A longitudinal analysis of the decision to drop out of post-compulsory education

In this paper we analyse the magnitude, timing, determinants and outcomes of dropping out of post-compulsory education over the period 1985-94. We use data from the Youth Cohort Surveys for England and Wales to estimate non-parametric single and competing risks duration models allowing for the effects of unobserved heterogeneity and time varying covariates. By the mid-1990s approximately 1 in 10 young people dropped out of post-compulsory education, especially in April and July. Dropouts were more likely to get jobs rather than become unemployed and the most important predictor of the likelihood of dropping out was prior attainment.

The effects of marine eukaryote evolution on phosphorus, carbon and oxygen cycling across the Proterozoic–Phanerozoic transition

This is the final version of the article. Available from Portland Press via the DOI in this record.A ‘Neoproterozoic oxygenation event’ is widely invoked as a causal factor in animal evolution, and often attributed to abiotic causes such as post-glacial pulses of phosphorus weathering. However, recent evidence suggests a series of transient ocean oxygenation events ∼660–520 Ma, which do not fit the simple model of a monotonic rise in atmospheric oxygen (pO2). Hence, we consider mechanisms by which the evolution of marine eukaryotes, coupled with biogeochemical and ecological feedbacks, potentially between alternate stable states, could have caused changes in ocean carbon cycling and redox state, phosphorus cycling and atmospheric pO2. We argue that the late Tonian ocean ∼750 Ma was dominated by rapid microbial cycling of dissolved organic matter (DOM) with elevated nutrient (P) levels due to inefficient removal of organic matter to sediments. We suggest the abrupt onset of the eukaryotic algal biomarker record ∼660–640 Ma was linked to an escalation of protozoan predation, which created a ‘biological pump’ of sinking particulate organic matter (POM). The resultant transfer of organic carbon (Corg) and phosphorus to sediments was strengthened by subsequent eukaryotic innovations, including the advent of sessile benthic animals and mobile burrowing animals. Thus, each phase of eukaryote evolution tended to lower P levels and oxygenate the ocean on ∼104 year timescales, but by decreasing Corg/P burial ratios, tended to lower atmospheric pO2 and deoxygenate the ocean again on ∼106 year timescales. This can help explain the transient nature and ∼106 year duration of oceanic oxygenation events through the Cryogenian–Ediacaran–CambrianThis work was supported by the NERC-NSFC programme ‘Biosphere Evolution, Transitions and Resilience’ through grant NE/P013651/1

The Mid-Pleistocene Transition induced by delayed feedback and bistability

The Mid-Pleistocene Transition, the shift from 41 kyr to 100 kyr glacial-interglacial cycles that occurred roughly 1 Myr ago, is often considered as a change in internal climate dynamics. Here we revisit the model of Quaternary climate dynamics that was proposed by Saltzman and Maasch (1988). We show that it is quantitatively similar to a scalar equation for the ice dynamics only when combining the remaining components into a single delayed feedback term. The delay is the sum of the internal times scales of ocean transport and ice sheet dynamics, which is on the order of 10 kyr. We find that, in the absence of astronomical forcing, the delayed feedback leads to bistable behaviour, where stable large-amplitude oscillations of ice volume and an equilibrium coexist over a large range of values for the delay. We then apply astronomical forcing. We perform a systematic study to show how the system response depends on the forcing amplitude. We find that over a wide range of forcing amplitudes the forcing leads to a switch from small-scale oscillations of 41 kyr to large-amplitude oscillations of roughly 100 kyr without any change of other parameters. The transition in the forced model consistently occurs near the time of the Mid-Pleistocene Transition as observed in data records. This provides evidence that the MPT could have been primarily a forcing-induced switch between attractors of the internal dynamics. Small additional random disturbances make the forcing-induced transition near 800 kyr BP even more robust. We also find that the forced system forgets its initial history during the small-scale oscillations, in particular, nearby initial conditions converge prior to transitioning. In contrast to this, in the regime of large-amplitude oscillations, the oscillation phase is very sensitive to random perturbations, which has a strong effect on the timing of the deglaciation events

Sketching the contours of state authenticity

We outline a program of research in which we examined state authenticity, the sense of being one’s true self. In particular, we describe its phenomenology (what it feels like to be experience authenticity), its correlates(e.g.,emotions,needs),itsnomologicalnetwork(e.g.,real-idealselfoverlap,publicandprivate self-consciousness), its cultural parameters (Easter and Western culture), its precursors or determinants (congruency, positivity, and hedonism), and its psychological health implications. We conclude by arguing that state authenticity deserves its own conceptual status, distinct from trait authenticity, and by setting an agenda for future research

Life on Earth is hard to spot

This is the final version. Available on open access from SAGE Publications via the DOI in this record.  The triumph of the Gaia hypothesis was to spot the extraordinary influence of Life on the Earth. ‘Life’ is the clade including all extant living beings, as distinct from ‘life’ the class of properties common to all living beings. ‘Gaia’ is Life plus its effects on habitability. Life’s influence on the Earth was hard to spot for several reasons: biologists missed it because they focused on life not Life; climatologists missed it because Life is hard to see in the Earth’s energy balance; Earth system scientists opted instead for abiotic or human-centred approaches to the Earth system; Scientists in general were repelled by teleological arguments that Life acts to maintain habitable conditions. Instead, we reason from organisms’ metabolisms outwards, showing how Life’s coupling to its environment has led to profound effects on Earth’s habitability. Recognising Life’s impact on Earth and learning from it could be critical to understanding and successfully navigating the Anthropocene.Zentrum fur Kunst und Medien, Karlsruh

State authenticity

State authenticity is the sense that one is currently in alignment with one’s true or real self. We discuss state authenticity as seen by independent raters, describe its phenomenology, outline its triggers, consider its well-being and behavioral implications, and sketch out a cross-disciplinary research agenda

Early warning signals of tipping points in periodically forced systems

This is the final version of the article. Available from the European Geosciences Union via the DOI in this record.The prospect of finding generic early warning signals of an approaching tipping point in a complex system has generated much interest recently. Existing methods are predicated on a separation of timescales between the system studied and its forcing. However, many systems, including several candidate tipping elements in the climate system, are forced periodically at a timescale comparable to their internal dynamics. Here we use alternative early warning signals of tipping points due to local bifurcations in systems subjected to periodic forcing whose timescale is similar to the period of the forcing. These systems are not in, or close to, a fixed point. Instead their steady state is described by a periodic attractor. For these systems, phase lag and amplification of the system response can provide early warning signals, based on a linear dynamics approximation. Furthermore, the Fourier spectrum of the system's time series reveals harmonics of the forcing period in the system response whose amplitude is related to how nonlinear the system's response is becoming with nonlinear effects becoming more prominent closer to a bifurcation. We apply these indicators as well as a return map analysis to a simple conceptual system and satellite observations of Arctic sea ice area, the latter conjectured to have a bifurcation type tipping point. We find no detectable signal of the Arctic sea ice approaching a local bifurcation.The research leading to these results has received funding from the European Union Seventh Framework Programme FP7/2007-2013 under grant agreement no. 603864 (HELIX). We are grateful to Peter Ashwin, Peter Cox, Michel Crucifix, Vasilis Dakos, Henk Dijkstra, Jan Sieber, Marten Scheffer and Appy Sluijs for the fruitful discussions over beers and balls

Benefits of federal community pastures on the prairies

Non-Peer ReviewedIn the wake of widespread soil erosion, during the 1930s, the federal governments passed the Prairie Farm Rehabilitation Administration (PFRA) act, establishing the agency, and through it a system of community pastures in the three prairie provinces. At present, PFRA operates 87 such pastures. The major motivation for this program was to reduce soil erosion through some careful land management practices, thereby enabling them to be a source of summer pasture for cattle grazing. This was seen as fostering greater economic security, stability and diversification in the region. Over time, many other uses of community pastures have emerged. Although grazing and breeding function has remained prominent, many other uses have become important enough so as not be totally ignored. Some of the notable uses include: wildlife and waterfowl habitats, recreational activity, preservation of biodiversity, preservation of fragile ecosystems, conservation of heritage sites, research activity, among others. In order to determine these uses, a survey of PFRA community pastures was undertaken during the summer of 2000. The results of this survey indicate that although grazing and breeding activities are still the major economic activities on these community pastures, the Canadian and the Prairie society benefits from these pastures in a significant manner. This study suggests that the PFRA community pastures are more than a place for farmers to leave their cattle for the summer period; they provide several benefits to local communities, and other members of the society through ecosystem functions, and other use and non-use related activities

Highly compressed water structure observed in a perchlorate aqueous solution

The discovery by the Phoenix Lander of calcium and magnesium perchlorates in Martian soil samples has fueled much speculation that flows of perchlorate brines might be the cause of the observed channeling and weathering in the surface. Here, we study the structure of a mimetic of Martian water, magnesium perchlorate aqueous solution at its eutectic composition, using neutron diffraction in combination with hydrogen isotope labeling and empirical potential structure refinement. We find that the tetrahedral structure of water is heavily perturbed, the effect being equivalent to pressurizing pure water to pressures of order 2 GPa or more. The Mg2+ and ClO4− ions appear charge-ordered, confining the water on length scales of order 9 Å, preventing ice formation at low temperature. This may explain the low evaporation rates and high deliquescence of these salt solutions, which are essential for stability within the low relative humidity environment of the Martian atmosphere

Abrupt Climate Change in an Oscillating World.

This is the final version of the article. Available from Nature Publishing Group via the DOI in this record.The notion that small changes can have large consequences in the climate or ecosystems has become popular as the concept of tipping points. Typically, tipping points are thought to arise from a loss of stability of an equilibrium when external conditions are slowly varied. However, this appealingly simple view puts us on the wrong foot for understanding a range of abrupt transitions in the climate or ecosystems because complex environmental systems are never in equilibrium. In particular, they are forced by diurnal variations, the seasons, Milankovitch cycles and internal climate oscillations. Here we show how abrupt and sometimes even irreversible change may be evoked by even small shifts in the amplitude or time scale of such environmental oscillations. By using model simulations and reconciling evidence from previous studies we illustrate how these phenomena can be relevant for ecosystems and elements of the climate system including terrestrial ecosystems, Arctic sea ice and monsoons. Although the systems we address are very different and span a broad range of time scales, the phenomena can be understood in a common framework that can help clarify and unify the interpretation of abrupt shifts in the Earth system.This work was carried out under the program of the Netherlands Earth System Science Centre (NESSC), financially supported by the Ministry of Education, Culture and Science (OCW). We are grateful to Chris Huntingford for his constructive comments that helped us to improve the manuscript. We would also like to acknowledge Michel Crucifix, Henk Dijkstra, and Peter Cox for their helpful comments. S.B. is eternally grateful to Nina Engelhardt and the University of Edinburgh for the inspiring working conditions