2,4-D and Mycoleptodiscus terrestris for control of Eurasian Watermilfoil

Growth chamber studies were conducted to evaluate the impact of an indigenous fungal pathogen, Mycoleptodiscus terrestris (Gerd.) Ostazeski, and the herbicide 2,4-D applied alone and in combination with one another, on the growth of a nuisance submersed plant, Eurasian watermilfoil ( Myriophyllum spicatum L.)(PDF has 6 pages.

New shield for gamma-ray spectrometry

Gamma-ray shield that can be evacuated, refilled with a clean gas, and pressurized for exclusion of airborne radioactive contaminants effectively lowers background noise. Under working conditions, repeated evacuation and filling procedures have not adversely affected the sensitivity and resolution of the crystal detector

Creep fatigue life prediction for engine hot section materials (isotropic): Fourth year progress review

As gas turbine technology continues to advance, the need for advanced life prediction methods for hot section components is becoming more and more evident. The complex local strain and temperature histories at critical locations must be accurately interpreted to account for the effects of various damage mechanisms (such as fatigue, creep, and oxidation) and their possible interactions. As part of the overall NASA HOST effort, this program is designed to investigate these fundamental damage processes, identify modeling strategies, and develop practical models which can be used to guide the early design and development of new engines and to increase the durability of existing engines

Creep fatigue life prediction for engine hot section materials (isotropic): Third year progress review

This program is designed to investigate fundamental damage processes, identify modeling strategies, and develop practical models which can be used to guide the early design and development of new engines and to increase the durability of existing engines. A review is given of the base program, completed in 1984, which included the comparison and evaluation of several popular high-temperature life prediction approaches as applied to continuously cycled isothermal specimen tests. The option program, of which one year is completed, is designed to develop models which can account for complex cycles and loadings, such as thermomechanical cycling, cumulative damage, multiaxial stress/strain rates, and environmental effects

A comparative study of nonparametric methods for pattern recognition

The applied research discussed in this report determines and compares the correct classification percentage of the nonparametric sign test, Wilcoxon's signed rank test, and K-class classifier with the performance of the Bayes classifier. The performance is determined for data which have Gaussian, Laplacian and Rayleigh probability density functions. The correct classification percentage is shown graphically for differences in modes and/or means of the probability density functions for four, eight and sixteen samples. The K-class classifier performed very well with respect to the other classifiers used. Since the K-class classifier is a nonparametric technique, it usually performed better than the Bayes classifier which assumes the data to be Gaussian even though it may not be. The K-class classifier has the advantage over the Bayes in that it works well with non-Gaussian data without having to determine the probability density function of the data. It should be noted that the data in this experiment was always unimodal

Firm Capabilities, Competition and Industrial Policies in a History-Friendly Model of the Computer Industry

In this paper, we explore some problems that industrial policy faces in industries characterized by dynamic increasing returns on the basis of a 'history friendly model' of the evolution of the computer industry. How does policy affect industry structure over the course of industry evolution? Is the timing of the intervention important? Do policy interventions have indirect and perhaps unintended consequences on different markets at different times? We focus on two sets of policies: antitrust and interventions aiming at supporting the entry of new forms in the industry. The results of our simulations show that, if strong dynamic increasing returns are operative, both through technological capabilities and through customer tendency to stick with a brand, there is little that antitrust and entry policy could have done to avert the rise of a dominant firm in mainframes. On the other hand, if the customer lock in effect had been smaller, either by chance or through policies that discouraged efforts of firms to lock in their customers, the situation might have been somewhat different. In the first place, even in the absence of antitrust or entry encouraging policies, market concentration would have been lower, albeit a dominant firm would emerge anyhow. Second, antitrust and entry encouraging policies would have been more effective in assuring that concentration would decrease. The leading firm would continue to dominate the market, but its relative power would be reduced. © Elsevier Science B.V

On the divine clockwork: the spectral gap for the correspondence limit of the Nelson diffusion generator for the atomic elliptic state

The correspondence limit of the atomic elliptic state in three dimensions is discussed in terms of Nelson's stochastic mechanics. In previous work we have shown that this approach leads to a limiting Nelson diffusion and here we discuss in detail the invariant measure for this process and show that it is concentrated on the Kepler ellipse in the plane z=0. We then show that the limiting Nelson diffusion generator has a spectral gap; thereby proving that in the infinite time limit the density for the limiting Nelson diffusion will converge to its invariant measure. We also include a summary of the Cheeger and Poincare inequalities both of which are used in our proof of the existence of the spectral gap.Comment: 30 pages, 5 figures, submitted to J. Math. Phy

Creep fatigue life prediction for engine hot section materials (ISOTROPIC)

The specific activities summarized include: verification experiments (base program); thermomechanical cycling model; multiaxial stress state model; cumulative loading model; screening of potential environmental and protective coating models; and environmental attack model

Quantum geometry from 2+1 AdS quantum gravity on the torus

Wilson observables for 2+1 quantum gravity with negative cosmological constant, when the spatial manifold is a torus, exhibit several novel features: signed area phases relate the observables assigned to homotopic loops, and their commutators describe loop intersections, with properties that are not yet fully understood. We describe progress in our study of this bracket, which can be interpreted as a q-deformed Goldman bracket, and provide a geometrical interpretation in terms of a quantum version of Pick's formula for the area of a polygon with integer vertices.Comment: 19 pages, 11 figures, revised with more explanations, improved figures and extra figures. To appear GER

Strain engineered graphene using a nanostructured substrate: I Deformations

Using atomistic simulations we investigate the morphological properties of graphene deposited on top of a nanostructured substrate. Sinusoidally corrugated surfaces, steps, elongated trenches, one dimensional and cubic barriers, spherical bubbles, Gaussian bump and Gaussian depression are considered as support structures for graphene. The graphene-substrate interaction is governed by van der Waals forces and the profile of the graphene layer is determined by minimizing the energy using molecular dynamics simulations. Based on the obtained optimum configurations, we found that: (i) for graphene placed over sinusoidally corrugated substrates with corrugation wave lengths longer than 2\,nm, the graphene sheet follows the substrate pattern while for supported graphene it is always suspended across the peaks of the substrate, (ii) the conformation of graphene to the substrate topography is enhanced when increasing the energy parameter in the van der Waals model, (iii) the adhesion of graphene into the trenches depends on the width of the trench and on graphene's orientation, i.e. in contrast to a small width (3 nm) nanoribbon with armchair edges, the one with zig-zag edges follows the substrate profile, (iv) atomic scale graphene follows a Gaussian bump substrate but not the substrate with a Gaussian depression, and (v) the adhesion energy due to van der Waals interaction varies in the range [0.1-0.4] J/m^2.Comment: 12 pages and 16 figures, To appear in Phys. Rev.