559 research outputs found
First direct observation of two protons in the decay of Fe with a TPC
The decay of the ground-state two-proton emitter 45Fe was studied with a
time-projection chamber and the emission of two protons was unambiguously
identified. The total decay energy and the half-life measured in this work
agree with the results from previous experiments. The present result
constitutes the first direct observation of the individual protons in the
two-proton decay of a long-lived ground-state emitter. In parallel, we
identified for the first time directly two-proton emission from 43Cr, a known
beta-delayed two-proton emitter. The technique developped in the present work
opens the way to a detailed study of the mechanism of ground-state as well as
beta-delayed two-proton radioactivity.Comment: 4 pages, 5 figure
Characterization of a radiator of eight arms with circular polarization
The cross antenna is a printed structure of average profile and circular polarization, which consists of a conductor or tape on a ground plane that follows the contour of a cross with four or more arms and a diameter of about 1.5 wavelengths developed by Antoine Roederer. The antenna is feeded by means of a coaxial line and is finished in an impedance of load, for what it is represented by a behavior of travelling wave. Though in principle the antenna was designed for applications in mobile communications in Band L (1500 MHhz), we present in this work the experimental characterization of an antenna of cross of eight arms that is employed at 10 GHz, with the principal intention of serving as feeder of a parabolic reflector for satellite communications
Floating stones off El Hierro, Canary Islands: xenoliths of pre-island sedimentary origin in the early products of the October 2011 eruption
The eruption that started off the south coast of El Hierro, Canary Islands, in October 2011 has emitted intriguing eruption products found floating in the sea. These specimens appeared as floating volcanic "bombs" that have in the meantime been termed "restingolites" (after the close-by village of La Restinga) and exhibit cores of white and porous pumice-like material. Currently the nature and origin of these "floating stones" is vigorously debated among researchers, with important implications for the interpretation of the hazard potential of the ongoing eruption. The "restingolites" have been proposed to be either (i) juvenile high-silica magma (e.g. rhyolite), (ii) remelted magmatic material (trachyte), (iii) altered volcanic rock, or (iv) reheated hyaloclastites or zeolite from the submarine slopes of El Hierro. Here, we provide evidence that supports yet a different conclusion. We have collected and analysed the structure and composition of samples and compared the results to previous work on similar rocks found in the archipelago. Based on their high silica content, the lack of igneous trace element signatures, and the presence of remnant quartz crystals, jasper fragments and carbonate relicts, we conclude that "restingolites" are in fact xenoliths from pre-island sedimentary rocks that were picked up and heated by the ascending magma causing them to partially melt and vesiculate. They hence represent messengers from depth that help us to understand the interaction between ascending magma and crustal lithologies in the Canary Islands as well as in similar Atlantic islands that rest on sediment/covered ocean crust (e.g. Cape Verdes, Azores). The occurrence of these "restingolites" does therefore not indicate the presence of an explosive high-silica magma that is involved in the ongoing eruption
Precision measurement of the half-life and the decay branches of 62Ga
In an experiment performed at the Accelerator Laboratory of the University of
Jyvaskyla, the beta-decay half-life of 62Ga has been studied with high
precision using the IGISOL technique. A half-life of T1/2 = 116.09(17)ms was
measured. Using beta-gamma coincidences, the gamma intensity of the 954keV
transition and an upper limit of the beta-decay feeding of the 0+_2 state have
been extracted. The present experimental results are compared to previous
measurements and their impact on our understanding of the weak interaction is
discussed.Comment: 7 pages, 7 figures, submitted to EPJ
Tratamiento de agua residual de microbiología usando películas delgadas de TiO2
(Eng) Microbiology cell-staining wastewater was treated by UV/TiO 2 thin films photocatalysis. A simple method of applying gravity sedimentation over grass-type substrate was used for the preparation of the films. The use of Na4 P2 O7, microwaves, and ultrasounds were studied for decreasing the TiO2 grain sizes on the films. It was established that the best method for reducing grain size resulted from a combination of Na4P2O7 (0.01M) and microwave radiation (700 W, 20 min). The Films were characterized by several microscopic and
spectroscopic methods. Anatase phase (gap energy of 3.2 eV) and grain sizes averaging 83 nm were achieved. Photocatalysis tests using TiO2-film showed 99.5 % of decolorization, 79 % TOC abatement, and total microbial inactivation after 14 h of treatment. No bacteria re–growth was found 48 h after the treatment was completed.(Spa) La fotocatálisis con UV/TiO2usando películas delgadas fue empleada para el tratamiento de agua residual de microbiología. Se empleó un método simple de sedimentación por gravedad sobre sustrato de vidrio para la preparación de las películas. El uso de Na4P2O7, microondas y ultrasonido fue estudiado para la disminución de los granos de TiO2 en las películas. Se estableció que el mejor método para disminuir los agregados resultó de una combinación de Na4P2O7(0.01M) y radiación de microondas (700 W, 20 min). Las películas fueron caracterizadas por métodos microscópicos y espectroscópicos. Se obtuvo la fase anatasa (brecha de energía de 3.2 e.V) y tamaños de grano de 83nm. Los ensayos fotocatalíticos utilizando las películas de TiO2generaron un 99.5% de decoloración, 79% de remoción de COT y una inactivación microbiana total luego de 14 h de tratamiento. No se encontró reactivación microbiana luego de 48 h de finalizado el tratamiento
Separation of the Exchange-Correlation Potential into Exchange plus Correlation: an Optimized Effective Potential Approach
Most approximate exchange-correlation functionals used within density
functional theory are constructed as the sum of two distinct contributions for
exchange and correlation. Separating the exchange component from the entire
functional is useful since, for exchange, exact relations exist under uniform
density scaling and spin scaling. In the past, accurate exchange-correlation
potentials have been generated from essentially exact densities constructed
using information from either quantum chemistry or quantum Monte Carlo
calculations but they have not been correctly decomposed into their separate
exchange and correlation components, except for two-electron systems. exchange
and correlation components (except for two-electron systems). Using a recently
proposed method, equivalent to the solution of an optimized effective potential
problem with the corresponding orbitals replaced by the exact Kohn-Sham
orbitals, we obtain the separation according to the density functional theory
definition. We compare the results for the Ne and Be atoms with those obtained
by the previously used approximate separation scheme
Molecular Pathogenesis of Preeclampsia: MicroRNA Hypothesis
The discovery of micro RNA (miRNA) in 1993 by Ambros and colleagues has a huge influence in pathogenesis theory, diagnosis and treatment approach of some diseases. Some studies have conducted to seek the association alterations of miRNA expression to incidences and severity of preeclampsia (PE). We have reviewed some studies that conducted to seek the association of miRNA and PE and we discussed the role of various miRNAs in PE pathogenesis. In summary, we have shown that many researchers have given evident that the different placental and plasma miRNA expression is associated with PE. Some studies also identified the novel candidate of miRNAs (and their pathways) that may be of etiologic relevance in the pathogenesis of PE. Base on review, specific miRNA have a role to down regulate of anti apoptosis genes, regulate angiogenics growth factors such as angiogenin, vascular endothelial growth factor (VEGF) B (VEGF-β), cysteine-rich 61 (CYR61), Placental growth factor (PlGF) and VEGF-A that have a role in angiogenesis. miRNA also have a role in survival, migration, and capillary tube formation of HUVEC by targeted of c-kit. Some miRNAs target genes that participate in immunologic dysfunction, cell adhesion, cell cycle, and signaling. miRNA also have a roles in endothelial cell response to hypoxia, cell differentiation, and survival. A miRNA influence calcium signaling through negative regulations of the calmodulin-coding mRNAs, Mef2a and Gata4, mainly in smooth muscle cells that contribute to PE pathogenesis. These investigations provide novel targets for further investigation of the pathogenesis of PE and these differential miRNAs may be potential markers for the diagnosis and provide a potential therapeutic target for PE. Further investigations on posttranscriptional regulation in PE to evaluate biologic effects of identified miRNAs (including confirmations of miRNA and target gene interactions) are neede
Exportações da piscicultura brasileira cresceram 119% em valor no primeiro trimestre de 2022.
As exportações da piscicultura aumentaram 119% comparadas ao primeiro trimestre de 2021, atingindo US 6,8 milhões, representando 97% do total. O Paraná foi o maior exportador de tilápia, com US$ 3 milhões. Os Estados Unidos importaram 78% das exportações brasileiras da piscicultura
Exportações da piscicultura brasileira cresceram 15% em 2022.
Exportações aumentaram 15% em 2022, atingindo US 23,2 milhões. Exportações de filés de tilápia congelados aumentaram 98% no ano, atingindo US 13,2 milhões
Exportações da piscicultura brasileira cresceram 78% em 2021.
As exportações da piscicultura brasileira totalizaram U 7,9 milhões. Percebe-se um crescimento gradual das exportações ao longo dos quatro trimestres do ano, tanto em termos de toneladas como em relação a valores financeiros
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