Component research for future propulsion systems

Factors affecting the helicopter market are reviewed. The trade-offs involving acquisition cost, mission reliability, and life cycle cost are reviewed, including civil and military aspects. The potential for advanced vehicle configurations with substantial improvements in energy efficiency, operating economics, and characteristics to satisfy the demands of the future market are identified. Advanced propulsion systems required to support these vehicle configurations are discussed, as well as the component technology for the engine systems. Considerations for selection of components in areas of economics and efficiency are presented

Report of optical ground truth measurements for 5 August 1973, test site number 548532, in support of the Skylab multispectral scanner

There are no author-identified significant results in this report

Yukawa Couplings for the Spinning Particle and the World Line Formalism

We construct the world-line action for a Dirac particle coupled to a classical scalar or pseudo-scalar background field. This action can be used to compute loop diagrams and the effective action in the Yukawa model using the world-line path-integral formalism for spinning particles.Comment: 10 pages Latex, two uuencoded postscript figures. Note added at the en

On the Connection Between Momentum Cutoff and Operator Cutoff Regularizations

Operator cutoff regularization based on the original Schwinger's proper-time formalism is examined. By constructing a regulating smearing function for the proper-time integration, we show how this regularization scheme simulates the usual momentum cutoff prescription yet preserves gauge symmetry even in the presence of the cutoff scales. Similarity between the operator cutoff regularization and the method of higher (covariant) derivatives is also observed. The invariant nature of the operator cutoff regularization makes it a promising tool for exploring the renormalization group flow of gauge theories in the spirit of Wilson-Kadanoff blocking transformation.Comment: 28 pages in plain TeX, no figures. revised and expande

The Entropy of a Binary Hidden Markov Process

The entropy of a binary symmetric Hidden Markov Process is calculated as an expansion in the noise parameter epsilon. We map the problem onto a one-dimensional Ising model in a large field of random signs and calculate the expansion coefficients up to second order in epsilon. Using a conjecture we extend the calculation to 11th order and discuss the convergence of the resulting series

The Intrinsic Dimensionality of Attractiveness: A Study in Face Profiles

The study of human attractiveness with pattern analysis techniques is an emerging research field. One still largely unresolved problem is which are the facial features relevant to attractiveness, how they combine together, and the number of independent parameters required for describing and identifying harmonious faces. In this paper, we present a first study about this problem, applied to face profiles. First, according to several empirical results, we hypothesize the existence of two well separated manifolds of attractive and unattractive face profiles. Then, we analyze with manifold learning techniques their intrinsic dimensionality. Finally, we show that the profile data can be reduced, with various techniques, to the intrinsic dimensions, largely without loosing their ability to discriminate between attractive and unattractive face

Renormalization Group Flow Equations and the Phase Transition in O(N)-models

We derive and solve flow equations for a general O(N)-symmetric effective potential including wavefunction renormalization corrections combined with a heat-kernel regularization. We investigate the model at finite temperature and study the nature of the phase transition in detail. Beta functions, fixed points and critical exponents \beta, \nu, \delta and \eta for various N are independently calculated which allow for a verification of universal scaling relations.Comment: 34 pages, 3 tables, 11 postscript figures, LaTe

Male water striders attract predators to intimidate females into copulation

Despite recent advances in our understanding of sexual conflict and antagonistic coevolution between sexes, the role of interspecific interactions, such as predation, in these evolutionary processes remains unclear. In this paper, we present a new male mating strategy whereby a male water strider Gerris gracilicornis intimidates a female by directly attracting predators as long as she does not accept the male's coercive copulation attempt. We argue that this male strategy is a counteradaptation to the evolution of the female morphological shield protecting her genitalia from coercive intromission by water strider males. The G. gracilicornis mating system clearly represents an effect expected from models of the coevolutionary arms race between sexes, whereby one sex causes a decrease in the fitness component of the other sex. Moreover, our study demonstrates a crucial role that interspecific interactions such as predation can have in the antagonistic coevolution between sexes

The Higher Derivative Expansion of the Effective Action by the String-Inspired Method, Part I

The higher derivative expansion of the one-loop effective action for an external scalar potential is calculated to order O(T**7), using the string-inspired Bern-Kosower method in the first quantized path integral formulation. Comparisons are made with standard heat kernel calculations and with the corresponding Feynman diagrammatic calculation in order to show the efficiency of the present method.Comment: 13 pages, Plain TEX, 1 figure may be obtained from the authors, HD-THEP-93-4