9,358 research outputs found
Argentina soybean yield model
A model based on multiple regression was developed to estimate soybean yields for the country of Argentina. A meteorological data set was obtained for the country by averaging data for stations within the soybean growing area. Predictor variables for the model were derived from monthly total precipitation and monthly average temperature. A trend variable was included for the years 1969 to 1978 since an increasing trend in yields due to technology was observed between these years
Brazil soybean yield covariance model
A model based on multiple regression was developed to estimate soybean yields for the seven soybean-growing states of Brazil. The meteorological data of these seven states were pooled and the years 1975 to 1980 were used to model since there was no technological trend in the yields during these years. Predictor variables were derived from monthly total precipitation and monthly average temperature
Argentina wheat yield model
Five models based on multiple regression were developed to estimate wheat yields for the five wheat growing provinces of Argentina. Meteorological data sets were obtained for each province by averaging data for stations within each province. Predictor variables for the models were derived from monthly total precipitation, average monthly mean temperature, and average monthly maximum temperature. Buenos Aires was the only province for which a trend variable was included because of increasing trend in yield due to technology from 1950 to 1963
Argentina corn yield model
A model based on multiple regression was developed to estimate corn yields for the country of Argentina. A meteorological data set was obtained for the country by averaging data for stations within the corn-growing area. Predictor variables for the model were derived from monthly total precipitation, average monthly mean temperature, and average monthly maximum temperature. A trend variable was included for the years 1965 to 1980 since an increasing trend in yields due to technology was observed between these years
Brazil wheat yield covariance model
A model based on multiple regression was developed to estimate wheat yields for the wheat growing states of Rio Grande do Sul, Parana, and Santa Catarina in Brazil. The meteorological data of these three states were pooled and the years 1972 to 1979 were used to develop the model since there was no technological trend in the yields during these years. Predictor variables were derived from monthly total precipitation, average monthly mean temperature, and average monthly maximum temperature
Pecuária de corte frente à emissão de gases de efeito estufa e estratégias diretas e indiretas para mitigar a emissão de metano.
Editado por: Mário De Beni Arrigoni, Cyntia Ludovico Martins, Danilo Domingues Millen, Marco Aurélio Factori, André Luis Coneglian Brichi, Alexandre Perdigão
A luminous blue kilonova and an off-axis jet from a compact binary merger at z=0.1341
The recent discovery of a faint gamma-ray burst (GRB) coincident with the
gravitational wave (GW) event GW 170817 revealed the existence of a population
of low-luminosity short duration gamma-ray transients produced by neutron star
mergers in the nearby Universe. These events could be routinely detected by
existing gamma-ray monitors, yet previous observations failed to identify them
without the aid of GW triggers. Here we show that GRB150101B was an analogue of
GRB170817A located at a cosmological distance. GRB 150101B was a faint short
duration GRB characterized by a bright optical counterpart and a long-lived
X-ray afterglow. These properties are unusual for standard short GRBs and are
instead consistent with an explosion viewed off-axis: the optical light is
produced by a luminous kilonova component, while the observed X-rays trace the
GRB afterglow viewed at an angle of ~13 degrees. Our findings suggest that
these properties could be common among future electromagnetic counterparts of
GW sources.Comment: 28 pages, 8 figures, 2 tables. Accepted for publicatio
A year in the life of GW170817: the rise and fall of a structured jet from a binary neutron star merger
We present the results of our year-long afterglow monitoring of GW170817, the
first binary neutron star (NS) merger detected by advanced LIGO and advanced
Virgo. New observations with the Australian Telescope Compact Array (ATCA) and
the Chandra X-ray Telescope were used to constrain its late-time behavior. The
broadband emission, from radio to X-rays, is well-described by a simple
power-law spectrum with index ~0.585 at all epochs. After an initial shallow
rise ~t^0.9, the afterglow displayed a smooth turn-over, reaching a peak X-ray
luminosity of ~5e39 erg/s at 160 d, and has now entered a phase of rapid
decline ~t^(-2). The latest temporal trend challenges most models of choked
jet/cocoon systems, and is instead consistent with the emergence of a
relativistic structured jet seen at an angle of ~22 deg from its axis. Within
such model, the properties of the explosion (such as its blastwave energy
E_K~2E50 erg, jet width theta_c~4 deg, and ambient density n~3E-3 cm^(-3)) fit
well within the range of properties of cosmological short GRBs.Comment: 11 pages, 8 figures, 2 tables, MNRAS, in press. Final version, minor
changes only relative to original submission dated 21 August 201
Particle Propagation on a Circle with a Point Interaction
We study a particle propagation on a circle in the presence of a point
interaction. We show that the one-particle Feynman kernel can be written into
the sum of reflected and transmitted trajectories which are weighted by the
elements of the n-th power of the scattering matrix evaluated on a line with a
point interaction. As a by-product we find three-parameter family of trace
formulae as a generalization of the Poisson summation formula.Comment: 21 pages, 12 figure
A precessing molecular jet signaling an obscured, growing supermassive black hole in NGC1377?
With high resolution (0."25 x 0."18) ALMA CO 3-2 observations of the nearby
(D=21 Mpc, 1"=102 pc), extremely radio-quiet galaxy NGC1377, we have discovered
a high-velocity, very collimated nuclear outflow which we interpret as a
molecular jet with a projected length of +-150 pc. Along the jet axis we find
strong velocity reversals where the projected velocity swings from -150 km/s to
+150 km/s. A simple model of a molecular jet precessing around an axis close to
the plane of the sky can reproduce the observations. The velocity of the
outflowing gas is difficult to constrain due to the velocity reversals but we
estimate it to be between 240 and 850 km/s and the jet to precess with a period
P=0.3-1.1 Myr. The CO emission is clumpy along the jet and the total molecular
mass in the high-velocity (+-(60 to 150 km/s)) gas lies between 2e6 Msun (light
jet) and 2e7 Msun (massive jet). There is also CO emission extending along the
minor axis of NGC1377. It holds >40% of the flux in NGC1377 and may be a
slower, wide-angle molecular outflow which is partially entrained by the
molecular jet.
We discuss the driving mechanism of the molecular jet and suggest that it is
either powered by a very faint radio jet or by an accretion disk-wind similar
to those found towards protostars. The nucleus of NGC1377 harbours intense
embedded activity and we detect emission from vibrationally excited HCN J=4-3
v_2=1f which is consistent with hot gas and dust. We find large columns of H2
in the centre of NGC1377 which may be a sign of a high rate of recent gas
infall. The dynamical age of the molecular jet is short (<1 Myr), which could
imply that it is young and consistent with the notion that NGC1377 is caught in
a transient phase of its evolution. However, further studies are required to
determine the age of the molecular jet, its mass and the role it is playing in
the growth of the nucleus of NGC1377.Comment: This is a revised and expanded version of a previous submission which
now has 13 pages, 6 figures (+ 4 in the Appendix) and is accepted for
publication in Astronomy & Astrophysic
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