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601.
Bruce H. Pugesek 《Behavioral ecology and sociobiology》1990,27(3):211-215
Summary Parental effort was studied among knownaged California gulls (Larus californicus) with a brood size of two. Results supported three of Triver's predictions from parent-offspring conflict theory. First, the amount of time parents withheld food from offspring increased with increasing offspring age. Second, older parents were less likely than younger parents to withhold food from offspring throughout the period of parental care. Third, older parents had a longer period of parental care compared to younger parents. Adult survival to future breeding seasons was inversely related to duration of parental care. Older parents, in association with their greater levels of parental effort, had a lower survival rate compared to that of younger parents. 相似文献
602.
The effect of cadmium on antioxidant responses and the susceptibility to oxidative stress in the hydrothermal vent mussel Bathymodiolus azoricus 总被引:1,自引:0,他引:1
Rui Company Angela Serafim Richard Cosson Lionel Camus Bruce Shillito Aline Fiala-Médioni Maria João Bebianno 《Marine Biology》2006,148(4):817-825
Hydrothermal vents are a unique environment of extreme physical–chemical characteristics and biological species composition.
Cd is a toxic non-essential metal present in high concentrations in the hydrothermal vent environment, contrary to those found
in marine coastal areas. Cd toxicity has been related, among other things, with reactive oxygen species production, even though
this is a non-redox metal. Bathymodiolus azoricus is a deep-sea Mytilid bivalve very common in the Mid Atlantic Ridge (MAR) hydrothermal vent fields and very little is known
about the antioxidant defence system in this specie. Because lethal Cd concentration in B. azoricus is unknown, the aim of this study was to assess the effects of a Cd concentration higher than that found in the hydrothermal
vents on oxidative stress biomarkers, such as antioxidant enzymes. Mussels were exposed to 100 μg l−1 Cd during 24, 48 and 144 h, respectively, in a pressurized aquarium (IPOCAMP). Superoxide dismutase (SOD), catalase (CAT),
glutathione peroxidases (GPx), total oxyradical scavenging capacity (TOSC), metallothionein (MT) and lipid peroxidation (LPO)
were measured in the gills and mantle of B. azoricus. The results indicate that gills are first affected by Cd toxicity. This may be due to different physiological functions
of the tissues and by the presence of thio and methanotrophic symbiotic bacteria in the gills. The SOD and CAT are inhibited
during the first day of exposure in the gills, although TOSC and MT concentrations were the same in control and exposed mussels.
In the mantle, enzymatic activation only occurred after 6 days, and no significant differences in MT concentrations were found
in the control and exposed mussels during the first day, as observed in the gills. 相似文献
603.
Bruce E. Lyon 《Behavioral ecology and sociobiology》1993,33(2):87-100
Summary I examined the tactics adopted by a conspecific brood parasite, the American coot (Fulica americana), and the degree to which these tactics reflect sources of mortality for parasitic eggs. Only 8% of parasitic eggs produced independent offspring, compared to a 35% success rate for non-parasitic eggs, and most mortality was due to egg-rejection by hosts or the consequences of laying eggs too late in the host's nesting cycle. Parasites usually laid parasitically before initiating their own nests and usually parasitized immediate neighbours. Parasites did not remove host eggs before laying their own egg, and egg disappearance in general was not more common at parasitized nests. I found no evidence for non-random host choice, either on the basis of stage of the host's nesting cycle or the host's brood size. The absence of adaptive host choice is likely a consequence of the fact that, due to host limitation, only a small proportion of parasites had meaningful variation among potential hosts to choose from. The pattern of egg dispersion among host nests by individual parasites appears to be a compromise between constraints imposed by host limitation and the increased success obtained from spreading eggs among nests. Most females laying fewer than five parasitic eggs laid them in a single host nest while females laying five or more eggs normally parasitized two or more hosts. An examination of egg rejection and survival rates showed that parasites would maximize success by laying a single egg per host nest, and the pattern of laying several eggs per host nest is likely a consequence of host limitation. However, no egg that was the fifth laid, or later, parasitic egg in a host nest was ever successful and this probably explains why most females laying five or more eggs parasitized more than one host. 相似文献
604.
605.
Lawrence D. Platt M.D. Greggory R. Devore Janet Horenstein Zdena Pavlova Bruce Kovacs Rena Ellen Falk 《黑龙江环境通报》1987,7(6):407-411
Fetal echocardiography was used to identify a cardiac rhabdomyoma in the second trimester. The combination of this finding with a maternal history of Tuberous Sclerosis allowed the patient and her family to make a more educated decision regarding termination of the pregnancy. Post mortem examination of the fetus confirmed the prenatal findings. This case report demonstrates the importance of ultrasound evaluation of the fetus at risk of recurrence of a genetic syndrome in which one or more anatomical defects might be seen. 相似文献
606.
Polycyclic musk compounds in higher trophic level aquatic organisms and humans from the United States 总被引:6,自引:0,他引:6
Kannan K Reiner JL Yun SH Perrotta EE Tao L Johnson-Restrepo B Rodan BD 《Chemosphere》2005,61(5):693-700
Polycyclic musks, 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[g]-2-benzopyran (HHCB) and 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene (AHTN), are used as fragrance ingredients in numerous consumer products such as cleaning agents and personal care products. Studies have reported the widespread occurrence of these musks in surface waters and fish from western European countries. Nevertheless, little is known about their accumulation in humans and wildlife in the United States. In this study, we measured concentrations of HHCB and AHTN in human adipose fat collected from New York City. Furthermore, tissues from marine mammals, water birds, and fish collected from US waters were analyzed to determine the concentrations of HHCB and AHTN. Concentrations of HHCB and AHTN in human adipose fat samples ranged from 12 to 798 and from <5 to 134 ng/g, on a lipid weight basis, respectively. A significant correlation existed between the concentrations of HHCB and AHTN in human adipose fat. Concentrations of HHCB and AHTN were not positively correlated with age or gender of the donors. HHCB was found in tissues of several wildlife species, but not in the livers of polar bear from the Alaskan Arctic. Among wildlife species analyzed, spinner and bottlenose dolphins collected from Florida coastal waters contained measurable concentrations of HHCB. 相似文献
607.
Srivastava RK Hall RE Khan S Culligan K Lani BW 《Journal of the Air & Waste Management Association (1995)》2005,55(9):1367-1388
Recent regulations have required reductions in emissions of nitrogen oxides (NOx) from electric utility boilers. To comply with these regulatory requirements, it is increasingly important to implement state-of-the-art NOx control technologies on coal-fired utility boilers. This paper reviews NOx control options for these boilers. It discusses the established commercial primary and secondary control technologies and examines what is being done to use them more effectively. Furthermore, the paper discusses recent developments in NOx controls. The popular primary control technologies in use in the United States are low-NOx burners and overfire air. Data reflect that average NOx reductions for specific primary controls have ranged from 35% to 63% from 1995 emissions levels. The secondary NOx control technologies applied on U.S. coal-fired utility boilers include reburning, selective noncatalytic reduction (SNCR), and selective catalytic reduction (SCR). Thirty-six U.S. coal-fired utility boilers have installed SNCR, and reported NOx reductions achieved at these applications ranged from 15% to 66%. Recently, SCR has been installed at >150 U.S. coal-fired utility boilers. Data on the performance of 20 SCR systems operating in the United States with low-NOx emissions reflect that in 2003, these units achieved NOx emission rates between 0.04 and 0.07 lb/10(6) Btu. 相似文献
608.
G. Bruce Wiersma 《Chemosphere》1987,16(10-12)
The concentration, enrichment factor and storage of 27 elements was examined for
growing in Olympic National Park, Washington. Most element concentrations changed significantly as the moss aged. Concentrations of copper, zinc, and lead were among the lowest found to date. Crustal enrichment factors indicated many elements were initially derived from atmospheric sources. These data indicate concentrations of heavy metals in remote, unpolluted sites may be considerably lower than initially thought.Mosses have been used to monitor air pollution because they accumulate trace elements and their growth is sensitive to pollutants.
and
were used to monitor trace element contamination in Europe (Yale and Lloyd 1984, Goodman and Roberts 1971, Lotschert and Wardtner 1982). The older portions of
tended to have higher concentrations of copper and zinc than the newer portions. Sweiboda and Kalemba (1981) used
and other mosses to monitor the presence of sulfur and flourine. An ecological index of contamination was developed by Le Blanc, et al. (1974) based heavily on the presence and absence of lichen and moss species around a copper mill area in Quebec, Canada. These studies demonstrate that the chemical composition of moss tissues and changes in species abundance are sensitive to atmospheric chemical composition. 相似文献
609.
610.
In their analyses of the impact of pollution taxation on the location of polluting decisions, U. K. Mathur (J. Environ. Econom. Management 3, 16–28 (1976)) and S. S. Gokturk (J. Reg. Sci. 19, 461–467 (1979)) obtained the result that a tax increase on urban pollution concentration may not succeed in pushing the polluting firm away from the urban center. In this paper is shown that the sufficient condition for success in this case depends upon the specification of the production and pollution emissions technology and may be the opposite to the one posited by Mathur and has more intuitive appeal. 相似文献