204 research outputs found

    Preconditioning for Allen-Cahn variational inequalities with non-local constraints

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    The solution of Allen-Cahn variational inequalities with mass constraints is of interest in many applications. This problem can be solved both in its scalar and vector-valued form as a PDE-constrained optimization problem by means of a primal-dual active set method. At the heart of this method lies the solution of linear systems in saddle point form. In this paper we propose the use of Krylov-subspace solvers and suitable preconditioners for the saddle point systems. Numerical results illustrate the competitiveness of this approach

    Assessment of Heart Disease using Fuzzy Classification Techniques

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    In this paper we discuss the classification results of cardiac patients of ischemical cardiopathy, valvular heart disease, and arterial hypertension, based on 19 characteristics (descriptors) including ECHO data, effort testings, and age and weight. In this order we have used different fuzzy clustering algorithms, namely hierarchical fuzzy clustering, hierarchical and horizontal fuzzy characteristics clustering, and a new clustering technique, fuzzy hierarchical cross-classification. The characteristics clustering techniques produce fuzzy partitions of the characteristics involved and, thus, are useful tools for studying the similarities between different characteristics and for essential characteristics selection. The cross-classification algorithm produces not only a fuzzy partition of the cardiac patients analyzed, but also a fuzzy partition of their considered characteristics. In this way it is possible to identify which characteristics are responsible for the similarities or dissimilarities observed between different groups of patients

    Introducing Semi-Interpenetrating Networks of Chitosan and Ammonium-Quaternary Polymers for the Effective Removal of Waterborne Pathogens from Wastewaters

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    The present work aims to study the influence of ammonium-quaternary monomers and chitosan, obtained from different sources, upon the effect of semi-interpenetrating polymer network (semi-IPN) hydrogels upon the removal of waterborne pathogens and bacteria from wastewater. To this end, the study was focused on using vinyl benzyl trimethylammonium chloride (VBTAC), a water-soluble monomer with known antibacterial properties, and mineral-enriched chitosan extracted from shrimp shells, to prepare the semi-IPNs. By using chitosan, which still contains the native minerals (mainly calcium carbonate), the study intends to justify that the stability and efficiency of the semi-IPN bactericidal devices can be modified and better improved. The new semi-IPNs were characterized for composition, thermal stability and morphology using well-known methods. Swelling degree (SD%) and the bactericidal effect assessed using molecular methods revealed that hydrogels made of chitosan derived from shrimp shell demonstrated the most competitive and promising potential for wastewater (WW) treatment.Introducing Semi-Interpenetrating Networks of Chitosan and Ammonium-Quaternary Polymers for the Effective Removal of Waterborne Pathogens from WastewaterspublishedVersio

    Time-Varying Dark Energy Constraints From the Latest SN Ia, BAO and SGL

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    Based on the latest SNe Ia data provided by Hicken et al. (2009) with using MLCS17 light curve fitter, together with the Baryon Acoustic Oscillation(BAO) and strong gravitational lenses(SGL), we investigate the constraints on the dark energy equation-of-state parameter ww in the flat universe, especially for the time-varying case w(z)=w0+wzz/(1+z)w(z)=w_0+w_zz/(1+z). The constraints from SNe data alone are found to be: (a) (ΩM,w)=(0.358,−1.09)(\Omega_M, w)=(0.358, -1.09) as the best-fit results; (b) (w0,wz)=(−0.73−0.97+0.23,0.84−10.34+1.66)(w_0, w_z)=(-0.73^{+0.23}_{-0.97}, 0.84^{+1.66}_{-10.34}) for the two parameters in the time-varying case after marginalizing the parameter ΩM\Omega_M; (c) the likelihood of parameter wzw_z has a high non-Gaussian distribution; (d) an extra restriction on ΩM\Omega_M is necessary to improve the constraint of the SNe Ia data on the parameters (w0w_0, wzw_z). A joint analysis of SNe Ia data and BAO is made to break the degeneracy between ww and ΩM\Omega_M, and leads to the interesting maximum likelihoods w0=−0.94w_0 = -0.94 and wz=0w_z = 0. When marginalizing the parameter ΩM\Omega_M, the fitting results are found to be (w0,wz)=(−0.95−0.18+0.45,0.41−0.96+0.79)(w_0, w_z)=(-0.95^{+0.45}_{-0.18}, 0.41^{+0.79}_{-0.96}). After adding the splitting angle statistic of SGL data, a consistent constraint is obtained (ΩM,w)=(0.298,−0.907)(\Omega_M, w)=(0.298, -0.907) and the constraints on time-varying dark energy are further improved to be (w0,wz)=(−0.92−0.10+0.14,0.35−0.54+0.47)(w_0, w_z) = (-0.92^{+0.14}_{-0.10}, 0.35^{+0.47}_{-0.54}), which indicates that the phantom type models are disfavored.Comment: 24 pages, 9 figures, to be published in JCA

    PHYMYCO-DB: A curated database for analyses of fungal diversity and evolution.

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    International audienceBackground: In environmental sequencing studies, fungi can be identified based on nucleic acid sequences, using either highly variable sequences as species barcodes or conserved sequences containing a high-quality phylogenetic signal. For the latter, identification relies on phylogenetic analyses and the adoption of the phylogenetic species concept. Such analysis requires that the reference sequences are well identified and deposited in public-access databases. However, many entries in the public sequence databases are problematic in terms of quality and reliability and these data require screening to ensure correct phylogenetic interpretation. Methods and Principal Findings: To facilitate phylogenetic inferences and phylogenetic assignment, we introduce a fungal sequence database. The database PHYMYCO-DB comprises fungal sequences from GenBank that have been filtered to satisfy stringent sequence quality criteria. For the first release, two widely used molecular taxonomic markers were chosen: the nuclear SSU rRNA and EF1-a gene sequences. Following the automatic extraction and filtration, a manual curation is performed to remove problematic sequences while preserving relevant sequences useful for phylogenetic studies. As a result of curation, ,20% of the automatically filtered sequences have been removed from the database. To demonstrate how PHYMYCO-DB can be employed, we test a set of environmental Chytridiomycota sequences obtained from deep sea samples. Conclusion: PHYMYCO-DB offers the tools necessary to: (i) extract high quality fungal sequences for each of the 5 fungal phyla, at all taxonomic levels, (ii) extract already performed alignments, to act as 'reference alignments', (iii) launch alignments of personal sequences along with stored data. A total of 9120 SSU rRNA and 672 EF1-a high-quality fungal sequences are now available. The PHYMYCO-DB is accessible through the URL http://phymycodb.genouest.org/

    Prospects for the Improvement of Energy Performance in Agroindustry Using Phase Change Materials

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    This work was partially supported by the Fundação para a Ciência e Tecnologia, UIDB/00066/2020 (CTS – Center of Technology and Systems).The use of Phase Change Materials (PCMs), able to store latent heat, represents an opportunity to improve energy efficiency in the agroindustry by means of thermal energy storage. PCMs provide higher energy density then sensible heat storage mediums, thus paving the way to multiple applications, like supporting the integration of renewables or allowing for new storage architectures, decentralized and directly installed in the chain production equipment, creating e.g. the opportunity to recover and value low-grade operational heat sub-products. Such new and decentralized architecture, not currently applied in agroindustry, is proposed in this work. A chocolate tempering machine using an organic PCM is conceived and analyzed using ANSYS Fluent software for computational fluid dynamics simulations, comparing the main aspects in the storage capacity and discharging process with a conventional sensitive heat storage solution that uses water. PCMs allows improving the stored energy, keeping the chocolate in the working temperature after being tempered for more than four times longer than using only hot water. If the PCMs are charged by renewables, the self-consumption ratio can be improved while providing energy flexibility to the user.authorsversionpublishe

    Redshift of the Einstein Ring in MG1549+305

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    A deep spectrum taken with the Echelle Spectrograph and Imager (ESI) at the Keck II Telescope as part of the Lenses Structure and Dynamics (LSD) Survey reveals the redshifts of the extremely red source of the radio Einstein Ring in the gravitational lens system MG1549+305 (zs=1.170±0.001z_{\rm s}=1.170\pm 0.001) and an intermediate redshift lensed spiral galaxy (zG2=0.604±0.001z_{\rm G2}=0.604\pm 0.001). The source redshift allows us to determine the mass of the SB0 lens galaxy enclosed by the Einstein Radius (R_{\rm E}=1\farcs15\pm0\farcs05) MEM_{\rm E}≡\equivM(<RE)=8.4±0.7×1010h65−1M(<R_{\rm E}) = 8.4\pm0.7\times 10^{10} h_{65}^{-1} M⊙_\odot. This corresponds to a Singular Isothermal Ellipsoid (SIE) velocity dispersion σSIE=214±5\sigma_{\rm SIE}=214\pm5 \kms, in good agreement with the measured stellar velocity dispersion σ=227±18\sigma=227\pm18 \kms (Leh\'ar et al. 1996). The mass-to-light ratio within the Einstein Radius (∼\sim1.4 effective radii) is 10±1h6510\pm1 h_{65} \mlu. This is only marginally larger than typical stellar mass-to-light ratios of local early-type galaxies, indicating that dark matter is not likely to be dominant inside the Einstein Radius.Comment: 4 pages, 3 figures, accepted for publication in MNRA

    The amplitude of mass fluctuations and mass density of the Universe constrained by strong gravitational lensing

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    We investigate the linear amplitude of mass fluctuations in the universe, σ8\sigma_8, and the present mass density parameter of the Universe, Ωm\Omega_\mathrm{m}, from the statistical strong gravitational lensing. We use the two populations of lens halos model with fixed cooling mass scale M_\mathrm{c}=3\times 10^{13}h^{-1}M_{\sun} to match the observed lensing probabilities, and leave σ8\sigma_8 or Ωm\Omega_\mathrm{m} as a free parameter to be constrained by data. Another varying parameter is the equation of state of dark energy ω\omega, and its typical values of -1, -2/3, -1/2 and -1/3 are investigated. We find that σ8\sigma_8 is degenerate with Ωm\Omega_\mathrm{m} in a way similar to that suggested by present day cluster abundance as well as cosmic shear lensing measurements: σ8Ωm0.6≈0.33\sigma_8\Omega_\mathrm{m}^{0.6}\approx 0.33 (Bahcall & Bode\cite{bahcall03a} and references therein). However, both σ8≤0.7\sigma_8\leq 0.7 and Ωm≤0.2\Omega_\mathrm{m}\leq 0.2 can be safely ruled out, the best value is when σ8=1.0\sigma_8=1.0, Ωm=0.3\Omega_\mathrm{m}=0.3 and ω=−1\omega=-1. This result is different from that obtained by Bahcall & Bode (\cite{bahcall03a}), who gives σ8=0.98±0.1\sigma_8 =0.98\pm 0.1 and Ωm=0.17±0.05\Omega_m =0.17\pm 0.05. For σ8=1.0\sigma_8=1.0, higher value of Ωm=0.35\Omega_\mathrm{m}=0.35 requires ω=−2/3\omega=-2/3 and Ωm=0.40\Omega_\mathrm{m}=0.40 requires ω=−1/2\omega=-1/2.Comment: 9 pages, 4 figures, references update
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