Search results for " Match"
showing 5 items of 345 documents
Improved camouflage through ontogenetic colour change confers reduced detection risk in shore crabs
2019
Abstract Animals from many taxa, from snakes and crabs to caterpillars and lobsters, change appearance with age, but the reasons why this occurs are rarely tested.We show the importance that ontogenetic changes in coloration have on the camouflage of the green shore crabs (Carcinus maenas), known for their remarkable phenotypic variation and plasticity in colour and pattern.In controlled conditions, we reared juvenile crabs of two shades, pale or dark, on two background types simulating different habitats for 10 weeks.In contrast to expectations for reversible colour change, crabs did not tune their background match to specific microhabitats, but instead, and regardless of treatment, all de…
The Eurasian Treecreeper (Certhia familiaris) has an effective camouflage against mammalian but not avian vision in boreal forests
2022
A well-known example of visual camouflage in birds is the plumage coloration of the Eurasian Treecreeper Certhia familiaris, yet this species’ camouflage has never been objectively quantified. Here, we quantify treecreeper camouflage in its boreal forest habitat, test whether treecreepers better match tree backgrounds at nest site, territory or habitat spatial scales, and explore which common tree species provide the best background match. Using photographic data of the birds and forested backgrounds, we test their background match using human, ferret and avian vision modelling. We found that a treecreeper’s wing and mantle provided closest background matching, whereas the wing stripe and t…
Influence of the learning environment on the representational strategies of middle school music students: an intervention-based study
2015
The purpose of this study was to examine the effects of a hypermedia learning environment on middle school students' meta-representational competence (MRC) in the domain of music. Particularly, we aimed at determining whether an educational intervention influenced the accuracy with which middle school students matched sounds (sonic fragments) to symbols (graphic representations). The students were randomly allocated to the experimental condition. An intervention was set up so that the experimental group students (E) were provided with scaffolding aimed at enhancing their use of constructive resources to generate representations and their critical capabilities to judge them. On the other han…
International Assessment Surveys of Educational Achievement in Developing Countries : Why Education Economists Should Care
2015
International audience; This paper reviews the most known international assessment studies that are conducted in the context of poor countries and highlights the lack of empirical evidence on the degree to which the contents of the tests really match countries' curricula. To illustrate, the paper evaluates the sensitivity of an international testing instrument by comparing the responses of students in two consecutive grades on the same battery of tests. Using propensity score matching to control for student and teacher characteristics, the results show that the tests are not grade sensitive, which raises the question of the validity of many empirical works that are based on similar instrume…
Webcam based display calibration
2012
International audience; We present an automatic method for measuring the tone response curve of display devices based on visual methods, where the eye is replaced by an end-user, uncalibrated camera, such as a webcam. Our approach compares a series of halftoned patches of known covering ratio with a continuous series of tone patches for each ratio. Both patches are shot by a camera that is used as a virtual eye to evaluate the luminance difference. By an iterative process, the continuous tone value is adjusted while compared with the perceived level of the halftoned patch. When the camera does not see any difference between the patches or a minimal difference, the luminance level of the con…