Monolayers of 3He on the Surface of Bulk Superfluid 4He

We have used quantum evaporation to investigate the two-dimensional fermion system that forms at the free surface of (initially isotopically pure) 4He when small quantities of 3He are added to it. By measuring the first-arrival times of the evaporated atoms, we have determined that the 3He-3He potential in this system is V_3S/k_B=(0.23+/-0.02) K nm^2 (repulsive) and estimated a value of m_3S=(1.53+/-0.02)m_3 for the zero-coverage effective mass. We have also observed the predicted second layer-state which becomes occupied once the first layer-state density exceeds about 0.6 monolayers.Comment: 2 pages, 3 figures. Submitted to Proc. LT-22 (1999) to appear in Physica

Relative Evaporation Probabilities of 3He and 4He from the Surface of Superfluid 4He

We report a preliminary experiment which demonstrates that 3He atoms in Andreev states are evaporated by high-energy (E/k_B ~ 10.2 K) phonons in a quantum evaporation process similar to that which occurs in pure 4He. Under conditions of low 3He coverage, high-energy phonons appear to evaporate 3He and 4He atoms with equal probability. However, we have not managed to detect any 3He atoms that have been evaporated by rotons, and conclude that the probability of a roton evaporating a 3He atom is less than 2% of the probability that it evaporates a 4He atom.Comment: 2 pages, 3 figures. Submitted to Proc. LT-22 (1999) Physica

An annotated checklist of the Coleoptera (Insecta) of the Cayman Islands, West Indies

A faunal list of 605 species of Coleoptera in 396 genera in 63 families is presented for the Cayman Islands. For most species, island and locality within island collecting information is provided

Studies on the use of supercritical ammonia for ceramic nitride synthesis and fabrication

The extractability of ammonia halides (including ammonium thiocyanate) formed as byproducts from the synthesis of Si(NH)2 via ammonolysis of the corresponding silicon tetrahalides using supercritical NH3 as the extraction medium was investigated. It was found that the NH4SCN byproduct of ammonolysis of Si(SCN)4 can be almost completely extracted from the insoluble Si(NH)2 forming a promising system for the synthesis of pure Si(NH)2, one of the best precursors for Si3N4. In addition it was found that Si3N4, AlN, BN, and Si(NH)2 are insoluble in SC ammonia. Also discussed are design considerations for a supercritical ammonia extraction unit

Modeling and Analysis of Power Processing Systems (MAPPS), initial phase 2

The overall objective of the program is to provide the engineering tools to reduce the analysis, design, and development effort, and thus the cost, in achieving the required performances for switching regulators and dc-dc converter systems. The program was both tutorial and application oriented. Various analytical methods were described in detail and supplemented with examples, and those with standardization appeals were reduced into computer-based subprograms. Major program efforts included those concerning small and large signal control-dependent performance analysis and simulation, control circuit design, power circuit design and optimization, system configuration study, and system performance simulation. Techniques including discrete time domain, conventional frequency domain, Lagrange multiplier, nonlinear programming, and control design synthesis were employed in these efforts. To enhance interactive conversation between the modeling and analysis subprograms and the user, a working prototype of the Data Management Program was also developed to facilitate expansion as future subprogram capabilities increase

Gender in the Property Industry and Professional Bodies - An Australian Perspective

Recently, significant public debate regarding the lack of women appointed to senior management positions such as on ASX listed company boards has highlighted the lack of gender equity. The property industry is dominated by male representation at the top levels despite the gender gap within university graduates approaching equal proportions. This paper evaluates the role that professional bodies are embracing to address the gender inequality and how this is reflected in the makeup of the board composition of the leading professional associations and industry bodies in Australia. While there is limited research on women in property this paper demonstrates the need for further in-depth analysis to identify the constraints to progressing gender equality. The findings indicate that the property profession while publicly promoting women in the property industry still maintain governing boards within their professional associations and industry bodies that are significantly under-represented by women