Field-based Models Research Articles

Four Models For Predicting Pediatric Body Composition For Anglo And Hispanic Youth

Body composition is becoming recognized as a critical component in the reporting of health-related measures in children due to the increase in metabolic disorders. However, measuring body composition is often difficult due to lack of training, privacy issues and cost of accurate measuring devices. Therefore, it may be advisable to develop a prediction equation that can be used to accurately determine body composition in youth. PURPOSE: To develop a body composition prediction equation for elementary age youth. METHODS: A stratified sampling method was used to select volunteer children for this study. Height, weight, BMI, age, and skinfold were collected on 886 Anglo (n=445) and Hispanic (n=441) children between the ages of 7 and 12 (9.1+2.1). Body composition was determined by using a standard two site procedure that is common in most schools. Group body fat means were examined through two-way ANOVA. Correlation matrices were run with each group on the variables of height, weight, BMI, age, and body fat percent. Regression prediction models were developed using stepwise regression techniques. Cook‘s D and Mahalanobis D distances were examined to determine outlier affects. R2 and standard error of the estimate (SEE) were examined for each resulting model. RESULTS: The data was split by gender and ethnicity after two-way ANOVA revealed a significant difference between males and females and between Anglo and Hispanic groups. Prediction models were established with the following variables for the following groups: Anglo Females: BMI, Weight, Age (R2 =.555, SEE = 4.34); Hispanic Females: Weight, Height (R2 =.478, SEE = 4.52); Anglo Males: BMI, Weight, Age (R2 =.561, SEE = 5.83); Hispanic Males: Weight, Age (R2 =.403, SEE = 5.32). All models indicated acceptable means and ranges for Cook‘s and Mahalanobis distances. CONCLUSIONS: The results indicate that reasonable field-based prediction models can be used as a general assessment tool when clinical methods are not available or practical within Anglo and Hispanic youth populations. The prediction variables also indicated consistency within ethnicities. Weight, age and BMI are consistent body fat prediction variables for Anglo youth while weight is a consistent body fat prediction variable for Hispanic youth. Future studies should examine these variables more closely.

Supporting Undergraduates in Conducting Field-Based Research: A Perspective from On-Site Faculty and Staff

Supporting Undergraduates in Conducting Field-Based Research: A Perspective from On-Site Faculty and Staff

Field-Based Internship Models for Alternative Certification of Science and Mathematics Teachers: Views of Interns, Mentors, and University Educators

In response to shortages of science and mathematics teachers in the U.S., many states have promoted alternative routes to certification in which individuals with non-education undergraduate degrees can become certificated in shorter timeframes than in traditional programs. One consideration in designing alternative programs is how to arrange field-based internships that help provide transformative pathways to non-traditional students in becoming a teacher. The purpose of this study was to understand the views of interns, their mentor teachers, and university personnel who participated in one alternative certification program regarding the best structures for field experiences. Through an analysis of artifacts collected in a meeting where we discussed the pros and cons of five different intership models as well as interviews with individuals in each stakeholder group, we were able to understand the various viewpoints. We found that, although perspectives were consistent within each group, they differed across the three groups. These differences were grounded in the personal needs and experiences of each group. Although our findings point to no “perfect” internship model to support the transformation of alternative certification students into teachers, they have implications for the design and enactment of field-based internships in such programs.

Voting techniques for expert search

In an expert search task, the users’ need is to identify people who have relevant expertise to a topic of interest. An expert search system predicts and ranks the expertise of a set of candidate persons with respect to the users’ query. In this paper, we propose a novel approach for predicting and ranking candidate expertise with respect to a query, called the Voting Model for Expert Search. In the Voting Model, we see the problem of ranking experts as a voting problem. We model the voting problem using 12 various voting techniques, which are inspired from the data fusion field. We investigate the effectiveness of the Voting Model and the associated voting techniques across a range of document weighting models, in the context of the TREC 2005 and TREC 2006 Enterprise tracks. The evaluation results show that the voting paradigm is very effective, without using any query or collection-specific heuristics. Moreover, we show that improving the quality of the underlying document representation can significantly improve the retrieval performance of the voting techniques on an expert search task. In particular, we demonstrate that applying field-based weighting models improves the ranking of candidates. Finally, we demonstrate that the relative performance of the voting techniques for the proposed approach is stable on a given task regardless of the used weighting models, suggesting that some of the proposed voting techniques will always perform better than other voting techniques.

Derivative-Neural Spectroscopy for Hyperspectral Bathymetric Inversion*

Bathymetry is an important variable in scientific and operational applications. The research objectives in this study were to estimate bathymetry based on derivative reflectance spectra used as input to a multilayer perceptron artificial neural network (ANN) and to evaluate the efficacy of field and simulated training/testing data. ANNs were used to invert reflectance field data acquired in optically shallow coastal waters. Results indicate that for the simulation-based models, nonderivative spectra yielded more accurate bathymetry retrievals than the derivative spectra used as ANN input. However, for the empirical field-based models, derivative spectra were superior to nonderivative spectra as ANN input. This study identifies circumstances under which derivative spectra are useful in bathymetry estimation, and thus increases the likelihood of obtaining accurate inversions.

Comparison of implicit solvent models for the simulation of protein–surface interactions

Empirical force field-based molecular simulations can provide valuable atomistic-level insights into protein-surface interactions in aqueous solution. While the implicit treatment of solvation effects is desired as a means of improving simulation efficiency, existing implicit solvent models were primarily developed for the simulation of peptide or protein behavior in solution alone, and thus may not be appropriate for protein interactions with synthetic material surfaces. The objective of this research was to calculate the change in free energy as a function of surface-separation distance for peptide-surface interactions using different empirical force field-based implicit solvation models (ACE, ASP, EEF1, and RDIE with the CHARMM 19 force field), and to compare these results with the same calculations conducted using density functional theory (DFT) combined with the self-consistent reaction field (SCRF) implicit solvation model. These comparisons show that distinctly different types of behavior are predicted with each implicit solvation method, with ACE providing the best overall agreement with DFT/SCRF calculations. These results also identify areas where ACE is in need of improvement for this application and provide a basis for subsequent parameter refinement.

Meta-Analytic Review of Responsiveness-To- Intervention Research: Examining Field-Based and Research-Implemented Models

A responsiveness-to-intervention (RTI) approach to diagnosing LD is a leading alter native to current practice. This study con ducted a meta-analytic review of research on four existing large-scale RTI models and other models implemented for research. Twenty-four effect sizes and unbiased esti mates of effect (UEE) were computed. Results found a larger UEE for studies of existing RTI models than those implemented by university faculty for research, but both were strong. The UEE for student achievement and sys temic outcomes both exceeded 1.0, but the UEE for systemic outcomes among field-based RTI models was nearly twice as large as for stu dent outcomes. Further, RTI models imple mented for research led to an UEE of 1.14 for student outcomes and 0.47 for systemic out comes. The mean percentage of nonrespon ders in the studies was 19.8% ( SD= 12.5), and an average of 1.68% ( SD = 1.45) of the stu dent population was placed into special edu cation. Implications for practice and future research are included.

Comparative reliability evaluation of lateritic soils as hydraulic barriers

A numerical investigation to determine the existence or otherwise of congruence between laboratory-based and field-based models for predicting hydraulic conductivity of compacted clay liners has been conducted. The comparisons here are based on values of the reliability index estimated with the use of the two models for cases when hydraulic conductivity is assumed to be normally and lognormally distributed. The laboratory reduced Proctor and modified Proctor compactive efforts were assumed to correspond to the lowest and highest compactor weights (165 kN and 338 kN for sheepsfoot rollers only from literature) respectively. The standard Proctor compactive effort was assumed to correspond to the mean compactor weight of 261.4 kN. Reliability estimates from the laboratory-based model were consistently higher than the corresponding values from the field-based model for each of the variables common to the two models. As laboratory samples usually involve small samples which are often unrepresentative of field situations, it is considered that reliability levels estimated with the use of the field-based model provide more realistic assessment of compacted lateritic soils as hydraulic barriers. Compactor weight of 300 kN and above may be needed for effective compaction of lateritic soil liners. Reliability-based designs of lateritic soil liners should incorporate appropriate probability distribution types for variables in the field-based model.

QMQSAR: Utilization of a semiempirical probe potential in a field‐based QSAR method

A semiempirical quantum mechanical approach is described for the creation of molecular field-based QSAR models from a set of aligned ligand structures. Each ligand is characterized by a set of probe interaction energy (PIE) values computed at various grid points located near the surface of the ligand. Single-point PM3 calculations afford these PIE values, which represents a pool of independent variables from which multilinear regression models of activity are built. The best n-variable fit is determined by constructing an initial regression using standard forward stepwise selection, followed by refinement using a simulated annealing technique. The resulting fit provides an easily interpreted 3D physical model of ligand binding affinity. Validation against three literature datasets demonstrates the ability of the semiempirical potential to model critical binding interactions in diverse systems.

A Theoretical Study of Residual Stress Effects on Fatigue Life Prediction

Recently, the trend has been toward the use of the full subsurface stress field in rolling element bearing fatigue life prediction (stress field-based life models). By using the stress field-based bearing life models, more accurate assessments of such things as fitting practice and thermal treatments on the bearing performance are achieved. However, one aspect missing in most models has been the consideration of the changing residual stress during operation of the bearing. This study was conducted to investigate the time dependent residual stress on contact fatigue life predictions. This study concluded that the changes in residual stress during operation were most likely a fatigue reaction of the material to the pre-fatigue residual stress and cyclic contact stress fields. The materials fatigue response changes the instantaneous values of the material constants in most stress field-based life equations, thus making them in-calculable. As such, the pre-fatigue residual stress field should be used in the stress field-based models. Presented as a Society of Tribologists and Lubrication Engineers Paper at the STLE/ASME Tribology Conference in San Francisco, CA October 21–24, 2001

Towards decentralised and more school-focused teacher preparation and professional development in Zimbabwe: the role of mentoring

The last decade has witnessed a pronounced trend in many countries of shifting from university- or college-based models of teacher preparation and professional development to more field-based models. Zimbabwe is on the threshold of a similar movement. Field-based models, however, tend to rely heavily on mentor involvement. In this article the authors examine the specific situation of Zimbabwe in this regard and generate research questions on mentoring that arise naturally from a consideration of a number of contextual features. The main questions have to do with the nature of experienced teacher to experienced teacher mentoring, and the content and process of subject-specific mentoring. This article therefore makes a contribution to the continuing discussion and building up in the literature of a knowledge base on mentoring-based models of teacher education.

Fe-rich tholeiitic liquids and their cumulate products in the Pleasant Bay layered intrusion, coastal Maine

Fe-rich tholeiitic liquids are preserved as chilled pillows and as the chilled base of a 27 meter thick macrorhythmic layer in the Pleasant Bay mafic-silicic layered intrusion. The compositions of olivine (Fo1) and plagioclase (An13−8) in these extremely fine grained rocks suggest that they represent nearly end stage liquids that formed by fractionation of tholeiitic basalt. Their major element compositions (∼17.5 wt% FeOT and 54 wt%SiO2) closely resemble highly evolved glasses in the Loch Ba ring dike and some recent estimates of end-stage liquids related to the Skaergaard layered intrusion, and are consistent with recent experimental studies of tholeiite fractionation. Their trace element compositions are consistent with extensive earlier fractionation of plagioclase, olivine, clinopyroxene, ilmenite, magnetite and apatite. The mineral assemblage of the chilled rocks (olivine, clinopyroxene, quartz, ilmenite and magnetite), apatite saturation temperatures, and very low Fe3+/Fe2+indicate conditions of crystallization at temperatures of about 950 °C and fO2 about two log units below FMQ. Cumulates that lie about 3 meters above the chilled base of the macrorhythmic layer contain cumulus plagioclase, olivine, clinopyroxene, ilmenite, apatite and zircon. This mineral assemblage and the Fe-Mg ratio in clinopyroxene cores suggest that this cumulate was in equilibrium with a liquid having a composition identical to that of the chilled margin which lies directly beneath it. The high FeOT and low SiO2 concentrations of this cumulate (23.3 and 45.8 wt%, respectively) are comparable to those in late stage cumulates of the Skaergaard and Kiglapait intrusions. This association of a chilled liquid and cumulate in the Pleasant Bay intrusion suggests that late stage liquids in tholeiitic layered intrusions may have been more SiO2-rich than field-based models suggest and lends support to recent experimental studies of tholeiite fractionation at low fO2 which indicate that saturation of an Fe-Ti oxide phase should cause FeOT to decrease in the remaining liquid.

Hydraulics of interrill overland flow on stone-covered desert surfaces

The hydraulics of interrill overland flow on stone-covered desert surfaces depend on the resistance to flow, which may be partitioned into grain resistance, form resistance, wave resistance, and rain resistance. Efforts to model large-scale roughness in open channels suggest that resistance to overland flow on such surfaces is a function of grain Reynolds number, Froude number, flow depth, and the size, shape, spacing, and pattern of the roughness elements. The effect of flow depth on flow resistance f is often hidden in the flow Reynolds number Re. In laboratory and field studies alike, f-Re relations have been found to be convex-upward and negatively sloping, and these shapes have been explained in terms of the progressive inundation of the roughness elements. Where laboratory- or field-based models have been developed for predicting f, they invariably contain percent stone cover. The prominence of this variable reflects the strong influence of stone size and spacing on flow resistance. A laboratory study shows that where the Froude number F > 0.50, wave resistance increases with stone cover and dominates resistance to flow on all surfaces with stone covers greater than 10%. A field study indicates that where F < 0.50 and wave resistance is inconsequential, grain and form resistance typically account for about 5% and 95% of f, respectively. These findings have important implications for sediment transport modeling because percent grain resistance is equal to percent grain shear stress, and it has recently been suggested that in overland flow, as in river flow, sediment transport capacity is determined by grain shear stress rather than total shear stress. A laboratory study, however, demonstrates that this is not the case. Sediment transport capacity is in fact greater than predicted by grain shear stress because energy dissipated in the wakes of roughness elements in overland flow is transformed into turbulence sufficiently close to the bed to affect sediment transport.

Communication in Collaboration/Consultation: Effective Practices in Schools

Communication is the core, underlying theme in collaboration/consultation. The role that communication plays in field-based school models is explored through a description of projects currently in operation across five states. These programs, spanning elementary, middle, and secondary schools, are all deemed successful through some form of internal or external review. Common characteristics of these programs (e.g., each serve a different, but specifically designated/limited student population) are identified. Concerns related to the gap between experimental research coming from the university and public school realities are noted.

The prediction of noise from urban traffic under interrupted flow conditions

A computer model is described for predicting noise levels generated by urban road traffic under interrupted flow conditions. The model is composed of two subsections. The first predicts the propagation characteristics of sound in typical street configurations and the second simulates the flow of road traffic in urban areas. The two subsections are combined to yield a model capable of predicting traffic noise levels in urban conditions. Predictions obtained from application of this model are compared with those given from application of predictive models based upon field measurements. The agreement between the predictions is good. It is shown that the model described in this paper can predict noise levels for situations which existing field-based models cannot handle.