Perfect graphs and perfect 0,l matrices are well studied in the literature. Here we introduce perfect 0, f 1 matrices. Our main result is a characterization of these matrices in terms of a family of perfect 0,l matrices. 0 Elsevim Science Inc., 1997 * This work was supported in part by NSF grants DMI-9424348 and DMS-9509581, and by ONR grant NOOO14-89-J-1063. LINEAR ALGEBRA AND ITS APPLZCATIONS...

Cyanothece sp. strain ATCC 51142 is a unicellular, diazotrophic cyanobacterium which demonstrated extensive metabolic periodicities of photosynthesis, respiration, and nitrogen fixation when grown under N2-fixing conditions. N2 fixation and respiration peaked at 24-h intervals early in the dark or subjective-dark period, whereas photosynthesis was approximately 12 h out of phase and peaked towa...

The level of dark adaptation of the whirligig beetle can be measured in terms of the threshold intensity calling forth a response. The course of dark adaptation was determined at levels of light adaptation of 6.5, 91.6, and 6100 foot-candles. All data can be fitted by the same curve. This indicates that dark adaptation follows parts of the same course irrespective of the level of light adaptati...

The circadian variation of the toxicity and nociceptive actIvity of aminophylline as an important methylxanthine was studied in mice. The animals were housed under controlled light-dark cycles for at least 2 weeks. Acute toxicity was determined by LD50. Hot-plate test was used for determination of thermal pain threshold. Doses of 200, 250, 280 and 340 mg/kg of aminophylline were injected i...