195 research outputs found

    Using complementary visual approaches to investigate residency, site fidelity and movement patterns of the dusky grouper (Epinephelus marginatus) in a Mediterranean marine protected area

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    AbstractAssessing individuals' abundance, residency (presence at a site within a certain period) and site fidelity (tendency to return to the same site in subsequent seasons or years) is crucial for evaluating and improving the effectiveness of spatial conservation/management measures regarding ecologically and socio-economically valuable species. Using underwater visual census (UVC) and photo-identification (photo-ID) techniques, we estimated the abundance, residency and site fidelity of the dusky grouper, Epinephelus marginatus, at two protected sites within the Tavolara-Punta Coda Cavallo Marine Protected Area (Sardinia, Italy) in the summers of 2017–2018. The scope and spatio-temporal resolution of the study was extended by involving volunteer recreational divers in the photo collection. Grouper mean densities varied significantly across sampling dates, with a significant variability between the 2 years and the two investigated sites. At least 94 grouper visited the study sites in the summers of 2017–2018 based on the analysis of 968 high-quality photos using a semi-automated software to photo-identify individuals. Overall, the most frequently sighted grouper was recorded on 32 different days and 21 individuals (22%) identified in 2017 were re-sighted in 2018. The participation of volunteer recreational divers helped detect the inter-site (3.5–4 km apart) movements of a female and a male, supporting previous findings regarding the occurrence of reproduction-related movements. This study provides novel insights into the residency and site-fidelity patterns of the dusky grouper, and its small-scale movements probably related to reproduction. Specifically, we provide indications that effective protection from fishing should encompass the entire area used by grouper for reproductive movements

    First direct evidence of reproductive behaviour of the white grouper, Epinephelus aeneus (Geoffroy Saint-Hilaire, 1817)

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    This study describes the first ever reported direct observation of a pair spawning event and the reproductive liveries of the white grouper, Epinephelus aeneus. Spawning took place on a rocky bank located in the Marine Protected Area (MPA) of Tavolara-Punta Coda Cavallo (NE Sardinia, Italy), in the Western Mediterranean Sea. In the evening of August 4th, 2018, the spawning of two large-sized individuals (~90 cm total length), displaying distinct colour patterns, was observed using SCUBA diving. This direct observation is the first record of E. aeneus male reproductive livery, characterized by a darker coloration on the head, the dorsal part of the body and the caudal fin. In addition, information on the environmental conditions in which reproduction occurred was collected. At the study site, relatively high seawater temperatures were recorded at the time of the E. aeneus spawning (24 °C at 24.7 m), as well as over the 2018 summer months (July-September), even in deep waters (>35 m), compared to previous summers. The spawning event occurred in a coralligenous-dominated seascape where fishing is prohibited, while diving activities are allowed. The site hosts abundant populations of ecologically and commercially valuable fish species (e.g., groupers, sparid fishes), with significant proportions of large-sized individuals (i.e. reproducers). Further studies are needed to advance our knowledge of the white grouper, with a particular emphasis on reproduction and the importance of implementing effective protection measures. Prioritizing management actions at key reproductive sites, such as rocky banks, is essential for ensuring the protection and/or recovery of over-exploited species

    Nonlinear optical properties of Au–Ag nanoplanets made by ion beam processing of bimetallic nanoclusters in silica

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    The nonlinear absorption of Au–Ag nanoplanets made by Ar irradiation of bimetallic nanoclusters in silica has been experimentally investigated by means of the single beam z-scan technique. The measurements have been performed in the picoseconds regime in order to isolate the fast electronic contribution to the third-order nonlinearity. The results reveal large nonlinear absorption properties of these systems, characterized by the concomitance of saturable and reverse saturable absorption. A phenomenological expression has been developed to fit the z-scan curves and to quantitatively determine the nonlinear optical parameters

    The experience of regular exercise participation for women moving into their middle years : its nature, meaning and its benefits

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    This study added to the limited research on positive aspects of the human condition. It highlighted the perspective that women in western society recognise that there are wider health benefits to be taken from exercise than science suggests. Whilst this study acknowledged the customary fragmentary view, it took a holistic approach to exploring the nature and meaning of regular participation in exercise from the perspective of 41 women aged 30 to 50 years. This qualitative study included the views of regular participants in facility based and non-facility based exercise, along with the views of exercise instructors and the researcher. The study was contextualised within the traditional theories of related disciplines, namely health, women's studies, and exercise science. Also it was founded on the fitness industry's perspective on its service provision and its instructor training. Theory was compared with the experiences of a sector of the female population who, despite all the accepted calls on their time and energy, consistently maintained regular involvement in exercise. The study provided a holistic perspective on the nature, meaning and benefits of regular participation in exercise. Semi-structured interviews and focus groups were utilised in the data gathering process. In each case, the process consisted of a series of questions designed to explore a subjective perception of experience in accordance with the Neuro-Logical Levels process, a model from within the field of Neuro-Linguistic Programming (Dilts, 1990; Dilts, Hallbom and Smith, 1990; O'Connor and Seymour, 1995). This model acknowledges that behaviours and actions, witnessed on a surface level, are driven by internal systems, including personal beliefs and identity structures. It was utilised as an exploratory technique to identify unconscious triggers for behaviour. The use of this process in the interviews facilitated individual exploration of the research topic at increasingly deep levels of awareness. Focus groups demonstrated a consensus on, as well as further individual differences in, the beliefs, attitudes, experiences and feelings of the participants as they arose from the interactive context. The heuristic methodology utilised in the analysis and presentation of the data offered a holistic, person-centred and reflective perspective on the nature, meaning and benefits of exercise (Moustakas, 1990). Individual and exemplary portraits depicted the experience and personal meaning of exercise as it emerged from the data. Composite depictions conveyed the nature of exercise participation from the perspectives of participants and instructors. The researcher's involvement in the complete study facilitated the emergence of a creative synthesis of the essence of exercise. Exercise provided emotional and spiritual gains that extended beyond the traditional lifestyle benefits. Individuals indicated a range of 'special' qualities in exercise, along with benefits to the mind. They noted unique personal benefits and enhanced interpersonal relationships in all spheres of life. Regular participation in exercise greatly enhanced the lives of those involved and contributed to an individual and collective evolutionary process. Effective exercise delivery consisted of interactional and motivational elements beyond the scientific and mechanistic topics traditionally recognised in instructor training programmes and was founded on empathy, facilitation, passion, love and positive energy.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

    From sea monsters to charismatic megafauna: changes in perception and use of large marine animals

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    Marine megafauna has always elicited contrasting feelings. In the past, large marine animals were often depicted as fantastic mythological creatures and dangerous monsters, while also arousing human curiosity. Marine megafauna has been a valuable resource to exploit, leading to the collapse of populations and local extinctions. In addition, some species have been perceived as competitors of fishers for marine resources and were often actively culled. Since the 1970s, there has been a change in the perception and use of megafauna. The growth of marine tourism, increasingly oriented towards the observation of wildlife, has driven a shift from extractive to non-extractive use, supporting the conservation of at least some species of marine megafauna. In this paper, we review and compare the changes in the perception and use of three megafaunal groups, cetaceans, elasmobranchs and groupers, with a special focus on European cultures. We highlight the main drivers and the timing of these changes, compare different taxonomic groups and species, and highlight the implications for management and conservation. One of the main drivers of the shift in perception, shared by all the three groups of megafauna, has been a general increase in curiosity towards wildlife, stimulated inter alia by documentaries (from the early 1970s onwards), and also promoted by easy access to scuba diving. At the same time, environmental campaigns have been developed to raise public awareness regarding marine wildlife, especially cetaceans, a process greatly facilitated by the rise of Internet and the World Wide Web. Currently, all the three groups (cetaceans, elasmobranchs and groupers) may represent valuable resources for ecotourism. Strikingly, the economic value of live specimens may exceed their value for human consumption. A further change in perception involving all the three groups is related to a growing understanding and appreciation of their key ecological role. The shift from extractive to non-extractive use has the potential for promoting species conservation and local economic growth. However, the change in use may not benefit the original stakeholders (e.g. fishers or whalers) and there may therefore be a case for providing compensation for disadvantaged stakeholders. Moreover, it is increasingly clear that even non-extractive use may have a negative impact on marine megafauna, therefore regulations are needed.SFRH/BPD/102494/2014, UID/MAR/04292/2019, IS1403info:eu-repo/semantics/publishedVersio

    Introduzione alle Nanotecnologie e ai Nanosistemi

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    Presentare un quadro completo e scientificamente avanzato dello stato dell’arte nel settore delle nanotecnologie, che peraltro si sta velocemente e “quotidianamente” modificando, necessiterebbe della partecipazione nella stesura di esperti in differenti settori tecnologici, la produzione di un testo di rilevanti dimensioni, con tempi di consegna della versione finale non consistenti con il piano temporale inizialmente previsto per la pubblicazione. Questo peraltro non era lo scopo dell’AssoAutomazione nel realizzare la presente documentazione. Le finalità indicate dall’AssoAutomazione erano quelle di fornire, in particolare alle PMI, un quadro generale sulle prospettive offerte dalle nanotecnologie, evitando di introdurre tematiche scientifiche avanzate, che potranno essere approfondite rivolgendosi a Centri di Ricerca specialistici, citati nel testo, o consultando articoli scientifici e testi specifici nel settore di interesse, riportati nei riferimenti bibliografici, anche se non in forma esaustiva. Questo lavoro non è quindi configurato come un testo scientifico indirizzato al settore della ricerca avanzata, ma come una selezione introduttiva alle proprietà chimico-fisiche di determinati materiali nanostrutturati o di nanostrutture, che attualmente presentano specifiche applicazioni e che, in prospettiva, possono trovare nuove ricadute tecnologiche. Il livello di presentazione è stato quindi adeguato ad un lettore non esperto nel settore ma, piuttosto, interessato ai possibili campi di applicazione dei nanomateriali. Si è evitato di approfondire inoltre alcune tematiche, attualmente affrontate da grandi industrie italiane o straniere. Per specifici interessi in tali settori si suggerisce di fare riferimento alle Industrie operanti nelle corrispondenti aree tecnologiche. Abbiamo riportato, nella parte finale, l’indicazione di Centri, Laboratori ed Istituti Universitari operanti nei vari settori dei materiali nanostrutturati

    Optical properties of metal nanoclusters in dielectrics

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    In this work we present some results concerning the optical properties of metallic nanoclusters embedded in dielectric matrices. After a brief historical presentation of the theoretical approach to the comprehension of the light-particle interaction from a semi-classical point of view, we discuss some typical experimental cases where the interplay between structural and optical analysis demonstrated to be fundamental for a deeper understanding of the materials properties

    Potentialities of ion implantation for the synthesis and modification of metal nanoclusters

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    This work reviews the basic features of ion implantation as a tool for synthesizing and manipulating nanostructured materials with particular emphasis to nanocomposites made by dielectric matrices embedding metallic nanoparticles. After a brief introduction on the physics of ion implantation, two operating modes of ion implantation will be presented: the first is related to the direct synthesis of nanoclusters as resulting from the precipitation of the supersaturated solid solution produced by the implanted ions; the second is related to the modification induced by the ion beam on already formed nanostructures and is therefore referred to as indirect synthesis. Throughout the paper also various possible technological applications of the different kind of nanoclusters (mono-elemental or bimetallic) obtained by both approaches are presented: examples are given in the field of nonlinear optics, nanophotonics, magnetism and gas sensing

    A trip in the history and evolution of ion-exchange process

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    The aim of this paper is to present a short review on some aspects and applications of ion-exchange, process with some considerations “old age” of this technique
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