Space-time modeling of soil moisture: Stochastic rainfall forcing with heterogeneous vegetation

The present paper complements that of Isham et al. (2005), who introduced a space-time soil moisture model driven by stochastic space-time rainfall forcing with homogeneous vegetation and in the absence of topographical landscape effects. However, the spatial variability of vegetation may significantly modify the soil moisture dynamics with important implications for hydrological modeling. In the present paper, vegetation heterogeneity is incorporated through a two dimensional Poisson process representing the coexistence of two functionally different types of plants (e.g., trees and grasses). The space-time statistical structure of relative soil moisture is characterized through its covariance function which depends on soil, vegetation, and rainfall patterns. The statistical properties of the soil moisture process averaged in space and time are also investigated. These properties are especially important for any modeling that aggregates soil moisture characteristics over a range of spatial and temporal scales. It is found that particularly at small scales, vegetation heterogeneity has a significant impact on the averaged process as compared with the uniform vegetation case. Also, averaging in space considerably smoothes the soil moisture process, but in contrast, averaging in time up to 1 week leads to little change in the variance of the averaged process

Regional analysis of runoff thresholds behaviour in Southern Italy based on theoretically derived distributions

The analysis of runoff thresholds and, more in general, the identification of main mechanisms of runoff generation controlling the flood frequency distribution is investigated, by means of theoretically derived flood frequency distributions, in the framework of regional analysis. Two nested theoretically-derived distributions are fitted to annual maximum flood series recorded in several basins of Southern Italy. Results are exploited in order to investigate heterogeneities and homogeneities and to obtain useful information for improving the available methods for regional analysis of flood frequency

Flood quantiles estimation based on theoretically derived distributions: regional analysis in Southern Italy

A regional probabilistic model for the estimation of medium-high return period flood quantiles is presented. The model is based on the use of theoretically derived probability distributions of annual maximum flood peaks (DDF). The general model is called TCIF (Two-Component IF model) and encompasses two different threshold mechanisms associated with ordinary and extraordinary events, respectively. Based on at-site calibration of this model for 33 gauged sites in Southern Italy, a regional analysis is performed obtaining satisfactory results for the estimation of flood quantiles for return periods of technical interest, thus suggesting the use of the proposed methodology for the application to ungauged basins. The model is validated by using a jack-knife cross-validation technique taking all river basins into consideration

A new measurement of cosmic-ray electrons with the Fermi Large Area Telescope

I present an updated measurement of the cosmic-ray electron and positron spectrum between 7GeV and 2TeV, based on 7 years of data collected with the Fermi Large Area Telescope (LAT). The LAT is the first space-based instrument to directly explore the region above 1TeV. The best fit to the spectrum that we measure is given by a broken power-law, with the break located at ∼ 50GeV. Above 50GeV our data are well described by a single power-law with a spectral index of 3.07 ± 0.02 (stat + syst) ±0.04 (energy scale). An exponential cutoff lower than 1.8TeV is excluded at 95% CL

Vitamin E in Viral Inactivated Vaccines

Abstract This research aimed at verifying whether vitamin E added to inactivated and emulsified vaccines enhances the immune response to viral antigens in chicken. Three hundred and twenty broilers (males and females) and 16 types of vaccines, varying in viral antigen [Newcastle disease virus, egg drop syndrome 1976 virus (EDS76V), and infectious bursal disease virus] and vitamin E amount (replacing 10, 20, and 30% of mineral oil) were used. Results show that vaccines with vitamin E, especially when it replaces 20 or 30% of mineral oil, induces a more rapid and higher antibody response than control vaccines. An adjuvant effect of vitamin E was also present in viral vaccine lacking bacterial antigens. Apart from vitamin E content, the Newcastle disease virus and infectious bursal disease virus monovalent vaccines induced higher titers of specific circulating antibodies in birds than did trivalent vaccines

Best Fit and Selection of Theoretical Flood Frequency Distributions Based on Different Runoff Generation Mechanisms

Theoretically derived distributions allow the detection of dominant runoff generation mechanisms as key signatures of hydrologic similarity. We used two theoretically derived distributions of flood peak annual maxima: the first is the ―IF‖ distribution, which exploits the variable source area concept, coupled with a runoff threshold having scaling properties; the second is the Two Component-IF (TCIF) distribution, which generalizes the IF distribution, and is based on two different threshold mechanisms, associated with ordinary and extraordinary events, respectively. By focusing on the application of both models to two river basins, of sub-humid and semi-arid climate in Southern Italy, we present an ad hoc procedure for the estimation of parameters and we discuss the use of appropriate techniques for model selection, in the case of nested distributions

effects of dietary vitamin e on the quality of table eggs enriched with n 3 long chain fatty acids

Abstract Because of the proposed cardioprotective benefits of n-3 fatty acids and vitamin E, a trial was carried out to investigate the possibility of enriching eggs with n-3 fatty acid and vitamin E added to the hen's diet. One hundred ninety-two Hy-Line Brown hens, 39-wk-old, were divided into eight groups: four groups received the basal diet supplemented with 3% lard and four doses of dl-alpha-tocopheryl acetate (0, 50, 100, and 200 ppm), whereas the diets of the other groups were supplemented with 3% of fish oil and the same doses of vitamin E. The performances of the hens and egg weights were not affected either by the type of lipid supplement or by the vitamin level. The treatment with fish oil caused a dramatic increase (

Effects of runoff thresholds on flood frequency distributions

International audienceRunoff generation during extreme floods usually occurs whenever rainfall forcing exceeds a given threshold. In many cases, different thresholds may be identified as responsible of the hydrological losses during ordinary events or extraordinary events at the basin scale. Such thresholds are shown to be related to the dynamics of soil saturation of the river basin and to account for the high skewness of their annual flood distributions. In basins where ordinary floods are mostly due to a small portion of the surface which is particularly prone to produce runoff, depending on permeability of a river basin and its antecedent soil moisture conditions, severe rainfall may exceed a basin-wide soil storage threshold and produce the so-called outlier events responsible of the high skewness of floods distributions. In this context, the derived theoretical model based on the concept of variable contributing area to peak flow proposed by Iacobellis and Fiorentino (2000) was generalized with the aim of incorporating such kind of dynamics in the description of the phenomena. The work produced a new formulation of the derived distribution where the two runoff components are explicitly considered. The present work was validated by using as test site a group of basins belonging to Southern Italy and characterized by flood distributions with high skewness. The application of the proposed model provided a good fitting to the observed distributions. Moreover, model parameters were found to be strongly related to physiographic basin characteristics giving consistency to the modelling assumptions