Gravity, a constant force on Earth, fundamentally shapes plant architecture by directing organ growth, a process known as gravitropism. Shoots typically grow upward (negative gravitropism) and roots downward (positive gravitropism). In seed plants, gravity is sensed by specialized cells, including endodermal cells in shoots and columella cells in roots, collectively termed statocytes. The gravitropic response occurs through three sequential steps: gravity sensing/perception, signal transduction, and growth response. For over a century, the starch-statolith hypothesis dominated our conceptual understanding of gravity sensing, yet its molecular mechanism remained elusive. A molecular basis was established in 2023, when sedimenting amyloplasts were shown to repolarize LAZY proteins. This discovery allows us to molecularly define one type of gravity sensing as the process from amyloplast sedimentation (physical susception) to LAZY repolarization (physiological signal conversion). Meanwhile, evidence suggests the existence of alternative gravity-sensing pathways independent of the starch-statolith model, the mechanisms of which remain largely unknown. This review summarizes current knowledge and perspectives on gravity sensing, primarily in vascular plants, while integrating key insights from nonvascular lineages to provide an evolutionary context. Potential agricultural applications of gravity-sensing mechanisms are also discussed. 重力是地球上恒定存在的力，通过指引器官的生长方向从根本上塑造了植物的形态结构。植物对重力刺激产生定向生长反应的过程被称为向重力性。植物的地上部分通常表现为向上生长(负向重力性)，而根则向下生长(正向重力性)。在种子植物中，重力由特化的细胞所感知，包括茎中的内皮层细胞和根中的根冠柱细胞，它们统称为平衡细胞。向重力性反应通过三个连续步骤完成:重力感受、信号转导和生长反应。一个多世纪以来，“淀粉‐平衡石”假说主导着我们对重力感受的认知，但其分子机制一直未被揭示。2023年，淀粉体沉降被证明可使LAZY蛋白重新极性化，从而为这一机制奠定了分子基础。这一发现使我们能够从分子层面将一类重力感受定义为从淀粉体沉降(物理感知)到LAZY蛋白重新极性化(生理信号转换)的过程。同时，有证据表明存在不依赖于“淀粉‐平衡石”模型的其他重力感受通路，但其机制在很大程度上仍不清楚。本文综述了当前关于重力感受的研究进展与观点，主要以维管植物为对象，同时从演化视角整合了非维管植物的关键发现，并探讨了重力感受机制潜在的农业应用价值。.
Accurate perception of self-motion perception is critical for spatial orientation, especially in environments lacking visual or gravitational cues, such as during spaceflight. This study investigated how humans perceive passive whole-body rotation while free-floating in microgravity during parabolic flight. Six study participants were passively rotated about their yaw, pitch, and roll axes by an operator. The rotation angles ranged from 30 degrees to 420 degrees, and participants reported their perceived angular displacement after each trial. Visual and auditory cues were eliminated, and motion was recorded using inertial sensors. Errors between perceived and actual amplitudes were generally larger for pitch and roll rotations than yaw. Participants tended to inaccurately estimate the amplitude of both pitch and yaw rotations, with errors becoming more pronounced at larger angular displacements. Perception gain (the ratio of perceived to actual rotation) showed greater variability for pitch and roll than yaw. Overall, perception gain was higher for roll than for pitch or yaw, although this may have been influenced by the slower average angular velocities of these roll rotations. These findings suggest axis-dependent differences in motion perception in microgravity, likely due to the absence of otolith input and changes in tactile feedback, which underscores the role gravity plays in perceiving pitch and roll motion. Errors in estimating rotations could pose operational challenges for astronauts performing orientation-dependent tasks in low-gravity environments. These findings may also inform rehabilitation strategies for vestibular patients by determining the roles of cues from the semicircular canals and tactile feedback when compensating for impaired sense of gravity.
Endoscopic spine surgery relies on continuous irrigation to maintain visualization and hemostasis. Gravity-based and improvised high-flow systems may generate unstable or excessive pressures, potentially increasing the risk of neurologic complications. Pump-controlled irrigation offers regulated pressure delivery, but its comparative safety and pressure behavior remain incompletely defined. To systematically review the literature comparing controlled pump versus gravity-based or high-flow irrigation systems in endoscopic spine surgery, with a focus on pressure dynamics and pressure-related complications. This systematic review was conducted in accordance with PRISMA 2020 guidelines. PubMed, Embase, Web of Science, and Google Scholar were searched from database inception through January 2026 using predefined search terms related to endoscopic spine surgery, irrigation, and pressure dynamics. Eligible studies included experimental, animal, and clinical investigations reporting irrigation-related pressure measurements (epidural, intradural, intracranial) or pressure-associated complications. Two reviewers independently screened studies, extracted data using a standardized framework, and assessed risk of bias using the Newcastle-Ottawa Scale and MINORS criteria. Due to heterogeneity in study design and outcomes, a qualitative synthesis was performed. Eleven studies (a retrospective series, cadaveric, and living animal models) met inclusion criteria. Baseline epidural, intradural, and intracranial pressures were low and remained near physiologic ranges during routine operative conditions (approximately 12-18 mmHg). One study found pump-controlled irrigation produced significantly lower working-space pressures compared with gravity-based systems (12.10 ± 3.51 vs 23.86 ± 6.97 mmHg, p = 0.001). Outflow obstruction and dural disruption were consistently identified as primary drivers of pressure escalation. Intracranial pressure remained below 20 mmHg with patent drainage but increased to 86-90 mmHg when outflow occlusion and dural compromise coexisted. One study found symptom onset was associated with pressures exceeding 37 mmHg, with mean symptomatic pressures of 52.9 ± 9.2 mmHg. Neurologic complications, including seizures, were reported in 0.52% of cases and were most frequently associated with impaired drainage and dural violation. Findings are limited by heterogeneity in study design, pressure measurement techniques, and reliance on observational and experimental data. Direct comparative clinical studies are limited, and publication bias cannot be excluded. Irrigation during endoscopic spine surgery generally maintains pressures within physiologic ranges under conditions of intact dura and adequate outflow. However, impaired drainage and dural disruption can result in rapid and clinically significant pressure elevations. Pump-controlled irrigation appears to provide more stable pressure profiles than gravity-based systems, though safety is ultimately dependent on maintaining effective outflow. These findings highlight the importance of intraoperative vigilance regarding drainage patency and dural integrity to mitigate neurologic risk.
We present a novel method for recovering world-grounded human motion from monocular video. The main challenge lies in the ambiguity of defining the world coordinate system, which varies between sequences. Previous approaches attempt to alleviate this issue by predicting relative motion in an auto-regressive manner, but are prone to accumulating errors. Instead, we propose estimating human poses in a novel Gravity-View (GV) coordinate system, which is defined by the world gravity and the camera view direction. The proposed GV system is naturally gravity-aligned and uniquely defined for each video frame, largely reducing the ambiguity of learning image-pose mapping. The estimated poses can be transformed back to the world coordinate system using camera rotations, forming a global motion sequence. Additionally, the per-frame estimation avoids error accumulation in the auto-regressive methods. Experiments on in-the-wild benchmarks demonstrate that our method recovers more realistic motion in both the camera space and world-grounded settings, outperforming state-of-the-art methods in both accuracy and speed. We further introduce a Stationary Label Predictor (SLP) to estimate the motion stationary states of hands and feet. By producing sharper decision boundaries, the module mitigates unnatural artifacts such as foot-sliding and shows improved performance under fast-motion inputs. The code is available at https://zju3dv.github.io/gvhmr.
Building fire key factors are the fundamental control variables that govern both the initiation of fires and dynamics of propagation. The accurate identification of key factors in building fires is crucial for enhancing the effectiveness of fire prevention strategies. To improve the accuracy of key factor identification in building fires, a novel K-shell Entropy Gravity (KEG) algorithm that integrates multiple topological metrics is proposed in this study. First, a complex network is constructed to characterize the relationships among accident factors, where nodes represent influencing factors and edges denote their co-occurrence in fire incidents. Subsequently, considering the positional importance and core connectivity of nodes, the information influence and irreplaceability of nodes, as well as the collaborative coupling and nonlinear characteristic among multiple indicators, a composite attribute integrating K-shell value, information entropy difference, and total shortest path length is developed to quantify node importance, thereby capturing both the local coreness and the global influence of nodes within the network. Then, these metrics are incorporated into an established gravity-based model to comprehensively assess the influential scope of each node, and the results are employed to identify the key factors. Finally, the proposed method is compared with baseline methods based on the Susceptible-Infected-Recovered (SIR) model and network robustness evaluation using the California Building Fire Dataset (2012-2024). In addition, a sensitivity analysis is performed to investigate how the removal of key factors affects accident propagation. To further verify the robustness of this method, fire data from Alaska are applied for comparison, and an ablation experiment is designed. The results indicate that the KEG algorithm achieves superior accuracy in identifying critical factors and offers a reliable analytical tool for developing targeted fire prevention and mitigation strategies.
Rapid and accurate detection of foodborne pathogens in field settings remains challenging, as current methods typically rely on equipment-intensive and contamination-prone molecular steps. In this study, we propose a compact, fully integrated microfluidic system enabling automated magnetic bead-based DNA extraction and fluorescent loop-mediated isothermal amplification (LAMP) detection in raw samples. For efficient DNA extraction, a gravity-mediated magnetic microfluidic chip (GMMC) featuring a single flow channel was proposed. Reagents required for extraction were naturally settled at specific locations within the chamber via gravity, separated by mineral oil for liquid-phase partitioning. To enable magnetic bead transfer and execute the DNA extraction protocol, an automated control platform was designed with a single motor-driven magnet whose trajectory was constrained by a specially designed slot and two slide rails. Under the attraction of the magnet, the magnetic beads were driven along the preset trajectory. Therefore, DNA capture, washing, and elution can be completed sequentially. The DNA was amplified and detected using fluorescence-based qLAMP. Experiments confirmed that the system achieved highly sensitive detection of Salmonella enteritidis, Escherichia coli O157:H7, and Staphylococcus aureus in real food samples within 50 min, with detection limits as low as 10 copies. This self-contained, low-cost platform delivers an efficient solution for on-site food safety diagnostics, facilitating molecular detection in resource-limited settings and demonstrating potential for further development in point-of-care (POC) diagnostics.
Inversion of gravity data is an important method for investigating subsurface density variations relevant to mineral exploration, geothermal assessment, carbon storage, natural hydrogen, groundwater resources, and tectonic evolution. Here we present a scientific machine-learning approach for three-dimensional gravity inversion that represents subsurface density as a continuous field using an implicit neural representation (INR). The method trains a deep neural network directly through a physics-based forward-model loss, mapping spatial coordinates to a continuous density field without predefined meshes or discretisation. Spatial encoding enhances the network's capacity to capture sharp contrasts and short-wavelength features that conventional coordinate-based networks tend to oversmooth due to spectral bias. We demonstrate the approach on synthetic examples including smooth models, representing realistic geological complexity, and a dipping block model to assess recovery of structures at different depths. The INR framework reconstructs detailed structure and geologically plausible boundaries without explicit regularisation or depth weighting, while reducing the number of inversion parameters as the problem size grows bigger. These results highlight the potential of implicit representations to enable scalable, flexible, and interpretable large-scale geophysical inversion. This framework could generalise to other geophysical methods and for joint/multiphysics inversion.
We study an O(N) scalar multiplet nonminimally coupled to gravity and follow its renormalization-group (RG) flow in the vicinity of an interacting, nonperturbatively UV-complete scaling regime of scalar-tensor theory. In the broken phase, the radial mode mediates a universal Yukawa correction to Newtonian gravity, parametrized by a strength α_{Y} and range λ_{Y}. Imposing UV completeness-regular RG trajectories that reach the UV scaling regime-restricts the infrared data to a finite wedge, which maps to a narrow region in the (α_{Y},λ_{Y}) plane. Its complement is, therefore, ruled out by UV completeness alone. Remarkably, part of this theory-excluded domain lies below current experimental exclusion envelopes, so improved fifth-force searches can directly test and potentially falsify this class of UV-complete scalar-tensor models.
During spaceflight, the lack of gravity-induced hydrostatic pressure gradients in the body results in a headward fluid shift hypothesized to play a role in pathophysiological changes in the cardiovascular, ocular, and central nervous systems. Here, 24 subjects (n=8 control) underwent 60 days of strict 6° head-down tilt (HDT) bedrest, an analog of spaceflight where we tested the ability of daily 30 min artificial gravity (AG) exposure via short-arm human centrifugation (intermittent AG, n=8, and continuous AG, n=8) to reverse the HDT-induced headward fluid shift. Right internal jugular vein (IJV) cross-sectional area (2D ultrasound), and near-infrared spectroscopy measures of total hemoglobin concentration ([HbT]) in the prefrontal cortex and gastrocnemius muscle were measured before, during, and after centrifugation. IJV area decreased from 0.88 cm2 (95% CI: 0.62 - 1.13) pre-AG to 0.33 cm2 (0.24 - 0.42, P<0.001) in the first 2 min of continuous AG and remained partially collapsed while exposed to AG, with similar results seen during application of intermittent AG; [HbT] in the gastrocnemius muscle increased by 78.7µM (13 - 177 µM, p<0.0001) during AG, with smaller decreases of [HbT] in the head (p<0.001). Overall, AG resulted in a rapid shift of blood volume from the upper to the lower body; however, beneficial fluid shifting towards the lower limbs during AG appear to only be present during active countermeasure application, regardless of intermittent or continuous AG application. Thus, AG may be an effective countermeasure to physiological changes resulting from the spaceflight-induced headward fluid shift, dependent on duration and dose of AG.
This study investigates the impact of the India-ASEAN Free Trade Agreement (FTA) on bilateral trade flows through an augmented gravity model. Employing panel data from 1990 to 2022 with 330 observations, the analysis incorporates key determinants such as GDP and population of India and ASEAN countries, tariff rates, geographic distance, historical ties, and levels of democracy, trade openness, and globalization. To address heteroskedasticity and cross-sectional dependency, we utilize Generalized Least Squares (GLS) estimations. Our analysis examines both export and import volumes between India and ASEAN nations. Results from Ordinary Least Squares (OLS) and GLS estimations indicate that ASEAN countries' GDP positively influences trade volumes, while India's GDP demonstrates mixed effects. Larger populations in both India and ASEAN countries significantly contribute to trade. Tariff rates and geographic distance are found to have a negative effect on both exports and imports. Interestingly, shared colonial history and language positively impact trade, whereas a common border yields mixed effects across the models. Control variables reveal that trade openness, democracy levels, and globalization have a positive and significant effect on India-ASEAN trade flows. The FTA dummy is positive and highly significant, confirming that AIFTA has substantially increased India's bilateral trade with ASEAN. Based on these findings, we suggest that enhancing economic growth, mitigating geographic barriers, leveraging historical ties, and promoting trade openness and regional integration are essential strategies to bolster trade between India and ASEAN countries.
Irrotational monochromatic surface gravity waves possess a mean Lagrangian drift which transports mass and enhances mixing in the upper ocean. In the ocean, where many surface waves are present, it is commonly assumed that the mean Lagrangian drift can be computed independently for each wave component and summed. Here we show, using laboratory measurements and fully nonlinear simulations of two-dimensional steep focusing wave packets, that this assumption underpredicts the average transport in regions of wave focusing by up to . To explain these enhancements, we derive a new exact method for constraining the local mean Lagrangian drift in general flows by working in the Lagrangian reference frame. From this method, we derive an expression for the local mean Lagrangian drift in deep-water narrow-banded wave fields governed by the nonlinear Schrödinger equation (NLSE) that predicts near-surface enhancements when waves focus and steepen. The theoretical predictions of the local transport agree with the laboratory measurements, particularly for smaller bandwidth packets where the NLSE approximation is most valid. These findings highlight that it is the local steepness of the wave field, not just the sum of the steepnesses of the linear (non-interacting) wave components, which sets the strength of these enhancements.
This paper introduces an enhanced gravity model that incorporates a coopetition framework and a K-nearest neighbor (KNN) spatial weighting scheme to analyze the synergistic evolution of China's five major coastal port clusters. Given the ongoing restructuring of global supply chains and the increasing focus on regional port integration, this research addresses a subject of considerable contemporary relevance and practical significance. Drawing on panel data spanning 2015 to 2024, we develop an evaluation framework comprising eight key indicators and employ the entropy weight method to quantify their respective contributions. Empirical findings identify inland waterway mileage, berth capacity, and railway mileage as the most influential drivers of port cluster synergy. The analysis reveals a consistently strengthening synergistic linkage between the Bohai Rim Port Cluster and the Pearl River Delta Port Cluster, while the synergy between the Bohai Rim and Yangtze River Delta port clusters demonstrates a gradual weakening trend. This study offers a methodological advancement for assessing interactive dynamics among port groups and yields strategic insights to inform policies aimed at fostering coordinated port development.
We demonstrate that the phase space of the soft sector of asymptotically flat gravity in four spacetime dimensions can be identified with that of a spherically symmetric finite casual diamond in Minkowski spacetime. The leading soft graviton mode is geometrically identified with the radial fluctuation of the causal diamond size, while the Goldstone mode involves both the radial fluctuation and its symplectic partner. This allows us to relate the radial fluctuations of the causal diamond with the asymptotic transverse fluctuations parametrized by the soft modes.
Türkiye is home to numerous historical masonry structures that reflect its rich cultural heritage. Understanding the structural behavior of such buildings under various loading conditions is crucial for identifying damage mechanisms and supporting effective conservation strategies. While previous studies have primarily focused on the effects of earthquakes, the impact of continuous vertical loads, such as gravity and snow, has been relatively overlooked. This study investigates the structural behavior of the St. Bartholomeus Church under static and dynamic loading conditions. After conducting material characterization and structural assessments, three-dimensional finite element model was developed using SAP2000 v20 and ANSYS v19 to identify the difference in the results. The structure was analyzed under its own weight, snow load, and seismic excitations to evaluate its response and identify potential sources of damage. The results indicate that the structure exhibits significant tensile and shear stress concentrations even under its own weight. When snow loads are included, these stress levels increase significantly, particularly in the roof and west wall. This suggests that damage could initiate under vertical loading conditions. Seismic effects could further exacerbate these effects and contribute to the progression of damage. These findings indicate that dead and snow loads can significantly contribute to the deterioration of abandoned historical masonry structures, and that these factors must be considered alongside seismic effects in structural assessments. Accordingly, structural reinforcement measures may be necessary to enhance stability and resilience, particularly in the event of a future earthquake.
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in Emilia-Romagna Region (Northern Italy), over 60% of emergency room (ER) visits involve low-complexity cases, with a hospitalization rate of less than 5%, in line with the national trend. In 2023-2024, to improve system efficiency and ensure more appropriate use of hospital resources, the Region established 42 Centres for Assistance and Urgency (CAU) to handle minor emergencies. to estimate the impact of this reorganization on healthcare service accessibility developing a gravitational model based on an adapted version of the Modified Huff Three-Step Floating Catchment Area (MH3SFCA). an observational and modelling study was implemented and adapted to the healthcare context, focusing on emergency department (ED) and Centres for Asisstance and Urgency (CAU) access flows in the Emilia-Romagna Region in 2024. The study was structured into three phases: 1. calculation of access probability (using the Huff probability model); 2. estimation of the regional network's service capacity; 3. computation of the accessibility index to the network. To implement the gravitational model, distance matrices were employed - constructed on road networks - to accurately estimate travel times and distances between municipalities and healthcare facilities. admission to ERs CAUs in Emilia-Romagna in 2023-2024. theoretical accessibility to network facilities, expressed as a composite municipal-level index; model performance assessed through R² and Weighted Mean Absolute Error (WMAE). the model integrates variables such as travel times, mobility propensity, and inter-municipal attractiveness. The results show good predictive performance and an accessibility distribution with higher values in peripheral municipalities. the proposed model serves as an operational tool to support healthcare planning by assessing territorial equity in access to services and simulating alternative scenarios in the planning process.
Cerebral palsy (CP) is one of the most common causes of motor disability in childhood. Since CP is a corollary of brain damage, persistent treatment should accompany alterations in brain functional activity in line with clinical improvements. A total of 14 children with spastic hemiplegic CP were randomly divided into 2 groups. The training group (8.5 years) underwent 45 min anti-gravity treadmill training sessions 3 times/week for 8 weeks, while the control group (8.2 years) received the same amount of occupational therapy (OT). Functional magnetic resonance imaging (fMRI) was conducted to quantify brain activation during the performance of passive tasks, including ankle plantarflexion to dorsiflexion and knee flexion to extension over the range of motion. Walking capacity was assessed using the timed-up-and-go, 10-m, and 6-m walking tests. All evaluations were performed before and after training and compared between the two groups. This study could detect the signatures of ankle and knee passive movement tasks in the fMRI and characterize them in terms of activated voxels. The pre-post activation changes following the completion of the training course showed that the elicited motor cortex activation was greater for the ankle than the knee tasks. For the ankle, the primary motor cortex, precentral gyrus, and corpus callosum showed significant enhancement in most study participants. The results indicated 16.1% more active voxels in the study than control groups. Similarly, clinical outcome measures improved over twice as much in this group. Anti-gravity treadmill training could be a potentially effective therapeutic intervention for improving gait and balance impairments in children with CP.
When intercepting a moving object, ocular and hand movements are often associated. The neural control of both tasks is known to combine sensory information with predictive mechanisms. When interacting with free-falling targets, the brain may integrate visual signals with an internal representation of gravity, which can be recruited also in virtual settings, when contextual cues about the environment naturalness are available. This internal representation may be shared between oculomotor and manual control. At the same time, concurrent execution of hand and eye movements may alter the oculomotor performance. Here, we investigated how task demands and visual context naturalness affected the relative weighting of sensory feedback and predictive information for ocular tracking control. Participants tracked targets, either congruent with gravity or perturbed with altered gravity, which were projected on either pictorial or neutral background. To enforce prediction, targets were occluded for variable intervals. One group of participants performed only ocular tracking, while another group also intercepted the targets. In general, subjects' ocular tracking depended on the target acceleration and the visual context. The effects of gravitational expectations were more evident for the time dependent oculomotor indexes (smooth pursuit and saccadic τ) and with the pictorial background, reinforcing the idea that recruitment of the gravity prior depends on the visual context. Instead, for post saccadic error and smooth pursuit gain no clear dissociation emerged between the effects of acceleration and velocity. Finally, participants who only tracked the target showed strong reliance on gravitational expectation early on, by displaying systematic oculomotor changes with the target acceleration since its perturbation. Instead, participants that also intercepted the target relied less on the gravity prior until the target occlusion, after which they showed oculomotor performance compatible with gravitational expectation. Thus, concurrence of ocular tracking and manual interception strongly influenced the temporal recruitment of the gravity prior.
Biological phase changes provoked by stress, such as vitrification or gel-sol transitions, enable many organisms, including extremotolerant tardigrades, to enter quiescent states and survive extreme environmental conditions. Protein-driven phase transitions are hypothesized to produce large-scale changes in intracellular viscosity, allowing tardigrades to survive extreme stresses such as desiccation. We report that the tardigrade Hypsibius exemplaris undergoes both large-scale and local increases in intracellular viscosity following exposure to anoxic and hyperosmotic stress. Such dramatic shifts in cellular viscosity would be expected to enhance cellular resilience to physical force. Indeed, we found that tardigrades can survive, behave normally, and reproduce after exposure to the highest simulated hypergravity (HG) achievable in an ultracentrifuge (one million times Earth's gravity). In contrast, Caenorhabditis elegans , a similarly sized animal, does not survive these extreme forces owing to loss of cellular integrity. Remarkably, tardigrades frozen during exposure to extreme hypergravitational force show minimal disruption of fine cellular ultrastructure and little evidence of stratification of cellular components whose density varies by nearly a factor of two. Further, exposure to anoxia, hyperosmotic stress, and HG all result in a large increase in reactive oxygen species (ROS), which is required for survival under these extreme environments. Inhibition of NADPH oxidase (NOX) suppresses survival both to HG and hyperosmotic stress. Our findings suggest that intracellular viscosity changes in response to multiple extreme stresses may underlie the resilience of these animals to extraordinary physical stress, and that survival in or recovery from these states relies on ROS signaling via NADPH oxidase. Tardigrades are renowned for surviving conditions that are lethal to nearly all other life forms. We reveal two mechanisms that support this resilience: intracellular viscosity changes and NADPH oxidase-mediated ROS signaling. Through direct assessment of the effects of altered cellular material properties, found that tardigrades are resilient to forces up to one million times Earth's gravity, establishing them as the most hypergravity-resistant animal currently known.