PAHs and star formation in the HII regions of nearby galaxies M83 and M33

We present mid-infrared (MIR) spectra of HII regions within star-forming galaxies M83 and M33. Their emission features are compared with Galactic and extragalactic HII regions, HII-type galaxies, starburst galaxies, and Seyfert/LINER type galaxies. Our main results are as follows: (i) the M33 and M83 HII regions lie in between Seyfert/LINER galaxies and HII-type galaxies in the 7.7/11.3 - 6.2/11.3 plane, while the different sub-samples exhibiting different 7.7/6.2 ratios; (ii) Using the NASA Ames PAH IR Spectroscopic database, we demonstrate that the 6.2/7.7 ratio does not effectively track PAH size, but the 11.3/3.3 PAH ratio does; (iii) variations on the 17 $\mu$m PAH band depends on object type; however, there is no dependence on metallicity for both extragalactic HII regions and galaxies; (iv) the PAH/VSG intensity ratio decreases with the hardness of the radiation field and galactocentric radius (Rg), yet the ionization alone cannot account for the variation seen in all of our sources; (v) the relative strength of PAH features does not change significantly with increasing radiation hardness, as measured through the [NeIII]/[NeII] ratio and the ionization index; (vi) We present PAH SFR calibrations based on the tight correlation between the 6.2, 7.7, and 11.3 $\mu$m PAH luminosities with the 24 $\mu$m luminosity and the combination of the 24 $\mu$m and H$\alpha$ luminosity; (vii) Based on the total luminosity from PAH and FIR emission, we argue that extragalactic HII regions are more suitable templates in modeling and interpreting the large scale properties of galaxies compared to Galactic HII regions.Comment: 26 pages, 24 figures, 6 tables. Accepted for publication in MNRA

The Predictive Nature of Individual Differences in Early Associative Learning and Emerging Social Behavior

Across the first year of life, infants achieve remarkable success in their ability to interact in the social world. The hierarchical nature of circuit and skill development predicts that the emergence of social behaviors may depend upon an infant's early abilities to detect contingencies, particularly socially-relevant associations. Here, we examined whether individual differences in the rate of associative learning at one month of age is an enduring predictor of social, imitative, and discriminative behaviors measured across the human infant's first year. One-month learning rate was predictive of social behaviors at 5, 9, and 12 months of age as well as face-evoked discriminative neural activity at 9 months of age. Learning was not related to general cognitive abilities. These results underscore the importance of early contingency learning and suggest the presence of a basic mechanism underlying the ontogeny of social behaviors

Residual Stress Measurements in Inconel Alloy 600 Tubing Using an Advanced X-ray Instrument and Cr K_β Radiation

Residual stresses in an inconel alloy 600 U-bend tube, used in heat exchangers in nuclear reactors, were studied using an advanced x-ray instrument developed at The Pennsylvania State University. The work funded by the Electric Power Research Institute (EPRI) mapped both the axial and circumferential (hoop) stresses on the outside surface of the tube. The residual stresses, inherent in the fabrication of the U-bend tubes, are a major contributor to stress corrosion cracking.</jats:p