Biomedical subjects

D Olvera

Publications and source records attributed to D Olvera.

3 recordsLinked to original sources

PubMed1997

Pneumoperitoneum: its alternatives.

The purpose of this study was to determine the advantages and disadvantages of several techniques for performing the pneumoperitoneum. We studied 75 patients divided into three groups of 25 each. In the first group, we used the Veress needle technique in the umbilicus. In the second group, the insertion was in the upper left quadrant, and in the third group the insertion was direct with a disposable trocar in the umbilicus without pneumoperitoneum. In the first group, we made 32 attempts, and the time varied from 8 to 35 min. In the second group we made 28 attempts and the time was from 3 to 6 min. In both we had complications. In the third group, we made 25 direct insertions without complications, and the time was from 45 s to 3 min.

Adolescent↗

PubMed1975

The measurement of sharing and cooperation as equity effects and some relationships between them.

The initial objective was to determine whether an increase in cooperative responses (minimal cooperation) was also accompanied by an increase in the degree of correspondence in the number of reinforcers of the two subjects (maximal cooperation). Correct matching-to-sample responses of seven pairs of male adolescents were reinforced with money. On each trial, a subject could (1) give the matching-to-sample problem to his coactor (give or cooperative responses), or (2) take the problem for himself (take responses). The first member of the pair to respond made the choice. Correspondence did increase under this procedure as compared to a baseline where problems were distributed randomly. However, the increased correspondence usually resulted from take responses rather than cooperative give responses. This equitable method of problem distribution, designated as sharing, was characterized by the subjects alternately taking problems. The spacing of daily sessions may have been partly responsible for the high degree of correspondence, because correspondence did not increase within the usual number of sessions when the sessions were massed, i.e., all in one day. Daily sessions require cooperative responses, i.e., each subject has to show up each day for the other to earn money, and this dependency upon the coactor's behavior may facilitate some sharing or cooperation to ensure the coactor's attendance.

Journal Article↗

PubMed1975

Switching from competition to sharing or cooperation at large response requirements: competition requires more responding.

Two pairs of high-school students matched-to-sample for money. On each trial, a subject could either respond on one lever to take the matching-to-sample problem himself (taking response) or respond on a second lever to give the problem to his coactor (giving response). The first subject to complete the response requirement determined the distribution of the problem. Competition maximizes the amount of responding over trials, i.e., both subjects make taking responses on each trial. Sharing and cooperation minimize responding: only one subject makes a taking response (sharing) or a giving response (cooperation) on each trial, and the subjects alternate responding such that there is an equitable distribution of responses and reinforcers over trials. Large increases in the fixed-ratio response requirement to distribute problems produced: (1) a switch from competition to sharing or cooperation, (2) the expected concomitant change from inequitable to equitable distributions of reinforcers, and (3) a reduction in the amount of responding for three of the four subjects. Previous animal research has shown that large response requirements may have aversive properties. Switching from competition to sharing or cooperation at large response requirements allows a reduction in responding and, at the same time, a moderate number of reinforcers for each subject.

Journal Article↗