Abstract Stewardship is broadly defined as ‘universal responsibility of humanity to care for the planet, to ensure that it can continue to provide the essential natural resources for life’. Stewardship practices shape ecosystems, create diverse biocultural landscapes, and can enhance the productivity, availability and health of plants used by Indigenous Peoples for traditional foods, fibres and medicines. In this paper, we argue that care is one key component that differentiates Indigenous stewardship from other forms of resource management and has the potential to cross cultural and institutional boundaries. We consider how care, which includes many of the principles, motivations and intentions behind Indigenous stewardship, is applied in cultural plant‐rich ecosystems maintained by Indigenous communities in Southwest Alaska, Northern California and Coastal Maine. This work emerged from collaborations among allied researchers, Indigenous gatherers, and Indigenous scholars, spanning three cultural plant‐focused projects. Collectively, we conducted 109 interviews with Indigenous plant stewards, many out on the landscape. We use qualitative coding analysis and discussion to identify key elements of care in Indigenous environmental stewardship. Our results highlight the many, sometimes subtle and nuanced, ways in which aspects of care motivate and shape stewardship. We group these components of care into themes that are part of our proposed conceptualization of care as a central tenet of Indigenous plant stewardship. We focus on responsibility and relationship as key elements of care; these are precursors to the privilege of harvesting cultural plants. Plants are cared for as family members, and there are transferable elements of care among human and plant kin. Care transcends time, being received from ancestors and carried out for those yet to come. In some places where colonization has interrupted care practices, Indigenous caretaking today is part of healing and reconciliation. Our conceptualization of care as one part of Indigenous environmental stewardship has the potential to shift collaborative work, community dynamics and societal worldviews related to environmental stewardship. Read the free Plain Language Summary for this article on the Journal blog.
Full-field methods such as Electronic Speckle Pattern Interferometry (ESPI) and Digital Image Correlation (DIC) emerge as promising alternatives to strain rosette in the hole-drilling method, each with its own advantages and limitations. In particular, DIC stands out as a method requiring minimal (and cheap) specimen preparation; however, its sensitivity is approximately one order of magnitude lower than that of conventional strain gauge techniques. We address two fundamental questions. First, how can the inverse problem of the hole-drilling method be systematically approached outside the well-established framework of ASTM E837, which provides users with comprehensive guidance, including automated regularization procedures? Second, thanks to full-field measurement techniques, is it possible to retrieve stress distributions at a spatial resolution finer than the drilling step? We revisit the theoretical development of the inverse problem, aiming to directly identify the residual stresses from raw images, without intermediate pre-processing of the displacement fields. We introduce the L-curve method-well established in other scientific domains-as a rational tool for the choice of the regularization parameter. Finally, we show that, in principle, it would be possible to identify the entire stress distribution from a single drilling increment. We perform a deep rolling treatment on an aluminum specimen and compare the residual stresses identified using both a strain gauge rosette and DIC. We demonstrate that the proposed framework yields results comparable to those obtained using strain gauge rosettes, while minimizing user-dependent arbitrariness. Furthermore, we show that depth super-resolution of at least a factor of two is already achievable with current technological capabilities.
Ultrafast laser technologies have greatly benefited from the unique properties of optical solitons, which enable stable pulse propagation and waveform control. While conventional solitons are well described by the balance between second-order group velocity dispersion (GVD) and Kerr nonlinearity, higher-order dispersion introduces richer dynamics. In the regime dominated by positive fourth-order dispersion (PFOD), the formation and evolution of dissipative pure-quartic solitons (DPQSs) and their molecular states in nonlinear polarization rotation (NPR) mode-locked fiber lasers remain insufficiently explored. Here, we numerically investigate the generation mechanisms and dynamic behaviors of DPQSs and bound-state molecules. The results reveal that pulse characteristics are determined by the interplay among FOD, nonlinearity, gain saturation, and spectral filtering. Increasing PFOD raises the pulse-splitting threshold, supporting higher-energy single pulses, whereas larger gain saturation energy facilitates soliton molecule formation. The spectral filtering bandwidth further governs the transition from single-pulse to multi-pulse regimes: a moderate bandwidth enhances pulse coupling and stabilizes bound states, while an excessively broad one weakens spectral confinement, leading to instability. These findings deepen the understanding of dissipative soliton dynamics in PFOD-dominated systems and provide theoretical guidance for designing high-energy, stable ultrafast fiber lasers.
This study focuses on the mechanical behavior of slab track structures within railway tunnels that traverse fault zones. By combining the concrete damaged plasticity (CDP) model with the finite element method, a coupled simulation model of the slab track-tunnel-surrounding rock system has been established. The analysis primarily centers on the effects of fault dislocation on the stress, deformation, and damage characteristics of both CRTS II and CRTS III slab tracks, with the former featuring longitudinally connected track slabs and the latter characterized by unit-type track slabs. The results demonstrate that under normal fault dislocation, track irregularity, structural damage, and the interlayer gap all increase as fault displacement grows. Owing to its relatively higher structural stiffness, the CRTS II slab track is more susceptible to stress concentration, thereby leading to more severe damage to the track slab and base plate, as well as larger interlayer gaps. Specifically, the maximum damage variable of the track slab in the CRTS II slab track is 16 times that of the CRTS III slab track, and its maximum interlayer gap is 1.3 times larger than that of CRTS III slab track. By contrast, the unit-type design of the CRTS III slab track endows it with better adaptability to foundation deformation and mitigates stress concentration. However, this design leads to more increased track irregularity. The maximum upward bending deflection of the rail on the hanging wall side of the fault in the CRTS III slab track is twice as large as that of the CRTS II slab track. Under reverse fault dislocation, compared to normal fault dislocation, the compressive effects reduce structural damage, yet the trends of deformation and interlayer contact remain consistent with the variation of fault displacement. This research offers valuable insights for the design and maintenance of high-speed railway tracks within tunnels that cross fault zones.
To further elucidate the influence of cleaning mechanisms on the effectiveness of laser paint removal, this study presents a comparative analysis between numerical simulations and experimental results for multipulse laser cleaning at three longitudinal overlap rates. The results indicate that under the shielding effect of the laser plasma, the experimental removal depth is consistently lower than the numerical simulation results for the same laser parameters, and intermittent ablation craters are formed in certain regions of the cleaned surface. As the longitudinal overlap rate increases, the residual primer thickness gradually decreases, the deposition amount of topcoating colourant and functional oxides gradually increases, and the ablation behaviour progressively strengthens. The thermal stress has little effect on the removal depth but can induce cracking in the residual primer and the exposed oxide film. The superposition of the remaining plasma enhances the plasma impact and shielding effects. In the laser irradiation zone, the three cleaning mechanisms of ablation, thermal stress, and plasma impact are coupled and interact. In the nonirradiated zone, the plasma impact and its induced secondary ablation and thermal stress mechanisms are coupled and interact.
