Search results for "high-resolution"
showing 10 items of 208 documents
Remote sensing and climate data as a key for understanding fasciolosis transmission in the Andes: review and update of an ongoing interdisciplinary p…
2006
Fasciolosis caused by Fasciola hepatica in various South American countries located on the slopes of the Andes has been recognized as an important public health problem. However, the importance of this zoonotic hepatic parasite was neglected until the last decade. Countries such as Peru and Bolivia are considered to be hyperendemic areas for human and animal fasciolosis, and other countries such as Chile, Ecuador, Colombia and Venezuela are also affected. At the beginning of the 1990s a multidisciplinary project was launched with the aim to shed light on the problems related to this parasitic disease in the Northern Bolivian Altiplano. A few years later, a geographic information system (GIS…
A mathematical study on effective wavenumber, an operative computation procedure, and its use with radiance-temperature relationships
2003
In this paper we study the existence of effective wavenumber for any sensor by means of simple mathematics. We implement a numeric algorithm, based on the developed mathematical background, into a computer program named 'srf2radi', which is freely available via anonymous File Transfer Protocol (FTP) at ftp://ftp.uv.es/pub/src/. The number of effective wavenumbers for each temperature and their accuracy are also computed and studied for NOAA-16 Advanced Very High Resolution Radiometer Version 3 (AVHRR/3) channel 4. These effective wavenumbers can be used to obtain radiance-temperature relationships with physical meaning for any sensor in user-defined temperature intervals.
A ‘TVD-like’ Scheme for Conservation Laws with Source Terms
2008
The theoretical foundations of high-resolution TVD schemes for homogeneous scalar conservation laws and linear systems of conservation laws have been firmly established through the work of Harten [5], Sweby [11], and Roe [9]. These TVD schemes seek to prevent an increase in the total variation of the numerical solution, and are successfully implemented in the form of flux-limiters or slope limiters for scalar conservation laws and systems. However, their application to conservation laws with source terms is still not fully developed. In this work we analyze the properties of a second order, flux-limited version of the Lax-Wendroff scheme preserving steady states [3]. Our technique is based …
Chromatography-mass spectrometry: Recent evolution and current trends in environmental science
2020
The coupling of chromatography to mass spectrometry has been a very important step in environmental science that has changed routine workflows opening a horizon of new and impressive possibilities. This hyphenated technique benefits from coupling as chromatography offers great separation power and comprises various techniques and mechanisms. In turn, chromatography exploits the identification capability of mass spectrometry and is able to provide nominal or exact mass charge ration (m/z) not only of the intact molecule but also of several characteristic fragments. The sensitivity, selectivity, specificity, and rapidity in chromatography–mass spectrometry make this technology highly powerful…
Synthesis and characterization of ZnS nanoparticles in water/AOT/n-heptane microemulsions
1999
ZnS nanoparticles were synthetized using water-containing AOT reversed micelles as nanoreactors and characterized by UV-Vis spectrophotometry, HRTEM (high-resolution transmission electron microscopy), SAED (selected-area electron diffraction), and digital image processing. The experimental data evidence a slow growing process of fractal-like ZnS nanoparticles’ coupled with a change of their photophysical properties. Both these processes are well described by power laws. The nanoparticles size is mainly controlled by the micellar size. After evaporation of the organic solvent, it has been found that the deposit is constituted by smaller and more stable ZnS nanoparticles bathed in a surfactan…
Coronary artery calcium score on low-dose computed tomography for lung cancer screening
2013
Aim: To evaluate the feasibility of coronary artery calcium score (CACS) on low-dose non-gated chest CT (ngCCT). Methods: Sixty consecutive individuals (30 males; 73 ± 7 years) scheduled for risk stratification by means of unenhanced ECG-triggered cardiac computed tomography (gCCT) underwent additional unenhanced ngCCT. All CT scans were performed on a 64-slice CT scanner (Somatom Sensation 64 Cardiac, Siemens, Germany). CACS was calculated using conventional methods/scores (Volume, Mass, Agatston) as previously described in literature. The CACS value obtained were compared. The Mayo Clinic classification was used to stratify cardiovascular risk based on Agatston CACS. Differences and corre…
Wide-scope screening of pharmaceuticals, illicit drugs and their metabolites in the Amazon River.
2021
Only a limited number of households in the Amazon are served by sewage collection or treatment facili- ties, suggesting that there might be a significant emission of pharmaceuticals and other wastewater contaminants into freshwater ecosystems. In this work, we performed a wide-scope screening to assess the occurrence of pharmaceuticals, illicit drugs and their metabolites in freshwater ecosystems of the Brazilian Amazon. Our study included 40 samples taken along the Amazon River, in three of its major tributaries, and in small tributaries crossing four important urban areas (Manaus, Santarém, Macapá, Belém). More than 900 compounds were investigated making use of target and suspect screenin…
Evaluation of the maximum evapotranspiration over the La Mancha region, Spain, using NO A A AVHRR data
1992
Abstract Actual evapotranspiration is an important parameter in crop yield models, soil moisture determination and crop stress detection. As actual evapotranspiration is not routinely available, maximum evapotranspiration (ETJ is normally used in agronomic models to calculate watering needs over irrigated areas. For this reason an empirical method has been developed to obtain ETra from albedo and temperature data suplied by the Advanced Very High Resolution Radiometer (AVHRR) sensor on board NOAA satellites. This model has been applied to the La Mancha region, Spain, where barley, vine and maize are the main crops, and ETM was obtained with an acceptable error of ± 1-4 mm of water per day.
Graphene-type sheets of Nb(1-x)W(x)S2: synthesis and in situ functionalization.
2013
Enlightened by the discovery of graphenes, a variety of inorganic analogues have been synthesized and characterized in recent years. Solvated Nb1−xWxS2 analogues of graphene-type sheets were prepared by lithiation and exfoliation of multistacked Nb1−xWxS2 coin roll nanowires (CRNWs), followed by in situ functionalization with gold nanoparticles to synthesize gold-loaded Nb1−xWxS2/Au nanocomposites. The Nb1−xWxS2 nanosheets and the corresponding Nb1−xWxS2/Au nanocomposites were characterized by high resolution electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDX), scanning transmission electron microscopy (STEM), dynamic light scattering (DLS) and scanning force microscopy …
Snapshots of the Formation of NaTi3O6(OH)·2H2O Nanowires: A Time-Resolved XRD/HRTEM Study
2013
Layered titanates are important intermediates during the formation of TiO2-related nanostructures in hot concentrated base solution. Microwave-assisted hydrothermal techniques allow a time-resolved ex-situ analysis of the reaction in one-minute intervals by rapid heating and quenching followed by separation and structure analysis of the intermediates. By a combination of powder X-ray diffraction, high resolution electron microscopy (HRTEM), and selected area electron diffraction (SAED) the individual stages of the reaction could be identified. Sodium titanate nanosheets are formed within several minutes by digesting the crystalline TiO2-P25 precursor in NaOH. These nanosheets with a low sod…