Development of an electron density probe Final report, 22 Jun. 1964 - 22 Mar. 1965

Electron density probes to perform measurements in flow fields at high altitude

Microradiography of Metals and Alloys Using a Medical X-Ray Unit

There is no doubt that the microradiograph technique is of value to the metallurgist. A three-dimensional picture to supplement the photomicrographs should give a true picture of the microstructure. Microradiography can be used where etchants can not differentiate between the various components or where no etchant can be found suitable for a particular alloy

[Introduction] Cognition in the wild: exploring animal minds with observational evidence

No description supplie

Wave climate model of the Mid-Atlantic shelf and shoreline (Virginian Sea): Model development, shelf geomorphology, and preliminary results

A computerized wave climate model is developed that applies linear wave theory and shelf depth information to predict wave behavior as they pass over the continental shelf as well as the resulting wave energy distributions along the coastline. Reviewed are also the geomorphology of the Mid-Atlantic Continental Shelf, wave computations resulting from 122 wave input conditions, and a preliminary analysis of these data

Solution to the problem of the poor cyclic fatigue resistance of bulk metallic glasses

The recent development of metallic glass-matrix composites represents a particular milestone in engineering materials for structural applications owing to their remarkable combination of strength and toughness. However, metallic glasses are highly susceptible to cyclic fatigue damage, and previous attempts to solve this problem have been largely disappointing. Here, we propose and demonstrate a microstructural design strategy to overcome this limitation by matching the microstructural length scales (of the second phase) to mechanical crack-length scales. Specifically, semisolid processing is used to optimize the volume fraction, morphology, and size of second-phase dendrites to confine any initial deformation (shear banding) to the glassy regions separating dendrite arms having length scales of ≈2 μm, i.e., to less than the critical crack size for failure. Confinement of the damage to such interdendritic regions results in enhancement of fatigue lifetimes and increases the fatigue limit by an order of magnitude, making these “designed” composites as resistant to fatigue damage as high-strength steels and aluminum alloys. These design strategies can be universally applied to any other metallic glass systems

Effect of a refuge from persistent male courtship in the Drosophila laboratory environment

The Drosophila melanogaster laboratory model has been used extensively in studies of sexual conflict because during the process of courtship and mating, males impose several costs upon females (e.g., reduced fecundity). One important difference between the laboratory and the wild is that females in the laboratory lack a spatial refuge from persistent male courtship. Here, we describe two experiments that examine the potential consequences of a spatial refuge for females. In the first experiment, we examined the influence of a spatial refuge on mating rate of females, and in the second one we examined its influence on females\u27 lifetime fecundity. We found that females mated about 25% less often when a spatial refuge was available, but that the absence of a spatial refuge did not substantially increase the level of male-induced harm to females (i.e., sexual conflict). © The Author 2008. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved

How did they get here from there? Detecting changes of direction in terrestrial ranging

Efficient exploitation of large-scale space is crucial to many species of animal, but the difficulties of studying how animals decide on travel routes in natural environments have hampered scientific understanding of environmental cognition. Field experiments allow researchers to define travel goals for their subjects, but practical difficulties restrict large-scale studies. In contrast, data on natural travel patterns are abundant and easy to record, but hard to interpret without circularity and subjectivity when making inferences about when and why an animal began heading to a particular location. We present a method of determining objectively the point at which an animal’s travel path becomes directed at a location, for instance a distant feeding site, based on the statistical characteristics of its route. We evaluate this method and illustrate how it can be tailored to particular problems, using data that is (a) synthetic; (b) from baboons, where travel is from a single sleeping site in an overlapping home range, and (c) from chimpanzees, where sleeping sites are unlimited within a large territory. We suggest that this ‘change- point test’ might usefully become a routine first step in interpreting the decision- making behind animal travel under natural conditions

Modelling spatially regulated B-catenin dynamics & invasion in intestinal crypts

Experimental data (e.g., genetic lineage and cell population studies) on intestinal crypts reveal that regulatory features of crypt behavior, such as control via morphogen gradients, are remarkably well conserved among numerous organisms (e.g., from mouse and rat to human) and throughout the different regions of the small and large intestines. In this article, we construct a partial differential equation model of a single colonic crypt that describes the spatial distribution of Wnt pathway proteins along the crypt axis. The novelty of our continuum model is that it is based upon assumptions that can be directly related to processes at the cellular and subcellular scales. We use the model to predict how the distributions of Wnt pathway proteins are affected by mutations. The model is then extended to investigate how mutant cell populations can invade neighboring crypts. The model simulations suggest that cell crowding caused by increased proliferation and decreased cell loss may be sufficient for a mutant cell population to colonize a neighboring healthy crypt

Purification and Characterization of meta-Cresol Purple for Spectrophotometric Seawater pH Measurements

Spectrophotometric procedures allow rapid and precise measurements of the pH of natural waters. However, impurities in the acid–base indicators used in these analyses can significantly affect measurement accuracy. This work describes HPLC procedures for purifying one such indicator, meta-cresol purple (mCP), and reports mCP physical–chemical characteristics (thermodynamic equilibrium constants and visible-light absorbances) over a range of temperature (T) and salinity (S). Using pure mCP, seawater pH on the total hydrogen ion concentration scale (pHT) can be expressed in terms of measured mCP absorbance ratios (R = λ2A/λ1A) as follows:where −log(K2Te2) = a + (b/T) + c ln T – dT; a = −246.64209 + 0.315971S + 2.8855 × 10–4S2; b = 7229.23864 – 7.098137S – 0.057034S2; c = 44.493382 – 0.052711S; d = 0.0781344; and mCP molar absorbance ratios (ei) are expressed as e1 = −0.007762 + 4.5174 × 10–5T and e3/e2 = −0.020813 + 2.60262 × 10–4T + 1.0436 × 10–4 (S – 35). The mCP absorbances, λ1A and λ2A, used to calculate R are measured at wavelengths (λ) of 434 and 578 nm. This characterization is appropriate for 278.15 ≤ T ≤ 308.15 and 20 ≤ S ≤ 40

Development of the dry tape battery concept

High energy anode and cathode for dry tape battery - incapsulation of electrolyte - manufacturing and testing of devic