Bounds on the number of samples needed for neural learning.

The relationship between the number of hidden nodes in a neural network, the complexity of a multiclass discrimination problem, and the number of samples needed for effect learning are discussed. Bounds for the number of samples needed for effect learning are given. It is shown that Omega(min (d,n) M) boundary samples are required for successful classification of M clusters of samples using a two-hidden-layer neural network with d-dimensional inputs and n nodes in the first hidden layer.     

A VLSI architecture for a half-edge-based corner detector

Corner detection is a low-level feature detection operator that is of great use in image processing applications, for example, optical flow and structure from motion by image correspondence. The detection of corners is a computationally intensive operation. Past implementations of corner detection techniques have been restricted to software. In this paper we propose an efficient very large-scale integration (VLSI) architecture for detection of corners in images. The corner detection technique is based on the half-edge concept and the first directional derivative of Gaussian. Apart from the location of the corner points, the algorithm also computes the corner orientation and the corner angle and outputs the edge map of the image. The symmetrical properties of the masks are utilized to reduce the number of convolutions effectively, from eight to two. Therefore, the number of multiplications required per pixel is reduced from 1800 to 392. Thus, the proposed architecture yields a speed-up factor of 4.6 over conventional convolution architectures. The architecture uses the principles of pipelining and parallelism and can be implemented in VLSI.     

Catalytic reduction of N2O with CH4 and C3H6 over Ag–Rh/Al2O3 bimetallic catalyst in the presence of oxygen

A study of nitrous oxide (N₂O) reduction with methane (CH₄) and propene (C₃H₆) in the presence of oxygen (5%) over Ag/Al₂O₃, Rh/Al₂O₃ and Ag–Rh/Al₂O₃ catalysts, with Ag and Rh loadings of 5 wt% and 0.05 wt% respectively, has been performed. From the results, it was observed that the Ag–Rh bimetallic catalyst was the most active for both nitrous oxide removal (more than 95%) and hydrocarbon oxidation. This high activity seems to be connected with a synergistic effect between Ag and Rh. The findings from X‐ray diffraction and X‐ray photoelectron spectroscopy studies showed also, that there were no strong interactions (eg alloying) between Ag and Rh. Copyright © 2005 Society of Chemical Industry     

Performance of hashed cache data migration schemes on multicomputers

Many researchers approach the problem of programming distributed memory machines by assuming a global shared name space. Thus the user views the distributed memory of the machine as though it were shared. A major issue that arises at this point is how to manage the memory. When a processor accesses data stored on another processor's memory, data must be moved between the two processors. Once these data are retrieved from another processor's memory, several interesting issues are raised. Where should these data be stored locally? What transformations must be performed to the code to guarantee that the nonlocal accesses reference the correct memory location? What optimizations can be performed to reduce the time spent in accessing the nonlocal data? In this paper we examine various data migration mechanisms that allow an explicit and controlled mapping of data to memory. We describe, experimentally evaluate, and model a set of schemes for storing and retrieving off-processor array elements. The schemes are all based on using hash tables for efficient access of nonlocal data. The three different techniques evaluated are the basic hashed cache, partial enumeration, and full enumeration, the details of which are described in the paper. In all three schemes, nonlocal data are stored in hash tables—the difference is in the amount of memory used by the schemes and the retrieval mechanisms for nonlocal data.     

Efficacy of surgical treatment in traumatic central cord syndrome

BACKGROUND: Controversy surrounds the treatment of traumatic central cord syndrome (TCCS), as there are strong advocates for nonsurgical treatment for most patients. However, conservative treatment has been shown to yield a longer period of discomfort from pain and weakness in certain cases. METHODS: In a retrospective review of 114 patients presenting with acute or chronic TCCS from 1988-94, four different age groups were separately observed under different treatments. Motor and sensory recovery were assessed. RESULTS: Better results were achieved in younger patients, with or without radiographic abnormalities, and in patients with clinically correlated encroaching cord lesions who received early surgical decompression. CONCLUSIONS: Surgical intervention for TCCS must be addressed with careful clinical and radiographic survey. Removal of offending lesions in the subacute period results in significant motor and sensory improvement in short-term and long-term follow-up.     

Maxillary sinus augmentation in the non-human primate: a comparative radiographic and histologic study between recombinant human osteogenic protein-1 and natural bone mineral

The posterior maxilla has traditionally been one of the most difficult areas to successfully place dental implants due to poor bone quality and close approximation to the maxillary sinus. Sinus augmentation procedures have become a viable means of assuring adequate bone for the placement of dental implants in this area. However, with the techniques currently employed, a considerable variation in the quality of bone attained with the sinus augmentation procedure exists. The purpose of this in vivo study was to evaluate the healing response and bone formation stimulated by 3 doses of recombinant human osteogenic protein-1 (rhOP-1), 0.25, 0.6, and 2.5 mg OP-1 per gram of collagen matrix; natural bone mineral; or collagen matrix alone (control) placed in the maxillary sinus of adult chimpanzees. Results were assessed using clinical, histologic, and radiographic techniques. Radiographic analysis of the computed tomography scans taken at 1 week, and 2.5, 4.5, and 6.5 months revealed a more rapid mineralization with the 2.5 mg OP-1/g collagen matrix and natural bone mineral treatment groups. The incremental bone mineral density (BMD) increase for these 2 treatments from 1 week to 2.5 months was over 2.5 times the increase found with the collagen matrix alone; these 2 treatments also had a higher BMD at the most superior slices evaluated when compared to the other 3 groups. Biopsy specimens were taken at 3.5, 5.5, and 7.5 months and for all 5 treatment groups bone formation was observed at all time points in the majority of the specimens. At 7.5 months the 2.5 and 0.6 mg OP-1/g collagen matrix treatment groups had an increase in the percent bone area when compared to the matrix alone control. In conclusion, these results demonstrate that sinus augmentation with natural bone mineral or 2.5 mg OP-1/g collagen matrix induce comparable radiographic and histologic evidence of bone formation and that both of these treatments performed superior to the control group of collagen matrix alone based upon all methods of evaluation.     

An inverse solution methodology for estimating the diffusion coefficient of gases in Athabasca bitumen from pressure-decay data

An inverse solution methodology is developed for the estimation of diffusion coefficient of gases in highly viscous, oil-sands bitumens from isothermal, pressure-decay measurements. The approach involves modeling the rate of change in pressure using the diffusion equation for the liquid phase coupled with a mass balance equation for the gas phase. The inverse solution framework is utilized to arrive at two graphical techniques for estimating the diffusion coefficient. Both techniques involve the determination of the slope of a straight line resulting from plotting the experimental data in accordance with the developed model. An advantage of the proposed techniques is that the diffusion coefficient is estimated directly, i.e. without making it an adjustable parameter. The novelty of the proposed method is in its simplicity as well as its ability to isolate portions of the pressure-decay data affected by experimental fluctuations. The effect of the initial pressure on the predicted diffusion coefficient and pressure-decay profile was also investigated. The diffusion coefficients of CO₂, CH₄, C₂H₆ and N₂ in Athabasca bitumen at 50–90 °C and about 8 MPa were estimated and compared with literature values.     

Serologic and molecular detection of granulocytic ehrlichiosis in Rhode Island

A new indirect fluorescent-antibody (IFA) assay with antigen produced in vitro in the human promyelocytic leukemia cell line HL60 was used to identify the first recognized case of human granulocytic ehrlichiosis in Rhode Island. This IFA assay was used to detect granulocytic ehrlichiae in white-footed mice and in a dog inhabiting the area surrounding the patient's residence. Host-seeking Ixodes scapularis ticks found in the same habitat also were infected. I. scapularis ticks collected from other locations were fed on dogs and New Zealand White rabbits to assess the competency of these species as hosts of granulocytotropic Ehrlichia. Tick-induced infections of dogs were confirmed by serologic testing, tissue culture isolation, and PCR amplification, whereas several rabbits seroconverted but were PCR and culture negative. PCR amplification of the 16S rRNA gene and DNA sequencing of the PCR products or culture isolation was used to confirm granulocytic Ehrlichia infections in humans, dogs, white-footed mice, and ticks.