RESUMO
Human-machine information transfer through tactile excitation has addressed new applications in virtual reality, robotics, telesurgery, sensory substitution and rehabilitation for the handicapped in the past few years. Power consumption is an important factor in the design of vibrotactile displays, because it affects energy needs and the size, weight, heat dissipation and cost of the associated electronics. An experimental study is presented on the power required to reach tactile thresholds in electromechanical and piezo-electric transducers. Three different waveforms are considered, with an excitatory period formed by a burst of rectangular 50% duty cycle pulses (R50), rectangular low duty cycle pulses (RLO) and sinusoidal pulses (SIN). Ten different pulse repetition periods (RPs) were considered in the range 1/550-1/25 s. The voltage and current waveforms applied to the transducers at sensation thresholds in a group of 12 healthy subjects were sampled and stored in a digital oscilloscope. The average power was determined for each subject, and differences of two orders of magnitude were measured between the electromechanical and the piezo-electric transducer power consumption. Results show that, for the electromechanical transducer, a smaller power consumption of 25 microW was determined for RP = 1/25 s and the RLO waveform. In the case of the piezo-electric transducer, power of 0.21 microW was determined for SIN excitation and RP = 1/250 s. These results show the advantages of reducing power requirements for vibrotactile displays, which can be optimised by the choice of appropriate types of transducer, excitatory waveforms and pulse repetition periods.
Assuntos
Estimulação Física/instrumentação , Auxiliares Sensoriais , Transdutores , Adulto , Fontes de Energia Elétrica , Humanos , Tato , VibraçãoRESUMO
Glutaraldehyde-preserved bovine pericardium (GPBP) is evaluated as a bioprosthesis for the reconstruction of surgical defects in the thoracoabdominal wall. The mechanical properties of bovine pericardium preserved at different concentrations of glutaraldehyde were studied. Samples preserved in 0.5% glutaraldehyde showed a significantly higher tensile strength (11.7 +/- 0.8 N/mm2) than samples preserved in 2.5, 5, or 10% (similar to pericardium preserved in normal saline). The percentage of elongation was significantly lower than samples preserved in 1, 2.5, and 5% glutaraldehyde. GPBP at 0.5% was used to repair experimentally induced defects of the abdominal wall (n = 9), chest wall (n = 6), diaphragm (n = 6), and sternum (n = 7). All animals presented adequate tolerance to the material used and no case of infection or rejection of the material was seen in any of the animals. Finally, 0.5% GPBP was used clinically in a series of 40 patients: postincisional abdominal hernia (n = 30), inguinal hernia (n = 8), diaphragmatic hernia (n = 1), and congenital pelvic defect with prolapse of abdominal organs (n = 1). Surgical use showed that GPBP was a very manageable material and long-term results were good in 37 patients with a mean follow up of 18 months (range 5-35 months). Six patients presented seroma formation (all abdominal hernia patients), three of which eventually developed infection and had the GPBP patch removed at 3, 5, and 7 months postoperatively. The rest of the patients presented good scar formation with adequate resistance at the area of implantation. GPBP is a biological material with sufficient resistance to be used surgically in the repair of thoracoabdominal defects. Ideal concentration of glutaraldehyde to be used in the preparation-preservation of the material is 0.5% since higher concentration negatively affect its tensile rupture strength and elongation.
Assuntos
Músculos Abdominais/cirurgia , Pericárdio/transplante , Cirurgia Torácica/métodos , Adolescente , Adulto , Idoso , Animais , Bovinos , Criança , Pré-Escolar , Diafragma/cirurgia , Cães , Feminino , Glutaral , Herniorrafia , Humanos , Masculino , Pessoa de Meia-Idade , Omento/cirurgia , Doenças Peritoneais/etiologia , Resistência à Tração , Aderências Teciduais/etiologia , Preservação de Tecido/métodosAssuntos
Ciclosporina/uso terapêutico , Rejeição de Enxerto/urina , Transplante de Pulmão/fisiologia , Tromboxano B2/urina , Análise de Variância , Animais , Biomarcadores/urina , Cães , Terapia de Imunossupressão/métodos , Transplante de Pulmão/imunologia , Radioimunoensaio , Fatores de Tempo , Transplante HomólogoRESUMO
Se presenta la distribución arterial en el mesocolon transverso encontrado en la disección de 58 fetos frescos de ambos sexos a los cuales se les inyectó vía aorta látex coloreado para la visualización. Se resume la descripción de los textos anatómicos clásicos, se compara con nuestro trabajo y se comunican algunas diferencias y hallazgos entre los que se analiza como algo nuevo la presencia de arterias accesorias de la zona pancreática que no se describen en los textos clásicos
Assuntos
Humanos , Masculino , Feminino , Artérias/anatomia & histologia , Mesocolo/irrigação sanguínea , FetoRESUMO
1. Trabajo realizado en la disección de 83 cadáveres adultos recién fallecidos. 2. Se estudia la forma que presenta. 3. Se efectúan mediciones en sus diámetros transversal y anteroposterior central. 4. Se analizan su grosor y recargo adiposo. 5. Se analizan su origen y su implantación colónica. 6. Se describe su proyección frente a la columna vertebral. 7. Se compara nuestro trabajo con textos clásicos el cual es muy pobre ya que no describen los parámetros que a nosotros nos interesan. 8. Se analiza la importancia de sus dimensiones en relación a las colostomías transversas. 9. No se incluye el estudio de la vascularización arterial venosa y linfática ni la inervación lo que será motivo de un estudio posterior