Low-temperature solvent fractionation of corn oil and calculation of its glyceride structure

Summary Corn oil was subjected to a low-temperature solventfractionation process and separated into 19 glyceride fractions; the glyceride structures of the fractions were calculated and added to obtain the glyceride structure of the oil. The experimentally obtained glyceride structure was compared to the structures calculated according to the mono-acid triglyceride, random, even, and partial random schemes and was found to agree most closely with the partial random system. The generous financial assistance of the Corn Products Refining Company, Argo, Illinois, is gratefully acknowledged. Contribution from the Department of Chemistry, University of Pittsburgh.     

A Scalable Intelligent Takeoff Controller for a Simulated Running Jointed Leg

Running with jointed legs poses a difficult control problem in robotics. Neural controllers are attractive because they allow the robot to adapt to changing environmental conditions. However, scalability is an issue with many neural controllers. This paper describes the development of a scalable neurofuzzy controller for the takeoff phase of the running stride. Scalability is achieved by selecting a controller whose size does not grow with the dimensionality of the problem. Empirical results show that with proper design the takeoff controller scales from a leg with a single movable link to one with three movable links without a corresponding growth in size and without a loss of accuracy.     

Statistical AM-FM models, extended Kalman filter demodulation,Cramer-Rao bounds, and speech analysis

A stochastic dynamical system model for describing time signals that are jointly amplitude (AM) and frequency (FM) modulated is presented. The signal is assumed to be bandpass, perhaps originating from a filter bank applied to a broadband signal, and includes the constraint that the magnitude of the complex baseband signal is positive. Motivated by speech processing and the desire for narrowband modulating signals, time is divided into frames, and the modulating signals are smoothly interpolated across each frame. The model allows a detailed characterization of the bandwidth of the modulating signals and the statistical character of the measurement noise. An adaptive estimation algorithm based on extended Kalman filtering ideas for extracting the modulating signals from the measured signal is described and demonstrated on both voiced and unvoiced speech signals. The Cramer-Rao bound on the performance of any estimator is computed     

Upper Extremity Limb Function Discrimination Using EMG Signal Analysis

A signal analysis technique is developed for discriminating a set of lower arm and wrist functions using surface EMG signals. Data wete obtained from four electrodes placed around the proximal forearm. The functions analyzed included wrist flexion/extension, wrist abduction/adduction, and forearm pronation/supination. Multivariate autoregression models were derived for each function; discrimination was performed using a multiple-model hypothesis detection technique. This approach extends the work of Graupe and Cline [1] by including spatial correlations and by using a more generalized detection philosophy, based on analysis of the time history of all limb function probabilities. These probabilities are the sufficient statistics for the problem if the EMG data are stationary Gauss-Markov processes. Experimental results on-normal subjects are presented which demonstrate the advantages of using the spatial and time correlation of the signals. This technique should be useful in generating control signals for prosthetic devices.     

Nonlinear modeling and processing of speech based on sums of AM-FMformant models

We describe a new statistical approach based on nonlinear filtering ideas for decomposing signals that are modeled as a sum of jointly amplitude- and frequency-modulated cosines, where each cosine has a slowly varying center frequency and the sum of terms is observed in additive noise. This is an alternative approach to methods based on deterministic models such as the Kaiser-Teager (see Proc. IEEE ICASSP-93, vol.III, p.149 and IEEE Trans. Acoust., Speech, Signal Processing, vol.28, no.5, pp. 599, 1980) energy operator. The Cramer-Rao bound for the resulting statistical estimation problem is computed. A practical nonlinear filter, an extended Kalman filter, is described. We demonstrate the ideas on a variety of speech problems     

Bayesian reconstruction of signals invariant under a space-groupsymmetry from Fourier transform magnitudes

A Bayesian signal reconstruction problem, motivated by X-ray crystallography, which includes magnitude of Fourier transform measurements and a Markov random field a priori model was approximately solved by Doerschuk (see J. Opt. Soc. Amer. A, vol.8, no.8, p.1222-1232 and p.1207-1221, 1991). These ideas are extended to signals that obey a space-group symmetry, which is a crucial extension for X-ray crystallography application. Performance statistics based on simulated data are presented.     

Symmetry-constrained 3-D interpolation of viral X-raycrystallography data

A three-dimensional (3-D) interpolation problem that is important in viral X-ray crystallography is considered. The problem requires new methods because the function is known to have icosahedral symmetry, the data is corrupted by experimental errors and therefore lacks the symmetry, the problem is 3-D, the measurements are irregularly spaced, and the number of measurements is large (10⁴). A least-squares approach is taken using two sets of basis functions: the functions implied by a minimum-energy bandlimited exact interpolation problem and a complete orthonormal set of bandlimited functions. A numerical example of the Cowpea Mosaic Virus is described     

Inflammatory cell distribution within and along asthmatic airways

Asthmatic airways are infiltrated with inflammatory cells that release mediators and cytokines into the microenvironment. In this study, we evaluated the distribution of CD45-positive leukocytes and eosinophils in lung tissue from five patients who died with severe asthma compared with five patients with cystic fibrosis. For morphometric analysis, the airway wall was partitioned into an "inner" area (between basement membrane and smooth muscle) and an "outer" area (between smooth muscle and alveolar attachments). Large airways (with a perimeter greater than 3.0 mm) from patients with asthma or cystic fibrosis had a greater density of CD45-positive cells (p < 0.05) and eosinophils (p < 0.001) in the inner airway region compared with the same airway region in small airways. Furthermore, in small airways, asthmatic lungs showed a greater density of CD45-positive cells (p < 0.01) and eosinophils (p < 0.01) in the outer compared with the inner airway wall region. These observations indicate that there are regional variations in inflammatory cell distribution within the airway wall in patients with asthma that are not observed in airways from patients with cystic fibrosis. We speculate that this inflammatory cell density in peripheral airways in severe asthma may relate to the peripheral airway obstruction characteristic of this condition.     

Increasing Participation of Females and Underrepresented Minorities in Computing

Retaining and recruiting women and underrepresented minorities in computing is an important issue for computing educators.