Synthesis of a new class of highly fluorinated aliphatic diisocyanates

Synthesis is basis for preparation of polyurethanes that are compatible with liquid oxygen. The two step process preparation from fluorocarbon diacid fluorides is explained in text

The Refined Elliptic Genus and Coulomb Gas Formulations of N=2N=2 Superconformal Coset Models

We describe, in some detail, a number of different Coulomb gas formulations of $N=2$ superconformal coset models. We also give the mappings between these formulations. The ultimate purpose of this is to show how the Landau-Ginzburg structure of these models can be used to extract the $W$-generators, and to show how the computation of the elliptic genus can be refined so as to extract very detailed information about the characters of component parts of the model.Comment: 40 pages in harvmac, no figure

MLS vertical guidance and navigation for a STOL airplane landing on an elevated STOLport

In contrast to CTOL landing operations, STOL airplanes landing on short STOLport runways typically begin the flare maneuver before reaching the runway surface. Vertical guidance procedures were developed to allow an autoland flight control system for a STOL airplane to use Microwave Landing System (MLS) signals as altitude and sink rate references for flare initiation, with a transition to radar altimeter after the airplane is over the runway. The implementation has minimum impact on the control system and landing performance. Data are presented which show validation of the concepts in a simulator

A Challenge to All: Raising the Participation and Success of Women and Minorities in Mathematics, Science, and Technlogy

This issue of our journal is the product of a Virginia Mathematics and Science Coalition (VMSC) conference titled, Programs That Work and held in March, 2000 on the issues of raising both the levels of success and the levels of participation of women and minorities in mathematics, science, and technology. Traditionally, these two groups have had low rates of participation in these subjects, and we believe this situation can and must be changed. The conference was to Coalition\u27s first direct assault on the problem

Opponents and supporters of water policy change in the Netherlands and Hungary

This paper looks at the role of individuals and the strategies that they use to bring about or oppose major policy change. Current analysis of the role that individuals or small collectives play in periods of major policy change has focussed on strategies that reinforce change and on the supporters of change. This paper adds the perspective of opponents, and asks whether they use similar strategies as those identified for supporters. Five strategies are explored: developing new ideas, building coalitions to sell ideas, using windows of opportunity, playing multiple venues and orchestrating networks. Using empirical evidence from Dutch and Hungarian water policy change, we discuss whether individuals pursued these strategies to support or oppose major policy change. Our analysis showed the significance of recognition of a new policy concept at an abstract level by responsible government actors, as well as their engagement with a credible regional coalition that can contextualise and advocate the concept regionally. The strategies of supporters were also used by opponents of water policy change. Opposition was inherent to policy change, and whether or not government actors sought to engage with opponents influenced the realisation of water policy change

Economic Reform and the Process of Global Integration

macroeconomics, economic reform, global integration

The role of the helicopter in transportation

A general overview is presented of the role that the helicopter plays in the current aviation scene with special emphasis on its use in the airport access function. Technological problems of present-day aircraft are discussed along with some plausible solutions. The economic and regulatory aspects of commercial helicopter operations are presented. Finally six commercial operations utilizing helicopters are reviewed and conditions that enhance the success of the helicopter in the airport access function are proposed

Carbon films grown from plasma on III-V semiconductors

Dielectric carbon films were grown on n- and p-type GaAs and InP substrates using plasmas generated at 30 KHz from gaseous hydrocarbons. The effect of gas source, flow rate, and power on film growth were investigated. Methane and n-butane gases were utilized. The flow rate and power ranged from 30 to 50 sccm and 25 to 300 W, respectively. AES measurements show only carbon to be present in the films. The relative Ar ion sputtering rate (3 KeV) of carbon depends on the ratio power/pressure. In addition, the degree of asymmetry associated with the carbon-semiconductor interface is approximately power-independent. SIMS spectra indicate different H-C bonding configurations to be present in the films. Band gaps as high as 3.05 eV are obtained from optical absorption studies

Electrical properties of oxide glasses containing iron and manganese

Imperial Users onl