Empirical Factors Research Articles

Reification of the p factor draws attention away from external causes of psychopathology.

Summarizing specific psychopathology symptoms into higher order factors has a long tradition in mental health science. More recently, the general psychopathology factor (p factor) has gained much interest and currently reflects the highest level of the psychopathology hierarchy. The p factor is modeled from covariance of transdiagnostic psychopathology symptoms. Because such covariance is robust (persons who score higher on symptom X compared to others also tend to score higher on symptom Y), there have been many factor-analytic studies that claim the discovery of-and/or empirical support for-a general psychopathology factor. The reification of the p factor has put person-internal common causes of psychopathology high on the research agenda, while person-external common causes are overlooked. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Engineering water-shut-off operations: Application of rheological time-temperature superposition approach for organically-crosslinked polymer gel systems

Polymer-based gels have been extensively utilized in reservoirs to prevent excessive water production and improve oil recovery. In this study, a sulfonated-hydrolyzed polyacrylamide polymer (HPAM-S) and low-toxic organic crosslinkers (hydroquinone and hexamethylenetetramine) were mixed in brine at specified concentrations to formulate the polymer-crosslinker fluid system. The quantitative rheological analysis, along with the TTS (Time-Temperature Superposition) approach, was examined for the first time to achieve the water shut-off operations in high-temperature reservoirs (90 °C–150 °C). The TTS approach was defined as modelling of the viscosity vs. time data obtained at various temperatures using an appropriate empirical shift factor (at) such that a single master curve is established for the viscosity evolution of the given fluid system. This approach facilitates the prediction of the gelation behavior of polymer-crosslinker fluid systems as a function of time at varied reservoir temperatures especially over time scales that are not experimentally accessible. The time-dependent rheological evolution of the fluid system was experimentally investigated using batch-wise bottle testing methods as well as viscosity and viscoelastic measurements by employing an advanced rheometer. The TTS approach was applied to the obtained rheological data at varied temperatures. The model was validated for an unknown set of temperature vs. viscosity data. Based on the TTS approach, the term ‘gelation time’ was defined as the time required to reach a pre-specified viscosity to signify a transition from the liquid-like state to the solid-like state. The gelation time decreases with increasing temperatures. After the gelation time, at each temperature, a swift increase in the fluid viscosity was observed, indicating the initiation of the rapid crosslinking in the fluid systems. It was found that beyond the gelation time, the batch-wise bottle testing showed (G-I) gel strength (qualitative). Analogously, the visco-elasticity test demonstrated a rapid rise in elastic modulus (G′) beyond the gelation time. An underlying mechanism based on polymer hydrolysis was utilized to explain the evolution of distinct viscous and viscoelastic properties as a function of temperature. Moreover, the modeling predictions for the fluid systems were examined for in-situ rock plugging with the help of core-flood equipment. The core-flooding tests confirmed a 99% reduction in the rock permeability beyond the gelation time. The gelation time values obtained from both the batch-wise bottle testing method and rheological tests for the polymer-crosslinker fluid systems were found in agreement with each other, with a tolerance of (±5%).

Establishing a physiologically based pharmacokinetic framework for aldehyde oxidase and dual aldehyde oxidase-CYP substrates.

Aldehyde oxidase (AO) contributes to the clearance of many approved and investigational small molecule drugs, which are often dual substrates of AO and drug-metabolizing enzymes such as cytochrome P450s (CYPs). As such, the lack of established framework for quantitative translation of the clinical pharmacologic correlates of AO-mediated clearance represents an unmet need. This study aimed to evaluate the utility of physiologically based pharmacokinetic (PBPK) modeling in the development of AO and dual AO-CYP substrates. PBPK models were developed for capmatinib, idelalisib, lenvatinib, zaleplon, ziprasidone, and zoniporide, incorporating invitro functional data from human liver subcellular fractions and human hepatocytes. Prediction of metabolic elimination with/without the additional empirical scaling factors (ESFs) was assessed. Clinical pharmacokinetics, human mass balance, and drug-drug interaction (DDI) studies with CYP3A4 modulators, where available, were used to refine/verify the models. Due to the lack of clinically significant AO-DDIs with known AO inhibitors, the fraction metabolized by AO (fmAO) was verified indirectly. Clearance predictions were improved by using ESFs (GMFE ≤1.4-fold versus up to fivefold with physiologically-based scaling only). Observed fmi from mass balance studies were crucial for model verification/refinement, as illustrated by capmatinib, where the fmAO (40%) was otherwise underpredicted up to fourfold. Subsequently, independent DDI studies with ketoconazole, itraconazole, rifampicin, and carbamazepine verified the fmCYP3A4, with predicted ratios of the area under the concentration-time curve (AUCR) within 1.5-fold of the observations. In conclusion, this study provides a novel PBPK-based framework for predicting AO-mediated pharmacokinetics and quantitative assessment of clinical DDI risks for dual AO-CYP substrates within a totality-of-evidence approach.

3D limit analysis of reinforced concrete with sliding along smeared cracks

Limit analysis (LA) is successfully used for investigating the bearing capacity of reinforced concrete (RC) structures. Some cautions must be taken when using this method for RC since the concrete component exhibits a softening behavior with decreasing strength and limited ductility. A commonly adopted provision consists of considering isotropic reduced values of concrete strength to be input in the analysis (empirical effectiveness factors). In this paper, an alternative and completely new approach is proposed and investigated in which concrete strength is weakened in a more targeted manner. To that purpose, the commonly used 3D truncated Mohr-Coulomb (TMC) criterion is adopted to classically describe the compressive, tensile, and shear failure of concrete. However, TMC is here in an original way enriched by additional constraints that allow to account for weakness and anisotropy induced by preferential failure patterns, assumed a priori. The limit analysis approach is then formulated for two dual analyses in the convex optimization framework, making it possible to quantify the numerical error and obtain a lower and an upper bound of the limit load. Numerical examples illustrate the agreement of the formulation with academic results and laboratory tests.

Design correlations for a novel enhanced compact heat exchanger with offset circular fins

A novel core geometry for compact heat exchangers, termed “circular offset fins (cOF)”, is proposed and experimentally investigated in the present work. This core design resembles the well-known offset strip fins used in efficient compact heat exchangers, with a key difference that instead of having rectangular fluid flow passages between deflections, this design features circular paths, resulting in fins with semicircular profiles. An experimental study examined heat transfer and pressure drop characteristics for five different core geometries. These geometries varied in passage diameters, lengths, and degrees of obstruction. The experiments were carried out over Reynolds numbers ranging from 500 to 3000 at different core wall temperatures. Data was analyzed using Kays and London's steady-state steam-to-air heat transfer technique to determine the empirical Colburn factor. The empirical Fanning friction factors for these geometries were also obtained. The asymptotic behavior of the Colburn and Fanning friction factor data allowed for the development of correlations in the function of Reynolds number and geometry dimensionless parameters. The proposed correlations predict data within ±6 % and ±8 %, respectively. The impact of different geometric parameters on core performance was assessed using the Colburn and Fanning friction factors, as well as area and volume goodness factors, and compared to rectangular offset strip fins. Direct comparisons showed that circular offset fins consistently exhibited a lower friction factor than rectangular fins. Although its Colburn factor was lower than rectangular fins up to a Reynolds number of 2000, circular fins it surpassed that of rectangular fins beyond this point. For the area goodness factor, their performance was comparable at a Reynolds number of 500, with circular fins outperforming after this point, achieving a 1.8-fold advantage at a Reynolds number of 3000. In terms of the volume goodness factor, both types of fins performed similarly up to a Reynolds number of 1000. Beyond this threshold, circular offset fins demonstrated a 1.3-fold improvement at a Reynolds number of 3000, underscoring the potential of the novel core geometry for compact heat exchanger applications.

Determining the critical factors for realising successful post-disaster reconstruction projects in the Caribbean

Business as usual project management practice may not be applicable in the recovery of the built environment following a disaster. Unfortunately, little research has been undertaken to understand the nature of post-disaster recovery projects and the requirements for their success in the Caribbean. The Caribbean islands' exposure and susceptibility to natural hazards make it essential to understand what constitutes successful post-disaster reconstruction. By drawing on end-users’ perspectives in four Caribbean islands (Antigua, Dominica, Grenada, St. Vincent) through a quantitative survey and factor analysis, this paper identifies critical factors that determine successful outcomes with post-disaster Caribbean recovery projects. The factor analysis results from the survey responses on 24 empirical success factors suggests four composite Caribbean specific critical success factors, namely, 1) effective management of project knowledge, 2) environment and ecosystem stewardship, 3) stakeholder engagements at multiple levels, and 4) efficient management of financial, social and human resources. The findings from this research can assist with minimising the recurring post-disaster reconstruction projects, project financing donors and managers with an understanding of the issues that matter most to the region success, and realising the end-users’ (the beneficiaries) expectations. Mainstreaming these factors into project planning and execution, and adopting resilience-oriented project management practices, augers well for managing Caribbean disaster reconstruction projects for greater success.

New insights into validity, reliability, and measurement invariance of the Kansas City Cardiomyopathy Questionnaire 23

Background: People affected by heart failure (HF) often exhibit a poor health status, which places a great deal of burden on the healthcare systems. The Kansas City Cardiomyopathy Questionnaire (KCCQ) 23 is the most used tool to measure the health status in this population; however, its psychometric properties have not been thoroughly established.Objective: To evaluate the psychometric properties of the KCCQ-23 in a European cohort of HF patients.Methods: 510 patients (median age 74 years, IQR=18, 58% males) completed the KCCQ-23 along with clinical and psychosocial measures. Factorial validity was established with confirmatory factor analysis (CFA); omega and model-based internal consistency indexes were computed to examine the internal consistency of the scale. Convergent validity was established by correlating the KCCQ-23 scores with clinical and psychosocial measures. Measurement invariance tests across those with preserved vs reduced ejection fraction were conducted within a multigroup framework.Results: Two CFA solutions were tested, which confirmed the theoretical and empirical models postulated by the original author. The internal consistency coefficients for the latent dimensions were adequate (Omega range =0.77-0.93; internal consistency coefficient =0.89-96). KCCQ-23 scores were found to be correlated with ejection fraction, NYHA levels, quality of life, self-care confidence, anxiety and depression, and symptom burden, supporting its convergent validity. Finally, the KCCQ-23 was invariant across ejection fraction levels, both in the theoretical and empirical factor solution.Conclusion: Overall, this study provides evidence of satisfactory psychometric properties of the KCCQ-23, promoting its use in clinical settings and research fields.

Evaporation from thin porous Coatings: Pore size effects and predictive equation for homogeneous coatings

Evaporation of small water droplets on solids is hindered because surface tension pulls the droplet into a spherical cap that has a small perimeter. Our solution is to coat a solid with a very thin, porous layer into which the droplet flows to create a large-area disk with concomitant high rate of evaporation. We investigate evaporation by varying factors that have not been previously considered: pore size and distribution, contact angle, temperature, and relative humidity (RH).A larger pore size resulted in faster evaporation, which we explain through faster transport within the coating. Even faster evaporation occurred for a bilayer structure with small particles on the air side and larger particles on the solid side. The water advancing contact angle had an insignificant effect in the range from < 10° through to 60°.Our results for different pore sizes, temperature, humidity, and contact angle all collapse onto a single curve when appropriately normalized. This validates an equation that can be used for the evaporation from a homogeneous coating that depends only one empirical factor and the droplet volume. Since the volume is often user-controlled, we envisage that this equation can be used to predict evaporation and guide design of fast-drying coatings.

Extensive reference set and refined computational protocol for calculations of 57Fe Mössbauer parameters.

Mössbauer spectroscopy is a powerful technique for probing the local electronic structure of iron compounds, because it reports in an element-selective manner on both the oxidation state and coordination environment of the Fe ion. Computational prediction of the two main Mössbauer parameters, isomer shift (δ) and quadrupole splitting (ΔEQ), has long been targeted by quantum chemical studies, and useful protocols based on density functional theory have been proposed. Here we present an extensive curated reference set of Fe compounds that is considerably larger and more diverse than literature precedents. We make a distinction between low-temperature and high-temperature experimental subgroups. This set is employed for optimizing a refined computational protocol utilizing the scalar version of the exact 2-component (X2C) Hamiltonian with the finite nucleus approximation. Attention is devoted to having an accurate and flexible all-electron basis set for Fe. We assess the performance of several DFT methods that cover all representative families and rungs of functionals and find that hybrid functionals with ca. 25-30% exact exchange offer the best accuracy for isomer shifts. The work establishes a refined general protocol of wide applicability that achieves good performance for the prediction of isomer shifts in a wider variety of systems than before, but the limitations of DFT for quadrupole splittings are also highlighted. Finally, comparison of calculated values with high-temperature experimental results shows that the use of an empirical correction factor is required to account for the second-order Doppler shift and to achieve the same quality of correlation as with the low-temperature data.

A Study of Time Evolution of Some Cosmological Parameters in The Framework of an Anisotropic Kaluza-Klein Metric Using an Empirical Exponential Scale Factor

The present study attempts to determine the time dependence of some cosmological parameters in flat space (i.e., a space of zero spatial curvature), in the framework of an anisotropic Kaluza-Klein metric. The field equations for this work have been derived from the metric by assuming a power-law relation between the normal scale factor and the scale factor corresponding to the extra (i.e., the fifth) dimension. An empirical scale factor, having the expression of a = B exp(αtβ), has been used here in order to derive the expressions for some cosmological parameters as functions of time. The reason for choosing this scale factor is that it generates an expression for the deceleration parameter which undergoes a change of sign, as time goes on, from positive to negative, indicating a transition of the universe from an initial state of decelerated expansion to that of an accelerated expansion (which is its present state), as has been inferred from astrophysical observations. We have graphically depicted the evolution of some cosmological parameters with respect to what one may call the relative time, expressed as t/t0, where t0 is the present age of the universe. The present study finds the dynamical cosmological constant (Λ) to be negative, and it becomes less negative with time, changing at a gradually decreasing rate. The dependence of pressure of the all-pervading cosmic fluid upon density, corresponding to the fifth dimension, has been described in terms of a skewness parameter (δ) which comes out to be decreasing with time. The anisotropy factor has been calculated in this study, whose numerical value has been found to be decreasing with time, indicating a journey of the universe towards phases of gradually smaller anisotropy.

Factors for improving productivity in the New Zealand residential construction sector

Purpose The New Zealand (NZ) construction industry significantly impacts the country's economy and is one of the largest sectors in terms of total employment. However, a persistent and pressing need for improvement exists. Meeting the ongoing demand for housing and urban development requires enhancing residential construction productivity. The purpose of this paper is to determine what factors improve construction productivity in the NZ residential construction sector. Design/methodology/approach Data were obtained from construction industry bodies using a semi-structured online questionnaire survey. From 305 online questionnaires administered, 106 samples were completed by residential industry construction professionals across NZ. The data were analysed using descriptive and inferential statistics to establish the importance of empirical factors for improving construction productivity in the NZ residential construction sector. Findings The Garrett ranking technique revealed this study's top five factors for enhancing construction productivity: adequate design, communication, quality management (QM), supervision and organizational training. Other factors, such as unskilled workers, skilled workers, reworks and employee motivation, ranked less important. Research limitations/implications While providing a valuable exploration of factors that can positively impact residential construction productivity in NZ, this study contains certain limitations. The study's focus on a specific geographic location and a small sample size (n = 106) may restrict the generalizability of its findings to other regions or countries. Furthermore, the reliance on self-reported data from industry professionals introduces the possibility of bias or inaccuracies in the results. In addition, this study did not investigate the potential influence of external factors, such as economic conditions or regulatory changes, on residential construction productivity. Despite these limitations, this study presents a foundation for future research on this topic. Future research could address these limitations by conducting multi-country studies and using objective productivity measures to provide a broader context. In addition, open-ended questions could be used to collect more detailed qualitative data, enhancing this study's dependability. This methodological constraint could have omitted important experiential nuances, which could be explored in future research to provide more comprehensive and rigorous findings. Practical implications Research studies indicate that several construction productivity factors have remained unchanged for over three decades (Arditi and Mochtar, 1996; Hasan et al., 2018). The implications of this study are significant for the residential sector in NZ. By identifying the key factors that can improve productivity in the sector, such as complete design and specifications, effective communication, quality management, adequate supervision, training, skilled labour and employee motivation, this study provides valuable insights for industry practitioners and policymakers. It expands the existing productivity literature around factors for improving NZ residential construction productivity. One important implication of this study is the link between QM and improved productivity, highlighting the significance of strategic organizational investments in QM and the added opportunity presented to policymakers concerning industry-wide improvements. Moreover, the findings suggest that investing in worker training is essential. Ensuring workers possess the necessary skills and knowledge to perform their tasks efficiently can enhance productivity and project outcomes. In conclusion, this study's findings emphasize the factors that can improve construction productivity in residential projects in NZ, ultimately leading to improved outcomes for all stakeholders. Originality/value This research offers a unique perspective on improving residential construction productivity in NZ by identifying and analysing specific factors that can enhance efficiency across the sector. It provides novel findings and valuable insight into possible organizational improvement strategies yet considered in the NZ residential sector.

Kinematic Source Properties of the 2023 Mw 7.7 Türkiye Earthquake Inferred from Near-Fault Strong Ground Motions

Abstract The 2023 Mw 7.7 Türkiye earthquake provided densely observed near-fault ground-motion data, which enabled us to investigate their characteristics and generations. This study aimed to obtain an intuitive understanding of the characteristics of near-fault strong ground motions and their relationship with kinematic source properties using a simple source model. Synthetic ground motions were calculated using the discrete wave number method and compared with observed ground motions. The observed strong motions were used after a time correction based on the first P-wave arrival. Results showed that near-fault pulse-like velocities (0.02–0.6 Hz) were generally explained by the simple kinematic source model that assumed a continuous rupture propagation along the faults. Comparisons at individual sites indicate the various rupture properties of the fault segments. Near-fault ground motions along the Narli segment were explained by the fault plane along the surface trace and not by aftershock distribution. A supershear rupture propagation speed is necessary for a part of the Amanos segment. Rupture stops and restarts were implied near the stepover along the Amanos segment. Empirical site factors estimated by generalized inversion techniques did not show peaks around the frequency of observed large velocity pulses, indicating that the velocity pulses were mainly generated by the source. The model bias and uncertainties were also examined to supplement the simplified subsurface structure used in the simulation. Our results will help to associate the qualitative and quantitative aspects of the kinematic source process with near-fault strong ground motions.

A Simple Expression for the Screening of Excitonic Couplings between Chlorophylls as Inferred for Photosystem I Trimers.

The Coulomb coupling between transition densities of the pigments in photosynthetic pigment-protein complexes, termed excitonic coupling, is a key factor for the description of optical spectra and energy transfer. A challenging question is the quantification of the screening of the excitonic coupling by the optical polarizability of the environment. We use the equivalence between the sophisticated quantum chemical polarizable continuum (PCM) model and the simple electrostatic Poisson-TrEsp approach to analyze the distance and orientation dependence of the dielectric screening between chlorophylls in photosystem I trimers. On the basis of these calculations we find that the vacuum couplings Vmn(0) and the couplings in the dielectric medium Vmn=fmnVmn(0) are related by the empirical screening factor fmn=0.60+39.6θ(|κmn|-1.17)exp(-0.56Rmn/Å), where κmn is the usual orientational factor of the dipole-dipole coupling between the pigments, Rmn is the center-to-center distance, and the Heaviside-function θ(|κmn|-1.17) ensures that the exponential distance dependence only contributes for in-line type dipole geometries. We are confident that the present expression can be applied also to other pigment-protein complexes with chlorophyll or related pigments of similar shape. The variance between the Poisson-TrEsp and the approximate coupling values is found to decrease by a factor of 8 and 3-4 using the present expression, instead of an exponential distance dependent or constant screening factor, respectively, assumed previously in the literature.

Converging Time-Dependent Density Functional Theory Calculations in Five Iterations with Minimal Auxiliary Preconditioning.

Eigenvalue problems and linear systems of equations involving large symmetric matrices are commonly solved in quantum chemistry using Krylov space methods, such as the Davidson algorithm. The preconditioner is a key component of Krylov space methods that accelerates convergence by improving the quality of new guesses at each iteration. We systematically design a new preconditioner for time-dependent density functional theory (TDDFT) calculations based on the recently introduced TDDFT-ris semiempirical model by retuning the empirical scaling factor and the angular momenta of a minimal auxiliary basis. The final preconditioner produced includes up to d-functions in the auxiliary basis and is named "rid". The rid preconditioner converges excitation energies and polarizabilities in 5-6 iterations on average, a factor of 2-3 faster than the conventional diagonal preconditioner, without changing the converged results. Thus, the rid preconditioner is a broadly applicable and efficient preconditioner for TDDFT calculations.

(Invited) Extended Hubbard Functionals for Accurate Modeling of Li-Ion Battery Cathode Materials

Designing novel cathode materials for Li-ion batteries necessitates accurate first-principles predictions of their properties. Density-functional theory (DFT) employing standard (semi-)local functionals encounters challenges due to pronounced self-interaction errors within the partially filled d shells of transition-metal (TM) elements. Here, we demonstrate the efficacy of DFT with extended Hubbard functionals in accurately predicting the "digital" change in oxidation states of TM ions for mixed-valence phases at intermediate Li concentrations in phospho-olivine and spinel cathode materials. The resulting voltages exhibit remarkable agreement with experimental data [1,2].Our approach involves the use of onsite U and intersite V Hubbard parameters computed from density-functional perturbation theory with Lowdin-orthogonalized atomic orbitals, thus circumventing empirical factors [3,4]. Notably, the incorporation of intersite Hubbard V interactions proves indispensable for the precise prediction of thermodynamic quantities, particularly when electronic localization occurs amid inter-atomic orbital hybridization.Extending our investigation to vibrational spectroscopy, we calculate Raman spectra for these materials and find very good agreement with available experimental data [5]. Leveraging the robust and accurate computational framework based on extended Hubbard functionals, we embark on a high-throughput screening of Li-containing compounds, aiming to unveil novel and promising candidates for cathodes [6]. Our findings underscore the pivotal role of advanced DFT methodologies in advancing the discovery and design of high-performance battery materials.[1] I. Timrov, F. Aquilante, M. Cococcioni, N. Marzari, PRX Energy 1, 033003 (2022).[2] I. Timrov, M. Kotiuga, N. Marzari, Phys. Chem. Chem. Phys. 25, 9061 (2023).[3] I. Timrov, N. Marzari, M. Cococcioni, Phys. Rev. B 98, 045141 (2021).[4] I. Timrov, N. Marzari, M. Cococcioni, Phys. Rev. B 103, 085127 (2018).[5] L. Bastonero, N. Marzari, I. Timrov, in preparation.[6] C. Malica, L. Bastonero, M. Bercx, N. Marzari, I. Timrov, in preparation.

A theoretical method to characterize the resistance effects of nonflat terrain on wind fields in a parametric wind field model for tropical cyclones

Traditionally, an empirical speed-up factor was introduced to reflect the effects of nonflat terrain on near-surface wind speeds. In this paper, the resistance effects of nonflat terrain are considered by introducing the terrain drag coefficient in the parametric wind field model for tropical cyclones (TCs) with a theoretical method. Terrain effects on wind fields are investigated in complex areas along the coastal zone in China under TC conditions. The results show that the terrain drag coefficient is the function of the slope angle and is sensitive to the spatial resolution. After including the resistance effect of nonflat terrain, the TC intensities weaken overall during landfall, with a slight enhancement near the coastal zone. The wind speeds outside the radius of the maximum wind speed decrease, while the wind speeds within the radius of the maximum wind speed increase. Both the TC eye and the radius of maximum wind speed shrink, which is more obvious when the TC center is entirely over land. As a result, the location and magnitude of the maximum wind speed are affected by the nonflat terrain. The changed structure of the wind fields demonstrates the necessity of considering the effects of nonflat terrain in simulating the wind fields under TC conditions.

Experimental Determination of the Unusual CH Stretch Frequency of Protonated Fullerenes

We report experimental values for the CH stretch frequencies of the protonated fullerenes C60H+ and C70H+. Anharmonic frequency calculations at the B3LYP/6-31G level of theory, which are independent of empirical scaling factors, reproduce the experimental values to within approximately 5 cm−1. Scaling theoretical harmonic frequencies by applying factors derived for polycyclic aromatic hydrocarbons deviate significantly from the experimentally measured frequency. We attribute this deviation to the unusual hydrocarbon structure that affects the degree of anharmonicity of the CH stretch. This result allows us to propose an original, specific scaling factor of 0.9524 to correct harmonic frequencies of CH stretches of protonated fullerenes calculated at the B3LYP/6-311 + G(d,p) level of theory. The special spectral position of the protonated fullerene CH stretch bands makes it a diagnostic marker that may aid in their detection in the interstellar medium.

Validation of the Instructional Materials Motivation Survey among Medicine Resident Physicians

Purpose The Instructional Materials Motivation Survey (IMMS) was developed to measure motivational characteristics of a learning activity, building on Keller's Attention, Relevance, Confidence, Satisfaction (ARCS) motivation model. We aimed to validate IMMS scores using validity evidence of internal structure and relations with other variables. Methods Participants were internal medicine and family medicine residents who completed the IMMS following an online module on outpatient medicine, from 2005 to 2009. We used confirmatory factor analysis (CFA) to examine model fit using half the data (split-sample approach). Finding suboptimal fit, we conducted exploratory factor analysis (EFA) and developed a revised instrument. We evaluated this instrument with CFA using the remaining data. Associations were evaluated between IMMS scores and knowledge and other measures of motivation (Motivated Strategies for Learning Questionnaire, MSLQ). All analyses accounted for repeated measures on subjects. Results There were 242 participants. Although internal consistency reliabilities were good (Cronbach alpha ≥0.70), CFA of the original 36-item, 4-domain instrument revealed poor model fit for data sample 1. EFA found that reverse-scored items clustered strongly together. Further EFA using data sample 1, followed by CFA using data sample 2, found good fit for a 13-item, 4-domain model that omitted reverse-scored items (standardized root mean square residual 0.045, root mean square error of approximation 0.066, comparative fit index 0.96). Linear regression confirmed positive, statistically significant associations for most hypothesized relationships, including IMMS total with knowledge (r=0.19) and MSLQ total (r=0.53; both p&lt;.001). Examination of reverse-scored items suggested participant inattention but not acquiescence. Conclusions IMMS scores show good reliability and relations with other variables. However, the hypothesized and empirical factor structures do not align, and reverse-scored items show particularly poor fit. A 13-item, 4-domain scale omitting reverse-scored items showed good model fit.

RMS error analysis of spatial uniformity and energy stability of the laser beam in second harmonic generation.

The coupling of the energy stability and spatial uniformity of the laser beam before and after second harmonic generation (SHG) was analyzed. SHG experiments were performed using a Nd:YAG nanosecond laser and LBO crystals, and images, pulse shapes, and energies were measured. The relationship between energy stability and spatial uniformity uses a formula derived from the previous study to analyze changes in energy stability and spatial uniformity of the input beam and converted beam. In addition, the measured input beam shape and energy are compared with the results of applying the SHG converting equation considering pump depletion. Both methods were similar to the experimental results when corrected by empirical factors. Through SHG, it was confirmed that there is an optimal point of energy stability and spatial uniformity of the laser beam near the critical power.

Pressure Loss Modeling for Multi-Stage Obstacles in Pressurized Ducts

Estimating singular pressure losses for multi-stage obstacles in pressurized hydraulic ducts is a challenging task. An experimental study was conducted in a closed-loop hydrodynamic tunnel to characterize the pressure losses of a system consisting of a porous fibrous foam placed in front of a bar rack. The pressure losses of different foam–rack configurations were measured over a range of inlet velocities in order to highlight the mutual influence of their characteristics on the flow. The interdependence between the two stages has been evidenced by both the experimental results and additional numerical simulations using RANS (Reynolds-Averaged Navier–Stokes Equations) simulations with a k-ω SST turbulent closure model. The pressure losses were first modeled using two approaches based on the assumption of either independence or full dependence between the stages. The respective advantages and limitations of these approaches led to an improved analytical formula that considers the transition of the flow from the porous foam to the bar rack. By taking into account an empirical transition factor, the proposed model improves the head loss prediction for all tested configurations, with an average relative error between the formula and experimental results less than that of the two simpler approaches. This study improves our understanding of global pressure losses in multi-stage systems that include a porous foam or other filtering or clogging media in front of bar racks.