Local Misfit Research Articles

Evaluating Restrictive Models in Educational and Behavioral Research: Local Misfit Overrides Model Tenability.

The frequent practice of overall fit evaluation for latent variable models in educational and behavioral research is reconsidered. It is argued that since overall plausibility does not imply local plausibility and is only necessary for the latter, local misfit should be considered a sufficient condition for model rejection, even in the case of omnibus model tenability. The argument is exemplified with a comparison of the widely used one-parameter and two-parameter logistic models. A theoretically and practically relevant setting illustrates how discounting local fit and concentrating instead on overall model fit may lead to incorrect model selection, even if a popular information criterion is also employed. The article concludes with the recommendation for routine examination of particular parameter constraints within latent variable models as part of their fit evaluation.

The Concerns About Pain (CAP) Scale: A Patient-Reported Outcome Measure of Pain Catastrophizing

Pain catastrophizing has been recognized as an important and consistent psychosocial predictor of nearly every key pain-related outcome. The purpose of this study was to develop a new measure of pain catastrophizing using modern psychometric methodology. People with chronic pain (N = 795) responded to thirty items. Data were analyzed using item response theory, including assessment of differential item functioning and reliability. Sensitivity to change and validity were examined using data collected from patients undergoing spinal fusion surgery (n = 184) and participating in an ongoing longitudinal aging with a disability survey study (n = 1,388). The final 24-item bank had no items with significant local dependence, misfit, or differential item functioning. Results provided strong evidence of reliability and validity. Six- and 2-item short forms were developed for use when computer adaptive testing is not feasible or desirable. The item bank was named the University of Washington Concerns About Pain scale because the term “catastrophizing” was considered stigmatizing by people with chronic pain. Guidance for score interpretation was developed with extensive feedback from individuals with chronic pain. The Concerns About Pain item bank, short forms, and user manuals are free and publicly available to all users and can be accessed online at https://uwcorr.washington.edu/measures/. PerspectiveThis article presents the development of the University of Washington Concerns About Pain scale, the first item response theory-based item bank of pain catastrophizing. The measure is intended for clinicians interested in improving outcomes of patients with chronic pain and for researchers who study impact of and treatment interventions aimed at reducing pain catastrophizing.

Microstructural and crystallographic analysis of hydride reorientation in a zirconium alloy cladding tube

Understanding the hydride platelet reorientation in zirconium (Zr) alloy fuel claddings that potentially occurs during the dry storage process of spent nuclear fuel is of great technological importance for the cladding integrity. In this study, detailed microstructural and crystallographic analysis of the circumferential and reoriented radial hydrides in a Zr–Sn–Nb cladding tube has been performed. The results show that the crystallographic nature of the reoriented radial hydrides in the material remains the same as that of the circumferential hydrides. The radial hydrides remain to be the δ-phase precipitated along the {10–17} habit plane of the α-Zr matrix and follow the {0001}α//{111}δ and <11–20>α//<110>δ orientation relationship with the matrix. The local misfit strain between the matrix grains and the circumferential/radial hydrides is accommodated by the development of {01–10}α <a> type misfit dislocations in the matrix grains as well as the dislocations and twinning in the hydrides. It is confirmed that the hoop stress applied on the cladding tube during the hydride precipitation only changes the growth direction of the macroscopic hydrides from the circumferential direction to the radial direction of the tube material. A qualitative micromechanical stress analysis shows that the shear stress on the basal plane of α-Zr grains promotes the activation of {01–10}α <a> type dislocations slip in the matrix. In addition, to accommodate the c-axis stretching of the matrix unit cell due to the application of hoop stress, the precipitated hydride sub-platelets stacks tend to grow along the direction perpendicular to the direction of the applied hoop stress, leading to the eventual formation of macroscopic radial hydrides (i.e., the occurrence of the stress reorientation).

Investigation of the discontinuous precipitation of U-Nb alloys via thermodynamic analysis and phase-field modeling

U-Nb’s discontinuous precipitation, γmatrixbcc→αcellularorth+γcellular′bcc, is intriguing in the sense that it allows formation and growth of the metastable γ′ phase during the course of its occurrence. Previous attempts to explain the thermodynamic origin of U-Nb’s discontinuous precipitation hypothesized that the energy of α forms an intermediate common tangent with the first potential of the double-well energy of γ at the γ′ composition. In this work, we examine different possible mechanisms by which the discontinuous precipitation product in the U-Nb system can be stabilized. We put forward a mechanism by which the bulk free energy of the γ can develop a non-monotonic dependency with composition. Additionally we posit that local contributions due to lattice mismatch between the α and γ phases may be responsible for the generation of metastable states that may stabilized by thermodyna mics as well as by kinetics. Our work suggests that local misfit strain tends to play a crucial role in the growth of the discontinuous precipitation product. Depending on the magnitude of strain developed at the α/γ′ interfaces, either an increasing γ′ composition or a random distribution of γ′ compositions around the equiatomic value with respect to increasing temperature could be expected. Moreover, we show how it is possible to stabilize the discontinuous precipitation front through highly anisotropic and fast interface diffusion.

Deep Seated Density Anomalies Across the Iberia-Africa Plate Boundary and Its Topographic Response.

The modes in which the lithosphere deforms during continental collision and the mechanisms involved are not well understood. While continental subduction and mantle delamination are often invoked in tectonophysical studies, these processes are difficult to be confirmed in more complex tectonic regions such as the Gibraltar Arc. We study the present‐day density and compositional structure of the lithosphere along a transect running from South Iberia to North Africa crossing the western Gibraltar Arc. This region is located in the westernmost continental segment of the African‐Eurasian plates, characterized by a diffuse transpressive plate boundary. An integrated and self‐consistent geophysical‐petrological methodology is used to model the lithosphere structure variations and the thermophysical properties of the upper mantle. The crustal structure is mainly constrained by seismic experiments and geological data, whereas the composition of the lithospheric mantle is constrained by xenolith data. The results show large lateral variations in the topography of the lithosphere‐asthenosphere boundary. We distinguish different chemical lithospheric mantle domains that reproduce the main trends of the geophysical observables and the modeled P and S wave seismic velocities. A sublithospheric body colder than the surrounding mantle is needed beneath the Betics‐Rif to adjust the measured potential fields. We link this body to the Iberian slab localized just to the east of the profile and having some effect on the geoid and Bouguer anomalies. Local isostasy allows explaining most of the topography, but an elastic thickness higher than 10 km is needed to explain local misfits between the Atlas and the Rif Mountains.

The Element Segregation Between γ/γʹ Phases in a Ni-Based Single Crystal Superalloy Studied by 3D-APT and Its Potential Impact on Local Interfacial Misfit Strain

Three-dimensional atom-probe tomography was used to characterize the γ/γʹ interface structure in a third-generation Ni-based single crystal superalloy with Re addition. It was found that an element-segregation layer with Re, Co and Cr was formed in the γ phase close to the γ/γ′ interface, resulting in a more negative local interface misfit (− 0.29%) compared to the measured result (− 0.16%) from high-resolution X-ray diffraction. Furthermore, the total reduction of interfacial free energy due to the solute atom segregation based on the Gibbsian interfacial excess was calculated to indicate that Re element was the most beneficial element in producing this more negative local misfit with the largest interfacial free energy reduction (13.67 ± 0.21 mJ/m2). Simultaneously, because of the co-segregation of Re, Co and Cr, and the depletion of Ni in the γ phase close to the γ/γ′ interface, it was also deduced that some harmful topologically close-packed phases might be easier to nucleate and grow in the γ phase close to the γ/γ′ interface in service. The element-segregation layer across γ/γ′ interface resulted in a more negative local interface misfit (− 0.29%), compared to the measured result (− 0.16%) from highresolution X-ray diffraction, and the total reduction of interfacial free energy due to the solute atom segregation was calculated to indicate that Re element was the most beneficial element in producing this more negative local misfit with the largest interfacial free energy reduction (13.67 ± 0.21 mJ/m2).

Multi-scale time-frequency domain full waveform inversion with a weighted local correlation-phase misfit function

Abstract Full Waveform Inversion (FWI) is based on the least squares algorithm to minimize the difference between the synthetic and observed data, which is a promising technique for high-resolution velocity inversion. However, the FWI method is characterized by strong model dependence, because the ultra-low-frequency components in the field seismic data are usually not available. In this work, to reduce the model dependence of the FWI method, we introduce a Weighted Local Correlation-phase based FWI method (WLCFWI), which emphasizes the correlation phase between the synthetic and observed data in the time-frequency domain. The local correlation-phase misfit function combines the advantages of phase and normalized correlation function, and has an enormous potential for reducing the model dependence and improving FWI results. Besides, in the correlation-phase misfit function, the amplitude information is treated as a weighting factor, which emphasizes the phase similarity between synthetic and observed data. Numerical examples and the analysis of the misfit function show that the WLCFWI method has a strong ability to reduce model dependence, even if the seismic data are devoid of low-frequency components and contain strong Gaussian noise.

Measuring Fatigue in TBI: Development of the TBI-QOL Fatigue Item Bank and Short Form.

To develop a traumatic brain injury (TBI)-specific, item response theory (IRT)-calibrated Fatigue item bank, short form, and computer adaptive test (CAT) as part of the Traumatic Brain Injury-Quality of Life (TBI-QOL) measurement system. Five TBI Model Systems rehabilitation centers in the US PARTICIPANTS:: Adults with complicated mild, moderate, or severe TBI confirmed by medical record review. Cross-sectional field testing via phone or in-person interview. TBI-QOL Fatigue item bank, short form, and CAT. A total of 590 adults with TBI completed 95 preliminary fatigue items, including 86 items from the Patient-Reported Outcomes Measurement Information System (PROMIS) and 9 items from the Quality of Life in Neurological Disorders (Neuro-QOL) system. Through 4 iterations of factor analysis, 22 items were deleted for reasons such as local item dependence, misfit, and low item-total correlations. Graded response model IRT analyses were conducted on the 73-item set, and Stocking-Lord equating was used to transform the item parameters to the PROMIS (general population) metric. A short form and CAT, which demonstrate similar reliability to the full item bank, were developed. Test-retest reliability of the CAT was established in an independent sample (Pearson's r and intraclass correlation coefficient = 0.82 [95% confidence interval: 0.72-0.88]). The TBI-QOL Fatigue item bank, short form, and CAT provide rehabilitation researchers and clinicians with TBI-optimized tools for assessment of the patient-reported experience and impact of fatigue on individuals with TBI.

Misfit strain induced phase transformation at a basal/prismatic twin boundary in deformation of magnesium

Phase transformation from hexagonal close-packed (HCP) to face-centered cubic (FCC) does not occur in plastic deformation of pure magnesium. In this work, a reversible HCP → FCC phase transformation was observed at basal/prismatic twin boundary (TB) of 101¯2 twinning mode, in atomistic simulations of TB migration in pure magnesium. The FCC phase was induced by a local misfit strain between the parent and the twin. When an FCC phase was formed at the basal/prismatic TB, the TB migration was temporarily hindered. As the strain increased, the FCC transformed to the HCP twin by atomic shuffling. The orientation relationship between the FCC and the HCP parent satisfies 111FCC||101¯0HCP. During transformation, a double-layered prismatic plane was transformed into a 111FCC close-packed plane of the FCC by shear and shuffle. The energy barriers for the reversible phase transformation was calculated.

Detecting Random Responses in a Personality Scale Using IRT-Based Person-Fit Indices

Abstract. Random response is a very common aberrant response behavior in personality tests and may negatively affect the reliability, validity, or other analytical aspects of psychological assessment. Typically, researchers use a single person-fit index to identify random responses. This study recommends a three-step person-fit analysis procedure. Unlike the typical single person-fit methods, the three-step procedure identifies both global misfit and local misfit individuals using different person-fit indices. This procedure was able to identify more local misfit individuals than single-index method, and a graphical method was used to visualize those particular items in which random response behaviors appear. This method may be useful to researchers in that it will provide them with more information about response behaviors, allowing better evaluation of scale administration and development of more plausible explanations. Real data were used in this study instead of simulation data. In order to create real random responses, an experimental test administration was designed. Four different random response samples were produced using this experimental system.

Investigating the Utility of Fixed-margin Sampling in Network Psychometrics

Steinley, Hoffman, Brusco, and Sher (2017) proposed a new method for evaluating the performance of psychological network models: fixed-margin sampling. The authors investigated LASSO regularized Ising models (eLasso) by generating random datasets with the same margins as the original binary dataset, and concluded that many estimated eLasso parameters are not distinguishable from those that would be expected if the data were generated by chance. We argue that fixed-margin sampling cannot be used for this purpose, as it generates data under a particular null-hypothesis: a unidimensional factor model with interchangeable indicators (i.e., the Rasch model). We show this by discussing relevant psychometric literature and by performing simulation studies. Results indicate that while eLasso correctly estimated network models and estimated almost no edges due to chance, fixed-margin sampling performed poorly in classifying true effects as “interesting” (Steinley et al. 2017, p. 1004). Further simulation studies indicate that fixed-margin sampling offers a powerful method for highlighting local misfit from the Rasch model, but performs only moderately in identifying global departures from the Rasch model. We conclude that fixed-margin sampling is not up to the task of assessing if results from estimated Ising models or other multivariate psychometric models are due to chance.

Determination of elastic moduli from measured acoustic velocities

Methods are evaluated in solution of the inverse problem associated with determination of elastic moduli for crystals of arbitrary symmetry from elastic wave velocities measured in many crystallographic directions. A package of MATLAB functions provides a robust and flexible environment for analysis of ultrasonic, Brillouin, or Impulsive Stimulated Light Scattering datasets. Three inverse algorithms are considered: the gradient-based methods of Levenberg-Marquardt and Backus-Gilbert, and a non-gradient-based (Nelder-Mead) simplex approach. Several data types are considered: body wave velocities alone, surface wave velocities plus a side constraint on X-ray-diffraction-based axes compressibilities, or joint body and surface wave velocities. The numerical algorithms are validated through comparisons with prior published results and through analysis of synthetic datasets. Although all approaches succeed in finding low-misfit solutions, the Levenberg-Marquardt method consistently demonstrates effectiveness and computational efficiency. However, linearized gradient-based methods, when applied to a strongly non-linear problem, may not adequately converge to the global minimum. The simplex method, while slower, is less susceptible to being trapped in local misfit minima. A “multi-start” strategy (initiate searches from more than one initial guess) provides better assurance that global minima have been located. Numerical estimates of parameter uncertainties based on Monte Carlo simulations are compared to formal uncertainties based on covariance calculations.

Distinctive role of plastic and creep strain in directional coarsening of a Ni-base single crystal superalloy

The distinctive role of plastic and creep strain in directional coarsening of a single crystal Ni-base superalloy, CMSX-4, was experimentally and analytically investigated. First, solid cylindrical samples were subjected to uniaxial tensile plastic strain at 900°C followed by thermal aging at 1080°C. Microstructural observation revealed that the extent of directional coarsening became more pronounced with increasing plastic strain until it reached 0.2%; no further coarsening was induced with the introduction of additional plastic strain. Second, several combinations of plastic and creep strain were applied to the samples. The magnitude of the compressive creep strain at 1080°C was varied with the plastic strain fixed at 1.5% at 900°C. The results indicated that the effect of 0.15% creep strain was completely balanced with that of the 1.5% plastic strain; hence, the effects of the plastic and creep strain on the morphological changes differed quantitatively. Finally, elastic-plastic and creep finite element analyses were conducted to rationalize the experimental results. The analytical investigations suggested that the directional coarsening was dependent on the inelastic strain gap between the γ and γ’ phases, which was attributed to an inhomogeneous relaxation of the local misfit stress field. The difference in the roles of plastic and creep strain in the coarsening was observed to quantitatively correspond to the difference in the localized inelastic deformations.

Improving the inverse modeling of a trace isotope: how precisely can radium-228 fluxes toward the ocean and submarine groundwater discharge be estimated?

Abstract. Radium-228 (228Ra), an almost conservative trace isotope in the ocean, supplied from the continental shelves and removed by a known radioactive decay (T1∕2 = 5. 75 years), can be used as a proxy to constrain shelf fluxes of other trace elements, such as nutrients, iron, or rare earth elements. In this study, we perform inverse modeling of a global 228Ra dataset (including GEOSECS, TTO and GEOTRACES programs, and, for the first time, data from the Arctic and around the Kerguelen Islands) to compute the total 228Ra fluxes toward the ocean, using the ocean circulation obtained from the NEMO 3.6 model with a 2° resolution. We optimized the inverse calculation (source regions, cost function) and find a global estimate of the 228Ra fluxes of 8.01–8. 49 × 1023 atoms yr−1, more precise and around 20 % lower than previous estimates. The largest fluxes are in the western North Atlantic, the western Pacific and the Indian Ocean, with roughly two-thirds in the Indo-Pacific Basin. An estimate in the Arctic Ocean is provided for the first time (0.43–0.50 × 1023 atoms yr−1). Local misfits between model and data in the Arctic, the Gulf Stream and the Kuroshio regions could result from flaws of the ocean circulation in these regions (resolution, atmospheric forcing). As radium is enriched in groundwater, a large part of the 228Ra shelf sources comes from submarine groundwater discharge (SGD), a major but poorly known pathway for terrestrial mineral elements, including nutrients, to the ocean. In contrast to the 228Ra budget, the global estimate of SGD is rather unconstrained, between 1.3 and 14. 7 × 1013 m3 yr−1, due to high uncertainties on the other sources of 228Ra, especially diffusion from continental shelf sediments. Better precision on SGD cannot be reached by inverse modeling until a proper way to separate the contributions of SGD and diffusive release from sediments at a global scale is found.

Europeanization in Time: Assessing the Legacy of URBAN in a Mid-size Italian City

The 2007 mainstreaming of URBAN raised important questions about the sustainability of its regeneration approach under the new regulatory regime, and particularly about the policy legacy left by this Community Initiative in its participating cities. Taking advantage of the recent conclusion of the 2007–2013 programming period, these questions are tackled here both theoretically and empirically. Building on the general model of Europeanization, the article posits a trade-off between local misfit with the URBAN approach and the durability of the policy change induced by the scheme. The argument is then illustrated through an in-depth study of Pescara, a mid-size Italian city that participated successfully in URBAN only to lose most of its policy innovations in the immediately subsequent programming period, when it took part in the country's mainstreamed funding scheme, the “Programmi integrati di sviluppo urbano”. With hindsight, the study suggests that URBAN was set up to fail exactly those cities with little experience in integrated and participatory regeneration that it was supposed to help the most. It also concludes that future European Union policy-making and implementation should factor in the misfit/durability trade-off to maximize effectiveness given the Union's goals as well as its involvement expectations.

Co-seismic fault geometry and slip distribution of the 26 December 2004, giant Sumatra–Andaman earthquake constrained by GPS, coral reef, and remote sensing data

We analyze co-seismic displacement field of the 26 December 2004, giant Sumatra–Andaman earthquake derived from Global Position System observations, geological vertical measurement of coral head, and pivot line observed through remote sensing. Using the co-seismic displacement field and AK135 spherical layered Earth model, we invert co-seismic slip distribution along the seismic fault. We also search the best fault geometry model to fit the observed data. Assuming that the dip angle linearly increases in downward direction, the postfit residual variation of the inversed geometry model with dip angles linearly changing along fault strike are plotted. The geometry model with local minimum misfits is the one with dip angle linearly increasing along strike from 4.3o in top southernmost patch to 4.5o in top northernmost path and dip angle linearly increased. By using the fault shape and geodetic co-seismic data, we estimate the slip distribution on the curved fault. Our result shows that the earthquake ruptured ~200-km width down to a depth of about 60 km. 0.5–12.5 m of thrust slip is resolved with the largest slip centered around the central section of the rupture zone 7ºN–10ºN in latitude. The estimated seismic moment is 8.2 × 1022 N m, which is larger than estimation from the centroid moment magnitude (4.0 × 1022 N m), and smaller than estimation from normal-mode oscillation data modeling (1.0 × 1023 N m).

Inversion of multicomponent seismic time shifts for reservoir pressure and length: a feasibility study

Pressure drops associated with reservoir production generate excess stress and strain that cause travel-time shifts of reflected waves. Here,we invert time shifts of P-, S-, and PS-waves measured between baseline and monitor surveys for pressure reduction and reservoir length. The inversion results can be used to estimate compaction-induced stress and strain changes around the reservoir. We implement a hybrid inversion algorithm that incorporates elements of gradient, global/genetic, and nearest neighbour methods and permits exploration of the parameter space while simultaneously following local misfit gradients. Our synthetic examples indicate that optimal estimates of reservoir pressure from P-wave data can be obtained using the reflections from the reservoir top. For S-waves, time shifts from the top of the reservoir can be accurately inverted for pressure if the noise level is low. However, if noise contamination is significant, it is preferable to use S-wave data (or combined shifts of all three modes) from reflectors beneath the reservoir. Joint wave type inversions demonstrate improvements over any single pure mode. Reservoir length can be estimated using the time shifts of any mode from the reservoir top or deeper reflectors. We also evaluate the differences between the actual strain field and those corresponding to the best-case inversion results obtained using P- and S-wave data. Another series of tests addresses the inversion of the time shifts for the pressure drops in two-compartment reservoirs, as well as for the associated strain field. Numerical testing shows that a potentially serious source of error in the inversion is a distortion in the strain-sensitivity coefficients, which govern the magnitude of stiffness changes. This feasibility study suggests which wave types and reflector locations may provide the most accurate estimates of reservoir parameters from compaction-induced time shifts.

Effect of plastic deformation on nonlinear ultrasonic response of austenitic stainless steel

Abstract The effect of tensile plastic deformation on the nonlinear ultrasonic response of austenitic stainless steel was examined, using nonlinear longitudinal wave. The plastic deformation induced the formation of twins and martensite needles in grains. The density of martensite needles increased with increasing plastic strain. The nonlinear ultrasonic parameter increased with increasing the plastic strain experienced by plastically deformed austenitic stainless steel. A simple power–law relation was proposed between the nonlinear ultrasonic parameter and the plastic strain, taking account of the contribution of local microstructures and microplastic deformation. Using this relationship, the stress exponent index was found to be 1.55. Considering the contributions of local microstructures, the deformation-induced phase change and the deformation associated with the formation of new phase, it is suggested that the acoustic nonlinearity of heterogeneous materials depends on local microstructures, phases, misfit, and high-order elastic constants of individual phases.

Improved Non-Parametric Geometric Corrections For Satellite Imagery Through Covariance Constraints

Satellite imagery enables rapid data collection and assessment for several earth and environmental sciences. However, the obtained raw imagery cannot be used directly for spatial data collection and assessment and should be further processed for geometric distortions. The usefulness and reliability of the data obtained from satellite images heavily relies on the geometric correction process and it can be applied through either parametric or non-parametric methods. Parametric methods require physical sensor model parameters which are generally available only to the vendor. The Rational Polynomial Coefficients (RPCs) supplied by several vendors provide global geometric correction, however they are usually available for specific high resolution imagery systems. Other polynomials methods provide geometric corrections locally but applicable for nearly all satellite imagery systems. Depending on the degree of the employed polynomial, the topography, the distribution and the quality of the control points, local geometric corrections could provide lower misfits at GCPs (Ground Control Points) while they might produce very large misfits at ICP (Independent Check Points). In particular, when the available number of GCPs is limited and they are poorly distributed over the image area. In this study, 2D and 3D Affine functions with covariance constraints are introduced to improve the geometric correction when the available GCP are of limited accuracy and poorly distributed. The efficiency of the proposed method was numerically shown in two applications. The results show that the proposed method provides a compromise between the local and global misfits without using any ICP coordinates and enables robust and efficient geometric correction of satellite imagery which lacks a precise RPC model such as TUBITAK RASAT satellite.

The dimensions of library service quality: A confirmatory factor analysis of the LibQUAL + instrument

The LibQUAL+ instrument has been widely adopted by libraries to evaluate user perceptions of library service quality. Studies combining groups (e.g., Lane et al., 2012) have shown high correlations between two factors, suggesting the possibility that a two-factor model may fit as well as the three-factor model theorized by the developers. Also, previous studies have not closely examined residuals to analyze local misfit in the context of theory but instead have often correlated error terms to improve model fit. This study uses LibQUAL+ responses from undergraduates at a public, comprehensive university to test three-factor, two-factor, and one-factor models of user perceptions of library service quality. Global fit indices indicated that both two-factor and three-factor models were empirically supported, but the three-factor model had better theoretical support. Furthermore, this article adds to the literature the unique perspective of residual analysis and builds theoretical arguments in the interpretation of the final model. Areas of local misfit suggest the need for independent studies to examine residuals. If areas of misfit repeat across institutional populations, that could suggest the potential for further instrument development, while if areas of misfit are unique to institutional populations, this could target areas for institutions to investigate more closely.