SUMMARY BackgroundThe cancer risk of low-grade dysplasia (LGD) in chronic ulcerative colitis is variable and its management remain contentious.

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SUMMARY BackgroundRisk of cancer in Barrett's oesophagus is reported to vary between studies and also between countries, where the studies were conducted as per several systematic reviews. Cancer incidence has implications on surveillance strategies.

Aim-To determine the outcome and identify predictive factors in children with psychogenic non-epileptic seizures (PNES). Method-The biographies of 35 children with PNES, attending a tertiary paediatric neurology centre, were reviewed. Results-Thirty five children attending the department between 1987 and 1997 were evaluated at a mean follow up of 4.6 years. The age range was 6-18 years. Twenty four were girls and 11 were boys. Eleven patients had a diagnosis of epilepsy with PNES, the remainder having PNES alone. Cause fell into four categories: a history of violence, abuse, or neglect; a high level of anxiety; dysfunctional family relationships; and attention seeking or avoidance behaviour. Management in all but five cases involved assessment and follow up by a child psychologist or child psychiatrist. The outcome was encouraging, with 66% of patients becoming PNES free. A further 23% have > 50% reduction in the frequency of PNES. Only two have had no reduction. Outcome was best in the group without epilepsy. Conclusion-These results suggest that the prognosis of PNES is better in children than in adults, perhaps because causes are more likely to be external to the child, more easily identified, and more amenable to prompt intervention. The importance of good assessment, good communication, and a treatment plan that includes both symptom management and addressing the precipitating and perpetuating factors is emphasised. (Arch Dis Child 2000;82:474-478)

The physical properties of a doped quantum dot (QD) are strongly influenced by the dopant site inside the host lattice, which determines the host-dopant coupling from the overlap between the dopant and exciton wave functions of the host lattice. Although several synthetic methodologies have been developed for introducing dopants inside the size-confined semiconductor nanocrystals, the controlled dopant-host lattice coupling by dopant migration is still unexplored. In this work, the effect of lattice mismatch of CdS/ZnS core/shell QDs on Mn(II) dopant behavior was studied. It was found that the dopant migration toward the alloyed interface of core/shell QDs is a thermodynamically driven process to minimize the lattice strain within the nanocrystals. The dopant migration rate could be represented by the Arrhenius equation and therefore can be controlled by the temperature and lattice mismatch. Furthermore, the energy transfer between host CdS QDs and dopants can be finely turned in a wide range by dopant migration toward the alloyed interface during ZnS shell passivation, which provides an efficient method to control both the number of the emission band and the ratio of the emission from the host lattice and dopant ions.