Search Results (2,524)

Therapeutic interventions within the urinary system are often limited by the complex and tortuous anatomy of the renal pelvis and ureters, restricting access to deep regions and increasing the risk of mucosal trauma. In this study, we present a multifunctional, magnetically controlled ferrofluid droplet robotic platform engineered for high deformability and precision navigation. A custom electromagnetic actuation system was developed and optimized via COMSOL Multiphysics (version 6.3, COMSOL Inc., Stockholm, Sweden) simulations to generate programmable magnetic fields. Experimental validation in both simplified environments and anatomically realistic 3D-printed urinary tract models demonstrated the droplets’ capacity for controlled locomotion, reversible deformation, and traversing constrictions significantly smaller than their resting diameter. The droplets’ locomotion and extreme deformability are governed by the dynamic balance between the applied magnetic gradient forces, the restoring interfacial tension of the ferrofluid, and the fluidic viscous drag. Quantitatively, the droplets achieved robust translational velocities up to 260 mm/s under single-coil actuation (51 mT, 20 Hz) and 108 mm/s under a more stable dual-coil configuration (51 mT, 8.3 Hz). Furthermore, two clinically relevant functionalities were successfully executed: rapid vibration-induced release of encapsulated dye for targeted drug delivery, and the precise mechanical capture and transport of artificial kidney stones. These results establish a highly versatile platform for minimally invasive urological procedures, highlighting the immense potential of soft magnetic microrobotics for integrated therapeutic applications. Full article

Background. Walking is a fundamental human activity, vital for daily living, social connection, employment, etc. Methods. In the current study, we present a mathematical model of it, based on the planar double pendulum system influenced by gravity. For parameters of the pendulum, i.e., the characteristic of the limbs (thigh + shank), we use realistic mass–inertial parameters. The model incorporates anthropometric and inertial data specific to the average Bulgarian, Russian, German, and American male, including segment masses, centres of mass, as well as densities of the segments taken from experimental studies. Results. We derive the corresponding nonlinear differential equations governing the model. We solve them analytically, when possible, and, in the general case, numerically. For moderate initial angles (from the frontal plane) and angular velocities of the thigh and shank, the pendulum exhibits motion closely resembling natural human gait. The results for all nationalities considered are very close to each other. For comparatively slow walking speeds, the model provides realistic results. Conclusions. Our approach highlights how a relatively simple biomechanical model can capture essential features of human locomotion and provides a foundation for further refinement and comparison with more complex gait modelling techniques. Such modifications are outlined. Full article

Resolving inverse kinematics and evaluating constrained workspace remain challenging for multi-module cable-driven robots. This paper analyzes a dual-module cable-driven hybrid robot inspired by inchworm locomotion and proposes a new configuration-based decoupling strategy in which a scalar decoupling factor relates the dominant bending variables of the two modules and organizes the redundant inverse kinematics into C-shaped and S-shaped configuration sets. A physically constrained workspace evaluation framework that combines the decoupling rule with cable-stroke, unilateral-cable, joint-deflection, and anti-winding constraints is established. Monte Carlo sampling is used to extract the admissible position and orientation workspaces. The results show that the dual-module topology increases the lateral reach from 65.2 mm to 180.6 mm relative to a single module while retaining a yaw range of about ±80°. In addition, the workspace subsets associated with positive and negative values of the decoupling factor correspond to boundary-reaching motion and lateral body adjustment, respectively. These results show that the proposed decoupling parameterization provides a valid way to organize redundant configurations and to evaluate the workspace amplification introduced by serial coupling. Full article

Ontogenetic changes in bone microstructure provide key information on growth patterns and functional differentiation in birds. This study describes microanatomical and histological variation in the appendicular and axial skeleton across an ontogenetic series of Pygoscelis antarctica. Fifty-two thin sections were analyzed, representing five chicks of different ages, a juvenile, and an adult. Early stages are characterized by thin, highly vascularized cortices and extensive trabecular bone surrounding a large medullary cavity. The chick sequence shows progressive periosteal deposition, trabecular expansion, and increasing osteosclerosis. In the juvenile, secondary compaction and the initial development of the inner circumferential layer appear together with the onset of extensive remodeling. The adult specimen exhibits fully developed outer and inner circumferential layers, lamellar cortical tissue, and marked secondary remodeling, with differential medullary reduction among skeletal elements. Compared with Aptenodytes patagonicus, P. antarctica shows earlier and more pronounced medullary reduction and secondary trabecular compaction in the forelimbs, likely related to its shorter dependency period and earlier initiation of marine locomotion. In contrast, hindlimbs retain a medullary cavity and follow sex-linked pathways of medullary modification: males develop an inner circumferential layer, whereas females show trabecular bone followed by secondary compaction. Full article

We developed an ethogram of Conepatus chinga (South American hog-nosed skunk, chingue) from the continuous monitoring of a captive individual, with environmental enrichment, at a wildlife rehabilitation center in the O’Higgins Region, Chile. Using video camera traps, 17 days (408 h) of its activity were recorded, allowing us to identify daily activity patterns and times of exploration, locomotion, feeding, shelter use, and other relevant behaviors. The individual displayed a constant nocturnal activity pattern, starting around 9:00 P.M. and finishing at 5:00 A.M. The most frequent behaviors were walking and sniffing, evidencing active exploration guided by smell. No hunting/scavenging attempts were observed under these husbandry conditions. The primary refuge used was a small tunnel (approximately 30 cm deep) excavated under a wooden pallet covered with tree branches, which is consistent with refuges reported in wildlife. No visible defecation, urination, or musk release was recorded in the camera-trap footage. Given the limited observation coverage, we cannot determine whether these behaviors did not occur or occurred outside the recorded field of view. This study provides behavioral information and a descriptive baseline for this individual, including a pilot ethogram useful for research and captive management. Full article

In Chuckwagon racing, teams of four Thoroughbred horses pull wagons at high speeds. Movement symmetry is a key locomotion metric linked to force production, racing direction, and lameness. Racehorse symmetry in trot during on-track warmups and cooldowns was assessed. Over 10 days, 60 horses (average 8 per day) were fitted with Global Navigation Satellite Systems combined with Inertial Measurement Unit (GNSS-IMU) sensors. Weight-bearing asymmetry was quantified using the minimum difference (MnD) in vertical trunk displacement between diagonal limb pairs, and push-off asymmetry was quantified using the upwards difference (UpD). Absolute (mm) and normalized (% ROM) asymmetries were compared between warmups and cooldowns using linear mixed models. Mean MnD was similar between warmup (6.2 mm; 17.6%) and cooldown (6.4 mm, 19.7%). Mean UpD increased from warmup (11.3 mm, 31.7%) to cooldown (12.8 mm, 38.0%), with UpD% significantly higher in cooldown (p = 0.046). No other differences were significant (all p ≥ 0.202). One horse sustained a catastrophic musculoskeletal (MSK) injury. This horse’s UpD ranged from 3.3–29.7 mm (11.4–69.3%) during warmups and 24.3–25.5 mm (47.8–76.4%) during cooldowns. Push-off asymmetry may increase after Chuckwagon racing. The injured horse showed high asymmetries, but high values also occurred in uninjured horses. Further work needs to establish normal asymmetry ranges in Chuckwagon racing and identify patterns associated with MSK injuries. Full article

Equine swimming is increasingly used for injury prevention and rehabilitation, but objective analysis of movement during swimming remains limited compared to land-based locomotion. Spatiotemporal parameters are essential for evaluating therapeutic outcomes, yet capturing these parameters is technically challenging due to difficulties in observing limb motion in water. Inertial sensors, already widely applied in equine science, offer a promising solution for measuring swimming kinematics objectively. The objective of this study was to evaluate the reliability of inertial sensors placed on equine distal limbs in detecting key spatiotemporal events during swimming by comparing it with video-based detection made by veterinarians. For the duration of the hindlimb swimming cycle, 24 data values were analysed and showed an “excellent” agreement, with an intraclass correlation coefficient = 0.96, 95% CI: 0.904–0.983, and Bland–Altmann analysis showed an upper limit of agreement of 50 ms (95% CI: 70 ms, 30 ms) and lower one of −60 ms (95% CI: −40 ms, −80 ms). The estimates of the “swimming” duty factor of the hindlimb (n = 24) demonstrated “moderate” to “excellent” with intraclass correlation of 0.82 (95% CI: 0.625–0.920) and limits of agreement of 4.39% (95% CI: 6.21%, 2.53%) and −5.28% (95% CI: −3.42%, −7.14%). The results of the forelimb were mixed, suggesting that the cycle duration and “swimming” duty factor parameters determined for this limb should be used with caution. Overall, the findings confirm that inertial sensors, particularly on the hindlimbs, provide reliable spatiotemporal measurements and are well suited for studying equine swimming. Full article

This 2 × 2 factorial study examined the welfare and performance of finishing pigs at two group sizes (9 or 18 pigs) over 12 weeks. For each set of groups of either 9 or 18 pigs, half of the pigs in each group size were fed ad libitum, while the others received a mildly restricted ration. Treatments were assigned to 16 partially slatted floor pens in a randomized block design, with a floor space of 1.15 m²/pig. Except in Week 1, there were proportionally fewer pigs with ear (p = 0.020) and tail (p < 0.0001) bite marks in groups of 18 than in groups of 9. Ear bite marks declined over time in both group sizes (p < 0.0001). There was also a significant interaction between group size and week regarding severe bite marks on the ears (p < 0.0002). Tail bite mark prevalence increased over time in the smaller groups but decreased in the larger groups (interaction: p < 0.001). A higher proportion of pigs in smaller groups sought human contact in Weeks 1 and 6, but this measurement equalized by Week 10 (interaction: p = 0.008). There were proportionally more pigs with tucked tails in the smaller groups in Week 1 but not in later weeks (interaction: p < 0.0001). Group size did not influence pig cleanliness or locomotion disorders. Ad libitum (vs. restricted) feeding increased average daily gain (p < 0.001), feed intake (p = 0.002), and slaughter weight (p = 0.030). Results suggest better welfare in the larger than in the smaller groups. Full article

Background: In dual-task (DT) conditions, individuals must walk while simultaneously engaging in cognitive or motor tasks, which impacts gait performance, especially in older adults and individuals with Parkinson’s disease (PD). Gait impairments in PD under DT conditions have implications for intersegmental coordination. Research question: Intersegmental coordination and gait biomechanics during the DTs were compared between people with PD and older adults. Methods: Thirty-two individuals (16 PD, H&Y 1–3; and 16 older adults) participated in this study and were asked to walk under the following self-selected conditions: single task, DT with a math component, and texting on a cell phone. Spatiotemporal, angular, and intersegmental coordination data were collected using a markerless motion analysis system (OpenCap). Results: Dual-task conditions significantly affected spatiotemporal and kinematic variables, as well as intersegmental coordination. A significant task effect was observed for thigh–shank coordination, whereas no significant group effect was found for the main coordination outcomes. Significance: Significant task effects were observed for intersegmental coordination (thigh–shank CRP), with no significant group differences. The concurrent demands of processing visual and motor information for texting and walking lead to significant reductions in gait speed and lower limb movement, as well as altered intersegmental coordination, with task demands rather than disease status being the primary driver of coordination changes. Full article

Background: Race walking, an Olympic discipline, produces an increase in energy cost and a change in the recruitment pattern of muscle fibres compared with running, yet the cardiorespiratory responses of elite race walkers to severe-intensity exercise remain poorly characterised. Objectives: (i) To determine whether exhaustive exercise performed at vΔ50 elicits VO₂max in young elite race walkers, and (ii) to compare the temporal and metabolic profiles of this effort with those of similarly trained runners. Methods: Fourteen elite junior athletes (seven race walkers and seven runners) completed an incremental test to determine velocity at the lactate threshold (vLT), vVO2max, and VO2max, followed by a constant-velocity trial at individual vΔ50 performed to voluntary exhaustion on a 400 m track. Breath-by-breath VO2, heart rate, capillary blood lactate concentration, and time to exhaustion, time limit (Tlim) were measured. Results: At vΔ50 (≈94% vVO2max), the race walkers reached VO2max, with no detectable VO2 slow component (SC) in six of seven participants. In contrast, runners exhibited a significant SC (8 ± 3% of total VO2). The energy cost (EC) was 16% higher in race walking than in running (p < 0.01). Conclusions: In elite junior race walkers, it seems that vΔ50 reliably elicits VO2max primarily due to a high baseline oxygen cost rather than a progressive VO2 SC, contrasting with the kinetic response observed in running. These discipline-specific responses suggest that interval training in race walking should be prescribed using walking-specific thresholds. This study is preliminary, given the small sample size; further studies with larger cohorts are warranted. Full article

The exploration of lunar caves is a critical aspect of the space exploration program of the European Space Agency (ESA). To facilitate this mission, the DAEDALUS study investigated a novel spherical robot design in 2021. The proposed robot uses a unique telescopic linear rod mechanism to generate rotation and hence locomotion. This drive mechanism requires a dedicated control scheme to ensure both locomotion and simultaneously stabilization of the robot. The overall task of following a curved trajectory is also a problem that cannot be solved by simple algorithms. In this work, we introduce, calculate, and simulate a solution for these tasks, the Virtual Pose Instruction Plane (VPIP). The VPIP breaks the problem of multiple independent controllable rods down to two controllable parameters (roll and pitch of the plane), which control the linear motion velocity, balance and ultimately curvature motion of the robot. Initial simulations show that both speed and cornering can be controlled by the VPIP. Full article

Triplophysa yarkandensis (Cypriniformes: Nemacheilidae), a rare endemic fish in the Tarim River Basin, Xinjiang, China, plays a pivotal role in maintaining the stability of plateau saline–alkaline aquatic ecosystems, yet its survival is increasingly threatened by habitat salinization. However, the multi-dimensional synergistic adaptation mechanisms linking its phenotypic variation, intestinal structure, and associated microbial communities to extreme saline–alkaline stress remain poorly understood. In this study, we innovatively integrated morphological/intestinal histological characterization, 16S rRNA gene sequencing, and microbial ecological analyses (co-occurrence networks and assembly processes) to systematically decode its adaptive strategies. Results revealed that T. yarkandensis exhibits a streamlined body shape, morphological variability, and elongated intestinal villi that may support locomotion and nutrient/ion uptake under osmotic stress. Its gut exerts a stringent selective filter, driving distinct differentiation between water and gut microbial communities—with gut-enriched core taxa (Aurantimicrobium and Aestuariivirga) and functional pathways (unsaturated fatty acid biosynthesis and ABC transporters) specialized for osmoregulation. Notably, the water microbial assembly is dominated by stochastic processes, while the gut assembly relies on host-driven deterministic selection, forming a habitat-specific adaptive pattern. These findings uncover the synergistic adaptation system of host phenotype and gut microbiota for survival in extreme saline–alkaline habitats, advancing our understanding of fish–microbe co-evolution in extreme ecosystems and providing critical theoretical support for the conservation of rare plateau fish, as well as guidance for the utilization of saline–alkaline water resources in aquaculture. Full article

Despite the widespread use of Aloe vera extracts, their developmental toxicity in aquatic organisms remains poorly understood. This study investigated the effects of a commercial Aloe vera extract on zebrafish embryogenesis, focusing on developmental, morphological, behavioural, and oxidative stress-related endpoints. The 96 h-LC₅₀ was determined to be 0.03%. Embryos at 2 h post-fertilization (hpf) were exposed for 96 h to 0.0004% (LC₁₀) and 0.03% (LC₅₀). Exposure to 0.0004% caused no significant effects compared to controls. In contrast, exposure to 0.03% significantly increased mortality, reduced heart rate, impaired locomotion, and induced multiple malformations. Biochemical analyses revealed alterations in redox-associated biomarkers, characterized by unchanged ROS levels and mitochondrial activity, increased antioxidant enzyme activities (SOD, GPx, GR), and a decreased GSH:GSSG ratio. Lipid peroxidation levels were reduced, while a significant increase in DNA double-strand breaks (DSBs) was observed. Additionally, Nrf2 protein expression was upregulated at 0.03%. Together, these findings suggest concentration-dependent developmental toxicity correlated with alterations in redox homeostasis and genomic stability during early zebrafish development. This study provides new insight into the developmental hazard potential of a commercial Aloe vera extract in an aquatic vertebrate model. Full article

Background: Special Forces Operators often carry out missions in conditions where the use of motor vehicles is impossible. Additional external load across areas with variable inclination may reduce walking efficiency and consequently limit the combat capability of soldiers. The aim of the study was to determine how ground inclination affects the spatiotemporal structure of gait in Special Forces Operators (SFO) with different military loads. Methods: The study included 50 operators from Polish special forces units. Measurements of walking were performed using the h/p/cosmos Gaitway 1D + 3D treadmill. Tests were conducted at four uphill inclination levels: 0%, 5%, 10%, and 15%. Each participant completed trials both without external load and with a 27 kg load (helmet, tactical vest, and backpack). Statistical analyses were performed using the Friedman test, the Durbin–Conover post hoc test, and linear mixed models (LMM) to assess interaction effects. The Robinson Symmetry Index (SI) was calculated to assess asymmetry between the dominant and non-dominant limbs. Results: Increasing inclination caused statistically significant changes in the spatiotemporal structure of gait. The greatest modifications were observed at 10–15% inclinations, particularly under the maximum load of 27 kg. A significant shortening of step length and gait cycle time was noted, while cadence showed a slight upward trend, especially at a 15% inclination with the highest load. Step width remained stable. Conclusions: Ground inclination, especially when combined with the additional mass of military equipment, significantly affects the locomotion of Special Forces Operators. The stable SI values and consistent step width indicate a high level of gait stability and effective adaptive mechanisms. However, the extent of spatiotemporal modifications observed at inclinations of 10–15% with a 27 kg load may increase the risk of overuse injuries among operators. Full article

The precise fabrication and controllable actuation of magnetic microspheres hold significant application value in biomedicine, microfluidic chips and other fields. Based on femtosecond laser two-photon polymerization technology (FLTPP), two methods are adopted to prepare magnetic microspheres in this study. Magnetic microspheres are fabricated via photoresist modification and post-treatment processes. Meanwhile, a 3D magnetic actuation system composed of a three-axis movable magnetic drive module and a real-time imaging system is constructed, enabling the flexible 3D actuation and real-time dynamic monitoring and visualized observation of magnetic microspheres. The results demonstrate that the magnetic microspheres exhibit sensitive magnetic response characteristics. The constructed magnetic actuation system features large travel range (XY: ±6.5 mm, Z: 10 mm), high precision (20 μm) and flexible manipulation, enabling stable locomotion of the microrobots in straight channels, L-shaped channels, and square channels. This study provides a technical reference for the fabrication and manipulation of magnetic micro/nano devices, and lays a foundation for their subsequent integrated applications in microfluidic systems. Full article