118 research outputs found

    Consistency and Performance of Concurrent Interactive Database Applications

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    In many modern database applications, there is an emerging need for interactive environments where users directly manipulate the contents of the database. Graphical user interfaces (GUIs) display images of the database which must reflect a consistent up-to-date state of the data with minimum perceivable delay to the user. Moreover, the possibility of several applications concurrently displaying different views of the same database increases the overall system complexity. In this paper, we show how design, performance and concurrency issues can be addressed by adapting existing database techniques. We propose the use of suitable display schemas whose instances compose active views of the database, an extended client caching scheme which is expected to yield significant performance benefits and a locking mechanism that maintains consistency between the GUIs and the database. <BR

    Integrated Network Management of Hybrid Networks

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    We describe our collaborative efforts towards the design and implementation of a next generation integrated network management system for hybrid networks (INMS/HN). We describe the overall software architecture of the system at its current stage of development. This network management system is specifically designed to address issues relevant for complex heterogeneous networks consisting of seamlessly interoperable terrestrial and satellite networks. Network management systems are a key element for interoperability in such networks. We describe the integration of configuration management and performance management. The next step in this integration is fault management. In particular we describe the object model, issues of the Graphical User Interface (GUI), browsing tools and performance data graphical widget displays, management information database (MIB) organization issues. Several components of the system are being commercialized by Hughes Network Systems. A revised version of this report has been published in Proceedings of the 1st Conference of Commercial Development of Space, Part One, pp. 345-350, Albuquerque, New Mexico, January 7-11, 1996.</ul

    Influence of electrolyte co-additives on the performance of dye-sensitized solar cells

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    The presence of specific chemical additives in the redox electrolyte results in an efficient increase of the photovoltaic performance of dye-sensitized solar cells (DSCs). The most effective additives are 4-tert-butylpyridine (TBP), N-methylbenzimidazole (NMBI) and guanidinium thiocyanate (GuNCS) that are adsorbed onto the photoelectrode/electrolyte interface, thus shifting the semiconductor's conduction band edge and preventing recombination with triiodides. In a comparative work, we investigated in detail the action of TBP and NMBI additives in ionic liquid-based redox electrolytes with varying iodine concentrations, in order to extract the optimum additive/I2 ratio for each system. Different optimum additive/I2 ratios were determined for TBP and NMBI, despite the fact that both generally work in a similar way. Further addition of GuNCS in the optimized electrolytic media causes significant synergistic effects, the action of GuNCS being strongly influenced by the nature of the corresponding co-additive. Under the best operation conditions, power conversion efficiencies as high as 8% were obtained

    Fabrication of Porous TiO2 Hollow Spheres and Their Application in Gas Sensing

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    In this work, porous TiO2 hollow spheres with an average diameter of 100 nm and shell thickness of 20 nm were synthesized by a facile hydrothermal method with NH4HCO3 as the structure-directing agent, and the formation mechanism for this porous hollow structure was proved to be the Ostwald ripening process by tracking the morphology of the products at different reaction stages. The product was characterized by SEM, TEM, XRD and BET analyses, and the results show that the as-synthesized products are anatase phase with a high surface area up to 132.5 m2/g. Gas-sensing investigation reveals that the product possesses sensitive response to methanal gas at 200°C due to its high surface area

    Preparation of TiO2 Anatase Nanocrystals by TiCl4 Hydrolysis with Additive H2SO4

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    A new methodology was developed to synthesize uniform titania anatase nanocrystals by the hydrolysis of titanium chloride in sulfuric acid aqueous solutions at 0–90°C. The samples were characterized by Raman spectroscopy, UV-visible spectroscopy, transmission electron microscopy (TEM), electron diffraction (ED), and an Energy dispersive X-ray spectroscopy (EDS). The effects of the reaction temperature, mole ratio of SO42− to Ti4+, and the calcinations temperature on the particle size and crystal phase were investigated. Depending on the acidity, the hydrolysis temperature, and the calcination temperature, rhombic anatase nanocrystals sizes in the range of 10 nm to 50 nm were obtained. In the additive of sulfuric acid, Raman spectra and electron diffraction confirmed that the nanoparticles are composed of anatase TiO2. No other titania phases, such as rutile or brookite, were detected

    Age-dependent alterations in the inflammatory response to pulmonary challenge

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    The aging lung is increasingly susceptible to infectious disease. Changes in pulmonary physiology and function are common in older populations, and in those older than 60 years, pneumonia is the major cause of infectious death. Understanding age-related changes in the innate and adaptive immune systems, and how they affect both pulmonary and systemic responses to pulmonary challenge are critical to the development of novel therapeutic strategies for the treatment of the elderly patient. In this observational study, we examined age-associated differences in inflammatory responses to pulmonary challenge with cell wall components from Gram-positive bacteria. Thus, male Sprague-Dawley rats, aged 6 months or greater than 18 months (approximating humans of 20 and 55-65 years), were challenged, intratracheally, with lipoteichoic acid and peptidoglycan. Cellular and cytokine evaluations were performed on both bronchoalveolar lavage fluid (BAL) and plasma, 24 h post-challenge. The plasma concentration of free thyroxine, a marker of severity in non-thyroidal illness, was also evaluated. The older animals had an increased chemotactic gradient in favor of the airspaces, which was associated with a greater accumulation of neutrophils and protein. Furthermore, macrophage migration inhibitory factor (MIF), an inflammatory mediator and putative biomarker in acute lung injury, was increased in both the plasma and BAL of the older, but not young animals. Conversely, plasma free thyroxine, a natural inhibitor of MIF, was decreased in the older animals. These findings identify age-associated inflammatory/metabolic changes following pulmonary challenge that it may be possible to manipulate to improve outcome in the older, critically ill patient

    Toxic chemicals and thyroid function: hard facts and lateral thinking

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    Increasing quantities of evidence-based data incriminate a large number of environmental pollutants for toxic effects on the thyroid. Among the many chemical contaminants, halogenated organochlorines and pesticides variably affect the hypothalamic-pituitary-thyroid axis and disrupt thyroid function. PCBs and their metabolites and PBDEs bind to thyroid transport proteins, such as transthyretin, displace thyroxine, and disrupt thyroid function. Meanwhile, at the molecular level, PCB congeners may activate phosphorylation of Akt, p-Akt, and forkhead box O3a (FoxO3a) protein resulting in inhibition of the natrium/iodide symporter. Given therefore the growing concern developing around these multiple toxic chemicals today invading numerous environments and their long-term deleterious effects not only on the thyroid but also on general health, we strongly advocate their strict regulation and, moreover, their gradual reduction. A good degree of “lateral thinking”, we feel, will lead to a use of chemicals that will enhance life while concurrently carefully protecting the environment. © 2016, Springer Science+Business Media New York

    Cinacalcet as alternative treatment for Primary hyperparathyroidism: Achievements and prospects

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    Primary hyperparathyroidism (pHPT), which most frequently occurs asymptomatically, is a common endocrine disease associated with increased morbidity and mortality. The newly introduced management guidelines as well as the recent availability of the first calcimimetic offer a highly promising therapeutic option for patients with pHPT. Cinacalcet, the first available calcimimetic, increases the sensitivity of the calcium-sensing receptor (CaR) to circulating serum calcium, thereby safely reducing serum calcium and PTH concentrations in patients with mild-tomoderate pHPT, intractable disease, and also parathyroid carcinoma. Cinacalcet has proved efficient in short-and long-term controls of hypercalcemia and, though bone mineral density was not improved, the available data point to cinacalcet as the treatment of choice in non-operable patients with pHPT. These results encompass a wide spectrum of disease severity. Results are pending as to whether cinacalcet decreases mortality and morbidity in pHPT, confirmation of which would conclusively recommend this drug as a valid alternative to surgery. © Springer Science+Business Media, LLC 2011
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