749 research outputs found

    Nonsingular systems of generalized Sylvester equations: An algorithmic approach

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    We consider the uniqueness of solution (i.e., nonsingularity) of systems of r generalized Sylvester and ⋆-Sylvester equations with n×n coefficients. After several reductions, we show that it is sufficient to analyze periodic systems having, at most, one generalized ⋆-Sylvester equation. We provide characterizations for the nonsingularity in terms of spectral properties of either matrix pencils or formal matrix products, both constructed from the coefficients of the system. The proposed approach uses the periodic Schur decomposition and leads to a backward stable O(n3r) algorithm for computing the (unique) solution

    Development of a nature conservation standard for enhancing biodiversity and marketing in organic farming systems

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    Abstract Organic farms are proven to yield highly beneficial environmental services for nature. But an appreciation of these services by consumers is nearly non-existent. Furthermore the state does not offer sufficient financial support in this field. This has led to the situa-tion that many farms, due to economic constraints, cannot tap their nature conservation potential, even though the will to do so is very high. It is hoped that through the devel-opment of a nature conservation standard for organic farms connected with nature con-servation advisory services and rewarding farmers for facilitating environmental services by marketing organic+biodiversity products, farmers will experience a higher added value. At the same time consumers who purchase these products will be exposed to more information about organic products and their nature conservation effects

    Gut für uns, gut für den Planeten: Gesunde Ernährung und eine geringe Lebensmittelverschwendung können unseren ökologischen Fußabdruck in erheblichem Ausmaß reduzieren

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    Welcher Zusammenhang besteht zwischen unserer täglichen Ernährung und Landnutzungsänderungen hier und anderswo in der Welt? In welchem Maße tragen wir mit unseren Ernährungsgewohnheiten und unserer derzeitigen Verschwendung von Lebensmitteln zum weltweiten Flächenverzehr bei? Ist die Entscheidung, was wir täglich essen bzw. wie viele Nahrungsmittel wir wegwerfen, wichtig für das Klima? Ist gesunde Ernährung gut für die Umwelt und gut für das Klima? Im Rahmen von drei umfassenden Studien (Noleppa und von Witzke, 2011 und 2012) wurde im Auftrag des WWF untersucht, wie sich die Ernährungsgewohnheiten der Deutschen darstellen und wie sich diese auf den Ressourcenverbrauch auswirken. Darüber hinaus wurde anhand von verschiedenen Szenarien analysiert, in wie weit veränderte Ernährungsgewohnheiten den Flächenverbrauch bzw. die Emissionen von Treibhausgasen reduzieren. Im Folgenden sollen ausgewählte Ergebnisse dargestellt werden

    Minas y metalurgia del azogue "El Porvenir" (Mieres-Asturias)

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    La Sociedad Española Minera "El Porvenir" dedicada al beneficio del azogue fue fundada en 1842 y reorganizada en 1859.Tiene su domicilio social en Madrid y en la actualidad explota las minas de cinabrio de "La Peña" y "La Esperanza"

    Toward Solution of Matrix Equation X=Af(X)B+C

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    This paper studies the solvability, existence of unique solution, closed-form solution and numerical solution of matrix equation X=Af(X)B+CX=Af(X) B+C with f(X)=XT,f(X) =X^{\mathrm{T}}, f(X)=Xˉf(X) =\bar{X} and f(X)=XH,f(X) =X^{\mathrm{H}}, where XX is the unknown. It is proven that the solvability of these equations is equivalent to the solvability of some auxiliary standard Stein equations in the form of W=AWB+CW=\mathcal{A}W\mathcal{B}+\mathcal{C} where the dimensions of the coefficient matrices A,B\mathcal{A},\mathcal{B} and C\mathcal{C} are the same as those of the original equation. Closed-form solutions of equation X=Af(X)B+CX=Af(X) B+C can then be obtained by utilizing standard results on the standard Stein equation. On the other hand, some generalized Stein iterations and accelerated Stein iterations are proposed to obtain numerical solutions of equation equation X=Af(X)B+CX=Af(X) B+C. Necessary and sufficient conditions are established to guarantee the convergence of the iterations

    Embedding social inclusiveness and appropriateness in engineering assessment of green infrastructure to enhance urban resilience

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    Urban resilience emerges not only from ‘what’ is done in relation to critical infrastructure systems, but in the ‘how’ of their conception, co-creation and integration into complex socio-ecological-technical systems. For green infrastructure, where ownership and agency may be distributed amongst organisations and diverse communities, inclusiveness and appropriateness require embedding in engineering assessments of green infrastructure and resilience. Through consideration of past, present and future engineering and resilience assessments – from monetising, through greening, to humanising – this paper examines the ways in which GI may be or has already contributed to enhancing urban resilience and types of assessment and indicators that have been or could be used. We suggest that enhancing visibility of the ‘whos’ (individuals, communities) is crucial to fully diversifying assessments. We also suggest some ideas for additional indicators and assert that co-production of future indicators needs to be undertaken with appropriate professionals (e.g. social impact assessment professionals)

    Characterization of Brazilian Syrah winter wines at bottling and after ageing

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    Double pruning extended the harvest season of wine grape (Vitis vinifera L.) to dry winter, enabling production of high quality wines in the southeastern Brazil. Winter harvest allows grapes to fulfill not only technological maturation, but also phenolic ripeness. Winter wines from Syrah grapes harvested from eight vineyards in southeastern Brazil during three harvests were analyzed for their chemical and aromatic composition after bottling and after ageing for 20, 30, and 42 months in bottle. Winter wines have high content of total phenolic compounds, which remained almost constant through ageing, as well as color intensity. Malvidin 3-O-glucoside stood out among anthocyanins, remaining 5-10 % after 39 months of ageing. Moreover, malvidin 3-O-glucoside-pyruvic acid was the main pyranoanthocyanin identified in winter wine. Polymerized pigments index ranged from 54 % at bottling to 80 % after 42 months of ageing. Young winter wines are rich in ester and monoterpene, as well as alcoholic volatile compounds responsible for ethereal, fruity, flowery, fresh and sweet aromas. Aged winter wines showed higher contents of furfural, geranyl ethyl ether, isoamyl decanoate, α-muurolene and α-calacorene, contributing to sweet, fruity and woody aromas. Syrah winter wines are characterized by high content of phenolic compounds and color stability, and keep good sensorial characteristics after ageing in bottle

    Predicting the size and morphology of nanoparticle clusters driven by biomolecular recognition

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    Nanoparticle aggregation is a driving principle of innovative materials and biosensing methodologies, improving transduction capabilities displayed by optical, electrical or magnetic measurements. This aggregation can be driven by the biomolecular recognition between target biomolecules (analytes) and receptors bound onto nanoparticle surface. Despite theoretical advances on modelling the entropic interaction in similar systems, predictions of the fractal morphologies of the nanoclusters of bioconjugated nanoparticles are lacking. The morphology of resulting nanoclusters is sensitive to the location, size, flexibility, average number of receptors per particle f̄, and the analyte-particle concentration ratio. Here we considered bioconjugated iron oxide nanoparticles (IONPs) where bonds are mediated by a divalent protein that binds two receptors attached onto different IONPs. We developed a protocol combining analytical expressions for receptors and linker distributions, and Brownian dynamics simulations for bond formation, and validated it against experiments. As more bonds become available (e.g., by adding analytes), the aggregation deviates from the ideal Bethe's lattice scenario due to multivalence, loop formation, and steric hindrance. Generalizing Bethe's lattice theory with a (not-integer) effective functionality feff leads to analytical expressions for the cluster size distributions in excellent agreement with simulations. At high analyte concentration steric impediment imposes an accessible limit value facc to feff, which is bounded by facc < feff < f̄. A transition to gel phase, is correctly captured by the derived theory. Our findings offer new insights into quantifying analyte amounts by assessing nanocluster size, and predicting nanoassembly morphologies accurately is a first step towards understanding variations of physical properties in clusters formed after biomolecular recognitionThis work has been partially funded by the Spanish Research Agencies (PID2020-117080RB-C51, PDC2021-121441-C21, PCI2019- 103600,CEX2020-001039-S, PID2019-111649RB-I00 PID2020- 117080RB-C53, MDM-2017-0720, RED2018-102626-T) and Comunidad de Madrid (NANOMAGCOST, S2018/NMT-4321). European COST Actions CA17115 (MyWave), and CA17140 (Nano2Clinic) are also acknowledged. ESD thanks Comunidad de Madrid for financial support (PEJ-2017-AI/BMD-7517). Authors thank Dr Patricia Pedraz for carefull acquisition of AFM image
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