Record tests to detect non-stationarity in the tails with an application to climate change

The analysis of trends and other non-stationary behaviours at the extremes of a series is an important problem in global warming. This work proposes and compares several statistical tools to analyse that behaviour, using the properties of the occurrence of records in i.i.d. series. The main difficulty of this problem is the scarcity of information in the tails, so it is important to obtain all the possible evidence from the available data. First, different statistics based on upper records are proposed, and the most powerful is selected. Then, using that statistic, several approaches to join the information of four types of records, upper and lower records of forward and backward series, are suggested. It is found that these joint tests are clearly more powerful. The suggested tests are specifically useful in analysing the effect of global warming in the extremes, for example, of daily temperature. They have a high power to detect weak trends and can be widely applied since they are non-parametric. The proposed statistics join the information of M independent series, which is useful given the necessary split of the series to arrange the data. This arrangement solves the usual problems of climate series (seasonality and serial correlation) and provides more series to find evidence. These tools are used to analyse the effect of global warming on the extremes of daily temperature in Madrid.

ON ESTIMATION OF STRESS-STRENGTH RELIABILITY USING LOWER RECORD VALUES FROM ODD GENERALIZED EXPONENTIAL - EXPONENTIAL DISTRIBUTION

This research paper aims to find the estimated values closest to the true values of the reliability functionunder lower record values and to know how to obtain these estimated values using point estimation methodsor interval estimation methods. This helps researchers later in obtaining values of the reliability function intheory and then applying them to reality which makes it easier for the researcher to access the missing datafor long periods such as weather. We evaluated the stress–strength model of reliability based on point andinterval estimation for reliability under lower records by using Odd Generalize Exponential–Exponentialdistribution (OGEE) which has an important role in the lifetime of data. After that, we compared theestimated values of reliability with the real values of it. We analyzed the data obtained by the simulationmethod and the real data in order to reach certain results. The Numerical results for estimated values ofreliability supported with graphical illustrations. The results of both simulated data and real data gave us thesame coverage.

Inferences for generalized Topp-Leone distribution under dual generalized order statistics with applications to Engineering and COVID-19 data

This article accentuates the estimation of a two-parameter generalized Topp-Leone distribution using dual generalized order statistics (dgos). In the part of estimation, we obtain maximum likelihood (ML) estimates and approximate confidence intervals of the model parameters using dgos, in particular, based on order statistics and lower record values. The Bayes estimate is derived with respect to a squared error loss function using gamma priors. The highest posterior density credible interval is computed based on the MH algorithm. Furthermore, the explicit expressions for single and product moments of dgos from this distribution are also derived. Based on order statistics and lower records, a simulation study is carried out to check the efficiency of these estimators. Two real life data sets, one is for order statistics and another is for lower record values have been analyzed to demonstrate how the proposed methods may work in practice.

Positive Effects of Probiotics on Motor Coordination and Brain during Moderate and High-Intensity Exercise in Adolescent Female Mice

Objectives This study aimed to investigate the effects of probiotics on inflammatory cytokines, neurotransmitters, and motor functions during different levels of exercise. Methods Female adolescent mice (n=140) were divided into two groups, of which one group was fed probiotics and the other group was not. For both groups, three levels of exercise were conducted: non-exercise, moderate-intensity exercise, and high-intensity exercise. Probiotics acquisition and aerobic treadmill exercise were the main variables during the growth period. We evaluated motor function with a rotarod test and analyzed cytokines and neurotransmitters in the cerebellum. Results In acceleration mode, the moderate and high-intensity exercise groups showed longer running times than the non-exercise groups (P<0.001). Also, the probiotic-ingestion group had longer latency before falling than those who did not take probiotics in both the high-intensity and the non-exercise groups (P=0.002, P=0.002, respectively). In steady-state mode, the non-exercise group showed lower records compared with the moderate and high-intensity exercise groups (P=0.017, P=0.004, respectively). The inflammatory cytokine levels were high in the groups that performed moderate and high-intensity exercises, but the high levels were relieved in those taking probiotics. The GABA concentration was high for the exercise group and the probiotic-ingestion group. Conclusion Taken together, probiotics help improve motor skills during moderate and high-intensity exercise and help relieve inflammatory responses in the brain. Thus, we suggest that probiotics can be a useful supplement for brain and body development during exercise in adolescence.

Records of Surface Meteorological Elements and their Applications in Alexandria Eastern Harbour, Egypt

The surface meteorological elements, namely: air temperature, wind regime (speed and direction), dew point temperature, relative humidity and atmospheric pressure were considered; to describe the general meteorological conditions over Alexandria Eastern Harbour (AEH). These conditions were then applied to calculate some important physical properties of the Harbour’s surface waters: sea surface temperature (SST), the evaporation rates and the net surface heat flux. The period of investigation extended from 01.01.2019 to 31.12.2020. The air temperature distribution over AEH reflected a seasonal variability with higher values in spring/summer and lower records in autumn/winter. The dominant wind direction was NNW with more than 40% occurrence and the average wind speed was 4.11 m/s. The inverse relationship between atmospheric pressure and air temperature was clear. The SST over the study period showed the same seasonal pattern in the air temperature. The mean daily evaporation from AEH surface water follows the pattern of air temperature variations to a considerable extent. The maximum mean monthly evaporation of 14 cm (0.14 m) occurred in July and August, while the minimum of 6 cm (0.06 m) occurred in January. This was associated with a volume loss of 0.389x106 m3 in July and of 0.171x106 m3 in January from AEH surface waters. The solar radiation (Qs) reached its maximum value in May (383 Wm-2) and its lowest value in September (258 Wm-2). The net surface heat in AEH (Qnet) showed a gain in four successive months: March-June, and a loss in the remaining period: July-September. Keywords: Alexandria Eastern Harbour

Bayesian Prediction for Exponentiated Generalized Xgamma Distribution Based on Dual Generalized Order Statistics with Application to Poverty and COVID-19 Mortality Rates

Statistical prediction is one of the most important problems in life testing; it has been applied in medicine, engineering, business and other areas as well. In this paper, the exponentiated generalized xgamma distribution is introduced as an application on the exponentiated generalized general class of distributions. Bayesian point and interval prediction of exponentiated generalized xgamma distribution based on dual generalized order statistics are considered. All results are specialized to lower records. The results are verified using simulation study as well as applications to real data sets to demonstrate the flexibility and potential applications of the distribution.

Inference of stress-strength reliability for two-parameter of exponentiated Gumbel distribution based on lower record values

The two-parameter of exponentiated Gumbel distribution is an important lifetime distribution in survival analysis. This paper investigates the estimation of the parameters of this distribution by using lower records values. The maximum likelihood estimator (MLE) procedure of the parameters is considered, and the Fisher information matrix of the unknown parameters is used to construct asymptotic confidence intervals. Bayes estimator of the parameters and the corresponding credible intervals are obtained by using the Gibbs sampling technique. Two real data set is provided to illustrate the proposed methods.

Record Tests to Detect Non Stationarity in the Tails With an Application to Climate Change

The analysis of non stationary behaviours and trends in the extremes of a series is an important problem in global warming. This work develops statistical tools to analyse that behaviour, using the properties of the occurrence of records in i.i.d. series. The main difficulty of this problem is the scarcity of information in the tails, so that it is important to obtain all the possible evidences from the data available. To that end, first, different statistics based on upper records are proposed and the most powerful is selected. Then, using that statistic, several approaches to join the information of four types of records, upper and lower records of forward and backward series, are suggested. It is found than these joint tests are clearly more powerful. The suggested tests are specifically useful in the analysis of the effect of global warming in the extremes, for example of daily temperature. They have a high power to detect weak trends and they can be widely applied, since they are non parametric. The proposed statistics join the information of M independent series, what is useful given the necessary split of the series to arrange the data. This arrangement solves usual problems of climate series (seasonality and serial correlation) and provides more series to find evidences. These tools are used to analyse the effect of global warming in the extremes of daily temperature in Madrid.

On generalizations of the optimal choice problem

The article is dedicated to some generalizations of the classical optimal choice problem (the fastidious bride problem, the secretary problem). Let there be a sequence of n identically distributed random variables on the interval [0, 1]. Getting consistently observed values of these variables, we should stop at some moment on one of them, accepting it as the initial point for counting upper or lower record values. In the optimal choice problem and its generalizations, it is needed to make the correct choice of the initial point of counting records, in order to guess the place of the last record (the classical optimal choice problem) or to maximize the expected sum of upper and/or lower record values or the expected total number of upper and/or lower records, obtained by this procedure. A review of results on the uniform distribution of the random variables and some new results concerning the exponential distribution are presented.

Aleyrodidae in three forest fragments in the state of Rio de Janeiro, Brazil

ABSTRACT: Studies that analyze the occurrence of whiteflies in forest environments are virtually non-existent, which is not justifiable given the ecological and agronomic importance of this insect group. The study aimed to evaluate the occurrence of Aleyrodidae collected from May/2013 to May/2014 in three Atlantic forest fragments in state of Rio de Janeiro, Brazil. Of all, 1,212 puparia were collected, and five genera and seven species of whiteflies occurring in nine hosts were identified. Aleuropleurocelus cecropiae was the only aleyrodid registered simultaneously occurring in Cecropia hololeuca in the three environments, with lower records in the two fragments considered as less anthropized. For the first time, Aleurothrixus floccosus was registered on Handroanthus ochraceus and Mangifera indica. In addition, it was observed the first register of Bemisia tabaci on Commelina benghalensis and Caesalpinia pluviosa. Minutaleyrodes minuta on Syzygium cumini was also the register of a new occurrence.