Are soil conservation technologies “win‐win?” A case study of Anjeni in the north‐western Ethiopian highlands

This study measures the impact of fanya juu terraces on the net value of crop income in a high‐rainfall area in the Ethiopian highlands using cross‐sectional multiple plot observations. Using propensity score matching methods we find that the net value of crop income for plots with fanya juu terraces is lower than for plots without fanya juu terraces. This finding makes it difficult to avoid concluding that while the technologies might reduce soil erosion and associated off‐site effects, they do so at the expense of poor farmers in the Ethiopian highlands. Therefore, fanya juu terraces cannot be characterized as a “win‐win” measure to reduce soil erosion. New agricultural technologies need to be profitable to the farmer if they are to be adopted and sustained.     

Is a negative correlation between resource abundance and growth sufficient evidence that there is a “resource curse”?

Evidence from cross-sectional growth regressions suggests that economies dependent on natural resource exports have had slower growth than resource scarce economies. Explanations for this “curse of resources” focus on institutional and market failures caused by resource abundance. With a simple two sector model exhaustible resource model, we demonstrate that the correlation between growth and natural resource abundance can be negative in the absence of market and institutional failures. Since there is no way to distinguish between efficient and inefficient equilibria on the basis of the negative correlation between growth and resource abundance, finding that correlation is not sufficient to conclude resources are a curse, nor is it necessary to find a positive correlation between growth and resources to overturn the resource curse interpretation. We show whether resources are a curse or a blessing for an economy can only be determined by an investigation of the correlation between resource abundance and income levels. Using panel data for U.S. states for the period 1970-2001, we show that resource abundance is negatively correlated with growth rates but positively correlated with income levels.     

Are denser cities greener? Evidence from China, 2000–2010

Whether a city develops into a more compact one with a higher density or a more sprawling one may affect multiple aspects of the urban environment, including ecosystem health, greenhouse gas emissions, and quality of life. Using panel data gathered from China's cities from 2000 to 2010, we take advantage of the significant variation in the temporal change of density across cities to estimate the relationship between gross urban population density and multiple indicators of urban greenness. Fixed‐effects estimates support the widely held belief that density improves air quality and reduces the per capita carbon footprint. Results also suggest that higher density reduces the growth of road infrastructure and vehicle ownership and promotes walking. While density often translates into proximity and accessibility, higher density does reduce a city's per capita urban park and green space. This study strengthens the urban policy and planning literature with much needed longitudinal evidence. Our overall findings support higher density as opposed to lower density urban development in China.     

Do Energy‐Based PET Models Require More Input Data than Temperature‐Based Models? — An Evaluation at Four Humid FluxNet Sites

It is well established that wet environment potential evapotranspiration (PET) can be reliably estimated using the energy budget at the canopy or land surface. However, in most cases the necessary radiation measurements are not available and, thus, empirical temperature‐based PET models are still widely used, especially in watershed models. Here we question the presumption that empirical PET models require fewer input data than more physically based models. Specifically, we test whether the energy‐budget‐based Priestley‐Taylor (P‐T) model can reliably predict daily PET using primarily air temperature to estimate the radiation fluxes and associated parameters. This method of calculating PET requires only daily minimum and maximum temperature, day of the year, and latitude. We compared PET estimates using directly measured radiation fluxes to PET calculated from temperature‐based radiation estimates at four humid AmeriFlux sites. We found good agreement between P‐T PET calculated from measured radiation fluxes and P‐T PET determined via air temperature. In addition, in three of the four sites, the temperature‐based radiation approximations had a stronger correlation with measured evapotranspiration (ET) during periods of maximal ET than fully empirical Hargreaves, Hamon and Oudin methods. Of the three fully empirical models, the Hargreaves performed the best. Overall, the results suggest that daily PET estimates can be made using a physically based approach even when radiation measurements are unavailable.     

G201光催化剂应用于陶瓷和玻璃生产技术

由福州桑莱思科技开发有限公司开发的G201光催化剂适用于新型环保建材光净化陶瓷和玻璃。主要技术内容一、基本原理利用高效光催化剂的强氧化性与超亲水性原理,以特定技术将上述高效光催化剂镀在陶瓷表面,形成的光催化膜可将光能转化为化学能,起到分解油污、降臭味、耐脏和自动杀灭细菌等作用。光催化膜本身也是一种纳米陶瓷涂层,生产该种陶瓷无需改变原有的陶瓷(包括瓷砖、卫生陶瓷和日用瓷等)生产工艺,仅需附加少量装置和增加两道工序。二、技术关键首先是使用专用高效光催化剂,其次是喷涂和热处理技术。光催化瓷砖环保性能优异,同时能保…     

Will Evolving Climate Conditions Increase the Risk of Floods of the Large U.S.‐Canada Transboundary Richelieu River Basin?

In spring 2011, an unprecedented flood hit the complex eastern United States (U.S.)–Canada transboundary Lake Champlain–Richelieu River (LCRR) Basin, destructing properties and inducing negative impacts on agriculture and fish habitats. The damages, covered by the Governments of Canada and the U.S., were estimated to C$90M. This natural disaster motivated the study of mitigation measures to prevent such disasters from reoccurring. When evaluating flood risks, long‐term evolving climate change should be taken into account to adopt mitigation measures that will remain relevant in the future. To assess the impacts of climate change on flood risks of the LCRR basin, three bias‐corrected multi‐resolution ensembles of climate projections for two greenhouse gas concentration scenarios were used to force a state‐of‐the‐art, high‐resolution, distributed hydrological model. The analysis of the hydrological simulations indicates that the 20‐year return period flood (corresponding to a medium flood) should decrease between 8% and 35% for the end of the 21st Century (2070–2099) time horizon and for the high‐emission scenario representative concentration pathway (RCP) 8.5. The reduction in flood risks is explained by a decrease in snow accumulation and an increase in evapotranspiration expected with the future warming of the region. Nevertheless, due to the large climate inter‐annual variability, short‐term flood probabilities should remain similar to those experienced in the recent past.     

技信息China Science and Technology Information186TN0-4I135;2;A;I;I135_2;马

00070002;183产学研结合——全面拓展职教空间的有效途径王华利;戴葵堂;湖北三峡职业技术学院,湖北三峡职业技术学院 443003,4430030中国科技信息China Science and Technology Information187 192G710H132;1;A;H;H132_1;王华利;00030010;184 189现代展览馆视觉识别系统的现状与建设思路吴郑玲;郑州美术馆 450003展览馆;;缺     

戈尔SuperflexTM"焚烧王"技术

美国戈尔公司基于"表面过滤"理论,开发的Gore-Tex 薄膜滤袋产品,为最严格的排放控制及电厂BOT运作的经济性提供了保障.其中,SuperflexTM滤袋产品及技术,为垃圾发电行业提供了超强的性能及极长的工作寿命.