463 research outputs found

    Conflating Relevance with Practical Significance and Other Issues: Commentary on Sen, Smith, and Van Note’s “Statistical Significance Versus Practical Importance in Information Systems Research”

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    Expanding on the current debate on the issues of statistical and practical significance in information systems research, where the article by Sen, Smith, and Van Note is a recent contribution, this commentary cautions against conflating relevance with practical significance. We emphasize that relevance is 1) about the real-world usefulness of research findings rather than their impressiveness for the researcher audience, 2) an essential quality of research spanning beyond its findings and not merely limited to statistical studies, and 3) determined by nonacademics rather than academics. We also comment on other aspects of the article by Sen et al., such as the term “practical importance,” the treatment of effect size measures, and the presentation of “marginal effects.

    The structure of gravel-bed flow with intermediate submergence: a laboratory study

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    The paper reports an experimental study of the flow structure over an immobile gravel bed in open channel at intermediate submergence, with particular focus on the near-bed region. The experiments consisted of velocity measurements using three-component (stereoscopic) Particle Image Velocimetry (PIV) in near-bed horizontal plane and two-component PIV in three vertical planes that covered three distinctly different hydraulic scenarios where the ratio of flow depth to roughness height (i.e., relative submergence) changes from 7.5 to 10.8. Detailed velocity measurements were supplemented with fine-scale bed elevation data obtained with a laser scanner. The data revealed longitudinal low-momentum and high-momentum "strips'' in the time-averaged velocity field, likely induced by secondary currents. This depth-scale pattern was superimposed with particle-scale patches of flow heterogeneity induced by gravel particle protrusions. A similar picture emerged when considering second-order velocity moments. The interaction between the flow field and gravel-bed protrusions is assessed using cross correlations of velocity components and bed elevations in a horizontal plane just above gravel particle crests. The cross correlations suggest that upward and downward fluid motions are mainly associated with upstream-facing and lee sides of particles, respectively. Results also show that the relative submergence affects the turbulence intensity profiles for vertical velocity over the whole flow depth, while only a weak effect, limited to the near-bed region, is noticed for streamwise velocity component. The approximation of mean velocity profiles with a logarithmic formula reveals that log-profile parameters depend on relative submergence, highlighting inapplicability of a conventional "universal'' logarithmic law for gravel-bed flows with intermediate submergence

    Association between Fluoride Exposure and Blood pressure

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    Objectives: This study investigated whether fluoride was associated with an increased prevalence of high blood pressure (BP) among adolescents in the United States. Methods: The study sample consisted of 2015–2016 National Health and Nutrition Examination Survey participants aged 13–17 years. Independent-samples t-tests, Chi-square tests, and regression models were used to analyze the data. Results: A total of 814 participants met the study criteria. The findings showed that the proportion of patients with high levels of water or plasma fluoride in the high BP group was higher than that in the normal BP group. However, after adjusting for sociodemographic covariates, neither water nor plasma fluoride levels were significantly associated with a high BP. Conclusions: This study did not find an association between either water or plasma fluoride levels and high BP. Further study is needed to exclude a dose dependent effect at higher levels of fluoride

    Do agents dream of abiding by the rules?:Learning norms via behavioral exploration and sparse human supervision

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    In recent years, several normative systems have been presented in the literature. Relying on formal methods, these systems support the encoding of legal rules into machine-readable formats, enabling, e.g. to check whether a certain workflow satisfies or agents abide by these rules. However, not all rules can be easily expressed (see for instance the unclear boundaries between tax planning and tax avoidance). The paper introduces a framework for norm identification and norm induction that automates the formalization of norms about non-compliant behavior by exploring the behavioral space via simulation, and integrating inputs from humans via active learning. The proposed problem formulation sets also a bridge between AI &amp; law and more general branches of AI concerned by the adaptation of artificial agents to human directives.</p

    Immunological and histopathological changes in Penaeus semisulcatus challenged with Vibrio harveyi

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    Two-hundred and sixty five green tiger shrimp juveniles (Penaeus semisulcatus) with the average weight of 7-12g were collected from Helleh farms in Bushehr province and transported to Iran Shrimp Research Center of Bushehr in October, 2009. The juveniles were acclimated for two weeks. The experiment was designed in three treatments (named 3, 4 and 5) and two controls (named 1 and 2) in triplicate with 15 shrimp in each repetition prepared of glass aquarium. All the treatments and repetitions were exposed to Vibrio harveyi (NCBI: GU974342.1). The concentrations of the treatments were 10^8,10^6 and 10^4 CFU ml^-1 in individual containers dedicated for each mentioned treatment (3, 4 and 5, respectively). The controls prepared with no any bacteria and fully filled with chlorinated and UV treated sea water were named 1 and 2 respectively. The hemolymph were withdrawn from abdominal segments of samples for measuring THC and TPC evaluation at designed hours (2, 6, 12, 24, 48, 96, 144, 192 and 240). The shrimp samples were also fixed in Davidson fixative for histopathological studies. The results showed that the difference of THC value between controls and group 3 during 12 till 96 hours of experiment was significant (P 0.05) between group 5 and control groups of THC. The data showed that differences of TPC value between control groups during 24 to 96 hours were significant (P< 0.05), whereas the differences between controls with groups 4 and 5 during 48 to 144 hours and 192 hours, were significant (P< 0.05) respectively. TPC and THC were observed with an increase in the concentration of bacteria and passing the time as inverse bell shape procedure. In histopathology, gills showed melanization and color changed to brown and black. The hepatopancreas cells revealed necrosis and vacuolization of B, E, R and F cells. The bolitas ball and bacterial colonization was observed in the intestine. Our results showed that Vibrio harveyi with 10^8 and 10^6 cell/ml decreased immunity factors such as THC and TPC. The histopathological changes increased with increasing the concentration of bacterial level. This finding can be used for assessing the health of shrimp culture and prevention of vibriosis

    A National Study Exploring the Association Between Fluoride Levels and Dental Fluorosis

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    Importance: While the effects of fluoride on health have been widely researched, fewer high-quality studies examine the association of fluoride levels in water and dental fluorosis. Objective: To investigate the association between fluoride exposure from drinking water and dental fluorosis. Design, setting, and participants: This cross-sectional study used the 2013-2014 and 2015-2016 National Health and Nutrition Examination Survey (NHANES) data (January 1, 2013, through December 31, 2016). NHANES uses a complex sampling technique to develop nationally representative sample estimates of the US population that consists of interviews and physical assessments. Children and adolescents aged 6 to 15 years were included because NHANES contains their data for all 3 forms of fluoride measures: plasma fluoride levels, water levels of fluoride, and dietary fluoride supplementation. Data were analyzed from January 1 to April 30, 2023. Exposures: Water and plasma fluoride levels were measured by laboratory personnel. Dietary fluoride supplement data were self-reported. Main outcomes and measures: The Dean's Fluorosis Index was used to evaluate fluorosis status for each tooth. The dental fluorosis severity value was based on the second most affected tooth. Independent variables included plasma and water fluoride concentrations and dietary fluoride supplementation. An independent samples t test was used to compare fluoride exposures between groups, and Pearson correlation assessed the association between plasma and water fluoride levels. To assess whether fluoride exposures were associated with dental fluorosis, logistic regression analyses were conducted. Results: There were 1543 participants in the 2013-2014 NHANES cycle (weighted proportion male, 51.9%; mean [SD] age, 11.0 [2.7] years) and 1452 in the 2015-2016 cycle (weighted proportion male, 52.6%; mean [SD] age, 11.1 [2.8] years). A weighted 87.3% exhibited some degree of fluorosis in the 2013-2014 cycle and 68.2% in the 2015-2016 cycle. Higher fluoride levels in water and plasma were significantly associated with higher odds of dental fluorosis (adjusted odds ratios, 2.378 [95% CI, 2.372-2.383] in the 2013-2014 cycle and 1.568 [95% CI, 1.564-1.571] in the 2015-2016 cycle). Conclusions and relevance: The findings of this cross-sectional study suggest that exposure to higher concentrations of fluoride in water and having higher plasma levels of fluoride were associated with a greater risk of dental fluorosis. Further research can help policy makers develop policies that balance substantial caries prevention with the risk of dental fluorosis.</p

    Shallow geothermal energy potential for heating and cooling of buildings with regeneration under climate change scenarios

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    Shallow ground-source heat pumps (GSHPs) are a promising technology for contributing to the decarbonisation of the energy sector. In heating-dominated climates, the combined use of GSHPs for both heating and cooling increases their technical potential, defined as the maximum energy that can be exchanged with the ground, as the re-injection of excess heat from space cooling leads to a seasonal regeneration of the ground. This paper proposes a new approach to quantify the technical potential of GSHPs, accounting for effects of seasonal regeneration, and to estimate the useful energy to supply building energy demands at regional scale. The useful energy is obtained for direct heat exchange and for district heating and cooling (DHC) under several scenarios for climate change and market penetration levels of cooling systems. The case study in western Switzerland suggests that seasonal regeneration allows for annual maximum heat extraction densities above 300 kWh/m2 at heat injection densities above 330 kWh/m2. Results also show that GSHPs may cover up to 55% of heating demand while covering 57% of service-sector cooling demand for individual GSHPs in 2050, which increases to around 85% with DHC. The regional-scale results may serve to inform decision making on strategic areas for installing GSHPs

    Covid-19 mobility restrictions: impacts on urban air quality and health

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    In 2020, Covid-19-related mobility restrictions resulted in the most extensive human-made air-quality changes ever recorded. The changes in mobility are quantified in terms of outdoor air pollution (concentrations of PM2.5 and NO2) and the associated health impacts in four UK cities (Greater London, Cardiff, Edinburgh and Belfast). After applying a weather-corrected machine learning (ML) technique, all four cities show NO2 and PM2.5 concentration anomalies in 2020 when compared with the ML-predicted values for that year. The NO2 anomalies are –21% for Greater London, –19% for Cardiff, –27% for Belfast and –41% for Edinburgh. The PM2.5 anomalies are 7% for Greater London, –1% for Cardiff, –15% for Edinburgh, –14% for Belfast. All the negative anomalies, which indicate air pollution at a lower level than expected from the weather conditions, are attributable to the mobility restrictions imposed by the Covid-19 lockdowns. Spearman rank-order correlations show a significant correlation between the lowering of NO2 levels and reduction in public transport (p < 0.05) and driving (p < 0.05), which is associated with a decline in NO2-attributable mortality. These positive effects of the mobility restrictions on public health can be used to evaluate policies for improved outdoor air quality

    Factors Associated with Periodontitis in Younger Individuals: A Scoping Review

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    Periodontitis is a disease that affects many young adults, and if left untreated, it can have lasting and permanent effects on an individual’s oral health. The purpose of this scoping review was to review the recent literature to identify factors that place young individuals at risk of stage II or III periodontitis. Using the PRISMA guidelines for scoping reviews, three databases were systematically searched for peer-reviewed human studies published in English that investigated risk factors associated with stage II and/or III periodontitis in individuals less than 40 years of age. This review excluded abstracts, literature reviews, including narrative, scoping, and systematic reviews and meta-analyses, conference proceedings, letters to the editor, and editorials. The authors then extracted data from the relevant studies using a predefined form to summarize the aims, design, results, risk factors examined, and the type and severity of periodontitis. Among a total of 2676 articles screened, only three articles met the review’s inclusion criteria. Of these articles, one was a longitudinal case-control study and two were cross-sectional studies. Identified risk factors associated with stage II or III periodontitis included self-reported bleeding when brushing, low bone mineral density, being overweight, and smoking in young adults. Of note, only three studies met the inclusion criteria, suggesting a gap in the research literature
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