Scaling laws and phase space analysis of a geomagnetic domino model

The geomagnetic field is among the most striking features of the Earth. By far the most important ingredient of it is generate in the fluid conductive outer core and it is known as the main field. It is characterized by a strong dipolar component as measured on the Earth’s surface. It is well established the fact that the dipolar component has reversed polarity many times, a phenomenon dubbed as dipolar field reversal (DFR). There have been proposed numerous models focused on describing the statistical features of the occurrence of such phenomena. One of them is the domino model, a simple toy model that despite its simplicity displays a very rich dynamic. This model incorporates several aspects of the outer core dynamics like the effect of rotation of Earth, the appearance of convective columns which create their own magnetic field, etc. In this paper we analyse the phase space of parameters of the model and identify several regimes. The two main regimes are the polarity changing one and the regime where the polarity remains the same. Also, we draw some scaling laws that characterize the relationship between the parameters and the mean time between reversals (mtr), the main output of the model.

Gravity Variations and Ground Deformations Resulting from Core Dynamics

Fluid motion within the Earth’s liquid outer core leads to internal mass redistribution. This occurs through the advection of density anomalies within the volume of the liquid core and by deformation of the solid boundaries of the mantle and inner core which feature density contrasts. It also occurs through torques acting on the inner core reorienting its non-spherical shape. These in situ mass changes lead to global gravity variations, and global deformations (inducing additional gravity variations) occur in order to maintain the mechanical equilibrium of the whole Earth. Changes in Earth’s rotation vector (and thus of the global centrifugal potential) induced by core flows are an additional source of global deformations and associated gravity changes originating from core dynamics. Here, we review how each of these different core processes operates, how gravity changes and ground deformations from each could be reconstructed, as well as ways to estimate their amplitudes. Based on our current understanding of core dynamics, we show that, at spherical harmonic degree 2, core processes contribute to gravity variations and ground deformations that are approximately a factor 10 smaller than those observed and caused by dynamical processes within the fluid layers at the Earth’s surface. The larger the harmonic degree, the smaller is the contribution from the core. Extracting a signal of core origin requires the accurate removal of all contributions from surface processes, which remains a challenge. Article Highlights Dynamical processes in Earth's fluid core lead to global gravity variations and surface ground deformations We review how these processes operate, how signals of core origin can be reconstructed and estimate their amplitudes Core signals are a factor 10 smaller than the observed signals; extracting a signal of core origin remains a challenge

Domestic Dharma in Japan

The domestic dimensions of Buddhist practice are a robust and ubiquitous stream, though they have not received much scholarly attention. The category of “domestic Dharma” is a conceptual lens that focuses on everyday lived phenomenon in order for scholars to see Buddhist activity occurring in the privacy of people’s homes. Accessing and understanding the contours of such activities largely depends on ethnographic research. The core dynamics of domestic Dharma engage a field of practices, including ritualization of daily life, mothering as locus of transmission of teachings and practices, rites and objects for protection, healing activities, and interplay with ancestors. Domestic Dharma practices fall under five broad overlapping modes of religious activity: ritualized, scriptural, communicative, materially interactive, and aesthetic. Domestic Dharma practices support people in facing infertility, crippling chronic pain, death through disease, untimely loss of family members, experiencing equanimity, cultivating harmonious relationships, and creating beauty in daily life. Such activities do not fit neatly into abstract categories and institutional frames, for they are complex, concrete, and ever-changing. Women propel domestic Dharma by tending to the physical, emotional, and spiritual needs of themselves and their families. A family’s homemade ritualized activities are efficacious, because they emerge out of immediate situations, idiosyncratic habits, and preferred aesthetics. Domestic Dharma is a vital sphere of harmonious, resilient responses to the vicissitudes of life in which respect, responsibility, and gratitude are cultivated.

THE The Human and the Non-Human in Ze života hmyzu by the Brothers Čapek: Contexts, Scheme, Interpretation

The study „The mutual engagement of human and insect sphere in Čapeks´ most-played drama“ attempts at a contextual perspective on the human and natural spheres of Čapeks celebrated „insect play“ (Ze života hmyzu). Summing up the potential thematic and structural influences on the play (such as L´Oiseau Bleu), the study uncovers the structure of the play (the mise-en-abyme and circular composition) and proves it to be one of the key interpretative tools for its understanding. The other analytical tools are derived from detailed evaluation of the figure of the Tramp (a universal human figure) and of the individual insect groups (types). In the final search for the core dynamics and the message of the play, the influence and legacy of Jean-Henri Fabre is recalled, alongside the authors´ own perspective.

Efficient spherical harmonic transforms on GPU and its use in planetary core dynamics simulations

<p>Most of the new supercomputers now use acceleration technology such as GPUs. They promise much higher performance than traditional CPU-only servers, both in terms of floating point operation throughput and memory bandwidth. Furthermore, the electric consumption is significantly reduced, resulting in lower carbon emissions.<br>However, such high computation speeds can only be achieved if a set of more or less stringent rules are followed with respect to memory access and program flow. As a consequence some algorithms more easily approach peak performance.</p><p>Here, we present the results of an effort to achieve high performance on recent nvidia GPU accelerators for the spherical harmonic transform. The spherical harmonic transform can be split into a Legendre transform (which is compute bound) and a Fourier transform (which is memory bound).<br>By taking advantage of recent algorithmic improvements as well as by tuning the Fourier transform, the can now compute a full forward or backward spherical harmonic transform up to degree 8191 on a single 16GB Volta GPU in less than 0.35 seconds.<br>For lower resolution (up to degree 1023), a single Volta GPU performs a full transform more than 3 times faster than a 48-cores dual socket Skylake Xeon Platinum server.</p><p>We also present results of an ongoing effort to port the (simulation of planetary core fluid and magnetic field dynamics) to GPU-accelerated computers.</p>

Effects of thermal boundary conditions on rotating Rayleigh-Bénard convection with implications on geophysical and astrophysical systems

<p>Rayleigh-Bénard convection (RBC) is a fluid phenomenon that has been studied for over a century because of its utility in simplifying very complex physical systems. Many geophysical and astrophysical systems, including planetary core dynamics and components of weather prediction, are modeled by including rotational forcing in classic RBC. Our understanding of these systems is confined by experimental and numerical limits, as well as theoretical assumptions. </p><p>The role of thermal boundary condition choice on experimental studies of geophysical and astrophysical systems has been often been overlooked, which could account for some lack of agreement between experimental and numerical models as well as the actual flows. The typical thermal boundary conditions prescribed at the top and the bottom of a convection system are fixed temperature conditions, despite few real geophysical systems being bounded with a fixed temperature. A constant heat flux is generally more applicable for real large-scale geophysical systems. However, when this condition is applied in numerical systems, the lack of fixed temperature can cause a temperature drift. In this study, we seek to minimize temperature drifting by applying a fixed temperature condition on one boundary and a fixed thermal flux on the other.</p><p>Experimental boundary conditions are also often assumed to be a fixed temperature. However, the actual condition is determined by the ratio of the height and thermal conductivity of the boundary material to that of the contained fluid, known as the Biot number. The relationship between the Biot number and thermal boundary condition behavior is defined by the Robin, or 'thin-lid', boundary condition such that low Biot number boundaries are essentially fixed thermal flux and high Biot number boundaries are essentially fixed temperature. </p><p>This study seeks to strengthen the link between numerical and experimental models and geophysical flows by investigating the effects of thermal boundary conditions and their relationship to real-world processes. Both fixed temperature and fixed flux boundary conditions are considered. In addition, the Robin boundary condition is studied at a range of Biot numbers spanning from fixed temperature to fixed flux, allowing intermediate conditions to be investigated. Each system is studied at increasingly rapid rotation rates, corresponding to decreasing Ekman numbers as low as Ek=10<sup>-5</sup> Heat transport is analyzed using the Nusselt number, Nu, and the form of the solution is described by the number of convection rolls and time-dependency. Further investigations will analyze Nu and fluid movement within a system with heterogeneous heat flux condition on the  sidewall boundary conditions, which is useful in the study of planetary core dynamics. The results of this study have implications for improvements in modeling geophysical systems both experimentally and numerically. </p>