An Examination of Lexical and Sublexical Reading Skills in Children with Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF1) is an inherited neurocutaneous disorder associated with a high frequency of cognitive and learning difficulties. Based on discrepancies between IQ and academic achievement, approximately 17% of children with NF1 have been classified as having reading impairments. In this study, the lexical and sublexical reading skills of children with NF1 (n = 30) were examined using the Castles' Word/Non-Word Test (modified version), together with measures of neuropsychological functioning and academic achievement. Twenty children (67%) demonstrated deficits in one or more reading subskills, with 75% of these meeting criteria for phonological dyslexia and 20% classified with mixed dyslexia. These findings indicate that a large proportion of children with NF1 may be characterized by a specific difficulty with the sublexical procedure, suggesting a difficulty employing spelling-to-sound rules to assemble a pronunciation when reading. In line with previous studies, the present findings also suggest that discrepancy-based methods may not be sufficiently sensitive to identify children who experience reading difficulties.     

Deficit in Response Inhibition in Children with Attention Deficit/Hyperactivity Disorder (ADHD): Impact of Motivation?

To date, neuropsychological and psycho-physiological studies have revealed inconsistent results regarding an executive or motivational deficit explaining the response inhibition deficit in children with attention deficit/hyperactivity disorder (ADHD). Research on differentiating neuropsychological processes in ADHD subtypes is still scarce. Therefore, the motivational impact on response inhibition among boys with ADHD was examined in this study. In the first study, 19 boys with ADHD-combined type (ADHD-C) and 19 age-matched healthy control subjects performed a modified Go/No-Go task with the following experimental conditions: neutral, auditory feedback, reward, response cost, and reward/response cost. Performance and physiological data (heart rate and skin conductance responses) were recorded. In a second study with the modified Go/No-Go task, data for six children with ADHD-C, six with ADHD-inattentive subtype (ADHD-I), and six healthy control subjects were compared. Neither of the two studies revealed group by condition interactions. In study 1, boys with ADHD-C generally made more commissions and omissions compared to the control group. However, feedback significantly improved the response inhibition in all children. The heart rate of all children was increased in the two conditions of reward and reward/response cost. Study 2 revealed that children with ADHD-I responded more slowly and showed increased reaction time variability compared to both other groups. The present study supports an executive rather than a motivational deficit in the response inhibition among children with ADHD-C, though further results also indicate the role of auditory feedback on response inhibition. Additionally, the findings support the differentiation of ADHD-C and ADHD-I, suggesting that ADHD-I children are characterized by a sluggish cognitive tempo.     

Processing Speed Weakness in Children and Adolescents with Non-Hyperactive but Inattentive ADHD (ADD)

DSM-IV-TR defines ADHD-Predominantly Inattentive as allowing up to five symptoms of hyperactivity/impulsivity, while theories of the inattentive type usually assume a group that is hypoactive and characterized by processing speed and cognitive interference deficits. In a community-recruited sample of 572 children and adolescents, a pure inattentive subtype of ADHD (ADD) was defined as those who met DSM-IV-TR criteria for ADHD-PI but had two or fewer hyperactive/impulsive symptoms. Processing and output speeds of those with ADD were compared to those identified with DSM-IV-TR ADHD combined type and non-ADHD controls. These results were then contrasted with those found when DSM-IV-TR defined ADHD-PI was compared with ADHD-C and controls. Processing and output speed were assessed with the Trailmaking A and B and the Stroop Naming Tests. Cognitive interference control was assessed with the interference score from the Stroop Task. Slower cognitive interference speed was found in the ADD vs. ADHD-C and controls comparisons, but not the ADHD-PI versus ADHD-C and controls comparisons. On output speed measures, ADD exhibited the slowest performance, significantly different from controls and the effect size for the set-shifting speed contrast (Trailmaking B) was double that of the ADHD-PI vs. control comparison. ADHD-Inattentive type as defined by the DSM-IV-TR is a heterogeneous condition with a meaningful proportion of those affected exhibiting virtually no hyperactive/impulsive symptoms. This subgroup may represent a distinct inattentive condition characterized by poor cognitive interference control and slow processing or output speed.     

Inattention,working memory,and academic achievement in adolescents referred for attention deficit/hyperactivity disorder (ADHD)

This study investigated the role of inattention and working memory in predicting academic achievement in 145 adolescents aged 13 to 18 referred for attention deficit/hyperactivity disorder (ADHD). Path analysis was used to examine whether auditory-verbal and visual-spatial working memory would mediate the relationships between classroom inattention symptoms and achievement outcomes. Results provide support for the mediational model. Behavioral inattention significantly predicted both auditory-verbal and visual-spatial working memory performance. Auditory-verbal working memory was strongly associated with adolescents' achievement in reading and mathematics, while visual-spatial working memory was only associated with achievement in mathematics. The path from inattention symptoms to reading was partially mediated by the working memory variables, but the path from inattention to mathematics was not mediated by working memory. The proposed model demonstrated a good fit to the data and explained a substantial amount of variance in the adolescents' achievement outcomes. These findings imply that working memory is a risk factor for academic failure for adolescents with attentional problems.     

Assessment of children's receptive vocabulary using event-related brain potentials: Development of a clinically valid test

The combined verbal and motor impairments characteristic of children with disorders such as Cerebral Palsy (CP) frequently compromise the accuracy of standard psychometric assessments. What is needed is a test to measure language that does not require verbal or motor responses. This study was designed to determine whether single-word receptive vocabulary could be assessed in young children without CP, using an ERP-compatible test based on Form M of the Peabody Picture Vocabulary Test-Revised (PPVT-R). Fifteen 10-year-old children with normal levels of psychometric intelligence participated. Ninety pictures were selected from the PPVT-R (Form M), representing three levels of single-word receptive vocabulary (Preschool, Child-Adolescent, Adult). Each picture was presented twice (pseudo-random), once paired with a spoken word that was semantically congruent with the picture and once paired with a semantically incongruent word. The children's N400 was significantly larger to incongruent than to congruent pairs, but only when the vocabulary was within their repertoire. The results are discussed in terms of electrophysiologic correlates of acquired language and the clinical use of this ERP test as an adjunct to assessing patients with moderate to severe communication and/or motor impairments (e.g., cerebral palsy, autism, head injury).     

The influence of interfaces on the formation of bubbles in He-ion-irradiated Cu/Mo nanolayers

The role of immiscible Cu/Mo interfaces on the formation of helium (He) bubbles in ion-irradiated Cu/Mo 5?nm multilayers is examined. Interfaces significantly enhance the critical He concentration above which bubbles, approximately 1?nm in diameter, are detected via through-focus imaging in a transmission electron microscope. He-to-vacancy ratio affects the formation and distribution of He bubbles. The diameter of He bubbles in Cu appears to be slightly larger than that in Mo.     

On the possibility of tuning the energy separation between space-quantized levels in a quantum well

The idea about change of energy distances between space-quantized energy levels by ionization of an impurity delta layer situated within a quantum well (QW) is put forward and justified. The self-consistent solutions of Schrödinger, Poisson, and electroneutrality equations made for n-type SiGe/Si/SiGe rectangular QW show that the effect really exists and the most dramatic changes can be observed for an edge-delta-doped QW structure.     

Effect of couple stress at the interfaces of a nano-hole on the anti-plane electro-mechanical behavior

In piezoelectric nanocomposites, surface/interface plays an important role in determining the size-dependent behavior of media. Within the framework of couple stress, the effect of surface/interface around a nano-hole on the anti-plane electro-mechanical behavior is examined. By introducing a surface/interface model, the stress and electric displacement effects on the size-dependent behavior are both considered. The governing equations in piezoelectric materials are decoupled into the classical ones. The displacement and electric potential are expressed by Bessel functions. By satisfying the boundary conditions around the hole with the interface/surface effect, the expanded coefficients are obtained. Through analysis, it is shown that the mechanical and electrical fields drastically depend on the relative size of the hole with respect to the characteristic length of the material. The effects of couple stresses on the stress and electric field are also addressed. Comparison with the existing results is also given.     

Effect of a nanoporous surface on photoluminescence from nanopatterned GaN thin films fabricated by anodic alumina templates

GaN photonic crystal slabs on InGaN/GaN multi-quantum well light-emitting diodes have been formed by dry etching using nanoporous anodic alumina templates, which have a periodic lattice constant of 105 nm and a hole diameter of 45 nm. The photonic crystal slab shows an enhanced intensity of photoluminescence due to the nanohole pattern array producing Fabry–Perot like interference. A rough surface of nanoholes results in a broad spectrum with a small oscillation, and well-ordered multiple facets of nanoholes results in a relatively sharp spectrum with a large oscillation.     

Islam,HIV/AIDS and activism: a critical analysis of some themes in Positive Muslims' ‘theology of compassion’

The present article is a critical analysis of the South African organization Positive Muslims' ‘theology of compassion’, put forward by its proponents as a Muslim religious initiative to combat the spread of HIV/AIDS and the stigmatization of those affected by the disease. The article addresses the hermeneutics applied and the results reached in relation to a wider contemporary Muslim religious discourse on HIV/AIDS. It also connects the ‘theology of compassion’ to a broader transnational movement of progressive Islam, of which the ‘theology of compassion’ is a practical, grass-roots application. The main analytical focus, however, is on the way in which certain features in this theology are shaped by basic assumptions on the part of its producers concerning the beliefs, emotions and background knowledge of its main stated consumers: believing Muslims.