Dust in Supernovae and Supernova Remnants I : Formation Scenarios

Supernovae are considered as prime sources of dust in space. Observations of local supernovae over the past couple of decades have detected the presence of dust in supernova ejecta. The reddening of the high redshift quasars also indicate the presence of large masses of dust in early galaxies. Considering the top heavy IMF in the early galaxies, supernovae are assumed to be the major contributor to these large amounts of dust. However, the composition and morphology of dust grains formed in a supernova ejecta is yet to be understood with clarity. Moreover, the dust masses inferred from observations in mid-infrared and submillimeter wavelength regimes differ by two orders of magnitude or more. Therefore, the mechanism responsible for the synthesis of molecules and dust in such environments plays a crucial role in studying the evolution of cosmic dust in galaxies. This review summarises our current knowledge of dust formation in supernova ejecta and tries to quantify the role of supernovae as dust producers in a galaxy.Peer reviewe

Short communication: Cystic fibrosis “factor(s)”: Present also in sera of shwachman’s pancreatic insufficiency

Using an in vivo closed-loop technique in rat jejunum, we have confirmed previous in vitro studies that cystic fibrosis (CF) serum inhibits water, sodium, and glucose absorption and transmural potential difference. CF heterozygote serum or sera from children with diarrhoeal disorders not associated with exocrine pancreatic insufficiency had no effect on transport. Sera from patients with Shwachman’s syndrome and exocrine pancreatic insufficiency had identical effects to CF serum. These results challenge the specificity of the CF “factor.”. Speculation: PANCREATIC-RELATED FACTORS The pancreas may modulate small intestinal absorption of water, electrolytes, and glucose via an humoral pathway. In exocrine pancreatic insufficiency, there could.be a deficiency of a normal serum factor which stimulates absorption or, alternatively, a factor which inhibits absorption could be present. © 1981 International Pediatric Research Foundation, Inc

First gut contents in a Cretaceous sea turtle

Modern sea turtles utilize a variety of feeding strategies ranging from herbivory to omnivory. In contrast, the diets of fossil sea turtles are poorly known. This study reports the first direct evidence: inoceramid bivalve shell pieces (encased in phosphatic material) preserved within the body cavities of several small protostegid turtles (cf. Notochelone) from the Lower Cretaceous of Australia. The shell fragments are densely packed and approximately 5–20 mm across. Identical shell accumulations have been found within coprolite masses from the same deposits; these are of a correct size to have originated from Notochelone, and indicate that benthic molluscs were regular food items. The thin, flexible inoceramid shells (composed of organic material integrated into a prismatic calcite framework) appear to have been bitten into segments and ingested, presumably in conjunction with visceral/mantle tissues and encrusting organisms. Although protostegids have been elsewhere interpreted as potential molluscivores, their primitive limb morphology is thought to have limited them to surface feeding. However, the evidence here that at least some forms were able to utilize benthic invertebrate prey indicates that, like modern sea turtles, protostegids probably exhibited a much broader range of feeding habits