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Articles 1 - 7 of 7

Full-Text Articles in Life Sciences

Forest Gardens Of The Maya, David A. Bainbridge Jan 1988

Forest Gardens Of The Maya, David A. Bainbridge

David A Bainbridge

The lowland Maya supported very high populations in an area with limited water and soil. Much can be learned from studying their sophisticated management practices. Forest gardens and agroforestry helped provide key nutrients, materials, and inputs for improved soil.


A Model For Evaluating Time Constraints On Short-Term Reproductive Success In Altricial Birds1, Larry Clark Jan 1988

A Model For Evaluating Time Constraints On Short-Term Reproductive Success In Altricial Birds1, Larry Clark

Larry Clark

We develop a simple single dimension model incorporating the time and energy commitments of breeding altricial birds in an effort to understand the evolutionary constraints on parental care. We chose time as the dimension of preference, because it is a naturally bounded constraint, e.g., length of day or breeding season. The utility of the model was evaluated by comparing simulations of time allocation of various breeding scenarios for the European starling (Sturnus vulgaris) to field data. The structure of the model may prove useful in determining the evolutionary constraints on parental care imposed by the developmental pattern of chicks.


Effect Of Biologically Active Plants Used As Netst Material And The Derived Benefit To Starling Nestlings, Larry Clark, J. R. Mason Jan 1988

Effect Of Biologically Active Plants Used As Netst Material And The Derived Benefit To Starling Nestlings, Larry Clark, J. R. Mason

Larry Clark

The European starling Sturnus vulgaris preferentially incorporates fresh sprigs of particular plant species for use as nesting material. Chemicals found in these plants may act to reduce pathogen and ectoparasite populations normally found in nest environments. The present experiments were performed to test this Nest Protection Hypothesis. In the fild, we experimentally determined that wild carrot Daucus carota, a plant species preferred as nest material, effectively reduced the number of hematophagous mites found within nests relative to control nests without green vegetation. Chicks from nests containing wild carrot had higher levels of blood hemoglobin than chicks from control nests. However ...


Truncation Of Screwworm (Diptera: Calliphoridae) Development By Irradiation Of Embryos., David B. Taylor, Robert L. Mangan Jan 1988

Truncation Of Screwworm (Diptera: Calliphoridae) Development By Irradiation Of Embryos., David B. Taylor, Robert L. Mangan

David B Taylor

Gamma irradiation of screwworm, Cochliomyia hominivorax (Coquerel), embryos was used to truncate the life cycle at the prepupal stage. Egg hatch and larval survival were not reduced by dosages ≤8 kilorads (kr). Pupariation and adult emergence were inhibited by dosages ≥2.8 and 1.2 kr, respectively. Larvae, irradiated as embryos with dosages ≤8 kr, successfully infested wounded sheep, although larval weight was lower than normal. A dosage of 5.8 kr was sufficient to prevent pupariation, while permitting larval development to the third instar. Truncation of screwworm development permits the use of artificially wounded and infested animals for screwworm ...


A Pesquisa Urbana No Equador, Fernando Carrión Mena Jan 1988

A Pesquisa Urbana No Equador, Fernando Carrión Mena

Fernando Carrión Mena

É relativamente difícil precisar a origem cronológica de um campo ou área de conhecimento de um país determinado. Ainda mais se tem em conta que tanto a constituição teórica de um campo de conhecimento ultrapassa as fronteiras nacionais, como o objeto empírico de estudo é anterior a sua constitui9ao teórica. Isto é, precede-a e é uma condição necessária porém insuficiente. Para o nosso caso, este objeto é a "cidade", que historicamente existe no Equador, segundo algumas hipóteses desde á conquistam espanhola (Carrión, F. 1986); no entanto um pensamento relativamente consistente sobre ela recém se inicia quando o processo de urbanização ...


Photoperiod Effects On 2n Pollen Production, Response To Anther Culture, And Net Photosynthesis Of A Diplandrous Clone Of Solanum Phureja, Henry Owen, R. Veilleux, F. Haynes, K. Haynes Jan 1988

Photoperiod Effects On 2n Pollen Production, Response To Anther Culture, And Net Photosynthesis Of A Diplandrous Clone Of Solanum Phureja, Henry Owen, R. Veilleux, F. Haynes, K. Haynes

Henry R. Owen

Flow-cytometric analysis of pollen samples obtained from Solanum phureja, clone PP5, grown under 10, 14, and 18 hour photoperiods at the Southeastern Plant Environment Laboratories of North Carolina State University yielded two populations of pollen based on size parameters. These populations corresponded to pollen separation based on propidium iodide staining of DNA. Anther culture response from plants grown under 14 and 18 hour photo periods for 8, I 0, 12, and 14 weeks was greatest from 8 week old plants grown under a 14 hour photoperiod. Net photosynthesis was significantly higher for plants grown under a 10 hour photoperiod than ...


Genetic Distance And Hybridization Of Black Ducks And Mallards: A Morph Of A Different Color?, G. R. Hepp, James M. Novak, K. T. Scribner, P. W. Stangel Jan 1988

Genetic Distance And Hybridization Of Black Ducks And Mallards: A Morph Of A Different Color?, G. R. Hepp, James M. Novak, K. T. Scribner, P. W. Stangel

James M. Novak

No abstract provided.