Introducing the black hole

The quasi-stellar object, the pulsar, the neutron star have all come onto the scene of physics within the space of a few years. Is the next entrant destined to be the black hole? If so, it is difficult to think of any development that could be of greater significance. A black hole, whether of “ordinary size” (approximately one solar mass, 1 M⊙) or much larger (around 10^6 M⊙ to 10^10 M⊙, as proposed in the nuclei of some galaxies), provides our “laboratory model” for the gravitational collapse, predicted by Einstein's theory, of the universe itself

The Pauli Exclusion Principle and SU(2) vs. SO(3) in Loop Quantum Gravity

Recent attempts to resolve the ambiguity in the loop quantum gravity description of the quantization of area has led to the idea that j=1 edges of spin-networks dominate in their contribution to black hole areas as opposed to j=1/2 which would naively be expected. This suggests that the true gauge group involved might be SO(3) rather than SU(2) with attendant difficulties. We argue that the assumption that a version of the Pauli principle is present in loop quantum gravity allows one to maintain SU(2) as the gauge group while still naturally achieving the desired suppression of spin-1/2 punctures. Areas come from j=1 punctures rather than j=1/2 punctures for much the same reason that photons lead to macroscopic classically observable fields while electrons do not.Comment: This paper received an "honorable mention" in the 2003 Essay Competition of the Gravity Research Foundation and should be appearing in a special issue of Int. J. Mod. Phys.

Model Averaging Software for Dichotomous Dose Response Risk Estimation

Model averaging has been shown to be a useful method for incorporating model uncertainty in quantitative risk estimation. In certain circumstances this technique is computationally complex, requiring sophisticated software to carry out the computation. We introduce software that implements model averaging for risk assessment based upon dichotomous dose-response data. This software, which we call Model Averaging for Dichotomous Response Benchmark Dose (MADr-BMD), fits the quantal response models, which are also used in the US Environmental Protection Agency benchmark dose software suite, and generates a model-averaged dose response model to generate benchmark dose and benchmark dose lower bound estimates. The software fulfills a need for risk assessors, allowing them to go beyond one single model in their risk assessments based on quantal data by focusing on a set of models that describes the experimental data.

Atmospheric leakage and condensate production in NASA's biomass production chamber. Effect of diurnal temperature cycles

A series of tests were conducted to monitor atmospheric leakage rate and condensate production in NASA's Biomass Production Chamber (BPC). Water was circulated through the 64 plant culture trays inside the chamber during the tests but no plants were present. Environmental conditions were set to a 12-hr photoperiod with either a matching 26 C (light)/20 C (dark) thermoperiod, or a constant 23 C temperature. Leakage, as determined by carbon dioxide decay rates, averaged about 9.8 percent for the 26 C/20 C regime and 7.3 percent for the constant 23 C regime. Increasing the temperature from 20 C to 26 C caused a temporary increase in pressure (up to 0.5 kPa) relative to ambient, while decreasing the temperature caused a temporary decrease in pressure of similar magnitude. Little pressure change was observed during transition between 23 C (light) and 23 C (dark). The lack of large pressure events under isothermal conditions may explain the lower leakage rate observed. When only the plant support inserts were placed in the culture trays, condensate production averaged about 37 liters per day. Placing acrylic germination covers over the tops of culture trays reduced condensate production to about 7 liters per day. During both tests, condensate production from the lower air handling system was 60 to 70 percent greater than from the upper system, suggesting imbalances exist in chilled and hot water flows for the two air handling systems. Results indicate that atmospheric leakage rates are sufficiently low to measure CO2 exchange rates by plants and the accumulation of certain volatile contaminants (e.g., ethylene). Control system changes are recommended in order to balance operational differences (e.g., humidity and temperature) between the two halves of the chamber

Twenty-Eight Years of Amazement-So Far

The following account describes the author’s transition to using SFBT whilst working in a Child & Adolescent Mental Health Service, and reflections on the influences on his practice prior to discovering the approach. Through two examples of practice the author shares his continuing sense of amazement over the potential for SFBT to be both effective and efficient. This paper concludes with a first-hand account of someone who experienced the effectiveness and efficiency of SFBT when seeking therapy for a long-standing set of challenges

The Impact of Anchorage's 2000 and 2007 Smoke-Free Policies on Select Restaurants and Bars

The American Lung Association in Alaska (ALAA) asked the Institute of Social and Economic Research (ISER) to investigate the impact of the Anchorage 2000 and 2007 Clean Indoor Air (CIA) municipal ordinances on selected restaurants and bars. As previous U.S. studies have been conducted that speak to the economic and health impacts of CIA laws, ALAA also requested that ISER synthesize results of these existing studies and conduct a survey on restaurant and bar representatives’ perceptions of the impact of the ordinances.The American Lung Association in AlaskaExecutive Summary / Introduction / Anchorage Municipal Ordinances / Policy Enforcement / Literature Review: Impact of Smoke-Free Laws on Employment and Air Quality / Methodology / Key Informant Interview Findings / Survey Findings / Limitations / References / Appendice

The introduction of ICT in fieldwork to enhance student learning

Report of a CELT project on supporting students through innovation and researchThe aim of the project was to introduce a dedicated ICT package into the fieldwork experience in order to enhance student learning in the field at a range of levels and in a number of subject areas. The field kit consists of a laptop computer, digital camera with multi-card reader, global positioning system (GPS), video camera, portable scanner and printer. The kit is kept in a waterproof portable case specifically for student fieldwork use (Plate 1). A digital microscope and video camera is also separately available. The students have been able to use the equipment in the field in order to produce supporting materials to enhance their fieldwork. For example the IT package has been used in conjunction with a data-logger on mapping equipment allowing maps to be printed in the field for detailed recording of field sites. Also the use of digital and video cameras has allowed students to take responsibility for identifying and recording aspects of fieldwork for their reports