320 research outputs found
Théories musicales
L’opĂ©ration magique impose le respect du rituel dans la gestuelle et les enchantements. NĂ©anmoins, les grimoires n’expliquent pas les modalitĂ©s d’énonciation des paroles magiques. Seules les thĂ©ories musicales peuvent apporter une information complĂ©mentaire sur cet aspect des pratiques magiques. Exception faite de la place de l’esthĂ©tisme dans le chant, surtout liturgique, qui n’est pas abordĂ© par les grimoires, les diffĂ©rents Ă©lĂ©ments qui constituent la thĂ©orie musicale conviennent Ă la rĂ©alisation des enchantements.Magic demands that ritual should be respected for movements and enchantments. Although books of spells explain the steps to achieve a magic ritual, they set no details on a specific pronunciation of magic words. Musical theories only can bring additional information on this aspect of magic practices. Except the problem of aestheticism in singing, mainly in liturgical singing which is not mentioned in magic books, the diverse elements of the musical theory may fit, for the most part, the spell ritual.El ritual mágico impone el estricto respeto en la realizaciĂłn de los gestos y de los encantamientos. Sin embargo los grimorios no ofrecen ninguna informaciĂłn sobre el modo de enunciaciĂłn de las palabras mágicas. Al tratarse de un discurso oral modulado, sĂłlo las teorĂas musicales pueden aportar informaciĂłn sobre este aspecto de las prácticas mágicas. Exceptuando la reflexiĂłn sobre la estĂ©tica del canto litĂşrgico, que no aparece en ningĂşn grimorio, los diferentes elementos que pueden conformar la teorĂa musical, pueden convenir a la realizaciĂłn de los encantamientos
Intrinsic variability of the Atlantic Meridional Overturning Circulation at interannual-to-multidecadal time scales
The low-frequency variability of the Atlantic meridional overturning circulation (AMOC) is investigated from 2, ¼°, and ° global ocean–sea ice simulations, with a specific focus on its internally generated (i.e., “intrinsic”) component. A 327-yr climatological ¼° simulation, driven by a repeated seasonal cycle (i.e., a forcing devoid of interannual time scales), is shown to spontaneously generate a significant fraction R of the interannual-to-decadal AMOC variance obtained in a 50-yr “fully forced” hindcast (with reanalyzed atmospheric forcing including interannual time scales). This intrinsic variance fraction R slightly depends on whether AMOCs are computed in geopotential or density coordinates, and on the period considered in the climatological simulation, but the following features are quite robust when mesoscale eddies are simulated (at both ¼° and ° resolutions); R barely exceeds 5%–10% in the subpolar gyre but reaches 30%–50% at 34°S, up to 20%–40% near 25°N, and 40%–60% near the Gulf Stream. About 25% of the meridional heat transport interannual variability is attributed to intrinsic processes at 34°S and near the Gulf Stream. Fourier and wavelet spectra, built from the 327-yr ¼° climatological simulation, further indicate that spectral peaks of intrinsic AMOC variability (i) are found at specific frequencies ranging from interannual to multidecadal, (ii) often extend over the whole meridional scale of gyres, (iii) stochastically change throughout these 327 yr, and (iv) sometimes match the spectral peaks found in the fully forced hindcast in the North Atlantic. Intrinsic AMOC variability is also detected at multidecadal time scales, with a marked meridional coherence between 35°S and 25°N (15–30 yr periods) and throughout the whole basin (50–90-yr periods)
La bioadsorption sur amidon réticulé pour enlever des métaux des effluents industriels
L’industrie de traitement de surface utilise de nombreux produits chimiques, en particulier des métaux toxiques et des substances organiques, qui sont connus pour être nocifs vis-à -vis des humains et de l’environnement. En raison d’une réglementation de plus en plus stricte, les effluents contenant des métaux lourds doivent être traités. Il existe une grande variété de procédés de traitement des eaux usées provenant de la filière traitement de surface. En général, les systèmes conventionnels de détoxification se composent principalement d’un ajustement de pH, d’une oxydation des cyanures et d’une réduction des chromes, suivi d’une précipitation sous forme d’hydroxydes et d’une clarification, et parfois d’une étape d’adsorption sur charbon. Cependant, la technologie sur charbon actif présente plusieurs problèmes tels que la saturation rapide et des problèmes de colmatage des réacteurs. Comme les résines d'échange d’ions, leur utilisation est restreinte due au coût élevé. Pour ces raisons, la plupart des petites et moyennes entreprises ne peuvent pas utiliser de tels traitements. Ainsi, afin de répondre à ces problématiques, de nombreuses études sont menées pour trouver des alternatives peu coûteuses, qui soient efficaces et acceptables pour un usage industriel. Dans cette étude, la bioadsorption sur un adsorbant d’amidon réticulé a été utilisée pour retenir les métaux contenus dans des effluents industriels. L’adsorption a été étudiée en fonction du temps de contact, de la masse d’adsorbant et de la charge polluante. L’influence de ces paramètres sur l’efficacité d’adsorption a été évaluée en utilisant une méthode conventionnelle en mode cuvée. Les résultats ont montré que le matériau présente des capacités d’adsorption élevées vis-à -vis des ions métalliques, ce qui permet de diminuer les concentrations métalliques en dessous des valeurs réglementaires. Des mesures de taux de germination sur des graines de Lactuca sativa, utilisé comme test de phytotoxicité, ont été réalisées sur les rejets industriels avant et après adsorption. Ces tests ont confirmé l’efficacité du procédé pour diminuer fortement la toxicité du rejet. L’abattement chimique et la réduction de la toxicité ont montré que la bioadsorption sur un matériau non conventionnel peut être une étape de finition intéressante pour la détoxification des rejets industriels.The surface-treatment industry consumes and discharges an important range of chemicals, in particular toxic metals and organics, that are known to be harmful to humans and the environment. Because of more and more stringent regulations, effluents polluted with heavy metals must be treated. There are a variety of treatment processes for wastewater from the surface-treatment industry. In general, conventional treatment and detoxification systems consist mainly of pH adjustments, oxidation of cyanide and reduction of chromium bearing wastewaters, followed by hydroxide precipitation, clarification, and sometimes carbon sorption. However, active carbon technology presents several problems such as rapid saturation and clogging of the reactors. Like ion-exchange resins, their widespread use is restricted due to high cost. For these reasons, most small and medium-size enterprises cannot employ such treatments. Thus, in order to overcome these problems, many attempts have been made to find inexpensive alternative sorbents, which are both effective and acceptable for industrial use. In this study, biosorption with a starch-based cross-linked adsorbent was used for the removal of heavy metals from industrial effluents. The adsorption of metals was studied as a function of contact time, adsorbent mass and pollutant load. The influence of these parameters on the adsorption efficiency was evaluated using a conventional batch method. Batch experiments showed that the material exhibited high sorption capacities toward metal ions, leading to concentrations that were below current regulatory values. Measurements of the germination rate of Lactuca sativa seeds, used as a phytotoxicity test, were carried out on discharged industrial waters before and after the finishing sorption treatment. Germination tests confirmed the ability of the sorption step to radically decrease the effluent toxicity. Both the chemical abatement and toxicity mitigation of waste water showed that biosorption onto a non-conventional sorbent may constitute an interesting additional treatment step for the detoxification of industrial wastewater
Does the wind systematically energize or damp ocean eddies?
Globally, mesoscale ocean eddies are a key component of the climate system, involved in transport and mixing of heat, carbon and momentum. However, they represent one of the major challenges of climate modelling, as the details of their nonlinear dynamics affect all scales. Recent progress analysing satellite observations of the surface ocean and atmosphere has uncovered energetic interactions between the atmospheric wind stress and ocean eddies that may change our understanding of key processes affecting even large-scale climate. Wind stress acts systematically on ocean eddies and may explain observed asymmetry in the distribution of eddies and details of their lifecycle of growth and decay. These findings provide powerful guidance for climate model development
Twenty years of dextrin research: a tribute to Professor Hans Pringsheim (1876–1940)
International audienc
Review: a history of cyclodextrins.
International audienc
Conventional and non-conventional adsorbents for dye removal from aqueous solutions: Introduction
International audienc
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