1,638 research outputs found
Custo de produção de leitões em diferentes sistemas de produção: um estudo de caso no Oeste catarinense.
Este texto é o relato do estudo de caso de um estabelecimento suinícola no município de Presidente Castello Branco na região Oeste Catarinense. O objetivo foi estimar o custo de produção de leitões no atual cenário, no qual 33% do consumo de milho são produzidos no estabelecimento e, também, em dois cenários alternativos, um com autossuficiência em milho e o outro especializado em suínos. O estudo de caso utiliza uma abordagem sistêmica do estabelecimento agropecuário. As fontes foram entrevistas, software de gestão e preços fornecidos por órgãos públicos. O custo de produção foi calculado com planilha eletrônica desenvolvida pela rede Interpig. Os três diferentes cenários determinaram diferentes preços do milho, principal componente no custo de suínos. No sistema atual o custo de produção foi de R94,97 por leitão e, por fim, R88,22 per piglet, while on the specialized system it was R77,90 per piglet on the self-sufficient system, which presented the lowest cost
Baroclinic Vorticity Production in Protoplanetary Disks; Part I: Vortex Formation
The formation of vortices in protoplanetary disks is explored via
pseudo-spectral numerical simulations of an anelastic-gas model. This model is
a coupled set of equations for vorticity and temperature in two dimensions
which includes baroclinic vorticity production and radiative cooling. Vortex
formation is unambiguously shown to be caused by baroclinicity because (1)
these simulations have zero initial perturbation vorticity and a nonzero
initial temperature distribution; and (2) turning off the baroclinic term halts
vortex formation, as shown by an immediate drop in kinetic energy and
vorticity. Vortex strength increases with: larger background temperature
gradients; warmer background temperatures; larger initial temperature
perturbations; higher Reynolds number; and higher resolution. In the
simulations presented here vortices form when the background temperatures are
and vary radially as , the initial vorticity
perturbations are zero, the initial temperature perturbations are 5% of the
background, and the Reynolds number is . A sensitivity study consisting
of 74 simulations showed that as resolution and Reynolds number increase,
vortices can form with smaller initial temperature perturbations, lower
background temperatures, and smaller background temperature gradients. For the
parameter ranges of these simulations, the disk is shown to be convectively
stable by the Solberg-H{\o}iland criteria.Comment: Originally submitted to The Astrophysical Journal April 3, 2006;
resubmitted November 3, 2006; accepted Dec 5, 200
Potencial produtivo do milho em resposta ao uso de dejetos suínos e adubação química.
Projeto/Plano de Ação: 05.12.50200-03
Optimal control of time-dependent targets
In this work, we investigate how and to which extent a quantum system can be
driven along a prescribed path in Hilbert space by a suitably shaped laser
pulse. To calculate the optimal, i.e., the variationally best pulse, a properly
defined functional is maximized. This leads to a monotonically convergent
algorithm which is computationally not more expensive than the standard
optimal-control techniques to push a system, without specifying the path, from
a given initial to a given final state. The method is successfully applied to
drive the time-dependent density along a given trajectory in real space and to
control the time-dependent occupation numbers of a two-level system and of a
one-dimensional model for the hydrogen atom.Comment: less typo
Libpsht - algorithms for efficient spherical harmonic transforms
Libpsht (or "library for Performant Spherical Harmonic Transforms") is a
collection of algorithms for efficient conversion between spatial-domain and
spectral-domain representations of data defined on the sphere. The package
supports transforms of scalars as well as spin-1 and spin-2 quantities, and can
be used for a wide range of pixelisations (including HEALPix, GLESP and ECP).
It will take advantage of hardware features like multiple processor cores and
floating-point vector operations, if available. Even without this additional
acceleration, the employed algorithms are among the most efficient (in terms of
CPU time as well as memory consumption) currently being used in the
astronomical community.
The library is written in strictly standard-conforming C90, ensuring
portability to many different hard- and software platforms, and allowing
straightforward integration with codes written in various programming languages
like C, C++, Fortran, Python etc.
Libpsht is distributed under the terms of the GNU General Public License
(GPL) version 2 and can be downloaded from
http://sourceforge.net/projects/libpsht.Comment: 9 pages, 8 figures, accepted by A&
Numerical analysis of energy recovery system for turbocharged internal combustion engines via a parallel compounding turbine
Increasing energy efficiency requirements mandatory ask for optimizing energy utilization in many devices, which include internal combustion engines. One of the most investigated subjects is the energy recovery from the exhaust, such as turbo-compound systems, which usually consist in a secondary turbine located afterward the turbocharger. Here an alternative arrangement is proposed and analysed via a numerical model. The recovery turbine works in parallel to the main turbine and uses the gasses which would be otherwise wasted through the waste-gate valve, once the set-point boost pressure is reached. The reference case analysed is a 12.4L turbocharged diesel engine, commonly used in marine, road and light railroad applications, with a nominal power of 380kW. The results showed that an overall 8% of power can be gained, without nor increasing the fuel mass flow rate, neither requiring significant modifications to the baseline engine. Moreover, in the case of the recovery system failure, the operation of the engine is not affected, thus resulting in no engine availability reduction. This work also shows a feasible way to convert the mechanical energy delivered by the recovery turbine into electrical energy, by making use of a high-speed electrical generator
Intracellular calcium changes induced by the endozepine triakontatetraneuropeptide in human polymorphonuclear leukocytes: role of protein kinase C and effect of calcium channel blockers
BACKGROUND: The endozepine triakontatetraneuropeptide (TTN) induces intracellular calcium ([Ca(++)](i)) changes followed by activation in human polymorphonuclear leukocytes (PMNs). The present study was undertaken to investigate the role of protein kinase (PK) C in the modulation of the response to TTN by human PMNs, and to examine the pharmacology of TTN-induced Ca(++ )entry through the plasma membrane of these cells. RESULTS: The PKC activator 12-O-tetradecanoylphorbol-13-acetate (PMA) concentration-dependently inhibited TTN-induced [Ca(++)](i )rise, and this effect was reverted by the PKC inhibitors rottlerin (partially) and Ro 32-0432 (completely). PMA also inhibited TTN-induced IL-8 mRNA expression. In the absence of PMA, however, rottlerin (but not Ro 32-0432) per se partially inhibited TTN-induced [Ca(++)](i )rise. The response of [Ca(++)](i )to TTN was also sensitive to mibefradil and flunarizine (T-type Ca(++)-channel blockers), but not to nifedipine, verapamil (L-type) or ω-conotoxin GVIA (N-type). In agreement with this observation, PCR analysis showed the expression in human PMNs of the mRNA for all the α1 subunits of T-type Ca(++ )channels (namely, α1G, α1H, and α1I). CONCLUSIONS: In human PMNs TTN activates PKC-modulated pathways leading to Ca(++ )entry possibly through T-type Ca(++ )channels
Snow metamorphism: a fractal approach
Snow is a porous disordered medium consisting of air and three water phases:
ice, vapour and liquid. The ice phase consists of an assemblage of grains, ice
matrix, initially arranged over a random load bearing skeleton. The
quantitative relationship between density and morphological characteristics of
different snow microstructures is still an open issue. In this work, a
three-dimensional fractal description of density corresponding to different
snow microstructure is put forward. First, snow density is simulated in terms
of a generalized Menger sponge model. Then, a fully three-dimensional compact
stochastic fractal model is adopted. The latter approach yields a quantitative
map of the randomness of the snow texture, which is described as a
three-dimensional fractional Brownian field with the Hurst exponent H varying
as continuous parameter. The Hurst exponent is found to be strongly dependent
on snow morphology and density. The approach might be applied to all those
cases where the morphological evolution of snow cover or ice sheets should be
conveniently described at a quantitative level
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