Pattern-directed invocation with changing equations

Pattern-directed invocation is a commonly used artifical-intelligence reasoning technique in which a procedure, called a demon, is automatically invoked whenever a term matching its pattern appears in a ground data base. For completeness, if the data base includes equations, a demon needs to be invoked not only when a term in the data base exactly matches its pattern, but also when some variant of a term in the data base matches. An incremental algorithm has been developed for invoking demons in this situation without generating all possible variants of terms in the data base. The algorithm is shown to be complete for a class of demons, called transparent demons, that obey a natural restriction between the pattern and the body of the demon. Completeness is maintained when new demons, terms, or equations are added to the data base in any order. Equations can also be retracted via a truth maintenance system. The algorithm has been implemented as part of a reasoning system called bread.     

The effect of measuring geometry on computer color matching

The debate over the best optical geometry for color measurement dates back to the development of the first recording reflectance spectrophotometer. It is hypothesized that a bidirectional geometry conforms best to the procedure used to inspect colored surface samples visually. This hypothesis was tested using two spectrophotometers of nearly identical design, one utilizing d/8 geometry and the other utilizing 0/45 geometry. The results indicate that bidirectional geometry may be superior to integrating-sphere geometry when matching standards with varying gloss. The bidirectional measurements are quite sensitive to the size of the source and the detector-aperture half angle.     

Extreme self-medication: a case report

On the background of insufficient allergological diagnostic a case of serious cowhair asthma was misinterpreted as intrinsic asthma which led to an extreme form of selfmedication. The excessive daily intravenous selfapplication of 2000 mg theophylline and 24 mg fenoterol per inhalationem for about 4 years was tolerated without any serious side effects. The continues smoking of 40 cigarettes per day may have protected the patient from a toxic dose of theophylline. This case report demonstrates the importance of basic diagnostic as well as the continuous control of the proposed medication.     

Noninvasive electrodes for electrocochleography in the chinchilla

This study compares noninvasive vs invasive electrodes for electrocochleography in chinchillas. Summating potential (SP) amplitude, action potential (AP) amplitude, and AP threshold, recorded with five types of noninvasive electrodes, were compared with simultaneous bulla recordings. Noninvasive electrodes included a needle electrode over the bulla, gold Tiptrode (Etymotic Research, Elk Grove Village, Ill), Enhancer I (Nicolet Instrument Corp, Madison, Wis), Coats (Lifetech Inc, Austin, Tex) electrode, and a locally constructed tympanic membrane (TM) electrode. Stimuli included 100-microsecond clicks and 6000-Hz tone bursts (with a 1 millisecond rise/fall time and a 5 millisecond plateau). Stimuli were initially presented at 110 dB peak equivalent sound pressure level for the clicks and 100 dB peak equivalent sound pressure level for the tone bursts. Intensity was then decreased in 10-dB decrements until no replicable AP activity was observed. The TM damping for the TM electrode was measured with 0.5, 1, 2, 4, and 6 kHz and click stimuli. The AP was clear and replicable for all electrodes used in the study, although the amplitude was substantially less for the noninvasive electrodes as opposed to the invasive electrode. The invasive electrode provided the largest amplitude SP recording, but SP could generally be clearly recorded with the needle electrode, Enhancer I, and the Coats electrode. The TM electrode and gold Tiptrode provided SP recordings less consistently. The AP threshold could be recorded with all the electrodes in the study and was generally within 10 dB of threshold recorded invasively. Electrode variables, including ease of electrode placement and potential injury, were examined. The Tiptrode and Enhancer I electrodes posed relatively few problems during placement.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of debt level on the residency preferences of graduating medical students

BACKGROUND: The increased educational indebtedness of graduating medical students has led to speculation about the effects of students' debt levels on their choices of practice specialties as evidenced by their residency preferences. METHOD: Information was analyzed for 1,658 medical students who graduated from six private medical schools in 1988, 1989, and 1990; 1,431 of these students had educational debts. Chi-square analysis was used to compare the 1,431 students' average levels of indebtedness with their selections of residencies leading to specialties with higher or lower potential incomes. For this analysis, the students were grouped into four clusters based on the potential incomes of their specialty preferences. In addition, various subgroups, i.e., men, women, need-based scholarship recipients, and underrepresented-minority students, were also studied. RESULTS: For all the students, there was no relationship among their average levels of indebtedness and their specialty preferences. Similar results were obtained for all the subgroups--men, women, underrepresented-minority students, and scholarship recipients. However, the women students tended to have higher levels of indebtedness than the men. CONCLUSION: The results do not support the hypothesis that debt level is a determining factor among the variables that influence choices of residency by graduating medical students.