The localization of sound sources with delay-and-sum (DAS) beamforming is limited by a poor spatial resolution-particularly at low frequencies. Various methods based on deconvolution are examined to improve the resolution of the beamforming map, which can be modeled by a convolution of the unknown acoustic source distribution and the beamformer's response to a point source, i.e., point-spread f...

The Hypocrealean epibiont of Baccharis coridifolia has been shown to synthesize de novo a series of macrocyclic trichothecene antibiotics, such as roridin A, roridin E, verrucarin A and verrucarin J. The structures of the compounds were determined by spectroscopic methods (1Hand 13C-NMR and FABMS).

Distortion product otoacoustic emissions (DPOAEs) recorded in the ear canal are a composite or vector sum of two underlying components. The relationship between hearing thresholds and DPOAE-component level, rather than composite level, has been of recent interest. Two different signal-processing methods, inverse fast Fourier transform (IFFT) with time-windowing and low-pass filtering, were used...

The fast Padé transform (FPT) is a method of spectral analysis that can be used to reconstruct nuclear magnetic resonance spectra from truncated free induction decay signals with superior robustness and spectral resolution compared with conventional Fourier analysis. The aim of this study is to show the utility of FPT in reducing of the scan time required for hyperpolarized 13C chemical shift i...

The aim of the present study was to compare polar lipids of yeast and mycelial forms of both Candida albicans and Candida dubliniensis. Cultures were harvested from Lee's medium after incubation at 37 degrees C for 48 h. Yeast and mycelial forms were washed, separated from one another, dried and lipids extracted and prepared for fast atom bombardment mass spectrometry analysis in the negative-i...

The technique of fast atom bombardment mass spectrometry has been shown to be capable of producing molecular weight and useful fragmentation information from a selection of penicilloic acids. In addition, the technique has been shown to give similar information on alkali metal salts of penicilloic acids.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) is one of themost fundamental analysis techniques for proteins, peptides, and synthetic polymers to date. Along with field desorption (FD), fast atom bombardment (FAB), laser desorption coupled with time-of-flight (LD-TOF), secondary ion mass spectrometry coupled with time-of-flight (SIMS-TOF), and electr...

Model adducts to be used in the identification of biologically formed adducts were synthesized by reaction of fjord-region dibenzo[a,l]pyrene 11,12-dihydrodiol 13,14-epoxides (DB[a,l]PDE) and deoxyadenosine (dA). The (+/-)-anti-DB[a,l]PDE was reacted with dA in dimethylformamide at 100 degrees C for 30 min to give four DB[a, l]PDE-14-N(6)dA adducts: (-)-anti-trans (26%), (+)-anti-trans (26%), (...

A rapid and sensitive method for assignment of disulfide bonds using fast atom bombardment mass spectrometry is described for hen egg white lysozyme and bovine ribonuclease A. The protein is initially digested to a mixture of peptides using chemical and enzymatic methods under conditions which minimize disulfide bond reduction and exchange. The digested sample is analyzed directly by fast atom ...