Whole body vibration in operators using agricultural soil preparation equipment / Alteração na vibração de corpo inteiro em operadores pela utilização de equipamentos agrícolas de preparo do solo

ABSTRACT: Agricultural tractors have been reported to exert negative effects on operator health. It is well known that when a farm machine is designed it must consider the human factors, to raise the safety levels and work quality. The aim of the present study was to estimate the degree of vibration transmissibility from the agricultural equipment used for the periodic soil preparation process and determine the exposure of the whole body of the operator to the vibration, incident to the agricultural tractor during the operation. A 4x2 TDA tractor was employed, coupled to the periodic soil preparation equipment. Five sets were used (tractor- disk plough, tractor-moldboard plow, tractor-offset disc harrow, tractor-rotary hoe, and tractor-scarifier) and the tractor without the equipment being coupled, at two tractor speeds of displacement (3.5 km.h-1 and 6.1 km.h-1). An index (IAVEA) was developed to assess whether the amplification or attenuation of the vibrations takes place on each orthogonal axis. The data were processed using the Noise Studio® software 6.95. Statistical evaluation was performed using the ASSISTAT version 7.7 beta program. After normality, the data were submitted to the analysis of variance by the F test; when significance was reported, the means were compared using the Tukey test, at 5% significance. The disk plow was the equipment that showed the greatest intensification of the vibrations in all the parameters estimated. All the sets assessed revealed statistically equal or higher values in terms of the tractor without the attached equipment. The IAVEA% was an index that enabled the quantification of the amplification or attenuation caused by the use of the agricultural equipment.

RESUMO: A utilização de tratores agrícolas tem causado efeitos negativos na saúde do operador. Faz-se necessário que no projeto de uma máquina agrícola sejam levados em consideração fatores humanos, para aumentar a segurança e melhorar a qualidade de trabalho. O objetivo do presente trabalho foi avaliar a transmissibilidade da vibração em equipamentos agrícolas de preparo periódico do solo devido a exposição a vibração de corpo inteiro incidente ao operador de trator agrícola durante a operação. O trator utilizado foi um trator 4x2 TDA acoplado a equipamentos de preparo periódico do solo. Foram utilizados cinco conjuntos (trator-arado de disco, trator-arado de aiveca, trator-grade off-set, trator-enxada rotativa, trator-escarificador) e um trator sem equipamento acoplado, em duas velocidades de deslocamento do trator (3,5 km.h-1 e 6,1 km.h-1). Foi desenvolvido um índice (IAVEA) para avaliar se ocorre amplificação ou atenuação das vibrações em cada eixo ortogonal. Os dados foram processados no software Noise Studio® 6.95. Para avaliação estatística foi utilizado o programa ASSISTAT versão 7.7 beta. Comprovada a normalidade, os dados foram submetidos à análise de variância pelo teste F e, quando significativas, as médias foram comparadas pelo teste de Tukey a 5% de significância. O arado de disco foi o equipamento que apresentou maior intensificação das vibrações em todos os parâmetros avaliados. Todos os conjuntos avaliados apresentam valores estatisticamente iguais ou superiores em relação ao trator sem equipamento acoplado. O IAVEA% se mostrou um índice capaz de quantificar a amplificação ou atenuação proporcionada pelo uso de equipamentos agrícolas.

The effect of mechanical or electrical stimulation on apnea length in mice

Premature birth is a leading cause of infant mortality which is often attributed to irregular breathing and apnea of prematurity. A common treatment for apnea is caffeine to stimulate the brain's respiratory center. However, caffeine's long term effect on infant development is not fully comprehended. We hypothesized that noninvasive localized body stimulation regularizes breathing pattern. We investigated the impact of electrical or mechanical stimulation on breathing in mice. After the mice were ventilated for 28 s to induce apnea, mice were taken off the ventilator while receiving mechanical, electrical, or no stimulation in a randomized order. Both stimuli targeted the diaphragm area through a custom-built belt with vibrating motors or adhesive electrodes. After each apnea cycle, the time to take the first breath (T) was recorded. The electrical stimulation given at 4.5, 8.3, 16.7 V (pulse rate = 3 Hz, pulse width = 120 μs) showed no reduction in T. Electrical stimulation at pulse rates of 10 or 20 Hz (16.7 V, pulse width 260 μs) showed a detrimental effect increasing T by ~ 7% compared to control values (p = 0.005, p = 0.038 respectively). High and medium intensity mechanical stimulations significantly reduced T by 11.74 (p<10⁻¹³) and by 17.08% (p<10⁻⁸), respectively. Further reducing the amplitude of vibrations did not affect T. When the probe was attached to the ankles, only the high intensity vibrations resulted in a decrease in T (p<10⁻¹³). Mechanical vibrations, applied at various intensities and locations, could be used to treat irregular breathing and apnea in infants.

Acute effects of local vibration on the neuromuscular responses / Efeito agudo da vibração local sobre as respostas neuromusculares

The aim of this study was to evaluate acute neuromuscular responses to local vibrations (LV) exposure through monitoring of imposed acceleration. Nineteen healthy males (age = 22.43 ± 2.76 years; body mass = 76.4 ± 12.94 kg; height = 175 ± 6.76 cm) performed an elbow flexion isometric exercise (Scott bench) in two experimental conditions: simple isometric exercise (Control - CON) and vibrating isometric exercise (Local Vibration - LV; Frequency = 20.01 ± 0.13, displacement = 2 - 5 mm). Protocols consisted of 5 maximal voluntary contractions of 12 seconds each and five minutes of recovery between series with (LV) or without vibration (CON). During the exercise, individuals were seated on the bench with the dominant arm resting on the bench support at an approximate angle of 45º between shoulder flexion and the torso. Strength parameters (Rate of Force Development - RFD, p = .030; Peak Force - PF, p = .027; and Fatigue Index - FI, p = .001) significantly increased in LV compared to CON. For EMG parameters, significant changes were only observed for highest value of increase rate of the EMG signal - RER (p = .041), median frequency of EMG signal between peak force and force at the end of the isometric action - MFFbic (p = .045) (agonist) and root mean square of EMG signal of peak force at the end of the isometric action - RMSFtric (p <.001) (antagonist). The addition of local vibrations in resistance training induced an increase in maximal strength, explosive strength and reduced the capacity to sustain strength generation.

O objetivo deste estudo foi avaliar as respostas neuromusculares durante o exercício com a variação dos parâmetros de vibração local. Foram recrutados 19 indivíduos saudáveis do gênero masculino (idade = 22,43 ± 2,76 anos; massa corporal = 76,4 ± 12,94 kg; altura = 175 ± 6,76 cm) que executaram o exercício isométrico em duas situações experimentais: somente o exercício isométrico (Controle); exercício com a adição de vibrações locais (LV; Frequência = 20 ± 3Hz, Deslocamento = 2 - 5 mm). Os parâmetros de força foram significativamente aumentados no tratamento LV comparados ao tratamento controle (RFD, p = ,030; PF, p = ,027; and FI, p = ,001). Para os parâmetros de atividade eletromiográfica, foram observadas alterações significativas para a RER (p = ,041), MFFbic (p = ,045) no músculo bíceps braquial (agonista) e RMSFtric (p <.001) no músculo tríceps braquial (antagonista). A adição de vibrações locais no treinamento contra ­ resistência, induziu um aumento da força máxima, força explosiva e uma redução da capacidade de sustentar a produção de força.

Modal and Vibration Analysis of Functionally Graded Dental Implant.

Dental implant is considered to be the best treatment when dealing with the loss of teeth. It gives beautiful results and can last longer than most of other treatments. Since the Osseo-integration period is a critical period for implant stability, so the used material for dental implant is one of the most factors affecting the stability and Functionally Graded Material (FGM) is one of the opportunities to improve it. The aim of this research is to carry out modal analysis and vibration analysis analytically for functionally graded Dental Implant. In this study several models for dental implant was analyzed by ANSYS15.0 APDL. The functionally graded material was considered in three models. The same materials, Ti-HA, where used in all of them but with different ratio in each. The natural frequency and mode shapes were extracted for all models. The frequency responses of functionally graded Dental Implant after performing a static analysis for each modal have been studied. It was noticed using modal analysis that all of the extracted results for FGM are vary between the two basic materials and it is affected by the concentration of each. It is firmly believed that FGM is the future of dental implant due to the ability of designing a specific material property to be more stable. A comparison of the materials that utilized in FGM when the ration of each 100% was performed as well as an evaluation for the classical dental implant. It is firmly believed that FGM is the future of dental implant due to the ability of designing a specific material property to be more stable.

Caracterización del comportamiento y las señales vibratorias en Euthyrhynchus floridanus (Hemiptera: Pentatomidae) durante el cortejo y la cópula / Characterization of the behavioral and vibrational signals in Euthyrhynchus floridanus (Hemiptera: Pentatomidae) during courtship and copulation

Euthyrhynchus floridanus (Linnaeus) (Hemiptera: Pentatomidae) is a neotropical species belonging to the family Pentatomidae with over 4 000 species described, and is distributed from Florida to Brazil. This study describes the sexual behavior and reported for the first time the production of substrate vibrations by males and females during copulatory behavior and mating. Courtship and copulatory behavior, as well as the diverse signals, were recorded with a phonographic cartridge connected to a video camera. Female vibrations were reproduced in the absence of females and the responses by males were recorded. At least three types of substrate vibrations were distinguished in males and one in females, and these signals were characterized by their low frequency, varying from 127 to 180Hz. The sounds of E. floridianus males were significantly different in frequency, duration and number of pulses, both in courtship and in copulation, for the purring and drumming sounds. The production of sounds in this species is associated principally with mechanical, stimulatory behavior during courtship and copulation. Patterns of behavior and their relation to substrate vibrations suggest that these signals are important for the males in the context of mate location and sexual selection.

Euthyrhynchus floridanus (Linnaeus) (Hemiptera: Pentatomidae) es una especie neotropical perteneciente a la familia Pentatomidae con más de 4 000 especies descritas, y se distribuye desde la Florida hasta Brasil. Este estudio describe el comportamiento sexual y reporta por primera vez la producción de vibraciones de sustrato por machos y hembras durante el comportamiento precopulatorio y la cópula. Se grabó tanto el comportamiento de cortejo y de cópula como las diversas señales producidas utilizando un cartucho fonográfico, conectado a una cámara de video. Posteriormente se reprodujo las vibraciones de las hembras en ausencia de estas y se registró las respuestas de los machos. Se distinguieron al menos tres vibraciones de sustrato distintas para los machos y una para las hembras, y se caracterizaron por ser señales de baja frecuencia que van desde los 127 hasta 180Hz. Las sonidos de los machos en E. floridianus fueron significativamente diferentes en la frecuencia, duración y número de pulsos tanto en el cortejo como en la cópula para los sonidos de ronroneo y tamborileo. La producción de sonidos en esta especie se asoció principalmente con comportamientos estimulatorios- mecánicos durante el cortejo y copula. Patrones de comportamiento y su relación con las vibraciones del sustrato sugiere que estas señales pueden ser importantes para los machos en el contexto de la localización de su compañera y la selección sexual.

Effect of multimodality chest physiotherapy on the rate of recovery and prevention of complications in patients with mechanical ventilation: A prospective study in medical and surgical intensive care units.

Background: Mechanically ventilated patients have an increased risk of complications leading to ventilation weaning more difficult resulting in excessive morbidity and mortality. Chest physiotherapy plays an important role in management of ventilated patients. However, these techniques have been studied on patients as a single entity or with combination of two techniques. The present study was designed to evaluate the effect of multimodality chest physiotherapy on the rate of recovery and prevention of complications in adult ventilated patients. Materials and Methods: Out of 173 patients who were randomly allocated to two groups, 86 patients received MH and suctioning in control group and 87 patients were treated with multimodality chest physiotherapy in the study group twice daily till they were extubated. All patients were followed up for the global outcomes and complications during mechanical ventilation. Results: There were significant improvements in terms of rate of recovery in study group compared to the control group (P = 0.000). Complication rates were higher with 61.6% in the control group as compared to 26.4% in the study group. Duration of hospitalization was longer in the study group (16 ± 9.40 days) as compared to the control group (12.8 ± 6.12 days). Successful weaning from mechanical ventilation was noted in 58 patients in the study group and 24 patients in the control group which was statistically significant. Conclusions: Multi-modality chest physiotherapy protocol has shown to prevent ventilator-associated pneumonia and enhance the clinical outcome in ventilated patients and may be recommended as a treatment option in ICU. It has also shown to enhance the weaning process and proved to be safe.

Effects of low frequency resonance on physiological function in rats / 医用生物力学

Objective To study the effect of continuous low frequency resonance on blood pressure, heart rate, breath rate and body temperature of the rat so as to provide basic data for the study of organs’ resonance injury and its reaction. Method Thirty two SD rats were divided into four groups randomly: false vibration group, 3 Hz vibration group, 6 Hz vibration group and 21 Hz vibration group. Femoral artery intubatton was given after anaesthesia with 1.5% sodium pentobarbital. All the rats were fastened on their back on the vibration platform staying calmly for 30 min. Then the vibration groups were given sine wave vibration with 5 mm amplitude(p-p), while the blood pressure, heart rate, breath rate and body temperature of the rats were measured at 0, 1, 3, 5, 10, 30, 60, 120, 180, 240, 300 and 360 min. The above physiological data were also observed in false vibration group at corresponding time. Results Continuous low frequency resonance could cause the blood pressure, heart rate, breath rate of the rat to rise rapidly after 1 min of vibration, and to reach the maximum value after 1 min to 3 min of vibration, and then to descend gradually and to be lower than the normal value after 30 min of vibration. The body temperature of the rat did not change at the beginning of vibration, but descended gradually after 10 min of vibration. At the beginning of vibration, the effect of 6 Hz resonance on blood pressure, heart rate, breath rate was dominating, while at the later stage, 3 Hz resonance was dominating. But the effect of the two frequencies on body temperature was accordant. Conclusions Continuous low frequency resonance can cause the blood pressure, heart rate, breath rate of the rat to rise rapidly at the beginning of vibration and then to descend gradually, and it can also depress the ability of body temperature regulation in rats.

Effects of Tai Chi Chuan combined with vibration training on the reflex activity of peripheral neuron / 医用生物力学

Objective To investigate the effects of Tai Chi Chuan combined with vibration training on the excitability of α-motorneuron pool and γ-reflex arc. Methods 55 healthy college students were divided into Tai Chi Chuan + vibration training (TAV) group, Tai Chi Chuan training (TAI) group, vibration training (VB) group, and control group (CON) for 8 weeks with 3 times training per week. Each time at pre-and post-training, H-reflex and M-wave were recorded by electrical stimulus induced on soleus muscle. T-reflex was also collected by knocking on the Achill tendon. Results After 8-week training, the ratios of Hmax/Mmax and T-reflex/Mmax in VB group were significantly decreased (P<0.05), while the ratio of T-reflex/Mmax in TAV group was significantly increased (P<0.05), and the change percentage of T-reflex/Mmax was significantly higher than that in VB group (P<0.05). Conclusions Although the vibration training could decrease the resting excitability of α-motorneuron pool, the Tai Chi Chuan combined with vibration training could give the muscle spindle stronger excitement so as to further induce the high excitability of γ-reflex arc. It indicated that the Tai Chi Chuan combined with vibration training is feasible since the neural adaptation around peripheral neuron system could be induced after such kind of training.