Search

Quantitative determination of palaeochannel geometry and hydraulics from point bar deposits requires an understanding of the interaction between channel-bend migration, temporal and spatial variation of point bar geometry and facies, and outcrop orientation. This interaction is modeled with the aid of a computer program which predicts three-dimensional (3-D) geometry and grain size variation of point bars. Synthetic deposits are produced for the cases of down-valley bend migration and/or increase in channel-bend sinuosity. Two-dimensional (2-D) cross-section in varying orientations across these simulated deposits display lateral-accretion bedset surface geometry, and variation in man bedset grain size and local palaeocurrent orientation. Most cross-sections show point bar deposits thickening away from the meander-belt axis due to a lateral progression from thinner bend-exit deposits to thicker bend-apex deposits (caused by down-valley channel translation), and/or due to a progression from thinner low sinuosity deposits to thicker high sinuosity deposits caused by channel bend expansion. In association with this lateral thickening, bedset surfaces become steeper and more convex upwards while the variation in mean grain size up bedsets commonly increases. Down-valley point bar translation allows preservation only of deposits formed downstream of the band apex, and produces characteristic fining upwards sequences. Marked lateral and vertical variation in palaeocurrent directions due to varying channel orientation relative to a given cross-section are also predicted. These results indicate a need in palaeochannel reconstructions, for a more detailed examination of 3-D variations in bedset surface geometry, palaeocurrent orientation and grain size distribution within and between bedsets of laterally accreted sediment. [ABSTRACT FROM AUTHOR]

• Dropcast 9,10-anthracenedicarboxylic acid (AnDCA) and vapor-deposited octanethiol form separate domains as octanethiol displaces AnDCA on Au(111). • Exposure to UV light causes octanethiol to change phase from close-packed standing phase to two distinct striped phases. • Domains of AnDCA were observed after exposure to UV light. Sequential adsorption of 9,10-anthracenedicarboxylic acid (AnDCA) and 1-octanethiol create a multicomponent self-assembled monolayer on Au(111). The presence of AnDCA does not alter the size of close-packed octanethiol domains, but can be found in separate close-packed domains. Successive exposure to 375 nm ultraviolet radiation causes organizational rearrangement of the adsorbed components. Sections of close-packed up-right phase, ϕ , octanethiol with (3 × 3)R30 ∘ packing and a density of 21.6 Å 2 /molecule or 4.63 molecules/nm 2 transition to a combination of lower density striped β and (5 × 2) phase with a density of 35.9 Å 2 /molecule or 2.79 molecules/nm 2. Small domains of AnDCA exhibit a packing density of 0.90 molecules/nm 2 or 110 Å 2 /molecule after 20 minutes of UV exposure. After 60 minutes of UV exposure, AnDCA exhibits a similar packing density of 0.91 molecules/nm 2 or 110 Å 2 /molecule. Ultimately the domain boundaries become less defined as the β and (5 × 2) packing dominates the self-assembled monolayer, and adjacent areas of longer-range ordered hydrogen-bonded regions of AnDCA are observed. [ABSTRACT FROM AUTHOR]

A clinical prediction rule represents a distillation of measurable features, usually by regression modelling. Competing interests We are the authors of the meta-analysis that compared Centor's score with McIsaac's score. REFERENCES 1 Willis BH, Coomar D, Baragilly M. Comparison of Centor and McIsaac scores in primary care: a meta-analysis over multiple thresholds. [Extracted from the article]

Objective: Previous research has demonstrated that individual risk of mental illness is associated with individual, co-resident, and household risk factors. However, modelling the overall effect of these risk factors presents several methodological challenges. In this study we apply a multilevel structural equation model (MSEM) to address some of these challenges and the impact of the different determinants when measuring mental health risk.Study Design and Setting: Two thousand, one hundred forty-three individuals aged 16 and over from 888 households were analysed based on the Household Survey for England-2014 dataset. We applied MSEM to simultaneously measure and identify psychiatric morbidity determinants while accounting for the dependency among individuals within the same household and the measurement errors.Results: Younger age, female gender, non-working status, headship of the household, having no close relationship with other people, having history of mental illness and obesity were all significant (p < 0.01) individual risk factors for psychiatric morbidity. A previous history of mental illness in the co-residents, living in a deprived household, and a lack of closeness in relationships among residents were also significant predictors. Model fit indices showed a very good model specification (CFI = 0.987, TLI = 0.980, RMSEA = 0.023, GFI = 0.992).Conclusion: Measuring and addressing mental health determinants should consider not only an individual's characteristics but also the co-residents and the households in which they live. [ABSTRACT FROM AUTHOR]

Cluster analysis of functional data is finding increasing application in the field of medical research and statistics. Here we introduce a functional version of the forward search methodology for the purpose of functional data clustering. The proposed forward search algorithm is based on the functional spatial ranks and is a data-driven non-parametric method. It does not require any preprocessing functional data steps, nor does it require any dimension reduction before clustering. The Forward Search Based on Functional Spatial Rank (FSFSR) algorithm identifies the number of clusters in the curves and provides the basis for the accurate assignment of each curve to its cluster. We apply it to three simulated datasets and two real medical datasets, and compare it with six other standard methods. Based on both simulated and real data, the FSFSR algorithm identifies the correct number of clusters. Furthermore, when compared with six standard methods used for clustering and classification, it records the lowest misclassification rate. We conclude that the FSFSR algorithm has the potential to cluster and classify functional data. [ABSTRACT FROM AUTHOR]

Background: Diagnostic meta-analyses on caries detection methods should assist practitioners in their daily practice. However, conventional meta-analysis estimates may be inapplicable due to differences in test conduct, applied thresholds and assessed population between settings. Our aim was to demonstrate the impact of tailored meta-analysis of visual and radiographic caries detection to different settings using setting-specific routine data. Methods: Published systematic reviews and meta-analyses on the accuracy of visual and radiographic caries detection were used. In two settings (a private practice in Germany and a public health clinic in Egypt), routine data of a total of 100 (n = 50/practice) consecutive 12–14 year-olds were collected. Test-positive rates of visual and radiographic detection for initial and advanced carious lesions on occlusal or proximal surfaces of molars were used to tailor meta-analyses. If prevalence data were available, these were also used for tailoring. Results: From the original reviews, 210 and 100 heterogeneous studies on visual and radiographic caries detection were included in our meta-analyses. For radiographic detection, sensitivity and specificity estimates derived from conventional and tailored meta-analysis were similar. For visual detection of advanced occlusal carious lesions, the conventional meta-analysis yielded a sensitivity and specificity (95% CI) of 64.6% (57–71) and 90.9% (88–93), whereas the tailored estimates for Egypt were 75.1% (70–81) and 84.9% (82–89), respectively, and 43.7% (37–51) and 96.5% (95–97) for Germany, respectively. Conclusion: Conventional test accuracy meta-analyses may yield aggregate estimates which are inapplicable to specific settings. Routine data may be used to produce a meta-analysis estimate which is tailored to the setting and thereby improving its applicability. [ABSTRACT FROM AUTHOR]

An important question for clinicians appraising a meta-analysis is: are the findings likely to be valid in their own practice-does the reported effect accurately represent the effect that would occur in their own clinical population? To this end we advance the concept of statistical validity-where the parameter being estimated equals the corresponding parameter for a new independent study. Using a simple ('leave-one-out') cross-validation technique, we demonstrate how we may test meta-analysis estimates for statistical validity using a new validation statistic, Vn, and derive its distribution. We compare this with the usual approach of investigating heterogeneity in meta-analyses and demonstrate the link between statistical validity and homogeneity. Using a simulation study, the properties of Vn and the Q statistic are compared for univariate random effects meta-analysis and a tailored meta-regression model, where information from the setting (included as model covariates) is used to calibrate the summary estimate to the setting of application. Their properties are found to be similar when there are 50 studies or more, but for fewer studies Vn has greater power but a higher type 1 error rate than Q. The power and type 1 error rate of Vn are also shown to depend on the within-study variance, between-study variance, study sample size, and the number of studies in the meta-analysis. Finally, we apply Vn to two published meta-analyses and conclude that it usefully augments standard methods when deciding upon the likely validity of summary meta-analysis estimates in clinical practice. © 2017 The Authors. Statistics in Medicine published by John Wiley & Sons Ltd. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "The Diagnostic Value of Symptoms for Colorectal Cancer in Primary Care: A Systematic Review," by M. Astin and colleagues which appeared in the 2011 issue of the periodical.

Background: To reach global and national goals for maternal and child mortality, countries must identify vulnerable populations, which includes sex workers and their children. The objective of this study was to identify and describe maternal deaths of female sex workers in Cambodia and causes of death among their children.Methods: A convenience sample of female sex workers were recruited by local NGOs that provide support to sex workers. We modified the maternal mortality section of the 2010 Cambodia Demographic and Health Survey and collected reports of all deaths of female sex workers. For each death we ask the 'sisterhood' methodology questions to identify maternal deaths. For child deaths we asked each mother who reported the death of a child about the cause of death. We also asked all participants about the cause of deaths of children of other female sex workers.Results: We interviewed 271 female sex workers in the four largest Cambodian cities between May and September 2013. Participants reported 32 deaths of other female sex workers that met criteria for maternal death. The most common reported causes of maternal deaths were abortion (n = 13;40%) and HIV (n = 5;16%). Participants report deaths of 8 of their children and 50 deaths of children of other female sex workers. HIV was the reported cause of death for 13 (36%) children under age five.Conclusion: This is the first report of maternal deaths of sex workers in Cambodia or any other country. This modification of the sisterhood methodology has not been validated and did not allow us to calculate maternal mortality rates so the results are not generalizable, however these deaths may represent unrecognized maternal deaths in Cambodia. The results also indicate that children of sex workers in Cambodia are at risk of HIV and may not be accessing treatment. These issues require additional studies but in the meantime we must assure that sex workers in Cambodia and their children have access to quality health services. [ABSTRACT FROM AUTHOR]

Presents a letter to the editor on a case of idiopathic primary pan intraventricular hemorrhage in a child.

Examines the late presentation of tethered spinal cord in adult patient. Different presentation of tethered cord syndrome in adults and children; Importance of diagnosis and intervention to prevent irreversible deficits; Symptoms of tethered cord syndrome in adults.