Newtonian Force Research Articles

Circumferential Labral Reconstruction With Knotless All-Suture Anchors Restores Hip Distractive Stability: A Cadaveric Biomechanical Analysis.

The essential component of managing femoroacetabular impingement involves restoration of the original labral function. Circumferential labral reconstruction (CLR) has shown positive results. However, biomechanical studies of CLR are limited and have not established the efficacy of the modern knotless all-suture anchor (ASA) pull-through technique. (1) CLR with knotless ASA fixation will restore native labral suction seal biomechanics; (2) tensioning the ASA to a high-tension state will increase the peak distractive force. Controlled laboratory study. Eight fresh-frozen human cadaveric hips were dissected free of all soft tissue except the native labrum and transverse acetabular ligament. On an electromechanical testing system, the hips were compressively loaded to 250 N to initiate a suction seal and distracted at a rate of 10 mm/s until rupture of the suction seal. Hips were tested in 4 states: intact labrum, full labral removal, knotless CLR with moderate anchor tension, and CLR with high anchor tension. Peak distractive force (in newtons) was compared using repeated measures analysis of variance (P < .05). Acetabular bevel angles (θ) were measured at labral clockface positions outside the transverse acetabular ligament using a 3-dimensional digitizer stylus after rim preparation. Linear regression plots compared θ and peak distractive force in the CLR state. Peak force values were 138.5 ± 13.6 N (mean ± SE) for the intact labrum, 18.4 ± 2.79 N for labral excision, 95.4 ± 23.3 N for moderate-tension CLR, and 126.2 ± 27.3 N for high-tension CLR. Significant differences were observed only when full labral removal was compared with the other conditions: intact (P < .001), moderate-tension CLR (P = .016), and high-tension CLR (P = .002). Steeper acetabular bevel angles (smaller θ) were correlated with greater suction seal restoration (P < .05). CLR restored distractive stability on average to 82.0% of the intact value after labral deficiency. Retensioning did not significantly increase peak distractive forces. These findings provide biomechanical validation supporting CLR using knotless ASAs in an effort to minimize volumetric bone loss and provide other surgical advantages. The prepared rim's bevel angle may be an important variable to optimize for improved suction seal restoration.

Impact of Needle Design and Suture Gauge on Tissue Tearing During Skin Suturing: A Comparative Analysis.

Surgeons face numerous choices in selecting sutures for skin closure, with potential adverse effects such as tissue tearing. To investigate the influence of needle design and suture gauge on tissue tearing during suturing procedures. The authors tested the tear-through force in Newtons for 3 needle types and 3 suture gauges using an artificial skin model and a professional-grade tensiometer. Suture material was secured into the skin model, and force was applied to the suture at a constant rate, resulting in tearing. Force-displacement and force-time curves were generated. Evaluation included conventional cutting (PC-3), reverse cutting (PS-3), and taper point (BB) needles with a 5-0 polypropylene suture. In addition, nylon sutures with a reverse cutting needle (PS-2) were tested at 3 suture gauges (5-0, 4-0, 3-0). The mean tear-through forces for PC-3, PS-3, and BB were 3.26 N, 3.75 N, and 4.07 N, respectively. For the 5-0, 4-0, and 3-0 nylon sutures, the mean tear-through forces were 3.44 N, 3.81 N, and 4.04 N, respectively. Statistical analysis revealed a significant impact of suture gauge size (p < .001) and needle geometry (p < .001) on tear-through force. Larger suture diameter and taper needles minimize tissue tearing.

Galaxy groups in the presence of cosmological constant: Increasing the masses of groups

The boundaries of galaxy groups and clusters are defined by the interplay between the Newtonian attractive force and the decoupling from the local expansion of the Universe. This work extends the definition of a zero radial acceleration surface (ZRAS) and the turnaround surface (TS) for a general distribution of the masses in an expanding background, governed by the cosmological constant. We apply these definitions to different galaxy groups in the local Universe, mapping these groups up to ten megaparsec distances. We discuss the dipole and the quadrupole rate for the Local Group of Galaxies and the implementations on the Hubble diagram correction and galaxy groups virialization. With these definitions, we present the surfaces showing the interplay between the local expansion vs the local Newtonian attraction for galaxy groups in the local Universe. Further, we estimate the masses of different galaxy groups and show that the inclusion of the Cosmological Constant in the analysis predicts these masses to be higher by 5-10%. For instance the Local Group of galaxies is estimated to be (2.47±0.08)⋅1012M⊙. For the groups with enough tracers close to the TS, the contribution of the Cosmological Constant makes the masses to be even higher. The results show the importance of including the local cosmic expansion in analyzing the Cosmic Flow of the local Universe.

Quantising a Hamiltonian curl force

Abstract Classical curl forces are position-dependent Newtonian forces (accelerations) that are not the gradient of a scalar potential, and in general cannot be described by Hamiltonians. However, a special class of curl forces can be described by Hamiltonians, with the unusual feature that the kinetic energy is anisotropic in the momentum components. Therefore they can be quantised conventionally. We quantise the simplest such case: motion in the plane, with a curl force azimuthally directed and linear. As expected, the quantum propagator, and the way this drives Gaussian wavepackets, directly reflects the spiralling classical curl force dynamics. Two classes of stationary states—eigenfunctions of a continuous spectrum for the unbounded Hamiltonian—are described. They possess unusual singularities and an unfamiliar quantisation condition; their explanation requires asymptotics and unfamiliar singularities in the underlying families of classical trajectories. The analysis is supported and illustrated numerically.

Comparative Analysis of Taper Point and Reverse Cutting Needles on Skin Puncture Force.

Reverse cutting needles are commonly used in cutaneous surgery due to their perceived ease of use. Despite this, there is limited research evaluating the force required to puncture skin using contemporary needles. This study aims to compare the puncture forces required for two different needle geometries across various gauge sizes. The authors assessed the force necessary to penetrate samples of human abdominal skin samples using taper needles of three different United States Pharmacopeia gauge sizes with their respective reverse cutting needle counterparts. Taper point needles tested were RB-1 (3-0), TF (4-0), and C-1 (5-0), while reverse cutting needles included PS-2 (3-0) and P-3 (4-0, 5-0). An electronic force meter was used to record the puncture force required by each needle type. The mean puncture force in newtons (N) for taper point needles was 1.00, 0.74, and 0.48 for RB-1, TF, and C-1, respectively. The mean puncture force for reverse cutting needles was 0.95 N, 0.60 N, and 0.51 N for PS-2, P-3 (4-0), and P-3 (5-0), respectively. There was a direct relationship between needle body diameter and puncture force for both needle geometries. There was no clinically significant difference in skin puncture force between needle geometries.

Maximal acceleration in Rainbow gravity

In this paper, we derive maximal acceleration of a massive particle in Rainbow gravity. Using eight-dimensional phase-space metric compatible with Rainbow gravity, we obtain the maximal acceleration, valid up to first order in the Rainbow gravity parameter η. Using the positivity condition on maximal acceleration, we find that the upper bound on the Rainbow gravity parameter is of the order of for positron and for a black hole. After obtaining the expression for maximal acceleration for different choices of Rainbow functions, we derive corresponding modifications to Unruh temperature. Comparing with the observational value of the Unruh temperature, we find the upper bound on η as for positron radiation. We then derive geodesic equations for different choices of Rainbow functions and also obtain the Newtonian limit of these geodesic equations. We find that the changes in the value of maximum acceleration, maximum temperature and Newtonian force equation are dependent on the choices of Rainbow functions.

Experimental study on joint sensing and early warning method of landslide disaster based on NPR-OFST

In order to explore more effective methods of landslide disaster monitoring and controlling, NPR anchor cable and optical fiber grating strain sensor are physically combined to form a slope reinforcement-monitoring integration system, with PVC pipe an intermediary. Physical model test is carried out according to timely warning of landslide disasters of the Newtonian force monitoring system. At the same time, the optical fiber sensing technology has the condition of continuous perception of time and space. The feasibility of monitoring the whole life cycle of slope instability and positioning the potential sliding surface is discussed. Through the analysis of the test results, it is concluded that the fiber grating strain sensor can effectively monitor the deep displacement of the slope. PVC pipe and the soil have deformation coordination, which is able to effectively reinforce the slope body together with the combined anchor cable sensing device, and can continuously sense the potential sliding surface in the whole life cycle of the slope. By comparing the results of Newton force monitoring curve with the fiber grating strain monitoring, the mechanical law of “Newton force sudden drops, immediately catastrophe happens” is further verified. The feasibility of the combined sensing and early warning method of optical fiber sensing technology and Newton force monitoring is verified. This method realizes the further optimization of Newton force monitoring system.

Experiment study on adhesion dynamic characteristics of droplet impacting on an inclined heated surface

The behaviors and mechanisms of droplet impact on an inclined heated surface is of great importance. In this work, an experimental platform for the droplets impact on the surfaces with different inclined angles and temperatures was established to study the various impact patterns and dynamics. The impact pattern, sliding distance, lengths at the leading and trailing edge points and maximum spreading factor were studied in detail. The results show that the impact patterns were classified as adhesion, splash, rebound and breakup patterns. In the adhesion pattern, a sliding distance model was developed based on Newton's second law and force analysis that considered the viscous, adhesion and gravitational forces for different angles. Larger angle promotes length of the leading edge point, inhibits length of the trailing edge point. Higher temperature suppresses the length of the trailing edge point by boiling. In addition, a model for the maximum spreading factor of the inclined surface was developed by combining a spreading prediction mode with an energy conservation equation, which incorporates kinetic, surface and dissipation energies. An increase in the normal Weber number suppresses the maximum spreading factor. Temperature has a different effect on the maximum spreading factor depending on the normal Weber number.

Evaluation of the Stability of Open-Tray Impression Coping Using Two Different Impression Materials at Three Different Subgingival Implant Placement Depths.

Objective To evaluate and compare the stability of the open trayimpression coping within the set impression while attaching the lab analog when polyether (PE) heavy body and polyvinyl siloxane (PVS) putty impression materials were used and the implant platform was placed sub-gingivally at three different depths. Methods Two impression materials, PE and PVS, and custom-made plexiglass models with embedded single implants to simulate implant positioning depths of 0 mm, 2 mm, and 4 mm, sub-gingivally, were used in the study. Open tray impressions were made after attaching impression coping to theimplant embedded in themodel. Implant lab analog was attached to the impression coping in the set impression, and its stability was measured using a universal testing machine. Forty-two open tray impressions were madein six groups, with seven impressions in each group. Descriptive statistics such as mean and standard deviation were calculated. A comparison of the meanstability between the two impression materials at each depth was done using an independent t-test.Comparison of the mean stability between the three different subgingival implant depths in each material was done by one-way ANOVA with the Scheffe multiple comparison test (post-hoc analysis). The level of significance was set at p<0.05. Results The stability of the impression coping was measured as the force in Newtons required for the displacement of the analog attached to the impression coping embedded in the set impression. PEwith the embedded impression coping at a depth of 0 mm gave the highest mean stability value (4.37+/-0.41), and the least mean stability was offered by PVS with the embedded impression coping at 4 mm depth (1.88+/-0.37). When an independent t-test was done to compare the mean stability values of PE and PVS,there was a statistically significant difference at0 mm, 2 mm, and 4 mm. On doing one-way ANOVA to compare the mean stability between the different depth groups, there was a statistically significant difference between the three depth groups in PE and PVS. Scheffe multiple comparison tests (post-hoc analysis) revealed a statistically significant difference between 0 mm, 2 mm, and 4 mm subgingival depths of the impression coping placement in bothPE and PVS. Conclusion The accuracy of the master cast is an important determinant for the precise fit and long life of the final prosthesis. In the case of maxillary anterior implant placements where deep subgingival placement of the implant platform is needed for aesthetic and functional reasons, the impression material should be selected carefully to ensure the stability of the impression coping. Among the materials included in the present study, the PE impression material offered the maximum stability for impression coping compared to PVS.

Study on copper-to-copper bonding of three-dimensional integrated circuits using the quasicontinuum method

Cu-Cu bonding presents an attractive approach to bottom-up manufacturing, facilitating nanoparticle production, linking, and restoration. The ramifications of varying bonding depths and orientations exhibit distinct characteristics. At the same time, investigations into the material composition of nanoscale bonded pairs involve scrutiny of atomic slippage, strain distribution, and the force-displacement profile. The methodology simulates the Cu-Cu bonding process by implementing the quasi-continuum (QC) approach, constituting a multifaceted mixed molecular dynamics technique integrating atomistic and continuum methods. The analysis of results reveals variations in the Contact effect induced by the four orientations, along with discrepancies in the atomic slippage observed in distinct directions. Notably, a pronounced distinction is discernible in the directional movement. Specifically, the strained regions on the flat surface of the lower substrate, characterized by the directionality of X[001]-Y[110], exhibit a notably broader range of atomic slip compared to regions strained by alternative orientations. Furthermore, the directional alignment of X[110]-Y[111] illustrates that irrespective of whether the lower substrate’s surface is flat or rough, the orientation of atomic slip diverges. In conclusion, our study employed a quasi-continuous method to explore the bonding efficacy of copper-to-copper interfaces on flat and irregular substrate surfaces. Through this approach, we scrutinized the distributions of strain, stress, average Newtonian force, and atom differential arrangement direction across different orientations.

Elastic solids under frictionless rigid contact and configurational force

A homogeneous elastic solid, bounded by a flat surface in its unstressed configuration, undergoes a finite strain when in frictionless contact against a rigid and rectilinear constraint, ending with a rounded or sharp corner, in a two-dimensional formulation. With a strong analogy to fracture mechanics, it is shown that (i.) a path-independent J–integral can be defined for frictionless contact problems, (ii.) which is equal to the energy release rate G associated with an infinitesimal growth in the size of the frictionless constraint, and thus gives the value of the configurational force component along the sliding direction. Furthermore, it is found that (iii.) such a configurational sliding force is the Newtonian force component exerted by the elastic solid on the constraint at the frictionless contact. Assuming the kinematics of an Euler–Bernoulli rod for an elastic body of rectangular shape, the results (i.)–(iii.) lead to a new interpretation from a nonlinear solid mechanics perspective of the configurational forces recently disclosed for one-dimensional structures of variable length. Finally, approximate but closed-form solutions (validated with finite element simulations) are exploited to provide further insight into the effect of configurational forces. In particular, two applications are presented which show that a transverse compression can lead to Eulerian buckling or to longitudinal dynamic motion, both realizing novel examples of soft actuation mechanisms. As an application to biology, our results may provide a mechanical explanation for the observed phenomenon of negative durotaxis, where cells migrate from stiffer to softer environments.

Finite element stress analysis in mandibular molars with apical root resorption and crown destruction after root canal treatment using various materials

Aim: The objective of this study is to analyze the stress distribution of root canal treated teeth under occlusal forces and aid in the selection of appropriate materials for teeth with root tip resorption and crown destruction, using the finite element stress analysis method (FEM). Methods: The study was conducted on two-rooted lower molar teeth, divided into five groups. The root length was 14 mm, the crown length was 7.5 mm, and the total length was 21.5 mm. It was assumed that the distal canals were resorbed by 4 mm. Group 1 consisted of untreated intact teeth. Group 2 involved filling the mesial canals with gutta-percha, filling the apical part of the distal canal with 4 mm Mineral Trioxide Aggregate (MTA), and fabricating the crown using glass fiber post and IPS e.max materials. Group 3 involved filling the mesial canals with gutta-percha, filling the apical part of the distal canal with 4 mm Biodentin, and manufacturing the crown using glass fiber post and IPS e.max materials. Group 4: The canals were filled with MTA, and an IPS e.max endocrown was used. Group 5: The canals were filled with Biodentin and an IPS e.max endocrown was used. The study examined the effect of a 100 Newton force applied in the occlusal direction on dental tissues using finite element stress analysis. Results: The study found that the application of fiber posts resulted in less stress accumulation in tooth tissues compared to endocrown. Conclusion: The use of Biodentin or MTA in endocrown teeth did not affect the stress in tooth tissues caused by applied force. In conclusion, while fiber posts increase durability by reducing stress in root-end resorbed teeth, the effect of Biodentin or MTA on stress resistance in dental tissues is limited. How to cite this article: Duran S, Şirin DA, Topbaş C. Finite element stress analysis in mandibular molars with apical root resorption and crown destruction after root canal treatment using various materials. J Med Dent Invest 2024;5:e240320. https://doi.org/10.5577/jomdi.e240320

Predicting hand grip force based on muscle electromyographic activity using artificial intelligence and neural networks

The research aims to find predictive values for hand grip strength based on electromyographic activity, in addition to identifying differences between measured grip strength and the predicted grip strength. The research sample included 12 advanced handball players, with their medical records verified. Researchers measured grip strength using a device designed to read Newton force, recording data in real-time with a sampling window of 0.1 seconds. This measurement was synchronized with the recording of muscle electromyographic activity (sEMG) using the Noraxon myoMOTION technique, with a frequency and number of channels set at 400Hz and 8 channels, respectively. The recommended methodology and conditions were strictly adhered to, with the process repeated for each player with complete rest intervals. The following research variables were adopted: peak electromyographic activity, root mean square, time to peak, time ratio between peak and minimum values, average peaks, area under the curve, peak sustain time, peak changes, and voluntary maximum contraction. Grip strength measurements using the designed device were conducted at three stages (50%, 75%, 100%), maintaining the specified intensity for 3 seconds. After data collection, preliminary processing involved isolation and purification to identify the most influential factors. IBM Statistical was the chosen technique for implementing neural networks and using artificial intelligence techniques to process data with a database synchronized using Python. The results generally supported some of the proposed ideas, with interesting findings revealing statistically insignificant and slight differences between recorded and expected grip strength

Numerical Simulation Study on Deformation Mechanism of Tunnel–Landslide Orthogonal Systems and Early Warnings of Imminent Sliding

This paper takes a tunnel through a landslide in Northwest China as an example, constructs a mechanical model of a tunnel–landslide orthogonal system, and explores the deformation mechanism of a tunnel–landslide system and the technology of early warnings of near-slips. Given the problem that it is difficult to accurately monitor the deformation and damage characteristics of the tunnel–landslide system using conventional methods, FLAC3D was used to analyze the deformation mechanism of the tunnel–landslide orthogonal system and numerical simulation of the NPR constant resistance large deformation anchors for the early warning of near-slips. Based on the strength reduction method, by reducing the mechanical parameters of the shear strength of the slip zone and simulating different degrees of landslides, we obtained the change rules of the displacement and the axial force of the NPR constant-resistance large deformation anchor cable in the tunnel–landslide orthogonal system, established the warning mode of the Newtonian force tunnel–landslide orthogonal system, and successfully issued a near-slip warning in actual engineering applications. The above research is of great significance to the stability monitoring and risk assessment of tunnel–landslide systems.

Calculations of Non-Metallic Particles Removal from Liquid Aluminium to Top Slag

In the paper, the results of a numerical analysis of KCl and KF particles present in liquid aluminium assimilation to the slag are presented. The authors analysed particle movement in the slag model, which is based on buoyant, capillary, viscosity, Newton and repulsion forces, interfacial tensions at the interface of phases and surface energy during the particle movement through phases boundary. On the basis of the mathematical model, a computer programme was written to make simulations under different conditions. The results of particle position in the slag are presented for different particle radiuses: 1, 5, 10, 20 μm, and constant viscosity of the slag including velocity evolution of the velocity. Another approach was used to indicate the influence of slag viscosity on particle and slag penetration depth. During computations, selected viscosities of slag of 0.0012, 0.0015, 0.0018 [kg/m·s] were taken into account. Different comparisons were made for the chosen particle sizes. Each examination takes into account the impact of the particle type. The results clearly show that for larger particles the penetration depth is greater and viscosity of the slag has an impact on the velocity evolution during assimilation process.

Generalization of the Schrödinger Equation for Open Systems Based on the Quantum-Statistical Approach

Within the framework of the quantum-statistical approach, utilizing both non-Hermitian Hamiltonian and Lindblad’s jump operators, one can derive various generalizations of the von Neumann equation for reduced density operators, also known as hybrid master equations. If one considers the evolution of pure states only, i.e., disregarding the coherence between states and spontaneous transitions from pure to mixed states, then one can resort to quantum-mechanical equations of the Schrödinger type. We derive them from the hybrid master equations and study their main properties, which indicate that our equations have a larger range of applicability compared to other generalized Schrödinger equations proposed hitherto. Among other features, they can describe not only systems which remain in the stationary eigenstates of the Hamiltonian as time passes, but also those which evolve from those eigenstates. As an example, we consider a simple but important model, a quantum harmonic oscillator driven by both Hamiltonian and non-Hamiltonian terms, and derive its classical limit, which turns out to be the damped harmonic oscillator. Using this model, we demonstrate that the effects of dissipative environments of different types can cancel each other, thus resulting in an effectively dissipation-free classical system. Another discussed phenomenon is whether a non-trivial quantum system can reduce to a classical system in free motion, i.e., without experiencing any classical Newtonian forces. This uncovers a large class of quantum-mechanical non-Hamiltonian systems whose dynamics are not determined by conventional mechanics’ potentials and forces, but rather come about through quantum statistical effects caused by the system’s environment.

Search for environment-dependent dilatons

The environment-dependent dilaton field is a well-motivated candidate for dark energy and naturally arises in the strong coupling limit of string theory. In this article, we present the very first experimental constraints on the parameters of this model. For this, we employ data obtained from the qBounce collaboration and the Lunar Laser Ranging (LLR) experiment. Furthermore, we forecast expected constraints for the Casimir And Non Newtonian force EXperiment (Cannex) soon to be realized in an improved setup. Finally, we provide a detailed analysis of the screening mechanism and additional symmetries of the dilaton field theory.

General relativity and background Lorentz transformations solve Supplee's submarine paradox

A submarine moving at relativistic horizontal velocity sinks in Earth's rest frame due to length contraction while appearing to float in its own frame. Using spacetime geometry and the Lorentz transformations, we show that the resolution lies in how metric components transform between reference frames in relative motion. This solution frees us from assumptions made in previous studies on how a Newtonian gravitational force should transform. The method of background Lorentz transformations is technically simpler than previous treatments in the framework of general relativity. Moreover, we find a novel and intuitive understanding of the paradox, and correct an erroneous expression for the gravitational force obtained by Supplee and used again in the literature.

Unveiling the intricacies of attracting zones in magnetic binary systems: Investigating the impact of Yukawa correction

This study delves into the restricted three-body problem with a Yukawa correction to Newtonian gravitational forces, focusing on magnetic binary systems. We scrutinize the influence of Yukawa correction parameters (α, β) and the ratio of magnitude of magnetic moments (λ) on the system’s equilibrium points and their stability, zero-velocity curves. In our case, there exist of five and seven equilibrium points and all are found to be unstable for given range of parameters. Our examination extends to the basins of convergence and the existence of fractal under the influence of α and λ. Graphs drawn with the help of Wolfram Mathematica software vividly portray the parameter-driven evolution of equilibrium points, zero-velocity curves and basins of convergence. Furthermore, we explore the fractal characteristics within the basins of convergence, offering valuable insights into the complex dynamics of magnetic binary systems with Yukawa correction.

A case study of a giant reactivated landslide based on NPR anchor cable Newton force early warning

A case study of a giant reactivated landslide based on NPR anchor cable Newton force early warning