LAGOON LITTER: PRELIMINARY APPROACH AND PROPOSAL OF SAMPLING METHODS FOR THE FUTURE IMPLEMENTATION OF WFD

Lagoons are one of the most productive ecosystems in the world, with unique hydrodynamic and ecological conditions. They provide many goods and services, otherwise they are located along coastal areas in which the anthropogenic pressures are very high, especially for what concerns plastic pollution. These transitional water ecosystems act as a trap for litter; in particular the impact of plastics could be higher with respect to marine litter because of the “trapping effect” of the lagoons. For this reason, the aims of this research are to analyze the methods for sampling plastics in respect to the dimension of the particles, sedimentation and suspension processes, and water circulation. Up to now, implementation methods for sampling plastics in order to measure their abundance and distribution are not well investigated, more efforts should be addressed in achieving consistency of the sampling techniques as well as standardization. The research was carried out in the Aquatina Lagoon (South Adriatic Sea, Apulia, Italy). The investigated plastics were divided in 3 main categories: microplastics (smaller than 5 mm), mesoplastics (between 5 mm and 2.5 cm) and macroplastics (bigger than 2.5 cm). The lagoon has been divided in different compartments that were separately considered and sampled: water surface, bottom and banks. Each compartment was sampled with different sampling methods such as: i) plankton net (200 μm) for the water surface, in order to have a better precision about the abundance and distribution of microplastic; ii) square method was applied for sampling bottom and banks. Bottom samples were collected using a grab while bank samples were collected by hand. Since the quantifying of the plastics is the first step to analyze the consequences of this anthropogenic impact on human-health, food chain, supply natural and goods and services of lagoons, here we propose and applied sampling methods for collecting plastics in different compartments and in order to catch the most common dimensional categories of plastic particles

Dependencies and Simultaneity in Membrane Systems

Membrane system computations proceed in a synchronous fashion: at each step all the applicable rules are actually applied. Hence each step depends on the previous one. This coarse view can be refined by looking at the dependencies among rule occurrences, by recording, for an object, which was the a rule that produced it and subsequently (in a later step), which was the a rule that consumed it. In this paper we propose a way to look also at the other main ingredient in membrane system computations, namely the simultaneity in the rule applications. This is achieved using zero-safe nets that allows to synchronize transitions, i.e., rule occurrences. Zero-safe nets can be unfolded into occurrence nets in a classical way, and to this unfolding an event structure can be associated. The capability of capturing simultaneity of zero-safe nets is transferred on the level of event structure by adding a way to express which events occur simultaneously

Optical measurements of phase steps in segmented mirrors - fundamental precision limits

Phase steps are an important type of wavefront aberrations generated by large telescopes with segmented mirrors. In a closed-loop correction cycle these phase steps have to be measured with the highest possible precision using natural reference stars, that is with a small number of photons. In this paper the classical Fisher information of statistics is used for calculating the Cramer-Rao bound, which determines the limit to the precision with which the height of the steps can be estimated in an unbiased fashion with a given number of photons and a given measuring device. Four types of measurement devices are discussed: a Shack-Hartmann sensor with one small cylindrical lenslet covering a sub-aperture centred over a border, a modified Mach-Zehnder interferometer, a Foucault test, and a curvature sensor. The Cramer-Rao bound is calculated for all sensors under ideal conditions, that is narrowband measurements without additional noise or disturbances apart from the photon shot noise. This limit is compared with the ultimate quantum statistical limit for the estimate of such a step which is independent of the measuring device. For the Shack-Hartmann sensor, the effects on the Cramer-Rao bound of broadband measurements, finite sampling, and disturbances such as atmospheric seeing and detector readout noise are also investigated. The methods presented here can be used to compare the precision limits of various devices for measuring phase steps and for optimising the parameters of the devices. Under ideal conditions the Shack-Hartmann and the Foucault devices nearly attain the ultimate quantum statistical limits, whereas the Mach-Zehnder and the curvature devices each require approximately twenty times as many photons in order to reach the same precision.Comment: 23 pages, 19 figures, to be submitted to Journal of Modern Optic

Romanesque and territory. The construction materials of Sardinian medieval churches: new approaches to the valorization, conservation and restoration

This paper is intended to illustrate a multidisciplinary research project devoted to the study of the constructive materials of the Romanesque churches in Sardinia during the “Giudicati” period (11th -13th centuries). The project focuses on the relationship between a selection of monuments and their territory, both from a historical-architectural perspective and from a more modern perspective addressing future restoration works. The methodologies of the traditional art-historical research (study of bibliographic, epigraphic and archival sources, formal reading of artifacts) are flanked by new technologies: digital surveys executed with a 3D laser-scanner, analyses of the materials (stones, mortars, bricks) with different instrumental methods: X-ray fluorescence (XRF) and inductively coupled mass spectrometry (ICP-MS) for chemical composition, X-ray diffractometer (XRD) to determine the alteration phases (e.g., soluble salts), optical microscopy and electronic (SEM) to study textures, mineral assemblages and microstructures, termogravimetric/differential scanning, calorimetric analysis (TG/DTA) for the composition of the binder mortars. This multidisciplinary approach allows the achieving of important results in an archaeometric context: 1) from a historical point of view, with the possible identification of ancient traffics, trade routes, sources of raw materials, construction phases, wall textures; 2) from a conservative point of view, by studying chemical and physical weathering processes of stone materials compatible for replacement in case of future restoration works. Sardinian Romanesque architectural heritage is particularly remarkable: about 200 churches of different types and sizes, with the almost exclusive use of cut stones. Bi- or poly-chromy, deriving from the use of different building materials, characterizes many of these monuments, becoming also a vehicle for political and cultural meanings. The paper will present some case studies aimed to illustrate the progress of the project and the results achieved

Leave-one-out prediction error of systolic arterial pressure time series under paced breathing

In this paper we show that different physiological states and pathological conditions may be characterized in terms of predictability of time series signals from the underlying biological system. In particular we consider systolic arterial pressure time series from healthy subjects and Chronic Heart Failure patients, undergoing paced respiration. We model time series by the regularized least squares approach and quantify predictability by the leave-one-out error. We find that the entrainment mechanism connected to paced breath, that renders the arterial blood pressure signal more regular, thus more predictable, is less effective in patients, and this effect correlates with the seriousness of the heart failure. The leave-one-out error separates controls from patients and, when all orders of nonlinearity are taken into account, alive patients from patients for which cardiac death occurred

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Relationships between size and abundance in beach plastics: A power-law approach

Sandy beaches are one of the most relevant coastal environments in terms of socio-ecological and economical value. So, the presence and accumulation of plastic litter determines a degradation of these values, and calls for management actions for cleaning are required. In this research, we investigated the features of plastic litter distribution on a Mediterranean beach in relation to size and abundance of the sampled items. Simple allometric models were applied with the aim to provide a parsimonious tool for estimating the amount and sizes of the beach plastic litter. The results show effective relations between size and abundance of plastic items according to the power-law distribution. This relationship could support decision-makers to estimate the total amount of beach plastics through the application of a simple model instead of more complex models requiring the estimation of many parameters and the availability of large datasets