Biomedical subjects

N Abarca

Publications and source records attributed to N Abarca.

3 recordsLinked to original sources

PubMed2001

Human papillomavirus genotypes in rural Mozambique.

We studied the genotype distribution of cervical human papillomavirus (HPV) infections in an age-stratified sample of 262 women in Mozambique using the PGMYO9-PGMY11 primer system in a reverse line-blot strip-based assay with high sensitivity in type-specific amplification. Despite the low precision of the estimates, we found that HPV-16 was not the dominant type. Instead, HPV 35 was the most commonly identified genotype among HPV-positive women (16/96 [17%]) and women with cervical neoplasia (7/23 [30%]). Certain genotypes might have been under-detected in previous studies, and type-specific HPV distributions might vary across populations. Therefore, the estimated proportion of cervical neoplasia that could be prevented by an HPV-16-based vaccine could be lower than expected.

Adolescent↗

PubMed1990

Sex differences in aversive and appetitive conditioning in two strains of rats.

In order to examine sex differences in non sexual behavior, 40 rats of each sex from two strains (gray, A x C and albino, Sprague-Dawley) were trained, using different experimental procedures. In Experiment I, aversive conditioning in a one-way (easy task) and a two-way (difficult task) active avoidance task was examined. Results consistently showed that males of both strains were inferior to females in the acquisition of the two-way avoidance task. A significant interaction between sex of both strains and the difficulty of the task was found. In Experiment II, rats were trained in a Sutherland Apparatus in an easy (black vs. white) and a difficult (horizontal vs. vertical) visual discrimination task, using appetitive reinforcement; no differences between sexes were observed. A significant interaction, however, was found between strain and task, indicating a lower performance of the A x C strain in the difficult task. The results are discussed within the theoretical framework of the Yerkes-Dodson Law, which states a relationship between drive level, performance and different degrees of task difficulty.

Acoustic Stimulation↗

PubMed1982

Choice and foraging.

In Experiment 1, six naive pigeons were trained on a foraging schedule characterized by different states beginning with a search state in which completion of a fixed-interval on a white key led to a choice state. In the choice state the subject could, by appropriate responding on a fixed ratio of three, either accept or reject the schedule of reinforcement that was offered (either a variable-interval five-second or a variable-interval 20-second). If the subject accepted the schedule, it entered a "handling state" in which the appropriate variable-interval schedule was presented. Completion of the variable-interval schedule produced food. The independent variable was the fixed-interval value in the search state, and the dependent variable was the rate of acceptance of the long variable-interval in the choice state. Experiment 2 was identical except that the search state required completion of a variable-interval, instead of a fixed-interval, schedule. The rate of acceptance of the long variable-interval schedule in both experiments was a direct function of the length of the search state, in accordance with both optimality theory and the delay-reduction hypothesis.

Journal Article↗