Early childhood neurodevelopment after intrauterine growth restriction: a systematic review

BACKGROUND AND OBJECTIVE: Children who experienced intrauterine growth restriction (IUGR) may be at increased risk for adverse developmental outcomes in early childhood. The objective of this study was to carry out a systematic review of neurodevelopmental outcomes from 6 months to 3 years after IUGR.

METHODS: PubMed, Embase, PsycINFO, Maternity and Infant Care, and CINAHL databases were searched by using the search terms intrauterine, fetal, growth restriction, child development, neurodevelopment, early childhood, cognitive, motor, speech, language. Studies were eligible for inclusion if participants met specified criteria for growth restriction, follow-up was conducted within 6 months to 3 years, methods were adequately described, non-IUGR comparison groups were included, and full English text of the article was available. A specifically designed data extraction form was used. The methodological quality of included studies was assessed using well-documented quality-appraisal guidelines.

RESULTS: Of 731 studies reviewed, 16 were included. Poorer neurodevelopmental outcomes after IUGR were described in 11. Ten found motor, 8 cognitive, and 7 language delays. Other delays included social development, attention, and adaptive behavior. Only 8 included abnormal Doppler parameters in their definitions of IUGR.

CONCLUSIONS: Evidence suggests that children are at risk for poorer neurodevelopmental outcomes following IUGR from 6 months to 3 years of age. The heterogeneity of primary outcomes, assessment measures, adjustment for confounding variables, and definitions of IUGR limits synthesis and interpretation. Sample sizes in most studies were small, and some examined preterm IUGR children without including term IUGR or AGA comparison groups, limiting the value of extant studies.

Measuring non-use value of environmental goods using the contingent valuation method:problems of information and cognition and the application of cognitive questionnaire design methods

Much interest now focuses on the use of the contingent valuation method (CVM) to assess non-use value of environmental goods. The paper reviews recent literature and highlights particular problems of information provision and respondent knowledge, comprehension and cognition. These must be dealt with by economists in designing CVM surveys for eliciting non-use values. Cognitive questionnaire design methods are presented which invoke concepts from psychology and tools from cognitive survey design (focus groups and verbal reports) to reduce a complex environmnetal good into a meaningful commodity that can be valued by respondents in a contingent market. This process is illustrated with examples from the authors' own research valuing alternative afforestation programmes. -Authors

The Development and Testing of a New Version of the Cognitive Reflection Test Applying Item Response Theory (IRT)

The cognitive reflection test (CRT) is a short measure of a person's ability to resist intuitive response tendencies and to produce a normatively correct response, which is based on effortful reasoning. Although the CRT is a very popular measure, its psychometric properties have not been extensively investigated. A major limitation of the CRT is the difficulty of the items, which can lead to floor effects in populations other than highly educated adults. The present study aimed at investigating the psychometric properties of the CRT applying item response theory analyses (a two-parameter logistic model) and at developing a new version of the scale (the CRT-long), which is appropriate for participants with both lower and higher levels of cognitive reflection. The results demonstrated the good psychometric properties of the original, as well as the new scale. The validity of the new scale was also assessed by measuring correlations with various indicators of intelligence, numeracy, reasoning and decision-making skills, and thinking dispositions. Moreover, we present evidence for the suitability of the new scale to be used with developmental samples. Finally, by comparing the performance of adolescents and young adults on the CRT and CRT-long, we report the first investigation into the development of cognitive reflection.

Dual-Hop Cognitive Amplify-and-Forward Relaying Networks over η− μ Fading Channels

This paper presents a thorough performance analysis of dual-hop cognitive amplify-and-forward (AF) relaying networks under spectrum-sharing mechanism over independent non-identically distributed (i.n.i.d.) 􀀀 fading channels. In order to guarantee the quality-of-service (QoS) of primary networks, both maximum tolerable peak interference power Q at the primary users (PUs) and maximum allowable transmit power P at secondary users (SUs) are considered to constrain transmit power at the cognitive transmitters. For integer-valued fading parameters, a closed-form lower bound for the outage probability (OP) of the considered networks is obtained. Moreover, assuming arbitrary-valued fading parameters, the lower bound in integral form for the OP is derived. In order to obtain further insights on the OP performance, asymptotic expressions for the OP at high SNRs are derived, from which the diversity/coding gains and the diversity-multiplexing gain tradeoff (DMT) of the secondary network can be readily deduced. It is shown that the diversity gain and also the DMT are solely determined by the fading parameters of the secondary network whereas the primary network only affects the coding gain. The derived results include several others available in previously published works as special cases, such as those for Nakagami-m fading channels. In addition, performance evaluation results have been obtained by Monte Carlo computer simulations which have verified the accuracy of the theoretical analysis.

Secure Switch-and-Stay Combining (SSSC) for Cognitive Relay Networks

In this paper, we study a two-phase underlay cognitive relay network, where there exists an eavesdropper who can overhear the message. The secure data transmission from the secondary source to secondary destination is assisted by two decode-and-forward (DF) relays. Although the traditional opportunistic relaying technique can choose one relay to provide the best secure performance, it needs to continuously have the channel state information (CSI) of both relays, and may result in a high relay switching rate. To overcome these limitations, a secure switch-and-stay combining (SSSC) protocol is proposed where only one out of the two relays is activated to assist the secure data transmission, and the secure relay switching occurs when the relay cannot support the secure communication any longer. This security switching is assisted by either instantaneous or statistical eavesdropping CSI. For these two cases, we study the system secure performance of SSSC protocol, by deriving the analytical secrecy outage probability as well as an asymptotic expression for the high main-to-eavesdropper ratio (MER) region. We show that SSSC can substantially reduce the system complexity while achieving or approaching the full diversity order of opportunistic relaying in the presence of the instantaneous or statistical eavesdropping CSI.