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A bstract We have investigated the pseudo-scalar meson structure in the form of transverse momentum-dependent parton distribution functions (TMDs) in the light-front based holographic model and quark model. Starting from leading order, we have calculated all the time-reversal even TMDs for pion and kaon up to twist-4 in these models. We have shown the 3-dimensional structure as well as the 2-dimensional structure of these particles along with their average quark transverse momenta. The parton distribution functions (PDFs) of pseudo-scalar pion have been compared with E615 and modified E615 results. The sum rules, TMD transverse dependence, inverse moments and Gaussian transverse dependence ratio in these models have also been studied. Further, the transverse quark densities have also been analyzed in the momentum space plane for these particles. The higher twist kaon properties in light-front framework have been predicted for the first time in this work.

We address the most general periodic travelling wave of the modified Korteweg–de Vries (mKdV) equation written as a rational function of Jacobian elliptic functions. By applying an algebraic method which relates the periodic travelling waves and the squared periodic eigenfunctions of the Lax operators, we characterize explicitly the location of eigenvalues in the periodic spectral problem away from the imaginary axis. We show that Darboux transformations with the periodic eigenfunctions remain in the class of the same periodic travelling waves of the mKdV equation. In a general setting, there exist three symmetric pairs of simple eigenvalues away from the imaginary axis, and we give a new representation of the second non-periodic solution to the Lax equations for the same eigenvalues. We show that Darboux transformations with the non-periodic solutions to the Lax equations produce rogue waves on the periodic background, which are either brought from infinity by propagating algebraic solitons or formed in a finite region of the time-space plane.

A time-like curve on the unit pseudo-sphere can be a solition solution to the time-like curve shortening flow We first introduce the sufficient conditions for it to hold. And by studying the properties of the structure function of non-geodesic curves, I deduce some conditions to be satisfied by the structure function of non-geodesic curves when forming the time-like space plane, and then analyze the influence of the extreme value point of the structure function, and finally discuss the classification according to the time-like space-like situation of the parameter vector.

Waves entering a spatially uniform lossy medium typically undergo exponential intensity decay, arising from either the energy loss of the Beer–Lambert–Bouguer transmission law or the evanescent penetration during reflection. Recently, exceptional point singularities in non-Hermitian systems have been linked to unconventional wave propagation. Here, we theoretically propose and experimentally demonstrate exponential decay free wave propagation in a purely lossy medium. We observe up to 400-wave deep polynomial wave propagation accompanied by a uniformly distributed energy loss across a nanostructured photonic slab waveguide with exceptional points. We use coupled-mode theory and fully vectorial electromagnetic simulations to predict deep wave penetration manifesting spatially constant radiation losses through the entire structured waveguide region regardless of its length. The uncovered exponential decay free wave phenomenon is universal and holds true across all domains supporting physical waves, finding immediate applications for generating large, uniform and surface-normal free-space plane waves directly from dispersion-engineered photonic chip surfaces. Exceptional points in nanostructured lossy photonic waveguides lead to uniformly distributed losses and linear amplitude decay.

In this new era of space exploration, reusability and lower environmental impact are critical drivers in pursuing innovative solutions for access to space. One of these leading solutions is the Space Rider, a European reusable space plane with the ability to be both an “access to space” and a “return from space”. Following the lesson learned from the Intermediate eXperimental Vehicle (IXV) design and testing, the Space Rider will be equipped with a parafoil to enhance manoeuvrability during landing. Politecnico di Torino (PoliTO), in collaboration with Thales Alenia Space Italy (TAS-I), has developed an integrated tool to assess the landing performances of spaceplanes equipped with parafoils during conceptual design. The presented approach fuses sizing, dynamic models, guidance and control algorithms to provide a software suite for the rapid prototyping, sizing and performance assessment of spaceplanes’ parafoils. This paper details the implementation, mathematical background, validation and lessons learned behind the different software modules.

Specialists speculate that it might be similar to a US spaceplane, and it could have research or military uses. Specialists speculate that it might be similar to a US spaceplane, and it could have research or military uses. The Boeing X-37B Orbital Test Vehicle and four crew members in white full body suits

ObjectivesTo develop a routinely applicable severity index for the management of acute appendicitis in adults using combined clinical and radiological parameters and retroperitoneal space planes (RSP).MethodsTwo hundred consecutive patients with histologically proven acute appendicitis and available presurgical CT scans were analysed retrospectively. Two radiologists assessed all CT scans for morphologic sings of appendicitis and six RSP. Clinical parameters were age, body temperature, C-reactive protein (CRP), white blood cell count, and duration of symptoms. Radiological parameters were appendix diameter and wall thickness, periappendiceal fat stranding and fluid, intraluminal and extraluminal air, thinning of appendiceal wall, caecal wall thickening, appendicolith and abscess formation.ResultsOne hundred and three patients (51%) had histologically proven complicated appendicitis. Based on three clinical (age ≥52 years, body temperature ≥37.5°C, duration of symptoms ≥48 h) and four computed tomography (CT) findings (appendix diameter ≥14 mm, presence of periappendiceal fluid, extraluminal air, perityphlitic abscess), the APSI was developed using regression coefficients of multivariate logistic regression analyses with a maximum of 10 points. A score of ≥4 points predicted complicated appendicitis with a positive predictive value of 92% and a negative predictive value of 83%. Substantial to excellent interobserver agreement was found for the four radiological parameters of the APSI [intraclass correlation coefficient (ICC), 0.78-0.83]. The RSP evaluation presented no added value for the diagnosis of complicated appendicitis.ConclusionsUsing APSI, an accurate and simple prediction of complicated appendicitis in adults was possible. The RSP count was not useful for the diagnosis of complicated appendicitis.Key points• Appendicitis severity score provides an accurate and simple prediction of complicated appendicitis• Appendicitis severity score ≥4 accurately predicted complicated appendicitis (PPV 92%;NPV 83%)• Evaluation of retroperitoneal space planes was not useful in diagnosing complicated appendicitis

Carbon/Carbon (C/C) composites exhibit excellent mechanical properties at high temperatures, making them widely used in aerospace, such as the leading edges of spaceplane wings and the nose cones of hypersonic aircraft. However, damage caused by rain erosion to C/C composites affects their mechanical properties and poses significant challenges during operational service periods. A jet impingement test platform was employed to conduct single and multiple water-jet erosion tests on three-dimensional orthogonal C/C composite materials and to investigate the residual mechanical properties of the specimens after jet impact. The damage was characterized using optical microscopy, scanning electron microscopy, and X-ray computed tomography. The results showed that the damage types of the C/C composite materials under water-jet impingement included fiber bundle fracturing, delamination, and debonding. The extent of erosion damage was positively correlated with the jet velocity and diameter. The changes in the multi-jet damage indicated a cumulative expansion process, and z-directional fiber bundles exhibited superior resistance to jet impact damage propagation. The results of the three-point bending tests showed that the greater the initial impact damage, the lower the residual mechanical properties of the materials, and the residual strength of the specimen suddenly decreased when damage occurred at the back of the specimen.

Very High Energy Electron (VHEE) therapy is gaining attention as an innovative approach for treating deep-seated tumors, combining favorable dose deposition, sharp lateral penumbra, and compatibility with ultra-high dose rate (FLASH) delivery. A critical aspect of clinical translation is understanding how beamline components and high-density materials, such as patient implants or collimators, influence beam quality and secondary radiation production. In this work, we performed a comprehensive Monte Carlo investigation of titanium effects on collimated and magnetically focused VHEE beams using TOPAS/Geant4. A 10 × 10 cm², 150 MeV electron beam was directed into a water phantom containing a titanium insert at 5 cm depth. Phase-space planes were scored downstream of the insert to quantify electron, photon, positron, and neutron yields, energy spectra, angular distributions, and spatial fluence maps. Percentage depth–dose (PDD) curves were also evaluated. Titanium produced negligible energy degradation of primary electrons (<0.5% mean loss) but induced modest angular broadening, >70% photon yield enhancement via bremsstrahlung, and nearly two orders of magnitude increase in neutron production through photonuclear reactions near the giant dipole resonance. Focused beams demonstrated improved fluence recovery and maintained distal dose conformity. These results inform material selection, shielding design, and treatment planning for future VHEE radiotherapy systems.

Data-driven surrogate models have become increasingly important in aerospace engineering for the rapid prediction of aerodynamic characteristics. However, when modelling aerodynamic data with varying flight conditions and complex shape parameters, traditional surrogates - such as kriging and fully connected neural network (FCNN) - face major challenges, including high dimensionality, large variable disparities, and limited data availability. Specifically, kriging models suffer from inefficient training processes, while FCNN models struggle with diminished prediction accuracy when confronted with diverse input sets. To address these challenges, this paper introduces two improved surrogate models by incorporating variable sensitivity into the kriging and FCNN models. They employ the analysis of variance to identify the global sensitivity of input variables and utilise K-means clustering to group variables based on their sensitivities. For the kriging model, auxiliary parameters corresponding to the number of clusters are introduced to replace hyperparameters, accelerating model training while maintaining high accuracy. For the FCNN model, input variables are grouped based on their sensitivities, with specialised expert networks handling each group, and a gating network combining their outputs to improve prediction accuracy. The effectiveness of these methods is demonstrated through numerical function examples and two aerodynamic data modelling scenarios: the FDL-5A hypersonic vehicle and the Saenger aerospace plane carrier wing. Results indicate that the proposed approaches significantly enhance the kriging model's training efficiency, achieving a 98% reduction in hyperparameter tuning time compared to conventional method, with minimal sacrifice in accuracy. Simultaneously, the modifications to the FCNN model not only improve its prediction accuracy but also increase its overall practical utility in engineering applications.