First numerical evidence of global Arnold diffusion in quasi--integrable systems

We provide numerical evidence of global diffusion occurring in slightly perturbed integrable Hamiltonian systems and symplectic maps. We show that even if a system is sufficiently close to be integrable, global diffusion occurs on a set with peculiar topology, the so--called Arnold web, and is qualitatively different from Chirikov diffusion, occurring in more perturbed systems.Comment: 8 pages 3 figure

A numerical study of the topology of normally hyperbolic invariant manifolds supporting Arnold diffusion in quasi--integrable systems.

We investigate numerically the stable and unstable manifolds of the hyperbolic manifolds of the phase space related to the resonances of quasi-integrable systems in the regime of validity of the Nekhoroshev and KAM theorems. Using a model of weakly interacting resonances we explain the qualitative features of these manifolds characterized by peculiar 'flower--like' structures. We detect different transitions in the topology of these manifolds related to the local rational approximations of the frequencies. We find numerically a correlation among these transitions and the speed of Arnold diffusion

Cyanobacteria as indicators of water quality in Campania coasts, Italy: a monitoring strategy combining remote/proximal sensing andin situdata

Cyanobacterial blooms (CBs) are generally triggered by eutrophic conditions due to anthropogenic nutrient inputs to local waters (wastewater or contaminated waters). During the bloom, some species produce toxic secondary metabolites (cyanotoxins) that are dangerous for humans and animals. Here, a multidisciplinary strategy for an early detection and constant monitoring is proposed. This strategy combines remote/proximal sensing technology with analytical/biotechnological analyses. To demonstrate the applicability of this strategy, four anthropogenically-impacted sites were selected along the Campania coast of southwestern Italy, in the so called 'Land of Fires'. The sites were observed using satellite and aircraft images during summer, 2015. Algal community composition was determined using spectrophotometric analysis for the detection of the cyanobacterial pigment phycocyanin (PC). Complementary metagenomic analysis revealed the taxonomic presence of cyanobacteria belonging to genera associated with strong eutrophic conditions. Key elements of this strategy are the combination and integration of applying different methodological approaches such as the parallel and combined use of satellite, aerial and in-situ data, the simplified multispectral image indexing and classification for a truly efficient method in detecting early blooms of cyanobacteria. The effectiveness of the strategy has been validated also by the specific taxa of cyanobacteria found in the examined areas that confirm the assumption that cyanobacterial blooms may serve as useful bioindicators of degraded water quality in coastal ecosystems. To our knowledge this is the first time that the presence of cyanobacteria has been observed in water bodies along the Campania coast

The burden of mental disorders, substance use disorders and self-harm among young people in Europe, 1990-2019 : Findings from the Global Burden of Disease Study 2019

Background Mental health is a public health issue for European young people, with great heterogeneity in resource allocation. Representative population-based studies are needed. The Global Burden of Disease (GBD) Study 2019 provides internationally comparable information on trends in the health status of populations and changes in the leading causes of disease burden over time. Methods Prevalence, incidence, Years Lived with Disability (YLDs) and Years of Life Lost (YLLs) from mental disorders (MDs), substance use disorders (SUDs) and self-harm were estimated for young people aged 10-24 years in 31 European countries. Rates per 100,000 population, percentage changes in 1990-2019, 95% Uncertainty Intervals (UIs), and correlations with Sociodemographic Index (SDI), were estimated. Findings In 2019, rates per 100,000 population were 16,983 (95% UI 12,823 - 21,630) for MDs, 3,891 (3,020 4,905) for SUDs, and 89.1 (63.8 - 123.1) for self-harm. In terms of disability, anxiety contributed to 647.3 (432 -912.3) YLDs, while in terms of premature death, self-harm contributed to 319.6 (248.9-412.8) YLLs, per 100,000 population. Over the 30 years studied, YLDs increased in eating disorders (14.9%;9.4-20.1) and drug use disorders (16.9%;8.9-26.3), and decreased in idiopathic developmental intellectual disability (-29.1%;23.8-38.5). YLLs decreased in self-harm (-27.9%;38.3-18.7). Variations were found by sex, age-group and country. The burden of SUDs and self-harm was higher in countries with lower SDI, MDs were associated with SUDs. Interpretation Mental health conditions represent an important burden among young people living in Europe. National policies should strengthen mental health, with a specific focus on young people. Funding The Bill and Melinda Gates Foundation Copyright (C) 2022 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)Peer reviewe

Scenarios for the dynamics of comet 67P/Churyumov-Gerasimenko over the past 500 kyr

The complex dynamics of 67P has the typical uncertainties of the Jupiter-family comets. The Rosetta mission provided a unique opportunity to dissipate them with fresh experimental data. We aim to constrain the residence time of the comet in a dynamics dominated by Jupiter and Saturn by comparing statistics of large sets of numerical integrations with assumptions on the erosion experienced by the comet. We integrated backward for 150 kyr 2000 clones of 67P selected from preliminary integrations of 500 000 clones. We find that the clones that did not arrive from hyperbolic/parabolic orbits have been mostly in the region dominated by Jupiter and Saturn in the last 150 kyr; they transit easily between dynamics dominated by Jupiter, dynamics also dominated by Saturn and, with smaller probability, by Saturn alone. Many clones were injected in the Jupiter family from hyperbolic orbits and orbits of large periods P > 500 yr, but none of the clones was injected from a Uranus-dominated dynamics through sequences of planetary scatterings, while 5 per cent of the clones were injected on this route in 500 kyr. 60 per cent of the clones had already been in an orbit with q < 1.5 au before 1959. Compatible with the uncertainties on the long-term model of non-gravitational forces, we conclude that 67P was injected from a cometary reservoir into a dynamics dominated by Jupiter and Saturn at an epoch that we estimate as being in between 30 and 150 kyr ago; this interval should be extended by considering periods of dormancies