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Abstract: The alarming pace of tropical biodiversity loss requires development of innovative approaches for in situ biodiversity conservation. Incentive-based approaches have emerged as one possible option. We interviewed 68 private nature reserve owners to learn more about one of Costa Rica's incentive programs. The interview group included all reserve owners participating in the government's Private Wildlife Refuge Program (n = 22) and a control group of nonparticipating owners (n = 46). Quantitative and qualitative data led to seven main conclusions on the use of incentive programs: (1) a developing country can expand and enhance its formal park system through conservation incentives; (2) insufficient promotion, and resulting information gaps, can prevent an incentive program from realizing its full potential; (3) landowners enter a program not only in response to the intended incentive package, but also for several powerful and hidden incentives such as publicity and marketing purposes; (4) underutilization of official incentives by participants, in part due to sporadic delivery of incentives by the government, can undermine program effectiveness; (5) biodiversity protection goals can be accomplished by means of a wide range of incentives; (6) programs that require only a short-term commitment by landowners can still lead to long-term biodiversity protection; and (  7) a program can produce unanticipated negative consequences at the national level, including putting conservation at odds with social justice. These and other lessons on the use of incentives should be of interest wherever biodiversity is threatened, wherever new conservation partners are being sought, and wherever incentive-based approaches are being considered.  相似文献   
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In order to take account of the congestion externalities associated with increased use intensity during a given period at a low density recreational resource, it is necessary to determine the effects of alternative use levels on the expected quality of each individual's experience. This paper describes a simulation model for wilderness recreation designed to provide such measures. In order to illustrate the model it is applied to the Spanish Peaks Areas in Montana.  相似文献   
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In order to keep subscribers up-to-date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of prenatal diagnosis. Each bibliography is divided into 22 sections: 1 Reviews; 2 General Interest; 3 Normal Fetal Development; 4 Preimplantation Genetic Diagnosis; 5 First Trimester Diagnosis; 6 Second Trimester Diagnosis; 7 Fetal Imaging: General; Ultrasound; MRI; Doppler; 8 Maternal Serum Screening for Aneuploidy; 9 Screening for Carriers of Genetic Abnormality; 10 Molecular Cytogenetics: Metaphase Cytogenetics/FISH; Array CGH; 11 Fetal Cells in Maternal Circulation; 12 Fetal DNA/RNA in Maternal Body Fluids; 13 Fetal Therapy; 14 Psychosocial and Ethical Aspects; 15 Epidemiology and Environmental Factors; 16 Developmental and Placental Pathology; 17 Genetic Counseling. Within each section, articles are listed in alphabetical order with respect to author. If, in the preceding period, no publications are located relevant to any one of these headings, that section will be omitted  相似文献   
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Methods have been developed for calculating the Ringelmann number, opacity, and other optical characteristics of stack plumes from information on particulate properties, concentrations, and system geometry. Such calculations can be used in selecting clean-up equipment to improve stack appearance required to meet Ringelmann number and opacity pollution regulations. Methods were developed for white plumes caused by water drops or crystalline material and for black plumes containing carbon emissions. The Mie theory of light scattering was utilized to calculate plume optical properties which were related to Ringelmann number through psycophysically significant correlations. A computer program was written to perform the Mie theory and related calculations. Graphical methods were developed for plumes with log-probability size distributions composed of water drops, dusts with refractive index of 1.50 or carbon type emissions of refractive index 1.59-0.66i. Agreement of Ringelmann numbers predicted by these techniques and those observed for large stacks is excellent.  相似文献   
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ABSTRACT

In order to evaluate the existing risk to public health in Arizona related to hazardous air pollution, ambient air monitoring for selected hazardous air pollutants (HAPs) was carried out in 1994-1996 in several representative urban and rural areas of Arizona. A wide range of organic HAPs was monitored, requiring a variety of sampling and analysis methods. Stainless steel SUMMA canisters were used for collection of volatile hydrocarbons and halocarbons, which were analyzed by capillary gas chromatography with flame ionization and electron capture detection (GC-FID/ECD). Carbonyl compounds were collected using 2,4-dinitrophenylhydrazine-impregnated cartridges and analyzed by high performance liquid chromatog-raphy with ultraviolet detection. Semi-volatile and non-volatile polycyclic aromatic compounds were collected using a sampling train consisting of a filter followed by a PUF/XAD-4/PUF sandwich cartridge. Following extraction, samples were analyzed by capillary GC with mass spectrometric detection (GC-MS). Database software was developed for data processing and reporting functions. This paper describes the sampling strategy and the sampling and analysis methods employed in the monitoring program and presents a summary of all the results obtained during the duration of the sampling program.  相似文献   
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ABSTRACT

Ogawa passive O3 samplers were used in a 13-week study (June 1-September 1, 1999) involving 11 forested and mountaintop sites in north-central Pennsylvania. Four of the sites were collocated with TECO model 49 O3 analyzers. A significant correlation (p < 0.0001) was found for 24-hr average weekly O3 concentrations between the two methodologies at the four sites with collocated monitors. As expected, there were positive relationships between increasing elevation of the sites and increasing O3 concentrations. No O3 exposure patterns were found on a west-to-east or south-to-north basis; however, the area known for lower O3 exposures within a smaller subsection of the study area showed consistently lower O3 exposures. Preliminary results regarding relationships of symptom responses within O3-sensitive bioindicators are also presented with black cherry (Prunus serotina, Elirli.) and common milkweed (Asclepias syriaca, L.) showing clear evidence of increasing injury with increasing O3 exposures. Due to the extremely dry conditions encountered in north-central Pennsylvania during the 1999 growing season, O3-induced symptoms were sporadic and quite delayed until late-season rains during the latter portion of the observation period.  相似文献   
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The intent of this paper is to place the concepts of exposure, vulnerability, resilience and risk in the context of the consequences of global change for the sustainable development of small island developing states (SIDS). Many such states face a number of global climate change risks, such as an increase in the proportion of more intense storms, along with other global change threats that include energy security and costs. All these threats come on top of local development threats, such as increased run-off, often with increasing levels of contaminants due to unsustainable agricultural and industrial practices. When taken together, the resulting pressures on islands and their communities lead to significant increases in vulnerability to change due to reduced resilience to these changes. Vulnerability is also increasing as a result of contemporary processes that heighten the exposure of material and other assets. The capacity to address hazard risk also influences vulnerability. This includes the level of awareness of coastal hazards and exposure, and access to critical life support infrastructure, especially for people living in hazard-prone areas. Vulnerability and resilience are considered to be important integrating concepts when managing the local consequences of global changes. There are many initiatives that will help reduce the vulnerability and enhance the resilience of SIDS to such changes. These include improving risk knowledge and coastal resource and land use management, while also strengthening socio-economic systems and livelihoods. In this way, managing global change can be closely aligned with local development and humanitarian processes, thereby enhancing the overall sustainability of development processes and outcomes.  相似文献   
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