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A review of physiology and behaviour–based studies on the function of stereotypic behaviour indicates contradiction and inconsistency within the literature. By considering appropriate neurochemical data alongside an existing model of motivation (Hughes and Duncan, 1988), a greater understanding of the function of stereotypy may be gained. The Hughes and Duncan model (1988), described stereotypies as highly motivated appetitive behaviours performed repeatedly in an environment where consummatory goals are denied. Moreover, appetitive behaviours activate reward circuitry such as the ventral tegmental area and nucleus accumbens and are thus considered to have a reward value associated with their performance (Carr, 2002; Jones et al., 1990). Stress induced sensitisation of reward circuitry may result in appetitive ‘stereotypies’ having increased reward value, perhaps becoming consummatory in their own right. In such a scenario, stereotypic behaviour could function as a coping tool, allowing the animal to counter the effects of an aversive environment.
Approximately 8% of European performance horses engage in cribbiting behaviour (McGreevy et al.,1995, Redbo et al., 1998), a trait which can reduce both financial value and welfare status of the animal. An increase in prevalence to 26% was reported in those families originating from crib-biting sires (Vecchiotti and Galantini 1986), tentatively implying that a genetic component may be involved. Indeed, in a herd of Przewalski's horse, there was an 84% chance of offspring crib-biting if they originated from cribbing parents (Marsden and Henderson 1994). Finally, hereditary transmission has been more reliably demonstrated in the rodent, where stereotypy can be induced following 9 days of food restriction in the highly inbred DBA mouse strain, but not the C57 strain (Cabib and Bonaventura 1997) suggesting 1) propagation of a genetic component within the DBA genotype and 2) the requirement of an environmental stressor for stereotypy development. In the rodent model this genetic pre-disposition manifests physiologically as a facilitation of dopamine transmission within the mesolimbic projection following a period of stress (Cabib et al., 1998).
Recently analysed hypervelocity impact data from retrieved satellites are summarised. Analyses of perforation data show that mean densities are low (around 1.5-2 g/cm3), impact velocities are consistent with radar meteor observations and that high aspect ratio particles are not found. Mean data, for Fmax > 30 μm agrees well with the Grün et al. Interplanetary flux model, though there is evidence of a strong bias towards the Earth apex of motion direction. For Fmax < 30 μm the data at LDEF's altitude is dominated by space debris.
Parents are a major supplier of alcohol to adolescents, yet there is limited research examining the impact of this on adolescent alcohol use. This study investigates associations between parental supply of alcohol, supply from other sources, and adolescent drinking, adjusting for child, parent, family and peer variables.
A cohort of 1927 adolescents was surveyed annually from 2010 to 2014. Measures include: consumption of whole drinks; binge drinking (>4 standard drinks on any occasion); parental supply of alcohol; supply from other sources; child, parent, family and peer covariates.
After adjustment, adolescents supplied alcohol by parents had higher odds of drinking whole beverages [odds ratio (OR) 1.80, 95% confidence interval (CI) 1.33–2.45] than those not supplied by parents. However, parental supply was not associated with bingeing, and those supplied alcohol by parents typically consumed fewer drinks per occasion (incidence rate ratio 0.86, 95% CI 0.77–0.96) than adolescents supplied only from other sources. Adolescents obtaining alcohol from non-parental sources had increased odds of drinking whole beverages (OR 2.53, 95% CI 1.86–3.45) and bingeing (OR 3.51, 95% CI 2.53–4.87).
Parental supply of alcohol to adolescents was associated with increased risk of drinking, but not bingeing. These parentally-supplied children also consumed fewer drinks on a typical drinking occasion. Adolescents supplied alcohol from non-parental sources had greater odds of drinking and bingeing. Further follow-up is necessary to determine whether these patterns continue, and to examine alcohol-related harm trajectories. Parents should be advised that supply of alcohol may increase children's drinking.
We give an update of our ongoing survey for intracluster light (ICL), in a sample of distant Abell clusters. We find that the amount of intracluster starlight is comparable to that seen in nearby clusters, and that tidal debris appear to be common.
The aim of this study was to examine the population structure, transmission and spatial relationship between genotypes of Shiga toxin-producing Escherichia coli (STEC) and Campylobacter jejuni, on 20 dairy farms in a defined catchment. Pooled faecal samples (n = 72) obtained from 288 calves were analysed by real-time polymerase chain reaction (rtPCR) for E. coli serotypes O26, O103, O111, O145 and O157. The number of samples positive for E. coli O26 (30/72) was high compared to E. coli O103 (7/72), O145 (3/72), O157 (2/72) and O111 (0/72). Eighteen E. coli O26 and 53 C. jejuni isolates were recovered from samples by bacterial culture. E. coli O26 and C. jejuni isolates were genotyped using pulsed-field gel electrophoresis and multilocus sequence typing, respectively. All E. coli O26 isolates could be divided into four clusters and the results indicated that E. coli O26 isolates recovered from calves on the same farm were more similar than isolates recovered from different farms in the catchment. There were 11 different sequence types of C. jejuni isolated from the cattle and 22 from water. An analysis of the population structure of C. jejuni isolated from cattle provided evidence of clustering of genotypes within farms, and among groups of farms separated by road boundaries.