Ecological Art: Art with a Purpose

Ecological art is purposeful and often prescriptive: the actions and directions intended by the artists for activists to undertake often are clearly represented. Yet, ecological art has been no more successful than, for example, targeted scientific research, deposits on returnable bottles, or land-protection campaigns at slowing global warming, reducing the amount of waste we generate every day, or halting the ongoing sixth mass extinction in the history of the Earth. Here, we consider the idea that prescriptive ecological art provides insufficient mental space for creative reflection about future scenarios of, and responses to, environmental change. We ask whether, by presenting a limited range of possibilities in ecological art, we limit the range of options that viewers consider in deciding on possible actions that they could take to slow or halt environmental decline. We conclude by asking how we artists and scientists can best engage diverse audiences in critically thinking about, and taking action to mitigate, environmental change. These questions and issues are addressed through a discussion of two of our recent ecological art installations: Hemlock Hospice and Warming Warning

Wind tunnel buffet load measuring technique

Indirect force measurement technique estimates unsteady forces acting on elastic model during wind tunnel tests. Measurement of forces is practically insensitive to errors in aeroelastic scaling between model and full-scale structure, simplifying design, fabrication and dynamic calibration

B-Physics at the Tevatron (Proceedings of PASCOS2010)

We report on recent B-Physics results from the Tevatron. The topics covered include measurement of the polarization amplitudes in $B_s^0 \to \phi \phi$, the search for rare flavor-changing neutral-current decays, CP violation in $B_s^0 \to J/\psi \phi$ and semileptonic $B_s^0$ decays, and a new measurement of the like-sign asymmetry in dimuon events.Comment: 6 pages, proceedings paper, 16th International Symposium on Particles, Strings, and Cosmology, Valencia, Spain, July 19 - 23, 201

The effect of surface contamination on contact angles and surface potentials Summary report

Surface contamination effects on behavior of liquids in space vehicle tanks at zero gravit

Acceleration Rates and Injection Efficiencies in Oblique Shocks

The rate at which particles are accelerated by the first-order Fermi mechanism in shocks depends on the angle, \teq{\Tbone}, that the upstream magnetic field makes with the shock normal. The greater the obliquity the greater the rate, and in quasi-perpendicular shocks rates can be hundreds of times higher than those seen in parallel shocks. In many circumstances pertaining to evolving shocks (\eg, supernova blast waves and interplanetary traveling shocks), high acceleration rates imply high maximum particle energies and obliquity effects may have important astrophysical consequences. However, as is demonstrated here, the efficiency for injecting thermal particles into the acceleration mechanism also depends strongly on obliquity and, in general, varies inversely with \teq{\Tbone}. The degree of turbulence and the resulting cross-field diffusion strongly influences both injection efficiency and acceleration rates. The test particle \mc simulation of shock acceleration used here assumes large-angle scattering, computes particle orbits exactly in shocked, laminar, non-relativistic flows, and calculates the injection efficiency as a function of obliquity, Mach number, and degree of turbulence. We find that turbulence must be quite strong for high Mach number, highly oblique shocks to inject significant numbers of thermal particles and that only modest gains in acceleration rates can be expected for strong oblique shocks over parallel ones if the only source of seed particles is the thermal background.Comment: 24 pages including 6 encapsulated figures, as a compressed, uuencoded, Postscript file. Accepted for publication in the Astrophysical Journa

Core-collapse model of broadband emission from SNR RX J1713.7-3946 with thermal X-rays and Gamma-rays from escaping cosmic rays

We present a spherically symmetric, core-collapse model of SNR RX J1713.7-3946 that includes a hydrodynamic simulation of the remnant evolution coupled to the efficient production of cosmic rays (CRs) by nonlinear diffusive shock acceleration (DSA). High-energy CRs that escape from the forward shock (FS) are propagated in surrounding dense material that simulates either a swept-up, pre-supernova shell or a nearby molecular cloud. The continuum emission from trapped and escaping CRs, along with the thermal X-ray emission from the shocked heated ISM behind the FS, integrated over the remnant, is compared against broadband observations. Our results show conclusively that, overall, the GeV-TeV emission is dominated by inverse-Compton from CR electrons if the supernova is isolated regardless of its type, i.e., not interacting with a >>100 Msun shell or cloud. If the SNR is interacting with a much larger mass >10^4 Msun, pion-decay from the escaping CRs may dominate the TeV emission, although a precise fit at high energy will depend on the still uncertain details of how the highest energy CRs are accelerated by, and escape from, the FS. Based on morphological and other constraints, we consider the 10^4 Msun pion-decay scenario highly unlikely for SNR RX J1713.7-3946 regardless of the details of CR escape. Importantly, even though CR electrons dominate the GeV-TeV emission, the efficient production of CR ions is an essential part of our leptonic model.Comment: 11 pages with 7 figures. Submitted to Ap