Increased variability in Greenland Ice Sheet runoff from satellite observations.

Runoff from the Greenland Ice Sheet has increased over recent decades affecting global sea level, regional ocean circulation, and coastal marine ecosystems, and it now accounts for most of the contemporary mass imbalance. Estimates of runoff are typically derived from regional climate models because satellite records have been limited to assessments of melting extent. Here, we use CryoSat-2 satellite altimetry to produce direct measurements of Greenland's runoff variability, based on seasonal changes in the ice sheet's surface elevation. Between 2011 and 2020, Greenland's ablation zone thinned on average by 1.4 ± 0.4 m each summer and thickened by 0.9 ± 0.4 m each winter. By adjusting for the steady-state divergence of ice, we estimate that runoff was 357 ± 58 Gt/yr on average - in close agreement with regional climate model simulations (root mean square difference of 47 to 60 Gt/yr). As well as being 21 % higher between 2011 and 2020 than over the preceding three decades, runoff is now also 60 % more variable from year-to-year as a consequence of large-scale fluctuations in atmospheric circulation. Because this variability is not captured in global climate model simulations, our satellite record of runoff should help to refine them and improve confidence in their projections.

Trends in Antarctic Ice Sheet Elevation and Mass.

Fluctuations in Antarctic Ice Sheet elevation and mass occur over a variety of time scales, owing to changes in snowfall and ice flow. Here we disentangle these signals by combining 25 years of satellite radar altimeter observations and a regional climate model. From these measurements, patterns of change that are strongly associated with glaciological events emerge. While the majority of the ice sheet has remained stable, 24% of West Antarctica is now in a state of dynamical imbalance. Thinning of the Pine Island and Thwaites glacier basins reaches 122 m in places, and their rates of ice loss are now five times greater than at the start of our survey. By partitioning elevation changes into areas of snow and ice variability, we estimate that East and West Antarctica have contributed -1.1 ± 0.4 and +5.7 ± 0.8 mm to global sea level between 1992 and 2017.

A reconciled estimate of ice-sheet mass balance.

We combined an ensemble of satellite altimetry, interferometry, and gravimetry data sets using common geographical regions, time intervals, and models of surface mass balance and glacial isostatic adjustment to estimate the mass balance of Earth's polar ice sheets. We find that there is good agreement between different satellite methods--especially in Greenland and West Antarctica--and that combining satellite data sets leads to greater certainty. Between 1992 and 2011, the ice sheets of Greenland, East Antarctica, West Antarctica, and the Antarctic Peninsula changed in mass by -142 ± 49, +14 ± 43, -65 ± 26, and -20 ± 14 gigatonnes year(-1), respectively. Since 1992, the polar ice sheets have contributed, on average, 0.59 ± 0.20 millimeter year(-1) to the rate of global sea-level rise.

Affective picture processing and motivational relevance: arousal and valence effects on ERPs in an oddball task.

There are two dominant theories of affective picture processing; one that attention is more deeply engaged by motivationally relevant stimuli (i.e., stimuli that activate both the appetitive and aversive systems), and two that attention is more deeply engaged by aversive stimuli described as the negativity bias. In order to identify the theory that can best account for affective picture processing, event-related potentials (ERPs) were recorded from 34 participants during a modified oddball paradigm in which levels of stimulus valence, arousal, and motivational relevance were systematically varied. Results were partially consistent with motivated attention models of emotional perception, as P3b amplitude was enhanced in response to highly arousing and motivationally relevant sexual and unpleasant stimuli compared to respective low arousing and less motivationally relevant stimuli. However P3b amplitudes were significantly larger in response to the highly arousing sexual stimuli compared to all other affective stimuli, which is not consistent with either dominant theory. The current study therefore highlights the need for a revised model of affective picture processing and provides a platform for further research investigating the independent effects of sexual arousal on cognitive processing.

Target processing is facilitated by motivationally relevant cues.

The effect that motivationally relevant stimuli have on processes of attentional engagement and disengagement was investigated during two modified peripheral cueing paradigms. Sexual, mutilation, threatening, and neutral stimuli served as peripheral cues in both experiments. Responses were made to target location in Experiment 1 (N=19 female) and target identity in Experiment 2 (N=18 female). As indexed by enhanced target-evoked P1 and P3b component amplitudes, target processing was facilitated by the presentation of sexual and mutilation stimuli in both experiments. This facilitation in response to targets cued by sexual and mutilation stimuli occurred regardless of whether cueing was valid or invalid as demonstrated by the non-significant cue validity x picture-type interaction. As such, the processes of attentional engagement (as inferred by responses to validly cued targets) and attentional disengagement (as inferred by responses to invalidly cued targets) were not differentially affected by the motivational relevance of the preceding cue. These results indicate that in a non-clinical sample, participants can shift attention rapidly to process information following the onset of motivationally relevant stimuli at attended (valid) and unattended (invalid) locations and that target processing is facilitated by the presence of appetitive and aversive cues.

A feasibility and tolerability study of lithium in Alzheimer's disease.

OBJECTIVE: To assess the safety and feasibility of prescribing long term lithium to elderly people with mild to moderate Alzheimer's disease (AD). METHODS: An open label treatment group with low dose lithium for up to 1 year with the Lithium Side Effects Rating Scale as the primary outcome measure. A comparison group matched for cognition and age not receiving lithium therapy. RESULTS: Twenty-two people with AD initiated lithium. Fourteen participants discontinued therapy after a mean of 16 weeks of treatment compared to the 39 weeks for those continuing to take treatment at the end of the study. Three patients discontinued treatment due to possible side effects that abated on ceasing therapy. The reports of side effects on the primary outcome scale did not differ between those discontinuing therapy and those remaining in the study. Two patients died whilst receiving lithium--in neither case was the treatment felt to be related to cause of death. There was no difference in deaths, drop outs or change in MMSE between those receiving lithium and the comparison group. CONCLUSIONS: Lithium treatment in elderly people with AD has relatively few side effects and those that were apparently due to treatment were mild and reversible. Nonetheless discontinuation rates are high. The use of lithium as a potential disease modification therapy in AD should be explored further but is not without problems.

Accomplishing care at home for people with dementia: using observational methodology.

The authors consider the problems and possibilities presented by using unstructured observation in the home setting. The findings of the original study are described elsewhere (Briggs, Askham, Norman, & Redfern 1998; National Health Service [NHS] Executive 1998). In this article, the authors discuss process issues (e.g., gaining and maintaining access to the research setting, disengaging, what can and cannot be observed, and the validity of the data and analysis), drawing on a study of the nature of care as a form of social organization in the homes of people with dementia. They show that observation is not only possible but, when combined with conversational interviewing, essential for understanding the processes of caring and what it means to live with dementia.