Remembering Lee Ann in South Africa: Meta-data and reflexive research practice

Lee Ann Fujii and I became fast friends, colleagues, and disciplinary comrades soon after we met at the 2004 Institute for Qualitative and Multi-Method Research (IQMR). IQMR presentations and workshops sparked fourteen years of conversation about the discipline, our positionality with respect to the discipline and research participants, methodologies, the “field,” and much more. Lee Ann made me laugh and encouraged me to think harder as we talked over coffee and chocolate at home in Oakland, New York, Washington, DC, Indianapolis, and Toronto; met up at APSA annual meetings; and practiced yoga together

Extreme Star Formation

Extreme star formation includes star formation in starbursts and regions forming super star clusters. We survey the current problems in our understanding of the star formation process in starbursts and super star clusters - initial mass functions, cluster mass functions, star formation efficiencies, and radiative feedback into molecular clouds - that are critical to our understanding of the formation and survival of large star clusters, topics that will be the drivers of the observations of the next decade.Comment: appeared in "Astrophysics in the Next Decade: JWST and Concurrent Facilities", Astrophysics and Space Science Proceedings, 2009, ed. H. A. Thronson, M. Stiavelli, and A. G. G. M. Tielens, proceedings of the conference, Astrophysics in the Next Decade, 24-27 September 2007, Tucson, A

On the Eccentricity Distribution of Exoplanets from Radial Velocity Surveys

We investigate the estimation of orbital parameters by least-$\chi^2$ Keplerian fits to radial velocity (RV) data using synthetic data sets. We find that while the fitted period is fairly accurate, the best-fit eccentricity and $M_p\sin i$ are systematically biased upward from the true values for low signal-to-noise ratio $K/\sigma\lesssim 3$ and moderate number of observations $N_{\rm obs}\lesssim 60$, leading to a suppression of the number of nearly circular orbits. Assuming intrinsic distributions of orbital parameters, we generate a large number of mock RV data sets and study the selection effect on the eccentricity distribution. We find the overall detection efficiency only mildly decreases with eccentricity. This is because although high eccentricity orbits are more difficult to sample, they also have larger RV amplitudes for fixed planet mass and orbital semi-major axis. Thus the primary source of uncertainties in the eccentricity distribution comes from biases in Keplerian fits to detections with low-amplitude and/or small $N_{\rm obs}$, rather than from selection effects. Our results suggest that the abundance of low-eccentricity exoplanets may be underestimated in the current sample and we urge caution in interpreting the eccentricity distributions of low-amplitude detections in future RV samples.Comment: Accepted for publication in Ap

Mapping islands, reefs and shoals in the oceans surrounding Australia

The author has identified the following significant results. Two geometric distortion tests of the same scene using different ground control identification methods have produced different estimates of the magnitude of geometric distortions of the image frame. A comparison of imagery with hydrographic charts shows that the imagery displays shoals and reefs which are close to the water surface. Such information can be used during the compilation of new maps of such regions, in the checking of existing hydrographic charts, or for navigation warning

Helicopters as a Theme in a Machine Design Course

Helicopters as a Theme in Teaching Machine Design A machine design course is required in most undergraduate mechanical engineering curricula.This course generally covers an introduction to mechanical engineering design, a review of materials engineering, a review of mechanics of materials (shear force and bending moment diagrams, stress and strain analysis, deflection and stiffness analysis of beams, columns, etc.),models for failure due to static loading and variable fatigue, and then presents (in somewhat arbitrary order) the design of specific mechanical elements: shafts, fasteners, springs, bearings,gears, flexible elements such as belts, chain, and wire rope, clutches, brakes, couplings, etc.For some topics in machine design it is not possible to develop analytical models from first principles, as is done in fluid mechanics or thermodynamics. Rather, there are guidelines and rules of thumb and equations that include factors that must be taken on blind faith and somehow used to get an approximate answer. The approach can be unsatisfying, arbitrary, and not meaningful unless it is tied to real-world problems.To help motivate student learning, foster interest in the topics, and make the material more alive,we are testing the idea of studying helicopters and their components throughout the course as a theme to teach students about the different mechanical elements. Helicopters are an ideal system to exemplify the concepts taught in the course because all aspects of machine design are encapsulated in the design of a helicopter and the price of failure of the components or design is high (human fatality). In the standard helicopter configuration, two turbine jet engines are used to drive a main rotor and a tail rotor and the pilot controls are mechanically linked to both rotors to allow for handling of the aircraft.For each topic in the course the connection to helicopters is presented and helicopter design challenges are posed. For example, the shafts and gearboxes used to transfer energy from the high-speed turbine engines to the low speed rotors can be used to teach students about shaft bending, gear design, and fatigue failure. When asked to design a gearbox to achieve the speed reduction between the turbine jet engine and the main rotor, students discover why planetary gears are used. Other topics such as clutches, brakes, couplings, fasteners, springs, and vibration effects are all prominent features of helicopter design. They serve as excellent motivating examples to show students the real-life applications of machine design concepts.In closing, students generally view the machine design course as very challenging and, due to themany specific machine elements covered, have difficulty seeing how the separate components fit within the needs for a real system. To address this concern, enhance learning, and bring more excitement to the topics, we explored the value of using a theme physical system, namely helicopters and their components, to bring the material to life when teaching machine design

The Birth of a Super Star Cluster: NGC 5253

We present images of the 7mm free-free emission from the radio "supernebula" in NGC 5253 made with the Very Large Array and the Pie Town link. The images reveal structure in the nebula, which has a <~ 1 pc (~50 mas radius) core requiring the excitation of 1200 O7 stars. The nebula is elongated, with an arc of emission curving to the northeast and to the south. The total ionizing flux within the central 1.2" (~20 pc) is 7 x 10^52 s^-1, corresponding to 7000 O7 stars. We propose that the radio source is coincident with a small, very red near-infrared cluster and apparently linked to a larger, optical source some 10 pc away on the sky. We speculate on the causes of this structure and what it might tell us about the birth of the embedded young super star cluster.Comment: Accepted, Astrophysical Journal Letters. 10 pages, including 2 figure