Dragon-kings: mechanisms, statistical methods and empirical evidence

This introductory article presents the special Discussion and Debate volume "From black swans to dragon-kings, is there life beyond power laws?" published in Eur. Phys. J. Special Topics in May 2012. We summarize and put in perspective the contributions into three main themes: (i) mechanisms for dragon-kings, (ii) detection of dragon-kings and statistical tests and (iii) empirical evidence in a large variety of natural and social systems. Overall, we are pleased to witness significant advances both in the introduction and clarification of underlying mechanisms and in the development of novel efficient tests that demonstrate clear evidence for the presence of dragon-kings in many systems. However, this positive view should be balanced by the fact that this remains a very delicate and difficult field, if only due to the scarcity of data as well as the extraordinary important implications with respect to hazard assessment, risk control and predictability.Comment: 20 page

The Betteshanger Summer School: Missing link between biodynamic agriculture and organic farming

Biodynamic agriculture and organic farming have been regarded as having different provenances and having arisen independently. The present account introduces the ‘missing link’ between the two. In 1938 Ehrenfried Pfeiffer published the milestone book on biodynamics: Bio-Dynamic Farming and Gardening. In 1940 Lord Northbourne published Look to the Land, the work that introduced the term ‘organic farming’. In the summer of the intervening year, Pfeiffer travelled from Switzerland to Northbourne’s estate in Kent, UK, and presented for British farmers a nine day course on biodynamics, the Betteshanger Summer School and Conference on Bio-Dynamic Farming, 1-9 July 1939. Pfeiffer was supported by the pre-eminent biodynamic scholar-practitioners, Otto Eckstein and Hans Heinze. Dr Scott Williamson of the Peckham Experiment was the sole British lecturer at the Betteshanger Summer School. For the UK Bio-Dynamic Association, the Betteshanger Summer School was the highlight of the year. Northbourne and Pfeiffer had collaborated on the Farleigh Experiment in 1938, and Northbourne had travelled to Switzerland in January 1939 to arrange Pfeiffer’s visit. War broke out less than eight weeks after the Betteshanger Summer School. Northbourne’s manifesto on organic agriculture, Look to the Land, was published in May of the following year. The book took the Steinerian and biodynamic view of ‘the farm as an organism’ as its central tenet and adopted it as the nominative motif for ‘organic’ farming. The book offered to the Anglophone world an account that was secular and distanced from any Anthroposophic or Germanic roots. Subsequently, Northbourne sought to bring Pfeiffer to the UK but Pfeiffer’s next and final visit was in 1950. The Betteshanger Summer School and Conference on biodynamics has been otherwise unreported. As this account demonstrates, Betteshanger was a stepping stone from biodynamics to organics. Northbourne sponsored Pfeiffer’s visit and the Betteshanger biodynamics conference in 1939, and the following year he introduced his term ‘organic farming’ and its philosophy in his book Look to the Land

The Pioneers of Biodynamics in Great Britain: From Anthroposophic Farming to Organic Agriculture (1924-1940)

Organic agriculture is the direct descendent of biodynamic agriculture; and biodynamic agriculture is the child of Dr Rudolf Steiner’s Agriculture Course presented at Koberwitz (now Kobierzyce, Poland) in 1924. Rudolf Steiner founded the Experimental Circle of Anthroposophic Farmers and Gardeners towards the end of that course. The task of the Experimental Circle was to test Steiner’s ‘hints’ for a new and sustainable agriculture, to find out what works, to publish the results, and to tell the world. Ehrenfried Pfeiffer published his book Bio-Dynamic Farming and Gardening in 1938, thereby fulfilling Steiner’s directive. Two years later, from Steiner’s characterisation of ‘the farm as an organism’, the British biodynamic farmer Lord Northbourne coined the term ‘organic farming’ and published his manifesto of organic agriculture, Look to the Land (1940). In the gestational period of biodynamics, 1924-1938, 43 individual Britons joined the Experimental Circle. Each received a copy of the Agriculture Course. Copies were numbered individually and inscribed with the name of the recipient. These 43 members were the pioneers of biodynamics and organics in Britain, and finally their names and locations are revealed. Of the 43 individuals, 11 received their Agricultural Course in German, 27 in English, and five received copies in both German and English; one couple shared a single copy. Of the 50 Agriculture Course copies supplied to Experimental Circle members in Britain, 17 copies were in German, while 33 were in English. The membership of the Experimental Circle comprised both men (n=21) and women (n=22). Members were domiciled in England (n=39), Scotland (n=3) and Wales (n=1) (Dr Lili Kolisko received her Agriculture Course in Stuttgart, Germany, migrated to England in 1936, and is tallied here as ‘England’). The revelation of the earliest pioneers of biodynamics, and thus organics, in Britain provides 43 starting points for further research

Cultivating Systems Leadership in Cross-Sector Partnerships: Lessons from the Linked Learning Regional Hubs of Excellence

Investments in the social sector have become increasingly complex, with many foundations shifting from supports for single organizations toward more systemic strategies focused on improving outcomes for entire communities. As a result, the field has become awash in regional, or place-based, investments that rely on cross-sector partnerships and networks to drive change. These efforts require coordination among stakeholders across all levels of the practice and policy continuum – from direct service providers, to nonprofit intermediaries, funders, advocacy organizations, and policymakers.It is in this context, and in the spirit of continuous learning, that The James Irvine Foundation's Linked Learning Regional Hubs of Excellence investment serves as a systems change experiment, offering insights and critical lessons that can inform others undertaking similar work. The aim of this Issue Brief – authored by Equal Measure and Harder+Company – is to contribute to field dialogue and learning about the role of leadership in complex systems change strategies, particularly those focused on producing equitable impacts in college and career readiness.Equal Measure and Harder+Company serve as the evaluators of The James Irvine Foundation's Linked Learning Regional Hubs of Excellence. They work in partnership with Jobs for the Future, the intermediary and technical assistance provider for this initiative

L\'evy flights on a comb and the plasma staircase

We formulate the problem of confined L\'evy flight on a comb. The comb represents a sawtooth-like potential field $V(x)$, with the asymmetric teeth favoring net transport in a preferred direction. The shape effect is modeled as a power-law dependence $V(x) \propto |\Delta x|^n$ within the sawtooth period, followed by an abrupt drop-off to zero, after which the initial power-law dependence is reset. It is found that the L\'evy flights will be confined in the sense of generalized central limit theorem if (i) the spacing between the teeth is sufficiently broad, and (ii) $n > 4-\mu$, where $\mu$ is the fractal dimension of the flights. In particular, for the Cauchy flights ($\mu = 1$), $n>3$. The study is motivated by recent observations of localization-delocalization of transport avalanches in banded flows in the Tore Supra tokamak and is intended to devise a theory basis to explain the observed phenomenology.Comment: 13 pages; 3 figures; accepted for publication in Physical Review

Self-Organized Supercriticality and Oscillations in Networks of Stochastic Spiking Neurons

Networks of stochastic spiking neurons are interesting models in the area of Theoretical Neuroscience, presenting both continuous and discontinuous phase transitions. Here we study fully connected networks analytically, numerically and by computational simulations. The neurons have dynamic gains that enable the network to converge to a stationary slightly supercritical state (self-organized supercriticality or SOSC) in the presence of the continuous transition. We show that SOSC, which presents power laws for neuronal avalanches plus some large events, is robust as a function of the main parameter of the neuronal gain dynamics. We discuss the possible applications of the idea of SOSC to biological phenomena like epilepsy and dragon king avalanches. We also find that neuronal gains can produce collective oscillations that coexists with neuronal avalanches, with frequencies compatible with characteristic brain rhythms.Comment: 16 pages, 16 figures divided into 7 figures in the articl