496 research outputs found

    Controlled Growth of Dendrimer-Coated Gold Nanoparticles: A Solvent-Free Process in Mild Conditions

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    Monodisperse dendrimer-coated gold nanoparticles with a spherical shape have been obtained by direct reduction of HAuCl4 with sodium borohydride in the presence of dodecanethiol as a stabilizer and subsequent functionalization by ligand exchange reaction with polybenzylic thiolated dendrons. The substitution pattern of the dendrimeric units plays a fundamental role in the rate of the functionalization exchange process and consequently conditions the size and the polydispersity of the NPs obtained. An ulterior growth process occurs by thermal stimuli (150 °C) in a solvent-free environment. This method, carried out in mild conditions, allows the formation of highly monodisperse gold NPs with different sizes for different time reactions, and we discuss the mechanisms involved in this process. Finally, we demonstrate the chemical composition and stability of our compounds by structural, thermal, and chemical characterization of the samples before and after thermal treatment

    Individually-rational collective choice

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    There is a collection of exogenously given socially-feasible sets, and, for each one of them, each individual in a group chooses from an individually-feasible set. The fact that the product of the individually-feasible sets is larger than the socially-feasible set notwithstanding, there arises no conflict between individual choices. Assuming that individual preferences are random, I characterize rationalizable collective choices

    A novel approach to analysing the regimes of temporary streams in relation to their controls on the composition and structure of aquatic biota

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    Gallart Gallego, Francesc et al.Temporary streams are those water courses that undergo the recurrent cessation of flow or the complete drying of their channel. The structure and composition of biological communities in temporary stream reaches are strongly dependent on the temporal changes of the aquatic habitats determined by the hydrological conditions. Therefore, the structural and functional characteristics of aquatic fauna to assess the ecological quality of a temporary stream reach cannot be used without taking into account the controls imposed by the hydrological regime. This paper develops methods for analysing temporary streams' aquatic regimes, based on the definition of six aquatic states that summarize the transient sets of mesohabitats occurring on a given reach at a particular moment, depending on the hydrological conditions: Hyperrheic, Eurheic, Oligorheic, Arheic, Hyporheic and Edaphic. When the hydrological conditions lead to a change in the aquatic state, the structure and composition of the aquatic community changes according to the new set of available habitats. We used the water discharge records from gauging stations or simulations with rainfall-runoff models to infer the temporal patterns of occurrence of these states in the Aquatic States Frequency Graph we developed. The visual analysis of this graph is complemented by the development of two metrics which describe the permanence of flow and the seasonal predictability of zero flow periods. Finally, a classification of temporary streams in four aquatic regimes in terms of their influence over the development of aquatic life is updated from the existing classifications, with stream aquatic regimes defined as Permanent, Temporary-pools, Temporary-dry and Episodic. While aquatic regimes describe the long-term overall variability of the hydrological conditions of the river section and have been used for many years by hydrologists and ecologists, aquatic states describe the availability of mesohabitats in given periods that determine the presence of different biotic assemblages. This novel concept links hydrological and ecological conditions in a unique way. All these methods were implemented with data from eight temporary streams around the Mediterranean within the MIRAGE project. Their application was a precondition to assessing the ecological quality of these streams.The research leading to these results received funding from the European Community’s Seventh Framework Programme (FP7/2007-2011) under grant agreement 211732 (MIRAGE project), as well from the Spanish Government under the RespHimed project (CGL2010-18374) and a research contract (Ram´on y Cajal programme) granted to J. Latron.Peer Reviewe

    Interleukin-8 expression in bronchoalveolar lavage cells in the evaluation of alveolitis in idiopathic pulmonary fibrosis

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    AbstractInterleukin-8 (IL-8) is a neutrophilic chemotactic factor which may have a prominent role in the attraction of neutrophils to the lung in idiopathic pulmonary fibrosis (IPF). The objective of this study was to investigate the usefulness of IL-8 expression in bronchoalveolar lavage (BAL) cells in the evaluation of alveolitis in IPF. We analysed the BAL cell expression of IL-8 by immunocytochemistry in 19 patients with IPF (six smokers, three ex-smokers and ten non-smokers) and in a control group composed of 14 individuals (six smokers, eight non-smokers). In IPF, BAL was performed on both the pulmonary lobe with the most extensive involvement and the one less extensively involved on high-resolution computed tomography (HRCT) scans. The percentages and absolute numbers of BAL IL-8+ macrophages from lobes with the most extensive HRCT scan involvement (36 ± 6% and (6 ± 2 × 104 ml−1) (SE) and from those less extensively involved [26% ± 4% and (6 ± 1) × 104 ml−1] were significantly higher with respect to both those from healthy smokers [17% ± 6% and (7 ± 4) × 104 ml−1] and those from non-smokers [2% ± 1% and (1 ± 0·3) × 104 ml−1] (P=0·005 and P=0·001, respectively), without differences between the two lobes. In contrast, both the proportions and the absolute numbers of BAL neutrophils in IPF were significantly higher in lobes with the most extensively involved HRCT scan in comparison with lobes with the least extensive involvement [13% ± 3%, (3 ± 1) × 104 ml−1 vs. 8% ± 2%, (1 ± 0·3) × 104 ml−1, P=0·05]. Moreover, the numbers of BAL neutrophils, but not those of IL-8+ macrophages, correlated with the extent of total pulmonary HRCT scan abnormalities in the most involved lobe (r=0·64, P=0·04). A correlation between neutrophils and IL-8+ cells was not observed. The results of this study suggest that, in IPF, BAL neutrophilia offers a better description of the disease inflammatory process than the expression of IL-8 in BAL cells

    Anticitrullinated peptide antibodies (ACPA) in the serum of heavy smokers without arthritis - a differential role of associated pulmonary disease?

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    2 páginas, 1 tabla.-- Póster presentado al 5º European Workshop on Immune-Mediated Inflammatory Diseases celebrado en Sitges (Barcelona) del 1 al 3 de Diciembre de 2010.An increased risk of RA has been described in smokers, but only in ACPA-positive RA patients. The frequency of ACPA in serum of heavy smokers is not known.Peer reviewe

    Terrorism and social media: global evidence

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    The study assesses the relationship between terrorism and social media from a cross section of 148 countries with data for the year 2012. The empirical evidence is based on Ordinary Least Squares, Negative Binomial and Quantile regressions. The main finding is that there is a positive relationship between social media in terms of Facebook penetration and terrorism. The positive relationship is driven by below-median quantiles of terrorism. In other words, countries in which existing levels of terrorism are low are more significantly associated with a positive Facebook-terrorism nexus. The established positive relationship is confirmed from other externalities of terrorism: terrorism fatalities, terrorism incidents, terrorism injuries and terrorism-related property damages. The terrorism externalities are constituents of the composite dependent variable

    A meta-analysis of state-of-the-art electoral prediction from Twitter data

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    Electoral prediction from Twitter data is an appealing research topic. It seems relatively straightforward and the prevailing view is overly optimistic. This is problematic because while simple approaches are assumed to be good enough, core problems are not addressed. Thus, this paper aims to (1) provide a balanced and critical review of the state of the art; (2) cast light on the presume predictive power of Twitter data; and (3) depict a roadmap to push forward the field. Hence, a scheme to characterize Twitter prediction methods is proposed. It covers every aspect from data collection to performance evaluation, through data processing and vote inference. Using that scheme, prior research is analyzed and organized to explain the main approaches taken up to date but also their weaknesses. This is the first meta-analysis of the whole body of research regarding electoral prediction from Twitter data. It reveals that its presumed predictive power regarding electoral prediction has been rather exaggerated: although social media may provide a glimpse on electoral outcomes current research does not provide strong evidence to support it can replace traditional polls. Finally, future lines of research along with a set of requirements they must fulfill are provided.Comment: 19 pages, 3 table

    Catálogo de las plantas vasculares de Río Muni (Guinea Ecuatorial): análisis florístico, diversidad, endemicidad y estado de amenaza

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    Se presenta un catálogo actualizado de las plantas vasculares de la región continental de Guinea Ecuatorial (Río Muni). El catálogo es fruto de la compilación de especímenes de herbario (6,850), registros de especies de la literatura botánica (7,985) y bases de datos en línea (10,109 registros de GBIF y 8,897 de RAINBIO). Se elaboró una base de datos de 23,517 registros georreferenciados realizando la actualización nomenclatural y estandarización de los nombres de localidades de todas estas fuentes. El catálogo comprende 2707 taxones (2598 especies, 81 subespecies y 28 variedades) incluidos en 1,020 géneros y 178 familias. El 90.6% de los taxones se consideran nativos, el 1.17% introducidos y el 5.96% naturalizados. Las 10 familias más diversas son Rubiaceae (294 especies), Fabaceae (290), Orchidaceae (168), Poaceae (105), Euphorbiaceae (87), Apocynaceae (85), Cyperaceae (79), Annonaceae (68), Acanthaceae (65) y Melastomataceae (61), que comprenden el 49.22% de las especies de Río Muni. Solo 11 especies pueden considerarse endémicas de Río Muni; este bajo número refleja la ausencia de barreras naturales en el territorio. El número de taxones amenazados (VU, EN y CR) es de 134 (5.02% del total evaluado) de los cuales 43 se encuentran en riesgo de extinción, al estar dentro de las categorías de En Peligro o En Peligro Crítico. Cinco especies restringidas al Golfo de Guinea se consideran amenazadas: tres En Peligro (Grossera angustifolia, Polyscias aequatoguineensis y Rhipidoglossum montealenense), y dos En Peligro Crítico (Asplenium carvalhoanum y Macropodiella uoroensis), por lo que deberían considerarse prioritarias en los planes de gestión y conservación

    The impact of a web-based lifestyle educational program (‘Living Better’) Reintervention on hypertensive overweight or obese patients

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    ‘Living Better’, a self-administered web-based intervention, designed to facilitate lifestyle changes, has already shown positive short-and medium-term health benefits in patients with an obesity–hypertension phenotype. The objectives of this study were: (1) to examine the long-term (3-year) evolution of a group of hypertensive overweight or obese patients who had already followed the ‘Living Better’ program; (2) to analyze the effects of completing this program a second time (reintervention) during the COVID-19 pandemic. A quasi-experimental design was used. We recruited 29 individuals from the 105 who had participated in our first study. We assessed and compared their systolic and diastolic blood pressure (SBP and DBP), body mass index (BMI), eating behavior, and physical activity (PA) level (reported as METs-min/week), at Time 0 (first intervention follow-up), Time 1 (before the reintervention), and Time 2 (post-reintervention). Our results showed significant improvements between Time 1 and Time 2 in SBP (-4.7 (-8.7 to -0.7); p = 0.017), DBP (-3.5 (-6.2 to -0.8); p = 0.009), BMI (-0.7 (-1.0 to -0.4); p 0.24). Implementation of the ‘Living Better’ program maintained positive long-term (3-year) health benefits in patients with an obesity–hypertension phenotype. Moreover, a reintervention with this program during the COVID-19 pandemic produced significant improvements in blood pressure, BMI, eating behavior, and PA. © 2022 by the authors. Licensee MDPI, Basel, Switzerland
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