6,158 research outputs found

    Aluminum work function: Effect of oxidation, mechanical scraping and ion bombardment

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    Surface studies have been performed on aluminum polycrystalline surfaces which have been mechanically scraped. Such studies were initiated in order to understand surface effects occurring in tribological processes which involve rubbing surfaces and the effects of adsorption of oxygen. To characterize the surfaces, the following three different experimental approaches have been used: (1) X.P.S. (X-ray photoelectron spectroscopy), in order to check the cleanliness of the surfaces and follow the adsorption and oxidation kinetics; (2) Analysis of the work function changes by following the energy spectra of secondary electrons emitted under low energy electron bombardment; and (3) Analysis of photoemission intensities under U.V. excitation. The reference state being chosen to be the surface cleaned by ion bombardment and exposures to oxygen atmospheres have been shown to lower the work function of clean polycrystalline aluminum by 1.2 eV. The oxygen pressure is found to affect only the kinetics of these experiments. Mechanical scraping has been shown to induce a decrease ( 0.3 eV) in the work function, which could sharply modify the kinetics of adsorption on the surface

    Corporate e-communication: its relationship with the corporate logo in the construction of digital interaction platforms

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    Purpose – The purpose of this article is to examine the influence of the corporate logo on the consumer’s attitude within corporate e-communication. Design/methodology/approach – This research designed a model and a number of hypotheses, based on previous studies on corporate logo, its antecedents on e-communication, corporate image and corporate reputation. Online survey was conducted consumers and followers of the shopping social networking platforms (Facebook and Twitter) in from Colombia. Findings – Taking into account previous corporate constructs theories, the author proposes a new conceptual framework to explain how corporate e-communication interacts within an organisation’s structure, and also to show that the consumer’s interaction in corporate e-communication platforms is based on the corporate logo perception held by consumers; as a consequence, the corporate reputation is affected. Originality/value – This study contributes on the understanding and expansion of the organisation’s structure by introducing a new corporate construct, named ‘corporate e-communication’, defined as the digital interaction than an organisation has with its stakeholders, it involves everything it says, shows and does. However, there are a few other areas of concern with regard to consequences related to corporate image and corporate reputation, particularly in Colombian retail setting

    Information Disclosure Policies: Evidence from the Electricity Industry

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    A “third wave” of environmental policy has recently emerged that emphasizes information provision as an integral part of the risk mitigation strategy. While theory suggests information programs may correct market failures and improve welfare, the empirical effectiveness of these programs remains largely undetermined. We show that mandatory information disclosure programs in the electricity industry achieve stated policy goals. We that the average proportion of fossil fuels decreases and the average proportion of clean increases in response to disclosure programs. However, the programs also produce unintended consequences. Customer composition and pre-existing fuel mix significantly affect program response, suggesting that effective information disclosure policies may not be efficient.disclosure, information, fuel mix, electric utilities

    Contemporaneous broad-band photometry and Hα\alpha observations of T Tauri stars

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    The study of contemporaneous variations of the continuum flux and emission lines is of great importance to understand the different astrophysical processes at work in T Tauri stars. In this paper we present the results of a simultaneous BVRIBVRI and Hα\alpha photometric monitoring, contemporaneous to medium-resolution spectroscopy of six T Tauri stars in the Taurus-Auriga star forming region. We have characterized the Hα\alpha photometric system using synthetic templates and the contemporaneous spectra of the targets. We show that we can achieve a precision corresponding to 2−-3 \AA\ in the Hα\alpha equivalent width, in typical observing conditions. The spectral analysis has allowed us to determine the basic stellar parameters and the values of quantities related to the accretion. In particular, we have measured a significant veiling only for the three targets with the strongest Hα\alpha emission (T Tau, FM Tau, and DG Tau). The broad-band photometric variations are found to be in the range 0.05−-0.70 mag and are often paired to variations in the Hα\alpha intensity, which becomes stronger when the stellar continuum is weaker. In addition, we have mostly observed a redder V−IV-I and a bluer B−VB-V color as the stars become fainter. For most of the targets, the timescales of these variations seem to be longer than the rotation period. One exception is T Tau, for which the broad-band photometry varies with the rotation period. The most plausible interpretation of these photometric and Hα\alpha variations is that they are due to non-stationary mass accretion onto the stars, but rotational modulation can play a major role in some cases.Comment: 21 pages, 11 figures, accepted for publication in Acta Astronomic

    Renormalization Group Equations for the CKM matrix

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    We derive the one loop renormalization group equations for the Cabibbo-Kobayashi-Maskawa matrix for the Standard Model, its two Higgs extension and the minimal supersymmetric extension in a novel way. The derived equations depend only on a subset of the model parameters of the renormalization group equations for the quark Yukawa couplings so the CKM matrix evolution cannot fully test the renormalization group evolution of the quark Yukawa couplings. From the derived equations we obtain the invariant of the renormalization group evolution for three models which is the angle α\alpha of the unitarity triangle. For the special case of the Standard Model and its extensions with v1≈v2v_{1}\approx v_{2} we demonstrate that also the shape of the unitarity triangle and the Buras-Wolfenstein parameters ρˉ=(1−1/2λ2)ρ\bar{\rho}=(1-{1/2}\lambda^{2})\rho and ηˉ=(1−1/2λ2)η\bar{\eta}=(1-{1/2}\lambda^{2})\eta are conserved. The invariance of the angles of the unitarity triangle means that it is not possible to find a model in which the CKM matrix might have a simple, special form at asymptotic energies.Comment: 9 page

    Del Mictlan al infierno: el sincretismo religioso en La conversiĂłn de San Pablo, pieza temprana del teatro de evangelizaciĂłn novohispano

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