Junjie Dong, Gabriel-Darius Mardaru, Paul D. Asimow
et al.
We present globally inverted pressure-temperature (P-T) phase diagrams up to 5,000 GPa for four fundamental planetary materials, Fe, MgO, SiO2, and MgSiO3, derived from logistic regression and supervised learning, together with an experimental phase equilibria database. These new P-T phase diagrams provide a solution to long-standing disputes about their melting curves. Their implications extend to the melting and freezing of rocky materials in the interior of giant planets and super-Earth exoplanets, contributing to the refinement of their internal structure models.
The Greenland Ice Sheet may be nearing a tipping point, transitioning to permanent melting. This article analyses two melt rate time series using the Bayesian Langevin estimation (BLE), providing further evidence for destabilizing melt dynamics, along with new insights from the method's nonlinear parameterisation. Comparing the results for Western Central Greenland and the Nuussuaq peninsula suggests that inland melt dynamics may approach less stable coastal dynamics on slow and fast scales. Both datasets show a significant increase in fast-scale amplitudes since the 1970s, possibly driven by large-scale atmospheric fluctuations. Additionally, the BLE's nonlinear drift proves crucial for obtaining these results, as a linear Ornstein-Uhlenbeck process fails to capture these dynamics due to the oversimplification of a strictly positive autocorrelation function.
Uranus and Neptune have intrinsic magnetic fields generated via convection in a molten H2O layer, where the field strength is determined by its electrical conductivity (EC) along with convection size and velocity. Previous shock experiments reported that the EC of molten H2O is high enough to generate magnetic fields of these ice giant planets with adiabatic thermal structures. Here we measured the EC of ionic H2O fluid for the first time by static compression experiments up to 45 GPa and 2,750 K. The EC determined is lower by a few orders of magnitude than earlier data by shock compression measurements and not capable of generating a magnetic field with the conventional interior thermal structures. Our results necessitate recently-suggested fewfold hotter interiors of Uranus and Neptune to explain their magnetic fields.
The observed equilibrium constants (Kobs) of the creatine kinase (EC 2.7.3.2), myokinase (EC 2.7.4.3), glucose-6-phosphatase (EC 3.1.3.9), and fructose-1,6-diphosphatase (EC 3.1.3.11) reactions have been determined at 38 degrees C, pH 7.0, ionic strength 0.25, and varying free magnesium concentrations. The equilibrium constant (KCK) for the creatine kinase reaction defined as: KCK = [sigma ATP] [sigma creatine] divided by ([sigma ADP] [sigma creatine-P] [H+]) was measured at 0.25 ionic strength and 38 degrees C and was shown to vary with free [Mg2+]. The value was found to be 3.78 x 10(8) M-1 at free [Mg2+] = 0 and 1.66 x 10(9) M-1 at free [Mg2+] = 10(-3) M. Therefore, at pH 7.0, the value of Kobs, defined as Kobs = KCK[H+] = [sigma ATP] [sigma creatine] divided by ([sigma ADP] [sigma creatine-P] was 37.8 at free [Mg2+] = 0 and 166 at free [Mg2+] = 10(-3) M. The Kobs value for the myokinase reaction, 2 sigma ADP equilibrium sigma AMP + sigma ATP, was found to vary with free [Mg2+], being 0.391 at free [Mg2+] = 0 and 1.05 at free [Mg2+] = 10(-3) M. Taking the standard state of water to have activity equal to 1, the Kobs of glucose-6-P hydrolysis, sigma glucose-6-P + H2O equilibrium sigma glucose + sigma Pi, was found not to vary with free [Mg2+], being 110 M at both free [Mg2+] = 0 and free [Mg2+] = 10(-3) M. The Kobs of fructose-1,6-P2 hydrolysis, sigma fructose-1,6-P2 equilibrium sigma fructose-6-P + sigma Pi, was found to vary with free [Mg2+], being 272 M at free [Mg2+] = 0 and 174 M at free [Mg2+] = 0.89 x 10(-3) M.
AbstractIn this work, we used a particle transport model integrated into the fluid solver in FLAC to simulate the transport of particles in the near-wellbore region inside a hydraulic fracture. Complex flow behaviors, including divergent flow near the fracture entrance and detouring flow around diverter packs, can be captured in this coupling system. In the numerical implementation, the coupled fluid flow and particle transport are realized by updating the fracture permeability, particle concentration, and velocities of fluid and particles in each time step. Simulation results indicate that the final shape of the particle bridging zone at the near-wellbore region is determined by the flow-driven and settling-driven particle transport. A continuous bridging band initially forms at the bottom region of the fracture, then the fluid-driven particles move upwards to block the top region of the fracture. Lastly, a V-shaped bridging band is formed inside the fracture. It is observed that high initial particle concentration and large particle size result in the creation of a small-scale bridging band near the injection entrance, which promotes the rapid growth of the closed bridging band and high-pressure buildup.
The paper by A.N. Kolmogorov 1934 "Random Moves", hereinafter ANK34, uses a Fokker-Planck-type equation for a 6-dimensional vector with a total rather than a partial derivative with respect to time, and with a Laplacian in the space of velocities. This equation is obtained by specifying the accelerations of the particles of the ensemble by Markov processes. The fundamental solution was used by A M Obukhov in 1958 to describe a turbulent flow in the inertial interval. Already recently it was noticed that the Fokker-Planck-type equation written by Kolmogorov contains a description of the statistics of other random natural processes, earthquakes, sea waves, and others. This theory, containing the results of 1941, paved the way for more complex random systems containing enough parameters to form an external similarity parameter. This leads to a change in the characteristics of a random process, for example, to a change in the slope of the time spectrum, as in the case of earthquakes and in a number of other processes (sea waves, cosmic ray energy spectrum, flood zones during floods, etc.). A review of specific random processes studied experimentally provides a methodology for how to proceed when comparing experimental data with the ANK34 theory. Thus, empirical data illustrate the validity of the fundamental laws of probability theory.
Matthias Schartner, Leonid Petrov, Christian Plötz
et al.
In this work, we present a status update and results of the designated research and development VLBI Intensive program VGOS-INT-S, observed between MACGO12M and WETTZ13S for the rapid determination of the Earth's phase of rotation, expressed via UT1-UTC. The main novelty of these sessions is the use of a special observation strategy, rapidly alternating between high- and low-elevation scans, enabling an improved determination of delays caused by the neutral atmosphere. Since 2021, 25 Intensive sessions have been observed successfully. In early 2022, VGOS-INT-S was among the most accurate Intensive programs with an average formal error $σ_{UT1-UTC}$ of 3.1 $μ$s and a bias w.r.t. IERS C04 of 1.1 $μ$s. Later, the session performance decreased due to multiple technical difficulties.
It has been shown that endocytic vesicles in BALB/c 3T3 cells have a pH of 5.0 (Tycko and Maxfield, Cell, 28:643-651). In this paper, a method for measuring the effect of various agents, including weak bases and ionophores, on the pH of endocytic vesicles is presented. The method is based on the increase in fluorescein fluorescence with 490-nm excitation as the pH is raised above 5.0. Intensities of cells were measured using a microscope spectrofluorometer after internalization of fluorescein-labeled alpha 2-macroglobulin by receptor-mediated endocytosis. The increase in endocytic vesicle pH was determined from the increase in fluorescence after addition of various concentrations of the test agents. The following agents increased endocytic vesicle pH above 6.0 at the indicated concentrations: monensin (6 microM), FCCP (10 microM), chloroquine (140 microM), ammonia (5 mM), methylamine (10 mM). The ability of many of these agents to raise endocytic vesicle pH may account for many of their effects on receptor-mediated endocytosis. Dansylcadaverine caused no effect on vesicle pH at 1 mM. The observed increases in vesicle pH were rapid (1-2 min) and could be reversed by removal of the perturbant. This reversibility indicates that the vesicles themselves contain a mechanism for acidification. The increase in vesicle pH due to these treatments can be observed visually using an SIT video camera. Using this method, it is shown that endocytic vesicles become acidic at very early times (i.e., within 5-7 min of continuous uptake at 37 degrees C).
The equilibrium climate sensitivity (ECS) of the CMIP6 global circulation models (GCMs) varies from 1.83 °C to 5.67 °C. Herein, 38 GCMs are grouped into three ECS classes (low, 1.80-3.00 °C; medium, 3.01-4.50 °C; high, 4.51-6.00 °C) and compared against the ERA5-T2m records from 1980-1990 to 2011-2021. We found that all models with ECS > 3.0 °C overestimate the observed global surface warming and that spatial t-statistics rejects the data-model agreement over 60% (using low-ECS GCMs) to 81% (using high-ECS GCMs) of the Earth's surface. Thus, the high and medium-ECS GCMs are unfit for prediction purposes. The low-ECS GCMs are not fully satisfactory yet, but they are found unalarming because by 2050 they predict a moderate warming ($ΔT_{preindustrial\rightarrow2050}\lesssim2\:{^\circ}C$).
Vishnu Viswanathan, Erwan Mazarico, Stephen Merkowitz
et al.
Lunar retro-reflector arrays (LRAs) consisting of corner-cube reflectors (CCRs) placed on the nearside of the Moon during the Apollo era have demonstrated their longevity, cost-effectiveness, ease of deployment, and most importantly their interdisciplinary scientific impact through the ongoing lunar laser ranging (LLR) experiment. The human exploration of the lunar south polar region provides a unique opportunity to build on this legacy and contribute to the scientific return of the Artemis, for many decades to come. Here we outline the extended science objectives realizable with the deployment of geodetic tracking devices by the Artemis III crew.
In this paper a new Geophysical gravimetry approach is presented, which is based on satellite imagery in remote sensing. The method uses a satellite image, together with a set of points in the image the gravity values of which are known. Template-based spheroidal spline method of interpolation is used to constitute a system of equations to find the values of gravity at other points in the image. A real case study is presented for the Qom region in Iran. Values of gravity are determined from the Landsat satellite image for this region, using 9 points in the image whose gravity values are known. Reference ellipsoid gravity values, which are based on coefficients derived from satellite gravimetry, are computed for this region, as well. Comparison between gravity values derived from Landsat image and those from reference ellipsoid shows that the standard deviation of the results is around 6.71 milli Gal, with the maximum of differences being 35 milli Gal.
Enceladus is characterised by a south polar hot spot associated with a large outflow of heat, the source of which remains unclear. We compute the viscous dissipation resulting from tidal and libration forcing in the moon's subsurface ocean using the linearised Navier-Stokes equation in a 3-dimensional spherical model. We conclude that libration is the dominant cause of dissipation at the linear order, providing up to about 0.001 GW of heat to the ocean, which remains insufficient to explain the (about) 10 GW observed by Cassini. We also illustrate how resonances with inertial modes can significantly augment the dissipation. Our work is an extension to Rovira-Navarro et al. [2019] to include the effects of libration. The model developed here is readily applicable to the study of other moons and planets.