54,480 research outputs found
Parabolic dunes in north-eastern Brazil
In this work we present measurements of vegetation cover over parabolic dunes
with different degree of activation along the north-eastern Brazilian coast. We
are able to extend the local values of the vegetation cover density to the
whole dune by correlating measurements with the gray-scale levels of a high
resolution satellite image of the dune field. The empirical vegetation
distribution is finally used to validate the results of a recent continuous
model of dune motion coupling sand erosion and vegetation growth.Comment: 18 pages, 14 figures, aubmitted to Geomorpholog
Robustness of the transition against compositional and structural ageing in S/F/S heterostructures
We have studied the temperature induced thermodynamic transition in
Nb/PdNi/Nb Superconductor/Ferromagnetic/Superconductor (SFS) heterostructures
by microwave measurements of the superfluid density. We have observed a shift
in the transition temperature with the ageing of the heterostructures,
suggesting that structural and/or chemical changes took place. Motivated by the
electrodynamics findings, we have extensively studied the local structural
properties of the samples by means of X-ray Absorption Spectroscopy (XAS)
technique, and the compositional profile by Time-of-Flight Secondary Ion Mass
Spectrometry (ToF-SIMS). We found that the samples have indeed changed their
properties, in particular for what concerns the interfaces and the composition
of the ferromagnetic alloy layer. The structural and compositional data are
consistent with the shift of the transition toward the behaviour of
heterostructures with different F layers. An important emerging indication to
the physics of SFS is the weak relevance of the ideality of the interfaces:
even in aged samples, with less-than-ideal interfaces, the temperature-induced
transition is still detectable albeit at a different critical F
thickness.Comment: 11 pages, 9 figures, accepted for publication on Phys. Rev. B,
http://journals.aps.org/prb
Impact of water saving irrigation systems on water use, growth and yield of irrigated lowland rice
To meet the growing demand for food and other needs from an increasing population, the rice production in Sri Lanka, which was 3.87 million tonnes in 2008, has to be increased to 4.2 million tonnes by the year 2020. This requirement could be achieved by increasing productivity and/or by increasing the cultivated extent. In 2008, about 77 % and 68 % of the total paddy land extent was cultivated with either partial or full irrigation during the maha and yala seasons, respectively. A considerable extent of paddy land was either not cultivated or cultivated for other crops due to the scarcity of water in the dry and intermediate zones. Furthermore, with increased competition for water for domestic and industrial needs and climate change, there will be further reductions in the availability of water for rice cultivation. Conserving irrigation water would increase the cultivated extent of land while reducing the probability of ate season water-stress in the cultivated rice crop. We studied the impact of different soil water regimes on water use, nutrient uptake, growth and grain yield of 3 – 3� age lowland rice at the Rice Research and Development Institute, Batalagoda, Ibbagamuwa. There was no significant difference in the grain yield in rice when grown under either saturated or flooded conditions, but the yield decreased significantly with alternate wetting and drying. However, under saturated conditions, the irrigation water requirement was significantly lower than the flooded condition. The lowest irrigation water requirement was recorded with saturated to dry conditions. The irrigation water requirement under flooded conditions, when compared with the saturated condition, increased by 39 % during the yala season. During the maha season, even though the total irrigation requirement was lower, when compared to saturated conditions, four times more irrigation water was required under flooded conditions. There was a significant increase in plant dry matter production and leaf N (nitrogen) under saturated conditions, when compared with conventional flooded conditions. These findings suggest that when soil water is maintained at a saturated level in lowland rice, a considerable amount of irrigation water could be saved without sacrificing grain yield.Length: pp.57-64RiceIrrigated farmingWater conservationIrrigation systems
Revealing structure and evolution within the corona of the Seyfert galaxy I Zw 1
X-ray spectral timing analysis is presented of XMM-Newton observations of the
narrow line Seyfert 1 galaxy I Zwicky 1 (I Zw 1) taken in 2015 January. After
exploring the effect of background flaring on timing analyses, X-ray time lags
between the reflection-dominated 0.3-1.0keV energy and continuum-dominated
1.0-4.0keV band are measured, indicative of reverberation off the inner
accretion disc. The reverberation lag time is seen to vary as a step function
in frequency; across lower frequency components of the variability, 3e-4 to
1.2e-3Hz a lag of 160s is measured, but the lag shortens to (59 +/- 4)s above
1.2e-3Hz. The lag-energy spectrum reveals differing profiles between these
ranges with a change in the dip showing the earliest arriving photons. The low
frequency signal indicates reverberation of X-rays emitted from a corona
extended at low height over the disc while at high frequencies, variability is
generated in a collimated core of the corona through which luminosity
fluctuations propagate upwards. Principal component analysis of the variability
supports this interpretation, showing uncorrelated variation in the spectral
slope of two power law continuum components. The distinct evolution of the two
components of the corona is seen as a flare passes inwards from the extended to
the collimated portion. An increase in variability in the extended corona was
found preceding the initial increase in X-ray flux. Variability from the
extended corona was seen to die away as the flare passed into the collimated
core leading to a second sharper increase in the X-ray count rate.Comment: 18 pages, 11 figures. Accepted for publication in MNRA
Tonsillar ulceration as manifestation of disseminated African histoplasmosis in an immunocompetent Portuguese host
Free PMC Article: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5466580/Histoplasmosis is a systemic mycosis caused by Histoplasma capsulatum. Rare in Europe but endemic in some regions of Brazil, United States, Africa and Asia. Most of the cases are asymptomatic. Disseminated form is defined by the presence of an extra-pulmonary focus, particularly associated with immunosuppression. We report a case of an unilateral persisted tonsillar ulceration, in an immunocompetent Portuguese host, as manifestation of disseminated African histoplasmosis 45 years later after living 3 years in Africa.info:eu-repo/semantics/publishedVersio
Tonsillar ulceration as manifestation of disseminated African histoplasmosis in an immunocompetent Portuguese host
Free PMC Article: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5466580/Histoplasmosis is a systemic mycosis caused by Histoplasma capsulatum. Rare in Europe but endemic in some regions of Brazil, United States, Africa and Asia. Most of the cases are asymptomatic. Disseminated form is defined by the presence of an extra-pulmonary focus, particularly associated with immunosuppression. We report a case of an unilateral persisted tonsillar ulceration, in an immunocompetent Portuguese host, as manifestation of disseminated African histoplasmosis 45 years later after living 3 years in Africa.info:eu-repo/semantics/publishedVersio
Picture-based task definition and parameterization support system
Applications for task definition and automation are valuable tools to automated software engineering area. This paper describes a solution to support a parameterized task definition using screen capture images. The approach allows the capture of a sequence of actions defined by the user. Through the captured sequence of actions, the approach assists in the implementation of task automation processes. Based on picture-driven computing the proposed tool aims to reduce the challenges that users face while trying to define tasks. This approach provides also a foundation for the creation of picture-driven based tests for interactive systems, enabling to test any interactive system but also allowing for the definition, parameterization and execution of tests that might involve the use of several independent interactive systems.info:eu-repo/semantics/acceptedVersio
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