Feature extraction and classification models for high‐dimensional profile data

As manufacturing transitions to real‐time sensing, it becomes more important to handle multiple, high‐dimensional (non‐stationary) time series that generate thousands of measurements for each batch. Predictive models are often challenged by such high‐dimensional data and it is important to reduce the dimensionality for better performance. With thousands of measurements, even wavelet coefficients do not reduce the dimensionality sufficiently. We propose a two‐stage method that uses energy statistics from a discrete wavelet transform to identify process variables and appropriate resolutions of wavelet coefficients in an initial (screening) model. Variable importance scores from a modern random forest classifier are exploited in this stage. Coefficients that correspond to the identified variables and resolutions are then selected for a second‐stage predictive model. The approach is shown to provide good performance, along with interpretable results, in an example where multiple time series are used to indicate the need for preventive maintenance. In general, the two‐stage approach can handle high dimensionality and still provide interpretable features linked to the relevant process variables and wavelet resolutions that can be used for further analysis. Copyright © 2011 John Wiley & Sons, Ltd.     

Novel forsterite/polycaprolactone nanocomposite scaffold for tissue engineering applications

Novel highly porous nanocomposite scaffolds consisting of polycaprolactone (PCL) and forsterite nanopowder were prepared by a solvent-casting/particle-leaching method. In addition, the effects of forsterite nanopowder contents on the structure of the scaffolds were investigated to provide an appropriate composite for bone regenerative medicine. Results showed that the scaffolds exhibited high porosity (up to 92%) with open pores of 100-300 μm average diameters. This porosity increased with decreasing forsterite nanopowder content. In addition, the pore walls contained numerous micropores. Microstructure studies showed that the pores were well distributed throughout the structures. Furthermore, the bioactive forsterite nanoparticles were homogenously distributed within the PCL matrix of the scaffolds, which contained up to 30 wt.% forsterite nanopowder. This porous structure with micropores provides the properties required for bone tissue engineering applications.     

Clinical status of ulcerative colitis in patients who smoke

OBJECTIVES: Ulcerative colitis (UC) is largely a disease of nonsmokers. There are few patients who are current smokers, but we have identified a group and reviewed their clinical status, disease activity, and nicotine exposure to examine whether they remain well controlled while smoking. METHODS: Fifty-one patients from three centers with verified UC were reviewed. RESULTS: Thirty of the group were men; mean age 50 yr, with a mean age of onset of 37 yr. Twenty-two patients had proctosigmoid disease, 12 involvement of left colon, and 17 total colitis. All were current smokers; 41 were cigarette smokers averaging 17 daily. At the onset of colitis 30 were nonsmokers, 25 of them were ex-smokers and 19 developed colitis within 2 yr of stopping smoking. Twenty-eight believed smoking improved disease activity and none felt smoking had a detrimental effect on their UC. Eleven were receiving no medication for UC, 40 were receiving 5-ASA (5-aminosalicylic acid) preparations, and only two took oral steroids. All were in clinical remission, with the exception of one patient; mean St. Marks score was 1.5, out of a possible total of 22. Sigmoidoscopic grades were inactive in all patients except three. Histological assessment showed significant activity in only five. Median serum nicotine was 8 ng/ml (range, 0.4-24.4), median serum cotinine 180 ng/ml (range, 20-453), with corresponding salivary cotinine of 255 ng/ml (range, 34-683). Median rise in nicotine 2 min after a cigarette in 35 patients was 12.1 ng/ml (range, 0.4-44). CONCLUSIONS: Because most current smokers with UC have inactive disease, smoking may contribute to the clinical remission in these patients.     

Zone refining of sintered,microwave derived YBCO superconductors

Post-sintering treatments, such as zone melting under a thermal gradient, have been conducted on sintered YBCO tape cast films. YBCO precursor powder was derived through decomposition of a mixture of nitrates of cations in a microwave oven for ~ 4 min. The resulting powder was characterized and made into thin sheets by tape casting and then sintered at 945 °C for 5 h. The sintered tapes were subjected to repeated zone refining operations at the relatively high speed of ~ 30 mm h^–1. A microstructure having uniformly orientated grains in thea-b plane throughout the bulk of the sample was obtained by three repeated zone refining operations. Details of precursor preparation, microwave processing and its advantages, zone refining conditions and microstructural features are presented in this paper.     

Analysis of an InGaAsP/InP twin-overlayed-waveguide switch

This paper examines the design considerations for a device combining vertical stacking of waveguides, carrier injection, and codirectional switching in InGaAsP/InP materials and demonstrates that many favorable features can be found in such a device, namely, an interaction length of about 408 μm, switching with about 1 V with an injection current density of the order of 108-988 A/cm² and a channel isolation up to 25 db with an absorption loss of under 1 dB. We base our argument on a self-consistent numerical calculation     

Monte Carlo Simulation of Carbon Nanotube Devices

A self-consistent Monte Carlo simulator for carbon-nanotube, field-effect transistors (CNTFETs) is reported. Transport is simulated in zigzag (n, 0) nanotubes having a coaxial gating geometry, and key aspects of the Monte Carlo implementation are described. The simulator is used to extract the channel mean-free path (MFP) of CNTFETs. Although the mean-free path of acoustic phonons in metallic tubes is known to be very large (on the order of a micron), our results show that the channel MFP is much shorter and bias dependent in CNTFETs, and that CNTFETs therefore operate near the ballistic limit only at channel lengths that are considerably shorter than those required for near-ballistic transport in metallic tubes.     

Queueing model of a bi-level Markov service-system and its solutionusing recursion

The authors present a closed queueing model of a bi-level stochastic service system using a Markov process. The existence of two modes of operation in some real situations such as reliability, inventory, and production problems is outlined. A recursive solution technique is developed for computing steady-state probabilities and the relevant performance measures for such a system. A bi-level system is completely analyzed. The effect of the two modes of operation on the system performance measures is also discussed. The recursive solution technique is consistently superior to other common solution techniques with respect to computation time and memory requirement. A procedure is outlined for extension to a multi-level service system     

Anemia of pregnancy

A general work-up for anemia during pregnancy could follow a simplified flow diagram, such as the one shown in Figure 1. More specific laboratory tests should be selected as needed.