A study of the Van Orden star

The purpose of the present study was to determine the variations in the star phoric behavior, using the Van Orden Star and a controlled stimulus to accomodation

A Nutrient-Driven tRNA Modification Alters Translational Fidelity and Genome-wide Protein Coding across an Animal Genus

<div><p>Natural selection favors efficient expression of encoded proteins, but the causes, mechanisms, and fitness consequences of evolved coding changes remain an area of aggressive inquiry. We report a large-scale reversal in the relative translational accuracy of codons across 12 fly species in the <i>Drosophila</i>/<i>Sophophora</i> genus. Because the reversal involves pairs of codons that are read by the same genomically encoded tRNAs, we hypothesize, and show by direct measurement, that a tRNA anticodon modification from guanosine to queuosine has coevolved with these genomic changes. Queuosine modification is present in most organisms but its function remains unclear. Modification levels vary across developmental stages in <i>D. melanogaster</i>, and, consistent with a causal effect, genes maximally expressed at each stage display selection for codons that are most accurate given stage-specific queuosine modification levels. In a kinetic model, the known increased affinity of queuosine-modified tRNA for ribosomes increases the accuracy of cognate codons while reducing the accuracy of near-cognate codons. Levels of queuosine modification in <i>D. melanogaster</i> reflect bioavailability of the precursor queuine, which eukaryotes scavenge from the tRNAs of bacteria and absorb in the gut. These results reveal a strikingly direct mechanism by which recoding of entire genomes results from changes in utilization of a nutrient.</p></div

Ciência, técnica e as expedições da marinha de guerra norteamericana, U.S. Navy, em direção à América Latina (1838-1901) Science, techniques, and U.S. naval expeditions toward Latin America (1838-1901)

Este artigo tem por objetivo mapear as expedições realizadas pela U. S. Navy - a marinha de guerra dos Estados Unidos - em direção à América Latina, no século XIX. Foram realizadas doze viagens no período, mostrando o interesse norte-americano pela região desde a década de 1830.<br>This article focuses on U.S. Navy expeditions set a course from United States to Latin America in nineteenth century. Twelve expeditions as a whole were accomplished in that period, showing the American concern in that region, since 1830 decade

Continuous and discrete latent structure models for item response data

latent structure, latent class, latent trait, item analysis, dichotomous factor analysis, Law School Admission Test (LSAT),