New control strategies for neuroprosthetic systems

The availability of techniques to artificially excite paralyzed muscles opens enormous potential for restoring both upper and lower extremity movements with\ud neuroprostheses. Neuroprostheses must stimulate muscle, and control and regulate the artificial movements produced. Control methods to accomplish these tasks include feedforward (open-loop), feedback, and adaptive control. Feedforward control requires a great deal of information about the biomechanical behavior of the limb. For the upper extremity, an artificial motor program was developed to provide such movement program input to a neuroprosthesis. In lower extremity control, one group achieved their best results by attempting to meet naturally perceived gait objectives rather than to follow an exact joint angle trajectory. Adaptive feedforward control, as implemented in the cycleto-cycle controller, gave good compensation for the gradual decrease in performance observed with open-loop control. A neural network controller was able to control its system to customize stimulation parameters in order to generate a desired output trajectory in a given individual and to maintain tracking performance in the presence of muscle fatigue. The authors believe that practical FNS control systems must\ud exhibit many of these features of neurophysiological systems

Feeding milk

The value of milk for young animals is well known to Iowa farmers; its value as part of a feeding ration for all animals has not been so well determined. Dairying is increasing so fast in the state, that this Station thought it wise to ascertain the value of milk, as a ration, or part of a ration, for cows giving milk. During the interval between college terms in 1891, we had surplus full milk, and skimmed milk, that we resolved to feed to cows on pasture to ascertain its effect on milk-giving. We took two Holstein cows to experiment with, Nos. 155 and 151. The former had been giving milk fora month, the latter was fresh

Methods and apparatus for the on-site production of hydrogen peroxide

Methods, apparatus, and applications for the on-site production of hydrogen peroxide are described. An embodiment of the apparatus comprises at least one anolyte chamber coupled to at least one anode, at least one catholyte chamber, wherein the at least one catholyte chamber is coupled to at least one cathode, at least one anode membrane and at least one cathode membrane, wherein the anode membrane is adjacent to the at least one anode, wherein the cathode membrane is adjacent to the at least one cathode, at least one central chamber disposed between the at least one anolyte chamber and the at least one catholyte chamber. Hydrogen peroxide is produced by reduction of an oxygen-containing gas at the cathode

EC92-124 Nebraska Handbook of Range Management

Every Nebraskans should be interested in rangeland. The plants, soil, and water are the foundation of Nebraska\u27s economy and quality of life. Rangeland is one of Nebraska\u27s most important and valuable natural resources because it: • produces forage for livestock and wild game; • provides a varied habitat for many wildlife species; • protects the soil from wind and water erosion; • preserves a germplasm bank for many plant species that may become important for yet unknown uses; • purifies and enhances the environment by cleasing the air, filtering the runoff to streams, increasing the intake of precipitation, and aiding groundwater recharge; • perseveres in adversity and renews itself when the opportunity is provided by those who use and sometimes abuse it; and • pleases those who have learned to appreciate the beauty and aesthetic qualities of rangeland. These are called the Seven P\u27s of Rangeland. Range plants must be the right kind and kept productive for best use of this resource. Most people enjoy wildlife, hunting, camping, clean water, fishing, and eating beef. Range supplies us with those items, so we must management it wisely

Systems engineering analysis of aplanatic Wolter type I x-ray telescopes

It is well known that normal-incidence aplanatic telescope designs perform better at small field angles than ones corrected only for spherical aberration. This is why most large astronomical telescopes fabricated in the past fifty years have been of the Ritchey-Chretien (aplanatic) design rather than of the classical Cassegrain design. For the relatively new field of x-ray astronomy, the Welter type I grazing incidence design has been extensively utilized. It consists of a paraboloidal primary mirror coaxial with a confocal hyperboloidal secondary mirror. Aplanatic versions of the Welter type I grazing incidence x-ray telescope have been discussed in detail in the literature, and are widely touted as being superior designs. However, scattering effects from residual optical fabrication errors and other practical engineering error sources prevent these grazing-incidence telescopes from being near diffraction-limited (even on axis) at the very short operational x-ray wavelengths. A systems engineering analysis of these error sources indicates that they will dominate coma at the small field angles, and of course astigmatism, field curvature, and higher-order aberrations dominate coma at the large field angles. Hence, there is little improvement in performance when going to an aplanatic design. Comparison of performance predictions for the classical versus aplanatic Welter type I x-ray telescope are presented for the special case of the Solar X-Ray Imager (SXI) baseline design. SXI is expected to become a standard subsystem aboard the next generation of NOAA/GOES weather satellites

SDSS J142625.71+575218.3: A Prototype for A New Class of Variable White Dwarf

We present the results of a search for pulsations in six of the recently discovered carbon-atmosphere white dwarf ("hot DQ") stars. On the basis of our theoretical calculations, the star SDSS J142625.71 + 575218.3 is the only object expected to pulsate. We observe this star to be variable, with significant power at 417.7 s and 208.8 s ( first harmonic), making it a strong candidate as the first member of a new class of pulsating white dwarf stars, the DQVs. Its folded pulse shape, however, is quite different from that of other white dwarf variables and shows similarities with that of the cataclysmic variable AM CVn, raising the possibility that this star may be a carbon-transferring analog of AM CVn stars. In either case, these observations represent the discovery of a new and exciting class of object.NSF AST-0507639, AST-0602288, AST-0607480, AST-0307321Astronom

Computing equilibrium states of cholesteric liquid crystals in elliptical channels with deflation algorithms

We study the problem of a cholesteric liquid crystal confined to an elliptical channel. The system is geometrically frustrated because the cholesteric prefers to adopt a uniform rate of twist deformation, but the elliptical domain precludes this. The frustration is resolved by deformation of the layers or introduction of defects, leading to a particularly rich family of equilibrium configurations. To identify the solution set, we adapt and apply a new family of algorithms, known as deflation methods, that iteratively modify the free energy extremisation problem by removing previously known solutions. A second algorithm, deflated continuation, is used to track solution branches as a function of the aspect ratio of the ellipse and preferred pitch of the cholesteric.Comment: 9 pages, 6 figure

Correlation of a-Amylase Inhibitor Content in Eastern Soft Wheats with Development Parameters of the Rice Weevil (Coleoptera: Curculionidae)

The a-amylase inhibitor content in saline extracts of 104 Eastern soft wheat cultivars was determined by assay against a purified a-amylase preparation from the rice weevil, Sitophilus oryzae (L.). A two-fold range of inhibitor levels, expressed as amylase inhibitor units per gram of dry weight (AID/g), was found across all cultivars. Inhibitory activity was lowest in cultivar \u27Augusta\u27 (5,084 ± 124 AIU/g) and highest in cultivar \u27Logan\u27 (10,410 ± 61 AID/g). No correlation of inhibitor content with progeny production (r = -0.161) or rate of emergence (r = -0.292) was found among weevils reared on 30 cultivars having relatively low, medium, and high inhibitor levels, but there was a positive correlation between inhibitor content and average number of days to adult emergence (r = 0.569). Although mean development times were significantly different on cultivars with low and high AIU/g (35.9 ± 0.2 and 36.6 ± 0.1 d, respectively), the differences were only slight and indicated that, for these cultivars of soft wheats, a-amylase inhibitors have little practical effect on initial population reductions. Nevertheless, based on a population model for S. oryzae developing on wheat at 25°C and 75% RH, the slight delay in mean development time (0.7 d) on cultivars with relatively high AIU/g results in a 20.9% reduction in total number of weevils after 180 d. Simulations also indicate that physical or biochemical resistance factors in wheat have to delay development time for about 6.2 d or reduce fecundity by about 40% to prevent wheat from being graded weevily 180 d after a single pair of weevils infests a hypothetical 6,000-bushel wheat bin

Global MHD simulation of flux transfer events at the high-latitude magnetopause observed by the cluster spacecraft and the SuperDARN radar system

A global magnetohydrodynamic numerical simulation is used to study the large-scale structure and formation location of flux transfer events (FTEs) in synergy with in situ spacecraft and ground-based observations. During the main period of interest on the 14 February 2001 from 0930 to 1100 UT the Cluster spacecraft were approaching the Northern Hemisphere high-latitude magnetopause in the postnoon sector on an outbound trajectory. Throughout this period the magnetic field, electron, and ion sensors on board Cluster observed characteristic signatures of FTEs. A few minutes delayed to these observations the Super Dual Auroral Radar Network (SuperDARN) system indicated flow disturbances in the conjugate ionospheres. These “two-point” observations on the ground and in space were closely correlated and were caused by ongoing unsteady reconnection in the vicinity of the spacecraft. The three-dimensional structures and dynamics of the observed FTEs and the associated reconnection sites are studied by using the Block-Adaptive-Tree-Solarwind-Roe-Upwind-Scheme (BATS-R-US) MHD code in combination with a simple open flux tube motion model (Cooling). Using these two models the spatial and temporal evolution of the FTEs is estimated. The models fill the gaps left by measurements and allow a “point-to-point” mapping between the instruments in order to investigate the global structure of the phenomenon. The modeled results presented are in good correlation with previous theoretical and observational studies addressing individual features of FTEs

The Devil is in the details:Pentagonal bipyramids and dynamic arrest

Colloidal suspensions have long been studied as a model for atomic and molecular systems, due to the ability to fluorescently label and individually track each particle, yielding particle-resolved structural information. This allows various local order parameters to be probed that are otherwise inaccessible for a comparable molecular system. For phase transitions such as crystallisation, appropriate order parameters which emphasise 6-fold symmetry are a natural choice, but for vitrification the choice of order parameter is less clear cut. Previous work has highlighted the importance of icosahedral local structure as the glass transition is approached. However, counting icosahedra or related motifs is not a continuous order parameter in the same way as, for example, the bond-orientational order parameters $Q_{6}$ and $W_6$. In this work we investigate the suitability of using pentagonal bipyramid membership, a structure which can be assembled into larger, five-fold symmetric structures, as a finer order parameter to investigate the glass transition. We explore various structural and dynamic properties and show that this new approach produces many of the same findings as simple icosahedral membership, but we also find that large instantaneous displacements are often correlated with significant changes in pentagonal bipyramid membership, and unlike the population of defective icosahedra, the pentagonal bypyramid membership and spindle number do not saturate for any measured volume fraction, but continues to increase.Comment: accepted by JStat Mech: Theory and Experiment 201