245 research outputs found

    Image Analysis for Facility Siting: a Comparison of Lowand High-altitude Image Interpretability for Land Use/land Cover Mapping

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    For two test sites in Pennsylvania the interpretability of commercially acquired low-altitude and existing high-altitude aerial photography are documented in terms of time, costs, and accuracy for Anderson Level II land use/land cover mapping. Information extracted from the imagery is to be used in the evaluation process for siting energy facilities. Land use/land cover maps were drawn at 1:24,000 scale using commercially flown color infrared photography obtained from the United States Geological Surveys' EROS Data Center. Detailed accuracy assessment of the maps generated by manual image analysis was accomplished employing a stratified unaligned adequate class representation. Both 'area-weighted' and 'by-class' accuracies were documented and field-verified. A discrepancy map was also drawn to illustrate differences in classifications between the two map scales. Results show that the 1:24,000 scale map set was more accurate (99% to 94% area-weighted) than the 1:62,500 scale set, especially when sampled by class (96% to 66%). The 1:24,000 scale maps were also more time-consuming and costly to produce, due mainly to higher image acquisition costs

    Reproductive biology of Pseudotocinclus tietensis (Siluriformes: Loricariidae: Hypoptopomatinae), a threatened fish species

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    Pseudotocinclus tietensis is endemic to the Upper TietĂȘ River basin and classified as vulnerable. The reproductive biology of this species is still unknown, therefore, we investigated its reproductive strategy and gonad development during its annual reproductive cycle. The fish were collected throughout one year, and histology of the gonads, fecundity and oocyte diameter was conducted. Three phases of gonad maturation were found in males and females (immature, developing, and spawning capable), and the development stages of the gametes were identified within each stage. In the testes, four stages of gamete development were distinguished: spermatogonia, spermatocytes, spermatids and spermatozoa. During spermiation, the spermatozoa were released into the tubular lumen and then continued through the efferent ducts. In the ovaries, five stages of gamete development were identified: chromatin nuclear, perinucleolar, yolk vesicle formation, vitellogenic and ripe. The minimum diameter of ovulating oocytes was 297 ”m, and the absolute fecundity was 64 to 306 oocytes. Males with spermatozoa in the lobular lumen and females with vitellogenic and ripe oocytes were found throughout the year. Pseudotocinclus tietensis has asynchronous ovarian development and gametes with fertilization capacity can be eliminated throughout the annual cycle

    Development of neutron resonance densitometry at the GELINA TOF facility

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    Neutrons can be used as a tool to study properties of materials and objects. An evolving activity in this field concerns the existence of resonances in neutron induced reaction cross sections. These resonance structures are the basis of two analytical methods which have been developed at the EC-JRC-IRMM: Neutron Resonance Capture Analysis (NRCA) and Neutron Resonance Transmission Analysis (NRTA). They have been applied to determine the elemental composition of archaeological objects and to characterize nuclear reference materials. A combination of NRTA and NRCA together with Prompt Gamma Neutron Analysis, referred to as Neutron Resonance Densitometry (NRD), is being studied as a non-destructive method to characterize particle-like debris of melted fuel that is formed in severe nuclear accidents such as the one which occurred at the Fukushima Daiichi nuclear power plants. This study is part of a collaboration between JAEA and EC-JRC-IRMM. In this contribution the basic principles of NRTA and NRCA are explained based on the experience in the use of these methods at the time-of-flight facility GELINA of the EC-JRC-IRMM. Specific problems related to the analysis of samples resulting from melted fuel are discussed. The programme to study and solve these problems is described and results of a first measurement campaign at GELINA are given.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

    Neutron cross-sections for advanced nuclear systems : The n-TOF project at CERN

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    © Owned by the authors, published by EDP Sciences, 2014 This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly citedThe study of neutron-induced reactions is of high relevance in a wide variety of fields, ranging from stellar nucleosynthesis and fundamental nuclear physics to applications of nuclear technology. In nuclear energy, high accuracy neutron data are needed for the development of Generation IV fast reactors and accelerator driven systems, these last aimed specifically at nuclear waste incineration, as well as for research on innovative fuel cycles. In this context, a high luminosity Neutron Time Of Flight facility, n-TOF, is operating at CERN since more than a decade, with the aim of providing new, high accuracy and high resolution neutron cross-sections. Thanks to the features of the neutron beam, a rich experimental program relevant to nuclear technology has been carried out so far. The program will be further expanded in the near future, thanks in particular to a new high-flux experimental area, now under construction.Peer reviewedFinal Published versio

    Cognitive style modulates semantic interference effects: evidence from field dependency

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    The so-called semantic interference effect is a delay in selecting an appropriate target word in a context where semantic neighbours are strongly activated. Semantic interference effect has been described to vary from one individual to another. These differences in the susceptibility to semantic interference may be due to either differences in the ability to engage in lexical-specific selection mechanisms or to differences in the ability to engage more general, top-down inhibition mechanisms which suppress unwanted responses based on task-demands. However, semantic interference may also be modulated by an individual’s disposition to separate relevant perceptual signals from noise, such as a field-independent (FI) or a field-dependent (FD) cognitive style. We investigated the relationship between semantic interference in picture naming and in an STM probe task and both the ability to inhibit responses top-down (measured through a Stroop task) and a FI/FD cognitive style measured through the embedded figures test (EFT). We found a significant relationship between semantic interference in picture naming and cognitive style—with semantic interference increasing as a function of the degree of field dependence—but no associations with the semantic probe and the Stroop task. Our results suggest that semantic interference can be modulated by cognitive style, but not by differences in the ability to engage top-down control mechanisms, at least as measured by the Stroop task
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