11,917 research outputs found
X-ray powder diffraction of high-absorption materials at the XRD1 beamline off the best conditions: Application to (Gd,Nd)5Si4 compounds
Representative compounds of the new family of magnetic materials Gd5-xNdxSi4
were analyzed by X-ray diffraction at the XRD1 beamline at LNLS. To reduce
X-ray absorption, thin layers of the powder samples were mounted outside the
capillaries and measured in Debye-Scherrer geometry as usual. The X-ray
diffraction analyses and the magnetometry results indicate that the behavior of
the magnetic transition temperature as a function of Nd content may be directly
related to the average of the four smallest interatomic distances between
different rare earth sites of the majority phase of each compound. The quality
and consistency of the results show that the XRD1 beamline is able to perform
satisfactory X-ray diffraction experiments on high-absorption materials even
off the best conditions.Comment: 12 pages, 3 figures, 3 table
Pressure induced magnetic and magnetocaloric properties in NiCoMnSb Heusler alloy
The effect of pressure on the magnetic and the magnetocaloric properties
around the martensitic transformation temperature in NiCoMnSb Heusler alloy has
been studied. The martensitic transition temperature has significantly shifted
to higher temperatures with pressure, whereas the trend is opposite with the
application of applied magnetic field. The maximum magnetic entropy change
around the martensitic transition temperature for Ni45Co5Mn38Sb12 is 41.4 J/kg
K at the ambient pressure, whereas it is 33 J/kg K at 8.5 kbar. We find that by
adjusting the Co concentration and applying suitable pressure, NiCoMnSb system
can be tuned to achieve giant magnetocaloric effect spread over a large
temperature span around the room temperature, thereby making it a potential
magnetic refrigerant material for applications.Comment: 16 pages, 5 figure
Abundance patterns in early-type galaxies: is there a 'knee' in the [Fe/H] vs. [alpha/Fe] relation?
Early-type galaxies (ETGs) are known to be enhanced in alpha elements, in
accordance with their old ages and short formation timescales. In this
contribution we aim to resolve the enrichment histories of ETGs. This means we
study the abundance of Fe ([Fe/H]) and the alpha-element groups ([alpha/Fe])
separately for stars older than 9.5 Gyr ([Fe/H]o, [alpha/Fe]o) and for stars
between 1.5 and 9.5 Gyr ([Fe/H]i, [alpha/Fe]i). Through extensive simulation we
show that we can indeed recover the enrichment history per galaxy. We then
analyze a spectroscopic sample of 2286 early-type galaxies from the SDSS
selected to be ETGs. We separate out those galaxies for which the abundance of
iron in stars grows throughout the lifetime of the galaxy, i.e. in which
[Fe/H]o < [Fe/H]i. We confirm earlier work where the [Fe/H] and [alpha/Fe]
parameters are correlated with the mass and velocity dispersion of ETGs. We
emphasize that the strongest relation is between [alpha/Fe] and age. This
relation falls into two regimes, one with a steep slope for old galaxies and
one with a shallow slope for younger ETGs. The vast majority of ETGs in our
sample do not show the 'knee' in the plot of [Fe/H] vs. [alpha/Fe] commonly
observed in local group galaxies. This implies that for the vast majority of
ETGs, the stars younger than 9.5 Gyrs are likely to have been accreted or
formed from accreted gas. The properties of the intermediate-age stars in
accretion-dominated ETGs indicate that mass growth through late (minor) mergers
in ETGs is dominated by galaxies with low [Fe/H] and low [alpha/Fe]. The method
of reconstructing the stellar enrichment histories of ETGs introduced in this
paper promises to constrain the star formation and mass assembly histories of
large samples of galaxies in a unique way.Comment: 22 pages, 25 figures, accepted for publication by A&
Catches in ghost-fishing octopus and fish traps in the northeastern Atlantic Ocean (Algarve, Portugal)
Ghost fishing is the term used to describe the continued capture of fish and other living organisms after a
fisherman has lost all control over the gear. Traps may be lost for a variety of reasons including theft, vandalism,
abandonment, interactions with other gear, fouling on the bottom (i.e., traps and ropes are caught on rocky substrate), bad weather, and human error (Laist, 1995). Annual trap loss can be as high as 20% to 50% of fished traps in some fisheries (Al-Masroori et al., 2004). Because lost traps can continue to fish for long periods, albeit
with decreasing efficiency over time (e.g., Smolowitz, 1978; Breen, 1987, 1990; Guillory, 1993), ghost fishing is
a concern in fisheries worldwide
Espacialização de indicadores socioeconômicos como subsídio ao macrozoneamento ecológico-econômico do Estado do Maranhão.
Macrozoneamentos ecológico-econômicos foram instituídos pelo governo federal e têm como finalidade identificar potencialidades e limitações de recursos naturais e da sociedade com base em um diagnóstico socioambiental e com o propósito de apoiar a formulação e execução de políticas de desenvolvimento regional . Indicadores socioeconômicos são instrumentos importantes em todas as fases do processo de formulação, implementação, monitoramento e avaliação das políticas públicas, e são elementos indispensáveis para a elaboração de macrozoneamentos ecológico-econômicos . O objetivo deste trabalho foi espacializar indicadores socioeconômicos que serão utilizados como subsídio para a elaboração do Macrozoneamento Ecológico-Econômico do Estado do Maranhão. Foram adotados, como unidade de referência territorial, os 217 municípios que compõem o estado e, como fonte de dados, a Produção Agrícola Municipal (PAM) do IBGE e o Censo Demográfico do IBGE. Foram selecionados os principais indicadores socioeconômicos, como saneamento básico, energia, água potável, saúde, educação, entre outros. O procedimento metodológico utilizado foi: definição e levantamento dos indicadores; criação e formatação das tabelas com auxílio do programa Excel; e, por fim, a utilização do software ArcGIS (ESRI), que, por meio das planilhas criadas, dos geocódigos municipais e dos shapefile disponibilizados pelo IBGE, possibilitou espacializar os dados e, assim, gerar os mapas temáticos. A espacialização dos indicadores pode contribuir para a formulação de políticas públicas em diferentes níveis de governo e, assim, para que sejam tomadas decisões mais adequadas
Produtividade de Panicum maximum jacq., linhagem k 187b e cultivar Coloniao sob pastejo.
bitstream/item/137572/1/PESQ-EM-ANDAMENTO-29.pdfCNPGC
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