1,720,995 research outputs found
Sistema di visione e acquisizione sincronizzata per misurazioni dinamiche di livello in falde idriche
No full textL’obiettivo del lavoro è lo sviluppo di un sistema di visione e acquisizione sincronizzata per lo studio di una prova denominata slug test, eseguita per la determinazione dei parametri idrodinamici dei sistemi acquiferi. Il sistema ha permesso di mettere in evidenza e studiare alcuni fenomeni anomali che si riscontrano durante l’esecuzione della prova in campo. Per studiare le anomalie riscontrate durante l’esecuzione degli slug test meccanici, è stato realizzato in laboratorio un modello di piezometro trasparente. Per apprezzare le rapide variazioni idriche che si registrano durante la prova, il piezometro è stato attrezzato mediante sensori di pressione e telecamere sincronizzati e interfacciati a PC (Windows 2000)
The value of water mites (Hydrachnidia) as bioindicators of stream ecological status: an example from Abruzzo, central Italy
No full text
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
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
Benthic invertebrate assemblages and leaf-litter breakdown along the eucrenal–hypocrenal ecotone of a rheocrene spring in Central Italy: Are there spatial and seasonal differences?
No full textTo better understand the pattern of variation in biocomplexity of springs and first-order streams, it is essential to explore how the characteristics of spring communities may vary from the spring source (eucrenal) to the first reach of the originating springbrook (hypocrenal). For these reasons, we assessed spatial and temporal variation of crenic assemblages and leaf-litter breakdown along a 45-m reach of a spring–springbrook system in Central Italy. We found that physicochemical and hydrological parameters of Vera Spring did not vary significantly along the 45-m reach investigated. In contrast, total richness of assemblages was significantly higher at 20 and 45 m from the spring source, while abundances were more variable and did not show significant differences between seasons and among sites. The composition of assemblages did not show significant temporal trends in all sites investigated, while spatial differences along the eucrenal–hypocrenal ecotone were more prominent. The functional organization of assemblages was relatively stable in both space and time, and no spatial differences were observed in the rate of leaf-litter breakdown, though the dry mass loss of poplar leaves was slightly higher at the most downstream site. We conclude that immediately after groundwater emergence, spring communities are less stable and more variable while they tend to be better organized at short distance downstream. Small and gradual spatial changes in the strength of competitive interactions and predation pressures may have a fundamental role in structuring spring communities more than variation in abiotic parameters and/or differences in quantity and quality of food resources
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
Lenght-weight relationships for some plecoptera and ephemeroptera from a carbonate stream in central Apennine (Italy)
No full textThe relationship between dry weight and
body length for larvae of Plecoptera (Leuctra spp.,
Isoperla grammatica, Nemoura cinerea) and
Ephemeroptera (Baetis spp., Habrophlebia fusca,
Paraleptophlebia submarginata, Ecdyonurus helveticus,
Rhithrogena semicolorata), collected from a
carbonate stream in the Apennine (central Italy), is
reported. The power equation f(x) = AxB has been
applied to fit the curves of dry weight vs. body size
(length) in the ranges 0.03–13.00 mg and 2–14 mm,
respectively; a total of 674 larvae were examined.
The power model was in very good agreement with
experimental data. Moreover, the error between
measured and estimated weight was in the 4–20%
range. The data on Isoperla grammatica, Leuctra
spp., Rhithrogena semicolorata and Baetis spp. were
compared to those in a previous study in a different
geographical setting (south-western Germany’s Black
Forest) obtaining similar results but with lower
errors. We used and compared two methods: the
weighted least-square method (WLS) and an analysis
of covariance (ANCOVA). The values of the A and B
coefficients obtained with the two methods were very
similar (\6% discrepancy for either A or B). We
found the best fits for all the examined Plecoptera
(species, genus, and order level), while the results for
Ephemeroptera were varied, with loose fits at the
order level and also for Leptophlebiidae collectively
considered
Diel activity cycles of freshwater gastropods under natural light: Patterns adn ecological implications
No full textThough much is known about freshwater snail ecology, their circadian rhythms remain poorly
investigated. Well-fed, stress-free, mid-size adults of six species common in central Italian lakes were exposed
to natural sunlight and photoperiod, and their activity status was recorded at 3-h intervals during a 9-d indoor
experiment. All species exhibited evident diurnal habits despite high individual variability, with middayto-
early-afternoon activity peaks. Activity was correlated with diel light conditions but not with short-term
changes in albedo. The prosobranch Bithynia (=Codiella) leachii and the pulmonates Physa (=Physella) acuta
and Planorbis planorbis were the most active species and exhibited the longest-lasting response to daytime
food addition. The prosobranch Valvata piscinalis exhibited long periods retracted in its shell with the operculum
shut, and the remaining taxa (the pulmonates Galba (=Lymnaea) truncatula and Radix (=Lymnaea)
auricularia) exhibited an intermediate degree of activity. P. acuta was the most active species at night and
exhibited the quicker response to nighttime food addition. Alertedness to (diurnal) predators may be highest
for the highly active P. acuta and P. planorbis, whose antipredator defenses are mainly behavioral. Diel activity
patterns and other ecological characteristics suggest that P. acuta may be favored in food-rich habitats,
while V. piscinalis may not be able to fully exploit food resources, especially if in limiting quantities. All snail
species – and P. acuta in particular – may stimulate periphyton metabolism while keeping its biomass low by
grazing mainly during the time of maximum photosynthesis
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