3,560 research outputs found
Role of growth factors in the pathogenesis of tissue fibrosis in systemic sclerosis.
The most severe clinical and pathologic manifestations of systemic sclerosis (SSc) are the result of a fibrotic process characterized by the excessive and often progressive deposition of collagen and other connective tissue macromolecules in skin and numerous internal organs. The mechanisms involved in the initiation and progression of the remarkable fibrotic process in SSc remain largely unknown. Extensive recent studies have indicated that a variety of polypeptide growth factors play a crucial role in this process. The most commonly implicated growth factors include transforming growth factor beta (TGF-β), connective tissue growth factor (CTGF), platelet derived growth factor (PDGF), and vascular endothelial growth factor (VEGF). Here, the experimental evidence supporting the participation of various growth factors in the pathogenesis of the fibrotic process in SSc and the molecular mechanisms involved will be reviewed
Digital Social Innovation in Latin America: A Qualitative Comparative Analysis Research in Progress
Governments are under increasing pressure to meet the Social Development Goals (SDG) by 2030. Digital social innovation has been perceived as an important strategy to address several of the social and environmental needs of developing countries, especially Latin America. Digital social innovation results from the digitalization of resources, capabilities, processes, products, services, and business models with the goal of addressing a social or environmental need. Little is known about the factors that promote the success of these business initiatives in Latin America. In this paper, we analyzed 100 companies that developed and commercialized these initiatives and identified 4 general factors that might influence the success of these initiatives. Applying fsQCA and as preliminary results, we found that the prominence of the company, the type of technology used in the service or product offered, and funds raised are key factors to promote digital social innovation initiatives that are financially sustainable and socially scalable
Biomarkers in systemic sclerosis.
Systemic sclerosis is an autoimmune inflammatory disorder of unknown etiologycharacterized b y pronounced fibroproliferative alterations in the microvasculature, and frequent cellular and humoral immunity abnormalities, culminating in a severe and often progressive fibrotic process. Numerous biomarkers reflecting the three main pathogenetic mechanisms in systemic sclerosis have been described; however, aside from several disease-specific autoantibodies, other biomarkers have not been thoroughly validated and require further study. Thus, there is an unmet need for validated biomarkers for diagnosis, disease classification, and evaluation of organ involvement and therapeutic response in systemic sclerosis
Patrones composicionales de hierbas ruderales en Santiago, Chile
Fragmentation of the natural environment is a consequence of urbanisation. It impacts the biodiversity of native flora thatcharacterises a region. This study focused on characterising the diversity, composition and distribution of native and alienruderal species present in different suburbs of Santiago de Chile. We found that plant assemblages of ruderal species werecharacterised by a higher proportion of alien species (69 taxa), whose original distribution corresponds to the MediterraneanBasin (46 taxa), and a low representation of native species (14 taxa). The results show that the spatial distribution of weedswithin Santiago was not random, because two clusters were found based on patterns of compositional similarity. Furtherresearch should be undertaken to determine the cause of this phenomenon that probably obeys historical and ecologicalfactors such as the past use of soils or urban landscape ornamentation programs.La expansión de los centros urbanos tiene como consecuencia la fragmentación de los ambientes naturales y elconsecuente impacto en la biodiversidad de la flora nativa que caracteriza a una región. El presente estudio se enfocó enla caracterización de la diversidad, composición y distribución de especies ruderales nativas e introducidas presentes endiferentes comunas de Santiago de Chile. Se encontró que los ensambles de especies ruderales están dominados por lapresencia de especies introducidas (69 taxa), cuya distribución original corresponde a la Cuenca Mediterránea (46 taxa),con una baja representación de especies nativas (14 taxa). Los resultados indican además que la distribución espacial demalezas en la ciudad de Santiago no es aleatoria, pues dos conglomerados fueron encontrados en función de los patrones desimilitud composicional. Las causas de este fenómeno deben ser investigadas, pero probablemente obedecen a un complejode factores entre los que se pueden mencionar el modo de uso de suelo, y/o programas de ornamentación del paisaje urbano
Measuring the effectiveness of volatility auctions
We propose a method for event studies based on synthetic portfolios that provides a robust data-driven approach to build a credible counterfactual. The method is used to evaluate the effectiveness of volatility auctions using intraday data from the Colombian Stock Exchange. The results indicate that the synthetic portfolio method provides an accurate way to build a credible counterfactual that approximates the behavior of the asset if the auction had not taken place. The main results indicate that the volatility auction mitigates the volatility of the asset, but its effect on liquidity and trading activity is ambiguous at best
Comparison of a Lightweight Experimental Shaker and an Orchard Tractor Mounted Trunk Shaker for Fresh Market Citrus Harvesting
[EN] A designed lightweight experimental shaker successfully used to collect ornamental oranges has been tested to harvest fresh market citrus. The aim of this study was to evaluate the removal efficiency and operational times of this experimental device compared to an orchard trunk shaker. Three different collecting systems were studied. 'Caracara' citrus trees were tested. Removal efficiency, vibration parameters, fruit and tree damages, and fruit quality were measured. A high-speed camera was used to record operational times and determine cumulative removal percentage over vibration time. The canvases on the ground reduced the severe fruit damages but were not useful to protect against light damages. The experimental shaker produced a higher percentage of slightly damaged oranges. No significant differences in removal efficiency were found between the two harvesting systems. However, removal efficiency using the experimental device could be reduced by 40 percent and working time increase by more than 50 percent when access to the main branches was difficult. In agreement with previous results, the curve representing the branch cumulative removal percentage in time followed a sigmoidal pattern. A model was built showing that during the first 5 s more than 50 percent of the fruits were detachedThis research has been fund by the European Agricultural Fund for Rural Development and cofounded by the Ministerio de Agricultura, Pesca y Alimentacion (project GO "Avances tecnologicos para la modernizacion y la sostenibilidad en la produccion de citricos CITRUSTECH").Ortiz Sánchez, MC.; Torregrosa, A.; Castro-García, S. (2021). Comparison of a Lightweight Experimental Shaker and an Orchard Tractor Mounted Trunk Shaker for Fresh Market Citrus Harvesting. Agriculture. 11(11):1-10. https://doi.org/10.3390/agriculture11111092110111
Gaussianization of LA-ICP-MS features to improve calibration in forensic glass comparison
The forensic comparison of glass aims to compare a glass sample of an unknown source with a control glass
sample of a known source. In this work, we use multi-elemental features from Laser Ablation Inductively
Coupled Plasma with Mass Spectrometry (LA-ICP-MS) to compute a likelihood ratio. This calculation is a
complex procedure that generally requires a probabilistic model including the within-source and betweensource variabilities of the features. Assuming the within-source variability to be normally distributed is a
practical premise with the available data. However, the between-source variability is generally assumed to
follow a much more complex distribution, typically described with a kernel density function. In this work,
instead of modeling distributions with complex densities, we propose the use of simpler models and the
introduction of a data pre-processing step consisting on the Gaussianization of the glass features. In this
context, to obtain a better fit of the features with the Gaussian model assumptions, we explore the use of
different normalization techniques of the LA-ICP-MS glass features, namely marginal Gaussianization based
on histogram matching, marginal Gaussianization based on Yeo-Johnson transformation and a more
complex joint Gaussianization using normalizing flows. We report an improvement in the performance of
the Likelihood Ratios computed with the previously Gaussianized feature vectors, particularly relevant in
their calibration, which implies a more reliable forensic glass comparisonThis work has been supported by the Spanish Ministerio de
Ciencia e Innovación through grant PID2021-125943OB-I0
11 NON-RANDOM DISTRIBUTION OF NATURALIZED FLORA IN CHILE Revista Chilena de Historia Natural
Patterns of turnover and floristic similarity show a non-random distribution of naturalized flora in Chile, South America ABSTRACT The current geographical distribution of alien species could be informative of processes involved in the biological invasions facilitated by humans. Because environmental and anthropic factors affect the geographic distribution of alien plants, we hypothesize that naturalized plants have a non-random distribution along extensive geographical ranges. On the basis of a complete and updated database of naturalized plants in Chile, we analyzed their turnover and floristic similarities among regions that encompass a wide latitudinal gradient in South America. Using Moran's index and Mantel's test we characterized the spatial auto-correlation (regional aggregation) and the effect of geographical distance on the index values. Additionally, we used clustering methods and resampling procedures to detect plant assemblages at regional level. Whittaker's index displayed a positive tilt, increasing according to geographical distance and reaching a plateau; conversely, Jaccard's index was negatively associated with geographical distance. Removing the effect of distance, both Whittaker's and Jaccard's values showed no significant trends. Multivariate analysis combined with resampling procedures revealed the existence of three distinctive plant clusters: Northernmost Chile, Centralsouthern Chile, and Southernmost Chile. These clusters are characterized by naturalized plants that are not present in the others. Based on this evidence, we conclude that the set of naturalized plants in Chile exhibits a non-random geographical distribution, displaying an ordered geographical pattern across regions (latitude). We discuss the role of the environmental variables (climate, latitude) and land use post-European colonization as factors in the distributional patterns here documented. Key words: Jaccard's index, Whittaker's index, plant invasions, naturalized plants, similarity, turnover. RESUMEN La distribución geográfica actual de especies exóticas puede ser informativa de los procesos involucrados en las invasiones biológicas facilitadas por humanos. Debido a que los factores ambientales y antrópicos pueden afectar la distribución geográfica de plantas exóticas, hipotetizamos que las plantas naturalizadas deberían exhibir una distribución no aleatoria. Utilizando una actualizada y completa base de datos de la distribución geográfica de plantas naturalizadas en Chile, analizamos los patrones de recambio (índice de Whittaker) y similitud florística (índice de Jaccard) entre regiones, las que cubren un amplio gradiente latitudinal en Sudamérica. Usando el índice de Moran y pruebas de Mantel, caracterizamos el nivel de autocorrelación espacial y el efecto de la distancia geográfica. Además, utilizamos métodos de aglomeración y procedimientos de remuestreo para detectar conglomerados florísticos a nivel regional. El índice de Whittaker mostró una relación positiva y asintótica en función de la distancia geográfica entre regiones; inversamente, el índice de Jaccard mostró una relación negativa con la distancia geográfica. Removiendo el efecto de la distancia, ninguno de los índices mostró tendencia significativa con la distancia geográfica. El análisis de conglomerados reveló la presencia de tres conglomerados florísticos regionales, localizados en el extremo norte, segmento centro-sur y extremo sur de Chile. En base a esta evidencia, concluimos que la distribución geográfica de plantas naturalizadas en Chile se encuentra geográficamente ordenada. Discutimos el presunto papel de la historia humana y el gradiente climático como factores determinantes de este patrón. Palabras clave: índice de Jaccard, índice de Whittaker, invasiones biológicas, plantas naturalizadas, similitud, recambio
Analytical characterisation of oxide dispersion strengthened steels for fusion reactors
Reduced activation ferritic/martensitic and ferritic steels strengthened by a dispersion of oxide nanoparticles have been considered viable structural materials for fusion applications above 550°C. However, the microstructural stability and mechanical behaviour of these steels subjected to the aggressive operating conditions of these reactors are not well known. An accelerated development of these materials is crucial if they are going to be used in future power reactors. Then, it is indispensable to understand their atomic scale evolution under high temperature and irradiation conditions. The present paper reviews how the combination of transmission electron microscopy and atom probe tomography has been successfully applied for the characterisation of these steels at the near atomic scale, to reveal the nanoparticle structure, grain boundary chemistry and void distribution
Earnings management and cultural values
Using theory and empirical data from social psychology to measure for cultural differences between countries, we study the effect of individualism as defined by Hofstede (1980) and egalitarianism as defined by Schwartz (1994, 1999, 2004) on earnings management. We find a significant influence of both cultural measures. In line with Licht et al. (2004), who argue that individualistic societies may be less susceptible to corruption, we find that countries scoring high on individualism tend to have lower levels of earnings management. In addition, we find that egalitarianism, defined as a society's cultural orientation with respect to intolerance for abuses of market and political power, is negatively related with earnings management. Our results are robust to different specifications and controls. The main message of this paper is that besides formal institutions, cultural differences are relevant to explain earnings management behaviour. We think that our work adds to the understanding of the importance of cultural values in managerial behaviour across countries contributing to the literature on earnings management and law and institutions
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