CCD Charge-Coupled Device Memories: A Perspective

CCD memories can fill the gap between RAMs and disks. If cost-effective, they will tend to be used in high-end, high-performance computers.     

Assessing urinary levoglucosan and methoxyphenols as biomarkers for use in woodsmoke exposure studies

A major contributor to particle concentrations in urban airsheds is domestic woodsmoke and smoke arising from wildfires or management burns. Particle concentrations in urban airsheds have been associated with a wide range of health effects. There has been little research into the contribution of biomass burning to studies of human health due to the complexity of attributing effects in the presence of multiple sources of pollutants and the variability in the nature and conditions of biomass burning. A significant advance is the use of biomarkers of exposure; methoxyphenol and levoglucosan; specific compounds produced following the combustion of lignins and detected in urine. Levoglucosan has not previously been assessed for its usefulness as a marker of human exposure. We report for the first time levoglucosan concentrations in urine. Twelve participants were recruited and asked to provide spot urine samples pre- and post-exposure to a fire training exercise. Both levoglucosan and methoxyphenol were detected in the urine of participants. There was no significant increase in these compounds post-exposure to smoke arising from the fire training. Further work is required to assess this biomarker for human exposure studies and in particular the role of diet and previous exposure.     

Buckling of simply supported rectangular plates under combined bending and compression using eigensensitivity analysis

In this paper, an approximate quadratic closed-form expression is presented for the critical buckling analysis of a plate subjected to combined bending and compression. The formula is developed by expanding the eigenvalue, the critical buckling load, for a plate under combined bending and compression in a Mauclaurin's series about a plate subjected only to compression. The general expression can be used for all combinations of simply supported and clamped rectangular plates boundary conditions. An explicit formula in terms of the plate aspect ratio R and plate load parameter α is evaluated for simply supported plates. Compared with the Rayleigh–Ritz method, this approximate expression provides an excellent comparison when the load parameter α1.52 for plate aspect ratio between 0.2R2.8.     

Parallel optical coherence tomography system

We present the design and procedures for implementing a parallel optical coherence tomography (POCT) imaging system that can be adapted to an endoscopic format. The POCT system consists of a single mode fiber (SMF) array with multiple reduced diameter (15 microm) SMFs in the sample arm with 15 microm center spacing between fibers. The size of the array determines the size of the transverse imaging field. Electronic scanning eliminates the need for mechanically scanning in the lateral direction. Experimental image data obtained with this system show the capability for parallel axial scan acquisition with lateral resolution comparable to mechanically scanned optical coherence tomography systems.     

Near-infrared analysis of ground barley for use as a feedstock for fuel ethanol production

The objective of this study was to explore the potential of near-infrared spectroscopy for determining the compositional quality properties of barley as a feedstock for fuel ethanol production and to compare the prediction accuracy between calibration models obtained using a Fourier transform near-infrared system (FT-NIR) and a dispersive near-infrared system. The total sample set contained 206 samples of three types of barley, hull-less, malt, and hulled varieties, which were grown at various locations in the eastern U.S. from 2002 to 2005 years. A new hull-less barley variety, Doyce, which was specially bred for potential use in ethanol production, was included in the sample set. One hundred and thirty-eight barley samples were used for calibration and sixty-eight were used for validation. Ground barley samples were scanned on both a FTNIR spectrometer (10 000 to 4000 cm(-1) at 4 cm(-1) resolution) and a dispersive NIR spectrometer (400 to 2498 nm at 10 nm resolution), respectively. Six grain components, moisture, starch, beta-glucan, protein, oil, and ash content, were analyzed as parameters of barley quality. Principal component analysis showed that barley samples could be classified by their types: hull-less, malt, and hulled. Partial least squares regression indicated that both FT-NIR and dispersive NIR spectroscopy have the potential to determine quality properties of barley with an acceptable accuracy, except for beta-glucan content. There was no predictive advantage in using a high-resolution FT-NIR instrument over a dispersive system for most components of barley.     

Transfer of near-infrared calibration model for determining fiber content in flax: effects of transfer samples and standardization procedure

The transfer of a calibration model for determining fiber content in flax stem was accomplished between two near-infrared spectrometers, which are the same brand but which require a standardization. In this paper, three factors, including transfer sample set, spectral type, and standardization method, were investigated to obtain the best standardization result. Twelve standardization files were produced from two sets of the transfer sample (sealed reference standards and a subset of the prediction set), two types of the transfer sample spectra (raw and preprocessed spectra), and three standardization methods (direct standardization (DS), piecewise direct standardization (PDS), and double window piecewise direct standardization (DWPDS)). The efficacy of the model transfer was evaluated based on the root mean square error of prediction, calculated using the independent prediction samples. Results indicated that the standardization using the sealed reference standards was unacceptable, but the standardization using the prediction subset was adequate. The use of the preprocessed spectra of the transfer samples led to the calibration transfers that were successful, especially for the PDS and the DWPDS correction. Finally, standardization using the prediction subset and their preprocessed spectra with DWPDS correction proved to be the best method for transferring the model.     

Using statistical models to identify factors that have a role in defining the abundance of ions produced by tandem MS

A database of 5448 peptide tandem mass spectra acquired in a quadrupole time-of-flight mass spectrometer was generated for peptides derived from proteins digested with trypsin. Peptides were identified from their mass spectra by the Mascot algorithm. Statistical models were then used to investigate factors influencing the abundance of ions formed. Separate models were formulated for b and y ions as it was thought that different factors may influence the formation of each type of ion. Several factors were found to have a highly significant influence on the abundance of ions formed. These include the actual mass of the ion formed after fragmentation as well as the location of the cleavage. The composition of the fragmenting peptide was also found to be important, and amino acids either side of the fragmentation site influenced the abundance of ions produced. To increase understanding of fragmentation mechanisms, the effect of several physicochemical properties of these residues was also investigated in a separate model. In conclusion, the models formulated for b and y ions provide useful characterization of the abundance of ions formed, and this information could be used to develop improved algorithms for peptide identification.