Mathematical biology of learning to drive an automobile

In learning to drive, an individual must learn to rapidly make small corrective turns to the right or to the left as the car comes too close correspondingly to the left or to the right edges of the lane. The magnitude of the corrective turn depends on the angle at which the edge is approached. Thus, the individual must learn to produce a quantitatively correct response (corrective turn) to any one of an infinite number of possible stimuli (angles of approach). By making a number of highly oversimplifying assumptions, the problem can be reduced to a learning situation, studied previously by H. D. Landahl (Bull. Math. Biophysic,3, 13–26, 71–77, 1941). This is used not so much to obtain any relation that might be considered practically applicable immediately as toillustrate what kind of relation can be obtained from such considerations. It is shown how the safe speed of a driver depends on his total driving experience (total distance driven) as well as on his psychophysical parameters.     

Biodegradation of solvents in varnish waste water of an airscrubber from an automobile varnish shop

The scrubber liquid of an automobile varnish shop, where varnish particle, pigments and resins are washed out, contains microorganisms, that are able to degrade the main compounds of the solvents in the waste gases, i.e. n-butanol, ethylbenzene and structural isomers of xylene, ethyltoluene and trimethylbenzene. The concentration of the compounds in the varnish waste water to be purified oscillated between 1000 and 1 ppm. The specific degradation efficiency could be increased 4 to 12 times by improvement in oxygen supply.A further enhancement was achieved by continuous addition of organic solvents in the gas phase. During the cultivation the number of different microorganisms of the mixed culture in the scrubber liquid was reduced. The biological system was also very stable and not sensitive to fluctuation in the solvent supply. Differences in the degradation capacity of structural isomers take place at the same concentration of aromatic hydrocarbons. The elimination of 2- or 4-ethyltoluene and 1,3,5- or 1,2,3-trimethylbenzene were 10 to 25% lower than 3-ethyltoluene or 1,2,4-trimethylbenzene.     

Beclomethasone dipropionate in asthma.

Beclomethasone dipropionate aerosol therapy can replace or diminish systemic corticosteroid therapy in the majority of asthmatics. In a clinical trial of 41 patients with perennial asthma, the 10 who had not required long-term corticosteroid therapy improved symptomatically and in pulmonary function. Of the 31 who had required prolonged systemic corticosteroid therapy 12 were able to discontinue oral prednisone therapy, 15 were able to decrease the maintenance dose of prednisone and only 4 were unable to decrease the dose; all maintained satisfactory lung function and some showed improvement. Discontinuation of systemic corticosteroid therapy was accomplished more readily in patients whose daily maintenance dose was less than 15 mg and who had been taking the drug for less than 3 years. Side effects consisted of a "dry throat" in seven patients, two of whom had throat infections with Candida albicans. Recurrence of rhinitis after discontinuation or reduction of systemic corticosteroid therapy was noted in 11 patients.     

Strategies in managing asthma.

The management of adult asthma involves a concerted effort to identify and remove or mollify inciting or triggering stimuli such as respiratory tract infections, gastric reflux, aspirin, beta-antagonists, and environmental agents; educate patients, using written treatment plans and pulmonary function monitoring; and properly use the antiasthmatic medications including beta-agonists, theophylline, anticholinergics, and corticosteroids, with an emphasis on aerosol delivery and the use of corticosteroids during exacerbations. This strategy is summarized with suggestions on therapy in emergency departments, during the transition from hospital to ambulatory care, before exercise, and during pregnancy.     

Ketotifen in adult asthma.

The efficacy and adverse effects of ketotifen 1 mg twice daily and 2 mg twice daily were compared with placebo in 50 patients with atopic asthma in a multicentre, double-blind study. Ketotifen in the higher dosage caused a slight reduction in salbutamol usage and a modest improvement in breathing in patients not already receiving inhaled corticosteroids. The drug was ineffective in patients receiving inhaled corticosteroids. Drowsiness was a troublesome effect causing withdrawal from treatment or reduction of dosage in seven patients while receiving ketotifen compared with only three while receiving placebo.