Gramsci in green: Neoliberal hegemony through urban forestry and the potential for a political ecology of praxis     

Harold A. Perkins 《Geoforum》2011,42(5):558-566

The US Department of Agriculture Forest Service and the Wisconsin Department of Natural Resources coordinate the distribution of urban forestry grants to nonprofits and citizen groups. These granting agencies increased state funding during a period of neoliberal, fiscal austerity in order to channel ecosystem services provided by urban forests. Increased funding is an instance of rollout neoliberalism whereby the fiscally austere state builds market capacity to harness these services as part of an ecologically modernist agenda. A Gramscian perspective and data gathered from 20 in-depth interviews with foresters are used in this paper to theorize how rollout policy is deployed through urban forestry to extend market hegemony to new geographies. This is anything but a smooth process because the public’s perception of urban trees is highly varied. State bureaucracies must build civil sector capacity to educate people about the ecosystem services trees provide as market commodities. In doing so the state’s market-oriented regulatory legitimacy is consolidated through the apparently benign act of promoting urban forestry. This dialectical process limits participation in urban forestry because markets are inherently selective. Yet it potentially gives rise to an alternative political ecology of praxis beyond market ideology when grant recipients participate in the production of urban ecology and recognize their relationship with nature.  相似文献   

Analysis and mapping of geochemical anomalies using logratio-transformed stream sediment data with censored values   总被引：1，自引：0，他引：1  

Emmanuel John M. Carranza 《Journal of Geochemical Exploration》2011

There is lack of research and documentation of actual (as opposed to theoretical) benefits (e.g., mineral deposit discovery) of developments in compositional data analysis and imputation of censored values to mineral exploration geochemistry. In the present study, analyses of logratio- and ln-transformed stream sediment geochemical data containing ca. 30% of samples with censored values of a pathfinder element for the mineral deposit-type of interest yielded the following findings. Exclusion of those samples supports interpretation of multi-element anomalies reflecting the presence of mineralization. However, the multi-element anomaly maps obtained by exclusion of those samples are barely better than the multi-element anomaly maps derived by inclusion of those samples after replacing the censored values with 1/2 of detection limit or with imputed values. Logratio (i.e., alr, clr, or ilr) transformation, compared to ln-transformation, of stream sediment geochemical data does not improve mapping of pathfinder element anomalies reflecting the presence of mineralization. However, stream sediment geochemical data, excluding or including censored values (replaced with 1/2 of detection limit or with imputed values), should be clr- or ilr-transformed to enhance recognition of anomalous multi-element associations reflecting the presence of mineralization. The anomaly maps of multi-element associations derived from ilr-transformed data are better, albeit slightly, than the anomaly maps of multi-element associations derived from clr-transformed data. In the present study, the main benefit of either clr- or ilr-transformation, compared to either ln- or alr-transformation, of stream sediment geochemical data is the enhancement of anomalous multi-element associations reflecting the presence of mineralization. This is an important benefit because variations in trace element concentrations in regional-scale stream sediment geochemical data are mostly due to lithology and other factors (or processes) unrelated to mineralization. Further investigations of various exploration geochemical data are needed to demonstrate and document the actual (as opposed to theoretical) benefits of developments in compositional data analysis and imputation of censored values to mineral exploration.  相似文献   

Regularizing Time Transformations in Symplectic and Composite Integration     

Seppo Mikkola  Paul Wiegert 《Celestial Mechanics and Dynamical Astronomy》2002,82(4):375-390

We consider numerical integration of nearly integrable Hamiltonian systems. The emphasis is on perturbed Keplerian motion, such as certain cases of the problem of two fixed centres and the restricted three-body problem. We show that the presently known methods have useful generalizations which are explicit and have a variable physical timestep which adjusts to both the central and perturbing potentials. These methods make it possible to compute accurately fairly close encounters. In some cases we suggest the use of composite (instead of symplectic) alternatives which typically seem to have equally good energy conservation properties.This revised version was published online in October 2005 with corrections to the Cover Date.  相似文献   

一类二阶非线性微分方程解的估计     

刘昌东 《广东海洋大学学报》1997,(2)

应用渐近比较的方法研究二阶非线性微分方程y＋p（t）g（y）＝0解的性质，得到该方程的所有解y（t）均满足估计式的条件。其中G（y）  相似文献   

Catch-quota balancing mechanisms in the Icelandic multi-species demersal fishery: Are all species equal?     

《Marine Policy》2015

In this study, utilization of catch-quota balancing mechanisms in the Icelandic demersal fishery, which allow for individual transferable quota to be transformed among species and transferred between years, is analyzed to determine whether annual catches closely adhere to total allowable catches on average. Icelandic landings data for 14 demersal fish species during 2001–2013 are compared to implemented total allowable catches as well as catch limits recommended by the Marine Research Institute (MRI) and a proxy for annual market values. Landings surpassed legal limits of total allowable catch in 27% of the cases (landings by species by fishing year), mostly due to species transformations, but TAC overages were not consistent for any species. Instead, catches of some species were consistently less than legal limits, with some indications that landings were related to profitability (i.e. landings were correlated with market value). However, landings surpassed MRI recommendations in 67% of the cases, and landings of four species (Atlantic wolffish, haddock, monkfish and redfish) consistently exceeded MRI recommendations. Therefore, discrepancies between scientific recommendations for catch limits and quotas selected through the political process may represent a higher risk to long-term sustainability than catch-quota balancing mechanisms.  相似文献   

Soil water content and yield variability in vineyards of Mediterranean northeastern Spain affected by mechanization and climate variability     

M. C. Ramos 《水文研究》2006,20(11):2271-2283

The objective of this paper was to analyse the combined influence of the Mediterranean climate variability (particularly the irregular rainfall distribution throughout the year) and the land transformations carried out in vineyards of northeastern Spain on soil water content evolution and its influence on grape production. The study was carried out in a commercial vineyard located in the Anoia–Alt Penedès region (Barcelona province, northeastern Spain), which was prepared for mechanization with important land transformations. Two plots were selected for the study: one with low degree of transformation of the soil profile, representing a non‐disturbed situation, and the second one in which more than 3 m were cut in the upper part of the plot and filled in the lower part, representing the disturbed situation. Soil water content was evaluated at three positions along the slope in each plot and at three depths (0–20, 20–40, 40–60 cm) during the period 1999–2001, years with different rainfall characteristics, including extreme events and long dry periods. Rainfall was recorded in the experimental field using a pluviometer linked to a data‐logger. Runoff rates and yield were evaluated at the same positions. For the same annual rainfall, the season of the year in which rainfall is recorded and its intensity are critical for water availability for crops. Soil water content varies within the plot and is related to the soil characteristics existing at the different positions of the landscape. The differences in soil depth created by soil movements in the field mechanization give rise to significant yield reductions (up to 50%) between deeper and shallow areas. In addition, for the same annual rainfall, water availability for crops depends on its distribution over the year, particularly in soils with low water‐storage capacity. The yield was strongly affected in years with dry or very dry winters. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

大凉山次级块体的整体抬升和逆时针转动   总被引：1，自引：0，他引：1       下载免费PDF全文

姚琪宋金程佳杨  文许  冲赵静 《地质科学》2017,(2):328-342

大凉山次级块体现今仍处于强烈隆升状态,周边地震活动频繁,对研究青藏高原东缘晚新生代以来的构造变形和隆升方式具有重要意义。本文基于90 m 分辨率的SRTM 数据,对大凉山次级块体及周边地区的高程进行了200 m 间隔的地形重分类,计算了地形起伏度、坡度及横跨主要断裂的廊带剖面,统计对比了该块体和相邻块体之间的高程-坡度分布。结合地震活动、大地电磁测深剖面、GPS 速度场和地质剖面,发现大凉山次级块的整体高程较高、地形较平坦,向四川盆地阶梯式下降。以安宁河断裂与则木河断裂交汇处为界,块体北部和南部的地形地貌差异较大。北部存在大量挤压抬升,南部挤压分量减少,走滑分量有所增加。在四川盆地和川滇块体的挟持下,大凉山次级块体在南东向运动时,以自身的逆时针旋转变形取代了块体内部的结构破坏和差异隆升,实现北部挤压至南部拉张的构造变形转换和整体抬升。  相似文献   

Selling only sustainable seafood: Attitudes toward public regulation and retailer policies     

《Marine Policy》2017

This study investigates consumer attitudes toward stores selling only sustainable seafood in seven European countries. Using a split sample design, half of the respondents were asked if they would support new regulations requiring stores to sell only sustainable labeled seafood. The other half was asked if they would continue to buy their seafood at their preferred seafood store if the store implemented a new policy of selling only sustainable labeled seafood. Respondents were on average positive to new sustainability regulations that increased prices by less than 7%, and would on average not change store unless prices increased by more than 8%. Country differences are investigated and implications for private and public policies related to sustainability of seafood discussed.  相似文献   

Three-dimensional analysis of rows of piles as passive barriers for ground vibration isolation   总被引：6，自引：0，他引：6  

G.Y. Gao  Z.Y. Li  Ch. Qiu  Z.Q. Yue 《Soil Dynamics and Earthquake Engineering》2006,26(11):1015-1027

This paper presents a theoretical study on the ground vibration isolation efficiency by multi-rows of piles as passive barrier in a three-dimensional context. Integral equations governing Rayleigh wave scattering are derived according to the Green's solution of Lamb problem. The integral equations are solved accurately and efficiently with an iteration technique. They are used to predict the complicated Rayleigh wave field that is generated by a number of irregular scatterers embedded in an elastic half-space solid. The method is verified with a numerical solution available in the literature for a simplified Rayleigh wave scattering problem. Passive isolation effectiveness of ground vibration with two or three rows of small piles is further studied in detail. Effects of relevant parameters on the effectiveness of vibration isolation are analyzed and presented.  相似文献   

Coherence and Scale of Vertical Velocity in the Convective Boundary Layer from a Doppler Lidar     

Marie Lothon  Donald H. Lenschow  Shane D. Mayor 《Boundary-Layer Meteorology》2006,121(3):521-536

We utilized a Doppler lidar to measure integral scale and coherence of vertical velocity w in the daytime convective boundary layer (CBL). The high resolution 2 μm wavelength Doppler lidar developed by the NOAA Environmental Technology Laboratory was used to detect the mean radial velocity of aerosol particles. It operated continuously in the zenith-pointing mode for several days in the summer 1996 during the “Lidars in Flat Terrain” experiment over level farmland in central Illinois. We calculated profiles of w integral scales in both the alongwind and vertical directions from about 390 m height to the CBL top. In the middle of the mixed layer we found, from the ratio of the w integral scale in the vertical to that in the horizontal direction, that the w eddies are squashed by a factor of about 0.65 as compared to what would be the case for isotropic turbulence. Furthermore, there is a significant decrease of the vertical integral scale with height. The integral scale profiles and vertical coherence show that vertical velocity fluctuations in the CBL have a predictable anisotropic structure. We found no significant tilt of the thermal structures with height in the middle part of the CBL.The National Center for Atmospheric Research is sponsored by the National Science Foundation.  相似文献