Length Effect at Testing Splitting Tensile Strength of Concrete

Tensile strength of concrete is the basic property when estimating the cracking resistance of the structure and when analysing fracture processes in concrete. The most common way of testing tensile strength is the Brazilian method. It has been noticed that the shape and size of specimens influence the tensile splitting strength. The experiments were performed to investigate the impact of cylinder’s length on tensile concrete strength received in the Brazilian method. During the experiment the tensile concrete strength was tested on two different sizes cylindrical specimens: 150 mm × 150 mm and 150 mm × 300 mm. Experiments were performed in two stages, with two types of maximum aggregate size: 16 mm and 22 mm. The software “Statistica” was used to perform the broad scale statistical analysis. When comparing test results for shorter and longer specimens, the increase of tensile splitting strength tested on shorter cylinders was observed (approximately 5%). However, when performing deeper statistical analysis, it has been found that the length effect was not sensitive to the strength of the cement matrix and the type of aggregate but was influenced by the aggregate size. Further experiments are needed in order to perform a multi-parameter statistical analysis of scale effect when testing the splitting tensile strength of concrete.

Can’t See the Words for the Letters: Whole Word Processing in Adolescents and a Novel “Visual” Intervention for Dyslexia

<p>Individuals with developmental dyslexia, considered as a group, perform poorly on tasks that involve phonological analysis, such as applying sight-sound rules to read new words, or analysing words into their component sounds (De Groot, Huettig, & Olivers, 2016; Temple & Marshall, 1983). However, dyslexia is also associated with other types of difficulties. For example, in some individuals, reading latencies increase disproportionately with the length of the word (De Luca, Barca, Burani, & Zoccolotti, 2008; Spinelli et al., 2005) suggesting they may have difficulties recognising familiar words as whole units (“whole word” processing). This thesis examined the relationship between the word length effect and overall reading proficiency in a diverse sample of 49 adolescents. We found that the length effect was a unique predictor of reading proficiency, even after factoring out variance in phonological skills (measured using a nonword reading task). We also tested the recent hypothesis that visual attention span - the number of letters a reader can capture in a single glance - is important for efficient whole word reading (Bosse, Tainturier, & Valdois, 2007). Contrary to this hypothesis, we found no association between the word length effect and scores on a standard measure of visual attention span (a partial report task). We also explored whether reading-delayed adolescents could benefit from an intervention targeting their specific cognitive profile. Five cases demonstrating a selective difficulty with either “phonological” or “whole word” skills completed two interventions. One targeted phonological skills: participants were trained to recognise and apply common sight-sound correspondences. The other targeted whole word skills: we reasoned that training participants to recognise commonly-occurring letter redundancies (e.g. ogue: rogue, synagogue, dialogue) could reduce the load on parallel letter processing. Only one of the five cases showed greater improvement in (untrained) word reading accuracy following their “target” intervention. However, four of the five showed intervention-specific improvements in reading latency. These results suggest that it could be valuable to consider heterogeneity when treating reading delay.</p>

Can’t See the Words for the Letters: Whole Word Processing in Adolescents and a Novel “Visual” Intervention for Dyslexia

<p>Individuals with developmental dyslexia, considered as a group, perform poorly on tasks that involve phonological analysis, such as applying sight-sound rules to read new words, or analysing words into their component sounds (De Groot, Huettig, & Olivers, 2016; Temple & Marshall, 1983). However, dyslexia is also associated with other types of difficulties. For example, in some individuals, reading latencies increase disproportionately with the length of the word (De Luca, Barca, Burani, & Zoccolotti, 2008; Spinelli et al., 2005) suggesting they may have difficulties recognising familiar words as whole units (“whole word” processing). This thesis examined the relationship between the word length effect and overall reading proficiency in a diverse sample of 49 adolescents. We found that the length effect was a unique predictor of reading proficiency, even after factoring out variance in phonological skills (measured using a nonword reading task). We also tested the recent hypothesis that visual attention span - the number of letters a reader can capture in a single glance - is important for efficient whole word reading (Bosse, Tainturier, & Valdois, 2007). Contrary to this hypothesis, we found no association between the word length effect and scores on a standard measure of visual attention span (a partial report task). We also explored whether reading-delayed adolescents could benefit from an intervention targeting their specific cognitive profile. Five cases demonstrating a selective difficulty with either “phonological” or “whole word” skills completed two interventions. One targeted phonological skills: participants were trained to recognise and apply common sight-sound correspondences. The other targeted whole word skills: we reasoned that training participants to recognise commonly-occurring letter redundancies (e.g. ogue: rogue, synagogue, dialogue) could reduce the load on parallel letter processing. Only one of the five cases showed greater improvement in (untrained) word reading accuracy following their “target” intervention. However, four of the five showed intervention-specific improvements in reading latency. These results suggest that it could be valuable to consider heterogeneity when treating reading delay.</p>

Numerical study of the flow around a circular cylinder with the slip length boundary effect at a critical Reynolds number

The paper presents an investigation of the slip length effect on the flow around a circular cylinder at Reynolds number Re = 2.5·105. The study was performed by means of numerical simulation of the flow with the URANS approach based on the k-ω SST model. Calculations show a significant effect of the slip length on the flow patterns. With an increase in the slip length, the drag coefficient noticeably decreases and the pulsations of the lift force reduce. With an increase in the slip length, the separation of the flow from the cylinder is delayed, which significantly affects the flow patterns in the wake behind the cylinder.

'Constituent length' effects in fMRI do not provide evidence for abstract syntactic processing

How are syntactically and semantically connected word sequences, or constituents, represented in the human language system? An influential fMRI study, Pallier et al. (2011, PNAS), manipulated the length of constituents in sequences of words or pseudowords. They reported that some language regions (in the anterior temporal cortex and near the temporo-parietal junction) were sensitive to constituent length only for sequences of real words but not pseudowords. In contrast, language regions in the inferior frontal and posterior temporal cortex showed the same pattern of increased response to longer constituents - and similar overall response magnitudes - for word and pseudoword sequences. Based on these results, Pallier et al. argued that the latter regions represent abstract sentence structure. Here we identify methodological and theoretical concerns with the Pallier et al. study and conduct a replication across two fMRI experiments. Our results do not support Pallier et al.'s critical claim of distinct neural specialization for abstract syntactic representations. Instead, we find that all language regions show a similar profile of sensitivity to both constituent length and lexicality (stronger responses to real-word than pseudoword stimuli). In addition, we argue that the constituent length effect in these experiments i) is not readily grounded in established theories of sentence processing, and ii) may not actually derive from syntactic structure building, but may instead reflect the temporal receptive window of the human language system.

Crack Length Effect on the Fracture Behavior of Single-Crystals and Bi-Crystals of Aluminum

Molecular dynamics simulations of cracked nanocrystals of aluminum were performed in order to investigate the crack length and grain boundary effects. Atomistic models of single-crystals and bi-crystals were built considering 11 different crack lengths. Novel approaches based on fracture mechanics concepts were proposed to predict the crack length effect on single-crystals and bi-crystals. The results showed that the effect of the grain boundary on the fracture resistance was beneficial increasing the fracture toughness almost four times for bi-crystals.