Showing papers by "University of Costa Rica published in 1974"
TL;DR: A stratiform, massive copper sulfide deposit with possible gold, silver, and cobalt credits was discovered by a United Nations reconnaissance team in Paleozoic metamorphic terrain of north central Turkey, which contains evidence of extensive prehistoric underground mining and smelting activity.
Abstract: A stratiform, massive copper sulfide deposit with possible gold, silver, and cobalt credits was discovered by a United Nations reconnaissance team in Paleozoic (?) metamorphic terrain of north central Turkey. The deposit, which is of possible volcanigenic exhalative origin, contains evidence of extensive prehistoric underground mining and smelting activity that, based on radiocarbon data, may date to 2800 B.C. (Early Bronze I Age).
15 citations
12 citations
10 citations
TL;DR: In this paper, the Ritz method with relaxed coordinate functions is used to establish a minimizing sequence for an extended functional, where the integrand of the functional involves discontinuous functions, which implies that the gradient of the related extremal curve or surface also admits discontinuities.
10 citations
TL;DR: In the Western Hemisphere there are listed 61 species of black flies which are recorded as biting man in the Neotropical Region and 37 in the Nearctic Region and the greatest biting rates in Costa Rica were at altitudes of 0 to 1500 m.
Abstract: In the Western Hemisphere there are listed 61 species of black flies which are recorded as biting man in the Neotropical Region and 37 in the Nearctic Region. Five neotropical species, Simulium quadrivittatum, S. metallicum, S. callidum, S. baematopotum and S. paynei, were collected while biting rates in Costa Rica. The greatest biting rates in Costa Rica were at altitudes of 0 to 1500 m.
7 citations
TL;DR: Observations in three Rhodnius prolixus infected thatch-roofed huts in the Departamento Francisco Morazan, Honduras, revealed that of their 22 inhabitants, 11 were positive serologically for Chagas’ disease, four of them with the Romana sign, and positive Trypanosoma cruzi hemoculture and xenodiagnosis.
Abstract: Observations in three Rhodnius prolixus infected thatch-roofed huts in the Departamento Francisco Morazan, Honduras, revealed that of their 22 inhabitants, 11 were positive serologically for Chagas’ disease, four of them with the Romana sign, and positive Trypanosoma cruzi hemoculture and xenodiagnosis. Another five persons (two serologically positive for Chagas' disease) were positive only for Trypanosoma rangeli in hemoculture, two of which were also positive for the same parasite by xenodiagnosis. Pure and mixed infections by both trypanosomes were found in 1230 R. prolixus captured in the three huts. In T. rangeli , examination of the feces, hemolymph and salivary glands is necessary to determine the number of infected insects. Precipitin tests showed the avidity of R. prolixus for biting man; one insect was found positive for human and opossum blood concomitantly.
4 citations
3 citations