Observational learning of quantity conservation and Piagetian generalization tasks.

20 1st graders who had scored 9 or less on a pretest of 8 Piagetian criterion tasks were divided into control and experimental groups. Experimental Ss underwent an observational learning phase in which a model correctly performed the 1st task used in the pretest, giving correct conservation judgments supported by justifications alternately based on identity, compensation, or reversibility considerations. All Ss were given the same 8 Piagetian tasks used in the pretest on immediate, 1-wk, and 3-mo delayed posttests. The experimental group generalized conservation to several tasks. One category of Ss behaved as rote learners and maintained conservation only for tasks closely similar to the modeled task and on immediate and 1-wk delayed posttest; a 2nd group of genuine conservers progressively generalized the conservation rule to more difficult tasks. The control group remained nonconserving throughout. Results are explained with reference to the Piagetian concept of sequential equilibration. The social experience of observation appeared to activate a cognitive restructuring of the Ss' mental operations. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Le changement représentational affectif chez les enfants d'age préscolaire.

Presents a series of experiments focused on preschool children's ability to understand representational change in both the affective and physical domains. In Exp 1, 24 5-yr-olds were asked if they would rather play with a box of crayons or a box of cards. They were also asked how they felt once the box had been opened and they found paper instead of their chosen toy and what was really in the box. Results showed that children correctly answered the questions about past representation in both domains. However, they had difficulty in reporting their present negative emotional state. In Exp 2, 48 5-yr-olds were administered an affective representational task change task in which they first had to rank objects. They were told that they that would receive the most attractive toy but instead were given the least attractive toy (positive-negative emotional sequence) or vice versa (negative-positive emotional sequence). Results indicate that children correctly answered the representational change questions in the negative-positive sequence but not in the positive-negative sequence. Finally, in Exp 3, 24 4-yr-olds failed to perform both the representational change task from Exp 2 and the task from Exp 1. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the use of observability measures for sensor location in tubular reactor

In this paper we discuss the choice of sensor positions for a tubular reactor with a preset number of sensors. Different observability measures, based on the observability matrix (Kailath, Linear Systems, Prentice Hall, Englewood Cliffs, NJ, 1980; Callier and Desoer, Linear System Theory, Springer-Verlag, Berlin, 1991: Damak et al., DYCORD '92, 1992, pp. 315–320), the observability gramian (Callier and Desoer, 1991) as well as on the Popov-Belevitch-Hautus rank test (Kailath. 1980) will be considered for locating optimal sensor positions. The analysis is carried out on the reduced finite-dimensional model of the process. The results of these investigations will be illustrated in simulation and put in perspective with the modal observability properties of the original infinite-dimensional model.     

Leonardo and Theoretical Mathematics

Leonardo’s mathematical notes bear witness to a work in progress and allow us to look directly into the mind of the writer. In Leonardo we find two of the three fundamental classical geometric problems: the duplication of the cube and the quadrature of the circle. While Leonardo is extremely familiar with two-dimensional geometry problems, and proposes playful graphic exercises of adding and subtracting polygonal surfaces of all kinds, he is still unable to solve the problem of the duplication of the cube. Numerous pages testify of the attempt to rise above planar geometry and reach the realm of the third dimension, but Leonardo always bumps against the limits of quantity calculation possibilities of his age.     

Poly(vinyl chloroformate) and its derivatives: 5. New poly(vinyl carbamates) and poly(vinyl thiocarbonates)

New poly(vinyl carbamates) and poly(vinyl thiocarbonates) have been prepared either by free radical polymerization of monomers or by chemical modification of poly(vinyl chloroformate) with appropriate amines and thiols using phase transfer catalysis. The structure of these polymers has been examined by i.r. and ¹³C n.m.r. spectroscopy and their thermal behaviour has been studied.     

Fatty acid profiles of 80 vegetable oils with regard to their nutritional potential

The current concern for fat intake in western countries has raised the question of the individual fatty acid (FA) impact on health. This important issue has strengthened the awareness of nutritionists and food manufacturers for the control of the FA profile of food products. The aim of this review is to provide a classification of the FA profiles of 80 vegetable oil sources, according to their nutritional potential. The first part of the review focuses on lipoprotein metabolism, and on the impact of each dietary FA on blood lipid composition (LDL‐cholesterol, HDL‐cholesterol and circulating triacylglycerols). In the second part of the review, the oil sources are clustered by similar FA profiles, and the classification is discussed with regard to the individual FA action on blood lipid composition. Apart from the major vegetable seeds, the clustering highlighted some interesting nutritional oil sources containing mainly α‐linolenic acid (camelina, linseed, perilla and stock oils), or interesting amounts of the two essential FA (purslane, chia, raspberry seed, sea buckthorn seed and salicorn oils). Furthermore, this classification provides a useful tool for the formulation of the FA profile of food products.     

Exploring IT Dependence and IT Governance

The purpose of this study is to identify the IT governance mechanisms that are used at different levels of IT dependence (defensive or offensive IT modes) and to compare the degree of their use between these IT modes. The results of a survey suggest that the degree of use of IT governance mechanisms varies by IT mode, and it is greater when a firm is in offensive versus defensive IT mode.     

Bagged Subspaces for Unsupervised Outlier Detection

In many domains, important events are not represented as the common scenario, but as deviations from the rule. The importance and impact associated with these particular, outnumbered, deviant, and sometimes even previously unseen events is directly related to the application domain (e.g., breast cancer detection, satellite image classification, etc.). The detection of these rare events or outliers has recently been gaining popularity as evidenced by the wide variety of algorithms currently available. These algorithms are based on different assumptions about what constitutes an outlier, a characteristic pointing toward their integration in an ensemble to improve their individual detection rate. However, there are two factors that limit the use of current ensemble outlier detection approaches: first, in most cases, outliers are not detectable in full dimensionality, but instead are located in specific subspaces of data; and second, despite the expected improvement on detection rate achieved using an ensemble of detectors, the computational efficiency of the ensemble will increase linearly as the number of components increases. In this article, we propose an ensemble approach that identifies outliers based on different subsets of features and subsamples of data, providing more robust results while improving the computational efficiency of similar ensemble outlier detection approaches.     

Impact of cross-section generation procedures on the simulation of the VVER-1000 pump startup experiment in the OECD/DOE/CEA V1000CT benchmark by coupled 3D thermal-hydraulics/neutron kinetics models

In the framework of joint effort between the Nuclear Energy Agency (NEA) of OECD, the United States Department of Energy (US DOE), and the Commissariat a l'Enerige Atomique (CEA), France a coupled three-dimensional (3D) thermal-hydraulics/neutron kinetics benchmark was defined. The overall objective of OECD/NEA V1000CT benchmark is to assess computer codes used in analysis of VVER-1000 reactivity transients where mixing phenomena (mass flow and temperature) in the reactor pressure vessel are complex. Original data from the Kozloduy-6 Nuclear Power Plant are available for the validation of computer codes: one experiment of pump start-up (V1000CT-1) and one experiment of steam generator isolation (V1000CT-2). Additional scenarios are defined for code-to-code comparison. As a 3D core model is necessary for a best-estimate computation of all the scenarios of the V1000CT benchmark, all participants were asked to develop their own core coupled 3D thermal-hydraulics/neutron kinetics models using the data available in the benchmark specifications and a common cross-section library. The first code-to-code comparisons based on the V1000CT-1 Exercise 2 specifications exhibited unacceptable discrepancies between two sets of results. The present paper focuses on the analysis of the observed discrepancies. The VVER-1000 3D neutron kinetics models are based on cross-section data homogenized on the assembly level. The cross-section library, provided as part of the benchmark specifications, thus consists in a set of parameterized two group cross sections representing the different assemblies and the reflectors. The origin of the observed large discrepancies was found mainly to lie in the methods used to solve the diffusion equation. The VVER reflector properties were also found to enhance discrepancies by increasing flux gradients at the core/reflector interface thus highlighting more the difficulties in some codes to handle high exponential flux gradients. This paper summarizes the different steps applied to analyze the neutronic codes and their predictions as well as the impact of cross-section generation procedures.