Absorption problems for quantum walks in one dimension

This paper treats absorption problems for the one-dimensional quantum walk determined by a 2 times 2 unitary matrix U on a state space {0,1,...,N} where N is finite or infinite by using a new path integral approach based on an orthonormal basis P, Q, R and S of the vector space of complex 2 times 2 matrices. Our method studied here is a natural extension of the approach in the classical random walk.Comment: 15 pages, small corrections, journal reference adde

Reciprocal Prospective Relationships Between Loneliness and Weight Status in Late Childhood and Early Adolescence

Adolescents who do not conform to weight ideals are vulnerable to disapproval and victimization from peers in school. But, missing from the literature is a prospective examination of weight status and feelings of loneliness that might come from those experiences. Using data from the Québec Longitudinal Study of Child Development, we filled that gap by examining the prospective associations between loneliness and weight status when the sample was aged 10 to 13 years. At ages 10, 12, and 13 years, 1042 youth (572 females; 92% from French speaking homes) reported on their loneliness and were weighed and measured. Family income sufficiency was included in our analyses given its relationship with weight status, but also its possible link with loneliness during early adolescence. The findings showed that (1) weight status and loneliness were not associated concurrently; (2) weight status predicted increases in loneliness from ages 12 to 13 years; and (3) loneliness predicted increases in weight from ages 12 to 13 years among female adolescents, but weight loss among male adolescents. The fact that loneliness was involved in weight gain for females suggests that interventions focused on reducing loneliness and increasing connection with peers during early adolescence could help in reducing obesity

Quality of life in a clinical sample of obese children

To measure health-related quality of life (HRQoL) in a clinical sample of obese children by child self-report and parent-proxy report; to compare quality of life assessments provided by obese children and their parents; to assess differences in quality of life between the obese clinical sample and healthy control children. Pairwise comparison of obese children matched for age, gender and socio-economic status with non-obese controls. One hundred and twenty-six obese children (body mass index (BMI) 98th centile) and 71 lean control children (BMI <85th centile). Controls were matched with 71 children from the obese clinical group (mean age 8.6, standard deviation (s.d.) 1.9 years; 33 M/38 F). Measurement: The Paediatric Quality of Life Inventory (UK) version 4 was self-administered to parents and to children aged 8–12 years and interview was administered to children aged 5–7 years. This questionnaire assessed physical, social, emotional and school functioning from which total, physical and psychosocial health summary scores were derived. In the obese clinical group (n=126), parent proxy-reported quality of life was low for all domains. In the obese clinical group, parent-reported scores were significantly lower than child self-reported scores in all domains except physical health and school functioning. Parent-proxy reports were significantly higher for healthy controls than obese children in all domains (median total score 85.2 vs 64.7; 95% confidence interval (CI) 15.6, 24.1). For child self-reports, only physical health was significantly higher for healthy controls than obese children (median score 81.3 vs 75.0; 95% CI 3.1, 12.5). HRQoL is impaired in clinical samples of obese children compared to lean children, but the degree of impairment is likely to be greatest when assessed using the parent perspective rather than the child perspective

Recolonisation of meiofauna after catastrophic iceberg scouring in shallow Antarctic sediments

A series of 10 samples from sediment in and adjacent to a shallow coastal iceberg scour at Signy Island, Antarctica, were taken by hand coring from 17 December 1993 until 23 August 1994. Scouring by the iceberg led to more than a 95% decrease in meiofaunal abundance and to a certain degree of reduction in diversity. Nematodes were always the most dominant group of meiofauna. The return of major meiofauna groups to control levels was accomplished in 30 days, although a decrease in abundance on the 50th day made interpretation difficult. The pioneering meiofaunal colonisers were copepods and ostracods, followed by nematodes. Microlaimus sp.1 was dominant among the nematodes throughout the whole period. Epistratum feeders and non-selective deposit feeders were highly dominant over selective deposit feeders and predators/omnivores. The Maturity Index, a measure for stress within nematode communities, was relatively low at all times and in controls, which indicates that r-strategists prevail in this community. In spite of the catastrophic destruction, nematode community structure was not affected by the iceberg impact, and there was no evidence of succession during recovery. This suggests that the nematode community in the shallow subtidal coast at Signy Island is well adapted to ice disturbance