Scaling and energy transfer in rotating turbulence

The inertial-range properties of quasi-stationary hydrodynamic turbulence under solid-body rotation are studied via high-resolution direct numerical simulations. For strong rotation the nonlinear energy cascade exhibits depletion and a pronounced anisotropy with the energy flux proceeding mainly perpendicularly to the rotation axis. This corresponds to a transition towards a quasi-two-dimensional flow similar to a linear Taylor-Proudman state. In contrast to the energy spectrum along the rotation axis which does not scale self-similarly, the perpendicular spectrum displays an inertial range with $k^{-2}_\perp$-behavior. A new phenomenology gives a rationale for the observations. The scaling exponents $\zeta_p$ of structure functions up to order $p=8$ measured perpendicular to the rotation axis indicate reduced intermittency with increasing rotation rate. The proposed phenomenology is consistent with the inferred asymptotic non-intermittent behavior $\zeta_p=p/2$.Comment: to be published in Europhysics Letters (www.epletters.net), minor changes to match version in prin

A scaling theory of 3D spinodal turbulence

A new scaling theory for spinodal decomposition in the inertial hydrodynamic regime is presented. The scaling involves three relevant length scales, the domain size, the Taylor microscale and the Kolmogorov dissipation scale. This allows for the presence of an inertial "energy cascade", familiar from theories of turbulence, and improves on earlier scaling treatments based on a single length: these, it is shown, cannot be reconciled with energy conservation. The new theory reconciles the t^{2/3} scaling of the domain size, predicted by simple scaling, with the physical expectation of a saturating Reynolds number at late times.Comment: 5 pages, no figures, revised version submitted to Phys Rev E Rapp Comm. Minor changes and clarification

On two-dimensionalization of three-dimensional turbulence in shell models

Applying a modified version of the Gledzer-Ohkitani-Yamada (GOY) shell model, the signatures of so-called two-dimensionalization effect of three-dimensional incompressible, homogeneous, isotropic fully developed unforced turbulence have been studied and reproduced. Within the framework of shell models we have obtained the following results: (i) progressive steepening of the energy spectrum with increased strength of the rotation, and, (ii) depletion in the energy flux of the forward forward cascade, sometimes leading to an inverse cascade. The presence of extended self-similarity and self-similar PDFs for longitudinal velocity differences are also presented for the rotating 3D turbulence case

A high-frequency, long-term data set of hydrology and sediment yield: the alpine badland catchments of Draix-Bléone Observatory

Draix-Bléone critical zone observatory was created in 1983 to study erosion processes in a mountainous badland region of the French Southern Alps. Six catchments of varying size (0.001 to 22 km2) and vegetation cover are equipped to measure water and sediment fluxes, both as bedload and suspended load. This paper presents the core dataset of the observatory, including rainfall and meteorology, high-frequency discharge and suspended-sediment concentration, and event-scale bedload volumes. The longest records span almost 40 years. Measurement and data-processing methods are presented, as well as data quality assessment procedures and examples of results. All the data presented in this paper are available on the open repository https://doi.org/10.17180/obs.draix (Draix-Bleone Observatory, 2015), and a 5-year snapshot is available for review at https://doi.org/10.57745/BEYQFQ (Klotz et al., 2023).</p

Road users rarely use explicit communication when interacting in today’s traffic: Implications for Automated Vehicles

To be successful, automated vehicles (AVs) need to be able to manoeuvre in mixed traffic in a way that will be accepted by road users, and maximises traffic safety and efficiency. A likely prerequisite for this success is for AVs to be able to communicate effectively with other road users in a complex traffic environment. The current study, conducted as part of the European project interACT, investigates the communication strategies used by drivers and pedestrians while crossing the road at six observed locations, across three European countries. In total, 701 road user interactions were observed and annotated, using an observation protocol developed for this purpose. The observation protocols identified 20 event categories, observed from the approaching vehicles/drivers and pedestrians. These included information about movement, looking behaviour, hand gestures, and signals used, as well as some demographic data. These observations illustrated that explicit communication techniques, such as honking, flashing headlights by drivers, or hand gestures by drivers and pedestrians, rarely occurred. This observation was consistent across sites. In addition, a follow-on questionnaire, administered to a sub-set of the observed pedestrians after crossing the road, found that when contemplating a crossing, pedestrians were more likely to use vehicle-based behaviour, rather than communication cues from the driver. Overall, the findings suggest that vehicle-based movement information such as yielding cues are more likely to be used by pedestrians while crossing the road, compared to explicit communication cues from drivers, although some cultural differences were observed. The implications of these findings are discussed with respect to design of suitable external interfaces and communication of intent by future automated vehicles

BMC Public Health

BACKGROUND: Connected health devices and applications (referred to hereafter as "SDApps" - Smart devices and applications) are being portrayed as a new way for prevention, with the promise of accessibility, effectiveness and personalization. Many effectiveness evaluations (experimental designs) with strong internal validity exist. While effectiveness does appear to vary, the mechanisms used by these devices have not yet been thoroughly investigated. This article seeks to unpack this black box, and describes the process of elaboration of an intervention theory for healthy eating and physical activity SDApps. It includes a set of requirements relative to their impact on social health inequalities. METHODS: To build this theory, we drew on theory-driven approaches and in particular on the theory of change (ToC) method. To this end, we developed a cumulative and iterative process combining scientific data from the literature with knowledge from experts (researchers and practitioners) and from patients or users. It was a 3-step process, as follows: 1 - identifying the evidence base; 2 - developing the theory through design intervention and creating realistic expectations, including in our case specific work on social health inequalities (SHIs); 3 - modeling process and outcome. RESULTS: We produced an evidence-based theory according to the ToC model, based on scientific evidence and knowledge from experts and users. It sets out a causal pathway leveraging 11 key mechanisms - theoretical domains - with which 50 behavior change techniques can be used towards 3 ultimate goals: Capacity, Opportunity, Motivation - Behavior (COM-B). Furthermore, the theory specifically integrates requirements relative to the impact on SHIs. CONCLUSIONS: This theory is an aid to SDAapp design and evaluation and it can be used to consider the question of the possible impact of SDApps on the increase in inequalities. Firstly, it enables developers to adopt a more overarching and thorough approach to supporting behavior change, and secondly it encourages comprehensive and contributive evaluations of existing SDApps. Lastly, it allows health inequalities to be fully considered

CDK5 Is Essential for Soluble Amyloid β-Induced Degradation of GKAP and Remodeling of the Synaptic Actin Cytoskeleton

The early stages of Alzheimer's disease are marked by synaptic dysfunction and loss. This process results from the disassembly and degradation of synaptic components, in particular of scaffolding proteins that compose the post-synaptic density (PSD), namely PSD95, Homer and Shank. Here we investigated in rat frontal cortex dissociated culture the mechanisms involved in the downregulation of GKAP (SAPAP1), which links the PSD95 complex to the Shank complex and cytoskeletal structures within the PSD. We show that Aβ causes the rapid loss of GKAP from synapses through a pathway that critically requires cdk5 activity, and is set in motion by NMDAR activity and Ca2+ influx. We show that GKAP is a direct substrate of cdk5 and that its phosphorylation results in polyubiquitination and proteasomal degradation of GKAP and remodeling (collapse) of the synaptic actin cytoskeleton; the latter effect is abolished in neurons expressing GKAP mutants that are resistant to phosphorylation by cdk5. Given that cdk5 also regulates degradation of PSD95, these results underscore the central position of cdk5 in mediating Aβ-induced PSD disassembly and synapse loss