1,834 research outputs found

    Towards the ultimate regime in Rayleigh-Darcy convection

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    Numerical simulations are used to probe Rayleigh-Darcy convection in fluid-saturated porous media towards the ultimate regime. The present three-dimensional dataset, up to Rayleigh-Darcy number, suggests that the appropriate scaling of the Nusselt number is, fitting the computed data for. Extrapolation of current predictions to the ultimate linear regime yields the asymptotic law, about less than indicated in previous studies. Upon examination of the flow structures near the boundaries, we confirm previous indications of small flow cells hierarchically nesting into supercells, and we show evidence that the supercells at the boundary are the footprints of the megaplumes that dominate the interior part of the flow. The present findings pave the way for more accurate modelling of geophysical systems, with special reference to geological sequestration

    Strong Rayleigh-Darcy convection regime in three-dimensional porous media

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    We perform large-scale numerical simulations to study Rayleigh-Darcy convection in three-dimensional fluid-saturated porous media up to Rayleigh-Darcy number. At these large values of, the flow is dominated by large columnar structures - called megaplumes - which span the entire height of the domain. Near the boundaries, the flow is hierarchically organized, with fine-scale structures interacting and nesting to form larger-scale structures called supercells. We observe that the correlation between the flow structure in the core of the domain and at the boundaries decreases only slightly for increasing, and remains rather high even at the largest considered here. This confirms that supercells are the boundary footprint of megaplumes dominating the core of the domain. In agreement with available literature predictions, we show that the thickness of the thermal boundary layer scales very well with the Nusselt number as. Measurements of the mean wavenumber - inverse of the mean length scale - in the core of the flow support the scaling, in very good agreement with theoretical and numerical predictions. Interestingly, the behaviour of the mean wavenumber near the boundaries scales as, which is distinguishably different from the presumed linear behaviour. We hypothesize that a linear behaviour can only be observed in the ultimate regime, which we argue to set in only at in excess of, whereas a sublinear behaviour is recovered at more modest. The present results are expected to help the development of long desired reliable models to predict the large- and fine-scale structure of Rayleigh-Darcy convection in the high- regime typically encountered in geophysical processes, such as for instance in geological carbon dioxide sequestration

    Cardiorespiratory fitness and sports activities in children and adolescents with solitary functioning kidney

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    Background: An increasing number of children with chronic disease require a complete medical examination to be able to practice physical activity. Particularly children with solitary functioning kidney (SFK) need an accurate functional evaluation to perform sports activities safely. The aim of our study was to evaluate the influence of regular physical activity on the cardiorespiratory function of children with solitary functioning kidney. Method: Twenty-nine patients with congenital SFK, mean age 13.9 ± 5.0 years, and 36 controls (C), mean age 13.8 ± 3.7 years, underwent a cardiorespiratory assessment with spirometry and maximal cardiopulmonary exercise testing. All subjects were divided in two groups: sedentary (S) and trained (T) patients, by means of a standardized questionnaire about their weekly physical activity. Results: We found that mean values of maximal oxygen consumption (VO2max) and exercise time (ET) were higher in T subjects than in S subjects. Particularly SFK-T presented mean values of VO2max similar to C-T and significantly higher than C-S (SFK-T: 44.7 ± 6.3 vs C-S: 37.8 ± 3.7 ml/min/kg; p < 0.0008). We also found significantly higher mean values of ET (minutes) in minutes in SFK-T than C-S subjects (SFK-T: 12.9 ± 1.6 vs C-S: 10.8 ± 2.5 min; p <0.02). Conclusion: Our study showed that regular moderate/high level of physical activity improve aerobic capacity (VO2max) and exercise tolerance in congenital SFK patients without increasing the risks for cardiovascular accidents and accordingly sports activities should be strongly encouraged in SFK patients to maximize health benefit

    Clinical evaluation of seven tumour markers in lung cancer diagnosis: can any combination improve the results?

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    In this study we compared the diagnostic utility of: (1) neuron-specific enolase (NSE); (2) squamous cell carcinoma antigen (SCC); (3) carcinoembryonic antigen (CEA); and (4) cytokeratin markers (CYFRA 21-1, TPA, TPM, TPS) in patients with small-cell lung cancer (SCLC) (21 cases) and non-small-cell lung cancer (94 cases). For comparison we also studied 66 patients with benign lung diseases and nine with pleural mesothelioma. NSE levels in SCLC patients were significantly higher than those in all the other groups studied. No significant variations were found among the SCC levels in all groups. CEA levels in patients with adenocarcinoma were significantly higher than those in all other groups studied. CYFRA 21-1 serum levels significantly increased in patients with squamous cell carcinoma and mesothelioma, while TPA, TPS and TPM increased in patients with lung cancer irrespective of the histological type. In patients with SCLC, high levels of all markers except SCC were found when the disease was extensive. In patients with non-SCLC, the highest levels of all tumour markers were usually found in those with advanced disease, although CYFRA 21-1 gave a sensitivity of 44% when a specificity of 95% was fixed in stage I non-SCLC patients. An analysis of receiver operating characteristic curves revealed that the highest diagnostic accuracies in distinguishing benign from malignant lung diseases were achieved with TPM (81%), CYFRA 21-1 (72%), CEA (78%) or TPA (78%) when using cut-off values of 46 Ul-1, 3.0 micrograms l-1, 2.0 micrograms l-1 and 75 Ul-1 respectively. When all patients were considered, the combined evaluation of more than one marker did not significantly improve the results obtained with TPM alone. However, taking into consideration the fact that CYFRA 21-1 is the most sensitive index of early lung tumours and that its combined determination with TPM did not worsen the overall sensitivity and specificity of the latter, the combined use of these two markers may be suggested as a useful took for the diagnosis of lung tumours

    Effect of meteorological and agronomic factors on maize grain contamination by fumonisin

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    Fumonisins are toxic secondary metabolites produced by fungi such as F.verticilloides. Maize is commonly colonized by several spoilage fungi both in pre- and post-harvest conditions. Field infection prevention is the best solution to contain contamination, using practices aimed at restricting plant stress and limiting the propagation of the disease. This work is focused on understanding the effect of environmental factors on the production of fumonisins in Friuli Venezia Giulia (NE Italy) on maize crops. The analysis has been performed on a dataset covering a period of 14 years (from 2000 to 2013), recording fumonisins contamination and daily meteorological data (air temperature, RH, Rain, Wind speed) for 13 different drying plants and for three different harvest times (early, medium and late). The drying plants collect grain production from an area of about 70.000-100.000 ha. Data were analyzed by full factorial ANOVA and a multiple regression approach was performed using STATA and SEMoLa software. ANOVA test pointed out a significant effect of factors \u201cyear\u201d and \u201charvest time\u201d (p<0.01) for fumonisin content. Instead, location had no significant effect. The best regression model (R2=0. 65, 2... observation) detected a significant correlation between fumonisin concentration and meteorological data in the period from 15th to 31st July. High fumonisin contents were positively correlated with daily thermal excursion, minimum temperature and wet conditions in this period. Silk drying and harvest time resulted as the key factors to contain and study fumonisins contamination in maize. Results will be used to implement a more complex dynamic model

    Web conversations about complementary and alternative medicines and cancer: Content and sentiment analysis

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    Background: The use of complementary and alternative medicine (CAM) among cancer patients is widespread and mostly self-administrated. Today, one of the most relevant topics is the nondisclosure of CAM use to doctors. This general lack of communication exposes patients to dangerous behaviors and to less reliable information channels, such as the Web. The Italian context scarcely differs from this trend. Today, we are able to mine and analyze systematically the unstructured information available in the Web, to get an insight of people's opinions, beliefs, and rumors concerning health topics. Objective: Our aim was to analyze Italian Web conversations about CAM, identifying the most relevant Web sources, therapies, and diseases and measure the related sentiment. Methods: Data have been collected using the Web Intelligence tool ifMONITOR. The workflow consisted of 6 phases: (1) eligibility criteria definition for the ifMONITOR search profile; (2) creation of a CAM terminology database; (3) generic Web search and automatic filtering, the results have been manually revised to refine the search profile, and stored in the ifMONITOR database; (4) automatic classification using the CAM database terms; (5) selection of the final sample and manual sentiment analysis using a 1-5 score range; (6) manual indexing of the Web sources and CAM therapies type retrieved. Descriptive univariate statistics were computed for each item: absolute frequency, percentage, central tendency (mean sentiment score [MSS]), and variability (standard variation Ò). Results: Overall, 212 Web sources, 423 Web documents, and 868 opinions have been retrieved. The overall sentiment measured tends to a good score (3.6 of 5). Quite a high polarization in the opinions of the conversation partaking emerged from standard variation analysis (δ≥1). In total, 126 of 212 (59.4%) Web sources retrieved were nonhealth-related. Facebook (89; 21%) and Yahoo Answers (41; 9.7%) were the most relevant. In total, 94 CAM therapies have been retrieved. Most belong to the "biologically based therapies or nutrition" category: 339 of 868 opinions (39.1%), showing an MSS of 3.9 (δ=0.83). Within nutrition, "diets" collected 154 opinions (18.4%) with an MSS of 3.8 (δ=0.87); "food as CAM" overall collected 112 opinions (12.8%) with a MSS of 4 (δ=0.68). Excluding diets and food, the most discussed CAM therapy is the controversial Italian "Di Bella multitherapy" with 102 opinions (11.8%) with an MSS of 3.4 (δ=1.21). Breast cancer was the most mentioned disease: 81 opinions of 868. Conclusions: Conversations about CAM and cancer are ubiquitous. There is a great concern about the biologically based therapies, perceived as harmless and useful, under-rating all risks related to dangerous interactions or malnutrition. Our results can be useful to doctors to be aware of the implications of these beliefs for the clinical practice. Web conversation exploitation could be a strategy to gain insights of people's perspective for other controversial topics

    Innovative Virtual Lab for Improving Safety and Port Operations

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    Computer simulation makes it possible to reproduce real systems and processes in a synthetic environment. In this way virtual analysis turn to be possible and it complex scenarios are suitable to be simulated. In the proposed paper is presented a port system where to study the behavior respect operations and accidents and to consider interaction among multiple players. The simulation is applied to create a Virtual Lab able to evaluate and investigate the development of new procedures, contingency plans during crises. The development of models to be used in simulations is clearly a critical aspect, since the consistency of the simulation depend on the quality of the models and their interaction; in this case the authors used their experience in the field to guarantee a successful Verification and Validation. In this case study, models are used for simulations of phenomena related to port accidents and crises with particular attention to dispersion system of liquid contaminant on sea surface and dispersion of toxic gases into atmosphere. These models have been tested in the Alacres2 simulator in order to create as an effective tool to observe and study the evolution and impact of dangerous situations, as well as a decision-making support to define response plans crises

    Use of complementary and alternative medicine (CAM) in cancer patients. An italian multicenter survey

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    INTRODUCTION: Complementary and Alternative Medicine (CAM) include a wide range of products (herbs, vitamins, minerals, and probiotics) and medical practices, developed outside of the mainstream Western medicine. Patients with cancer are more likely to resort to CAM first or then in their disease history; the potential side effects as well as the costs of such practices are largely underestimated. PATIENTS AND METHOD: We conducted a descriptive survey in five Italian hospitals involving 468 patients with different malignancies. The survey consisted of a forty-two question questionnaire, patients were eligible if they were Italian-speaking and receiving an anticancer treatment at the time of the survey or had received an anticancer treatment no more than three years before participating in the survey. RESULTS: Of our patients, 48.9% said they use or have recently used CAM. The univariate analysis showed that female gender, high education, receiving treatment in a highly specialized institute and receiving chemotherapy are associated with CAM use; at the multivariate analysis high education (Odds Ratio, (OR): 1.96 95% Confidence Interval, CI, 1.27-3.05) and receiving treatment in a specialized cancer center (OR: 2.75 95% CI, 1.53-4.94) were confirmed as risk factors for CAM use. CONCLUSION: Roughly half of our patients receiving treatment for cancer use CAM. It is necessary that health professional explore the use of CAM with their cancer patients, educate them about potentially beneficial therapies in light of the limited available evidence of effectiveness, and work towards an integrated model of health-care provision
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