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931.
932.
Renata Durães Bette A. Loiselle John G. Blake 《Behavioral ecology and sociobiology》2008,62(12):1947-1957
Leks, display grounds where males congregate and females visit to copulate, are typically traditional in location, despite
often high turnover of individual males. How leks can persist in face of male turnover is not well understood, in part due
to a lack of detailed field data allowing for a clear understanding of lek dynamics. We followed the fate of individual males
at 11 to 15 leks of the blue-crowned manakin Lepidothrix coronata across four breeding seasons to gain insights on how leks are formed and changed in space and time. Between years, leks were
traditional in location despite changes in territory ownership due to male disappearance and recruitment. New males were equally
likely to recruit by taking over existing territories or by establishing new territories. Recruitment was influenced by age,
as recruits were more likely to be adults than subadults. Lek size did not affect the probabilities of a male recruiting or
persisting at a territory, and vocalization rate, a correlate of mating success in this population, did not affect male persistence.
We used our field data to model changes in lek size and composition over longer periods of time (100 years) to understand
how lek traditionality can be reconciled with high male turnover. Our simulations showed that leks in our population rapidly
stabilize in size despite changes in territory ownership and that rates of male recruitment and disappearance compensate each
other, such that leks have the potential to persist for several decades after the original males have disappeared from them. 相似文献
933.
Malcolm Richard Gent Mario Menendez Javier Toraño Diego Isidro Susana Torno 《Waste management (New York, N.Y.)》2009,29(6):1819-1827
Cylindrical cyclone media separators using a suspended calcite separation media simulating industrial scale operations are demonstrated to effectively separate a wide variety of forms and a greater range of particle sizes of plastics by density than presently recycled. Purities of plastic products and recoveries obtained from mixed plastic wastes are comparable to those reported for established separations. Products of ≈100% purity with recoveries of >99% were obtained for high density fractions and >98% purities and recoveries for the low density fractions. Cyclonic centrifugal forces and/or the fine particle size of the separation media appear to minimize hydroscopic and particle shape effects.A mathematical model is proposed for defining plastic waste feed rates and treatable particle size ranges for the LARCODEMS media separator.Waste plastic separations yielded Ecart probable (Ep) values ?0.024 for a water only separation media. The Ep for 1.1 g cm?3 separation medias was <0.032 with minimal to no variation in values for 1–8 mm particle sizes. Variation in the quality of separations is shown to be minimal with <72 μm, <45 μm and <2 μm media particle sizes. Media density offset created varied according to particle size. 相似文献
934.
935.
936.
Increasing interest in biofuels trade between developed and developing countries has spurred worldwide discussions on issues such as subsidies and the ‘food for fuel’ crisis. One issue missing in recent discourse is the pressure exerted on developing countries to adopt large-scale mechanized farming practices to increase economic efficiencies. Such approaches often exclude small-scale farmers from participating in the emerging biofuels market, thus exacerbating poverty and social exclusion. Drawing on both qualitative and technical data, we discuss such pressures using Brazilian ethanol and biodiesel production. Pressure from international markets to become more economically efficient may contribute towards the erosion of recent schemes to encourage social benefits for small farmers in biodiesel production. We conclude with trade and policy implications. 相似文献
937.
938.
Maria Okumura Victor Bunduki Christina Shiang Regina Schultz Marcelo Zugaib 《黑龙江环境通报》2006,26(4):330-332
The classic sonographic appearance of the kidneys in fetuses with autosomal recessive polycystic kidney disease (ARPKD) has been well described. We report a case of enlarged kidneys with pyramidal hyperechogenicity quite similar to medullary nephrocalcinosis found in a fetus at 34 weeks' gestation. At 39 weeks, a female neonate was delivered and died after 22 h due to pulmonary insufficiency secondary to severe oligohydramnios. On pathological analysis, the gross and microscopic findings were typical of ARPKD with diffuse dilatation of tubules throughout. The fetal renal lobulation was prominent and on section, the pyramids were delineated within each lobule, accounting for the clear image of the pyramids observed on sonography. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
939.
Lino Tralhão João Coutinho-Rodrigues Luís Alçada-Almeida 《Waste management (New York, N.Y.)》2010,30(12):2418-2429
The location of multi-compartment sorted waste containers for recycling purposes in cities is an important problem in the context of urban waste management. The costs associated with those facilities and the impacts placed on populations are important concerns. This paper introduces a mixed-integer, multiobjective programming approach to identify the locations and capacities of such facilities. The approach incorporates an optimization model in a Geographical Information System (GIS)-based interactive decision support system that includes four objectives. The first objective minimizes the total investment cost; the second one minimizes the average distance from dwellings to the respective multi-compartment container; the last two objectives address the “pull” and “push” characteristics of the decision problem, one by minimizing the number of individuals too close to any container, and the other by minimizing the number of dwellings too far from the respective multi-compartment container. The model determines the number of facilities to be opened, the respective container capacities, their locations, their respective shares of the total waste of each type to be collected, and the dwellings assigned to each facility. The approach proposed was tested with a case study for the historical center of Coimbra city, Portugal, where a large urban renovation project, addressing about 800 buildings, is being undertaken. This paper demonstrates that the models and techniques incorporated in the interactive decision support system (IDSS) can be used to assist a decision maker (DM) in analyzing this complex problem in a realistically sized urban application. Ten solutions consisting of different combinations of underground containers for the disposal of four types of sorted waste in 12 candidate sites, were generated. These solutions and tradeoffs among the objectives are presented to the DM via tables, graphs, color-coded maps and other graphics. The DM can then use this information to “guide” the IDSS in identifying additional solutions of potential interest. Nevertheless, this research showed that a particular solution with a better objective balance can be identified. The actual sequence of additional solutions generated will depend upon the objectives and preferences of the DM in a specific application. 相似文献
940.
Percilia Cardoso Giaquinto Claudia Militão da Silva Berbert Helton Carlos Delicio 《Behavioral ecology and sociobiology》2010,64(6):1029-1035
Selection favors females that attend to reliable information about male genetic quality and fitness. Male nutritional condition
can be a significant sign of mate quality since poor nutrition can be related to reduced sperm quality, low sperm quantity,
sexually transmitted diseases, and parasites. We tested whether female Nile tilapia, Oreochromis niloticus, preferred the chemical cues of males that were well fed with high-protein diet over those fed with low-protein diet. Females
do not only discriminate between males but also show a preference for well-fed males, discriminating between the odors with
respect to nutritional state, suggesting that they were responding to a food-specific chemical cue. It is therefore likely
that nutritional condition is related to the production of pheromones in males. Our results suggest that information about
male nutritional state can be conveyed in chemical cues and that females attend to these cues during mate choice. 相似文献