INTRUSION ARC IN ORTHODONTIC:

The intrusion arch is a device for orthodontic anterior teeth intrusion, having been introduced by Burstone in 1977 for the treatment of deep bite, especially in the case of Class II division 2. But they are based on the origin of malocclusion and the patient's clinical characteristics, such as smile line, vertical dimension, predicted growth, among others. Use of this arc is governed by the principles of mechanical intrusion, which include obtaining a pure no intrusion proclination movements, therefore, necessary for successful treatment. Among these we can highlight to get a constant magnitude of force and the choice of point of application of force in the anterior segment, which would determine whether the motion would be pure intrusion or intrusion inclined. The mechanical stability of this is making it more advantageous in the treatment of deep bite in relation to treatment with extrusion of posterior teeth, which is notoriously prone to relapse. Thus, based on the principles of mechanics and its stability, several authors have developed some type of intrusion arches, using the original biomechanics, but differing mainly in the type of alloy wire and the point of application of force to the center of resistance to achieve the goals of the treatment

Validity of Mechanical advantage hypothesis of human grasping depends on the nature of task difficulty

Successful object interaction during daily living involves maintaining the grasped object in a static equilibrium by properly arranging the fingertip contact forces. According to the mechanical advantage hypothesis, during supination or pronation torque production, fingers with longer moment arms would produce greater normal force than those with shorter moment arms. Previous studies have probed this hypothesis by investigating the force contributions of the individual fingers through systematic variations (or perturbations) of properties of the grasped handle. In the current study, we examined the applicability of this hypothesis in a paradigm wherein the thumb tangential force was constrained to a minimal constant magnitude. This was achieved by placing the thumb on a freely movable slider platform. The total mass of the handle was systematically varied by adding external loads directly below the center of mass of the handle. Our findings suggest that in the human hand, the central nervous system (CNS) adopts the principle of mechanical advantage depending on an abstract sense of challenge attached to the task situation.

Resonant Instability of Kink Oscillations in Magnetic Flux Tubes with Siphon Flow

We study kink oscillations of a straight magnetic tube in the presence of siphon flows. The tube consists of a core and a transitional or boundary layer. The flow velocity is parallel to the tube axis, has constant magnitude, and confined in the tube core. The plasma density is constant in the tube core and it monotonically decreases in the transitional layer to its value in the surrounding plasma. We use the expression for the decrement/increment previously obtained by Ruderman and Petrukhin (Astron. Astrophys.631, A31, 2019) to study the damping and resonant instability of kink oscillations. We show that, depending on the magnitude of siphon-velocity, resonant absorption can cause either the damping of kink oscillations or their enhancement. There are two threshold velocities: When the flow velocity is below the first threshold velocity, kink oscillations damp. When the flow velocity is above the second threshold velocity, the kink oscillation amplitudes grow. Finally, when the flow velocity is between the two threshold velocities, the oscillation amplitudes do not change. We apply the theoretical result to kink oscillations of prominence threads. We show that, for particular values of thread parameters, resonant instability can excite these kink oscillations.

Chaos on the hypercube

We analyze the spectral properties of a d-dimensional HyperCubic (HC) lattice model originally introduced by Parisi. The U(1) gauge links of this model give rise to a magnetic flux of constant magnitude ϕ but random orientation through the faces of the hypercube. The HC model, which also can be written as a model of 2d interacting Majorana fermions, has a spectral flow that is reminiscent of Maldacena-Qi (MQ) model, and its spectrum at ϕ = 0, actually coincides with the coupling term of the MQ model. As was already shown by Parisi, at leading order in 1/d, the spectral density of this model is given by the density function of the Q-Hermite polynomials, which is also the spectral density of the double-scaled Sachdev-Ye-Kitaev model. Parisi demonstrated this by mapping the moments of the HC model to Q-weighted sums on chord diagrams. We point out that the subleading moments of the HC model can also be mapped to weighted sums on chord diagrams, in a manner that descends from the leading moments. The HC model has a magnetic inversion symmetry that depends on both the magnitude and the orientation of the magnetic flux through the faces of the hypercube. The spectrum for fixed quantum number of this symmetry exhibits a transition from regular spectra at ϕ = 0 to chaotic spectra with spectral statistics given by the Gaussian Unitary Ensembles (GUE) for larger values of ϕ. For small magnetic flux, the ground state is gapped and is close to a Thermofield Double (TFD) state.

Analog Beamforming in Millimeter Wave MIMO Systems

In traditional analog beamforming schemes, like the beam selection method, use the strongest path array steering vector of the channel to generate a beam pointing to the user. In multi-user systems, such schemes will result in the large interference among the users, especially when the users are closely located. In this paper, we designed an analog beamforming scheme for downlink mm-wave multi-user systems to enhance the beamforming gain and suppress the inter-user interference at the same time. A multi-objective problem is developed to beat a balance between the inter-user interference and the beamforming gain. To solve the problem, we firstly use the weighted-sum method and then 𝜺 -constraint method to transform the multi-objective problem into a single-objective problem. Then, the analog beamforming is made tractable with the constant-magnitude constraints with the use of semidefinite programing technique. Adding to these, the robust beamforming is designed to mitigate the effects of the channel estimation and to provide the robustness against the imperfect channel information. The simulation results shows that the 𝜺 -constraint method outperforms when compared with the weighted-sum method at high SNR’s for the robust multi-user analog beamforming

ISOGEOMETRIC – BASED DYNAMIC ANALYSIS OF BERNOULLI – EULER CURVED BEAM SUBJECTED TO MOVING LOAD

In this paper dynamic analysis of a curved Bernoulli – Euler beam subjected to a moving load ispresented. Moving load is modelled as a single force with constant magnitude and direction, whichmoves along its trajectory. Plane curved Bernoulli – Euler beam element is formulated usingisogeometric approach where both the displacement field and geometry of the beam are describedusing NURBS basis functions. Behavior of the beam element is defined and studied in the case oflinear formulation where displacements and displacement gradients are assumed to be small.Validation of the proposed approach is presented for the plane curved beam subjected to movingload with constant velocity, magnitude and direction.

Extensivity and entropy current at thermodynamic equilibrium with acceleration

We derive a sufficient condition for the existence of the entropy current of a fluid at local thermodynamic equilibrium using relativistic quantum statistical mechanics, and put forward a general method to calculate it. We also work out a specific calculation in a non-trivial case of interest, namely a system at global thermodynamic equilibrium with proper acceleration of constant magnitude along the flow lines in Minkowski space–time, whose lowest possible proper temperature is the Unruh temperature. In this case, we show that the integral of the entropy current in the right Rindler wedge is the entanglement entropy with the left Rindler wedge.

Flexural Motions of Beams on Foundation Subjected to Moving Concentrated Force

In this present paper, the dynamic analysis of nonprismastic beams subjected to moving concentrated forces is investigated at constant speed. Two cases of load- beam interaction problems described by the Dirac delta function with constant and harmonic magnitude mobile forces are studied. The technique called Galerkin’s method in conjunction with integral transform method was employed to solve the motion equation. From the numerical results, it is evidently seen that an increase in the foundation stiffness provides reduction on the beam deflection. And furthermore, the issue of resonance is closely monitored and observed to have reached earlier in constant magnitude than harmonic variable magnitude problem. Results presented in this work are useful in constructions engineering designs.

Fractional-Order Phase Shifters with Constant Magnitude Frequency Responses

This contribution presents and experimentally analyzes the idea how to reach the constant magnitude as well as the phase response in the fractional-order (FO) phase when shifting two-ports. The straightforward method employing the automatic gain control circuit (AGC) in a cascade after so-called constant phase block approximating FO integrator or differentiator is studied. The variable gain amplifier utilized in AGC and simple RC-based FO constant phase elements (approximating capacitors with order alpha = 1/4 and alpha = 1/2 as an example) connected in the feedback of operational amplifier-based integrator are established in the experimental setup. The operation indicated in three decades (between 100 Hz and 100 kHz) is evaluated. The known solutions of the standard FO phase shifting circuits are discussed and generally compared with the features obtained in this paper, together with the supposed effects of AGC on their performances.