Periodic orbits in the logarithmic potential

Analytic methods to investigate periodic orbits in galactic potentials. To evaluate the quality of the approximation of periodic orbits in the logarithmic potential constructed using perturbation theory based on Hamiltonian normal forms. The solutions of the equations of motion corresponding to periodic orbits are obtained as series expansions computed by inverting the normalizing canonical transformation. To improve the convergence of the series a resummation based on a continued fraction may be performed. This method is analogous to that looking for approximate rational solutions (Prendergast method). It is shown that with a normal form truncated at the lowest order incorporating the relevant resonance it is possible to construct quite accurate solutions both for normal modes and periodic orbits in general position.Comment: 10 pages, 9 figures, accepted for publication on Astronomy and Astrophysic

Stability of axial orbits in galactic potentials

We investigate the dynamics in a galactic potential with two reflection symmetries. The phase-space structure of the real system is approximated with a resonant detuned normal form constructed with the method based on the Lie transform. Attention is focused on the stability properties of the axial periodic orbits that play an important role in galactic models. Using energy and ellipticity as parameters, we find analytical expressions of bifurcations and compare them with numerical results available in the literature.Comment: 20 pages, accepted for publication on Celestial Mechanics and Dynamical Astronom

Quantitative predictions with detuned normal forms

The phase-space structure of two families of galactic potentials is approximated with a resonant detuned normal form. The normal form series is obtained by a Lie transform of the series expansion around the minimum of the original Hamiltonian. Attention is focused on the quantitative predictive ability of the normal form. We find analytical expressions for bifurcations of periodic orbits and compare them with other analytical approaches and with numerical results. The predictions are quite reliable even outside the convergence radius of the perturbation and we analyze this result using resummation techniques of asymptotic series.Comment: Accepted for publication on Celestial Mechanics and Dynamical Astronom

Redox imbalance and morphological changes in skin fibroblasts in typical Rett syndrome.

Evidence of oxidative stress has been reported in the blood of patients with Rett syndrome (RTT), a neurodevelopmental disorder mainly caused by mutations in the gene encoding the Methyl-CpG-binding protein 2. Little is known regarding the redox status in RTT cellular systems and its relationship with the morphological phenotype. In RTT patients (n = 16) we investigated four different oxidative stress markers, F2-Isoprostanes (F2-IsoPs), F4-Neuroprostanes (F4-NeuroPs), nonprotein bound iron (NPBI), and (4-HNE PAs), and glutathione in one of the most accessible cells, that is, skin fibroblasts, and searched for possible changes in cellular/intracellular structure and qualitative modifications of synthesized collagen. Significantly increased F4-NeuroPs (12-folds), F2-IsoPs (7.5-folds) NPBI (2.3-folds), 4-HNE PAs (1.48-folds), and GSSG (1.44-folds) were detected, with significantly decreased GSH (−43.6%) and GSH/GSSG ratio (−3.05 folds). A marked dilation of the rough endoplasmic reticulum cisternae, associated with several cytoplasmic multilamellar bodies, was detectable in RTT fibroblasts. Colocalization of collagen I and collagen III, as well as the percentage of type I collagen as derived by semiquantitative immunofluorescence staining analyses, appears to be significantly reduced in RTT cells. Our findings indicate the presence of a redox imbalance and previously unrecognized morphological skin fibroblast abnormalities in RTT patients

Mesoscale Sea Surface Salinity in the Algerian Basin observed through SMOS and ABACUS glider data

Ocean Salinity Science Conference, 6-9 November 2018, Paris.-- 1 pageThe Algerian Basin is a key component of the general circulation in the Western Mediterranean Sea. The presence of both fresh Atlantic water and more saline Mediterranean water gives the basin an intense inflow/outflow regime and complex circulation patterns. In recent years, several studies have demonstrated the advantages of combined use of autonomous underwater vehicles, such as gliders, with remotely sensed products. In this framework, an important contribution could come from a new generation of enhanced sea surface salinity (SSS) products, i.e. Soil Moisture and Ocean Salinity (SMOS), Soli Mosture Active Passive (SMAP) and Aquarius. Here we present a preliminary study to assess the advantages of using the enhanced SMOS SSS products obtained through a new methodology using a combination of debiased non-Bayesian retrieval, DINEOF (Data Interpolating Empirical Orthogonal Functions) and multifractal fusion with high resolution Sea Surface Temperature (OSTIA SST) maps for improving their spatial and temporal resolution in the Western Mediterranean Sea (Olmedo et al., 2018). The Algerian Basin SSS described by the new SMOS maps have been compared with the in situ high resolution glider measurements collected in the framework of the ABACUS series observational program conducted in the Algerian Basin during fall 2014 - 2017(Cotroneo et al., 2016; Aulicino et al., 2018) in the framework of the SOCIB (Balearic Islands Coastal Observing and Forecasting System) glider facility open access programme and supported by the Joint European Research Infrastructure network for Coastal Observatories (JERICO) Trans National Access (TNA)The ABACUS missions were funded by the Joint European Research Infrastructure network for Coastal Observatories (JERICO) Trans National Access (TNA) third call (agreement no. 262584), by the SOCIB external access call 2015, and by JERICO-NEXT TNA second and third call (agreement no. 654410)Peer Reviewe

Sea Surface Salinity in the Algerian Basin Observed Through SMOS and ABACUS Glider Data

European Space Agency’s 2019 Living Planet Symposium, 13-17 May 2019, Milan, ItalyThe Algerian Basin is a key component of the general circulation in the Western Mediterranean Sea. The presence of both fresh Atlantic water and more saline Mediterranean water gives the basin an intense inflow/outflow regime and complex circulation patterns. Energetic mesoscale structures that evolve from meanders of the Algerian Current into isolated cyclonic and anticyclonic eddies dominate the area, with marked repercussions on biological activity. In recent years, several studies have demonstrated the advantages of combined use of autonomous underwater vehicles, such as gliders, with remotely sensed products. In this framework, an important contribution could come from a new generation of enhanced sea surface salinity (SSS) products, i.e. Soil Moisture and Ocean Salinity (SMOS), Soli Mosture Active Passive (SMAP) and Aquarius. Here we present a preliminary study to assess the advantages of using the enhanced SMOS SSS products obtained through a new methodology using a combination of debiased non-Bayesian retrieval, DINEOF (Data Interpolating Empirical Orthogonal Functions) and multifractal fusion with high resolution Sea Surface Temperature (OSTIA SST) maps for improving their spatial and temporal resolution in the Western Mediterranean Sea (Olmedo et al., 2018). The Algerian Basin SSS described by the new SMOS maps have been compared with the in situ high resolution glider measurements collected in the framework of the ABACUS series observational program conducted in the Algerian Basin during fall 2014 – 2017 and spring 2017 – 2018 (Cotroneo et al., 2016; Aulicino et al., 2018). The achieved results show that i) the enhanced SMOS products well represent the salinity patterns described by in situ SSS; ii) the mesoscale structures described by SMOS in the Algerian Basin coincide with those identified by gliders and described by altimetry and MODIS imagesPeer reviewe

Scavenger receptor B1 post-translational modifications in Rett syndrome.

AbstractThe modulation of the HDL receptor scavenger receptor B1 (SRB1) was evaluated in skin fibroblasts isolated from patients with Rett syndrome (RTT), a genetic form of infantile autism. Patients showed an altered plasma lipid profile, while their skin fibroblasts showed a dramatic reduction in SRB1 (immunogold, Western blot and immunohistochemistry). The decreased SRB1 levels were demonstrated to be the consequence of its binding with 4-hydroxy-2-nonenal (4HNE), a product of lipid peroxidation, and its increased ubiquitination. Our findings show for the first time a loss of SRB1 in RTT cells and its relationship with a chronic oxidative stress status

Anomalia di forma dei globuli rossi e danno ossidativo nella membrana eritrocitaria nella sindrome di Rett

In condizioni fisiologiche, i globuli rossi - cellule dalle dimensioni di 7-8 m (millesimo di mm) - mostrano una caratteristica forma a disco biconcavo (discociti), di importanza chiave per tutte le loro funzioni, quali la deformabilità (per adattarsi alle sinuosità della rete circolatoria), e lo scambio di ossigeno (O2), ma sono molto suscettibili a cambiamenti morfologici, con conseguente perdita della loro funzionalità. Tra i fattori che causano alterazioni morfologiche ci possono essere i cambiamenti di osmolarità, di pH, condizioni di ipossia e presenza di ossidanti (sostanze o molecole che possono indurre stress ossidativo) [1-5]. I globuli rossi a causa degli alti livelli di ferro cellulare e della proprietà dell’emoglobina ad auto-ossidarsi, sono una costante sorgente di produzione di ossidanti (radicali liberi dell’ossigeno come l’anione superossido) [6,7] e di ferro in forma libera (NPBI), cioè non legato a proteine, redox attivo. Stress ossidativo (SO) e ipossia possono portare ad alterazioni nella forma dei globuli rossi in pazienti adulti con malattia polmonare cronica ostruttiva (COPD) [7,8]. Nella forma tipica della sindrome di Rett (RTT ) il nostro gruppo ha dimostrato la presenza di ipossia cronica, alterati scambi di gas a livello polmonare, aumentato SO e lesioni morfologiche polmonari, simili a quelle evidenziabili nella malattia polmonare interstiziale associata a bronchiolite respiratoria dei fumatori (RB-ILD) [9,10]. Nonostante i globuli rossi svolgano un ruolo fondamentale nel trasporto e scambio di O2 nei mammiferi, finora non esistevano informazioni sulla morfologia dei globuli rossi nelle bimbe e ragazze affette da RTT . In particolare, nei nostri precedenti studi avevamo dimostrato che lo SO è in grado di indurre nei globuli rossi rilascio di NPBI, formazione di metemoglobina (Met-Hb) e alterazioni ossidative dei lipidi (perossidazione lipidica) e delle proteine di membrana [11]. Quindi nel presente studio abbiamo valutato se lo SO possa indurre cambiamenti morfologici e danno ossidativo nei globuli rossi di pazienti Rett con forma classica. La forma dei globuli rossi in pazienti RTT e in soggetti sani è stata correlata ai marker di SO, stato di ossigenazione, scambi gassosi polmonari e vari parametri cardiorespiratori