Apparatus for igniting solid propellants Patent

Solid propellant ignition with hypergolic fluid injected to predetermined portions of propellan

Method of igniting solid propellants Patent

Method for igniting solid propellant rocket motors by injecting hypergolic fluid

Disruptive Innovations and Disruptive Assurance: Assuring Machine Learning and Autonomy

Autonomous and machine learning-based systems are disruptive innovations and thus require a corresponding disruptive assurance strategy. We offer an overview of a framework based on claims, arguments, and evidence aimed at addressing these systems and use it to identify specific gaps, challenges, and potential solutions

The Physicist's Guide to the Orchestra

An experimental study of strings, woodwinds (organ pipe, flute, clarinet, saxophone and recorder), and the voice was undertaken to illustrate the basic principles of sound production in music instruments. The setup used is simple and consists of common laboratory equipment. Although the canonical examples (standing wave on a string, in an open and closed pipe) are easily reproduced, they fail to explain the majority of the measurements. The reasons for these deviations are outlined and discussed.Comment: 11 pages, 10 figures (jpg files). Submitted to European Journal of Physic

Development and Use of Color Standards for Egg Yolks

Abstract FOR SOME YEARS poultry scientists have been engaged in nutrition studies on the effects of various grains fed to laying birds. Some of these studies have been concerned with the effect of grain or combinations of grains in determining yolk color. The desired yolk color for home use varies with the geographical location and customs of the people, but in general a fairly light color is preferred. On the other hand users of yolks such as noodle manufacturers and cake bakers pay premium prices for dark colored yolk. It is therefore more profitable for the egg producer if he accurately maintains the yolk color within the desired range for his particular market. Since verbal color descriptions are ambiguous it is necessary to have standards for egg yolk colors in recording and communicating the results of poultry diet research. The only color chart available in Canada was one which had been

Atomic Absorption as an Index of the Silver Concentration in Precipitation, Silver Iodide Plume Studies, Part 1

The Perkin Elmbver Model 303, equipped with the DCR-1, digital concentration readout, was evaluated as to its ability to provide an index of silver concentration in water solutions, without concentrating in any manner. The procedures, principal settings, and adjustments which must be observed are described. This instrument can detect the difference between concentrations of 10-15 and 10-12 gm/ml. However, as the concentration of silver decreases the experimental error increases to a point at which the error becomes greater than the differences in readout due to differences in silver concentration

Transverse Magnetoresistance of GaAs/AlGaAs Heterojunctions in the Presence of Parallel Magnetic Fields

We have calculated the resistivity of a GaAs\slash AlGaAs heterojunction in the presence of both an in--plane magnetic field and a weak perpendicular component using a semiclassical Boltzmann transport theory. These calculations take into account fully the distortion of the Fermi contour which is induced by the parallel magnetic field. The scattering of electrons is assumed to be due to remote ionized impurities. A positive magnetoresistance is found as a function of the perpendicular component, in good qualitative agreement with experimental observations. The main source of this effect is the strong variation of the electronic scattering rate around the Fermi contour which is associated with the variation in the mean distance of the electronic states from the remote impurities. The magnitude of the positive magnetoresistance is strongly correlated with the residual acceptor impurity density in the GaAs layer. The carrier lifetime anisotropy also leads to an observable anisotropy in the resistivity with respect to the angle between the current and the direction of the in--plane magnetic field.Comment: uuencoded file containing a 26 page RevTex file and 14 postscript figures. Submitted to Phys. Rev.

A genome-wide investigation of the worldwide invader Sargassum muticum shows high success albeit (almost) no genetic diversity

Twenty years of genetic studies of marine invaders have shown that successful invaders are often characterized by native and introduced populations displaying similar levels of genetic diversity. This pattern is presumably due to high propagule pressure and repeated introductions. The opposite pattern is reported in this study of the brown seaweed, Sargassum muticum, an emblematic species for circumglobal invasions. Albeit demonstrating polymorphism in the native range, microsatellites failed to detect any genetic variation over 1,269 individuals sampled from 46 locations over the Pacific-Atlantic introduction range. Single-nucleotide polymorphisms (SNPs) obtained from ddRAD sequencing revealed some genetic variation, but confirmed severe founder events in both the Pacific and Atlantic introduction ranges. Our study thus exemplifies the need for extreme caution in interpreting neutral genetic diversity as a proxy for invasive potential. Our results confirm a previously hypothesized transoceanic secondary introduction from NE Pacific to Europe. However, the SNP panel unexpectedly revealed two additional distinct genetic origins of introductions. Also, conversely to scenarios based on historical records, southern rather than northern NE Pacific populations could have seeded most of the European populations. Finally, the most recently introduced populations showed the lowest selfing rates, suggesting higher levels of recombination might be beneficial at the early stage of the introduction process (i.e., facilitating evolutionary novelties), whereas uniparental reproduction might be favored later in sustainably established populations (i.e., sustaining local adaptation).Agence Nationale de la Recherche - ANR-10-BTBR-04; European Regional Development Fund; Fundacao para a Ciencia e a Tecnologia - SFRH/BPD/107878/2015, UID/Multi/04326/2016, UID/Multi/04326/2019; Brittany Region;info:eu-repo/semantics/publishedVersio

Quantized charge pumping through a quantum dot by surface acoustic waves

We present a realization of quantized charge pumping. A lateral quantum dot is defined by metallic split gates in a GaAs/AlGaAs heterostructure. A surface acoustic wave whose wavelength is twice the dot length is used to pump single electrons through the dot at a frequency f=3GHz. The pumped current shows a regular pattern of quantization at values I=nef over a range of gate voltage and wave amplitude settings. The observed values of n, the number of electrons transported per wave cycle, are determined by the number of electronic states in the quantum dot brought into resonance with the fermi level of the electron reservoirs during the pumping cycle.Comment: 8 page