13 research outputs found
Resonant Particle Heating of an Electron Plasma by Oscillating Sheaths,” Phys
The first unambiguous measurements of a bounce-resonance effect in a non-neutral plasma are presented. Two striking signatures are observed when a magnetized electron column is heated by oscillating an end sheath. First, the heating rate increases by a factor of 10 4 as the oscillation frequency is increased by a factor of 10 near the thermal electron bounce frequency. Second, the heating is enhanced when the sheaths at both ends are oscillated out of phase, but is suppressed when they are in phase. The measured rates are in quantitative agreement with a resonant particle heating theory. [S0031-9007(98
Amount of Time to Eat Lunch Is Associated with Children’s Selection and Consumption of School Meal Entrée, Fruits, Vegetables, and Milk
Background
There are currently no national standards for school lunch period length and little is known about the association between the amount of time students have to eat and school food selection and consumption.
Objective Our aim was to examine plate-waste measurements from students in the control arm of the Modifying Eating and Lifestyles at School study (2011 to 2012 school year) to determine the association between amount of time to eat and school meal selection and consumption.
Design We used a prospective study design using up to six repeated measures among students during the school year.
Participants/setting One thousand and one students in grades 3 to 8 attending six participating elementary and middle schools in an urban, low-income school district where lunch period lengths varied from 20 to 30 minutes were included.
Main outcome measures School food selection and consumption were collected using plate-waste methodology.
Statistical analyses performed Logistic regression and mixed-model analysis of variance was used to examine food selection and consumption.
Results
Compared with meal-component selection when students had at least 25 minutes to eat, students were significantly less likely to select a fruit (44% vs 57%; PPPP
Conclusions During the school year, a substantial number of students had insufficient time to eat, which was associated with significantly decreased entrée, milk, and vegetable consumption compared with students who had more time to eat. School policies that encourage lunches with at least 25 minutes of seated time might reduce food waste and improve dietary intake
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Application of Archimedes Filter for Reduction of Hanford HLW
Archimedes Technology Group, Inc., is developing a plasma mass separator called the Archimedes Filter that separates waste oxide mixtures ion by ion into two mass groups: light and heavy. For the first time, it is feasible to separate large amounts of material atom by atom in a single pass device. Although vacuum ion based electromagnetic separations have been around for many decades, they have traditionally depended on ion beam manipulation. Neutral plasma devices, on the other hand, are much easier, less costly, and permit several orders of magnitude greater throughput. The Filter has many potential applications in areas where separation of species is otherwise difficult or expensive. In particular, radioactive waste sludges at Hanford have been a particularly difficult issue for pretreatment and immobilization. Over 75% of Hanford HLW oxide mass (excluding water, carbon, and nitrogen) has mass less than 59 g/mol. On the other hand, 99.9% of radionuclide activity has mass greater than 89 g/mol. Therefore, Filter mass separation tuned to this cutoff would have a dramatic effect on the amount of IHLW produced--in fact IHLW would be reduced by a factor of at least four. The Archimedes Filter is a brand new tool for the separations specialist's toolbox. In this paper, we show results that describe the extent to which the Filter separates ionized material. Such results provide estimates for the potential advantages of Filter tunability, both in cutoff mass (electric and magnetic fields) and in degree of ionization (plasma power). Archimedes is now engaged in design and fabrication of its Demonstration Filter separator and intends on performing a full-scale treatment of Hanford high-level waste surrogates. The status of the Demo project will be described