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51.
Lloyd Wright 《Natural resources forum》2001,25(2):121-134
The rapid growth of Latin American urban centres beginning in the 1970s placed a heavy strain upon urban transport service providers. Facing high population growth from a citizenry dependent upon public transport and having limited financial resources to develop car‐based infrastructure, Latin American municipal planners were challenged to create a new transport paradigm. One ingenious response to this dilemma was the busway, a surface metro system that utilizes exclusive right‐of‐way bus lanes. The developers of the Latin American busways astutely observed that the ultimate objective was to swiftly, efficiently and cost‐effectively move people rather than cars. Examples of innovative busway systems are presented from Curitiba, Bogota, Porto Alegre, Quito and Sao Paulo. The low cost, flexibility and speed of the exclusive busways all contribute to extremely high levels of customer satisfaction. Innovative approaches to the design of busway loading stations and simplified ticketing have also helped to reduce operating costs and improve customer flows. Additionally, clear system maps, colour‐coded routing, system safety and cleanliness and superior customer service have helped direct consumer preference towards the busway. The success of busways has also proved that costly subway systems or uncontrolled sprawl are not the only options available to municipal planners. The Latin American busway corridors provide high peak capacities that permit busway corridors to serve the transit requirements of most medium‐ to large‐sized cities. When integrated with progressive land‐use policies, busways can also form the basis of more sustainable urban design by encouraging development corridors with high‐density, mixed‐use land use. The environmental benefits and calming influences afforded cities by busway systems have translated into dramatically improved levels of quality of life indicators, including improvements in health, crime reduction and poverty alleviation. The user‐friendliness and cost‐effectiveness of busway systems have convinced municipal leaders in North America, Europe and Australia to develop similar systems of their own. Latin American busways thus provide a unique example of South to North technology transfer. 相似文献
52.
Residual herbicides regularly used in conjunction with conservation tillage to produce corn ( L.) and soybean [ (L.) Merr] are often detected in surface water at concentrations that exceed their U.S. maximum contaminant levels (MCL) and ecological standards. These risks might be reduced by planting glyphosate-tolerant varieties of these crops and totally or partially replacing the residual herbicides alachlor, atrazine, linuron, and metribuzin with glyphosate, a contact herbicide that has a short half-life and is strongly sorbed to soil. Therefore, we applied both herbicide types at typical rates and times to two chisel-plowed and two no-till watersheds in a 2-yr corn/soybean rotation and at half rates to three disked watersheds in a 3-yr corn/soybean/wheat-red clover ( L.- L.) rotation and monitored herbicide losses in surface runoff for three crop years. Average dissolved glyphosate loss for all tillage practices, as a percentage of the amount applied, was significantly less ( ≤ 0.05) than the losses of atrazine (21.4x), alachlor (3.5x), and linuron (8.7x) in corn-crop years. Annual, flow-weighted, concentration of atrazine was as high as 41.3 μg L, much greater than its 3 μg L MCL. Likewise, annual, flow-weighted alachlor concentration (MCL = 2 μg L) was as high as 11.2 and 4.9 μg L in corn- and soybean-crop years, respectively. In only one runoff event during the 18 watershed-years it was applied did glyphosate concentration exceed its 700 μg L MCL and the highest, annual, flow-weighted concentration was 3.9 μg L. Planting glyphosate-tolerant corn and soybean and using glyphosate in lieu of some residual herbicides should reduce the impact of the production of these crops on surface water quality. 相似文献
53.
This study examined the cooperative effects of diffusion and reaction on the degradation of a polymer. The work was intended
to describe bulk degradation processes, where the polymer volume remains nearly constant. Test coupons made from poly (2-ethyl
2-oxazoline) were immersed in water for controlled durations. The coupons were weighed before and after immersion in the wet
and dried condition. The coupons were observed to gain weight for short immersion durations. At longer durations the weight
change became negative as the solvent reacted with and dissolved the polymer. An average solvent concentration was found from
the weight measurements. Fick’s law was used to express the increase in concentration while a first order reaction law was
used to represent the decrease in concentration of the solvent. The competing changes in concentration were combined from
which the net solvent concentration at any given time was obtained. The model was compared with the experimental measurements
using coupons of various thicknesses. The model was found to describe the observed polymer degradation in water including
thickness effects. 相似文献
54.
The Forum Theatre of Augusto Boal: A Dramatic Model for Dialogue and Community-Based Environmental Science 总被引:1,自引:0,他引:1
Community oriented environmental science combines the inclusive, action-oriented goals of environmental justice communities and the rationalist methodologies of science in an effort to balance urgent social and physical needs with research protocols, precise analysis and carefully measured conclusions. Community-based participatory research acknowledges that local expertise and networks, adverse social and economic consequences of environmental degradation and community beliefs and attitudes are vital factors that affect both overall community health and research outcomes. A unique CBPR approach to inclusive outreach and education is Community Environmental Forum Theatre (CEFT), developed through the National Institute of Environmental Health Sciences Center in Environmental Toxicology at the University of Texas Medical Branch/Galveston TX. CEFT integrates the dramaturgy of Augusto Boal's Theatre of the Oppressed and the democratizing dialogic process of Paulo Freire into the design and implementation of environmental health research, community health care and education. CEFT projects throughout the Texas petrochemical belt have used this form of interactive workshop and energized public performance to increase knowledge of toxicological concepts, develop risk awareness, extend and strengthen coalitions, create action agendas and promote community advocacy skills. Boal image-making techniques help to deconstruct concepts such as exposure pathways, dose response, differential susceptibilities, multiple stressors/cumulative risk and the healthy worker effect. Image-based ethnographies provide insight into risk perceptions, risk communication outcomes and overarching community dynamics impacting environmental justice. CEFT project efficacy is evaluated via a multi-frame process focused on goals specific to the roles of the scientific/environmental health outreach specialist, the community development artist/practitioner and the advocate for environmental health and justice issues. 相似文献
55.
56.
57.
Glenn Lurman Till Blaser Miles Lamare Koh-Siang Tan Hans Poertner Lloyd S. Peck Simon A. Morley 《Marine Biology》2010,157(8):1705-1712
Temperature and mitochondrial plasticity are well studied in fishes, but little is known about this relationship in invertebrates.
The effects of habitat temperature on mitochondrial ultrastructure were examined in three con-familial limpets from the Antarctic
(Nacella concinna), New Zealand (Cellana ornata), and Singapore (Cellana radiata). The effects of seasonal changes in temperature were also examined in winter and summer C. ornata. Stereological methods showed that limpet pedal myocytes were 1–2 orders of magnitude smaller in diameter (≈3.5 μm) than
in vertebrates, and that the diameter did not vary as a function of temperature. Mitochondrial volume density (Vv(mt,f)) was approximately 2–4 times higher in N. concinna (0.024) than in the other species (0.01 and 0.006), which were not significantly different from each other. Mitochondrial
cristae surface density (Sv(im,mt)) was significantly lower in summer C. ornata (24.1 ± 0.50 μm2 μm−3) than both winter C. ornata (32.3 ± 0.95 μm2 μm−3) and N. concinna (34.3 ± 4.43 μm2 μm−3). The surface area of mitochondrial cristae per unit fibre volume was significantly higher in N. concinna, due largely to the greater mitochondrial volume density. These results and previous studies indicate that mitochondrial
proliferation in the cold is a common, but not universal response by different species from different thermal habitats. Seasonal
temperature decreases on the other hand, leading preferentially to an increase in cristae surface density. Stereological measures
also showed that energetic reserves, i.e. lipid droplets and glycogen in the pedal muscle changed greatly with season and
species. This was most likely related to gametogenesis and spawning. 相似文献
58.
Conservation tillage can reduce soil loss; however, the residual herbicides normally used to control weeds are often detected in surface runoff at high levels, particularly if runoff-producing storms occur shortly after application. Therefore, we measured losses of alachlor, atrazine, linuron, and metribuzin from seven small (0.45-0.79-ha) watersheds for 9 yr (1993-2001) to investigate whether a reduced-input system for corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] production with light disking, cultivation, and half-rate herbicide applications could reduce losses compared with chisel and no-till. As a percentage of application, annual losses were highest for all herbicides for no-till and similar for chisel and reduced-input. Atrazine was the most frequently detected herbicide and yearly flow-weighted concentrations exceeded the drinking water standard of 3 microg L(-1) in 20 out of 27 watershed years that it was applied. Averaged for 9 corn yr, yearly flow-weighted atrazine concentrations were 26.3, 9.6, and 8.3 microg L(-1) for no-till, chisel, and reduced-input, respectively. Similarly, flow-weighted concentrations of alachlor exceeded the drinking water standard of 2 microg L(-1) in 23 out of 54 application years and in all treatments. Thus, while banding and half-rate applications as part of a reduced-input management practice reduced herbicide loss, concentrations of some herbicides may still be a concern. For all watersheds, 60 to 99% of herbicide loss was due to the five largest transport events during the 9-yr period. Thus, regardless of tillage practice, a small number of runoff events, usually shortly after herbicide application, dominated herbicide transport. 相似文献
59.
Jacek A. Koziel Jarett P. Spinhirne Jenny D. Lloyd David B. Parker Donald W. Wright Fred W. Kuhrt 《Journal of the Air & Waste Management Association (1995)》2013,63(8):1147-1157
Abstract Odorous gases associated with livestock operations are complex mixtures of hundreds if not thousands of compounds. Research is needed to know how best to sample and analyze these compounds. The main objective of this research was to compare recoveries of a standard gas mixture of 11 odorous compounds from the Carboxen/PDMS 75–μm solid–phase microextraction fibers, polyvinyl fluo–ride (PVF; Tedlar), fluorinated ethylene propylene copolymer (FEP; Teflon), foil, and polyethylene terephthalate (PET; Melinex) air sampling bags, sorbent 2,b–diphenylene–oxide polymer resin (Tenax TA) tubes, and standard 6–L Stabilizer sampling canisters after sample storage for 0.5, 24, and 120 (for sorbent tubes only) hrs at room temperature. The standard gas mixture consisted of 7 volatile fatty acids (VFAs) from acetic to hexanoic, and 4 semivolatile organic compounds including p–cresol, indole, 4–ethylphenol, and 2'–aminoacetophenone with concentrations ranging from 5.1 ppb for indole to 1270 ppb for acetic acid. On average, SPME had the highest mean recovery for all 11 gases of 106.2%, and 98.3% for 0.5– and 24–hr sample storage time, respectively. This was followed by the Tenax TA sorbent tubes (94.8% and 88.3%) for 24 and 120 hr, respectively; PET bags (71.7% and 47.2%), FEP bags (75.4% and 39.4%), commercial Tedlar bags (67.6% and 22.7%), in–house–made Tedlar bags (47.3% and 37.4%), foil bags (16.4% and 4.3%), and canisters (4.2% and 0.5%), for 0.5 and 24 hr, respectively. VFAs had higher recoveries than semivolatile organic compounds for all of the bags and canisters. New FEP bags and new foil bags had the lowest and the highest amounts of chemical impurities, respectively. New commercial Tedlar bags had measurable concentrations of N,N–dimethyl acetamide and phenol. Foil bags had measurable concentrations of acetic, propionic, butyric, valeric, and hexanoic acids. 相似文献
60.
A. Gwen Eklund Samuel L. Altshuler Paulina C. Altshuler Judith C. Chow George M. Hidy Alan C. Lloyd 《Journal of the Air & Waste Management Association (1995)》2013,63(11):1235-1244
Supplemental Materials: Supplemental materials are available for this paper. Go to the publisher's online edition of the Journal of the Air & Waste Management Association. 相似文献