1,086 research outputs found
Influence of drainage status on soil and water chemistry, litter decomposition and soil respiration in central Amazonian forests on sandy soils
Central Amazonian rainforest landscape supports a mosaic of tall terra firme rainforest and ecotone campinarana, riparian and campina forests, reflecting topography-induced variations in soil, nutrient and drainage conditions. Spatial and temporal variations in litter decomposition, soil and groundwater chemistry and soil CO2 respiration were studied in forests on sandy soils, whereas drought sensitivity of poorly-drained valley soils was investigated in an artificial drainage experiment. Slightly changes in litter decomposition or water chemistry were observed as a consequence of artificial drainage. Riparian plots did experience higher litter decomposition rates than campina forest. In response to a permanent lowering of the groundwater level from 0.1 m to 0.3 m depth in the drainage plot, topsoil carbon and nitrogen contents decreased substantially. Soil CO2 respiration decreased from 3.7±0.6 ”mol m-2 s-1 before drainage to 2.5±0.2 and 0.8±0.1 ”mol m-2 s-1 eight and 11 months after drainage, respectively. Soil respiration in the control plot remained constant at 3.7±0.6 ”mol m-2 s-1. The above suggests that more frequent droughts may affect topsoil carbon and nitrogen content and soil respiration rates in the riparian ecosystem, and may induce a transition to less diverse campinarana or short-statured campina forest that covers areas with strongly-leached sandy soil
Development of Multifunctional Materials and Structures with Improved Capacities in Aerodynamics, De-icing, Acoustics or Electromagnetism for Civil and Military Aircrafts
For several years, either in the frame of research projects (French, European), or for direct
application on aircraft programs, Dassault Aviation has developed multifunctional materials
and structures (MMS) with specific benefits in aerodynamics, de-icing, acoustic or
electromagnetisms. The main challenge is to get the best compromise between the high
functional performances desired and the mechanical and aeronautic environment resistance
needed for the application. This presentation will review some examples of development
performed in the recent years for aircraft aerodynamics improvement, icing protection,
acoustics and new antenna radomes
Trophic Status of the Bandar Kayangan Lembah Sari Reservoir, Rumbai Pesisir Sub-district, Pekanbaru Based on Nitrate and Phosphate Concentration
As a basis to determine the trophic status of the waters. A research aims tounderstand the trophic status of the waters of the Bandar Kayangan Lembah Sarireservoir was conducted in Mach-April 2016.There were 4 stations, namely St 1 (in theinlet from Ambang River), St 2 (in the inlet from Merbau River), St3 (in the middle ofthe lake) and St 4 (in the dam). Samplings were conducted 3 times, once/ week. Watersamples were taken from the water surface.Results shown that nitrate concentration was ranged from 0.075 â 0.096 mg/L,phosphate from 0.208 â 0.293 mg/L, temperature 31-32°C, transparency 56.8 â 60.2 cm,depth 219.3 â 378.7 cm, velocity0.25 â 0.40 cm/s, pH was4, dissolved oxygen (DO)5.38 â 8.31mg/L. Based on nitrate concentration, the trophic status of the BandarKayangan Lembah Sari reservoir was categorized as oligotrophic, whereas based onphosphate concentration, it can be categorized as eutrophic
Adaptive-Attentive Geolocalization From Few Queries: A Hybrid Approach
We tackle the task of cross-domain visual geo-localization, where the goal is to geo-localize a given query image against a database of geo-tagged images, in the case where the query and the database belong to different visual domains. In particular, at training time, we consider having access to only few unlabeled queries from the target domain. To adapt our deep neural network to the database distribution, we rely on a 2-fold domain adaptation technique, based on a hybrid generative-discriminative approach. To further enhance the architecture, and to ensure robustness across domains, we employ a novel attention layer that can easily be plugged into existing architectures. Through a large number of experiments, we show that this adaptive-attentive approach makes the model robust to large domain shifts, such as unseen cities or weather conditions. Finally, we propose a new large-scale dataset for cross-domain visual geo-localization, called SVOX
Ionization history of the cosmic plasma in the light of the recent CBI and future PLANCK data
The paper is devoted to the methods of determination of the cosmological
parameters from recent CMB observations. We show that the more complex models
of kinetics of recombination with a few "missing" parameters describing the
recombination process provide better agreement between measured and expected
characteristics of the CMB anisotropy. In particular, we consider the external
sources of the Ly-{alpha} and Ly-{c} radiation and the model with the strong
clustering of baryonic component. These factors can constrain the estimates of
the cosmological parameters usually discussed. We demonstrate also that the
measurements of polarization can improve these estimates and, for the precision
expected for the PLANCK mission, allow to discriminate a wide class of models.Comment: 25 pages, 7 figures, extended and corrected after the referee report.
Accepted in Ap
Exploring the parent population of beamed NLS1s: from the black hole to the jet
The aim of this work is to understand the nature of the parent population of
beamed narrow-line Seyfert 1 galaxies (NLS1s), by studying the physical
properties of three parent candidates samples: steep-spectrum radio-loud NLS1s,
radio-quiet NLS1s and disk-hosted radio-galaxies. In particular, we focused on
the black hole mass and Eddington ratio distribution and on the interactions
between the jet and the narrow-line region.Comment: 6 pages, 2 figures, to appear in Proceedings of High Energy Phenomena
in Relativistic Outflows (HEPRO) V, Workshop Series of the Argentinian
Astronomical Societ
Unveiling the parent population of beamed narrow-line Seyfert 1s
Narrow-line Seyfert 1 galaxies (NLS1s) are active galactic nuclei (AGN)
recently identified as a new class of -ray sources. The high energy
emission is explained by the presence of a relativistic jet observed at small
angles, just like in the case of blazars. When the latter are observed at
larger angles they appear as radio-galaxies, but an analogue parent population
for beamed NLS1s has not yet been determined. In this work we analyze this
problem by studying the physical properties of three different samples of
parent sources candidates: steep-spectrum radio-loud NLS1s, radio-quiet NLS1s,
and disk-hosted radio-galaxies, along with compact steep-spectrum sources. In
our approach, we first derived black hole mass and Eddington ratio from the
optical spectra, then we investigated the interaction between the jet and the
narrow-line region from the [O III] 4959,5007 lines. Finally,
the radio luminosity function allowed us to compare their jet luminosity and
hence determine the relations between the samples.Comment: 6 pages, no figures. Proceedings of the 28th Texas Symposium, Geneva,
December 13-18, 201
Cana-de-açĂșcar cultivada em solo adubado com lodo de esgoto: nutrientes, metais pesados e produtividade.
A pesquisa objetivou avaliar o uso de lodo de esgoto (Le) na adubação de soqueira (2o corte) de cana-de-açĂșcar (Saccharum spp., var. RB72-454). Aplicou-se Le ao solo, localizando-o no fundo de um sulco com 15 cm de profundidade e distando 40 cm da linha de cana. Avaliaram-se os efeitos das doses do Le (0, 15 e 30 t.ha-1) nas produtividades de biomassa e de açĂșcar, nos teores de nutrientes e de metais pesados do solo e da planta. O Le diminuiu a acidez potencial (H + Al) do solo e forneceu nutrientes para a cana-de-açĂșcar, principalmente P, S, Ca, Cu e Zn, o que refletiu em aumentos de produtividades de colmos e de açĂșcar por hectare. O Le causou aumentos de exportaçÔes de P, S, Ca, Cu, K, Mg e Ni pela parte aĂ©rea da cana-de-açĂșcar; tais aumentos, por sua vez, foram motivados pelos aumentos dos teores destes elementos no tecido vegetal, e da produtividade em biomassa. Os metais pesados (Cd, Cr, Ni e Pb), contidos no Le, nĂŁo apresentaram perigo Ă cadeia trĂłfica Ă curto prazo
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