Podolsky's electromagnetic theory on the null-plane

We have analyzed the null-plane canonical structure of Podolsky's electromagnetic theory. As a theory that contains higher order derivatives in the Lagrangian function, it was necessary to redefine the canonical momenta related to the field variables. We were able to find a set of first and second-class constraints, and also to derive the field equations of the system. Copyright © owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.

Continuous torque system with control of the reaction unit

This article describes an orthodontic system used to obtain active continuous torque with movement control of both active and reactive units; the system relies on principles of the segmented technique. A cantilever system with .017 x .025-in beta-titanium alloy wire was designed to provide the desirable moment on the active unit. A transpalatal bar or a lingual arch increases the anchorage and neutralizes the side effects on the reactive unit. This technique is an efficient approach for major corrections of buccolingual inclinations of certain teeth. © 2010 American Association of Orthodontists.

Covariance for electromagnetic current for two bosons at higher order in the light front

We show that the electromagnetic current for a system composed by two charged bosons has a structure of many bodies even in the impulse approximation, when described in the time x +. In terms of the two body component for the bound state, the current contains two body operators. We discuss the process of pair creation by the photon and interpret it as a zero mode contribution to the current and its consequences for the components of currents in the light front. © 2010 American Institute of Physics.

Podolsky's electromagnetic theory on the null-plane gauge

Following the Dirac's technique for constrained systems we performed a detailed analysis of the constraint structure of Podolsky's electromagnetic theory on the null-plane coordinates. The null plane gauge condition was extended to second order theories and appropriate boundary conditions were imposed to guarantee the uniqueness of the inverse of the constraints matrix of the system. Finally, we determined the generalized Dirac brackets of the independent dynamical variables. © 2010 American Institute of Physics.

Performance and operation of the CMS electromagnetic calorimeter

The operation and general performance of the CMS electromagnetic calorimeter using cosmic-ray muons are described. These muons were recorded after the closure of the CMS detector in late 2008. The calorimeter is made of lead tungstate crystals and the overall status of the 75 848 channels corresponding to the barrel and endcap detectors is reported. The stability of crucial operational parameters, such as high voltage, temperature and electronic noise, is summarised and the performance of the light monitoring system is presented. © 2010 IOP Publishing Ltd and SISSA.

Time reconstruction and performance of the CMS electromagnetic calorimeter

The resolution and the linearity of time measurements made with the CMS electromagnetic calorimeter are studied with samples of data from test beam electrons, cosmic rays, and beam-produced muons. The resulting time resolution measured by lead tungstate crystals is better than 100 ps for energy deposits larger than 10 GeV. Crystal-to-crystal synchronization with a precision of 500 ps is performed using muons produced with the first LHC beams in 2008. © 2010 IOP Publishing Ltd and SISSA.

Influence of high insertion torque on implant placement - an anisotropic bone stress analysis

The aim of this study was to evaluate the influence of the high values of insertion torques on the stress and strain distribution in cortical and cancellous bones. Based on tomography imaging, a representative mathematical model of a partial maxilla was built using Mimics 11.11 and Solid Works 2010 softwares. Six models were built and each of them received an implant with one of the following insertion torques: 30, 40, 50, 60, 70 or 80 Ncm on the external hexagon. The cortical and cancellous bones were considered anisotropic. The bone/implant interface was considered perfectly bonded. The numerical analysis was carried out using Ansys Workbench 10.0. The convergence of analysis (6%) drove the mesh refinement. Maximum principal stress (σ max) and maximum principal strain (ε max) were obtained for cortical and cancellous bones around to implant. Pearson's correlation test was used to determine the correlation between insertion torque and stress concentration in the periimplant bone tissue, considering the significance level at 5%. The increase in the insertion torque generated an increase in the σ max and ε max values for cortical and cancellous bone. The σmax was smaller for the cancellous bone, with greater stress variation among the insertion torques. The ε max was higher in the cancellous bone in comparison to the cortical bone. According to the methodology used and the limits of this study, it can be concluded that higher insertion torques increased tensile and compressive stress concentrations in the periimplant bone tissue.

Modeling for performance analysis of electromagnetic zero-sequence suppressor

The purpose of this work is to present a frequency domain model to demonstrate the operation of an electromagnetic arrangement for controlling the injection of zero-sequence currents in the electrical system. Considering the diversity of sequential distribution of harmonic components of a current, the device proposed can be used in the process of mitigation of zero-sequence components. This device, here called electromagnetic suppressor, consists of a blocker and filter both electromagnetic, whose joint operation can provide paths of high and low impedances that can be conveniently adjusted in order to search for a desired performance. This study presents physical considerations, mathematical modeling and computer simulations that clearly demonstrate the viability of this application as a more viable alternative in the conception of filtering systems. The performance analysis is based on the frequency response of harmonic transmittances. The efficacy of this technique in direct actions to maximize the harmonic mitigation process is demonstrated. ©2010 IEEE.

Experimental analysis and adherence test of the electromagnetic zero-sequence blocking model

This paper reveals new contributions to the analysis and development of mitigating harmonic distortion devices. Considering the variety of sequential distribution of harmonic current, in the use of passive filters, one can point out the electromagnetic blocking device, which have received particular attention due to its robustness and low cost of installation. In this context, aiming the evaluation of the reliability of the results obtained through mathematical modeling, experimental tests are carried out using a low-power prototype, highlighting particular aspects related to its function as a zero-sequence harmonic blocking. © 2011 IEEE.

Bandgap voltage reference with low susceptibility to electromagnetic interference (EMI)

In this paper, the susceptibility of a current-mode bandgap voltage reference to electromagnetic interference (EMI) superimposed to the power supply is investigated by simulation. Designed for AMS 0.35 CMOS process, the circuit provides a stable voltage reference in the temperature range of -40-150°C. When EMI disturbances are present, the circuit exhibits only 6.7 mV of offset for interfering signals in the frequency range of 150 kHz-1 GHz. © 2011 ACM.

Maximal isokinetic peak torque and EMG activity determined by shorter ranges of motion

Purpose. Isokinetic tests are often applied to assess muscular strength and EMG activity, however the specific ranges of motion used in testing (fully flexed or extended positions) might be constrictive and/or be painful for patients with injuries or under-going rehabilitation. The aim of this study was to examine the effects of different ranges of motion (RoM) when determining maximal EMG during isokinetic knee flexion and extension with different types of contractions and velocities. Methods. Eighteen males had EMG activity recorded on the vastus lateralis, vastus medialis, semitendinosus and biceps femoris muscles during five maximal isokinetic concentric and eccentric contractions for the knee flexors and extensors at 60° • s -1 and 180° • s -1. The root mean square of EMG was calculated at three different ranges of motion: (1) a full range of motion (90°-20° [0° = full knee extension]); (2) a range of motion of 20° (between 60°-80° and 40°-60° for knee extension and flexion, respectively) and (3) at a 10° interval around the angle where peak torque is produced. EMG measurements were statistically analyzed (ANOVA) to test for the range of motion, contraction velocity and contraction speed effects. Coefficients of variation and Pearson's correlation coefficients were also calculated among the ranges of motion. Results. Predominantly similar (p > 0.05) and well-correlated EMG results (r > 0.7, p ≤ 0.001) were found among the ranges of motion. However, a lower coefficient of variation was found for the full range of motion, while the 10° interval around peak torque at 180° • s -1 had the highest coefficient, regardless of the type of contraction. Conclusions. Shorter ranges of motion at around the peak torque angle provides a reliable indicator when recording EMG activity during maximal isokinetic parameters. It may provide a safer alternative when testing patients with injuries or undergoing rehabilitation.

Experimental analysis of an electromagnetic zero-sequence suppressor

The intent of this paper is to present contributions focused on the analysis and development of harmonic attenuator devices. Among these, highlights here the so-called electromagnetic zero-sequence suppressor. This arrangement consists of a filter and a blocker, both electromagnetic, whose combined operation provides paths for low and high impedance, respectively, which can be conveniently adjusted to the desired performance. In this context, here are present results related to experimental studies that show the behavior of the equipment in front of different operating conditions. The tests were performed on a low-power prototype (1kVA/220V) and the analysis results show the main motivator aspects for the use of these devices. © 2012 IEEE.

Analysis of primary stability of dental implants inserted in different substrates using the pullout test and insertion torque

The aim of the study was to evaluate mechanical behavior of implants inserted in three substrates, by measuring the pullout strength and the relative stiffness. 32 implants (Master Porous-Conexao, cylindrical, external hexagon, and surface treatment) were divided into 4 groups (n = 8): pig rib bone, polyurethane Synbone, polyurethane Nacional 40 PCF, and pinus wood. Implants were installed with the exact distance of 5 mm of another implant. The insertion torque (N·cm) was quantified using the digital Kratos torque meter and the pullout test (N) was performed by an axial traction force toward the long axis of the implant (2 min/mm) through mount implant devices attached to a piece adapted to a load cell of 200 Kg of a universal testing machine (Emic DL10000). Data of insertion torque and maximum pullout force were submitted to one-way ANOVA and Bonferroni tests (α = 0.05). Polyurethane Nacional 40 PCF and pinus wood showed the highest values of insertion torque and pullout force, with significant statistical difference (P < 0.05) with other groups. The analysis showed stiffness materials with the highest values for primary stability. © 2013 Nathalia Ferraz Oliscovicz et al.

Hamilton-Jacobi formalism to Podolsky electromagnetic theory on the null-plane

In this work we develop the Hamilton - Jacobi formalism to study the Podolsky electromagnetic theory on the null-plane coordinates. We calculate the generators of the Podolsky theory and check the integrability conditions. Appropriate boundary conditions are introduced to assure uniqueness of the Green functions associated to the differential operators. Non-involutive constraints in the Hamilton-Jacobi formalism are eliminated by constructing their respective generalized brackets. © 2013 American Institute of Physics.

Ideas of four-fermion operators in electromagnetic form factor calculations

Four-fermion operators have been used in the past to link the quark-exchange processes in the interaction of hadrons with the effective meson-exchange amplitudes. In this paper, we apply the similar idea of a Fierz rearrangement to the self-energy and electromagnetic processes and focus on the electromagnetic form factors of the nucleon and the electron. We explain the motivation of using four-fermion operators and discuss the advantage of this method in computing electromagnetic processes. © 2013 American Physical Society.