260 research outputs found

    Partially Identified Prevalence Estimation under Misclassification using the Kappa Coefficient

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    We discuss a new strategy for prevalence estimation in the presence of misclassification. Our method is applicable when misclassification probabilities are unknown but independent replicate measurements are available. This yields the kappa coefficient, which indicates the agreement between the two measurements. From this information, a direct correction for misclassification is not feasible due to non-identifiability. However, it is possible to derive estimation intervals relying on the concept of partial identification. These intervals give interesting insights into possible bias due to misclassification. Furthermore, confidence intervals can be constructed. Our method is illustrated in several theoretical scenarios and in an example from oral health, where prevalence estimation of caries in children is the issue

    Investigation of the Structural Coating Homogeneity in Open‐Porous Nickel/Polyurethane Hybrid Foams Produced by Flow‐Controlled Electrodeposition

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    In today’s world, the saving of raw materials together with the reduction of emissions necessitates the development of new, customized and applicationoriented materials which fulfill various requirements at the same time. Metal foams achieve a high strength combined with low weight. The present work deals with a flow-controlled production technique for hybrid foams to deposit a nanocrystalline nickel (Ni) layer on pre-treated, open-porous polyurethane (PU) foams. The analysis of the resulting coating thickness distributions with gravimetric and microscopic methods shows the qualitative and quantitative influences on the local deposition by varying the process parameters. For the first time, the coating thickness distribution of Ni/PU hybrid foams is investigated regarding the analysis of a global and local homogeneity. The comparison of experimental data with simulated flow velocity profiles leads to an estimation of the correlation between flow velocity, anode distance, and coating thickness distribution, which represents the mass transport. The correlations show, that the coating process is strongly controlled by the electrolyte’s flow velocity as well as the distribution of the electric field

    Partially identified prevalence estimation under misclassification using the kappa coefficient

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    AbstractWe discuss prevalence estimation under misclassification. That is we are concerned with the estimation of a proportion of units having a certain property (being diseased, showing deviant behavior, etc.) from a random sample when the true variable of interest cannot be observed, but a related proxy variable (e.g. the outcome of a diagnostic test) is available. If the misclassification probabilities were known then unbiased prevalence estimation would be possible. We focus on the frequent case where the misclassification probabilities are unknown but two independent replicate measurements have been taken. While in the traditional precise probabilistic framework a correction from this information is not possible due to non-identifiability, the imprecise probability methodology of partial identification and systematic sensitivity analysis allows to obtain valuable insights into possible bias due to misclassification. We derive tight identification intervals and corresponding confidence regions for the true prevalence, based on the often reported kappa coefficient, which condenses the information of the replicates by measuring agreement between the two measurements. Our method is illustrated in several theoretical scenarios and in an example from oral health on prevalence of caries in children

    The group-based social skills training SOSTA-FRA in children and adolescents with high functioning autism spectrum disorder - study protocol of the randomised, multi-centre controlled SOSTA - net trial

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    Background: Group-based social skills training (SST) has repeatedly been recommended as treatment of choice in high-functioning autism spectrum disorder (HFASD). To date, no sufficiently powered randomised controlled trial has been performed to establish efficacy and safety of SST in children and adolescents with HFASD. In this randomised, multi-centre, controlled trial with 220 children and adolescents with HFASD it is hypothesized, that add-on group-based SST using the 12 weeks manualised SOSTA–FRA program will result in improved social responsiveness (measured by the parent rated social responsiveness scale, SRS) compared to treatment as usual (TAU). It is further expected, that parent and self reported anxiety and depressive symptoms will decline and pro-social behaviour will increase in the treatment group. A neurophysiological study in the Frankfurt HFASD subgroup will be performed pre- and post treatment to assess changes in neural function induced by SST versus TAU. Methods/design: The SOSTA – net trial is designed as a prospective, randomised, multi-centre, controlled trial with two parallel groups. The primary outcome is change in SRS score directly after the intervention and at 3 months follow-up. Several secondary outcome measures are also obtained. The target sample consists of 220 individuals with ASD, included at the six study centres. Discussion: This study is currently one of the largest trials on SST in children and adolescents with HFASD worldwide. Compared to recent randomised controlled studies, our study shows several advantages with regard to in- and exclusion criteria, study methods, and the therapeutic approach chosen, which can be easily implemented in non-university-based clinical settings. Trial registration: ISRCTN94863788 – SOSTA – net: Group-based social skills training in children and adolescents with high functioning autism spectrum disorder

    Social Experiences of Adolescents with High Functioning Autism (HFA) and/or Asperger Syndrome (AS) - Their Perceptions and Their Views of Their Caregivers: An Exploratory Study

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    This study used the Grounded Theory methodology to investigate, through an exploratory manner, the social experiences of adolescents with High Functioning Autism (HFA) and/or Asperger\u27s Syndrome (AS) as shared by the adolescents themselves, and the views of their parent/caregivers regarding this experience. In addition the adolescents and parents shared their thoughts on having and managing a diagnosis of HFA/AS and the current adaptive behaviors of the adolescents. Seven adolescents and their respective parent/caregivers participated in video-taped paired interviews. The themes emergent from the interviews regarding the diagnosis of HFA/AS for the parents were: rejection, feeling blamed, emotional toll and management of the disorder. For the adolescents emergent themes were: indifference, distancing from diagnosis through use of third person plural and singular, and perceived positives and negatives of having HFA/AS. The emergent themes and patterns regarding the experiences of the parent caring for an adolescents with HFA/AS along with the adolescents\u27 shared thoughts on the diagnosis illuminated the overt worry of the caregivers juxtaposed to a seemingly indifferent response by their adolescents. Information shared regarding the adolescents adaptive behaviors revealed that the adolescents participating in this study, although all of average and above average intelligence, lacked independent with an overall reliance on mother. From different vantage points the adolescents and their caregivers shared corresponding themes of social experiences: restricted social circle, object-oriented connections rather than emotional ties, isolation, both self-sort and imposed and outsider. The results of this study were discussed in terms of the objectives of this study, and its limitations

    Intermolecular London Dispersion Interactions of Azobenzene Switches for Tuning Molecular Solar Thermal Energy Storage Systems

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    The performance of molecular solar thermal energy storage systems (MOST) depends amongst others on the amount of energy stored. Azobenzenes have been investigated as high-potential materials for MOST applications. In the present study it could be shown that intermolecular attractive London dispersion interactions stabilize the (E)-isomer in bisazobenzene that is linked by different alkyl bridges. Differential scanning calorimetry (DSC) measurements revealed, that this interaction leads to an increased storage energy per azo-unit of more than 3 kcal/mol compared to the parent azobenzene. The origin of this effect has been supported by computation as well as X-ray analysis. In the solid state structure attractive London dispersion interactions between the C−H of the alkyl bridge and the π-system of the azobenzene could be clearly assigned. This concept will be highly useful in designing more effective MOST systems in the future
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