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A fiber distributed data interface (FDDI) standard is being developed in the Accredited Standards Committee (ASC) X3T9. This standard is for a 100 MB/s dual fiber (counter-rotating) ring. Stations on the ring are interconnected by optical fibers and provisions have been made to allow optional optical switches to bypass a station when needed.

The physiological conditions for the excretion of staphylococcal enterotoxin B (SEB) by nongrowing cells have been determined. In general, SEB excretion appears to be best when amino acids serve as sources of carbon, nitrogen, and energy. Little toxin was produced in a nitrogen-free medium with glucose as the sole carbon source. Inhibitor studies have shown that most of the toxin excreted by nongrowing cells was the result of de novo protein synthesis. Optimum toxin excretion was also obtained under conditions of aeration, and at or near optimum growth temperature, those conditions at which the cells are metabolically and biosynthetically most active. Levels of cell-associated SEB decreased during toxin excretion. However, these levels of toxin could not account for the high levels of toxin released during excretion. Glucose and several other rapidly fermentable carbohydrates inhibited toxin excretion by as much as 80% under conditions of uncontrolled decrease in pH; however, when the pH was kept at either 6.2 or 7.5 a stimulation of toxin excretion was observed. Protoplast studies have suggested that SEB production does not take place in the absence of an intact cell wall.

A rapid screening procedure was used to test the effect of 42 dyes on growth of 30 bacteria on solid media. The results indicated that many readily available dyes might have potential application for selective isolation of specific bacterial groups as well as value in differentiating between closely related bacterial taxa. Separation of Enterobacter from Escherichia, Salmonella from Shigella , and Staphylococcus from Micrococcus by selected dyes was also evaluated.

A minimal chemically defined medium has been developed for growth (approximately 25 Klett units) and production of detectable enterotoxin B (approximately 5-6 μg/ml) by Staphylococcus aureus S-6. This medium contains monosodium glutamate as a source of carbon, nitrogen, and energy, three additional amino acids (arginine, cystine, and phenylalanine), six inorganic salts, and four vitamins. Increasing the concentrations of several amino acids in a series of defined media gave no increase in enterotoxin production. Apparently the limiting factor for growth and enterotoxin production in these media is the biosynthesis of one or more missing amino acids, rather than the concentration of the amino acids present in the media. An additional requirement for proline and valine was observed when glucose was added as the primary source of energy. When compared to complex media, our results indicated that the inhibitory effect of glucose on enterotoxin synthesis in defined media was less evident or totally absent.

The utility of the multi-channel analysis of surface waves (MASW) seismic method for noninvasive assessment of earthen levees was evaluated for a section of the Citrus Lakefront Levee, New Orleans, Louisiana. This test was conducted after the New Orleans’ area levee system had been stressed by Hurricane Katrina in 2005. The MASW data were acquired in a seismically noisy, urban environment using an accelerated weight-drop seismic source and a towed seismic land streamer. Much of the seismic data were contaminated with higher-order mode guided-waves, requiring application of muting filtering techniques to improve interpretability of the dispersion curves. Comparison of shear-wave velocity sections with boring logs suggests the existence of four distinct horizontal layers within and beneath the levee: (1) the levee core, (2) the levee basal layer of fat clay, (3) a sublevel layer of silty sand, and (4) underlying Pleistocene deposits of sandy lean clay. Along the surveyed section of levee, lateral variations in shearwave velocity are interpreted as changes in material rigidity, suggestive of construction or geologic heterogeneity, or possibly, that dynamic processes (such as differential settlement) are affecting discrete levee areas. The results of this study suggest that the MASW method is a geophysical tool with significant potential for non-invasive characterization of vertical and horizontal variations in levee material shear strength. Additional work, however, is needed to fully understand and address the complex seismic wave propagation in levee structures.

A miniaturized method for performing IMViC tests is proposed. Twenty-four gram-negative bacterial species and strains were tested by use of miniaturized and conventional methods; the results were comparable. The miniaturized method effects saving of time, space, materials, and effort.

A rapid miniaturized procedure, with a Microtiter plate and the Amojell-overlay technique, is described for the detection of acid and gas production by bacterial cultures. Images

Shallow seismic-reflection surveys conducted near Borah Peak, Idaho, define subsurface structure across a segment of the Lost River fault that was reactivated in 1983. Four different seismic lines using different sets of recording parameters produced reflections from different depth ranges and at different resolutions. The combined interpretation shows the Lost River fault zone in the upper 50 m to be 180 m wide and to be composed of high-angle faults of various ages. The northeast edge of the Lost River fault is clearly defined at a depth of approximately 43±2 m. The dip of the fault plane in the upper 43±2 m is approximately 55° southwest with an uncertainty of 5°. The interpretation presented correlates with surface structure as well as with deeper geophysical data.

In 1938 more cases of measles were reported in Chicago than during any year since this disease was made reportable. Table 1 shows that apparently there has been no reduction in the number of cases of measles reported each year over the last twenty-five years. Rather the trend is toward more cases, probably because of better reporting. The mortality, however, has dropped rather steadily from 12.4 per hundred thousand of population in 1913 to 1.1 in 1938. It should be noted in table 1 that only the years of largest incidence are charted, one might say the epidemic years. In 1938 the case fatality was amazingly low, being 0.1 per cent, whereas in 1913 it was 1.9 per cent. However, during this year the case fatality was low over the entire country. Improved housing, more adequate medical care, better nursing attention, increased use of measles-modifying substances in susceptible contacts, recent

The presence of a thin layer embedded in any formation creates complex reflection patterns because of interferences within the thin bed. Amplitude variation with offset (AVO) is used increasingly in seismic interpretation and has been tested more recently on ground-penetrating radar (GPR) data to characterize nonaqueous-phase liquid contaminants. In those analyses, phase and dispersion properties of the reflected signals generally are omitted, although they contain useful information. An inversion methodology to examine thin-bed properties -- dispersive amplitude and phase versus offset (DAPVO) -- combines all reflectivity properties (amplitude, phase, and dispersion) of the reflected GPR signal generated by a thin bed embedded within a homogeneous material. A brief description of electromagnetic (EM) phenomena is presented. The dispersive properties of the dielectric permittivity of investigated materials can be described using a Jonscher parameterization, which allows the study of the dependency of amplitude and phase versus offset (APVO) curves on the frequency of thin-bed properties (filling nature, aperture). Simplifying assumptions and using careful corrections are necessary to convert raw common-midpoint (CMP) reflected data into DAPVO curves and to study the propagation and radiation-pattern corrections. The inversion methodology is explained and validated to a synthetic set of CMP GPR data and can be illustrated with a real CMP data set acquired along a vertical cliff. This allows for extraction of the characteristics of a subvertical fracture while simultaneously satisfying resolution and confidence. Such a study motivates interest in combining the dispersion dependency of the reflection-coefficient variations with classical AVO analysis for thin-bed characterization.