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To improve nonparametric estimates of lifetime distributions, we propose using the increasing odds rate (IOR) model as an alternative to other popular, but more restrictive, 'adverse ageing' models, such as the increasing hazard rate one. This extends the scope of applicability of some methods for statistical inference under order restrictions, since the IOR model is compatible with heavy-tailed and bathtub distributions. We study a strongly uniformly consistent estimator of the cumulative distribution function of interest under the IOR constraint. Numerical evidence shows that this estimator often outperforms the classic empirical distribution function when the underlying model does belong to the IOR family. We also study two different tests to detect deviations from the IOR property and establish their consistency. The performance of these tests is also evaluated through simulations. [ABSTRACT FROM AUTHOR]

The effect of trapped non-thermal polarization force on low-frequency solitary waves (dust acoustic solitons) is addressed in a collisionless complex plasma. For this purpose, we have firstly redefined the three-dimensional Cairns–Gurevich distribution that describes, simultaneously, the evolution of the energetic ions and those trapped in the plasma potential well, and derived the associated both density and polarization force expressions. The polarization force effects are remarkably modified due to the presence of the trapped non-thermal ions. In particular, we have found that the polarization force magnitude decreases with the increase of ion non-thermality character. Next, the modifications arising in dust-acoustic (DA) solitons and its energy due to the presence of these trapped non-thermal density and polarization force are analyzed. In particular, we have found that the presence of the polarization force leads to an increase in the amplitude and width of DA solitary wave can be propagated in different complex plasma media. Finally, a complementary study on the polarization force effects on the DA energy, associated with both space and experimental dusty plasmas, is also carried out. Our numerical results have shown that more is strong the polarization force more is higher the energy transported by DA solitons. [ABSTRACT FROM AUTHOR]

The star-shaped ordering between probability distributions is a common way to express aging properties. A well-known criterion was proposed by Saunders and Moran [(1978). On the quantiles of the gamma and F distributions. Journal of Applied Probability 15(2): 426–432], to order families of distributions depending on one real parameter. However, the lifetime of complex systems usually depends on several parameters, especially when considering heterogeneous components. We extend the Saunders and Moran criterion characterizing the star-shaped order when the multidimensional parameter moves along a given direction. A few applications to the lifetime of complex models, namely parallel and series models assuming different individual components behavior, are discussed. [ABSTRACT FROM AUTHOR]

High order stop-loss transforms provide a risk measure that enables some flexibility on the weight given to high or low values of the risk. We interpret stop-loss transforms as iterated distributions and prove a recursive representation for risks expressed as convolutions. We apply this to the case of gamma distributions with integer shape parameter, the Erlang distributions, proving that high order stop-loss transforms are equivalent to the tails of the exponential distribution. The latter result is also extended to general gamma distributions. Furthermore, we prove that this equivalence to exponential tails does not hold in general, by proving that the stop-loss transform for a Weilbull distribution degenerates, unless, of course, in the exponential case. [ABSTRACT FROM AUTHOR]

The nanocomposite of WO3/Fe3O4 was prepared using a facile precipitation method and characterized by several techniques. XRD patterns showed a magnetite and a monoclinic structure, respectively, for Fe3O4 and WO3 particles. Formation of WO3/Fe3O4 nanocomposite proved using EDX spectra and also EDX element maps indicated the uniform distribution of Fe, W, and O atoms in the prepared nanocomposite. The SEM image approved a spherical shape for nanocomposite particles. Band-gap energy of WO3/Fe3O4 obtained 1.2 eV using DRS spectra. The room temperature hysteresis loops showed magnetization 21.21 emu/g for WO3/Fe3O4 particles. The synthesized magnetite photocatalyst used in treatment of yellow water as one of the effluents of the production process of TNT. Central composite experimental design applied for optimization of independent variables such as pH of the sample, dose of photocatalyst and amount of pollutant. Photodegradation efficiencies were calculated by reducing the COD values of the samples. The p-values of studied variables obtained <0.05 in ANOVA (analysis of variance) results which indicates their impact on photodegradation efficiency. The F-value and p-value of proposed model for photodegradation process were 29.65 and <0.05, respectively, in 95% confidence level. Also, the p-value of "lack-of-fit" (>0.05) showed that predicted data of the proposed model fit to actual experimental response data. A 65% reduction in the COD value of a sample was achieved under optimized conditions of pH 5, dose of photocatalyst 1.0 g⋅L−1 and amount of pollutant 20 mg⋅L−1. [ABSTRACT FROM AUTHOR]

In this study, the precipitation concentration index (PCI), the seasonal PCI (SPCI), the precipitation concentration degree (PCD), and the precipitation concentration period (PCP) were analyzed using monthly precipitation data from Serbia during the period from 1946 to 2019. The spatial distribution of annual PCI showed a uniform-to-moderate precipitation concentration over the country. The SPCI maps showed a uniform distribution of precipitation over the whole region in spring and winter and a uniform-to-moderate seasonal precipitation concentration from west to east in summer and autumn. The correlation decay distance (CDD) was calculated for each station to show the spatial variability of precipitation and to provide complementary information for precipitation concentration analysis. The obtained map showed a decreasing gradient from southwest to the north of Serbia. According to the obtained PCD maps for two sub-periods (1946–1989 and 1990–2019), it was realized that the precipitation concentration of the southern part was decreasing over time. The pattern of PCD is in line with the pattern of annual PCI and a significant positive correlation of 0.65 is observed between the PCD and annual PCI. Comparing the maps produced by the CDD and PCD, it can be concluded that the region with lower spatial variability of precipitation has the highest precipitation concentration and vice versa. The topography of the region also showed a direct relation with the spatial variability of precipitation and an indirect relation with the precipitation concentration. Hence, the higher the elevation, the higher the spatial variability of precipitation and the lower the precipitation concentration. The highest correlations are also observed between the PCD for the second sub-period and latitude, and the summer PCI and longitude at 0.75 and 0.73, respectively. [ABSTRACT FROM AUTHOR]

The convex transform order is one way to make precise comparison between the skewness of probability distributions on the real line. We establish a simple and complete characterization of when one Beta distribution is smaller than another according to the convex transform order. As an application, we derive monotonicity properties for the probability of Beta distributed random variables exceeding the mean or mode of their distribution. Moreover, we obtain a simple alternative proof of the mode‐median‐mean inequality for unimodal distributions that are skewed in a sense made precise by the convex transform order. This new proof also gives an analogous inequality for the anti‐mode of distributions that have a unique anti‐mode. Such inequalities for Beta distributions follow as special cases. Finally, some consequences for the values of distribution functions of binomial distributions near to their means are mentioned. [ABSTRACT FROM AUTHOR]

We study the problem of comparing ageing patterns of lifetimes of k-out-of-n systems with i.i.d. components. Mathematically, this reduces to being able to decide about a stochastic ordering relationship between different order statistics. We discuss such relationships with respect to second-order stochastic dominance, obtaining characterizations through the verification of relative convexity with respect to a suitably chosen reference distribution function. We introduce a hierarchy of such reference functions leading to classes, each expressing different and increasing knowledge precision about the distribution of the components lifetimes. Such classes are wide enough to include popular families of distributions, such as, for example, the increasing failure rate distributions. We derive sufficient dominance conditions depending on the identification of the class which includes the component lifetimes. We discuss the applicability of this method and characterize a test for the relative convexity, as this notion plays a central role in the proposed approach. [ABSTRACT FROM AUTHOR]

Stochastic ordering of random variables may be defined by the relative convexity of the tail functions. This has been extended to higher order stochastic orderings, by iteratively reassigning tail-weights. The actual verification of stochastic orderings is not simple, as this depends on inverting distribution functions for which there may be no explicit expression. The iterative definition of distributions, of course, contributes to make that verification even harder. We have a look at the stochastic ordering, introducing a method that allows for explicit usage, applying it to the Gamma and Weibull distributions, giving a complete description of the order of relations within each of these families. [ABSTRACT FROM AUTHOR]

In this article, we introduce the notion of trace variance function which is the trace of the variance-covariance matrix. Under some conditions, we prove that this trace variance function characterizes the Natural Exponential Family (NEF). We apply this characterization in order to estimate the distribution which belongs to some NEFs. Therefore, we introduce the estimator of this trace variance function. We give the asymptotic properties of this estimator. Finally, we illustrate our results using a simulation study. [ABSTRACT FROM AUTHOR]

In this paper, we examine the problem of estimating the parameters of the proposed Diagonal of the Modified Riesz Distribution (DMRD) defined in R r . Several methods can be used for estimating the parameters of the DMRD. In the present work, we address the issue of estimating the parameters of the DMRD through a Bayesian approach associated with Monte Carlo methods. The proposed approach is compared via a simulation study with maximum likelihood method and method of moments by calculating the Mean Square Error (MSE). [ABSTRACT FROM AUTHOR]

Background: Uterine environment and fetal period can profoundly affect health of the neonat. Hypoxia-inducible factor-1α (HIF-1α) is a transcription factor that regulates cellular stress responses and its activity is essential in both embryogenesis and postnatal life. The aim of the present study was to investigate the effects of maternal swimming on rat pups' HIF-1α levels as a key regulator of oxygen in lungs. Methods: Sixteen female Wistar rats weighing 180- 200 grams were acclimated to a new environment consisting of equal light-darkness cycle and ad lib access to chow and adapted to the stress caused by water for two weeks. The rats were divided into two swimming and control groups. Swimming training began on the first day of pregnancy in a pool and continued for 3 weeks (1 h/day, 5 days/wk). Pups' lungs were removed two days after birth and their HIF-1α concentration was determined with enzyme-linked immunosorbent assay (ELISA). Statistical analysis of the data was done using independent t-test. A p-value smaller than 0.05 was considered statistically significant. Results: Swimming lead to a significant (P<0.001) increase in the pups' lung HIF-1α levels compared with the control group. Although 3-wk period of swimming training, showed no significant increase in weight and also lung weight of newborns. Thus it can be concluded that swimming endurance training in pregnancy, can be considered as appropriate alternative in order to embryos development. Conclusion: Our research suggests that HIF-1α level is an essential element for the development of the lungs of embryos. Moreover, further studies on the lung HIF-1α levels at post-natal period with different modes of exercise will provide more clear insight into the mechanisms of the findings resulting from this study. [ABSTRACT FROM AUTHOR]

A simple and sensitive flow injection method is described for the determination of trace amounts of hydrazine, based on its inhibitory effect on the reaction between pyrogallol red and iodate in hydrochloric acid media. The reaction was monitored spectrophotometrically by measuring the change in absorbance of pyrogallol red at 470 nm. The calibration graph was linear over the range of 0.050–1.20 μg/mL, with a limit of detection of 0.03 μg/mL. The relative standard deviation for ten replicate measurements of 0.060 and 0.70 μg/mL was 2.2 and 0.50%, respectively. Potential interfering substances were studied in the presence of hydrazine. The proposed method was applied to the determination of hydrazine in water samples. [ABSTRACT FROM AUTHOR]

The nanocomposite of WO3/Fe3O4 was prepared using a facile precipitation method and characterized by several techniques. XRD patterns showed a magnetite and a monoclinic structure, respectively, for Fe3O4 and WO3 particles. Formation of WO3/Fe3O4 nanocomposite proved using EDX spectra and also EDX element maps indicated the uniform distribution of Fe, W, and O atoms in the prepared nanocomposite. The SEM image approved a spherical shape for nanocomposite particles. Band-gap energy of WO3/Fe3O4 obtained 1.2 eV using DRS spectra. The room temperature hysteresis loops showed magnetization 21.21 emu/g for WO3/Fe3O4 particles. The synthesized magnetite photocatalyst used in treatment of yellow water as one of the effluents of the production process of TNT. Central composite experimental design applied for optimization of independent variables such as pH of the sample, dose of photocatalyst and amount of pollutant. Photodegradation efficiencies were calculated by reducing the COD values of the samples. The p-values of studied variables obtained <0.05 in ANOVA (analysis of variance) results which indicates their impact on photodegradation efficiency. The F-value and p-value of proposed model for photodegradation process were 29.65 and <0.05, respectively, in 95% confidence level. Also, the p-value of "lack-of-fit" (>0.05) showed that predicted data of the proposed model fit to actual experimental response data. A 65% reduction in the COD value of a sample was achieved under optimized conditions of pH 5, dose of photocatalyst 1.0 g⋅L−1 and amount of pollutant 20 mg⋅L−1. [ABSTRACT FROM AUTHOR]