3,203 research outputs found
Coherence effects in disordered geometries with a field-theory dual
We investigate the holographic dual of a probe scalar in an asymptotically
Anti-de-Sitter (AdS) disordered background which is an exact solution of
Einstein's equations in three bulk dimensions. Unlike other approaches to model
disorder in holography, we are able to explore quantum wave-like interference
effects between an oscillating or random source and the geometry. In the
weak-disorder limit, we compute analytically and numerically the one-point
correlation function of the dual field theory for different choices of sources
and backgrounds. The most interesting feature is the suppression of the
one-point function in the presence of an oscillating source and weak random
background. We have also computed analytically and numerically the two-point
function in the weak disorder limit. We have found that, in general, the
perturbative contribution induces an additional power-law decay whose exponent
depends on the distribution of disorder. For certain choices of the gravity
background, this contribution becomes dominant for large separations which
indicates breaking of perturbation theory and the possible existence of a phase
transition induced by disorder.Comment: 36 pages, 19 figs, v3 accepted versio
Variable broad lines and outflow in the weak blazar PBC J2333.9-2343
Indexación: Scopus; Scielo.Funding text #1
1Instituto de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso, Gran Bretaña 1111, Playa Ancha, Valparaíso, Chile 2INAF – Istituto di Astrofisica e Planetologia Spaziali di Roma (IAPS-INAF), Via del Fosso del Cavaliere 100, I-00133 Roma, Italy 3INAF – Osservatorio Astronomico di Roma, via Frascati 33, I-00078 Monte Porzio Catone, Italy 4Excellence Cluster Universe, Technische Universität München, Boltzmannstr. 2, D-85748, Garching, Germany 5European Southern Observatory, Karl-Schwarzschild-Str 2, D-85748 Garching b. München, Germany 6Instituto Nacional de Astrofísica, Óptica y Electrónica, Apartado Postal 51-216, 72000 Puebla, México 7Argelander Institute for Astronomy, University of Bonn, Auf dem Hügel 71, D-53121 Bonn, Germany 8International Max Planck Research School of Astronomy and Astrophysics at the Universities of Bonn and Cologne, Auf dem Hügel 69, D-53121 Bonn, Germany 9INAF – Osservatorio di Astrofisica e Scienza dello Spazio, via Gobetti 93/3, I-40129 Bo...View all
Funding text #2
We acknowledge the referee, M. Villar Martín, for her comments and suggestions that helped to improve the paper. This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester, the NASA/IPAC extragalactic database (NED), the STARLIGHT code, and the IRAF software. Based upon observations carried out at the Observatorio Astronómico Nacional on the Sierra San Pedro Mártir (OAN-SPM), Baja California, México. LHG and FP acknowledge the ASI/INAF agreement number 2013-023-R1, LHG partial support from FONDECYT through grant 3170527, MP from ESSTI under the MoST, and from MINECO through research projects AYA2013-42227-P and AYA2016-76682-C3-1-P (AEI/FEDER, UE), LHG and SC from the Spanish grant AYA2013-42227-P, VC by CONACyT research grant 280789, EFJA from the Collaborative Research Center 956, subproject A1, funded by DFG, and GV from the DFG Cluster of Excellence ‘Origin and Structure of the Universe’ (www.universe-cluster.de).PBC J2333.9-2343 is a peculiar active nucleus with two giant radio lobes and a weak blazarlike nucleus at their centre. In this work we show new optical, ultraviolet (UV), and X-ray data taken from the San Pedro Mártir telescope, the New Technology Telescope, NTT/EFOSC2, and the Swift/XRT satellite. The source is highly variable at all frequencies, in particular the strongest variations are found in the broad Hα component with a flux increase of 61±4 per cent between 2009 and 2016, following the X-ray flux increase of 62±6 per cent between 2010 and 2016. We also detected a broad Hβ component in 2016, making the optical classification change from type 1.9 to type 1.8 in 1 yr. We have also detected a broad component of the [OIII]λ5007 line, which is blue-shifted and of high velocity, suggesting an origin from a highly disturbed medium, possibly an outflow. The line flux variability and broad widths are indicative of a jet that is, at least in part, responsible for the ionization of the broad line region (BLR) and narrow line region (NLR). © 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.https://academic.oup.com/mnras/article-abstract/478/4/4634/4999938?redirectedFrom=fulltex
Formal conceptualisation as a basic for a more procedural knowledge management
Knowledge management at an organisational level can only be brought into practice if a corporate memory is defined. Unfortunately, at this moment there is no complete and procedural specification on how to build it. This paper presents a complete and generic knowledge representation scheme that makes it possible to conceptualise/represent the knowledge of any domain in a systematic way, guiding the definition of a corporate memory and allowing us to reach a more procedural level in knowledge management discipline. The conclusions of our study, which follows the generic and formal definition of any conceptualisation, are illustrated by a real project
Brassica oleracea var. costata: comparative study on organic acids and biomass production with other cabbage varieties
BACKGROUND: A study was undertaken to evaluate the effect of agronomic practices, harvesting time and leaf age on the
organic acid composition and biomass production of Brassica oleracea L. var. costata DC (tronchuda cabbage). Samples were
cultivated under eight different fertilisation regimes (two levels each of nitrogen, boron and sulfur, an organic fertiliser and no
fertiliser) and collected at three different times.
RESULTS: Principal component analysis of the data indicated significant differences. Three principal components with an
eigenvalue higher than one accounted for 79.0% of the total variance of the data set. Samples obtained with conventional
fertilisation were characterised by the highest values of fresh weight. External leaves showed higher total organic acid and
malic acid contents than internal leaves,while the latterwere characterised by higher proportions of citric acid. For consecutive
harvests, total organic acid concentration decreased in both external and internal leaves.
CONCLUSION: The use of a conventional fertilisation regime (nitrogen, boron or sulfur) improved the growth of B. oleracea
var. costata without affecting its organic acid profile. However, for consecutive harvests, total organic acid concentration was
observed to decrease independently of the agronomic practices tested. Leaf age influenced the quantitative composition of
organic acids.FC
First Evaluation of Associated Gut Microbiota in Wild Thick-Lipped Grey Mullets (Chelon labrosus, Risso 1827)
This study aimed to characterize the intestinal microbiota of wild thick-lipped grey mullets (Chelon labrosus) and explore its potential functionality on the host. Intestinal contents of anterior and posterior sections from wild fish were collected and DNA was extracted. Subsequently, the V3–V4 regions of 16S rRNA were sequenced using the Illumina technology and results were analyzed by bioinformatics pipeline. The functional profile of the microbial community was analyzed using PICRUSt software. Shannon and Simpson diversity indices were significantly higher in the posterior section of wild specimens. The overall taxonomic composition suggests a certain homogeneity in the anterior section of the intestine and heterogeneity in the posterior section. Due to this, no statistical differences were detected at any level among both intestinal sections. Predicted functions of intestinal microbiota showed the most abundant were those related to amino acid metabolism, carbohydrate metabolism, energy metabolism, membrane transport, and cell replication and repair. Furthermore, the analysis revealed microbial functional genes related to the elimination of environmental toxins.This work was financed by the Project ‘Design and evaluation of probiotics and feed in uncoupled aquaponic system of fishes, plants and microalgae’ (grant #Agl-2017-83260R) granted by Agencia Estatal de Investigación (MINECO, Spanish Government), and by the Project Bluemaro (PID2020 116136 RB100) of the Ministry of Science and Innovation of Spain. Partial funding for open access charge: Universidad de Málag
Sintonización heurística mediante algoritmos genéticos del control de un prototipo de un aerogenerador
[ES] La gran madurez de las energías renovables permite la búsqueda de métodos de control más sofisticados de la mano de la mejora computacional propiciada por los avances tecnológicos. Como resultado, se ha obtenido una mejora en cuanto a especificaciones de las turbinas eólicas y eficiencia en los últimos años. En el presente artículo se diseña un modelo a escala de un aerogenerador el cual incluye dos lazos de control para la estabilización de la potencia extraída; el lazo externo se encarga
de controlar la carga eléctrica del generador, mientras que el lazo interno controla el ángulo de pitch de las palas de la turbina.
El objetivo principal del prototipo es la obtención de un comportamiento análogo al de un aerogenerador convencional, respetando las regiones de operación correspondientes. Partiendo de una sintonización experimental, se optimizan los parámetros del control con ayuda de algoritmos genéticos, dotando de una mayor inteligencia al sistema con la capacidad de adaptarse a distintas condiciones. Finalmente, se obtiene un modelo de turbina eólica capaz de realizar pruebas de algoritmos de control y sirviendo como base para prototipos de aerogeneradores flotantes (FOWT).[EN] The reached maturity of renewable energies allows the application of more sophisticated and efficient control methods due to the computational advances made by the technology. As a result, an improvement in wind turbine specifications and efficiency has been obtained in recent years. In this paper, a wind turbine scale model is designed which includes two control loops for the stabilization of output power: the external loop is responsible of the control of the electrical load of the generator, while the inner loop controls the pitch angle of the turbine blades. The main objective of the prototype is to obtain a behavior analogous to that of a conventional wind turbine, with the corresponding operating regions. Starting from an experimental
tuning, the control parameters are used using genetic algorithms, giving the system greater intelligence and the ability to adapt to different conditions. Finally, a wind turbine model able to testing control algorithms is obtained, serving as a base for floating offshore wind turbine prototypes (FOWT)
Recreational Drugs and the Risk of Hepatocellular Carcinoma
Hepatocellular carcinoma represents an important contributor to the global cancer-related burden, and liver cirrhosis is the main risk factor for its development. Conventional or illegal drug consumption is a potential but infrequent cause of cirrhosis. However, the causal relationship between recreational drugs and the risk of developing liver cancer has not been studied in detail thus far. The aim of this review is to synthesize the available published evidence on legal and illegal recreational drug use and the risk of hepatocellular carcinoma and other liver tumors. Expanding our knowledge about the contributions of these substances to the appearance of liver cancers is important for combatting this preventable cause of cancer.
Abstract
Recreational or aesthetic drug use is a distinctive behavior of humans, principally attested in the last century. It is known that recreational and illegal drugs are major contributors to the universal morbidity rate worldwide. Many of these substances have a well-established hepatotoxic potential, causing acute or chronic liver injury, liver fibrosis and cirrhosis, but their implications for hepatocellular carcinoma or other varieties of liver tumors are little known. In this article, we perform an extensive literature review, aiming to provide updated information about recreational drug use and the risk of developing liver tumors. Khat use and pyrrolizidine alkaloid consumption (present in some natural plants) have been linked to liver cirrhosis. Kava intake is associated with different liver tumors in animal models but not in humans. Cannabis’ potential to accelerate liver fibrosis in chronic hepatitis is controversial according to the existing data. Cigarette smoking is an important contributor to hepatocellular carcinoma, and anabolic androgen steroids are well-defined causes of a variety of liver cancers and other hepatic tumors. (...)This research was supported by grants from Instituto de Salud Carlos III, cofounded by the Fondo Europeo de Desarrollo Regional—FEDER (contract numbers: FIS 21_01248; PI18/00901; UMA18-FEDERJA-193). CIBEREHD is funded by the Instituto de Salud Carlos III (ISCIII). All authors are members of the COST ACTION “CA-17112”, Prospective European Drug-Induced Liver Injury Network, supported by COST (European Cooperation in Science and Technology), www.cost.eu. JMPB holds a Rio Hortega contract from ISCIII. ASZ holds a Jaume Bosch Training Action 2022 from CIBEREHD (ISCIII)
Contribución al estudio palinológico de la familia cruciferae del entorno de Alcalá de Henares (Madrid) y Sigüenza (Guadalajara)
Las características morfológicas y métricas de 24 especies de la familia Cruciferae recolectados en el entorno de Alcalá de Henares (Madrid) y Sigüenza (Guadalajara), han sido analizadas mediante dos diferentes análisis estadísticos: correlación parcial y regresión
múltiple. El dendrograma y la matriz de distancias obtenidas se comparan con Flora Europaea para establecer una relación sistemática polen-especie.
Se propone también por primera vez el término "oblongo".Morphological and metrical of pollens traits of 24 species of Crucijerae from skirts of two villages (Alcala de Henares and Sigüenza, Spain) were analized through two different
statistical analysis: partial correlation and multivariate regression.
The distances matrix and tree were compared with Flora Europaea in order to establish a systematic polle-species relation.
Likewise, the term "oblongo" is firstly proposed
Datos palinológicos de una turbera localizada en el Puerto de Canencia (Madrid)
Se presentan los primeros datos palinológicos obtenidos en el Puerto de Canencia
(Madrid). El estudio de esta zona nos va a permitir por un lado cubrir el vacío existente, en
el sector más oriental del Sistema Central, desde el punto de vista palinolólogico, así como poner de manifiesto la evolución y desarrollo de la vegetación de la zona, caracterizado por
la presencia de géneros de carácter relíctico eurosiberiano.It's presented the first palinologycal datas obtained in the Puerto de Canencia
(Madrid). The study of this zone will let us palliate the actual emptiness, from the
palinologycal point of view, in the most eastern part of the Sistema Central and show the evolution and development of the vegetation in this zone
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