Skilled Mutual Fund Selection: False Discovery Control Under Dependence

Selecting skilled mutual funds through the multiple testing framework has received increasing attention from finance researchers and statisticians. The intercept α of Carhart four-factor model is commonly used to measure the true performance of mutual funds, and positive α’s are considered as skilled. We observe that the standardized ordinary least-square estimates of α’s across the funds possess strong dependence and nonnormality structures, indicating that the conventional multiple testing methods are inadequate for selecting the skilled funds. We start from a decision theoretical perspective, and propose an optimal multiple testing procedure to minimize a combination of false discovery rate and false nondiscovery rate. Our proposed testing procedure is constructed based on the probability of each fund not being skilled conditional on the information across all of the funds in our study. To model the distribution of the information used for the testing procedure, we consider a mixture model under dependence and propose a new method called “approximate empirical Bayes” to fit the parameters. Empirical studies show that our selected skilled funds have superior long-term and short-term performance, for example, our selection strongly outperforms the S&P 500 index during the same period.</p

Optimal and fast confidence intervals for hypergeometric successes

We present an efficient method of calculating exact confidence intervals for the hypergeometric parameter representing the number of “successes,” or “special items,” in the population. The method inverts minimum-width acceptance intervals after shifting them to make their endpoints nondecreasing while preserving their level. The resulting set of confidence intervals achieves minimum possible average size, and even in comparison with confidence sets not required to be intervals it attains the minimum possible cardinality most of the time, and always within 1. The method compares favorably with existing methods not only in the size of the intervals but also in the time required to compute them. The available R package hyperMCI implements the proposed method.</p

Catalytic Asymmetric Synthesis of 3‑Hydroxy-3-trifluoromethyl Benzofuranones via Tandem Friedel–Crafts/Lactonization Reaction

A highly enantioselective and regioselective chiral Lewis acid catalyzed tandem Friedel–Crafts/lactonization reaction is reported, providing direct access to plenty of 3-hydroxy-3-trifluoromethyl benzofuran-2-ones in up to 94% yields with up to >99% ee. Mechanistic study reveals that the interactions between the phenolic hydroxyl group and trifluoropyruvate are the most likely contributing factor to the high enantio- and regioselectivity. Optically pure (−)-BHFF can be obtained in gram-scale with 0.05 mol % catalyst, demonstrating the potentially utility of this method in medicinal chemistry

Hierarchical Neyman-Pearson Classification for Prioritizing Severe Disease Categories in COVID-19 Patient Data

COVID-19 has a spectrum of disease severity, ranging from asymptomatic to requiring hospitalization. Understanding the mechanisms driving disease severity is crucial for developing effective treatments and reducing mortality rates. One way to gain such understanding is using a multi-class classification framework, in which patients’ biological features are used to predict patients’ severity classes. In this severity classification problem, it is beneficial to prioritize the identification of more severe classes and control the “under-classification” errors, in which patients are misclassified into less severe categories. The Neyman-Pearson (NP) classification paradigm has been developed to prioritize the designated type of error. However, current NP procedures are either for binary classification or do not provide high probability controls on the prioritized errors in multi-class classification. Here, we propose a hierarchical NP (H-NP) framework and an umbrella algorithm that generally adapts to popular classification methods and controls the under-classification errors with high probability. On an integrated collection of single-cell RNA-seq (scRNA-seq) datasets for 864 patients, we explore ways of featurization and demonstrate the efficacy of the H-NP algorithm in controlling the under-classification errors regardless of featurization. Beyond COVID-19 severity classification, the H-NP algorithm generally applies to multi-class classification problems, where classes have a priority order.</p

<i>γ</i>-GTP activity in gonad (A) and GSI (B) of exposed male goldfish.

<p>Male goldfish were exposed to dechlorinated tap water, 100% treated effluent, 0.5% diluted MBR outlet, and 0.5% diluted landfill leachate (designated Tap Water, Effluent, MBR Outlet, and Leachate, respectively) for 28 days in a semi-static exposure system. Data are presented as the mean ± standard deviation (n = 24). Values with different letters denote statistically significant differences according to a one-way ANOVA analysis (<i>p</i><0.05).</p

Mean concentrations of target EEs measured by GC-MS and EEQs of different samples.

<p>The estrogen equivalent quantity (EEQ) was defined as the sum of the concentration for each individual compound after multiplying an estradiol equivalency factor derived from previous studies <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0095597#pone.0095597-Behnisch1" target="_blank">[17]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0095597#pone.0095597-Api1" target="_blank">[73]</a>–<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0095597#pone.0095597-Liu1" target="_blank">[76]</a>. E₁, E₂, E₃, EE₂, and DNOP were under detection limits.</p

Technical data of leachate and treated effluent.

<p>COD_Cr: chemical oxygen demand; BOD₅: five-day's biochemical oxygen demand; TN: total nitrogen; TP: total phosphorus; TSS: total suspended solids.</p

Asymmetric Annulation of Donor–Acceptor Cyclopropanes with Dienes

An efficient [4 + 3] cycloaddition reaction of D–A cyclopropanes with dienes has been successfully developed. The reaction proceeds well with various dienolsilyl ethers in the presence of Lewis acid, delivering a variety of cycloheptenes and [<i>n</i>,5,0]­carbobicycles with excellent stereoselectivity. The asymmetric version of this reaction is also realized using a newly designed chiral Cy-TOX ligand, providing a new approach to access optically active cycloheptenes and [<i>n</i>,5,0]­carbobicycles. Mechanisic study reveals that the reaction involves a stepwise pathway, which undergoes an unusual ring opening of five-membered [3 + 2] intermediate and sequential intramolecular cyclization to afford the thermodynamically stable [4 + 3] annulation product

Asymmetric Annulation of Donor–Acceptor Cyclopropanes with Dienes

An efficient [4 + 3] cycloaddition reaction of D–A cyclopropanes with dienes has been successfully developed. The reaction proceeds well with various dienolsilyl ethers in the presence of Lewis acid, delivering a variety of cycloheptenes and [<i>n</i>,5,0]­carbobicycles with excellent stereoselectivity. The asymmetric version of this reaction is also realized using a newly designed chiral Cy-TOX ligand, providing a new approach to access optically active cycloheptenes and [<i>n</i>,5,0]­carbobicycles. Mechanisic study reveals that the reaction involves a stepwise pathway, which undergoes an unusual ring opening of five-membered [3 + 2] intermediate and sequential intramolecular cyclization to afford the thermodynamically stable [4 + 3] annulation product