A single-board preprocessor and pulse generator

The Aeronomy Lab. of NOAA has designed and built a single board, programmable radar controller for use with VHF ST (stratosphere troposphere) radars. The controller consists of a coherent integrator preprocessor and a radar pulse generator, both of which are described, as well as interfaces to an antenna beam switch and a receiver bandwidth switch. The controller occupies a single slot in a Data General Nova of Eclipse computer. The integrator and pulse generator take advantage of high density, dual port FIFO chips such as the 512 x 9 Mostek MK 4501. These FIFOs have separate input and output ports and independent read and write cycles with cycle times of less than 200 ns, making them very fast and easy to interface. A simple block diagram of the coherent integrator is shown. The integrator is designed to handle inputs from one receiver (2 channels) with 1 sec sample spacing. The pulse generator is based on controllers designed by R. F. Woodman for the Arecibo and SOUSY radars us a recirculating memory scheme

Effects of dark matter annihilation on the first stars

We study the evolution of the first stars in the universe (Population III) from the early pre-Main Sequence until the end of helium burning in the presence of WIMP dark matter annihilation inside the stellar structure. The two different mechanisms that can provide this energy source are the contemporary contraction of baryons and dark matter, and the capture of WIMPs by scattering off the gas with subsequent accumulation inside the star. We find that the first mechanism can generate an equilibrium phase, previously known as a "dark star", which is transient and present in the very early stages of pre-MS evolution. The mechanism of scattering and capture acts later, and can support the star virtually forever, depending on environmental characteristic of the dark matter halo and on the specific WIMP model.Comment: Proceedings of the IAU Symposium 255, "Low-Metallicity Star Formation: From the First Stars to Dwarf Galaxies"; L.K. Hunt, S. Madden and R. Schneider ed

Large inverse tunneling magnetoresistance in Co2_2Cr0.6_{0.6}Fe0.4_{0.4}Al/MgO/CoFe magnetic tunnel junctions

Magnetic tunnel junctions with the layer sequence Co$_2$Cr$_{0.6}$Fe$_{0.4}$Al/MgO/CoFe were fabricated by magnetron sputtering at room temperature (RT). The samples exhibit a large inverse tunneling magnetoresistance (TMR) effect of up to -66% at RT. The largest value of -84% at 20 K reflects a rather weak influence of temperature. The dependence on the voltage drop shows an unusual behavior with two almost symmetric peaks at $\pm600$ mV with large inverse TMR ratios and small positive values around zero bias

Citizenship Education for the 21st Century Leveraging the K-6 Developmental Time Window

An online survey of K to 12 teachers, graduate students, and college instructors, ages 18 to 60+, from Western and Non-Western countries, was conducted to measure opinions about and experiences with Citizenship Education (CE). CE is fundamentally defined in this paper as the teaching of individual and collective rights and responsibilities in academic and social contexts in K to 12 schooling (~ 4 to 18 years of age). The purpose of this preliminary research was to develop several core conclusions about CE using literature support and develop a number of basic survey expectations based on some of those conclusions and the experiences of the author. Literature-supported core conclusions included that CE: a) has the power to equip students with the knowledge of their individual and group rights and responsibilities regarding both academic and inter-personal or social pursuits; b) has elements that can be leveraged in many academic and social learning experiences in elementary and secondary schooling; c) is important to citizens as a general rule, but often takes an informal form, which tends to lead to a lack of awareness regarding its value; d) when viewed as ‘engaged learning’, may lack adequate funding, especially in K to 6 schooling; e) is qualitatively dependent upon the degree to which especially K to 6 education is based in facts, critical thinking skills, hard work, respect, and reflection; f) is most effective when started in the K to 6 school years and continued through secondary schooling; and g) in order to be effective internationally needs the world’s educational systems to focus support for foundational academic and social learning and development early in the education lives of children, where it is the most efficient and effective. A conclusion that ties these together is that, while it is ultimately the responsibility of young adults in any society to take over the mantel of power, it is the precursory responsibility of parental generations to prepare young people for this task through continuous lessons, in every possible context, about how to think and act in ways that serve themselves and their communities well. Qualitative analysis of survey results from 28 respondents from 10 countries and 6 age groups indicated a pattern of responses that supported study expectations, including that: a) respondents tended to have CE definitions that centered on creating good and responsible citizens; b) a significant number of respondents (about 1/3) reported experiencing informal CE; c) most respondents reported experiencing some form of CE in elementary or secondary schooling; and d) members of all age groups surveyed felt that CE is important. Given the preliminary nature of the survey investigation, age- and country- based consistency was tested rather than response differences correlated to age or country. Recommendations include doing a more age and internationally extensive survey to check for said patterns and using a better structured survey to check for more precise opinions, especially regarding how CE might have affected respondents’ lives overall and how CE, or a lack there of, may be affecting the adult lives and childhoods of ‘millennial’ and 21st century generations. Keywords: Citizenship education, Cognitive and social development, Self-determination, Social brain, Return on investment, Sensitivity to learning, Global issu