2,304 research outputs found
Optimal control in heterogeneous domain decomposition methods
Some new domain decomposition methods (DDM) based on optimal control approach are introduced for the coupling of first- and second-order equations on overlapping subdomains. Several cost functionals and control functions are proposed. Uniqueness and existence results are proved for the coupled problem and the convergence of iterative processes is analyze
Effect of a glyphosate formulation on freshwater plankton: A community combined metric approach
Aim: The aim of this study was to experimentally assess the effects of glyphosate formulation on plankton composition by using different community parameters through a mesocosm experiment. Methodology: A 600 l mesocosm experiment was performed for 7 days, including a control (without glyphosate) and two concentrations of glyphosate. Results: Glyphosate caused a significant decrease in cladoceran density and a significant increase in rotifer, Chlorophyceae, and Euglenophyceae densities. In addition, zooplankton size diversity as well as microalgal evenness diminished. Interpretation:The decrease in cladoceran density may have benefited rotifers since they are less competitive for food resources. Moreover, the decrease in cladoceran foraging pressure over Chlorophyceae and Euglenophyceae may have benefited them. The different tolerances and competitiveness within the plankton components make the structure of this community a good indicator of environmental disturbance.Fil: Polla, Wanda. Universidad Nacional del Litoral. Facultad de Humanidades y Ciencias. Laboratorio de Ecotoxicologia; ArgentinaFil: Regaldo, Luciana María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Humanidades y Ciencias. Laboratorio de Ecotoxicologia; ArgentinaFil: Reno, Ulises. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Humanidades y Ciencias. Laboratorio de Ecotoxicologia; ArgentinaFil: Popielarz, Andrea Silvina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Gervasio, Susana Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Fernandez, V.. Universidad Nacional del Litoral. Facultad de Humanidades y Ciencias. Laboratorio de Ecotoxicologia; ArgentinaFil: Gagneten, Ana María. Universidad Nacional del Litoral. Facultad de Humanidades y Ciencias. Laboratorio de Ecotoxicologia; Argentin
Micron-sized Spinel Crystals In High Level Waste Glass Compositions: Determination Of Crystal Size And Crystal Fraction
The compositions utilized for immobilization of high-level nuclear wastes (HLW) are controlled using glass property models to avoid the deleterious effects of crystallization in the high-level waste (HLW) vitrification melters. The type and size of the crystals that precipitate during melter operations (typically at 1150 °C) and idling (∼1000 °C) are significantly impacted by glass composition and thermal history. This study was conducted to measure the impact of melt composition and heat treatment temperature on crystal size and fraction. A matrix of 31 multi-component glasses canvasing the expected Hanford HLW compositional space was developed and the glasses fabricated, and heat treated at 850, 900, and 950 °C. The crystal amounts, as determined by X-ray diffraction, varied from 0.2 to 41.0 wt.%. Spinel concentrations ranged from 0.0 to 13.8 wt.%. One glass of the matrix did not precipitate spinel and contained 0.2 wt.% RuO2, which was assumed to be undissolved from the melting process. All compositions contained crystals in the as-quenched glass. All of the spinel-based crystals present in the glasses were less than 10 μm in diameter, as determined by scanning electron microscopy with image analysis. Composition and temperature dependent models were generated using the resulting data and the best model fit was obtained by only considering spinel concentrations (R2 = 0.87). Two glasses were unable to be characterized because of an inability to process the glass under the conditions of this study. Those glasses were utilized to give insight into a potential multi-component constraint to aid in future statistical composition designs
The action of physiological and synthetic steroids on the calcium channel CatSper in human sperm
The sperm-specific channel CatSper (cation channel of sperm) controls the intracellular Ca2+ concentration ([Ca2+]i) and plays an essential role in sperm function. It is mainly activated by the steroid progesterone (P4) but is also promiscuously activated by a wide range of synthetic and physiological compounds. These compounds include diverse steroids whose action on the channel is so far still controversial. To investigate the effect of these compounds on CatSper and sperm function, we developed a high-throughput screening (HTS) assay to measure changes in [Ca2+]i in human sperm and screened 1,280 approved and off-patent drugs including 90 steroids from the Prestwick chemical library. More than half of the steroids tested (53%) induced an increase in [Ca2+]i and reduced the P4-induced Ca2+ influx in human sperm in a dose-dependent manner. Ten of the most potent steroids (activating and P4-inhibiting) were selected for a detailed analysis of their action on CatSper and their ability to act on sperm acrosome reaction (AR) and penetration in viscous media. We found that these steroids show an inhibitory effect on P4 but not on prostaglandin E1-induced CatSper activation, suggesting that they compete for the same binding site as P4. Pregnenolone, dydrogesterone, epiandrosterone, nandrolone, and dehydroepiandrosterone acetate (DHEA) were found to activate CatSper at physiologically relevant concentrations within the nanomolar range. Like P4, most tested steroids did not significantly affect the AR while stanozolol and estropipate slightly increased sperm penetration into viscous medium. Furthermore, using a hybrid approach integrating pharmacophore analysis and statistical modelling, we were able to screen in silico for steroids that can activate the channel and define the physicochemical and structural properties required for a steroid to exhibit agonist activity against CatSper. Overall, our results indicate that not only physiological but also synthetic steroids can modulate the activity of CatSper with varying potency and if bound to CatSper prior to P4, could impair the timely CatSper activation necessary for proper fertilization to occur
High sensitivity GEM experiment on double beta decay of 76-Ge
The GEM project is designed for the next generation 2 beta decay experiments
with 76-Ge. One ton of ''naked'' HP Ge detectors (natural at the first GEM-I
phase and enriched in 76-Ge to 86% at the second GEM-II stage) are operating in
super-high purity liquid nitrogen contained in the Cu vacuum cryostat (sphere
with diameter 5 m). The latest is placed in the water shield. Monte Carlo
simulation evidently shows that sensitivity of the experiment (in terms of the
T1/2 limit for neutrinoless 2 beta decay) is 10^27 yr with natural HP Ge
crystals and 10^28 yr with enriched ones. These bounds corresponds to the
restrictions on the neutrino mass less than 0.05 eV and 0.015 eV with natural
and enriched detectors, respectively. Besides, the GEM-I set up could advance
the current best limits on the existence of neutralinos - as dark matter
candidates - by three order of magnitudes, and at the same time would be able
to identify unambiguously the dark matter signal by detection of its seasonal
modulation.Comment: LaTeX, 20 pages, 4 figure
A search for neutrinoless double beta decay of 130Te with a thermal detector
Abstract A 73.1 g TeO2 bolometric detector has been operating for more than two months at about 16 mK in a specially constructed low activity dilution refrigerator installed in the Gran Sasso Underground Laboratory and shielded against environmental radioactivity. Its energy resolution is comparable with that of a Ge diode. A spectrum of the thermal pulses collected in 1389 h of effective running time shows no evidence for neutrinoless double beta decay of 130Te. The corresponding lower limit of the lifetime is three orders of magnitude more stringent than those obtained for the some nucleus with conventional techniques. It also exceeds the value for the inclusive (two neutrino and neutrinoless) lifetime obtained by geochemical searches. Double beta decay of 130Te has therefore to be attributed mainly to the two neutrino channel
Assessment of the model refinement category in CASP12
We here report on the assessment of the model refinement predictions submitted to the 12th Experiment on the Critical Assessment of Protein Structure Prediction (CASP12). This is the fifth refinement experiment since CASP8 (2008) and, as with the previous experiments, the predictors were invited to refine selected server models received in the regular (nonrefinement) stage of the CASP experiment. We assessed the submitted models using a combination of standard CASP measures. The coefficients for the linear combination of Z‐scores (the CASP12 score) have been obtained by a machine learning algorithm trained on the results of visual inspection. We identified eight groups that improve both the backbone conformation and the side chain positioning for the majority of targets. Albeit the top methods adopted distinctively different approaches, their overall performance was almost indistinguishable, with each of them excelling in different scores or target subsets. What is more, there were a few novel approaches that, while doing worse than average in most cases, provided the best refinements for a few targets, showing significant latitude for further innovation in the field
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