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At least 217 records · Page 12Linked to original sources
PubMed2006

Multi-dimensional profiling of medical students' cognitive models about learning.

INTRODUCTION: In current constructivist paradigms, learners' previous subject-matter knowledge, or cognitive models, provide the foundations for the construction of new knowledge. Learners' cognitive models about learning also mediate students' capacities to learn in their chosen topics of study. The diverse backgrounds of students entering medicine suggest that they might come to medical studies equipped with a wide variety of cognitive models about learning. Some current theories tend to reduce students' cognitions about learning to parsimonious representations, such as surface-deep approaches or mastery-performance goals. It is possible that such reduced representations underrepresent, or misrepresent, the complexity of students' cognitive models about learning. Good quality teaching needs to take account of learners' cognitive models, not just about subject matter, but also about learning. This study investigated the diversity and complexity of medical students' cognitive models about learning. METHODS: A total of 7 graduate entry, clinical-year medical students volunteered for in-depth interviews about learning. NUD*IST text analysis software and correspondence analysis were employed to identify dimensions and to profile students' responses. RESULTS: The correspondence analysis identified a significant 4-dimensional solution that illustrates the contributions of multiple variables to students' cognitive models about learning. Individual profiles highlight diversity between participants. DISCUSSION: This study provides evidence that students' cognitive models about learning are complex and highly differentiated. Representations of what students know about learning need to take account of such complexity in order to inform instructional practice more adequately.

Cognition↗
PubMed2003

Experimental verification of the roles of intrinsic matrix viscoelasticity and tension-compression nonlinearity in the biphasic response of cartilage.

A biphasic-CLE-QLV model proposed in our recent study [2001, J. Biomech. Eng., 123, pp. 410-417] extended the biphasic theory of Mow et al. [1980, J. Biomech. Eng., 102, pp. 73-84] to include both tension-compression nonlinearity and intrinsic viscoelasticity of the cartilage solid matrix by incorporating it with the conewise linear elasticity (CLE) model [1995, J. Elasticity, 37, pp. 1-38] and the quasi-linear viscoelasticity (QLV) model [Biomechanics: Its foundations and objectives, Prentice Hall, Englewood Cliffs, 1972]. This model demonstrates that a simultaneous prediction of compression and tension experiments of articular cartilage, under stress-relaxation and dynamic loading, can be achieved when properly taking into account both flow-dependent and flow-independent viscoelastic effects, as well as tension-compression nonlinearity. The objective of this study is to directly test this biphasic-CLE-QLV model against experimental data from unconfined compression stress-relaxation tests at slow and fast strain rates as well as dynamic loading. Twelve full-thickness cartilage cylindrical plugs were harvested from six bovine glenohumeral joints and multiple confined and unconfined compression stress-relaxation tests were performed on each specimen. The material properties of specimens were determined by curve-fitting the experimental results from the confined and unconfined compression stress relaxation tests. The findings of this study demonstrate that the biphasic-CLE-QLV model is able to describe the strain-rate-dependent mechanical behaviors of articular cartilage in unconfined compression as attested by good agreements between experimental and theoretical curvefits (r2 = 0.966 +/- 0.032 for testing at slow strain rate; r2 = 0.998 +/- 0.002 for testing at fast strain rate) and predictions of the dynamic response (r2 = 0.91 +/- 0.06). This experimental study also provides supporting evidence for the hypothesis that both tension-compression nonlinearity and intrinsic viscoelasticity of the solid matrix of cartilage are necessary for modeling the transient and equilibrium responses of this tissue in tension and compression. Furthermore, the biphasic-CLE-QLV model can produce better predictions of the dynamic modulus of cartilage in unconfined dynamic compression than the biphasic-CLE and biphasic poroviscoelastic models, indicating that intrinsic viscoelasticity and tension-compression nonlinearity of articular cartilage may play important roles in the load-support mechanism of cartilage under physiologic loading.

Animals↗
PubMed1999

Predicting methylphenidate response in children with ADHD: theoretical, empirical, and conceptual models.

OBJECTIVE: To evaluate the theoretical merit and empirical validity of models designed to predict response to methylphenidate (MPH) among children with attention-deficit/hyperactivity disorder (ADHD). METHOD: Seventy-six children with ADHD received each of 4 counterbalanced doses of MPH (5, 10, 15, and 20 mg) in the context of a double-blind, placebo-controlled, within-subject (crossover) experimental design. Logical and conceptual foundations of 3 models of MPH response were subjected to critical scrutiny, and patterns of relationship anticipated on the basis of these models were subjected to empirical analysis. RESULTS: The conceptual foundations of all reviewed models were found to be substantially flawed, and none provided an adequate empirical basis for predicting response to MPH among children with ADHD. CONCLUSIONS: The observed pattern of relationships suggests that magnitudes of response to MPH in domains of classroom attention and behavioral disinhibition are correlated and differentially predictive of response on measures of academic performance and teacher-rated behavior.

Attention Deficit Disorder with Hyperactivity↗
PubMed2002

On the microscopic foundations of elasticity.

The modeling of the elastic properties of disordered or nanoscale solids requires the foundations of the theory of elasticity to be revisited, as one explores scales at which this theory may no longer hold. The only cases for which microscopically based derivations of elasticity are documented are (nearly) uniformly strained lattices. A microscopic approach to elasticity is proposed. As a first step, microscopically exact expressions for the displacement, strain and stress fields are derived. Conditions under which linear elastic constitutive relations hold are studied theoretically and numerically. It turns out that standard continuum elasticity is not self-evident, and applies only above certain spatial scales, which depend on details of the considered system and boundary conditions. Possible relevance to granular materials is briefly discussed.

Journal Article↗
PubMed2004

Modeling and convergence analysis of distributed coevolutionary algorithms.

A theoretical foundation is presented for modeling and convergence analysis of a class of distributed coevolutionary algorithms applied to optimization problems in which the variables are partitioned among p nodes. An evolutionary algorithm at each of the p nodes performs a local evolutionary search based on its own set of primary variables, and the secondary variable set at each node is clamped during this phase. An infrequent intercommunication between the nodes updates the secondary variables at each node. The local search and intercommunication phases alternate, resulting in a cooperative search by the p nodes. First, we specify a theoretical basis for a class of centralized evolutionary algorithms in terms of construction and evolution of sampling distributions over the feasible space. Next, this foundation is extended to develop a model for a class of distributed coevolutionary algorithms. Convergence and convergence rate analyzes are pursued for basic classes of objective functions. Our theoretical investigation reveals that for certain unimodal and multimodal objectives, we can expect these algorithms to converge at a geometrical rate. The distributed coevolutionary algorithms are of most interest from the perspective of their performance advantage compared to centralized algorithms, when they execute in a network environment with significant local access and internode communication delays. The relative performance of these algorithms is therefore evaluated in a distributed environment with realistic parameters of network behavior.

Journal Article↗
PubMed1995

The place of suicide prevention in the spectrum of intervention: definitions of critical terms and constructs.

The authors trace the evolution of prevention models and conceptual foundations for the prevention of disorders starting with the public health/medical model and concluding with the contemporary model recently proposed by the Institute of Medicine of the National Academy of Sciences. They compare and contrast the contributions of each model toward the theoretical reduction of suicide in the general population. Risk and protective factors as they relate to suicidal behaviors are identified. The paper explores conceptual frameworks used to understand population-level risk factors and moves toward a discussion of how to target individuals at risk for suicidal behaviors. First-order and second-order targets of change in prevention efforts are defined and examples provided.

Causality↗
PubMed1996

[Resource orientation in nursing. A contribution to the future in nursing in theory and practice].

The interest in recent health science discussions does not centre only on health risks but is also concerned with the question asked by the medical sociologist Aaron Antonovsky: under which conditions do people remain healthy or regain their health? This discussion is the background for a resource orientated nursing model which is presented here. In the first place the theoretical foundations of this model are considered and then new points of emphasis in a resource orientated practice of nursing which take account of already existing nursing models like Dorothea Orem's self-care model are pointed out. Finally the question is raised what contribution nursing research can make in establishing this model in the practice of nursing.

Health Resources↗
PubMed1979

Childhood leukemia as a model for cancer research: the Richard and Hinda Rosenthal Foundation Award Lecture.

Childhood acute lymphocytic leukemia (ALL) is a model for the study of disseminated cancer. It is always disseminated and relatively uniform, it is accessible to repetitive tissue sampling, and we have highly effective chemotherapy for it. The first systematic, controlled trials of cancer therapy were designed for patients with ALL by physicians with the courage and audacity to aim for cure of a "hopeless" disease. The concept of leukemia cell subpopulations in each patient received major clinical support from ALL. The pharmacological sanctuary, typified by the meninges, was first discovered and specifically attacked in ALL. Combination therapy, aggressive therapy during remission, phase-specific therapy, and the interrelationships of phases of therapy were developed first in ALL. Since leukemia cell features, such as T-cell characteristics, correlate with responsiveness to therapy, powerful new tools may be developed to improve the biological specifically of therapy. In addition to the gratifying results of therapy over the past two decades, childhood ALL continuity offers opportunities for biological research as well as improved therapy for ALL and other forms of disseminated cancer.

Adult↗
PubMed2006

Modified models of polymer phase separation.

In this paper we discuss continuum models of phase separation in polymer solutions, with emphasis on the thermodynamic foundation of these models. We demand that these models obey a free energy dissipation relation, which in the present context plays the role of the second law of thermodynamics, since the system is isothermal. First, we derive a modified two-fluid model for viscoelastic phase separation from nonequilibrium thermodynamics. Then we study the special case when only diffusion is present, and hydrodynamic effects are neglected. Numerical results demonstrate that our models show better stability properties and at the same time reproduce the expected physical phenomena such as volume shrinking and phase inversion. Our findings suggest that these important phenomena are caused by a diffusional asymmetry of the constituent molecules.

Journal Article↗
PubMed1992

On laying the foundations for an empirico-logical model of mental health nursing.

This paper argues that nursing is an elemental activity, the first concern of which is a person's experience of illness, not the causes of that experience. Any model of nursing should begin with an account of that experience and deduce from that what it is that nurses ought to do in order to explain what it is that they actually do. The logical form of such a model is delineated. An account of the experience of illness is offered and the nursing imperatives implied by such an account are stated in terms of securing client safety, obviating the client's experience by treatment and motivating the client to sustain or resume ordinary activities of life. These dimensions of nursing care--safety, treatment and motivation--were tested against the actual activities of mental health nurses in three services and were found to have utility as categories of nursing activity. A summary of that research is given and an outline of a model of mental health nursing suggested by the results is given.

Activities of Daily Living↗
PubMed2003

Evaluating the California Wellness Foundation's Health Improvement Initiative: a logic model approach.

The difficulties of conducting randomized trials to evaluate community-based initiatives have led some researchers to argue in favor of a case study "logic model" approach to evaluation. This article describes a case study logic approach adopted for the evaluation of one community initiative, the Health Improvement Initiative (HII) funded by the California Wellness Foundation (TCWF). The HII is a comprehensive, community-based initiative designed to improve population health by implementing and sustaining community-level systems changes. Nine communities received funding to create broad-based community coalitions (Health Partnerships) that were charged with developing and implementing action plans around systems change. The HII is being evaluated using a case-study logic-model approach that uses quantitative and qualitative data to construct indicators of coalition functioning, systems changes, and population health. By examining the relationship between these indicators over time, it should be possible to determine if any changes in intermediate or long-term outcomes are associated with Health Partnership activities.

California↗
PubMed2004

Adipogenesis: usefulness of in vitro and in vivo experimental models.

The use of experimental models is the foundation of experimental biology, so it is important to know how much the models can tell us about actual animals. Inconsistent or contradictory results from in vitro models are often associated with the perception that a particular model or results are somehow wrong and therefore cannot tell us anything important about how an animal works. In fact, in vitro conditions do not create new biology. Differences between in vitro and in vivo behavior can only result from the actual cellular repertoire, which provides a powerful tool to uncover new information. Adipose tissue research provides a useful context for examining this issue because the regulation of adipose growth and metabolism has important economic implications for livestock production. Examples are discussed in which either excess skepticism or narrow interpretation of results slowed progress toward our current understanding of adipose biology. Similarly, contemporary examples using genomics are used to suggest that large inconsistencies are still apparent with in vitro methods. Careful consideration of these inconsistencies may provide new insights.

Adipocytes↗
PubMed1996

Development and testing of a quality of life model for long-term female cancer survivors.

This research resulted in the evolution of a model depicting the quality of life of long-term female cancer survivors. The foundation for this model's development was Ferrell's (1993) breast cancer model, which incorporates physical, social, psychological and spiritual domains of life. The Ferrell model was adapted following focus-group discussions with 11 long-term female cancer survivors. The adjusted model included new categories, within each of Ferrell's initial domains, that were specific to the focus group participants. Administration of a new instrument, the Long-Term Quality of Life (LTQL), to 187 long-term female cancer survivors produced a final model that included the interaction of all four domains in six major concepts of quality of life. This new model, which reflects the complexity of life in long-term female cancer survivors, may be useful to health professionals in designing interventions to meet the unique needs of these women.

Activities of Daily Living↗
PubMed1989

The selection by ward managers of an appropriate nursing model for long-stay psychiatric patient care.

The Northern Ireland National Board of Nursing, Midwifery and Health Visiting has stipulated that models of nursing must be utilized on psychiatric nurse training wards. However, since there are approximately 40 such frameworks available to the practicing nurse a problem of choosing an appropriate one arises. The philosophical basis for this research centres around the assumption that all nurses regardless of specialty possess values and beliefs concerning four essential elements. These are: nursing, health, the person, and the environment. In addition the literature reveals that each of the recognized nursing models are also constructed around these four concepts, forming in many cases the very foundations of the model. Within this study it was possible to ask 95 ward managers from 49 long-stay psychiatric wards to view how different models deal with the four elements and to choose a model which best reflects not only their personal beliefs about nursing, health, person, and environment, but also the needs of their patients.

Adult↗