4,475 research outputs found
The 1987 agricultural recovery: a district perspective
Farm income ; Farms - Valuation ; Federal Reserve District, 8th
Farm policy and mandatory supply controls - the case of tobacco
Agricultural price supports ; Tobacco industry
A review of the Eighth District's agricultural economy in 1986
Agriculture ; Farm income ; Agricultural credit ; Federal Reserve District, 8th
A Parallel Tree-SPH code for Galaxy Formation
We describe a new implementation of a parallel Tree-SPH code with the aim to
simulate Galaxy Formation and Evolution. The code has been parallelized using
SHMEM, a Cray proprietary library to handle communications between the 256
processors of the Silicon Graphics T3E massively parallel supercomputer hosted
by the Cineca Supercomputing Center (Bologna, Italy). The code combines the
Smoothed Particle Hydrodynamics (SPH) method to solve hydro-dynamical equations
with the popular Barnes and Hut (1986) tree-code to perform gravity calculation
with a NlogN scaling, and it is based on the scalar Tree-SPH code developed by
Carraro et al(1998)[MNRAS 297, 1021]. Parallelization is achieved distributing
particles along processors according to a work-load criterion. Benchmarks, in
terms of load-balance and scalability, of the code are analyzed and critically
discussed against the adiabatic collapse of an isothermal gas sphere test using
20,000 particles on 8 processors. The code results balanced at more that 95%
level. Increasing the number of processors, the load-balance slightly worsens.
The deviation from perfect scalability at increasing number of processors is
almost negligible up to 32 processors. Finally we present a simulation of the
formation of an X-ray galaxy cluster in a flat cold dark matter cosmology,
using 200,000 particles and 32 processors, and compare our results with Evrard
(1988) P3M-SPH simulations. Additionaly we have incorporated radiative cooling,
star formation, feed-back from SNae of type II and Ia, stellar winds and UV
flux from massive stars, and an algorithm to follow the chemical enrichment of
the inter-stellar medium. Simulations with some of these ingredients are also
presented.Comment: 19 pages, 14 figures, accepted for publication in MNRA
Star formation and chemical evolution in SPH simulations: a statistical approach
In Smoothed Particles Hydrodynamics (SPH) codes with a large number of
particles, star formation as well as gas and metal restitution from dying stars
can be treated statistically. This approach allows to include detailed chemical
evolution and gas re-ejection with minor computational effort. Here we report
on a new statistical algorithm for star formation and chemical evolution,
especially conceived for SPH simulations with large numbers of particles, and
for parallel SPH codes.
For the sake of illustration, we present also two astrophysical simulations
obtained with this algorithm, implemented into the Tree-SPH code by Lia &
Carraro (2000). In the first one, we follow the formation of an individual
disc-like galaxy, predict the final structure and metallicity evolution, and
test resolution effects. In the second one we simulate the formation and
evolution of a cluster of galaxies, to demonstrate the capabilities of the
algorithm in investigating the chemo-dynamical evolution of galaxies and of the
intergalactic medium in a cosmological context.Comment: 17 pages, 20 figures, accepted for publication on MNRA
The dubious success of export subsidies for wheat
Farm produce ; Exports ; Export controls
THE EFFECT OF INTERSTATE BANKING ON FARM LENDER MARKET SHARES IN NEW YORK STATE
Commercial bank loans to New York farmers are significantly overestimated in the reported USDA statistics due to out-of-state lending and reporting of some agribusiness loans as agricultural loans by New York State banks. Correcting for this distortion lowers the 1978-84 average New York agricultural credit market share held by banks from 36 to 24 percent. As deregulation allows more interstate banking activity, the overestimate of agricultural loan volume in states with money center banks and the corresponding underestimate of loan levels and market shares in nonmoney center states could cause increased distortion of state level farm debt statistics.Agricultural Finance,
The cost of checkable deposits in the United States
Checking accounts ; Bank deposits ; Banks and banking - Costs
The status of farm lenders: an assessment of Eighth District and national trends
Agricultural credit ; Agriculture
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