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Local S.A.R. chapter holds first officer installation (open access)

Local S.A.R. chapter holds first officer installation

Article in the Hamilton Harold-News containing information about the TXSSAR Leon River Valley Chapter's first officer installation in on January 8, 1991.
Date: January 19, 1991
Creator: unknown
System: The UNT Digital Library
A method for characterizing volcanic ash (open access)

A method for characterizing volcanic ash

The development of an automated program for characterization of particles using a scanning electron microscope (SEM) with an energy dispersive X-ray detector (EDS) has greatly reduced the time required for analysis of particulate samples. The SEM system provides a digital representation of all particles scanned such that further measurement of the size, shape, and area are a product of image processing. The EDS and associated software provides information as to the particles' chemical composition. The data obtained from the SEM by this method are reduced by computer to obtain distribution graphs for size, density, shape, and mineralogy. These SEM results have been tested by comparisons with results obtained by traditional optical microscopy, which supports the results and provide details concerning crystallinity and glass content. This method was applied to the ash that damaged the engines from the KLM 747 flight of December 15, 1989 while encountering the ash cloud from Redoubt Volcano. The sample was collected from the pitot-static system and had not been exposed to any engine parts that might have changed its characteristics. The sample analysis presented here demonstrates the capabilities and information obtainable from out automated SEM technique. 5 refs., 7 figs., 3 tabs.
Date: January 19, 1991
Creator: Bayhurst, Gregory K.; Wohletz, Kenneth H. & Mason, Allen S.
System: The UNT Digital Library
Weak interactions and presupernova evolution (open access)

Weak interactions and presupernova evolution

The role of weak interactions, particularly electron capture and {beta}{sup {minus}} decay, in presupernova evolution is discussed. The present uncertainty in these rates is examined and the possibility of improving the situation is addressed. 12 refs., 4 figs.
Date: February 19, 1991
Creator: Aufderheide, M.B. (Lawrence Livermore National Lab., CA (USA) State Univ. of New York (USA). Dept. of Physics)
System: The UNT Digital Library
epsilon. prime /. epsilon. : Review and recent progress (open access)

epsilon. prime /. epsilon. : Review and recent progress

The evolution of the theoretical perspective on {epsilon}{prime}/{epsilon} is reviewed. The introduction of the Z{sup O} penguin and the effects of high M{sub t} are discussed, in particular the possibility for {epsilon}{prime}/{epsilon} to be identically zero. Recent calculations of {epsilon}{prime}/{epsilon} based on current estimates and bounds on the input parameters are presented. 41 refs., 13 figs.
Date: April 19, 1991
Creator: Franzini, P. J.
System: The UNT Digital Library
Optical design of a high power fiber optic coupler (open access)

Optical design of a high power fiber optic coupler

Fiber optic beam delivery systems are replacing conventional mirror delivery systems for many reasons (e.g., system flexibility and redundancy, stability, and ease of alignment). Commercial products are available that use of fiber optic delivery for laser surgery and materials processing. Also, pump light of dye lasers can be delivered by optical fibers. Many laser wavelengths have been transported via optical fibers; high power delivery has been reported for argon, Nd:YAG, and excimer. We have been developing fiber optic beam delivery systems for copper vapor laser light; many of the fundamental properties of these systems are applicable to other high power delivery applications. A key element of fiber optic beam delivery systems is the coupling of laser light into the optical fiber. For our application this optical coupler must be robust to a range of operating parameters and laser characteristics. We have access to a high power copper vapor laser beam that is generated by a master oscillator/power amplifier (MOPA) chain comprised of three amplifiers. The light has a pulse width of 40--50 nsec with a repetition rate of about 4 kHz. The average power (nominal) to be injected into a fiber is 200 W. (We will refer to average power …
Date: June 19, 1991
Creator: English, R. Edward, Jr.; Halpin, John M.; House, F. Allen & Paris, Robert D.
System: The UNT Digital Library
Selective generation and extraction of low emittance electrons from plasmas: A new concept for E-beam cathodes (open access)

Selective generation and extraction of low emittance electrons from plasmas: A new concept for E-beam cathodes

It is shown that hollow cathode discharges can operate in a mode characterized by a two-component electron energy distribution: bulk electrons with a thermal distribution with a temperature of a few electron volts, and a component of fast electrons with an energy of about 30 eV and a thermal spread of about 0.1 eV. Measurements of both parallel and perpendicular energy spreads confirm the existence of fast, low energy spread electrons. Selective extraction of these electrons can form the basis of a high current, high brightness electron gun which could be well suited for EBIS applications. 8 refs., 4 figs., 1 tab.
Date: September 19, 1991
Creator: Hershcovitch, A.
System: The UNT Digital Library
Buckminsterfullerene, C₆₀: Improved Synthesis, Electron Microscopy, Electron States, Anions and Related Aspects (open access)

Buckminsterfullerene, C₆₀: Improved Synthesis, Electron Microscopy, Electron States, Anions and Related Aspects

This article describes the synthesis and characterization of C₆₀, by means of electron microscopy, electron states, cyclic voltammetry and other techniques.
Date: August 19, 1991
Creator: Pradeep, T.; D'Souza, Francis; Subbanna, G.N.; Krishnan, V. & Rao, C.N.R.
System: The UNT Digital Library
Yucca Mountain Project total-system performance assessment preliminary analyses: Overview; Draft (open access)

Yucca Mountain Project total-system performance assessment preliminary analyses: Overview; Draft

Sandia National Laboratories and Pacific Northwest Laboratory have produced a coordinated initial total-system performance assessment analysis for the potential repository at Yucca Mountain. Analyses included radionuclide transport via groundwater and gas flow, human intrusion, tectonism, and basaltic igneous intrusion. Both abstracted and detailed calculations were used for the analyses. Probabilistic release distributions were calculated for the individual components, and a combined distribution for the overall behavior of the system was constructed. Results from the analyses using abstracted models indicate that this method produces reasonable outcomes based on our current understanding of the site.
Date: December 19, 1991
Creator: Barnard, R. W. & Dockery, H. A.
System: The UNT Digital Library
DNA sequencing conference, 2 (open access)

DNA sequencing conference, 2

This conference focused on DNA sequencing, genetic linkage mapping, physical mapping, informatics and bioethics. Several were used to study this sequencing and mapping. This article also discusses computer hardware and software aiding in the mapping of genes.
Date: June 19, 1991
Creator: Cook-Deegan, R. M.; Venter, J. C.; Gilbert, W.; Mulligan, J. & Mansfield, B. K.
System: The UNT Digital Library