8,442 research outputs found
Solar neutrinos and the influence of radiative opacities on solar models
Use of new radiative opacities based on the hot Thomas-Fermi model of the atom yields a predicted solar neutrino flux which is still considerably larger than the flux observed in Davis's Cl-37 experiment
Investigation of semiconductor clad optical waveguides
A variety of techniques have been proposed for fabricating integrated optical devices using semiconductors, lithium niobate, and glasses as waveguides and substrates. The use of glass waveguides and their interaction with thin semiconductor cladding layers was studied. Though the interactions of these multilayer waveguide structures have been analyzed here using glass, they may be applicable to other types of materials as well. The primary reason for using glass is that it provides a simple, inexpensive way to construct waveguides and devices
The Rachel Carson Letters and the Making of Silent Spring
Environment, conservation, green, and kindred movements look back to Rachel Carson’s 1962 book Silent Spring as a milestone. The impact of the book, including on government, industry, and civil society, was immediate and substantial, and has been extensively described; however, the provenance of the book has been less thoroughly examined. Using Carson’s personal correspondence, this paper reveals that the primary source for Carson’s book was the extensive evidence and contacts compiled by two biodynamic farmers, Marjorie Spock and Mary T. Richards, of Long Island, New York. Their evidence was compiled for a suite of legal actions (1957-1960) against the U.S. Government and that contested the aerial spraying of dichlorodiphenyltrichloroethane (DDT). During Rudolf Steiner’s lifetime, Spock and Richards both studied at Steiner’s Goetheanum, the headquarters of Anthroposophy, located in Dornach, Switzerland. Spock and Richards were prominent U.S. anthroposophists, and established a biodynamic farm under the tutelage of the leading biodynamics exponent of the time, Dr. Ehrenfried Pfeiffer. When their property was under threat from a government program of DDT spraying, they brought their case, eventually lost it, in the process spent US$100,000, and compiled the evidence that they then shared with Carson, who used it, and their extensive contacts and the trial transcripts, as the primary input for Silent Spring. Carson attributed to Spock, Richards, and Pfeiffer, no credit whatsoever in her book. As a consequence, the organics movement has not received the recognition, that is its due, as the primary impulse for Silent Spring, and it is, itself, unaware of this provenance
Mach 4 free-jet tunnel starting experiments for a hypersonic research engine model causing high blockage
Tests of a full scale hypersonic research engine (HRE) were conducted in the hypersonic tunnel facility at Mach numbers of 5, 6, and 7. Since the HRE would cause a rather high blockage (48.83 percent of the nozzle area), subscale tests were conducted in various available small wind tunnels prior to the full scale tests to study the effects of model blockage on tunnel starting. The results of the Mach 4 subscale tests which utilized a model system at 0.0952 scale which simulated the HRE in the test section of the tunnel are presented. A satisfactory tunnel starting could not be achieved by varying the free jet length or diffuser size nor by inserting the model into the test stream after tunnel starting. However, the installation of a shroud around the HRE model allowed the tunnel to start with the model preset in the tunnel at a tunnel stagnation pressure to atmospheric exit pressure ratio of 13.4. The simulation of the discharge of instrumentation cooling water and the addition of test hardware at the aft end of the HRE model did not have a significant effect on the tunnel starting
Atomic and Molecular Opacities for Brown Dwarf and Giant Planet Atmospheres
We present a comprehensive description of the theory and practice of opacity
calculations from the infrared to the ultraviolet needed to generate models of
the atmospheres of brown dwarfs and extrasolar giant planets. Methods for using
existing line lists and spectroscopic databases in disparate formats are
presented and plots of the resulting absorptive opacities versus wavelength for
the most important molecules and atoms at representative temperature/pressure
points are provided. Electronic, ro-vibrational, bound-free, bound-bound,
free-free, and collision-induced transitions and monochromatic opacities are
derived, discussed, and analyzed. The species addressed include the alkali
metals, iron, heavy metal oxides, metal hydrides, , , , ,
, , , and representative grains. [Abridged]Comment: 28 pages of text, plus 22 figures, accepted to the Astrophysical
Journal Supplement Series, replaced with more compact emulateapj versio
Putting Ethics on the Agenda for Real Estate Agents
This article uses sociological role theory to
help understand ethical challenges faced by Norwegian
real estate agents. The article begins with an introductory
case, and then briefly examines the strengths and limitations
of using legal definitions and rules for understanding
real estate agency and real estate agent ethics. It goes on to
argue that the ethical challenges of real estate agency can
be described and understood as a system of conflicting
roles with associated rights and duties, in particular sales
agent, intermediary and adviser sub-roles. The arguments
are developed using exploratory findings from a survey of
Norwegian real estate agents and from several focus
groups. The article then suggests the use of various
intranet tools as a kind of action research aimed at putting
ethics on the real estate agents’ agenda, working to
develop a collective conscience and collective selfcriticism
among the agents, and, in doing so, building
bridges between academic research and the practical
working world of the agents
Quantum Fluctuations around the Electroweak Sphaleron
We present an analysis of the quantum fluctuations around the electroweak
sphaleron and calculate the associated determinant which gives the 1--loop
correction to the sphaleron transition rate. The calculation differs in various
technical aspects from a previous analysis by Carson et al. so that it can be
considered as independent. The numerical results differ also -- by several
orders of magnitude -- from those of this previous analysis; we find that the
sphaleron transition rate is much less suppressed than found previously.Comment: DO-TH-93/19 39 pages, 5 figures (available on request as Postscript
files or via Fax or mail), LaTeX, no macros neede
Ultrareliable, fault-tolerant control systems: A conceptual description
An Ultrareliable, Fault-Tolerant, Control-System (UFTCS) concept is described using a systems design philosophy which allows development of system structures containing virtually no common elements. Common elements limit achievable system reliability and can cause catastrophic loss of fault-tolerant system function. The UFTCS concept provides the means for removing common system elements by permitting the elements of the system to operate as independent, uncoupled entities. Multiple versions of the application program are run on dissimilar hardware. Fault tolerance is achieved through the use of static redundancy management
Relativistic Thermal Bremsstrahlung Gaunt Factor for the Intracluster Plasma
We calculate the relativistic thermal bremsstrahlung Gaunt factor for the
high-temperature plasma which exists in clusters of galaxies. We calculate the
Gaunt factor by employing the Bethe-Heitler cross section corrected by the
Elwert factor. We also calculate the Gaunt factor by using the
Coulomb-distorted wave functions for nonrelativistic electrons following the
method of Karzas and Latter. By comparing the Gaunt factors calculated by these
two different methods, we carefully assess the accuracy of the calculation. We
present the numerical results in the form of tables.Comment: 15 pages, 4 figures and 2 tables, submitted to Astrophysical Journa
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