripe fruit. We used principal components analysis (PCA) to examine patterns of variation in nutrient components of leaves, unripe fruit, and ripe fruit, as well as to compare the mean levels of nutrients. Overall, unripe fruit provided levels of nutrients comparable with those of ripe fruit of the same species for many organic and mineral components. Unripe fruit were only half as rich in iron as ripe fruit, but unripe fruit had high levels of calcium compared with ripe fruit of the same species. Leaves are often cited as a rich source of protein for fruit bats, and our results were consistent with this suggestion. Leaves were also found to be rich in zinc, manganese, and calcium. Therefore, flying foxes and other herbivores probably do not avoid unripe fruits and leaves because of their low nutrient levels. It may be that these famine foods are not normally consumed because of the presence of secondary compounds, low concentrations of palatable sugars, or a distasteful and hard pericarp on unripe fruits

ISO observations of obscured Asymptotic Giant Branch stars in the Large Magellanic Cloud

We present ISO photometric and spectroscopic observations of a sample of 57 bright Asymptotic Giant Branch stars and red supergiants in the Large Magellanic Cloud, selected on the basis of IRAS colours indicative of high mass-loss rates. PHOT-P and PHOT-C photometry at 12, 25 and 60 $\mu$m and CAM photometry at 12 $\mu$m are used in combination with quasi-simultaneous ground-based near-IR photometry to construct colour-colour diagrams for all stars in our sample. PHOT-S and CAM-CVF spectra in the 3 to 14 $\mu$m region are presented for 23 stars. From the colour-colour diagrams and the spectra, we establish the chemical types of the dust around 49 stars in this sample. Many stars have carbon-rich dust. The most luminous carbon star in the Magellanic Clouds has also a (minor) oxygen-rich component. OH/IR stars have silicate absorption with emission wings. The unique dataset presented here allows a detailed study of a representative sample of thermal-pulsing AGB stars with well-determined luminosities.Comment: 19 pages, 10 figures. Accepted for publication in Astronomy and Astrophysics Main Journa

Summer Precipitation Predicts Spatial Distributions of Semiaquatic Mammals

Citation: Ahlers, A. A., Cotner, L. A., Wolff, P. J., Mitchell, M. A., Heske, E. J., & Schooley, R. L. (2015). Summer Precipitation Predicts Spatial Distributions of Semiaquatic Mammals. Plos One, 10(8), 14. doi:10.1371/journal.pone.0135036Climate change is predicted to increase the frequency of droughts and intensity of seasonal precipitation in many regions. Semiaquatic mammals should be vulnerable to this increased variability in precipitation, especially in human-modified landscapes where dispersal to suitable habitat or temporary refugia may be limited. Using six years of presence-absence data (2007-2012) spanning years of record-breaking drought and flood conditions, we evaluated regional occupancy dynamics of American mink (Neovison vison) and muskrats (Ondatra zibethicus) in a highly altered agroecosystem in Illinois, USA. We used noninvasive sign surveys and a multiseason occupancy modeling approach to estimate annual occupancy rates for both species and related these rates to summer precipitation. We also tracked radiomarked individuals to assess mortality risk for both species when moving in terrestrial areas. Annual model-averaged estimates of occupancy for mink and muskrat were correlated positively to summer precipitation. Mink and muskrats were widespread during a year (2008) with above-average precipitation. However, estimates of site occupancy declined substantially for mink (0.56) and especially muskrats (0.09) during the severe drought of 2012. Mink are generalist predators that probably use terrestrial habitat during droughts. However, mink had substantially greater risk of mortality away from streams. In comparison, muskrats are more restricted to aquatic habitats and likely suffered high mortality during the drought. Our patterns are striking, but a more mechanistic understanding is needed of how semiaquatic species in human-modified ecosystems will respond ecologically in situ to extreme weather events predicted by climate-change models

Photocatalytic water splitting reaction catalyzed by ion-exchanged salts of potassium poly(heptazine imide) 2D materials

Potassium poly (heptazine imide) (K-PHI), a crystalline two-dimensional carbon–nitride material, is an active photocatalyst for water splitting. The potassium ions in K-PHI can be exchanged with other ions to change the properties of the material and eventually to design the catalysts. We report here the electronic structures of several ion-exchanged salts of K-PHI (K, H, Au, Ru, and Mg) and their feasibility as water splitting photocatalysts, which were determined by density functional theory (DFT) calculations. The DFT results are complemented by experiments where the performances in the photocatalytic hydrogen evolution reaction (HER) were recorded. We show that due to its narrow band gap, Ru-PHI is not a suitable photocatalyst. The water oxidation potentials are straddled between the band edge potentials of H-PHI, Au-PHI, and Mg-PHI; thus, these are active photocatalysts for both the oxygen and hydrogen evolution reactions, whereas K-PHI is active only for the HER. The experimental data show that these are active HER photocatalysts, in agreement with the DFT results. Furthermore, Mg-PHI has shown remarkable performance in the HER, with a rate of 539 μmol/(h·g) and a quantum efficiency of 7.14% at 410 nm light irradiation, which could be due to activation of the water molecule upon adsorption, as predicted by our DFT calculations

A quasi-time-dependent radiative transfer model of OH104.9+2.4

We investigate the pulsation-phase dependent properties of the circumstellar dust shell (CDS) of the OH/IR star OH104.9+2.4 based on radiative transfer modeling (RTM) using the code DUSTY. Our previous study concerning simultaneous modeling of the spectral energy distribution (SED) and near-infrared (NIR) visibilities (Riechers et al. 2004) has now been extended by means of a more detailed analysis of the pulsation-phase dependence of the model parameters of OH104.9+2.4. In order to investigate the temporal variation in the spatial structure of the CDS, additional NIR speckle interferometric observations in the K' band were carried out with the 6 m telescope of the Special Astrophysical Observatory (SAO). At a wavelength of 2.12 micron the diffraction-limited resolution of 74 mas was attained. Several key parameters of our previous best-fitting model had to be adjusted in order to be consistent with the newly extended amount of observational data. It was found that a simple rescaling of the bolometric flux F_bol is not sufficient to take the variability of the source into account, as the change in optical depth over a full pulsation cycle is rather high. On the other hand, the impact of a change in effective temperature T_eff on SED and visibility is rather small. However, observations, as well as models for other AGB stars, show the necessity of including a variation of T_eff with pulsation phase in the radiative transfer models. Therefore, our new best-fitting model accounts for these changes.Comment: 7 pages, including 5 postscript figures and 3 tables. Published in Astronomy and Astrophysics. (v1: accepted version; v2: published version, minor grammatical changes

CO in OH/IR stars close to the Galactic centre

Aims: A pilot project has been carried out to measure circumstellar CO emission from three OH/IR stars close to the Galactic centre. The intention was to find out whether it would be possible to conduct a large-scale survey for mass-loss rates using, for example, the Atacama Large Millimeter Array (ALMA). Such a survey would increase our understanding of the evolution of the Galactic bulge. Methods: Two millimetre-wave instruments were used: the Nobeyama Millimeter Array at 115 GHz and the Submillimeter Array at 230 GHz. An interferometer is necessary as a `spatial filter' in this region of space because of the confusion with interstellar CO emission. Results: Towards two of the stars, CO emission was detected with positions and radial velocities coinciding within the statistical errors with the corresponding data of the associated OH sources. However, for one of the stars the line profile is not what one expects for an unresolved expanding circumstellar envelope. We believe that this CO envelope is partially resolved and that this star therefore is a foreground star not belonging to the bulge. Conclusions: The results of the observations have shown that it is possible to detect line profiles of circumstellar CO from late-type stars both within and in the direction of the Galactic bulge. ALMA will be able to detect CO emission in short integrations with sensitivity sufficient to estimate mass-loss rates from a large number of such stars.Comment: 5 pages, 3 figure