Output Of Mass Research Articles

Deposition of mass, momentum, and energy by massive stars into the interstellar medium

view Abstract Citations (364) References (107) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Deposition of Mass, Momentum, and Energy by Massive Stars into the Interstellar Medium Leitherer, Claus ; Robert, Carmelle ; Drissen, Laurent Abstract The study presents models for the integrated output of mass, momentum, and energy from a population of massive stars. An extensive grid of radiative wind models is computed for hot stars, and scaling parameters are derived for the mass-loss rates and wind velocities as a function of stellar parameters, including the metal abundance. The mass-loss rate is found to scale with metal abundance like M-dot varies as Z exp 0.8. These wind models are combined with empirical stellar-wind data of other stellar types to obtain predictions for mass-loss rates and wind velocities in the entire upper Hertzprung-Russel diagram. Theoretical and observational uncertainties are discussed. The output of mass, momentum, and energy from stellar winds is computed for typical starburst parameters. It is confirmed that stellar winds and SN explosions can energize superwinds if the kinetic energy of the stellar winds and the SN explosions is efficiently thermalized in the galactic interstellar medium. Publication: The Astrophysical Journal Pub Date: December 1992 DOI: 10.1086/172089 Bibcode: 1992ApJ...401..596L Keywords: Interstellar Matter; Massive Stars; Stellar Mass Ejection; Stellar Models; Stellar Winds; Hertzsprung-Russell Diagram; Hot Stars; Metallicity; Radiative Transfer; Starburst Galaxies; Stellar Evolution; Supernovae; Astrophysics; NUCLEAR REACTIONS; NUCLEOSYNTHESIS; ABUNDANCES; STARS: MASS LOSS; STARS: SUPERNOVAE: GENERAL full text sources ADS | data products SIMBAD (12) MAST (1)

Adrenal cholesterol esters as substrate source for steroidogenesis

Adrenocortical cells obtained from tissues of unstimulated rats and which contained a high concentration of endogenous esterified cholesterol, were labeled in vitro with unesterified [4- 14C]cholesterol, or incubated in the presence of [2- 14C]acetate or lipoprotein [4- 14C]cholesterol oleate (LP-CE). Incubations were conducted in the absence and presence of ACTH, and changes in the specific radioactivity (SA) of the secreted corticosterone were used to assess the primary sources of cholesterol substrate used for steroidogenesis. Incubations of cells containing [4- 14C]cholesterol with ACTH resulted in a marked increase in the output of corticosterone mass, but not of labeled corticosterone. Thus, the SA of corticosterone when cells were incubated with ACTH was only 6.5% of that obtained from cells incubated in the absence of ACTH. During incubations with (2- 14C]acetate, the ACTH-induced increase in the output of corticosterone mass was not associated with increased isotope output, and the SA of corticosterone was only 15% of that in control incubations. This dilution was not altered in cells isolated from adrenals of rats treated with 4-aminopyrazalopyrimidine (4-APP), in which increased cholesterogenesis was demonstrable. The uptake, and hydrolysis of LP-CE, and formation of labeled corticosterone was lipoprotein concentration dependent, and was not influenced by ACTH. However, in the presence of ACTH, the SA of the secreted corticosterone was only 4–8% of that in unstimulated cells. The consistent dilution of the SA of corticosterone in ACTH-treated cells in all studies suggest that the large stores of cytoplasmic cholesterol esters in these cells may normally serve as a primary source of the immediate precursor sterol used for steroidogenesis.

Theoretical productivity of cutting equipment of blasthole-drilling type

1. The theoretical productivity of a system of cutting equipment or a cutting system of the blasthole-drilling type can be expressed in terms of the principal parameters of the basic operational machine: the machine rate of boring and the specific output of rock mass per meter of borehole. 2. Expressions for the theoretical productivity of CC of different schemes allow the influence of the basic parameters of the operational machines to be analyzed and allows their most rational values to the discovered. 3. On the basis of the formulas and calculations presented, nomograms have been plotted for determining the theoretical productivity of the cutting complexes operating in different rock-geological conditions, in integrated and sequential schemes, with various combinations of operational machines.

Multiple linear regression equations for the prediction of food intake in the laying fowl.

Synopsis By means of multiple linear regression analysis, an equation for the prediction of food intake in the laying fowl was derived: where F = daily food intake (g), ΔW= daily live‐weight change (g), W 0.75 = metabolic body size (g) and E= daily egg mass (g) A correction factor for the effect of environmental temperature upon food intake is given, whilst a modification of the intercept value is presented to account for the effect of the dietary energy/body weight interaction upon food intake. It is suggested that equation variation with age, so as to attain maximum accuracy of intake, may only be required in the periods immediately following peak output of egg mass. Individual equations for two strains of hybrid are also presented, and it is concluded that such equations are very narrow in their capability of prediction; not necessarily applying to strains with a similar body weight.

Relation between maximal acid output of stomach and lean body mass.

Relation between maximal acid output of stomach and lean body mass.