4,103 research outputs found

    Interfacial velocity estimation in highly aerated stepped spillway flows with a single tip fibre optical probe and Artificial Neural Networks

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    peer reviewedAir-water flows can be found in different engineering applications: from nuclear engineering to huge hydraulic structures. In this paper, a single tip fibre optical probe has been used to record high frequency (over 1 MHz) phase functions at different locations of a stepped spillway. These phase functions have been related to the interfacial velocities by means of Artificial Neural Networks (ANN) and the measurements of a classical double tip conductivity probe. Special attention has been put to the input selection and the ANN dimensions. Finally, ANN have shown to be able to link the signal rising times and plateau shapes to the air-water interfacial velocity

    Laser-generated plasma as a spectroscopic light source

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    Laser generated plasma as spectroscopic light sourc

    On the estimation of free-surface turbulence using ultrasonic sensors

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    Accurate determination of free-surface dynamics has attracted much research attention during the past decade and has important applications in many environmental and water related areas. In this study, the free-surface dynamics in several turbulent flows commonly found in nature were investigated using a synchronised setup consisting of an ultrasonic sensor and a high-speed video camera. Basic sensor capabilities were examined in dry conditions to allow for a better characterisation of the present sensor model. The ultrasonic sensor was found to adequately reproduce free-surface dynamics up to the second order, especially in two-dimensional scenarios with the most energetic modes in the low frequency range. The sensor frequency response was satisfactory in the sub-20 Hz band, and its signal quality may be further improved by low-pass filtering prior to digitisation. The application of the USS to characterise entrapped air in high-velocity flows is also discussed

    A high performance LIA-based interface for battery powered sensing devices

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    This paper proposes a battery-compatible electronic interface based on a general purpose lock-in amplifier (LIA) capable of recovering input signals up to the MHz range. The core is a novel ASIC fabricated in 1.8 V 0.18 µm CMOS technology, which contains a dual-phase analog lock-in amplifier consisting of carefully designed building blocks to allow configurability over a wide frequency range while maintaining low power consumption. It operates using square input signals. Hence, for battery-operated microcontrolled systems, where square reference and exciting signals can be generated by the embedded microcontroller, the system benefits from intrinsic advantages such as simplicity, versatility and reduction in power and size. Experimental results confirm the signal recovery capability with signal-to-noise power ratios down to -39 dB with relative errors below 0.07% up to 1 MHz. Furthermore, the system has been successfully tested measuring the response of a microcantilever-based resonant sensor, achieving similar results with better power-bandwidth trade-off compared to other LIAs based on commercial off-the-shelf (COTS) components and commercial LIA equipment

    Isolated Sleep Paralysis: Clinical Features, Perception of Aetiology, Prevention and Disruption Strategies in a Large International Sample

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    Study objectives Isolated sleep paralysis is a benign but frightening condition characterised by a temporary inability to move at sleep onset or upon awakening. Despite the prevalence of this condition, little is known concerning its clinical features, associated demographic characteristics, and prevention as well as disruption strategies. Methods An online cross-sectional study was conducted. The sample comprised 3523 participants who had reported at least one lifetime episode of ISP and 3288 participants without a lifetime episode. Participants answered a survey including questions about sleep quality, sleep paralysis, and sleep paralysis prevention/disruption techniques. Results A total of 6811 participants were investigated (mean age = 46.9, SD = 15.4, age range = 18–89, 66.1% female). Those who reported experiencing ISP at least once during their lives reported longer sleep onset latencies, shorter sleep duration, and greater insomnia symptoms. Females (vs. male) and younger (vs. older) participants were more likely to experience ISP. Significant fear during episodes was reported by 76.0% of the participants. Most people (63.3%) who experienced ISP believed it to be caused by ‘something in the brain’. A minority endorsed supernatural causes (7.1%). Five prevention strategies (e.g., changing sleep position, adjusting sleep patterns) with at least 60.0% effectiveness, and five disruption strategies (e.g., physical/bodily action, making noise) with varying degrees of effectiveness (ranging from 29.5 to 61.8) were identified through open-ended responses. Conclusions ISP is associated with shorter sleep duration, longer sleep onset latency, and greater insomnia symptoms. The multiple prevention and disruption techniques identified in this study support existing treatment approaches and may inform subsequent treatment development. Implications for current diagnostic criteria are discussed

    Associations between sleep variables and ostensibly paranormal experiences and paranormal beliefs: A scoping review

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    Night-time is a period of great significance for many people who report paranormal experiences. However, there is limited understanding of the associations between sleep variables and seemingly paranormal experiences and/or beliefs. The aim of this review is to improve our understanding of these associations while unifying a currently fragmented literature-base into a structured, practical review. In this pre-registered scoping review, we searched for relevant studies in MEDLINE (PubMed), PsycINFO (EBSCO), Web of Science and EMBASE using terms related to sleep and ostensibly paranormal experiences and beliefs. Forty-four studies met all inclusion criteria. All were cross-sectional and most investigated sleep paralysis and/or lucid dreaming in relation to ostensibly paranormal experiences and paranormal beliefs. Overall, there were positive associations between many sleep variables (including sleep paralysis, lucid dreams, nightmares, and hypnagogic hallucinations) and ostensibly paranormal experiences and paranormal beliefs (including those of ghosts, spirits, and near-death experiences). The findings of this review have potential clinical implications such as reducing misdiagnosis and treatment development and provide foundations for further research. Our findings also highlight the importance of understanding why so many people report ‘things that go bump in the night’

    Five pillars for stakeholder analyses in sustainability transformations: The global case of phosphorus.

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    Phosphorus is a critical agricultural nutrient and a major pollutant in waterbodies due to inefficient use. In the form of rock phosphate it is a finite global commodity vulnerable to price shocks and sourcing challenges. Transforming toward sustainable phosphorus management involves local to global stakeholders. Conventional readings of stakeholders may not reflect system complexity leaving it difficult to see stakeholder roles in transformations. We attempt to remedy this issue with a novel stakeholder analysis method based on five qualitative pillars: stakeholder agency, system roles, power and influence, alignment to the problem, and transformational potential. We argue that our approach suits case studies of individual stakeholders, stakeholder groups, and organisations with relationships to sustainability challenges

    Obesity-associated gut microbiota is enriched in Lactobacillus reuteri and depleted in Bifidobacterium animalis and Methanobrevibacter smithii

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    Background: Obesity is associated with increased health risk and has been associated with alterations in bacterial gut microbiota, with mainly a reduction in Bacteroidetes, but few data exist at the genus and species level. It has been reported that the Lactobacillus and Bifidobacterium genus representatives may have a critical role in weight regulation as an anti-obesity effect in experimental models and humans, or as a growth-promoter effect in agriculture depending on the strains. Objectives and methods: To confirm reported gut alterations and test whether Lactobacillus or Bifidobacterium species found in the human gut are associated with obesity or lean status, we analyzed the stools of 68 obese and 47 controls targeting Firmicutes, Bacteroidetes, Methanobrevibacter smithii, Lactococcus lactis, Bifidobacterium animalis and seven species of Lactobacillus by quantitative PCR (qPCR) and culture on a Lactobacillus-selective medium. Findings: In qPCR, B. animalis (odds ratio (OR) 0.63; 95% confidence interval (CI) 0.39-1.01; P = 0.056) and M. smithii (OR = 0.76; 95% CI 0.59-0.97; P = 0.03) were associated with normal weight whereas Lactobacillus reuteri (OR = 1.79; 95% CI 1.03-3.10; P = 0.04) was associated with obesity. Conclusion: The gut microbiota associated with human obesity is depleted in M. smithii. Some Bifidobacterium or Lactobacillus species were associated with normal weight (B. animalis) while others (L. reuteri) were associated with obesity. Therefore, gut microbiota composition at the species level is related to body weight and obesity, which might be of relevance for further studies and the management of obesity. These results must be considered cautiously because it is the first study to date that links specific species of Lactobacillus with obesity in humans. International Journal of Obesity (2012) 36, 817-825; doi:10.1038/ijo.2011.153; published online 9 August 201

    Dissemination and survival of commercial wine yeast in the vineyard: a large-scale, three years study

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    The use of commercial wine yeast strains as starters has been extensively generalised over the past two decades. In this study, a large-scale sampling plan was devised over a period of three years in six different vineyards to evaluate the dynamics and survival of industrial yeast strains in the vineyard. A total of 198 grape samples were collected at various distances from the wineries, before and after harvest, and yeast strains isolated after spontaneous fermentation were subsequently identified by molecular methods. Among 3780 yeast strains identified, 296 isolates had a genetic profile identical to that of commercial yeast strains. For a large majority (94%), these strains were recovered at very close proximity to the winery (10-200m). Commercial strains were mostly found in the post harvest samples, reflecting immediate dissemination. Analysis of population variations from year to year indicated that permanent implantation of commercial strains in the vineyard did not occur, but instead that these strains were subject to natural fluctuations of periodical appearance/disappearance like autochthonous strains. Our data show that dissemination of commercial yeast in the vineyard is restricted to short distances and limited periods of times and is largely favoured by the presence of water runoff.ENOSAFE (Nº 762, Programa AGRO, medida 8.1) and the grant nº 657 C2 from the cooperation agreement between the Portuguese Institute for International Scientific and Technological Cooperation (ICCTI) and the French Embassy in Lisbon and the Marie Curie Fellowship of the European Community programme of Quality of Life under Contract QLK4-CT-2001-51873

    CARACTERÍSTICAS Y APLICACIONES DE SOFTWARE EN DIETÉTICA Y NUTRICIÓN PARA SU USO EN POBLACIÓNES SANAS Y PACIENTES CRÍTICOS.

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    The aim of this work is to start an introduction to software characteristics and applications in dietetics and nutrition in the Spanish language. There are very much nutrition programs and nutritional calculators in the web of uncertain application due either to its doubtful database or to their “non-existent” authors. That’s why the computer programs with the highest reliability besides an optimum quality-price ratio have been chosen. This software shows a very high trustworthiness and handling just because of its scientific-technical professionalism, and it can be used according to the case, from a personal use to a very specialized one, as in the case of researcher or health professional workers. Its characteristics, as well as its applications are described in a sufficiently concise way to start to study the use of these informatics tools.Con el siguiente trabajo se ha tratado de iniciar una introducción a las características y aplicaciones de software en dietética y nutrición en el idioma castellano. Existen en la webincontable número de programas en nutrición y calculadoras nutricionales de muy insegura aplicación debido a su dudosa base de datos o a su inexistencia de autores. Para ello se han seleccionado los programas informáticos que presentan la mayor fiabilidad así como una relación calidad-precio óptima. Debido a la profesionalidad científico-técnica muestran un manejo y una fiabilidad muy alta, pudiendo ser utilizados dependiendo del caso, desde un uso personal hasta un uso más especializado como es el del profesional investigador y/o sanitario. Sus características así como aplicaciones son descritas de forma suficiente y concisa para iniciarse en el manejo de dichas herramientas informáticas
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