Geometric nonlinear deformation analysis for heterogeneous solar sail membrane with creases under solar radiation pressure

This study aims to develop and evaluate a novel slit-lamp-based system to acquire 3-dimensional (3D) ultrasound volumes using conventional ultrasound probes. A slit-lamp adapter was 3D printed and connected with a linear actuator and graphical user interface (GUI) system to control movement and create volumes of 2-dimensional scans. The ultrasound probe contacted the patient's cornea to perform the scan. The GUI software was designed to acquire and process b-scan images, which were exported to 3D Slicer and manually annotated. The annotated images were used to render 3D renderings of ophthalmic anatomy using MATLAB and 3D Slicer. The optimal resolution, quality, scan type, and patient comfort were determined through simulations. Higher scan numbers and light contact pressure resulted in sufficient image clarity. Out of 250 completed scans, four 3D ultrasound models were created, depicting diagnoses such as tractional retinal detachment, choroidal hemorrhage, and myopia. These models were compared with traditional imaging methods. The study successfully created 3D ultrasound scans using a novel slit-lamp-based system and manual annotation. The accuracy of the models was comparable to other imaging forms and demonstrated greater details. This study represents a significant step toward an accessible point-of-care ultrasound system in ophthalmology.

Influence of albedo, radiation pressure, oblateness, and dust belt on the stability in the generalized elliptic restricted three-body problem

We use ALMA CO(1-0) observations and VLT/MUSE rest-frame optical data of the ultraluminous infrared galaxy (ULIRG) IRAS20100-4156 at z = 0.1297 to characterize its powerful outflow in multiple phases using tracers of cold molecular, ionized, and neutral atomic gas and dust as well. Our analysis uses the correspondence with the stellar velocity field to split the complex emission line profiles of the CO(1-0) line into components in gravitational and non-gravitational motion. We find a massive (8 × 10 9 M ⊙ ) molecular outflow containing about 40% of the total molecular gas mass in the system. The outflow shows a bi-conical morphology centered on the brightest galaxy in the merger, oriented along its minor axis and extending to ∼5 kpc. This outflow has a characteristic velocity of 170 km/s, an outflow mass rate of 700 M ⊙ /yr, a depletion time of 16 Myr, and energetics consistent with star formation as a driver. The neutral atomic and ionized gas phases traced by NaI absorption and H α emission show counterparts to the blueshifted cold molecular outflow but are only 15% and 3% as massive. None of the three gas phases show any signs of slowing down over the extent at which we detected the outflow, suggesting an acceleration mechanism acting on the outflowing gas at kpc scales. We also detect 3.5 × 10 7 M ⊙ of dust, traced by optical extinction in the MUSE data, in the blueshifted outflowing cold molecular gas. The ionization state of the non-outflowing gas is consistent with star formation, while the outflowing component shows shock-like ionization. We conclude that the multiphase outflow in IRAS20100-4156 originates in the southeast nucleus of the merger and is driven by the starburst activity there, with radiation pressure likely playing a significant role in its acceleration.

Audio-tactile association improves pitch perception in listeners with and without cochlear implants.

The observational appearance of debris disks is largely controlled by collisional grinding of their dust grains. However, the mechanical strength of dust at sizes in the micrometer to millimeter range is poorly known. Recent studies suggest that dust particles in the Solar System might have a higher critical fragmentation energy, QD, value than previously anticipated, while another recent study considered the Fomalhaut debris disk and found lower QD values to provide better fits to the data. In order to constrain the mechanical strength of dust, we investigate the collisional evolution of debris disks with QD prescriptions differing by about three orders of magnitude. We find that, above a certain threshold QD value, the disk's collisional evolution is dominated by rebounding -- rather than disruptive or cratering -- collisions. Rebounding (also known as bouncing) collisions are those in which both impactors survive, being only slightly eroded and producing fragments that only carry a minor fraction of their mass. We show that disks dominated by rebounding collisions would have brightness profiles increasing outward outside the parent belt. Since such profiles are not observed, this places an upper limit on how hard the debris dust is allowed to be in order not to violate the observations. We derived an approximate analytic expression for this limit, QD ≈ (1/8) v ^2(r) for grains close to the radiation pressure blowout size, where v K in the Keplerian circular speed at a distance r from the star. This implies QD łesssim 10^ 9...10 for micrometer-sized grains in typical debris disks. Even though rebounding collisions are not expected to affect debris disk evolution significantly, we emphasize that these collisions are actually much more frequent than disruptive and cratering ones in all debris disks.

Lagrangian points represent critical equilibrium configurations in celestial mechanics where gravitational and centrifugal forces balance, enabling small bodies to maintain relative positions with respect to two primary masses. This study investigates the location and stability of these points under the influence of radiative forces, with a particular focus on the role of radiation pressure in modifying gravitational equilibrium. Using a mathematical modeling approach, the research derives expressions for the collinear and triangular Lagrangian points and examines how radiation pressure affects their equilibrium configurations. The analysis shows that the positions of the collinear points shift as a function of the radiation parameter, while the stability characteristics of the triangular points are governed by the mass ratio of the system. These findings refine the theoretical understanding of Lagrangian dynamics in radiating systems and highlight the sensitivity of equilibrium configurations to radiative effects. The study concludes that incorporating radiation pressure is essential for accurately characterizing gravitational equilibrium in realistic astrophysical and space mission scenarios, thereby providing a more robust foundation for celestial navigation, satellite deployment, and space mission design, and contributing to a deeper understanding of orbital mechanics relevant to future space exploration missions.

Abstract Throughout two investigation periods, we estimated the canopy transpiration, understory evapotranspiration and total stand water use of Alnus alnobetula at three stands within the treeline ecotone of the Central Austrian Alps. Our study included one site at the lower edge of the treeline ecotone and two plots at the tree limit: one north-facing leeward and one south-east facing windward. Canopy transpiration ( T c ) was estimated at each site by taking sap flow measurements on six stems and scaling them up to stand canopy level. Understory and soil evapotranspiration ( ET u ) were derived using the soil water budget method. Throughout the treeline ecotone, normalized sap flow density was significantly correlated with solar radiation and vapour pressure deficit. By contrast, soil water content had no effect on normalised sap flow density, suggesting that A. alnobetula is highly tolerant of the limited soil water availability in the topsoil. Our estimated total stand evapotranspiration ( ET to t = T c + ET u ) for the treeline ecotone on Mt. Patscherkofel averaged 4.3 ± 0.6 mm per day, while T c averaged 3.6 ± 0.5 mm per day. These values considerably exceed the means reported for the growing season of adjacent isolated Pinus cembra trees, dwarf shrub communities, and grasslands, and should be taken into account when forecasting the potential effects of shrub encroachment on the water balance of the treeline ecotone.

When particles interact with light, they can absorb momentum, leading to optical forces and torques that are widely used for manipulating microscopic objects. In this study, we demonstrate that a parity-time (PT) symmetric laser operating near and below the lasing threshold can generate giant optical pulling and pushing forces, surpassing conventional radiation pressure by several orders of magnitude. This remarkable enhancement arises from the spectral singularities of the PT-symmetric system, where both reflection and transmission coefficients diverge at real frequencies. The giant forces open up new possibilities for controlling micro- and nanoparticles through routing, trapping, and assembly.

Understanding the relationship between interfacial molecular structures and their frictional properties is one of the key issues in analyzing boundary lubrication mechanisms. In this study, the interfacial structure and frictional behavior of stearic acid (SA) solution were investigated using frequency-modulation atomic force microscopy (FM-AFM) and lateral force microscopy (LFM). FM-AFM visualized two distinct repulsive regions on steel and self-assembled monolayer substrates corresponding to vertically adsorbed SA molecules and a solvation layer of n-hexadecane (HD) molecules oriented parallel to the surface. Interaction force analysis revealed that the upper solvation layer was disrupted under approximately 15.6 pN loading. LFM measurements demonstrated a transition in the friction coefficient near 123 pN, indicating a load-dependent change in the interfacial configuration. A comparison of FM-AFM and LFM contact pressures using the Derjaguin-Muller-Toporov model showed that variations in Young's modulus and Poisson's ratio had a negligible effect on the estimated contact pressure, confirming the consistency of breakthrough pressure between the two measurement methods. These findings suggest that the low-friction regime under light pressure originates from the parallel alignment of HD molecules on the vertically oriented SA film.

This paper investigates the stability of triangular equilibrium points (L4, L5) in the generalized photogravitational restricted three‑body problem, considering the combined effects of radiation pressure and oblateness of both primaries. Using variational equations and characteristic roots, the linear stability conditions are derived. The analysis shows that triangular points are stable when the mass parameter lies within 0   < c, and unstable otherwise. The critical mass ratio c is obtained, and its range of stability is shown to increase, decrease, or remain unchanged depending on the sign of parameter p, which depends on radiation and oblateness coefficients. These results demonstrate that oblateness and radiation significantly modify the location and stability of triangular points compared to the classical restricted three‑body case, offering deeper insights into celestial mechanics and artificial satellite dynamics

Single crystals with tunable birefringence hold an exciting position in optical and photonic devices due to their exceptional ability of light manipulation. Although ferroelectric domains have been utilized to regulate physical properties, studies on tuning their birefringence by virtue of domain structure remain largely scarce. Herein, we have demonstrated the modulation of in-plane birefringence through manipulating domain structures in a 2D metal halide ferroelectric, (2-MBA)2PbCl4 (1, 2-MBA=2-methylbutylamine), which exhibits a phase transition at 314K with spontaneous polarization of 1.6µC/cm2. Crystal 1 exhibits controllable birefringence that can be modified by thermal and optical stimuli; this behavior directly involves with its ferroelectric properties. Notably, we have achieved unusual in-plane birefringence tuning via domain structure, which is further modulated by coupling domain manipulation with heat, light, and mechanical pressure. This work provides a new strategy for controlling birefringence, and advances the development of ferroelectric-based photonic devices for data storage and integrated optoelectronics.

ABSTRACT Single crystals with tunable birefringence hold an exciting position in optical and photonic devices due to their exceptional ability of light manipulation. Although ferroelectric domains have been utilized to regulate physical properties, studies on tuning their birefringence by virtue of domain structure remain largely scarce. Herein, we have demonstrated the modulation of in‐plane birefringence through manipulating domain structures in a 2D metal halide ferroelectric, (2‐MBA) 2 PbCl 4 ( 1 , 2‐MBA = 2‐methylbutylamine), which exhibits a phase transition at 314 K with spontaneous polarization of 1.6 µC/cm 2 . Crystal 1 exhibits controllable birefringence that can be modified by thermal and optical stimuli; this behavior directly involves with its ferroelectric properties. Notably, we have achieved unusual in‐plane birefringence tuning via domain structure, which is further modulated by coupling domain manipulation with heat, light, and mechanical pressure. This work provides a new strategy for controlling birefringence, and advances the development of ferroelectric‐based photonic devices for data storage and integrated optoelectronics.

Imaging polarimetry enables the spatially resolved investigation of cometary dust properties across different morphological structures. While cometary comae have been studied thoroughly in the pertinent literature, cometary tails have remained less explored. Comparing these regions can reveal differences in the size, structure, and composition of their dust. The goal of this study is to examine the size, structure and composition of the dust particles in the coma and in particular in the tail of the bright comet C/2023 A3 (Tsuchinshan-ATLAS) and to infer possible differences. For this purpose, we rely on the method of telescopic wide-field polarimetric imaging of the comet in the visible to near-infrared domain in order to obtain the dependence of the degree of linear polarization (DoLP) of the coma and tail on the phase angle across a broad range. An off-the-shelf industrial grade polarization camera was used in combination with a telescope of short aperture ratio. These observations are complemented by T-matrix and discrete dipole approximation modeling using the MSTM5 and DDSCAT software framework, respectively, for simulation of light scattering by dust particles of fractal agglomerate and agglomerate debris morphology. Our observations indicate that the coma exhibits a high maximum DoLP of 0.34, which is further exceeded by a factor of about two by the DoLP of the comet's tail. Our modeling results suggest a 50:50 olivine-carbon composition. The fraction of agglomerate debris was found to be 50% in the coma and possibly higher in the tail. The differences between the coma and the tail in the observed maximum DoLP and the phase angle at which it occurs can be explained by a predominance of particles with radii larger than 0.6 μm in the coma versus smaller sub-micrometer particles close to the Rayleigh limit in the tail, assuming power-law size distributions with exponents of 2 and 5, respectively. Our results are consistent with smaller particles being transported from the coma into the tail more efficiently than larger particles by the solar radiation pressure. The possibly larger agglomerate debris fraction in the tail than in the coma may be a dynamical effect due to the mass difference between porous and compact particles of similar size.

Context . Giant impacts between planetary embryos are a natural step in the terrestrial planet formation process and are expected to create disks of warm debris in the terrestrial regions of their stars. Understanding the gas and dust debris produced in giant impacts is vital for comprehending and constraining models of planetary collisions. Aims . We reveal the distribution of millimeter (mm) grains in the giant impact debris disk of HD 172555 for the first time, using new ALMA 0.87 mm observations at ∼80 mas (2.3 au) resolution. Methods . We modeled the interferometric visibilities to obtain basic spatial properties of the disk and compared these data to the disk’s dust and gas distributions at other wavelengths. Results . We detected the star and dust emission from an inclined disk out to ∼9 au and down to 2.3 au (on-sky) from the central star, with no significant asymmetry in the dust distribution. The radiative transfer modeling of the visibilities indicates the disk surface density distribution of mm grains most likely peaks around ∼5 au, while the width inferred remains model-dependent at the S/N of the data. We highlighted an outward radial offset of the small grains traced by scattered light observations compared to the mm grains, which could be explained by the combined effect of gas drag and radiation pressure in the presence of large enough gas densities. Furthermore, our SED modeling implies a size distribution slope for the mm grains consistent with the expectation of collisional evolution and flatter than inferred for the micron-sized grains, implying a break in the grain size distribution and confirming an overabundance of small grains.

We demonstrate an all-optically operated centimeter-milligram-scale torsion pendulum for atto-Newton (aN) level force detection, enabled by an ultrathin silica fiber and optical precooling in ultrahigh vacuum. Ten radiation pressure measurement experiments confirm the system's excellent linearity and accuracy in responding to external forces. The modulated intensity of the radiation laser ranges from 87.2 to 3.16nW, achieving a minimum external optical force amplitude of 13.3aN. Notably, our system delivers a force sensitivity of 3.7 fN/sqrt[Hz] and a force resolution of 6.6aN after 91.7h of integration at 6mHz. Compared with recent work by Sokhi etal. [Phys. Rev. Lett. 133, 083801 (2024)PRLTAO0031-900710.1103/PhysRevLett.133.083801], this represents approximately one order of magnitude higher force sensitivity and a 60-fold enhancement in force resolution. It not only extends the limits of light field coupling and detectability in optomechanical systems to the sub-nW scale but also establishes a new benchmark for macroscale low-frequency torsion pendulums. Building on these superior metrics, our approach opens a new avenue in the fields of tabletop gravity measurements and new physics searches at the aN level.

Light can be squeezed by reducing the quantum uncertainty of the electric field for some phases. We show how to use this purely quantum effect to extract net mechanical work from radiation pressure in a simple quantum photon engine. Along the way, we demonstrate that the standard definition of work in quantum systems does not capture the extractable mechanical work, as it does not reflect the energy leaked to these quantum degrees of freedom. We use these results to design an Otto engine able to produce mechanical work from squeezing baths, in the absence of a thermal gradient. Interestingly, while work extraction from squeezing generally improves for low temperatures, there exists a nontrivial squeezing-dependent temperature for which work production is maximal, demonstrating the complex interplay between thermal and squeezing effects.

Abstract The angular momentum of radiation from an arbitrarily moving relativistic charge is studied. A charge moving along a curved path can emit radiation with high orbital angular momentum. In the ultrarelativistic case a significant part of this angular momentum is the product of the radiation pressure by the instantaneous radius of the trajectory curvature. This is an ‘extrinsic’ part of the angular momentum of the radiation. The rest of the angular momentum which we denote as ‘intrinsic’ angular momentum can be associated with ‘twisted’ radiation. In this paper, we investigate the intrinsic and spin components of the canonical angular momentum and the angular momentum following from the symmetrized stress-energy tensor. Explicit expressions for the intrinsic and extrinsic components of the angular momentum of the radiation are obtained and studied.

Abstract High-quality proton beams with low energy spread and divergence are essential for applications such as fast ignition in inertial confinement fusion, isochoric heating of warm dense matter, and ion radiotherapy. Laser-driven ion acceleration via radiation pressure acceleration (RPA) offers promise for generating quasi-monoenergetic beams, yet it is often limited by instabilities and transverse particle expansion. Here, we propose an enhanced RPA scheme employing a mass-limited disk-shaped carbon-hydrogen (CH) target irradiated by an ultra-intense circularly polarized Laguerre-Gaussian (LG) laser pulse. The target's radius is matched to the LG focal spot to confine particles within the laser's ponderomotive potential well, thereby suppressing transverse instabilities. Additionally, the CH composition provides a buffering effect through heavier carbon ions, while the disk geometry minimizes cold electron reflux to sustain strong accelerating fields. Three-dimensional particle-in-cell simulations demonstrate the generation of a quasi-monoenergetic proton beam by employing a laser intensity of $\sim$5$\times$10$^{22}$ W/cm$^{2}$ with cutoff energy near 1 GeV, peak energy of 795.3 MeV, energy spread of 7.39$\%$, and divergence angle of 2.16$^\circ$. Compared to Gaussian laser counterparts, this configuration yields superior beam quality, with higher energy, improved monochromaticity, and reduced divergence. Parametric studies confirm the scheme's robustness across variations in density, thickness, carbon-to-hydrogen ratio, and laser intensity. These results highlight the potential of LG-driven disk CH targets for advancing compact, high-performance ion sources.

Photovoltaic development （PVPPC） has gradually become an important way to address climate change and achieve energy transition. Under the influence of PVPPC， a unique photovoltaic ecosystem is formed by the interaction between biological communities and inorganic environments within the photovoltaic field. Maintaining carbon balance is crucial for achieving the sustainability and health of the photovoltaic ecosystem. Net ecosystem carbon exchange （NEE） helps measure the carbon cycle balance of photovoltaic ecosystems， which is influenced by various environmental factors such as meteorology and soil. Taking the Gonghe photovoltaic park on the Qinghai Tibet Plateau as the research area， field-measured meteorological， soil， and flux data were obtained to analyze the mutual feedback response relationship between ecological environmental factors and the NEE of desert photovoltaic ecosystems. It was found that net radiation， air temperature， wind speed， relative humidity， and average atmospheric pressure were the five driving factors that had the greatest impact on the NEE of the desert photovoltaic ecosystems. A support vector machine （SSA-SVM） optimized based on the sparrow search algorithm was used to construct an ecosystem NEE estimation model under the influence of desert photovoltaic development. The model was used to predict the changes in NEE of desert photovoltaic ecosystems under different climate scenarios. The results showed that the model had good simulation performance for the NEE of the desert photovoltaic ecosystem， with an error controlled within 2%. Under three climate scenarios （SSP126， SSP245， and SSP585）， the carbon sink of the desert photovoltaic ecosystem during the growing season was higher than that during the non-growing season. The average annual NEE （calculated as C） was -37.96， -41.32， and -47.68 g·（m2·a）-1 and -12.69， -12.25， and -12.33 g·（m2·a）-1. The impact of climate change on carbon cycling during the growing season was significantly higher than that during the non-growing season， indicating that the desert photovoltaic ecosystem will still maintain strong carbon sequestration potential in the future. This study provides a new perspective for predicting carbon exchange in desert photovoltaic ecosystems and also provides data support for fields such as ecosystem stability assessment， environmental restoration， and climate change trend analysis.