Age, individuality, and context as factors in sustained visual attention during the preschool years

In 3 studies, the authors explored age changes and individual differences in preschool children's sustained attention in several different contexts--watching a videotape, playing with toys, and performing reaction time tasks. Various indexes of attention increased from 30 months to 54 months, whereas inattention decreased. Changes tended to occur earlier for play and television viewing than for the reaction time task. Together, the results also provide evidence for individual differences in measures of attention and inattention through high internal consistency and stability over time within situations. Correlations across situations, however, were low to modest. These results suggest that children have stable tendencies to focus and sustain attention in particular contexts but that their attention varies with the demands of the task and their ability or interest in meeting those demands.     

The differentiation of activity in infants' exploration of objects.

If an activity during manipulative play is exploratory, it should, in contrast to other activity, be used differentially for objects that vary in novelty. In a study of 5-mo-olds, different definitions of exploratory mouthing were tested, and results suggest that mouthing followed immediately by a look fulfilled some criteria for an exploratory activity. In the next study of 5- to 11-mo-olds, mouthing with looks after and examining, a measure of visual–manipulative inspection, met the criteria for exploratory activity; other kinds of mouthing and visual–manipulatory activity did not. Exploratory mouthing decreased with age, and examining increased. The exploratory function of mouthing apparently was not due to concurrent manual activity providing haptic information. The conclusion is that some activities are exploratory and information-gathering and other activities are nonexploratory and serve other functions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A new Rett syndrome family consistent with X-linked inheritance expands the X chromosome exclusion map

Although familial recurrences of Rett syndrome (RTT) comprise only approximately 1% of the reported cases, it is these cases that hold the key for the understanding of the genetic basis of the disorder. Families in which RTT occurs in mother and daughter, aunt and niece, and half sisters are consistent with dominant inheritance and variable expressivity of the phenotype. Recurrence of RTT in sisters is likely due to germ-line mosaicism in one of the parents, rather than to recessive inheritance. The exclusive occurrence of classic RTT in females led to the hypothesis that it is X-linked and may be lethal in males. In an X-linked dominant disorder, unaffected obligate-carrier females would be expected to show nonrandom or skewed inactivation of the X chromosome bearing the mutant allele. We investigated the X chromosome inactivation (XCI) patterns in the female members of a newly identified family with recurrence of RTT in a maternal aunt and a niece. Skewing of XCI is present in the obligate carrier in this family, supporting the hypothesis that RTT is an X-linked disorder. However, evaluation of the XCI pattern in the mother of affected half sisters shows random XCI, suggesting germ-line mosaicism as the cause of repeated transmission in this family. To determine which regions of the X chromosome were inherited concordantly/discordantly by the probands, we genotyped the individuals in the aunt-niece family and two previously reported pairs of half sisters. These combined exclusion-mapping data allow us to exclude the RTT locus from the interval between DXS1053 in Xp22.2 and DXS1222 in Xq22.3. This represents an extension of the previous exclusion map.     

Desiccant wheel regenerated by thermal energy from a microcogenerator: Experimental assessment of the performances

Hybrid desiccant HVAC systems have shown several advantages, compared to conventional cooling and dehumidification systems. Therefore, their use is also spreading for tertiary and residential buildings, especially when the regeneration of the desiccant can be obtained by using available waste heat.     

An approach for restoring the coherence between the scanning surfaces in phaseless near-field antenna characterization

We propose an approach for restoring the coherence between the scanning surfaces in phaseless near-field antenna characterization. The approach consists of accounting for the misalignments of the second scanning surface with respect to the first one directly within the radiation operator, restoring the coherence within the phaseless characterization algorithm. The restore of the coherence is demanded to a global optimization stage, performed by an efficient and effective Multilevel, Single-Linkage (MLSL) routine. The proposed method does not require any human intervention, nor it does need any additional hardware instrumentation. Numerical and experimental results show the potentialities of the technique.     

TiO2‐Oligoaldaramide nanocomposites as efficient core‐shell systems for wood preservation

Homogeneous core‐shell systems were obtained with a growth, in controlled steps, of several oligoamides on TiO₂ nanoparticles. Derivatives of natural compounds, such as l ‐tartaric acid and α,α′‐trehalose, were used as diesters in the polycondensation reactions with ethylenediamine. TiO₂ anatase was chosen because of its high photo‐activity and its antimicrobial activity. The TiO₂ nanoparticles had been previously activated then functionalized using two different coupling agents, and finally, the TiO₂‐oligoamide nanocomposites were synthesized using two synthetic pathways. The final products were characterized by ¹H NMR, ¹³C NMR, FT‐IR, and transmission electron microscope. These nanocomposites can show improved properties in comparison with the single components (TiO₂ nanoparticles or oligoamides), which are useful in many fields, such as antimicrobial coatings for surfaces in cultural heritage conservation. A nanocomposite (TiO₂‐polyethylenetartaramide) was used for applicative studies, and it has shown a good efficacy against fungal attack by Trametes versicolor on wood specimens (Fagus sylvatica). © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42047.     

Power pattern synthesis of reconfigurable conformal arrays with near-field constraints

A conformal array power pattern synthesis technique is presented which makes it possible to take into account near-field constraints and to reconfigure the radiated pattern by controlling only the phases of the excitation coefficients. Far-field pattern specifications are given by masks while near-field constraints are given by prescribing the maximum allowable field intensity at points arbitrarily located in a given near-field region. The amplitude of the excitations, common to all radiated beams, and the phases corresponding to each one are obtained as a result of the synthesis algorithm.     

Development of attention and distractibility in the first 4 years of life.

This observational study describes the early development of attention and distractibility. Under several conditions of distraction, 172 children at 10, 26, and 42 months of age played with toys. Attention to the toys was coded as casual, settled, or focused. All 3 levels of attention changed with age, with casual attention decreasing and focused attention increasing. The 10-month-olds were more distractible than the other children, even during focused attention. The infants were most distracted by the auditory-visual distractor, whereas the oldest children were most distracted by the visual distractor. Some 42-month-olds showed evidence of being more focused in the presence of distractors. Overall, the results point to a developmental transition in the processes underlying attention during play. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Phaseless characterisation of compact antenna test ranges

Antenna characterisation and radar cross section measurements can be conveniently and successfully carried out by means of a compact antenna test range (CATR), whose performance is primarily assessed in terms of quiet zone size and field uniformity. CATR characterisation and diagnostics are usually performed by means of (amplitude and phase) field measurements in the quiet zone and are of timely interest either on CATR installation or on its periodic reassessments performed by manufacturers and/or users. This paper addresses CATR characterisation from amplitude-only data, an attractive topic because of the application of CATRs to the millimetre or sub-millimetre wave ranges. The approach is based on an appropriate strategy retrieving the missing quiet zone phase and facing the issue of the large electrical dimensions of the CATR. To take into account the characteristics of the collimating system as well as to keep as low as possible the number of unknowns to be sought for, it exploits the Jacobi-Bessel expansion of the aperture field. The performance of the algorithm has been tested through a wide numerical analysis against synthetic data generated by GRASP8-SE whose full version is routinely employed for CATR design. The main results related to a Gregorian dual offset reflector CATR, modelled on that proposed in the literature by Pistorius et ah, and to a single offset reflector CATR, inspired by the one available at the Queen Mary & Westfield College, London (UK), are reported.     

Nano/micro ternary composites based on PP,nanoclay, and CaCO3

Nano‐/microcomposites based on polypropylene/montmorillonite/calcium carbonate were prepared by melt mixing. Their structures and properties were characterized by small‐angle X‐ray diffraction, thermal analysis, and rheological measurements. The intercalation degree was found to be dependent on the compatibilizer content and the processing temperature. The addition of the organoclay slightly increased the melt crystallization temperature of polypropylene, acting as nucleating agents, and improved the degree of crystallinity. The rheological tests showed that nanocomposites increased the complex viscosity when compared with the microcomposites with the same filler content and exhibited a pronounced shear‐thinning behavior in the low frequency range. A Carreau‐Yasuda model was used to model the rheological behavior of these materials. The nano‐/microcomposites showed a significant improvement (about 50%) of the Young's modulus when compared with microcomposites with the same filler content due to the intercalation or exfoliation of the organoclay and the enhanced degree of crystallinity. Moreover, some formulations showed an enhancement of elongation at break and ultimate strength. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009