608 research outputs found

    VRIO: Static or dynamic?

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    During the 1980s, the principal concern of theorists in what regarded strategic management was linked to the analysis of the external environment. However, many researchers defend that considering the turbulence of today’s business environment with the technology’ advancement, the ever-changing industries and with an ever continuingly-increasing reduction in the time-frame of competitive advantage, a resource-based view has been gaining its own space regarding strategic formulation. Despite of the model’s capability, the theory has received diverse criticism during the last years, which we believe that some of these criticisms deserve to be analyzed. Therefore, the present article intends to illustrate a new theoretical basis for the analysis of the resources and capabilities in order to explain the advantages of applying a conceptual model that articulates the VRIO framework, initially developed by Barney (1991) with a new conceptual model that allow companies to perceive the dynamism of the company’s competitive advantage through the inclusion of the values, dynamic capabilities and governance concepts from the VDS acronym. The article is subdivided into six parts, the first part is referent to the theoretical exploitation of the RBV dematerialized in the creation of the VRIO model. The second part presents the main criticisms existent in the literature regarding the model and its limitations. The third, fourth and fifth parts refer to the approach in order to achieve the articulation between the VRIO model and the three additional parameters. In the sixth part, the new model will be presented and lastly, some considerations will be presented regarding this subject.info:eu-repo/semantics/submittedVersio

    Do Littoral Macrophytes Influence Crustacean Zooplankton Distribution?

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    In a meso-eutrophic reservoir, cladoceran and copepod assemblages were characterised in two sampling sites: One located in the pelagic zone (site 1) and the other in the shallow littoral zone (site 2), the latter colonised by emergent macrophytes. Samples were collected biweekly from June to July 2001 and from May to July 2002 at the two sites. At site 1, crustacean zooplankton samples were obtained by vertical hauls using a Wisconsin type net of 64 mm mesh size. At site 2 several random samples were obtained using a van Dorn bottle. Those samples were pooled together and the total sample was sieved through a 64 mm mesh size. Macrophyte relative abundance for each species was visually estimated. Macrophyte community was composed of Glyceria declinata, Eleocharis palustris and Carex sp. A Mann-Whitney U-test was carried out to test for statistically significant differences between sites, for environmental parameters and crustacean zooplankton species densities. Alona rectangula, Alona costata, Alona quadrangularis and Chydorus sphaericus were only found in littoral samples. Daphnia longispina, Daphnia pulex, Ceriodaphnia pulchella, Bosmina longirostris, Diaphanosoma brachyurum, Copidodiaptomus numidicus, and Acanthocyclops robustus were found at both sites. However, Daphnia and Bosmina densities did not differ significantly between the pelagic and littoral sites. Ceriodaphnia, Diaphanosoma, and C. numidicus densities were significantly higher in the pelagic site, whereas A. robustus densities showed the opposite pattern.En un embalse meso-eutrofico las comunidades de cladóceros y copépodos fueron caracterizadas en dos estaciones de muestreo. Una localizada en la zona pelágica (estación 1) y la otra en la zona litoral (estación 2). Esta última está colonizada por macrofitos emergidos. Los muestreos fueron efectuados quincenalmente de Junio a Julio de 2001 y de Mayo a Julio de 2002 en las dos estaciones. En la estación 1 los muestreos de crustáceos del zooplancton se obtuvieron mediante arrastre vertical utilizando una red tipo Wisconsin de 64 mm de poro. En la estación 2 se realizaron varias muestras aleatorias con una botella tipo van Dorn. Las muestras obtenidas en la estación 2 se juntaron y la muestra total resultante fue filtrada por una red de 64 mm de poro. La abundancia relativa de cada una de las especies de macrófitos fue estimada visualmente. La comunidad de macrófitos está constituida por Glyceria declinata, Eleocharis palustris y Carex sp. Fue realizado el test de U de Mann-Whitney para detectar las diferencias estadísticamente significativas entre las dos estaciones, para los parámetros ambientales y para las densidades de los crustáceos del zooplancton. Alona rectangula, Alona costata, Alona quadrangularis y Chydorus sphaericus se han observado únicamente en los muestreos obtenidos en el litoral. Daphnia longispina, Daphnia pulex, Ceriodaphnia pulchella, Bosmina longirostris, Diaphanosoma brachyurum, Copidodiaptomus numidicus y Acanthocyclops robustus se han encontrado en ambas estaciones, no obstante las densidades de Daphnia y Bosmina no presentan diferencias estadísticamente significativas entre la zona pelágica y la litoral. Las densidades de Ceriodaphnia, Diaphanosoma y C. numidicus fueran significativamente más elevadas en la zona pelágica, mientras que la densidad de A. robustus presentó un patrón opuesto

    Limiting properties in the characterisation of mixed recycled aggregates for use in the manufacture of concrete

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    El objetivo principal de este trabajo de investigación es estudiar las propiedades del árido reciclado mixto para la fabricación de hormigón reciclado en aplicaciones no estructurales. Se ha realizado la caracterización completa de 35 muestras de áridos reciclados mixtos gruesos de distinta calidad, procedentes de 13 plantas de tratamiento diferentes de la geografía española. Se han estudiado las correlaciones que existen entre las diferentes propiedades, en particular, con la absorción de agua, el contenido de sulfatos y la composición. Se propone una clasificación de los áridos reciclados y se limita de forma indicativa el contenido de yeso para que una muestra de árido reciclado mixto cumpla con la limitación del 0,8% de los sulfatos solubles en ácido de la Instrucción EHE-08. Recycling of construction and demolition waste (CDW) has become a widespread concern in Spain for the last years, as a way to preserve natural resources and achieve a better control of waste disposal sites.Specific applications which make use of mixed recycled aggregates are of great importance, as this types of aggregates constitute the majority of the total production. Structural and non-structural concrete is one of the possible applications, being this the main goal of our study. This paper presents a study on the physical and chemical characteristics of mixed recycled aggregates which have been obtained from different CDW treatment plants of Spain. Correlations between the different properties were investigated in order to find criterions of acceptance for recycled aggregates to be used in concrete. The comparison between the properties offers the possibility of pre-selecting a great quantity of mixed recycled aggregates, these being suitable for either structural and non-structural concrete. The determination of water absorption and the gypsum content are good indicators in order to evaluate the quality of the mixed recycled aggregates for its application in the production of concrete

    An annotated checklist of freshwater copepoda (crustacea, hexanauplia) from continental Ecuador and the Galapagos archipelago

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    An annotated checklist of the free-living freshwater Copepoda recorded in different regions in Ecuador (including the Amazon, the Andes, the coastal region, and the Galapagos Islands) is here provided. We revised all published records, critically evaluated the validity of each taxon and provided short taxonomic and biogeographical remarks for each one. A total of 27 taxa have been reported, including species and records at the generic level only. The species and taxa identified only up to the generic level belong to five families and 14 genera. The Cyclopoida is the most diverse group with 16 records belonging to species (or identified to the generic level only) and eight genera, followed by the Harpacticoida with six species, one identification to the generic level only, and four genera, and Calanoida with four species belonging to two genera. A total of 18 taxa are recorded for the Andes. Six have been recorded in the Amazon, two are recorded for the coastal region, and six for the Galapagos. One species is shared between the Amazon and the Andes. One species is shared between the coastal region and the Amazon. Seventeen are only reported from the Andes and four are only reported from the Amazon. At the current status of the knowledge, any attempt to analyze and generalize distributional patterns of copepods in Ecuador is premature due to the scarcity of available information, and evidently there is an urgent need for more extensive field collections. A few working hypothesis for future studies are identified

    a mixed methods study

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    Spatio-temporal water hyacinth monitoring in the lower Mondego (Portugal) using remote sensing data

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    Monitoring invasive plant species is a crucial task to assess their presence in affected ecosystems. However, it is a laborious and complex task as it requires vast surface areas, with difficult access, to be surveyed. Remotely sensed data can be a great contribution to such operations, especially for clearly visible and predominant species. In the scope of this study, water hyacinth (Eichhornia crassipes) was monitored in the Lower Mondego region (Portugal). For this purpose, Sentinel-2 satellite data were explored enabling us to follow spatial patterns in three water channels from 2018 to 2021. By applying a straightforward and effective methodology, it was possible to estimate areas that could contain water hyacinth and to obtain the total surface area occupied by this invasive species. The normalized difference vegetation index (NDVI) was used for this purpose. It was verified that the occupation of this invasive species over the study area exponentially increases from May to October. However, this increase was not verified in 2021, which could be a consequence of the adopted mitigation measures. To provide the results of this study, the methodology was applied through a semi-automatic geographic information system (GIS) application. This tool enables researchers and ecologists to apply the same approach in monitoring water hyacinth or any other invasive plant species in similar or different contexts. This methodology proved to be more effective than machine learning approaches when applied to multispectral data acquired with an unmanned aerial vehicle. In fact, a global accuracy greater than 97% was achieved using the NDVI-based approach, versus 93% when using the machine learning approach (above 93%).This research activity was funded by POCI-FEDER as part of the project “BioComp_2.0—Produção de compostos orgânicos biológicos para o controlo do jacinto de água e para a valorização de subprodutos agropecuários, florestais e agroindustriais” (POCI-01-0247-FEDER-070123).info:eu-repo/semantics/publishedVersio

    Gd(III) chelates as NMR probes of protein-protein interactions. Case study: rubredoxin and cytochrome c3

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    Inorganic Chemistry 50(21):10600-7Two cyclen-derived Gd probes, [Gd-DOTAM](3+) and [Gd-DOTP](5-) (DOTAM = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetamide; DOTP = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis(methylenephosphonate)), were assessed as paramagnetic relaxation enhancement (PRE)-inducing probes for characterization of protein-protein interactions. Two proteins, Desulfovibrio gigas rubredoxin and Desulfovibrio gigas cytochrome c(3), were used as model partners. In a (1)H NMR titration it was shown that [Gd-DOTP](5-) binds to cytochrome c(3) near heme IV, causing pronounced PREs, characterized by line width broadenings of the heme methyl resonances at ratios as low as 0.08. A K(d) of 23 ± 1 μM was calculated based on chemical shift perturbation of selected heme methyl resonances belonging to three different heme groups, caused by allosteric effects upon [Gd-DOTP](5-) binding to cytochrome c(3) at a molar ratio of 2. The other probe, [Gd-DOTAM](3+), caused PREs on a well-defined patch near the metal center of rubredoxin (especially the patch constituted by residues D19-G23 and W37-S45, which broaden beyond detection). This effect was partially reversed for some resonances (C6-Y11, in particular) when cytochrome c(3) was added to this system. Both probes were successful in causing reversible PREs at the partner binding site, thus showing to be good probes to identify partners' binding sites and since the interaction is reversible to structurally characterize protein complexes by better defining the complex interface
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