How Well Do We Know the Beta-Decay of 16N and Oxygen Formation in Helium Burning

We review the status of the 12C(a,g)16O reaction rate, of importance for stellar processes in a progenitor star prior to a super-nova collapse. Several attempts to constrain the p-wave S-factor of the 12C(a,g)16O reaction at Helium burning temperatures (200 MK) using the beta-delayed alpha-particle emission of 16N have been made, and it is claimed that this S-factor is known, as quoted by the TRIUMF collaboration. In contrast reanalyses (by G.M. hale) of all thus far available data (including the 16N data) does not rule out a small S-factor solution. Furthermore, we improved our previous Yale-UConn study of the beta- delayed alpha-particle emission of \n16 by improving our statistical sample (by more than a factor of 5), improving the energy resolution of the experiment (by 20%), and in understanding our line shape, deduced from measured quantities. Our newly measured spectrum of the beta-delayed alpha-particle emission of 16N is not consistent with the TRIUMF('94) data, but is consistent with the Seattle('95) data, as well as the earlier (unaltered !) data of Mainz('71). The implication of this discrepancies for the extracted astrophysical p-wave s-factor is briefly discussed.Comment: 6 pages, 4 figures, Invited Talk, Physics With Radioactive Beams, Puri, India, Jan. 12-17, 1998, Work Supported by USDOE Grant No. DE-FG02-94ER4087

Managed Bumblebees Outperform Honeybees in Increasing Peach Fruit Set in China: Different Limiting Processes with Different Pollinators

© 2015 Zhang et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. http://creativecommons.org/licenses/by/4.0/ The file attached is the published version of the article

Postcranial disparity of galeaspids and the evolution of swimming speeds in stem-gnathostomes

Galeaspids are extinct jawless relatives of living jawed vertebrates whose contribution to understanding the evolutionary assembly of the gnathostome bodyplan has been limited by absence of postcranial remains. Here, we describe Foxaspis novemura gen. et sp. nov., based on complete articulated remains from a newly discovered Konservat-Lagerst¨atte in the Early Devonian (Pragian,∼410 Ma) of Guangxi, South China. F. novemura had a broad, circular dorso-ventrally compressed headshield, slender trunk and strongly asymmetrical hypochordal tail fin comprised of nine ray-like scale-covered digitations.This tail morphology contrasts with the symmetrical hypochordal tail fin of Tujiaaspis vividus, evidencing disparity in galeaspid postcranial anatomy. Analysis of swimming speed reveals galeaspids as moderately fast swimmers, capable of achieving greater cruising swimming speeds than their more derived jawless and jawed relatives. Our analyses reject the hypothesis of a driven trend towards increasingly active food acquisition which has been invoked to characterize early vertebrate evolution

Growth diagram of La0.7Sr0.3MnO3 thin films using pulsed laser deposition

An experimental study was conducted on controlling the growth mode of La0.7Sr0.3MnO3 thin films on SrTiO3 substrates using pulsed laser deposition (PLD) by tuning growth temperature, pressure and laser fluence. Different thin film morphology, crystallinity and stoichiometry have been observed depending on growth parameters. To understand the microscopic origin, the adatom nucleation, step advance processes and their relationship to film growth were theoretically analyzed and a growth diagram was constructed. Three boundaries between highly and poorly crystallized growth, 2D and 3D growth, stoichiometric and non-stoichiometric growth were identified in the growth diagram. A good fit of our experimental observation with the growth diagram was found. This case study demonstrates that a more comprehensive understanding of the growth mode in PLD is possible