1,720,961 research outputs found
Development of semi-theoretical light radiation and photosynthetic growth model for the optimal exploitation of wastewaters by microalgae
Full text linkIn the last decade, interest toward the potential application of microalgae has grown considering their potential use in industrial sectors as human nutrition and health, animal feed and biopolymers. Their ability to use light or/and organic carbon as energy source, makes them able to grow in a wide range of conditions. Because of that, the possibility to use alternative nutrients and water sources for their cultivation has been investigated. The microalgal cultivation using wastewaters mixed with synthetic medium might be a good combination that could
reduce costs of water, nutrients and wastewater treatment. Anyway, wastewaters are frequently dark colored and contain toxic compounds that could have a negative impact on microalgal light uptake and metabolism. In this study, an experimental first principles hybrid method for the estimation of microalgal growth in non-transparent media was developed as a guide in the choice of the best formulation of wastewater-based culture media for microalgae. To carry out several experimental runs in parallel with different conditions (dilution of the
wastewater, different light sources, etc.) a cylindrical bubble column PhotoBioReactor (PBR) was adopted. Its simple geometry allows the analysis of inside light fluxes. A non-metabolizable and non-toxic dye, in condition of purely light-radiative growth limitation, was added to the medium mimicking the reduced transparency of wastewaters. As final step to test the model, culture mediums with wastewater addiction were used for microalgal cultivation, showing their nutritive effects on growth
Causality Rules: Performance Feedback on Hierarchically Related Goals and Capital Investment Variability
Full text linkWe extend March and Simon’s (1958) analysis of strategic decisions by distinguishing between two rules for allocating attention – priority versus causality. We develop theory concerning causality rules which have been largely overlooked in prior literature. Specifically, we examine how performance feedback on the intermediate productivity goal and the higher‐order profitability goal independently and jointly influence the variability of firm capital investments. Panel analysis of 2,477 Spanish manufacturing firms reveals that these goals jointly affect the variability of capital investments through both priority and causality attention rules. Our study provides new insights on how firms handle multiple goals, deconstruct performance feedback, and cope with the attentional constraints of bounded rationality
Blending in while standing out : selective conformity and new product introduction in family firms
Full text linkResearch on the conformity-distinctiveness tradeoff in family firms is divided. Examining the product innovations of Spanish manufacturing firms between 1998 and 2012, we hypothesize that family and nonfamily firms conform selectively and are driven by different motivations. Family firms align with their closest peers to avoid social losses while nonfamily firms conform to firms with different attributes to pursue social gains. Moreover, propensity to conform leads to more substantive organizational responses in family firms. We contribute to understanding how family firms navigate the conformity-distinctiveness trade-off, unveil the cognitive dimension of conformity and address the puzzling evidence on family firm innovation
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Multi-component extraction process of high added value compounds from microalgae with supercritical CO2: a technical and economic study
No full textIn this work a multicomponent extraction process of high added value compounds (principally omega-3 fatty acids and carotenoids) from a microalgal matrix (Chlorella vulgaris), using supercritical CO2, was studied. Chlorella's metabolites were analyzed singularly, not as a pseudocomponent, and their affinities to the solvent were explored. The Simplified Broken and Intact Cell model was implemented in order to represent the extraction yields and to define the best conditions in terms of operative variables, ensuring the preservation of the bioactive and thermolabile properties of the extracted metabolites. Moreover, these conditions were chosen also for keeping carotenoids’ solubility in supercritical CO2 very low, in order to separate them (residue stream) from fatty acids (extract stream) without further purification steps. All of these informations were used to implement a simulation of the process, optimizing the daily cycles and increasing the productivity. As last step, calculations of the energy and utilities’ consumption for the estimation of the Operating Expense (OPEX) and Capital Expenditure (CAPEX), as starter point for a future industrial implementation of the process, were carried out
An optimized separation process of microalgal lipidic products by molecular distillation: techno-economic analysis
No full textMicroalgae are a sustainable rich source of high-added value metabolites, as omega-3 and carotenoids, for their ability to grow and accumulate these compounds also in wastewaters or in seawaters. Molecular distillation is a valid techinque respect to conventional distillation for fractionation of these thermosensitive products without affecting their nutritional and biological values. In this work a fractionation process using molecular distillation for separating fatty acids (in part omega-3) as esters and carotenoids from a microalgal lipidic extract, was designed and optimized. A Response Surface Method (RSM) analysis was carried out in order to find the optimal operative conditions of the molecular distiller in terms of temperature, pressure and purification ability. Furthermore, to complete the process scheme, also the design of the other equipments, including in particular the esterification reactor and the dewatering column, was done. In order to complete the feasibility study of the process, an estimation of the Operating Expense (OPEX) and Capital Expenditure (CAPEX), using the results of the simulations in terms of energy and utilities’ consumption, was done. All of these informations, both technical and economical, will be the basis for future industrial implementations of the designed process
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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