Thermal Ecology of the Federally Endangered Blunt-nosed Leopard Lizard

Recognizing how climate change will impact populations can aid in making decisions about approaches for conservation of endangered species. The Blunt-nosed Leopard Lizard (Gambelia sila) is a federally endangered species that, despite protection, remains in extremely arid, hot areas and may be at risk of extirpation due to climate change. We collected data on the field-active body temperatures, preferred body temperatures, and upper thermal tolerance of G. sila. We then described available thermal habitat using biophysical models, which allowed us to (1) describe patterns in lizard body temperatures, microhabitat temperatures, and lizard microhabitat use, (2) quantify the lizards’ thermoregulatory accuracy, (3) calculate the number of hours they are currently thermally restricted in microhabitat use, (4) project how the number of restricted hours will change in the future as ambient temperatures rise, and (5) assess the importance of Giant Kangaroo Rat burrows and shade-providing shrubs in the current and projected future thermal ecology of G. sila. Lizards maintained fairly consistent daytime body temperatures over the course of the active season, and use of burrows and shrubs increased as the season progressed and ambient temperatures rose. During the hottest part of the year, lizards shuttled among kangaroo rat burrows, shrubs, and open habitat to maintain body temperatures below their upper thermal tolerance, but occasionally, higher than their preferred body temperature range. Lizards are restricted from staying in the open habitat for 75% of daylight hours and are forced to seek refuge under shrubs or burrows to avoid surpassing their upper thermal threshold. After applying climatic projections of 1 and 2˚C increases to 2018 ambient temperatures, G. sila will lose additional hours of activity time that could compound stressors faced by this population, potentially leading to extirpation. Finally, temperature-based activity estimation (TBAE) is an automated method for predicting surface activity and microhabitat use based on the temperature of an organism and its habitat. In an attempt to lessen impacts on sensitive species and costs, we assessed continuously logged field active body temperatures as a tool to predict the surface activity and microhabitat use of an endangered lizard (Blunt-nosed Leopard Lizard, Gambelia sila). We found that TBAE accurately predicts whether a lizard is above or below ground 75.7% of the time when calculated using air temperature, and 60.5% of the time when calculated using biophysical models. While surface activity was correctly predicted about 93% of the time using either method, accuracy in predicting below ground (burrow) occupancy was 62% for air temperature and 51% for biophysical models. Using biophysical model data, TBAE accurately predicts microhabitat use in 79% of observations in which lizards are in the sun, 47% in the shade, and 51% in burrows. Heliotherms bask in the sun, and thus body temperatures can shift rapidly when the animal moves to a new microhabitat. This sensitivity, makes TBAE a promising means of remotely monitoring animal activity, particularly for specific variables like emergence time and surface activity

Introduction to the problem of rocket-powered aircraft performance

An introduction to the problem of determining the fundamental limitations on the performance possibilities of rocket-powered aircraft is presented. Previous material on the subject is reviewed and given in condensed form along with supplementary analyses. Some of the problems discussed are: 1) limiting velocity of a rocket projectile; 2) limiting velocity of a rocket jet; 3) jet efficiency; 4) nozzle characteristics; 5) maximum attainable altitudes; 6) ranges. Formulas are presented relating the performance of a rocket-powered aircraft to basic weight and nozzle dimensional parameters. The use of these formulas is illustrated by their application to the special case of a nonlifting rocket projectile

Convectively driven coastal currents in a rotating basin

Density driven coastal currents were produced in the laboratory by differentially heating and cooling the end walls of a rotating rectangular cavity. After turning on the heat flux, intrusions propagated along the side walls of the cavity under an inertial buoyancy balance, with a geostrophic cross-stream balance. These boundary currents were internally stratified in temperature, while the environment during the early stages of development of the flow was isothermal. Rotational instabilities developed on the edge of the currents and broke to form cyclone-anticyclone eddy pairs. Measurements were made of the intrusion velocity, the temporal development of the width of the boundary currents, their internal thermal structure, and the characteristics of the unstable waves, including their growth rates, wavelengths, and phase speeds. Comparisons are made with previous field observations of the Leeuwin Current off Western and Southern Australia

Giving voice to equitable collaboration in participatory design

An AHRC funded research project titled Experimenting with the Co-experience Environment (June 2005 – June 2006) culminated in a physical environment designed in resonance with a small group of participants. The participants emerged from different disciplines coming together as a group to share their expertise and contribute their knowledge to design. They engaged in storytelling, individual and co-thinking, creating and co-creating, sharing ideas that did not require justification, proposed designs even though most were not designers …and played. The research questioned how a physical environment designed specifically for co-experiencing might contribute to new knowledge in design? Through play and by working in action together the participants demonstrated the potential of a physical co-experience environment to function as a scaffold for inter-disciplinary design thinking,saying, doing and making (Ivey & Sanders 2006). Ultimately the research questioned how this outcome might influence our approach to engaging participants in design research and experimentation

Non-ideality of quantum operations with the electron spin of a 31P donor in a Si crystal due to interaction with a nuclear spin system

We examine a 31P donor electron spin in a Si crystal to be used for the purposes of quantum computation. The interaction with an uncontrolled system of 29Si nuclear spins influences the electron spin dynamics appreciably. The hyperfine field at the 29Si nuclei positions is non-collinear with the external magnetic field. Quantum operations with the electron wave function, i.e. using magnetic field pulses or electrical gates, change the orientation of hyperfine field and disturb the nuclear spin system. This disturbance produces a deviation of the electron spin qubit from an ideal state, at a short time scale in comparison with the nuclear spin diffusion time. For H_ext=9 T, the estimated error rate is comparable to the threshold value required by the quantum error correction algorithms. The rate is lower at higher external magnetic fields.Comment: 11 pages, 2 figure

Simple mixing criteria for the growth of negatively buoyant phytoplankton

Phytoplankton population dynamics are controlled by the relative rather than absolute timescales of mixing, growth, and loss processes such as sedimentation, grazing, and so on. Here, the vertical distribution and biomass of phytoplankton populations are quantified by two timescale ratios: the Peclet number Pe the ratio of mixing and sedimentation timescales-and the growth number G the ratio of sedimentation and net growth timescales. Three mixing regimes are defined for phytoplankton and other particles. For Pe greater than or equal to 100, the population is translated linearly down the water column over time and will leave the surface mixing layer completely after sedimentation time 7, For 0.