565 research outputs found

    On the tuning of a wave-energy driven oscillating-water-column seawater pump to polychromatic waves

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    Performance of wave-energy devices of the oscillating water column (OWC) type is greatly enhanced when a resonant condition with the forcing waves is maintained. The natural frequency of such systems can in general be tuned to resonate with a given wave forcing frequency. In this paper we address the tuning of an OWC sea-water pump to polychromatic waves. We report results of wave tank experiments, which were conducted with a scale model of the pump. Also, a numerical solution for the pump equations, which were proven in previous work to successfully describe its behavior when driven by monochromatic waves, is tested with various polychromatic wave spectra. Results of the numerical model forced by the wave trains measured in the wave tank experiments are used to develop a tuning criterion for the sea-water pump.Comment: 21 pages, 14 figure

    Preliminary definitions for the sonographic features of synovitis in children

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    Objectives Musculoskeletal ultrasonography (US) has the potential to be an important tool in the assessment of disease activity in childhood arthritides. To assess pathology, clear definitions for synovitis need to be developed first. The aim of this study was to develop and validate these definitions through an international consensus process. Methods The decision on which US techniques to use, the components to be included in the definitions as well as the final wording were developed by 31 ultrasound experts in a consensus process. A Likert scale of 1-5 with 1 indicating complete disagreement and 5 complete agreement was used. A minimum of 80% of the experts scoring 4 or 5 was required for final approval. The definitions were then validated on 120 standardized US images of the wrist, MCP and tibiotalar joints displaying various degrees of synovitis at various ages. Results B-Mode and Doppler should be used for assessing synovitis in children. A US definition of the various components (i.e. synovial hypertrophy, effusion and Doppler signal within the synovium) was developed. The definition was validated on still images with a median of 89% (range 80-100) of participants scoring it as 4 or 5 on a Likert scale. Conclusions US definitions of synovitis and its elementary components covering the entire pediatric age range were successfully developed through a Delphi process and validated in a web-based still images exercise. These results provide the basis for the standardized US assessment of synovitis in clinical practice and research

    One-Factor-at-a-Time versus Designed Experiments

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    The Web will kill them all: new media, digital utopia, and political struggle in the Italian 5-Star Movement

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    This article examines the role of discourses about new media technology and the Web in the rise of the 5-Star Movement (Movimento 5 Stelle, or M5S) in Italy. Founded by comedian and activist Beppe Grillo and Web entrepreneur Gianrobe rto Casaleggio in 2009, this movement succeeded in becoming the second largest party at t he 2013 national elections in Italy. This article aims to discuss how elements of digital uto pia and Web-centric discourses have been inserted into the movement’s political message, and how the construction of the Web as a myth has shaped the movement’s discourse and political p ractice. The 5-Star Movement is compared and contrasted with other social and political move ments in Western countries which have displayed a similar emphasis on new media, such as the Occupy movement, the Indignados movement, and the Pirate Parties in Sweden and Germ any. By adopting and mutating cyber- utopian discourses from the so-called Californian i deology, the movement symbolically identifies itself with the Web. The traditional political esta blishment is associated with “old” media (television, radio, and the printed press), and rep resented as a “walking dead,” doomed to be superseded and buried by a Web-based direct democra cy

    Continuous cultivation of photosynthetic microorganisms: approaches, applications and future trends

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    The possibility of using photosynthetic microorganisms, such as cyanobacteria and microalgae, for converting light and carbon dioxide into valuable biochemical products has raised the need for new cost-efficient processes ensuring a constant product quality. Food, feed, biofuels, cosmetics and pharmaceutics are among the sectors that can profit from the application of photosynthetic microorganisms. Biomass growth in a photobioreactor is a complex process influenced by multiple parameters, such as photosynthetic light capture and attenuation, nutrient uptake, photobioreactor hydrodynamics and gas-liquid mass transfer. In order to optimize productivity while keeping a standard product quality, a permanent control of the main cultivation parameters is necessary, where the continuous cultivation has shown to be the best option. However it is of utmost importance to recognize the singularity of continuous cultivation of cyanobacteria and microalgae due to their dependence on light availability and intensity. In this sense, this review provides comprehensive information on recent breakthroughs and possible future trends regarding technological and process improvements in continuous cultivation systems of microalgae and cyanobacteria, that will directly affect cost-effectiveness and product quality standardization. An overview of the various applications, techniques and equipment (with special emphasis on photobioreactors) in continuous cultivation of microalgae and cyanobacteria are presented. Additionally, mathematical modelling, feasibility, economics as well as the applicability of continuous cultivation into large-scale operation, are discussed.This research work was supported by the grant SFRH/BPD/98694/2013 (Bruno Fernandes) from Fundacao para a Ciencia e a Tecnologia (Portugal). The authors thank the FCT Strategic Project PEst-OE/EQB/LA0023/2013. The authors also thank the Project "BioInd Biotechnology and Bioengineering for improved Industrial and Agro-Food processes, REF. NORTE-07-0124-FEDER-000028" Co-funded by the Programa Operacional Regional do Norte (ON.2-O Novo Norte), QREN, FEDE

    Consensus-based recommendations for the management of uveitis associated with juvenile idiopathic arthritis:the SHARE initiative

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    BACKGROUND: In 2012, a European initiative called Single Hub and Access point for pediatric Rheumatology in Europe (SHARE) was launched to optimise and disseminate diagnostic and management regimens in Europe for children and young adults with rheumatic diseases. Juvenile idiopathic arthritis (JIA) is the most common rheumatic disease in children and uveitis is possibly its most devastating extra-articular manifestation. Evidence-based guidelines are sparse and management is mostly based on physicians' experience. Consequently, treatment practices differ widely, within and between nations. OBJECTIVES: To provide recommendations for the diagnosis and treatment of JIA-associated uveitis. METHODS: Recommendations were developed by an evidence-informed consensus process using the European League Against Rheumatism standard operating procedures. A committee was constituted, consisting of nine experienced paediatric rheumatologists and three experts in ophthalmology from Europe. Recommendations derived from a validated systematic literature review were evaluated by an Expert Committee and subsequently discussed at two consensus meetings using nominal group techniques. Recommendations were accepted if >80% agreement was reached (including all three ophthalmologists). RESULTS: In total, 22 recommendations were accepted (with >80% agreement among experts): 3 on diagnosis, 5 on disease activity measurements, 12 on treatment and 2 on future recommendations. CONCLUSIONS: The SHARE initiative aims to identify best practices for treatment of patients suffering from JIA-associated uveitis. Within this remit, recommendations for the diagnosis and treatment of JIA-associated uveitis have been formulated by an evidence-informed consensus process to suggest a standard of care for JIA-associated uveitis patients throughout Europe

    Robust optimization framework for process parameter and tolerance design

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    This article introduces a framework for including different uncertainties at the chemical plant design stage. Through an integrated robust optimization approach and problem formulation, equipment, operating, control, and quality costs are simultaneously taken into account, leading to system, parameter, and tolerance design. Rather than using single pointwise solutions in the decision space, operating windows leading to overall best performance are identified and defined. Such windows and their width allow us to point out control needs and goals at a very early stage of plant design. Two small-scale case studies (for a CSTR and a batch distillation column) provide enough evidence to support the practicality of the optimization framework: the robust solutions found are different and much better than the corresponding solutions obtained with the fully deterministic optimization paradigms

    Scales and structure of frontal adjustment and freshwater export in a region of freshwater influence

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    Sea surface temperature satellite imagery and a regional hydrodynamic model are used to investigate the variability and structure of the Liverpool Bay thermohaline front. A statistically based water mass classification technique is used to locate the front in both data sets. The front moves between 5 and 35 km in response to spring-neap changes in tidal mixing, an adjustment that is much greater than at other shelf-sea fronts. Superimposed on top of this fortnightly cycle are semi-diurnal movements of 5-10 km driven by flood and ebb tidal currents. Seasonal variability in the freshwater discharge and the density difference between buoyant inflow and more saline Irish Sea water give rise to two different dynamical regimes. During winter, when cold inflow reduces the buoyancy of the plume, a bottom-advected front develops. Over the summer, when warm river water provides additional buoyancy, a surface-advected plume detaches from the bottom and propagates much larger distances across the bay. Decoupled from near-bed processes, the position of the surface front is more variable. Fortnightly stratification and re-mixing over large areas of Liverpool Bay is a potentially important mechanism by which freshwater, and its nutrient and pollutant loads, are exported from the coastal plume system. Based on length scales estimated from model and satellite data, the erosion of post-neap stratification is estimated to be responsible for exporting approximately 19% of the fresh estuarine discharge annually entering the system. Although the baroclinic residual circulation makes a more significant contribution to freshwater fluxes, the episodic nature of the spring-neap cycle may have important implications for biogeochemical cycles within the ba
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