68 research outputs found
Adattabilità antropica ed evoluzione dei sistemi fluviali nell’area del delta padano meridionale tra la tarda Età romana e l’inizio del Medioevo
Nonostante numerose siano le ricerche sulla ricostruzione dell’evoluzione paleogeografica del Delta del Po, i quesiti aperti restano ancora molti; non è infatti semplice collocare topograficamente i pochi dati noti dalle fonti antiche, mentre le trasformazioni avvenute in epoca medievale e moderna hanno spesso obliterato le tracce fluviali più antiche. Partendo da una disamina delle ipotesi paleogeografiche ricostruttive finora avanzate e delle conoscenze archeologiche note per l’area del delta meridionale, si è cercato di contestualizzare i nuovi dati geoarcheologici recentemente raccolti nell’area a nord di Ravenna. Attraverso l’interpretazione delle varie facies deposizionali riconoscibili all’interno del carotaggio PCR02 (svolto nei pressi del sito archeologico di Butrium), è stato possibile non solo ricostruire l’evoluzione del paesaggio a scala locale, ma anche ipotizzare cambiamenti a più ampio respiro. Ciò è stato possibile tramite analisi XRF mirati su campioni rappresentativi delle principali facies per determinare la provenienza dei sedimenti e datazione tramite 14C del cambiamento da ambiente lagunare a paludoso, riconosciuto nel carotaggio. Contestualizzando questi nuovi dati con le informazioni desunte da fonti scritte e letterarie e i dati geologici e archeologici pregressi, è stato ipotizzato un avanzamento della linea di costa entro il II/III secolo d.C., probabilmente a causa della possibile attivazione di un ramo del Po, passante non molto lontano da Ravenna, che però solo future indagini potrebbero eventualmente permettere di mappare.Human adaptability and river network evolution in the southern Po delta between the Roman period and the beginning of the Middle Ages.
Despite several studies have already focused on the palaeogeographical reconstruction of the Po Delta, many questions remain unanswered. Indeed it is not easy to locate on the ground the few data known from ancient sources, while medieval and modern alluvial transformations hide previous landforms and fluvial traces. Starting from a reanalysis of existing palaeogeographical reconstructions and known archaeological data from the southern Delta, it was possible to frame the new geoarchaeological data collected north of Ravenna. Interpreting the different geological layers identified in coring PCR02, carried out near the archaeological site of Butrium, it was possible to reconstruct landscape changes at the local level and hypothesize ones occurred at a broader scale. Especially for the latter, this was possible thanks to XFR analysis on targeted samples and 14C dating of the change from lagoonal to marshy environment recognized in the core. Contextualizing these data with historical, archaeological and geological knowledge, it was possible to suggest a phase of coastline progradation that must have happened within the 2nd or 3rd century AD. This change may be linked to a new southern branch of the Po river, possibly flowing not so far from Ravenna, but that only future investigation may be able to map
Injection of a Body into a Geodesic: Lessons Learnt from the LISA Pathfinder Case
Launch lock and release mechanisms constitute a common space business, however, some science missions due to very challenging functional and performance requirements need the development and testing of dedicated systems. In the LISA Pathfinder mission, a gold-coated 2-kg test mass must be injected into a nearly pure geodesic trajectory with a minimal residual velocity with respect to the spacecraft. This task is performed by the Grabbing Positioning and Release Mechanism, which has been tested on-ground to provide the required qualification. In this paper, we describe the test method that analyzes the main contributions to the mechanism performance and focuses on the critical parameters affecting the residual test mass velocity at the injection into the geodesic trajectory. The test results are also presented and discussed
Método de Pós-fechamento do Balanço de Energia para Avaliação dos Fluxos de Modelos da SuperfÃcie Terrestre
In this work, an analysis of the uncertainty of energy flux resulting from post-closure methods of the energy balance: H Method, LE method and Bowen method for the data observed in native grass area of the Pampa biome, located in Santa Maria, RS, Brazil. From these three methods suggest a new one, which we call the Combined Method. This method takes into account the quality classes of eddy covariance to choose the correct method to be applied. The uncertainties of flux were obtained by the difference between the fluxes corrected by one of the post-closure methods and the raw fluxes. The maximum values of the uncertainties occur during the daytime. Regarding the combined method, the highest percentage of cases resulted in the application of correction by Bowen method, followed by the LE method and with less occurrence Method H. Thus, this method can be considered valid to evaluate the uncertainty of simulated fluxes over land surface models.Neste trabalho foi feita uma análise da incerteza dos fluxos de energia resultantes dos métodos pós-fechamento do Balanço de energia: Método H, Método LE e Método Bowen para os dados observados em área de campo nativo do bioma Pampa, localizado em Santa Maria, RS, Brasil . A partir destes três métodos sugerimos um novo, ao qual chamamos de Método Combinado. Este método leva em conta as classes de qualidade dos fluxos turbulentos para a escolha do método de correção a ser aplicado. As incertezas dos fluxos foram obtidas pela diferença entre os fluxos corrigidos por um dos métodos pós-fechamento e os fluxos brutos. Os valores máximos das incertezas ocorrem no perÃodo diurno. Quanto ao Método Combinado, a maior porcentagem de casos resultou na aplicação da correção pelo Método Bowen, seguido do Método LE e com menos ocorrência o Método H. Dessa forma, este Método pode ser considerado válido para avaliar a incerteza dos fluxos simulados por modelos de superfÃcie terrestre
Sub-Femto- g Free Fall for Space-Based Gravitational Wave Observatories: LISA Pathfinder Results
We report the first results of the LISA Pathfinder in-flight experiment. The results demonstrate that two free-falling reference test masses, such as those needed for a space-based gravitational wave observatory like LISA, can be put in free fall with a relative acceleration noise with a square root of the power spectral density of 5.2±0.1  fm s−2/Hz, or (0.54±0.01)×10−15  g/Hz, with g the standard gravity, for frequencies between 0.7 and 20 mHz. This value is lower than the LISA Pathfinder requirement by more than a factor 5 and within a factor 1.25 of the requirement for the LISA mission, and is compatible with Brownian noise from viscous damping due to the residual gas surrounding the test masses. Above 60 mHz the acceleration noise is dominated by interferometer displacement readout noise at a level of (34.8±0.3)  fm/Hz, about 2 orders of magnitude better than requirements. At f≤0.5  mHz we observe a low-frequency tail that stays below 12  fm s−2/Hz down to 0.1 mHz. This performance would allow for a space-based gravitational wave observatory with a sensitivity close to what was originally foreseen for LISA.CNES 1316634/CNRS 103747UnivEarthS Labex program/ANR-10-LABX-0023UnivEarthS Labex program/ANR-11-IDEX-0005-02DLRFederal Ministry for Economic Affairs and Energy/FKZ 50OQ0501Federal Ministry for Economic Affairs and Energy/FKZ 50OQ1601Agenzia Spaziale ItalianaInstituto Nazionale di Fisica NucleareAYA2010-15709 (MICINN)ESP2013-47637-P (MINECO)ESP2015-67234-P (MINECO)Fundacion General CSICSwiss Space Office (SSO)Swiss National Science FoundationUnited Kingdom Space Agency (UKSA)University of GlasgowUniversity of BirminghamImperial CollegeScottish Universities Physics Alliance (SUPA)U.S. National Aeronautics and Space Administration (NASA
Laser Interferometer Space Antenna
Following the selection of The Gravitational Universe by ESA, and the
successful flight of LISA Pathfinder, the LISA Consortium now proposes a 4 year
mission in response to ESA's call for missions for L3. The observatory will be
based on three arms with six active laser links, between three identical
spacecraft in a triangular formation separated by 2.5 million km.
LISA is an all-sky monitor and will offer a wide view of a dynamic cosmos
using Gravitational Waves as new and unique messengers to unveil The
Gravitational Universe. It provides the closest ever view of the infant
Universe at TeV energy scales, has known sources in the form of verification
binaries in the Milky Way, and can probe the entire Universe, from its smallest
scales near the horizons of black holes, all the way to cosmological scales.
The LISA mission will scan the entire sky as it follows behind the Earth in its
orbit, obtaining both polarisations of the Gravitational Waves simultaneously,
and will measure source parameters with astrophysically relevant sensitivity in
a band from below Hz to above Hz.Comment: Submitted to ESA on January 13th in response to the call for missions
for the L3 slot in the Cosmic Vision Programm
Calibrating LISA Pathfinder raw data into femto-g differential accelerometry
LISA Pathfinder is an in-flight test of the local sources of acceleration noise in LISA. The acceleration noise level in LISA Pathfinder is measured by the residual differential acceleration Δg between the two test masses once the coupling to the spacecraft motion has been removed. The full process from raw data to Δg passes through a series of calibration experiments and different data elaboration procedure which are thoroughly used during the mission and represent the baseline for any other further investigation
COVID-19 in rheumatic diseases in Italy: first results from the Italian registry of the Italian Society for Rheumatology (CONTROL-19)
OBJECTIVES:
Italy was one of the first countries significantly affected by the coronavirus disease 2019 (COVID-19) epidemic. The Italian Society for Rheumatology promptly launched a retrospective and anonymised data collection to monitor COVID-19 in patients with rheumatic and musculoskeletal diseases (RMDs), the CONTROL-19 surveillance database, which is part of the COVID-19 Global Rheumatology Alliance.
METHODS:
CONTROL-19 includes patients with RMDs and proven severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) updated until May 3rd 2020. In this analysis, only molecular diagnoses were included. The data collection covered demographic data, medical history (general and RMD-related), treatments and COVID-19 related features, treatments, and outcome. In this paper, we report the first descriptive data from the CONTROL-19 registry.
RESULTS:
The population of the first 232 patients (36% males) consisted mainly of elderly patients (mean age 62.2 years), who used corticosteroids (51.7%), and suffered from multi-morbidity (median comorbidities 2). Rheumatoid arthritis was the most frequent disease (34.1%), followed by spondyloarthritis (26.3%), connective tissue disease (21.1%) and vasculitis (11.2%). Most cases had an active disease (69.4%). Clinical presentation of COVID-19 was typical, with systemic symptoms (fever and asthenia) and respiratory symptoms. The overall outcome was severe, with high frequencies of hospitalisation (69.8%), respiratory support oxygen (55.7%), non-invasive ventilation (20.9%) or mechanical ventilation (7.5%), and 19% of deaths. Male patients typically manifested a worse prognosis. Immunomodulatory treatments were not significantly associated with an increased risk of intensive care unit admission/mechanical ventilation/death.
CONCLUSIONS:
Although the report mainly includes the most severe cases, its temporal and spatial trend supports the validity of the national surveillance system. More complete data are being acquired in order to both test the hypothesis that RMD patients may have a different outcome from that of the general population and determine the safety of immunomodulatory treatments
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