The Machines Aren’t Taking Over (Yet): An Empirical Comparison of Traditional, Profiling, and Machine Learning Approaches to Criterion-Related Validation

Criterion-related validation (CRV) studies are used to demonstrate the effectiveness of selection procedures. However, traditional CRV studies require significant investment of time and resources, as well as large sample sizes, which often create practical challenges. New techniques, which use machine learning to develop classification models from limited amounts of data, have emerged as a more efficient alternative. This study empirically investigates the effectiveness of traditional CRV with a variety of profiling approaches and machine learning techniques using repeated cross-validation. Results show that the traditional approach generally performs best both in terms of predicting performance and larger group differences between candidates identified as top or non-top performers. In addition to empirical effectiveness, other practical implications are discussed

Comparing Empirically Keyed and Random Forest Scoring Models in Biodata Assessments

Effective pre-hire assessments impact organizational outcomes. Recent developments in machine learning provide an opportunity for practitioners to improve upon existing scoring methods. This study compares the effectiveness of an empirically keyed scoring model with a machine learning, random forest model approach in a biodata assessment. Data was collected across two organizations. The data from the first sample (N=1,410), was used to train the model using sample sizes of 100, 300, 500, and 1,000 cases, whereas data from the second organization (N=524) was used as an external benchmark only. When using a random forest model, predictive validity rose from 0.382 to 0.412 in the first organization, while a smaller increase was seen in the second organization. It was concluded that predictive validity of biodata measures can be improved using a random forest modeling approach. Additional considerations and suggestions for future research are discussed

Direct Substrate Delivery into Mitochondrial-Fission Deficient Pancreatic Islets Rescues Insulin Secretion

In pancreatic beta cells, mitochondrial bioenergetics control glucose-stimulated insulin secretion (GSIS). Mitochondrial dynamics are generally associated with quality control, maintaining the functionality of bioenergetics. By acute pharmacological inhibition of mitochondrial fission protein Drp1, we here demonstrate that mitochondrial fission is necessary for GSIS in mouse and human islets. We confirm that genetic silencing of Drp1 increases mitochondrial proton leak in MIN6 cells. However, our comprehensive analysis of pancreatic islet bioenergetics reveals that Drp1 does not control insulin secretion via its effect on proton leak but instead via modulation of glucose-fuelled respiration. Notably, pyruvate fully rescues the impaired insulin secretion of fission-deficient beta cells, demonstrating that defective mitochondrial dynamics solely impact substrate supply upstream of oxidative phosphorylation. The present findings provide novel insights in how mitochondrial dysfunction may cause pancreatic beta cell failure. In addition, the results will stimulate new thinking in the intersecting fields of mitochondrial dynamics and bioenergetics, as treatment of defective dynamics in mitochondrial diseases appears to be possible by improving metabolism upstream of mitochondria

Mitochondria and the regulation of free radical damage in the eye

Neuronal cell death can be determined by the overall level of reactive oxygen species (ROS) resulting from the combination of extrinsic sources and intrinsic production as a byproduct of oxidative phosphorylation. Key controllers of the intrinsic production of ROS are the mitochondrial uncoupling proteins (UCPs). By allowing a controlled leak of protons across the inner mitochondrial membrane activation of these proteins can decrease ROS and promote cell survival. In both primate models of Parkinson’s disease and mouse models of seizures, increased activity of UCP2 significantly increased neuronal cells survival. In the retina UCP2 is expressed in many neurons and glial cells, but was not detected in rod photoreceptors. Retinal ganglion cell survival following excitotoxic damage was much greater in animals overexpressing UCP2. Traditional Chinese medicines, such as an extract of Cistanche tubulosa, may provide benefit by altering mitochondrial metabolism

Insights into the evolution of Darwin's finches from comparative analysis of the Geospiza magnirostris genome sequence

Background: A classical example of repeated speciation coupled with ecological diversification is the evolution of 14 closely related species of Darwin's (Galápagos) finches (Thraupidae, Passeriformes). Their adaptive radiation in the Galápagos archipelago took place in the last 2-3 million years and some of the molecular mechanisms that led to their diversification are now being elucidated. Here we report evolutionary analyses of genome of the large ground finch, Geospiza magnirostris.Results: 13,291 protein-coding genes were predicted from a 991.0 Mb G. magnirostris genome assembly. We then defined gene orthology relationships and constructed whole genome alignments between the G. magnirostris and other vertebrate genomes. We estimate that 15% of genomic sequence is functionally constrained between G. magnirostris and zebra finch. Genic evolutionary rate comparisons indicate that similar selective pressures acted along the G. magnirostris and zebra finch lineages suggesting that historical effective population size values have been similar in both lineages. 21 otherwise highly conserved genes were identified that each show evidence for positive selection on amino acid changes in the Darwin's finch lineage. Two of these genes (Igf2r and Pou1f1) have been implicated in beak morphology changes in Darwin's finches. Five of 47 genes showing evidence of positive selection in early passerine evolution have cilia related functions, and may be examples of adaptively evolving reproductive proteins.Conclusions: These results provide insights into past evolutionary processes that have shaped G. magnirostris genes and its genome, and provide the necessary foundation upon which to build population genomics resources that will shed light on more contemporaneous adaptive and non-adaptive processes that have contributed to the evolution of the Darwin's finches. © 2013 Rands et al.; licensee BioMed Central Ltd

Detection of child abuse in emergency departments: a multi-centre study

Objective: This study examines the detection rates of suspected child abuse in the emergency departments of seven Dutch hospitals complying and not complying with screening guidelines for child abuse. Design: Data on demographics, diagnosis and suspected child abuse were collected for all children aged ≤18 years who visited the emergency departments over a 6-month period. The completion of a checklist of warning signs of child abuse in at least 10% of the emergency department visits was considered to be compliance with screening guidelines. Results: A total of 24 472 visits were analysed, 54% of which took place in an emergency department complying with screening guidelines. Child abuse was suspected in 52 children (0.2%). In 40 (77%) of these 52 cases, a checklist of warning signs had been completed compared with a completion rate of 19% in the total sample. In hospitals complying with screening guidelines for child abuse, the detection rate was higher (0.3%) than in those not complying (0.1%, p<0.001). Conclusion: During a 6-month period, emergency department staff suspected child abuse in 0.2% of all children visiting the emergency department of seven Dutch hospitals. The numbers of suspected abuse cases detected were low, but an increase is likely if uniform screening guidelines are widely implemented

A broad distribution of the alternative oxidase in microsporidian parasites

Microsporidia are a group of obligate intracellular parasitic eukaryotes that were considered to be amitochondriate until the recent discovery of highly reduced mitochondrial organelles called mitosomes. Analysis of the complete genome of Encephalitozoon cuniculi revealed a highly reduced set of proteins in the organelle, mostly related to the assembly of ironsulphur clusters. Oxidative phosphorylation and the Krebs cycle proteins were absent, in keeping with the notion that the microsporidia and their mitosomes are anaerobic, as is the case for other mitosome bearing eukaryotes, such as Giardia. Here we provide evidence opening the possibility that mitosomes in a number of microsporidian lineages are not completely anaerobic. Specifically, we have identified and characterized a gene encoding the alternative oxidase (AOX), a typically mitochondrial terminal oxidase in eukaryotes, in the genomes of several distantly related microsporidian species, even though this gene is absent from the complete genome of E. cuniculi. In order to confirm that these genes encode functional proteins, AOX genes from both A. locustae and T. hominis were over-expressed in E. coli and AOX activity measured spectrophotometrically using ubiquinol-1 (UQ-1) as substrate. Both A. locustae and T. hominis AOX proteins reduced UQ-1 in a cyanide and antimycin-resistant manner that was sensitive to ascofuranone, a potent inhibitor of the trypanosomal AOX. The physiological role of AOX microsporidia may be to reoxidise reducing equivalents produced by glycolysis, in a manner comparable to that observed in trypanosome