Roughness-induced critical phenomena in a turbulent flow

I present empirical evidence that turbulent flows are closely analogous to critical phenomena, from a reanalysis of friction factor measurements in rough pipes. The data collapse found here corresponds to Widom scaling near critical points, and implies that a full understanding of turbulence requires explicit accounting for boundary roughness

Turbulent Friction in Rough Pipes and the Energy Spectrum of the Phenomenological Theory

The classical experiments on turbulent friction in rough pipes were performed by J. Nikuradse in the 1930's. Seventy years later, they continue to defy theory. Here we model Nikuradse's experiments using the phenomenological theory of Kolmog\'orov, a theory that is widely thought to be applicable only to highly idealized flows. Our results include both the empirical scalings of Blasius and Strickler, and are otherwise in minute qualitative agreement with the experiments; they suggest that the phenomenological theory may be relevant to other flows of practical interest; and they unveil the existence of close ties between two milestones of experimental and theoretical turbulence.Comment: Accepted for publication in PRL; 4 pages, 4 figures; revised versio

Guided Conversations: Findings and Social Impact

This is the final version.European Regional Development Fund (ERDF

Soft X-ray radiation damage in EM-CCDs used for Resonant Inelastic X-ray Scattering

Advancement in synchrotron and free electron laser facilities means that X-ray beams with higher intensity than ever before are being created. The high brilliance of the X-ray beam, as well as the ability to use a range of X-ray energies, means that they can be used in a wide range of applications. One such application is Resonant Inelastic X-ray Scattering (RIXS). RIXS uses the intense and tuneable X-ray beams in order to investigate the electronic structure of materials. The photons are focused onto a sample material and the scattered X-ray beam is diffracted off a high resolution grating to disperse the X-ray energies onto a position sensitive detector. Whilst several factors affect the total system energy resolution, the performance of RIXS experiments can be limited by the spatial resolution of the detector used. Electron-Multiplying CCDs (EM-CCDs) at high gain in combination with centroiding of the photon charge cloud across several detector pixels can lead to sub-pixel spatial resolution of 2–3 μm. X-ray radiation can cause damage to CCDs through ionisation damage resulting in increases in dark current and/or a shift in flat band voltage. Understanding the effect of radiation damage on EM-CCDs is important in order to predict lifetime as well as the change in performance over time. Two CCD-97s were taken to PTB at BESSY II and irradiated with large doses of soft X-rays in order to probe the front and back surfaces of the device. The dark current was shown to decay over time with two different exponential components to it. This paper will discuss the use of EM-CCDs for readout of RIXS spectrometers, and limitations on spatial resolution, together with any limitations on instrument use which may arise from X-ray-induced radiation damage

Jung and Deleuze: Enchanted Openings to the Other: A Philosophical Contribution

This paper draws from resources in the work of Deleuze to critically examine the notion of organicism and holistic relations that appear in historical forerunners that Jung identifies in his work on synchronicity. I interpret evidence in Jung's comments on synchronicity that resonate with Deleuze's interpretation of repetition and time and which challenge any straightforward foundationalist critique of Jung's thought. A contention of the paper is that Jung and Deleuze envisage enchanted openings onto relations which are not constrained by the presupposition of a bounded whole, whether at the level of the macrocosm or the microcosm. Openings to these relations entail the potential for experimental transformation beyond sedentary habits of thought which are blocked by a disenchanting ‘image of thought’ that stands in need of critique. Other examples of enchanted openings in Jung's work are signposted in an effort to counter their marginalisation in some post-Jungian critiques and to signal their potential value from a Deleuzian perspective

Health States of Exception: unsafe non-care and the (inadvertent) production of ‘bare life’ in complex care transitions

This paper draws on the work of Giorgio Agamben to understand how the social organisation of care transitions can reduce people to their 'bare' life thereby making harmful and degrading treatment seemingly legitimate. The findings of a two-year ethnographic study show how some people experience hospital discharge as undignified, inhumane and unsafe process, expressed through their lack of involvement in care planning, delayed discharge from hospital, and poorly coordinated care. Our analysis explores how these experiences stem from the way patients are constituted as 'unknown' and 'ineligible' subjects and, in turn, how professionals become 'not responsible' for their care. In effect the person is reduce to their 'bare' life with limited value within the care system. We suggest the social productio

Chase-away evolution maintains imperfect mimicry in a brood parasite-host system despite rapid evolution of mimics.

We studied a brood parasite-host system (the cuckoo finch Anomalospiza imberbis and its host, the tawny-flanked prinia Prinia subflava) to test (1) the fundamental hypothesis that deceptive mimics evolve to resemble models, selecting in turn for models to evolve away from mimics ('chase-away evolution') and (2) whether such reciprocal evolution maintains imperfect mimicry over time. Over only 50 years, parasites evolved towards hosts and hosts evolved away from parasites, resulting in no detectible increase in mimetic fidelity. Our results reflect rapid adaptive evolution in wild populations of models and mimics and show that chase-away evolution in models can counteract even rapid evolution of mimics, resulting in the persistence of imperfect mimicry. [Abstract copyright: © 2023. The Author(s).

The biosocial subject: sensor technologies and worldly sensibility

Sensor technologies are increasingly part of everyday life, embedded in buildings (movement, sound, temperature) and worn on persons (heart rate, electro-dermal activity, eye tracking). This paper presents a theoretical framework for research on computational sensor data. My approach moves away from theories of agent-centered perceptual synthesis (on behalf of a perceiving organism) and towards a more expansive understanding of the biosocial learning environment. The focus is on sensor technologies that track sensation below the bandwidth of human consciousness. I argue that there is an urgent need to reclaim this kind of biodata as part of an unequally distributed worldly sensibility, and to thereby undermine more narrow reductive readings of such data. The paper explores the biopolitical implications of recasting biodata in terms of trans-individual inhuman forces, while continuing to track the distinctive power of humans

Rethinking the Ambiguities of Abstraction in the Anthropocene

The ambiguities of abstraction were at the heart of critical approaches to the problems of modernity. Abstraction, so fundamental to the modernist episteme, was seen to have alienated humanity from itself and from its entangled relations with its environment, constituting a fundamental rift between the subject and the world. This article analyses how the critique of the modernist episteme has increasingly shifted under the auspices of the Anthropocene. Rather than seeking to overcome the ambiguities of abstraction and return the human to the world, approaches that seek to affirm the Anthropocene have emphasised that modernist thought did not take abstraction far enough. Rather than abstraction being problematic for contemporary thought, abstraction is seen to be a facet of the world in its lively, partial and contingent interaction. This article is organised in three sections. The first section introduces the problematic of abstraction in the Anthropocene, highlighting that critical theory approaches tend to see the Anthropocene within a discourse of modernist critique. The second section draws out the importance of understanding the distinct mode of contemporary affirmation, which rather than seeking to return man to the world, emphasises the impossibility of finding meaning in the world. It is this inverting of critical understandings that enables abstraction to be seen positively rather than problematically. The final section expands on this point to consider how contemporary theoretical approaches articulate the transvaluation of abstraction as the guide to contemporary modes of life