Making our own meanings: a critical review of media effects research in relation to the causation of aggression and social skills difficulties in children and anorexia nervosa in young women.

This study examines concerns regarding the effects of video and television on certain types of behaviour. In the forefront of such debate is the claim by Elizabeth Newson [Newson E. (1994) Video violence and the protection of children. Journal of Mental Health 3,221-227] that video and television representations of violence have a direct influence on children. Newson's argument is challenged in this paper, as is the popular belief that media images cause anorexia nervosa in young women. The author's argument against the notion of such direct influence is aimed at media effects research, which will be criticized as both deterministic and simplistic, on the grounds that as a positivist approach it overlooks the sophisticated resistance of viewers. Evidence from cultural studies, within an interpretivist tradition, will be cited as a challenge to the 'moral panic of the media', highlighting the incommensurability of diverse research disciplines. Mental health professionals have long been confronted with the failure of science to provide any unitary truth regarding the aetiology of mental health problems. Frustrating as that is, it is proposed that diverse empirical methods in the social sciences enrich debate and serve to expose the quest for a monocasual aetiology as fundamentally flawed. Media effects are thus only part of a myriad possible causes of anorexia nervosa, and yet are seen as central to current alarm regarding the way children learn (or don't learn) to cooperate with, and show concern for, other people.

Population differentiation and evolution in the common guillemot Uria aalge.

Common (Uria aalge) and Brünnich's guillemots (U. lomvia) are colonial seabirds that nest in temperate to arctic oceans throughout the Northern hemisphere. They are very similar in the characteristics of ecology, demography and life history that are thought to determine the extent of differentiation among populations, yet geographic variation in morphology is notably greater in common guillemots. Despite evidence of strong natal philopatry, previous analyses of allozymes and the mitochondrial cytochrome b gene revealed little genetic differentiation among North Atlantic colonies of Brünnich's guillemots. To determine if the more extensive morphological variability in common guillemots reflects greater genetic variability, we sequenced part of the cytochrome b gene for 160 common guillemots from 10 colonies distributed throughout the Northern hemisphere. Genotype frequencies and phylogenetic relationships among genotypes both indicated that Atlantic and Pacific populations are genetically distinct. Genetic divergence among genotypes suggested that differentiation of these populations has resulted from separation by Pleistocene glaciers and the Bering Landbridge, as well as by currently unsuitable breeding habitat in the Arctic Ocean. Cytochrome b genotype frequencies also differed among Atlantic colonies, and appeared to define a cline similar to that described for morphological characters. Analyses of sequence variation suggested that this variation probably results from secondary contact between two refugial populations from the Pleistocene glaciations, rather than from isolation by distance or selection. In contrast, the Atlantic population of Brünnich's guillemots appears to have arisen through recent expansion of a single homogeneous refugial population.

Recent changes in levels of persistent organochlorines and mercury in eggs of seabirds from the Barents Sea.

Eggs of ten seabird species were collected from six regions in North Norway, Svalbard and NW Russia in 1993, and were analyzed for organochlorines (OCs) and mercury. Significant declines in levels of PCBs, p,p'-DDE, HCB, beta-HCH, gamma-HCH and oxychlordane were documented in nearly half the data set since a similar study in 1983 in six of the seabird species breeding in North Norway. Only four of the 90 paired data sets increased significantly, and the remainder remained unchanged. There was very little change in mercury levels. The decline in OCs corresponds to similar declines found in Canada and the Baltic Sea, and to declines documented in marine fish in a Norwegian fjord. They can all be attributed to the reduction in use and spread of contaminants, both in Norway and internationally. No consistent regional differences in residue levels were found.

Brain stem localization of rodent esophageal premotor neurons revealed by transneuronal passage of pseudorabies virus.

BACKGROUND/AIMS: Brain stem premotor neurons control swallowing through contacts with both afferent neurons and motoneurons. The location and connectivity of premotor neurons innervating the esophagus was determined using pseudorabies virus. METHODS: In 30 rats, viral injections were made into either the cervical or subdiaphragmatic esophagus, cricothyroid muscle, or stomach. After a 48-62-hour survival, brain sections were processed immunocytochemically for the virus. RESULTS: Neuronal labeling was limited to the compact formation of the nucleus ambiguus for survivals of 48-54 hours. At 57-62-hour survivals, virus-labeled second-order neurons (premotor neurons) were localized to the central subnucleus of nucleus of the solitary tract. Injections in the cricothyroid muscle and stomach resulted in distinct patterns of motoneuronal labeling in the nucleus ambiguus and dorsal motor nucleus and premotor neuronal labeling in the nucleus of the solitary tract. CONCLUSIONS: Virus-labeled premotor neurons in the nucleus of the solitary tract occurred as a result of retrograde transport of the virus from the nucleus ambiguus because no viral antigen was present in the tractus solitarius. The esophagus is controlled by a central circuit whereby esophageal vagal afferents terminate on premotor neurons in the central subnucleus that in turn innervate esophageal motoneurons in the nucleus ambiguus.

Mercury concentrations in seabirds from colonies in the northeast Atlantic.

Total mercury concentrations were determined in samples of body feathers from a range of common seabird species breeding at Låtrabjarg, northwest Iceland, St. Kilda, Foula and the Firth of Forth, Scotland and Bleiksøy, Syltefjord, and Hornøy, Norway. Seabirds from Låtrabjarg generally exhibited the highest mercury concentrations, with a trend of decreasing mercury concentrations in a southwest to northeast direction in seabirds at the other colonies; seabirds at Hornøy were generally found to have the lowest mercury concentrations. Some species at the Firth of Forth exhibited relatively elevated mercury concentrations compared to those at Foula and Norwegian sites. Inter-colony differences in diet were thought to be relatively small for most species and unlikely to account for the range of mercury concentrations measured in the seabirds (Låtrabjarg: lowest arithmetic mean mercury concentration in common guillemots Uria aalge, 1.6 micrograms/g, s.d. = 0.6, n = 45; highest arithmetic mean mercury concentration in kittiwakes Rissa tridactyla, 5.5 micrograms/g, s.d. = 1.7, n = 36). The oceanic transport of mercury, together with the effects of anthropogenic inputs of mercury to the northeast Atlantic, and the removal of mercury from the water column via biological activity are discussed as influential factors determining the observed patterns of mercury concentration in seabirds.