4,458 research outputs found
Decline of long-range temporal correlations in the human brain during sustained wakefulness
Sleep is crucial for daytime functioning, cognitive performance and general
well-being. These aspects of daily life are known to be impaired after extended
wake, yet, the underlying neuronal correlates have been difficult to identify.
Accumulating evidence suggests that normal functioning of the brain is
characterized by long-range temporal correlations (LRTCs) in cortex, which are
supportive for decision-making and working memory tasks.
Here we assess LRTCs in resting state human EEG data during a 40-hour sleep
deprivation experiment by evaluating the decay in autocorrelation and the
scaling exponent of the detrended fluctuation analysis from EEG amplitude
fluctuations. We find with both measures that LRTCs decline as sleep
deprivation progresses. This decline becomes evident when taking changes in
signal power into appropriate consideration.
Our results demonstrate the importance of sleep to maintain LRTCs in the
human brain. In complex networks, LRTCs naturally emerge in the vicinity of a
critical state. The observation of declining LRTCs during wake thus provides
additional support for our hypothesis that sleep reorganizes cortical networks
towards critical dynamics for optimal functioning
Virginia Berridge and Griffith Edwards â Opium and the People: Opiate Use in Nineteenth-Century England.
Deforestation and Decolonization: Lafcadio Hearnâs French Antillean Writing
Looking outside at my breadfruit tree reminds me how European colonialism shaped Caribbean landscape through the genocide of indigenous peoples and colonization of their lands, followed by the theft, commodification and dispersal of indigenous plants and botanic knowledge. Furthermore, these processes were accompanied by the production and hierarchization of race and the enslavement and exploitation of African and Asian populations. As Elizabeth Deloughrey, Renee Gosson, and George Handley note, âthere is probably no other region in the world that has been more radically altered in terms of human and botanic migration, transplantation and settlement than the Caribbeanâ. Yet, our ability to detect ecoimperialist activities by reading Caribbean landscapes is hampered by âthe ever-expanding and ambitious imaginative symbolismâ through which the colonizers constituted the islands as tropical paradisesâ. As Deloughrey explains, âat the height of the process of altering and damaging island landscapes, tropical islands were interpellated in Edenic terms, removed in space and timeâ and segregated from human agency. This interpellation, still active in todayâs tourism advertisements, naturalizes the altered landscapes, thereby effacing the violent ecological history of the Caribbean plantation economy
Behavioural simulation of biological neuron systems using VHDL and VHDL-AMS
The investigation of neuron structures is an incredibly difficult and complex task that yields relatively low rewards in terms of information from biological forms (either animals or tissue). The structures and connectivity of even the simplest invertebrates are almost impossible to establish with standard laboratory techniques, and even when this is possible it is generally time consuming, complex and expensive. Recent work has shown how a simplified behavioural approach to modelling neurons can allow âvirtualâ experiments to be carried out that map the behaviour of a simulated structure onto a hypothetical biological one, with correlation of behaviour rather than underlying connectivity. The problems with such approaches are numerous. The first is the difficulty of simulating realistic aggregates efficiently, the second is making sense of the results and finally, it would be helpful to have an implementation that could be synthesised to hardware for acceleration. In this paper we present a VHDL implementation of Neuron models that allow large aggregates to be simulated. The models are demonstrated using a system level VHDL and VHDL-AMS model of the C. Elegans locomotory system
Child and family practitioners' understanding of child development: lessons learnt from a small sample of serious case reviews (Research Report DFE-RR110)
Serious and fatal child maltreatment : setting serious case review data in context with other data on violent and maltreatment-related deaths in 2009-10
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