Background/Objectives: In pole vaulting, the capacity to store elastic energy within the pole (E-pole) significantly influences performance. This study investigated the characteristics of E-pole storage by analyzing the box reaction force and vector angle. Methods: Eight male pole vaulters, including World Championships participants, were examined. A motion capture system (VICON) and force plates (Kistler) were used to measure the vector angle (angle between the compression force (CF) and box reaction force vectors) and horizontal velocity of the center of gravity (COG) (Vcogh). E-pole was calculated as the integral of the CF (estimated from the box reaction forces), and pole bending displacement. The relationships between each variable and the peak height of COG (HP) were assessed using Pearson's product-moment correlation coefficients. Results: HP correlated with Vcogh in the pole plant (PP) (r = 0.82) and E-pole (r = 0.94). Vaulters with a higher HP maintained a vector angle < 2 degrees between 20% and 80% of the pole bending phase, indicating closer directional alignment between the box reaction force vector and pole chord direction, whereas vaulters with lower HP exhibited larger vector angles (4-8 degrees), associated with a relative reduction in the axial component of force transmitted to the pole. Conclusions: A smaller vector angle effectively enhanced the CF, thereby increasing pole bending and promoting greater accumulation of E-pole. Therefore, maintaining a small vector angle may enable more effective force transmission along the pole chord, and vector angle characteristics and PP horizontal velocity may assist appropriate pole selection and training strategies to enhance elastic energy storage and performance.
Oxidation of ferrous Fe in Fe-bearing minerals during serpentinization has a key role in the production of H2, which is an energy source for microbial communities within the oceanic lithosphere. Serpentinization of the oceanic lithosphere occurs at various stages and temperatures, and in a range of rock types. However, the temporal and spatial variations in H2 generation during alteration of the oceanic lithosphere are poorly constrained. In this study, we investigated Fe partitioning and H2 generation in the oceanic lithosphere using samples of drillcore recovered from the lower crust and upper mantle sections at the Oman Drilling Project CM site, based on bulk-rock chemistry, thermogravimetric analyses, magnetic analyses, and bulk-rock and twodimensional imaging using Fe K-edge X-ray absorption near edge structure spectroscopy. Depth profiles of loss-on-ignition values indicate there was broadly consistent extent of serpentinization of the crust-mantle transition zone (serpentinized dunite) and mantle section (serpentinized harzburgite). The bulk-rock molar Fe3+/Sigma Fe ratios show no systematic variations with depth, but vary with rock type. The twodimensional X-ray absorption near edge structure imaging revealed variations in the Fe oxidation state in relation to rock type and mineral texture. The mesh texture serpentine has a similar Fe3+/Sigma Fe ratio regardless of rock type. Serpentine near magnetite veins that cut the mesh texture in dunite and harzburgite has higher Fe3+/ Sigma Fe ratios than mesh texture serpentine. The Fe oxidation state varies with texture, indicating that the redox conditions during serpentinization changed spatially or temporally. The H2 was generated mainly in the early-stage serpentinization characterized by mesh texture. The amounts of H2 generated during the mesh-texture serpentinization in the olivine gabbro (24-307 mmol/kgrock) and wehrlite (81-366 mmol/kgrock) are comparable to that in the dunite (143-393 mmol/kgrock) and harzburgite (71-151 mmol/kgrock). In addition to the H2 generated during mesh-texture serpentinization, up to 280 mmol/kgrock of H2 may have been generated during the later-stage formation of magnetite veins in dunite and harzburgite. Brucite in the serpentinized dunite and harzburgite contains a considerable amount of ferrous Fe. If the reaction of Fe-rich brucite to magnetite could have occurred in response to the increase in the water/rock ratio (W/R) that accompanied fracturing, it could have generated a considerable amount of H2. In contrast, during the later stages of serpentinization of the olivine gabbro and plagioclase-bearing wehrlite, the supply of silica from plagioclase suppressed the formation of magnetite and H2 generation. The depth variations of the amount and oxidation state of Fe in the lower crust and upper mantle sections of the Oman Ophiolite highlight the spatial and temporal heterogeneity in H2 production during the alteration of the oceanic lithosphere.
Mylonitic mantle peridotites exposed at the Tosa Megamullion in the Shikoku Basin, Philippine Sea, provide direct evidence for amagmatic ductile shear deformation of the upper mantle beneath a back-arc spreading center. Oceanic core complexes (OCCs), or megamullions, are dome-shaped structures formed by detachment faulting and occur locally along slow-spreading mid-ocean ridges and back-arc basins, where they expose fault rocks derived from ductile shear zones in the lower crust and upper mantle. The Shikoku Basin hosts several OCCs, including the Tosa Megamullion, which formed during the early stage of back-arc spreading. In this study, nine ultramafic rocks were collected from the Tosa Megamullion using the submersible Shinkai6500 during cruise YK23-05S. Although all samples were highly serpentinized, several preserved primary peridotitic textures were composed mainly of olivine, orthopyroxene, with subordinate clinopyroxene, plagioclase, and spinel. Seven samples exhibit well-developed foliation and porphyroclastic textures dominated by orthopyroxene porphyroclasts, ranging from rounded to strongly elongated forms, commonly showing microkinks and undulose extinction. Crystallographic preferred orientations (CPOs) of three representative samples, analyzed using SEM-EBSD, reveal E-type-dominant olivine fabrics characterized by the (001)[100] slip system, with a subordinate contribution from C-type (100)[001] slip. These CPOs suggest deformation under non-dry conditions involving moderate hydration and/or elevated differential stress. These results indicate that the ultramafic rocks from the Tosa Megamullion represent mantle-derived mylonitic peridotites formed by ductile shear beneath the spreading axis and subsequently exhumed under strongly magma-poor, amagmatic conditions. The Tosa Megamullion thus represents an amagmatic end-member of the OCC formation in back-arc basins, dominated by tectonic strain localization rather than by magmatic accretion.
Metasomatic reactions affect the mechanical properties of the interface between the mantle wedge and a subducting plate. However, the controls on fluid-mediated reactions that occur at the interface, involving mass transfer, volume change, and deformation, are poorly constrained. In this study, we experimentally investigated metasomatic reactions at the boundary between mantle rocks (serpentinite and harzburgite) and sedimentary rocks (quartzite or pelitic schist) at 500 °C and 1 GPa, using an assembly with a core of metasedimentary rock sandwiched between serpentinite and harzburgite. In all experimental runs, talc formed preferentially in the mantle rocks. In experiments using quartzite, talc formed along pre-existing fractures in serpentinite and as a layer within harzburgite, while no obvious alteration occurred in the quartzite. In experiments using pelitic schist, talc formed within tree-like fractures in serpentinite, whereas in harzburgite it formed as a layer or wedge-like filling. In the pelitic schist, albite porphyroblasts were preferentially replaced by Mg-rich saponite. These observations and mass balance calculations indicate that: (1) the solid volume-decreasing reactions in serpentinite accompanying reaction-induced fracturing and solid volume-increasing reaction in harzburgite caused the contrasting textures in the two rock types; and (2) Al-bearing minerals in the sedimentary rocks absorbed Mg, which facilitated the overall progress of the Mg-releasing, talc-forming reactions in the mantle rocks. These results suggest that compositional heterogeneity in subducting sediments can produce variations in the talc distribution and rheological properties at the slab–mantle interface, potentially affecting the location of episodic tremor and slip in a mantle wedge corner.
Deploying clinical prediction models across healthcare systems often fails when key training covariates are unavailable at deployment and labeled outcomes are limited in the target domain. For example, high-performing models for out-of-hospital cardiac arrest (OHCA) rely on detailed prehospital measurements routinely collected in high-resource settings but unavailable in many international registries. Existing methods either discard missing covariates, sacrificing predictive information, or rely on untestable assumptions about their target distribution. We propose DRUM (Distributionally Robust Unsupervised transfer learning with structurally Missing covariates), a framework that transfers prediction models to target populations where certain covariates are structurally absent and outcome labels are unavailable. DRUM partitions covariates into shared components (X), observed across all settings, and missing components (A), observed only in the source. Rather than imputing missing covariates, DRUM optimizes worst-case predictive performance over the unknown target distribution of A | X using a neural network generator, with a robustness parameter controlling allowable deviation from the source conditional. We further develop a bias correction procedure that reduces sensitivity to nuisance estimation error. Simulations show substantial improvements in both mean and worst-case prediction error under distribution shift. Applied to cross-national OHCA prediction, transferring models from a US registry to multiple Asian registries where prehospital variables are unrecorded, DRUM yields better-calibrated predictions and improved clinical classification performance across sites.
