37 research outputs found
The effects of a Variable IMF on the Chemical Evolution of the Galaxy
In this work we explore the effects of adopting an initial mass function
(IMF) variable in time on the chemical evolution of the Galaxy. In order to do
that we adopt a chemical evolution model which assumes two main infall episodes
for the formation of the Galaxy. We study the effects on such a model of
different IMFs. First, we use a theoretical one based on the statistical
description of the density field arising from random motions in the gas. This
IMF is a function of time as it depends on physical conditions of the site of
star formation. We also investigate the behaviour of the model predictions
using other variable IMFs, parameterized as a function of metallicity. Our
results show that the theoretical IMF when applied to our model depends on time
but such time variation is important only in the early phases of the Galactic
evolution, when the IMF is biased towards massive stars. We also show that the
use of an IMF which is a stronger function of time does not lead to a good
agreement with the observational constraints suggesting that if the IMF varied
this variation should have been small. Our main conclusion is that the G-dwarf
metallicity distribution is best explained by infall with a large timescale and
a constant IMF, since it is possible to find variable IMFs of the kind studied
here, reproducing the G-dwarf metallicity but this worsens the agreement with
other observational constraints.Comment: 7 pages, to appear in "The Chemical Evolution of the Milky Way: Stars
vs Clusters", Vulcano, September 1999, F. Giovannelli and F. Matteucci eds.
(Kluwer, Dordrecht) in pres
Emerging country pharmacology: a 10-year perspective from Naunyn-Schmiedebergâs Archives of Pharmacology
Effects of the Addition of Glucose, Sodium Bicarbonate, and Vitamin E to the Drinking Water of Pre-Slaughter Broiler Chickens on Carcass Yield, Gastric Emptying and Meat Quality
Preparation and Anti-Corrosive Properties of Cerium Oxide Conversion Coatings on Steel X52
Clinical, epidemiological and laboratory aspects of patients with American cutaneous leishmaniasis in the State of Pernambuco
Redalyc.Effects of the Addition of Glucose, Sodium Bicarbonate, and Vitamin E to the Drinking Water of Pre-Slaughter Broiler Chickens on Carcass Yield, Gastric Emptying and Meat Quality
Effects of the Addition of Glucose, Sodium Bicarbonate, and Vitamin E to the Drinking Water of Pre-Slaughter Broiler Chickens on Carcass Yield, Gastric Emptying and Meat Quality
ABSTRACT An experiment was conducted of the poultry facilities of La Salle Agricultural College in XanxerĂȘ, SC, Brazil, to evaluate the effect of the administration of sodium bicarbonate, glucose and vitamin E to the drinking water during pre-slaughter feed withdrawal on carcass yield, organ relative weights (heart, liver, proventriculus, and gizzard), gizzard emptying, and meat quality of broiler chickens. The applied treatments were: water as control; 50g/L of glucose; 50g/L de glucose + 200mg/L of vitamin E; 75g/L of glucose; 75g/L + 200mg/L of vitamin E; 0.45% of sodium bicarbonate; 0.45% of sodium bicarbonate + 200mg/L of vitamin E; 0.55% of sodium bicarbonate; 0.55% of sodium bicarbonate + 200mg/L of vitamin E; 200mg/L de vitamin E. On the last day before slaughter, during the water diet period,500 birds were distributed in a completely randomized experimental design with ten treatments and ten replicates of five birds each. No difference in broiler carcass yield and organ relative weights was found. There were no significant changes in gizzard contents, in ultimate meat, cooking loss, shear force value, or in the meat color parameters L* (lightness), a* (redness) and b* (yellowness). It was concluded is that the addition of glucose, sodium bicarbonate, and vitamin E to the drinking water during pre-slaughter feed withdrawal period has no influence on carcass yield or on relative organ weight, neither on the emptying of the gizzard contents and the meat quality of broiler chickens