Vertical and Orovestibular Forces Generated by Beta-Titanium and Stainless-Steel Rectangular Wires in Labial and Fully Customized Lingual Bracket Systems

This study aimed to investigate the force values exerted from rectangular wires when combined with conventional labial and fully customized lingual appliances under predefined, idealized activation. Fully customized lingual brackets of two brands Incognito™ (3M Unitek, Monrovia, MN, USA) and WIN (DW Lingual Systems, Bad Essen, Germany) and labial brackets of another brand, discovery® MIM and discovery® smart systems (Dentaurum, Ispringen, Germany), were chosen. Stainless-steel and beta-titanium wires of 0.018” × 0.025” were examined. For IncognitoTM, 0.0182” × 0.025” beta-titanium wires were tested. Intrusion/extrusion and orovestibular movements were performed in a range of 0.2 mm, and the forces were recorded for each 0.1 mm of the movement. Mean values and standard deviations were calculated for all measurements, and ANOVA was performed for statistical analysis. Slight differences were observed between the forces generated from beta-titanium and stainless-steel wires. The same wire generated in some cases 5–53% higher forces with the lingual appliance due to the vertical orientation of the long walls during intrusion/extrusion and increased wire stiffness at the anterior region. Beta-titanium and stainless-steel 0.018” × 0.025” wires can generate similar force values during the final stages of the orthodontic therapy; thus, possibly only one of the two alloys could be used in each orthodontic wire sequence.

Calculation of a magnetic force acting on small superconducting celestial bodies

Recent discoveries of superconducting phases in the samples of meteorites suggest the possibility of a natural occurrence of superconducting state in space. Superconductors are known to exhibit interesting behaviours when subjected to external magnetic fields, such as levitation. Similar force may act on a superconducting bit in space. The goal of this paper is to quantify this force and assess its effects. Several scenarios in which a superconducting bit can be produced and interact with a magnetic field in space are suggested. The force acting on a superconductor in different conditions is calculated with numerical simulations. The dependence on a magnetic flux density, its gradient, and the geometry and the properties of the superconductor are found. The empirical formulas are derived and used to calculate a magnetic force. The resultant force is extremely weak in all analysed scenarios. It is found that its strength decreases rapidly with the distance from the source of the magnetic flux. Its effect on trajectory of the superconductor is almost negligible. Some possibilities of increasing its strength and the effects are considered.

Towards Reducing Risk of Injury in Nursing: Design and Analysis of a New Passive Exoskeleton for Torso Twist Assist

Nursing is among the most physically challenging occupations and involves intensive lifting activities often including twisting of torso while performing tasks such as patient handling. Frequent and repetitive twisting of the body is known to induce large demands on the musculature, which may lead to MSD with direct and indirect costs to the hospital governance. One solution proposed through this article includes an exoskeleton specifically designed to assist in twisting movements of the trunk. This involves a double-actuator fully passive system that assists in rotation of the torso with the help of mechanical springs and cable modules. Our study provides a conceptual design of the mechanism, and a preliminary analysis using the concepts of kinematics, dynamics, usability, wearability, and freedom of movement. Results show that the mechanism could offer freedom of rotation for the wearer’s torso up to 52, 25 and 22 degrees (with stationary hip joint) along the transverse, sagittal and coronal planes, respectively. Moreover, similar force generation (up to 80N) was obtained in both actuators for same rotation on transverse plane in both directions for a combination of spring stiffness (0.5 – 1 N/mm) and damping (0.1 - 0.5 N-sec/mm) parameters. Our proposed design could also be integrated to the current exoskeletons in the form of a module and could be beneficial in more general work settings.

Effects of Concentric and Eccentric Strength Training on Fatigue Induced by Concentric and Eccentric Exercises

Purpose: To compare the concentric and eccentric training effects on fatigue induced by eccentric and concentric protocols. Methods: A total of 22 men and women (22 [3.6] y) were assigned to concentric (GCON, n = 11) or eccentric training (GECC, n = 11). The concentric (CON) and eccentric (ECC) protocols were composed of 4 sets of 20 knee-extension/flexion repetitions. Force losses were analyzed by comparing 10 repetitions’ mean torques during the protocols and by verifying the maximal voluntary contraction and rate of torque development before and after the protocols. Muscle damage was assessed using echo intensity of the vastus lateralis 48 h after the protocols. Training consisted of 6 wk of isokinetic exercise at 60°/s (concentric or eccentric) twice weekly. Results: Before training, both protocols resulted in dynamic and isometric force losses in GCON and GECC (P < .01), but the magnitude was greater after the CON protocol than after the ECC protocol (P < .001). After training, both GCON and GECC showed similar force decreases during the CON and ECC protocols (P < .01), and these changes were not different from the pretraining decreases. Regarding maximal voluntary contraction after training, GECC showed lower force decreases than GCON after ECC exercise (−13.7% vs −22.3%, respectively, P < .05), whereas GCON showed lower maximal voluntary contraction decreases after CON exercise compared with pretraining (−29.2%, P < .05). Losses in rate of torque development were similar after the protocols before and after the training regimens. No changes in echo intensity were observed after the protocols before and after training. Conclusion: Both interventions resulted in similar force decreases during fatigue protocols compared with those associated with pretraining.

Gait Rehab Adaptive Machine: Design of GRAM, a Walking Linkage Powered Wheelchair for Lower Body Therapy and Assistance

Nearly half of individuals with stroke experience some form of long-term disability and stroke is one of the main causes of wheelchair use in the United States [1]. Early rehabilitation in the acute phase of stroke has been shown critical to promoting motor plasticity and patient outcomes. However, research shows that only 32% of the time during inpatient rehabilitation is spent in active therapy, while the rest of the time is spent on other activities around the ward [2]. For walking impairment, it is especially important for patients to experience similar force loading and practice the patterning of gait in order to recover [3]. However, in a typical therapy session focused on gait rehabilitation patients only will take about 300 steps on average. This is far below what has been thought needed for humans to learn how to walk [4].

Feasibility of International Proposed Standardized Enteral Connector for Semi-Solid Formula Feeding

Background/Aims: The current study was undertaken to assess if the semi-solid formulas could be used with a new ENFit connector with similar force to current percutaneous endoscopic gastrostomy (PEG) tubes. Methods: Experiment 1: We measured the applied pressure (force) needed to compress the syringe containing 7 viscous semi-solid formulas with a 20 Fr PEG tube and low-profile tube through the ENFit connector or the current connector. Experiment 2: This experiment was conducted to evaluate the compression force through 2 connectors in 3 infusion velocity, 7 PEG tube types with 2 semi-solid formulas. Results: Experiment 1: The force needed to compress the syringe through the ENFit connector was higher in 3 semi-solid formulas with a 20 Fr low-profile tube; otherwise, there were no significant differences. Experiment 2: Each formula required a higher force in the ENFit connector in 6 settings out of 21. Conclusions: The ENFit connector will likely not show any remarkable change in the force to administer the semi-solid formula. However, a higher force was required under some conditions in the prototype ENFit connector. Further investigation of sensory test is needed to confirm the feasibility of the ENFit connector for using the semi-solid formulas.

CASES OF INTEGRABILITY CORRESPONDING TO THE PENDULUM MOTION IN FOUR-DIMENSIONAL SPACE

In this article, we systemize some results on the study of the equations of motion of dynamically symmetric fixed four-dimensional rigid bodies–pendulums located in a nonconservative force fields. The form of these equations is taken from the dynamics of real fixed rigid bodies placed in a homogeneous flow of a medium. In parallel, we study the problem of the motion of a free four-dimensional rigid body also located in a similar force fields. Herewith, this free rigid body is influenced by a nonconservative tracing force; under action of this force, either the magnitude of the velocity of some characteristic point of the body remains constant, which means that the system possesses a nonintegrable servo constraint. We also show the nontrivial topological and mechanical analogies.

Cases of integrability corresponding to the pendulummotion on the plane

In this article, we systemize the results on the study of plane-parallel motion equations of fixed rigid body-pendulum which is placed in certain nonconserva- tive force field. In parallel, we consider the problem of a plane-parallel motion of a free rigid body which is also placed in a similar force field. Thus, the non-conservative tracking force operates onto this body. That force forces the value of certain point of a body to be constant for all the time of a motion, which means the existence of nonintegrable servoconstraint in the system. The obtained results are systematized and served in the invariant form. We also show the nontrivial topological and mechanical analogies.