A haptic control system for functional electrical stimulation of paraplegic legs

Functional electrical stimulation (FES) is a means by which paraplegic men and women can use their natural legs for walking. In FES the impaired muscles are stimulated with electricity in a proper cycle to cause the legs to move in a walking pattern. It can be greatly beneficial for paraplegics however, current systems are not widely used because they are difficult to control in a useful manner. The system proposed here uses a haptic interface, one that utilizes the sense of touch, attached to a user’s index and middle fingers. The haptic device allows the wearer to feel with the fingers what would normally be felt by the feet. Movement of the fingers is monitored and the positions of the two fingertips can be used to dictate the appropriate positions for the feet to be moved to using FES. Therefore, by moving the fingers in a cyclic pattern similar to that of walking, a stimulation pattern needed for activation of leg muscles to allow walking can be generated. Further, by having the sense of feeling for the feet translated to the fingers a person could have improved control over their legs. To test the feasibility of this system a virtual simulation was developed. The simulation navigated a virtual environment using the finger walking technique. The trajectory and velocity of the movements of the subjects was compared to normal human gait and it was found that finger walking greatly resembles natural human gait. Further, it was determined that control was enhanced by haptic feedback. These results show that FES walking can benefit from a controller that incorporates haptics

Mass study for modular approaches to a solar electric propulsion module

The propulsion module comprises six to eight 30-cm thruster and power processing units, a mercury propellant storage and distribution system, a solar array ranging in power from 18 to 25 kW, and the thermal and structure systems required to support the thrust and power subsystems. Launch and on-orbit configurations are presented for both modular approaches. The propulsion module satisfies the thermal design requirements of a multimission set including: Mercury, Saturn, and Jupiter orbiters, a 1-AU solar observatory, and comet and asteroid rendezvous. A detailed mass breakdown and a mass equation relating the total mass to the number of thrusters and solar array power requirement is given for both approaches

Effect of Thickness on Structural, Optical and Sensing Properties of SnS Thin Films Prepared by Ultrasonic Nebulizer Method

Thin Film of tin sulfide with different thickness (100, 250, 450, 600 ) nm have been prepared on pre-heated glass substrates up to (430oC)by Ultrasonic Nebulizer Deposition (UND). The effect of thickness on the structural, optical, and gas sensing properties of films has been investigated. The results of the XRD show that the film which deposited with thickness (100 and 250) nm exhibit only SnS phase with (111) orientation, and with thickness (450 and 600) nm crystallized in the mixed phase SnS and Sn2S3depending upon the films thickness. Atomic force measurement showed the grain size increase with thickness in the range of (76.08 - 105.67 nm).The optical properties of the films have been studied over a wavelength (370-1100) nm. The calculated optical energy band gap values were between 1.3 and 2.4 eV, depending on the film thickness and in which phase crystallized. The effect of thickness and operating temperature on performance of the sensor material has been investigated to choice optimum thickness and temperature for each ethanol and ammonia gases. The films with 600 nm thickness showed high response and excellent sensitivity for ethanol and ammonia gases at low temperature (140,110)oC and high temperature (380,240) oC respectively

A mechanical, thermal and electrical packaging design for a prototype power management and control system for the 30 cm mercury ion thruster

A prototype electric power management and thruster control system for a 30 cm ion thruster is described. The system meets all of the requirements necessary to operate a thruster in a fully automatic mode. Power input to the system can vary over a full two to one dynamic range (200 to 400 V) for the solar array or other power source. The power management and control system is designed to protect the thruster, the flight system and itself from arcs and is fully compatible with standard spacecraft electronics. The system is easily integrated into flight systems which can operate over a thermal environment ranging from 0.3 to 5 AU. The complete power management and control system measures 45.7 cm (18 in.) x 15.2 cm (6 in.) x 114.8 cm (45.2 in.) and weighs 36.2 kg (79.7 lb). At full power the overall efficiency of the system is estimated to be 87.4 percent. Three systems are currently being built and a full schedule of environmental and electrical testing is planned

Study of microRNAs-21/221 as potential breast cancer biomarkers in Egyptian women

microRNAs (miRNAs) play an important role in cancer prognosis. They are small molecules, approximately 17–25 nucleotides in length, and their high stability in human serum supports their use as novel diagnostic biomarkers of cancer and other pathological conditions. In this study, we analyzed the expression patterns of miR-21 and miR-221 in the serum from a total of 100 Egyptian female subjects with breast cancer, fibroadenoma, and healthy control subjects. Using microarray-based expression profiling followed by real-time polymerase chain reaction validation, we compared the levels of the two circulating miRNAs in the serum of patients with breast cancer (n = 50), fibroadenoma (n = 25), and healthy controls (n = 25). The miRNA SNORD68 was chosen as the housekeeping endogenous control. We found that the serum levels of miR-21 and miR-221 were significantly overexpressed in breast cancer patients compared to normal controls and fibroadenoma patients. Receiver Operating Characteristic (ROC) curve analysis revealed that miR-21 has greater potential in discriminating between breast cancer patients and the control group, while miR-221 has greater potential in discriminating between breast cancer and fibroadenoma patients. Classification models using k-Nearest Neighbor (kNN), Naïve Bayes (NB), and Random Forests (RF) were developed using expression levels of both miR-21 and miR-221. Best classification performance was achieved by NB Classification models, reaching 91% of correct classification. Furthermore, relative miR-221 expression was associated with histological tumor grades. Therefore, it may be concluded that both miR-21 and miR-221 can be used to differentiate between breast cancer patients and healthy controls, but that the diagnostic accuracy of serum miR-21 is superior to miR-221 for breast cancer prediction. miR-221 has more diagnostic power in discriminating between breast cancer and fibroadenoma patients. The overexpression of miR-221 has been associated with the breast cancer grade. We also demonstrated that the combined expression of miR-21 and miR-221can be successfully applied as breast cancer biomarkers