11,895 research outputs found

    An assessment of the construct validity of environmental strategy measures

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    The natural resource-based view of the company is emerging as a dominant paradigm for understanding the intersection of strategic management and the natural environment. Companies that proactively incorporate a natural environment perspective into their enterprise strategies are said to have sustainable competitive advantages. However, defining and measuring environmental strategy has been challenging, with different approaches yielding inconsistent results. Many studies ignore the empirical difficulties of marrying the theoretical connection between the company's resource base and environmental strategy, and its impact on environmental company performance. In this paper, we apply an inductive approach to derive a measure of environmental strategy theoretically congruent with the natural resource-based-view of the firm. We assess its reliability and, using a multi-trait multi-method matrix, confirm the convergent and discriminant validities of this measure against other measures often used by researchers. We also establish predictive validity of our environmental strategy measure for environmental performance. We discuss the implications of the measure for future research and practice.environmental performance; environmental strategies; inductive study; measures;

    The quark-antiquark potential at finite temperature and the dimension two gluon condensate

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    A recently proposed phenomenological model, which includes non perturbative effects from dimension two gluon condensates, is applied to analyze the available lattice data for the heavy quark free energy in the deconfined phase of quenched QCD. For large qqˉq\bar{q} separations we recover previous results for the Polyakov loop, exhibiting unequivocal condensate contributions. For the qqˉq\bar{q} potential at finite temperature and finite separation we find that a good overall description of the lattice data can be achieved once the condensate is properly accounted for. In addition, the model predicts a duality between the zero temperature potential as a function of the qqˉq\bar{q} separation, on the one hand, and the quark selfenergy as a function of the temperature, on the other, which turns out to be satisfied to a high degree by the lattice data.Comment: 9 pages, 5 figure

    Optical measurement of heteronuclear cross-relaxation interactions in Tm:YAG

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    We investigate cross-relaxation interactions between Tm and Al in Tm:YAG using two optical methods: spectral holeburning and stimulated echoes. These interactions lead to a reduction in the hyperfine lifetime at magnetic fields that bring the Tm hyperfine transition into resonance with an Al transition. We develop models for measured echo decay curves and holeburning spectra near a resonance, which are used to show that the Tm-Al interaction has a resonance width of 10~kHz and reduces the hyperfine lifetime to 0.5 ms. The antihole structure is consistent with an interaction dominated by the Al nearest neighbors at 3.0 Angstroms, with some contribution from the next nearest neighbors at 3.6 Angstroms.Comment: 13 pages, 9 figure

    Predictive learning, prediction errors, and attention: evidence from event-related potentials and eye tracking

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    Prediction error (‘‘surprise’’) affects the rate of learning: We learn more rapidly about cues for which we initially make incorrect predictions than cues for which our initial predictions are correct. The current studies employ electrophysiological measures to reveal early attentional differentiation of events that differ in their previous involvement in errors of predictive judgment. Error-related events attract more attention, as evidenced by features of event-related scalp potentials previously implicated in selective visual attention (selection negativity, augmented anterior N1). The earliest differences detected occurred around 120 msec after stimulus onset, and distributed source localization (LORETA) indicated that the inferior temporal regions were one source of the earliest differences. In addition, stimuli associated with the production of prediction errors show higher dwell times in an eyetracking procedure. Our data support the view that early attentional processes play a role in human associative learning

    ISOPHOT Observations of Narrow-Line Seyfert 1 Galaxies

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    Broad infrared spectra (7-200 micrometer) of four NLS1 galaxies, obtained with the imaging photo-polarimeter (ISOPHOT) on board the Infrared Space Observatory (ISO), are presented. The infrared luminosities and temperatures, opacities and sizes of the emitting dust components are derived. A comparison between the observed infrared spectra and the optical emission line fluxes of a sample of 16 NLS1 galaxies suggests that these objects suffer different degrees of dust absorption according to the inclination of the line of sight with respect to the dust distribution.Comment: Contributed talk presented at the Joint MPE,AIP,ESO workshop on NLS1s, Bad Honnef, Dec. 1999, to appear in New Astronomy Reviews; also available at http://wave.xray.mpe.mpg.de/conferences/nls1-worksho

    Proving strong magnetic fields near to the central black hole in the quasar PG0043+039 via cyclotron lines

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    The optical luminous quasar PG0043+039 has not been detected before in deep X-ray observations indicating the most extreme optical-to-X-ray slope index αox{\alpha}_{ox} of all quasars. This study aims to detect PG0043+039 in a deep X-ray exposure. Furthermore, we wanted to check out whether this object shows specific spectral properties in other frequency bands. We took deep X-ray (XMM-Newton), far-ultraviolet (HST), and optical (HET, SALT telescopes) spectra of PG0043+039 simultaneously in July 2013. We just detected PG0043+039 in our deep X-ray exposure. The steep αox=2.37±0.05{\alpha}_{ox} = -2.37 {\pm} 0.05 gradient is consistent with an unusual steep gradient FνναF_{\nu} {\sim} {\nu}^{\alpha} with α=2.67±0.02{\alpha} = -2.67 {\pm} 0.02 seen in the UV/far-UV continuum. The optical/UV continuum flux has a clear maximum near 2500 {\AA}. The UV spectrum is very peculiar because it shows broad humps in addition to known emission lines. A modeling of these observed humps with cyclotron lines can explain their wavelength positions, their relative distances, and their relative intensities. We derive plasma temperatures of T {\sim} 3keV and magnetic field strengths of B {\sim} 2 ×108{\times} 10^8 G for the line-emitting regions close to the black hole.Comment: 4 pages, 3 figures, Astronomy & Astrophysics in pres
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