2,424 research outputs found

    Creeping flow solution of the Leidenfrost phenomenon

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    Creeping flow solution of Leidenfrost phenomenon by use of Navier-Stokes, continuity, and energy equation

    A generalized correlation of vaporization times of drops in film boiling on a flat plate

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    Vaporization time correlations for drops in leidenfrost state of film boiling on flat plat

    Somatic hybridisation using a double mutant of Nicotiana tabacum

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    Leaf mesophyll protoplasts of a nitrate reductase deficient, streptomycin resistant double mutant of Nicotiana tabacum were fused with cell suspension protoplasts of wild type N. rustica. Hybrid colonies were selected for nitrate reductase proficiency and streptomycin resistance. Green, actively proliferating colonies were recovered in the selection medium. Eleven of twenty green colonies, transferred to regeneration medium, produced plants. Regenerated plants were analysed for their vegetative and floral characteristics, Fraction 1 protein polypeptide composition and leaf esterases. All the eleven regenerants were nuclear somatic hybrids possessing the chloroplast of the N. tabacum parent. By developing a double mutant with a negative (auxotrophic) and a positive (resistance) selection marker in a species of interest, this species can be hybridised by somatic cell fusion with wild type species lacking selectable markers

    'I Sat Filling in This Form While Smoking and It Was Divine'. An Analysis of Free-Text Comments from Smokers Who Report They Have No Intention of Quitting in the Next Six Months

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    INTRODUCTION: Smokers unmotivated to quit are neglected by smoking cessation research. Free-text comment analysis is a potentially useful way to gain insight into this group's beliefs. AIMS: To analyse the free-text comments provided by smokers unmotivated to quit as part of a randomized controlled trial of computer-tailored feedback for smoking cessation. METHOD: A random sample of 58,660 smokers were sent a smoking behaviour questionnaire (SBQ). The responses and follow-up outcomes of those providing free-text comments were compared to those who did not to assess the representativeness of the former group of smokers. The comments of participants unmotivated to quit (631) were thematically analysed. RESULTS: Those who provided a comment differed from those who did not on variables including education level and quit attempts at six-month follow-up. Emergent themes included; justification of smoking and restricting smoking instead of quitting. CONCLUSIONS: The findings illustrate the value of free-text comments in identifying issues important to respondents. The identified themes highlight areas for future research in smokers unmotivated to quit including cutting down as a path to quitting and explicit messages regarding the inability of positive health behaviours to balance out the negative impact of smoking on health. Trial registration: Current Controlled Trials ISRCTN05385712

    DYNAMICS OF SELECTED TOWER DIVE TAKE-OFFS

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    The mechanics of platform diving, unlike those of springboard diving. have not been investigated to any great degree. Unlike the springboard, the platform provides no elastic energy to enhance the diver's momentum. At take-off the diver must achieve sufficient linear momentum to ensure the necessary height and distance to travel safely away from the platform and sufficient angular momentum to complete the required number of rotations about the transverse axis. Ground reaction forces (GRF) developed during contact with the diving platform and the body position of the diver at take-off define the magnitude and direction of the diver's momentum. The nature of rotations in springboard diving has been reported by many researchers and coaches (Fairbanks, 1963; Batterman, 1968; Stroup and Bushnell, 1969)...-tn most cases, it was felt that body Jean at take-off determined the number of rotations in the dive. Golden (1984) found that body lean at take-off increases according to the number of rotations being performed. Miller (1984) found that the height obtained in springboard diving was predominantly due to the action of the lower extremities as they accelera ted the trunk upwards. Although a number of investigators have studied springboard diving, there is an apparent Jack of information pertaining to platform diving. Furthermore, it seemes necessary to study the nature of increased rotations in platform diving. The purpose of this study was, therefore, to investigate the kinetics and kinematics of platform dive take-offs in which a rotation or multiple rotations occurred

    Factors associated with the suppressiveness of sugarcane soils to plant-parasitic nematodes

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    Observations in three Australian sugarcane fields suggested that the soil just under the trash blanket (the covering of crop residue that remains on the soil surface after crops are harvested) was suppressive to plant-parasitic nematodes. Roots were concentrated in this upper layer of soil but plant-parasitic nematode populations were relatively low and roots showed few signs of nematode damage. Root biomass was much lower 15 cm further down the soil profile, where root health was poor and populations of plant-parasitic nematodes were 3-5 times higher than near the soil surface. A bioassay in which Radopholus similis (a nematode that does not occur in sugarcane soils) was inoculated into heat-sterilized and untreated soils, confirmed that biological factors were limiting nematode populations in some of the soils, with soil from 0-2 cm much more suppressive than soil from 15-17 cm. Surface soil from one site was highly suppressive, as only 16% of R. similis recoverable from heated soil were retrieved from this soil after 8 days. Numerous soil chemical, biochemical, and biological properties were measured, and non-linear regression analysis identified two major groups of factors that were significantly associated with suppressiveness. One group reflected the amount of organic matter in soil (total C, total N, and labile C) and the other was associated with the size of the free-living nematode community (total numbers of free-living nematodes, and numbers of plant associates, bacterial feeders, fungal feeders, and carnivores). These results suggested that suppressiveness was biologically mediated and was sustained by C inputs from crop residues and roots. Since nematode-trapping fungi in the test soils could not be quantified using traditional dilution plating methods, their possible role as suppressive agents was assessed by generating TRFLP profiles with Orbiliales-specific primers, and by sequencing cloned PCR products. Although the molecular data were obtained from a limited number of samples, the level of suppression was significantly correlated to the number of Orbiliales clone groups and was also related to the number of Orbiliales species and TRFs, suggesting that this group of fungi may have been one of the suppressive factors operating in the test soils

    Assessing the fidelity of delivery of an intervention to increase attendance at the English Stop Smoking Services

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    Background: Implementation fidelity refers to the extent to which a proposed intervention is enacted as designed and is necessary to determine how much the intervention in question is the primary mechanism in any changes observed. Start2quit was a randomised controlled trial that aimed to improve attendance at the English Stop Smoking Service (SSS). The complex intervention combining computer-tailored personal risk letters and no-commitment (“taster”) sessions aimed at encouraging attendance at the SSS doubled attendance at the SSS and significantly increased abstinence rates, although attendance and abstinence varied between participating SSSs. Assessment of the fidelity of the delivery of the taster sessions to the protocol was embedded into the trial and is the focus of this study. / Methods: Eighteen SSSs participated in the study. Taster sessions were delivered by SSS advisors in the area. Of the 131 sessions delivered, 93 (71 %) were recorded and 41 (31.3 %) were selected for transcription and analysis. The taster session protocol contained 73 specified behaviours, which were independently classified into component behaviour change techniques (BCTs) using an established taxonomy for smoking cessation. All transcripts were coded by two authors with 25 % additionally coded by a third. The fidelity of each taster session was expressed as the percentage of overall protocol-specified behaviours that were delivered. Adherence to each BCT was measured as the number of behaviours applied by the advisors within each BCT divided by the total number classified within each. / Results: Adherence of protocol-specified behaviours was relatively high (median 71.23 %), though there was considerable variation (28.76 to 95.89 %) in individual sessions. Median fidelity to specific BCTs across sessions also varied from 50 to 100 %. Shorter sessions, sessions run jointly by two advisors, by female advisors, or by advisors aged 45 to 54 were associated with higher levels of adherence. There was no association between adherence and subsequent attendance at the SSS. / Conclusions: These results suggest that the delivery of the intervention of this study is not likely to have been impacted by issues of fidelity. As such, we can have greater confidence that variability in the main outcome is not due to variability in SSS advisor adherence to the protocol of the taster sessions. / Trial registration: Current Controlled Trials ISRCTN7656191

    Calibrating ensemble reliability whilst preserving spatial structure

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    Ensemble forecasts aim to improve decision-making by predicting a set of possible outcomes. Ideally, these would provide probabilities which are both sharp and reliable. In practice, the models, data assimilation and ensemble perturbation systems are all imperfect, leading to deficiencies in the predicted probabilities. This paper presents an ensemble post-processing scheme which directly targets local reliability, calibrating both climatology and ensemble dispersion in one coherent operation. It makes minimal assumptions about the underlying statistical distributions, aiming to extract as much information as possible from the original dynamic forecasts and support statistically awkward variables such as precipitation. The output is a set of ensemble members preserving the spatial, temporal and inter-variable structure from the raw forecasts, which should be beneficial to downstream applications such as hydrological models. The calibration is tested on three leading 15-d ensemble systems, and their aggregation into a simple multimodel ensemble. Results are presented for 12 h, 1° scale over Europe for a range of surface variables, including precipitation. The scheme is very effective at removing unreliability from the raw forecasts, whilst generally preserving or improving statistical resolution. In most cases, these benefits extend to the rarest events at each location within the 2-yr verification period. The reliability and resolution are generally equivalent or superior to those achieved using a Local Quantile-Quantile Transform, an established calibration method which generalises bias correction. The value of preserving spatial structure is demonstrated by the fact that 3×3 averages derived from grid-scale precipitation calibration perform almost as well as direct calibration at 3×3 scale, and much better than a similar test neglecting the spatial relationships. Some remaining issues are discussed regarding the finite size of the output ensemble, variables such as sea-level pressure which are very reliable to start with, and the best way to handle derived variables such as dewpoint depression
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