The Toffoli-Hadamard Gate System: an Algebraic Approach

Shi and Aharonov have shown that the Toffoli gate and the Hadamard gate give rise to an approximately universal set of quantum computational gates. The basic algebraic properties of this system have been studied in Dalla Chiara et al. (Foundations of Physics 39(6):559–572, 2009), where we have introduced the notion of Shi-Aharonov quantum computational structure. In this paper we propose an algebraic abstraction from the Hilbert-space quantum computational structures, by introducing the notion of Toffoli-Hadamard algebra. From an intuitive point of view, such abstract algebras represent a natural quantum generalization of both classical and fuzzy-like structures.     

Biomechanical and energetic determinants of technique selection in classical cross-country skiing

Classical cross-country skiing can be performed using three main techniques: diagonal stride (DS), double poling (DP), and double poling with kick (DK). Similar to other forms of human and animal gait, it is currently unclear whether technique selection occurs to minimize metabolic cost or to keep some mechanical factors below a given threshold. The aim of this study was to find the determinants of technique selection. Ten male athletes roller skied on a treadmill at different slopes (from 0° to 7° at 10 km/h) and speeds (from 6 to 18 km/h at 2°). The technique preferred by skiers was gathered for every proposed condition. Biomechanical parameters and metabolic cost were then measured for each condition and technique. Skiers preferred DP for skiing on the flat and they transitioned to DK and then to DS with increasing slope steepness, when increasing speed all skiers preferred DP. Data suggested that selections mainly occur to remain below a threshold of poling force. Second, critically low values of leg thrust time may limit the use of leg-based techniques at high speeds. A small role has been identified for the metabolic cost of locomotion, which determined the selection of DP for flat skiing.     

Intergroup Distinctiveness and Discriminatory Immigration Attitudes: The Role of National Identification

We examined the moderating role of national identification in understanding when a focus on intergroup similarity versus difference on ingroup stereotypical traits—manipulated with scale anchors—leads to support for discriminatory immigration policies. In line with intergroup distinctiveness research, national identification moderated the similarity–difference manipulation effect. Low national identifiers supported discriminatory immigration policies more when intergroup difference rather than similarity was made salient, whereas the opposite pattern was found for high national identifiers: They trended toward being more discriminatory when similarity was made salient. The impact of assimilation expectations and national identity content on the findings is discussed.     

Working Memory Capacity and the Development of Quantitative Central Conceptual Structures

Abstract

This article reconsiders Case’s theory of central conceptual structures (CCS), examining the relation between working memory and the acquisition of quantitative CCS. The lead hypothesis is that the development of working memory capacity shapes the development of quantitative concepts (whole and rational numbers). Study I, with 779 children from preschool to grade 5, validated a measure of the whole number CCS and found that children’s understanding of whole number advances by one developmental level per additional unit of working memory capacity. Study II, with 92 sixth- and seventh-graders, found that a test of the rational number CCS was predicted by working memory capacity and, to a lesser extent, by intrusion errors in the listening span. We also identified 2 subsets of items that demand a capacity of 4 or 5 units, respectively. Overall, the results support Case’s CCS theory and clarify the role of working memory in the acquisition of numerical concepts. The relevance of these results in relation to the current debate is discussed, with extensive connections to other current theories of whole or rational number comprehension.     

Poor Readers but Compelled to Read: Stroop Effects in Developmental Dyslexia

We studied a group of 24 children with dyslexia in second to fifth primary school grades by using a discrete-trial computerized version of the Stroop Color-Word Test. Since the classic Stroop effect depends on the interference of reading with color naming, one would expect these children to show no interference or, at least, less interference than normal readers. Children with dyslexia showed, however, a Stroop effect larger than normal readers of the same age. This suggests that reading, although difficult and slow, is an inescapable step that precedes naming both in poor and in normal readers.     

Reading and Spelling Disabilities in Children with and Without a History of Early Language Delay: A Neuropsychological and Linguistic Study

Language delay is a frequent antecedent of literacy problems, and both may be linked to phonological impairment. Studies on developmental dyslexia have led to contradictory results due to the heterogeneity of the pathological samples. The present study investigated whether Italian children with dyslexia showed selective phonological processing deficits or more widespread linguistic impairment and whether these deficits were associated with previous language delay. We chose 46 children with specific reading deficits and divided them into two groups based on whether they had language delay (LD) or not (NoLD). LD and NoLD children showed similar, severe deficits in reading and spelling decoding, but only LD children showed a moderate impairment in reading comprehension. LD children were more impaired in phonological working memory and phonological fluency, as well as in semantic fluency, grammatical comprehension, and verbal IQ. These findings indicate the presence of a moderate but widespread linguistic deficit (not limited to phonological processing) in a subset of dyslexic children with previous language delay that does not generalize to all children with reading difficulties.     

Working Memory Failures in Children with Arithmetical Difficulties

A large body of literature has examined the relationship between working memory and arithmetic achievement, but results are still ambiguous. To examine this relationship, we compared the performance of third and fifth graders with arithmetic difficulties (AD) and controls of the same age, grade, and verbal intelligence on a battery of working memory tasks, differentiating between different aspects of working memory. Children with AD scored significantly lower on active working memory tasks requiring manipulation of the to-be-recalled information (Listening Completion task, Corsi Span Backwards, Digit Backwards), but not in passive working memory tasks, requiring the recall of information in the same format in which it had been presented (Digit, Word, and Corsi Forwards Span tasks), nor in tasks involving word processing (word articulation rate, forwards and backwards word spans). A regression analysis showed that the best predictors of differences between AD children and the control group were the Corsi Span Backwards, the Listening Completion task, and the rate of articulation of pseudowords. The analysis of strategies used by children in mental calculation revealed the greater tendency of children with AD to rely on more primitive strategies: finger use never appeared as the most frequent strategy in skilled children, whereas it was the most used strategy in children with AD. Verbal and visual strategies appeared associated with successful performance in third graders, but in fifth grade, the most successful strategy was verbalization.     

Sample size, confidence, and contingency judgement.

According to statistical models, the acquisition function of contingency judgement is due to confidence increasing with sample size. According to associative models, the function reflects the accumulation of associative strength on which the judgement is based. Which view is right? Thirty university students assessed the relation between a fictitious medication and a symptom of skin discoloration in conditions that varied sample size (4, 6, 8 or 40 trials) and contingency (delta P = .20, .40, .60 or .80). Confidence was also collected. Contingency judgement was lower for smaller samples, while confidence level correlated inversely with sample size. This dissociation between contingency judgement and confidence contradicts the statistical perspective.