5,256 research outputs found

    Synthesis and properties of composites of starch and chemically modified natural rubber

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    A means is developed for forming polysaccharide-based composites with useful material properties through use of unmodified and chemically modified natural rubber latex (NRL). Starch was used as a model for polysaccharides. The NRL was modified by grafting with dimethylaminoethyl methacrylate (DMAEMA) to form a latex with cationic water-soluble polymeric “hairs” of polyDMAEMA, which should form hydrogen bonds with starch. Starch solutions, containing 20% glycerol as a film-forming aid, and the modified NRL were mixed and films allowed to form. The unmodified latex acted only as filler in the starch films, but with modified NRL, the mechanical properties of the films were significantly altered. The elastic modulus was greatly decreased and strain at break greatly increased. The glass transition temperature increased from –48°C to –32°C, suggesting significant compatibilization. Freeze-fracture TEM micrographs indicate strong interactions between the surface of the modified NRL and starch. The polyDMAEMA chains are more hydrophilic than the starch, and the addition of grafted latex results in a 20° drop of the water contact angle of the formed film, and a 25% increase of the water absorption compared to the native starch; with unmodified NRL, the opposite effect was observed

    Clément Juglar and Algeria: three pillars of modern anti-colonial criticism

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    The objective of this paper is to recall the forgotten opposition of Clément Juglar to the colonization of Algeria, the originality of this position, and his contributions to the genesis of analysing colonial institutions. Juglar was not a theoretician of colonialism, but a liberal economist who rejected the process of colonization on economic grounds. This paper provides evidence that conventional wisdom on French colonialism is indebted to his work. The issues of capital returns in the colonies, French colonialism as mercantilism and protectionism, and the role of colonial institutions in economic development were all addressed by Juglar. He identified property rights and colonial institutions as central issues in his explanation of the predictable failure of colonialism, and in doing so he can be regarded as a forerunner of neo-institutionalist analysis of colonialism

    Centerline Depletion in Direct-Chill Cast Aluminum Alloys: The Avalanche Effect and Its Consequence for Turbulent Jet Casting

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    Avalanche dynamics of sedimenting grains in direct-chill casting of aluminum ingots is investigated as a primary driving force for centerline segregation. An analytical model predicting the importance of avalanche events as a function of casting parameters is proposed and validated with prior art results. New experimental results investigating the transient and steady-state centerline segregation of DC casting with a turbulent jet are reported

    Analysis of the Usability of Automatically Enriched Cultural Heritage Data

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    This chapter presents the potential of interoperability and standardised data publication for cultural heritage resources, with a focus on community-driven approaches and web standards for usability. The Linked Open Usable Data (LOUD) design principles, which rely on JSON-LD as lingua franca, serve as the foundation. We begin by exploring the significant advances made by the International Image Interoperability Framework (IIIF) in promoting interoperability for image-based resources. The principles and practices of IIIF have paved the way for Linked Art, which expands the use of linked data by demonstrating how it can easily facilitate the integration and sharing of semantic cultural heritage data across portals and institutions. To provide a practical demonstration of the concepts discussed, the chapter highlights the implementation of LUX, the Yale Collections Discovery platform. LUX serves as a compelling case study for the use of linked data at scale, demonstrating the real-world application of automated enrichment in the cultural heritage domain. Rooted in empirical study, the analysis presented in this chapter delves into the broader context of community practices and semantic interoperability. By examining the collaborative efforts and integration of diverse cultural heritage resources, the research sheds light on the potential benefits and challenges associated with LOUD.Comment: This is the preprint version of a chapter submitted to be included in the book "Decoding Cultural Heritage: a critical dissection and taxonomy of human creativity through digital tools", to be published by Springer Nature. The chapter is currently undergoing peer review for potential inclusion in the boo

    Convergence of a misanthrope process to the entropy solution of 1D problems

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    International audienceWe prove the convergence, in some strong sense, of a Markov process called "a misanthrope process" to the entropy weak solution of a one-dimensional scalar nonlinear hyperbolic equation. Such a process may be used for the simulation of traffic flows. The convergence proof relies on the uniqueness of entropy Young measure solutions to the nonlinear hyperbolic equation, which holds for both the bounded and the unbounded cases. In the unbounded case, we also prove an error estimate. Finally, numerical results show how this convergence result may be understood in practical cases

    Simulation des transferts rĂ©actifs multi-constituants au sein des lits d’infiltration percolation – évaluation des capacitĂ©s d’oxygĂ©nation

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    L’assainissement des eaux usĂ©es par infiltration percolation appartient Ă  la filiĂšre de traitement des rejets polluants Ă  cultures fixĂ©es. Dans un contexte gĂ©ographique spĂ©cifique et pour une population avoisinant 500 Ă  1 000 Ă©quivalents habitants, elle paraĂźt bien indiquĂ©e. FiliĂšre dite rustique, elle n’en est pas moins complexe. L’objectif de cette Ă©tude est de contribuer, Ă  travers une simulation numĂ©rique, Ă  la comprĂ©hension des phĂ©nomĂšnes physiques et biochimiques qui s’établissent au sein d’un lit d’infiltration percolation. Les aspects essentiels Ă  l’activitĂ© bactĂ©rienne que sont l’hydrodynamique du milieu poreux, le dĂ©veloppement de la biomasse active, le transport, la consommation et les transferts d’oxygĂšne y sont abordĂ©s. À travers des essais d’une vĂ©rification mĂ©thodique du modĂšle effectuĂ©e Ă  partir des solutions analytiques, il ressort principalement que la dispersion hydrodynamique et le taux de dĂ©gradation ont des effets contraires sur le rendement d’abattement des charges polluantes. En outre, un rĂ©sultat significatif obtenu est la comparaison qualitative et quantitative des apports convectifs et diffusifs en oxygĂšne au sein des lits d’infiltration percolation qui sont Ă  aĂ©ration naturelle.Wastewater sanitation using infiltration/percolation is part of an approach that uses attached microorganisms to treat pollutant loads. It appears suitable for a specific geographical context, and for population equivalents of approximately 500-1000 people. The aim of this study was to improve, by means of a numerical simulation, the understanding of certain physical and biochemical phenomena observed within an infiltration/percolation bed. All the aspects essential to bacterial activity are examined, including: the hydrodynamics of the porous media; the development of an active biomass; transport; and oxygen transfer and consumption. The latter are of paramount importance in non-saturated porous media, where significant aeration can take place, whereas in saturated soils and aquifers containing nitrogenous and organic compounds, the oxygen in water is rapidly consumed.The model we have formulated includes seven equations, which describe macroscopic transport, and are coupled and non-linear. The terms “wells/sources” are functions of unknown variables. The resolution of the equations, obtained after discretization of the equations using Euler’s finite difference method, was performed using Thomas’ algorithm and Fortran 95 programming. We used an innovative approach: analytical solutions developed for saturated porous media were modified to take into account a heterogeneous flow field in a non-saturated porous medium. In a systematic approach, we tested two problems that are part of a gradual verification process: one-dimensional convection-dispersion solute without a kinetic reaction; one-dimensional solute with a first-order decay.The code we have developed insures a very good approximation of the solute transport within a non-saturated porous medium. For a given rate of flow and a given supply period, the greater the dispersion, the quicker the solute will become homogeneous. In other words, a very high dispersion will induce a very low residence time for the solute within the medium. In wastewater treatment within sand beds, the residence time or contact period between the pollutant matter transported by the effluent and the purifying biomass attached to the support is thus a parameter that is linked to the dispersion of the effluent within the medium. It also appears that the reduction in pollutant load is optimized within a biofilm with a high degradation rate, and for an effluent with a low dispersion coefficient. This result is coherent with the link between dispersion and residence time of the effluent in the system.We also examined the impact that the hydraulic load and the substrate content in the effluent have on the oxygenation capacities of a filtering mass. A qualitative and quantitative analysis of the incoming oxygen flow was performed. Thus we show that, at the beginning of the supply period, convection is more influential than diffusion. We also present several results from the simulations of substrate reduction profiles, which were very closely linked to oxygen content profiles. Thus we observed a rapid decrease in oxygen content due to intensive bacterial activity in the upper part of sand filters, followed by an increase in oxygen towards the bottom of the filter due to the absence of substrate. The main conclusion of this part of the study was that in order to optimize the ability for oxygenation within infiltration/percolation beds, it would be preferable to connect them to the separate sewer networks, which yield more concentrated effluents than do combined sewer networks

    A multi-site, double-blind, placebo-controlled pilot clinical trial to evaluate the efficacy of buspirone as a relapse-prevention treatment for cocaine dependence

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    Objective—To evaluate the potential efficacy of buspirone as a relapse-prevention treatment for cocaine dependence. Method—A randomized, double-blind, placebo-controlled, 16-week pilot trial conducted at six clinical sites between August 2012 and June 2013. Adult crack cocaine users meeting DSM-IVTR criteria for current cocaine dependence scheduled to be in inpatient/residential substance use disorder (SUD) treatment for 12–19 days when randomized, and planning to enroll in local outpatient treatment through the end of the active treatment phase were randomized to buspirone titrated to 60 mg/day (n=35) or to placebo (n=27). All participants received psychosocial treatment as usually provided by the SUD treatment programs in which they were enrolled. Outcome measures included maximum days of continuous cocaine abstinence (primary), proportion of cocaine use days, and days-to-first-cocaine-use during the outpatient treatment phase (study weeks 4–15) as assessed by self-report and urine drug screens. Results—There were no significant treatment effects on maximum continuous days of cocaine abstinence or days to first cocaine use. In the females (n=23), there was a significant treatment-bytime interaction effect (X2 (1)=6.06, p=.01), reflecting an increase in cocaine use by the buspirone, relative to placebo, participants early in the outpatient treatment phase. A similar effect was not detected in the male participants (n=39; X2 (1)=0.14, p=.70). Conclusions—The results suggest that buspirone is unlikely to have a beneficial effect on preventing relapse to cocaine use and that buspirone for cocaine-dependent women may worsen their cocaine-use outcomes. Trial Registration—Clinical Trials.gov http://www.clinicaltrials.gov; Identifier: NCT0164115

    The French intelligence act : resonances with the USA patriot act

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    International audienceThis paper is a study in political philosophy. In the wake of the January 2015 terrorist attacks in Paris, the French parliament adopted an Intelligence Act. Some considered the Act, passed in May and June of the same year, balanced, justified, and necessary. Others rejected it as an ill-conceived erosion of freedom. Does this Act blatantly undermine the democratic balance between the need for security and the demand for civil rights and liberties? The public might have expected the French Intelligence Act of 2015 to give rise to a serious, frank, and open debate about the means for combating terrorism without imposing measures that appear detrimental to citizen privacy. Instead, on July 23, just months after the terrorist attacks, the Constitutional Council, which François Hollande, the President of the Republic, had asked to convene about the constitutionality of this law, delivered its verdict: the Intelligence Act in no way violates the principles of the Republic. Some compare the situation in France to that in the United States in 2001, when a set of emergency laws under the acronym USA PATRIOT Act were hastily promulgated several weeks after the criminal attacks of September 11, 2001. Is the Intelligence Act in France essentially a French Patriot Act

    Origin of fluids in iron oxide-copper-gold deposits: constraints from ÎŽ 37Cl, 87Sr/86Sri and Cl/Br

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    The origin of the hypersaline fluids (magmatic or basinal brine?), associated with iron oxide (Cu-U-Au-REE) deposits, is controversial. We report the first chlorine and strontium isotope data combined with Cl/Br ratios of fluid inclusions from selected iron oxide-copper-gold (IOCG) deposits (Candelaria, RaĂșl-Condestable, Sossego), a deposit considered to represent a magmatic end member of the IOCG class of deposit (Gameleira), and a magnetite-apatite deposit (El Romeral) from South America. Our data indicate mixing of a high ÎŽ 37Cl magmatic fluid with near 0‰ ÎŽ 37Cl basinal brines in the Candelaria, RaĂșl-Condestable, and Sossego IOCG deposits and leaching of a few weight percent of evaporites by magmatic-hydrothermal (?) fluids at Gameleira and El Romeral. The Sr isotopic composition of the inclusion fluids of Candelaria, RaĂșl-Condestable, and El Romeral confirms the presence of a non-magmatic fluid component in these deposits. The heavy chlorine isotope signatures of fluids from the IOCG deposits (Candelaria, RaĂșl-Condestable, Sossego), reflecting the magmatic-hydrothermal component of these fluids, contrast with the near 0‰ ÎŽ 37Cl values of porphyry copper fluids known from the literature. The heavy chlorine isotope compositions of fluids of the investigated IOCG deposits may indicate a prevailing mantle Cl component in contrast to porphyry copper fluids, an argument also supported by Os isotopes, or could result from differential Cl isotope fractionation processes (e.g. phase separation) in fluids of IOCG and porphyry Cu deposit
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