Burrow morphology of Uca uruguayensis and Uca leptodactylus (Decapoda: Ocypodidae) from a subtropical mangrove forest in the western Atlantic

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of triceps surae and quadriceps muscle fatigue on the mechanics of landing in stepping down in ongoing gait

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Scattering Amplitudes Interpolating Between Instant Form and Front Form of Relativistic Dynamics

Among the three forms of relativistic Hamiltonian dynamics proposed by Dirac in 1949, the front form has the largest number of kinematic generators. This distinction provides useful consequences in the analysis of physical observables in hadron physics. Using the method of interpolation between the instant form and the front form, we introduce the interpolating scattering amplitude that links the corresponding time-ordered amplitudes between the two forms of dynamics and provide the physical meaning of the kinematic transformations as they allow the invariance of each individual time-ordered amplitude for an arbitrary interpolation angle. We discuss the rationale for using front form dynamics, nowadays known as light-front dynamics (LFD), and present a few explicit examples of hadron phenomenology that LFD uniquely can offer from first-principles quantum chromodynamics. In particular, model-independent constraints are provided for the analyses of deuteron form factors and the N Delta transition form factors at large momentum transfer squared Q(2). The swap of helicity amplitudes between the collinear and non-collinear kinematics is also discussed in deeply virtual Compton scattering.

Do people with recurrent back pain constrain spinal motion during seated horizontal and downward reaching?

Background: Although the effect of symptomatic back pain on functional movement has been investigated, changes to spinal movement patterns in essentially pain-free people with a history of recurrent back pain are largely unreported. Reaching activities, important for everyday and occupational function, often present problems to such people, but have not been considered in this population. The purpose of this study was to compare the amplitude and timing of spinal and hip motions during two, seated reaching activities in people with and without a history of recurrent low back pain (RLBP).Methods: Spinal and hip motions during reaching downward and across the body, in both directions, were tracked using electromagnetic sensors. Analyses were conducted to explore the amplitudes, velocities and timings of 3D segmental movements and to compare controls with subjects with recurrent, but asymptomatic lumbar or lumbosacral pain.Findings: We detected significant differences in the amplitude and timing of movement in the lower thoracic region, with the RLBP group restricting movement and demonstrating compensatory increased motion at the hip. The lumbar region displayed no significant between-group differences. The order in which the spinal segments achieved peak velocity in cross-reaching was reversed in RLBP compared to controls, with lumbar motion leading in controls and lagging in RLBP.Interpretation: Subjects with a history of RLBP show a number of altered kinematic features during reaching activities which are not related to the presence or intensity of pain, but which suggest adaptive changes to movement control. (C) 2013 Elsevier Ltd. All rights reserved.

The influence of the use of stabilizer bracelet in a child with choreoathetoid cerebral palsy

Introduction: The use of stabilizer bracelet is a frequent treatment for movement disorders to strengthen muscles and adjust coordination. Still questions remain regarding the benefi t of using loads to decrease involuntary movements and the best load and placement. Objective: To measure the infl uence of the stabilizer bracelet on the kinematics and spatiotemporal parameters in planar movements performed by the upper limb. Method: One child, who has the spastic diplegy type of cerebral palsy with choreoathetoid component, and a control child without cerebral palsy, both female and 7 years old, were subjected to analysis of movements in relation to displacement, velocity, linear acceleration, and the calculation of mean square error (MSE) with and without use of stabilizer bracelet with loads of 25, 50, and 75% of the supported maximum load. Results: After comparing data between subjects, a difference was found between patient and control in all situations and variables. An inter-individual comparison using 25% of the maximum load showed the smallest difference with the NDE. Discussion and Conclusion: This therapeutic option is low cost, easy to apply, and does not signifi cantly interfere in the aesthetic of the individual. Therefore, physiotherapists may prescribe this for activities that require greater control of the upper limb because for the case studied the upper limb movement was more effi cient with the use of the stabilizer bracelet.

Analysis of the positioning of the head, trunk, and upper limbs during gait in children with visual impairment

Background: This study analyzed the positioning of the head, trunk, and upper extremities during gait in children with visual impairment. Methods: A total of 11 children participated in this study: 6 with blindness and 5 with low vision. The kinematics of the positioning of the head, trunk, shoulders, and elbows in each participant was analyzed during the four phases of the gait cycle: foot strike, support, toe-off, and swing. Results: There were significant differences between children with blindness and low vision in the positioning of the trunk in the sagittal plane during the foot strike, support, and swing phases. Conclusions: The analysis identified postural alterations of the head, trunk, shoulder, and elbow during the children’s gait, highlighting the relevance of appropriate stimulation at an early age in orientation and mobility programs, as well as the essential presence of professionals who work with movement.

Modeling of multiple cracks in reinforced concrete members using solid finite elements with high aspect ratio

This paper presents a new technique to model interfaces by means of degenerated solid finite elements, i.e., elements with a very high aspect ratio, with the smallest dimension corresponding to the thickness of the interfaces. It is shown that, as the aspect ratio increases, the element strains also increase, approaching the kinematics of the strong discontinuity. A tensile damage constitutive relation between strains and stresses is proposed to describe the nonlinear behavior of the interfaces associated with crack opening. To represent crack propagation, couples of triangular interface elements are introduced in between all regular (bulk) elements of the original mesh. With this technique the analyses can be performed integrally in the context of the continuum mechanics and complex crack patterns involving multiple cracks can be simulated without the need of tracking algorithms. Numerical tests are performed to show the applicability of the proposed technique, studding also aspects related to mesh objectivity.

Aspects of Manual Wheelchair Configuration Affecting Mobility: A Review

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação cinemática em cães: revisão

Kinematics is the geometry of motion, including displacement, speed and acceleration, without considering the forces acting over a body. The use of kinematics is still very limited when we are evaluating dogs because of the high cost of the equipment, but the information obtained is objective and precise, what is essential for a trustful evaluation. Taking all this into consideration, this evaluation will describe some researches that used the method, specifying the final objective for each of them. By this analysis, we can conclude that kinematic studies, according to the characteristics of dog races, are necessary to explain how body structure and conformance may affect the function. Besides that, according to normative patterns of a population it is possible to study some diseases and treatment evolution

Análise biomecânica do chute frontal de karatê: implicações em lesões nos membros inferiores

Pós-graduação em Engenharia Mecânica - FEG

Ergonomia de tablets em uso ocupacional: atividade visual e biomecânica postural sob a influência de ofuscamentos reflexivos causados pela iluminação

Pós-graduação em Design - FAAC

Elementos estruturais relacionados com a mineralização do eoceno - oligoceno entre Mollebamba e Santo Domingo região de Apurimac, sul do Peru

Pós-graduação em Geociências e Meio Ambiente - IGCE

Does proprioceptive system stimulation improve sit-to-walk performance in healthy young adults?

[Purpose] Sit-to-walk performance is linked to proper proprioceptive information processing. Therefore, it is believed that an increase of proprioceptive inflow (using muscle vibration) might improve sit-to-walk performance. However, before testing muscle vibration effects on a frail population, assessment of its effects on healthy young people is necessary. Thus, the aim of this study was to investigate the effects of muscle vibration on sit-to-walk performance in healthy young adults. [Subjects and Methods] Fifteen young adults performed the sit-to-walk task under three conditions: without vibration, with vibration applied before movement onset, and with vibration applied during the movement. Vibration was applied bilaterally for 30 s to the tibialis anterior, rectus femoris, and upper trapezius muscles bellies. The vibration parameters were as follows: 120 Hz and 1.2 mm. Kinematics and kinetic data were assessed using a 3D motion capture system and two force plates. The coordinates of reflective markers were used to define the center-of-mass velocities and displacements. In addition, the first step spatiotemporal variables were assessed. [Results] No vibration effect was observed on any dependent variables. [Conclusion] The results show that stimulation of the proprioceptive system with local muscle vibration does not improve sit-towalk performance in healthy young adults.

The dark matter profile of the Milky Way: a non-parametric reconstruction

We present the results of a new, non-parametric method to reconstruct the Galactic dark matter profile directly from observations. Using the latest kinematic data to track the total gravitational potential and the observed distribution of stars and gas to set the baryonic component, we infer the dark matter contribution to the circular velocity across the Galaxy. The radial derivative of this dynamical contribution is then estimated to extract the dark matter profile. The innovative feature of our approach is that it makes no assumption on the functional form or shape of the profile, thus allowing for a clean determination with no theoretical bias. We illustrate the power of the method by constraining the spherical dark matter profile between 2.5 and 25 kpc away from the Galactic center. The results show that the proposed method, free of widely used assumptions, can already be applied to pinpoint the dark matter distribution in the Milky Way with competitive accuracy, and paves the way for future developments.

Reliability and differentiation capability of dynamic and static kinematic measurements of rearfoot eversion in patellofemoral pain

Excessive rearfoot eversion is thought to be a risk factor for patellofemoral pain development, due to the kinesiological relationship with ascendant adaptations. Individuals with patellofemoral pain are often diagnosed through static clinical tests, in scientific studies and clinical practice. However, the adaptations seem to appear in dynamic conditions. Performing static vs. dynamic evaluations of widely used measures would add to the knowledge in this area. Thus, the aim of this study was to determine the reliability and differentiation capability of three rearfoot eversion measures: rearfoot range of motion, static clinical test and static measurement using a three-dimensional system. A total of 29 individuals with patellofemoral pain and 25 control individuals (18-30 years) participated in this study. Each subject underwent three-dimensional motion analysis during stair climbing and static clinical tests. Intraclass correlation coefficient and standard error measurements were performed to verify the reliability of the variables and receiver operating characteristic curves to show the diagnostic accuracy of each variable. In addition, analyses of variance were performed to identify differences between groups. Rearfoot range of motion demonstrated higher diagnostic accuracy (an area under the curve score of 0.72) than static measures and was able to differentiate the groups. Only the static clinical test presented poor and moderate reliability. Other variables presented high to very high values. Rearfoot range of motion was the variable that presented the best results in terms of reliability and differentiation capability. Static variables do not seem to be related to patellofemoral pain and have low accuracy values.