Who's afraid of the big bad wolf: a prospective paradigm to test Rachman's indirect pathways in children

Rachman's theory [The conditioning theory of fear insition: a critical examination. Behav. Res. Ther. 15 (1977) 375–387] of fear acquisition suggests that fears and phobias can be acquired through three pathways: direct conditioning, vicarious learning and information/instruction. Although retrospective studies have provided some evidence for these pathways in the development of phobias during childhood [see King, Gullone, & Ollendick, Etiology of childhood phobias: current status of Rachman's three pathway's theory. Behav. Res. Ther. 36 (1998) 297–309 for a review], these studies have relied on long-term past memories of adult phobics or their parents. The current study was aimed towards developing a paradigm in which the plausibility of Rachman's indirect pathways could be investigated prospectively. In Experiment 1, children aged between 7 and 9 were presented with two types of information about novel stimuli (two monsters): video information and verbal information in the form of a story. Fear-related beliefs about the monsters changed significantly as a result of verbal information but not video information. Having established an operational paradigm, Experiment 2 looked at whether the source of verbal information had an effect on changes in fear-beliefs. Using the same paradigm, information about the monsters was provided by either a teacher, an adult stranger or a peer, or no information was given. Again, verbal information significantly changed fear-beliefs, but only when the information came from an adult. The role of information in the acquisition of fear and maintenance of avoidant behaviour is discussed with reference to modern conditioning theories of fear acquisition

Methane, carbon dioxide and nitrous oxide fluxes from a temperate salt marsh: grazing management does not alter global warming potential

Soil greenhouse gas emissions from cattle grazed and un-grazed temperate upper salt marsh were measured using dark static chambers, monthly for one year. Below-ground gas sampling tubes were also used to measure soil methane (CH4) concentrations. CH4 efflux from grazed and un-grazed salt marsh did not differ significantly although grazing did lead to ‘hotspots’ of underground CH4 (up to 6% of total air volume) and CH4 efflux (peak of 9 mg m−2 h−1) significantly linked to high soil moisture content, low soil temperatures and the presence of Juncus gerardii. Carbon dioxide (CO2) efflux was greater from the un-grazed marsh (mean of 420 mg m−2 h−1) than the grazed marsh (mean of 333 mg m−2 h−1) throughout most of the year and was positively correlated with the deeper water table and greater soil temperatures. Grazing was not a significant predictor of nitrous oxide (N2O) soil emissions. Global Warming Potential (GWP; over 100 years), calculated from mean yearly chamber fluxes for CH4 and CO2, did not differ significantly with grazing treatment. Seasonal variation in the key drivers of soil greenhouse gas efflux; soil temperature, moisture and water table, plus the presence or absence of aerenchymatous plants such as J. gerardii were more important to the magnitude of greenhouse gas emissions than grazing management per se

Substrate Influences Temperature Sensitivity of Dissolved Organic Carbon (DOC) and Nitrogen (DON) Mineralization in Arid Agricultural Soils

The bioavailability of nitrogen (N) in soil relies on the progressive breakdown of necromass protein to peptide and amino acid components and conversion to inorganic N forms. We understand the fluxes and pathways of the N cycle downstream from amino acids, but our understanding of the factors controlling peptide and amino acid mineralization, particularly in arid soils, is lacking. We investigated the influence of temperature on the rate of dissolved organic carbon (DOC) and nitrogen (DON) cycling in three agricultural soils from Saudi Arabia. Although the physical and chemical properties of the soils differed markedly, phospholipid fatty acid (PLFA) analysis revealed they had similar topsoil and subsoil microbial communities. Soils behaved similarly in terms of the rate of substrate use, microbial C-use efficiency, and response to temperature. Substrate mineralization rate increased with temperature with more C being allocated to microbial catabolic rather than anabolic processes. Our results show that climate change is likely to lead to changes in soil organic matter turnover and shift C allocation patterns within the soil microbial community. This is expected to reduce soil quality and exacerbate nutrient losses. Management strategies are required to promote the retention of organic matter in these soils