Engraved ochres and ostrich eggshells from the South African Blombos Cave and Diepkloof Rock Shelter are among the earliest expressions of human symbolic behavior. They appear to document a continuous practice of mark-making across ∼40,000 years. During this time, the engraved markings change from simpler, unstructured patterns to more complex markings such as cross-hatchings. Previous work examining the cognitive implications of these changes concluded that the engravings were likely used as decorations and may have served as group identity markers, but not as denotational symbols. To inform discussions of the emergence of symbolic behavior, we conducted a two-part experimental study inspired by these engravings and based on the assumption that artifact use will motivate incremental adaptive refinements. Part 1 combined a delayed reproduction task with a transmission chain design to simulate an enduring mark-making practice. Eleven transmission chains were seeded with four drawings derived from the early Blombos and Diepkloof engravings and reproduced over eight generations. Transmission chain drawings showed a tendency to become increasingly regular, organized, and symmetric. Part 2 subjected a sample of the transmission chain drawings to a suite of psychophysical experiments to assess the cognitive implications of the accumulated structural changes. We found that the drawings became easier to discriminate, looked more like they had been intentionally made, and became easier to remember and reproduce, but there was no evidence of a systematic change in saliency or stylistic properties. Finally, we compared the results from the transmission chains with a similar analysis of the drawings derived from the original engravings. Although we observe interesting qualitative similarities between the original engravings and the experimental drawings, our findings suggest that cognitive biases and working memory constraints are not sufficient to generate the patterns observed in the archaeological record, highlighting the significance of social and functional contexts in shaping early symbolic artifacts. By integrating archaeological and experimental research, we can better inform inferences on sparse records of early symbolic behavior. Our study thus leads to a broader consideration of the role, strengths, and potential limitations of the transmission chain approach in analyzing trajectories of early symbolic behavior.
Paleolithic decorated caves are home to a priceless heritage, but their preservation depends on hydroclimatic conditions within the cave. In coastal areas, changing sea levels pose a further threat to caves, as the sea floods the karst and obliterates Paleolithic artefacts. In this paper, we study the case of the Cosquer Cave, a half-submerged coastal cave located in southeastern France, home to Upper Paleolithic archeological remains. This is a very special case, where the sea represents both an opportunity and a threat for the preservation of an archeological site. The cave is confined, submerged in its lower part, and embedded in a limestone massif with low permeability in the unsaturated zone. Several times a year, mainly in autumn, winter, and spring, air flows through the karstic massif, most likely below sea level, raising the cave's air pressure above atmospheric pressure. The resulting overpressure lowers the cave water level for weeks, keeping it below sea level and temporarily keeping the lowest wall paintings and engravings emerged. However, the oceanographic conditions that cause a pressurization event have not yet been described, although it is a key understanding to help preserve the natural heritage housed in the Cosquer Cave. Based on nine years of in situ continuous monitoring, we use descriptive statistics to decipher the oceanographic conditions controlling air inflow, air outflow, and absence of air flow through the submerged karst. We show that waves are the engine for the pressurization of the cave. The three main factors controlling air entrance are wave height, wave direction and seawater level. 90 % of air inflows coincide with significant wave heights exceeding 0.8 m. Additionally, air inflows are more efficiently caused by SSW and SW waves, propagating in a direction orthogonal to the cliff than by waves from the SE-SSE direction, propagating along the cliff. The minimum wave height required for air inflow to occur increases with sea-level rise, likely because submerged conduits become less accessible for air input. This study establishes a conceptual model of functioning for the natural hydrosystem of the Cosquer Cave, and provides the basis for further modeling and predictions according to scenarios of climate change and sea-level rise.
British anatomical physiology in the early 19th century evolved from the work of William Harvey, Thomas Willis, and William Hunter, who emphasized cerebral functional localization, integrating physiology and anatomy. This novel perspective was championed by Herbert Mayo (1796-1852). A student of Charles Bell at the Middlesex Hospital in London, Mayo subsequently became a surgeon there in 1818 and later a professor of anatomy and surgery. His experiments on the motor functions of the seventh cranial nerve and sensorimotor functions of the fifth cranial nerve brought him renown. Mayo, inspired by Johann Christian Reil, also conducted the first accurate brainstem dissections, developed innovative tissue preservation methods, and provided detailed descriptions of key fiber tracts. Mayo's 1822-1823 Anatomical and Physiological Commentaries and 1827 A Series of Engravings Intended to Illustrate the Structure of the Brain and Spinal Chord in Man accurately depicted the corona radiata, cerebellar peduncles, and uncinate fascicle. In his 1842 book, The Nervous System and Its Functions, Mayo discussed the localization of higher brain functions. His dissections remained unmatched until Josef Klingler's work in 1934. Despite the quality of his work, Mayo has been largely neglected, possibly because of his tumultuous relationship with Bell and later professional difficulties. Nevertheless, Mayo significantly contributed to white matter anatomy and led the search for cerebral localization, subsequently impacting neurosurgery. This article examines his life and work.
Root-bone interactions are common in buried skeletal remains, yet their diagnostic value remains largely unexplored because few controlled studies have linked root marks to specific plant types. Consequently, the potential of these marks to provide information about burial environments in archaeological, paleontological, and forensic contexts has been largely overlooked. Here, we present a long-term experimental study documenting root-induced bone modifications under natural field conditions in central Spain. Deer ribs were buried at various depths and for different lengths of time among three widespread Mediterranean trees and shrubs: holm oak (Quercus ilex), olive (Olea europaea), and grapevine (Vitis vinifera). Using optical and scanning electron microscopy, we identified distinct patterns of root engraving on cortical bone surfaces that varied by plant type. Holm oak roots produced sinuous, dendritic grooves; olive roots generated shallow, rectilinear markings; and grapevine roots formed linear-to-circular engravings, which were often associated with localized cracking. Mark intensity increased with burial depth and duration. These findings underscore the diagnostic value of root marks in identifying plant-specific signatures and offer a novel approach to recognizing plant activity in burial environments. This information improves taphonomic interpretations in various fields, including fossil reworking processes and forensic secondary burials.
Real-time, non-invasive biofluid monitoring is pivotal for precision medicine. However, conventional wearable sensing systems are constrained by their reliance on passive sampling, as well as barriers to design and fabrication. Integrating active sweat extraction with reliable enzyme-free multimodal sensing remains a critical challenge in wearable electronics. Herein, we report a wearable sweat monitoring system (WSMS) featuring a programmable metabolic flux sampling strategy, enabling precise and on-demand regulation of perspiration rates. By synergizing active thermal induction with microfluidic quantitative transport, the WSMS achieves controlled sweat rates in the range of 0.1-4 μL min-1·cm-2, with a maximum inducted sweat flux of 6.3 μL min-1·cm-2. This active sampling module is integrated with an enzyme-free electrochemical sensor array for the simultaneous detection of glucose, uric acid, and pH, exhibiting superior detection limits of 6.79 μM, 0.16 μM, and 1.3 pH units, respectively. More importantly, we demonstrate a laser-engraving manufacturing process capable of fabricating large-area sensor arrays (6 m × 0.5 m, ∼1340 units) within 4 h, bridging the gap to commercial scalability. Human subjects validation confirms the ability of the WSMS to accurately track sweat metabolites in both sedentary and exercise states. This work establishes a scalable, active-sensing paradigm that overcomes the limitations of passive environmental triggers, paving the way for non-invasive health monitoring and early diagnosis.
This paper presents a miniaturized, polarization-insensitive frequency-selective metasurface (FSMS) with stopband behavior for RF shielding applications. The FSMS is designed to suppress communication at 10 GHz frequency in the X-band. The design comprises a circular metallic patch with a staircase slot engraved in the center. The FSMS achieves an attenuation of 38.5 dB at the resonant frequency with a 10 dB suppression fractional bandwidth of more than 46%. The physical geometry of the unit cell makes it polarization-independent, and the angle of incidence has no effect on the stopband. The FSMS cell has overall dimensions of 0.3λo × 0.3λo × 0.05λo, where λo is free-space wavelength at the resonant frequency. Moreover, an equivalent circuit model (ECM) of the FSMS filter is developed to analyze its operation principle. An FSMS prototype is fabricated and tested for its performance, and the simulated and measured results show good agreement, making it suitable for selective electromagnetic interference (EMI) shielding applications.
Porcine acellular dermal matrix (PADM) is a commonly used xenogeneic wound dressing, but its natural structure is not conducive to cell infiltration and angiogenesis. In this study, we fabricated micro-structured porcine acellular dermal matrix (MPADM) by adopting a microstructural modification strategy, aiming to enhance the application potential of PADM in deep burn wound repair. Adopting laser engraving technology, biomimetic microstructures were constructed on the dermal surface of PADM, and medical silica gel was used to reconstruct the epidermal layer on the epidermal surface, resulting in MPADM. Through multiple methods, the microstructures of MPADM were observed, and its physicochemical properties were verified. Cell experiments confirmed the cytocompatibility of MPADM and the chemotaxis of its microstructures on cell growth. Animal experiments validated its inductive vascularization capacity and wound coverage effect. Regular groove structures were formed on the dermal surface of MPADM, which improved the material's water absorption capacity and water vapor transmission rate (WVTR) while maintaining good mechanical strength. The proliferation and migration of human umbilical vein endothelial cells (HUVECs) and human skin fibroblasts (HSFs) on MPADM showed an obvious aggregation tendency towards the grooves. Animal experiments demonstrated that the MPADM group exhibited faster cell infiltration and growth in the wound bed, enhanced vascularization capacity, and a lower level of inflammatory response. Microstructural modification can effectively improve the physicochemical properties and bioactivity of PADM, and MPADM exhibits great potential in promoting the repair of deep burn wounds. This microstructural modification strategy provides a new perspective for the functionalization of traditional xenogeneic skin materials.
Dual-function soft actuators that combine actuation and luminescence have broad application prospects in bionics, information transmission, and encryption. However, traditional dual-function soft actuators require multiple stimuli to perform their functions concurrently, and they are slow to respond. Consequently, developing actuation-luminescence dual-function devices based on a single stimulus that can achieve fast and stable actuation is of great significance. Therefore, in this study, a dielectric elastomer actuator was integrated with the electroluminescent device by constructing an asymmetric electrode structure to decrease the voltage and optimizing the ZnS:Cu2+ phosphor content to balance actuation performance and luminescent stability. The resulting all-in-one device exhibits simultaneous out-of-plane actuation and luminescence under a single electrical stimulus, with a fast response (∼160 ms), high curvature (4.71 cm-1), broad frequency response (0.5-15 Hz), excellent durability (20 000 cycles), and a synchronous luminous intensity of 72 nW/cm2. In addition, we developed laser engraving technology to fabricate bionic luminescent butterflies and multi-size array devices, thereby expanding the applications of the dual-function devices in fields such as bionics and multi-environment displays. This strategy provides new ideas for the development of multifunctional soft actuators.
Psychological stress is a common complex emotional state in humans, and if it accumulates over a long period of time, it can lead to serious psychological problems. The accurate detection of cortisol, an important indicator of the body's response to stress, is crucial for health assessment, psychological state analysis, and the diagnosis of stress-related diseases. To this end, this study prepared a wearable electrochemical aptasensor based on tetrahedral DNA nanostructures and gold nanoparticle-modified laser-engraved graphene (LEG), achieving simple, efficient, and noninvasive cortisol detection. Among them, LEG obtained by direct laser irradiation of polyimide is considered an ideal electrode due to its excellent conductivity. Using methylene blue (MB) as the signal molecule, the conformational change induced by the aptamer-cortisol binding alters the distance between MB and the electrode surface, thereby generating a detectable signal change. In addition, microfluidic devices can quickly collect sweat, effectively avoiding evaporation and contamination issues. By integrating laser-engraved electrodes with microfluidic devices, we have achieved in situ monitoring of cortisol in sweat. The sensor exhibits high sensitivity and excellent specificity, with a linear range of 1 pg/mL-1 μg/mL in artificial sweat and a detection limit as low as 1.06 × 10-2 pg/mL. Furthermore, this method has been successfully applied to the in situ detection of cortisol in sweat, demonstrating the broad application prospects of wearable sensors for detecting sweat biomarkers.
As a green energy technology, triboelectric nanogenerators (TENGs) convert mechanical energy into electricity and have gained significant attention in response to growing global environmental concerns. However, the widespread use of petroleum-based polymers as triboelectric materials in high-performance TENGs raises concerns over plastic pollution. In this work, we report a high-performance biodegradable TENG utilizing chitosan/laser-induced graphene (LIG) composite films as triboelectric layers. Modified chitosan substrates were first converted into LIGs via a convenient one-step CO2 laser engraving, subsequently incorporated into chitosan matrices to form homogeneous composite films. A TENG device was designed by pairing the LIG/chitosan composite film with the fluorinated ethylene propylene (FEP) film, and copper electrodes. The introduction of LIG effectively strengthens charge storage and dielectric properties of the chitosan matrix, thereby significantly boosting the triboelectric output performance. Experimental results demonstrate that the as-assembled TENG with an LIG concentration of 1 wt.% achieves a peak open-circuit voltage of 196 V and short-circuit current of 2.1 μA, with a maximum power density of 295 mW/m2. It can drive LED lights and small low-power electronic devices. Furthermore, the designed TENG device exhibits good biodegradability, flexibility, and stability, serving as a self-powered sensor for monitoring human joint movements. This work provides a simple and scalable strategy for integrating laser-induced graphene with biomass-based polymers, offering new insights into the design of high-performance, biobased triboelectric materials.
A novel number-color code system was developed to enhance brachytherapy catheter identification. Radiopaque buttons with unique number-color combinations and number tags were used for freehand and template-based catheters, respectively, replacing handwritten adhesive labels. A multidisciplinary survey was conducted to assess its accuracy, ease of use, speed, and user confidence and compare the new and previous methods after 1 year on a five-point Likert scale. Twenty-two staff members (5 radiation oncologists, 7 radiation therapy technologists, 4 nurses, 5 medical physicists, and 1 dosimetrist) participated. No incorrect identification was reported with either method. Personnel with direct applicator contact rated the new system higher on all aspects for freehand catheters. Medical physicists and dosimetrists also gave higher ratings but noted the radiologic invisibility of the colors and suggested shape coding. The most common issue was button positioning. For template-based catheters, number tags were preferred over adhesive labels. To address legibility issues, participants suggested enlarging tags or engraving numbers. The findings indicate that our novel number-color code system is simple and well-accepted by users. Further studies should define objective measures and develop more robust identification labels.
A freestanding manganese oxide nanoparticle–decorated laser-induced graphene electrode (MnOx-LIGE) for sensitive electrochemical detection of the organophosphate insecticide fenitrothion (FT) is reported. The electrode is fabricated via a one-step laser-engraving process on MnCl₂-doped polyimide films, enabling the simultaneous formation of porous graphene and in situ decoration with MnOx nanoparticles. Structural characterization confirms a three-dimensional porous graphene network uniformly decorated with MnOx nanoparticles, providing abundant active sites and accelerated electron transfer. Benefiting from this architecture, the MnOx-LIGE exhibits a wide linear detection range from 100.0 nmol/L to 250.0 µmol/L with a low detection limit of 13.66 nmol/L. Integrated with a portable electrochemical workstation, the sensor demonstrates excellent selectivity and stability. It achieves reliable recoveries of 102.4–104.2% in mango samples, highlighting its potential for rapid on-site monitoring of pesticide residues.
Atomic force nanolithography provides a precise method for sculpting magnetic thin films, enabling controlled engineering of magnetic anisotropy in soft ferromagnets at the microscale. We demonstrate that nanoscale groove arrays patterned into permalloy ( Ni 80 Fe 20 ${\rm Ni}_{80}{\rm Fe}_{20}$ ) films induce a robust in-plane uniaxial anisotropy, with the easy axis aligned along the groove direction. The effective anisotropy field is shown to increase with decreasing groove period and increasing engraving depth, offering continuous tunability of magnetic hardness within a single fabrication step. Artificially engraved microstructures further allow domain configurations and domain-wall trajectories to be directed along predefined pathways, exemplified by the creation of a chessboard-like magnetic landscape. Owing to its adaptability to diverse ferromagnetic materials and arbitrary corrugation geometries, this approach provides a versatile platform for tailoring in-plane magnetic anisotropy. Concrete applications are demonstrated in the design of magnonic elements and anisotropic magnetoresistance sensors.
Rheumatoid arthritis (RA) is a systemic autoimmune disorder wherein sustained, drug-free remission remains an elusive clinical goal. Frequent disease flares upon treatment withdrawal indicate that conventional immunosuppression fails to eradicate a deeply ingrained "pathogenic memory." In this Review, we provide a comprehensive framework illustrating how the hostile, nutrient-deprived synovial microenvironment acts as a metabolically restrictive microenvironment. Driven by "metabolic parasitism" and mitochondrial collapse, the massive accumulation of intermediate metabolites-most notably lactate, acetyl-CoA, and succinyl-CoA-transcends their traditional roles as bioenergetic waste to function as potent epigenetic regulators. We decode the emerging "PTM multiverse," highlighting how aberrant lactylation, acetylation, and RNA modifications (ac4C) persistently rewire chromatin architecture and critical non-histone sensors (e.g., cGAS). Amplified by hyperactive acetyltransferases and the hypoxia-induced collapse of Sirtuin deacetylases, these modifications engrave resilient "epigenetic scars" that lock innate immune and stromal cells into highly destructive phenotypes via trained immunity. We further integrate this localized articular inflammation into a holistic meta-organ model, tracing disease origins to mucosal gene-environment interactions and detailing systemic regulation via the gut-microbiota-joint axis and chronobiological rhythms. Ultimately, we explore how deciphering these integrated networks translates into next-generation prognostic biomarkers (e.g., AMPAs and GlycA) and heralds a critical therapeutic paradigm shift-from transient immune blockade to precise metabolic-epigenetic restoration.
Conifers are a challenging host for herbivores since their tissues are very low in essential nutrients but high in chemical defenses. For herbivorous insects, such as phloem-colonizing bark beetles, mutualistic fungi may improve their diet by providing a nutritious mycelium. A recent study revealed that two filamentous fungi are mutualists of the European fir engraver beetle Pityokteines vorontzowi, but a potential nutritional contribution of the fungi, as well as their capability to degrade plant antiherbivore defenses remains unknown. We analyzed the nutrient content of the fungal mutualists Ophiostoma piceae and Geosmithia sp. F1 and examined their ability to degrade the constitutive chemical defenses of silver fir phloem in comparison to other fungi. Both mutualists turned out to be rich in amino acids, sugars, and B vitamins and were found to efficiently deplete their phloem media of several defenses. Strikingly, O. piceae not only accumulated the highest amounts of the B vitamin nicotinic acid of the 17 tested fungi but also showed a high ability to deplete its medium of chemical defenses, similar to the behavior of the Ips typographus mutualist Endoconidiophora polonica. Beetle-vectored, non-mutualistic fungi isolated from P. vorontzowi showed similar capacities to deplete defensive compounds, whereas non-fir-associated fungi were less effective in reducing their concentrations in the phloem medium. The nutritious mycelium of O. piceae and Geosmithia sp. F1 and the ability of these fungi to deplete the medium of major fir defense compounds likely facilitates the colonization of silver fir phloem by P. vorontzowi.
Control of surface roughness during ultrashort laser processing remains challenging due to an incomplete understanding of the mechanisms governing its evolution, despite its critical role in determining surface properties. In this study, we analyze the evolution of the surface texture of laser-processed fused silica samples by performing spectral analysis. Spectral analysis reveals that surface roughness evolution is influenced by scanning strategy and its parameters, the presence of laser-induced nanoripples, and newly generated low spatial frequency features. Furthermore, we observe that texture evolves differently depending on the initial surface roughness due to varying attenuation rates of different spatial frequencies.
Monitoring cortisol levels is essential for understanding the body's response to stress. Traditional cortisol testing is confined to centralized labs, and current portable platforms are based on slow and complex assays. Here, we introduce a portable, disposable, non-invasive, and sensitive electrochemical sensor strip created using electropolymerized molecularly imprinted polymers (eMIPs) on laser engraved graphene (LEG) electrodes for rapid, simple, and reliable salivary cortisol detection. Herein, the characteristics of LEGs generated on a polyimide (PI) film with different laser processing parameters are also studied and optimized. The sensor quantifies salivary cortisol by selectively binding onto the cortisol-imprinted electropolymerized polypyrrole-Prussian blue (eMIP-PPy/PB) film on LEG electrodes. The PB redox probes embedded in the eMIP produce direct electrical signals upon cortisol binding, allowing sensitive and label-free amperometric detection. The developed cort-eMIP/LEG sensor strip displays an outstanding dynamic range (0.10 to 10 000 pg mL-1), a remarkable limit of detection (0.08 pg mL-1), and a strong correlation coefficient (R2) of 0.9983 (n = 4) for cortisol detection in human saliva. A rapid 3-minute analysis can more effectively measure cortisol levels in real-time than traditional methods. This sensor's performance was evaluated in human samples and validated two-way using enzyme-linked immunosorbent assays (ELISAs) and a third-party provider, Salimetrics, on 12 student volunteers exposed to varying stress levels. Results show an excellent correlation (r = 0.9948) between the developed sensors and standardized tests. The cort-eMIP/LEG cortisol sensor strip offers a simple, accessible, sample-to-answer diagnostic platform for stress monitoring.
In this study, a nonlinear finite element model of a 30 mm chain-gun barrel with progressive rifling was developed to investigate the influence of twist-law parameters on interior ballistic behavior and rifling-induced stresses. The progressive twist design was characterized using the twist exponent n and the muzzle exit angle αE. Their effects on projectile translation, spin evolution, and rotating-band engraving stresses were evaluated. The results reveal that muzzle velocity and axial acceleration are governed primarily by chamber-pressure loading and are largely insensitive to the rifling-geometry variations considered. In contrast, the twist exponent has a pronounced influence on spin-rate growth and on circumferential (θ-direction) stresses induced by rotating-band engraving. Circumferential stress exhibited strong sensitivity to twist intensity, with variations exceeding 30%, indicating that progressive twist design directly controls stress concentrations along the rifling lands. Among the examined cases, n = 1.6 produced a comparatively balanced stress response and stable spin-rate development. Based on a combined assessment using finite element stress analysis and the Miller gyroscopic stability criterion, a design range of n = 1.6 and αE = 7°-8° is recommended to achieve adequate gyroscopic stability while limiting excessive engraving stresses. The proposed modeling framework provides a quantitative basis for optimizing progressive-rifling barrels under high-pressure interior ballistic conditions.
This study aims to develop an automated system for measuring z-axis laser alignment in computed tomography (CT) using a Siemens CT phantom. The automatic method for measuring z-axis laser alignment involves many steps. The image of the second module of the Siemens CT phantom was segmented. The radius of the phantom image was measured. The profile of pixel value along the two engraved notches was made at the 97% of phantom's radius. The distance between two peaks of the pixel value profile, indicating the distance between two engraved notches, was measured. The distance was then converted from pixel units to millimeter units. This distance indicated the z-axis displacement (d). The automated method was evaluated for various set distances (d) ranging from 0 to 9 mm and for different slice thicknesses from 0.6 to 5 mm. The results of automated d measurements were compared to the manual d measurements. The coefficient of correlation (R) between automated and set d are above 0.99. Measured d values with the automatic method are slightly lower compared to those from the manual method. The average differences between automatic and manual d results range from 0.14 mm to 0.26 mm across various nominal slice thicknesses. The developed software for automated z-axis laser alignment offers reliable, objective, and accurate results. This approach has the potential to help medical practitioners perform quality control of z-axis laser alignment.
While the operational and funding structures of hospice care vary significantly across the globe, volunteers remain an indispensable component of hospice care teams. Existing research has examined volunteers' working experiences and training models; however, less is known about incentive strategies to promote sustained engagement. To explore the incentive strategies for hospice care volunteers through this qualitative case study in China and thus provide evidence to enhance global volunteer retention. A descriptive qualitative case study was conducted using participant observation and semi-structured interviews to explore hospice care volunteers' expectations for incentives, as well as administrators' perspectives on strategies to motivate and retain volunteers. Data were analyzed through conventional content analysis. Analysis yielded four themes and twelve sub-themes. (1) Material incentives, encompassing: Basic Subsidy Relief, Tangible Resources Empowerment, and Health and Welfare Support; (2) Organizational incentives, including: Engraving Volunteer Business Cards, Fostering Cohesive Teams, and Flexible Adaptive Management. (3) Spiritual incentives, encompassing: Multi-dimensional Value Recognition, Nourishing the Soul, and Intrinsic Motivation Enhancement. (4) Growth-oriented incentives, including: Knowledge and Skill Enhancement, Experience Sharing and Reflection, and Character Progression and Development. Organizational managers should develop incentive strategies for hospice care volunteers that align with their varied motivations for service. Given that hospice care volunteers generally prioritize spiritual fulfillment and personal growth, these strategies should focus on strengthening spiritual and growth-oriented incentives. Furthermore, incentive approaches should evolve to address the volunteers' changing needs at different stages, providing support for those with developmental aspirations to facilitate progressive growth in their roles.