2,176 research outputs found

    The new markets tax credit program: a midcourse assessment

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    Tax credits ; Community development corporations ; Economic development

    Synchrotron radiation photoionization mass spectrometry of laser ablated species

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    The present paper describes an experimental apparatus suitable to create and study free clusters by combining laser ablation and synchrotron radiation. First tests on sulfur samples, S, showed the production, through laser ablation, of neutral Sn clusters (n = 1–8). These clusters were ionized using synchrotron radiation at photon energies from 160 eV to 175 eV, across the S 2p core edge. The feasibility of such combined ablation–synchrotron radiation experiments is demonstrated, opening new possibilities on the investigation of free clusters and radical

    Recursive dynamic mode decomposition of transient and post-transient wake flows

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    A novel data-driven modal decomposition of fluid flow is proposed, comprising key features of proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD). The first mode is the normalized real or imaginary part of the DMD mode that minimizes the time-averaged residual. The NNth mode is defined recursively in an analogous manner based on the residual of an expansion using the first N−1N−1 modes. The resulting recursive DMD (RDMD) modes are orthogonal by construction, retain pure frequency content and aim at low residual. Recursive DMD is applied to transient cylinder wake data and is benchmarked against POD and optimized DMD (Chen et al., J. Nonlinear Sci., vol. 22, 2012, pp. 887–915) for the same snapshot sequence. Unlike POD modes, RDMD structures are shown to have purer frequency content while retaining a residual of comparable order to POD. In contrast to DMD, with exponentially growing or decaying oscillatory amplitudes, RDMD clearly identifies initial, maximum and final fluctuation levels. Intriguingly, RDMD outperforms both POD and DMD in the limit-cycle resolution from the same snapshots. Robustness of these observations is demonstrated for other parameters of the cylinder wake and for a more complex wake behind three rotating cylinders. Recursive DMD is proposed as an attractive alternative to POD and DMD for empirical Galerkin models, in particular for nonlinear transient dynamics

    Heat exchanger/reactors (HEX reactors): Concepts, technologies: State-of-the-art

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    Process intensification is a chemical engineering field which has truly emerged in the past few years and is currently rapidly growing. It consists in looking for safer operating conditions, lower waste in terms of costs and energy and higher productivity; and away to reach such objectives is to develop multifunctional devices such as heat exchanger/reactors for instance. This review is focused on the latter and makes a point on heat exchanger/reactors. After a brief presentation of requirements due to transposition from batch to continuous apparatuses, heat exchangers/reactors at industrial or pilot scales and their applications are described

    Uncommon branching pattern of the hepatic arteries in a living donor: a case report and brief literature review

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    Numerous variations of the hepatic arteries are common in surgical patients. We present a 35-year-old woman who was admitted to our department in order to assess possibility of becoming living donor. Preoperative computed tomography scan revealed anomalous branching pattern of the hepatic arteries. In this case right posterior sectoral artery has been given off by the greater pancreatic artery, left hepatic artery has been replaced by the artery arising from the left gastric artery and double segment 4 branches have been observed. To the best of our knowledge, this pattern has not been described in the literature, yet

    A concise review on microwave-assisted polycondensation reactions and curing of polycondensation polymers with focus on the effect of process conditions

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    During the past 15 years, increasing application of microwave heating to polycondensation reactions has been witnessed. Experiments have been carried out at laboratory scale using widely different experimental procedures. The use of microwaves has often led to significant benefits compared to conventional heating experiments in terms of multi-fold decrease in reaction times and energy consumption and production of polymers with increased molecular weight and improved mechanical properties. In other cases, microwaves do not appear to produce any significant benefits compared to conventional heating. At present, guidelines to experimentalist as to the process conditions and experimental design that should be applied are missing and experimentation seems to be based on an empirical trial-and-error approach. In view of the very different experimental protocols that have been applied and the contradictory trends that are frequently reported, we aim in this review to shed light on the role of important process parameters, such as the presence and type of solvent, the dielectric properties of the mixture and the individual phases, the use of heterogeneous catalysts, pressure, stirring, reflux conditions, temperature measurement method and microwave absorbing fillers, which all seem to determine the occurrence and magnitude of the benefits enabled by microwaves during polycondensation reactions

    Thyroid dysfunction in patients with diabetic retinopathy

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    Thyroid disease and diabetes mellitus (DM) are the most common endocrinopathies in clinical practice that interact with each other. On the one hand, thyroid hormones regulate carbohydrate metabolism and pancreas functions, and on the other hand DM affects the function and work of the thyroid gland. Diabetic retinopathy (DR) is a highly specific neurovascular complication of both type 1 and type 2 DM, which is a significant cause of vision loss on a global scale. In DM, the internal blood-retinal barrier is the earliest to be damaged, and changes in neuroretina result from the loss of its adaptation to metabolic disorders. Patients with DM have a higher incidence of thyroid disease compared to people without DM. The coexistence of DM with thyroid disease leads to endothelial damage, and the degree of its dysfunction has a significant impact on the course of macro- and microangiopathic complications in patients. There are few reports in the literature about the impact of thyroid disease and substitution of levothyroxine preparations on the development and course of DR in patients with DM. It is unknown whether the fact that patients with unrecognised hypothyroidism are not treated with levothyroxine preparations disrupts thyroid hormone homeostasis to the extent that it may contribute to a higher incidence of DR. This review discusses recent clinical trials for thyroid dysfunction in patients with DR.
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