Characteristics of dental fear among Arabic-speaking children: a descriptive study

BACKGROUND: Dental fear has not only been linked to poor dental health in children but also persists across the lifespan, if unaddressed, and can continue to affect oral, systemic, and psychological health. The aim of this study was to assess the factor structure of the Arabic version of the Children’s Fear Survey Schedule-Dental Subscale (CFSS-DS), and to assess the difference in factor structure between boys and girls. METHODS: Participants were 220 consecutive paediatric dental patients 6–12 years old seeking dental care at the Faculty of Dentistry, King Abdulaziz University, Saudi Arabia. Participants completed the 15-item Arabic version of the CFSS-DS questionnaire at the end of the visit. Internal consistency was assessed using Cronbach’s alpha. Factor analysis (principal components, varimax rotation) was employed to assess the factor structure of the scale. RESULTS: The Cronbach’s alpha was 0.86. Four factors with eigenvalues above 1.00 were identified, which collectively explained 64.45% of the variance. These factors were as follows: Factor 1, ‘fear of usual dental procedures’ consisted of 8 items such as ‘drilling’ and ‘having to open the mouth’, Factor 2, ‘fear of health care personnel and injections’ consisted of three items, Factor 3, ‘fear of strangers’, consisted of 2 items. Factor 4, ‘fear of general medical aspects of treatment’, consisted of 2 items. Notably, four factors of dental fear were found in girls, while five were found in boys. CONCLUSIONS: Four factors of different strength pertaining to dental fear were identified in Arabic-speaking children, indicating a simple structure. Most items loaded high on the factor related to fear of usual dental procedures. The fear-provoking aspects of dental procedures differed in boys and girls. Use of the scale may enable dentists to determine the item/s of dental treatment that a given child finds most fear-provoking and guide the child’s behaviour accordingly. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/1472-6831-14-118) contains supplementary material, which is available to authorized users

Development of a Hybrid Deterministic-Stochastic Method for Full Core Neutronics

La conception, l’analyse et le fonctionnement des réacteurs de fission nucléaire dépendent de la compréhension des vitesses des différentes réactions neutroniques dans le coeur du réacteur. C’est pour cela que la distribution du flux neutronique dans le coeur doit être estimée avec une bonne précision. Depuis la découverte de la fission nucléaire et l’introduction des réacteurs nucléaires, différentes approches déterministes et stochastiques ont été développées ayant pour but la modélisation des coeurs du réacteur ainsi que l’étude de la distribution du flux des neutrons. Les méthodes neutroniques actuelles utilisées pour simuler des réacteurs complets souffrent d’une précision relativement faible ou nécessitent des ressources en mémoire et en temps de calcul extrêmes. La conception de nouveaux réacteurs nucléaires demande de nouvelles méthodes qui soient à la fois précises et pratiques dans les applications de production pour la simulation et l’étude de la neutronique. Dans ce travail, une revue de la méthode Monte Carlo (MC) et de ses défis est incluse. La méthode MC est basée sur le suivi statistique des neutrons basés sur des distributions de probabilité physique qui le rend très proche d’un réacteur virtuel. La solution qu’elle fournit est largement acceptée comme une estimation précise de la distribution du flux neutronique bien que les coûts de calculs soient importants. Dans les études MC de coeur complet, un grand nombre de paramètres physiques sont enregistrés et la taille de l’échantillon statistique doit être très grande pour obtenir une solution avec une confiance élevée. L’extrême charge de calcul des simulations de coeur complet basées sur MC son utilisation pour des calculs de production peu pratiques et la méthode a été limitée pour l’étalonnage et la validation. La convergence lente de la source de fission, la difficulté de la coupler aux solveurs de rétroaction multiphysique et l’estimation de la variance vraie sont d’autres défis pour les études MC de coeur. L’utilisation des méthodes déterministes s’avère donc inévitables. Ces dernières sont basées sur la discrétisation de l’équation du transport dans l’espace de phase. Ces méthodes sont également fondées sur l’obtention d’une solution approximative à l’aide des méthodes numériques. Ici, un résumé de l’étude de l’équation de transport et de l’approximation des probabilités de collision est présenté. En plus de la solution du mode fondamental décrivant la répartition asymptotique du flux neutronique, l’équation de transport suppose un grand nombre de solutions qui peuvent être très utiles dans les études de la perturbation, la cartographie et la synthèse des flux neutroniques.----------Abstract Research efforts in reactor physics focus on the improvement of current analysis methods for neutronics or development of advanced ones. Recently, there is a renewed interest in stochastic simulations due to their superior accuracy and the advances in computing platforms. In particular, there is an interest in the development of hybrid stochastic deterministic methods for accelerating the inactive cycles of Monte Carlo. However, such hybrid approaches are not very efficient as the inactive cycle constitute a very small portion of the simulation. In this work, a novel hybrid method is developed and discussed. The approach combines conventional Monte Carlo with deterministic flux mapping to reduce computational costs of full core simulations. The main contributors to the computational expenses of Monte Carlo is the number of tallies scored and the number of neutron histories tracked. In the proposed hybrid method, the Monte Carlo simulation is performed with a small number of neutron histories while maintaining good confidence and scoring flux tallies on a coarse mesh. Then,the dominant modes of the transport equation and flux mapping are employed to reconstruct the neutron flux and reaction rates on a finer mesh. Application to a number of example problems show that the studied hybrid method can achieve up to 90% reduction in the computational time compared to conventional Monte Carlo while maintaining comparable accuracy

Necrotizing Fasciitis Causing Complete Femoral Vessels Necrosis and Thrombosis in an Intravenous Drug Abuser: A Case Report

Background: Intravenous drug abuse is an anciently known health and social problem worldwide. The nonsterile application of addicting drugs leads to severe life-threatening vascular complications. The femoral triangle is an easy target for this purpose. Groin necrotic fasciitis (NF) with vessel necrosis is a challenging diagnosis that requires prompt treatment. Case Report: A 44-year-old male intravenous drug user presented for a left groin pain. He was diagnosed by computed tomography scan to have necrotizing fasciitis. Urgent debridement was performed and identified infected and necrotic ruptured femoral vessels without active bleeding. Debridement with vessel ligation was performed, and delayed revascularization was planned. The patient was admitted six weeks later with a left fifth toe necrosis and delayed arterial revascularization was performed via extra-anatomic trans-obturator ilio-femoral anastomosis. The patient had a favorable follow-up.  Conclusion: NF in intravenous drug abusers should always be taken into consideration when a patient presents with groin pain and swelling. Urgent surgical control should be established. Extra-anatomical trans-obturator ilio-femoral anastomosis is a good option for revascularization

The Potential of Natural Leaf Extracts as Green Inhibitors for Mild Steel Corrosion in Hydrochloric Acid Solutions

The inhibitive and thermodynamic behavior of Abelmoschus Esculentus and Citrus Maxima leaf extracts on the corrosion of mild steel in Hydrochloric acid solutions were investigated using potentiodynamic polarization curves measurements and electrochemical impedance spectroscopy (EIS) technique. Fourier transform infrared spectroscopy (FTIR) was done to predict some suggested chemical constituent of both leaf extracts. At any given concentration Abelmoschus Esculentus leaf extract is more efficient as a corrosion inhibitor for mild steel in 0.5 M HCl solutions than Citrus Maxima leaf extract. Potentiodynamic polarization curves indicated that both leaf extracts act as mixed type inhibitors for mild steel in 0.5 M HCl solutions. The impedance responses indicated that the corrosion process takes place under activation control. The inhibition of these plant leaf extracts depends on the physical adsorption of the chemical constituents of the extracts on mild steel surface as confirmed by Scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS)

Reliability and validity of the Children’s Fear Survey Schedule-Dental Subscale for Arabic-speaking children: a cross-sectional study

BACKGROUND: Early recognition of dental fear is essential for the effective delivery of dental care. This study aimed to test the reliability and validity of the Arabic version of the Children’s Fear Survey Schedule-Dental Subscale (CFSS-DS). METHODS: A school-based sample of 1546 children was randomly recruited. The Arabic version of the CFSS-DS was completed by children during class time. The scale was tested for internal consistency and test-retest reliability. To test criterion validity, children’s behavior was assessed using the Frankl scale during dental examination, and results were compared with children’s CFSS-DS scores. To test the scale’s construct validity, scores on “fear of going to the dentist soon” were correlated with CFSS-DS scores. Factor analysis was also used. RESULTS: The Arabic version of the CFSS-DS showed high reliability regarding both test-retest reliability (intraclass correlation = 0.83, p < 0.001) and internal consistency (Cronbach’s α = 0.88). It showed good criterion validity: children with negative behavior had significantly higher fear scores (t = 13.67, p < 0.001). It also showed moderate construct validity (Spearman’s rho correlation, r = 0.53, p < 0.001). Factor analysis identified the following factors: “fear of invasive dental procedures,” “fear of less invasive dental procedures” and “fear of strangers.” CONCLUSION: The Arabic version of the CFSS-DS is a reliable and valid measure of dental fear in Arabic-speaking children. Pediatric dentists and researchers may use this validated version of the CFSS-DS to measure dental fear in Arabic-speaking children

New insights on the complex dynamics of two-phase flow in porous media under intermediate-wet conditions

Multiphase flow in porous media is important in a number of environmental and industrial applications such as soil remediation, CO2 sequestration, and enhanced oil recovery. Wetting properties control flow of immiscible fluids in porous media and fluids distribution in the pore space. In contrast to the strong and weak wet conditions, pore-scale physics of immiscible displacement under intermediate-wet conditions is less understood. This study reports the results of a series of two-dimensional high-resolution direct numerical simulations with the aim of understanding the pore-scale dynamics of two-phase immiscible fluid flow under intermediate-wet conditions. Our results show that for intermediate-wet porous media, pore geometry has a strong influence on interface dynamics, leading to co-existence of concave and convex interfaces. Intermediate wettability leads to various interfacial movements which are not identified under imbibition or drainage conditions. These pore-scale events significantly influence macro-scale flow behaviour causing the counter-intuitive decline in recovery of the defending fluid from weak imbibition to intermediate-wet conditions

Fluorescence devices for the detection of dental caries

BACKGROUND: Caries is one of the most prevalent and preventable conditions worldwide. If identified early enough then non‐invasive techniques can be applied, and therefore this review focusses on early caries involving the enamel surface of the tooth. The cornerstone of caries detection is a visual and tactile dental examination, however alternative methods of detection are available, and these include fluorescence‐based devices. There are three categories of fluorescence‐based device each primarily defined by the different wavelengths they exploit; we have labelled these groups as red, blue, and green fluorescence. These devices could support the visual examination for the detection and diagnosis of caries at an early stage of decay. OBJECTIVES: Our primary objectives were to estimate the diagnostic test accuracy of fluorescence‐based devices for the detection and diagnosis of enamel caries in children or adults. We planned to investigate the following potential sources of heterogeneity: tooth surface (occlusal, proximal, smooth surface or adjacent to a restoration); single point measurement devices versus imaging or surface assessment devices; and the prevalence of more severe disease in each study sample, at the level of caries into dentine. SEARCH METHODS: Cochrane Oral Health's Information Specialist undertook a search of the following databases: MEDLINE Ovid (1946 to 30 May 2019); Embase Ovid (1980 to 30 May 2019); US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov, to 30 May 2019); and the World Health Organization International Clinical Trials Registry Platform (to 30 May 2019). We studied reference lists as well as published systematic review articles. SELECTION CRITERIA: We included diagnostic accuracy study designs that compared a fluorescence‐based device with a reference standard. This included prospective studies that evaluated the diagnostic accuracy of single index tests and studies that directly compared two or more index tests. Studies that explicitly recruited participants with caries into dentine or frank cavitation were excluded. DATA COLLECTION AND ANALYSIS: Two review authors extracted data independently using a piloted study data extraction form based on the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS‐2). Sensitivity and specificity with 95% confidence intervals (CIs) were reported for each study. This information has been displayed as coupled forest plots and summary receiver operating characteristic (SROC) plots, displaying the sensitivity‐specificity points for each study. We estimated diagnostic accuracy using hierarchical summary receiver operating characteristic (HSROC) methods. We reported sensitivities at fixed values of specificity (median 0.78, upper quartile 0.90). MAIN RESULTS: We included a total of 133 studies, 55 did not report data in the 2 x 2 format and could not be included in the meta‐analysis. 79 studies which provided 114 datasets and evaluated 21,283 tooth surfaces were included in the meta‐analysis. There was a high risk of bias for the participant selection domain. The index test, reference standard, and flow and timing domains all showed a high proportion of studies to be at low risk of bias. Concerns regarding the applicability of the evidence were high or unclear for all domains, the highest proportion being seen in participant selection. Selective participant recruitment, poorly defined diagnostic thresholds, and in vitro studies being non‐generalisable to the clinical scenario of a routine dental examination were the main reasons for these findings. The dominance of in vitro studies also means that the information on how the results of these devices are used to support diagnosis, as opposed to pure detection, was extremely limited. There was substantial variability in the results which could not be explained by the different devices or dentition or other sources of heterogeneity that we investigated. The diagnostic odds ratio (DOR) was 14.12 (95% CI 11.17 to 17.84). The estimated sensitivity, at a fixed median specificity of 0.78, was 0.70 (95% CI 0.64 to 0.75). In a hypothetical cohort of 1000 tooth sites or surfaces, with a prevalence of enamel caries of 57%, obtained from the included studies, the estimated sensitivity of 0.70 and specificity of 0.78 would result in 171 missed tooth sites or surfaces with enamel caries (false negatives) and 95 incorrectly classed as having early caries (false positives). We used meta‐regression to compare the accuracy of the different devices for red fluorescence (84 datasets, 14,514 tooth sites), blue fluorescence (21 datasets, 3429 tooth sites), and green fluorescence (9 datasets, 3340 tooth sites) devices. Initially, we allowed threshold, shape, and accuracy to vary according to device type by including covariates in the model. Allowing consistency of shape, removal of the covariates for accuracy had only a negligible effect (Chi(2) = 3.91, degrees of freedom (df) = 2, P = 0.14). Despite the relatively large volume of evidence we rated the certainty of the evidence as low, downgraded two levels in total, for risk of bias due to limitations in the design and conduct of the included studies, indirectness arising from the high number of in vitro studies, and inconsistency due to the substantial variability of results. AUTHORS' CONCLUSIONS: There is considerable variation in the performance of these fluorescence‐based devices that could not be explained by the different wavelengths of the devices assessed, participant, or study characteristics. Blue and green fluorescence‐based devices appeared to outperform red fluorescence‐based devices but this difference was not supported by the results of a formal statistical comparison. The evidence base was considerable, but we were only able to include 79 studies out of 133 in the meta‐analysis as estimates of sensitivity or specificity values or both could not be extracted or derived. In terms of applicability, any future studies should be carried out in a clinical setting, where difficulties of caries assessment within the oral cavity include plaque, staining, and restorations. Other considerations include the potential of fluorescence devices to be used in combination with other technologies and comparative diagnostic accuracy studies