Increased auditory cortex neural response amplitude in adults with chronic unilateral conductive hearing impairment.

Animal studies have demonstrated that unilateral hearing loss can induce changes in neural response amplitude of the mature central auditory system (CAS). However, there is limited physiological evidence of these neural gain changes in the auditory cortex of human adults. The present study investigated the impact of chronic, unilateral conductive hearing impairment on cortical auditory evoked potentials (CAEPs) recorded from 15 adults (21-65 years old) in response to a 1 kHz tone (80 ms duration) presented to the impaired ear via a bone conduction transducer. The amplitude and latency of the main CAEP components were compared to those obtained from normal hearing age-matched control participants. Both P1-N1 and N1-P2 amplitudes were significantly larger in the hearing impaired relative to the control participants. Differences between groups in the mean latencies of P1, N1, and P2 were not statistically significant. These results are the first to provide direct evidence of increased neural response amplitude in the adult human auditory cortex in the presence of unilateral conductive hearing loss. Importantly, the study shows that central gain changes are a direct result of deprivation of sound rather than cochlear or neural pathology.

Spatial models with covariates improve estimates of peat depth in blanket peatlands.

Peatlands are spatially heterogeneous ecosystems that develop due to a complex set of autogenic physical and biogeochemical processes and allogenic factors such as the climate and topography. They are significant stocks of global soil carbon, and therefore predicting the depth of peatlands is an important part of establishing an accurate assessment of their magnitude. Yet there have been few attempts to account for both internal and external processes when predicting the depth of peatlands. Using blanket peatlands in Great Britain as a case study, we compare a linear and geostatistical (spatial) model and several sets of covariates applicable for peatlands around the world that have developed over hilly or undulating terrain. We hypothesized that the spatial model would act as a proxy for the autogenic processes in peatlands that can mediate the accumulation of peat on plateaus or shallow slopes. Our findings show that the spatial model performs better than the linear model in all cases-root mean square errors (RMSE) are lower, and 95% prediction intervals are narrower. In support of our hypothesis, the spatial model also better predicts the deeper areas of peat, and we show that its predictive performance in areas of deep peat is dependent on depth observations being spatially autocorrelated. Where they are not, the spatial model performs only slightly better than the linear model. As a result, we recommend that practitioners carrying out depth surveys fully account for the variation of topographic features in prediction locations, and that sampling approach adopted enables observations to be spatially autocorrelated.

Ecosystem state shifts during long-term development of an Amazonian peatland.

The most carbon (C)-dense ecosystems of Amazonia are areas characterized by the presence of peatlands. However, Amazonian peatland ecosystems are poorly understood and are threatened by human activities. Here, we present an investigation into long-term ecohydrological controls on C accumulation in an Amazonian peat dome. This site is the oldest peatland yet discovered in Amazonia (peat initiation ca. 8.9 ka BP), and developed in three stages: (i) peat initiated in an abandoned river channel with open water and aquatic plants; (ii) inundated forest swamp; and (iii) raised peat dome (since ca. 3.9 ka BP). Local burning occurred at least three times in the past 4,500 years. Two phases of particularly rapid C accumulation (ca. 6.6-6.1 and ca. 4.9-3.9 ka BP), potentially resulting from increased net primary productivity, were seemingly driven by drier conditions associated with widespread drought events. The association of drought phases with major ecosystem state shifts (open water wetland-forest swamp-peat dome) suggests a potential climatic control on the developmental trajectory of this tropical peatland. A third drought phase centred on ca. 1.8-1.1 ka BP led to markedly reduced C accumulation and potentially a hiatus during the peat dome stage. Our results suggest that future droughts may lead to phases of rapid C accumulation in some inundated tropical peat swamps, although this can lead ultimately to a shift to ombrotrophy and a subsequent return to slower C accumulation. Conversely, in ombrotrophic peat domes, droughts may lead to reduced C accumulation or even net loss of peat. Increased surface wetness at our site in recent decades may reflect a shift towards a wetter climate in western Amazonia. Amazonian peatlands represent important carbon stores and habitats, and are important archives of past climatic and ecological information. They should form key foci for conservation efforts.

Solar cycles or random processes? Evaluating solar variability in Holocene climate records.

Many studies have reported evidence for solar-forcing of Holocene climate change across a range of archives. These studies have compared proxy-climate data with records of solar variability (e.g. (14)C or (10)Be), or have used time series analysis to test for the presence of solar-type cycles. This has led to some climate sceptics misrepresenting this literature to argue strongly that solar variability drove the rapid global temperature increase of the twentieth century. As proxy records underpin our understanding of the long-term processes governing climate, they need to be evaluated thoroughly. The peatland archive has become a prominent line of evidence for solar forcing of climate. Here we examine high-resolution peatland proxy climate data to determine whether solar signals are present. We find a wide range of significant periodicities similar to those in records of solar variability: periods between 40-100 years, and 120-140 years are particularly common. However, periodicities similar to those in the data are commonly found in random-walk simulations. Our results demonstrate that solar-type signals can be the product of random variations alone, and that a more critical approach is required for their robust interpretation.

The long-term fate of permafrost peatlands under rapid climate warming.

Permafrost peatlands contain globally important amounts of soil organic carbon, owing to cold conditions which suppress anaerobic decomposition. However, climate warming and permafrost thaw threaten the stability of this carbon store. The ultimate fate of permafrost peatlands and their carbon stores is unclear because of complex feedbacks between peat accumulation, hydrology and vegetation. Field monitoring campaigns only span the last few decades and therefore provide an incomplete picture of permafrost peatland response to recent rapid warming. Here we use a high-resolution palaeoecological approach to understand the longer-term response of peatlands in contrasting states of permafrost degradation to recent rapid warming. At all sites we identify a drying trend until the late-twentieth century; however, two sites subsequently experienced a rapid shift to wetter conditions as permafrost thawed in response to climatic warming, culminating in collapse of the peat domes. Commonalities between study sites lead us to propose a five-phase model for permafrost peatland response to climatic warming. This model suggests a shared ecohydrological trajectory towards a common end point: inundated Arctic fen. Although carbon accumulation is rapid in such sites, saturated soil conditions are likely to cause elevated methane emissions that have implications for climate-feedback mechanisms.

Restoration of blanket peatlands.

There is concern that ecosystem services provided by blanket peatlands have come under threat due to increasing degradation. Blanket peatlands are subject to a wide range of drivers of degradation and are topographically variable. As a result, many degradation forms can develop, including those resulting from eroding artificial drainage, incising gullies and areas of bare peat. Many degraded blanket peatlands have undergone restoration measures since the turn of the century. However, there has been little formal communication of the techniques used and their success. Using practitioner knowledge and a review of the available literature, this paper discusses the methodologies used for restoring sloping blanket peatlands. It then considers current understanding of the impact of restoration on blanket peatland ecosystem services. There is a paucity of research investigating impacts of several common restoration techniques and much more is needed if informed management decisions are to be made and funding is to be appropriately spent. Where data are available we find that restoration is largely beneficial to many ecosystem services, with improvements being observed in water quality and ecology. However, the same restoration technique does not always result in the same outcomes in all locations. The difference in response is predominantly due to the spatial and temporal heterogeneity inherent in all blanket peatlands. Peatland practitioners must take this variability into account when designing restoration strategies and monitoring impact.

Addressing an overweight child and an unaware parent in the general practice consultation.

KEY MESSAGES: General practitioners (GPs) can play a key role in tackling the current obesity epidemic, especially helping parents who may not realise that their child is overweight. In a ten-minute consultation, a GP should: explore a parent's ideas, concerns and expectations about food and exercise and build a picture of the home environmentexclude medical causes of overweight and plot height and weight on a growth chartoffer practical strategies and achievable goals, agree follow up and involve the multidisciplinary team for support. WHY THIS MATTERS TO ME: Childhood obesity is a global epidemic that has significant impact on the physical and psychological health and development of children, and often persists into adulthood where the health sequelae are well known. Parents are key players in putting healthy living advice into practice but our recent systematic review showed that parents are poor at recognising overweight in their own children. We believe GPs are key to providing health promotion for this group. However, to approach this sensitive subject requires one to have confidence and skills at one's fingertips and we hope this guide can provide these.

A systematic review of parental perception of overweight status in children.

To systematically review the proportion of parents able to recognize overweight status in their children who were recorded as being overweight by internationally recognized standards. Two independent reviewers searched electronic databases including MEDLINE, EMBASE, PSYCHINFO, and CINAHL for studies from inception to August 2007 using search terms related to childhood overweight and parents. Twenty-three studies satisfied inclusion criteria, representing 3864 overweight children from 7 countries and 5 distinct standard definitions of overweight status. Seventeen of 23 studies employed either greater than 95th centile or the International Obesity Task Force criteria. Parental recognition of their child's overweight status ranged from 6.2% to 73%, but in 19 of 23 studies, it was less than 50%. More than half of parents cannot recognize when their child is overweight. Relying on parents to seek help for their overweight children is likely to be ineffective, and hence population-based screening may be justified.