117,675 research outputs found
Risk-based prioritization methodology for the classification of groundwater pollution sources
No full textWater management is one of the EU environmental priorities and it is one of the most serious challenges that today's major cities are facing. The main European regulation for the protection of water resources is represented by the Water Framework Directive (WFD) and the Groundwater Directive (2006/118/EC) which require the identification, risk-based ranking and management of sources of pollution and the identification of those contamination sources that threaten the achievement of groundwater's good quality status. The aim of this paper is to present a new risk-based prioritization methodology to support the determination of a management strategy for the achievement of the good quality status of groundwater. The proposed methodology encompasses the following steps: 1) hazard analysis, 2) pathway analysis, 3) receptor vulnerability analysis and 4) relative risk estimation. Moreover, by integrating GIS functionalities and Multi Criteria Decision Analysis (MCDA) techniques, it allows to: i) deal with several sources and multiple impacted receptors within the area of concern; ii) identify different receptors' vulnerability levels according to specific groundwater uses; iii) assess the risks posed by all contamination sources in the area; and iv) provide a risk-based ranking of the contamination sources that can threaten the achievement of the groundwater good quality status. The application of the proposed framework to a well-known industrialized area located in the surroundings of Milan (Italy) is illustrated in order to demonstrate the effectiveness of the proposed framework in supporting the identification of intervention priorities. Among the 32 sources analyzed in the case study, three sources received the highest relevance score, due to the medium-high relative risks estimated for Chromium (VI) and Perchloroethylene. The case study application showed that the developed methodology is flexible and easy to adapt to different contexts, thanks to the possibility to introduce specific relevant parameters identified according to expert judgment and data availability
A fast code using nonmagnetic measurements for RFX current and magnetic field profile reconstruction
No full textFast identification techniques of the plasma internal magnetic structure are needed for the real time control of the plasma current distribution in magnetic confinement devices. In this paper, a fast identification code using plasma internal nonmagnetic measurements is proposed and applied to the reversed field pinch experiment. The identification tool is based on a force-free ideal magnetohydrodynamic equilibrium model, using a parametric radial profile for the magnetic field and current density. A set of constraints on the internal magnetic distribution are derived from the Faraday rotation data given by a five-chord polarimeter, assuming the plasma density as given by an interferometric diagnostic. The code execution time is about a few second
Fattori di rischio perinatali, socio-economici ed infettivi per la malattia celiachia: uno studio di coorte di nascita attraverso record-linkage di flussi informativi correnti.
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Workflow for the Assessment of ITER Plasma Control System Design
No full textThe plasma control system (PCS) for the first nonactive ITER operation phase will require simultaneous active monitoring and control of many continuous and discrete quantities. Considering the unique challenges ITER will face, all the controllers will be integrated and deployed with very little experimental time dedicated to PCS tuning and development. In order to maximize the efficiency of the ITER PCS design, a formal system engineering approach has been adopted. In a simplified way, the design process starts with the definition of the requirements. Functionalities are then designed and developed in order to meet these requirements. As a last step in the design process, it is important to assess that all the designed functionalities meet the associated requirements and that all the requirements are covered. The many different control functions will be designed and implemented in ITER PCS simulation platform (PCSSP) by different designing teams, both internal and external to ITER Organization. Although each team will be responsible for the independent assessment of the modules they deliver, an extra step is, nevertheless, necessary to guarantee that all the modules still continue to work when connected together. Therefore, integrated assessments will be built from independent assessments and will prove the controllers continue to meet the requirements. For this reason, it is necessary to have a unified workflow for the assessments performed by all the different designing teams. In fact, in order to guarantee a smooth integration assessment, it is important that all the assessments follow the same rules, use the same tools, are provided with the correct information, and are performed on the same platform. In this article, we present the proposed assessment workflow for ITER PCS components and some early impressions gathered from assessments of first delivered modules
A life cycle assessment study of European Space Agency's space tracking terminal
No full textThe transition to a low-carbon and resource-efficient circular economy is a political pillar of the EU and a priority for space agencies. Indeed, the space industry is pursuing sustainable development practices to reduce the environmental impacts. Life Cycle Assessment (LCA) is internationally recognized as the most appropriate methodology to estimate the environmental impacts of products, processes, and services and to evaluate the effectiveness of sustainability strategies related to reducing these negative externalities. To support the European Space Agency (ESA) in the process of planning more sustainable eco-design solutions, the objective of this paper is the development of a cradle-to-grave screening LCA study to assess the environmental impacts concerning the ESA's ground-based satellite tracking system based in New Norcia (AU) along its entire life cycle, including the tracking antenna and the photovoltaic panels. This scenario has been compared with 2 other scenarios to verify whether the use of photovoltaic panels has a benefit in terms of environmental impact (scenario A) and to understand the consequences in changing the location of the station, from New Norcia to Cebreros (E) by considering the change in the national energy mix from the Australian to the Spanish (scenario B). This study is one of the first attempts to apply the LCA methodology to the space sector, and its results, conducted according to ISO 14040/44 2021 guidelines and by means of the ReCiPe calculation method (2016), will be exploited by the ESA to plan a more sustainable eco-design for the construction of future space tracking stations
Poloidal magnetic field measurements in a reversed field pinch plasma by a far-infrared polarimeter
No full textA multichannel far-infrared (FIR) polarimeter has been installed in RFX, a Reversed Field Pinch (RFP) plasma experiment, to measure the poloidal magnetic field profile. The polarimeter uses a CH3OH FIR laser operating at lambda=118.8 mgrm. Faraday rotation measurements on five of six parallel diagnostic chords are used in preliminary investigations of poloidal field profiles. The experimental results are generally found in good agreement with the mu&p model predictions. The choice of the profile of mu = mu0 j·B/B2 is discussed. For the reconstruction of the magnetic field profiles a numerical filamentary current equilibrium code is described, where polarimetric data are included as constraints. An alternative method based on the best-fit of a three-parameter mu profile to the polarimetric data is also reported. Both methods provide reliable reconstructions of the plasma magnetic field and the results indicate the existence in RFX of hollow mu profiles
Square Dancing with the Stars to Enhance Dynamic Hirschman Linkages?
No full textIn this Presidential Address, the author takes the reader on a reconnaissance of his life and time as a regional scientist. He points out scenery he found scintillating along the way, hoping that some may pick up the banner and chew on a few of the ideas for a while. He suggests a revisit to Albert O. Hirschman’s notion of key sectors and more empirical analysis related to Marcus Berliant’s and Masahisa Fujita’s notion of knowledge creation and transfer.Presidential Address, San Antonio, Texas, March 29, 2014 (53rd Meetings of the Southern Regional Science Association
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Revealing the architecture and composition of the sperm flagellum tip
No full textThe eukaryotic flagellum is a membrane-bound protruding organelle with a cytoskeleton of microtubules. Flagella are found in unicellular as well as multicellular organisms, performing a variety of functions. Motile flagella enable cell locomotion, like in protists or spermatozoa, but can also create flows of fluids or mucus, like in respiratory airways. Flagella also act as cellular “antennas”, as their surface can probe the environment with sensorial receptors. The flagellar ultrastructure is often regarded as widely conserved among eukaryotes, however significant differences have been reported for the structure of the distal flagellar tip between organisms. The tip is where the flagellum grows and where intra-flagellar transport must unload and load cargo, making it a hub of flagellar-specific processes that are still relatively under-explored.
In humans, genetic mutations that impair proper flagellar function cause primary ciliary dyskinesia, a collective term for numerous pathologies which are still not fully characterized. To elucidate the ultrastructure of the human flagellar tip, we performed cryo-electron tomography on intact spermatozoa, plunge-frozen in their native environment. The results revealed drastic differences compared to commonly studied model organisms. Additionally, a novel extensive structure (named TAILS) was discovered decorating the lumen of sperm tip microtubules. These results together highlight the power of cryo-electron tomography in displaying complex cellular structures in their native environment, as well as the importance of studying the human system directly.
Lastly, a multi-pronged approach was designed to biochemically identify and characterize TAILS, based on a reverse structural biology perspective. This included obtaining high-resolution structures of TAILS produced with different cryo-electron microscopy techniques, the first ever flagellar tip proteome and an evolutionary overview of TAILS conservation
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