Search results for "quantitative"
showing 10 items of 2409 documents
Spatial graphs and Convolutive Models
2020
In the last two decades, many complex systems have benefited from the use of graph theory, and these approaches have shown robust applicability in the field of finance, computer circuits and in biological systems. Large scale models of brain systems make also a great use of random graph models. Graph theory can be instrumental in modeling the connectivity and spatial distribution of neurons, through a characterization of the relative topological properties. However, all approaches in studying brain function have been so far limited to use experimental constraints obtained at a macroscopic level (e.g. fMRI, EEG, MEG, DTI, DSI). In this contribution, we present a microscopic use (i.e. at the …
Detection of lactobacillic acid in low erucic rapeseed oil--A note of caution when quantifying cyclic fatty acid monomers in vegetable oils.
2010
International audience; The purpose of this work was to identify an unknown component which has been detected during the analysis of cyclic fatty acid monomers (CFAMs) in low erucic acid rapeseed oils (LEAR). A sample of crude LEAR was transformed into fatty acid methyl esters (FAMEs) and hydrogenated using PtO2. The hydrogenated sample was fractionated by reversed-phase high-performance liquid chromatography (RP-HPLC) and the fraction containing the CFAMs transformed into picolinyl esters. Analysing these picolinyl derivatives by gas-liquid chromatography coupled to mass spectrometry (GC-MS) showed that the unknown product observed in LEAR is the 11,12-methylene-octadecanoic acid. This cyc…
Efficient flow injection and sequential injection methods for spectrophotometric determination of oxybenzone in sunscreens based on reaction with Ni(…
2001
Spectrophotometric determination of a widely used UV-filter, such as oxybenzone, is proposed. The method is based on the complexation reaction between oxybenzone and Ni(II) in ammoniacal medium. The stoichiometry of the reaction, established by the Job method, was 1:1. Reaction conditions were studied and the experimental parameters were optimized, for both flow injection (FI) and sequential injection (SI) determinations, with comparative purposes. Sunscreen formulations containing oxybenzone were analyzed by the proposed methods and results compared with those obtained by HPLC. Data show that both FI and SI procedures provide accurate and precise results. The ruggedness, sensitivity and LO…
A Quantitative Model for Alkane Nucleophilicity Based on C−H Bond Structural/Topological Descriptors
2020
A first quantitative model for calculating the nucleophilicity of alkanes is described. A statistical treatment was applied to the analysis of the reactivity of 29 different alkane C−H bonds towards in situ generated metal carbene electrophiles. The correlation of the recently reported experimental reactivity with two different sets of descriptors comprising a total of 86 parameters was studied, resulting in the quantitative descriptor‐based alkane nucleophilicity (QDEAN) model. This model consists of an equation with only six structural/topological descriptors, and reproduces the relative reactivity of the alkane C−H bonds. This reactivity can be calculated from parameters emerging from th…
O pytaniach podczas rozmowy maturalnej z języka polskiego
2019
“Now, let us move to our conversation — please name characteristics of a parable”. On questions students are asked during their high school oral leaving exam in PolishIn the article I present the results of a qualitative and quantitative analysis of 149 questions asked by teachers during 30 high school oral leaving exams in Polish. In this I use the classification formulated by Elizabeth Perrott, who, taking into account Benjamin Bloom’s “taxonomy of educational objectives”, has proposed a division of the questions by the type of thinking process launched during answering, distinguishing lower-level questions recall, understanding, application and higher-level questions analysis, synthesis …
YouTube and influencers in childhood. Content analysis and educational proposals
2020
RESUMEN: La presencia de las tecnologías móviles e Internet entre los niños y jóvenes está generando nuevos marcos de comprensión, interacción y consumo de medios y contenidos. YouTube se ha convertido en una de las plataformas más utilizadas por estos, lo cual exige investigar las repercusiones ejercidas por estos influencers en los niños. En el presente trabajo se realiza una contextualización teórica sobre el nuevo entorno digital en el que Internet y las redes sociales forman parte indiscutible de la cotidianeidad, para avanzar hacia un marco metodológico y de investigación de los principales YouTubers seguidos por niños/as de Educación Primaria en España. Se ha utilizado una metodologí…
Polarographische Untersuchungen an monomeren und polymeren N-Chlorcarbonamiden
1979
The polarographic reduction of low molecular and high molecular N-chlorocarboxamides at the dropping mercury electrode proceeds in two one-electron-transfer steps, which are highly irreversible. In the case of the low molecular models 1 and 2 the reaction is diffusion-controlled, whereas in the case of the poly(N-chloroamide) 3 the reaction is adsorption-controlled. Reduction of several poly(N-chloroamide)s shows always two reduction waves with a distance of 0,5 V. There is, however, no relation between the polyamide-type and the position of the half-wave potentials. The polarographic reduction can be used as an analytical method for quantitative determination of N-chlorocarboxamide groups …
From Knowledge to Action, Analysis of the Decision Making Process in Africa : the Case of the State Contract Teacher Policy
2011
Policy analysis in Africa has mainly focused on their evaluation. Now that several reforms are undertaken and that the progressive move toward democracy allows new actors to enter the political arena, it is useful to analyze how decisions on public issues are made. The dissertation examines the reform of the teacher recruitment policy in francophone Africa. The reform consisted in changing the teacher status in order to allow the government to pay a lower salary to new teachers. The drawbacks of the usual policy and research from the area of economics of education demonstrating that the reform was necessary put the issue on the agenda. If many countries adopted it, some have not. Factors th…
Perspectives of REAL network scholars: Challenges and opportunities for regional development
2020
The aim of many policy actions is to foster the interaction between scientific research, firms and regional development. However, the manner by which this interaction may be stimulated and the measuring of its effects are still a challenging research topic (Bernela & Levy, 2017). This special issue of Regional Science Policy & Practice journal is one example of research collaboration among scholars in regional science research worldwide.
Taiteella on vapautensa mutta…
2020
Poliitikkojen väitetään vaikenevan taiteesta ja kulttuurista. Suurimmalla osasta puolueista on silti tarve sanallistaa suhdettaan taiteeseen ja kulttuuriin sekä niiden edistämiseen. Tutkimusaineistoni koostuu viimeisen kuudenkymmenen vuoden aikana toimineen 48 puolueen 1270 poliittisesta ohjelmasta. Vuosina 1960–2019 toimivista ja vuodesta 1969 lähtien rekisteröityjen puolueiden ohjelmista yhteensä 579:stä löytyy taide- ja kulttuurikirjauksia. Tämän artikkelin tavoitteena on laadullisen ja määrällisen sisällönanalyysin kautta löytää, tunnistaa ja nimetä eri puolueita yhdistävät pitkät linjat, päämäärät ja motiivit taidetta ja kulttuuria koskevissa kirjauksissa poliittisissa ohjelmateksteiss…