SAN ANTONIO — December 18, 2025 — The Southwest Research Institute-led Ultraviolet Spectrograph (UVS) aboard NASA’s Europa Clipper spacecraft has made valuable observations of the interstellar comet 3I/ATLAS, which in July became the third officially recognized interstellar object to cross into our solar system. UVS had a unique view of the object during a period when Mars- and Earth-based observations were impractical or impossible.

The paper “Resolved mass assembly and star formation in Milky Way Progenitors since z = 5 from JWST/CANUCS: From clumps and mergers to well-ordered disks” was published in the Astrophysical Journal. Led by Dr. Vivian Tan, who recently completed her Ph.D. at York University under the supervision of Prof. Adam Muzzin, provides the most detailed reconstruction yet of how the Milky Way may have evolved from its earliest phases to the structured spiral we see today. Tan and her colleagues examined 877 “Milky Way twins” — galaxies whose masses and properties closely match what astronomers expect the Milky Way would have looked like at different ages across cosmic time. By observing more distant, and therefore progressively younger examples of these galactic look-alikes, the team effectively charted a timeline of our galaxy’s life, with surprising results. Our Milky Way’s history started from a remarkably tumultuous youth before its more settled adulthood.

On 17 December, in the Atacama Desert in northern Chile, representatives from the Cherenkov Telescope Array Observatory (CTAO), the European Southern Observatory (ESO), and governmental authorities gathered to celebrate the official groundbreaking of the CTAO’s southern site, CTAO-South. After years of successful site preparations, the event marked the beginning of construction on the telescope foundations, paving the way for the first telescopes of the first and largest gamma-ray observatory in the southern hemisphere.

With the advancement of Internet applications, the global demand for broadband satellite communication services is incessantly escalating. Furthermore, there exists an exponential surge in the requisition for the capacity of satellite communication systems. In response to this evolving demand, the domain of satellite communication technology is progressively evolving toward the realm of high-throughput satellite (HTS) communication systems. The typical technical characteristics of HTS are: (a) the satellite adopts multibeam technology for beam overlapping coverage of the service area, which improves the quality of the wireless link while realizing the spatial dimension segmentation; (b) based on this, the system adopts multiple frequency multiplexing to improve the communication capacity of a single satellite; (c) the gateway station is tightly coupled with the user beam clusters are tightly coupled to complete 2-hop communication, which makes multiple gateway stations share the communication resources of the same satellite, forming a spatial isolation of the gateway stations, and once again realizing the frequency multiplexing of the gateway station links. A key requirement for future multibeam broadband satellite communication systems is the ability to flexibly adjust beam capacity according to changes in business distribution, in order to meet time-varying business requirements. Beam hopping technology provides an efficient solution to achieve the efficient use of frequency resources and power resources. At the same time, the use of beam hopping makes the beam hopping of satellite payload need to match the business signals of ground signal stations, bringing about the need for synchronization of beam hopping between satellite and ground.

A large study of rats shows that genes shape the gut microbiome in two ways: directly, by influencing an individual’s own microbes, and indirectly by sharing microbes with others in their living space. The discovery has implications for understanding hows genetic effects on health can ripple through social groups.

To advance global collaboration in lunar science, the Department of Earth and Planetary Sciences at The University of Hong Kong (DEPS-HKU) and the Institute of Geology and Geophysics, Chinese Academy of Sciences (IGG-CAS) jointly hosted the International Lunar Sample Research Symposium 2025 from 21 to 24 November. The event attracted 230 participants from China, the USA, France, the UK, Japan, India, and other regions around the world.

Abstract

Purpose – The primary objective of this research is to develop new algorithms in the framework of deep neural networks for the valuation of options under dynamics driven by stochastic volatility models. We aim to use the Heston model for equity options to demonstrate the accuracy of our approach.

Design/methodology/approach – Physics-informed neural networks (PINNs) are trained to minimize a loss function that includes terms from the partial differential equation residuals, initial condition and boundary conditions evaluated at selected points in the space-time domain. Speed and accuracy comparisons are carried out against single hidden-layer neural networks, called physics-informed extreme learning machines (PIELMs). American options are formulated as linear complementarity problems, and PINNs are applied in conjunction with penalty methods for the computation of the option prices.

Findings – For American options under the Heston model, PINNs yield accurate prices. Computed Greeks sensitivities are in close agreement with those reported for mesh-based methods. In contrast to mesh-based penalty methods for American options, PINNs work with smaller values of the penalty term. For the real estate index American option problem, numerical prices obtained using PINNs have comparable accuracies as those obtained by a high-order radial basis functions finite difference scheme.

Practical implications – There is a lack of reliable pricing models for pricing property derivatives. This work contributes to developing accurate neural network algorithms.