712 research outputs found
[Recensione a:] Maurizio Mistri, The Euro Crisis. An Institutionalist Approach, Padova, Padova University Press, 2021, 196 pp.
No full textThe book by Maurizio Mistri deals above all with the complex institutional system of the EU and the Euroland in particular. As the author wrote ‘the euro is an opportunity to deal with a pivotal issue, namely the determination of institutional and supranational system to ensure the governance of economic and monetary integration processes’ (p. 9). Consequently, the purpose of the book is to present some analytical tools mainly derived from a careful use of Thomas Schelling’s contributions. The centrality that Mistri gives to the author of ‘The Strategy of Conflict’ (1960) is significant: Embracing the theoretical results reached by many economists and political scientists who have followed Shelling’s lesson, Mistri clearly brings out the controversial relationship between national institutions and supranational institutions in the European reality
Persistence of benthic communities: a case study from the Valli di Comacchio, a Northern Adriatic lagoonal ecosystem (Italy)
No full textData collected from a 3 yr continuing sampling program were used to study the persistence of the macrofaunal communities living in the Valli di Comacchio (44°41'N, 12°10'E), a complex of shallow-water brackish lagoons located in the southernmost part of the Po River deltaic area (Italy). Univariate and multivariate analyses were used to assess the variability and persistence of the community at each of the 4 sites investigated. A total of 46 benthic taxa were identified from bottom grab samples: Annelida was the most abundant group, followed by Crustacea and Mollusca. The abundance of some species exhibited marked temporal fluctuations. At 3 out of 4 sites, abundance fluctuation were unpredictable in terms of both timing and magnitude. There was little evidence that factors operating at lagoon-wide scale contributed to variability in community structure. The balance of taxa within each community was probably most affected by forcing factors acting on a local scale. The perception of macrofaunal communities as being persistent through time decreased as the analysis moved from coarser (presence/absence) to finer (absolute abundance) levels of numerical resolution. Analyses showed that macrobenthic assemblages at some sites were both persistent and variable: this paradox reflected viewpoints of different analytical scales. Because of this, a multi-level approach is probably more useful in gaining insight into community persistence and variabilit
Recensione a M. Mistri, La Città Metropolitana, Vicenza, La Gru, 2013, pp. 178
No full textquesto articolo evidenzia in modo analitico i problemi principali connessi al problema della confusa riforma
italiana in tema di Città metropolitane così come ben individuati dall'autore M. Mistri nel libro "La Città Metropolitana". Il problema della nascita della città metropolitana, intrecciandosi con la questione
del riassetto delle Province, suscita non pochi problemi di natura politica in
quanto coinvolge l’intera governance del territorio. L’Autore mette sotto la
lente critica i recenti provvedimenti che hanno toccato il sistema delle autonomie locali, i
quali dimostrano la mancanza di una reale e coerente visione riformatrice in materia.This article stress the main problems about the confusing Italian reform of metropolitan cities, as well identified by the author M. Mistri in the book "La Città Metropolitana"
Prey preference of Carcinus aestuarii: possible implications with the control of an invasive mytilid and Manila clam culture in a northern Adriatic lagoon
No full textThe cultivated Manila clam, Ruditapes philippinarum, and the accidentally introduced Asian date mussel, Musculista senhousia, are nowadays the most abundant bivalve species in the Sacca di Goro (northeastern Italy). M. senhousia, with its sub-surficial extended mats, creates quite a heavy economical impact to clam shellfish culture. Individual Mediterranean shore crabs Carcinus aestuarii were allowed to forage on the 2 bivalve species to examine crab's preference in light of the optimal foraging theory. Crabs preferred M. senhousia over R. philippinarum: mortality was higher for the former (34.6%) than for the latter bivalve species (9.5%). It is suggested that the marked preference of C. aestuarii for Asian date mussels over Manila clams could be advantageously exploited to control or to reduce the extension of mats, especially where these create management problems to infaunal, burrowing bivalve culture
Predatory behavior and preference of a successful invader, the mud crab Dyspanopeus sayi (Panopeidae), on its bivalve prey
No full textPredator-prey relationships between the panopeid crab, Dyspanopeus sayi, and the mytilid Musculista senhousia, were investigated. Through laboratory experiments, prey-handling behavior, prey size selection, predator foraging behavior, and preferences for two types of prey (M. senhousia and the Manila clam Ruditapes philippinarum), were assessed. Handling time differed significantly with respect to the three prey sizes offered (small: 15.0 - 20.0 mm shell length, SL, medium: 20.1 - 25.0 mm SL, and large: 25.1 - 30.0 mm SL); mud crabs were more efficient in predating medium-small than large prey. Although differences in prey profitability were not evident, D. sayi exhibited a marked reluctance to feed on larger-sized prey whilst smaller, more easily predated mussels were available. Size selection may be the result of a mechanical process in which encountered prey are attacked but rejected if they remain unbroken after a certain number of opening attempts. D. sayi exhibited inverse density-dependent foraging. A significant higher mortality of prey was evident at low prey density. Thus, at low predator density, the D. sayi-M. senhousia interaction was a destabilizing Type II functional response. Interference responses affected the magnitude of predation intensity by D. sayi on M. senhousia, since as the density of foraging crabs increased, their foraging success fell. At high density (4 crabs tank-1), crabs engaged in a high amount of agonistic activity when encountering a conspecific specimen, greatly diminished prey mortality. Finally, presenting two types of prey, Manila clam juveniles were poorly predated by mud crabs, which focused their predation mostly on M. senhousia. It is hypothesized that, when more accessible prey is available, mud crabs will have a minimal predatory impact on commercial R. philippinarum juvenile stock
Structure of a protozoan community in a percolating filter
No full textStructural factors of the microbial community of a percolating filter have been investigated. The presence of some ciliate species has been related to physico-chemical and plant operational variables by means of ordination procedures. In an 87-d study period, large variations in density of some species were observed. A limited number of environmental parameters strongly affect ciliate community composition. Major structural factors are sloughed biofilm wasting and nitrogen loading: both induce disturbance and make the community revert to a less mature phase. Moderate disturbance episodes reduce the effectiveness of competitive mechanisms. © 1994 Taylor & Francis Group, LLC
Foraging behaviour and mutual interference in the Mediterranean shore crab, Carcinus aestuarii, preying upon the immigrant mussel Musculista senhousia
No full textPredator-prey dynamics between the Mediterranean shore crab Carcinus aestuarii and the non-indigenous mussel Musculista senhousia were examined in laboratory experiments to assess the effects of varying predator and prey densities upon predator foraging rates and prey survival. The factorial design involved 3 predator and 3 prey densities, with 4 trial per treatment combination. Functional responses were differentiated statistically by analysis of the exponent of a general functional response model. Shore crabs displayed type II (decelerating rise to an upper asymptote) inversely density-dependent functional responses at low and moderate predator densities, while a nontraditional model was probably more appropriate at high predator density. No density-dependent refuge was observed for M. senhousia, whereas, at high predator density, mutual interference among crabs was evident and prey mortality was lowered. Mediterranean shore crab's combined functional and interference response, by affecting foraging rates, was important to the outcome of interactions between predators and the bivalve prey, and might play an important role in determining crab's predatory behaviour and dispersion and prey persistence in the fiel
F-IND: A framework to design fuzzy indices of environmental condition
No full textMultivariable indices of environmental conditions summarize the information provided by several biotic or abiotic variables into a single value of immediate interpretability, thus they are important instruments for monitoring. Developing new indices that combine different variables is not a trivial task: variables may be qualitative, or measured in different units, and the relationship between primitive components and quality may be ambiguous. Fuzzy logic has been repeatedly proposed as an effective technique to cope with such problems; however, the variety of choices that exist at each stage of the development of fuzzy models may present a problem for the index designer. In this paper we present F-IND, a framework to create fuzzy indices by means of a simplified and intuitive procedure. It allows to capture the expert knowledge of the system under study (air, soil, water) to easily generate a multivariable index of environmental conditions. F-IND is implemented in Java, to achieve an optimal portability on any operating syste
The non-indigenous mussel Musculista senhousia in an Adriatic lagoon: effects on benthic community over a ten year period
No full textThe Asian date mussel, Musculista senhousia (Mytilidae), is a good example of a species that has dispersed outwards from its native area through human-mediated transport, establishing sustainable populations in distant parts of the world. The date mussel, which is endemic in the Western Pacific region, appeared and became very abundant in the Sacca di Goro, a brackish lagoon in the Po River Delta (northern Adriatic Sea, Italy) in the early 1990s. Effects of M. senhousia on macrobenthic biodiversity were assessed over a 10 yr time period. At the study site, the increase in abundance and spread of M. senhousia resulted in an alteration of the pre-established macrobenthic community. Changes in benthic dynamics seemed apparent, through the inhibition of epifaunal, suspension-feeding taxa (Ficopomatus enigmaticus, Mytilaster minimus), and the enhancement of detritivores (Neanthes succinea, Streblospio shrubsolii, Microdeutopus gryllotalpa). It is hypothesized that the Asian date mussel was initially successful because it exploited a naturally disturbed, sparsely occupied environment, rather than interjecting itself among and displacing existing species. M. senhousia acted, at least initially, as a colonizer rather than an invade
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