Domain Of Validity Research Articles

Validation of Multisource Feedback in Assessing Medical Performance: A Systematic Review.

Over the past 10 years, a number of systematic reviews have evaluated the validity of multisource feedback (MSF) to assess and quality-assure medical practice. The purpose of this study is to synthesize the results from existing reviews to provide a holistic overview of the validity evidence. This review identified eight systematic reviews evaluating the validity of MSF published between January 2006 and October 2016. Using a standardized data extraction form, two independent reviewers extracted study characteristics. A framework of validation developed by the American Psychological Association was used to appraise the validity evidence within each systematic review. In terms of validity evidence, each of the eight reviews demonstrated evidence across at least one domain of the American Psychological Association's validity framework. Evidence of assessment validity within the domains of "internal structure" and "relationship to other variables" has been well established. However, the domains of content validity (ie, ensuring that MSF tools measure what they are intended to measure); consequential validity (ie, evidence of the intended or unintended consequences MSF assessments may have on participants or wider society), and response process validity (ie, the process of standardization and quality control in the delivery and completion of assessments) remain limited. Evidence for the validity of MSF has, across a number of domains, been well established. However, the size and quality of the existing evidence remains variable. To determine the extent to which MSF is considered a valid instrument to assess medical performance, future research is required to determine the following: (1) how best to design and deliver MSF assessments that address the identified limitations of existing tools and (2) how to ensure that involvement within MSF supports positive changes in practice. Such research is integral if MSF is to continue to inform medical performance and subsequent improvements in the quality and safety of patient care.

High Z neoclassical transport: Application and limitation of analytical formulae for modelling JET experimental parameters

Heavy impurities, such as tungsten (W), can exhibit strongly poloidally asymmetric density profiles in rotating or radio frequency heated plasmas. In the metallic environment of JET, the poloidal asymmetry of tungsten enhances its neoclassical transport up to an order of magnitude, so that neoclassical convection dominates over turbulent transport in the core. Accounting for asymmetries in neoclassical transport is hence necessary in the integrated modeling framework. The neoclassical drift kinetic code, NEO [E. Belli and J. Candy, Plasma Phys. Controlled Fusion P50, 095010 (2008)], includes the impact of poloidal asymmetries on W transport. However, the computational cost required to run NEO slows down significantly integrated modeling. A previous analytical formulation to describe heavy impurity neoclassical transport in the presence of poloidal asymmetries in specific collisional regimes [C. Angioni and P. Helander, Plasma Phys. Controlled Fusion 56, 124001 (2014)] is compared in this work to numerical results from NEO. Within the domain of validity of the formula, the factor for reducing the temperature screening due to poloidal asymmetries had to be empirically adjusted. After adjustment, the modified formula can reproduce NEO results outside of its definition domain, with some limitations: When main ions are in the banana regime, the formula reproduces NEO results whatever the collisionality regime of impurities, provided that the poloidal asymmetry is not too large. However, for very strong poloidal asymmetries, agreement requires impurities in the Pfirsch-Schlüter regime. Within the JETTO integrated transport code, the analytical formula combined with the poloidally symmetric neoclassical code NCLASS [W. A. Houlberg et al., Phys. Plasmas 4, 3230 (1997)] predicts the same tungsten profile as NEO in certain cases, while saving a factor of one thousand in computer time, which can be useful in scoping studies. The parametric dependencies of the temperature screening reduction due to poloidal asymmetries would need to be better characterised for this faster model to be extended to a more general applicability.

Comparison of the Standard Differencing With the Exponential Differencing for the FDTD Method in Lossy Media

This paper compares the standard and exponential differencing's on time used with the finite-difference time-domain (FDTD) method in such lossy media as conducting media and plasma media. It is shown that the performances of the two differencing's are quite close, concerning both the accuracy of the computed results and the domain of validity of the FDTD method in lossy media. There is no particular advantage or drawback in using one differencing in place of the other, they can be used indifferently in FDTD calculations.

Empirical Modeling of the Quiet and Storm Time Geosynchronous Magnetic Field

AbstractA dynamical empirical model of the near‐geosynchronous magnetic field has been constructed, based on a recently developed radial basis functions approach and a multiyear set of spacecraft data taken by Time History of Events and Macroscale Interactions during Substorms (THEMIS), Polar, Cluster, and Van Allen Probes missions including 133 geomagnetic storms in the time interval between 1996 and 2016. The model describes the field as a function of Cartesian solar magnetic coordinates, dipole tilt angle, and solar wind ram pressure and of a set of dynamic variables representing the response of the magnetosphere to the external driving/loading during the active phase of a space weather event, followed by the internal relaxation/dissipation during the storm recovery. In terms of the disturbance level, the model's validity range extends to intense storms with peak SYM‐H values down to −150 nT. The spatial validity domain is a toroidal volume bounded by the inner (L ∼ 5) and outer (L ∼ 9) dipolar L shells, which allows the model to be used for tracing field lines to magnetically map geosynchronous spacecraft locations down to low altitudes. The model has been validated on independent out‐of‐sample magnetic field data and compared with an earlier empirical model and GOES 15 data taken in 2012 and 2015.

On the validity range of strain-gradient elasticity: A mixed static-dynamic identification procedure

Wave propagation in architectured materials, or materials with microstructure, is known to be dependent on the ratio between the wavelength and a characteristic size of the microstructure. Indeed, when this ratio decreases (i.e. when the wavelength approaches this characteristic size) important quantities, such as phase and group velocity, deviate considerably from their low frequency/long wavelength values. This well-known phenomenon is called dispersion of waves. Objective of this work is to show that strain-gradient elasticity can be used to quantitatively describe the behaviour of a microstructured solid, and that the validity domain (in terms of frequency and wavelength) of this model is sufficiently large to be useful in practical applications. To this end, the parameters of the overall continuum are identified for a periodic architectured material, and the results of a transient problem are compared to those obtained from a finite element full field computation on the real geometry. The quality of the overall description using a strain-gradient elastic continuum is compared to the classical homogenization procedure that uses Cauchy continuum. The extended model of elasticity is shown to provide a good approximation of the real solution over a wider frequency range.

Is the Rayleigh-Sommerfeld diffraction always an exact reference for high speed diffraction algorithms?

In several areas of optics and photonics the behavior of the electromagnetic waves has to be calculated with the scalar theory of diffraction by computational methods. Many of these high-speed diffraction algorithms based on a fast-Fourier-transformation are approximations of the Rayleigh-Sommerfeld-diffraction (RSD) theory. In this article a novel sampling condition for the well-sampling of the Riemann integral of the RSD is demonstrated, the fundamental restrictions due to this condition are discussed, it will be demonstrated that the restrictions are completely removed by a sampling below the Abbe resolution limit and a very general unified approach for applying the RSD outside its sampling domain is given.

Gaussian process for 6-DoF rigid motions

Data-driven modeling approaches receive significant attention in robotics as they are capable of representing system behavior to which first-order principles cannot be employed. Modeling of human motions, based on observations is one of the many application areas. So far, however, the available probabilistic approaches cannot handle dynamics evolving in the space of rigid motions, as rotations are not appropriately considered. In this article, we present a mathematical framework for Gaussian process modeling, where the valid input domain is generalized to full rigid motions, namely the special Euclidean group SE(3). The kernel functions inside the Gaussian process are modified to exploit properties of the input data representation by dual quaternions. We further prove that the presented covariance functions maintain the Gaussian process properties. The correctness and accuracy of our approach is validated on simulated and real human motion data. We analyze the estimation performance of the novel Gaussian process framework in comparison to state of the art techniques, and show significantly improved model behavior of rigid motions.

Determining the number of layers in few‐layer graphene by combining Raman spectroscopy and optical contrast

Raman spectroscopy is commonly used to determine the number of layers of few‐layer graphene (FLG) samples. In this work, we focus on the criteria based on the G‐band integrated intensity and on the laser optical contrast. Limitations due to stacking order are discussed and lead to the conclusion that it is necessary to combine Raman and optical contrast to avoid misinterpretation. Both methods enable to distinguish unambiguously between single layer graphene and multilayer graphene. However, neither each method separately nor the combination of the two enable a determination of the number of layers for all possible stacking orientations. Importantly, because the two methods always significantly disagree when they fail, the comparison of the values deduced by each method allows to discriminate if the determined number of layers can be specified or not. Other important parameters (substrate, laser wavelength, objective numerical aperture) are discussed to define a reliable method to determine the number of graphene layers in FLG and its domain of validity. The proposed method that combines Raman and optical contrast measurements, carried out with a 532 nm laser and using a 100× objective with a numerical aperture of 0.9, allows the determination of the number of layers for (up to 5) FLG on the following substrates: (1) glass (soda lime glass or similar with refractive index between 1.50 and 1.55) and (2) oxidized silicon (SiO2 on silicon, with a SiO2 thickness of 90 ± 5 nm). The method is however limited to high quality graphene and FLG with small defect density and low residue. Copyright © 2017 John Wiley & Sons, Ltd.

A model-based data mining approach for determining the domain of validity of approximated models

Parametric models derived from simplifying modelling assumptions give an approximated description of the physical system under study. The value of an approximated model depends on the consciousness of its descriptive limits and on the precise estimation of its parameters. In this manuscript, a framework for identifying the model domain of validity for the simplifying model hypotheses is presented. A model-based data mining method for parameter estimation is proposed as central block to classify the observed experimental conditions as compatible or incompatible with the approximated model. A nonlinear support vector classifier is then trained on the classified (observed) experimental conditions to identify a decision function for quantifying the expected model reliability in unexplored regions of the experimental design space. The proposed approach is employed for determining the domain of reliability for a simplified kinetic model of methanol oxidation on silver catalyst.

Conference presentation to publication: a retrospective study evaluating quality of abstracts and journal articles in medical education research

BackgroundThere is little evidence regarding the comparative quality of abstracts and articles in medical education research. The Medical Education Research Study Quality Instrument (MERSQI), which was developed to evaluate the quality of reporting in medical education, has strong validity evidence for content, internal structure, and relationships to other variables. We used the MERSQI to compare the quality of reporting for conference abstracts, journal abstracts, and published articles.MethodsThis is a retrospective study of all 46 medical education research abstracts submitted to the Society of General Internal Medicine 2009 Annual Meeting that were subsequently published in a peer-reviewed journal. We compared MERSQI scores of the abstracts with scores for their corresponding published journal abstracts and articles. Comparisons were performed using the signed rank test.ResultsOverall MERSQI scores increased significantly for published articles compared with conference abstracts (11.33 vs 9.67; P < .001) and journal abstracts (11.33 vs 9.96; P < .001). Regarding MERSQI subscales, published articles had higher MERSQI scores than conference abstracts in the domains of sampling (1.59 vs 1.34; P = .006), data analysis (3.00 vs 2.43; P < .001), and validity of evaluation instrument (1.04 vs 0.28; P < .001). Published articles also had higher MERSQI scores than journal abstracts in the domains of data analysis (3.00 vs 2.70; P = .004) and validity of evaluation instrument (1.04 vs 0.26; P < .001).ConclusionsTo our knowledge, this is the first study to compare the quality of medical education abstracts and journal articles using the MERSQI. Overall, the quality of articles was greater than that of abstracts. However, there were no significant differences between abstracts and articles for the domains of study design and outcomes, which indicates that these MERSQI elements may be applicable to abstracts. Findings also suggest that abstract quality is generally preserved from original presentation to publication.

Assessment for multi-endpoint values of carbon nanotubes: Quantitative nanostructure-property relationship modeling with norm indexes

Carbon nanotubes (CNTs) have important role in ecological environment owing to their ability of the adsorption of organic contaminants which might greatly affect the dispersibility of CNTs in aquatic environments. Thus in this work, quantitative nanostructure-property relationship modeling studies were performed with the norm indexes descriptors our group proposed to predict the adsorption data (represented by logK∞ and logKSA) of organic compounds by multi-walled CNTs and the dispersibility (represented by logCmax) of single-walled CNT in various organic solvents. Calculation results showed that the three models could provide accurate and satisfactory predictions with the squared correction coefficient for the training set and the test set of 0.9500 and 0.9792 for logK∞, 0.9258 and 0.9770 for logKSA, 0.9511 and 0.9956 for logCmax respectively. Validation results containing cross validation, Y-randomized test and applicability domain analysis together with the comparison with other works demonstrated that our models were stable, robust and reliable. These satisfactory results showed that the norm indexes descriptors our group proposed might have extensive and promising applications in nanotechnology.

Building a pedotransfer function for soil bulk density on regional dataset and testing its validity over a larger area

Though soil bulk density (BD) is important for crop growth and land management, information about BD is often missing in soil database due to the fact that the determination of BD is time consuming and labor intensive. In order to fill this gap, pedotransfer functions (PTFs) have been developed for predicting bulk density during last decades. To avoid non-valid extrapolation, the validity domain of PTFs should be investigated. In this study, a PTFs for bulk density was built using GBM model on data from Region Centre and we tested its validity on data from mainland France except Region Centre. Standardized Euclidean distance was applied to distinguish dissimilar soil samples from Region Centre data and other regions data. The established PTFs were not suitable for predicting these dissimilar samples. In order to make a balance between prediction accuracy and the number of samples can be predicted with our PTFs, different cutoff limits of Standardized Euclidean distance was compared. When optimized distance cutoff limit was at 97%, compared to result without excluding dissimilar samples, RMSPE value on test data decreased from 0.179 to 0.163gcm−3. An additional sampling strategy based on these dissimilar samples can improve the predictive ability of PTFs. We also suggest that the purposive sampling strategy or the systematic and dense sampling strategy will do large contribution in robust modelling of PTFs.

Neurodevelopment of HIV-Exposed and HIV-Unexposed Uninfected Children at 24 Months.

We sought to determine if HIV-exposed uninfected (HEU) children had worse neurodevelopmental outcomes at 24 months compared with HIV-unexposed uninfected (HUU) children in Botswana. HIV-infected and uninfected mothers enrolled in a prospective observational study ("Tshipidi") in Botswana from May 2010 to July 2012. Child neurodevelopment was assessed at 24 months with the Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III: cognitive, gross motor, fine motor, expressive language, and receptive language domains) and the Development Milestones Checklist (DMC), a caregiver-completed questionnaire (locomotor, fine motor, language and personal-social domains). We used linear regression models to estimate the association of in-utero HIV exposure with neurodevelopment, adjusting for socioeconomic and maternal health characteristics. We evaluated 670 children (313 HEU, 357 HUU) with ≥1 valid Bayley-III domain assessed and 723 children (337 HEU, 386 HUU) with a DMC. Among the 337 HEU children with either assessment, 122 (36%) were exposed in utero to maternal 3-drug antiretroviral treatment and 214 (64%) to zidovudine. Almost all HUU children (99.5%) breastfed, compared with only 9% of HEU children. No domain score was significantly lower among HEU children in adjusted analyses. Bayley-III cognitive and DMC personal-social domain scores were significantly higher in HEU children than in HUU children, but differences were small. HEU children performed equally well on neurodevelopmental assessments at 24 months of age compared with HUU children. Given the global expansion of the HEU population, results suggesting no adverse impact of in-utero HIV and antiretroviral exposure on early neurodevelopment are reassuring.

Combination of linear power flow tools for voltages and power estimation on MV networks

European grid codes define new network management rules. To answer these decrees, it is important to estimate accurately the voltages and powers inside distribution networks. The intermittent nature of renewable sources leads to consider stochastic variables in power flow algorithms. A review of power flow methods and their ability to comply with these requirements is done, which shows that computationally demanding non-linear methods have to be discarded when dealing with stochastic data and considering limited calculation time. A combination of linear methods is proposed, for which average errors in power and voltage are quite low, when applied to a real-life distribution network. The validity domain of the method is also presented.

Modeling of transport processes through large-scale discrete fracture networks using conforming meshes and open-source software

Most industrial and field studies of transport processes in Discrete Fracture Networks (DFNs) involve strong simplifying assumptions, especially at the meshing stage. High-accuracy simulations are therefore required for validating these simplified models and their domain of validity. The present paper proposes an efficient workflow based on open-source software to obtain transport simulations. High-quality computational meshes for DFNs are first generated using the conforming meshing approach FraC. Then, a tracer transport model implemented in the open-source code DuMux is used for simulating tracer transport driven by the advection-dispersion equation. We adopt the box method, a vertex-centered finite volume scheme for spatial discretization, which ensures concentration continuity and mass conservation at intersections between fractures. Numerical results on simple networks for validation purposes and on complex realistic DFNs are presented. An a-posteriori convergence study of the discretization method shows an order of convergence O(h) for tracer concentration with h the mesh size.

01.21: Static and cyclic behaviour of bolted gusset plate connections: Numerical and analytical modelling

ABSTRACTIn dissipative seismic concept according to Eurocode 8, capacity design leads to additional cost for brace connections. In this concept, connections, either bolted or welded, don't dissipate energy, this role being dedicated to braces. However bolted gusset plate connections of brace are able to dissipate energy by sliding, bearing and block shear. Within the RFCS project Meakado, the seismic behaviour of these shear joints and their influence on the global resistance of the concentrically braced frame (CBF) have been studied performing time history analysis on CBF structures where springs were introduced at the location of connections. To calibrate this spring model, tests on bolted connections of single channel and double angles have been performed by Tecnalia during this project and completed by a numerical simulations based on the finite element code ANSYS. The results of the numerical simulations are presented in this paper. The model is firstly confronted to experimental tests and a parametrical study has been carried out to extend the domain of validity and particularly to study connections of tubes. Finally, an equivalent spring model, based on the component method of Eurocode 3, supposed to represent the behaviour of connections in seismic nonlinear analyses is developed.

C-SWRL: A Unique Semantic Web Framework for Reasoning Over Stream Data

The synergy of Data Stream Management Systems and Semantic Web applications has steered towards a new paradigm known as Stream Reasoning. The Semantic Web standards for knowledge base modeling and querying, namely RDF, OWL and SPARQL, has extensively been used by the Stream Reasoning community. However, the Semantic Web rule languages, such as SWRL and RIF, have never been used in stream data applications. Instead, different non-Semantic Web rule systems have been approached. Since RIF is primarily intended for exchanging rules among systems, we focused on SWRL applications with stream data. This proves difficult following the SWRL’s open world semantics. To overcome SWRL’s expressivity issues we propose an infrastructure extension, which will enable SWRL reasoning with stream data. Namely, a query processing system, such as C-SPARQL, was layered under SWRL to support closed-world and time-aware reasoning. Moreover, OWLAPI constructs were utilized to enable non-monotonicity, while SPARQL constructs were used to enable negation as failure. Water quality monitoring was used as a validation domain of the proposed system.

Expanded uncertainty associated with determination of isotope enrichment factors: Comparison of two point calculation and Rayleigh-plot

The enrichment factor (ε) is a common way to express Isotope Effects (IEs) associated with a phenomenon. Many studies determine ε using a Rayleigh-plot, which needs multiple data points. More recent articles describe an alternative method using the Rayleigh equation that allows the determination of ε using only one experimental point, but this method is often subject to controversy. However, a calculation method using two points (one experimental point and one at t0) should lead to the same results because the calculation is derived from the Rayleigh equation. But, it is frequently asked “what is the valid domain of use of this two point calculation?” The primary aim of the present work is a systematic comparison of results obtained with these two methodologies and the determination of the conditions required for the valid calculation of ε. In order to evaluate the efficiency of the two approaches, the expanded uncertainty (U) associated with determining ε has been calculated using experimental data from three published articles. The second objective of the present work is to describe how to determine the expanded uncertainty (U) associated with determining ε. Comparative methodologies using both Rayleigh-plot and two point calculation are detailed and it is clearly demonstrated that calculation of ε using a single data point can give the same result as a Rayleigh-plot provided one strict condition is respected: that the experimental value is measured at a small fraction of unreacted substrate (f < 30%). This study will help stable isotope users to present their results in a more rigorous expression: ε ± U and therefore to define better the significance of an experimental results prior interpretation.Capsule: Enrichment factor can be determined through two different methods and the calculation of associated expanded uncertainty allows checking its significance.

Performance of the two-source energy budget (TSEB) model for the monitoring of evapotranspiration over irrigated annual crops in North Africa

The main objective of this study was to evaluate the performance and the domain of validity of the two-source energy balance model (TSEB) for the monitoring of actual evapotranspiration (ETa) as a first step towards its use for irrigation planning. Secondary objectives were to analyze the ability of TSEB model to detect water stress and to evaluate evapotranspiration partition between evaporation (E) and transpiration (T) over irrigated annual crops. Within this context, TSEB was compared to the calibrated FAO-56 dual approach, taken as a reference tool for the monitoring of crop water consumption. TSEB computes ETa as the residual of a double component energy balance driven by the radiative surface temperature (Ts) used as a proxy of crop hydric conditions; the FAO-56 dual crop coefficient approach uses the Normalized Difference Vegetation Index (NDVI) as a proxy of Basal Crop Coefficient (Kcb) and assesses the hydric status directly by solving a two layer soil water budget. Both approaches were evaluated over four plots of wheat and sugar beet located in the Haouz plain (Marrakech, Morocco) that were instrumented with eddy covariance systems during the 2012 and 2013 growing seasons. Series of ASTER images were acquired during the first agricultural season. Both models offered fair performances compared to ETa observations with Root Mean Square Error (RMSE) lower than 1mmday−1 apart from the FAO-56 dual approach on the sugar beet plot because of uncertain irrigation inputs. This highlights a major weakness of this model when water inputs are uncertain; a very likely case at the plot scale. By contrast, the TSEB model offered smoother performances in all cases. The potentialities of both approaches to predict a water stress index based on the departure from potential evapotranspiration (ETc) was evaluated: although the FAO-56 dual was better suited to detect high water stresses, the TSEB model was able to detect moderate stresses without a need to prescribe water inputs. Finally, the partition of ETa between soil evaporation and plant transpiration was estimated indirectly by confrontation between simulated soil evaporation and surface (0–5cm) soil moisture acquired spatially with Theta Probe sensors and taken as a proxy of soil evaporation. TSEB evaporation was well correlated to surface soil moisture (r=0.82) for low Leaf Area Index (LAI) values (<1.5m2m−2). In addition, TSEB predicted partition compared well to snapshot measurements based on the stable isotope method. This in-depth comparison of two simple tools to monitor ETa leads us to the conclusion that the TSEB model can reasonably be used to map ETa on large scale and possibly for the decision-making process of irrigation scheduling.

Compact On-Wafer Test Structures for Device RF Characterization

The main objective of this paper is to validate the radio frequency (RF) characterization procedure based on compact test structures compatible with 50- $\mu \text{m}$ -pitch RF probes. It is shown that by using these new test structures, the layoutgeometry and hence the on-chip space consumption for complete sets of passive and active devices, e.g., coplanar waveguide transmission lines and RF MOSFETs, is divided by a factor of two. The validity domain of these new compact test structures is demonstrated by comparing their measurement results with classical test structures compatible with 100– $150~\mu \text{m}$ -pitch RF probes. 50- $\mu \text{m}$ -pitch de-embedding structures have been implemented on 0.18- $\mu \text{m}$ RF silicon-on-insulator (SOI) technology. Cutoff frequencies and parasitic elements of the RF SOI transistors are extracted and the RF performance of trap-rich SOI substrates is analyzed under small- and large-signal conditions.