42,684 research outputs found
SAMplus: adaptive optics at optical wavelengths for SOAR
Adaptive Optics (AO) is an innovative technique that substantially improves
the optical performance of ground-based telescopes. The SOAR Adaptive Module
(SAM) is a laser-assisted AO instrument, designed to compensate ground-layer
atmospheric turbulence in near-IR and visible wavelengths over a large Field of
View. Here we detail our proposal to upgrade SAM, dubbed SAMplus, that is
focused on enhancing its performance in visible wavelengths and increasing the
instrument reliability. As an illustration, for a seeing of 0.62 arcsec at 500
nm and a typical turbulence profile, current SAM improves the PSF FWHM to 0.40
arcsec, and with the upgrade we expect to deliver images with a FWHM of
arcsec -- up to 0.23 arcsec FWHM PSF under good seeing
conditions. Such capabilities will be fully integrated with the latest SAM
instruments, putting SOAR in an unique position as observatory facility.Comment: To appear in Proc. SPIE 10703 (Ground-based and Airborne
Instrumentation for Astronomy VII; SPIEastro18
Topological Approach to Microcanonical Thermodynamics and Phase Transition of Interacting Classical Spins
We propose a topological approach suitable to establish a connection between
thermodynamics and topology in the microcanonical ensemble. Indeed, we report
on results that point to the possibility of describing {\it interacting
classical spin systems} in the thermodynamic limit, including the occurrence of
a phase transition, using topology arguments only. Our approach relies on Morse
theory, through the determination of the critical points of the potential
energy, which is the proper Morse function. Our main finding is to show that,
in the context of the studied classical models, the Euler characteristic
embeds the necessary features for a correct description of several
magnetic thermodynamic quantities of the systems, such as the magnetization,
correlation function, susceptibility, and critical temperature. Despite the
classical nature of the studied models, such quantities are those that do not
violate the laws of thermodynamics [with the proviso that Van der Waals loop
states are mean field (MF) artifacts]. We also discuss the subtle connection
between our approach using the Euler entropy, defined by the logarithm of the
modulus of per site, and that using the {\it Boltzmann}
microcanonical entropy. Moreover, the results suggest that the loss of
regularity in the Morse function is associated with the occurrence of unstable
and metastable thermodynamic solutions in the MF case. The reliability of our
approach is tested in two exactly soluble systems: the infinite-range and the
short-range models in the presence of a magnetic field. In particular, we
confirm that the topological hypothesis holds for both the infinite-range () and the short-range () models. Further studies are very
desirable in order to clarify the extension of the validity of our proposal
Aplicação de ácido húmico via fertirrigação na produtividade da bananeira BRS Tropical.
Os ácidos húmicos constituem a maior fração da matéria orgânica do solo. A parte mais estável do carbono presente na matéria orgânica do solo e são cruciais no conceito de desenvolvimento sustentável, devido à sua influência na manutenção da qualidade do solo
The CORALIE survey for southern extra-solar planets. X. A Hot Jupiter orbiting HD73256
Recent radial-velocity measurements obtained with the CORALIE spectrograph on
the 1.2-m Euler Swiss telescope at La Silla unveil the presence of a new
Jovian-mass Hot Jupiter around HD 73256. The 1.85-M_Jup planet moves on an
extremely short-period (P=2.5486 d), quasi-circular orbit. The best Keplerian
orbital solution is presented together with an unsuccessful photometric
planetary-transit search performed with the SAT Danish telescope at La Silla.
Over the time span of the observations, the photometric follow-up of the
candidate has nevertheless revealed a P=14-d photometric periodicity
corresponding to the rotational period of the star. This variation as well as
the radial-velocity jitter around the Keplerian solution are shown to be
related to the fair activity level known for HD 73256.Comment: 7 pages, 7 figures. Accepted in A&
The CORALIE survey for southern extrasolar planets. XVI. Discovery of a planetary system around HD 147018 and of two long period and massive planets orbiting HD 171238 and HD 204313
We report the detection of a double planetary system around HD 140718 as well
as the discovery of two long period and massive planets orbiting HD 171238 and
HD 204313. Those discoveries were made with the CORALIE Echelle spectrograph
mounted on the 1.2-m Euler Swiss telescope located at La Silla Observatory,
Chile. The planetary system orbiting the nearby G9 dwarf HD 147018 is composed
of an eccentric inner planet (e=0.47) with twice the mass of Jupiter (2.1 MJup
) and with an orbital period of 44.24 days. The outer planet is even more
massive (6.6 MJup) with a slightly eccentric orbit (e=0.13) and a period of
1008 days. The planet orbiting HD 171238 has a minimum mass of 2.6 MJup, a
period of 1523 days and an eccentricity of 0.40. It orbits a G8 dwarfs at 2.5
AU. The last planet, HD 204313 b, is a 4.0 MJup -planet with a period of 5.3
years and has a low eccentricity (e = 0.13). It orbits a G5 dwarfs at 3.1 AU.
The three parent stars are metal rich, which further strengthened the case that
massive planets tend to form around metal rich stars.Comment: 6 pages, 6 figures, accepted for publication in A&
Data center environment monitoring system
The Internet of things (IoT) is applied to many cases in the smart cities topic. We apply an IoT-developed platform using LoRa communication to a Data Center to understand temperature behavior within a concentration of servers and the working behavior of these server machines. We describe our work as an IoT platform to measure temperature, humidity, and energy consumption in these data centers. In the end, the gradient temperature was found in the rack, and the increasing temperature is correlated with energy consumption and the backup routines in the night. Our developed approach can be used to understand CPU usage and related temperature and the energy consumption.info:eu-repo/semantics/publishedVersio
Inductive learning spatial attention
This paper investigates the automatic induction of spatial attention
from the visual observation of objects manipulated
on a table top. In this work, space is represented in terms of
a novel observer-object relative reference system, named Local
Cardinal System, defined upon the local neighbourhood
of objects on the table. We present results of applying the
proposed methodology on five distinct scenarios involving
the construction of spatial patterns of coloured blocks
Selection of Stylosanthes Guianensis for the Cerrados of Brazil
Progenies of intervarietal hybrid stylos (Stylosanthes guianensis var.vulgaris x S.guianensis var.pauciflora) with mid-season maturity date (early-and mid-June), high dry matter and seed yields have been identified at the National Beef Cattle Research Center (CNPGC), Campo Grande, MS, Brazil. Dry matter yields of the best selections were comparable to those of the late-flowering control, cv. Mineirão. Several mid-season hybrids produced 150 to 200 kg/ha of seed-inpod and a single plant selection yielded in excess of 300 kg/ha. The high degree of resistance to anthracnose observed in the advanced generations is attributed to the immense genetic diversity of these heterogeneous populations which restricted the development of this highly variable pathogen. Stability of disease resistance of superior mid-season maturity types and their adaptation to a wider range of ecological situations have yet to be assessed in multilocational trials. Grazing productivity experiments are required to determine animal production and persistency of the selected materials
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