Spatial reconstruction of human motion by means of a single camera and a biomechanical model

The value of the results of the inverse dynamic analysis procedures used in the study of human tasks is dependent on the quality of the kinematic and kinetic data supplied to the biomechanical model that supports it. The kinematic data, containing the position, velocity and acceleration of all anatomical segments of the biomechanical model, result from the reconstruction of human spatial motion by means of the evaluation of the anatomic points positions that enable to uniquely define the position of all anatomical segments. Furthermore, the motion data must be kinematically consistent with the structure of the biomechanical model used in the analysis. The traditional photogrammetric methodologies used for the spatial reconstruction of the human motion require images of two or more calibrated and synchronized cameras. This is due to the fact that the projection of each anatomical point is described by two linear equations relating its three spatial coordinates with the two coordinates of the projected point. The need for the image of another camera arises from the fact that a third equation is necessary to find the original spatial position of the anatomical point. The methodology proposed here substitutes the projection equations of the second camera with the kinematic constraint equations associated with a biomechanical model in the motion reconstruction process. In the formulation the system of equations arising from the point projections and biomechanical model kinematic constraints, representing the constant length of the anatomical segments, are solved simultaneously. Because the system of equations has multiple solutions for each image, a strategy based on the minimization of a cost function associated to the smoothness of the reconstructed motion is devised. It is shown how the process is implemented computationally avoiding any operator intervention during the motion reconstruction for a given time period. This leads to an automated computer procedure that ensures the uniqueness of the reconstructed motion. The result of the reconstruction process is a set of data that is kinematically consistent with the biomechanical model used. Through applications of the proposed methodology to several sports exercises its benefits and shortcomings are discussed.     

结构方程在心理学研究中的应用

近年来,在教育、社会及心理学等研究领域,结构方程模型(SEM,Structural Equation Modeling)已成为重要的多变量分析方法,并日益受到广大研究者的重视。本文旨在对SEM作简要概述,并讨论其在心理学研究中的应用,以及在应用过程中应该遵循的标准和需要注意的一些问题。     

Evaluating Three Models of Intimate Relationships

The purpose of this study was to evaluate three models of intimate relationships: attachment, elementary pragmatic, and selfhood. These models were evaluated with three instruments respectively constructed to evaluate the validity of each model. One convenience group of functioning individuals and three experimental groups of inpatients and outpatients were administered the three instruments. All three instruments showed relatively high internal consistency and discriminated among the four groups. Significant correlations were found among the measure of attachment with measures of the pragmatic elementary and selfhood models. These correlations indicate that all three instruments were measuring similar aspects of intimate relationships. Clinical and preventive implications and applications of these models are briefly discussed.     

Minimax d-optimal designs for item response theory models

Various different item response theory (IRT) models can be used in educational and psychological measurement to analyze test data. One of the major drawbacks of these models is that efficient parameter estimation can only be achieved with very large data sets. Therefore, it is often worthwhile to search for designs of the test data that in some way will optimize the parameter estimates. The results from the statistical theory on optimal design can be applied for efficient estimation of the parameters.A major problem in finding an optimal design for IRT models is that the designs are only optimal for a given set of parameters, that is, they are locally optimal. Locally optimal designs can be constructed with a sequential design procedure. In this paper minimax designs are proposed for IRT models to overcome the problem of local optimality. Minimax designs are compared to sequentially constructed designs for the two parameter logistic model and the results show that minimax design can be nearly as efficient as sequentially constructed designs.     

On the Value of the Panentheistic Analogy: A Response to Willem Drees

The author expresses appreciation to Professor Drees for his careful and mostly accurate reading of God and Contemporary Science. The exchange provides the opportunity to step back from the specifics of the debate and clarify what it is that gives rise to the increasing talk of panentheism within religion‐science discussions today. What is the central challenge that the natural sciences raise for theistic belief? How far does panentheism go toward answering this challenge, and what work still needs to be done? Locating the book in this way clarifies questions of where the burden of proof lies, especially with regard to the relation of physical, mental, and spiritual qualities.     

Analysis of multinomial models under inequality constraints: Applications to measurement theory

Multinomial random variables are used across many disciplines to model categorical outcomes. Under this framework, investigators often use a likelihood ratio test to determine goodness-of-fit. If the permissible parameter space of such models is defined by inequality constraints, then the maximum likelihood estimator may lie on the boundary of the parameter space. Under this condition, the asymptotic distribution of the likelihood ratio test is no longer a simple χ² distribution. This article summarizes recent developments in the constrained inference literature as they pertain to the testing of multinomial random variables, and extends existing results by considering the case of jointly independent mutinomial random variables of varying categorical size. This article provides an application of this methodology to axiomatic measurement theory as a means of evaluating properly operationalized measurement axioms. This article generalizes Iverson and Falmagne’s [Iverson, G. J. & Falmagne, J. C. (1985). Statistical issues in measurement. Mathematical Social Sciences, 10, 131-153] seminal work on the empirical evaluation of measurement axioms and provides a classical counterpart to Myung, Karabatsos, and Iverson’s [Myung, J. I., Karabatsos, G. & Iverson, G. J. (2005). A Bayesian approach to testing decision making axioms. Journal of Mathematical Psychology, 49, 205-225] Bayesian methodology on the same topic.     

Models of Psychotherapy: Implications for Pastoral Care Practice

Pastoral care givers are called to provide care and counseling to parishioners that are suffering in many ways. A core question is what does a pastor rely on to provide this care? Pastors usually call on models of psychotherapy to inform their care giving. A framework of theological anthropology, cosmology, soteriology and harmatiology is developed for analyzing the worldviews inherent in models of psychotherapy. The specific models of Adler’s Individual Psychology, Narrative therapy, Horney’s personality theory, and Intersubjective theory are used to demonstrate the application of this framework. Several pastoral care implications are developed following the application of the framework.