Directional nature of Goodman–Kruskal gamma and some consequences: identity of Goodman–Kruskal gamma and Somers delta,and their connection to Jonckheere–Terpstra test statistic

Although usually taken as a symmetric measure, G is shown to be a directional coefficient of association. The direction in G is not related to rows or columns of the cross-table nor the identity of the variables to be a predictor or a criterion variable but, instead, to the number of categories in the scales. Under the conditions where there are no tied pairs in the dataset, G equals Somers’ D so directed that the variable with a wider scale (X) explains the response pattern in the variable with a narrower scale (g), that is, D(g│X). Hence, G = G(g│X) = D(g│X) but G ≠ D(X│g) and G ≠ D(symmetric). If there are tied pairs, the estimates by G = G(g│X) are more liberal in comparison with those by D(g│X). Algebraic relation of G and D with Jonckheere–Terpstra test statistic (JT) is derived. Because of the connection to JT, G = G(g│X) and D = D(g│X) indicate the proportion of logically ordered test-takers in the item after they are ordered by the score. It is strongly recommendable that gamma should not be used as a symmetric measure, and it should be used directionally only when willing to explain the behaviour of a variable with a narrower scale by the variable with a wider scale. This fits well with the measurement modelling settings.

     

A mobile game as a support tool for children with severe difficulties in reading and spelling

We used a randomized controlled trial to investigate if a mobile game, GraphoLearn (GL), could effectively support the learning of first graders (N = 70), who have severe difficulties in reading and spelling. We studied the effects of two versions of the game: GL Reading, which focused on training letter-sound correspondence and word reading; and GL Spelling, which included additional training in phonological skills and spelling. During the spring of first grade, the children trained with tablet computers which they could carry with them during the six-week intervention. The average exposure time to training was 5 hr 44 min. The results revealed no differences in the development of reading or spelling skills between GL players and the control group. However, pre-training self-efficacy moderated the effect among GL Reading players: children with high self-efficacy developed more than the control group in word reading fluency, whereas children with low self-efficacy developed less than the control group in spelling.     

Exploiting fashion x-commerce through the empowerment of voice in the fashion virtual reality arena

Virtual Reality - The ongoing development of eXtended Reality (XR) technologies is supporting a rapid increase of their performances along with a progressive decrease of their costs, making them...     

Triboelectric charging of monodisperse particles in fluidized beds

To investigate the interplay between particle charging and hydrodynamics in fluidized beds, models for triboelectric charging and electrostatic forces were built into a computational fluid dynamics‐discrete element method model. Charge transfer was governed by the difference in effective work function between contacting materials as well as the electric field at the point of contact. Monodisperse particles were fluidized with an effective work function difference between the particles and the conducting walls. For smaller work function differences, hydrodynamics were not changed significantly as compared with an uncharged case. In these simulations, the average charge saturated at a value much lower than the value anticipated based on the work function difference, and a unimodal distribution of charges was observed. For larger work function differences, particles stuck to walls and bed height oscillations due to slugging were less pronounced. For these cases, a bimodal distribution of charges emerged due to effects from strong electric fields. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1872–1891, 2017     

Direct transmission detection of tunable mechanical resonance in an individual carbon nanofiber relay

A direct on-chip transmission measurement of the resonance frequency of an individual singly clamped carbon nanofiber relay is reported. The experimental results are in good agreement with a small signal model and show the expected tuning of the resonance frequency with changing bias voltage.     

Methods of Testing Discrete Semiconductors in the 1149.4 Environment

This paper describes measurement methods for testing discrete semiconductors in the environment defined by the IEEE 1149.4 standard for a mixed-signal bus. First, the paper introduces and illustrates measurement procedures for obtaining such essential electrical parameters of diodes and transistors as can be used for testing and identification. Then, the procedures are carried out and the achieved measurement results presented. To demonstrate the usability of the measurement procedures, the paper then presents test methods and measurement results for discrete component blocks. The results indicate that testing and measuring some of the electrical parameters of discrete semiconductors is possible in the 1149.4 environment. These parameters allow the determination of whether the component under test is working properly or not. Our tests only covered the semiconductors’ DC features, disregarding their AC features. Also discussed are limitations of the 1149.4 environment in discrete semiconductor testing.

Potent inhibitors of the human UDP-glucuronosyltransferase 2B7 derived from the sesquiterpenoid alcohol longifolol

The tricyclic sesquiterpenol (+)-longifolol served as a lead structure for the design of inhibitors of the human UDP-glucuronosyltransferase (UGT) 2B7. Twenty-four homochiral and epimeric longifolol derivatives were synthesized and screened for their ability to inhibit the enzyme. The absolute configuration at the stereogenic center C1' was determined by X-ray crystallography and 2D NMR spectroscopy (gHSQC, gNOESY). The phenyl-substituted secondary alcohol 16 b (beta-phenyllongifolol) displayed the highest affinity toward UGT2B7, and its inhibitory dissociation constant was 0.91 nM. The mode of inhibition was rapidly reversible and competitive. The inhibitor was not glucuronidated by UGT2B7 or other hepatic UGTs, presumably as a result of the high steric demand exerted by the phenyl group. Inhibition assays employing 14 other UGT isoforms suggested that inhibitor 16 b was highly selective for UGT2B7.     

Stereochemical and steric control of the UDP-glucuronosyltransferase-catalyzed conjugation reaction: a rational approach for the design of inhibitors for the human UGT2B7

A set of 76 derivatives of the epimeric tricyclic sesquiterpenols longifolol and isolongifolol was subjected to inhibition and glucuronidation assays employing the human UDP-glucuronosyltransferase (UGT) 2B7. Detailed structure-activity relationships (SARs) with respect to functionality, stereochemical properties, and steric features were derived. To gain further insight into the SARs of UGT2B7 ligands herein, we have developed a 3D-quantitative structure-activity relationship (3D-QSAR) using Comparative Molecular Similarity Analysis (CoMSIA). The formation of the enzyme-inhibitor complex was predominantly controlled by spatially directed hydrophobic interactions. The glucuronidation rate was significantly influenced by the steric demand of substituents in proximity of the nucleophilic hydroxy group. The glucuronidation of the compounds was prevented by the introduction of bulky substituents such as isopropyl, tert-butyl, and phenyl groups. The epimeric longifolol derivatives of series D were the best inhibitors displaying IC(50) values as low as 4.6 nM. This study shows that high-potency substrates can be turned into potent inhibitors by addressing functional, stereochemical, and steric properties.