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In this work we present for the first time, to our knowledge, the CVD epitaxial growth of β-SiC using an ion beam synthesized (IBS) β-SiC layer as seed, which has been formed by multiple implantation into Si wafers at 500 °C. The ion beam synthesized continuous layer is constituted by β-SiC nanocrystals that are well oriented relative to the silicon substrate. Comparison of the epitaxial growth on these samples with that on silicon test samples, both on and off-axis, is performed. The results show that the epitaxial growth can be achieved on the IBS samples without the need of the carbonization step and that the structural quality of the CVD layer is comparable to that obtained on a carbonized silicon sample. Improvement of the quality of the deposited layer is proposed., QC 20150313

The diffusion of deuterium (H-2) in epitaxial 4H-SiC layers with buried highly Al-acceptor doped regions has been studied by secondary ion mass spectrometry. H-2 was introduced in the near surface region by the use of 20-keV implantation after which the samples were thermally annealed. As a result, an anomalous accumulation of H-2 in the high doped layers was observed. To explain the accumulation kinetics, a model is proposed where positively charged H-2 ions are driven into the high doped layer and become trapped there by the strong electric field at the edges. This effect is important for other semiconductors as well, since hydrogen is a common impurity present at high concentrations in many semiconductors., QC 20150625

NR 20140805

Deuterium was introduced in p-type SiC from a gas ambient. The samples were partially coated with 200 Angstrom thick metal layer of titanium, nickel, platinum or gold. Heat treatments were performed in the temperature range 500-800 degreesC during 4 h. Secondary ion mass spectrometry (SIMS) was used to measure the deuterium content after deuterium exposure. The catalytic metal coating is shown to play an important role for introducing deuterium into SiC. Nickel and platinum facilitate hydrogen incorporation in p-type SiC, which may be due to an increased hydrogen concentration at the metal/SiC interface and/or an increase the H+ ions to H ratio. No in-diffusion of deuterium is observed using titanium although large quantities of deuterium are stored in the titanium film. Furthermore, gold reveals an inert character and does not promote in-diffusion of deuterium., International Conference on Silicon Carbide and Related Materials, RES TRIANGLE PK, NORTH CAROLINA, OCT 10-15, 1999 NR 20140805

This study is an investigation of the relationship between muscle morphology and surface electromyographic (EMG) parameters [mean frequency of the power spectrum (MNF), signal amplitude (root mean square, RMS) and the signal amplitude ratio (SAR, i.e. the ratio between the RMS level during the passive part of the contraction cycle and the RMS level during the active part of the contraction cycle)] during 100 maximal dynamic knee extensions at 90░.s-1. Each contraction cycle comprised of 1 s of active knee extension and 1 s of passive knee flexion. The surface EMG was recorded from the vastus lateralis muscle. Twenty clinically healthy subjects participated in the study, and muscle biopsy samples of the vastus lateralis were obtained from 19 of those subjects. The relationships between muscle morphology and EMG were investigated at three stages of the test: initially, during the fatigue phase (initial 40 contractions), and at the endurance level (the final 50 contractions). Major findings on correlations are that SAR and MNF tended to correlate positively with the proportion of type 1 fibres, and RMS correlated positively with the proportion of type 2 muscle fibres. The muscle fibre areas showed little correlation with the EMG variables under investigation. The results of the present study showed that the three EMG variables of a dynamic endurance test that were investigated (RMS, MNF and SAR were clearly correlated with the proportions of the different fibre types, but only to a small extent with fibre areas. These findings contradict some of the theoretical models of the EMG, especially for parameters in the frequency domain.

In this paper, we introduce the nonstationary signal analysis methods to analyze the myoelectric (ME) signals during dynamic contractions by estimating the time-dependent spectral moments. The time-frequency analysis methods including the short-time Fourier transform, the Wigner-Ville distribution, the Choi-Williams distribution, and the continuous wavelet transform were compared for estimation accuracy and precision on synthesized and real ME signals. It is found that the estimates provided by the continuous wavelet transform have better accuracy and precision than those obtained with the other time-frequency analysis methods on simulated data sets. In addition, ME signals from four subjects during three different tests (maximum static voluntary contraction, ramp contraction, and repeated isokinetic contractions) were also examined.In this paper, we introduce the nonstationary signal analysis methods to analyze the myoelectric (ME) signals during dynamic contractions by estimating the time-dependent spectral moments. The time-frequency analysis methods including the short-time Fourier transform, the Wigner-Ville distribution, the Choi-Williams distribution, and the continuous wavelet transform were compared for estimation accuracy and precision on synthesized and real ME signals. It is found that the estimates provided by the continuous wavelet transform have better accuracy and precision than those obtained with the other time-frequency analysis methods on simulated data sets. In addition, ME signals from four subjects during three different tests (maximum static voluntary contraction, ramp contraction, and repeated isokinetic contractions) were also examined.

A capillary zone electrophoretic method for the analysis of low molecular weight carboxylic acids in water was developed. The application uses the chromophore trimellitic acid that allows for indirect photometric detection at 254 nm. Selectivity control by the addition of Ca2+ to the carrier electrolyte made possible a baseline resolved separation of 14 carboxylic acids. Good linearity and repeatability were obtained for both electrokinetic and hydrostatic injection modes. The usefulness of the method is demonstrated by the analysis of a snow sample.

The applicability of a recently developed capillary zone electrophoretic (CZE) method for the determination of low molecular weight (LMW) organic acids in water was tested on five types of environmental samples (rainwater, water extract from peat, and soil water from two polluted sites). A full baseline resolved separation of fourteen commonly found LMW carboxylic acids in natural waters (malonic, oxalic, fumaric, maleic, formic, succinic, tartaric, glutaric, adipic, acetic, propionic, butyric, valeric and citric acids), was achieved within eight minutes. The limits of detection (2 x noise) were in the ranges 90-200 mug/l and 0.5 - 5 mug/l for hydrodynamic and electrokinetic injection, respectively. Two different CZE systems, a Waters Quanta 4000 and a Hewlett Packard HP (CE)-C-3D system, were used and their performance compared.

Deuterium was introduced in p-type SiC from a gas ambient. The samples were partially coated with 200 Angstrom thick metal layer of titanium, nickel, platinum or gold. Heat treatments were performed in the temperature range 500-800 degreesC during 4 h. Secondary ion mass spectrometry (SIMS) was used to measure the deuterium content after deuterium exposure. The catalytic metal coating is shown to play an important role for introducing deuterium into SiC. Nickel and platinum facilitate hydrogen incorporation in p-type SiC, which may be due to an increased hydrogen concentration at the metal/SiC interface and/or an increase the H+ ions to H ratio. No in-diffusion of deuterium is observed using titanium although large quantities of deuterium are stored in the titanium film. Furthermore, gold reveals an inert character and does not promote in-diffusion of deuterium.

A concept for the fabrication of low cost resonant scanning miners using standard microstructure technology is proposed. To demonstrate the process a mirror device for a head mounted display system was designed and fabricated. The mirror was successfully, Addresses: Vangbo M, Uppsala Univ, Angstrom Lab, Box 534, SE-75221 Uppsala, Sweden. Uppsala Univ, Angstrom Lab, SE-75221 Uppsala, Sweden.

NR 20150402

SiC epitaxial layers have been grown in a commercial multi-wafer reactor. Results from the initial growth runs are presented. The reactor is vertical and has a high speed rotating susceptor that can support up to six 50 mm diameter wafers. The surface morphology of the grown layers are specular and show no indication of step-bunching. The unintentional background doping is p-type in the low 10(15) cm(-3) range, consisting mainly of Al. Both N and Al have been used for doped layers showing wide doping range capability and sharp transients. The best uniformity in thickness and doping achieved so far on the same 35 mm wafer are +/- 7% and +/- 10%, respectively. (C) 1999 Elsevier Science S.A. All rights reserved., QC 20150625

Deuterium and lithium were introduced in p-type SiC by implantation of 20 keV H-2(+) or 30 keV Li-7(+) ions in order to form a diffusion source. The samples were subsequently annealed in vacuum in the temperature range 400-700 degrees C for 0.25 to 16 h. Secondary ion mass spectrometry (SIMS) was used to measure the deuterium and the lithium distribution after heat treatments. Both deuterium and lithium readily decorate the bombardment-induced defects in the vicinity of the ion implantation profile and they are also trapped, most likely by residual boron impurities, during diffusion into the bulk. An effective diffusion coefficient, reflecting the dissociation of trapped lithium, with an activation energy of 2.1 eV is extracted for lithium diffusion in p-type 6H SIG. Furthermore, a capture radius for trapping (most likely by boron) of deuterium is estimated as 10 Angstrom. (C) 1999 Elsevier Science S.A. All rights reserved., 2nd European Conference on Silicon Carbide and Related Materials (ECSCRM 98), MONTPELLIER, FRANCE, SEP 02-04, 1998 NR 20140805

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NR 20140805

This paper describes a technique called producer-push that enhances the performance of a page-based software distributed shared memory system. Shared data, in software DSM systems, must normally be requested from the node that produced the latest value. Producer-push utilizes the execution history to predict this communication so that the data is pushed to the consumer before it is requested. In contrast to previously proposed mechanisms to proactively send data to where it is needed, producer-push uses information about the source code location of communication to more accurately predict the needed communication. Producer-push requires no source code modifications of the application and it effectively reduces the latency of shared memory accesses. This is confirmed by our performance evaluation which shows that the average time to wait for memory updates is reduced by 74%. Producer-push also changes the communication pattern of an application making it more suitable for modern networks. The latter is a result of a 44% reduction of the average number of messages and an enlargement of the average message size by 65%., QCR 20160527