Risk of pre-term birth as a function of sleep quality and obesity: prospective analysis in a large Prematurity Research Cohort

STUDY OBJECTIVE: To investigate whether poor sleep quality is associated with pre-term birth (PTB) risk, overall and independent of sleep apnea and habitual snoring. METHODS: We used longitudinal data from the Washington University Prematurity Research Cohort to investigate the association between poor sleep quality (defined as a Pittsburgh Sleep Quality Index > 5) and PTB, overall and independent of sleep apnea and snoring (defined by the Berlin questionnaire and prior sleep clinic attendance). Associations were investigated for sleep quality early and throughout pregnancy. Stratified analyses were performed by factors previously shown to modify associations between sleep and PTB (race, pre-pregnancy obesity). RESULTS: Of the 976 eligible participants, 50.1% experienced poor sleep quality early in pregnancy (<20 completed weeks) and 14.2% delivered pre-term (n = 50 without and 89 with poor sleep quality). In multivariable-adjusted analyses, poor sleep quality early in pregnancy was associated with increased PTB risk (hazard ratio [HR] = 1.48, 95% confidence interval [CI] = 1.02-2.14). This association persisted after further adjustment for sleep apnea and snoring (HR = 1.50, 95% CI = 1.02-2.20) and in analyses stratified by race. It varied, however, by pre-pregnancy obesity. Among individuals without obesity, no association was observed between poor sleep and PTB (HR = 1.08, 95% CI = 0.65-1.79), whereas among those with obesity, a positive association was observed (HR = 2.94, 95% CI = 1.52-5.69, p-interaction = .05). This association was limited to individuals with obesity who experienced poor sleep both earlier and later in pregnancy (HR = 3.94, 95% CI = 1.56-9.99). CONCLUSION: Our findings suggest that improving sleep quality early in pregnancy may be important for PTB prevention, particularly among individuals with obesity

Ideal hierarchical secret sharing schemes

Hierarchical secret sharing is among the most natural generalizations of threshold secret sharing, and it has attracted a lot of attention from the invention of secret sharing until nowadays. Several constructions of ideal hierarchical secret sharing schemes have been proposed, but it was not known what access structures admit such a scheme. We solve this problem by providing a natural definition for the family of the hierarchical access structures and, more importantly, by presenting a complete characterization of the ideal hierarchical access structures, that is, the ones admitting an ideal secret sharing scheme. Our characterization deals with the properties of the hierarchically minimal sets of the access structure, which are the minimal qualified sets whose participants are in the lowest possible levels in the hierarchy. By using our characterization, it can be efficiently checked whether any given hierarchical access structure that is defined by its hierarchically minimal sets is ideal. We use the well known connection between ideal secret sharing and matroids and, in particular, the fact that every ideal access structure is a matroid port. In addition, we use recent results on ideal multipartite access structures and the connection between multipartite matroids and integer polymatroids. We prove that every ideal hierarchical access structure is the port of a representable matroid and, more specifically, we prove that every ideal structure in this family admits ideal linear secret sharing schemes over fields of all characteristics. In addition, methods to construct such ideal schemes can be derived from the results in this paper and the aforementioned ones on ideal multipartite secret sharing. Finally, we use our results to find a new proof for the characterization of the ideal weighted threshold access structures that is simpler than the existing one.Peer ReviewedPostprint (author's final draft

How Coupling Determines the Entrainment of Circadian Clocks

Autonomous circadian clocks drive daily rhythms in physiology and behaviour. A network of coupled neurons, the suprachiasmatic nucleus (SCN), serves as a robust self-sustained circadian pacemaker. Synchronization of this timer to the environmental light-dark cycle is crucial for an organism's fitness. In a recent theoretical and experimental study it was shown that coupling governs the entrainment range of circadian clocks. We apply the theory of coupled oscillators to analyse how diffusive and mean-field coupling affects the entrainment range of interacting cells. Mean-field coupling leads to amplitude expansion of weak oscillators and, as a result, reduces the entrainment range. We also show that coupling determines the rigidity of the synchronized SCN network, i.e. the relaxation rates upon perturbation. %(Floquet exponents). Our simulations and analytical calculations using generic oscillator models help to elucidate how coupling determines the entrainment of the SCN. Our theoretical framework helps to interpret experimental data

Glial and light-dependent glutamate metabolism in the suprachiasmatic nuclei

The suprachiasmatic nuclei, the main circadian clock in mammals, are entrained by light through glutamate released from retinal cells. Astrocytes are key players in glutamate metabolism but their role in the entrainment process is unknown. We studied the time dependence of glutamate uptake and glutamine synthetase (GS) activity finding diurnal oscillations in glutamate uptake (high levels during the light phase) and daily and circadian fluctuations in GS activity (higher during the light phase and the subjective day). These results show that glutamate-related astroglial processes exhibit diurnal and circadian variations, which could affect photic entrainment of the circadian system.Fil: Leone, Maria Juliana. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Cronobiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Beaule, C.. Washington University in St. Louis; Estados UnidosFil: Marpegan, Luciano. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Cronobiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Simon, T.. Washington University in St. Louis; Estados UnidosFil: Herzog, E.D.. Washington University in St. Louis; Estados UnidosFil: Golombek, Diego Andrés. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Cronobiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Sustainable forest management of Natura 2000 sites: a case study from a private forest in the Romanian Southern Carpathians

Biodiversity and forest management are analyzed for a 500 ha privately owned forest within the Natura 2000 area ROSCI0122 Muntii Fagaras. Habitat types and indicator species are identified to measure environmental quality. Working towards an integrated approach to conservation, a range of options that will result in sustainable forest management are then considered. For beech forests light heterogeneity emerges as a crucial management target to ensure tree species richness and structural diversity as a basis for saving indicator species such as Morimus funereus, Cucujus cinnaberinus, Bolitophagus reticulatus and Xestobium austriacum. For spruce forests thinning over a broad range of diameters and maintenance of veteran trees would provide habitats for indicator species such asOlisthaerus substriatus. The populations of a number of bird species would be increased by strip-harvesting slopes: species such as Tetrao urogallus, Bonasia bonasia and Ficedula parva prefer forest margins. Steep slopes, and the areas around springs and watercourses, as well as rock faces, should remain unmanaged. Future management should start with a grid-based inventory to create an objective database of forest structure and life. An example is presented for high-elevation spruce forest. The inventory should quantify the variations in diameter, height and volume of trees per unit area. Such data would allow the advanced planning of forest operations. We discuss a wide range of administrative and organizational changes; changes that are needed for the sustainable forest management of the vast close-to-natural forests of the Muntii Fagaras, the maintenance of the Nardusgrasslands and the protection of wetland vegetation around springs and streams in this Natura 2000-area. </span

Interactive effects of landscape context constrain the effectiveness of local agri-environmental management

summary 1. Ecological theory predicts that the effectiveness of local agri-environmental management to enhance species richness at field scales will be the highest at intermediate levels of landscape complexity because of nonlinear effects of landscape context on field-scale diversity. 2. We examined how landscape complexity determined effectiveness of local agri-environmental management in terms of effects on species richness of birds, plants, spiders and bees in 232 extensive and intensive paired fields (112 arable fields and 120 grasslands) from 18 regions located in six European countries. 3. As predicted, landscape complexity enhanced field-scale species richness in a mostly nonlinear (sigmoidal) way, with earlier species richness increases in extensive than in intensive fields along landscape complexity gradients. Length of semi-natural boundaries (for arable fields) and proportion of unfarmed habitat (for grasslands) were the landscape features influencing species richness. 4. The relationships between effectiveness of local management and landscape complexity for all taxa were best described with hump-shaped curves, indicating the highest effectiveness at intermediate landscape complexities. 5. Synthesis and applications. We used models to investigate how and why effects of local management intensity on species richness vary along wide gradients of landscape complexity. We conclude that landscape-scale management options should take priority over local extensification measures within agri-environmental programmes. These programmes should follow a hierarchical multi-scale approach directed to address landscape-scale constraints on local diversity