Vectorial Force Research Articles

Finding the main facial aging vector force to reverse the impact of soft tissues and weak ligaments to the original youthful face

Background: In order to reverse a flabby face, we need to be aware of where the main vectorial aging face force, which is the sum of the descendent forces like gravity, attenuated ligaments and facial fat deflation, is placed. Main soft tissues promote medial inferior deflation and fat compartment shape changes. Aims: We propose a new method to find the angle of the main vectorial facial aging without the need to visualize the zygomaticus major muscle directly, but instead by doing a finger test by pulling the skin upwards and laterally with the patient’s head in the upright position. Patients/ Methods: We collected facial measures from 73 female subjects within the Brazilian population, aged between 30 to 69 years old. Then, the main aging vector angle was measured on each participant sitting in the upright position guided by a standardized protocol. Results: The median aging vector angle was made and the patients were divided into age-groups from 30 to 39 years old (52.5o), from 40 to 49 (51o); 50 to 59 (55o) and 60 to 69 (51o). Conclusions: According to our study and statistical analysis we could find the main facial aging vector angle between 30 and 69 years old didn’t vary significantly and was around 51°to 55°. Our aim was to propose guidance to a better natural surgical or nonsurgical lifting strategy that focuses on the reversal of flabby tissues (inferomedially) by counteracting the main facial aging vector force toward the superior-lateral facial area.

Behavior and Design of Power-Actuated Fastener Connections in Cold-Formed Steels Subjected to Shear

This study proposes an innovative type of simple connection utilizing power-actuated fasteners to join a cold-formed steel channel to a rectangular hollow section column via a web-side plate or a T-section. An experimental program composed of 26 specimens was carried out to investigate the behavior of the connections under the combination of shear and rotation. The experimental results are discussed in two limit states including bearing and pull-out by shear. An analytical model is proposed to predict the shear strength of the connections based on the provided information of vectorial force at a fastener, displacement, and rotation at the connections. The proposed model yields a conservative prediction for the tested connections with a mean test-to-prediction ratio of 1.05 and the coefficient of variation of 6% or 9%, depending on the limit state. A design example is provided to illustrate the implementation of the proposed model in practice.

Compact Vectorial Transverse Force Sensor Based on Two-Modal Interference in a Few-Mode Seven-Core Fiber

A compact and highly sensitive optical fiber vectorial transverse force sensor is proposed to simultaneously measure the magnitude and direction of the transverse force based on two-modal interference. The sensor consists of a few-mode seven-core fiber (FM-SCF) connected to a fan-in/out coupler. The calculation model for predicting the performance characteristics of the proposed FM-SCF sensor under transverse forces has been developed, and the different spectral shifts of its each core are theoretically and experimentally analyzed. The magnitudes and direction angles are investigated by calculating the dip wavelength shifts and its difference. The sensitivity of the force sensor of 17.527 nm/N and the minimum resolved force of 0.005N were observed experimentally. Additionally, it is able to detect the direction angle of the transverse force with an accuracy of 1.15°. The effect of temperature on the response of FM-SCF sensor can be eliminated while measuring the direction angles. The presented results indicate a great potential of the FM-SCF sensor applications of microsurgery.

Determining the orientation of the flexural modes of a thermally driven microwire cantilever

Mechanical resonators are excellent transducers for ultrasensitive detection applications. Recent advances such as vectorial force sensing and ultrahigh-resolution mass spectra rely on the identification of two flexural vibrational modes of a resonator. The orientations of the flexural modes with respect to the incident optical axis are crucial parameters for a cantilevered resonator. Previous methods have adopted complex experimental setups using quadrant photodetectors or have required simultaneous detection of two flexural modes of the cantilever. In this paper, we propose a method for determination of the orientations of the flexural vibrations of a cantilever using a microlens optical fiber interferometer that takes both the light interference and the lateral light scattering of the cantilever into account. We demonstrated the method by experimentally determining the orientation of the first three flexural vibrational modes of a thermally driven microwire. Our method can be used to characterize individual flexural modes with arbitrary orientations and thus provides a new tool for detecting vectorial forces.

The Manifestation of Will: The Vectorial Force of Accepting Guilt

Individual conduct involves the orientation of actions in a certain way by making a decision. The attempt to establish the unique and appropriate purpose of the action is based on the intention to achieve that goal, followed by the elaboration of the mental plan for the realization of the action. In the deliberation, certain processes are underway to investigate the conditions for carrying out the criminal activity, assessing its effects in the objective reality. Following the analysis of the meanings, the reasons and the purpose pursued, the mental plan for the concrete realization of the criminal activity is finalized by making the decision to commit the crime. Finalizing the decision is followed by its execution to achieve the goal pursued, the aggressor using is hull psychophysical ability, knowledge, skills and ability in adopting a method of action. The manifestation of will is realized when the individual acts knowingly, even if the purpose of his actions coincides with the interests and needs of others. The guilt appears to be a force contrary to the manifestation of freedom of each individual, considered as the original behavioral form of any collectivity that opposes block of opposite behavior.

Tension mediated nonlinear coupling between orthogonal mechanical modes of nanowire resonators

We study the nonlinear coupling between orthogonal flexural modes of doubly clamped InAs nanowire resonators. The two orthogonal modes are formed by the symmetry breaking and lifting of degeneracy of the fundamental mode. The presence of a Duffing nonlinearity emerges when a mode is driven to large amplitudes. In this regime the modes are coupled due to the tension induced from the large amplitude of oscillations and is reflected in the hysteretic response of the mode that is not strongly driven. We study the driven-driven response of the mechanical modes to elucidate the role of nonlinear mode coupling in such mechanical resonators. The dynamics of the coupled modes studied here could prove useful in technological applications such as nanowire based vectorial force sensing.

Eigenmode orthogonality breaking and anomalous dynamics in multimode nano-optomechanical systems under non-reciprocal coupling

Thermal motion of nanomechanical probes directly impacts their sensitivities to external forces. Its proper understanding is therefore critical for ultimate force sensing. Here, we investigate a vectorial force field sensor: a singly-clamped nanowire oscillating along two quasi-frequency-degenerate transverse directions. Its insertion in a rotational optical force field couples its eigenmodes non-symmetrically, causing dramatic modifications of its mechanical properties. In particular, the eigenmodes lose their intrinsic orthogonality. We show that this circumstance is at the origin of an anomalous excess of noise and of a violation of the fluctuation dissipation relation. Our model, which quantitatively accounts for all observations, provides a novel modified version of the fluctuation dissipation theorem that remains valid in non-conservative rotational force fields, and that reveals the prominent role of non-axial mechanical susceptibilities. These findings help understand the intriguing properties of thermal fluctuations in non-reciprocally-coupled multimode systems.

Machine Learning Force Fields: Construction, Validation, and Outlook

Force fields developed with machine learning methods in tandem with quantum mechanics are beginning to find merit, given their (i) low cost, (ii) accuracy, and (iii) versatility. Recently, we proposed one such approach, wherein, the vectorial force on an atom is computed directly from its environment. Here, we discuss the multistep workflow required for their construction, which begins with generating diverse reference atomic environments and force data, choosing a numerical representation for the atomic environments, down selecting a representative training set, and lastly the learning method itself, for the case of Al. The constructed force field is then validated by simulating complex materials phenomena such as surface melting and stress–strain behavior, that truly go beyond the realm of ab initio methods, both in length and time scales. To make such force fields truly versatile an attempt to estimate the uncertainty in force predictions is put forth, allowing one to identify areas of poor performance...

Tuning Nonlinear Mechanical Mode Coupling in GaAs Nanowires Using Cross-Section Morphology Control.

We investigate the nonlinear mechanical properties of GaAs nanowires with anisotropic cross-section. Fundamental and second order flexural modes are studied using laser interferometry with good agreement found between experiment and theory describing the nonlinear response under mechanical excitation. In particular, we demonstrate that the sign of the nonlinear coupling between orthogonal modes is dependent on the cross-section aspect ratio. The findings are of interest for applications such as amplitude to frequency conversion and vectorial force sensing.

A universal and ultrasensitive vectorial nanomechanical sensor for imaging 2D force fields.

The miniaturization of force probes into nanomechanical oscillators enables ultrasensitive investigations of forces on dimensions smaller than their characteristic length scales. It also unravels the vectorial character of the force field and how its topology impacts the measurement. Here we present an ultrasensitive method for imaging two-dimensional vectorial force fields by optomechanically following the bidimensional Brownian motion of a singly clamped nanowire. This approach relies on angular and spectral tomography of its quasi-frequency-degenerated transverse mechanical polarizations: immersing the nanoresonator in a vectorial force field not only shifts its eigenfrequencies but also rotates the orientation of the eigenmodes, as a nanocompass. This universal method is employed to map a tunable electrostatic force field whose spatial gradients can even dominate the intrinsic nanowire properties. Enabling vectorial force field imaging with demonstrated sensitivities of attonewton variations over the nanoprobe Brownian trajectory will have a strong impact on scientific exploration at the nanoscale.

Vectorial scanning force microscopy using a nanowire sensor.

Self-assembled nanowire (NW) crystals can be grown into nearly defect-free nanomechanical resonators with exceptional properties, including small motional mass, high resonant frequency and low dissipation. Furthermore, by virtue of slight asymmetries in geometry, a NW's flexural modes are split into doublets oscillating along orthogonal axes. These characteristics make bottom-up grown NWs extremely sensitive vectorial force sensors. Here, taking advantage of its adaptability as a scanning probe, we use a single NW to image a sample surface. By monitoring the frequency shift and direction of oscillation of both modes as we scan above the surface, we construct a map of all spatial tip-sample force derivatives in the plane. Finally, we use the NW to image electric force fields distinguishing between forces arising from the NW charge and polarizability. This universally applicable technique enables a form of atomic force microscopy particularly suited to mapping the size and direction of weak tip-sample forces.

Time-Resolved Nonlinear Coupling between Orthogonal Flexural Modes of a Pristine GaAs Nanowire.

We demonstrate nonlinear coupling between two orthogonal flexural modes of single as-grown GaAs nanowires. The resonant frequency of one mode can be shifted over many line widths by mechanically driving the other mode. We present time-domain measurements of the mode coupling and characterize it further by pump-probe experiments. Measurements show that a geometric nonlinearity causes the frequency of one mode to depend directly on the square amplitude of the other mode. Nearly degenerate orthogonal modes in nanowires are particularly interesting given their potential use in vectorial force sensing.

Force Feedback Control System Dedicated for Robin Heart Surgical Robot

3D contact force sensors were developed and integrated in a demonstration system for testing the feasibility of their application in minimal invasive surgery (MIS). Piezoresistive MEMS based vectorial force sensors were designed and fabricated by 3D silicon micromachining technology and packaged according to their proposed transducer and sensor applications. In this work we demonstrated the integrability and functional applicability of the 3D force sensors in MIS robotic systems to improve their flexibility and reliability by providing real-time force and tactile information during the operation.The final goal is to integrate the new subsystems in the Robin Heart surgery robot of FRK. [1] Three different functions are targeted: 1. Micro-joystick actuator to be integrated in the hilt of the laparoscope to easily control robotic movement during operation. 2. Force sensor inside the laparoscopic jaw to provide feedback to the surgeon by measuring the grasping strength and 3. 3D force/tactile sensor which facilitates palpation for tissue diagnostics during operation. In this paper we demonstrate a feasibility study regarding these proposed applications.

Learning scheme to predict atomic forces and accelerate materials simulations

The behavior of an atom in a molecule, liquid or solid is governed by the force it experiences. If the dependence of this vectorial force on the atomic chemical environment can be $learned$ efficiently with high-fidelity from benchmark reference results-using "big data" techniques, i.e., without resorting to actual functional forms-then this capability can be harnessed to enormously speed up $in \ silico$ materials simulations. The present contribution provides several examples of how such a $force$ field for Al can be used to go far beyond the length-scale and time-scale regimes accessible presently using quantum mechanical methods. It is argued that pathways are available to systematically and continuously improve the predictive capability of such a learned force field in an adaptive manner, and that this concept can be generalized to include multiple elements.

Dynamic stability analysis of wedge in rock slope based on kinetic vector method

A new method (kinetic vector method, KVM) is presented for analyzing the dynamic stability of wedge in rock slope. The dynamic analysis is carried out based on three dimensional distinct element code (3DEC), and the kinetic inertial force of the wedge under seismic loading can be obtained via calculating the net vectorial nodal force of the finite difference grid. Then, the factor of safety (FOS) of the wedge can be calculated based on limit equilibrium method (LEM) at each dynamic analysis step, therefore time series of the FOS for whole earthquake process can be obtained. For the purpose of evaluating the entire dynamic stability of the wedge, dynamic factor of safety (DFOS) is proposed and defined as a numerical value corresponding with a given rate of probability guarantee based on reliability theory. Consequently, the KVM inherits the merits of the LEM and also has fully nonlinear dynamic analysis capabilities, and the feasibility and correctness of the KVM are tested by an example given by Hoek and Bray (1981). Finally, a rock slope case in Wenchuan Earthquake regions of China is presented to verify the engineering practicability of the KVM, and the results matched the actual situation well.

Measuring functional outcome after total hip replacement with subject-specific hip joint loading

Total hip replacement is an often-performed orthopedic surgical procedure; the amount of procedures undertaken will increase since our life expectancy is growing. In order to optimize function, hip biomechanics should be restored to as near normal as possible. The goal of this pilot study was to determine whether or not it is feasible to compute the vectorial hip reaction force pathways on the head of the prosthesis and the force angles relative to the cup of the prosthesis that occur during gait in total hip replacement patients, serving as an objective measurement of the functional outcome following hip replacement. A three-dimensional gait analysis, measuring ground reaction forces and kinematics, was performed. The data retrieved from the gait analysis was used as the input for the musculoskeletal model to compute vectorial joint reaction forces for data processing. To evaluate the position and orientation of the joint reaction forces, the force path, as well as the force angles for the operated and non-operated joint, has been calculated during the stance phase of the specific leg. The force path for subject 2 on the non-operated side is only located in the posterior-lateral quarter, as is the force path for subject 1. In contrast to this subject, the force path for subject 2 at the operated hip joint can be found only within the anterior quarter of the head of the implant, where it is nearly equally distributed in the medio-lateral half of the prosthesis head. The force-inclination angles on the cup of subject 1, with respect to the plane of the socket face, indicates that the force vector is mainly positioned in the same quadrant when compared with subject 2 (in a cup-fixed coordinate system). The force-anteversion angle behaves similarly to the force-inclination angle, even when the effects are not as pronounced. The proposed methods in this article are aiming to define two functional outcomes of total hip replacement that are related to wear and rim loading. It is accepted that wear is not only a function of time, but a function of use. Owing to the methods listed in this article, we are able to determine a) the applied force and b) the sliding distance (force pathway) in a subject-specific manner. The computed hip-reaction force angles and the distance to the rim cup are a measurement for cup or rim loading, and occurs in the so-called safe-zones. This method may well give us insight into the biomechanical situation during gait, after receiving total hip replacement, that we need to fully understand the mechanisms acting on a hip joint and to prove a possible increase of functional outcome after receiving total hip replacement.

Myosin Va and Myosin VI Engage in a “Tug of War” on Actin Tracks while Transporting Cargoes in vitro

Myosin Va (myoVa) and myosin VI (myoVI) are processive molecular motors that transport cargo in opposite directions on actin tracks. Since myoVa and myoVI may colocalize to the same cargo in vivo, these motors may undergo a tug of war. Therefore, we sought to characterize the stepping dynamics of single myoVa and myoVI motors in vitro as they mechanically interact when linked together by a Qdot cargo. Expressed myoVa-HMM with an N-terminal biotin tag were labeled with streptavidin-Qdots (565nm) while expressed dimerized myoVI-HMM were Qdot(655nm)-labeled on an exchanged calmodulin. The effective tug of war on actin filament tracks (25mM KCl, 2mM ATP, 22°C) was observed in TIRF with 6nm resolution, allowing individual steps to be detected. MyoVa won ∼80% of the time and regardless of which motor won, its stepping rate was reduced ∼50% below its unloaded value due to the resistive load of the opposing motor. Interestingly, as the winning motor stepped forwards (myoVa, 73nm; myoVI, 56nm) the opposing motor stepped backwards (myoVa, 68nm; myoVI, 65nm) at the same rate, although myoVI appeared to be dragged at times. Why does myoVa dominate when its stall force is similar to myoVI? Given the probability that both myoVa and myoVI take occasional backsteps and experience a 2-3-fold reduction in stepping rate when winning, we estimate based on optical trapping data (Altman et al., 2004; Kad et al., 2008) that myoVa exerts a 50% greater resistive load compared to myoVI, providing a potential advantage to myoVa. Differences in the length of the myoVa and myoVI constructs could lead to each motor experiencing different vectorial force components, the potential that this may influence the outcome of the tug of war is being investigated.

Dynamins at a glance

The superfamily of dynamins includes classical dynamins and dynamin-related proteins. Classical dynamins are proteins that share sequence similarity with the first described dynamin, which is a large GTPase with five characteristic domains. Dynamin-related proteins differ from classical dynamins in

Architecture of optimal transport networks

We analyze the structure of networks minimizing the global resistance to flow (or dissipative energy) with respect to two different constraints: fixed total channel volume and fixed total channel surface area. First, we show that channels must be straight and have uniform cross-sectional areas in such optimal networks. We then establish a relation between the cross-sectional areas of adjoining channels at each junction. Indeed, this relation is a generalization of Murray's law, originally established in the context of local optimization. We establish a relation too between angles and cross-sectional areas of adjoining channels at each junction, which can be represented as a vectorial force balance equation, where the force weight depends on the channel cross-sectional area. A scaling law between the minimal resistance value and the total volume or surface area value is also derived from the analysis. Furthermore, we show that no more than three or four channels meet at each junction of optimal bidimensional networks, depending on the flow profile (e.g., Poiseuille-like or pluglike) and the considered constraint (fixed volume or surface area). In particular, we show that sources are directly connected to wells, without intermediate junctions, for minimal resistance networks preserving the total channel volume in case of plug flow regime. Finally, all these results are compared with the structure of natural networks.

Mechanically driven ATP synthesis by F1-ATPase

ATP, the main biological energy currency, is synthesized from ADP and inorganic phosphate by ATP synthase in an energy-requiring reaction. The F1 portion of ATP synthase, also known as F1-ATPase, functions as a rotary molecular motor: in vitro its gamma-subunit rotates against the surrounding alpha3beta3 subunits, hydrolysing ATP in three separate catalytic sites on the beta-subunits. It is widely believed that reverse rotation of the gamma-subunit, driven by proton flow through the associated F(o) portion of ATP synthase, leads to ATP synthesis in biological systems. Here we present direct evidence for the chemical synthesis of ATP driven by mechanical energy. We attached a magnetic bead to the gamma-subunit of isolated F1 on a glass surface, and rotated the bead using electrical magnets. Rotation in the appropriate direction resulted in the appearance of ATP in the medium as detected by the luciferase-luciferin reaction. This shows that a vectorial force (torque) working at one particular point on a protein machine can influence a chemical reaction occurring in physically remote catalytic sites, driving the reaction far from equilibrium.