Cortical excitability correlates with the event-related desynchronization during brain-computer interface control

Objective Brain-computer interfaces (BCIs) based on motor control have been suggested as tools for stroke rehabilitation. Some initial successes have been achieved with this approach, however the mechanism by which they work is not yet fully understood. One possible part of this mechanism is a, previously suggested, relationship between the strength of the event-related desynchronization (ERD), a neural correlate of motor imagination and execution, and corticospinal excitability. Additionally, a key component of BCIs used in neurorehabilitation is the provision of visual feedback to positively reinforce attempts at motor control. However, the ability of visual feedback of the ERD to modulate the activity in the motor system has not been fully explored. Approach We investigate these relationships via transcranial magnetic stimulation delivered at different moments in the ongoing ERD related to hand contraction and relaxation during BCI control of a visual feedback bar. Main results We identify a significant relationship between ERD strength and corticospinal excitability, and find that our visual feedback does not affect corticospinal excitability. Significance Our results imply that efforts to promote functional recovery in stroke by targeting increases in corticospinal excitability may be aided by accounting for the time course of the ERD

Increased adaptability to rapid environmental change can more than make up for the two-fold cost of males

The famous "two-fold cost of sex" is really the cost of anisogamy -- why should females mate with males who do not contribute resources to offspring, rather than isogamous partners who contribute equally? In typical anisogamous populations, a single very fit male can have an enormous number of offspring, far larger than is possible for any female or isogamous individual. If the sexual selection on males aligns with the natural selection on females, anisogamy thus allows much more rapid adaptation via super-successful males. We show via simulations that this effect can be sufficient to overcome the two-fold cost and maintain anisogamy against isogamy in populations adapting to environmental change. The key quantity is the variance in male fitness -- if this exceeds what is possible in an isogamous population, anisogamous populations can win out in direct competition by adapting faster.Comment: 15 pages, 3 figure

Software Sustainability: The Modern Tower of Babel

<p>The aim of this paper is to explore the emerging definitions of software sustainability from the field of software engineering in order to contribute to the question, what is software sustainability?</p

Emergent scale-free networks

Many complex systems--from social and communication networks to biological networks and the Internet--are thought to exhibit scale-free structure. However, prevailing explanations rely on the constant addition of new nodes, an assumption that fails dramatically in some real-world settings. Here, we propose a model in which nodes are allowed to die, and their connections rearrange under a mixture of preferential and random attachment. With these simple dynamics, we show that networks self-organize towards scale-free structure, with a power-law exponent $\gamma = 1 + \frac{1}{p}$ that depends only on the proportion $p$ of preferential (rather than random) attachment. Applying our model to several real networks, we infer $p$ directly from data, and predict the relationship between network size and degree heterogeneity. Together, these results establish that realistic scale-free structure can emerge naturally in networks of constant size and density, with broad implications for the structure and function of complex systems.Comment: 24 pages, 5 figure

Robust future changes in temperature variability under greenhouse gas forcing and the relationship with thermal advection

Recent temperature extremes have highlighted the importance of assessing projected changes in the variability of temperature as well as the mean. A large fraction of present day temperature variance is associated with thermal advection, as anomalous winds blow across the land-sea temperature contrast for instance. Models project robust heterogeneity in the 21st century warming pattern under greenhouse gas forcing, resulting in land-sea temperature contrasts increasing in summer and decreasing in winter, and the pole-to-equator temperature gradient weakening in winter. In this study, future monthly variability changes in the 17 member ensemble ESSENCE are assessed. In winter, variability in midlatitudes decreases while in very high latitudes and the tropics it increases. In summer, variability increases over most land areas and in the tropics, with decreasing variability in high latitude oceans. Multiple regression analysis is used to determine the contributions to variability changes from changing temperature gradients and circulation patterns. Thermal advection is found to be of particular importance in the northern hemisphere winter midlatitudes, where the change in mean state temperature gradients alone could account for over half the projected changes. Changes in thermal advection are also found to be important in summer in Europe and coastal areas, although less so than in winter. Comparison with CMIP5 data shows that the midlatitude changes in variability are robust across large regions, particularly high northern latitudes in winter and mid northern latitudes in summer

Text messaging to help women with overweight or obesity lose weight after childbirth:the intervention adaptation and SMS feasibility RCT

Background There is a need to develop weight management interventions that fit seamlessly into the busy lives of women during the postpartum period. Objective The objective was to develop and pilot-test an evidence- and theory-based intervention, delivered by short message service, which supported weight loss and weight loss maintenance in the postpartum period. Design Stage 1 involved the development of a library of short message service messages to support weight loss and weight loss maintenance, with personal and public involvement, focusing on diet and physical activity with embedded behaviour change techniques, and the programming of a short message service platform to allow fully automated intervention delivery. Stage 2 comprised a 12-month, single-centre, two-arm, pilot, randomised controlled trial with an active control. Setting This study was set in Northern Ireland; women were recruited via community-based approaches. Participants A total of 100 women with overweight or obesity who had given birth in the previous 24 months were recruited. Interventions The intervention group received an automated short message service intervention about weight loss and weight loss maintenance for 12 months. The active control group received automated short message service messages about child health and development for 12 months. Main outcome measures The main outcomes measured were the feasibility of recruitment and retention, acceptability of the intervention and trial procedures, and evidence of positive indicative effects on weight. Weight, waist circumference and blood pressure were measured by the researchers; participants completed a questionnaire booklet and wore a sealed pedometer for 7 days at baseline, 3, 6, 9 and 12 months. Outcome assessments were collected during home visits and women received a voucher on completion of each of the assessments. Qualitative interviews were conducted with women at 3 and 12 months, to gather feedback on the intervention and active control and the study procedures. Quantitative and qualitative data were used to inform the process evaluation and to assess fidelity, acceptability, dose, reach, recruitment, retention, contamination and context. Results The recruitment target of 100 participants was achieved (intervention, n = 51; control, n = 49); the mean age was 32.5 years (standard deviation 4.3 years); 28 (28%) participants had a household income o

2023's Antarctic sea ice extent is the lowest on record

Antarctic sea ice is a vitally important part of the regional and global climate. In 2023, sea ice extent fell to record lows, reaching unprecedented values for both the summer minimum, winter maximum and intervening freeze-up period. Here, we show that the extreme values observed were truly remarkable within the context of the satellite record, despite the challenge of quantifying how rare such an event might be, and discuss some contributing factors. While this could be part of a decline in sea ice associated with human-caused climate change, it is too early to say conclusively if this is the case

The impact of Arctic sea ice change on midlatitude climate

Arctic sea ice loss is a robust feature of observations and of climate model projections. Amplified winter lower tropospheric warming in the Arctic relative to the global mean is associated with this ice loss. Many recent studies have addressed the possible effects of these changes on the midlatitude atmospheric circulation, particularly in the North Atlantic. These studies suggest responses including an equatorward jet shift, a negative annular mode response and changes in Rossby wave behaviour. However, there is disagreement on the magnitude, significance and even sign of these responses. Previous studies have shown the advantages of model hierarchies for understanding the atmosphere. In this thesis, experiments are conducted in HadGAM1 with simplified lower boundary conditions. Two sets of experiments are conducted, one in a zonally symmetric aquaplanet and the other in a configuration with representative northern hemisphere land masses. A wide range of sea ice profiles are imposed. The dominant response to ice removal in an aquaplanet is an equatorward jet shift, consistent with previous work. This response is moderate in magnitude for ice which does not exceed 65◦ latitude, but strongly nonlinear for greater ice extents. The zonal mean response is qualitatively similar in the asymmetric configuration, but the nature of the asymmetric response shows sensitivity to the exact ice edge location. These results have implications for understanding the impact of sea ice anomalies in past as well as present climates. Changes in surface temperature gradients, including from Arctic amplification, could affect midlatitude climate even if circulation changes are small. In particular, changes in thermal advection could alter midlatitude temperature variability and extremes. In this thesis a multiple regression model is used to investigate projected monthly temperature variance changes in a recent single model ensemble. Many robust changes, including reduced winter temperature variance in Europe, are consistent with the effect of changes in the seasonal mean temperature gradient alone