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181.
A tradeoff between immune response and life history traits, in particular growth rate, has been documented in various bird species. Ostriches are fast-growing birds and a typical feature of cohorts is that offspring often differ greatly in size. We investigated the relationship between hatching date and growth rate of chicks and both cell-mediated (measured using a phytohaemagglutinin (PHA) injection) and humoral immune responses in ostrich chicks maintained on a research farm. Chicks with higher growth rates had intermediate responses to both diphtheria and tetanus toxoids. By contrast, no relation between growth rates and responses to PHA injection were found. We conclude that chick growth rate variation may be explained beyond a certain threshold by a tradeoff between the humoral response and growth. Both responses to PHA injection and humoral responses in chicks were found to decrease with chick hatching date. Within the context of ostrich farming, these results could partially explain size variations observed in cohorts of chicks, as well as high mortality rates during their first 3 months of age.  相似文献   
182.
Small island developing states (SIDS) in the Caribbean have long specialised in primary commodity exports, and traditional export sectors continue to be a major source of employment. The challenge of sustainable development for the Caribbean SIDS has two dimensions. The first is to adjust to the economic and social impact of the loss of preferential markets for traditional exports and of the dismantling of the ISI apparatus erected during the post-World War II period. The second is to ensure that existing and new patterns of production and consumption comply with the criteria for sustainable development, which is here defined as environmental, socio-cultural and economic sustainability.
This article outlines the potential contribution of sustainable tourism to the larger goal of sustainable development in the SIDS in the Caribbean. It reviews current literature on sustainable development and sustainable tourism, particularly their application to the Caribbean SIDS, and evaluates the Caribbean tourism industry from the point of view of sustainable tourism. Conclusions are drawn and proposals made for a policy-oriented agenda in support of the quest for sustainable tourism in the SIDS in the Caribbean.  相似文献   
183.
ABSTRACT: This paper reports on the current assessment of climate impacts on water resources, including aquatic ecosystems, agricultural demands, and water management, in the U.S. Great Plains. Climate change in the region may have profound effects on agricultural users, aquatic ecosystems, and urban and industrial users alike. In the central Great Plains Region, the potential impacts of climate changes include changes in winter snowfall and snow-melt, growing season rainfall amounts and intensities, minimum winter temperature, and summer time average temperature. Specifically, results from general circulation models indicate that both annual average temperatures and total annual precipitation will increase over the region. However, the seasonal patterns are not uniform. The combined effect of these changes in weather patterns and average seasonal climate will affect numerous sectors critical to the economic, social and ecological welfare of this region. Research is needed to better address the current competition among the water needs of agriculture, urban and industrial uses, and natural ecosystems, and then to look at potential changes. These diverse demands on water needs in this region compound the difficulty in managing water use and projecting the impact of climate changes among the various critical sectors in this region.  相似文献   
184.

BOOKS

The Handbook of Environmental Chemistry Founded by: Otto Hutzinger – Publisher: Springer – Editors-in-chief: Damià Barceló · Andrey G. Kostianoy – ISSN: 1867-979X  相似文献   
185.
Reactive nitrogen can travel far from emission sources and impact sensitive ecosystems. From 2002 to 2006, policy actions have led to decreases in NO(x) emissions from power plants and motor vehicles. In this study, atmospheric chemical transport modeling demonstrates that these emissions reductions have led to a downward trend in ambient measurements of transported reactive nitrogen, especially atmospheric concentrations and wet deposition of nitrate. The trend in reduced nitrogen, namely ammonium, is ambiguous. As reduced nitrogen becomes a larger fraction of the reactive nitrogen budget, wide-spread NH(3) measurements and improved NH(3) emissions assessments are a critical need.  相似文献   
186.
Methodology to produce materials derived from renewable resources is of great importance in decreasing both environmental impact as well as dependence on fossil fuels. We report a straightforward method of polymer grafting to soy protein hydrolysates, which are available in surplus. Benzylthiocarbonate moieties were installed on the protein surface via amidation of free amino groups, creating a protein macro chain transfer agent (CTA) for reversible addition fragmentation transfer (RAFT) polymerization. We found that subjection of this soy protein macro-CTA (SP-CTA) to RAFT polymerization conditions with polar acrylate monomers resulted in protein-polymer nanometer-scale particles with solubility properties dictated by monomer polarity. Polymer grafting, particle size and polymerization were characterized by elemental analysis, transmission electron microscopy and gel permeation chromatography. We anticipate that this method of grafting will be of use in generation of new materials based on renewable resources.  相似文献   
187.
Recent Federal legislation on the implementation and enforcement of environmental quality standards requires an economic analysis of industrial waste treatment. Estimates of abatement costs provide information on the adequacy of industrial programs to meet current standards and the likely economic impact of future controls.  相似文献   
188.
The fuel shortage has encouraged the utilization of high sulfur fuels in those facilities where they can be used in an environmentally safe manner. A study was undertaken by the State of Iowa to correlate sulfur content of coals, stack heights, and maximum ground level concentrations from power plants. This study revealed that the primary National Ambient Air Quality Standards for SO2 are more restrictive than the secondary standard in almost all cases. This conclusion is contrary to the position that the attainment of the secondary standard could beata later date than the attainment of the primary standards.  相似文献   
189.
2,2,4-trimethyl, 1,3-pentanediol monoisobutyrate (TPM) is a widely used solvent found in water-based coatings. Ambient measurements of TPM are reported here for the first time. Although this compound has been previously measured in indoor air, this study illustrates successful detection and quantification of TPM in ambient air at three locations in Southern California: Pico Rivera, Azusa, and Riverside. TPM was detected in every sample collected, with concentrations ranging from 0.7 to 49.5 parts per trillion (ppt). Collections took place during summer 2009, fall 2009, winter 2009/2010, and spring 2010, for 5–7 days during each season. The highest mean concentrations were observed during the summer months for each city, when coating activities are typically at their highest.

Implications 2,2,4-Trimethyl, 1,3-pentanediol monoisobutyrate (TPM) is a widely used solvent found in water-based coatings. Ambient measurements of TPM are reported here for the first time. The highest mean concentrations were observed during the summer months for each city, when coating activities are typically at their highest. Unreacted TPM constitutes approximately 0.01% of the total nonmethane hydrocarbon (NMHC) concentrations in the Los Angeles air basin and given its slow reactivity rate in forming ozone, this would be an approximate upper limit for the fraction of ozone that it is responsible for forming.  相似文献   
190.
A wind tunnel study was conducted to determine the optimal design features of a large, open-top chamber, as needed for pollution exposure studies on mature trees. An optimally-designed, open-top chamber must minimize the incursion of ambient air through its opening and maintain a uniform treatment concentration throughout the chamber. The design features of interest are the diameter and height of the chamber and the deflection angle and opening size of any frustum that may be mounted on top of a model chamber.

Design specifications depend on the turbulence regime about the chamber, which is influenced by the nature of the surrounding vegetation. Consequently, our investigation was performed on scale-model, open-top chambers in a wind tunnel populated with a model coniferous forest. Turbulence measurements demonstrated the similarity between the turbulence regime of the model and a natural forest. A hydrocarbon tracer was injected into the wind tunnel flow to characterize chamber performance.

The main design features of open-top chambers are the velocity of air exiting through the top and the relationship between the length scale of the turbulence and the diameter of the chamber opening. As exit velocities increase, the proportion of eddies with sufficient force to penetrate into the chamber decrease. Therefore, for equal volumetric air flows, smaller opening sizes increase the exit velocities and reduce the number and extent of ambient air incursions. Almost total exclusion of ambient air is achieved as the exit velocity of the air exceeds the magnitude of one standard deviation of the vertical wind velocity measured at the chamber top. The incursion of ambient air is also reduced when the diameter of the chamber opening is smaller than the characteristic length scale of the turbulence, a measure of mean eddy size.

Frusta deflect air flow over the chamber. Three prototypes, with 30?, 45? and 60-degree angles were tested. A 30-degree frustum slightly improves the performance of the chamber and is more effective in preventing ambient air from entraining into the chamber opening than frusta with either a 45? or 60-degree angle. A flatter frustum allows for a smoother transition in the wind velocity streamline and is less apt to cause wake turbulence, as is the case with steeper frusta.

Knowledge of the turbulence characteristics of plant canopies are readily available in the literature and can aid scientists and engineers in designing the optimal chamber and frusta dimensions for their particular application. Therefore, the empirical approach to chamber design can be avoided, and substantial savings can be realized.  相似文献   
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