Simple models have been used to describe ecological processes for over a century. However, the complexity of ecological systems makes simple models subject to modelling bias due to simplifying assumptions or unaccounted factors, limiting their predictive power. Neural ordinary differential equations (NODEs) have surged as a machine-learning algorithm that preserves the dynamic nature of the data (Chen et al. 2018 Adv. Neural Inf. Process. Syst.). Although preserving the dynamics in the data is an advantage, the question of how NODEs perform as a forecasting tool of ecological communities is unanswered. Here, we explore this question using simulated time series of competing species in a time-varying environment. We find that NODEs provide more precise forecasts than autoregressive integrated moving average (ARIMA) models. We also find that untuned NODEs have a similar forecasting accuracy to untuned long-short term memory neural networks and both are outperformed in accuracy and precision by empirical dynamical modelling . However, we also find NODEs generally outperform all other methods when evaluating with the interval score, which evaluates precision and accuracy in terms of prediction intervals rather than pointwise accuracy. We also discuss ways to improve the forecasting performance of NODEs. The power of a forecasting tool such as NODEs is that it can provide insights into population dynamics and should thus broaden the approaches to studying time series of ecological communities.

We present an analysis of ground-based and JWST observations of SN 2022pul, a peculiar "03fg-like" (or "super-Chandrasekhar") Type Ia supernova (SN Ia), in the nebular phase at 338 days postexplosion. Our combined spectrum continuously covers 0.4-14 mu m and includes the first mid-infrared spectrum of a 03fg-like SN Ia. Compared to normal SN Ia 2021aefx, SN 2022pul exhibits a lower mean ionization state, asymmetric emission-line profiles, stronger emission from the intermediate-mass elements (IMEs) argon and calcium, weaker emission from iron-group elements (IGEs), and the first unambiguous detection of neon in a SN Ia. A strong, broad, centrally peaked [Ne ii] line at 12.81 mu m was previously predicted as a hallmark of "violent merger" SN Ia models, where dynamical interaction between two sub-M-Ch white dwarfs (WDs) causes disruption of the lower-mass WD and detonation of the other. The violent merger scenario was already a leading hypothesis for 03fg-like SNe Ia; in SN 2022pul it can explain the large-scale ejecta asymmetries seen between the IMEs and IGEs and the central location of narrow oxygen and broad neon. We modify extant models to add clumping of the ejecta to reproduce the optical iron emission better, and add mass in the innermost region (<2000 km s(-1)) to account for the observed narrow [O i] lambda lambda 6300, 6364 emission. A violent WD-WD merger explains many of the observations of SN 2022pul, and our results favor this model interpretation for the subclass of 03fg-like SNe Ia.

Compression of small molecules can induce solid-state reactions with products that are difficult or impossible to obtain through solution-phase synthesis. Of particular interest is the topochemical-like reaction of arenes to produce polymeric nanomaterials rich in sp3 carbon. However, high reaction onset pressures and poor control over high-pressure reaction selectivity remain significant challenges to be addressed. Herein, the incorporation of electron withdrawing/donating groups into π-stacked arenes is proposed as a strategy to reduce reaction barriers and onset pressures. Charge transfer cocrystals represent systems with optimal π-stacking and reduced energy barriers for intermolecular cycloaddition reactions, however, competing side-chain reactions between functional groups must also be considered. For the case of a diaminobenzene:tetracyanobenzene cocrystal, amidine formation between side groups is the first reaction to occur with an onset pressure near 9 GPa, as characterized using vibrational spectroscopy, X-ray diffraction, and computational studies. High-pressure reactivity is system-dependent and while functionalized arenes are predicted to exhibit reduced-barrier energy cycloaddition pathways, directed reactions between side groups can be used as a novel strategy for the formation unique polymeric materials.

A key challenge in materials discovery is to find high-temperature superconductors. Hydrogen and hydride materials have long been considered promising materials displaying conventional phononmediated superconductivity. However, the high pressures required to stabilize these materials have restricted their application. Here, we present results from high-throughput computation, considering a wide range of high-symmetry ternary hydrides from across the periodic table at ambient pressure. This large composition space is then reduced by considering thermodynamic, dynamic, and magnetic stability before direct estimations of the superconducting critical temperature. This approach has revealed a metastable ambient-pressure hydride superconductor, Mg2IrH6, with a predicted critical temperature of 160 K, comparable to the highest temperature superconducting cuprates. We propose a synthesis route via a structurally related insulator, Mg2IrH7, which is thermodynamically stable above 15 GPa, and discuss the potential challenges in doing so.

The vertebrate gut microbiota is a critical determinant of organismal function, yet it remains unclear if and how gut microbial communities affect host fitness under natural conditions. Here, we investigate associations between growth rate (a fitness proxy) and gut microbiota diversity and composition in a field experiment with threespine stickleback fish (Gasterosteus aculeatus). We detected on average 63% more bacterial taxa in the guts of high-fitness fish compared to low-fitness fish (i.e., higher -diversity), suggesting that higher diversity promotes host growth. The microbial communities of high-fitness fish had higher similarity (i.e., lower {beta}-diversity) than low-fitness fish, supporting the Anna Karenina principle-that there are fewer ways to have a functional microbiota than a dysfunctional microbiota. Our findings provide a basis for functional tests of the fitness consequences of host-microbiota interactions.

Decades of measurements of the thermophysical properties of hot metals show that pulsed Joule heating is an effective method to heat solid and liquid metals that are chemically reactive or difficult to contain. To extend such measurements to hundreds of GPa pressure, pulsed heating methods have recently been integrated with diamond anvil cells. The recent design used a low-side switch and active electrical sensing equipment that was prone to damage and measurement error. Here, we report the design and characterization of new electronics that use a high-side switch and robust, passive electrical sensing equipment. The new pulse amplifier can heat similar to 5 to 50 mu m diameter metal wires to thousands of kelvin at tens to hundreds of GPa using diamond anvil cells. Pulse durations and peak currents can each be varied over three orders of magnitude, from 5 mu s to 10 ms and from 0.2 to 200 A. The pulse amplifier is integrated with a current probe. Two voltage probes attached to the body of a diamond anvil cell are used to measure voltage in a four-point probe geometry. The accuracy of four-point probe resistance measurements for a dummy sample with 0.1 Omega resistance is typically better than 5% at all times from 2 mu s to 10 ms after the beginning of the pulse.

Brassinosteroid (BR) signaling leads to the nuclear accumulation of the BRASSINAZOLE-RESISTANT 1 (BZR1) transcription factor, which plays dual roles in activating or repressing the expression of thousands of genes. BZR1 represses gene expression by recruiting histone deacetylases, but how it activates transcription of BR -induced genes remains unclear. Here, we show that BR reshapes the genome-wide chromatin accessibility landscape, increasing the accessibility of BR -induced genes and reducing the accessibility of BR -repressed genes in Arabidopsis. BZR1 physically interacts with the BRAHMA -associated SWI/SNF (BAS) -chromatin -remodeling complex on the genome and selectively recruits the BAS complex to BR -activated genes. Depletion of BAS abrogates the capacities of BZR1 to increase chromatin accessibility, activate gene expression, and promote cell elongation without affecting BZR1's ability to reduce chromatin accessibility and expression of BR -repressed genes. Together, these data identify that BZR1 recruits the BAS complex to open chromatin and to mediate BR -induced transcriptional activation of growth -promoting genes.

Accretional heating of Earth's interior during formation is pivotal to its subsequent thermal and chemical evolution. In particular, impact heating of Earth's core is expected, but its amplitude and radial distribution within the core is unknown and could influence the onset of the geodynamo. The uncertainty is due, in part, to the lack of constraints on the temperature of the interior following formation due to the difficulty of preserving a record of such a high energy environment, and the assertion that super-heating during formation would be rapidly lost through magma ocean cooling. Here we systematically investigate core heating due to giant impacts using a Smoothed Particle Hydrodynamics (SPH) code with simulations spanning a range of impact angles, velocities, and masses. From these simulations we derive a scaling relation for core heating that depends on the impact parameters and predicts the radial core temperature profile following the impact. Our findings show that a significant amount of heat is deposited into the core, with a canonical impact scenario resulting in an average core temperature increase of about 3000 K, approximately 500 K higher than that of the overlying mantle. In this case the heat distribution within the core produces a strong thermal stratification. We use a parameterized cooling model to estimate that the core could have cooled to an adiabatic state similar to 290 Myr after a canonical impact, which is consistent with the observed time span between the age of the Moon and evidence for an active geodynamo.