PubMed Health⌕ Search

Biomedical subjects

J G Robinson

Publications and source records attributed to J G Robinson.

17 recordsLinked to original sources
PubMed1990

Variability and adaptability in the genus Cebus.

Capuchins (Cebus) present an array of similarities to humans and apes in morphology, behavior and life history which raise a host of questions about the relations of these features to each other and about their evolutionary origins. As a genus and as individuals, capuchins possess marked adaptability and great variability in behavior. These two characteristics contribute directly to the biological success of capuchins. Variability and adaptability are also hallmarks of human behavior.

Animals↗
PubMed1990

Infanticide in wedge-capped capuchin monkeys, Cebus olivaceus.

Three cases of infanticide are reported from a well-studied population of wedge-capped capuchin monkeys, Cebus olivaceus, located in the Venezuelan llanos. For each case, we examined the social context and the consequences to the reproductive success of the infanticidal male. In 1 case, the male probably killed his own son. In 2 cases, the male killed an unrelated animal. In all 3 cases, the female conceived in the following breeding season, but in only 1 case did the infanticidal male possibly enhance his own reproductive success. These data are interpreted in the light of current hypotheses for infanticide.

Aggression↗
PubMed1989

Comparison of high-dose with low-dose subcutaneous heparin to prevent left ventricular mural thrombosis in patients with acute transmural anterior myocardial infarction.

We performed a double-blind randomized trial comparing high doses of subcutaneous heparin (12,500 units every 12 hours) with low doses (5000 units every 12 hours) for 10 days in the prevention of left ventricular mural thrombosis in 221 patients with acute anterior myocardial infarction. Left ventricular mural thrombosis was observed by two-dimensional echocardiography on the 10th day after infarction in 10 of 95 patients (11 percent) in the high-dose group and in 28 of 88 patients (32 percent) in the low-dose group (P = 0.0004). One patient in the high-dose group and four in the low-dose group had nonhemorrhagic strokes (P = 0.17). One patient in the low-dose group had a fatal pulmonary embolism. There was no difference in the frequency of hemorrhagic complications, which occurred in six patients in the high-dose group and four in the low-dose group. The mean (+/- SEM) plasma heparin concentration was 0.18 +/- 0.017 U per milliliter in the high-dose group and 0.01 +/- 0.005 U per milliliter in the low-dose group (P less than 0.0001). In the high-dose group, the mean plasma heparin concentration was 0.10 +/- 0.029 U per milliliter among patients with abnormal two-dimensional echocardiograms, as compared with 0.19 +/- 0.019 U per milliliter among patients with normal echocardiograms (P = 0.01). We conclude that heparin administered subcutaneously in a dosage of 12,500 units every 12 hours to patients with acute anterior transmural myocardial infarction is more effective than a lower dosage (5000 units every 12 hours) in preventing left ventricular mural thrombosis.

Aged↗
PubMed1989

Seasonal or ecological differences in diet and molar microwear in Cebus nigrivittatus.

Dental microwear analyses have raised new hopes and questions for functional morphologists. One hope is that analyses will allow insights into subtle dietary differences of extinct species. One major question is whether seasonal and/or habitat differences in dental microwear are reliably detectable. The extensive collections of Cebus nigrivittatus obtained by the Smithsonian Venezuelan Project allowed us to examine seasonal and habitat differences in dental microwear. Specimens were collected from three distinct ecological life zones that are distinguished by both the amount of rainfall and its seasonability. Environmental variation is generally correlated with variation in resource availability which, in C. nigrivittatus, affects diet. Published field studies indicate that these animals depend more on dry hard fruit and chitinous invertebrates during drier times and succulent fruits and caterpillars during wetter times of the year. As in previous microwear analyses, epoxy replicas were prepared from dental impressions, and the replicas were examined under a scanning electron microscope. Two micrographs were taken of facet 9 on M2 of each specimen. Mean values for the proportion of pits (vs. scratches), pit width, and scratch width were computed for each of 62 individuals and compared between ecological zones and collecting dates by using a multiple comparison test. Results indicate that, while seasonal differences in molar microwear in C. nigrivittatus are perhaps reliably detectable, 1) they are small in magnitude, 2) they are only detectable in certain ecological life zones, and 3) they are not of the order of magnitude that will obscure major interspecific differences in molar microwear such as those between C. apella and C. nigrivittatus.

Analysis of Variance↗
PubMed1983

Intergroup loud calls, range size, and spacing in Callicebus torquatus.

Observations are reported on the response of a free-ranging group of Callicebus torquatus to recordings of loud intergroup calls. When the recording consisted of the call of a solo adult male, the group fled from the recording. When the recording consisted of the adult male and female duetting together, the group remained in place and called back to the recording. These results contrast with previously described vocal and spatial responses of C. moloch and suggest that range size influences the mechanisms that regulate between-group spacing. The consequence of intergroup loud calls in C. moloch is to define and reinforce the location of boundaries, whereas in C. torquatus, homologous calls maintain spacing between groups.

Animals↗
PubMed1980

Estimating the approximate size of the illegal alien population in the United States by the comparative trend analysis of age-specific death rates.

This paper presents the results of an attempt to determine, through the use of demographic analysis, the approximate magnitude of the resident illegal alien population in the United States. The method described is the comparative analysis of trends in age-specific death rates in the United States and selected States, 1950 to 1975. The procedure depends on two assumptions: (a) that few or no illegal aliens are included in decennial census counts or current population estimates; and (b) that the reported statistics on deaths include deaths to all or nearly all illegal aliens. If the illegal alien population has increased by several million since 1970, then death rates in geographic areas where illegal aliens are most concentrated should show substantial excesses over the rates for the remainder of the country. A roughly similar downward trend in the death rates of all age groups since 1970 in all areas of the United States is apparent and hence does not support the view that many millions of illegal residents (perhaps over 6 million) are living here. However, the finding of a persistent deviation in the death rate trend for 10 selected States since 1960 for whites males, ages 20 to 44, and for no other group, suggests that the deaths of illegal aliens are being recorded in our vital statistics system. A range of estimates of the illegal alien population based on this analysis is presented and compared with the results of other studies.

Adolescent↗
PubMed1979

An analysis of the organization of vocal communication in the titi monkey Callicebus moloch.

Vocalizations of titi monkeys were recorded from 6 groups at two sites in the Ilanos of Colombia during 8 months of study. Frequency and temporal measurements from spectrograms of recordings, and differences in their patterns of use, were used to characterize call types. Animals repeat calls to form phrases, and combine phrases to form sequences. The six sequence types, defined by different transition probabilities between phrases, varied in proportion in different contexts. To examine the effect of order of phrases on response, I played back artificially constructed sequences to subject groups. I discuss hierarchical and sequential mechanisms as generators of vocal sequences, and draw comparisons with models of human language.

Animal Communication↗