Hypoxic adaptation during development: relation to pattern of neurological presentation and cognitive disability

Children with acute hypoxic-ischaemic events (e.g. stroke) and chronic neurological conditions associated with hypoxia frequently present to paediatric neurologists. Failure to adapt to hypoxia may be a common pathophysiological pathway linking a number of other conditions of childhood with cognitive deficit. There is evidence that congenital cardiac disease, asthma and sleep disordered breathing, for example, are associated with cognitive deficit, but little is known about the mechanism and whether there is any structural change. This review describes what is known about how the brain reacts and adapts to hypoxia, focusing on epilepsy and sickle cell disease (SCD). We prospectively recorded overnight oxyhaemoglobin saturation (SpO2) in 18 children with intractable epilepsy, six of whom were currently or recently in minor status (MS). Children with MS were more likely to have an abnormal sleep study defined as either mean baseline SpO2 <94% or >4 dips of >4% in SpO2/hour (p = .04). In our series of prospectively followed patients with SCD who subsequently developed acute neurological symptoms and signs, mean overnight SpO2 was lower in those with cerebrovascular disease on magnetic resonance angiography (Mann-Whitney, p = .01). Acute, intermittent and chronic hypoxia may have detrimental effects on the brain, the clinical manifestations perhaps depending on rapidity of presentation and prior exposure.     

Thermal stability of nanocrystalline fcc and hcp Ni(Si) synthesized by mechanical alloying of Ni90Si10

The thermal stability of nanocrystalline fcc and hcp Ni(Si), obtained by mechanical alloying of Ni₉₀Si₁₀, has been studied. The allotropic transformation from fcc to hcp Ni(Si) is accompanied by a volume expansion of 8.6% and is observed when fcc Ni(Si) reaches a critical crystallite size of 10nm. The hcp phase transforms to stable fcc Ni(Si) at 573K. It has been identified that the lattice distortion in nanometre-sized crystallites from the equilibrium configuration and the decrease in the interfacial energy with grain refinement act as self obstacles in controlling the grain growth of nanocrystalline materials.     

Shortening the Home Environment Inventory: A Polytomous Item Response Theory approach

Assessing an Indian home presents a great challenge to researchers because of its’ cultural uniqueness, complex family structure, and social practices. Currently, the home environment inventory (HEI) is the most widely applied Indian scale for assessment of home environment of school-going children. However, administration of the scale becomes cumbersome in a testing situation because of its lengthy nature. The present study aimed at shortening the 100-item HEI so as to reduce the respondents’ burden while preserving the quality of information simultaneously. Data were collected from 548 adolescent school students (Mean age?=?14 years; SD?=?1.24) from Bengali Hindu middle-class families and analyzed using a polytomous item response theory approach. A shortened version of the scale was derived through Principal Component Analysis and compared with the original scale based on the fit measures obtained through confirmatory factor analysis. Further, a preliminary validation of the shortened scale was done by comparing it with the original scale in another adolescent sample (n?=?256). Results bear evidence of statistically valid applicability of the shortened version of HEI.