Flapping Counter Torque (FCT) is an intrinsic mechanism in flapping-wing flight of animals, where the rotation of an animal's body creates asymmetric left-right wing motion, leading to a counter torque that opposes the body rotation. FCT corresponds to a passive damping effect that could be harnessed for disturbance rejection and flight stabilization, but its role in fast maneuvers remains unclear. In this work, we used the reconstructed escape flight of hummingbirds to test the effects of FCT in fast maneuvers, which features rapid and simultaneous body pitch, roll, and yaw, and linear accelerations. In addition to Computational Fluid Dynamics (CFD) simulation of free-body flight, we also performed a fixed-body CFD simulation by removing the body-rotation induced wing velocities while retaining the wing kinematics relative to the body. The aerodynamic torques from the fixed-body flight are considered active torques, and the differences between the free and fixed-body flights are considered the FCTs. Our results show that the FCT in the roll axis is particularly strong during downstroke, due to the large bilateral wing velocity asymmetry associated with the body roll, as well as changes to the wings' angle of attack by body rotations around the other axes. To overcome the strong damping and sustain the rotation, the bird utilizes an active torque to overcome the FCT during downstrokes and also employs the wing kinematics that would incur less FCT during upstrokes. Overall, the hummingbird is able to alleviate and control the FCT and still achieve great agility in the maneuver.

We show that the Novikov coordinates can be obtained in a direct and physically transparent way from the radial geodesics of massive particles with negative energy in the Schwarzschild spacetime. These geodesics form a complete congruence that covers the entire spacetime. By rectifying this family of trajectories using the proper time as the time coordinate, the Novikov variables naturally emerge, providing a clear dynamical interpretation of the different regions usually identified as black-hole and white-hole sectors. In Novikov coordinates, observers at fixed spatial positions follow free-fall trajectories. From their perspective, the gravitational collapse of a dust star is completed in a finite proper time, independently of their initial distance from the star. In contrast, observers described by Schwarzschild–Droste coordinates perceive the boundary of the collapsing star as taking an infinite coordinate time to reach the horizon. We emphasize that Schwarzschild–Droste observers are static with respect to the center of mass of the star and therefore cannot be in free fall. The use of these coordinates implicitly requires the presence of a force that compensates for the gravitational attraction. From this viewpoint, the apparent infinite-time collapse is not a physical effect but a coordinate artifact associated with non-inertial observers.

The use of universal energy means (UEM) in agricultural production is quite limited, despite their technological capabilities. The purpose of the article is to study the technological capabilities of the UEM, the features of their operation, a comparative analysis of the operational properties of the UEM, in a unit with a semi-mounted forage harvester, with other forage harvesters. For this purpose, studies were conducted to optimize the operation of the harvesting and transport complex (HTC), "field" and theoretical studies were conducted. The "field" studies were based on statistical data characterizing the operation of the HTC, and theoretical studies - elements of probability theory. Based on the results of previously conducted studies, it was assumed that depending on the speed of movement of the chopped mass in the technological path of the forage harvester, the bulk density (bulk density) of the cargo in the body of the vehicle will change, which in turn will have a significant impact on the productivity of vehicles. The theoretical dependence of the bulk density of the harvested crop in the body of the vehicle on the speed of movement in the technological path of the forage harvester is derived. It is established that with an increase in the speed of movement, the bulk density of the harvested crop in the body of the vehicle increases: during free fall (KSS-2.6), at a free fall speed of about 5-6 m / s, the bulk density is 0.250 t / m3, at a speed of 57.6 m / s (UES-280 + KPK-3000) - 0.443 t / m3. The use of mathematical dependencies allows you to quickly determine the yield of the harvested agricultural crop, based on the yield, taking into account the forage harvester used, the distance from the field to the storage location, it is possible to determine the optimal number of vehicles required to ensure non-stop operation of forage harvesters, i.e. quickly manage the work of the harvesting and transport complex. The results of the research can be used in practical activities in any region of Russia.

Training in mechanics at both high school and university levels is often constrained by the lack of adequately equipped laboratories, as much of the necessary equipment is prohibitively expensive. To address these limitations, a virtual environment was developed that integrates interactive simulations of phenomena such as free fall, uniform rectilinear motion, pendulums, inclined planes, and the Atwood machine experiment. Each simulation was implemented as an independent applet with parameter controls (mass, gravity, angle, velocity, etc.) linked to scripts that generate real-time graphs of selected variables. These applets are embedded in a responsive website, organized into sections on theory, user guides, simulations, and references, accessible via computers and mobile devices. The proposed activities enable students to calculate slopes, determine percentage errors, and compare theoretical and simulated values of gravitational acceleration in different planetary environments. Analysis of pedagogical use suggests that these simulations enhance motivation, visual understanding, and learning autonomy, particularly in resource-limited contexts. It is recommended that evaluation be expanded to additional institutions, qualitative studies of user interaction be incorporated, and personalization through artificial intelligence be explored.

In Newton’s theory of gravity, space is the universal container of all things and does not take any part in the movement of material bodies. However, there are a number of observations that are not described by this theory and are used as evidence for the theory of relativity and other theories that refute the absoluteness of space. This article discusses the possibility of departing from the absoluteness of space and supplementing Newton’s theory of gravity with the hypothesis of the torsion of space by rotating space objects. The rationale for this approach is that the law of universal gravitation contains only the mass of the gravitating object and does not take into account the influence of angular momentum, which is possessed by almost all space objects. Based on this hypothesis, formulas are derived for calculating the perihelion displacement of the planets of the solar system and the deflection of light when passing near the Sun. The obtained calculation results coincide with the observational data, which can be considered not only a justification of the hypothesis, but also a refutation of the assumption of the anomaly of these phenomena. It is established that the graph of the torsion velocity function of space has a physical meaning of the trajectory of free fall, since the force of gravity is directed tangentially to it. Considering the torsion of space by the rotating mass of the galaxy, an analytical expression for the rotation curves is obtained. This makes it possible to explain the features of the motion of matter in the disk of the galaxy. It has been established that, unlike the MOND theory, these features are not the result of violations of the law of universal gravitation and relativistic effects, but are explained by an external influence on the rotating space of the galaxy. Based on the logarithmic shape of the rotation curves in the far zone, which most fully corresponds to the observations, a universal analytical expression for the Tully-Fisher type relation is obtained in the form: v ~ln(M).

Microfluidics study of free fall and forced gravity drainage in single- and multi-block fractured porous media: Implications on matrix-fracture interactions

The water entry phenomenon has a wide range of applications in various engineering disciplines, including marine, mechanical, and aerospace engineering fields. In marine engineering, understanding wedge water entry is crucial for the design and safety assessment of high-speed planing craft. Existing theoretical models are developed to estimate hydrodynamic loads during the impact; however, these often rely on rigid body assumptions and constant-entry velocity, limiting their accuracy for flexible structures and realistic impact scenarios. This paper introduces a novel hybrid approach that integrates experimentally measured spray root propagation with re-derived theoretical models to predict hydrodynamic pressure and wedge kinematics during water entry. The method is validated through a case study involving the free fall impact of a flexible wedge, where analytical models are re-derived to account for velocity loss and match experimental conditions. The hybrid approach, particularly when combined with the re-derived Armand and Cointe model, accurately estimates the hydrodynamic impact pressure with errors in peak pressure location and magnitude within 2% and 7%, respectively. When compared with the pure theoretical approaches, the hybrid approach also shows superior performance in predicting hydrodynamic pressure data. This work establishes a foundation for advanced hydrodynamic analysis of highly flexible structures, enabling future applications in early-stage design of small craft and in situ pressure measurement for planing hulls.

This research examined the integration of high-speed video analysis with the Framecount application to enhance Mathayomsuksa 4 students' understanding of free fall motion. Three objectives were pursued: 1) to study free fall motion using high-speed video analysis, 2) to develop supplementary learning activities based on this technique, and 3) to assess the impact of these activities on students' conceptual understanding and academic achievement. A high-speed video camera (using a smartphone at 60 fps) and the Framecount application were employed to record and analyze free fall experiments. The results demonstrated the feasibility of determining gravitational acceleration with an error of less than 5%. Furthermore, students who engaged in the developed learning activities exhibited significantly improved problem-solving skills and academic achievement compared to a control group (p < .05). This study highlights the potential of combining active learning strategies with technology-enhanced analysis to deepen students' conceptual understanding of physics.

The aim of this work was to experimentally substantiate the neuroprotective potential of new combined tablets containing dry extract of peony roots, L-tryptophan, and glycine to eliminate the existing gap in the pharmacotherapy of traumatic brain injury (TBI) associated with the insufficient effectiveness of current monotherapeutic approaches. Material and methods. The study was conducted on 40 male white rats weighing 200–250 g. The TBI model was induced by the free fall of a weight onto a fixed head of the animal. The test preparation was administered orally for 7 days. The effectiveness was assessed using morphological, morphometric, and biochemical methods, including the determination of neuron-specific enolase (NSE) and S100 protein levels in blood serum, as well as analysis of the condition of neurons in the sensorimotor cortex and hippocampus. Results. Rats with TBI demonstrated a significant increase in NSE and S100 levels, a decrease in the number of normochromic neurons, activation of glial cells, and cerebral tissue oedema. Administration of the combined drug contributed to a reduction in neuronal damage markers, a decrease in the glio-neuronal index, and normalization of brain microstructures. Morphological examination revealed preservation of the neuronal layer and a reduction in destructive changes, indicating a pronounced neuroprotective effect of the drug. Conclusions. The developed combined drug demonstrated an effective protective effect on brain tissue under conditions of experimental TBI. The obtained results substantiate the feasibility of further preclinical studies to investigate its mechanisms of action and potential clinical application

The characteristics of air resistance during free fall are a classic problem in fluid mechanics, with significant value for aerospace, airdrop rescue, and meteorological detection. Previous studies on single geometric bodies are relatively complete, but few works compare spheres, cubes, and cones under the same conditions. Wind tunnel experiments are laborious and limited in demonstrating resistance laws across Reynolds number ranges, while the influence of shape parameters such as corner curvature and cone angle lacks quantitative explanation. Based on literature data and theoretical models, this paper proposes a framework for analyzing resistance differences of the three types of bodies without experiments. The resistance coefficient ranges are determined as sphere 0.47-0.50, cube 1.05-1.20, and cone 0.75-0.85. Results show the geometric influences resistance by changing boundary layer separation and wake distribution. At high Reynolds numbers, shape parameters adjust resistance efficiency by 40%-60%, far exceeding secondary factors such as surface roughness and turbulence intensity (<5%). The prediction method achieves 5% error compared with experiments. This study establishes an air resistance theory for low-speed, lightweight, non-spherical objects, providing engineering value for drag reduction, attitude control, and terminal velocity prediction while reducing research and development costs.

A Packet of Short Annular Perturbations around a Crown in the Initial Stage of Merging of a Free Falling Drop with a Fluid at Rest in the Impact Regime

BackgroundEmergency departments (EDs) routinely screen for fall risk, but patients are rarely notified of their results or referred to preventive resources. There is a critical need for an intervention that notifies patients when they are at risk for falls and automates referrals to fall prevention programs without increasing clinician workload. Chatbots can be used to provide patient education and community resources in a conversational, friendly manner. We developed and implemented an automated intervention using our health system's electronic health record (EHR) and an artificial intelligence chatbot, Livi, to address this gap in fall prevention across 17 EDs.ObjectiveThis study aimed to share how we developed our fall risk notification and referral intervention and iteratively improved it based on end-user feedback.MethodsWe collaborated with the EHR and ED operations teams to automate patient notification of fall risk and referral. First, we leveraged existing fall risk screening questions in nursing documentation to identify patients at risk for falls. We then developed an EHR workflow that delivers a QR code in the after-visit summary for all high-risk patients at ED discharge. Scanning the QR code launches a conversation with Livi, guiding users to physician-vetted, evidence-based, free or low-cost fall prevention resources in their area. In this workflow, only ED patients who are screened as high risk receive linkage to Livi, and clinicians do not need to manually place referrals or enter specific fall prevention resources at discharge. We conducted rapid, iterative usability testing of the Livi falls chatbot with 93 community members during the development process at 3 community fairs in distinct settings.ResultsRapid iterative testing led to enhancements in the intervention, such as increased font size, an option for Spanish language, additional geographic locations for fall prevention resources, home modification resources, the ability to self-assess for fall risk, fall prevention tips, and the ability for patients to leave feedback on the Livi chatbot. Because all EDs in the health system use the same instance of Epic, the EHR workflow was instantaneously deployed system-wide. The use of a QR code linked to the Livi chatbot also allows for the rapid updating of prevention resources.ConclusionsThis study describes the formative development and system-wide implementation of the intervention. This scalable, EHR-integrated intervention demonstrates a novel and pragmatic approach to improving population health by capitalizing on existing clinical workflows and automating both risk notification and personalized resource referral for older adults without increasing clinician burden. The next steps include conducting a randomized controlled trial to assess the impact of the screening and referral tool on recurrent fall-related health care use compared with routine care in the ED. Formal evaluation of the implementation outcomes will be conducted in the planned trial.

Abstract Weyl geometric gravity theory, in which gravitational action is constructed from the square of the Weyl curvature scalar and the strength of the Weyl vector, has been intensively investigated recently. The theory admits a scalar–vector–tensor representation, obtained by introducing an auxiliary scalar field, and can therefore be reformulated as a scalar–vector–tensor theory in a Riemann space in the presence of a non-minimal coupling between the Ricci scalar and the scalar field. By assuming that the Weyl vector has only a radial component, an exact spherically symmetric vacuum solution of the field equations can be obtained, depending on three integration constants. As compared to the Schwarzschild solution, the Weyl geometric gravity solution contains two new terms, linear and quadratic, in the radial coordinate, respectively. We consider the possibility of testing and obtaining observational restrictions on the Weyl geometric gravity black hole at the scale of the Solar System, by considering six classical tests of general relativity (gravitational redshift, the Eötvös parameter and the universality of free fall, the Nordtvedt effect, the planetary perihelion precession, the deflection of light by a compact object, and the radar echo delay effect) for an exact spherically symmetric black hole solution of the Weyl geometric gravity. These gravitational effects can be fully explained, and are consistent with the vacuum solution of the Weyl geometric gravity. Moreover, the study of the classical general relativistic tests also allows us to constrain the free parameter of the solution.

Background: Free fatal falls (FFF) are a frequent occurrence in forensic medicine. Many variables, such as the victim's sex, BMI, intoxication, height of the fall, and mental illness, can influence injury patterns. Previous studies identified fracture patterns and frequencies mostly with general anatomical detail, focusing on broad areas. As specific fractures might be roots for new statistical connections, this leaves a gap in our understanding. Using postmortem computed tomography, we aim to establish fracture frequencies and identify possible new statistical connections. Methods: In total, we retrospectively analyzed seventy-nine cases of confirmed deaths due to falls using the database of the Department and Institute of Forensic Medicine in Lublin. Our inclusion criteria were death due to free fall onto hard, non-deformable surfaces. We excluded cases of ground-level falls. All victims must have undergone postmortem computed tomography. Furthermore, each analyzed case documented individual intrinsic variables (sex, age, body mass, height, pre-existing mental conditions, and drug or alcohol use) and extrinsic variables (fall height, landing surface, time between the fall and death, and known cause of the fall). Results: Injuries in free fatal falls tend to focus on the axial skeleton. Suicides experience more severe, bilateral fractures, often involving the pelvis and limbs, while accidents tend to have unilateral injuries with rare limb involvement. We established new correlations with the height of the fall for the maxilla, mandible, anterior and posterior regions of the occipital bone, and the temporal bone. Moreover, our research confirmed previously noted correlations between the height of the fall and fractures of the limbs (and their individual bones), the lumbar vertebrae, and the chest. Conclusions: Our findings highlight that free fatal falls are characterized by distinct skeletal injury patterns that differ between accidents and suicides, with bilateral pelvic and limb fractures being particularly indicative of intentional falls. The integration of PMCT with autopsy improves the detection of these patterns. It provides valuable diagnostic and medico-legal insights, supporting a more precise determination of the cause and manner of death.

Yang–Mills gravity is a quantum theory of gravity with translational gauge symmetry that is based on a flat spacetime. The universal coupling of all quantum fields to quantum Yang–Mills gravity is based on the replacement of [Formula: see text] by the translational gauge covariant derivative [Formula: see text] in the Lagrangians of non-gravitational fields. Near the surface of the Earth, Yang–Mills gravity causes the phase gradient [Formula: see text] to be altered by a factor of [Formula: see text]. In addition, the usual gauge-invariant combination of phase gradients and electromagnetic vector potentials [Formula: see text] in Josephson junctions is modified and is no longer [Formula: see text] gauge invariant. The voltage across a Josephson junction is thus affected by the presence of the gravitational coupling constant g, and is now given by [Formula: see text]. If one were to compare the voltage across a Josephson junction in a laboratory at rest on Earth with that across a junction in free fall (e.g. in the International Space Station), Yang–Mills gravity predicts a difference on the order of 1 part in [Formula: see text], which should be detectable as the precision of the Josephson junction voltage standard is on the order of a few parts in [Formula: see text]. Measurements of two terms in [Formula: see text] can test (i) the gravitational effect on the Josephson voltage-phase relation, and (ii) the violation of the [Formula: see text] gauge symmetry in superconductors by Yang–Mills gravity.

Many insect species are reluctant to fly freely in wind tunnels, limiting direct free-flight energetics measurements to just two species. More commonly tethered-flight energetics have been investigated, though the effects of tethering on metabolic rate are unclear. Here, we report mass-specific gross metabolic rate (assessed as the rate of carbon dioxide production; ) across a speed range (0–4.1 m s−1) in bumblebee (Bombus terrestris) workers during tethered and free flight in a closed-circuit wind tunnel. followed a U-shaped relationship with airspeed during both free (p = 0.009) and tethered flight (p < 0.001). Bees were anaesthetized with isoflurane during tethering, which had no subsequent effect on their metabolic rate (p > 0.05), avoiding issues reported during immobilization with CO2 or cold exposure. Tethered was 45% lower than during free flight (p < 0.001), but the minimum power speed and the trajectory of the metabolic power–speed relationship (p > 0.8) were similar. Overall flight efficiency ranged from 7.3 to 14.7% and did not vary with airspeed. These findings confirm a U-shaped metabolic power–speed relationship in insects, and suggest that tethered flight may approximate free-flight energetics. However, a shift in the maximum range speed to slower speeds during tethered flight warrants caution against using this variable to predict behaviour.

ABSTRACT Once an epicentre of higher learning, Afghanistan has been constructed as ground zero for globalisation and competing militaristic projects. Focusing on the privatisation of higher education, this paper examines how military occupation instilled neoliberal economic and educational policies. With the rise of the private higher education landscape, the paper illuminates how Afghans grew dissatisfied with private higher education due to compromised educational quality, emphasis on economic profits and increasing alignments with foreign interests. The withdrawal of the US Military, unravelling of the neoliberal economic system, adoption of the America First agenda and increasingly restrictive educational policies for women have led to a state of free fall of higher education in the country.

Abstract Accurately measuring the velocity field of granular flow in silos and elucidating the rule of the distribution under different discharge modes are essential for understanding of the granular rheology mechanisms, and optimizing the discharge system design. This work studies the flow characteristics of black electroplated glass beads in a two-dimensional silo under free fall discharge and conveyor belt discharge. The Particle Tracking Velocimetry (PTV) method is employed to measure the velocity field, and the distribution characteristics under the two modes are systematically compared and analyzed. The results show that while there are significant differences in the numerical values of granular velocity, the normalized velocity profiles are highly consistent. On this basis, a quantitative relationship for the velocity profiles under two discharge modes is established through the kinematic model. This reveals that the differences in velocity profiles caused by the discharge modes are essentially magnitude scaling, while the flow characteristics remain invariant. This finding not only provides a predictive model for the velocity field under conveyor belt discharge in silos, but also contributes empirical data to advance the rheological theory of granular flow.

This research review paper explores the complex relationship between the removal of energy subsidies and the depreciation of the Nigerian naira under the current democratic government. Energy subsidies have long been a point of contention in Nigeria, with successive governments grappling with the economic, social, and political implications of their removal. The removal of energy subsidies has been touted as a necessary measure to free up government revenue for development projects, but it has also triggered inflation, social unrest, and a free fall of the naira in the foreign exchange market. This review paper examines the historical context of energy subsidies in Nigeria, their impact on the economy, and the theoretical and conceptual frameworks that explain the interaction between subsidy removal and currency depreciation. It also delves into the current administration’s policies on subsidy removal, the challenges posed by the free fall of the naira, and potential strategies for mitigating these issues. The paper concludes with recommendations for sustainable economic reform, focusing on balancing fiscal responsibility with social equity in a democratic context.

We present a theoretical study of delta-kick collimation (DKC) applied to heteronuclear Feshbach molecules, focusing on both condensed and thermal ensembles across various interaction and temperature regimes. We demonstrate that DKC enables significant reductions in molecular cloud expansion energies and beam divergence, achieving expansion energies in the picokelvin range, comparable to state-of-the-art results obtained experimentally with atoms. Furthermore, we show that vibrational and translational motions remain strongly decoupled throughout the process, and that the vibrational energy remains well below the molecular binding energy, thereby ensuring molecular stability during the delta kick. This work paves the way for advanced experimental sequences involving degenerate ground-state molecules, light-pulse molecular interferometry, and applications of dual-species precision measurements, such as testing the universality of free fall.