Causal ordering of physical self-concept and exercise behavior: Reciprocal effects model and the influence of physical education teachers.

Does prior physical self-concept influence subsequent exercise behavior? On the basis of a large sample of physical education classes (2,786 students, 200 classes, 67 teachers) collected early (Time 1) and late (Time 2) in the school year, findings support a reciprocal effects model in which prior physical self-concept and exercise behavior both influence subsequent physical self-concept and exercise behavior. Whereas variables from the theory of planned behavior (TOPB; behavioral intentions, perceived behavioral control, exercise attitudes) also contributed to the prediction of subsequent exercise behavior, the effect of prior physical self-concept was significant for subsequent outcomes after controlling these variables, suggesting that the TOPB should be supplemented with self-concept measures. On the basis of multilevel models, there were systematic differences in these variables for students taught by different teachers that generalized over time and across different classes taught by the same teacher. Support for the reciprocal effects model was robust. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

FC++: Functional tools for object‐oriented tasks

FC++ is a library for programming functionally in C++. Compared to other C++ functional programming libraries, FC++ is distinguished by its powerful type system which allows the manipulation of parametrically polymorphic functions (e.g., passing them as arguments to other functions and returning them as results). In this paper, we show how FC++ can be used in common object‐oriented programming tasks. We demonstrate FC++ implementations of several common design patterns (Adapter, Builder, Command, and more). Compared to conventional C++ implementations of these patterns, our implementations are either simpler (in that fewer classes/dependencies are needed), more efficient, or more type‐safe (thanks to parametric polymorphism and type inference). Copyright © 2002 John Wiley & Sons, Ltd.     

On the Generation of Time-Evolving Regional Data*

Benchmarking of spatio-temporal databases is an issue of growing importance. In case large real data sets are not available, benchmarking requires the generation of artificial data sets following the real-world behavior of spatial objects that change their locations, shapes and sizes over time. Only a few innovative papers have recently addressed the topic of spatio-temporal data generators. However, all existing approaches do not consider several important aspects of continuously changing regional data. In this report, a new generator, called generator of time-evolving regional data (G-TERD), for this class of data is presented. The basic concepts that determine the function of G-TERD are the structure of complex 2-D regional objects, their color, maximum speed, zoom and rotation-angle per time slot, the influence of other moving or static objects on the speed and on the moving direction of an object, the position and movement of the scene-observer, the statistical distribution of each changing factor and finally, time. Apart from these concepts, the operation and basic algorithmic issues of G-TERD are presented. In the framework developed, the user can control the generator response by setting several parameters values. To demonstrate the use of G-TERD, the generation of a number of sample data sets is presented and commented. The source code and a visualization tool for using and testing the new generator are available on the Web.¹ Thus, it is easy for the user to manipulate the generator according to specific application requirements and at the same time to examine the reliability of the underlying generalized data model.     

Preserving mapping consistency under schema changes

In dynamic environments like the Web, data sources may change not only their data but also their schemas, their semantics, and their query capabilities. When a mapping is left inconsistent by a schema change, it has to be detected and updated. We present a novel framework and a tool (ToMAS) for automatically adapting (rewriting) mappings as schemas evolve. Our approach considers not only local changes to a schema but also changes that may affect and transform many components of a schema. Our algorithm detects mappings affected by structural or constraint changes and generates all the rewritings that are consistent with the semantics of the changed schemas. Our approach explicitly models mapping choices made by a user and maintains these choices, whenever possible, as the schemas and mappings evolve. When there is more than one candidate rewriting, the algorithm may rank them based on how close they are to the semantics of the existing mappings.Received: 13 January 2004, Accepted: 26 March 2004, Published online: 12 August 2004Edited by: M. Carey     

Micromorphology,composition and origin of the orange patina on the marble surfaces of Propylaea (Acropolis,Athens)

This paper is an attempt to contribute to the discussion started in the 1980s and continuing until today, on the origin of orange-brown patinas observed on marble surfaces. SEM and XRD were used in the study of the orange-brown patina growing at the east stoa of Propylaea, at the Acropolis of Athens. The patina consists of an extremely compact, homogenous, 500-microm-thick layer, mainly of hydroxyapatite. The outer part (50 microm) of the layer presents an orange colour attributed to iron in clay particles, which were deposited on the surface of the patina and have gradually been diffused in the bulk. The interface between the phosphatic layer and the marble is very uneven and full of cavities colonised by microorganisms. The phosphatic layer penetrates into the grain boundaries and fills the empty space between the grains. The presence of biological attack at the interface causes progressive erosion and detachment of both the patina and the marble. The minimum presence of oxalates, the absence of microorganisms or remnants of them in the phosphatic layer, the homogeneity and compactness of the patina, give evidence against the theory of biogenic origin. It is suggested that the layer originates from an artificial coating deliberately applied onto the marble surface for protective or aesthetic reasons, when the marble had already been weathered. Possible manmade pastes are suggested.     

Bioreactors in Tissue Engineering

Tissue engineering is a promising interdisciplinary scientific field of regenerative medicine. Aiming at the structural and functional restoration of damaged tissues and organs, it possesses a role of significant socioeconomical impact. In the course towards the ultimate goal of artificially constructed natural organs, our knowledge of the elementary constitutive components of living organisms and the intrinsic mechanisms that drive their interactions is greatly enhanced. Bioreactors are valuable tools providing the technological means to investigate fundamental issues for basic research and to improve tissue‐engineering products for clinical applications. They are devices enabling the in vitro simulation of the in vivo biological, physical and mechanical environment of growing tissues. In this review paper, we discuss the general demands defining the design considerations for modern bioreactor systems. These criteria originate from physiological characteristics of the cells and biochemical and mechanical properties of the extracellular matrix (ECM). In this context, we present an overview of the various bioreactor systems dedicated to the study of specific functional tissues developed by numerous research groups.     

An optimisation study of colour measurements on digitised slides of painted works of art

This paper deals with the problem of the colorimetric fidelity of digitised colour slides of painted works of art. A six-matrix conversion model was derived that permitted the transformation of any RGB device-dependent measurement on digitised colour slides to XYZ CIE 1931 device-independent values. The model was calibrated against a reference colour chart. Eighty-one uniformly-painted colour samples were photographed together with a painting on a 4 × 5 inch colour slide that was digitised using a high resolution scanner. A 3 × 3 transformation matrix, of the corrected R, G and B values and the respective X, Y and Z tristimulus values provided by spectrophotometry, was calculated. The calculated matrix was then applied to a 13th century Byzantine fresco, captured on the same digitised slide, to transform the RGB measurements to XYZ CIE 1931 device-independent values which were then converted into the L* a* b* CIE 1976 colorimetric system.     

What makes a region entrepreneurial? Evidence from Britain

There is a great deal of variation in the levels of entrepreneurship, or rates of self-employment, across the regions of Britain. Over the period 1983–1995, average self-employment in the North, Scotland, and the West Midlands was respectively 25%, 15%, and 15% lower than the national average, whereas in the South West, East Anglia, and Wales it was respectively 28%, 23%, and 21% higher. We develop a theoretical model of regional self-employment, and estimate the roles of labour market conditions, labour force characteristics, industry composition, and region-specific factors such as entrepreneurial human capital. Our results suggest that all of these factors are important, and that regional heterogeneity and regionally correlated disturbances must be accounted for when estimating regional self-employment relationships. Received: November 1998 / Accepted: July 1999     

Multilayer Resuspension of Small Identical Particles by Turbulent Flow

ABSTRACT

A model for the resuspension of a multilayer deposit by turbulent flow is developed. The resuspension rate is obtained by solving a set of coupled, first-order kinetic equations. The multilayer resuspension rate depends explicitly on single-particle resuspension rates that are determined from a modified energy-transfer model. The surface-particle and particle-particle interaction potentials are calculated by a microscopic approach based on the integration of the Lennard-Jones intermolecular interaction potential. The effect of the surface roughness, which leads to a distribution of the adhesive forces, is considered, as well as the energy transfer from the fluctuating part of the turbulent flow to the particle. It is shown that for a geometrical arrangement of deposited particles with a co-ordination number of two (particles stacked on top of each other) particles from the top layers resuspend at lower friction velocities than particles adjacent to the surface. The predicted long-term resuspension rate decays algebraically with exposure time. Calculations are presented for a two-layer deposit of either SnO₂ and Al₂O₃ particles on a stainless steel surface.