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671.
672.
Bruce P. Hayden Robert Dolan Scott Hoffman Alan Robinson 《Environmental management》1978,2(3):209-218
Beach erosion on Cinnamon Bay in the U.S. Virgin Islands results from storm waves in the North Atlantic. The net trend of erosion, however, is due to local environmental degradation. Reef die-back, initiated during the period of high sedimentation associated with 18th and 19th century sugar cane cropping, has reduced the rate of generation of new coral sands. Sand losses to deep water during periods of storm waves are not replenished. Engineering measures designed to check erosion at Cinnamon Bay have had little effect in this environment of low wave energies, but sand deficiency. The appropriate environmental focus for management of reef-beach systems is reef health and thus, water quality. 相似文献
673.
Donald M. Bruce 《Journal of Agricultural and Environmental Ethics》2002,15(3):279-289
Future technological developmentsconcerning food, agriculture, and theenvironment face a gulf of social legitimationfrom a skeptical public and media, in the wakeof the crises of BSE, GM food, and foot andmouth disease in the UK (House of Lords, 2000). Keyethical issues were ignored by the bioindustry,regulators, and the Government, leaving alegacy of distrust. The paper examinesagricultural biotechnology in terms of a socialcontract, whose conditions would have to be fulfilled togain acceptance of novel applications. Variouscurrent and future GM applications areevaluated against these conditions. Successwould depend critically on how far a sharedvision can be found with the public. Tore-establish trust, significant changes areidentified in the planning and pursuit ofbiotechnology. 相似文献
674.
675.
Leakage and Comparative Advantage Implications of Agricultural Participation in Greenhouse Gas Emission Mitigation 总被引:2,自引:0,他引:2
Heng-Chi Lee Bruce A. McCarl Uwe A. Schneider Chi-Chung Chen 《Mitigation and Adaptation Strategies for Global Change》2007,12(4):471-494
The world is moving toward efforts to reduce net greenhouse gas emissions. Reduction efforts may involve the agricultural
sector through options such as planting of trees, altering crop and livestock management, and increasing production of biofuels.
However, such options can be competitive with domestic food production. In a free trade arena, reduced domestic food production
could stimulate increased production and exports in other countries, which are not pursuing net emission reductions. As a
consequence, emission reduction efforts in implementing countries may be offset by production increases stimulated in other
countries.
We examine the competitive effects of agriculturally related emission reduction actions on agricultural production and international
trade. In doing this, we employ the assumption that U.S. emission reduction caused cost increases will also occur in other
reducing countries. We consider emission reduction: 1) unilaterally by the U.S., 2) by all Kyoto Protocol Annex B countries,
and 3) globally. The results, which are only suggestive of the types of effects that would be observed due to the simplifying
cost assumptions, indicate compliance causes supply cutbacks in regulated countries and increases in non-regulated countries.
The study results show that producers in regulating countries are likely to benefit and consumers lose due to commodity price
increases.
Seniority of Authorship is shared among the first three authors. 相似文献
676.
Bruce A. Ramsay Ilie Saracovan Juliana A. Ramsay Robert H. Marchessault 《Journal of Polymers and the Environment》1994,2(1):1-7
A simple method was developed for the preparation of an autoclavable, long-side-chain poly (-hydroxyalkanoate) (LSC-PHA) colloidal suspension, which was used as a substrate for enzymatic degradation and to prepare agar overlay plates for the isolation of microorganisms producing extracellular LSC-PHA depolymerase. Six cultures producing extracellular LSC-PHA depolymerase were isolated from a composted hydrocarbon-contaminated soil. All were pseudomonads or related bacteria. All (with the possible exception ofXanthomonas maltophilia) could produce LSC PHA. Except forX. maltophilia none could hydrolyze poly (-hydroxybutyrate). Screening of sevenPseudomonas strains known to accumulate LSC PHA showed that all were negative for extracellular LSC-PHA depolymerase production. It was concluded that extracellular LSC-PHA depolymerase producers are found mostly in the genusPseudomonas but that they are relatively uncommon. 相似文献
677.
We captured two species of deep-sea zoarcids, Melanostigma pammelas and Lycodapus mandibularis, from Monterey Bay California and maintained them in the laboratory. One shallow-water zoarcid, Eucryphycus californicus, and an ecologically and morphologically similar stichaeid fish Xiphister atropurpureus were collected from intertidal and subtidal habitats in Monterey Bay. We investigated the absorption and assimilation efficiencies
of these fishes to determine whether deep-sea species have evolved mechanisms to increase their efficiency of food use. Fishes
were placed in experimental chambers and fed a known quantity of food. Ammonia excretion was measured and feces were collected
daily. Both food and feces were analyzed for water, protein, lipid and ash to determine specific absorption efficiencies.
Absorption ranged from 87.7 to 92.4% and assimilation efficiencies from 84.0 to 86.5%. Meal sizes from 0.5 to 4.0% of body
weight did not affect the results. No significant differences were found between deep-sea and shallow-water species fed single
meals or fed ad libitum for 10 days. This suggests that the selective pressure to maximize absorption and assimilation is
universal and is not affected by the productivity of the habitat occupied. However, the relative size of the intestine in
the deep-sea species was significantly smaller suggesting that they had a lower metabolic cost to maintain their digestive
apparatus. It could not be concluded whether this was the result of pressure to conserve energy or rather the tendency of
the shallow-living species to ingest more refractory material (i.e. sediment, algae). 相似文献
678.
This paper describes the results of a survey of the North Sea and north Atlantic waters adjacent to the Orkney and Shetland Islands, from 23 May to 9 June, 1973, using simultaneous tows of the prototype Undulating Oceanographic Recorder (UOR) and the Continuous Plankton Recorder (CPR). The UOR sampled plankton and measured salinity and temperature over its undulation profile from 5 to 65 m in depth. The CPR sampled plankton at a fixed depth of 10 m. Three principal water masses were identified, each with a characteristic plankton community. 相似文献
679.
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
680.
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