Circadian regulation of slow waves in human sleep:Topographical aspects

Slow waves (SWs, 0.5-4Hz) in field potentials during sleep reflect synchronized alternations between bursts of action potentials and periods of membrane hyperpolarization of cortical neurons. SWs decline during sleep and this is thought to be related to a reduction of synaptic strength in cortical networks and to be central to sleep's role in maintaining brain function. A central assumption in current concepts of sleep function is that SWs during sleep, and associated recovery processes, are independent of circadian rhythmicity. We tested this hypothesis by quantifying all SWs from 12 EEG derivations in 34 participants in whom 231 sleep periods were scheduled across the circadian cycle in a 10-day forced-desynchrony protocol which allowed estimation of the separate circadian and sleep-dependent modulation of SWs. Circadian rhythmicity significantly modulated the incidence, amplitude, frequency and the slope of the SWs such that the peaks of the circadian rhythms in these slow-wave parameters were located during the biological day. Topographical analyses demonstrated that the sleep-dependent modulation of SW characteristics was most prominent in frontal brain areas whereas the circadian effect was similar to or greater than the sleep-dependent modulation over the central and posterior brain regions. The data demonstrate that circadian rhythmicity directly modulates characteristics of SWs thought to be related to synaptic plasticity and that this modulation depends on topography. These findings have implications for the understanding of local sleep regulation and conditions such as ageing, depression, and neurodegeneration which are associated with changes in SWs, neural plasticity and circadian rhythmicity

Infraslow oscillations in human sleep spindle activity

Background: It has previously been reported that EEG sigma (10-15 Hz) activity during sleep exhibits infraslow oscillations (ISO) with a period of 50 seconds. However, a detailed analysis of the ISO of individually identified sleep spindles is not available. New Method: We investigated basic properties of ISO during baseline sleep of 34 healthy young human participants using a new and established methods. The analyses focused on fast sleep spindle and sigma activity (13-15 Hz) in NREM stage 2 and slow wave sleep (SWS). To describe ISO in sigma activity we analysed power of power of the EEG signal. For the study of ISO in sleep spindle activity we applied a new method in which the EEG signal was reduced to a spindle on/off binary square signal. Its spectral properties were contrasted to that of a square signal wherein the same spindles and also the inter spindle intervals were permutated randomly. This approach was validated using surrogate data with imposed ISO modulation. Results: We confirm the existence of ISO in sigma activity albeit with a frequency below the previously reported 0.02 Hz. These ISO are most prominent in the high sigma band and over the centro-parieto-occipital regions. A similar modulation is present in spindle activity. ISO in sleep spindles are most prominent in the centro-parieto-occipital regions, left hemisphere and second half of the night independent of the number of spindles. Conclusions: The comparison of spectral properties of binary event signals and permutated event signals is effective in detecting slow oscillatory phenomena

The twist-2 Compton operator and its hidden Wandzura-Wilczek and Callan-Gross relations

Power corrections for virtual Compton scattering at leading twist are etermined at operator level. From the complete off-cone representation of the twist-2 Compton operator integral representations for the trace, antisymmetric and symmetric part of that operator are derived. The operator valued invariant functions are written in terms of iterated operators and may lead to interrelations. For matrix elements they go over into relations for generalized parton distributions. -- Reducing to the s-channel relevant part one gets operator pre-forms of the Wandzura-Wilczek and the (target mass corrected) Callan-Gross relations whose structure is exactly the same as known from the case of deep inelastic scattering; taking non-forward matrix elements one reproduces earlier results [B. Geyer, D. Robaschik and J. Eilers, Nucl. Phys. B 704 (2005) 279] for the absorptive part of the virtual Compton amplitude. -- All these relations, obtained without any approximation or using equations of motion, are determined solely by the twist-2 structure of the underlying operator and, therefore, are purely of geometric origin.Comment: 13 pages, Latex 2e, Introduction shortend, Section Prerequisites added, more obvious formulations used, some formulas rewritten as well as added, conclusions extended, references added. Final version as appearing in PR

Tropical extra-tropical thermocline water mass exchanges in the Community Climate Model v.3 Part I: the Atlantic Ocean

The climatological annual mean tropical-extra-tropical pathways of thermocline waters in the Atlantic Ocean are investigated with the NCAR CCSM numerical coupled model. Results from three numerical experiments are analyzed: Two are fully coupled runs with different spatial resolution (T42 and T85) for the atmospheric component. The third numerical experiment is an ocean-only run forced by NCEP winds and fluxes. Results show that the different atmospheric resolutions have a significant impact on the subduction pathways in the Atlantic because of how the wind field is represented. These simulation results also show that the water subducted at the subtropics reaching the EUC is entirely from the South Atlantic. The coupled model ability to simulate the STCs is discussed

To what extent can the experience of outdoor learning contexts prevent permanent school exclusion for older learners? A visual analysis

This is the author accepted manuscript. The final version is available from IATED via the DOI in this record.We report on a one-year project that focused on outdoor learning experiences for learners 12 - 14 years of age in a woodland environment in the UK. We wanted to investigate the ways in which experience in the outdoor environment could potentially mitigate school factors such as practitioner values and attitudes, learner motivation and engagement [1] that contribute to the processes of permanent school exclusion and therefore examine the claim that outdoor learning could provide an ‘alternative’ to using exclusion as a disciplinary sanction [2]. Permanent school exclusion has been rising in the UK since 2014 and the number of permanent exclusions in England in 2016 rose from 6,685 to 7,720 pupils in 2017 [3] and it is particularly prevalent in the age group involved in this project. While some argue that outdoor learning is often evangelised as a panacea for the shortcomings of school environments, particularly for very young learners [4], we draw on the work presented in [5] to make a case for the ways in which outdoor experiences can contribute to the learning needs of older learners at risk of permanent exclusion. We analysed a sample of 102 photographs taken by the project team during the practical sessions in the woodland. We devised a set of categories for coding the images based on our theoretical and pedagogical concerns, and from our reading of empirical literature. Two members of the project team tried out our initial coding categories with the sample in order to check for exhaustiveness and exclusivity, and to try and avoid overlap of codes [6]. Photographs were then coded independently by the four members of the project team using the agreed coding framework. We ask critical questions about the ways in which space, risk, resources, outdoor pedagogies and adult identities can be mobilised to support the learning needs of young people who find school a difficult place to be. In this presentation we will use a selection of photographs to demonstrate that our approach to Visual Content Analysis, drawing on [6] in using a methodologically explicit approach to analysing visual evidence, can produce results that are valid and theoretically ‘interesting’. We interpret the implications of our analysis for educational professionals who want to learn more about preventing permanent exclusion

Inferior Mesenteric Artery Aneurysm: Case Report and Review of the Literature

Aneurysms of the inferior mesenteric artery are very rare. We report a new case associated with aorto-iliac occlusive disease and occlusion of the superior mesenteric artery, as well as review the pertinent literature

A proof of uniqueness of the Gurarii space

We present a short and elementary proof of isometric uniqueness of the Gurarii space.Comment: 6 pages, some improvements incorporate