An investigation of volcanic gases and dust (aerosols) in the stratosphere

There are no author-identified significant results in this report

Twisted split-ring-resonator photonic metamaterial with huge optical activity

Coupled split-ring-resonator metamaterials have previously been shown to exhibit large coupling effects, which are a prerequisite for obtaining large effective optical activity. By a suitable lateral arrangement of these building blocks, we completely eliminate linear birefringence and obtain pure optical activity and connected circular optical dichroism. Experiments at around 100-THz frequency and corresponding modeling are in good agreement. Rotation angles of about 30 degrees for 205nm sample thickness are derived.Comment: 6 pages, 4 figure

Voyager 1 and 2 measurements of radial and latitudinal cosmic ray gradients during 1981 - 1984

The cosmic ray radial gradient was determined during 1981-84 using data from very similar detectors onboard spacecraft Voyagers 1 and 2 (radial separation approx. 6 AU, heliolatitude separation approx. 25 deg.) and from the Earth-orbiting satellite IMP 8. The principal result is that the radial gradient over this period decreased at the rate approx. 2.0%/AU between 1 and 16 AU and approx. 0.6%/AU between approx. 16 and 22 AU

Student Perceptions of Male and Female Instructors in a Post-Secondary Welding Course

Agricultural mechanics and welding have traditionally been perceived to be careers reserved for males, yet more females have entered professions using welding such as agricultural education. This research was developed because of the lack of gender research in welding. The purpose of this study was to examine students’ perceptions of learning from a male instructor versus a female instructor in a post-secondary welding course. We examined associations and differences between students’ preference of a male and a female welding instructor as well as individual self-efficacy and perceptions towards using welding technology. The population for this study was undergraduate students and the sample was 45 undergraduate students enrolled in a beginning welding course at Utah State University. Students’ perceptions toward welding technology and learning welding technology, tinkering self-efficacy, demographics, and preferences toward the gender of their welding instructor were collected to look at differences between students. Research findings suggest receiving instruction from a female welding instructor had a positive influence on the student’s beliefs of learning from a female instructor. Several individuals showed evidence of gender bias or preference through their survey responses. Male students had higher levels of tinkering self-efficacy, were more involved in a technology-oriented degree of studies, and overall had more welding experience compared to the female students. Recommendations include more agricultural mechanics coursework in agricultural education teacher preparation programs to increase confidence to teach agricultural mechanics for all agricultural educators, addressing gender bias issues in teaching methods courses, and more research be conducted in a similar environment to verify gender bias in agricultural mechanics

THE NUCLEAR ROCKET: NEW POWERPLANT FOR SPACE VEHICLE PROPULSION

A fundamental and practical survey is made of nuclear rocket application to space vehicle propulsion. The engine is described and propellant and radiation effects are discussed. Project Rover is summarized and performance requirements for a space vehicle are discussed. It is concluded that nuclear rockets can provide substantial performance, reliability, and economic advantages for difficult space missions. (T.R.H.

Causes of the Violation of Integrity Constraints for Supporting the Quality of Databases

[EN] The quality of the information provided by databases can be captured by integrity constraints. Thus, violated cases of constraints may serve as a basis for measuring the quality of given database states. A quality metric with the potential of more accuracy is obtained by measuring the causes, i.e., data that are responsible for constraint violations. Such measures also serve for controlling quality impairment across updates.Partially supported by FEDER and the Spanish grants TIN2009-14460-C03 and TIN2010-17139Decker, H. (2011). Causes of the Violation of Integrity Constraints for Supporting the Quality of Databases. Lecture Notes in Computer Science. 6786:283-292. https://doi.org/10.1007/978-3-642-21934-4_24S2832926786Ceri, S., Gottlob, G., Tanca, L.: What you always wanted to know about Datalog (and never dared to ask). TKDE 1(1), 146–166 (1989)Christiansen, H., Martinenghi, D.: On simplification of database integrity constraints. Fundam. Inform. 71(4), 371–417 (2006)Decker, H.: Answers that Have Integrity in Databases that Violate Constraints. Presented at the ICALP Workshop SDKB 2010, to appear in the Post-Workshop Proceedings of SDKB (2011)Decker, H.: Toward a uniform cause-based approach to inconsistency-tolerant database semantics. In: Meersman, R., Dillon, T., Herrero, P. (eds.) OTM 2010. LNCS, vol. 6427, pp. 983–998. Springer, Heidelberg (2010)Decker, H.: Quantifying the Quality of Stored Data by Measuring their Integrity. In: Proc. DIWT 2009, Workshop SMM, pp. 823–828. IEEE, Los Alamitos (2009)Decker, H., Martinenghi, D.: Inconsistency-tolerant Integrity Checking. TKDE 23(2), 218–234 (2011)Decker, H., Martinenghi, D.: Modeling, measuring and monitoring the quality of information. In: Heuser, C.A., Pernul, G. (eds.) ER 2009. LNCS, vol. 5833, pp. 212–221. Springer, Heidelberg (2009)Grant, J., Hunter, A.: Measuring inconsistency in knowledgebases. J. Intelligent Information Systems 27(2), 159–184 (2006)Ramakrishnan, R., Gehrke, J.: Database Management Systems. McGraw-Hill, New York (2003

Kinetic modelling of runaway electron avalanches in tokamak plasmas

Runaway electrons (REs) can be generated in tokamak plasmas if the accelerating force from the toroidal electric field exceeds the collisional drag force due to Coulomb collisions with the background plasma. In ITER, disruptions are expected to generate REs mainly through knock-on collisions, where enough momentum can be transferred from existing runaways to slow electrons to transport the latter beyond a critical momentum, setting off an avalanche of REs. Since knock-on runaways are usually scattered off with a significant perpendicular component of the momentum with respect to the local magnetic field direction, these particles are highly magnetized. Consequently, the momentum dynamics require a full 3-D kinetic description, since these electrons are highly sensitive to the magnetic non-uniformity of a toroidal configuration. A bounce-averaged knock-on source term is derived. The generation of REs from the combined effect of Dreicer mechanism and knock-on collision process is studied with the code LUKE, a solver of the 3-D linearized bounce-averaged relativistic electron Fokker-Planck equation, through the calculation of the response of the electron distribution function to a constant parallel electric field. This work shows that the avalanche effect can be important even in non-disruptive scenarios. RE formation through knock-on collisions is found to be strongly reduced when taking place off the magnetic axis, since trapped electrons cannot contribute to the RE population. The relative importance of the avalanche mechanism is investigated as a function of the key parameters for RE formation; the plasma temperature and the electric field strength. In agreement with theoretical predictions, the simulations show that in low temperature and E-field knock-on collisions are the dominant source of REs and can play a significant role for RE generation, including in non-disruptive scenarios.Comment: 23 pages, 12 figure