Fundação de Apoio a Pesquisa e à Inovação Tecnológica do Estado de Sergipe - FAPITEC/SE / Studies report that alternating current is more effective in promoting analgesia than low frequency pulsed currents. However, the hypoalgesic potential and the clinical use of the medium frequency alternating current in kHz (Aussie) are based on hypothetical mechanisms of action. The present study aimed to investigate the hypoalgesic potential of the Aussie Current (AC) in healthy individuals. Eighty-one healthy subjects underwent electrostimulation by using kilohertz-frequency alternating current for 20 minutes and were randomized into three distinct groups (1 kHz, 4 kHz or placebo). Pressure pain threshold (PPT, algometry), conditioned pain modulation (CPM, ischemic pain in the contralateral upper limb and algometry), temporal summation (TS, algometry) were measured before and after intervention, the level of anxiety (STAI-T and STAI-E), in turn, was measured only at the pre-intervention. At the end of the protocol, subjects were questioned regarding the treatment they received and the comfort during the stimulation (numerical scale) and, similarly, investigators were questioned about their expectation related to subject’s allocation groups. These responses were recorded and used to test the adequacy of the masking procedure regarding the subject and the investigator. The level of anxiety evaluated did not a statistically significant difference between the groups, who received the active AC (1 kHz / 4kHz) or placebo, (p> 0.05). Regarding PPT, there was no statistically significant difference in the active AC 1 kHz, active 4 kHz and placebo groups at any of the moments evaluated. The active group AC 4 kHz presented a statistically significant reduction in the amplification of pain intensity, verified by the reduction of perceived pain intensity, in the tenth (p = 0.02), twentieth (p = 0.01) and thirtieth second (p = 0.001) in the TS test. The active group AC 1 kHz, in turn, presented significant reduction of pain intensity only at the end of the measurement (thirty-second, p = 0.01). In the evaluation of the CPM, there was no significant difference of the PPT, during induction of ischemia, in the AC active groups 4 kHz and active AC 1 kHz, before and after intervention (p> 0.05). However, in the placebo group there was a significant reduction in PPT, only during induced ischemia, both before and after intervention (p = 0.01). Thus, our study provides evidence that kilohertz-frequency AC current, especially when used with an equivalent 4 kHz frequency, presents hypoalgesic effect, having having possible inhibitory action in the Central Nervous System (CNS). / Estudos relatam que a corrente alternada é mais eficaz em promover analgesia que as correntes pulsadas de baixa frequência. Porém, o potencial hipoalgésico e a utilização clínica da corrente alternada de média frequência em kHz (Aussie) são baseados em mecanismos de ação hipotéticos. O presente estudo teve, como objetivo, investigar o potencial hipoalgésico da corrente Aussie (CA) em indivíduos saudáveis. Oitenta e um sujeitos saudáveis foram submetidos à eletroestimulação com corrente alternada de média frequência em quilohertz durante 20 minutos, sendo randomizados em três grupos distintos (1 kHz, 4 kHz ou placebo). Limiar de dor por pressão (LDP, algometria), modulação condicionada da dor (MCD, dor isquêmica no membro superior contralateral e algometria), somação temporal (ST, algometria) foram mensurados antes e após intervenção, o nível de ansiedade (IDATE-T e IDATE-E), por sua vez, foi mensurado apenas no momento pré-intervenção. Ao final do protocolo, os sujeitos foram questionados com relação ao tratamento que receberam e o conforto durante a estimulação (escala numérica) e, similarmente, os avaliadores sobre sua expectativa relacionada ao grupo de alocação dos sujeitos. Estas respostas foram registradas e usadas para testar a adequação do procedimento de mascaramento referente ao sujeito e ao investigador. O nível ansiedade, avaliado no momento pré-intervenção, não diferiu entre os grupos que receberam a CA ativa (1 kHz/ 4 kHz) ou placebo, sendo p>0,05. Em relação ao LDP, não houve diferença estatisticamente significativa nos grupos de intervenção CA ativa 1kHz, ativa 4 kHz e placebo em nenhum dos momentos avaliados. O grupo ativo CA 4 kHz apresentou redução estatisticamente significativa da amplificação da intensidade da dor, verificada pela redução da intensidade de dor percebida, no décimo (p=0,02), vigésimo (p=0,01) e trigésimo segundos (p=0,001), no teste de ST. O grupo ativo CA 1 kHz, por sua vez, apresentou redução significativa da intensidade de dor apenas no final da mensuração (trigésimo segundo; p=0,01). Na avaliação da MCD, não houve diferença significativa do LDP, durante a indução de isquemia, nos grupos CA ativo 4 kHz e CA ativo 1 kHz, no momento antes e após intervenção (p>0,05). No entanto, no grupo placebo, houve redução significativa do LDP, apenas durante a isquemia induzida, comparando pré e pós-intervenção (p=0,01). Dessa forma, o nosso estudo, fornecem evidências de que a corrente aussie, principalmente, quando utilizada com frequência equivalente 4 kHz, apresenta resultados hipoalgésicos, tendo possível ação inibitória no sistema nervoso central (SNC).

Orientador: Gilmar Barreto / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-09T16:50:00Z (GMT). No. of bitstreams: 1 Giesbrecht_Mateus_M.pdf: 3904732 bytes, checksum: 55e43903b08b7c8d770f9120fb071c40 (MD5) Previous issue date: 2007 / Resumo: A motivação para este estudo é criar um modelo computacional capaz de prever se o regime de trabalho a que um motor monofásico de indução é submetido implica ou não em um aquecimento que comprometa os materiais isolantes do mesmo. A solução apresentada busca encontrar uma equação a diferenças em que a saída do sistema (temperatura do motor no instante k+1) é calculada como uma combinação linear das entradas (temperatura do motor, valor RMS da corrente e temperatura ambiente no instante k). Para conhecer os coeficientes desta combinação linear, foram realizados alguns ensaios e, a partir de seus resultados, foi aplicado o método dos mínimos quadrados para a obtenção do modelo computacional que representa o sistema. Os resultados computacionais obtidos com o modelo proposto refletem com exatidão o comportamento do sistema real. O modelo desenvolvido também é útil para outras aplicações em que se utilize um motor de indução monofásico em regime intermitente periódico com partida / Abstract: This study motivation was finding a computer-based model that was able to foresee if the duty cycle applied in a single-phase induction motor implies or not in an overheating that can compromise the motor insulation. The solution presented here is based on finding a difference equation in which the system output (motor temperature at time k+1) is calculated as a linear combination of the input (motor temperature, RMS current and ambient temperature at time k). The Mean Square Method was applied to find the coefficients of this linear combination, resulting in the final computational model that represents the system. The computational results found with the proposed model reflect exactly the real system behaviour. This model is also useful to other applications in which a single-phase induction motor during intermittent periodic duty with starting is used. / Mestrado / Automação / Mestre em Engenharia Elétrica

Conventional therapeutic techniques treat the patient by delivering a biotherapeutic to the entire body rather than the target tissue. In the case of chemotherapy, the biotherapeutic is a drug that kills healthy and diseased cells indiscriminately which can lead to undesirable side effects. With targeted delivery, biotherapeutics can be delivered directly to the diseased tissue significantly reducing exposure to otherwise healthy tissue. Typical composite delivery devices are minimally composed of a stimuli responsive polymer, such as poly(N-isopropylacrylamide), allowing for triggered release when heated beyond approximately 32 °C, and magnetic nanoparticles which enable targeting as well as provide a mechanism for stimulus upon alternating magnetic field heating. Although more traditional methods, such as emulsion polymerization, have been used to realize these composite devices, the synthesis is problematic. Poisonous surfactants that are necessary to prevent agglomeration must be removed from the finished polymer, increasing the time and cost of the process. This study seeks to further explore non-toxic, biocompatible, non-residual, photochemical methods of creating stimuli responsive nanogels to advance the targeted biotherapeutic delivery field. Ultraviolet photopolymerization promises to be more efficient, while ensuring safety by using only biocompatible substances. The reactants selected for nanogel fabrication were N-isopropylacrylamide as monomer, methylene bisacrylamide as cross-linker, and Irgacure 2959 as ultraviolet photo-initiator. The superparamagnetic nanoparticles for encapsulation were approximately 10 nm in diameter and composed of magnetite to enable remote delivery and enhanced triggered release properties. Early investigations into the interactions of the polymer and nanoparticles employ a pioneering experimental setup, which allows for coincident turbidimetry and alternating magnetic field heating of an aqueous solution containing both materials. Herein, a low-cost, scalable, and rapid, custom ultraviolet photo-reactor with in-situ, spectroscopic monitoring system is used to observe the synthesis as the sample undergoes photopolymerization. This method also allows in-situ encapsulation of the magnetic nanoparticles simplifying the process. Size characterization of the resulting nanogels was performed by Transmission Electron Microscopy revealing size-tunable nanogel spheres between 50 and 800 nm by varying the ratio and concentration of the reactants. Nano-Tracking Analysis indicates that the nanogels exhibit minimal agglomeration as well as provides a temperature-dependent particle size distribution. Optical characterization utilized Fourier Transform Infrared and Ultraviolet Spectroscopy to confirm successful polymerization. When samples of the nanogels encapsulating magnetic nanoparticles were subjected to an alternating magnetic field a temperature increase was observed indicating that triggered release is possible. Furthermore, a model, based on linear response theory that innovatively utilizes size distribution data, is presented to explain alternating magnetic field heating results. The results presented here will advance targeted biotherapeutic delivery and have a wide range of applications in medical sciences like oncology, gene delivery, cardiology and endocrinology.

Compared to other children, children with Autism Spectrum Disorder (ASD) are known to engage less in joint attention - the sharing of attention between two individuals toward a common object or event. Joint attention behaviors - for example gaze following, alternating gaze, and pointing - play an important role in early development, as they provide a foundation for learning and social interaction. Study I and Study II focused on infant siblings of children with ASD. These infants, often termed high risk (HR) infants, have an increased probability of receiving a later ASD diagnosis. Studying them therefore allows for the detection of early signs of ASD. Live eye tracking was used to investigate different joint attention behaviors at 10 months of age. Study I showed that omitting the head movement that usually accompany experimenters’ eye gaze shifts in similar designs reduced gaze following performance in the HR group, but not in a group of infants at low risk (LR) for ASD. HR infants may thus be less sensitive to eye information, or may need more salient cues in order to follow gaze optimally. Study II focused on the infants’ tendency to initiate joint attention by alternating their gaze between a person and an event. LR infants engaged more in alternating gaze than HR infants, and less alternating gaze in infancy was associated with more ASD symptoms at 18 months. This relation remained when controlling for visual disengagement and general social interest in infancy. Study III explored the role of joint attention later in development, by investigating the microstructure of the looking behaviors of autistic and typically developing children (~6 years old). The results indicated that seeing somebody look at an object influenced the processing of that object less in autistic children than in the typically developing controls. Both groups followed gaze effectively, suggesting that differences in joint attention at this age may be subtle, but detectable with eye tracking technology. Together, the studies contribute to our understanding of the role that joint attention atypicalities play both in the early development of infants at risk for ASD, and later in the development of children with a confirmed diagnosis.

No description available.

The efficiency of the conventional, explicit finite difference time domain (FDTD)method is constrained by the upper limit on the temporal discretization, imposed by the Courant–Friedrich–Lewy (CFL) stability condition. Therefore, there is a growing interest in overcoming this limitation by employing unconditionally stable FDTD methods for which time-step and space-step can be independently chosen. Unconditionally stable Crank Nicolson method has not been widely used in time domain electromagnetics despite its high accuracy and low anisotropy. There has been no work on the Crank Nicolson FDTD (CN–FDTD) method for frequency dependent medium. In this thesis a new three-dimensional frequency dependent CN–FDTD (FD–CN–FDTD) method is proposed. Frequency dependency of single–pole Debye materials is incorporated into the CN–FDTD method by means of an auxiliary differential formulation. In order to provide a convenient and straightforward algorithm, Mur’s first-order absorbing boundary conditions are used in the FD–CN–FDTD method. Numerical tests validate and confirm that the FD–CN–FDTD method is unconditionally stable beyond the CFL limit. The proposed method yields a sparse system of linear equations which can be solved by direct or iterative methods, but numerical experiments demonstrate that for large problems of practical importance iterative solvers are to be used. The FD–CN–FDTD sparse matrix is diagonally dominant when the time-stepis near the CFL limit but the diagonal dominance of the matrix deteriorates with the increase of the time-step, making the solution time longer. Selection of the matrix solver to handle the FD–CN–FDTD sparse system is crucial to fully harness the advantages of using larger time-step, because the computational costs associated with the solver must be kept as low as possible. Two best–known iterative solvers, Bi-Conjugate Gradient Stabilised (BiCGStab) and Generalised Minimal Residual (GMRES), are extensively studied in terms of the number of iteration requirements for convergence, CPU time and memory requirements. BiCGStab outperforms GMRES in every aspect. Many of these findings do not match with the existing literature on frequency–independent CN–FDTD method and the possible reasons for this are pointed out. The proposed method is coded in Fortran and major implementation techniques of the serial code as well as its parallel implementation in Open Multi-Processing (OpenMP) are presented. As an application, a simulation model of the human body is developed in the FD–CN–FDTD method and numerical simulation of the electromagnetic wave propagation inside the human head is shown. Finally, this thesis presents a new method modifying the frequency dependent alternating direction implicit FDTD (FD–ADI–FDTD) method. Although the ADI–FDTD method provides a computationally affordable approximation of the CN–FDTD method, it exhibits a loss of accuracy with respect to the CN-FDTD method which may become severe for some practical applications. The modified FD–ADI–FDTD method can improve the accuracy of the normal FD–ADI–FDTD method without significantly increasing the computational costs.

No description available.

In this work, we propose a specialization of the inductive incremental coverability algorithm that solves alternating finite automata emptiness problem. We experiment with various design decisions, analyze them and prove their correctness. Even though the problem itself is PSpace-complete, we are focusing on making the decision of emptiness computationally feasible for some practical classes of applications. We have obtained interesting comparative results against state-of-the-art algorithms, especially in comparison with antichain-based algorithms.

Inorganic alternating current electroluminescent devices (AC-ELs) are known for their ruggedness and extreme long-term reliability, which is why they can often been found in industrial and medical equipment as well as in applications in the military sector. In contrast to the inorganic phosphors used in AC-ELs, organic materials offer a number of advantages, in particular a significantly higher efficiency, easier processibility, and a wide selection of emitter materials spanning the entire visible spectrum. Several efforts towards alternating current driven organic light-emitting devices have recently been made, however, important operating mechanism are still not well understood. In the first part of this theses, alternating current driven, capacitively coupled, pin-based organic light-emitting devices are investigated with respect to the influence of the thickness of the insulating layer and the intrinsic organic layer on the driving voltage. A three-capacitor model is employed to predict the basic behavior of the devices and good agreement with the experimental values is found. The proposed charge regeneration mechanism based on Zener tunneling is studied in terms of field strength across the intrinsic organic layers. A remarkable consistency between the measured field strength at the onset point of light emission (3–3.1 MV/cm) and the theoretically predicted breakdown field strength of around 3 MV/cm is obtained. The latter value represents the field required for Zener tunneling in wide band gap organic materials according to Fowler-Nordheim theory. In a second step, asymmetric driving of capacitively coupled OLEDs is investigated. It is found that different voltages and/or pulse lengths for positive and negative half-cycle lead to significant improvements in terms of brightness and device efficiency. Part two of this work demonstrates a device concept for highly efficient organic light-emitting devices whose emission color can be easily adjusted from, e.g., deep-blue through cold-white and warm-white to saturated yellow. The presented approach exploits the different polarities of the positive and negative half-cycles of an alternating current driving signal to independently address a fluorescent blue emission unit and a phosphorescent yellow emission unit vertically stacked on top of each other. The electrode design is optimized for simple fabrication and driving and allows for two-terminal operation by a single source. The presented approach for color-tunable OLEDs is versatile in terms of emitter combinations and meets application requirements by providing a high device efficiency of 36.2 lm/W, a color rendering index of 82 at application relevant brightness levels of 1000 cd/m², and warm-white emission color coordinates. The final part demonstrates an approach for full-color OLED pixels that are fabricated by vertical stacking of a red-, green-, and blue-emitting unit. Each unit can be addressed separately which allows to efficiently generate every color that is a superposition of spectra of the individual emission units. The device is built in a top-emission geometrywhich is highly desirable for display fabrication as the pixel can be directly deposited onto the back-plane electronics. Furthermore, the presented device design requires only three independently addressable electrodes which simplifies fabrication and electrical driving. The electrical performance of each individual unit is on par with standard pin single emission unit OLEDs, showing very low leakage currents and achieving high brightness levels at moderate voltages of around 3–4 V.

No description available.