On the testing hypothesis in uniform family of distributions with nuisance parameter

The problem of finding optimal tests in the family of uniform distributions is investigated. The general forms of the uniformly most powerful and generalized likelihood ratio tests are derived. Moreover, the problem of finding the uniformly most powerful unbiased test for testing two-sided hypothesis in the presence of nuisance parameter is investigated, and it is shown that such a test is equivalent to the generalized likelihood ratio test for the same problem. The simulation study is performed to evaluate the performance of power function of the tests.

Stress-Strength Parameter Estimation under Small Sample Size: A Testing Hypothesis Approach

In this paper, uniformly most powerful unbiased test for testing the stress-strength model has been presented for the first time. The end of the paper is recommending a method which is appropriate for no large data where a normal asymptotic distribution is not applicable. The previous methods for inference on stress-strength models use almost all the asymptotic properties of maximum likelihood estimators. The distribution of components is considered exponential and generalized logistic. A corresponding unbiased confidence interval is constructed, too. We compare presented methodology with previous methods and show the method of this paper is logically better than other methods. Interesting result is that our recommended method not only uses from small sample size but also has better result than other ones.

Assessing computational variant effect predictors with a large prospective cohort

Computational predictors can help interpret pathogenicity of human genetic variants, especially for the majority of variants where no experimental data are available. However, because we lack a high-quality unbiased test set, identifying the best-performing predictors remains a challenge. To address this issue, we evaluated missense variant effect predictors using genotypes and traits from a prospective cohort. We considered 139 gene-trait combinations with rare-variant burden association based on at least one of four systematic studies using phenotypes and whole-exome sequences from ~200K UK Biobank participants. Using an evaluation set of 35,525 rare missense variants and the relevant associated traits, we assessed the correlation of participants' traits with scores derived from 20 computational variant effect predictors. We found that two predictors—VARITY and REVEL—outperformed all others according to multiple performance measures. We expect that this study will help in selecting variant effect predictors, for both research and clinical purposes, while providing an unbiased benchmarking strategy that can be applied to additional cohorts and predictors.

Rapid cross-sensory adaptation of self-motion perception

Perceptual adaptation is often studied within a single sense. However, our experience of the world is naturally multisensory. Here, we investigated cross-sensory (visual vestibular) adaptation of self motion perception. It was previously found that relatively long visual self-motion stimuli (greater or equal to 15s) are required to adapt subsequent vestibular perception, and that shorter duration stimuli do not elicit cross sensory (visual vestibular) adaptation. However, it is not known whether several discrete short duration stimuli may lead to cross sensory adaptation (even when their sum, if presented together, would be too short to elicit cross sensory adaptation). This would suggest that the brain monitors and adapts to supra modal statistics of events in the environment. Here we investigated whether cross sensory (visual vestibular) adaptation occurs after experiencing several short (1s) self-motion stimuli. Forty five participants discriminated the headings of a series of self motion stimuli. To expose adaptation effects, the trials were grouped in 140 batches, each comprising three prior trials, with headings biased to the right or left, followed by a single unbiased test trial. Right, and left biased batches were interleaved pseudo randomly. We found significant adaptation in both cross sensory conditions (visual prior and vestibular test trials, and vice versa), as well as both unisensory conditions (when prior and test trials were of the same modality, either visual or vestibular). Fitting the data with a logistic regression model revealed that adaptation was elicited by the prior stimuli (not prior choices). These results suggest that the brain monitors supra modal statistics of events in the environment, even for short duration stimuli, leading to functional (supra modal) adaptation of perception.

Characterizing Continuous Manipulation Families for Dexterous Soft Robot Hands

There has been an explosion of ideas in soft robotics over the past decade, resulting in unprecedented opportunities for end effector design. Soft robot hands offer benefits of low-cost, compliance, and customized design, with the promise of dexterity and robustness. The space of opportunities is vast and exciting. However, new tools are needed to understand the capabilities of such manipulators and to facilitate manipulation planning with soft manipulators that exhibit free-form deformations. To address this challenge, we introduce a sampling based approach to discover and model continuous families of manipulations for soft robot hands. We give an overview of the soft foam robots in production in our lab and describe novel algorithms developed to characterize manipulation families for such robots. Our approach consists of sampling a space of manipulation actions, constructing Gaussian Mixture Model representations covering successful regions, and refining the results to create continuous successful regions representing the manipulation family. The space of manipulation actions is very high dimensional; we consider models with and without dimensionality reduction and provide a rigorous approach to compare models across different dimensions by comparing coverage of an unbiased test dataset in the full dimensional parameter space. Results show that some dimensionality reduction is typically useful in populating the models, but without our technique, the amount of dimensionality reduction to use is difficult to predict ahead of time and can depend on the hand and task. The models we produce can be used to plan and carry out successful, robust manipulation actions and to compare competing robot hand designs.

Correlability of solar wind with seismic events in the Balkan peninsula zone

The Solar Heliospheric Observatory (SOHO) satellite was launched on the 2nd of December 1995 at L1 Lagrange point (1.5x106 km from Earth) with the purpose of gathering data for helioseismology, remote sensing of the solar atmosphere, and solar wind in situ. The satellite was positioned into orbit in early 1996, with data acquisition expected to commence on January 20th. The correlation between increased values of solar wind parameters and earthquakes in the Balkan peninsula zone between 1996 and 2018 was made possible by data obtained through continuous proton density and proton velocity monitoring. The assessment of the anomalous threshold was based on statistically determined parameters due to the huge fluctuation of solar wind over time and distinct value increases of proton density and speed. Visual representations of proton density and proton speed were created for the time window preceding each earthquake after defining the boundary between normal and anomalous values. According to the chart analysis, increased proton density occurred in 40 of the 50 cases observed, whereas increased proton velocity appeared in 28 of the 50 cases. Using hypergeometrical probability and an unbiased test with randomly generated parameters, the discovered correlation was statistically verified. A retrospective selection bias analysis is also provided in the research paper.

Estimating COVID-19 Virus Prevalence from Records of Testing Rate and Test Positivity

ABSTRACTIntroductionPCR testing for COVID-19 is not done at random but selectively on suspected cases. This paper presents a method to estimate a “genuine Virus Prevalence” by quantifying and removing the bias related to selective testing.MethodsData used are from nine (9) neighbouring countries in Western Europe that record similar epidemic trends despite differences in Testing Rate. Regression analysis is used to establish a relationship of declining Test Positivity with increased Testing Rate. By extrapolating this trend to an “infinitely complete” Testing Rate, an unbiased Test Positivity or “genuine Virus Prevalence” is computed. Via pairing of “genuine Virus Prevalence” with Excess-Deaths, a “genuine Infection Fatality Rate (IFR) is also derived.ResultsPeak levels of “genuine Virus Prevalence” were around 0.5 to 2% during the 1st epidemic “wave” (week 10 to week 20) and are approaching similar levels in the ongoing 2nd “wave” (week 34 onward). “Genuine Virus Prevalence” estimates are close to reported Seroprevalence in the studied countries with a correlation coefficient of 0.58. “Genuine” IFR is found comparable to closed-community model IFR. Finally, results of community mass-testing in Slovakia are within the estimated range of “genuine Virus Prevalence”.ConclusionsEstimates of “genuine Virus Prevalence” benchmark favourably to other indications of virus prevalence suggesting the estimation method is robust and potentially deployable beyond this initial dataset of countries. “Genuine Virus Prevalence” curves suggest that during the 1st epidemic “wave”, curve flattening and waning happened at very modest levels of infection spread, either naturally or facilitated by government measures.

Morphological redescriptions and neotypification of two poorly known tintinnine ciliates (Alveolata, Ciliophora, Tintinnina), with a phylogenetic investigation based on SSU rRNA gene sequences

Two poorly known tintinnine ciliates collected from the coastal waters of PR China, viz., Codonellopsis mobilis Wang, 1936 and Tintinnopsis chinglanensis Nie & Ch’eng, 1947, were redescribed and neotypified using live observation, protargol staining and SSU rRNA gene sequencing. Ciliature information and SSU rRNA gene sequence data of both species were revealed for the first time and improved diagnoses were given based on the original descriptions and data from the present study. Further phylogenetic analyses inferred from SSU rRNA gene sequences and morphological data suggested that the genus Tintinnopsis is polyphyletic and that the genus Codonellopsis is non-monophyletic. The approximately unbiased test, however, does not reject the possibility that Codonellopsis is monophyletic.

Are Corporate Bond Defaults Contagious across Sectors?

Corporate bond defaults in different sectors often increase suddenly at roughly similar times, although some sectors see default rates jump earlier than others. This could reflect contagion among sectors—specifically, defaults in one sector leading to credit stresses in other sectors of the economy that would not otherwise have seen stresses. To complicate matters, simple correlation-based tests for contagion are often biased, reflecting increased volatility in periods of stress. This paper uses sectoral default data from over 30 sectors to test for signs of contagion over the past 30 years. While jumps in sectoral default rates do often coincide, there is no consistent evidence of contagion across different periods of stress from unbiased test results. Instead, coincident jumps in sectoral default rates are likely to reflect common macroeconomic shocks.

Multi-gene incongruence consistent with hybridisation in Cladocopium (Symbiodiniaceae), an ecologically important genus of coral reef symbionts

Coral reefs rely on their intracellular dinoflagellate symbionts (family Symbiodiniaceae) for nutritional provision in nutrient-poor waters, yet this association is threatened by thermally stressful conditions. Despite this, the evolutionary potential of these symbionts remains poorly characterised. In this study, we tested the potential for divergent Symbiodiniaceae types to sexually reproduce (i.e. hybridise) within Cladocopium, the most ecologically prevalent genus in this family. With sequence data from three organelles (cob gene, mitochondrion; psbAncr region, chloroplast; and ITS2 region, nucleus), we utilised the Incongruence Length Difference test, Approximately Unbiased test, tree hybridisation analyses and visual inspection of raw data in stepwise fashion to highlight incongruences between organelles, and thus provide evidence of reticulate evolution. Using this approach, we identified three putative hybrid Cladocopium samples among the 158 analysed, at two of the seven sites sampled. These samples were identified as the common Cladocopium types C40 or C1 with respect to the mitochondria and chloroplasts, but the rarer types C3z, C3u and C1# with respect to their nuclear identity. These five Cladocopium types have previously been confirmed as evolutionarily distinct and were also recovered in non-incongruent samples multiple times, which is strongly suggestive that they sexually reproduced to produce the incongruent samples. A concomitant inspection of next generation sequencing data for these samples suggests that other plausible explanations, such as incomplete lineage sorting or the presence of co-dominance, are much less likely. The approach taken in this study allows incongruences between gene regions to be identified with confidence, and brings new light to the evolutionary potential within Symbiodiniaceae.