Qualitative and analytical results of the bifurcation thresholds to halo orbits

We study the dynamics in the neighborhood of the collinear Lagrangian points in the spatial, circular, restricted three--body problem. We consider the case in which one of the primaries is a radiating body and the other is oblate (although the latter is a minor effect). Beside having an intrinsic mathematical interest, this model is particularly suited for the description of a mission of a spacecraft (e.g., a solar sail) to an asteroid. The aim of our study is to investigate the occurrence of bifurcations to halo orbits, which take place as the energy level is varied. The estimate of the bifurcation thresholds is performed by analytical and numerical methods: we find a remarkable agreement between the two approaches. As a side result, we also evaluate the influence of the different parameters, most notably the solar radiation pressure coefficient, on the dynamical behavior of the model. To perform the analytical and numerical computations, we start by implementing a center manifold reduction. Next, we estimate the bifurcation values using qualitative techniques (e.g. Poincar\'e surfaces, frequency analysis, FLIs). Concerning the analytical approach, following \cite{CPS} we implement a resonant normal form, we transform to suitable action-angle variables and we introduce a detuning parameter measuring the displacement from the synchronous resonance. The bifurcation thresholds are then determined as series expansions in the detuning. Three concrete examples are considered and we find in all cases a very good agreement between the analytical and numerical results

Environmental Genomics: A Tale of Two Fishes

The influence of the environment on two congeneric fishes, Gillichthys mirabilis and Gillichthys seta, that live in the Gulf of California at temperatures of 10-25 degrees C, and up to 42-44 degrees C, respectively, was addressed by analyzing their genomes. Compared with G. mirabilis, G. seta showed some striking features. Substitution rates in the mitochondrial genes were found to be extremely fast, in fact faster than in noncoding control regions (D-loops), from which a divergence time of less than 0.66-0.75 Mya could be estimated. In the nuclear genome, 1) both AT --> GC/GC --> AT and transversion: transition ratios in coding sequences (CDSs) were relatively high; moreover, the ratios of nonsynonymous/synonymous changes (Ka/Ks) suggested that some genes were under positive selection; 2) DNA methylation showed a very significant decrease; and 3) a GC-rich minisatellite underwent a 4-fold amplification in the gene-rich regions. All these observations clearly indicate that the environment (temperature and the accompanying hypoxia) can rapidly mold the nuclear as well as the mitochondrial genome. The stabilization of gene-rich regions by the amplification of the GC-rich minisatellite and by the GC increase in nuclear CDSs is of special interest because it provides a model for the formation of the GC-rich and gene-rich isochores of the genomes of mammals and birds

FOTOSS Phase I: Chronicle of an Achievement

Prodotto della scheda progetto FOTOSS presente nel PT INAF 2021-2023This document is a record of the key tasks and dedicated activities that ushered the start of FOTOSS, a project of the Torino Astrophysical Observatory (OATo) carried out in cooperation with the Shanghai Astronomical Observatory (SHAO). Its first objective is the high accurate digitization of the entire OATo’s plate archive, with the ultimate goal of preserving century-old astronomical observations for their scientific exploitation

Historical colonization and demography of the Mediterranean damselfish, Chromis chromis

The desiccation of the Mediterranean Sea during the Messinian Salinity Crisis 6.0–5.3 million years ago (Ma), caused a major extinction of the marine ichthyofauna of the Mediterranean. This was followed by an abrupt replenishment of the Mediterranean from the Atlantic after the opening of the Strait of Gibraltar. In this study, we combined demographic and phylogeographic approaches using mitochondrial and nuclear DNA markers to test the alternative hypotheses of where (Atlantic or Mediterranean) and when (before or after the Messinian Salinity Crisis) speciation occurred in the Mediterranean damselfish, Chromis chromis. The closely related geminate transisthmian pair Chromis multilineata and Chromis atrilobata was used as a way of obtaining an internally calibrated molecular clock. We estimated C. chromis speciation timing both by determining the time of divergence between C. chromis and its Atlantic sister species Chromis limbata(0.93–3.26 Ma depending on the molecular marker used, e.g. 1.23–1.39 Ma for the control region), and by determining the time of coalescence for C. chromis based on mitochondrial control region sequences (0.14–0.21 Ma). The time of speciation of C. chromis was always posterior to the replenishment of the Mediterranean basin, after the Messinian Salinity Crisis. Within the Mediterranean, C. chromis population structure and demographic characteristics revealed a genetic break at the Peloponnese, Greece, with directional and eastbound gene flow between western and eastern groups. The eastern group was found to be more recent and with a faster growing population (coalescent time = 0.09–0.13 Ma, growth = 485.3) than the western group (coalescent time = 0.13–0.20 Ma, growth = 325.6). Our data thus suggested a western origin of C. chromis, most likely within the Mediterranean. Low sea water levels during the glacial periods, the hydrographic regime of the Mediterranean and dispersal restriction during the short pelagic larval phase of C. chromis(18–19 days) have probably played an important role in C. chromis historical colonization

Optical tracking of deep-space spacecraft in Halo L2 orbits and beyond: the Gaia mission as a pilot case

We tackle the problem of accurate optical tracking of distant man-made probes, on Halo orbit around the Earth-Sun libration point L2 and beyond, along interplanetary transfers. The improved performance of on-target tracking, especially when observing with small-class telescopes is assessed providing a general estimate of the expected S/N ratio in spacecraft detection. The on-going Gaia mission is taken as a pilot case for our analysis, reporting on fresh literature and original optical photometry and astrometric results. The probe has been located, along its projected nominal path, within 0.13 +/- 0.09 arcsec, or 0.9 +/- 0.6 km. Spacecraft color appears to be red, with (V-R_c) = 1.1 +/- 0.2 and a bolometric correction to the R_c band of (Bol-R_c) = -1.1 +/- 0.2. The apparent magnitude, R_c = 20.8 +/- 0.2, is much fainter than originally expected. These features lead to suggest a lower limit for the Bond albedo a = 0.11 +/- 0.05 and confirm that incident Sun light is strongly reddened by Gaia through its on-board MLI blankets covering the solar shield. Relying on the Gaia figures, we found that VLT-class telescopes could yet be able to probe distant spacecraft heading Mars, up to 30 million km away, while a broader optical coverage of the forthcoming missions to Venus and Mars could be envisaged, providing to deal with space vehicles of minimum effective area Aeff >= 10^6 cm^2. In addition to L2 surveys, 2m-class telescopes could also effectively flank standard radar-ranging techniques in deep-space probe tracking along Earth's gravity-assist maneuvers for interplanetary missions.Comment: In press for Advances in Space Research (w/ 15 colour figures and 1 table

Cardiovascular magnetic resonance imaging in hypertrophic cardiomyopathy:the importance of clinical context

In patients with suspected or established hypertrophic cardiomyopathy (HCM), cardiovascular magnetic resonance (CMR) is widely employed for clinical management, given its multimodality approach capable of providing unique information on cardiac morphology, function, and tissue characterization. Guidance regarding all aspects of HCM diagnosis and management is provided by the comprehensive 2014 European Society of Cardiology (ESC) guidelines on HCM. CMR should be performed in centres with recognized expertise in heart muscle diseases, by physicians who are familiar with the whole HCM disease spectrum, differential diagnoses, and pitfalls. Because CMR is usually performed and interpreted by physicians not directly involved in patient care, detailed, bidirectional, and standardized communication becomes essential to obtain best results and avoid misinterpretation. In order to maximize the potential of CMR, it is of paramount importance that reporting physicians are provided with the essential clinical information and that, in turn, referring physicians are given a core set of CMR morphological, functional, and tissue characterization results following the test. This article aims to summarize the current knowledge on the role of CMR in managing HCM and, in addition, to review the importance of the clinical context in which the report is provided, in both adult and paediatric population, highlighting implications for clinical research