1,721,022 research outputs found
Role of density and resource competition in determining aggressive behavior in salamanders
No full textIntraspecific aggression is an important aspect of social behaviour that can significantly affect individual survivorship and population dynamics. Aggressiveness may be particularly important in food-deprived habitats, like caves, but few studies have investigated behavioural and ecological determinants of aggressiveness and cannibalism in cave vertebrates. In this study, we evaluated the role of density, competition for food, starvation and rearing history under cave-like conditions in promoting aggression. We performed a behavioural experiment on larvae collected from multiple underground springs and neighbouring streams, and we reared them under two different settings: total darkness and outdoor conditions. Intraspecific attacks were very scarce in hatchlings, and increased after 1 month. Starvation periods and high density clearly increased aggressiveness. Furthermore, aggressiveness strongly increased under competition conditions (presence of other larvae feeding). Aggressiveness increased with age more quickly in larvae from caves than in those from streams. Environmental features typically experienced by cave populations, such as starvation and high density, increase intraspecific attacks and might promote cannibalism. Strong plasticity for aggression may enhance the possibility to successfully colonize and exploit food-deprived environments where no other predators can survive, such as underground environments
Odonata occurrence in caves: active or accidentals? A new case study
Full text linkCaves are environments that host unique faunas and may be important for rganisms not exclusively dependent on caves. The occurrence of epigean taxa in caves is
often considered accidental, but their study can provide useful information on cave colonization. Records of Odonata underground are extremely scarce. We have identified larvae of Cordulegaster bidentata in two caves, one natural and one artificial, from Lombardy in northwestern Italy. They occurred in pools near the cave entrance that have
84 lux of maximum illuminance, reached in early spring. In both caves we found a high
density of larvae, and some of them were at very advanced instars. They had an
important role in the cave’s trophic web, exerting a high predation pressure on larvae of the salamander Salamandra salamandra. The plasticity of some Odonata species may allow them to take advantage of underground spring
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
New Insights for Health and Environmental Impact Assessment of PM Released by Specific Emission Sources
Full text linkThis study is aimed to improve the knowledge about the association between health and environmental effects of particulate matter (PM) and its chemical composition and sources and it is focused on the integration of different observation systems and monitoring techniques. PM samples originated from different sources were collected and analyzed by traditional and innovative analytical methods, thus reaching a very detailed knowledge of their inorganic and organic chemical composition.
(A) Acellular assays: 1,4-dithiothreitol (DTT), ascorbic acid (AA) and 2',7'dichlorodihydrofluorescein (DCFH), able to give information about PM capacity to generate oxidative stress, were applied to PM-selected components to estimate the oxidative potential (OP) of PM released by different emission sources (A1). Plant and animal model organisms were exposed in vivo under controlled conditions to the PM-selected components. Oxidative stress and other biological responses were evaluated and correlated to the OP and chemical composition of PM and the reliability of the OP methods as proxies of the production of reactive oxygen (ROS) and nitrogen (RNS) species was assessed (A2, A3). Furthermore, the potential of NO to restore the cellular balance between the ROS and the RNS in the root system of a plant species exposed to As and Cd was evaluated (A4).
(B) To obtain valuable information for PM source apportionment and thus for the assessment of health and climate impact, a chemical/size fractionation method was applied to sampling campaigns carried out for seven consecutive years in the Po Valley (Northern Italy) (B1). PM10 and size-segregated PM samples collected in workplaces (B2) and in indoor environments of private dwellings (B3) were analyzed to investigate the health impact of particles emitted in different size fractions by specific indoor sources.
(C) Innovative and very-low volume samplers were used for high spatial resolution analyses of PM chemical components in the Terni basin (Central Italy), which can be considered as an open air laboratory for studying the spatial distribution of PM, since it is characterized by atmospheric stability and by the presence of several anthropic PM sources (C1, C2, C3). The impact of local emission sources was assessed and the spatial variability of PM element concentrations was mapped (C3) and compared with the results achieved by biomonitoring through lichen transplants (C4) and leaf deposition on riparian species (C5), to verify the reliability of biomonitoring techniques for the assessment of atmospheric element concentrations. The experimental approach, based on the mapping of spatially-resolved PM chemical data, is a powerful tool for a reliable assessment of population exposure to PM air pollutants and also promises to be effective for optimization and validation of dispersion models. This approach, combined with on-site human biomonitoring will allow further investigations on the relationships between health effects and PM chemical composition and sources.
(D) To investigate relationships between health effects and PM chemical composition and sources, the suitability of different biological matrixes for on-site human biomonitoring exposure to environmental pollution was evaluated. Rapid analytical methods for routine elemental analysis of a significant number of human hair samples were developed and validated (D1, D2). Moreover, Hg As, Pb and Cd levels in breast milk were assessed to provide valuable information on the maternal toxic load and to be used as an indicator for prenatal and post-natal exposure of infants to these chemicals. In addition, we assessed the capacity of a multi-strain probiotic to protect the infants from their exposure (D3).
(E) Finally, during the PhD research, environmental remediation techniques for inorganic and organic pollutants were investigated. The potential of food waste materials as low-cost adsorbents for the removal of toxic elements, heavy metals (E1) and volatile organic compounds (E2, E3) from wastewater was evaluated. The adsorption capacity of food waste materials was assessed by comparing the removal efficiency of elements and VOCs from complex solutions, maintaining homogeneous experimental conditions, which allowed us comparing the adsorption capacity of the individual sorbents
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Fringe parks, green spaces and urban forestry in Milano (Italy): state of the art and future development
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