49,405 research outputs found
Food allergy in children: relationship between level of IgE intestinal cells and response to restricted diet
No full textSBA-15 Anchored Metal Containing Catalysts in the Oxidative Desulfurization Process
No full textRecalcitrant sulfur compounds are common impurities in crude oil. During combustion they produce SOx derivatives that are able to affect the atmospheric ozone layer, increasing the formation of acid rains, and reducing the life of the engine due to corrosion. In the last twenty years, many efforts have been devoted to develop conventional hydrodesulfurization (HDS) procedures, as well as alternative methods, such as selective adsorption, bio-desulfurization, oxidative desulfurization (ODS) under extractive conditions (ECODS), and others. Among them, the oxidative procedures have been usually accomplished by the use of toxic stoichiometric oxidants, namely potassium permanganate, sodium bromate and carboxylic and sulfonic peracids. As an alternative, increasing interest is devoted to selective and economical procedures based upon catalytic methods. Heterogeneous catalysis is of relevance in industrial ODS processes, since it reduces the leaching of active species and favors the recovery and reuse of the catalyst for successive transformations. The heterogenization of different types of high-valent metal transition-based organometallic complexes, able to promote the activation of stoichiometric benign oxidants like peroxides, can be achieved using various solid supports. Many successful cases have been frequently associated with the use of mesoporous silicas that have the advantage of easy surface modification by reaction with organosilanes, facilitating the immobilization of homogeneous catalysts. In this manuscript the application of SBA-15 as efficient support for different active metal species, able to promote the catalytic ODS of either model or real fuels is reviewed, highlighting its beneficial properties such as high surface area, narrow pore size distribution and tunable pore diameter dimensions. Related to this topic, the most relevant advances recently published, will be discussed and critically described
Harmonic analysis of oscillators throught standard numerical continuation tools
No full textIn this paper, we describe a numerical continuation method that enables harmonic analysis of nonlinear periodic oscillators. This method is formulated as a boundary value problem that can be readily implemented by resorting to a standard continuation package — without modification — such as AUTO, which we used. Our technique works for any kind of oscillator, including electronic, mechanical and biochemical systems. We provide two case studies. The first study concerns itself with the autonomous electronic oscillator known as the Colpitts oscillator, and the second one with a nonlinear damped oscillator, a nonautonomous mechanical oscillator. As shown in the case studies, the proposed technique can aid both the analysis and the design of the oscillators, by following curves for which a certain constraint, related to harmonic analysis, is fulfilled
Modeling the dynamic rupture propagation on heterogeneous faults with rate- and state-dependent friction RID B-5039-2010
No full textWe investigate the effects of non-uniform distribution of constitutive parameters on the dynamic propagation of an earthquake rupture. We use a 2D finite difference numerical method and we assume that the dynamic rupture propagation is governed by a rate- and state-dependent constitutive law. We first discuss the results of several numerical experiments performed with different values of the constitutive parameters a (to account for the direct effect of friction), b (controlling the friction evolution) and L (the characteristic length-scale parameter) to simulate the dynamic rupture propagation on homogeneous faults. Spontaneous dynamic ruptures can be simulated on velocity weakening (a < b) fault patches: our results point out the dependence of the traction and slip velocity evolution on the adopted constitutive parameters. We therefore model the dynamic rupture propagation on heterogeneous faults. We use in this study the characterization of different frictional regimes proposed by Boatwright and Cocco (1996) based on different values of the constitutive parameters a, b and L. Our numerical simulations show that the heterogeneities of the L parameter affect the dynamic rupture propagation, control the peak slip velocity and weakly modify the dynamic stress drop and the rupture velocity. Moreover, a barrier can be simulated through a large contrast of L parameter. The heterogeneity of a and b parameters affects the
dynamic rupture propagation in a more complex way. A velocity strengthening area (a > b) can arrest a dynamic rupture, but can be driven to an instability if suddenly loaded by the dynamic rupture front. Our simulations provide a picture of the complex interactions between fault patches having different frictional properties and illustrate how the traction and slip velocity evolutions are modified during the propagation on heterogeneous faults. These results involve interesting implications for slip duration and fracture energy
Sensitivity of cloud radiative forcing to changes of microphysical parameters measured by the CLOUDS mission
No full textCLOUDS (a Cloud and Radiation monitoring satellite) is a study for a satellite mission designed to provide the gross vertical profile, the internal structure. the radiative and the imaging features of clouds. This subject is addressed by several missions designed for process study intent. CLOUDS, instead, is designed for providing data of routine use in long-term Numerical Weather Prediction (NWP) and General Circulation Model (GCM). User requirements have been collected from various sources, and instruments concepts derived to meet those requirements. However, to establish the sensitivity of a GCM to the targeted parameters and confirm the soundness of the specified requirements (mainly accuracy and vertical resolution), special effort had to be placed. The present paper offers a rather complete assessment of the range of usefulness that CLOUDS measurements may have on the radiative calculation. To this purpose, the cloud forcing was computed as a function of cloud parameters by using a radiative model that has been applied in the GCM of the Laboratory for Atmospheres at the NASA Goddard Space Flight Center. The results show that, in most cases, the model response to the addressed cloud parameters is good if the error is within the specified limit. This is better demonstrated for relatively large particle sizes, for ice better than for liquid water, for low optical thickness and for low cloud cover. The model, however, suggests that more stringent requirements would be appropriate when small particles are considered
Selaginella goudotiana var. abyssinica Bizzarri
No full text<p> <b> <i>Selaginella goudotiana</i> Spring var. <i>abyssinica</i> (Spring) Bizzarri</b> —</p> <p>Habit: Lycophyte.</p> <p>Habitat: LMWF; up to 2 500 m. Distribution: II.</p> <p>Voucher: N/A.</p> <p>References: Bussmann (1994), Bussmann & Beck (1995a), Agnew (2013).</p>Published as part of <i>Zhou, Ya-Dong, Mwachala, Geoffrey, Hu, Guang-Wan & Wang, Qing-Feng, 2022, Annotated checklist of the vascular plants of Mount Kenya, East Africa, pp. 1-108 in Phytotaxa 546 (1)</i> on page 13, DOI: 10.11646/phytotaxa.546.1.1, <a href="http://zenodo.org/record/6550464">http://zenodo.org/record/6550464</a>
Measurement of the ratio of branching fractions B(B0→K∗0γ )/B(B0s→φγ ) and the directCP asymmetry inB 0→K∗0γ
No full textThe ratio of branching fractions of the radiative B decays B0→K⁎0γ and B0s→ϕγ has been measured using an integrated luminosity of 1.0 fb−1 of pp collision data collected by the LHCb experiment at a centre-of-mass energy of s√=7TeV. The value obtained is
B(B0→K⁎0γ)B(B0s→ϕγ)=1.23±0.06(stat.)±0.04(syst.)±0.10(fs/fd),
where the first uncertainty is statistical, the second is the experimental systematic uncertainty and the third is associated with the ratio of fragmentation fractions fs/fd. Using the world average value for B(B0→K⁎0γ), the branching fraction B(B0s→ϕγ) is measured to be (3.5±0.4)×10−5.
The direct CP asymmetry in B0→K⁎0γ decays has also been measured with the same data and found to be
ACP(B0→K⁎0γ)=(0.8±1.7(stat.)±0.9(syst.))%.
Both measurements are the most precise to date and are in agreement with the previous experimental results and theoretical expectations
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
GPS radio occultation sounding to support general circulation models
No full textAn assessment of the suitability of the horizontal and vertical resolution of GPS radio occultation measurements for climate studies is carried out. Simple physical relations are used to estimate the consistency between horizontal and vertical resolutions of radio occultation measurements as compared with those of the existing observing systems. In particular, the horizontal scale of the upper troposphere water vapour is investigated by analysing the variability of the refractivity index using the re-analysis data from NCEP/NCAR. The computation shows that the 300 km horizontal resolution of GPS radio occultation is within the useful range and captures the water vapour variations that are relevant for climatological purposes. Next, focusing the analysis on the requirements of the vertical resolution, we study the sensitivity of a radiative model to changes in the vertical resolution, assessing the impacts of these variations on the atmospheric equilibrium. For this purpose one reference profile and other five with lower vertical resolutions are used to perform the experiment. Results show that the model is sensitive to variations in the vertical sampling, suggesting that high vertical resolution measurements are necessary for an accurate observation of the atmosphere. To further assess the influence of the vertical sampling, the thermal tropopause height dependence on the number of layers considered is studied. Results indicate that the highest vertical resolution is needed for determining the radiative component of the tropopause dynamics
Racecadotril at the Beginning of Pediatric Gastroenteritis: A Small Experience of a Primary Level Hospital
No full textparents because of it does not reduce the frequency of bowel movements and the loss of fluids from the gut nor
shortens the duration of the disease.
Racecadotril reduces secretions of intestinal fluids but it doesn’t inhibit the intestinal motility.
Methods: We retrospectively reviewed 61 children affected by mild acute gastroenteritis consecutively admitted
to our Pediatric Service along two years (2009 to 2010).
The children treated with Racecadotril plus OR were 26 and those treated with OR alone were 35.
Results: Out of 35 children treated with Racecadotril+OR, 17 patients (65.4%) were discharged within twentyfour
hours after admission because of a marked improvement in symptoms compared with the 14/35 patients
(40.0%) of children treated with OR alone with statistically significant values (p<0.05).
Children, converted to parenteral therapy due to the worsening of symptoms, were 26.9% and 42.9% in the
OR+Racecadotril Group and in the OR Group respectively. We have had no side effects regarding the use of
Racecadotril.
Conclusions: Our hospital is a Primary Level Hospital and we often assess children at the beginning of their
symptoms. This allows us to administer Racecadotril at the onset of diarrhoea.
Our sample is small, but it shows that the early use of Racecadotril shortens the hospitalization and decreases
the rate of conversion to parenteral rehydration therapy in children with mild gastroenteriti
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