A Novel Cable-Driven Robotic Training Improves Locomotor Function in Individuals Post-Stroke

A novel cable-driven robotic gait training system has been tested to improve the locomotor function in individuals post stroke. Seven subjects with chronic stroke were recruited to participate in this 6 weeks robot-assisted treadmill training paradigm. A controlled assistance force was applied to the paretic leg at the ankle through a cable-driven robotic system. The force was applied from late stance to mid-swing during treadmill training. Body weight support was provided as necessary to prevent knee buckling or toe drag. Subjects were trained 3 times a week for 6 weeks. Overground gait speed, 6 minute walking distance, and balance were evaluated at pre, post 6 weeks robotic training, and at 8 weeks follow up. Significant improvements in gait speed and 6 minute walking distance were obtained following robotic treadmill training through a cable-driven robotic system. Results from this study indicate that it is feasible to improve the locomotor function in individuals post stroke through a flexible cable-driven robot

Controlled Heterogeneous Nucleation and Growth of Germanium Quantum Dots on Nanopatterned Silicon Dioxide and Silicon Nitride Substrates

Controlled heterogeneous nucleation and growth of Ge quantum dots (QDs) are demonstrated on SiO_2/Si_3N_4 substrates by means of a novel fabrication process of thermally oxidizing nanopatterned SiGe layers. The otherwise random self-assembly process for QDs is shown to be strongly influenced by the nanopatterning in determining both the location and size of the QDs. Ostwald ripening processes are observed under further annealing at the oxidation temperature. Both nanopattern oxidation and Ostwald ripening offer additional mechanisms for lithography for controlling the size and placement of the QDs

Thermal Analysis on Cryogenic Liquid Hydrogen Tank on an Unmanned Aerial Vehicle System

Thermal analyses are performed on the liquid hydrogen (LH2) tank designed for an unmanned aerial vehicle (UAV) powered by solar arrays and a regenerative proton-exchange membrane (PEM) fuel cell. A 14-day cruise mission at a 65,000 ft altitude is considered. Thermal analysis provides the thermal loads on the tank system and the boiling-off rates of LH2. Different approaches are being considered to minimize the boiling-off rates of the LH2. It includes an evacuated multilayer insulation (MLI) versus aerogel insulation on the LH2 tank and aluminum versus stainless steel spacer rings between the inner and outer tank. The resulting boil-off rates of LH2 provided by the one-dimensional model and three-dimensional finite element analysis (FEA) on the tank system are presented and compared to validate the results of the three-dimensional FEA. It concludes that heat flux through penetrations by conduction is as significant as that through insulation around the tank. The tank system with MLI insulation and stainless steel spacer rings result in the lowest boiling-off rate of LH2

Water content of the Martian soil: Laboratory simulations of reflectance spectra

Reflectance spectra from the surface of Mars collected by instruments such as the imaging spectrometer (ISM) onboard the 1988 Soviet Phobos 2 spacecraft exhibit strong 3 μm absorption features that have long been attributed to hydrated materials on the Martian surface. This interpretation is consistent with a series of chemical weathering models suggesting an abundance of palagonites, clays, and other hydrated mineral phases in the Martian fines. Little work, however, has been done to constrain the actual water content of the Martian surface materials. New laboratory data presented here show that the ISM spectra are consistent with up to 4% water by weight and that the deep hydration features observed in the spacecraft data could be due to less than 0.5% water if the hydrated phases are present in the form of grain coatings. These results are consistent with the somewhat uncertain in situ measurements obtained by the Viking landers which yielded approximately 2 wt % water from samples heated to 500°C. On the basis of this work, we expect the TEGA instrument on the Mars '98 lander to find less than 4% adsorbed or bound water in the upper few centimeters of the Martian soil

Project Exodus

A design for a manned Mars mission, PROJECT EXODUS is presented. PROJECT EXODUS incorporates the design of a hypersonic waverider, cargo ship and NIMF (nuclear rocket using indigenous Martian fuel) shuttle lander to safely carry out a three to five month mission on the surface of Mars. The cargo ship transports return fuel, return engine, surface life support, NIMF shuttle, and the Mars base to low Mars orbit (LMO). The cargo ship is powered by a nuclear electric propulsion (NEP) system which allows the cargo ship to execute a spiral trajectory to Mars. The waverider transports ten astronauts to Mars and back. It is launched from the Space Station with propulsion provided by a chemical engine and a delta velocity of 9 km/sec. The waverider performs an aero-gravity assist maneuver through the atmosphere of Venus to obtain a deflection angle and increase in delta velocity. Once the waverider and cargo ship have docked the astronauts will detach the landing cargo capsules and nuclear electric power plant and remotely pilot them to the surface. They will then descend to the surface aboard the NIMF shuttle. A dome base will be quickly constructed on the surface and the astronauts will conduct an exploratory mission for three to five months. They will return to Earth and dock with the Space Station using the waverider

Stability of hydroxylated minerals on Mars: A study on the effects of exposure to ultraviolet radiation

The density and composition of the Martian atmosphere allow solar ultraviolet photons with wavelengths as short as 190 nm to reach the surface. We investigate the hypothesis that this UV radiation is capable of inducing the release of water from iron oxyhydroxide minerals resulting in the formation of oxide phases. These experiments, which utilize a quadrupole mass spectrometer to monitor the water vapor pressure above mineral samples during cyclic exposure to ultraviolet radiation, offer 5 to 6 orders of magnitude greater sensitivity than previous attempts to establish and quantify this process. We find no evidence that UV photons are capable of liberating OH from the crystal lattice of minerals, and we set a minimum ultraviolet radiation-induced dehydroxylation time of 10^8 years for removal of this structural OH from mineral particles at the Martian surface. The overturning timescales for surface fines are likely to be shorter than this lower limit for exposure time. Thus we conclude that UV-stimulated dehydroxylation is not a significant process at the Martian surface and that iron oxyhydroxides, if formed during an earlier water-rich environment, should still be found on Mars today. The lack of clear evidence for iron oxyhydroxides at the Martian surface further suggests that Mars' surface was never warm and wet for a long enough period of time for Earth-like weathering to have occurred

A Comparative Study on Machine Learning Algorithms for Network Defense

Network security specialists use machine learning algorithms to detect computer network attacks and prevent unauthorized access to their networks. Traditionally, signature and anomaly detection techniques have been used for network defense. However, detection techniques must adapt to keep pace with continuously changing security attacks. Therefore, machine learning algorithms always learn from experience and are appropriate tools for this adaptation. In this paper, ten machine learning algorithms were trained with the KDD99 dataset with labels, then they were tested with different dataset without labels. The researchers investigate the speed and the efficiency of these machine learning algorithms in terms of several selected benchmarks such as time to build models, kappa statistic, root mean squared error, accuracy by attack class, and percentage of correctly classified instances of the classifier algorithms

HIV cure strategies: Which ones are appropriate for Africa?

Although combination antiretroviral therapy (ART) has reduced mortality and improved lifespan for people living with HIV, it does not provide a cure. Patients must be on ART for the rest of their lives and contend with side effects, unsustainable costs, and the development of drug resistance. A cure for HIV is, therefore, warranted to avoid the limitations of the current therapy and restore full health. However, this cure is difficult to find due to the persistence of latently infected HIV cellular reservoirs during suppressive ART. Approaches to HIV cure being investigated include boosting the host immune system, genetic approaches to disable co-receptors and the viral genome, purging cells harboring latent HIV with latency-reversing latency agents (LRAs) (shock and kill), intensifying ART as a cure, preventing replication of latent proviruses (block and lock) and boosting T cell turnover to reduce HIV-1 reservoirs (rinse and replace). Since most people living with HIV are in Africa, methods being developed for a cure must be amenable to clinical trials and deployment on the continent. This review discusses the current approaches to HIV cure and comments on their appropriateness for Africa