Evaluation of a pulsed quasi-steady MPD thruster and associated subsystems

The performance of quasi-steady magnetoplasmadynamic (MPD) thrusters at high power levels is discussed. An axisymmetric configuration is used for the MPD thruster, with various cathode and anode sizes, over a wide range of experimental conditions. Thrust is determined from impulse measurements with current waveforms, while instantaneous measurements are made for all other variables. It is demonstrated that the thrust produced has a predominately self-magnetic origin and is directly proportional to the square of the current. The complete set of impulse measurement data is presented

Circuit QED and sudden phase switching in a superconducting qubit array

Superconducting qubits connected in an array can form quantum many-body systems such as the quantum Ising model. By coupling the qubits to a superconducting resonator, the combined system forms a circuit QED system. Here, we study the nonlinear behavior in the many-body state of the qubit array using a semiclassical approach. We show that sudden switchings as well as a bistable regime between the ferromagnetic phase and the paramagnetic phase can be observed in the qubit array. A superconducting circuit to implement this system is presented with realistic parameters .Comment: 4 pages, 3 figures, submitted for publication

Quasi-steady MPD propulsion at high power Final technical report

Quasi-steady MPD propulsion at power levels in range 1 to 10 megawatt

Patient experience and challenges in group concept mapping for clinical research.

BACKGROUND AND OBJECTIVE: Group concept mapping (GCM) is a research method that engages stakeholders in generating, structuring and representing ideas around a specific topic or question. GCM has been used with patients to answer questions related to health and disease but little is known about the patient experience as a participant in the process. This paper explores the patient experience participating in GCM as assessed with direct observation and surveys of participants. METHODS: This is a secondary analysis performed within a larger study in which 3 GCM iterations were performed to engage patients in identifying patient-important outcomes for diabetes care. Researchers tracked the frequency and type of assistance required by each participant to complete the sorting and rating steps of GCM. In addition, a 17-question patient experience survey was administered over the telephone to the participants after they had completed the GCM process. Survey questions asked about the personal impact of participating in GCM and the ease of various steps of the GCM process. RESULTS: Researchers helped patients 92 times during the 3 GCM iterations, most commonly to address software and computer literacy issues, but also with the sorting phase itself. Of the 52 GCM participants, 40 completed the post-GCM survey. Respondents averaged 56 years of age, were 50% female and had an average hemoglobin A1c of 9.1%. Ninety-two percent (n = 37) of respondents felt that they had contributed something important to this research project and 90% (n = 36) agreed or strongly agreed that their efforts would help others with diabetes. Respondents reported that the brainstorming session was less difficult when compared with sorting and rating of statements. DISCUSSION: Our results suggest that patients find value in participating in GCM. Patients reported less comfort with the sorting step of GCM when compared with brainstorming, an observation that correlates with our observations from the GCM sessions. Researchers should consider using paper sorting methods and objective measures of sorting quality when using GCM in patient-engaged research to improve the patient experience and concept map quality

Re-Evaluation of Ar-39 - Ar-40 Ages for Apollo Lunar Rocks 15415 and 60015

We re-analyzed 39Ar-40Ar ages of Apollo lunar highland samples 15415 and 60015, two ferroan anorthosites analyzed previously in the 1970 s, with a more detailed approach and with revised decay constants. From these samples we carefully prepared 100-200 mesh mineral separates for analysis at the Noble Gas Laboratory at NASA-Johnson Space Center. The Ar-39-Ar-40 age spectra for 15415 yielded an age of 3851 +/- 38 Ma with 33-99% of Ar39 release, roughly in agreement with previously reported Ar-Ar ages. For 60015, we obtained an age of 3584 +/- 152 Ma in 23-98% of Ar39 release, also in agreement with previously reported Ar-Ar ages of approximately 3.5 Ga. Highland anorthosites like these are believed by many to be the original crust of the moon, formed by plagioclase floatation atop a magma ocean, however the Ar-Ar ages of 15415 and 60015 are considerably younger than lunar crust formation. By contrast, recently recovered lunar anorthosites such as Dhofar 489, Dhofar 908, and Yamato 86032 yield older Ar-Ar ages, up to 4.35 Ga, much closer to time of formation of the lunar crust. It follows that the Ar-Ar ages of the Apollo samples must have been reset by secondary heating, and that this heating affected highland anorthosites at both the Apollo 15 and Apollo 16 landing sites but did not affect lunar highland meteorites. One obvious consideration is that while the Apollo samples were collected from the near side of the moon, these lunar meteorites are thought to have originated from the lunar far sid

Isotopic Evidence for a Martian Regolith Component in Martian Meteorites

Noble gas measurements in gas-rich impact-melt (GRIM) glasses in EET79001 shergottite showed that their elemental and isotopic composition is similar to that of the Martian atmosphere [1-3]. The GRIM glasses contain large amounts of Martian atmospheric gases. Those measurements further suggested that the Kr isotopic composition of Martian atmosphere is approximately similar to that of solar Kr. The (80)Kr(sub n) - (80)Kr(sub M) mixing ratio in the Martian atmosphere reported here is approximately 3%. These neutron-capture reactions presumably occurred in the glass-precursor regolith materials containing Sm- and Br- bearing mineral phases near the EET79001/ Shergotty sites on Mars. The irradiated materials were mobilized into host rock voids either during shock-melting or possibly by earlier aeolian / fluvial activity

Developing Cultural Competence among 4-H Leaders

Access, equity, diversity, and inclusion are essential elements of 4-H’s goals related to positive youth development and organizational sustainability. The 4-H organization has impacted over 6 million youth worldwide and continues to grow every day. At the county, state, and national level, 4-H programs have grown more diverse, making it essential that 4-H programs encourage and highlight cultural similarities and differences through education. However, training in cultural competence for 4-H leaders is lacking, which is the bridge to connecting diversity and inclusion. Cultural competency is an awareness of one’s own cultural identity and the ability to interact effectively and appropriately with people from other cultures. This project utilized a multidisciplinary and collaborative effort to deliver cultural competence training for 27 4-H young adult and adult leaders in a mid-South U.S. state. All participants completed pre-assessments of the Intercultural Development Inventory (IDI), participated in 2-hour training sessions on cultural competence, and completed post-IDI assessments three months later. Overall, most 4-H leaders scored in the Minimization orientation, which is the most common orientation among adults. In order to advance beyond the Minimization orientation to the Acceptance orientation, 4-H educators need additional educational opportunities, which may aid them in understanding crucial differences between cultures. The cultural competency model of the IDI provides a valuable framework in preparing culturally sensitive 4-H educators to construct settings where equity, access, and opportunity are available to all youth, allowing 4-H members to better reach their potential as capable, caring, and competent leaders of today and tomorrow

39Ar - 40Ar Studies of Lherzolitic Shergottites Yamato 000097 and 984028

Yamato 984028 (Y984028) was discovered by the Japanese Antarctic Research Expedition (JARE) in 1998 and recently classified as a lherzolitic shergottite with large pyroxene oikocrysts enclosing rounded olivine and chromites. It also contains shock veining and maskelynite. Y984028 is paired with the more recent lherzolitic shergottite finds Y000027/47/97 based on similarities in mineralogy and chemistry, as well as isotopic composition. We present here the studied Ar-39-Ar-40 of Y-984028 whole rock (WR) and pyroxene (Px), in order to gain better understanding of trapped Ar components with a comparison of the possibly-paired Y000097 Ar release

Canonical and kinetic forms of the electromagnetic momentum in an ad hoc quantization scheme for a dispersive dielectric

An ad hoc quantization scheme for the electromagnetic field in a weakly dispersive, transparent dielectric leads to the definition of canonical and kinetic forms for the momentum of the electromagnetic field in a dispersive medium. The canonical momentum is uniquely defined as the operator that generates spatial translations in a uniform medium, but the quantization scheme suggests two possible choices for the kinetic momentum operator, corresponding to the Abraham or the Minkowski momentum in classical electrodynamics. Another implication of this procedure is that a wave packet containing a single dressed photon travels at the group velocity through the medium. The physical significance of the canonical momentum has already been established by considerations of energy and momentum conservation in the atomic recoil due to spontaneous emission, the Cerenkov effect, the Doppler effect, and phase matching in nonlinear optical processes. In addition, the data of the Jones and Leslie radiation pressure experiment is consistent with the assignment of one ?k unit of canonical momentum to each dressed photon. By contrast, experiments in which the dielectric is rigidly accelerated by unbalanced electromagnetic forces require the use of the Abraham momentum.Comment: 21 pages, 1 figure, aip style, submitted to PR