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

Direction of arrival estimation using a cluster of beams in a cone-shaped digital array radar'

In this paper some potential system and processing advantages of conformal cone shaped digital array radar have been investigated, in particular in relation to potential alternative approaches for angle estimation with respect to the traditional monopulse. First of all potential benefit in terms of reduction of the number of radiating elements is shown when a conical array is considered with respect to a traditional system formed by four planar arrays, if a coverage of 360° must be assured. Secondly, having in mind an innovative digital array system where the received signals are analog to digital converted at element level and the corresponding data are possibly transferred to a central elaboration unit, an alternative approach is investigated for angular estimation. In this paper we derive the theoretical expression of the Cramer Rao Lower Bound for elevation angle estimation using a cluster of beams; we compare the limit performance of the traditional approach for angle estimation based on Sum and Difference beams with the approach based on a crowded cluster of RX beams properly spaced. The approaches show approximately equivalent performance, making the second particularly interesting for those situations where monopulse is known to experience performance degradation, as low elevation angle estimation; in this particular case an example of cluster design is shown, where the direct signal from a low altitude target must compete with a specular multipath

Tecniche di elaborazione di segnali a banda larga per sistemi radar multi-canale spaceborne e airborne

L’ambito scientifico dell’attività di ricerca svolta riguarda lo sviluppo e l’analisi di tecniche innovative per l’elaborazione di segnali a banda larga, utilizzando le potenzialità che sistemi multo-canale e/o multi - sensore forniscono. Nello specifico l’obiettivo è rappresentato dallo studio di funzionalità avanzate per radar aviotrasportati e spaziali di nuova generazione, tra cui la cancellazione di interferenze elettromagnetiche (e.m.) a banda larga e la capacità di imaging di target ad alta risoluzione. Il primo argomento trattato riguarda l’elaborazione di dati radar ad apertura sintetica multicanale (M-SAR), allo scopo di difendere il sistema da interferenze elettromagnetiche a larga banda (SAR-ECCM) preservando le normali capacità di imaging. I SAR sono sensori attivi in grado di produrre, attraverso tecniche di scansione, “mappe” di parametri radiativi ad alta risoluzione, grazie all’utilizzo di bande elevate; a tal fine sfruttano il backscattering dalla superficie, che subisce un’attenuazione a due vie, quindi è di estrema importanza che sistemi di questo tipo siano in grado di proteggersi dalle interferenze elettromagnetiche (intenzionali, dovute al Jamming, oppure dovute alle spurie di altri sistemi a radiofrequenza, in altre parole Radio Frequency Interference - RFI), che subiscono attenuazioni a una via e possono essere caratterizzate da potenze molto più elevate di quelle del segnale utile, anche se ricevute dai lobi laterali del pattern di antenna. L’utilizzo di tecniche di nulling di antenna ottimizzate per lavorare a banda stretta non può garantire la protezione da interferenze di tipo Noise-Like a banda larga, quindi sembra di grande interesse lo sviluppo e lo studio di prestazioni di tecniche apposite, che prevedano l’aumento di gradi di libertà a disposizione, sia spaziali, nel senso di un numero maggiore di canali riceventi ed eventualmente introducendo vincoli aggiuntivi, sia temporali, in altre parole considerando la possibilità di elaborare più campioni di segnale per ciascun canale ricevente. Il secondo argomento affrontato riguarda l’elaborazione di dati radar ad apertura sintetica inversa (ISAR) al fine di aumentare la risoluzione cross-range dell’immagine quando siano disponibili le acquisizioni, monostatiche o bistatiche, di una molteplicità di sensori aviotrasportati. Come è noto l’ISAR fornisce immagini di target ad alta risoluzione sfruttando le caratteristiche del moto dei bersagli rispetto a un sensore, posto su di una piattaforma quasi stazionaria. Il principale svantaggio di questo tipo di processing risiede nel fatto che le prestazioni raggiungibili in termini di risoluzione cross-range dipendono dalle caratteristiche intrinseche del moto del bersaglio, piuttosto che da parametri di sistema; mentre la risoluzione in slant-range è determinata una volta che la banda e la forma d’onda trasmessa sono state decise, non c’è nessun modo di assegnare un valore desiderato di risoluzione cross-range. In casi particolari di bersagli con piccole componenti di movimento il valore di risoluzione di cross-range ottenuto può essere insufficiente, se si pensa che le immagini ISAR generalmente sono usate nelle procedure di Non Cooperative Target Recognition (NCTR). Per contrastare questo effetto è possibile derivare delle procedure per combinare in modo coerente le acquisizioni di un insieme di sensori trasportati da piattaforme che volano in formazione; in questo modo è possibile sintetizzare un’apertura equivalente maggiore, quindi un valore di risoluzione migliore che se si considerasse un unico sensore

Built environment and elderly population health: a comprehensive literature review

Global population aging over recent years has been linked to poorer health outcomes and higher healthcare expenditure. Policies focusing on healthy aging are currently being developed but a complete understanding of health determinants is needed to guide these efforts. The built environment and other external factors have been added to the International Classification of Functioning as important determinants of health and disability. Although the relationship between the built environment and health has been widely examined in working age adults, research focusing on elderly people is relatively recent. In this review, we provide a comprehensive synthesis of the evidence on the built environment and health in the elderly

Ecosistemi per la ricerca Atti Convegno ACNP/NILDE Trieste, 22-23 maggio 2014

Il secondo convegno congiunto ACNP / NILDE: ecosistemi per la ricerca è stato ospitato dal 22 al 23 maggio 2014 dall’Università di Trieste. Sotto gli auspici della stessa Università di Trieste e degli altri enti di ricerca del Friuli Venezia Giulia1 sono stati affrontati in un’ottica internazionale i temi del rapporto tra cataloghi collettivi e servizi interbibliotecari, e il più generale ambito dei servizi bibliografici per la ricerca scientifica. ACNP e NILDE possono essere considerati un vero e proprio ecosistema. Le biblioteche e i bibliotecari collaborano tra di loro in maniera reciproca e secondo modalità interconnesse, offrendo agli utenti servizi sempre più evoluti e dinamici. Questo ecosistema, essendo aperto, mette i propri servizi a disposizione della ricerca scientifica in senso generale. Il convegno di Trieste ha offerto l’occasione di investigare e proporre soluzioni innovative, interconnessioni e relazioni nuove e più proficue. Il convegno ha presentato alcune rilevanti esperienze internazionali in tema di servizi interbibliotecari e cataloghi collettivi e la prosecuzione di attività che erano state proposte come spunti di ispirazione nel convegno precedente2 inoltre si sono condotte delle riflessioni sulle nuove esigenze dell’utenza. Una ultima parte è dedicata alla illustrazione degli sviluppi tecnici e le prospettive future di ACNP e di NILDE. Hanno partecipato all’evento oltre 200 colleghi italiani e stranieri ed i relatori dei 18 contributi provenivano da Italia, Germania, Austria, Grecia, Slovenia e Stati Uniti. Il carattere di confronto e di condivisione delle esperienze tipico della realtà partecipativa di ACNP e NILDE, è emerso anche in questa occasione nella tavola rotonda - di cui viene riportato un resoconto dettagliato - che ha affrontato il tema della valutazione della ricerca dal punto di vista delle biblioteche. Inoltre, la molto partecipata sessione poster ha ospitato 13 lavori- anch’essi riportati nel volume - incentrati oltre che su ACNP e NILDE anche sul tema ricerca e sistema biblioteca, dando ottimi spunti di partecipazione, dialogo e confronto sulle diverse realtà in cui operiamo

The rapid spread of SARS-COV-2 Omicron variant in Italy reflected early through wastewater surveillance

The SARS-CoV-2 Omicron variant emerged in South Africa in November 2021, and has later been identified worldwide, raising serious concerns. A real-time RT-PCR assay was designed for the rapid screening of the Omicron variant, targeting characteristic mutations of the spike gene. The assay was used to test 737 sewage samples collected throughout Italy (19/21 Regions) between 11 November and 25 December 2021, with the aim of assessing the spread of the Omicron variant in the country. Positive samples were also tested with a real-time RT-PCR developed by the European Commission, Joint Research Centre (JRC), and through nested RT-PCR followed by Sanger sequencing. Overall, 115 samples tested positive for Omicron SARS-CoV-2 variant. The first occurrence was detected on 7 December, in Veneto, North Italy. Later on, the variant spread extremely fast in three weeks, with prevalence of positive wastewater samples rising from 1.0% (1/104 samples) in the week 5-11 December, to 17.5% (25/143 samples) in the week 12-18, to 65.9% (89/135 samples) in the week 19-25, in line with the increase in cases of infection with the Omicron variant observed during December in Italy. Similarly, the number of Regions/Autonomous Provinces in which the variant was detected increased from one in the first week, to 11 in the second, and to 17 in the last one. The presence of the Omicron variant was confirmed by the JRC real-time RT-PCR in 79.1% (91/115) of the positive samples, and by Sanger sequencing in 66% (64/97) of PCR amplicons. In conclusion, we designed an RT-qPCR assay capable to detect the Omicron variant, which can be successfully used for the purpose of wastewater-based epidemiology. We also described the history of the introduction and diffusion of the Omicron variant in the Italian population and territory, confirming the effectiveness of sewage monitoring as a powerful surveillance tool

The Biodiversity of the Mediterranean Sea: Estimates, Patterns, and Threats

The Mediterranean Sea is a marine biodiversity hot spot. Here we combined an extensive literature analysis with expert opinions to update publicly available estimates of major taxa in this marine ecosystem and to revise and update several species lists. We also assessed overall spatial and temporal patterns of species diversity and identified major changes and threats. Our results listed approximately 17,000 marine species occurring in the Mediterranean Sea. However, our estimates of marine diversity are still incomplete as yet—undescribed species will be added in the future. Diversity for microbes is substantially underestimated, and the deep-sea areas and portions of the southern and eastern region are still poorly known. In addition, the invasion of alien species is a crucial factor that will continue to change the biodiversity of the Mediterranean, mainly in its eastern basin that can spread rapidly northwards and westwards due to the warming of the Mediterranean Sea. Spatial patterns showed a general decrease in biodiversity from northwestern to southeastern regions following a gradient of production, with some exceptions and caution due to gaps in our knowledge of the biota along the southern and eastern rims. Biodiversity was also generally higher in coastal areas and continental shelves, and decreases with depth. Temporal trends indicated that overexploitation and habitat loss have been the main human drivers of historical changes in biodiversity. At present, habitat loss and degradation, followed by fishing impacts, pollution, climate change, eutrophication, and the establishment of alien species are the most important threats and affect the greatest number of taxonomic groups. All these impacts are expected to grow in importance in the future, especially climate change and habitat degradation. The spatial identification of hot spots highlighted the ecological importance of most of the western Mediterranean shelves (and in particular, the Strait of Gibraltar and the adjacent Alboran Sea), western African coast, the Adriatic, and the Aegean Sea, which show high concentrations of endangered, threatened, or vulnerable species. The Levantine Basin, severely impacted by the invasion of species, is endangered as well

Comparative roles of upwelling and glacial iron sources in Ryder Bay, coastal western Antarctic Peninsula

Iron (Fe) is an essential micronutrient for phytoplankton, and is scarce in many regions including the open Southern Ocean. The western Antarctic Peninsula (WAP), an important source region of Fe to the wider Southern Ocean, is also the fastest warming region of the southern hemisphere. The relative importance of glacial versus marine Fe sources is currently poorly constrained, hindering projections of how changing oceanic circulation, productivity, and glacial dynamics may affect the balance of Fe sources in this region.Dissolved and total dissolvable Fe concentrations were measured throughout the summer bloom period at a coastal site on the WAP. Iron inputs to the surface mixed layer in early summer were strongly correlated with meteoric meltwater from glaciers and precipitation. A significant source of Fe from underlying waters was also identified, with dissolved Fe concentrations of up to 9.5 nM at 200 m depth. These two primary Fe sources act on different timescales, with glacial sources supplying Fe during the warm summer growing period, and deep water replenishing Fe over annual periods via deep winter mixing.Iron supply from deep water is sufficient to meet biological demand relative to macronutrient supply, making Fe limitation unlikely in this area even without additional summer Fe inputs from glacial sources. Both glacial and deep-water Fe sources may increase with continued climate warming, potentially enhancing the role of the WAP as an Fe source to offshore waters

Effect of remote ischaemic conditioning on clinical outcomes in patients with acute myocardial infarction (CONDI-2/ERIC-PPCI): a single-blind randomised controlled trial.

BACKGROUND: Remote ischaemic conditioning with transient ischaemia and reperfusion applied to the arm has been shown to reduce myocardial infarct size in patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI). We investigated whether remote ischaemic conditioning could reduce the incidence of cardiac death and hospitalisation for heart failure at 12 months. METHODS: We did an international investigator-initiated, prospective, single-blind, randomised controlled trial (CONDI-2/ERIC-PPCI) at 33 centres across the UK, Denmark, Spain, and Serbia. Patients (age >18 years) with suspected STEMI and who were eligible for PPCI were randomly allocated (1:1, stratified by centre with a permuted block method) to receive standard treatment (including a sham simulated remote ischaemic conditioning intervention at UK sites only) or remote ischaemic conditioning treatment (intermittent ischaemia and reperfusion applied to the arm through four cycles of 5-min inflation and 5-min deflation of an automated cuff device) before PPCI. Investigators responsible for data collection and outcome assessment were masked to treatment allocation. The primary combined endpoint was cardiac death or hospitalisation for heart failure at 12 months in the intention-to-treat population. This trial is registered with ClinicalTrials.gov (NCT02342522) and is completed. FINDINGS: Between Nov 6, 2013, and March 31, 2018, 5401 patients were randomly allocated to either the control group (n=2701) or the remote ischaemic conditioning group (n=2700). After exclusion of patients upon hospital arrival or loss to follow-up, 2569 patients in the control group and 2546 in the intervention group were included in the intention-to-treat analysis. At 12 months post-PPCI, the Kaplan-Meier-estimated frequencies of cardiac death or hospitalisation for heart failure (the primary endpoint) were 220 (8·6%) patients in the control group and 239 (9·4%) in the remote ischaemic conditioning group (hazard ratio 1·10 [95% CI 0·91-1·32], p=0·32 for intervention versus control). No important unexpected adverse events or side effects of remote ischaemic conditioning were observed. INTERPRETATION: Remote ischaemic conditioning does not improve clinical outcomes (cardiac death or hospitalisation for heart failure) at 12 months in patients with STEMI undergoing PPCI. FUNDING: British Heart Foundation, University College London Hospitals/University College London Biomedical Research Centre, Danish Innovation Foundation, Novo Nordisk Foundation, TrygFonden

Distributed ISAR focusing for targets undergoing 3D motion

The issue of focusing ISAR images with improved cross-range resolution of targets undergoing 3D motion observed by multiple radar systems is here addressed. Both multi-aspect and multi-grazing acquisition geometries are here considered. The Distributed Point Spread Function is devised with two possible approaches: (i) ID Multi-Aspect/Multi-Grazing and (ii) 3D approach, when the distributed processing is matched to the vertical/horizontal or to the effective component of the rotation motion respectively. The needed focusing technique is presented with the results obtained against simulated data; performance analysis shows that, despite some spatially variant degradation experienced with respect to ideal case (i.e. acquisition geometry completely matched to the motion characteristics) ISAR images of quality considerably higher than in the conventional single sensor case can be obtained