90 research outputs found
Water temperature from XBT taken from the research vessel Italica in the Southern Ocean and Southwest Pacific Ocean from 1997-01-26 to 1997-02-19 (NCEI Accession 0172042)
No full textVertical temperature profiles were taken from January 26th 1997 to February 19th 1997 from the research vessel Italica during an oceanographic cruise between New Zealand and the Ross Sea in the framework of the Climatic Long Term Interaction for the Mass-balance in Antarctica (CLIMA) project of the Italian National Antarctic Research Programme (PNRA) using Sippican T7 Expendable Bathythermograph (XBT). Used probes have a vertical resolution of 65 cm and a maximum nominal depth of 760 m. XBT launches have been interrupted in case of severe sea and weather conditions. This implies the presence of gaps in the sampling. Final spatial resolution of the sampling is about 15 nm. All temperature profiles are quality controlled for consistency between adjacent profiles and through spike editing. Data are provided in TXT format
MINDhEARTH: Una ricerca-intervento con gli adolescenti per la promozione del benessere, della mindfulnless e della connessione con la natura
No full textLoneliness and Problematic Internet Use in Adolescents: The Mediating Role of Dissociation
No full textBackground/Objectives. Problematic Internet uUse (PIU) is a multifaceted syndrome characterized by excessive or poorly controlled preoccupations, urges, or behaviors regarding Internet use leading to significant impairments in daily life and mental health. Previous research has separately related PIU to loneliness and dissociation, both in adults and adolescents. The aim of the present study is to analyze the mutual relationship between PIU, loneliness, and dissociation in an adolescent sample, in particular evaluating the indirect effect of dissociation on the relationship between loneliness and PIU. Methods. A cross-sectional design was used with 243 Italian high school students (69.1% females), from year 9 to 13 (age: M = 17.1, SD = 1.4 years), who participated in the study from January to June 2020. They completed measures of PIU (Generalized Problematic Internet Use Scale-2), loneliness (UCLA Loneliness Scale), and dissociation (Adolescent Dissociative Experiences Scale). Socio-demographic and contextual variables were also collected (i.e., age, gender, type of school, school year, sport practice, hobby engagement, assessment before/during the COVID-19 pandemic). Data were analyzed using regression, Pearson’s correlation, and mediation analysis. Results. Severe PIU was observed in 8.6% of the sample. None of the socio-demographic and contextual variables had a significant effect on PIU. Positive medium-sized correlations were observed between PIU, loneliness, and dissociation. Mediation analyses showed an indirect effect of loneliness on PIU through dissociation. Conclusions. Feelings of loneliness may significantly exacerbate adolescents’ PIU by increasing their dissociative tendency. Understanding this dynamic is crucial for developing targeted interventions to address both loneliness and dissociation in efforts to mitigate PIU among adolescents
Potenziale dei trattamenti idrotermici propedeutici all’incenerimento dei fanghi di depurazione
No full textLa normativa sulla gestione dei fanghi di depurazione sta progressivamente evolvendo verso standard di protezione ambientale sempre più elevati, promuovendo, di fatto, il ricorso all’incenerimento di crescenti quantità di fanghi. Le tecniche attualmente disponibili di mono- e co-incenerimento spesso richiedono la preventiva riduzione del tenore di umidità mediante disidratazioni meccaniche e spesso processi di essiccamento termico. Questi ultimi comportano significativi consumi energetici, poiché basati sull’evaporazione dell’umidità. Alcuni processi di trattamento idrotermico di sviluppo relativamente recente hanno dimostrato la possibilità di abbattere significativamente il fabbisogno energetico per la rimozione di umidità dai fanghi evitandone l’evaporazione. Si tratta di processi denominati HTC = Hydro-Thermal Carbonisation e/o HTD = Hydro-Thermal Dewatering. L’esito di questi processi è un significativo cambiamento delle proprietà reologiche dei fanghi che ne consente un’apprezzabile disidratazione meccanica, tale da rendere superflui eventuali essiccamenti termici propedeutici all’incenerimento.
Un processo HTD è stato recentemente studiato dagli autori mediante varie prove su un impianto pilota. I risultati della sperimentazione hanno consentito di valutare le prestazioni attese a scala industriale, sulla base delle quali, il presente lavoro confronta due scenari di incenerimento dei fanghi: (a) lo scenario di riferimento in cui i fanghi sono disidratati meccanicamente, essiccati termicamente e inceneriti; (b) lo scenario HTD in cui i fanghi, dopo la disidratazione meccanica sono sottoposti a trattamento idrotermico, a ulteriore disidratazione meccanica e, infine, a incenerimento.
I risultati ottenuti mostrano che i consumi di gas naturale (e le conseguenti emissioni di CO2) per lo scenario basato su HTD si attestano a circa il 19% dello scenario di riferimento. Una preliminare analisi economica, basata sulla stima dei costi industriali di trattamento, evidenzia la convenienza dello scenario HTD che consegue tempi di ritorno dell’investimento dell’ordine di 1-2 anni
Multi-Collocation-Based Estimation of Wave Climate in a Non-Tidal Bay: The Case Study of Bagnoli-Coroglio Bay (Tyrrhenian Sea)
No full textA stochastic model for phytoplankton dynamics in the Tyrrhenian Sea
No full textIn this work we try to answer the question how relevant the random fluctuations are in the dynamics of a natural system. Specifically we ask which role the external fluctuations play in a real ecosystem, which is a typical example of complex system, since it is governed
by nonlinear dynamics and subject to deterministic and random perturbations coming from the environment. For this purpose we study the spatio-temporal dynamics of phytoplankton abundances in a marine ecosystem, comparing results from the model with experimental findings. The study is based on a stochastic reaction-diffusiontaxis model, which is used to analyze the spatio-temporal dynamics of five phytoplankton groups in the middle of the Tyrrhenian Sea, inside the Modified Atlantic Water (MAW), that is the upper layer of the water column of the Mediterranean Sea (from the surface down to 200 m). The study is performed by considering the intraspecific competition of the phytoplanktonic groups for limiting factors, i.e. light intensity and nutrient concentration, and the seasonal changes of environmental variables. Moreover, we take into account the effects of the random
fluctuations of the temperature and the velocity field on the phytoplankton populations by inserting terms of multiplicative noise in the differential equations of the model. In order to compare theoretical results with experimental findings, the picophytoplankton abundances obtained by the stochastic model are converted in chlorophyll a concentrations. The statistical analysis, based on the chi-square test, shows that the vertical distributions of total chlorophyll concentration are in a good agreement with experimental data acquired in the marine site investigated during four different sampling periods (seasons) of the year
Cryptocurrency ecosystems and social media environments: An empirical analysis through Hawkes’ models and natural language processing
No full textCopyright © 2021 The Author(s). We analyse, using a mixture of statistical models and natural language process techniques, what happened in social media from June 2019 onwards to understand the relationships between Cryptocurrencies’ prices and social media, focusing on the rise of the Bitcoin and Ethereum prices. In particular, we identify and model the relationship between the cryptocurrencies market price changes, and sentiment and topic discussion occurrences on social media, using Hawkes’ Model. We find that some topics occurrences and rise of sentiment in social media precedes certain types of price movements. Specifically, discussions concerning governments, trading, and Ethereum cryptocurrency as an exchange currency appear to negatively affect Bitcoin and Ethereum prices. Those concerning investments, appear to explain price rises, whilst discussions related to new decentralized realities and technological applications explain price falls. Finally, we validate our model using a real case study: the already famous case of ”Wallstreetbet and GameStop”1 that took place in January 2021.Funding: No funding was received for this work
Reaction-diffusion-taxis model for spatio-temporal dynamics of five picophytoplankton populations
No full textRecently new models were devised to study spatio-temporal dynamics of phytoplankton populations in view of obtaining more precise predictions of the vertical biomass distributions in marine ecosystems. These studies and related results can be crucial from the point of view of fishery. Indeed the abundance of fish species is strictly connected with primary production, i.e. phytoplankton biomass, responsible for chlorophyll concentration. In this work a one-dimensional deterministic reaction-diffusion-taxis model is used to reproduce the spatio-temporal dynamics, along a water column, of five picophytoplankton populations sampled in a real ecosystem. In our analysis, to better reproduce the spatio-temporal behaviour of picophytoplankton populations we take into account the periodical changes of the light intensity and profiles of
vertical turbulent diffusivity, obtaining the time evolution of the system over a period of five years. Moreover, the seasonal variations of the depth of thermocline and the thickness of the upper mixed layer close to the water surface are considered. As a first step, the spatio-temporal behaviour of biomass concentration of each picophytoplankton population is calculated by numerically solving the equations of the model. Afterwards, the numerical results for biomass concentration, expressed in cell/m^3, are converted in total concentration of chlorophyll a (chl a) and divinil-chlorophyll a Dvchl a, obtaining the chlorophyll distributions along the whole water column. These theoretical profiles are compared with experimental data for chlorophyll concentration collected in a site of the Tyrrhenian Sea in four different days, corresponding to different seasons of the same year. Statistical analysis, based on χ2 goodnessof-fit test, shows that numerical results are in a good agreement with real chlorophyll distributions for all seasons investigated. In particular, numerical results indicate that the primary production of phytoplankton biomass is strongly influenced by the light intensity and vertical turbulent diffusivity, which take on different values along the water column, depending also on seasonal variations. These findings could contribute to predict future changes in phytoplankton distributions due to global warming, and to devise strategies which can prevent the decline of primary production and consequent decrease of fish abundance
Multi-Collocation-Based Estimation of Wave Climate in a Non-Tidal Bay: The Case Study of Bagnoli-Coroglio Bay (Tyrrhenian Sea)
No full textIn this paper, the advantages of shaping a non-conventional triple collocation-based calibration of a wave propagation model is pointed out. Illustrated through a case study in the Bagnoli-Coroglio Bay (central Tyrrhenian Sea, Italy), a multi-comparison between numerical data and direct measurements have been carried out. The nearshore wave propagation model output has been compared with measurements from an acoustic Doppler current profiler (ADCP) and an innovative low-cost drifter-derived GPS-based wave buoy located outside the bay. The triple collocation—buoy, ADCP and virtual numerical point—make possible an implicit validation between instrumentations and between instrumentation and numerical model. The procedure presented here advocates for an alternative “two-step” strategy. Indeed, the triple collocation technique has been used solely to provide a first “rough” calibration of one numerical domain in which the input open boundary has been placed, so that the main wave direction is orthogonally aligned. The need for a fast and sufficiently accurate estimation of wave model parameters (first step) and then an ensemble of five different offshore boundary orientations have been considered, referencing for a more detailed calibration to a short time series of a GPS-buoy installed in the study area (second step). Such a stage involves the introduction of an enhancement factor for the European Centre for Medium-Range Weather Forecasts (ECMWF) dataset, used as input for the model. Finally, validation of the final model’s predictions has been carried out by comparing ADCP measurements in the bay. Despite some limitations, the results reveal that the approach is promising and an excellent correlation can be found, especially in terms of significant wave height
How diffusivity, thermocline and incident light intensity modulate the dynamics of Deep Chlorophyll Maximum in Tyrrhenian Sea
No full textDuring the last few years theoretical works have shed new light and proposed new hypotheses on the mechanisms which regulate the spatio-temporal behaviour of phytoplankton communities in marine
pelagic ecosystems. Despite this, relevant physical and biological issues, such as effects of the time-
dependent mixing in the upper layer, competition between groups, and dynamics of non-stationary deep
chlorophyll maxima, are still open questions. In this work, we analyze the spatio-temporal behaviour of
five phytoplankton populations in a real marine ecosystem by using a one-dimensional reaction-diffusion-taxis model. The study is performed, taking into account the seasonal variations of environmental variables, such as light intensity, thickness of upper mixed layer and profiles of vertical turbulent diffusivity, obtained starting from experimental findings. Theoretical distributions of phytoplankton cell concentration was converted in chlorophyll concentration, and compared with the experimental profiles measured in a site of the Tyrrhenian Sea at four different times (seasons) of the year, during four different oceanographic cruises. As a result we find a good agreement between theoretical and experimental distributions of chlorophyll concentration. In particular, theoretical results reveal that the seasonal changes of
environmental variables play a key role in the phytoplankton distribution and determine the properties of the deep chlorophyll maximum. This study could be extended to other marine ecosystems to predict future changes in the phytoplankton biomass due to global warming, in view of devising strategies to prevent the decline of the primary production and the consequent decrease of fish species
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