Heavy metals, uranium and thorium in agricultural soils and plants from the Buhovo region, Bulgaria

Ten soil and five plant samples from private gardens in Buhovo town and from the agriculturalarea between Buhovo town and Yana village, Bulgaria, were investigated. Inductively coupled plasma mass spectrometry was used for the determination of Cu, Pb, Zn, Cd, Hg, Ni, As, Cr, U and Th concentrations. The results showedhigher concentrations of Pb and As in soil samples. The highest contents of U and Th were determined in soils collectedfrom private gardens in Buhovo town and sample collected from the Manastirska riverside. Among the plant samples,the highest uptake of Pb, As, Cr and Cu were established for the sunflower and wheat stems. The comparison of soiland plant samples U/Th ratios clearly indicate uranium enrichment of the sunflower and thorium enrichment of thewheat samples. In the wild briar, hawthorn and reed fruits the contents of U and Th were below the detection limit

Computing the Kolmogorov-Smirnov Distribution When the Underlying CDF is Purely Discrete, Mixed, or Continuous

The distribution of the Kolmogorov-Smirnov (KS) test statistic has been widely studied under the assumption that the underlying theoretical cumulative distribution function (CDF), F (x), is continuous. However, there are many real-life applications in which fitting discrete or mixed distributions is required. Nevertheless, due to inherent difficulties, the distribution of the KS statistic when F (x) has jump discontinuities has been studied to a much lesser extent and no exact and efficient computational methods have been proposed in the literature. In this paper, we provide a fast and accurate method to compute the (complementary) CDF of the KS statistic when F (x) is discontinuous, and thus obtain exact p values of the KS test. Our approach is to express the complementary CDF through the rectangle probability for uniform order statistics, and to compute it using fast Fourier transform (FFT). Secondly, we provide a C++ and an R implementation of the proposed method, which fills the existing gap in statistical software. We give also a useful extension of the Schmid's asymptotic formula for the distribution of the KS statistic, relaxing his requirement for F (x) to be increasing between jumps and thus allowing for any general mixed or purely discrete F (x). The numerical performance of the proposed FFT-based method, implemented both in C++ and in the R package KSgeneral, available from https://CRAN.R-project.org/package=KSgeneral, is illustrated when F (x) is mixed, purely discrete, and continuous. The performance of the general asymptotic formula is also studied

Molecular networking-assisted flavonoid profile of Gypsophila glomerata extract in relation to its protective effects on carbon tetrachloride-induced hepatorenal damage in rats

The aim of the study was to provide an in-depth characterization of the methanol-aqueous extract from the aerial parts of Gypsophila glomerata Pall. Ex Adams (Caryophyllaceae) (EGG) and to assess its protective potential on carbon tetrachloride (CCl4)-induced liver and kidney damage in male Wistar rats. Twenty-two flavonoid C-, O- and C,O-glycosides in EGG were annotated by mass spectrometry-based molecular networking; nine of them are reported in this species for the first time. Fourteen-day oral administration of EGG at a dose 200 mg kg–1 bm prevented significantly CCl4-induced liver injury, discerned by an amelioration of the markers of oxidative stress (GSH and MDA) and transaminase activity. EGG decreased the serum level of urea and creatinine as well. The observed improvement of biochemical parameters was supported by histopathological observations. The protective hepatorenal effects of EGG, rich in 2"-О-pentosyl-6-С-hexosyl-apigenin/luteolin/methylluteolin and their acetyl- and methoxycinnamoyl-derivatives, were comparable with the effects of the positive control silymarin

LC-MS analysis of phenolic compounds and oleraceins in aerial parts of Portulaca oleracea L.

Portulaca oleracea L. (purslane) is a well-known edible and ethnomedicinal plant and it has been called “vegetable for long life” in the Chinese herbal medicine. The plant is recognized for the high content of polyphenols, including flavonoids and phenolic acids.In this study, hydromethanolic purslane extracts from Bulgarian and Greek locations were screened for polyphenolic content. Based on polyphenols, saponins and DPPH antioxidant activity, an orthogonaldesign L9(34) was performed in order to improve the ultrasound assisted extraction procedure of dry and fresh plant material. An UHPLC-Orbitrap-MS method in parallel-reaction monitoring mode was developed for the simultaneous identification and quantification of 14 compounds comprising hydroxybenzoic, hydroxycinnamic and caffeoylquinic acids, as well as 2 flavonol glycosides. The quantitative analysis was validated for curve fit, range, instrumental detection limit (IDL), instrumental quantification limit (IQL), LOD, LOQ, precision, recovery and accuracy. The UHPLC-MS quantification method revealed good linearity (r2 > 0.9950), LOD < 925.85 ng/g dw and LOQ < 3055.31 ng/g dw. Moreover, 11 cylco-dopa amides (Oleraceins A-D, N-Q, S, U and W) were tentatively identified through UHPLC-MS and their MS2 mass fragmentation was described

Excess of loss reinsurance under joint survival optimality

Explicit expressions for the probability of joint survival up to time x of the cedent and the reinsurer, under an excess of loss reinsurance contract with a limiting and a retention level are obtained, under the reasonably general assumptions of any non-decreasing premium income function, Poisson claim arrivals and continuous claim amounts, modelled by any joint distribution. By stating appropriate optimality problems, we show that these results can be used to set the limiting and the retention levels in an optimal way with respect to the probability of joint survival. Alternatively, for fixed retention and limiting levels, the results yield an optimal split of the total premium income between the two parties in the excess of loss contract. This methodology is illustrated numerically on several examples of independent and dependent claim severities. The latter are modelled by a copula function. The effect of varying its dependence parameter and the marginals, on the solutions of the optimality problems and the joint survival probability, has also been explored

Optimal joint survival reinsurance: An efficient frontier approach

The problem of optimal excess of loss reinsurance with a limiting and a retention level is considered. It is demonstrated that this problem can be solved, combining specific risk and performance measures, under some relatively general assumptions for the risk model, under which the premium income is modelled by any non-negative, non-decreasing function, claim arrivals follow a Poisson process and claim amounts are modelled by any continuous joint distribution. As a performance measure, we define the expected profits at time x of the direct insurer and the reinsurer, given their joint survival up to x, and derive explicit expressions for their numerical evaluation. The probability of joint survival of the direct insurer and the reinsurer up to the finite time horizon x is employed as a risk measure. An efficient frontier type approach to setting the limiting and the retention levels, based on the probability of joint survival considered as a risk measure and on the expected profit given joint survival, considered as a performance measure is introduced. Several optimality problems are defined and their solutions are illustrated numerically on several examples of appropriate claim amount distributions, both for the case of dependent and independent claim severitie

Modelling the joint distribution of competing risks survival times using copula functions

The problem of modelling the joint distribution of survival times in a competing risks model, using copula functions is considered. In order to evaluate this joint distribution and the related overall survival function, a system of non-linear differential equations is solved, which relates the crude and net survival functions of the modelled competing risks, through the copula. A similar approach to modelling dependent multiple decrements was applied by Carriere (1994) who used a Gaussian copula applied to an incomplete double decrement model which makes it difficult to calculate any actuarial functions and draw relevant conclusions. Here, we extend this methodology by studying the effect of complete and partial elimination of up to four competing risks on the overall survival function, the life expectancy and life annuity values. We further investigate how different choices of the copula function affect the resulting joint distribution of survival times and in particular the actuarial functions which are of importance in pricing life insurance and annuity products. For illustrative purposes, we have used a real data set and used extrapolation to prepare a complete multiple decrement model up to age 120. Extensive numerical results illustrate the sensitivity of the model with respect to the choice of copula and its parameter(s)