Hybrid resampling methods for confidence intervals: comment

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Practical higher-order smoothing of the bootstrap

In the context of functional estimation, the bootstrap approach amounts to substitution of the empirical distribution function for the unknown underlying distribution in the definition of the functional. A smoothed bootstrap alternative substitutes instead a smoothed version of the empirical distribution function, obtained by kernel smoothing of the given data sample. It may be theoretically advantageous to base such a smoothed bootstrap estimator on a higher-order kernel density estimator. Such density estimators necessarily take negative values, which creates a practical problem when simulation is to be used in construction of the bootstrap estimator. We illustrate how a negativity correction may be combined with rejection sampling to make higher-order smoothing feasible in the bootstrap context. Estimation of the variance of a sample quantile is examined both theoretically and in a simulation study.published_or_final_versio

Distribution of likelihood-based p-values under a local alternative hypothesis

We consider inference on a scalar parameter of interest in the presence of a nuisance parameter, using a likelihood-based statistic which is asymptotically normally distributed under the null hypothesis. Higher-order expansions are used to compare the repeated sampling distribution, under a general contiguous alternative hypothesis, of pp-values calculated from the asymptotic normal approximation to the null sampling distribution of the statistic with the distribution of pp-values calculated by bootstrap approximations. The results of comparisons in terms of power of different testing procedures under an alternative hypothesis are closely related to differences under the null hypothesis, specifically the extent to which testing procedures are conservative or liberal under the null. Empirical examples are given which demonstrate that higher-order asymptotic effects may be seen clearly in small-sample contexts

Consistency of a hybrid block bootstrap for distribution and variance estimation for sample quantiles of weakly dependent sequences

Consistency and optimality of block bootstrap schemes for distribution and variance estimation of smooth functionals of dependent data have been thoroughly investigated by Hall, Horowitz & Jing (1995), among others. However, for nonsmooth functionals, such as quantiles, much less is known. Existing results, due to Sun & Lahiri (2006), regarding strong consistency for distribution and variance estimation via the moving block bootstrap (MBB) require that b→∞, where b=⌊n/ℓ⌋ is the number of resampled blocks to be pasted together to form the bootstrap data series, n is the available sample size, and ℓ is the block length. Here we show that, in fact, weak consistency holds for any b such that 1≤b=O(n/ℓ). In other words we show that a hybrid between the subsampling bootstrap (b=1) and MBB is consistent. Empirical results illustrate the performance of hybrid block bootstrap estimators for varying numbers of blocks

Bak-Sneppen backwards

We study the backwards Markov chain for the Bak–Sneppen model of biological evolution and derive its corresponding reversibility equations. We show that, in contrast to the forwards Markov chain, the dynamics of the backwards chain explicitly involve the stationary distribution of the model, and from this we derive a functional equation that the stationary distribution must satisfy. We use this functional equation to derive differential equations for the stationary distribution of Bak–Sneppen models in which all but one or all but two of the fitnesses are replaced at each step, subject to certain conditions on the relative locations of the replaced species. This gives a unified way of deriving Schlemm’s expressions for the stationary distributions of the isotropic four-species model, the isotropic five-species model, and the anisotropic three-species model

Preventing Advanced Persistent Threats in Complex Control Networks

An Advanced Persistent Threat (APT) is an emerging attack against Industrial Control and Automation Systems, that is executed over a long period of time and is difficult to detect. In this context, graph theory can be applied to model the interaction among nodes and the complex attacks affecting them, as well as to design recovery techniques that ensure the survivability of the network. Accordingly, we leverage a decision model to study how a set of hierarchically selected nodes can collaborate to detect an APT within the network, concerning the presence of changes in its topology. Moreover, we implement a response service based on redundant links that dynamically uses a secret sharing scheme and applies a flexible routing protocol depending on the severity of the attack. The ultimate goal is twofold: ensuring the reachability between nodes despite the changes and preventing the path followed by messages from being discovered.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Effect of Substrate Characteristics on the Growth and Sporulation of Two Biocontrol Microorganisms during Solid State Cultivation

Biocontrol agents are a group of naturally occurring organisms capable of interrupting the lifespan and suppressing the propagation of disease organisms. The use of biocontrol agents offers an environment-friendly and sustainable solution to the synthetic agrochemicals. In this study, we investigated parboiled rice and millets as substrates for spore production of two model biocontrol microorganisms (Bacillus pumilus and Streptomyces griseus) under solid state cultivation (SSC) conditions. The effects of cultivation parameters such as initial moisture content, water activity, and cultivation time on microbial growth and spore production were studied. Furthermore, texture profile analysis was performed to test the stress and strain curve and the hardness and stickiness of the substrates. The greatest spore production occurred at 50% moisture content with millets as a substrate, yielding a count of 1.34 × 108 spores/g-wet-substrate enumerated with plate count analysis and 1.70 × 108 events/g-wet-substrate using flow cytometry analysis. Substrate texture profile was highly correlative to the initial moisture content and substrate type and all proved to be essential process variables in controlling the bacterial growth and sporulation during SSC processes

Continuity of retail therapy of fashion product shopping - A daily diary analysis -

Since the late 2000s, healing which is comforts and heals the tiredness has been emerging as a consumer trend, from economic recession and social relationships. This is emerging through consumers’ attitudes about their present happiness. Previous studies have explained that consumers can feel better through shopping, and introduced concepts such as \u27Retail Therapy\u27 or \u27Therapy Shopping\u27. This study analyzes the participants’ diary for a week to find the mechanism of retail therapy effect and continuity

Coulomb Explosion Dynamics of Chlorocarbonylsulfenyl Chloride

The Coulomb explosion dynamics following strong field ionization of chlorocarbonylsulfenyl chloride was studied using multimass coincidence detection and covariance imaging analysis, supported by density functional theory calculations. These results show evidence of multiple dissociation channels from various charge states. Double ionization to low-lying electronic states leads to a dominant C-S cleavage channel, while higher states can alternatively correlate to the loss of Cl+. Triple ionization leads to a double dissociation channel, the observation of which is confirmed via three-body covariance analysis, while further ionization leads primarily to atomic or diatomic fragments whose relative momenta depend strongly on the starting structure of the molecule