SummaryAn analysis of the distribution of light within some culture vessels developed at. General Dynamics/Electric Boat is presented. The concept of a mean effective light intensity, E, is introduced and procedures are developed for computing i ?for any culture vessel geometry and incident light intensity distribution. A correlation is performed indicating the significance of E in assessing the growth rate of dense, continuous cultures of microalagae.

Throughout much of the northern Chihuahuan Desert, the grasslands that were widespread at the time of European settlement have been replaced by desert shrublands. Little is known about the effects of this change on avian communities. We analyzed historic U.S. Government Land Office records to assess large‐scale changes in vegetation cover from the 1880s to the present day. We studied vegetation and avian communities in one grassland habitat type and four desert shrubland habitat types to examine (1) how breeding‐bird communities may have changed in response to habitat conversion from grassland to desert shrubland and (2) whether breeding‐bird communities differ among the four desert shrubland habitat types that compose Chihuahuan Desert scrub in this region. To estimate the characteristics of 1880s black grama (   Bouteloua eriopoda) grassland, we focused on plots located within extensive patches of present‐day black grama and compared the avian communities found there with those in desert shrubland. Species richness was higher in desert shrubland than grassland. Among the desert shrubland habitat types, species richness was consistently highest in mesquite. Avian abundance patterns differed among the four desert shrubland habitat types. At least 30% of the avian community in each habitat pair was distinct. Conversion of grassland to shrubland in south‐central New Mexico has likely been accompanied by a major turnover in the avian community. Remaining tracts of black grama provide habitat for species that may be uniquely adapted to the northern Chihuahuan Desert and should be protected.

The cobalt, copper, and iron contents of a vertical series of water samples from Linsley Pond are given. Cobalt and iron are higher in the hypolimnion than in the epilimnion, but copper is not, The cobalt and iron content of the seston is estimated to be about equal to the content in normal soils, but the copper content is much higher. Vitamin B12 only exists in the water at concentrations lower than the optimum for some algae in culture. The proportion of the total cobalt tied up in vitamin B12 in the epilimnion is about 10% and about 4% or less in the hypolimnion.

The demographic and job satisfaction characteristics of Florida community college faculty were studied in Florida's 28 community colleges. A total of 1,116 faculty responded in the fall of 1977 to an instrument developed to measure faculty characteristics and attitudes. The results showed that the Florida faculty is a satisfied faculty with over 95% reporting that they were satisfied with community college work as a career and with 72% stating that they plan to stay in the community college field until they retire. Second, it was found that faculty participation in in-service training programs had increased significantly since 1968. In 1977-1978, 69% of the faculty reported participation in one or more inservice programs while the 1968 percentage was 37%.It is concluded that periodic surveys in other community colleges and states similar to this one should provide useful information for the further development and improvement of community colleges.

Engineering data on the design and operation of algal culture systems for photosynthetic gas exchange are virtually non‐existent. The authors have conducted intermediate and definitive level engineering studies to characterize algal systems—with a view to extrapolating to larger‐scale systems for life support in closed spaces. Light intensity, carbon dioxide concentration, and dilution rate were the principal parameters used to control the photosynthetic rate and, consequently, oxygen production. Carbon dioxide absorption rate, equilibrium density, and cellular growth rate were also investigated. It was found that: (1) properly jacketed high intensity, incandescent lamps provided a suitable light source for growing algae; and (2) physiologically safe (0·5 per cent) concentrations of carbon dioxide produced growth comparable to that obtained at higher concentrations. A dilution rate of nearly 0·1 volume change per hour produced the best oxygen yield (2·41 × 10−3 lb/h) for the definitive system. Maximum cell doubling time was 5·1 h. The highest culture density attained was 5·9 mm3/ml, and the maximum dry weight algae yield was 3·0 × 10−3 lb/h.