Spatial, seasonal and interannual variability of supraglacial ponds in the Langtang Valley of Nepal, 1999–2013

Supraglacial ponds play a key role in absorbing atmospheric energy and directing it to the ice of debris-covered glaciers, but the spatial and temporal distribution of these features is not well documented. We analyse 172 Landsat TM/ETM+ scenes for the period 1999–2013 to identify thawed supraglacial ponds for the debris-covered tongues of five glaciers in the Langtang Valley of Nepal. We apply an advanced atmospheric correction routine (Landcor/6S) and use band ratio and image morphological techniques to identify ponds and validate our results with 2.5 m Cartosat-1 observations. We then characterize the spatial, seasonal and interannual patterns of ponds. We find high variability in pond incidence between glaciers (May–October means of 0.08–1.69% of debris area), with ponds most frequent in zones of low surface gradient and velocity. The ponds show pronounced seasonality, appearing in the pre-monsoon as snow melts, peaking at the monsoon onset at 2% of debris-covered area, then declining in the post-monsoon as ponds drain or freeze. Ponds are highly recurrent and persistent, with 40.5% of pond locations occurring for multiple years. Rather than a trend in pond cover over the study period, we find high interannual variability for each glacier after controlling for seasonality

A physically based 3-D model of ice cliff evolution over debris-covered glaciers

We use high-resolution digital elevation models (DEMs) from unmanned aerial vehicle (UAV) surveys to document the evolution of four ice cliffs on the debris-covered tongue of Lirung Glacier, Nepal, over one ablation season. Observations show that out of four cliffs, three different patterns of evolution emerge: (i) reclining cliffs that flatten during the ablation season; (ii) stable cliffs that maintain a self-similar geometry; and (iii) growing cliffs, expanding laterally. We use the insights from this unique data set to develop a 3-D model of cliff backwasting and evolution that is validated against observations and an independent data set of volume losses. The model includes ablation at the cliff surface driven by energy exchange with the atmosphere, reburial of cliff cells by surrounding debris, and the effect of adjacent ponds. The cliff geometry is updated monthly to account for the modifications induced by each of those processes. Model results indicate that a major factor affecting the survival of steep cliffs is the coupling with ponded water at its base, which prevents progressive flattening and possible disappearance of a cliff. The radial growth observed at one cliff is explained by higher receipts of longwave and shortwave radiation, calculated taking into account atmospheric fluxes, shading, and the emission of longwave radiation from debris surfaces. The model is a clear step forward compared to existing static approaches that calculate atmospheric melt over an invariant cliff geometry and can be used for long-term simulations of cliff evolution and to test existing hypotheses about cliffs' survival

Optimising NDWI supraglacial pond classification on Himalayan debris-covered glaciers

The ability of medium-resolution (10–30 m) satellite imagery to delineate the size and persistence of ponds on debris-covered glaciers is a topic of recent interest as it has become apparent through the use of fine-resolution products that smaller ponds have often been neglected. In this study, we performed a quantitative analysis of pond detection using a normalised difference water index (NDWI) applied to several widely used satellite sensors, which offer multispectral information at high radiometric precision. These data include: RapidEye (5 m spatial resolution), Sentinel-2 Multispectral Instrument (MSI) (10–20 m), and Landsat 8 Operational Land Imager (OLI) multispectral imagery (30 m). We demonstrate a method to derive an optimum NDWI value for pond classification using a subset reference dataset of 285 ponds classified using fine-resolution (0.5 m) imagery. We then applied the optimised NDWI (NDWI-O) to the remaining images to assess pond classification accuracy against a broader reference dataset of 898 ponds. NDWI values calculated using Sentinel-2 imagery showed the best spectral contrast between water and surrounding debris cover, and the strongest relationship with pixel water content (R2 = 0.56), followed by the RapidEye NDWI (R2 = 0.45). We conclude that RapidEye and Sentinel-2 imagery is best suited for accurate pond classification using a multispectral classification approach, which is important for quantifying their role in glacier ablation, meltwater regulation, and lake development. By comparison, the impact of using coarse-resolution Landsat 8 imagery to characterise surface water dynamics is minimised when applied to large glacier lakes, where the area-to-perimeter ratio is greater

The plight of the sense-making ape

This is a selective review of the published literature on object-choice tasks, where participants use directional cues to find hidden objects. This literature comprises the efforts of researchers to make sense of the sense-making capacities of our nearest living relatives. This chapter is written to highlight some nonsensical conclusions that frequently emerge from this research. The data suggest that when apes are given approximately the same sense-making opportunities as we provide our children, then they will easily make sense of our social signals. The ubiquity of nonsensical contemporary scientific claims to the effect that humans are essentially--or inherently--more capable than other great apes in the understanding of simple directional cues is, itself, a testament to the power of preconceived ideas on human perception

Memory consolidation in the cerebellar cortex

Several forms of learning, including classical conditioning of the eyeblink, depend upon the cerebellum. In examining mechanisms of eyeblink conditioning in rabbits, reversible inactivations of the control circuitry have begun to dissociate aspects of cerebellar cortical and nuclear function in memory consolidation. It was previously shown that post-training cerebellar cortical, but not nuclear, inactivations with the GABA(A) agonist muscimol prevented consolidation but these findings left open the question as to how final memory storage was partitioned across cortical and nuclear levels. Memory consolidation might be essentially cortical and directly disturbed by actions of the muscimol, or it might be nuclear, and sensitive to the raised excitability of the nuclear neurons following the loss of cortical inhibition. To resolve this question, we simultaneously inactivated cerebellar cortical lobule HVI and the anterior interpositus nucleus of rabbits during the post-training period, so protecting the nuclei from disinhibitory effects of cortical inactivation. Consolidation was impaired by these simultaneous inactivations. Because direct application of muscimol to the nuclei alone has no impact upon consolidation, we can conclude that post-training, consolidation processes and memory storage for eyeblink conditioning have critical cerebellar cortical components. The findings are consistent with a recent model that suggests the distribution of learning-related plasticity across cortical and nuclear levels is task-dependent. There can be transfer to nuclear or brainstem levels for control of high-frequency responses but learning with lower frequency response components, such as in eyeblink conditioning, remains mainly dependent upon cortical memory storage

Mapping ice cliffs on debris-covered glaciers using multispectral satellite images

Ice cliffs play a key role in the mass balance of debris-covered glaciers, but assessing their importance is limited by a lack of datasets on their distribution and evolution at scales larger than an individual glacier. These datasets are often derived using operator-biased and time-consuming manual delineation approaches, despite the recent emergence of semi-automatic mapping methods. These methods have used elevation or multispectral data, but the varying slope and mixed spectral signal of these dynamic features makes the transferability of these approaches particularly challenging. We develop three semi-automated and objective new approaches, based on the Spectral Curvature and Linear Spectral Unmixing of multispectral images, to map these features at a glacier to regional scale. The transferability of each method is assessed by applying it to three sites in the Himalaya, where debris-covered glaciers are widespread, with varying lithologic, glaciological and climatic settings, and encompassing different periods of the melt season. We develop the new methods keeping in mind the wide range of remote sensing platforms currently in use, and focus in particular on two products: we apply the three approaches at each site to near-contemporaneous atmospherically-corrected Pléiades (2 m resolution) and Sentinel-2 (10 m resolution) images and assess the effects of spatial and spectral resolution on the results. We find that the Spectral Curvature method works best for the high spatial resolution, four band Pléaides images, while a modification of the Linear Spectral Unmixing using the scaling factor of the unmixing is best for the coarser spatial resolution, but additional spectral information of Sentinel-2 products. In both cases ice cliffs are mapped with a Dice coefficient higher than 0.48. Comparison of the Pléiades results with other existing methods shows that the Spectral Curvature approach performs better and is more robust than any other existing automated or semi-automated approaches. Both methods outline a high number of small, sometimes shallow-sloping and thinly debris-covered ice patches that differ from our traditional understanding of cliffs but may have non-negligible impact on the mass balance of debris-covered glaciers. Overall these results pave the way for large scale efforts of ice cliff mapping that can enable inclusion of these features in debris-covered glacier melt models, as well as allow the generation of multiple datasets to study processes of cliff formation, evolution and decline

Appropriate interventions for the prevention and management of self-harm: a qualitative exploration of service-users' views

BACKGROUND: The engagement of service-users in exploring appropriate interventions for self-harm has been relatively neglected in comparison with clinical studies focusing on the management and prevention of self-harm. The purpose of this study was to investigate perceptions of interventions for self-harm (formal and informal, prevention and treatment) among people who have first-hand experience as a result of their own behaviour. METHODS: Semi-structured interviews were undertaken with 14 patients admitted to hospital following a repeat act of self-harm. Data analysis was undertaken thematically, drawing broadly on some of the principles and techniques of grounded theory RESULTS: The patients were a heterogeneous group with respect to their personal characteristics and the nature of their self-harm. Thirteen of the 14 patient accounts could be assigned to one or more of three overlapping experiential themes: the experience of psychiatric illness, the experience of alcohol dependency, and the experience of traumatic life events and chronic life problems. These themes were related to the nature of patients' self-harm and their experiences of, and attitudes towards, interventions for self-harm and their attitudes towards these. There was a clear preference for specialist community-based interventions, which focus on the provision of immediate aftercare and acknowledge that the management of self-harm may not necessarily involve its prevention. The findings generate the preliminary hypothesis that personal circumstances and life history are major influences on the choice of interventions for self-harm. CONCLUSION: This study attests to the importance of recognising differences within the self-harming population, and acknowledging patients' personal circumstances and life history. These may provide clues to the antecedents of their self-harm, and lead to more acceptable and appropriate treatments

Faculty verbal evaluations reveal strategies used to promote medical student performance

Background: Preceptors rarely follow medical students’ developing clinical performance over time and across disciplines. This study analyzes preceptors’ descriptions of longitudinal integrated clerkship (LIC) students’ clinical development and their identification of strategies to guide students’ progress. Methods: We used a common evaluation framework, reporter-interpreter-manager-educator, to guide multidisciplinary LIC preceptors’ discussions of students’ progress. We conducted thematic analysis of transcripts from preceptors’ (seven longitudinal ambulatory preceptors per student) quarterly group discussions of 15 students’ performance over one year. Results: All students’ clinical development progressed, although most experienced obstacles. Lack of structure in the history and physical exam commonly obstructed progression. Preceptors used templates for data gathering, and modeling or experiences in the inpatient setting to provide time and solidify structure. To advance students’ knowledge acquisition, many preceptors identified focused learning topics with their students; to promote application of knowledge, preceptors used reasoning strategies to teach the steps involved in synthesizing clinical data. Preceptors shared accountability for helping students advance as the LIC allowed them to follow students’ response to teaching strategies. Discussion: These results depict preceptors’ perceptions of LIC students’ developmental continuum and illustrate how multidisciplinary preceptors can use a common evaluation framework to identify strategies to improve performance and follow students’ performance longitudinally