1,720,985 research outputs found
The soundscape of Mediterranean shallow water
No full textIn the marine environment, acoustic signals are source of information, crucial for inter and intra specific communication, i.e. during territorial and reproductive activities, orientation and habitat recognition. Soundscape analysis highlights the coexistence and the interconnection of all acoustic components, revealing different ecosystem processes.
The Mediterranean Sea comprises a plurality of ecosystems and shows a high degree of biological diversity. However, poor studies have been carried out to investigate if this ecological richness is reflected in the acoustic environment.
Objective of this work is to investigate the soundscape of Mediterranean coastal habitats in protected and impacted areas, with the aim of improving knowledge for the conservation of shallow waters habitats. Biological signals were described, together with their temporal and spatial patterns, and the impact of anthropogenic noise was estimated. Furthermore, the efficiency of the Acoustic Complexity Index (ACI), developed to study the acoustic complexity of terrestrial environment, was tested for Mediterranean coastal habitats.
In order to obtain a baseline of the Mediterranean coastal soundscape, the marine protected area of Lampedusa Island was monitored one year long. The soundscape is dominated over 2 kHz by snapping shrimps activity along all the year, following daily and seasonal patterns. The fish choruses characterize the frequencies below 2 kHz during the summer season. Results show that the presence of a protected zone does not preserve the acoustic space of species, since the boat noise masks during 46% of time sampled the frequency band used by soniferous fish. Moreover, the acoustic complexity index (ACI), applied in this Mediterranean shallow waters, was recognized as a good indicator for biological emissions, even if a major adjustment was needed to be applied to the marine environment.
In order to overcome this issue, I tested how ACI efficiency varies by adjusting its temporal resolution, applied during ACI computation, in relation to the different biological signals considered. Compared to terrestrial habitats, the soundscape of marine environment is characterized by manifold biophonical component in terms of type of signals (impulsive, tonal) and of frequency extent (from few Hz to hundreds kHz), that could influence index response. I found that higher temporal resolution was required for pulsed signals than for tonal sounds, while ACI efficiency for boat noise and geophonies did not change when a different temporal resolution was selected.
After to have demonstrated the functioning of the acoustic metrics in marine coastal environment, I applied them to study a high impacted area made up of the typical Posidonia oceanica meadow and sandy patches. Results showed that these two different habitats are characterized at the high and medium frequencies by distinct soundscapes and, the meadows have a more complex soundscape. New biological signals have been described for the first time and potentially attributed to both endemic and alien fish species.
Finally, a new approach to analyze the impact of noise in a shallow water environment has been carried out. The propagation of particle velocity generated by pile driving in an enclosed and simulated shallow sandy habitat resulted complexly related to the sound pressure transmission.
This thesis represents a base study for the future Mediterranean soundscape analysis, describing and characterizing different acoustic environments and their components. This first contribution paves the way for new questions and studies through different approaches. For example, the connection between the health status of the habitat and its soundscape complexity is poorly analyzed, and nowadays totally unknown in the Mediterranean marine system. The full comprehension of this relationship, mostly in key habitats, such as Posidonia oceanica meadows, could make the soundscape approach one of the most powerful tool to monitor of habitat changes under a growing human impact
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
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
The Importance of Empirical Particle Motion Measurements for Monitoring Underwater Noise from Wave Energy Converters
No full textThe energy transition to achieve NetZero objectives by 2050 2050 needs a sharp increase of Marine Renewable Energies (MREs). This growth must ensure environmental sustainability while aligning with biodiversity conservation goals, as outlined in the EU Biodiversity Strategy. However, significant knowledge gaps persist regarding the impacts of MREs on marine ecosystems, leading to uncertainties in assessing cumulative effects on marine organisms. Comprehensive monitoring and data collection are crucial to enable the sustainable development of MREs. Underwater noise is a recognized stressor associated with MRE devices, including Wave Energy Converters (WECs). It is also classified as an environmental quality indicator under Descriptor 11 of the Marine Strategy Framework Directive (EU), mandating its monitoring during anthropogenic activities as a potential pollutant for marine ecosystems. Standards for MRE devices noise assessment are now available (IEC TS 62600-40). Traditionally, underwater noise monitoring has focused on scalar pressure measurements. However, particle motion, a vectorial measure representing the acceleration or velocity of water particles caused by sound waves, is equally significant, especially in shallow water environments where WECs and their mooring systems may influence soundscapes more through vibration than pressure. Many marine organisms perceive sounds predominantly as particle motion rather than pressure due to their physiological characteristics (i.e. fish and invertebrates). This highlights the need to broaden current noise monitoring frameworks, which primarily focus on pressure, to incorporate particle motion measurements.
This paper emphasizes the importance of particle motion as a critical component of underwater noise monitoring for WEC applications. We present initial findings from empirical measurements of both particle motion and pressure conducted at a pilot site in the Mediterranean Sea using an underwater acoustic vector sensor (M20-105 system, GTI Geospectrum Technologies Inc.). Acoustic data were collected near the ISWEC (Inertial Sea Wave Energy Converter) off the coast of Pantelleria, Italy, offering novel insights into the underwater noise characteristics generated by WECs and the role of particle motion in their assessment
Motility and acoustic signals of the decapod Cherax destructor
No full textThe present study examined for the first time the sound production and motility of the freshwater decapod crustacean Cherax destructor. An acoustic and video system was used to monitor the behavior of 10 individual (5 males and 5 females) in an experimental tank. Video data were used to analyze three motility variables (velocity, distance moved, and angular velocity). Acoustic data were analyzed to obtain abundance and these acoustic parameters: duration, 1st and 2nd peak frequency, sound pressure level (SPL) and the bandwidth. Both males and females produced short-duration pulses that could be grouped into three categories, high, medium, and low frequency. Males showed a higher rate of emission of mid-frequency sounds than females. The sounds emitted by females had significantly higher 1st and 2nd peak frequencies (Mean± DS: F1= 23±32 kHz; F2= 17±20 kHz) than males (F1= 10±15 kHz Mean± DS; F2= 11±16 kHz), sound duration was also higher in females (10±7 ms) than in males (8±4 ms), otherwise, SPL was higher in males (133±5 dB re 1μParms) than in females (132±7 dBre 1 μParms). Concerning the motility, there is no particular differences in velocity and distance moved, on the contrary, angular velocity was greater in males (21±39 deg/s) than in females (18±41 deg/s). This study is part of a wider one on the behaviour associated with the production of sounds by these animals observed both individually and in groups and on the behavioural and biochemical responses to potential sources of anthropogenic noise disturbance
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
Noise accelerates embryonic development in a key crab species: Morphological and physiological carryover effects on early life stages
No full textAnthropogenic noise is considered one important global pollutant. The impact of noise on marine invertebrates has been less assessed. The present study evaluated the chronic effect of the motorboat noise obtained from a lagoon´s soundscape, the natural habitat of the key crab Neohelice granulata, on its whole embryonic development, considering morphological and physiological carryover effects on embryos and hatched larvae. Results demonstrated that embryonic development was shortened under noise exposure. The effects on advanced embryos, larvae and adult females were: increased heartbeats and non-viable eggs, and decreased fecundity. Biochemical responses showed lipid peroxidation in embryos while antioxidant enzymes were activated in larvae and adults, indicating a counteracting effect related to the life stage. The negative effects on fitness offspring may imply ecological consequences at the population level. Results are discussed in terms of the ecosystem engineer species studied and the habitat, a MAB UNESCO Reserve lagoon, suggesting the urgent need to develop mitigation plans.Fil: Sal Moyano, María Paz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Mitton, Francesca María. Instituto Nacional de Investigaciones y Desarrollo Pesquero; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Luppi, Tomas Atilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Snitman, Solana Morena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Nuñez, Jesus Dario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Lorusso, Martin Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Ceraulo, Maria. Consiglio Nazionale delle Ricerche; ItaliaFil: Gavio, Maria Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Buscaino, Giuseppa. Consiglio Nazionale delle Ricerche; Itali
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