1,870 research outputs found

    Some linear Jacobi structures on vector bundles

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    We study Jacobi structures on the dual bundle A∗A^\ast to a vector bundle AA such that the Jacobi bracket of linear functions is again linear and the Jacobi bracket of a linear function and the constant function 1 is a basic function. We prove that a Lie algebroid structure on AA and a 1-cocycle ϕ∈Γ(A∗)\phi \in \Gamma (A^\ast) induce a Jacobi structure on A∗A^\ast satisfying the above conditions. Moreover, we show that this correspondence is a bijection. Finally, we discuss some examples and applications.Comment: 6 pages, To appear in C. R. Acad. Sci. Paris, S\'erie

    Some applications of semi-discrete variational integrators to classical field theories

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    We develop a semi-discrete version of discrete variational mechanics with applications to numerical integration of classical field theories. The geometric preservation properties are studied.Comment: 14 page

    High efficiency cathodes for SOFCs prepared by spray-pyrolysis

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    In recent years, lowering the operating temper-ature of the Solid Oxide Fuel Cells (SOFCs) to the intermediate temperature range (500-700 ÂșC) has become the main challenge for this technology. The electrolyte resistance might be substantially reduced by using thin film electrolytes. However, the cathode polarization resitance is responsible for much of the loss in performance at low temperatures. Thus, the development of cathode materials with high electro-catalytic activity for the oxygen reduction reaction (ORR) is essential for this technology. Lanthanum strontium manganite La1-xSrxMnO3- (LSM) is the cathode material most widely used in SOFCs. However, LSM exhibits high activation energy for oxygen reduction reaction (ORR) and poor ionic conductivity, limiting its application at high temperatures. Alternative mixed ionic-electronic conductors, such as La1-xSrxCo1-yFeyO3-ÎŽ (LSCF) and GdBaCo2O5+x (GBC) has been investi-gated, exhibiting better performances in the inter-mediate temperature range [1]. The performance of these electrodes might be improved at reduced temperature by extending the triple phase bounda-ry length at which gas, electrode and electrolyte phases are simultaneously in contact, serving as the predominant site for the electrochemical reac-tions. To date, the preparation of electrodes via wet infiltration of a cation solution into a porous electrolyte backbone is one of the most effective methods to increase the TPB area and to improve the efficiency of the cathodes, despite the limitations of this process for large-scale manufacturing of SOFCs. In this contribution an alternative preparation method based on spray-pyrolisis deposition into an electrolyte backbone is proposed, which posses a series of advantages with respect to the classical wet infiltration process, including easy industrial implementation, preparation in one single deposition/thermal step as well as low cost [2]. The most widely used cathodes in SOFCs technology were prepared by this alternative method process: La1-xSrxMnO3- and La0.6Sr0.4Co1-yFeyO3-ÎŽ (y = 0-2) series. The electrodes were deposited on porous Ce0.8Gd0.1O1.95 (CGO) backbones at 250 ÂșC by conventional spray pyrolysis from an aqueous precursor solution of metal nitrates. The structure, microstructure and electrochemical properties of these materials have been investigated by X-ray diffraction, field-emission SEM (Fig. 1.a) and im-pedance spectroscopy in symmetrical cells. The values of polarization resistance (Fig. 1.b) are ex-tremely low, ranging from 0.40 cm2 for LSM to 0.07 cm2 for LSCF0.2 at 600 ÂșC in air, compared to those previously reported in the literature for commercial electrolytes deposited at high tempera-ture, e.g. 25 cm2 for LSM.Universidad de MĂĄlaga. Campus de Excelencia Internacional AndalucĂ­a Tech

    A Critical Dialogue: Communicating with Type 2 Diabetes Patients about Cardiovascular Risk

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    Patients with type 2 diabetes mellitus (DM) are at increased risk for cardiovascular disease (CVD), and many patients are inadequately treated for risk factors such as hyperglycemia, hyperlipidemia, hypertension, and smoking. Providing individualized risk information in a clear and engaging manner may serve to encourage both patients and their physicians to intensify risk-reducing behaviors and therapies. This review outlines simple and effective methods for making CVD risk infomation understandable to persons of all levels of literacy and mathematical ability. To allow the patient to understand what might happen and how, personal risk factors should be clearly communicated and the potential consequences of a CVD event should be presented in a graphic but factual manner. Risk calculation software can provide CVD risk estimates, and the resulting information can be made understandable by assigning risk severity (eg, “high”) by comparing clinical parameters with accepted treatment targets and by comparing the individual's risk with that of the “average” person. Patients must also be informed about how they might reduce their CVD risk and be supported in these efforts. Thoughtful risk communication using these techniques can improve access to health information for individuals of low literacy, especially when interactive computer technology is employed. Research is needed to find the best methods for communicating risk in daily clinical practice

    Monetary policy and inflation persistence in the Eurozone

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    The primary goal of the European Central Bank’s (ECB) monetary policy is to achieve price stability. Whereas during the 1980s and 1990s there was a rapid and strong convergence in terms of price differential among the Euro countries, particularly in those countries with higher inflation rates in the past, single monetary policy has proved to be quite inefficient in continuing this trend and has not achieved further reductions in inflation rate differentials within the euro zone. Since the ECB sets the official interest rate according to the average inflation of the euro area, the persistence of such price differentials within the area would mean that the “one size interest rate policy” would not fit all. This paper studies empirically the inflation rate differentials and their persistence in some currency unions with the aim to draw some conclusions for the working of the ECB monetary policy. KEYWORDS: monetary policy; inflation persistence; currency unions

    Strengthening of Aluminum Wires Treated with A206/Alumina Nanocomposites.

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    This study sought to characterize aluminum nanocomposite wires that were fabricated through a cold-rolling process, having potential applications in TIG (tungsten inert gas) welding of aluminum. A206 (Al-4.5Cu-0.25Mg) master nanocomposites with 5 wt % γAl₂O₃ nanoparticles were first manufactured through a hybrid process combining semi-solid mixing and ultrasonic processing. A206/1 wt % γAl₂O₃ nanocomposites were fabricated by diluting the prepared master nanocomposites with a monolithic A206 alloy, which was then added to a pure aluminum melt. The fabricated Al-γAl₂O₃ nanocomposite billet was cold-rolled to produce an Al nanocomposite wire with a 1 mm diameter and a transverse area reduction of 96%. Containing different levels of nanocomposites, the fabricated samples were mechanically and electrically characterized. The results demonstrate a significantly higher strength of the aluminum wires with the nanocomposite addition. Further, the addition of alumina nanoparticles affected the wires' electrical conductivity compared with that of pure aluminum and aluminum-copper alloys. The overall properties of the new material demonstrate that these wires could be an appealing alternative for fillers intended for aluminum welding

    Innovations in healthcare delivery and policy: Implications for the role of the psychologist in preventing and treating diabetes

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    Although the biomedical model has dominated U.S. health care for more than a century, it has failed to adequately address current U.S. health care challenges, including the treatment and prevention of chronic disease; the epidemic rise in diabetes is one important example. In response, newer models of health care have been developed that address patients' mental and physical health concerns by multidisciplinary care teams that place the patient and family in the center of shared decision making. These new models of care offer many important opportunities for psychologists to play a larger role in the prevention and treatment of diabetes. However, for psychology's role to be fully realized, both external and internal challenges must be addressed. This will require psychologists to become more interdisciplinary, more familiar with the larger health care culture, more willing to expand their skill sets, and more collaborative with other health disciplines both from a patient-care and a larger advocacy perspective
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