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61.
Douglas HD 《Die Naturwissenschaften》2008,95(1):45-53
Alloanointing, the transfer of chemicals between conspecifics, is known among mammals, but hitherto, the behavior has not been documented for birds. The crested auklet (Aethia cristatella), a colonial seabird of Alaskan and Siberian waters, alloanoints during courtship with fragrant aldehydes that are released from specialized wick-like feathers located in the interscapular region. Crested auklets solicit anointment at the colony, and prospective mates rub bill, breast, head, and neck over wick feathers of their partners. This distributes aldehydes over the head, neck, and face where the birds cannot self-preen. The resulting chemical concentrations are sufficient to deter ectoparasites. Auklets that emit more odorant can transfer more defensive chemicals to mates and are thus more sexually attractive. Behavioral studies showed that crested auklets are attracted to their scent. Wild birds searched for dispensers that emitted their scent and rubbed their bills on the dispensers and engaged in vigorous anointment behaviors. In captive experiments, naïve crested auklets responded more strongly to synthetic auklet scent than controls, and the greatest behavioral response occurred during early courtship. This study extends scientific knowledge regarding functions of alloanointing. Alloanointing had previously been attributed to scent marking and individual recognition in vertebrates. Alloanointing is described here in the context of an adaptive social cue — the transfer of arthropod deterrents between prospective mates. 相似文献
62.
Agricultural income from growing crops is susceptible to a variety of risks—the price of output and the actual amount of output are generally the largest risk variables. This article focuses on yield risk rather than price risk by reviewing innovation in risk transfer for natural hazard risk in agriculture. While many higher-income countries have long-standing crop insurance programs, these programs are not appropriate for lower-income countries. Lower-income countries can ill-afford the subsidies that are used in most multiple peril crop insurance programs throughout the world. Still, lower-income countries have large numbers of small farms increasing the need for agricultural insurance to protect against common problems that create disastrous losses for many individual farm households. 相似文献
63.
Terry Barker Annela Anger Olivier Dessens Hector Pollitt Helen Rogers Serban Scrieciu Rod Jones John Pyle 《Environmental Science & Policy》2010,13(8):661-670
This paper reports the methodology and results of an one-way coupling of the E3 Model at the Global level (E3MG) model to the global atmospheric chemistry model, p-TOMCAT, to assess the effects on the concentrations of atmospheric gases over Mexico of a low-GHG scenario compared to an alternative reference case with higher use of fossil fuels. The paper covers the data and methods, changes in atmospheric gas concentrations, the macroeconomic effects of the policies, and the outcome for pollution. The results suggest that in the conditions of underemployment in Mexico, substantial investment in low-carbon technologies, such as electric vehicles, heat pumps and geo-thermal power, could improve employment prospects, maintain growth, as well as reduce some of the risks associated with prospective falls in oil revenues. The concentrations of low-level ozone, both for Mexico-only and global decarbonisation scenarios relative to the original reference case, show appreciable reductions, sufficient to bring concentrations close to the WHO guideline levels. An indication is given of the potential scale of the benefits on human health in Mexico City. 相似文献
64.
Gutierrez-Banuelos H Pinchak WE Min BR Carstens GE Anderson RC Tedeschi LO Krueger WK Krueger NA Lancaster PA Gomez RR 《Journal of environmental science and health. Part. B》2011,46(4):360-365
Pathogenic bacteria attached to the hide or shed in the feces of cattle at slaughter can contaminate carcasses intended to be processed for human consumption. Therefore, new pre-harvest interventions are needed to prevent the carriage and excretion of foodborne pathogens in cattle presented to the processing plant. The objectives of this study were to examine the antimicrobial effects of hydrolysable tannin-rich chestnut and condensed tannin-rich mimosa extracts on bacterial indicators of foodborne pathogens when applied as a hide-intervention and as a feed additive to feedlot cattle. Water (control) or solutions (3 % wt/vol) of chestnut- and mimosa-extract treatments were sprayed (25 mL) at the left costal side of each animal to a 1000 cm2 area, divided in four equal quadrants. Hide-swabs samples obtained at pre-, 2-min, 8-h, and 24-h post-spray application were cultured to enumerate Escherichia coli/total coliforms and total aerobic plate counts. In a second experiment, diets supplemented without (controls) or with (1.5 % of diet dry matter) chestnut- or mimosa-extracts were fed during a 42-day experimental feeding period. Weekly fecal samples starting on day 0, and rumen fluid obtained on days 0, 7, 21 or 42 were cultured to enumerate E.coli/total coliforms and Campylobacter. Tannin spray application showed no effect of treatment or post-application-time (P > 0.05) on measured bacterial populations, averaging 1.7/1.8, 1.5/1.6 and 1.5/1.7 (log??CFU/cm2) for E. coli/total coliforms, and 4.0, 3.4 and 4.2 (log??CFU/cm2) in total aerobes for control, chestnut and mimosa treatments, respectively. Mean (± SEM) ruminal E. coli and total coliform concentrations (log(10) CFU/mL) were reduced (P < 0.01) in steers fed chestnut-tannins (3.6 and 3.8 ± 0.1) in comparison with the controls (4.1 and 4.2 ± 0.1). Fecal E. coli concentrations were affected by treatment (P< 0.01), showing the highest values (log?? CFU/g) in fecal contents from mimosa-fed steers compared to controls (5.9 versus 5.6 ± 0.1 SEM, respectively). Total coliforms (log CFU/g) showed the highest values (P < 0.01) in feces from chestnut- and mimosa-fed steers (6.0 and 6.1 ± 0.1 respectively) in comparison with controls (5.7 ± 0.1). Fecal Campylobacter concentrations (log??CFU/g) were affected by treatment (P < 0.05), day (P < 0.001) and their interaction (P < 0.01) with the controls having lower concentrations than chestnut- and mimosa-fed steers (0.4, 1.0, and 0.8 ± 0.3, respectively). It was concluded that under our research conditions, tannins were not effective in decreasing measured bacterial populations on beef cattle hides. Additionally, chestnut tannin reduced E. coli and total coliforms within the rumen but the antimicrobial effect was not maintained in the lower gastrointestinal tract. Further research is necessary to elucidate the possible antimicrobial effects of tannins at site-specific locations of the gastrointestinal tract in beef cattle fed high-grain and high-forage diets. 相似文献