A model of dunnian flow at hillslope scale

The development of a thin stream above the soil surface (overland flow) is associated to two mechanism of runoff generation on the hillslope: the infiltration excess (hortonian flow) and saturation excess (dunnian flow) mechanism. The first one is typical of arid and semi-arid regions, usually characterised by high rainfall intensities on soil exhibiting low permeability. The second one, firstly introduced by Hewlett and Hibbert, constitutes the main mechanism of runoff generation in humid regions, characterised by high groundwater table. In the last mechanism runoff is produced by contributing areas of restricted extent that expands with time, where near to the bottom of the hillslope a high value initial soil water content occurs and gradually decreases versus upstream of the hillslope. Following this sketch, under the hypothesis of constant depth of the permeable layer, for stationary rainfall of indefinite duration, this work aims to investigate on the implications of temporal variability of active hillslope length on the hydrologic response for the dunnian mechanism of runoff generation. The flow in the unsaturated zone is modelled by the piston displacement model of Beven (1982a, 1982b). Once the wetting front reaches the impermeable layer (with different times along the hillslope), the transportation process, over and under the hillslope, is represented as the envelope of the infinite sequence of hydrographs, corresponding to the progressive lengths activated by the infiltration process and Ta - shifted from the beginning of the rainfall, where Ta is the starting up time associated to the active length. The overland hydrographs are modelled with the analytical solution of Agnese et al. (2001) over a plan hillslope, recently introduced. The subsurface stormflow hydrographs is modelled by using the classical linear storage model

Influence of the rainfall measurement interval on the erosivity determinations in the Mediterranean area

The single-storm erosion index, EI, of the USLE and RUSLE models may vary appreciably with the rainfall measurement interval, Dt. However, the effect of Dt on EI has not been investigated in the Mediterranean area. Approximately 700 erosive events and 1.5 years of rainfall energies measured by a rainfall impact measurement device were used to evaluate the effect of the rainfall measurement interval (5 min 6 Dt 6 60 min) on the erosivity determinations in the Mediterranean semi-arid area of Sicily. According to both literature and practical considerations, a reference time interval equal to 15 min was used in this investigation. Hourly rainfall data led to an appreciable underestimation of the mean value of EI (i.e., by also a factor of two, depending on the location). In the range 5 min 6 Dt 6 15 min, the effect of the rainfall measurement interval on the predicted erosivity was negligible (i.e., mean values differing by a maximum factor of 1.10) as compared with the uncertainties in the soil loss predictions. Two methods were developed for estimating the reference single-storm erosion index, (EI)15, from hourly rainfall data in Sicily. Method 1 converts the erosion index calculated on a 60- min measurement interval basis to (EI)15. Method 2 estimates (EI)15 by using the storm rainfall depth and the maximum rainfall intensity. Testing the two methods against two independent data sets produced a maximum difference between the estimated and the calculated mean values of (EI)15 equal to 7% for method 1 and 11% for method 2. Both methods may be applied in practice, depending on the available rainfall data. For a given rainfall intensity, the specific power, P, measured at eight time intervals (5 min 6 Dt 6 60 min) was in the range ±10% of the mean of the eight P values

Applying a probabilistic model of rainfall and snow days occurrence to daily series recorded in NW Italy.

Daily precipitation records exist spanning several decades. A valuable amount of climatic information exists in the time-series of interarrival times (IT), defined as the succession of times (number of days) elapsed from a rainy (or snowy) day to the one immediately preceding it.In a previous work, Agnese et al. (2014) have been successfully tested some probabilistic modelling of rain occurrence on Sicily rainfall data; particularly, the better fitting of IT’s observed frequencies was obtained by 3-parameter Lerch-series distribution. In this work thisdistribution is tested on 70 years of 20 precipitation time-series taken in the North-West Italy, both in the plain and in the mountains, up to the 2000 meters altitude. In such Mediterranean climatetwo markedly different behaviours were observed in the dry semester (April to September) and in the wet one (October to March). A better fit was obtained with that simple subdivision of the year, in comparison with the whole year modelling. However, the NW Italy climate is both more similar to the Central Europe one, and it is deeply influenced by the higher peaks of the Alps. Therefore the seasonality of daily precipitation data is much more complicated. Usually spring and fall are the seasons characterized by the higher precipitations, but the convective vs. frontal events also play a role in the IT distributions. In this work, different subdivisions were compared with the whole year fitting. The whole year Lerch distributions successfully fitted the data in a part of the time series, opening the way to interesting climate applications

OltreMare - Un progetto per il futuro della Biodiversità del Mediterraneo

Osservatorio e comunicazione. Questo progetto narra dello sguardo degli artisti dell’Accademia di Belle Arti di Palermo sul lavoro di ricerca portato avanti dall’IAS - CNR (ex IAMC) riguardo all’osservazione e alla tutela della Biodiversità e costituisce uno strumento eccellente di comunicazione per un pubblico quanto mai ampio. La divulgazione della scienza è un’attività complessa e sicuramente necessita di competenze e attitudini multidisciplinari oltreché di motivazione ed entusiasmo. La comunicazione delle tematiche scientifiche, di per sè ostiche nella traduzione al grande pubblico, grazie alla forza e all’immediatezza tipica dell’espressione artistica diventa prodigioso spunto di riflessione e di osservazione, sia per i giovani che per la comunità intera. Grazie al progetto Osservatorio della Biodiversità Siciliana, sono state realizzate da partners con competenze istituzionali complementari , quali l’Accademia di Belle Arti di Palermo e l’IAS - CNR di Capo Granitola, delle azioni didattiche e creative di valore scientifico espresse con straordinaria forza e bellezza. La sinergia creata, nata da un rapporto consolidato ormai da tempo, ha portato ad uno scambio tra ricercatori e professori che si sono messi in gioco in uno sforzo congiunto per avvicinare le proprie competenze. In seguito ad un’intensa attività di coordinamento e pianificazione dei lavori, si è riusciti a portare avanti un progetto ambizioso e imponente, coinvolgendo moltissimi ambiti scientifici e altrettante cattedre, sensibilizzando così gli artisti ai temi della Biodiversità. Le opere prodotte, accompagnate da schede scientifiche, hanno dunque acquisito un valore, oltreché artistico, didattico, e restano come testimonianze oggettive, nel percorso culturale, per i visitatori dell’Osservatorio. Questa collaborazione conferma l’importanza e l’opportunità di unire arte e scienza per esaltare la percezione della ricerca scientifica da parte della comunità e ,ancora una volta, si conferma come, per fare “cose straordinarie”, siano più importanti i rapporti umani piuttosto che le competenze tecniche. A tal proposito, un ringraziamento sentito al Prof. Calogero Piro che, con passione e dedizione, ha reso possibile questa esperienza, e al gruppo di Comunicazione EDU Lab dell’IAS - CNR, che è stato, per me, un supporto indispensabile per la realizzazione di questo complesso progetto

An explainable model of host genetic interactions linked to COVID-19 severity

We employed a multifaceted computational strategy to identify the genetic factors contributing to increased risk of severe COVID-19 infection from a Whole Exome Sequencing (WES) dataset of a cohort of 2000 Italian patients. We coupled a stratified k-fold screening, to rank variants more associated with severity, with the training of multiple supervised classifiers, to predict severity based on screened features. Feature importance analysis from tree-based models allowed us to identify 16 variants with the highest support which, together with age and gender covariates, were found to be most predictive of COVID-19 severity. When tested on a follow-up cohort, our ensemble of models predicted severity with high accuracy (ACC = 81.88%; AUCROC = 96%; MCC = 61.55%). Our model recapitulated a vast literature of emerging molecular mechanisms and genetic factors linked to COVID-19 response and extends previous landmark Genome-Wide Association Studies (GWAS). It revealed a network of interplaying genetic signatures converging on established immune system and inflammatory processes linked to viral infection response. It also identified additional processes cross-talking with immune pathways, such as GPCR signaling, which might offer additional opportunities for therapeutic intervention and patient stratification. Publicly available PheWAS datasets revealed that several variants were significantly associated with phenotypic traits such as "Respiratory or thoracic disease", supporting their link with COVID-19 severity outcome.A multifaceted computational strategy identifies 16 genetic variants contributing to increased risk of severe COVID-19 infection from a Whole Exome Sequencing dataset of a cohort of Italian patients

Carriers of ADAMTS13 Rare Variants Are at High Risk of Life-Threatening COVID-19

Thrombosis of small and large vessels is reported as a key player in COVID-19 severity. However, host genetic determinants of this susceptibility are still unclear. Congenital Thrombotic Thrombocytopenic Purpura is a severe autosomal recessive disorder characterized by uncleaved ultra-large vWF and thrombotic microangiopathy, frequently triggered by infections. Carriers are reported to be asymptomatic. Exome analysis of about 3000 SARS-CoV-2 infected subjects of different severities, belonging to the GEN-COVID cohort, revealed the specific role of vWF cleaving enzyme ADAMTS13 (A disintegrin-like and metalloprotease with thrombospondin type 1 motif, 13). We report here that ultra-rare variants in a heterozygous state lead to a rare form of COVID-19 characterized by hyper-inflammation signs, which segregates in families as an autosomal dominant disorder conditioned by SARS-CoV-2 infection, sex, and age. This has clinical relevance due to the availability of drugs such as Caplacizumab, which inhibits vWF-platelet interaction, and Crizanlizumab, which, by inhibiting P-selectin binding to its ligands, prevents leukocyte recruitment and platelet aggregation at the site of vascular damage