In vivo measurement of 3-D skeletal kinematics from sequences ofbiplane radiographs: Application to knee kinematics

Current noninvasive or minimally invasive methods for evaluating in vivo knee kinematics are inadequate for accurate determination of dynamic joint function due to limited accuracy and/or insufficient sampling rates. A three-dimensional (3-D) model-based method is presented to estimate skeletal motion of the knee from high-speed sequences of biplane radiographs. The method implicitly assumes that geometrical features cannot be detected reliably and an exact segmentation of bone edges is not always feasible. An existing biplane radiograph system was simulated as two separate single-plane radiograph systems. Position and orientation of the underlying bone was determined for each single-plane view by generating projections through a 3-D volumetric model (from computed tomography), and producing an image (digitally reconstructed radiograph) similar (based on texture information and rough edges of bone) to the two-dimensional radiographs. The absolute 3-D pose was determined using known imaging geometry of the biplane radiograph system and a 3-D line intersection method. Results were compared to data of known accuracy, obtained from a previously established bone-implanted marker method. Difference of controlled in vitro tests was on the order of 0.5 mm for translation and 1.4 degrees for rotation. A biplane radiograph sequence of a canine hindlimb during treadmill walking was used for in vivo testing, with differences on the order of 0.8 mm for translation and 2.5 degrees for rotation.     

The analysis of alkyl-capped alcohol ethoxylates and alcohol ethoxycarboxylates from alcohol ethoxylates by atmospheric pressure chemical ionization mass spectrometry

Alcohol ethoxylates (AEs) are nonionic surfactants. They are industrially important compounds that have historically been difficult to analyze, with the best results to date achieved through derivatization (e.g., silylation) followed by analysis by gas chromatography/mass spectrometry (GC/MS). Recently, mass spectrometric techniques such as field desorption (FD), time-of-flight secondary ion mass spectrometry (TOF-SIMS), fast atom bombardment (FAB), electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) have been employed to analyze surfynol(R) 4xx. In an effort to produce low-cost alkyl-capped AEs and anionic detergents from AEs, a fast and reliable measure of the product yields and conversions from AEs is required in research. We found that the product yields and conversions from reactions of AEs, obtained by the employment of atmospheric pressure chemical ionization (APCI), were in good agreement with those obtained from proton nuclear magnetic resonance spectroscopy ((1)H-NMR). Therefore, APCI can be used as a validated tool for studying AE reactions. Mixtures that contain either silylated or unsilylated ethoxylates and/or carboxylates yield the same APCI mass spectra. Copyright -Copyright 1999 John Wiley & Sons, Ltd.     

Concept of multipole magnetic field rotation in ECRIS

The conventional type of magnetic well is formed by superposition of two types of magnetic field, axial bumpy field and radial multipole field. It is used to contain plasma that consists of neutrals, ions and electrons. These particles are in constant motion in the well and energetic electrons create plasma by violent collisions with neutrals and ions. The confined electrons are constantly heated by ECR technique in the presence of magnetic field. In this paper it has been shown theoretically that how the electron motion is influenced in terms of heating, containment and azimuthal uniformity of plasma, by the axial rotation of the multipole magnetic field [1,2]. Afterwards, the feasibility of achieving a rotating magnetic multipole field is discussed to some extent. And it is seen that it is not beyond the capability of the scientific community in the present scenario of the advanced technology. Presently, it can be achieved for lesser field and slightly larger size of the multipole electromagnet and can be used for improvement of the ECR ion source (ECRIS).     

Optimizing head/media electrical characterization in the presence of skew at high track density

The skew angle causes a discrepancy in determining the reader-to-writer offset (RWO) when using different periodical patterns in track profile tests. It also separates the peak overwrite (OW) from the peak high frequency amplitude HFA, (1 T periodical pattern) on corresponding track profiles. Furthermore, higher track density and larger skew angle exacerbate the skew effect and induce more RWO error, thus impacting the parametric performance optimization. Simulation studies are used to interpret the skew effect on the RWO determination and OW cross-track characteristics. Based on experimental investigations and simulation analyses, using the HFA, track profile for deriving the optimal RWO is proposed for spin-stand tests. Actual parametric characterization has proven that the optimal RWO minimized the skew effect and the RWO error, thus improving the parametric performance and reducing the test variation. The method is beneficial and necessary for the high track density characterization.     

Parallel architecture for prototype training

The letter suggests an efficient parallel hardware architecture for prototype training in pattern recognition. Sample means and covariance matrices are computed by the same architecture and much attention is paid to the implementation of covariance matrices. A k2-chip of processor elements is used to implement covariance matrices.     

Thresholding based on learning theory

Learning theory is applied to real-time thresholding of gray-level images on a line-by-line basis. With this approach, each scan line becomes an isolated entity and a dynamic threshold value for each pixel is iteratively calculated while scanning. The approach works with horizontal or vertical scanning. The locations of objects in the image may also be identified while thresholding. This approach can be used to develop fast real-time algorithms suitable for hardware implementation     

Real-time thresholding technique

A real-time thresholding technique is presented. The technique depends on a simple RC integrator circuit where the input is a pulse train representing the image's grey level values and the output is the approximated estimate of the threshold values. The technique can handle noise-free and noisy images.