Future Earth

A water conveyance open channel project in Xinjiang passes through a vast region of collapsible loess. Under intermittent water supply conditions and the environmental effect of seasonal temperature variations, the sliding failure of the canal slope often occurs. To analyze the influence of environmental effects on collapsible loess, this study examines the variation law of mechanical properties through triaxial tests subjected to dry–wet–freeze–thaw cycles. An elastoplastic constitutive model suitable for structural loess is proposed based on the modified Cam-clay model. The results indicate that as the number of dry–wet–freeze–thaw cycles increases, the stress–strain curve of loess decreases, while the volume change curve rises, with a progressively smaller range of variation. The cohesion and internal friction angle show an exponentially decreasing trend, greatly affecting cohesion by the dry–wet–freeze–thaw cycle. Three failure modes are observed in loess soil samples. The stress–strain curve corresponding to shear failure exhibits a softening type, the curve for bulging failure shows a weak hardening type, and the curve belonging to compaction failure demonstrates a strong hardening type. Based on the modified Cam-clay model, the concept of upper and lower loading surfaces is introduced to account for the structure of loess, and a nonassociated flow criterion is used to develop a boundary surface elastoplastic constitutive model suitable for loess. The fitting results are in good agreement with triaxial test data obtained under dry–wet–freeze–thaw cycles. These findings provide theoretical support for the safe operation of open channels.

Wavelength division multiplexing (WDM) optical interconnect technology offers an effective solution for addressing the ever-increasing data traffic. Microring modulators (MRMs), owing to their high bandwidth, compact footprint, and inherent wavelength selectivity, have become key building blocks in WDM systems. However, the limited free spectral range (FSR) of MRMs restricts the number of available wavelength channels and the corresponding overall data rate capacity in WDM systems. In this study, we propose an optimized Bezier-bent MRM, in which the device radius is reduced to 3 μm to significantly enhance the FSR. The proposed MRM operates without the need for a DC bias voltage and an RF amplifier, exhibiting a low insertion loss of 0.4 dB, an ultrawide FSR exceeding 4 THz, and a high electro-optic bandwidth of over 110 GHz. Back-to-back (BtB) transmission experiments demonstrate that the modulator supports 400 Gbps PAM-8 data transmission under a driving voltage of only 1 V, satisfying the 7% hard-decision forward error correction (HD-FEC) bit-error-rate (BER) threshold of 3.8 × 10–3. Owing to the compact-radius design, the junction capacitance is substantially reduced, enabling an exceptionally low modulation power consumption of 0.2 fJ/bit. The proposed MRM presents significant potential for dense integration in future optical communication systems.

Thermal structure of the lithosphere reflects its long-term evolution and controls its rheology, expressed in crustal and mantle anisotropic layering as observed in many seismic tomographic models globally and for Asia. Estimates of lithosphere thermal thickness, which defines lithospheric geotherms, show significant differences depending on the method and the employed lithosphere definition (Artemieva, 2011). While lithosphere thermal structure is often constrained by borehole heat flow values, the approach requires, among other critical things, exclusion of tectonic provinces with non-steady-state thermal state and areas with active tectonics (young magmatism and hots springs) (Artemieva & Mooney, 2001). These requirements are not satisfied for ca. 75% of the Asian continent. Due to data limitations and intrinsic complexity of lithosphere structure and composition, the existing models for lithosphere thermal structure are either of low resolution, or poorly constrained, or unreliable.This study fills this knowledge gap by presenting lithosphere thermal model for the entire Asia continent (15-50 N/70-135 E) based on an alternative approach (Artemieva, 2019a,b, 2022; Artemieva & Shulgin, 2019; Xia et al., 2023). The results are discussed in relation to regional geological ages (Artemieva, 2006) and geodynamic processes that shaped the region from Archean to present. Artemieva, I.M. and Mooney, W.D., 2001. Thermal thickness and evolution of Precambrian lithosphere: A global study. JGR, 106(B8): 16387-16414.Artemieva, I.M., 2006. Global 1o x 1o thermal model TC1 for the continental lithosphere: Implications for lithosphere secular evolution. Tectonophysics, 416(1-4): 245-277.Artemieva, I.M., 2011. The lithosphere: An interdisciplinary approach. Cambridge University Press, Cambridge, U.K., 794 pp.Artemieva, I.M., 2019a. Lithosphere structure in Europe from thermal isostasy. Earth-Science Reviews, 188: 454-468.Artemieva, I.M., 2019b. Lithosphere thermal thickness and geothermal heat flux in Greenland from a new thermal isostasy method. Earth-Science Reviews, 188: 469-481.Artemieva, I.M., 2022. Antarctica ice sheet basal melting enhanced by high mantle heat. Earth-Science Reviews, 226: 103954.Artemieva, I.M. and Shulgin, A., 2019. Geodynamics of Anatolia: Lithosphere Thermal Structure and Thickness. Tectonics, 38(12): 4465-4487.Xia, B., Artemieva, I.M., Thybo, H. and Klemperer, S.L., 2023. Strong Variability in the Thermal Structure of Tibetan Lithosphere. JGR, 128(B): e2022jb026213.

The safety assessment of a Deep Geologic Repository (DGR) for high-level radioactive waste in Korea necessitates a precise and integrated understanding of subsurface conditions. Building upon previous research that established a basic 3D site model for intuitive geological understanding, this study focuses on developing an integrated 3D visualization tool. The primary objective is to develop the procedures to manage and visualize diverse investigation datasets by integrating them into a coordinate-based 3D framework, thereby enhancing the reliability of site characterization.The input data for the proposed tool are categorized into geological features and investigation results. Geological features, including volumes and surfaces (e.g., faults), are constructed by interpolating point clouds from surface maps and joining boundaries within the SKUA-GOCAD environment. Investigation data, comprising geotechnical and geophysical results, are structured into a 4x3 matrix based on their spatial forms (point, line, surface, volume) and physical quantities (scalar, vector, tensor). This systematic classification allows the tool to accommodate all standard investigation formats within a unified spatial environment.The developed visualization tool provides three core capabilities: 1) Spatial Precision: A coordinate-based system ensures the exact locations of multi-source investigation data. 2) Intuitive Visualization of Physical Quantities: The position and magnitude of physical quantities of scalars, vectors, and tensors can be verified intuitively. The tool utilizes RGB color mapping (blue for low values, red for high values) to represent the magnitude of physical quantities, making data interpretation straightforward. 3) Spatial Interaction and Feedback: The tool enables the analysis of geological attributes along borehole trajectories and geophysical cross-sections. This spatial comparison facilitates a feedback loop, allowing the 3D model to be iteratively refined and updated based on empirical investigation data.Currently, the tool’s functionality has been verified using geological and investigation data from the research testbed. This integrated approach significantly improves the efficiency of site characterization and provides a robust foundation for DGR safety assessments. Future research will focus on program stabilization, thorough verification and the implementation of advanced analytical features to support long-term site monitoring and management.

Abstract The red seaweed Asparagopsis taxiformis can reduce methane emissions in livestock by over 90%, but its mariculture remains in its infancy and biomass for research and commercial use relies partly on wild populations. Knowledge on the impacts of harvesting A. taxiformis is lacking, emphasising the need for ecological research to guide the development of its sustainable harvesting. This study examined the regrowth potential of A. taxiformis meadows following small-scale harvesting. A harvest experiment testing the methods, handpicking and cutting, was conducted in Gladstone, Queensland, Australia, during the austral winter, with plots monitored over six months. Harvesting immediately affected percent cover and shoot length. Handpicked and cut plots exhibited regrowth within four to five months in terms of cover, which notably exceeded or were slightly above that of control plots. The shoot length of harvested plots paralleled that of control plots and was mainly influenced by seasonality. Control plots exhibited reduced growth at three months, suggesting that harvesting mimicked the seasonal reduction in biomass after the winter peak. This study also demonstrated the importance of vegetative propagation in the regrowth of A. taxiformis . The sessile benthic community in harvested plots underwent temporal shifts similar to those in the control plots, indicating that harvesting did not substantially alter community dynamics. Approximately 19 taxa of mobile fauna were recorded within Asparagopsis meadows, potentially indicating its habitat role. Overall, these findings provide ecological insights into the harvesting impacts on this seaweed, with further studies needed to assess broad-scale and long-term impacts.

Immunoassays are widely used for preliminary drug screening. While lateral flow assays (LFAs) offer rapid and portable testing, they often suffer from limited sensitivity and subjective interpretation. In contrast, laboratory-based immunoassay systems provide high precision but are unsuitable for field use due to their size and cost. To address these limitations, we developed a portable fluorescence-based microfluidic assay capable of detecting methamphetamine (MET), benzoylecgonine (BE), 11-nor-9-carboxy-tetrahydrocannabinol (THC-COOH), and benzodiazepines (BZOs) in urine specimens within 5 min. They were selected based on both global and domestic prevalence, as well as the detection capability of the developed microfluidic chip, which was designed to simultaneously target all four. The assay comprises a portable reader and a chip with two channels, each aligned with drug-specific antibodies, enabling simultaneous detection. The assay was tested against standard concentrations of the target drugs, delivering accurate test/reference ratios and signal displacements at threshold levels. We evaluated urine specimens (N = 141) provided by the National Forensic Service in Korea, including drug-free controls (N = 30) and cases confirmed for MET (N = 30), THC-COOH (N = 30), and BZOs (N = 13), along with samples from Paraguay for BE (N = 38), using validated diagnostic techniques. Analysis of 141 authentic urine specimens, encompassing verified instances of both single and poly drug use, showed high sensitivity and specificity with minimal cross reactivity. This study confirms that the microfluidic assay is effective in detecting multiple drugs simultaneously, offering high accuracy, cost-effectiveness, and portability, with excellent sensitivity for each drug tested.

Our main result is a succinct counterpoint to Courcelle's meta-theorem as follows: every cw-nontrivial monadic second-order (MSO) property is either NP-hard or coNP-hard over graphs given by succinct representations. Succint representations are Boolean circuits computing the adjacency relation. Cw-nontrivial properties are those which have infinitely many models and infinitely many countermodels with bounded cliquewidth. Moreover, we explore what happens when the cw-nontriviality condition is dropped and show that, under a reasonable complexity assumption, the previous dichotomy fails, even for questions expressible in first-order logic.