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Planetary cores are the seat of rich and complex fluid dynamics, in which the effects of rotation and magnetic field combine. The equilibria governing the strength of the magnetic field produced by the dynamo effect, the organisation and amplitude of the flow, and those of the density field, remain debated despite remarkable progress made in their numerical simulation. This paper describes an approach based on the explicit consideration of the variation of time scales $\tau $ with spatial scales $\ell $ for the different physical phenomena involved. The $\tau $–$\ell $ diagrams thus constructed constitute a very complete graphic summary of the dynamics of the object under study. We highlight the role of the available convective power in controlling this dynamics, together with the relevant force balance, for which we derive a very telling $\tau $–$\ell $ translation. Several scenarios are constructed and discussed for the Earth’s core, shedding new light on the width of convective columns, and on the force equilibria to be considered. A QG-MAC scenario adapted from [Aubert, 2019] gives a good account of the observations. A diversion to Venus reveals the subtlety and relativity of the notion of “fast rotator”. We discuss scaling laws and their validity domain, and illustrate “path strategies”. A complete toolbox is provided, allowing everyone to construct a $\tau $–$\ell $ diagram of a numerical simulation, a laboratory experiment, a theory, or a natural object.

The heat flux across the core–mantle boundary (CMB) is a fundamental variable for Earth evolution and internal dynamics. Seismic tomography provides access to seismic heterogeneities in the lower mantle, which can be related to present-day thermal heterogeneities. Alternatively, mantle convection models can be used to either infer past CMB heat flux or to produce statistically realistic CMB heat flux patterns in self-consistent models. Mantle dynamics modifies the inertia tensor of the Earth, which implies a rotation of the Earth with respect to its spin axis, a phenomenon called true polar wander (TPW). This rotation must be taken into account to link the dynamics of the mantle to the dynamics of the core. In this study, we explore the impact of TPW on the CMB heat flux over long timescales (∼1 Gyr) using two recently published mantle convection models: one model driven by a plate reconstruction and a second that self-consistently produces a plate-like behaviour. We compute the geoid in both models to correct for TPW. In the plate-driven model, we compute a total geoid and a geoid in which lateral variations of viscosity and density are suppressed above 350 km depth. An alternative to TPW correction is used for the plate-driven model by simply repositioning the model in the original paleomagnetic reference frame of the plate reconstruction. The average TPW rates range between 0.4 and 1.8° Myr -1 , but peaks up to 10° Myr -1 are observed. We find that in the plate-driven mantle convection model used in this study, the maximum inertia axis produced by the model does not show a long-term consistency with the position of the magnetic dipole inferred from paleomagnetism. TPW plays an important role in redistributing the CMB heat flux, notably at short timescales (≤10 Myr). Those rapid variations modify the latitudinal distribution of the CMB heat flux, which is known to affect the stability of the magnetic dipole in geodynamo simulations. A principal component analysis (PCA) is computed to obtain the dominant CMB heat flux pattern in the different cases. These heat flux patterns are representative of the mantle convection cases studied here and can be used as boundary conditions for geodynamo models. [ABSTRACT FROM AUTHOR]

Heat flux across the core-mantle boundary (CMB) is an important variable of Earth's thermal evolution and dynamics. Seismic tomography provides access to seismic heterogeneities in the lower mantle, which can be related to present-day thermal heterogeneities. Alternatively, mantle convection models can be used to either infer past CMB heat flux or to produce statistically realistic CMB heat flux patterns in self-consistent models. Mantle dynamics modifies the inertia tensor of the Earth, which implies a rotation of the Earth with respect to its spin axis, a phenomenon called true polar wander (TPW). This rotation must be taken into account to link the dynamics of the mantle to the dynamics of the core. In this study, we use two recently published mantle convection models to explore the impact of TPW on the CMB heat flux over long timescales (~ 1 Gyr). One of the mantle convection models is driven by a plate reconstruction, while the other self-consistently produces a plate-like behavior. We compute the geoid in both models to correct for TPW. In the plate-driven model, we compute a total geoid and a geoid in which lateral variations of viscosity and temperature are suppressed above 350 km depth. We show that TPW plays an important role in redistributing the CMB heat flux, notably at short time scales (≤ 10 Myr). Those rapid variations modify the latitudinal distribution of the CMB heat flux, which is known to affect the stability of the magnetic dipole in geodynamo simulations. A principal component analysis (PCA) is computed to obtain the dominant CMB heat flux pattern in the different cases. These heat flux patterns can be used as boundary conditions for geodynamo models as representative of the mantle convection cases studied here. We note that the geoids produced by the two models are widely different from each other and from the observed present-day geoid. Work thus still needs to be done to improve the computation of the geoid in mantle convection models related to plate-tectonics. [ABSTRACT FROM AUTHOR]

The core-mantle boundary (CMB) heat flux is an important variable of Earth's thermal evolution and dynamics. Seismic tomography enables access to seismic heterogeneities in the lower mantle, which can be related to present-day thermal heterogeneities. Alternatively, mantle convection models can be used to either infer the past CMB heat flux or to produce statistically realistic CMB heat flux distributions in self-consistent models. Mantle dynamics modifies the inertia tensor of the Earth, which implies a rotation of the Earth with respect to its rotation axis called True Polar Wander (TPW). This rotation has to be taken into account if mantle dynamics is to be linked to core dynamics. In this study, we explore the TPW and the CMB heat flux produced by a self-consistent mantle convection model. The geoid is also computed and investigated in order to determine the driving mechanism of TPW. This model includes continents, dense chemical piles at the bottom of the shell and plate-like behavior, providing the possibility to link TPW and the CMB heat flux with plate tectonics. A principal component analysis (PCA) of the CMB heat flux is computed to obtain the dominant heat flux patterns. The model shows a geoid dominated by upper mantle structures. Subduction zones and continents are correlated with positive geoid anomalies, about 20 times larger than the observed geoid anomalies. Chemical piles are mostly correlated with negative geoid anomalies because of the anti-correlation between the positions of subducting slabs and the piles. TPW thus tends to lock continents and subduction zones close to the equator, while chemical piles are shifted towards higher latitudes. The positive CMB heat flux anomalies are mostly located at low latitudes because of the equatorial slabs. The dominant heat flux patterns obtained by the PCA largely reflect the supercontinent cycle captured by the model, providing CMB heat flux patterns representative of the supercontinent formation and dispersal. [ABSTRACT FROM AUTHOR]

Background: In patients with immune-mediated inflammatory disorders, poor adherence to medication is associated with increased healthcare costs, decreased patient satisfaction, reduced quality of life and unfavorable treatment outcomes. Objective: To determine the impact of different interventions on medication adherence in patients with immune-mediated inflammatory disorders. Design: Systematic review. Data sources: MEDLINE, EMBASE and Cochrane Library. Study eligibility criteria for selecting studies: Included studies were clinical trials and observational studies in adult outpatients treated for psoriasis, Crohn’s disease, ulcerative colitis, rheumatoid arthritis, spondyloarthritis, psoriatic arthritis or multiple sclerosis. Study appraisal and synthesis methods: Intervention approaches were classified into four categories: educational, behavioral, cognitive behavioral, and multicomponent interventions. The risk of bias/study limitations of each study was assessed using the GRADE system. Results: Fifteen studies (14 clinical trials and one observational study) met eligibility criteria and enrolled a total of 1958 patients. Forty percent of the studies (6/15) was conducted in patients with inflammatory bowel disease, half (7/15) in rheumatoid arthritis patients, one in psoriasis patients and one in multiple sclerosis patients. Seven out of 15 interventions were classified as multicomponent, four as educational, two as behavioral and two as cognitive behavioral. Nine studies, of which five were multicomponent interventions, had no serious limitations according to GRADE criteria. Nine out of 15 interventions showed an improvement of adherence: three multicomponent interventions in inflammatory bowel disease; one intervention of each category in rheumatoid arthritis; one multicomponent in psoriasis and one multicomponent in multiple sclerosis. Conclusion: The assessment of interventions designed for increasing medication adherence in IMID is rare in the literature and their methodological quality may be improved in upcoming studies. Nonetheless, multicomponent interventions showed the strongest evidence for promoting adherence in patients with IMID. [ABSTRACT FROM AUTHOR]

The mantle plume hypothesis was proposed thirty years ago by Jason Morgan to explain hotspot volcanoes such as Hawaii. A thermal diapir (or plume) rises from the thermal boundary layer at the base of the mantle and produces a chain of volcanoes as a plate moves on top of it. The idea is very attractive, but direct evidence for actual plumes is weak, and many questions remain unanswered. With the great improvement of seismic imagery in the past ten years, new prospects have arisen. Mantle plumes are expected to be rather narrow, and their detection by seismic techniques requires specific developments as well as dedicated field experiments. Regional travel-time tomography has provided good evidence for plumes in the upper mantle beneath a few hotspots (Yellowstone, Massif Central, Iceland). Beneath Hawaii and Iceland, the plume can be detected in the transition zone because it deflects the seismic discontinuities at 410 and 660 km depths. In the lower mantle, plumes are very difficult to detect, so specific methods have been worked out for this purpose. There are hints of a plume beneath the weak Bowie hotspot, as well as intriguing observations for Hawaii. Beneath Iceland, high-resolution tomography has just revealed a wide and meandering plume-like structure extending from the core-mantle boundary up to the surface. Among the many phenomena that seem to take place in the lowermost mantle (or D″), there are also signs there of the presence of plumes. In this article I review the main results obtained so far from these studies and discuss their implications for plume dynamics. Seismic imaging of mantle plumes is still in its infancy but should soon become a turbulent teenager. [ABSTRACT FROM AUTHOR]

Focuses on the scattering of S waves diffracted at the core-mantle boundary. Observation of amplitudes and waveforms in seismic stations; Analysis of the heterogeneous structures on the diffracted S waves; Application of heterogeneous models in geometry.

Presents a seismological study of the mantle beneath the Bowie hotspot of west of Canada. Revellation of a zone of low seismic velocitites; Delay of 0.15 seconds to the travel time of seismic waves traversing a region approximately 150 kilometers in diameter; Suggestions that a mantle plume is present in the lower mantle with the amplitude of the anomaly implying a temperature contrast of 300 K.

Discusses the relative rotation of the earth's core as compared to the mantle. Description of the inner core; Technique of measuring seismic waves by emitters and receivers to investigate the earth's core; Experiments performed by A. Souriau, Song and Richards, and Vidale et al; Use of the Large Aperture Seismic Array (LASA) in Vidale's study, which made for a higher-resolution technique; Discussion of the findings of Vidale et al.

The contribution of small scale turbulent fluctuations to the induction of a mean magnetic field is investigated in our liquid sodium spherical Couette experiment with an imposed magnetic field. An inversion technique is applied to a large number of measurements at Rm≈100 to obtain radial profiles of the α and β effects and maps of the mean flow. It appears that the small scale turbulent fluctuations can be modeled as a strong contribution to the magnetic diffusivity that is negative in the interior region and positive close to the outer shell. Direct numerical simulations of our experiment support these results. The lowering of the effective magnetic diffusivity by small scale fluctuations implies that turbulence can actually help to achieve self-generation of large scale magnetic fields. [ABSTRACT FROM AUTHOR]

Objective: We aimed to determine patient and rheumatologist factors associated with the safety skills of patients receiving bDMARDs for inflammatory arthritis.Methods: Data were obtained from a descriptive observational cross-sectional nationwide survey performed in 2011 in France. Community- and hospital-based rheumatologists were selected at random. The BioSecure questionnaire was used to collect information on patient safety skills.Results: Of the 677 patients included (mean age 53±13years old; 452 (67%) women, 411 (61%) had RA; 421 (64%) received subcutaneous bDMARDs). Patients had received information about their treatments from their physician 610 (90%), a nurse 207 (31%), by a written booklet 398 (59%), and/or during therapeutic patient education (TPE) sessions 99 (15%). The median BioSecure total score was 72/100 (IQR 60-82). In total, 99 (16.4%) patients had a low skill level; 321 (53.2%) a moderate skill level and 183 (30.3%) a high skill level. On multivariate regression analysis, as compared with high safety skills, low skills were associated with living alone (OR 2.8 [95% CI 1.3⿿6.0]), low educational level (OR 4.3 [2.1⿿8.9]), living in a large city (OR 3.1 [1.2⿿8.2]), being unemployed (OR 3.3 [1.6⿿6.7]) and not receiving written information, participating in TPE sessions or consulting a nurse (OR 3.8 [1.6⿿8.8]). One rheumatologist-related factor was a high number of patients receiving bDMARDs in the practice.Conclusion: We reveal factors associated with low safety skills of patients receiving bDMARDs for inflammatory arthritis, which should be addressed to improve safety skills in this population. [ABSTRACT FROM AUTHOR]

We present a reconstruction of the mean axisymmetric azimuthal and meridional flows in the Derviche Tourneur Sodium installation in Grenoble liquid sodium experiment. The experimental device sets a spherical Couette flow enclosed between two concentric spherical shells where the inner sphere holds a strong dipolar magnet, which acts as a magnetic propeller when rotated. Measurements of the mean velocity, mean induced magnetic field, and mean electric potentials have been acquired inside and outside the fluid for an inner sphere rotation rate of 9 Hz (Rm≃28). Using the induction equation to relate all measured quantities to the mean flow, we develop a nonlinear least-squares inversion procedure to reconstruct a fully coherent solution of the mean velocity field. We also include in our inversion the response of the fluid layer to the nonaxisymmetric time-dependent magnetic field that results from deviations of the imposed magnetic field from an axial dipole. The mean azimuthal velocity field we obtain shows superrotation in an inner region close to the inner sphere where the Lorentz force dominates, which contrasts with an outer geostrophic region governed by the Coriolis force, but where the magnetic torque remains the driver. The meridional circulation is strongly hindered by the presence of both the Lorentz and the Coriolis forces. Nevertheless, it contributes to a significant part of the induced magnetic energy. Our approach sets the scene for evaluating the contribution of velocity and magnetic fluctuations to the mean magnetic field, a key question for dynamo mechanisms. [ABSTRACT FROM AUTHOR]