35 research outputs found
Turning round the telescope. Centre-right parties and immigration and integration policy in Europe
This is an Author's Original Manuscript of 'Turning round the telescope. Centre-right parties and immigration and integration policy in Europe', whose final and definitive form, the Version of Record, has been published in the Journal of European Public Policy 15(3):315-330, 2008 [copyright Taylor & Francis], available online at: http://www.tandfonline.com/doi.org/10.1080/13501760701847341
Performing Values Practices and Grassroots Organizing: The Case of Solidarity Economy Initiatives in Greece
This article discusses solidarity economy initiatives as instances of grassroots organizing, and explores how âvalues practicesâ are performed collectively during times of crisis. In focusing on how power, discourse and subjectivities are negotiated in the everyday practices of grassroots exchange networks (GENs) in crisis-stricken Greece, the study unveils and discusses three performances of values practices, namely mobilization of values, re-articulation of social relations, and sustainable living. Based on these findings, and informed by theoretical analyses of performativity, we propose a framework for studying the production and reproduction of values in the context of GENs, and the role of values in organizing alternatives
An interlaboratory comparison of mid-infrared spectra acquisition: Instruments and procedures matter
Diffuse reflectance spectroscopy has been extensively employed to deliver timely and cost-effective predictions of a number of soil properties. However, although several soil spectral laboratories have been established worldwide, the distinct characteristics of instruments and operations still hamper further integration and interoperability across mid-infrared (MIR) soil spectral libraries. In this study, we conducted a large-scale ring trial experiment to understand the lab-to-lab variability of multiple MIR instruments. By developing a systematic evaluation of different mathematical treatments with modeling algorithms, including regular preprocessing and spectral standardization, we quantified and evaluated instruments' dissimilarity and how this impacts internal and shared model performance. We found that all instruments delivered good predictions when calibrated internally using the same instruments' characteristics and standard operating procedures by solely relying on regular spectral preprocessing that accounts for light scattering and multiplicative/additive effects, e.g., using standard normal variate (SNV). When performing model transfer from a large public library (the USDA NSSC-KSSL MIR library) to secondary instruments, good performance was also achieved by regular preprocessing (e.g., SNV) if both instruments shared the same manufacturer. However, significant differences between the KSSL MIR library and contrasting ring trial instruments responses were evident and confirmed by a semi-unsupervised spectral clustering. For heavily contrasting setups, spectral standardization was necessary before transferring prediction models. Non-linear model types like Cubist and memory-based learning delivered more precise estimates because they seemed to be less sensitive to spectral variations than global partial least square regression. In summary, the results from this study can assist new laboratories in building spectroscopy capacity utilizing existing MIR spectral libraries and support the recent global efforts to make soil spectroscopy universally accessible with centralized or shared operating procedures
Incubation experiments on net nitrogen mineralization in organic Greek soils
Aerobic incubation experiments were conducted in organic surface samples collected from arable soils of Philippoi, in Northern Greece. Laboratory experiments were carried out to investigate the nitrogen (N) mineralized from soils and sugar beet residues incorporated into the soils. Cumulative mineralization of N, potentially mineralizable nitrogen (N-0), and mineralization rate constant k were estimated after 30 continuous incubation weeks at 35 degrees C. Total N content of soils ranged between 6.6 and 19.2 g ka(-1), total soil carbon from 119 to 309 g kg(-1), soil organic carbon ranged from 119 to 308 g kg(-1), and the C:N ratio varied from 13.5 to 18.3. The cumulative net mineralized N ranged between 132 and 426 mg kg(-1) for nonamended soil and between 165 and 586 mg kg(-1) for residue-amended soil. Nitrate was the main form of mineralized N. although appreciable amounts of ammonium were measured. Potentially mineralizable nitrogen (NO) varied between 254 and 1067 mg kg(-1) for nonamended soil and 311-1465 mg N kg(-1) in residue-treated soil. The mineralization constant k was between 0.052 and 0.068 (week(-1)). Close relationships between total soil N and soil organic carbon, and between cumulative mineralization and total soil N were found. Mineralization occurred rather rapidly, although the amount of mineralized N per week was reduced in the later weeks of incubation. Variation in net mineralization among soil samples can be attributed to soil organic matter content, origin, and state of decomposition, as well as differences in management histories, and soil and microenvironmental conditions. Monitoring of mineralization process may ensure a basis for increasing nitrogen use efficiency
Assessing the efficiency of switchgrass different cultural practices for pellet production
Switchgrass is a perennial crop producing high amounts of biomass for good quality pellet production. The objective of this study is to examine the efficiency of different cultural practices of switchgrass for pellet production under field conditions for four different N-fertilization (0, 80, 160 and 240 kg ha(-1)) and two different irrigation levels (0 and 250 mm), in two soils in central Greece with rather different moisture status over the period 2009-2012. Moreover, comparison between three harvest methods (two different types of bales and silage) was made. The results derived from this study revealed that the bale at 22 kg is the harvesting practice with the highest costs while there was reduction of efficiency scores when nitrogen levels increased. At both environments the efficiency scores followed the same trend, confirming that low levels of nitrogen fertilization enhance the economic competitiveness of switchgrass production. Palamas site is the area where switchgrass for pellet production had positive income ranging from 400 to 1600 (sic)ha(-1), while Velestino site had always negative. Therefore, places like Velestino with non-aquic soil should be avoided for switchgrass. These data suggest that growing switchgrass for solid biofuel production as energy crop is a worthwhile decision only in areas with a moderately shallow groundwater table (aquic soil) or maybe in high precipitation regions. (C) 2014 Elsevier Ltd. All rights reserved