26 research outputs found
Validation of the H-SAF precipitation product H03 over Greece using rain gauge data
No full textThis paper presents an extensive validation of the combined infrared/microwave H-SAF (EUMETSAT Satellite Application Facility on Support to Operational Hydrology and Water Management) precipitation product H03, for a 1-year period, using gauge observations from a relatively dense network of 233 stations over Greece. First, the quality of the interpolated data used to validate the precipitation product is assessed and a quality index is constructed based on parameters such as the density of the station network and the orography.
Then, a validation analysis is conducted based on comparisons of satellite (H03) with interpolated rain gauge data to
produce continuous and multi-categorical statistics at monthly and annual timescales by taking into account the different geophysical characteristics of the terrain (land, coast, sea, elevation).
Finally, the impact of the quality of interpolated data on the validation statistics is examined in terms of different
configurations of the interpolation model and the rain gauge network characteristics used in the interpolation. The possibility of using a quality index of the interpolated data as a filter in the validation procedure is also investigated. The continuous validation statistics show yearly root mean squared error (RMSE) and mean absolute error (MAE) corresponding to the 225 and 105 % of the mean rain rate, respectively. Mean error (ME) indicates a slight overall tendency for underestimation of the rain gauge rates, which takes large values for the high rain rates. In general, the H03 algorithm cannot retrieve very well the light (10 mm/h) precipitation. The poor correlation between satellite and gauge data points to algorithm problems in colocating precipitation patterns. Seasonal comparison shows that retrieval errors are lower for cold months than in the summer months of the year. The multi-categorical statistics indicate that the H03 algorithm is able to discriminate efficiently the rain from the no rain events although a large number of rain events are missed. The most prominent feature is the very high false alarm ratio (FAR) (more than 70 %), the relatively low probability of detection (POD) (less than 40 %), and the overestimation of the rainy pixels. Although the different geophysical features of the terrain (land, coast, sea,
elevation) and the quality of the interpolated data have an effect on the validation statistics, this, in general, is not significant and seems to be more distinct in the categorical than in the continuous statistics
The Trojan-Horse Method applied to the6Li(p,α)3He reaction down to astrophysical energies
No full textThe Trojan-Horse Method has been applied to the three-body d(6Li,alpha 3He)n breack-up reaction in order to extract the bare nucleus S(E) factor for the 6Li(p,alpha)3He reaction down to astrophysical energies
Indirect study of the astrophysically relevant reaction 6Li(p,alpha)3He by means of the Trojan Horse Method
No full textThe Trojan Horse Method was applied to the 2H(6Li,α3He)n three-body reaction in order to extract the bare nucleus S(E) factor for the 6Li(p,α)3He reaction. The three-body reaction was performed in two kinematically complete experiments at beam energies of 25 and 14 MeV. The selected quasi-free coincidence yield was compared with the result of a Monte Carlo calculation where the entering two-body cross section was the result of a R-matrix parameterization of the direct two-body cross section. The quite good agreement throughout the investigated region above and below the p-6Li Coulomb barrier, allowed for the extraction of the bare S(E) factor in the astrophysical energy region. The S(0) value together with an independent estimate of the screening potential Ue were derived and compared with those obtained from direct measurements
Cross-section of
No full textThe cross-section of 8
Li(,n)11
B has been measured at = 1.25 MeV to be mb using novel techniques, i.e. a 8
Li radioactive ion beam produced at the tandem in Catania in combination with a 4
He gas cell and a neutron detector. The value is in fair agreement with previous work strengthening the model of inhomogeneous Big Bang nucleosynthesis
Between subject enclitic and agreement marker: The second person endings in sicilian
No full textIn this paper we analyse the characteristics of 2sg verb-final -tu in Sicilian. Although this is generally referred to as an enclitic subject pronoun, it is clear that it is different from the subject clitics found in northern Italian dialects. The question of whether it is an actual subject enclitic or rather an inflectional affix remains controversial. The primary empirical goal of this study is to provide a general characterization of the synchronic properties of this element, focusing firstly on its grammatical status, and secondly on the distributional differences with respect to the 2pl ending -vu. This comparison will lead us to the conclusion that -tu and -vu instantiate a path of grammaticalization, and that their origins are to be sought in the morphosyntactic reflexes of the feature 'hearer'. More specifically, we claim that the original subject pronoun was at some stage the phonological realization of the head of the functional projection HearerP, but has been subsequently reanalysed as a bound morpheme encoding agreement. This diachronic account straightforwardly explains the flows and problems with the historical analysis that assumes disambiguation in the verbal paradigm to be the triggering factor. © The Philological Society 2012
THE TROJAN HORSE METHOD APPLIED TO THE ASTROPHYSICALLY RELEVANT PROTON CAPTURE REACTIONS ON Li ISOTOPES
No full textThe 7Li(p,alpha)4He, 6Li(d,alpha)4He and 6Li(p,alpha)3He reactions were performed in the framework of the Trojan Horse Method applied to the d(7Li,alpha alpha)n, 6Li(6Li,alpha 3He)n three-body reactions, respectively. Their bare astrophysical S-factor were extracted, and from the comparison with the behaviour of the screened direct data, an independent estimate of the screening polential was obtained
8Li(alpha,n)11B at Big Bang Temperatures: Neutron Counting With a Low Intensity 8Li Radioactive Beam
No full textThe cross section of 8Li(alpha,n)11B is very important for the study of primordial nuclesynthesis models. In this paper we report on the production of a 8Li beam via the 7(d,p)8Li reaction at the Laboratori Nazionali del Sud. Also a novel experimental technique for measuring the reaction 8Li(alpha,n)11B at energies of astrophysical interest has been implemented and tested
