3,563 research outputs found

    Location Choice

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    Much of the excitement around the North American Free Trade Agreement (NAFTA) has been generated by anticipations of a strongly foreign investment response. Nevertheless, the plethora of applied papers about the NAFTA have all either ignored DFI or kept it exogenous. In this paper we provide support, with empirical underpinning, for the anticipation of a strong DFI response; however this support is qualified by the demonstration that no such DFI response will be forthcoming unless the NAFTA is used to drastically reform the agriculture and services sectors in Mexico.

    Use of Hydration Inhibitors to Improve Bond Durability of Aluminum Adhesive Joints

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    An investigation is conducted of the mechanisms by which nitrilotris methylene phosphonic acid (NTMP) and related compounds are adsorbed onto oxidized aluminum surfaces to inhibit hydration and increase the durability of adhesive bonds formed with inhibitor-treated panels. P - O - Al bonds are identified as the basis of adsorption, and it is found that water initially adsorbed onto the etched aluminum surfaces is displaced by the NTMP. The hydration of the NTMP-treated surfaces occurs in three stages, namely the reverisble physisorption of water, the slow dissolution of NTMP followed by rapid hydration of the freshly exposed Al2O3 to AlOOH and further hydration of the surface to Al(OH)3. Five properties of an ideal inhibitor are identified

    Atomistic mechanisms for the ordered growth of Co nano-dots on Au(788): comparison of VT-STM experiments and multi-scaled calculations

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    Hetero-epitaxial growth on a strain-relief vicinal patterned substrate has revealed unprecedented 2D long range ordered growth of uniform cobalt nanostructures. The morphology of a Co sub-monolayer deposit on a Au(111) reconstructed vicinal surface is analyzed by Variable Temperature Scanning Tunneling Microscopy (VT-STM) experiments. A rectangular array of nano-dots (3.8 nm x 7.2 nm) is found for a particularly large deposit temperature range lying from 60 K to 300 K. Although the nanodot lattice is stable at room temperature, this paper focus on the early stage of ordered nucleation and growth at temperatures between 35 K and 480 K. The atomistic mechanisms leading to the nanodots array are elucidated by comparing statistical analysis of VT-STM images with multi-scaled numerical calculations combining both Molecular Dynamics for the quantitative determination of the activation energies for the atomic motion and the Kinetic Monte Carlo method for the simulations of the mesoscopic time and scale evolution of the Co submonolayer

    A broadband optical cavity spectrometer for measuring weak near-ultraviolet absorption spectra of gases

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    Accurate absorption spectra of gases in the near-ultraviolet (300 to 400 nm) are essential in atmospheric observations and laboratory studies. This paper describes a novel incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) instrument for measuring very weak absorption spectra from 335 to 375 nm. The instrument performance was validated against the B-3(1)-X(1)A(1) transition of SO2. The measured absorption varied linearly with SO2 column density and the resulting spectrum agrees well with published spectra. Using the instrument, we report new absorption cross-sections of O-3, acetone, 2-butanone, and 2-pentanone in this spectral region, where literature data diverge considerably. In the absorption minimum between the Huggins and Chappuis bands, our absorption spectra fall at the lower range of reported ozone absorption cross-sections. The spectra of the ketones agree with prior spectra at moderate absorptions, but differ significantly at the limits of other instruments' sensitivity. The collision-induced absorption of the O-4 dimer at 360.5 nm was also measured and found to have a maximum cross-section of ca. 4.0 x 10(-46) cm(5) molecule(-2). We demonstrate the application of the instrument to quantifying low concentrations of the short-lived radical, BrO, in the presence of stronger absorptions from Br-2 and O-3

    The process of irreversible nucleation in multilayer growth. II. Exact results in one and two dimensions

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    We study irreversible dimer nucleation on top of terraces during epitaxial growth in one and two dimensions, for all values of the step-edge barrier. The problem is solved exactly by transforming it into a first passage problem for a random walker in a higher-dimensional space. The spatial distribution of nucleation events is shown to differ markedly from the mean-field estimate except in the limit of very weak step-edge barriers. The nucleation rate is computed exactly, including numerical prefactors.Comment: 22 pages, 10 figures. To appear in Phys. Rev.

    Near-ultraviolet absorption cross sections of nitrophenols and their potential influence on tropospheric oxidation capacity

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    Nitrophenols and methylnitrophenols have been identified as photolytic precursors of nitrous acid, HONO, but their gas-phase absorption has not previously been reported. In this study, the absorption cross sections of 2-nitrophenol, 3-methyl-2-nitrophenol, and 4-methyl-2-nitrophenol were measured from 320 to 450 nm using incoherent broad-band cavity enhanced absorption spectroscopy (IBBCEAS). The benzaldehyde absorption spectrum wasmeasured to validate the approach and was in good agreement with literature spectra. The nitrophenol absorption cross sections are large (ca. 10-17 cm2 molecule-1)  and blue-shifted about 20 nm compared to previously measured solution spectra. Besides forming HONO, nitrophenol absorption influences other photochemistry by reducing the available actinic flux. The magnitudes of both effects are evaluated as a function of solar zenith angle, and nitrophenol absorption is shown to lower the photolysis rates of O3 and NO2

    Using integrated absorption to calibrate optical cavity spectrometers

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    Sensitive absorption techniques using optical cavities (such as CEAS or ICOS) generally need the spectrometer response to be calibrated for quantitative measurements. Most calibrations are based on the instrument response to a known, steady state absorption. Such calibrations often have drawbacks in terms of cost, complexity, or convenience, especially for field measurements. In this paper, we show that the relationship between the integrated absorption and a known amount of absorber provides an alternative calibration strategy that yields a highly linear calibration curve and has a low uncertainty. This method is straightforward to implement and offers a practical alternative to other calibration strategies

    Crossover in the scaling of island size and capture zone distributions

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    Simulations of irreversible growth of extended (fractal and square) islands with critical island sizes i=1 and 2 are performed in broad ranges of coverage \theta and diffusion-to-deposition ratios R in order to investigate scaling of island size and capture zone area distributions (ISD, CZD). Large \theta and small R lead to a crossover from the CZD predicted by the theory of Pimpinelli and Einstein (PE), with Gaussian right tail, to CZD with simple exponential decays. The corresponding ISD also cross over from Gaussian or faster decays to simple exponential ones. For fractal islands, these features are explained by changes in the island growth kinetics, from a competition for capture of diffusing adatoms (PE scaling) to aggregation of adatoms with effectively irrelevant diffusion, which is characteristic of random sequential adsorption (RSA) without surface diffusion. This interpretation is confirmed by studying the crossover with similar CZ areas (of order 100 sites) in a model with freezing of diffusing adatoms that corresponds to i=0. For square islands, deviations from PE predictions appear for coverages near \theta=0.2 and are mainly related to island coalescence. Our results show that the range of applicability of the PE theory is narrow, thus observing the predicted Gaussian tail of CZD may be difficult in real systems.Comment: 9 pages, 7 figure

    Learning in Partnership: Leadership as a Cornerstone for Interprofessional Education Between GPs and Community Pharmacists

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    Objective: Interprofessional education (IPE), defined as ‘Occasions where two or more professions learn with, from and about each other to improved collaboration and the quality of care’ (Barr, 2002), is vital for development of new NHS models of patient care. This project aimed to develop and evaluate an IPE programme to encourage the development of networks of Community Pharmacists and GPs, and to deepen understanding of each other’s NHS contracts and their role in helping achieve better patient outcomes. / Design: Leadership training provided common ground for IPE with GPs and community pharmacists. Five pairs of GPs and community pharmacists, recruited from London and the South East, attended an initial project induction event and five half-day sessions focussing on leadership training based on the Healthcare Leadership Model (NHS Leadership Academy, 2013). The pairs then spent four half day placements in each other’s practice. As an outcome of these activities, each pair was required to jointly undertake, write up and present a Quality Improvement Project (QIP). The leadership training was evaluated using a questionnaire containing open questions developed from previously used questionnaires. Responses were scrutinised to identify and frequency-count themes. / Results: Eight responses were received. Ten overarching themes emerged. The most frequent themes were ‘developing understanding’ and ‘collaborative working’, as illustrated by the following quotes: ‘I have a new found respect for Doctors now and realise we are in the same boat.’ ‘We can work together to achieve a common goal.’ / Conclusion: The focus on leadership training enabled pharmacists and GPs to learn from, with and about each other through the identification of similar challenges and issues. This provided a strong basis to develop interprofessional communication and collaborative working to improve the patient journey
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