Manufacturing and test procedures for Aerobee 350 burst diaphragms

Manufacturing and test procedures for fuel and oxidizer burst diaphragms for Aerobee 350 propellant start valve

Effect of high frequency ultrasounds on lycopene and total phenolic concentration, antioxidant properties and α-glucosidase inhibitory activity of tomato juice

Tomato juice was subjected to high frequency ultrasounds(378 and 583 kHz)at increasing energy densities (up to 250 MJ/m3). Results relevant to the treatments at high frequency providing an energy density of 250 MJ/m3 were compared with those obtained at 24 kHz delivering the same energy density. Lycopene and total phenolic concentration, as well as the α-glucosidase inhibitory activityof tomato juice, were not affected by ultrasound regardless the frequency and energy density. However, the antioxidant properties were negatively affected by high frequency ultrasounds

Explosive Nucleosynthesis from GRB and Hypernova Progenitors: Direct Collapse versus Fallback

The collapsar engine behind long-duration gamma-ray bursts extracts the energy released from the rapid accretion of a collapsing star onto a stellar-massed black hole. In a collapsing star, this black hole can form in two ways: the direct collapse of the stellar core into a black hole and the delayed collapse of a black hole caused by fallback in a weak supernova explosion. In the case of a delayed-collapse black hole, the strong collapsar-driven explosion overtakes the weak supernova explosion before shock breakout, and it is very difficult to distinguish this black hole formation scenario from the direct collapse scenario. However, the delayed-collapse mechanism, with its double explosion, produces explosive nucleosynthetic yields that are very different from the direct collapse scenario. We present 1-dimensional studies of the nucleosynthetic yields from both black hole formation scenarios, deriving differences and trends in their nucleosynthetic yields.Comment: 47 pages, submitted to Ap

Light Curve Calculations of Supernovae from Fallback Gamma-Ray Bursts

The currently-favored model for long-duration gamma-ray bursts (GRBs) invokes explosions from the collapse of a massive star down to a black hole: either directly or through fallback. Those GRBs forming via fallback will produce much less radioactive nickel, and hence it has been argued (without any real calculation) that these systems produce dim supernovae. These fallback black-hole GRBs have been recently been argued as possible progenitors of a newly discovered set of GRBs lacking any associated supernovae. Here we present the first ever radiation-hydrodynamics calculations of the light-curves produced in the hypernova explosion by a delayed-fallback gamma-ray burst. We find that the bolometric light-curve is dominated by shock-deposited energy, not the decay of radioactive elements. As such, observations of such bursts actually probe the density in the progenitor wind more than it does the production of radioactive nickel.Comment: 11 pages (including 3 figures), submitted to ApJ, comments welcom

Creating meaning : an ethnographic study of pre-schoolers, literary response and play.

The purpose of this study was to first identify and describe the literary response behaviors exhibited by pre-schoolers in a literature rich setting. Next, the study examined these response behaviors as indicative of the characteristics of theorist Michael Benton\u27s \u27secondary world\u27 of literary response (1983) and of psychologist D. W. Winnicott\u27s \u27third area\u27 of play (1971). Finally, the study considered the possibilities inherent in these secondary worlds for the creation and exploration of meaning on the part of pre-schoolers. This study utilized ethnographic methods of participant observation, in-depth interviewing, informal conversations, field notes and videotaping. Validity was established and checked through trianglization using the adults in the setting and two outside readers. The findings of this study are culture specific. This ethnographic study offers ways of thinking about, considering and discussing how young children use their experiences of interacting with books and responding to books to create meaning for their lives. Response behaviors were identified, described and organized into three general categories: (1) Individual/dyadic response behaviors involving one child/book(s), two children/book(s) and a child/adult/book(s), (2) Communal response behaviors involving several children/book(s) or several children/adult/book(s), and (3) Guided/directed response behaviors which always involved several children, an adult and book(s), and, in addition, had a specific goal or objective. Response behaviors in each of these categories covered a broad range of activities and formed an integral part of the living and learning experiences of the pre-schoolers in this day care setting. Both physically and humanly this setting was an organized and supportive environment which expected and encouraged interactions with and response to books. Within this setting, reliable and trustworthy relationships were formed which both allowed and encouraged the creation of secondary worlds. Such secondary worlds were intermediate between inner psychic reality and outer shared reality, were dependent upon individual contributions and provided place and opportunity for the creation of meaning. The pre-schoolers used these secondary worlds to explore self identity, emotions, competency development and to expand and integrate their ways of being in the world

A line-binned treatment of opacities for the spectra and light curves from neutron star mergers

The electromagnetic observations of GW170817 were able to dramatically increase our understanding of neutron star mergers beyond what we learned from gravitational waves alone. These observations provided insight on all aspects of the merger from the nature of the gamma-ray burst to the characteristics of the ejected material. The ejecta of neutron star mergers are expected to produce such electromagnetic transients, called kilonovae or macronovae. Characteristics of the ejecta include large velocity gradients, relative to supernovae, and the presence of heavy $r$-process elements, which pose significant challenges to the accurate calculation of radiative opacities and radiation transport. For example, these opacities include a dense forest of bound-bound features arising from near-neutral lanthanide and actinide elements. Here we investigate the use of fine-structure, line-binned opacities that preserve the integral of the opacity over frequency. Advantages of this area-preserving approach over the traditional expansion-opacity formalism include the ability to pre-calculate opacity tables that are independent of the type of hydrodynamic expansion and that eliminate the computational expense of calculating opacities within radiation-transport simulations. Tabular opacities are generated for all 14 lanthanides as well as a representative actinide element, uranium. We demonstrate that spectral simulations produced with the line-binned opacities agree well with results produced with the more accurate continuous Monte Carlo Sobolev approach, as well as with the commonly used expansion-opacity formalism. Additional investigations illustrate the convergence of opacity with respect to the number of included lines, and elucidate sensitivities to different atomic physics approximations, such as fully and semi-relativistic approaches.Comment: 27 pages, 22 figures. arXiv admin note: text overlap with arXiv:1702.0299