1,015 research outputs found

    Efficiency in European railways: Not as inefficient as one might think

    Get PDF
    The paper studies technical inefficiency in the railway systems of ten countries of the European Union. A new approach is used which permits the disaggregation of inefficiency by factor of production to result in estimates of input-specific technical inefficiency. The cost structure is represented using a generalized McFadden flexible functional form. Policy implications and guidelines for rational decision making in the railway sector, are discussed in detail.technical efficiency; symmetric generalized McFadden form; flexible functional forms; duality; input-specific technical efficiency; European railways

    The Hybrid Approach to Intervention of Chronic Total Occlusions

    Get PDF
    The "hybrid" approach to chronic total occlusion (CTO) percutaneous coronary intervention (PCI) was developed to provide guidance on optimal crossing strategy selection. Dual angiography remains the cornerstone of clinical decision making in CTO PCI. Four angiographic parameters are assessed: (a) morphology of the proximal cap (clear-cut or ambiguous); (b) occlusion length; (c) distal vessel size and presence of bifurcations beyond the distal cap; and (d) location and suitability of location and suitability of a retrograde conduit (collateral channels or bypass grafts) for retrograde access. Antegrade wire escalation is favored for short (<20 mm) occlusions, usually escalating rapidly from a soft tapered-tip polymer-jacketed guidewire to a stiff polymer-jacketed or tapered-tip guidewire. Antegrade dissection/re-entry is favored in long (≥20 mm long) occlusions, trying to minimize the dissection length by re-entering into the distal true lumen immediately after the occlusion. Primary retrograde approach is preferred for lesions with an ambiguous proximal cap, poor distal target, good interventional collaterals, and heavy calcification,as well as chronic kidney disease. The "hybrid" approach advocates early change between strategies to enable CTO crossing in the most efficacious, efficient, and safe way. Several early studies are demonstrating high success and low complication rates with use of the "hybrid" approach, supporting its expanding use in CTO PCI

    Use of denaturing gradient gel electrophoresis in screening unknown &beta;-thalassemia mutations in Egyptian patients

    Get PDF
    The molecular defects resulting in a &#946;-thalassemia phenotype, in the Egyptian population show a clear heterogenic pattern. Many studies have embarked on the molecular detection and characterization of these mutations, using a wide array of the available techniques with successful detection of both known and unknown mutations. PCR based techniques, as well as direct DNA sequencing are effective with some limitations as regards the time, effort and high cost to reach a final diagnosis. Intermediary screening techniques have proved to be effective tools to overcome these drawbacks. This study aims to assess the use of the denaturing gradient gel electrophoresis (DGGE)1 to detect b-thalassemia mutations prior to the performance of direct sequencing to minimize the cost and workload involved in the process. In this study, forty-two previously genotyped patients in a study by El-Gawhary et al. in 2007, have been analyzed by DGGE for fragment 2 then 1. These are the &#946;-globin gene fragments showing the majority of the &#946;-thalassemia mutations. Sixty-eight alleles out of 79 mutant alleles in total were detected within these two fragments. The 11 undetected alleles comprise 9 alleles that require further examination using other DGGE fragments (0, 4 and 5) and correspond to -87(C &gt; G), intervening sequence (IVS)II-1(G &gt;A), IVS II-745, and IVS II-848(C &gt; A). The remaining two that failed detection correspond to codon (CD) 37(G&gt; A). Although, IVS-II 745(C &gt;G) is undetectable within these two fragments, its 100% linkage polymorphism (+20 C&gt; T) was detected in fragment 1 gel. DGGE is a sensitive technique to screen for &#946;-thalassemia mutations. For simultaneous analysis of multiple samples with unknown mutations, it is recommended that direct DNA sequencing be coupled with DGGE whenever available to reduce time, effort and cost.Keywords: &#946;-Thalassemia; DGGE; PCR; Mutations; Polymorphism; Screenin

    An Application of the Coherent Noise Model for the Prediction of Aftershock Magnitude Time Series

    Get PDF
    Recently, the study of the coherent noise model has led to a simple (binary) prediction algorithm for the forthcoming earthquake magnitude in aftershock sequences. This algorithm is based on the concept of natural time and exploits the complexity exhibited by the coherent noise model. Here, using the relocated catalogue from Southern California Seismic Network for 1981 to June 2011, we evaluate the application of this algorithm for the aftershocks of strong earthquakes of magnitude M≥6. The study is also extended by using the Global Centroid Moment Tensor Project catalogue to the case of the six strongest earthquakes in the Earth during the last almost forty years. The predictor time series exhibits the ubiquitous 1/f noise behavior

    Collaborative governance networks: A case study of argentina’s forest law

    Get PDF
    Deforestation causes biodiversity loss and the eviction of small-scale ranchers and indigenous people. Accordingly, it is a global issue in environmental politics. This article analyzes a participatory governance system associated with the implementation of Argentina’s forest law in a hotspot of deforestation: the province of Salta in the Gran Chaco ecoregion. Specifically, this article investigates policy actors’ core beliefs, how they match with policy network clusters, and how this affects the implementation of the forest law. The study is based on a unique data set derived from extensive fieldwork and a network survey among all actors who participate in the policy forums. After defining three main core beliefs that describe policy actors’ motivations, we systematically analyze all key actors’ beliefs as well as their interactions in the various policy networks. This analysis shows that it is necessary to empirically identify coalitions based on both behavior and core beliefs to understand the limited implementation of the law. Our methodological approach holds promise for the analysis of other governance systems where multiple stakeholders engage in consensus-oriented decision-making

    Codifying and commodifying nature: Narratives on forest property rights and the implementation of tenure regularization policies in Northwestern Argentina

    Get PDF
    Environmental resource management requires negotiation among state and non-state actors with conflicting goals and different levels of influence. In northwestern Argentina, forest policy implementation is described as weak, due to governance structure and ambiguities in the law. We studied how policy actors’ attitudes and their positions in the forest governance network relate to the implementation of land tenure regularization in a context where land tenure regularization is at the core of struggles over environmental policies. We focused on the Chaco Salteño part of the Gran Chaco ecosystem, one of the world’s major deforestation frontiers. We argue that the presence of weak advocacy coalitions requires an analysis of agency to understand this policy process. Our policy network analysis revealed a lack of clear contrasting factions, due to a core–periphery structure. The core of the network brings together all core beliefs but not all of the most influential actors. Assessing network centrality and reputational influence enabled us to identify actors with exceptional agency. We contribute to the debates on advocacy coalitions and on land tenure by distinguishing between attitudes toward tenure regularization policies and their actual implementation in a context where actors have diverging interests and objectives
    • …
    corecore