Decision Tree Induction Based on Efficient Tree Restructuring

The ability to restructure a decision tree efficiently enables a variety of approaches to decision tree induction that would otherwise be prohibitively expensive. Two such approaches are described here, one being incremental tree induction (ITI), and the other being non-incremental tree induction using a measure of tree quality instead of test quality (DMTI). These approaches and several variants offer new computational and classifier characteristics that lend themselves to particular applications.     

Determination of the michaelis-menten constant for beta-hydroxy-beta-methylglutaryl coenzyme A reductase. Demonstration of a substrate affinity 10-fold greater than previously reported

This paper presents evidence that earlier kinetic determinations of rat liver beta-hydroxy-beta-methylglutaryl coenzyme A (HMG-CoA) reductase, the reported rate-determining enzyme in cholesterol biogenesis, may have substantially underestimated the affinity of this enzyme for HMG-CoA. Nonlinear conversion of this substrate to mevalonic acid, with time, is shown under the conditions of a previous study, and it was concluded that velocities were limited at the lower substrate levels tested by an insufficient quantity of substrate. For this present study, conditions were established under which linearity of time versus product formation was observed, and the extent of conversion did not exceed 6% of the initial quantity of D isomer. These conditions gave a Michaelis-Menten constant of 1.01 +/- 0.12 muM for the D isomer, which is 3.5 to 40 times lower than those previously reported.     

A simplified surgical approach to the incomplete form of testicular feminization

A simplified surgical approach to the intersex child with the incomplete form of testicular feminization is presented. The procedure is particularly useful in patients where the gonadal tissue is located in the scrotolabial folds and eliminates the necessity for exploratory laparotomy. Representative drawings of the procedure are shown.     

Impermeant maleimides. Identification of an exofacial component of the human erythrocyte hexose transport mechanism

The facilitated diffusion of D-glucose across human erythrocyte membranes requires an exofacial (outer surface) sulfhydryl group which can be alkylated by the impermeant reagents glutathione-maleimide and dextran-maleimide. The irreversible inhibition produced by these reagents is asymmetric; inhibition of glucose efflux considerably exceeds that of influx when transport is assayed in the absence of glucose on the opposite side of the membrane. Both D-glucose and cytochalasin B protect the exofacial transport site from alkylation by the impermeant maleimides. This masking effect provides the basis for a two-step procedure for differential labeling of the outer transport site with radioactive glutathione-maleimide. The method labels clearly and consistently a component of the membrane proteins which migrates in sodium dodecyl sulfate-polyacrylamide gels between Coomassie brilliant blue-stained Bands 4.2 and 5, corresponding to an apparent molecular weight of 65,000 to 70,000. Transport studies after inhibition with N-ethylmaleimide suggest that the hexose mechanism also requires a second sulfhydryl group which is not accessible at the cell surface.     

Embolic pulmonary aneurysms in yearling feedlot cattle

Throughout all of 1974, we surveyed, for illnesses and deaths, about 407,000 yearling feedlot cattle. Of 1,988 cattle necropsied, 25 (1.3%) had ruptured pulmonary aneurysms and an additional 4 had gross pulmonary emboli without rupture. The emboli originated from thrombi in the caudal vena cava where that vessel closely applies to the left border of the liver and where parenchymal abscesses had developed. The emboli had lodged in the pulmonary artery, weakened its wall, and led to saccular aneurysms. Infection weakened and blood pressure ruptured the saccule and opened the adjacent bronchi. Extravasated blood dissected the tunica adventitia, formed hematomas, poured into the bronchus, and was expelled from the larynx. A portion was swallowed into the rumen, and some was coughed and blown from the nose and mouth. Deaths were attributed to exsanguination and pulmonary incapacitation.     

Diseases of yearling feedlot cattle in Colorado

During all of 1974 we surveyed, for illnesses and deaths, about 407,000 yearling feedlot cattle. The morbidity was 5.1%, with a case mortality of 18.9% and a population mortality of 1.0%. Both morbidity and mortality were higher during fall and winter than during spring and summer. Of the 3,943 dead cattle, 1,988 were necropsied. The most prevalent diseases were: pneumonia, 48%; diphtheria, 6%; brisket disease, 6%; hemorrhagic colitis, 5%; riding injury, 4%; bloat, 3%; calculosis, 2%; endocarditis, 2%; abomasal ulcers, 2%; bovine viral diarrhea, 2%; embolic pulmonary aneurysm, 1%; and pulmonary edema, 1%.     

Integrated concentrations of luteinizing hormone and puberty

Integrated serum concentrations of luteinizing hormone have been compared among 30-minute collections from 10 boys (6-18 years old) and 5 girls (5-11 years old). This study suggests that perpubertal as well as pubertal boys have greater mean integrated concentrations of LH during sleep than during waking. One of two pubertal girls had greater concentrations of LH during sleep, while three prepubertal girls did not.     

Lack of reliability of the SISI procedure for determining inner ear threshold

Ten normally hearing subjects were tested using the conductive short increment sensitivity index procedure to evaluate the 60-dB constant as used in the test described by Byers (1974). Also investigated were the effects of frequency and order of presentation on the short increment sensitivity index at high sensation levels. Test frequencies included 1, 2, 4, and 6 kHz in random order. Means of all frequencies exceeded the 60-dB constant implemented by Byers (1974). Intersubject variability was large. Frequency and order of presentation were not statistically significant factors. It was recommended that the conductive short increment sensitivity index be used with caution.     

Reproductive performance and fertility testing in strain 13 and Hartley guinea pigs

A study to test the effects of certain experimental manipulation on the reproductive capacity of male guinea pigs required verifying the fertility of the male guinea pigs before and after manipulation. Methods of testing fertility were evaluated, and normal reproductive data from preexperimental and control groups were tabulated and analyzed. No data from the actual experiments were included. Virgin and proven fertile males were mated with 1 (1:1) or 2 (2:1) virgin or proven fertile females. Inbred (13/N Umm) and conventional (Mfi:CFDH-ML (DH) ) guinea pigs were used. Ninety-five percent of both groups of males were fertile. Eighty-four percent of both groups of females were fertile. Male guinea pigs previously proven fertile had the same subsequent fertility rate as virgin males. Over one-third of the conceptions did not take place during the first estrus cycle (16 da) during which the males and females were mated. Strain 13 and Hartley females had litters of approximately the same size (3.1 vs 3.0), but the neonatal mortality was statistically lower (P less than 0.001) in the Hartley stock (9.3%) than in the Strain 13 guinea pigs (28.4%).