23 research outputs found
A large topographic feature on the surface of the trans-Neptunian object (307261) 2002 MS measured from stellar occultations
This work aims at constraining the size, shape, and geometric albedo of the
dwarf planet candidate 2002 MS4 through the analysis of nine stellar
occultation events. Using multichord detection, we also studied the object's
topography by analyzing the obtained limb and the residuals between observed
chords and the best-fitted ellipse. We predicted and organized the
observational campaigns of nine stellar occultations by 2002 MS4 between 2019
and 2022, resulting in two single-chord events, four double-chord detections,
and three events with three to up to sixty-one positive chords. Using 13
selected chords from the 8 August 2020 event, we determined the global
elliptical limb of 2002 MS4. The best-fitted ellipse, combined with the
object's rotational information from the literature, constrains the object's
size, shape, and albedo. Additionally, we developed a new method to
characterize topography features on the object's limb. The global limb has a
semi-major axis of 412 10 km, a semi-minor axis of 385 17 km, and
the position angle of the minor axis is 121 16. From
this instantaneous limb, we obtained 2002 MS4's geometric albedo and the
projected area-equivalent diameter. Significant deviations from the fitted
ellipse in the northernmost limb are detected from multiple sites highlighting
three distinct topographic features: one 11 km depth depression followed by a
25 km height elevation next to a crater-like depression with an
extension of 322 39 km and 45.1 1.5 km deep. Our results present an
object that is 138 km smaller in diameter than derived from thermal
data, possibly indicating the presence of a so-far unknown satellite. However,
within the error bars, the geometric albedo in the V-band agrees with the
results published in the literature, even with the radiometric-derived albedo
Prediction and estimation of effective population size
Effective population size (Ne) is a key parameter in population genetics. It has important applications in evolutionary biology, conservation genetics, and plant and animal breeding, because it measures the rates of genetic drift and inbreeding and affects the efficacy of systematic evolutionary forces such as mutation, selection and migration. We review the developments in predictive equations and estimation methodologies of effective size. In the prediction part, we focus on the equations for populations with different modes of reproduction, for populations under selection for unlinked or linked loci, and for the specific applications to conservation genetics. In the estimation part, we focus on methods developed for estimating the current or recent effective size from molecular marker or sequence data. We discuss some underdeveloped areas in predicting and estimating Ne for future research
Inbreeding Effects on Layer Performance at Two Levels of Protein Intake
The growth and laying performance of two strains (6 and 8) after two generations of close inbreeding (44%) were compared with that of their reciprocal crosses ( 6 X 8 and 8X6) under two levels (17% and 13%) of dietary protein and a corresponding 19% reduction in daily protein intake.
Inbreeding effects were large for most traits measured, including body weights, components of egg production, and egg quality.
Reduced dietary protein had adverse effects upon viability, egg mass, age at first egg, and body weight late in the laying period. However, this dietary modification improved egg mass produced per kilogram of protein intake and had no effects upon egg quality.
The tendency for inbreeding depression to be greater under the low (13%) protein diet for viability, sexual maturity, and egg production was too slight for statistical significance. Inbreeding did not change feed or protein conversion response to low protein because inbreds increased their intake of the low protein diet less than the crosses
Effect of selection for part-record number of eggs from housing vs selection for hen-day rate of production from age at first egg
vokKirjasto Aj-
Efecto de la edad, orden de eyaculado y selección por alta producción de huevos en algunos rasgos seminales y morfológicos de gallos leghorns
Se midieron algunos rasgos seminales y morfológicos en gallos de dos líneas control (!líneas 5 y 7), dos líneas seleccionadas por porcentaje de postura, del primer huevo puesto hasta los 273 días de edad (líneas 1 y 9) y dos líneas seleccionadas (líneas