A multidisciplinary geophysical approach to recognize and quantify the gas occurrence in the Northern Adriatic

L'Adriatico settentrionale \ue8 caratterizzato da una presenza diffusa di gas nel sottosuolo, testimoniata da vari segni distintivi sul fondo mare e nei sedimenti sottostanti. Nel 2009 e nel 2014, OGS ha effettuato nell'area due campagne di sismica a riflessione 2D , finalizzate ad indagare la relazione tra le emissioni di gas, i cammini di migrazione e l'assetto geologico della regione. Inoltre, si voleva caratterizzare da un punto petrofisico i fluidi all'interno della successione sedimentaria. In questa tesi, due linee sismiche perpendicolari del dataset sono state selezionate ed analizzate. L'obiettivo era la determinazione della distribuzione del gas e la stima della sua concentrazione lungo le due linee sismiche, all'interno della successione sedimentaria Plio-Quaternaria e correlando log di pozzo e attributi sismici. Un approccio multidisciplinare \ue8 stato applicato sia nell'analisi che nell'interpretazione dei dati, integrando l'informazione geologica e quella geofisica. La caratterizzazione del gas nell'area di studio ha due implicazioni importanti: 1) Una valutazione complessiva della presenza di gas e della sua dinamica di migrazione all'interno della successione sedimentaria pu\uf2 vincolare il ruolo delle strutture tetttoniche identificate 2) L'approccio innovativo e multidisciplinare usato pu\uf2 essere applicato in altre aree di studio, caratterizzate dalla presenza di gas nei sedimenti e in simili assetti geologici. Inoltre, considerato il fondale molto basso dell'area, il trasferimento di gas dai sedimenti alla colonna d'acqua e nell'atmosfera potrebbe essere rapido e significativo. Comprendere a fondo i meccanismi di fuoriuscita di gas ha quindi importanti implicazioni climatologiche, dato che il metano, il componente principale del gas nell'area, ha un ruolo di spicco come gas serra.The Northern Adriatic is characterized by widespread occurrence of gas in the subsurface, testified by the presence of fluid related seabed and sub-seabed features (Donda et al., 2015, and references therein). In 2009 and 2014 OGS carried out two 2D multichannel seismic surveys in the area to constrain the relationship between gas emissions, migration paths and the regional geological setting. A further aim was to characterize the gas-charged fluids occurring within the sedimentary succession. Two seismic lines from these datasets were analyzed in the framework of this PhD thesis (GEA project, \u2019Gas Emissions in the Northern Adriatic Sea\u2019). The objective of this thesis is to determine the distribution of gas and estimate its concentration along the two selected perpendicular seismic profiles within the Plio-Quaternary sedimentary succession, through the petrophysical characterization of the sediments with the use of well-log to seismic attributes correlation. A multidisciplinary approach was applied both in the analysis and in the interpretation of the data, through the integration of geological information with geophysical wireline logs and seismic data. The proper characterization of the gas occurrence in the study area has two direct implications: 1. The comprehensive evaluation of both the gas occurrence and its migration within the sedimentary succession will constrain the role of the identified tectonic features; 2. The innovative and multidisciplinary approach used in this thesis could be applied to other areas characterized by gas-charged fluids in similar geological settings. Moreover, due to the shallow water in the Northern Adriatic, the potential transfer of gas from sediment to the water column and then into the atmosphere could be significant. Therefore, understanding the mechanisms of natural gas seepage has important climatological implications, since methane, the main component of the gas in the area (Donda et al., accepted), plays a major role as a greenhouse gas

Quality-dependent adaptation in a swarm of drones for environmental monitoring

© 2020 IEEE. Recently, individual or groups of drones have been used increasingly more frequently for applications in environmental monitoring. Groups of drones add larger robustness, lower vulnerability, higher accuracy and flexibility with respect to the use of single drones. These groups are called swarms when designed to make collective decisions trough local mutual interactions, as real social insects swarms. Natural environments are characterized by intrinsic dynamics that are hard to predict. Since a main issue faced by swarms of drones is the absence of adaptability to changes of the environment, in this paper we proposed a principled approach that can potentially be used to develop monitoring system based on drones swarm, able to adapt to changes of the environment thanks to the presence of stubborn individuals. Furthermore, we study how the level of consensus is affected by the interplay between the proportion of stubborn individuals and the difficulty of the problem, expressed by the ratio between the qualities of the different sites

Collective decision making in dynamic environments

© 2019, The Author(s). Collective decision making is the ability of individuals to jointly make a decision without any centralized leadership, but only relying on local interactions. A special case is represented by the best-of-n problem, whereby the swarm has to select the best option among a set of n discrete alternatives. In this paper, we perform a thorough study of the best-of-n problem in dynamic environments, in the presence of two options (n= 2). Site qualities can be directly measured by agents, and we introduce abrupt changes to these qualities. We introduce two adaptation mechanisms to deal with dynamic site qualities: stubborn agents and spontaneous opinion switching. Using both computer simulations and ordinary differential equation models, we show that: (i) The mere presence of the stubborn agents is enough to achieve adaptability, but increasing its number has detrimental effects on the performance; (ii) the system adaptation increases with increasing swarm size, while it does not depend on agents’ density, unless this is below a critical threshold; (iii) the spontaneous switching mechanism can also be used to achieve adaptability to dynamic environments, and its key parameter, the probability of switching, can be used to regulate the trade-off between accuracy and speed of adaptation

Collective decision making in dynamic environments

Abstract: Collective decision making is the ability of individuals to jointly make a decision without any centralized leadership, but only relying on local interactions. A special case is represented by the best-of-n problem, whereby the swarm has to select the best option among a set of n discrete alternatives. In this paper, we perform a thorough study of the best-of-n problem in dynamic environments, in the presence of two options (n=2). Site qualities can be directly measured by agents, and we introduce abrupt changes to these qualities. We introduce two adaptation mechanisms to deal with dynamic site qualities: stubborn agents and spontaneous opinion switching. Using both computer simulations and ordinary differential equation models, we show that: (i) The mere presence of the stubborn agents is enough to achieve adaptability, but increasing its number has detrimental effects on the performance; (ii) the system adaptation increases with increasing swarm size, while it does not depend on agents’ density, unless this is below a critical threshold; (iii) the spontaneous switching mechanism can also be used to achieve adaptability to dynamic environments, and its key parameter, the probability of switching, can be used to regulate the trade-off between accuracy and speed of adaptation

Cross-inhibition leads to group consensus despite the presence of strongly opinionated minorities and asocial behaviour

Strongly opinionated minorities can have a dramatic impact on the opinion dynamics of a large population. Two factions of inflexible minorities, polarised into two competing opinions, could lead the entire population to persistent indecision. Equivalently, populations can remain undecided when individuals sporadically change their opinion based on individual information rather than social information. Our analysis compares the cross-inhibition model with the voter model for decisions between equally good alternatives, and with the weighted voter model for decisions among alternatives characterised by different qualities. Here we show that cross-inhibition, differently from the other two models, is a simple mechanism, ubiquitous in collective biological systems, that allows the population to reach a stable majority for one alternative even in the presence of asocial behaviour. The results predicted by the mean-field models are confirmed by experiments with swarms of 100 locally interacting robots. This work suggests an answer to the longstanding question of why inhibitory signals are widespread in natural systems of collective decision making, and, at the same time, it proposes an efficient mechanism for designing resilient swarms of minimalistic robots

The best-of-n problem with dynamic site qualities: Achieving adaptability with stubborn individuals

© 2018, Springer Nature Switzerland AG. Collective decision-making is one of main building blocks of swarm robotics collective behaviors. It is the ability of individuals to make a collective decision without any centralized leadership, but only via local interaction and communication. The best-of-n problem is a subclass of collective decision-making, whereby the swarm has to select the best option among a set of n possible alternatives. Recently, the best-of-n problems has gathered momentum: a number of decision-making mechanisms have been studied focusing both on cases where there is an explicit measurable difference between the two qualities, as well as on cases when there are only delay costs in the environment driving the consensus to one of the n alternatives. To the best of our knowledge, all the formal studies on the best-of-n problem have considered a site quality distribution that is stationary and does not change over time. In this paper, we perform a study of the best-of-n problems in a dynamic environment setting. We consider the situation where site qualities can be directly measured by agents, and we introduce abrupt changes to these qualities, whereby the two qualities are swapped at a given time. Using computer simulations, we show that a vanilla application of one of the most studied decision-making mechanism, the voter model, does not guarantee adaptation of the swarm consensus towards the best option after the swap occurs. Therefore, we introduce the notion of stubborn agents, which are not allowed to change their opinion. We show that the presence of the stubborn agents is enough to achieve adaptability to dynamic environments. We study the performance of the system with respect to a number of key parameters: the swarm size, the difference between the two qualities and the proportion of stubborn individuals

Spatial and temporal distribution of mineral nutrients and sugars throughout the lifespan of Hibiscus rosa-sinensis L. flower

AbstractAlthough the physiological and molecular mechanisms of flower development and senescence have been extensively investigated, a whole-flower partitioning study of mineral concentrations has not been carried out. In this work, the distribution of sucrose, total reducing sugars, dry and fresh weight and macro and micronutrients were analysed in Hibiscus rosa-sinensis L. petals, stylestigma including stamens and ovary at different developmental stages (bud, open and senescent flowers). Total reducing sugars showed the highest value in petals of bud flowers, then fell during the later stages of flower development whereas sucrose showed the highest value in petals of senescent flowers. In petals, nitrogen and phosphorus content increased during flower opening, then nitrogen level decreased in senescent flowers. The calcium, phosphorus and boron concentrations were highest in ovary tissues whatever the developmental stage. Overall, the data presented suggests that the high level of total reducing sugars prior the onset of flower opening contributes to support petal cells expansion, while the high amount of sucrose at the time of petal wilting may be viewed as a result of senescence. Furthermore, this study discusses how the accumulation of particular mineral nutrients can be considered in a tissue specific manner for the activation of processes directly connected with reproduction

An investigation into the railway ballast grading using GPR and image analysis

This study reports on an investigation into the grain size distribution of the railway ballast using ground-penetrating radar (GPR) and image analysis. The proposed approach relies on the hypothesis that the dimension (grading) of the ballast aggregates can influence the back-reflected spectrum received by the use of GPR. This assumption was confirmed by the finite difference time-domain (FDTD) simulations of the GPR signal, which were run by using the numerical simulator package gprMax 2D. A regression model was developed which related the "equivalent" diameter of the ballast aggregates and the frequency of the peak within the received spectrum. The model was validated in the laboratory environment by means of a 155 cm x 155 cm x 50 cm methacrylate tank, filled up with railway ballast. An air-coupled GPR system equipped with a 2000 MHz central frequency antenna was used for testing purposes. A total of three spatial distributions of the ballast aggregates within the tank were investigated, by emptying out and filling up thrice the tank with the same material. The geometric information on the ballast grading obtained from the simulation-based regression model was compared to the actual grading curve of the ballast. To this effect, an algorithm based on the automatic image analysis was developed. The comparison showed that the modelled aggregate diameter corresponded to the 70 % of the grading of the material sieved out in the laboratory. This contribution paves the way to new methodologies for the non-destructive assessment and the monitoring of segregation phenomena within the railway ballast layers in railway track-beds

Benzo[b]tiophen-3-ol derivatives as effective inhibitors of human monoamine oxidase: design, synthesis, and biological activity

A series of benzo[b]thiophen-3-ols were synthesised and investigated as potential human monoamine oxidase (hMAO) inhibitors in vitro as well as ex vivo in rat cortex synaptosomes by means of evaluation of 3,4-dihydroxyphenylacetic acid/dopamine (DOPAC/DA) ratio and lactate dehydrogenase (LDH) activity. Most of these compounds possessed high selectivity for the MAO-B isoform and a discrete antioxidant and chelating potential. Molecular docking studies of all the compounds underscored potential binding site interactions suitable for MAO inhibition activity, and suggested structural requirements to further improve the activity of this scaffold by chemical modification of the aryl substituents. Starting from this heterocyclic nucleus, novel lead compounds for the treatment of neurodegenerative disease could be developed

Dental age estimation in children affected by juvenile rheumatoid arthritis

Dental root calcification has proven to be a reliable biological evidence to estimate chronological age of children. The development of structures usually examined in the age estimation forensic practice (e.g. skeleton, teeth) is supposed to be influenced by diseases and nutritional, environmental, ethnic, and ultimately even socioeconomic factors. This research aims to study the age estimation in children affected by juvenile rheumatoid arthritis (JRA) with and without steroids treatment and compared with healthy subjects. Material and methods Dental age estimations based on 752 OPGs, 420 girls and 332 boys, aged from 3.3 to 15.99 years, were provided by applying Demirjian and Willems' original methods. Of the whole sample, 103 individuals were affected by JRA and 40 received a continuous corticosteroid therapy, over 1 year long. Conclusions Willems' and Demirjian's original methods, as methods commonly applied to estimate age for sub-adults with unremarkable medical history, can be used for medico-legal purposes to children affected by JRA. Willems' method tended to underestimate age while Demirjian's method resulted to be prone to overestimation for both healthy and JRA-affected children. JRA showed to have no influence on root calcification process even in children that received steroid treatment for 1 year or longer