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  • 1
    Electronic Resource
    Electronic Resource
    Optimization and control of a small angle ion source using an adaptive neural network controller (invited) : Proceedings of 5th international conference on ion sources (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 1411-1415 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This project developed an automated controller based on an artificial neural network and evaluated its applicability in a real-time environment. This capability was developed within the context of a small angle negative ion source on the Discharge Test Stand at Los Alamos. The controller processes information obtained from the beam current wave form, developing a figure of merit (fom) to determine the ion source operating conditions. The fom is composed of the magnitude of the beam current, the stability of operation, and the quietness of the beam. Using no knowledge of operating conditions, the controller begins by making of rough scan of the four-dimensional operating surface. This surface uses as independent variables the anode and cathode temperatures, the hydrogen flow rate, and the arc voltage. The dependent variable is the fom described above. Once the rough approximation of the surface has been determined, the network formulates a model from which it determines the best operating point. The controller takes the ion source to that operating point for a reality check. As real data is fed in, the model of the operating surface is updated until the neural network's model agrees with reality. The controller then uses a gradient ascent method to optimize the operation of the ion source. Initial tests of the controller indicate that it is remarkably capable. It has optimized the operation of the ion source on six different occasions bringing the beam to excellent quality and stability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144978
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  • 2
    Electronic Resource
    Electronic Resource
    Maintaining soil fertility under increasing land use pressure in the Middle Mountains of Nepal (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Soil use and management 10 (1994), S. 0 
    Details
    ISSN: 1475-2743
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. Nepal is facing a serious problem of being unable to maintain soil fertility in agriculture and forestry. Land use practices initiated over the past 10–15 years have resulted in insufficient nutrient inputs, while biomass use and production have increased. Changes in forest soil fertility have resulted from intensive use of forest biomass for animal feed and collection of forest litter for use in agriculture. The agricultural fertility changes have resulted from intensifying annual crop rotations from 1.5 to 2.5 crops and insufficient inputs. The removal of biomass from the forest has curtailed the natural organic cycle by virtually eliminating nutrient inputs.The soils are very acidic and have little C, N, P and exchangeable bases, but have large amounts of active iron. Basic nutrients are not sustained in agriculture and differences in inputs and management between irrigated and rainfed agricultural systems are becoming visible. Irrigated fields show the largest cation content because of input from irrigation water. Rainfed agricultural sites, which receive the most nutrients (fertilizers and manure), have the highest pH values and C and N contents. All soil fertility conditions are marginal and put into question the long-term sustainability of current levels of production. Alterations in the cropping intensity are needed and the introduction of nitrogen fixing trees and crops seems to be the most viable option towards sustainability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1475-2743.1994.tb00474.x
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  • 3
    Electronic Resource
    Electronic Resource
    Magnetic viscosity, fluctuation fields, and activation energies (invited) : The 6th joint magnetism and magnetic materials (MMM)−intermag conference (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 6386-6390 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Time dependence of magnetization in ferromagnetic materials was first described towards the end of the 19th century. Subsequently, two types of mechanisms responsible for time dependent behavior were identified and became known as "diffusion'' and "fluctuation'' after-effect or viscosity. The former depends on thermally induced motion of impurity atoms. The latter is a consequence of thermal activation of irreversible domain processes such as domain-wall motion and the nucleation of domains of reverse magnetization. Fluctuation viscosity affects, to a greater or smaller extent, all magnetic materials subject to hysteresis. In the late 1940s descriptions of magnetic viscosity in terms of fluctuation fields (Néel) and activation energy distributions (Street and Woolley) were developed. The two approaches will be described. An analysis of the time dependent phenomena exhibited by magneto-optical films will be presented as a simple example of the application of activation energy modeling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358275
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  • 4
    Electronic Resource
    Electronic Resource
    Observation of near-band-gap luminescence from boron nitride films (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 1251-1253 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report results from cathodoluminescence spectroscopy of boron nitride films grown on Si(100) substrates by ion-source-assisted magnetron sputtering of a hexagonal BN target. Three main peaks are observed in the near-band-gap region for hexagonal boron nitride films at energies of 4.90, 5.31, and 5.50 eV. We also report deep-level emission spectra of predominantly cubic boron nitride films which are correlated with sample growth conditions. In particular we show that the emission intensity, position, and linewidth are strongly dependent on the substrate bias voltage used during sample growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.112086
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  • 5
    Electronic Resource
    Electronic Resource
    Concentrations of Volatile Organic Compounds in Indoor Air – A Review (1994)
    Oxford, UK : Munksgaard International Publishers
    Indoor air 4 (1994), S. 0 
    Details
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: A review is presented of investigations of volatile organic compound (VOC) concentrations in indoor air of buildings of different classifications (dwellings, offices, schools, hospitals) and categories (established, new and complaint buildings). Measured concentrations obtained from the published literature and from research in progress overseas were pooled so that VOC concentration profiles could be derived for each building classification/category. Mean concentrations of individual compounds in established buildings were found to be generally below 50 μg/m3, with most below 5 μg/m3. Concentrations in new buildings were much greater, often by an order of magnitude or more, and appeared to arise from construction materials and building contents. The nature of these sources and approaches to reduce indoor air concentrations by limiting source VOC emissions is discussed. Total VOC (TVOC) concentrations were substantially higher than concentrations of any individual VOCs in all situations, reflecting the large number of compounds present, but interpretation of such measurements was limited by the lack of a common definition for TVOC relevant to occupant exposure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0668.1994.t01-2-00007.x
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  • 6
    Electronic Resource
    Electronic Resource
    Do the penicillin antibiotics interact with digoxin? (1994)
    Springer
    European journal of clinical pharmacology 46 (1994), S. 479-480 
    Details
    ISSN: 1432-1041
    Keywords: Digoxon ; Amoxycillin ; Flucloxacillin ; penicillin V penicillin antibiotics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00191916
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  • 7
    Electronic Resource
    Electronic Resource
    Feeding, growth and bioluminescence of the heterotrophic dinoflagellate Protoperidinium huberi (1994)
    Springer
    Marine biology 121 (1994), S. 373-380 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Feeding, growth and bioluminescence of the thecate heterotrophic dinoflagellate Protoperidinium huberi were measured as a function of food concentration for laboratory cultures grown on the diatom Ditylum brightwellii. Ingestion of food increased with food concentration. Maximum ingestion rates were measured at food concentrations of ∼600 μg C l-1 and were ∼0.7 μg C individual-1 h-1 (1.8 D. brightwelli cells individual-1 h-1). Clearance rates decreased asymptotically with increasing food concentration. Maximum clearance rates at low food concentration were ca. 23 μl ind-1 h-1, which corresponds to a volume-specific clearance rate of 5.9x105 h-1. Cell size of P huberi was highly variable, with a mean diameter of 42 μm, but no clear relationship between cell size and food concentration was evident. Specific growth rates increased with food concentration until maximum growth rates of ∼0.7 d-1 were reached at a food concentration of 400 μg C l-1 (∼1000 cells ml-1). Food concentrations as low as 10 μg C l-1 of D. brightwellii (∼25 cells ml-1) were able to support growth of P. huberi. The bioluminescence of P. huberi varied with its nutritional condition and growth rate. Cells held without food lost their bioluminescence capacity in a matter of days. P. huberi raised at different food concentrations showed increased bioluminescence capacity, up to food concentration that supported maximum growth rates. The bioluminescence of P. huberi varied over a diel cycle, and these rhythmic changes persisted during 48 h of continuous darkness, indicating that the rhythm was under endogenous control.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00346747
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  • 8
    Electronic Resource
    Electronic Resource
    Residual stress measurement in thermal sprayed hydroxyapatite coatings (1994)
    Springer
    Journal of materials science 5 (1994), S. 756-759 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Hydroxyapatite coatings have been used for many years on dental and prosthetic implants to provide a biocompatible surface for long-term fixation of the implant to bone. In this study two thermal spraying processes, air plasma spraying (APS) and a high velocity oxy fuel process (CDS) have been employed to produce hydroxyapatite coatings. An X-ray diffraction technique (XRD) has been applied to measure the residual stresses in thermal sprayed hydroxyapatite coatings. It has been shown that such stresses are sensitive to spraying parameters and that the newer high velocity oxy fuel spraying process results in lower residual stresses than the conventional air plasma spraying process. Heat treatment of the coating has been shown to significantly reduce the residual stress in the coating.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00120371
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  • 9
    Electronic Resource
    Electronic Resource
    Rapid and efficient construction of yeast artificial chromosome contigs in the mouse genome with interspersed repetitive sequence PCR (IRS-PCR): Generation of a 5-cM, 〉5 megabase contig on mouse Chromosome 1 (1994)
    Springer
    Mammalian genome 5 (1994), S. 597-607 
    Details
    ISSN: 1432-1777
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have developed a new technique for the generation of YAC contigs in the mouse genome that is based on the ability to detect overlapping clones by hybridization of shared IRS-PCR products. As a demonstration of the technique, a 5-cM, 〉5 megabase contig was developed on the distal half of mouse Chromosome (Chr) 1, spanning the region from Lamb2 to At3. The contig covers roughly 5% of the genetic distance of the chromosome and is comprised of more than 80 clones; 71 probes were assigned physical order on the chromosome, of which 59 were new markers generated in this study. Eight of the new probes were shown to be polymorphic between C3H/HeJ-gld and M. spretus. Three probes were mapped on a [(C3H/HeJ-gld x M. spretus) x C3H/HeJ-gld] interspecific backcross to integrate the physical map with a high-resolution genetic map of the region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00411453
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  • 10
    Electronic Resource
    Electronic Resource
    Sequencing of the olfactory marker protein gene in normal and shaker-1 mutant mice (1994)
    Springer
    Mammalian genome 5 (1994), S. 11-14 
    Details
    ISSN: 1432-1777
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The mouse olfactory marker protein gene (Omp) maps close to the deafness mutation shaker-1 (sh-1) and has been considered a candidate gene for both sh-1 and its potential human homolog, the deaf-blind syndrome Usher Type I. Using primers devised from the available rat Olfactory Marker Protein gene sequence, we have determined the coding sequence of the mouse gene in both control inbred strains and six shaker-1 mutants. The coding sequence of the mouse Omp gene shows 97% nucleotide identity and 98% amino acid identity with the rat gene sequence. No sequence variants were detected in the coding region of any of the sh-1 mutants, ruling out Omp as the shaker-1 gene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00360561
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