1,212 research outputs found

    Thin film instability with thermal noise

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    We study the effects of stochastic thermal fluctuations on the instability of the free surface of a flat liquid film upon a solid substrate. These fluctuations are represented as a standard Brownian motion that can be added to the deterministic equation for the film thickness within the lubrication approximation. Here, we consider that while the noise term is white in time, it is coloured in space. This allows for the introduction of a finite correlation length in the description of the randomized intermolecular interaction. Together with the expected spatial periodicity of the flow, we find a dimensionless parameter, β\beta, that accounts for the relative importance of the spatial correlation. We perform here the linear stability analysis (LSA) of the film under the influence of both terms, and find the corresponding power spectra for the amplitudes of the normal modes of the instability. We compare this theoretical result with the numerical simulations of the complete non-linear problem, and find a good agreement for early times. For late times, we find that the stochastic LSA predictions on the dominant wavelength remains basically valid. We also use the theoretical spectra to fit experimental data from a nanometric melted copper film, and find the corresponding times of the evolution as well as the values of the parameter, β\beta

    Taxonomic composition and ecological characteristics of the endemic flora of the lower Duero Basin (Iberian Peninsula)

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    The taxonomical composition and an analysis of four ecological characteristics of the 46 endemic species occurring in the lower Duero Basin (CW Iberian Peninsula) have been made. A comparative analysis of the results reveals that this endemic flora does not comply with the general patterns previously observed in other floras. Predominant life forms are hemicryptophytes (43%) and chamaephytes (22%). As far seed-dispersal is concerned, 54% of the endemic species lack any noteworthy adaptative feature. 89% of the endemic species are pollinated by animals (mostly by insects) and only 1 species is dioecious. Following binary classification of the above characteristics have been used to plot statistically significant associations.La composition taxonomique et une analyse de quatre caracteristiques ecologiques des 46 especes endemiques rencontrees dans le bassin inferieur du Duero (CW de Ia Peninsula lberique) ont ete realisees. Une analyse comparative des resultats montre que cette !lore endemique ne correspond pas aux schemas generaux observes precedemment dans d'autres flares. Les formes biologiques predominantes son! les Mmicryptophytes (43%) et les chamephytes (22%). En ce qui conceme le mode de dispersion des diaspores, 54% des especes endemiques son! depourvues de tout aspect adaptatif particulier. 89% des especes endemiques son! pollinisees par des animaux (essentiellement des insectes) et une seule espece est dioique. En se basant sur une classification binaire, les caracteristiques precedentes ont eta utilisees pour representer graphiquement les associations statistiquement significatives.We would like to thank Dr. Tyteca for the translation of the French texts. This research was supported by a grant from Castilla y Leon Autonomous Government (SA 037/02)info:eu-repo/semantics/publishedVersio

    Conservation status of the threatened Iberian Peninsula narrow endemic Antirrhinum lopesianum Rothm. (Scrophulariaceae)

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    Antirrhinum lopesianum Rothm. is a narrow endemic of the Lusitan Duriensean biogeographical sector (central western Spain and north-eastern Portugal). The species is listed as threatened in several Spanish documents, although it does not figure as such in any Portuguese document. This paper provides a detailed study of its distribution, estimates of the sizes of its populations, the threats it faces, and its current conservation status. The total number of individuals thought to exist is only 768, distributed along the valley of the River Duero on the Spanish – Portuguese border (562, 71.2%), and in the Portuguese Sabor River valley (206, 26.8%). The main threat to the species is loss of habitat: about one third of the Iberian populations can be considered threatened; one population containing 37.6% of all these plants (289) is severely threatened. To determine the Area of Occupancy and the Extent of Occurrence, an exhaustive bibliographical survey was carried out, and herbarium specimens deposited in several institutions were revised. It is, therefore, classifiable as Critically Endangered in Portugal and Endangered in Spai

    La relación entre la falta de sueño, el ocio sedentario y el sobrepeso infantil

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    En esta investigación se estudio, a través del path analysis, la relación entre los hábitos de ocio sedentario, sueño y el índice de Masa Corporal (IMC). Participó una muestra de 72 alumnos, 41 chicas y 31 chicos, de cuarto de primaria con una edad comprendida entre los 9 y los 10 años y medio. Para ello se realizó una entrevista individual en la que se preguntaba a los niños los programas que veían cada uno de los días de la semana y los juegos con los que jugaban con la consola y el ordenador. Los resultados pusieron de manifiesto que los niños que duermen menos emplean más tiempo realizando alguna forma de ocio sedentario y que esto se relaciona a su vez con un IMC más elevado. Se discuten las implicaciones sobre el estudio del estilo de vida y sobrepeso infantil.The objective of this research was to analyse the relations between short sleeping, sedentary leisure and childhood overweight using the path analysis. The sample consisted of 72 participants aged 9 to 10 and half years, 41 girls and 31 boys. One individual interview was used in order to evaluate these variables. The results pointed out that participants with short sleeping spent more time watching TV and playing videogames o using computer and in the same way this type of leisure is related with a higher Body Mass Index. The implications on the study of childhood lifestyle and overweight are discussed

    Increased Presentation of Diabetic Ketoacidosis and Changes in Age and Month of Type 1 Diabetes at Onset during the COVID-19 Pandemic in Spain

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    COVID-19; Aparició de la diabetis; Diabetis tipus 1COVID-19; Aparición de diabetes; Diabetes tipo 1COVID-19; Diabetes onset; Type 1diabetesObjective: To assess the impact of the COVID-19 pandemic and lockdown measures on the presenting characteristics (age at diagnosis, severity, monthly distribution) of newly diagnosed type 1 diabetes in Spanish children. Research Design and Methods: An ambispective observational multicenter study was conducted in nine Spanish tertiary-level hospitals between January 2015 and March 2021. Inclusion criteria: new cases of type 1 diabetes in children (0–14 years) recording age, sex, date of diagnosis, presence of diabetic ketoacidosis (DKA) at onset, and severity of DKA. Data were compared before and during the pandemic. Results: We registered 1444 new cases of type 1 diabetes in children: 1085 in the pre-pandemic period (2015–2019) and 359 during the pandemic (2020–March 2021). There was a significant increase in the group aged ≤4 years in the pandemic period (chi-squared = 10.986, df 2, p = 0.0041). In 2020–2021, cases of DKA increased significantly by 12% (95% CI: 7.2–20.4%), with a higher percentage of moderate and severe DKA, although this increase was not significant. In 2020, there was a sharp decrease in the number of cases in March, with a progressive increase from May through November, higher than in the same months of the period 2015–2019, highlighting the increase in the number of cases in June, September, and November. The first three months of 2021 showed a different trend to that observed both in the years 2015–2019 and in 2020, with a marked increase in the number of cases. Conclusions: A change in monthly distribution was described, with an increase in DKA at onset of type 1 diabetes. No differences were found in severity, although there were differences in the age distribution, with an increase in the number of cases in children under 4 years of age

    Monitoring the performance of wastewater treatment plants for organic matter removal using excitation-emission matrix fluorescence

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    This study has assessed the usefulness of excitation-emission matrix fluorescence (EEMF) as a fast and simple analytical technique to track changes in dissolved organic matter (DOM) during the sequence of treatment in wastewater treatment plants (WWTPs). Three different industrial wastewaters and treatment plants have been studied in this work: an industrial park wastewater treated in an independent line at the Burgos WWTP (Spain), a food industry wastewater (crisps and snacks manufacturing) that was treated in a MBR (Membrane Biological Reactor) pilot plant (University of Burgos) and a municipal landfill leachate treated in a physicochemical treatment plant within the same landfill. Removal percentages for the wastewater organic matter at each stage of the treatment plants were successfully obtained by monitoring the main fluorescence peaks: protein-like peaks (tryptophan-like peaks T1, T2 and tyrosine-like peaks B1, B2), humic-like peaks (fulvic-like peak A and humic-like peak C) and microbially-derived peak M. Therefore, EEMF readily allows the assessment of the reactivity of the different types of organic matter towards specific treatments, such as clarification, biodegradation, filtration, etc. Among the wastewaters studied, the food industry wastewater exhibited the greater diversity of fluorescence peaks (B1, B2, T1, T2, A1, A2 and M) whereas the landfill leachate only showed the presence of humic substances (mainly humic-like peak C). This study has demonstrated that EEMF is a useful and user-friendly technique to monitor the performance of wastewater treatment plants for organic matter removal, allowing a rapid response to potential problems in the treatment

    LAL regulators SCO0877 and SCO7173 as pleiotropic modulators of phosphate starvation response and actinorhodin biosynthesis in Streptomyces coelicolor

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    [EN] LAL regulators (Large ATP-binding regulators of the LuxR family) constitute a poorly studied family of transcriptional regulators. Several regulators of this class have been identified in antibiotic and other secondary metabolite gene clusters from actinomycetes, thus they have been considered pathway-specific regulators. In this study we have obtained two disruption mutants of LAL genes from S. coelicolor (Δ0877 and Δ7173). Both mutants were deficient in the production of the polyketide antibiotic actinorhodin, and antibiotic production was restored upon gene complementation of the mutants. The use of whole-genome DNA microarrays and quantitative PCRs enabled the analysis of the transcriptome of both mutants in comparison with the wild type. Our results indicate that the LAL regulators under study act globally affecting various cellular processes, and amongst them the phosphate starvation response and the biosynthesis of the blue-pigmented antibiotic actinorhodin. Both regulators act as negative modulators of the expression of the two-component phoRP system and as positive regulators of actinorhodin biosynthesis. To our knowledge this is the first characterization of LAL regulators with wide implications in Streptomyces metabolismSIThis work was supported by the Spanish Ministerio de Ciencia e Innovación (BIO2007-67585 and BIO2010-19911 to JFA); and the Junta de Castilla y León (Grupo de Excelencia GR117). FPU fellowships of the Ministerio de Ciencia e Innovación (AP2005-3644 to JSA, AP2007-02055 to T.D.P.); a fellowship from the University of León (to SMG); and a contract from the Junta de Castilla y León (E-24-2009-0053914 to CMV). The funders had no role in study design, data collection and analysis, decision to publish, or presentation of the manuscript

    Elucidation of the chemical role of the pyroclastic materials on the state of conservation of mural paintings from Pompeii

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    Pyroclastic strata have always been thought to protect the archaeological remains of the Vesuvian area (Italy), hence allowing their conservation throughout the centuries. In this work, we demonstrate that they constitute a potential threat for the conservation state of the mural paintings of Pompeii. The ions that could be leached from them and the ion‐rich groundwater coming from the volcanic soil/rocks may contribute to salt crystallisation. Thermodynamic modelling not only allowed to predict which salts can precipitate from such leaching events but also assisted the identification of additional sources of sulfates and alkali metals to explain the formation of the sulfates identified in efflorescences from the mural paintings of Pompeii. For the future, fluorine, mainly related to a volcanic origin, can be proposed as a marker to monitor the extent of the impact in the mural paintings of Pompeii in situ
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