Efeitos de acoplamentos biquadráticos e campos aleatórios em vidros de spins

In this work we have studied the effects of random biquadratic and random fields in spin-glass models using the replica method. The effect of a random biquadratic coupling was studied in two spin-1 spin-glass models: in one case the interactions occur between pairs of spins, whereas in the second one the interactions occur between p spins and the limit p > oo is considered. Both couplings (spin glass and biquadratic) have zero-mean Gaussian probability distributions. In the first model, the replica-symmetric assumption reveals that the system presents two pha¬ses, namely, paramagnetic and spin-glass, separated by a continuous transition line. The stability analysis of the replica-symmetric solution yields, besides the usual instability associated with the spin-glass ordering, a new phase due to the random biquadratic cou¬plings between the spins. For the case p oo, the replica-symmetric assumption yields again only two phases, namely, paramagnetic and quadrupolar. In both these phases the spin-glass parameter is zero. Besides, it is shown that they are stable under the Almeida-Thouless stability analysis. One of them presents negative entropy at low temperatures. We developed one step of replica simmetry breaking and noticed that a new phase, the biquadratic glass phase, emerge. In this way we have obtained the correct phase diagram, with.three first-order transition lines. These lines merges in a common triple point. The effects of random fields were studied in the Sherrington-Kirkpatrick model consi¬dered in the presence of an external random magnetic field following a trimodal distribu¬tion {P{hi) = p+S(hi - h0) +Po${hi) +pS(hi + h0))- It is shown that the border of the ferromagnetic phase may present, for conveniently chosen values of p0 and hQ, first-order phase transitions, as well as tricritical points at finite temperatures. It is verified that the first-order phase transitions are directly related to the dilution in the fields: the extensions of these transitions are reduced for increasing values of po- In fact, the threshold value pg, above which all phase transitions are continuous, is calculated analytically. The stability analysis of the replica-symmetric solution is performed and the regions of validity of such a solution are identified

Efeitos interfaciais em heteroestruturas quânticas nô-abruptas: GaAs/ALxGa1-xAs

Um minuncioso estudo das propriedades de confinamento em heterostructuras bidimensionais(poços quânticos) GaAs/AlxGa1_xAs, com interfaces graduais é realizado. Um modelo teórico que represente bem a variação da fração molar do alumínio nas interfaces, resultante do aparecimento de micro-rugosidades e ilhas durante os processos de crescimento e recozimento pós-crescimento da amostra, é elaborado. Vários perfis desta fração molar de alumínio nas interfaces são considerados. Soluções analíticas da equação de Schrodinger, na aproximação da massa efetiva constatne nas interfaces, resultando em equações transcendentais, que possibilitam a obtenção dos níveis de energia dos portadores, decorrentes do seu confinamento quântico, são apresentadas. Energias de ligação e de confinamento de excitons 2D, utilizando-se um método analítico e numerérico e a aproximação do potencial efetivo, são também calculadas. Resultados numéricos para os níveis de energia dos portadores e para as energias de ligação e de confinamento dos excitons 2D, em poços quânticos GaAs/Al0.35Ga0.65As não-abruptos, sem e com a presença de campo elétrico aplicado para vários perfis interfaciais da fração de molar, são mostrados. Para a obtenção desses resultados, faz-se uso do método dos degraus múltiplos e da técnica da matriz de transferência, e adota-se, como operador de energia cinética, o de Ben-Daniel e Duque para uma massa efetiva dependente da posição. Conclui-se que um modelo que leva em conta a existência de interfaces não-abruptas e seus diversos perfis é indispensável para uma melhor descrição das propriedades opto-eletrônicas de poços quânticos GaAs/AlxGa1-xAs, enquanto que a aproximação das interfaces abruptas apresenta-se bastante limitada

Propagação de danos: importância da atualização dinâmica, efeitos da diluição e propriedades termodinâmicas

Neste trabalho investigamos aspectos da propagação de danos em sistemas cooperativos, descritos por modelos de variáveis discretas (spins), mutuamente interagentes, distribuídas nos sítios de uma rede regular. Os seguintes casos foram examinados: (i) A influência do tipo de atualização (paralela ou sequencial) das configurações microscópicas, durante o processo de simulação computacional de Monte Carlo, no modelo de Ising em uma rede triangular. Observamos que a atualização sequencial produz uma transição de fase dinâmica (Caótica- Congelada) a uma temperatura TD ≈TC (Temperatura de Curie), para acoplamentos ferromagnéticos (TC=3.6409J/Kb) e antiferromagnéticos (TC=0). A atualização paralela, que neste caso é incapaz de diferenciar os dois tipos de acoplamentos, leva a uma transição em TD ≠TC; (ii) Um estudo do modelo de Ising na rede quadrada, com diluição temperada de sítios, mostrou que a técnica de propagação de danos é um eficiente método para o cálculo da fronteira crítica e da dimensão fractal do aglomerado percolante, já que os resultados obtidos (apesar de um esforço computacional relativamente modesto), são comparáveis àqueles resultantes da aplicação de outros métodos analíticos e/ou computacionais de alto empenho; (iii) Finalmente, apresentamos resultados analíticos que mostram como certas combinações especiais de danos podem ser utilizadas para o cálculo de grandezas termodinâmicas (parâmetros de ordem, funções de correlação e susceptibilidades) do modelo Nα x Nβ, o qual contém como casos particulares alguns dos modelos mais estudados em Mecânica Estatística (Ising, Potts, Ashkin Teller e Cúbico)

Efeitos de interface em bicamadas magnéticas

We study magnetic interface roughness in F/AF bilayers. Two kinds of roughness were considered. The first one consists of isolated defects that divide the substrate in two regions, each one with an AF sub-lattice. The interface exchange coupling is considered uniform and presents a sudden change in the defects line, favoring Neel wall nucleation. Our results show the interface field dependence of the threshold thickness for the reorientation of the magnetization in the ferromagnetic film. Angular profiles show the relaxation of the magnetization, from Neel wall, at the interface, to reoriented state, at the surface. External magnetic field, perpendicular to the easy axis of the substrate, favors the reoriented state. Depending, of the external magnetic field intensity, parallel to the easy axis of the AF, the magnetization profile at surface can be parallel or perpendicular to the field direction. The second one treats of distributed deffects, periodically. The shape hysteresis curves, exchange bias and coercivity were characterized by interface field intensity and roughness pattern. Our results show that dipolar effects decrease the exchange bias and coercivity

Efeitos da interação dipolar na nucleação de vórtices em nano-cilindros magnéticos

The effect of confinement on the magnetic structure of vortices of dipolar coupled ferromagnetic nanoelements is an issue of current interest, not only for academic reasons, but also for the potential impact in a number of promising applications. Most applications, such as nano-oscillators for wireless data transmission, benefit from the possibility of tailoring the vortex core magnetic pattern. We report a theoretical study of vortex nucleation in pairs of coaxial iron and Permalloy cylinders, with diameters ranging from 21nm to 150nm, and 12nm and 21nm thicknesses, separated by a non-magnetic layer. 12nm thick iron and Permalloy isolated (single) cylinders do not hold a vortex, and 21nm isolated cylinders hold a vortex. Our results indicate that one may tailor the magnetic structure of the vortices, and the relative chirality, by selecting the thickness of the non-magnetic spacer and the values of the cylinders diameters and thicknesses. Also, the dipolar interaction may induce vortex formation in pairs of 12nm thick nanocylinders and inhibit the formation of vortices in pairs of 21nm thick nanocylinders. These new phases are formed according to the value of the distance between the cylinderes. Furthermore, we show that the preparation route may control relative chirality and polarity of the vortex pair. For instance: by saturating a pair of Fe 81nm diameter, 21nm thickness cylinders, along the crystalline anisotropy direction, a pair of 36nm core diameter vortices, with same chirality and polarity is prepared. By saturating along the perpendicular direction, one prepares a 30nm diameter core vortex pair, with opposite chirality and opposite polarity. We also present a theoretical discussion of the impact of vortices on the thermal hysteresis of a pair of interface biased elliptical iron nanoelements, separated by an ultrathin nonmagnetic insulating layer. We have found that iron nanoelements exchange coupled to a noncompensated NiO substrate, display thermal hysteresis at room temperature, well below the iron Curie temperature. The thermal hysteresis consists in different sequences of magnetic states in the heating and cooling branches of a thermal loop, and originates in the thermal reduction of the interface field, and on the rearrangements of the magnetic structure at high temperatures, 5 produce by the strong dipolar coupling. The width of the thermal hysteresis varies from 500 K to 100 K for lateral dimensions of 125 nm x 65 nm and 145 nm x 65 nm. We focus on the thermal effects on two particular states: the antiparallel state, which has, at low temperatures, the interface biased nanoelement with the magnetization aligned with the interface field and the second nanoelement aligned opposite to the interface field; and in the parallel state, which has both nanoelements with the magnetization aligned with the interface field at low temperatures. We show that the dipolar interaction leads to enhanced thermal stability of the antiparallel state, and reduces the thermal stability of the parallel state. These states are the key phases in the application of pairs of ferromagnetic nanoelements, separated by a thin insulating layer, for tunneling magnetic memory cells. We have found that for a pair of 125nm x 65nm nanoelements, separated by 1.1nm, and low temperature interface field strength of 5.88kOe, the low temperature state (T = 100K) consists of a pair of nearly parallel buckle-states. This low temperature phase is kept with minor changes up to T= 249 K when the magnetization is reduced to 50% of the low temperature value due to nucleation of a vortex centered around the middle of the free surface nanoelement. By further increasing the temperature, there is another small change in the magnetization due to vortex motion. Apart from minor changes in the vortex position, the high temperature vortex state remains stable, in the cooling branch, down to low temperatures. We note that wide loop thermal hysteresis may pose limits on the design of tunneling magnetic memory cells

Efeitos das inomogeneidades da matéria em Cosmologias Aceleradas

The recent observational advances of Astronomy and a more consistent theoretical framework turned Cosmology in one of the most exciting frontiers of contemporary science. In this thesis, homogeneous and inhomogeneous Universe models containing dark matter and different kinds of dark energy are confronted with recent observational data. Initially, we analyze constraints from the existence of old high redshift objects, Supernovas type Ia and the gas mass fraction of galaxy clusters for 2 distinct classes of homogeneous and isotropic models: decaying vacuum and X(z)CDM cosmologies. By considering the quasar APM 08279+5255 at z = 3.91 with age between 2-3 Gyr, we obtain 0,2 < OM < 0,4 while for the j3 parameter which quantifies the contribution of A( t) is restricted to the intervalO, 07 < j3 < 0,32 thereby implying that the minimal age of the Universe amounts to 13.4 Gyr. A lower limit to the quasar formation redshift (zJ > 5,11) was also obtained. Our analyzes including flat, closed and hyperbolic models show that there is no an age crisis for this kind of decaying A( t) scenario. Tests from SN e Ia and gas mass fraction data were realized for flat X(z)CDM models. For an equation of state, úJ(z) = úJo + úJIZ, the best fit is úJo = -1,25, úJl = 1,3 and OM = 0,26, whereas for models with úJ(z) = úJo+úJlz/(l+z), we obtainúJo = -1,4, úJl = 2,57 and OM = 0,26. In another line of development, we have discussed the influence of the observed inhomogeneities by considering the Zeldovich-Kantowski-DyerRoeder (ZKDR) angular diameter distance. By applying the statistical X2 method to a sample of angular diameter for compact radio sources, the best fit to the cosmological parameters for XCDM models are OM = O, 26,úJ = -1,03 and a = 0,9, where úJ and a are the equation of state and the smoothness parameters, respectively. Such results are compatible with a phantom energy component (úJ < -1). The possible bidimensional spaces associated to the plane (a , OM) were restricted by using data from SNe Ia and gas mass fraction of galaxy clusters. For Supernovas the parameters are restricted to the interval 0,32 < OM < 0,5(20") and 0,32 < a < 1,0(20"), while to the gas mass fraction we find 0,18 < OM < 0,32(20") with alI alIowed values of a. For a joint analysis involving Supernovas and gas mass fraction data we obtained 0,18 < OM < 0,38(20"). In general grounds, the present study suggests that the influence of the cosmological inhomogeneities in the matter distribution need to be considered with more detail in the analyses of the observational tests. Further, the analytical treatment based on the ZKDR distance may give non-negligible corrections to the so-calIed background tests of FRW type cosmologies

Efeitos não-gaussianos em astrofísica e cosmologia

The recent astronomical observations indicate that the universe has null spatial curvature, is accelerating and its matter-energy content is composed by circa 30% of matter (baryons + dark matter) and 70% of dark energy, a relativistic component with negative pressure. However, in order to built more realistic models it is necessary to consider the evolution of small density perturbations for explaining the richness of observed structures in the scale of galaxies and clusters of galaxies. The structure formation process was pioneering described by Press and Schechter (PS) in 1974, by means of the galaxy cluster mass function. The PS formalism establishes a Gaussian distribution for the primordial density perturbation field. Besides a serious normalization problem, such an approach does not explain the recent cluster X-ray data, and it is also in disagreement with the most up-to-date computational simulations. In this thesis, we discuss several applications of the nonextensive q-statistics (non-Gaussian), proposed in 1988 by C. Tsallis, with special emphasis in the cosmological process of the large structure formation. Initially, we investigate the statistics of the primordial fluctuation field of the density contrast, since the most recent data from the Wilkinson Microwave Anisotropy Probe (WMAP) indicates a deviation from gaussianity. We assume that such deviations may be described by the nonextensive statistics, because it reduces to the Gaussian distribution in the limit of the free parameter q = 1, thereby allowing a direct comparison with the standard theory. We study its application for a galaxy cluster catalog based on the ROSAT All-Sky Survey (hereafter HIFLUGCS). We conclude that the standard Gaussian model applied to HIFLUGCS does not agree with the most recent data independently obtained by WMAP. Using the nonextensive statistics, we obtain values much more aligned with WMAP results. We also demonstrate that the Burr distribution corrects the normalization problem. The cluster mass function formalism was also investigated in the presence of the dark energy. In this case, constraints over several cosmic parameters was also obtained. The nonextensive statistics was implemented yet in 2 distinct problems: (i) the plasma probe and (ii) in the Bremsstrahlung radiation description (the primary radiation from X-ray clusters); a problem of considerable interest in astrophysics. In another line of development, by using supernova data and the gas mass fraction from galaxy clusters, we discuss a redshift variation of the equation of state parameter, by considering two distinct expansions. An interesting aspect of this work is that the results do not need a prior in the mass parameter, as usually occurs in analyzes involving only supernovae data.Finally, we obtain a new estimate of the Hubble parameter, through a joint analysis involving the Sunyaev-Zeldovich effect (SZE), the X-ray data from galaxy clusters and the baryon acoustic oscillations. We show that the degeneracy of the observational data with respect to the mass parameter is broken when the signature of the baryon acoustic oscillations as given by the Sloan Digital Sky Survey (SDSS) catalog is considered. Our analysis, based on the SZE/X-ray data for a sample of 25 galaxy clusters with triaxial morphology, yields a Hubble parameter in good agreement with the independent studies, provided by the Hubble Space Telescope project and the recent estimates of the WMAP

Efeitos da inclinação da esteira na marcha de indivíduos hemiparéticos crônicos

Objective: To examine the effects of treadmill inclinations on the walking of hemiparetic chronic subjects. Design: Observational descriptive study. Location: Laboratory of human movement analysis. Participants: Eighteen subjects, 10 men and 8 women were evaluated, with a mean age of 55.3 ± 9.3 years and the time since the injury of about 36 ± 22.8 months. Intervention: Not applicable. Main Outcome Measures: All subjects were evaluated for functional independence (Functional Independence Measure - FIM) and balance (Berg Balance Scale). Angular variations of the hips, knees and ankles in the sagittal plane were observed, as well as the speed of the movement (m/s), cadence (steps/min), stride length (m), cycle time (s), step time on the paretic leg and on the non-paretic leg (s), support phase time and balance phase time on the paretic leg (s) and the ratio of symmetry inter-limb as subjects walked on a treadmill at three conditions of inclination (0%, 5% and 10% ). Results: There were angular increases in the initial contact of the hip, knee and ankle, amplitude increase in the hip between 0% and 10% (37.83 ± 5.23 versus 41.12 ± 5.63, p < 0,001) and 5% and 10% (38.80 ± 5.96 versus 41.12 ± 5.63, p = 0,002), amplitude increases in the knee between 0% and 10% (47.51 ± 15.07 versus 50, 30 ± 12.82, p = 0,040), extension decreases in the hip, dorsiflexion increases in the balance phase and in the time of support phase from 0% to 5% (0.83 ± 0.21 versus 0.87 ± 0, 20, p = 0,011) and 0% and 10% (0.83 ± 0.21 versus 0.88 ± 0.23, p = 0,021). Conclusion: The treadmill inclination promoted angle changes as such as the increase of the angle of the hip, knee and ankle during the initial contact and the balance phase and the increase of the range of motion of the hip and knee; furthermore, it also promoted the increase of the support time of the paretic lower limb

Efeitos imediatos da eletroestimulação nervosa transcutânea e crioterapia na espasticidade e na atividade eletromiográfica de sujeitos hemiparéticos

Cerebrovascular accident (CVA) is a term used to characterize an ischemic or hemorrhagic vascular injury, which has got as main clinic manifestations, the motor and reflex function disturbance. In the first stage there is flaccidity and loss of voluntary movements that afterwards is substituted by mass patterns and spasticity. The spasticity brings with itself functional deficits and can generate negative impacts in various motor patterns. The aim of this research was to investigate the hyperreflexia and identify the immediate effects of transcutaneous nervous stimulation (TENS) and cryotherapy in the spasticity and electromyographic activity of hemiparetic subjects. The study is characterized as an almost experimental type, in which were selected, to compose the sample, 16 patients of both sex with CVA sequel. These individuals were evaluated by collecting the amplitude peak to peak and H reflex latency, Motor response (M response) in solear muscle and the electromyography (EMG) of the injured and healthy legs anterior tibial muscles. In the injured limb the evaluations occurred in different days for cryotherapy, TENS and control, in two moments, before and after the interventions. The healthy limb was evaluated one single time to serve as baseline, for comparison with the injured limb. It was used an statistic analysis, the t paired student test to identify the H reflex differences, latency and EMG of the injured and healthy limbs and to compare the results before and after the recourses application. The ANOVA for related samples was used to identify the differences among the recourses used. It was attributed for the statistic tests a significance level of 5%. The amplitude peak to peak of normalized maximum H reflex through the maximum motor response (Hmax/Mmax), showed itself significantly increased in the injured limb (p=0.0245). The H reflex latency was presented reduced in the injured limb (p=0, 0375). The electromyographic activity was showed decreased in the injured limb (p< 0.0001). After the TENS there was a Hmáx/Mmáx ratio decrease (0.60±0.16 versus 0.49.±0.18; P = 0.0006). Nonetheless, Just after the cryotherapy application there was an increase of Hmáx/Mmáx ratio (0.58 ± 0,15 to 0.77 ± 0.13, P=0,0007) and increase of signal latency (30.41 ± 1.87 versus 33.24 ± 2.19; P=0.0001). The electromyographic activity wasn t altered significantly by any resource. It was met statistic significant differences when the Hmáx/Mmáx P<0.0001) ratio and H reflex latency (P<0.0001) were compared between the post TENS, cryotherapy and control. One can conclude that the TENS can be used to spasticity immediate reduction, and that the cryotherapy can increase the hyperreflexia state in spastic patients. Nonetheless, the spasticity decrease or increase didn t provoke lectromyographic activity change in the muscle that is opponent to the spastic one

Efeitos da inclinação da esteira na marcha de crianças com síndrome de down

Background: Down syndrome (DS) is a genetic alteration characterized by being a nonprogressive congenital encephalopathy. Children with DS have hypotonia and developmental delays that interfere in the movement`s acquisition for these children. Objective: Analyze the effects of treadmill inclination on angle and spatiotemporal gait characteristics of these individuals. Methodology: We studied 23 subjects of both sexes, with ages ranged between 05 and 11 years, they presented ability to walk on level 5 classified according to the Functional Ambulation Category (FAC). Initially held a subjective evaluation of balance through a questionnaire (Berg Balance Scale-BBS) then the kinematic gait analysis was realized on a treadmill first, without inclination and then, with inclination of 10%, using the motion system analysis Qualisys System. Data analysis was done using BioStat 5.0 attributing significance level of 5%. Normality of data was verified using D'Agostino test and later was applied paired t-test to compare data in two experimental conditions. Results: There was a statistically significant difference in the spatiotemporal variables: reduction in the cadence (from 108.92 ± 39.07 to 99.11 ± 27.51, p <0.04), increase in cycle time (from 1.24 ± 0.27 to 1.36 ± 0.34, p = 0.03 ) and increase in time to take stock (from 0.77 ± 0.15 to 0.82 ± 0.18, p <0.001). Angular variables that showed statistically significant increasing were: the hip in the initial contact (12.23 ± 4.63 to 18.49 ± 5.17, p <0.0001) and max. flexion in balance (12.96±4:32 to 19.50 ± 4.51, p <0.0001 ), knee in the initial contact (15.59 to ± 6.71 to 21.63 ± 6.48, p <0.0001), the ankle in the initial contact (-2.79 ± 9.8 to 2.25 ± 8.79, p <0.0001), max dorsiflexion in stance (4.41 ± 10.07 to 7.13 ± 11.58, p <0.0009), maximum plantar flexion in the pre-assessment of the ankle joint (increase of -6.33 ± 8.77 to -2.69 ± 8.62, p <0.0004).Conclusions: The inclination acts in a positive way for angular and spatiotemporal features gait of children with Down syndrome, demonstrating possible benefit of using this surface in the gait rehabilitation of children with Down Syndrome

Efeitos do treinamento de dupla tarefa no controle do equilíbrio dinâmico e estático de idosas pré-frágeis: um estudo piloto

The increasing world population of older individuals has become a subject of growing research for prevention and reversibility of the frailty because it is a major risk factor for the occurrence of falls, especially when it involves everyday situations of dual task. Some rehabilitation programs have already used the methods of dual-task with general exercises for improving gait and postural control, but has been reported that these interventions have little specificity with limited success to improve certain aspects of static and dynamic position during the performance of functional tasks. This study aimed to verify the measures of postural control in a group of elderly women with fragility phenotype after physical therapy intervention program based on dual-task treadmill training. We selected six pre-frail elderly subjects, with a minimum age of 65, female, living in the community and randomly assigned to two groups. The survey was conducted twice a week for 45 minutes, for four weeks. The simple task intervention consisted only in training on a treadmill and the dual task consisted of in treadmill training associated with visual stimuli. The assessments were made with the use of the Berg Balance Scale (BBS) and the Balance Master® computerized posturography, static and dynamically. The effects of retention were observed after one month, using the same instruments earlier used. The results showed a tendency toward improvement or maintenance of the balance after training on a treadmill, especially with respect to static equilibrium. Both groups showed the most notable changes in the variables related to gait, as the length and speed. The BBS scores and the baropodometric variables showed that the experimental group could keep all values similar or better even one month after completion of training unlike the control group. We concluded that the dual-task performance had no additional value in relation to the improvement of balance in general, but we observed that the effectiveness of visual stimulation occurred in the maintenance of short term balancevariables

Efeitos do alongamento e do aquecimento no desempenho isocinético e na atividade eletromiográfica do músculo bíceps femoral ensaio clínico randomizado

To evaluate the effects of warm-up and stretching, singly or combined, on isokinetic performance and electromyographic activity of the biceps femoris. Materials and methods: Sixty-four volunteers of both sexes, with mean age of 23,1 ± 3,5 years and mean body mass index of 23,5 ± 2,5 Kg/m2 were randomly assigned into 4 groups: control, warm-up (stationary bicycle for 10 minutes), stretching (4 sets of 30 seconds of hamstring muscles static stretching) and warm-up + stretching. All the volunteers were submitted to evaluation pre and post-intervention of the muscle latency time and biceps femoris RMS and the passive torque, peak torque and power of the hamstring muscles. Results: The warm-up + stretching group had reduction of muscle latency time. There was a reduction of RMS during passive torque evaluation in stretching group. The RMS during isometric evaluation was reduced in all experimental groups. The RMS during eccentric evaluation showed reduction in control and warm-up + stretching groups. The passive torque and the eccentric peak torque had no significant differences pre to post-intervention in any group. There was reduction in isometric peak torque in all groups. Conclusion: The warm-up and stretching, when applied in combination can reduce the muscle latency time; stretching protocol promoted neural changes; the protocols used did not alter the muscle viscoelastic properties

Efeitos da eletroestimulação sobre os parâmetros eletromiográficos e dinamométricos do músculo quadríceps femoral

To analyze the effects of electrical stimulation at two frequencies on the EMG parameters (EMG) and dynamometer, in muscles with different typing. MATERIALS AND METHODS: This is a controlled clinical trial, randomized and double blind. Sixty healthy volunteers (23.6 ± 4.2anos; 54.2 ± 7.7kg, 1.62 ± 0.009 cm) of both sexes were divided randomly into three groups: control group (CG), experimental group 1 (SG1) with application of the current Russian 30 HZ and experimental group 2 (EG2) at 70 Hz The volunteers performed an initial assessment (AV1) on the isokinetic dynamometer with three repetitions maximum voluntary isometric (MVC) for knee extension concomitant uptake of EMG for the VM muscle, VL and RF. Later, after application of NMES, they underwent an experimental protocol of isometric fatigue using 70% of MVIC, ending with the completion of a final assessment (AV2) in the same manner as the AV1. RESULTS: By analyzing the profile of the 60 subjects in three broad, VM showed a higher value of RMS behavior when the VL and RF (p = 0.03 and p = 0.02). With respect to Fmed the RF muscle (p = 0.001) showed a higher value for the VM. The VM muscle showed significant increases of Fmed (p = 0.05) after electrical stimulation at 70 Hz when compared the AV1 AV2 and RF showed significant decreases (p = 0.009) after stimulation at 30 Hz during the fatigue showed an increase RMS in the VM and VL, with a reduction in RF. For the variable Fmed was observed in three broad decline during fatigue. CONCLUSION: Our findings provide evidence that the muscles VM, VL and RF fiber typing are different besides indicating that the frequency of NMES tend to relate to the muscle stimulated. Finally suggests the surface EMG as a noninvasive method for characterizing muscle

Efeitos da eletroestimulação percutânea na incontinência urinária e qualidade de vida pós-prostatectomia: registro de seis casos

Introduction: Radical prostatectomy surgery is the best treatment currently adopted by detecting prostate cancer. The urinary incontinence is one more common and difficult to treat postoperative complications, which causes a negative impact on quality of life of the individual prostatectomy . The surface electrical nerve stimulation involves the transmission of electrical impulses from an external stimulator for peripheral nerve through surface electrodes attached to skin. It is an easy and efficient technique, widely used for pain relief, rehabilitation and muscle strengthening. Objective: To analyze the effect of T10-L2 percutaneous electrical stimulation, in individuals with urinary incontinence who underwent radical prostatectomy by the laparoscopic technique. Methods: Six patients had previously undergone radical prostatectomy were submitted to 20 sections of surface electrical stimulation with frequency of 4 Hz, pulse width of 1ms during 20 minutes. All subjects fillid a quality of life - International Consultation on Incontinence Questionnaire- Short FormI - ICIQ-SF questionnaire evaluating. Results: Results showed reduction in the use of the number of pads, number of leaks before and after treatment, and reduced voiding frequency and consequent improvement in quality of life. No side effects were reported. Conclusion: Percutanous electrical stimulation in T10-L2 may be an effective technique to treat urinary incontinence (UI) after radical prostatectomy video laparoscopy

Efeitos da perda de peso induzida pela cirurgia bariátrica sobre a função respiratória

Background: Obesity leads to alteration of lung volumes and capacities due to accumulation of fat in the chest wall and abdomen. Few studies have shown that weight loss induced by surgery improves lung function. Our objective was to evaluate the anthropometric development, pulmonary function, respiratory muscle, strength and endurance after weight loss induced by bariatric surgery. Methods: We evaluated in pre and post operative period variables of weight, BMI, NC, WHR and spirometric and respiratory pressure. Results: 39 subjects were evaluated, with age mean 35.9 ± 10.9 years, predominantly by women (76.3%). The weight mean decreased from 124.8 ± 17.5 kg to 88.8 ± 14.28 kg in post operative. The mean BMI ranged from 47,9 ± 5,6 Kg/m² to 34,3 ± 4,75 Kg/m². There was a significant increase in FVC from 3,63 ± 0,94 to 4,01±1,03, FEV1 from 3,03 ± 0,72 to 3,39 ± 0,85, FEF 25-75% from 3,41 ± 0,72 to 3,82 ± 0,94, PEF from 6,56 ± 1,47 to 7,81 ± 1,69, ERV from 0,35 ± 0,39 to 0,66 ± 0,38, MVV ranged from 103,43 ± 22,21 to 137,27 ± 29,84, all of them to p<0,01. The MIP and MEP showed no significant difference in pre and post operative. It was noted that for every centimeter reduced in neck circumference, an increase of 0.06 in FVC and 5.98 in MVV is observed. This is also observed in weight and BMI. Conclusion: We conclude that weight loss induced by bariatric surgery in obese provides a significant improvement in lung function and reduction of fat around the neck is more important in the generation of lung volume than the reduction of BMI