56 research outputs found

    Antimicrobial activities of the bacteriocin-like substances produced by lactic acid bacteria isolated from Moroccan dromedary milk

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    A total of 450 different colonies, isolated from 25 samples of dromedary milk collected from Laâyoune region of Morocco, were tested for antimicrobial compounds production. Out of these, 30 were determined to be lactic acid bacteria (LAB) and able to inhibit the growth of the indicator strain Listeria innocua CECT 4030. Seven isolates were selected by the large and clear zones of inhibition when tested by the agar well diffusion assay. They were classified by phenotypic and biochemical analysis as two Enterococcus durans (E204 and E214), two Lactococcus lactis (R75 and R76), one Enterococcus faecium R111, one Lactococcus cremoris R112 and one Enterococcus avium R122. Their antimicrobial compounds were detected in cell-free culture supernatant fluids under conditions that eliminate acid and hydrogen peroxide inhibition. The antimicrobial activity was altered after treatment with trypsin, -chymotrypsin, pepsin or papain which confirms the proteinaceous nature of the inhibition. It was heat stable even at autoclaving temperature (121°C for 15 min) and also active over a wide pH range (2 to 10). This fact suggests that bacteriocin-like produced by the seven LAB strains may find application as biopreservatives in food products.Key words: Dromedary milk, lactic acid bacteria, bacteriocin-like substances, antimicrobial activity

    Use of the Sentinel‐2 and Landsat‐8 Satellites for Water Quality Monitoring: An Early Warning Tool in the Mar Menor Coastal Lagoon

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    During recent years, several eutrophication processes and subsequent environmental crises have occurred in Mar Menor, the largest hypersaline coastal lagoon in the Western Mediterranean Sea. In this study, the Landsat‐8 and Sentinel‐2 satellites are jointly used to examine the evolution of the main water quality descriptors during the latest ecological crisis in 2021, resulting in an important loss of benthic vegetation and unusual mortality events affecting different aquatic species. Several field campaigns were carried out in March, July, August, and November 2021 to measure water quality variables over 10 control points. The validation of satellite biogeochemical variables against on‐site measurements indicates precise results of the water quality algorithms with median errors of 0.41 mg/m3 and 2.04 FNU for chlorophyll‐a and turbidity, respectively. The satellite preprocessing scheme shows consistent performance for both satellites; therefore, using them in tandem can improve mapping strategies. The findings demonstrate the suitability of the methodology to capture the spatiotemporal distribution of turbidity and chlorophyll‐a concentration at 10– 30 m spatial resolution on a systematic basis and in a cost‐effective way. The multitemporal products allow the identification of the main critical areas close to the mouth of the Albujon watercourse and the beginning of the eutrophication process with chlorophyll‐a concentration above 3 mg/m3. These innovative tools can support decision makers in improving current monitoring strategies as early warning systems for timely assistance during these ecological disasters, thus preventing detrimental conditions in the lagoon.0,64

    Macrofauna de invertebrados del Cretácico superior de la Depresión Central Asturiana

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    Se reporta y comenta la fauna de inocerámidos, rudistas, ammonites, braquiópodos y equmnidos recogida y localizada en yacimientos o series estratigráficas de detalle, durante los trabajos de campo de la tesis doctoral del primero de los autores (E.B.) sobre los seláceos del Cretácico de Asturias. La distribución, principalmente de inocerámidos y ammonites, permite identificar el Cenomaniense superior y el Turoniense inferior y medio. Se han reconocido rudistas del Turoniense superior y del Coniaciense, braquiópodos del Cenomaniense y del Santoniense inferior y un registro relativamente rico y variado de equínidos desde el Cenomaniense hasta el Coniaciense.The fauna collected and located on fossil localities or stratigraphical profiles, during the field work of the first author's doctoral thesis on the Cretaceous selachians from Asturias, is reported and commented. It includes inoceramids, rudists, ammonoids, brachiopods and echinoids. Distribution of, mainly inoceramids and ammonoids, allowed to identify the Upper Cenomanian and the Lower and Middle Turonian. LateTuronian and Coniacian rudists have been recognized, as well as Cenomanian and lower Santonian brachiopods and a quite rich and diversified record of echinoids ranging from Cenomanian to Coniacian

    La secuencia magmática Jurásico Superior-Cretácico Superior en la Cordillera Central, República Dominicana: sección cortical de un arco-isla intraoceánico.

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    The Late Jurassic-Late Cretaceous magmatic sequence exposed in the central-western sector of the Cordillera Central Dominican Republic, can be divided in five main lithostratigraphic units formed by plutonio, volcanic, volcanoclastic and sedimentary rocks. All rocks have suffered very heterogeneous ductile deformation and low-grade metamorphism with magmatic textures often preserved. From bottom to top, this magmatic sequence is made up of:: (1) Loma Caribe serpentinized peridotites, (2) the N-MORB volcano-plutonic assemblage of El Aguacate, of ophiolitic affinity, (3) the Duarte Complex oceanic plateau, (4) the arc-related volcanic and volcano-sedimentary sequence of the Tireo Formation, intruded by the Loma de Cabrera Batolith, and (5) the massive basaltic flows of Peña Blanca y Nalga de Maco. It is suggested that the magmatic sequence represents the crustal section of an intra-oceanic island arc, which was built onto a proto-caribbean oceanic crust and an overlying Lower Cretaceous oceanic plateau. The sequence is overlain by Upper Cretaceous basalts of the Caribbean oceanic plateau and limestones

    Volcanism and climate change as drivers in Holocene depositional dynamic of Laguna del Maule (Andes of central Chile – 36° S)

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    Late Quaternary volcanic basins are active landscapes from which detailed archives of past climate and seismic and volcanic activity can be obtained. A multidisciplinary study performed on a transect of sediment cores was used to reconstruct the depositional evolution of the high-elevation Laguna del Maule (LdM) (36∘ S, 2180 m a.s.l., Chilean Andes). The recovered 5 m composite sediment sequence includes two thick turbidite units (LT1 and LT2) and numerous tephra layers (23 ash and 6 lapilli). We produced an age model based on nine new 14C AMS dates, existing 210Pb and 137Cs data, and the Quizapú ash horizon (1932 CE). According to this age model, the relatively drier Early Holocene was followed by a phase of increased productivity during the mid-Holocene and higher lake levels after 4.0 ka cal BP. Major hydroclimate transitions occurred at ca. 11, 8.0, 4.0 and 0.5 ka cal BP. Decreased summer insolation and winter precipitation due to a southward shift in the southern westerly winds and a strengthened Pacific Subtropical High could explain Early Holocene lower lake levels. Increased biological productivity during the mid-Holocene (∼8.0 to 6.0 ka cal BP) is coeval with a warm–dry phase described for much of southern South America. Periods of higher lake productivity are synchronous to a higher frequency of volcanic events. During the Late Holocene, the tephra layers show compositional changes suggesting a transition from silica-rich to silica-poor magmas at around 4.0 ka cal BP. This transition was synchronous with increased variability of sedimentary facies and geochemical proxies, indicating higher lake levels and increased moisture at LdM after 4.0 ka cal BP, most likely caused by the inception of current El Niño–Southern Oscillation and Pacific Decadal Oscillation (ENSO–PDO) dynamics in central Chile.Postprin

    VISUAL PPINOT: A Graphical Notation for Process Performance Indicators

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    Process performance indicators (PPIs) allow the quantitative evaluation of business processes, providing essential information for decision making. It is common practice today that business processes and PPIs are usually modelled separately using graphical notations for the former and natural language for the latter. This approach makes PPI definitions simple to read and write, but it hinders maintenance consistency between business processes and PPIs. It also requires their manual translation into lower-level implementation languages for their operationalisation, which is a time-consuming, error-prone task because of the ambiguities inherent to natural language definitions. In this article, Visual ppinot, a graphical notation for defining PPIs together with business process models, is presented. Its underlying formal metamodel allows the automated processing of PPIs. Furthermore, it improves current state-of-the-art proposals in terms of expressiveness and in terms of providing an explicit visualisation of the link between PPIs and business processes, which avoids inconsistencies and promotes their co-evolution. The reference implementation, developed as a complete tool suite, has allowed its validation in a multiple-case study, in which five dimensions of Visual ppinot were studied: expressiveness, precision, automation, understandability, and traceability

    Negative responses of highland pines to anthropogenic activities in inland Spain: a palaeoecological perspective

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    Palaeoecological evidence indicates that highland pines were dominant in extensive areas of the mountains of Central and Northern Iberia during the first half of the Holocene. However, following several millennia of anthropogenic pressure, their natural ranges are now severely reduced. Although pines have been frequently viewed as first-stage successional species responding positively to human disturbance, some recent palaeobotanical work has proposed fire disturbance and human deforestation as the main drivers of this vegetation turnover. To assess the strength of the evidence for this hypothesis and to identify other possible explanations for this scenario, we review the available information on past vegetation change in the mountains of northern inland Iberia. We have chosen data from several sites that offer good chronological control, including palynological records with microscopic charcoal data and sites with plant macro- and megafossil occurrence. We conclude that although the available long-term data are still fragmentary and that new methods are needed for a better understanding of the ecological history of Iberia, fire events and human activities (probably modulated by climate) have triggered the pine demise at different locations and different temporal scales. In addition, all palaeoxylological, palynological and charcoal results obtained so far are fully compatible with a rapid human-induced ecological change that could have caused a range contraction of highland pines in western Iberia

    Late Ordovician glaciomarine sediments from the Cantabrian Zone (NW Spain)

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    4 páginas, 5 figuras.-- Trabajo presentadpo en la 40ª Sesión Científica, León, 2006.Preliminary studies of some stratigraphic sections spanning the Ordovician-Silurian boundary in the southern Cantabrian Zone (Iberian Massif, NW Spain) demonstrate the existence of a record of Hirnantian glaciomarine diamictites and shallow-water quartzites in at least three localities, situated in the Bodón nappe. These rocks, evidenced for the first time in the Cantabrian Zone, are probably related to the infilling of a paleorelief, scoured in the Barrios Formation during the Late Ordovician glaciation. The occurrence of an ubiquitous quartzite unit, generally related to the Ordovician-Silurian boundary in most parts of northern Gondwana, is now extended to the outcrops here analyzed. The Hirnantian quarzite probably occurs in additional areas of the Bodón and Correcilla nappes, where its location and significance might be underestimated, and described as the uppermost part of the Barrios Formation (Middle Cambrian to Arenigian). The same quartzite is probably recognized in the areas with volcanic necks within the Barrios Formation, and also in its stratotype, in which a latest Ordovician/earliest Silurian quartzite overlies unconformably on Middle Ordovician shales.Esta nota es una contribución al proyecto 503 del Programa Internacional de Geociencias (IUGS-UNESCO) y se inscribe en las actividades del Grupo de Precámbrico y Paleozoico perigondwánico de la Universidad Complutense de Madrid.Peer reviewe
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