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  • 1
    Electronic Resource
    Electronic Resource
    A practicable steepest-edge simplex algorithm (1977)
    Springer
    Mathematical programming 12 (1977), S. 361-371 
    Details
    ISSN: 1436-4646
    Keywords: Simplex Method ; Linear Programming ; Steepest-edge ; LU Factorization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract It is shown that suitable recurrences may be used in order to implement in practice the steepest-edge simplex linear programming algorithm. In this algorithm each iteration is along an edge of the polytope of feasible solutions on which the objective function decreases most rapidly with respect to distance in the space of all the variables. Results of computer comparisons on medium-scale problems indicate that the resulting algorithm requires less iterations but about the same overall time as the algorithm of Harris [8], which may be regarded as approximating the steepest-edge algorithm. Both show a worthwhile advantage over the standard algorithm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01593804
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  • 2
    Electronic Resource
    Electronic Resource
    The Response to Gibberellin in Pisum sativum Grown under Alternating Day and Night Temperature (1998)
    Springer
    Journal of plant growth regulation 17 (1998), S. 161-167 
    Details
    ISSN: 1435-8107
    Keywords: Key Words. DIF—Gibberellin—Inactivation—Pea—Response—Stem elongation—Temperature—Thermoperiodism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. The application of gibberellins (GA) reduces the difference in stem elongation observed under a low day (DT) and high night temperature (NT) combination (negative DIF) compared with the opposite regime, a high DT/low NT (positive DIF). The aim of this work was to investigate possible thermoperiodic effects on GA metabolism and tissue sensitivity to GA by comparing the response to exogenously applied GA (in particular, GA1 and GA3) in pea plants (Pisum sativum cv. Torsdag) grown under contrasting DIF. Control plants not treated with growth inhibitors or additional GA were 38% shorter under negative (DT/NT 13/21°C) than positive DIF (DT/NT 21/13°C) because of shorter internodes. Additional GA1 or GA3 decreased the difference between positive and negative DIF. In pea plants dwarfed with paclobutrazol, which inhibits GA biosynthesis at an early step, the response to GA1 was reduced more strongly by negative compared with positive DIF than the response to GA3. The induced stem elongation by GA19 and GA20 did not deviate significantly from the response to GA1. Plants treated with prohexadione-calcium, an inhibitor of both the production and the inactivation of GA1, grew equally tall under the two temperature regimes in response to both GA1 and GA3. We hypothesize that the reduced response to GA1 compared with GA3 in paclobutrazol-treated plants grown under negative DIF is caused by a higher rate of 2β-hydroxylation of GA1 into GA8 under negative than positive DIF. This contributes to lower levels of GA1 and consequently shorter stems and internodes in pea plants grown under negative than positive DIF. Differences in tissue sensitivity to GA alone cannot account for this specific thermoperiodic effect on stem elongation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00007030
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  • 3
    Electronic Resource
    Electronic Resource
    Heavy top quark decay into a charged Higgs scalar and a photon (gluon) (1991)
    Springer
    The European physical journal 51 (1991), S. 395-398 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We consider the decay of a heavy top quark into a charged Higgs scalar and a hard photon (gluon)t→H + bγ(g). We give the general result for fermions of arbitrary mass. Our results for the differential decay rate for these two processes are remarkably simple. The radiation amplitude zero (RAZ) factorization is explicit but there is no RAZ for these processes because of the presence of opposite-sign charges. We obtain a branching ratio of 0.063% for bH+γ and 5.6% for bH+g. Thus both decays should be relatively easy to see at the SSC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01548561
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  • 4
    Electronic Resource
    Electronic Resource
    Detection of sulphur dioxide at, and below, the part per billion level using a tunable diode laser (1979)
    Springer
    Optical and quantum electronics 11 (1979), S. 385-391 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A laser absorption spectrometer is described which employs a wavelength tunable diode laser in conjunction with a multipass White cell. The instrument uses absorption lines in theν 3 band of SO2 to monitor atmospheric SO2 concentrations with sensitivities as high as 0.2 parts per billion (ppb) in a laboratory system. A portable instrument with a fast response time and a sensitivity of 1 ppb is described, and the development of a highly practical field instrument, based on pyroelectric detectors, is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00619820
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  • 5
    Electronic Resource
    Electronic Resource
    High sensitivity detection of trace gases at atmospheric pressure using tunable diode lasers (1985)
    Springer
    Optical and quantum electronics 17 (1985), S. 31-39 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A detailed study of the detection of trace gases at atmospheric pressure using tunable diode lasers is described. The influence of multipass cells, retroreflectors and topographical targets is examined. The minimum detectable infrared absorption ranges from 0.1% for a pathlength of 1.2 km to 0.01% over short pathlengths. The factors which limit this sensitivity are discussed, and the techniques are illustrated by monitoring atmospheric CO2 and CH4.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00619991
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  • 6
    Electronic Resource
    Electronic Resource
    Implicit Scaling of Linear Least Squares Problems (2000)
    Springer
    BIT 40 (2000), S. 146-157 
    Details
    ISSN: 1572-9125
    Keywords: Weighted linear least squares ; QR factorization ; backward errors ; iterative refinement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract We consider the solution of weighted linear least squares problems by Householder transformations with implicit scaling, that is, with the weights stored separately. By holding inverse weights, the constrained case can be accommodated. The error analysis of the weighted and unconstrained case is readily extended and we show that iterative refinement may be applied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022374520140
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  • 7
    Electronic Resource
    Electronic Resource
    Modeling of high-pressure 12-μm NH3 lasers (1985)
    Springer
    Applied physics 37 (1985), S. 165-170 
    Details
    ISSN: 1432-0649
    Keywords: 42.55.Hq ; 33.80Be ; 42.60.By
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Experimental measurements of small-signal gain in an optically-pumped NH3 amplifier are carried out at pressures ranging from 40 Torr to 760 Torr, and the results are used to validate a rate-equation model describing the amplifier dynamics. The gain measurements show that dilute mixtures of 〈0.5% NH3 in N2 are reqired to minimize the problems of gas heating due to pump absorption. The model is used to extrapolate the results to gas pressures of several atmospheres, and to demonstrate the potential for highpressure operation of optically-pumped NH3 lasers. For a pump intensity of 100 MW/cm2, calculations indicate that operation of an NH3−N2 laser is feasible up to a pressure of 10 atm, which would provide a maximum continuous tuning range of 4 cm−1. High-resolution spectroscopy reveals that gain on a few NH3 transitions is eliminated at high pressures due to the presence of overlapping absorptions in other NH3 bands.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00692080
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  • 8
    Electronic Resource
    Electronic Resource
    Gain dynamics of the 4.3 μm CO2 laser (1985)
    Springer
    Applied physics 36 (1985), S. 115-124 
    Details
    ISSN: 1432-0649
    Keywords: 42.55.Dk ; 42.60.By
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A detailed study of the gain dynamics of the pulsed, optically pumped 4.3 μm CO2 laser is described. Small-signal gain coefficients as high as 14%/cm are measured in a 4.3 μm amplifier using low-power pulses from a 4.3 μm probe laser. The measurements are compared with a rate-equation model and good quantitative agreement is obtained. The model, which uses no adjustable parameters, is described in detail. Gain is studied as a function of optical pumping power, gas mixture, gas pressure and discharge excitation of the 4.3 μm amplifier. Optimization of the gain is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00691775
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  • 9
    Electronic Resource
    Electronic Resource
    High power, high efficiency optically pumped NH3 lasers (1990)
    Springer
    Applied physics 51 (1990), S. 371-373 
    Details
    ISSN: 1432-0649
    Keywords: 33.80.Be ; 42.55.Hq ; 42.60.By
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A simple and efficient NH3 laser was tuned over more than 70 vibrational band transitions between 10.08 and 14.14 μm. The active medium was a dilute mixture of ammonia in argon and was optically pumped by the 9R(30) transition of a pulsed TEA-CO2 laser. Output energies greater than 1 J per pulse were observed on several of the strongest lines. In a non-selective cavity an energy conversion efficiency of greater than 35% was obtained with a maximum output energy of 4.6J. Optically pumped NH3 is shown to be a flexible and efficient system for the downconversion of CO2 radiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00348975
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  • 10
    Electronic Resource
    Electronic Resource
    Harmonic detection with tunable diode lasers —two-tone modulation (1982)
    Springer
    Applied physics 29 (1982), S. 279-285 
    Details
    ISSN: 1432-0649
    Keywords: 07.65 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The minimum absorption detectable by a tunable diode laser spectrometer utilising harmonic techniques is often limited by interference fringes generated by scattered light. The sensitivity of the spectrometer to absorption can be increased by applying a jitter modulation. In this paper, the theory of harmonic response for single- and two-tone modulation over optical fringes and Lorentzian absorption lines is developed and compared to experimental measurements. A simple analytic expression for the two-tone harmonic line shape is derived. This expression provides a physical understanding of the effects of the second modulation, and a means to unravel the effects of the second modulation on the linewidth and line shape. For a specific choice of the jitter frequency and phase, it is possible to simultaneously minimise the fringe signal and increase the harmonic absorption signal. The results of this investigation are applicable to trace gas detection using tunable diode lasers, and to other areas of spectroscopy and magnetic resonance where harmonic techniques are used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00689188
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