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During an outbreak, infectious disease can spread among populations through host movement, potentially fueling local outbreaks with their own epidemiological dynamics. However, it is difficult to know how often infections between populations are transmitted by diseased travelers infecting healthy residents when abroad, rather than by diseased residents infecting healthy travelers, who later return home with the new pathogen. In this paper, we introduce a phylogeographic model where pathogens spread through visitor dynamics, whereby hosts “visit” other populations for short trips before returning home. To do so, we used the stationary properties of an epidemiological compartment model with visitor dynamics to construct an approximation that is statistically accurate and computationally tractable for phylogenetic modeling. We applied our model to empirical infection data and travel statistics from the European SARS-CoV-2 pandemic. Inference under our model suggests that, in the early stages of the outbreak, SARS CoV-2 was more often “pulled” into new countries by returning travelers than “pushed” into new countries by visitors from the source country. Estimates of host movement–related parameter values under our visitor model suggest that competing migration models, with trips of indefinite length, may underestimate the magnitude of outbreaks caused by visitors. This study emphasizes the importance of carefully incorporating host movement dynamics into such models. Significance StatementViral infections can spread among distinct locations by human travel. Being able to identify the source of a local outbreak – whether triggered by infected visitors or individuals returning home – is crucial. Here, we designed a phylogenetic model for modeling infectious disease transmission in spatially structured populations, explicitly accounting for realistic host movement. By accounting for “short trips”, our model can help inform travelrelated strategies for containing outbreaks. 

Abstract Ecological theory predicts that local species richness can influence biogeographic rates of speciation, extinction, and dispersal. For instance, increasing the number of competing species within a region may cause local speciation and dispersal rates to decrease but local extinction rates to increase, inducing a carrying capacity for local species richness. In this article, we introduce a fully generative, event-based phylogenetic diversification model, called DDGeoSSE, that allows diversity-dependent effects of local species richness to modulate biogeographic rates of diversification and range evolution. DDGeoSSE can accommodate and test a variety of alternative diversification scenarios that involve positive, negative, and neutral interactions among sympatric species for speciation, extinction, and dispersal. We derive mathematical and statistical properties of biogeographic outcomes generated by this model, such as the carrying capacity for a clade at equilibrium, which we validate through simulation. Because diversity-dependent phylogenetic models typically do not have tractable likelihood functions, we use deep learning withphyddleto perform parameter inference and model selection. Separately applying DDGeoSSE to CaribbeanAnolislizards and cloud forest-dwellingViburnumplants, we find evidence that local species richness plays a significant role in shaping diversification dynamics for both clades. 

ABSTRACT Global warming is expected to transfer carbon from soil organic matter to atmospheric CO₂, with microbial communities playing a crucial role in regulating this exchange. While the immediate impact of temperature on microbial functions is well understood and causes soil carbon losses, the long‐term response remains unclear, with losses stabilising over time, reducing the overall effect of chronic warming on soil organic carbon (SOC) stocks. Here, we examined the temperature dependence of microbial respiration and growth after 9 years of +5°C warming in a temperate forest. Using these temperature dependences and field temperature data, we modelled in situ carbon fluxes and changes in SOC stocks. Results showed that the direct effect of temperature initially increased respiration and growth, projecting a potential 31% SOC stock loss if the trend had persisted. However, the gradual optimisation of microbial traits to warming balanced the direct temperature effects, enhanced carbon use efficiency and offset CO₂emissions. Together, these microbial trait shifts limited the heat‐induced SOC loss to 15%, closely aligning with empirical observations. These findings suggest that microbial trait optimisation can moderate carbon emissions, providing a parsimonious mechanistic explanation for observations worldwide and underscoring the need to integrate microbial dynamics into models. 

The 70/30 copper–nickel alloy is used mainly in critical parts with more demanding conditions in marine settings. There is a need for innovative methods that offer fast production and cost-effectiveness in order to supplement current copper–nickel alloy manufacturing processes. In this study, we employ wire arc additive manufacturing (WAAM) to fabricate the 70/30 copper–nickel alloy. The as-built microstructure is characterized by columnar grains with prominent dendrites and chemical segregation in the inter-dendritic area. The aspect ratio of the columnar grain increases with increasing travel speed (TS) at the same wire feed speed (WFS). This is in contrast with the equiaxed grain structure, with a more random orientation, of the conventional sample. The sample built with a WFS of 8 m/min, TS of 1000 mm/min, and a track distance of 3.85 mm exhibits superior corrosion properties in the 3.5 wt% NaCl solution when compared with the conventional sample, as evidenced by a higher film resistance and breakdown potential, along with a lower passive current density of the WAAM sample. The corrosion morphology reveals the critical roles played by the nickel element that is unevenly distributed between the dendrite core and inter-dendritic area. 

Abstract Wire-arc directed energy deposition (DED) processed Inconel (IN) 718 is known to have coarse columnar grains, strong texture, and significant chemical and microstructural inhomogeneity in the as-fabricated condition. Homogenization treatment is commonly used prior to aging to eliminate the inhomogeneity and detrimental precipitation for better mechanical properties. In this study, however, direct aging (DA) at 700 °C without homogenization has resulted in room-temperature yield strength, ultimate tensile strength (UTS), and elongation that are comparable to wrought condition and among the highest reported properties for wire-arc DED IN718. The DA samples at between 650 and 750 °C aging also demonstrates remarkable ductility when deformed at elevated temperatures. In addition, when aged below 750 °C the DA IN718 possesses significantly higher UTS compared to those with homogenization treatment. These superior mechanical properties are highly likely due to the non-uniform and hierarchical precipitation consisting of disk-shaped γ″ in diameter from a few to tens of nm in the dendritic core area and micron-sized Laves phase and carbides in the inter-dendritic region. 

Abstract BaTiO₃is a technologically relevant material in the perovskite oxide class with above‐room‐temperature ferroelectricity and a very large electro‐optical coefficient, making it highly suitable for emerging electronic and photonic devices. An easy, robust, straightforward, and scalable growth method is required to synthesize epitaxial BaTiO₃thin films with sufficient control over the film's stoichiometry to achieve reproducible thin film properties. Here the growth of BaTiO₃thin films by hybrid molecular beam epitaxy is reported. A self‐regulated growth window is identified using complementary information obtained from reflection high energy electron diffraction, the intrinsic film lattice parameter, film surface morphology, and scanning transmission electron microscopy. Subsequent optical characterization of the BaTiO₃films by spectroscopic ellipsometry revealed refractive index and extinction coefficient values closely resembling those of stoichiometric bulk BaTiO₃crystals for films grown inside the growth window. Even in the absence of a lattice parameter change of BaTiO₃thin films, degradation of optical properties is observed, accompanied by the appearance of a wide optical absorption peak in the IR spectrum, attributed to optical transitions involving defect states present. Therefore, the optical properties of BaTiO₃can be utilized as a much finer and more straightforward probe to determine the stoichiometry level present in BaTiO₃films.