Modeling L- and X-band backscattering of wheat and tests over fields of Pampas

A discrete scattering model and a detailed set of ground measurements are used to simulate the backscattering coefficients of wheat fields during the whole growth cycle. Simulations are carried out at L- and X-band, and at HH, VV, and HV polarizations. Wheat fields are located in Pampas (Argentina), and are characterized by low values of plant density. Simulations show that the backscattering coefficient is driven by variations of soil moisture at L-band, particularly for HH polarization, with low vegetation effects. Conversely, the attenuation of vegetation is dominant in producing variations of backscattering coefficients at X-band, particularly for VV polarization. Simulations are compared against experimental data collected over the same Pampas region, using airborne SARAT SAR at L-band and COSMO-SKYMED at X-band. Assuming a surface height standard deviation in a 0.4–0.7 cm range, the simulations generally agree with experimental data, with an RMSE lower than about 2 dB at L-band and X-band, except a limited number of cases. Discrepancies observed in specific conditions are discussed. Overall, the results indicate that a joint use of L- and X-band has a good potential to monitor both soil moisture and vegetation growth

Herbage Production, Nitrogen Fixation and Condensed Tannin Concentrations in \u3cem\u3eLotus glaber\u3c/em\u3e Mill. Germplasm

Lotus glaber (Lg) grows on clay, sandy and medium textured soils in central Chile (32º to 38º S). The diversity of environments where the species grows naturally supports the hypothesis that genetic variability would be found. The objectives of the experiment were to characterise accessions of Lg collected in the region for dry matter (DM) production, comparative capacity to fix atmospheric N and condensed tannins (CT) in Lg grown on clay soils used for cropping rice

Genetic Variability Between Adapted Populations of Annual Ryegrass (\u3cem\u3eLolium Multiflorum\u3c/em\u3e Lam) In Argentina

Italian ryegrass (Lolium multiflorum Lam.) is one of the most important annual grasses used in Argentina because it adapts better to the intensive animal system of the Humid Pampas than other annual forage grass. Although much research has been done to study its productive potential and management technologies, little work has focused on breeding and selection. There is ample evidence that genetic variability occurs within grass species (Snaydon, 1987; Andrés and Barufaldi, 1997) both in morphology and physiology. As a result the variation of attributes related with yield potential, quality and adaptation to different management systems, is often used in plant breeding to develop new varieties. The objective of this work was to evaluate the genetic variability between 32 populations of annual ryegrass adapted to different grassland environments in the Humid Pampas Region of Argentina as an introductory part of a breeding programme at INTA. The final aim of this programme is to provide new varieties of annual ryegrass adapted to different management systems

Twenty years monitoring growth dynamics of a logged tropical forest in Western Amazon.

Resumo - Foi conduzido um estudo sobre a dinâmica de crescimento em floresta localizada no Estado do Acre na Amazônia sul ocidental, onde uma área de 20 ha foi explorada para extração de madeira em 1992. O estudo foi baseado em parcelas permanentes (1 ha) estabelecidas dentro da área explorada e na floresta não manejada, imediatamente após o fim das operações florestais. Os parâmetros da dinâmica florestal foram analisados em termos da biomassa seca acima do solo (BAS). Durante o período do estudo três eventos climáticos extremos causaram um elevado impacto tanto nas áreas exploradas como nas não perturbadas por exploração, produzindo perdas de biomassa superiores às estimadas para a exploração. Vinte anos após a exploração, as taxas de ingresso e mortalidade foram semelhantes às esperadas em uma área de floresta não perturbada por exploração e a recuperação da BAS foi significativamente mais alta nas áreas cortadas. Quando praticado de forma adequada, o manejo de floresta pode promover uma recuperação da BAS mais rápida. Nós sugerimos que o manejo florestal pode ser considerado como uma alternativa para adaptação a eventos extremos de clima por meio da promoção de perturbações controladas que minimizem a mortalidade de árvores e a perda de biomassa

El agronegocio del cultivo de tartago em el mundo.

bitstream/CNPA/18351/1/CIRTEC101.pd

Overview of Phosphorus Effect in Molybdenum-Based Hydrotreating Catalysts Supported on Ordered Mesoporous Siliceous Materials

This chapter presents an overview of the literature on the effect of phosphorus modification of ordered mesoporous silica (OMS) such as MCM-41, HMS, SBA-15, and SBA-16 to be used as supports for hydrotreating catalysts based on transition metal sulfides (TMS). The influence of the support modification with variable quantities of phosphorus on the performance for hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) reactions is outlined and discussed considering the changes in the structural and textural properties (SBET), acidity, reducibility, etc., of the substrate brought about by phosphorus incorporation

Characterization of the HD 108236 system with CHEOPS and TESS Confirmation of a fifth transiting planet

Context. The HD 108236 system was first announced with the detection of four small planets based on TESS data. Shortly after, the transit of an additional planet with a period of 29.54 d was serendipitously detected by CHEOPS. In this way, HD 108236 (V = 9.2) became one of the brightest stars known to host five small transiting planets (Rp < 3 R⊕). Aims. We characterize the planetary system by using all the data available from CHEOPS and TESS space missions. We use the flexible pointing capabilities of CHEOPS to follow up the transits of all the planets in the system, including the fifth transiting body. Methods. After updating the host star parameters by using the results from Gaia eDR3, we analyzed 16 and 43 transits observed by CHEOPS and TESS, respectively, to derive the planets’ physical and orbital parameters. We carried out a timing analysis of the transits of each of the planets of HD 108236 to search for the presence of transit timing variations. Results. We derived improved values for the radius and mass of the host star (R★ = 0.876 ± 0.007 R0 and M★ = 0.867-0.046+0.047M⊙). We confirm the presence of the fifth transiting planet f in a 29.54 d orbit. Thus, the HD 108236 system consists of five planets of Rb = 1.587±0.028, Rc = 2.122±0.025, Rd = 2.629 ± 0.031, Re = 3.008 ± 0.032, and Rf = 1.89 ± 0.04 [R⊕]. We refine the transit ephemeris for each planet and find no significant transit timing variations for planets c, d, and e. For planets b and f, instead, we measure significant deviations on their transit times (up to 22 and 28 min, respectively) with a non-negligible dispersion of 9.6 and 12.6 min in their time residuals. Conclusions. We confirm the presence of planet f and find no significant evidence for a potential transiting planet in a 10.9 d orbital period, as previously suggested. Further monitoring of the transits, particularly for planets b and f, would confirm the presence of the observed transit time variations. HD 108236 thus becomes a key multi-planetary system for the study of formation and evolution processes. The reported precise results on the planetary radii – together with a profuse RV monitoring – will allow for an accurate characterization of the internal structure of these planets

Decomposing virulence to understand bacterial clearance in persistent infections

Following an infection, hosts cannot always clear the pathogen, instead either dying or surviving with a persistent infection. Such variation is ecologically and evolutionarily important because it can affect infection prevalence and transmission, and virulence evolution. However, the factors causing variation in infection outcomes, and the relationship between clearance and virulence are not well understood. Here we show that sustained persistent infection and clearance are both possible outcomes across bacterial species showing a range of virulence in Drosophila melanogaster. Variation in virulence arises because of differences in the two components of virulence: bacterial infection intensity inside the host (exploitation), and the amount of damage caused per bacterium (per parasite pathogenicity). As early-phase exploitation increased, clearance rates later in the infection decreased, whereas there was no apparent effect of per parasite pathogenicity on clearance rates. Variation in infection outcomes is thereby determined by how virulence – and its components – relate to the rate of pathogen clearance. Taken together we demonstrate that the virulence decomposition framework is broadly applicable and can provide valuable insights into host-pathogen interactions

A Comprehensive View of the 2006 December 13 CME: From the Sun to Interplanetary Space

The biggest halo coronal mass ejection (CME) since the Halloween storm in 2003, which occurred on 2006 December 13, is studied in terms of its solar source and heliospheric consequences. The CME is accompanied by an X3.4 flare, EUV dimmings and coronal waves. It generated significant space weather effects such as an interplanetary shock, radio bursts, major solar energetic particle (SEP) events, and a magnetic cloud (MC) detected by a fleet of spacecraft including STEREO, ACE, Wind and Ulysses. Reconstruction of the MC with the Grad-Shafranov (GS) method yields an axis orientation oblique to the flare ribbons. Observations of the SEP intensities and anisotropies show that the particles can be trapped, deflected and reaccelerated by the large-scale transient structures. The CME-driven shock is observed at both the Earth and Ulysses when they are separated by 74$^{\circ}$ in latitude and 117$^{\circ}$ in longitude, the largest shock extent ever detected. The ejecta seems missed at Ulysses. The shock arrival time at Ulysses is well predicted by an MHD model which can propagate the 1 AU data outward. The CME/shock is tracked remarkably well from the Sun all the way to Ulysses by coronagraph images, type II frequency drift, in situ measurements and the MHD model. These results reveal a technique which combines MHD propagation of the solar wind and type II emissions to predict the shock arrival time at the Earth, a significant advance for space weather forecasting especially when in situ data are available from the Solar Orbiter and Sentinels.Comment: 26 pages, 10 figures. 2008, ApJ, in pres