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Efthymia Paparistodemou Richard Noss Dave Pratt 《International Journal of Computers for Mathematical Learning》2008,13(2):89-110
This article describes how children use an expressive microworld to articulate ideas about how to make a game seem fair with
the use of randomness. Our aim in this study is to disentangle different flavours of fairness and to find out how children
used each flavour to make sense of potentially complex behaviour. In order to achieve this, a spatial computer game was designed
to enable children to examine the consequences of their attempts to make the game fair. The study investigates how 23 children,
aged between 5.5 and 8 years, engaged in constructing a crucial part of a mechanism for a fair spatial lottery machine (microworld).
In particular, the children tried to construct a fair game given a situation in which the key elements happened randomly.
The children could select objects, determine their properties, and arrange their spatial layout in the machine. The study
is based on task-based interviewing of children who were interacting with the computer game. The study shows that children
have various cognitive resources for constructing a random fair environment. The spatial arrangement, the visualisation and
the manipulations in the lottery machine allow us gain a view into the children’s thinking of the two central concepts, fairness
and randomness. The paper reports on two main strategies by which the children attempted to achieve a balance in the lottery
machine. One involves arranging the balls symmetrically and the other randomly. We characterize the nature of the thinking
in these two strategies: the first we see as deterministic and the latter as stochastic, exploiting the random collisions
of the ball. In this article we trace how the children’s thinking moved between these two perspectives.
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Dave PrattEmail: |
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Efthymia Ramou Guilherme Rebordo Susana I. C. J. Palma Ana C. A. Roque 《Molecules (Basel, Switzerland)》2021,26(19)
Liquid crystals represent a fascinating intermediate state of matter, with dynamic yet organized molecular features and untapped opportunities in sensing. Several works report the use of liquid crystal droplets formed by microfluidics and stabilized by surfactants such as sodium dodecyl sulfate (SDS). In this work, we explore, for the first time, the potential of surface-active ionic liquids of the imidazolium family as surfactants to generate in high yield, stable and oriented liquid crystal droplets. Our results show that [C12MIM][Cl], in particular, yields stable, uniform and monodisperse droplets (diameter 74 ± 6 µm; PDI = 8%) with the liquid crystal in a radial configuration, even when compared with the standard SDS surfactant. These findings reveal an additional application for ionic liquids in the field of soft matter. 相似文献
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Normal correlation coefficient of non-normal variables using piece-wise linear approximation 总被引:1,自引:0,他引:1
The correlation coefficient of non-normal variables is expressed as a function of the correlation coefficient of normal variables
using piece-wise linear approximation of each univariate transform of normal to anything, and the second order moments of
a multiply truncated bivariate normal distribution. For the inverse problem, an algorithm iterates this analytic function
in order to assign a normal correlation coefficient to two non-normal variables. The algorithm is applied for the generation
of randomized bivariate samples with given correlation coefficient and marginal distributions and used in a randomization
test for bivariate nonlinearity. The test correctly does not reject the null hypothesis of linear correlation if the nonlinearity
is plausible and due to the sample transform alone. 相似文献
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Mayya Sundukova Efthymia Prifti Annalisa Bucci Kseniia Kirillova Joana Serrao Luc Reymond Miwa Umebayashi Ruud Hovius Howard Riezman Kai Johnsson Paul A. Heppenstall 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(8):2363-2366
Optical monitoring of neuronal voltage using fluorescent indicators is a powerful approach for the interrogation of the cellular and molecular logic of the nervous system. Herein, a semisynthetic tethered voltage indicator (STeVI1) based upon nile red is described that displays voltage sensitivity when genetically targeted to neuronal membranes. This environmentally sensitive probe allows for wash‐free imaging and faithfully detects supra‐ and sub‐threshold activity in neurons. 相似文献
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Papakonstantinou O Foufa K Benekos O Alexopoulou E Mademli M Balanika A Economopoulos N Kelekis NL 《Magnetic resonance imaging》2012,30(7):926-933
Purpose
To assess the performance and results of R2 relaxometry using a fat-suppressed (FS) multiecho sequence and compare these to conventional R2 relaxometry in estimating tissue iron overload.Materials and Methods
Relaxation rate values (R2=1/T2) of the liver, spleen, pancreas and vertebral bone marrow (VBM) were estimated in 21 patients with β-thalassemia major, using a respiratory-triggered 16-echo Carr-Purcell-Meiboom-Gill (CPMG) spin-echo sequence before (R2) and after (R2 FS) the application of chemically selective fat suppression.Results
Hepatic and splenic R2 FS values correlated with respective R2 values (r=0.98 and r=0.96, P<.001), whereas correlations between R2 FS and R2 values for pancreas and VBM were not statistically significant. Bland–Altman plots show disagreement between R2 and R2 FS values, particularly for pancreas and VBM. Hepatic, pancreatic and VBM R2 FS values correlated with serum ferritin (r=0.88, P<.001; r=0.51, P<.003; and r=0.75, P<.002, respectively). Hepatic R2 FS values correlated with splenic R2 FS (r=0.77, P<.03), pancreatic R2 FS (r=0.61, P<.006) and VBM R2 FS values (r=0.70, P<.001), whereas pancreatic R2 FS values correlated also with VMB R2 FS values. On the contrary, among the R2 values of the above tissues, obtained without fat suppression, only hepatic R2 values correlated with serum ferritin, whereas no correlation was documented between hepatic and pancreatic or VBM R2 values. The application of fat suppression did not improve breathing or flow artifacts.Conclusion
Application of fat suppression in the standard CPMG sequence improved the capability of MRI in noninvasive quantification of iron, particularly in lipid-rich tissues, such as vertebral bone marrow (VBM) and pancreas. 相似文献8.
We reconsider the problem of the convergence of Birkhoff's normal form for a system of perturbed harmonic oscillators, under the condition that the system is essentially isochronous. In contrast with previous proofs based on the so called quadratically convergent method, the present proof uses only classical expansions in a parameter. This allows us to bring into light some mechanisms of accumulation of small divisors, which can be useful in more complicated and interesting cases. These same mechanisms allow us to prove the theorem with the Bruno condition on the frequencies in a very natural way. 相似文献
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Efthymia G. Gioti Theocharis V. Koftis Efstratios Neokosmidis Elli Vastardi Stefanos S. Kotoulas Sakellarios Trakossas Theodoros Tsatsas Elizabeth E. Anagnostaki Theodoros D. Panagiotidis Constantinos Zacharis Evanthia P. Tolika Anastasia-Aikaterini Varvogli Thanos Andreou John K. Gallos 《Tetrahedron》2018,74(4):519-527
A new synthesis of entecavir from d-glucose in an average total yield of 3.5% was achieved via an intramolecular nitrile oxide cycloaddition (INOC) reaction and a Peterson olefination as key-steps. The present process was designed for industrial application, using widely available raw materials, simple and cheap reagents and avoiding low reaction temperatures, which are very common in the synthetic approaches towards similarly complex structures. 相似文献
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Efthymia Symitsi Panagiotis Stamolampros George Daskalakis Nikolaos Korfiatis 《European Journal of Operational Research》2021,288(2):605-619
This paper investigates the informational value of online reviews posted by employees for their employer, a rather untapped source of online information from employees, using a sample of 349,550 reviews from 40,915 UK firms. We explore this novel form of electronic Word-of-Mouth (e-WOM) from different perspectives, namely: (i) its information content as a tool to identify the drivers of job satisfaction/dissatisfaction, (ii) its predictive ability on firm financial performance and (iii) its operational and managerial value. Our approach considers both the rating score as well as the review text through a probabilistic topic modeling method, providing also a roadmap to quantify and exploit employee big data analytics. The novelty of this study lies in the coupling of structured and unstructured data for deriving managerial insights through a battery of econometric, financial and operational research methodologies. Our empirical analyses reveal that employee online reviews have informational value and incremental predictability gains for a firm's internal and external stakeholders. The results indicate that when models integrate structured and unstructured big data there are leveraged opportunities for firms and managers to enhance the informativeness of decision support systems and in turn, gain competitive advantage. 相似文献
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