Animals rely on movement to survive-to explore their environment, find food and mates, and avoid danger. During development, changes in body shape, muscle strength, and physiological needs drive the continuous adjustment of locomotor patterns. How these changes are orchestrated in a flexible and adaptive manner remains unknown. We explore this question in Danionella cerebrum, a miniature freshwater fish that is emerging as an important vertebrate model in systems neuroscience. We identify a clear transition in locomotion, from continuous to burst-and-coast swimming occurring around 3 weeks of age. We demonstrate that this transition is an energy-saving strategy and that it reflects an instability in the sensorimotor process governing speed regulation. Rather than a preprogrammed developmental switch, it is therefore directly tied to the animal swimming strength. We confirmed this finding by manipulating sensory feedback to induce a similar transition at fixed developmental stages. Together, our results illustrate a dynamic interplay between body, brain, and environment during development, offering insights into the principles governing adaptive locomotion.
A line-ratio method for determining the reduced electric field is benchmarked against independent measurements from electrostatic probes and cavity ring-down spectroscopy. The method is applied to oxygen DC glow discharges with trace admixtures of argon and xenon. A corona model incorporating fluorescence quenching by heavy species is used to simulate the emission, with electron-impact excitation rates calculated using the LisbOn KInetics Boltzmann solver. The excitation cross sections and quenching coefficients are those proposed and validated for actinometry in part one of this combined study (Baratte et al 2025 Plasma Sources Sci. Technol. ). The reduced electric field is determined over a pressure range of 0.55 to 5 Torr (at 40 mA) and a current range of 15 to 50 mA (at 5 Torr). Consistent agreement with measured emission line intensities is achieved when applying a correction factor of κ c , Ar = 3 ± 0.5 to the excitation cross sections for the argon lines at 750 nm and 811 nm. With this correction, the reduced electric field values obtained from the line-ratio method are in good agreement with direct measurements. A comparison of different line ratios is presented, showing that the best performance is achieved using the ratio of the Ar 750 nm and Xe 828 nm lines. This ratio is particularly sensitive to changes in the electron energy distribution function, due to the large difference in excitation thresholds, while remaining independent of the knowledge of species densities.
Surface topography plays a critical role in regulating cellular behavior through contact guidance. In this context, micro‐nanostructured materials have gained widespread use in biomedicine with applications in biosensing, bioimaging, or tissue engineering. Among the different strategies that can be applied for surface structuration, laser‐induced surface patterning offers a precise and versatile alternative to traditional lithographic techniques by enabling rapid processing and tailored modifications of material properties. Using an ultrafast femtosecond laser, the laser structuring of three different biopolymers, sodium alginate, gelatin, and collagen are investigated here. The resulting surfaces are analyzed using confocal and scanning electron microscopy (SEM). In parallel, the structural and chemical modifications induced by the laser ablation are thoroughly characterized. The interaction of human myoblasts cultured on these engineered surfaces is evaluated revealing that the laser‐induced topographical features have a significant impact on myoblast alignment. Specifically, optimal channel widths of 20–25 µm and interline spacings ranging from 35 to 150 µm promoted efficient cell organization mimicking the native constraint of skeletal muscle tissue. These findings emphasize the potential of laser‐patterned polymer surfaces to guide muscle cell orientation and differentiation, providing a promising approach for developing functional surfaces in skeletal muscle tissue engineering.
When driving a disordered elastic manifold through quenched disorder, the pinning forces exerted on the center of mass are fluctuating, with mean f_{c}=-F_{w}[over ¯] and variance Δ(w)=F_{w}F_{0}[over ¯]^{c}, where w is the externally imposed control parameter for the preferred position of the center of mass. Δ(w) was obtained via the functional renormalization group in the limit of vanishing temperature T→0, and vanishing driving velocity v→0. There are two fixed points, and deformations thereof, which are well understood: The depinning fixed point (T→0 before v→0) rounded at v>0, and the zero-temperature equilibrium fixed point (v→0 before T→0) rounded at T>0. Here we consider the whole parameter space of driving velocity v>0 and temperature T>0, and quantify numerically the crossover between these two fixed points.
With as many as 2000 satellites per year forecast to be launched over the next decade, onboard propulsion systems will become increasingly important for ensuring both mission success and a sustainable space environment. Plasma-based electric propulsion systems are particularly attractive because of their high fuel efficiency, but due to challenges with conventional propellants such as xenon, a strong interest in viable alternatives has emerged. One such alternative is iodine, which in addition to space-based applications, is also of use in a number of ground-based industrial applications such as plasma etching. With a lower cost, higher global production output, and a reduced ionization threshold compared with xenon, iodine has the potential to meet current and future space industry demand while also providing improved propulsion performance. Furthermore, iodine is a solid at typical ambient conditions with a high storage density. However, iodine is chemically reactive with many common materials and has a more complex plasma chemistry that includes molecular dissociation, attachment to form negative ions, and several ionization processes creating positive atomic and molecular ions. This topical review provides a comprehensive overview of iodine within the context of plasma applications and also serves as a useful data source for various thermodynamic properties, collision cross-sections, and iodine-surface interactions. In addition to discussing the physical and atomic/molecular properties of iodine, we also highlight important theoretical, numerical, and experimental work in the field and discuss the current state-of-the-art: including the space flight heritage of iodine-fueled propulsion systems and remaining research/technical challenges.
