17,205 research outputs found
Group algebras and enveloping algebras with nonmatrix and semigroup identities
Let K be a field of positive characteristic p, let R be either a group
algebra K[G] or a restricted enveloping algebra u(L), and let I be the
augmentation ideal of R. We first characterize those R for which I satisfies a
polynomial identity not satisfied by the algebra of all 2-by-2 matrices over K.
Then we examine those R for which I satisfies a semigroup identity (that is, a
polynomial identity which can be written as the difference of two monomials).Comment: 11 pages. Written in LaTeX2
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Suspension Design, Modeling, and Testing of a Thermo-Acoustic-Driven Linear Alternator
The Score-Stove™ generates electricity from a wood-burning cooking stove using a thermo-acoustic engine (TAE) that converts heat to sound through a linear alternator (LA). This paper introduces a prototype hemitoroidal suspension that was refined into a segmented trapezoidal shape that gave a higher cyclic life for the LA and includes a critical evaluation that compares a theoretical analysis with experimental results. The results show an improvement from the 40% efficiency of a standard loudspeaker used in reverse as an LA to 70–80% efficiency with the new suspension and a double Halbach array magnetic topology
An Iron Fulgurite from Nebraska
From the time of the ancients man has been impressed with the force of lightning and its effect on the rocks at the surface of the earth. It was Saussure in 1786 who first wrote a scientific account of a true fulgurite, and a wealth of literature has been written about the subject since this time. Many unusual fulgurites have been described, some of which may not truly be the result of lightning. The iron fulgurite is a strange conical object about 3 inches high composed mainly of tiny spheres and filaments of metallic iron intermixed with a small amount of nonmetallic soil minerals. It is believed that a bold of lightning hit an iron object lying in a farmyard, instantly melted it, and somehow sprayed the molten iron into the soil where it solidified. The power needed by a lightning bold to instantly melt a mass of iron this size was computed at 2050 x 106 watts
Evaluation of the SPAR thermal analyzer on the CYBER-203 computer
The use of the CYBER 203 vector computer for thermal analysis is investigated. Strengths of the CYBER 203 include the ability to perform, in vector mode using a 64 bit word, 50 million floating point operations per second (MFLOPS) for addition and subtraction, 25 MFLOPS for multiplication and 12.5 MFLOPS for division. The speed of scalar operation is comparable to that of a CDC 7600 and is some 2 to 3 times faster than Langley's CYBER 175s. The CYBER 203 has 1,048,576 64-bit words of real memory with an 80 nanosecond (nsec) access time. Memory is bit addressable and provides single error correction, double error detection (SECDED) capability. The virtual memory capability handles data in either 512 or 65,536 word pages. The machine has 256 registers with a 40 nsec access time. The weaknesses of the CYBER 203 include the amount of vector operation overhead and some data storage limitations. In vector operations there is a considerable amount of time before a single result is produced so that vector calculation speed is slower than scalar operation for short vectors
A simplex-like search method for bi-objective optimization
We describe a new algorithm for bi-objective optimization, similar to the Nelder Mead simplex
algorithm, widely used for single objective optimization. For diferentiable bi-objective functions on
a continuous search space, internal Pareto optima occur where the two gradient vectors point in
opposite directions. So such optima may be located by minimizing the cosine of the angle between
these vectors. This requires a complex rather than a simplex, so we term the technique the \cosine
seeking complex". An extra beneft of this approach is that a successful search identifes the direction
of the effcient curve of Pareto points, expediting further searches. Results are presented for some
standard test functions. The method presented is quite complicated and space considerations here
preclude complete details. We hope to publish a fuller description in another place
A note on leapfrogging vortex rings
In this paper we provide examples, by numerical simulation using the Navier-Stokes equations for axisymmetric laminar flow, of the 'leapfrogging' motion of two, initially identical, vortex rings which share a common axis of symmetry. We show that the number of clear passes that each ring makes through the other increases with Reynolds number, and that as long as the configuration remains stable the two rings ultimately merge to form a single vortex ring
‘But by blood no wolf am I’: Language and Agency, Instinct and Essence – Transcending Antinomies in Maggie Stiefvater’s Shiver trilogy
Young Adult dark romance is often more questioning than its adult counterpart; different, less constraining commercial imperatives are perhaps at work, or readers’ expectations less fixed. This chapter will show how, woven into a sensitive coming-of-age narrative of first love and familial problems, Maggie Stiefvater’s Shiver trilogy performs a far more sophisticated interrogation of the boundaries of animality and humanity than other such fictions, highlighting the centrality of language and its relationship to agency. The hero, Sam’s, struggle with his lupine nature becomes an existentialist refusal to be defined by nature; other characters are tempted instead to yield to a fatalistic surrender of will. The books are tantalisingly ambivalent about the appeal of the instinctual and the borderline between an embodied humanity and the animal, particularly as manifested in the love affair of the teenage protagonists. For Marcuse, the surplus-repression of the proximity senses (smell, taste) enforces the isolation of individuals in civilisation. Stiefvater continually emphasises the sense of smell both as a trigger to sexual attraction and as an aspect of the pack sociality and sense of belonging of the wolves. Through such devices, she concretely renders the nearness of Grace and Sam (her young lovers) to wolfhood. This is contrasted with her exploration of human subjectivity through language, particularly in the perceptive depiction of silences and miscommunications and her hero’s absorption in books and poetry
Short-Chained Oligo(Ethylene Oxide)-Functionalized Gold Nanoparticles: Realization Of Significant Protein Resistance
Protein corona formed on nanomaterial surfaces play an important role in the bioavailability and cellular uptake of nanomaterials. Modification of surfaces with oligoethylene glycols (OEG) are a common way to improve the resistivity of nanomaterials to protein adsorption. Short-chain ethylene oxide (EO) oligomers have been shown to improve the protein resistance of planar Au surfaces. We describe the application of these EO oligomers for improved protein resistance of 30 nm spherical gold nanoparticles (AuNPs). Functionalized AuNPs were characterized using UV-Vis spectroscopy, dynamic light scattering (DLS), and zeta potential measurements. Capillary electrophoresis (CE) was used for separation and quantitation of AuNPs and AuNP-protein mixtures. Specifically, nonequilibrium capillary electrophoresis of equilibrium mixtures (NECEEM) was employed for the determination of equilibrium and rate constants for binding between citrate-stabilized AuNPs and two model proteins, lysozyme and fibrinogen. Semi-quantitative CE analysis was carried out for mixtures of EO-functionalized AuNPs and proteins, and results demonstrated a 2.5-fold to 10-fold increase in protein binding resistance to lysozyme depending on the AuNP surface functionalization and a 15-fold increase in protein binding resistance to fibrinogen for both EO oligomers examined in this study
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