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Search Results: 1 - 10 of 6935 matches for " Paolo Guidetti "
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Within-Otolith Variability in Chemical Fingerprints: Implications for Sampling Designs and Possible Environmental Interpretation
Antonio Di Franco, Fabio Bulleri, Antonio Pennetta, Giuseppe De Benedetto, K. Robert Clarke, Paolo Guidetti
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0101701
Abstract: Largely used as a natural biological tag in studies of dispersal/connectivity of fish, otolith elemental fingerprinting is usually analyzed by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). LA-ICP-MS produces an elemental fingerprint at a discrete time-point in the life of a fish and can generate data on within-otolith variability of that fingerprint. The presence of within-otolith variability has been previously acknowledged but not incorporated into experimental designs on the presumed, but untested, grounds of both its negligibility compared to among-otolith variability and of spatial autocorrelation among multiple ablations within an otolith. Here, using a hierarchical sampling design of spatial variation at multiple scales in otolith chemical fingerprints for two Mediterranean coastal fishes, we explore: 1) whether multiple ablations within an otolith can be used as independent replicates for significance tests among otoliths, and 2) the implications of incorporating within-otolith variability when assessing spatial variability in otolith chemistry at a hierarchy of spatial scales (different fish, from different sites, at different locations on the Apulian Adriatic coast). We find that multiple ablations along the same daily rings do not necessarily exhibit spatial dependency within the otolith and can be used to estimate residual variability in a hierarchical sampling design. Inclusion of within-otolith measurements reveals that individuals at the same site can show significant variability in elemental uptake. Within-otolith variability examined across the spatial hierarchy identifies differences between the two fish species investigated, and this finding leads to discussion of the potential for within-otolith variability to be used as a marker for fish exposure to stressful conditions. We also demonstrate that a ‘cost’-optimal allocation of sampling effort should typically include some level of within-otolith replication in the experimental design. Our findings provide novel evidence to aid the design of future sampling programs and improve our general understanding of the mechanisms regulating elemental fingerprints.
Intercultural education for citizenship in complex societies. Summary of the International Conference on Intercultural Education for citizenship. Educazione interculturale alla cittadinanza nella società complessa. Sintesi dei risultati del Convegno di studi internazionale: Educazione interculturale alla cittadinanza
Barbara Guidetti
Ricerche di Pedagogia e Didattica , 2009,
Abstract: Summary of the International Conference held on 15 and May 16, 2009 in Verona. An event planned at the end of a Research Project of National Interest (PRIN) designed to detect and promote the practices of education for democratic citizenship in Italian schools, following the guidelines of the Council of Europe on Education for Democratic Citizenship (EDC) and using the methodologies proposed in the "Tool for Quality Assurance of EDC in schools". Sintesi dei risultati del Convegno di studi internazionale svoltosi il 15 e il 16 maggio 2009 a Verona. Un evento ideato al termine di un Progetto di Ricerca di Interesse Nazionale (PRIN) finalizzato a rilevare e promuovere le pratiche di educazione alla cittadinanza democratica nelle scuole italiane, seguendo le linee guida del Consiglio d’Europa sull’Education for Democratic Citizenship (EDC) e utilizzando le metodologie proposte nel “Tool for quality assurance of EDC in schools”.
Parabolic problems with general Wentzell boundary conditions and diffusion on the boundary
Davide Guidetti
Mathematics , 2015,
Abstract: We show a result of maximal regularity in spaces of H\"older continuous function, concerning linear parabolic systems, with dynamic or Wentzell boundary conditions, with an elliptic diffusion term on the boundary.
Classical solutions to quasilinear parabolic problems with dynamic boundary conditions
Davide Guidetti
Mathematics , 2015,
Abstract: We study linear nonautonomous parabolic systems with dynamic boundary conditions. Next, we apply these results to show a theorem of local existence and uniqueness of a classical solution to a second order quasilinear system with nonlinear dynamic boundary conditions.
Dispersal Patterns of Coastal Fish: Implications for Designing Networks of Marine Protected Areas
Antonio Di Franco, Bronwyn M. Gillanders, Giuseppe De Benedetto, Antonio Pennetta, Giulio A. De Leo, Paolo Guidetti
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0031681
Abstract: Information about dispersal scales of fish at various life history stages is critical for successful design of networks of marine protected areas, but is lacking for most species and regions. Otolith chemistry provides an opportunity to investigate dispersal patterns at a number of life history stages. Our aim was to assess patterns of larval and post-settlement (i.e. between settlement and recruitment) dispersal at two different spatial scales in a Mediterranean coastal fish (i.e. white sea bream, Diplodus sargus sargus) using otolith chemistry. At a large spatial scale (~200 km) we investigated natal origin of fish and at a smaller scale (~30 km) we assessed “site fidelity” (i.e. post-settlement dispersal until recruitment). Larvae dispersed from three spawning areas, and a single spawning area supplied post-settlers (proxy of larval supply) to sites spread from 100 to 200 km of coastline. Post-settlement dispersal occurred within the scale examined of ~30 km, although about a third of post-settlers were recruits in the same sites where they settled. Connectivity was recorded both from a MPA to unprotected areas and vice versa. The approach adopted in the present study provides some of the first quantitative evidence of dispersal at both larval and post-settlement stages of a key species in Mediterranean rocky reefs. Similar data taken from a number of species are needed to effectively design both single marine protected areas and networks of marine protected areas.
Assessing Dispersal Patterns of Fish Propagules from an Effective Mediterranean Marine Protected Area
Antonio Di Franco, Giovanni Coppini, José Martin Pujolar, Giulio A. De Leo, Marino Gatto, Vladyslav Lyubartsev, Paco Melià, Lorenzo Zane, Paolo Guidetti
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0052108
Abstract: Successfully enforced marine protected areas (MPAs) have been widely demonstrated to allow, within their boundaries, the recovery of exploited species and beyond their boundaries, the spillover of juvenile and adult fish. Little evidence is available about the so-called ‘recruitment subsidy’, the augmented production of propagules (i.e. eggs and larvae) due to the increased abundance of large-sized spawners hosted within effective MPAs. Once emitted, propagules can be locally retained and/or exported elsewhere. Patterns of propagule retention and/or export from MPAs have been little investigated, especially in the Mediterranean. This study investigated the potential for propagule production and retention/export from a Mediterranean MPA (Torre Guaceto, SW Adriatic Sea) using the white sea bream, Diplodus sargus sargus, as a model species. A multidisciplinary approach was used combining 1) spatial distribution patterns of individuals (post-settlers and adults) assessed through visual census within Torre Guaceto MPA and in northern and southern unprotected areas, 2) Lagrangian simulations of dispersal based on an oceanographic model of the region and data on early life-history traits of the species (spawning date, pelagic larval duration) and 3) a preliminary genetic study using microsatellite loci. Results show that the MPA hosts higher densities of larger-sized spawners than outside areas, potentially guaranteeing higher propagule production. Model simulations and field observation suggest that larval retention within and long-distance dispersal across MPA boundaries allow the replenishment of the MPA and of exploited populations up to 100 km down-current (southward) from the MPA. This pattern partially agrees with the high genetic homogeneity found in the entire study area (no differences in genetic composition and diversity indices), suggesting a high gene flow. By contributing to a better understanding of propagule dispersal patterns, these findings provide crucial information for the design of MPAs and MPA networks effective to replenish fish stocks and enhance fisheries in unprotected areas.
Large-Scale Assessment of Mediterranean Marine Protected Areas Effects on Fish Assemblages
Paolo Guidetti, Pasquale Baiata, Enric Ballesteros, Antonio Di Franco, Bernat Hereu, Enrique Macpherson, Fiorenza Micheli, Antonio Pais, Pieraugusto Panzalis, Andrew A. Rosenberg, Mikel Zabala, Enric Sala
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0091841
Abstract: Marine protected areas (MPAs) were acknowledged globally as effective tools to mitigate the threats to oceans caused by fishing. Several studies assessed the effectiveness of individual MPAs in protecting fish assemblages, but regional assessments of multiple MPAs are scarce. Moreover, empirical evidence on the role of MPAs in contrasting the propagation of non-indigenous-species (NIS) and thermophilic species (ThS) is missing. We simultaneously investigated here the role of MPAs in reversing the effects of overfishing and in limiting the spread of NIS and ThS. The Mediterranean Sea was selected as study area as it is a region where 1) MPAs are numerous, 2) fishing has affected species and ecosystems, and 3) the arrival of NIS and the northward expansion of ThS took place. Fish surveys were done in well-enforced no-take MPAs (HP), partially-protected MPAs (IP) and fished areas (F) at 30 locations across the Mediterranean. Significantly higher fish biomass was found in HP compared to IP MPAs and F. Along a recovery trajectory from F to HP MPAs, IP were similar to F, showing that just well enforced MPAs triggers an effective recovery. Within HP MPAs, trophic structure of fish assemblages resembled a top-heavy biomass pyramid. Although the functional structure of fish assemblages was consistent among HP MPAs, species driving the recovery in HP MPAs differed among locations: this suggests that the recovery trajectories in HP MPAs are likely to be functionally similar (i.e., represented by predictable changes in trophic groups, especially fish predators), but the specific composition of the resulting assemblages may depend on local conditions. Our study did not show any effect of MPAs on NIS and ThS. These results may help provide more robust expectations, at proper regional scale, about the effects of new MPAs that may be established in the Mediterranean Sea and other ecoregions worldwide.
On real interpolation, finite differences, and estimates depending on a parameter for discretizations of elliptic boundary value problems
Davide Guidetti,Sergei Piskarev
Abstract and Applied Analysis , 2003, DOI: 10.1155/s1085337503306359
Abstract: We give some results concerning the real-interpolation method andfinite differences. Next, we apply them to estimate theresolvents of finite-difference discretizations of Dirichletboundary value problems for elliptic equations in spacedimensions one and two in analogs of spaces of continuous andHölder continuous functions. Such results were employed tostudy finite-difference discretizations of parabolic equations.
Identification of a convolution kernel in a control problem for the heat equation with a boundary memory term
Cecilia Cavaterra,Davide Guidetti
Mathematics , 2013, DOI: 10.1007/s10231-012-0301-y
Abstract: We consider the evolution of the temperature $u$ in a material with thermal memory characterized by a time-dependent convolution kernel $h$. The material occupies a bounded region $\Omega$ with a feedback device controlling the external temperature located on the boundary $\Gamma$. Assuming both $u$ and $h$ unknown, we formulate an inverse control problem for an integrodifferential equation with a nonlinear and nonlocal boundary condition. Existence and uniqueness results of a solution to the inverse problem are proved.
The Small GTPase Rap1b: A Bidirectional Regulator of Platelet Adhesion Receptors
Gianni Francesco Guidetti,Mauro Torti
Journal of Signal Transduction , 2012, DOI: 10.1155/2012/412089
Abstract: Integrins and other families of cell adhesion receptors are responsible for platelet adhesion and aggregation, which are essential steps for physiological haemostasis, as well as for the development of thrombosis. The modulation of platelet adhesive properties is the result of a complex pattern of inside-out and outside-in signaling pathways, in which the members of the Rap family of small GTPases are bidirectionally involved. This paper focuses on the regulation of the main Rap GTPase expressed in circulating platelets, Rap1b, downstream of adhesion receptors, and summarizes the most recent achievements in the investigation of the function of this protein as regulator of platelet adhesion and thrombus formation. 1. Introduction The adhesion of circulating blood platelets to the subendothelial matrix exposed upon vessel wall injury represents the initial event of the haemostatic process required to limit hemorrhage. Platelets express several membrane receptors specific for all the major adhesive ligands of the vascular extracellular matrix [1]. Among these, collagen is probably the most important subendothelial matrix component involved in thrombus formation, and platelet adhesion to collagen is associated with a complex pattern of activatory signaling pathways. Integrin α2β1 and glycoprotein VI (GPVI) are the two main platelet receptors for collagen and, in the rheological conditions of low shear rates, typically present in large veins and venules, are sufficient to mediate firm platelet adhesion. At high shear rates, characteristic of small arteries and stenotic vessels, platelets are unable to efficiently interact to exposed collagen fibers, and in these conditions adhesion is preceded by platelet tethering and rolling on the site of injury. This process is mediated by the membrane GPIb-IX-V complex, a platelet-specific receptor for the multimeric glycoprotein von Willebrand factor (VWF). At high shear stress, circulating VWF rapidly interacts with exposed collagen fibers and undergoes a conformational change that allows the interaction with the GPIb-XI-V complex, decelerating platelets and favoring the subsequent stable adhesion mediated by other platelet receptors [2]. The interaction of platelet adhesion receptors with subendothelial matrix components stimulates an intricate pattern of signal transduction pathways, that trigger spreading, secretion of soluble proaggregating molecules, thromboxane A2 (TxA2) synthesis and release, and phosphatydilserine exposure. These events recruit and activate additional circulating platelets to initiate a
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