Browse Articles

How do RNA molecules distinguish self from non-self?

RNA molecules form homotypic clusters in a variety of contexts. mRNAs enriched in germ granules in Drosophila embryos are a canonical example, with polar granule component ( pgc ) mRNAs colocalized with other pgc mRNAs, and nanos mRNAs with other nanos mRNAs. The observation of homotypic clustering poses a conundrum: how can RNAs of a given sequence distinguish other RNAs of the same sequence from those with different sequences? Here we show in silico that RNAs can distinguish self from non-self through the presence of palindromic regions within RNA sequences, and that palindromes can mediate homotypic clustering. We further show that RNA–RNA interactions are unlikely to lead to homotypic clusters in the absence of palindromes due to a competition between intra- and intermolecular RNA structures. We explore the implications of the palindrome-based clustering hypothesis for nanos and pgc mRNAs, and suggest how it may clear up a surprising feature of nanos clusters. More broadly, our results indicate that the palindrome content of RNAs may be under evolutionary selection pressure across a range of contexts.

Comment on “Electromagnetic metagratings for diffraction fields manipulation” [J. Appl. Phys. 138, 120701 (2025)]

Finsler fractional anisotropy (FFA): a directionally sensitive descriptor for multi-fiber white matter characterization in HARDI

Abstract Diffusion tensor imaging has significantly advanced the study of brain microstructure, but it faces challenges in regions with complex fiber architectures. High angular resolution diffusion imaging provides improved angular resolution, but still lacks straightforward scalar measures for complex diffusion patterns. We propose Finsler fractional anisotropy (FFA), a directionally sensitive biomarker derived from the Finsler geometry framework to capture local features in multi-fiber white matter. The descriptor was evaluated using both synthetic and in vivo data. Results suggest that FFA offers improved sensitivity in differentiating fiber crossings from parallel bundles, showing enhanced contrast and directional sensitivity, particularly within multi-fiber voxels where traditional scalar measures tend to be less informative. Statistical evaluations (t-test and Wilcoxon signed-rank test) indicated significant differences, with p -values $$\ll 0.01$$ . We also discuss the strengths and limitations of FFA in analyzing complex white matter. Overall, these preliminary findings suggest that FFA may serve as a valuable complementary tool for characterizing complex brain microstructure. While results show enhanced directional sensitivity in regions with crossing fibers, further validation in larger clinical cohorts is required to establish its utility for investigating conditions such as multiple sclerosis and Alzheimer’s disease.

Insects manipulate host nuclear trafficking and epigenetic regulation to facilitate herbivory

Impact of density and disorder on the low-temperature heat capacity of carbon–carbon composites

The low-temperature specific heat of expanded graphite (EG) and EG–multiwalled carbon nanotube (MWCNT) composites (1.0, 3.0 wt. % MWCNTs) was investigated over the temperature range of 2–300 K. The results reveal that the heat capacity of pure EG and EG–MWCNT composites is primarily governed by low-frequency out-of-plane phonons with quadratic dispersion, characteristic of two-dimensional layered systems. These flexural phonon modes dominate vibrational behavior at cryogenic temperatures. Compared to bulk crystalline graphite, EG exhibits higher heat capacity at low temperatures due to its increased defect density, structural disorder, and reduced interlayer coherence. X-ray diffraction and Raman spectroscopy measurements of the structure supported by energy-dispersive x-ray spectroscopy analysis confirmed the variations in the stacking order, defect concentration, and impurity levels. Heat capacity was effectively described by a three-term equation: a defect-related linear term (C1T), a Debye phonon term (C3T3), and a dispersive phonon term (C5T5). A strong correlation was observed between the linear coefficient (C1) and EG density, validated by the Raman I2D/IG ratio. The negative C5 coefficient in EG samples confirms the quadratic dispersion of flexural phonons, aligning with the Komatsu–Nagamiya phonon model and emphasizing EG's anisotropic vibrational properties. The absence of a low-temperature hump, typical in disordered solids, further supports the two-dimensional phonon behavior. These findings highlight the impact of MWCNT integration and structural disorder on the vibrational heat capacity of EG-based composites, offering insight into phonon dynamics in anisotropic carbon systems.

The effects of seaweed extract and amino acid fertilizers on growth and productivity of two grape (Vitis vinifera L.) cultivars

Significant Southern Hemisphere contribution to the Indonesian Throughflow over the last 800,000 years

Abstract The low-latitude flow of water masses from the Pacific to the Indian Ocean, the Indonesian Throughflow (ITF), is a choke point of the surface ocean return flow of the ocean conveyor belt. Even though the significance of the ITF for the modern global ocean circulation and climate has long been established, little is known about the hemispheric origin of the water masses contributing to its overall transport in the past. Here, we take advantage of the distinctly different isotopic composition of subsurface nitrate in the Northern and Southern Hemisphere source waters to document the admixture of these waters in the ITF through time. Our record of bulk sedimentary δ 15 N from the Banda Sea, at the heart of the ITF, shows that Southern Hemisphere-sourced subsurface waters contributed significantly to the total ITF transport during the last 800,000 years. Because Southern Ocean processes ultimately set the biogeochemical source signature of the Southern Hemisphere endmember, the Banda Sea record implies an important conduit by which high southern latitude climate and ocean variability is transmitted into the global ocean.

Dielectric function, band-to-band transitions, and exciton properties of bulk single-crystal In2O3 from room temperature to 600 °C determined by <i>in situ</i> spectroscopic ellipsometry

We investigate the temperature-dependent complex dielectric function of bulk single-crystal In2O3 over the spectral range of 1–6 eV and temperatures from room temperature to 600 °C under high-vacuum conditions using in situ spectroscopic ellipsometry. The dielectric function was modeled using wavelength-by-wavelength and critical-point model dielectric function analyses. The dielectric function exhibits pronounced alterations with increasing temperature, attributed to thermally induced changes in the band structure and carrier dynamics. We identify direct and indirect interband transitions and excitonic contributions associated with the direct bandgap near the onset of absorption. At elevated temperatures, features in the dielectric function due to indirect transitions emerge below the direct bandgap energy, which shift toward shorter photon energies with increasing temperature. Combining our results with low-temperature data from previous reports, both observed shifts of the direct and indirect transitions can be seamlessly explained with the Bose–Einstein model. The direct transition is coupled less strong to the phonon bath (average temperature θB=512 K), leading to a smaller high-temperature slope (γ=−0.2 meV/K) than for the indirect transition (θB=360 K, γ=−1.3 meV/K). The exciton contributions diminish toward higher temperatures reflected by the decrease in amplitude and increase in broadening model parameters. Our parameter set can be used to calculate the model dielectric function In2O3 at elevated temperatures.

Risk assessment of mountain tunnel collapse under complex geological conditions

Dysregulation of macrophage lipid metabolism underlies intracellular bacterial neuroinvasion

Reefense: Living shoreline mosaics can achieve ecological and engineering outcomes with interdisciplinary design

Living shorelines that comprise oyster reefs within a mosaic of multiple coastal habitats can be a resilient and adaptive coastal protection alternative to conventional engineered structures. The success of an oyster reef living shoreline depends on the evolution of a stable base substrate that provides initial short-term coastal protection, to the growth of a living oyster reef and associated habitats in the longer-term, which can enhance protection and provide other ecosystem services. Interdisciplinary global teams that include ecologists, biologists, engineers, techno-economists, and industry are leading the development and implementation of innovative reef-based coastal protection (“Reefense”) solutions that can be scaled to face the challenges of climate change.

Strong actuation of mass-loaded membranes for gravity studies at the milligram scale

An increasing number of studies are moving toward the combination of quantum mechanics and gravity, where studying gravity from a very small source mass is a viable starting point. Preparing for such experiments, investigations of weak gravitational forces have employed mechanical resonators to detect time-dependent gravitational forces from actuated source masses. Here, we demonstrate a source mass approach that utilizes capacitive actuation of a 1 mg gold sphere embedded on a silicon nitride membrane, rather than piezoelectric or motorized actuation. The design simultaneously provides a method for microwave-optomechanical implementation by coupling the membrane position to the electromagnetic mode of a 3D cavity. The cavity quality factor is not significantly compromised by electromagnetic leakage to the actuation electrode, allowing DC and kilohertz AC voltages to be introduced in the region where electric fields are strongly concentrated. We measure over 700 nm of a driven oscillation amplitude and more than 10% tunability in the mechanical resonance frequency of the loaded membrane, giving the potential to match the oscillations to the frequency range of a detector in future experiments. An optomechanical readout is demonstrated by measuring the cavity resonance at cryogenic temperatures, while room-temperature measurements provide complementary understanding of the mechanisms that influence the mechanical response, including repulsive contact due to collisions within the device.

External validation of the Phoenix Sepsis Score in a paediatric intensive care unit in Saudi Arabia

Abstract We externally validated the Phoenix Sepsis Score (PSS) for predicting n-hospital mortality in a Paediatric Intensive Care Unit (PICU) setting in Saudi Arabia and compared its performance with those of the International Paediatric Sepsis Consensus Conference (IPSCC) criteria and Paediatric Logistic Organ Dysfunction-2 (PELOD-2) score. This retrospective cohort study of a prospectively maintained paediatric sepsis registry included 0–14-year-old PICU-admitted children with suspected sepsis between 2015 and 2023. Of 431 admissions, 281 (65.2%) met the PSS criteria (PSS ≥ 2), of whom 197/281 patients (70.1%) met the septic shock criteria. The in-hospital mortality rates were 21.8% for the entire cohort, 12% for infection, and 27% for sepsis. A PSS ≥ 2 yielded a sensitivity of 80.9% (95% confidence interval [CI]: 71.7–87.5) and positive predictive value of 27.0% (95%CI: 22.2–32.5). The area under the precision-recall curve for the PSS was 0.45 (95% CI: 0.35–0.56), which was higher than that for the IPSCC criteria (0.38, 95%CI: 0.29–0.48) and comparable to that for the PELOD-2 score (0.48, 95%CI: 0.37–0.58). PSS discriminative performance, assessed by the area under the receiver-operating characteristic curve, was 0.67 (95% CI: 0.61–0.74), similar to that of the IPSCC criteria (0.67, 95%CI: 0.60–0.73) and PELOD-2 score (0.72, 95%CI: 0.65–0.77). The PSS demonstrated favourable precision-recall performance and fair discrimination for in-hospital mortality in this critical care cohort. Its precision-recall performance was superior to that of the IPSCC criteria and comparable to that of the PELOD-2 score. Notably, the PSS relies on fewer variables across four organ systems, which may enhance its practicality for risk stratification in comparable high-acuity critically ill children.

Sparseness facilitates image encoding across visuo-frontal networks in freely moving macaque

Combined effects of particle geometry and applied vibrations on the mechanics and strength of entangled materials

Entangled materials offer attractive structural features including tensile strength and large deformations, combined with infinite assembly and disassembly capabilities. How the geometry of individual particles governs entanglement, and, in turn, translates into macroscopic structural properties, provides a rich landscape in terms of mechanics, and offers intriguing possibilities in terms of structural design. However, there are major knowledge gaps on the entanglement mechanisms and how they can generate strength. In this report, we present tensile tests and discrete element method simulations on bundles of entangled staple-like particles that capture the combined effects of particle geometry and vibrations on local entanglement, tensile force chains, and strength. Standard steel staples with θ = 90° crown-leg angle initially entangle better than θ = 20° modified staples because of their more “open” geometry. However, as vibrations are applied, entanglement increases faster in θ = 20° bundles so that they develop strong and stable tensile force chains, producing bundles which are almost ten times stronger than θ = 90° bundles. Both tensile strength and entanglement density increase with vibrations and with deformations, up to a steady state value where the rate of entanglement balances the rate of disentanglement. Finally, we show that vibration and mechanical confinement can be used as a strategy to manipulate entanglement and disentanglement for disassembly and recycling. This work provides a fundamental understanding of how particle geometry and vibrations govern the properties of entangled materials, which can lead to better design guidelines for lightweight, reversible materials and structures and aggregate architectures.

Mixed attention mechanism multi-task learning for fetal abdominal standard plane recognition and key anatomical structure detection

A multi-modal diffusion model with dual-cross-attention for multi-omics data generation and translation

Bond weakening and strong anharmonicity driven ultralow thermal conductivity in monolayer CdIn2Se4

Two-dimensional (2D) materials with ultralow lattice thermal conductivity (kl) are crucial for high-efficiency thermoelectrics. Herein, we investigate the thermal transport properties of monolayer CdIn2Se4 using first-principles calculations combined with the phonon Boltzmann transport equation. An exceptionally low kl of 0.28 W m−1 K−1 is predicted at 300 K. This ultralow kl originates from the synergistic effect of strong lattice anharmonicity and weakened chemical bonds. The strong anharmonicity induces intense phonon scattering, and an extremely strong intraband and interband scattering in the out-of-plane acoustic branch is identified beyond expectation, leading to extremely short phonon relaxation times. Chemical bonding analysis reveals that the filling of antibonding states below the Fermi level weakens the Se–Cd bonds, which significantly reduces the phonon group velocities. Further scattering channel analysis confirms that the strong acoustic–acoustic and acoustic–optical phonon scatterings are the key factors suppressing kl. Our findings not only pinpoint the dual origins of ultralow kl in a promising 2D thermoelectric material but also provide a mechanistic framework for designing materials with engineered thermal transport properties.

Wireless sensor network design with reliable and long network lifetime

Revealing the hidden third dimension of point defects in two-dimensional MXenes

Abstract Point defects govern many important functional properties of two-dimensional (2D) materials. However, resolving the three-dimensional (3D) arrangement of these defects in multi-layer 2D materials remains a fundamental challenge, hindering rational defect engineering. Here, we overcome this limitation using an artificial intelligence-guided electron microscopy workflow to map the 3D topology and clustering of atomic vacancies in Ti 3 C 2 T X MXene. Our approach reconstructs the 3D coordinates of vacancies across hundreds of thousands of lattice sites, generating robust statistical insight into their distribution that can be correlated with specific synthesis pathways. This large-scale data enables us to classify a hierarchy of defect structures—from isolated vacancies to nanopores—revealing their preferred formation and interaction mechanisms, as corroborated by molecular dynamics simulations. This work provides a generalizable framework for understanding and ultimately controlling point defects across large volumes, paving the way for the rational design of defect-engineered functional 2D materials.