1,500 research outputs found
Near-infrared spatially resolved spectroscopy of (136108) Haumea's multiple system
The transneptunian region of the solar system is populated by a wide variety
of icy bodies showing great diversity. The dwarf planet (136108) Haumea is
among the largest TNOs and displays a highly elongated shape and hosts two
moons, covered with crystalline water ice like Hamuea. Haumea is also the
largest member of the sole TNO family known to date. A catastrophic collision
is likely responsible for its unique characteristics. We report here on the
analysis of a new set of observations of Haumea obtained with SINFONI at the
ESO VLT. Combined with previous data, and using light-curve measurements in the
optical and far infrared, we carry out a rotationally resolved spectroscopic
study of the surface of Haumea. We describe the physical characteristics of the
crystalline water ice present on the surface of Haumea for both regions, in and
out of the Dark Red Spot (DRS), and analyze the differences obtained for each
individual spectrum. The presence of crystalline water ice is confirmed over
more than half of the surface of Haumea. Our measurements of the average
spectral slope confirm the redder characteristic of the spot region. Detailed
analysis of the crystalline water-ice absorption bands do not show significant
differences between the DRS and the remaining part of the surface. We also
present the results of applying Hapke modeling to our data set. The best
spectral fit is obtained with a mixture of crystalline water ice (grain sizes
smaller than 60 micron) with a few percent of amorphous carbon. Improvements to
the fit are obtained by adding ~10% of amorphous water ice. Additionally, we
used the IFU-reconstructed images to measure the relative astrometric position
of the largest satellite Hi`iaka and determine its orbital elements. An orbital
solution was computed with our genetic-based algorithm GENOID and our results
are in full agreement with recent results.Comment: Accepted for publication in A&
Non-Fermi Liquid behavior in CeIrIn near a metamagnetic transition
We present specific heat and resistivity study of CeIrIn5 in magnetic fields
up to 17 T and temperature down to 50 mK. Both quantities were measured with
the magnetic field parallel to the c-axis (H || [001]) and within the a-b plane
(H \perp [001]). Non-Fermi-liquid (NFL) behavior develops above 12 T for H ||
[001]. The Fermi liquid state is much more robust for H \perp [001] and is
suppressed only moderately at the highest applied field. Based on the observed
trends and the proximity to a metamagnetic phase transition, which exists at
fields above 25 T for H || [001], we suggest that the observed NFL behavior in
CeIrIn5 is a consequence of a metamagnetic quantum critical point.Comment: 5 pages, 4 figures, submitted to Phys. Rev. Letter
Upland rice under tillage as affected by early fertilization of nitrogen.
The objective was to determine the effect of timing of nitrogen application on plant height and lodging, yield components, grain yield and industrial quality of rice grains
Resistência a inseticidas piretróides em populações de Sitophilus zeamais (Coleoptera: curculionidae) coletadas em unidades armazenadoras de arroz no Estado do Tocantins.
O Estado do Tocantins tem um grande potencial agrícola, com extensas áreas propícias à prática da agricultura e, vem se destacando no cenário nacional como grande produtor de grãos, principalmente arroz, segunda cultura em área plantada, encontrando-se já instalados grandes complexos de armazenagem e beneficiamento. Nas unidades armazenadoras tocantinenses o uso de inseticidas para o controle preventivo ou curativo de insetos-praga é uma prática comum, o que levanta a suspeita das populações já terem desenvolvido resistência aos inseticidas usados em seu controle. Nesse contexto, informações sobre resistência a inseticidas para esta espécie são necessárias e úteis para implementação de programas de manejo de resistência a inseticidas
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