The Differential Form Method for Finding Symmetries

This article reviews the use of differential forms and Lie derivatives to find symmetries of differential equations, as originally presented by Harrison and Estabrook, J. Math. Phys., 12 (1971), 653. An outline of the method is given, followed by examples and references to recent papers using the method.Comment: Published in SIGMA (Symmetry, Integrability and Geometry: Methods and Applications) at http://www.emis.de/journals/SIGMA

A Method for Constructing a Lax Pair for the Ernst Equation

A systematic construction of a Lax pair and an infinite set of conservation laws for the Ernst equation is described. The matrix form of this equation is rewritten as a differential ideal of gl(2,R)-valued differential forms, and its symmetry condition is expressed as an exterior equation which is linear in the symmetry characteristic and has the form of a conservation law. By means of a recursive process, an infinite collection of such laws is then obtained, and the conserved "charges" are used to derive a linear exterior equation whose components constitute a Lax pair.Comment: 12 pages; minor correction

Reducing Crop Production Cost

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Most Asked Agronomic Questions

Exact date of bulletin unknown.PDF pages: 4

757 Path Loss Measurements

Path Loss Measurements were obtained on three (3) GPS equipped 757 aircraft. Systems measured were Marker Beacon, LOC, VOR, VHF (3), Glide Slope, ATC (2), DME (2), TCAS, and GPS. This data will provide the basis for assessing the EMI (Electromagnetic Interference) safety margins of comm/nav (communication and navigation) systems to portable electronic device emissions. These Portable Electronic Devices (PEDs) include all devices operated in or around the aircraft by crews, passengers, servicing personnel, as well as the general public in the airport terminals. EMI assessment capability is an important step in determining if one system-wide PED EMI policy is appropriate. This data may also be used comparatively with theoretical analysis and computer modeling data sponsored by NASA Langley Research Center and others

The Dark Internet: Without Darkness There is No Light

What is the Bright Internet? One way to define ‘bright’ is to explore darkness. The purpose of this panel is to clarify what is meant by the ‘Bright Internet’ by presenting the contrast of the ‘Dark Internet’ and the dark web. The panelists, all of whom have expertise in the dark side of Internet and information technology use, will discuss deception, fraud, phishing, terrorism, and the dark web

Immunity to self co-generates regulatory T cells

Immune responses to self are kept in check by tolerance mechanisms, including suppression by regulatory T cells (Tregs). The defective generation of Tregs specific for self-antigens may lead to autoimmune disease. We identified a novel population of human CD4^+^ Tregs, characterized by high surface expression of CD52, which is co-generated in response to autoantigen. Blood CD4^+^CD52^hi^ T cells were generated preferentially in response to low-dose autoantigen and suppressed proliferation and interferon-[gamma] production by other T cells. Depletion of resting CD4^+^CD52^hi^ T cells enhanced the T-cell response to autoantigen. CD4^+^CD52^hi^ Tregs were neither derived from nor distinguished by markers of conventional resting CD4^+^CD25^+^ Tregs. In response to the pancreatic islet autoantigens glutamic acid decarboxylase, the generation of CD4^+^CD52^hi^ Tregs was impaired in individuals with and at-risk for type 1 diabetes, compared to healthy controls and individuals with type 2 diabetes. CD4^+^CD52^hi^ Tregs co-generated to self-antigen may therefore contribute to immune homeostasis and protect against autoimmune disease

Comment on "Tectonic Rotations in Extensional Regimes and Their Paleomagnetic Consequences for Ocean Basalts" by Kenneth L. Verosub and Eldridge M. Moores

One of the more intriguing results from palcomagnetic studies of Deep Sea Drilling Project (DSDP) basalts is that a surprisingly large number of samples have inclinations that deviate significantly from expected values. Vetosub and Moores [1981] sought to account for what appear to be systematic departures of mean inclination at several DSDP basement sites in terms of tectonic rotations along listtic normal faults. Such rotations, about horizontal axes perpendicular to the extension direction and typically amounting to 30ø-50 ø but as large as 70 ø to 90 ø, were suggested to be characteristic of an extensional tectonic regime such as near an ocean spreading ridge system. There is a clear implication that large tectonic rotations are a characteristic process associated with ocean crust formation

Electrically conductive, optically transparent polymer/carbon nanotube composites and process for preparation thereof

The present invention is directed to the effective dispersion of carbon nanotubes (CNTs) into polymer matrices. The nanocomposites are prepared using polymer matrices and exhibit a unique combination of properties, most notably, high retention of optical transparency in the visible range (i.e., 400 800 nm), electrical conductivity, and high thermal stability. By appropriate selection of the matrix resin, additional properties such as vacuum ultraviolet radiation resistance, atomic oxygen resistance, high glass transition (T.sub.g) temperatures, and excellent toughness can be attained. The resulting nanocomposites can be used to fabricate or formulate a variety of articles such as coatings on a variety of substrates, films, foams, fibers, threads, adhesives and fiber coated prepreg. The properties of the nanocomposites can be adjusted by selection of the polymer matrix and CNT to fabricate articles that possess high optical transparency and antistatic behavior