4,657 research outputs found

    Top-antitop resonance searches beyond 1 TeV

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    We perform a general parton level analysis for the search of heavy resonant states in the production of top-antitop pairs at the LHC with an integrated luminosity of 30 fb^-1. We assume the existence of resonances that only couple to quarks and propose kinematic cuts in order to increase the amount of events produced through quark-annihilation. We study the interplay between different variables and their impact on the purity of the selected sample. We make focus on the longitudinal (β\beta) and transverse (pTp_T) momentum of the top-antitop pair, and the scattering angle (θ\theta) in the center of mass reference frame. We observe that β\beta is replaced by θ\theta as a suitable discriminating variable of quark-annihilation processes for invariant masses above 1 TeV. Finally, we illustrate the analysis with a gluon resonance of 1.5 TeV and show the improvement in the sensitivity of the signal when cuts on θ\theta are imposed.Comment: 19 pages and 6 figure

    Using the host immune response to hemorrhagic fever Viruses to understand pathogenesis and improve diagnostics

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    Hemorrhagic fever viruses cause severe infections characterized by a hyperactive immune response that often leads to multiorgan failure and death. Current diagnostic tests are based on detecting viral proteins and nucleic acids in the blood. These are late-stage events during infection, which makes it impossible to perform a diagnosis before they are present in the collected sample. In this thesis, I explore an alternative approach using the transcriptional changes of circulating immune cells during the early stages of infection to identify unique markers of viral infection. The main advantage of this method is that it can be used to identify highly pathogenic viruses before standard detection methods become effective. I initially used RNA sequencing data to compare the host patterns of expression of macaques infected with either Lassa virus or Marburg virus, two related hemorrhagic fever viruses. I identified a set of genes that quickly become upregulated after a viral infection and remain highly expressed throughout the entire disease course, irrespective of the specific virus that caused the infection. I was also able to identify a set of biomarker genes that follow unique patterns of expression depending on the type of infection. I used an independent dataset to validate the potential of these genes to be used as biomarkers of infection. Additionally, I compared these results to the patterns of expression of macaques infected with Ebola virus, looking at multiple experimental conditions, tissues and routes of infection. Finally, I validated the host patterns of expression using two independently generated datasets corresponding to infection by different strains of arenaviruses and filoviruses. Studying the host immune response has the potential to improve the diagnosis of viral hemorrhagic fevers and other diseases. It can also accelerate our efforts to understand the underlying molecular mechanisms that lead to pathogenesis and severe disease

    Editorial

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    Queremos tomar la imagen algo indefinida que ilustra la portada de nuestra tercera entrega como una metáfora para referimos a ese individuo que se apropia de la ciudad, la habita y la marca con su presencia; al ciudadano que, al fin de cuentas, es otra historia, otra sombra, otra mano que trata de alcanzar la porción de esperanza que le corresponde bajo el sol. En esta ocasión iniciamos la hojeada ojeando la ciudad como espacio de comunicación. En el recorrido nos topamos con el cuerpo del desplazado, asumido desde una perspectiva estética; en la Medellín, que en el umbral de siglo recibe a cientos de desarraigados, conviven también los jóvenes construyen su identidad desde la puesta en escena de complejos modos de acción y relación con su espacio y con sus gentes. En las barriadas el álbum familiar testifica el nacimiento del Rock; gracias a ese efectivo dispositivo de memoria, que al hablar de los amigos retrata a toda una generación, se revive la historia y se disparan los recuerdos. Después de la reflexión sobre los desplazados, se da cuenta, entonces, de esas huellas que fueron configurando las culturas juveniles urbanas contemporáneas

    Assessment of mortar evolution in pig slurry by mechanical and ultrasonic measurements

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    This work presents the results obtained in a long-term experiment focused on the study of the evolution of cementitious materials immersed in pig slurry at real conditions. Cement mortars were made with four different cement types and immersed in pig slurry for 48 months. Furthermore, to separate pure hydration process from pig slurry effect, mortar samples were immersed in water for 12 months at laboratory conditions. Compressive strength, X-ray diffraction and ultrasonic measurements were made in all samples. Ultrasonic measurements were made from ultrasonic images obtained from automatic ultrasonic inspections. Use of ultrasonic images has allowed the extraction of information about the state of the studied materials. An empirical relationship between ultrasonic velocity and compressive strength has been obtained and the long-term effect of pig slurry on cementitious materials has been determined

    Opinion mining and sentiment analysis in marketing communications: a science mapping analysis in Web of Science (1998–2018)

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    Opinion mining and sentiment analysis has become ubiquitous in our society, with applications in online searching, computer vision, image understanding, artificial intelligence and marketing communications (MarCom). Within this context, opinion mining and sentiment analysis in marketing communications (OMSAMC) has a strong role in the development of the field by allowing us to understand whether people are satisfied or dissatisfied with our service or product in order to subsequently analyze the strengths and weaknesses of those consumer experiences. To the best of our knowledge, there is no science mapping analysis covering the research about opinion mining and sentiment analysis in the MarCom ecosystem. In this study, we perform a science mapping analysis on the OMSAMC research, in order to provide an overview of the scientific work during the last two decades in this interdisciplinary area and to show trends that could be the basis for future developments in the field. This study was carried out using VOSviewer, CitNetExplorer and InCites based on results from Web of Science (WoS). The results of this analysis show the evolution of the field, by highlighting the most notable authors, institutions, keywords, publications, countries, categories and journals.The research was funded by Programa Operativo FEDER Andalucía 2014‐2020, grant number “La reputación de las organizaciones en una sociedad digital. Elaboración de una Plataforma Inteligente para la Localización, Identificación y Clasificación de Influenciadores en los Medios Sociales Digitales (UMA18‐ FEDERJA‐148)” and The APC was funded by the same research gran

    NGC1277: a massive compact relic galaxy in the nearby Universe

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    As early as 10 Gyr ago, galaxies with more than 10^11 Msun in stars already existed. While most of these massive galaxies must have subsequently transformed through on-going star formation and mergers with other galaxies, a small fraction (<0.1%) may have survived untouched till today. Searches for such relic galaxies, useful windows to explore the early Universe, have been inconclusive to date: galaxies with masses and sizes like those observed at high redshift (M*>10^11 Msun; Re<1.5 kpc) have been found in the local Universe, but their stars are far too young for the galaxy to be a relic galaxy. This paper explores the first case of a nearby galaxy, NGC1277 (in the Perseus cluster at a distance of 73 Mpc), which fulfills all the criteria to be considered a relic galaxy. Using deep optical spectroscopy, we derive the star formation history along the structure of the galaxy: the stellar populations are uniformly old (>10 Gyr) with no evidence for more recent star formation episodes. The metallicity of their stars is super-solar ([Fe/H]=0.20+-0.04) and alpha enriched ([alpha/Fe]=0.4+-0.1). This suggests a very short formation time scale for the bulk of stars of this galaxy. This object also rotates very fast (Vrot~300 km/s) and has a large velocity dispersion (sigma>300 km/s). NGC1277 will allow future explorations in full detail of properties such as the structure, internal dynamics, metallicity, dust content and initial mass function at around 10-12 Gyr back in time when the first massive galaxies were built.Comment: 4 figures; Accepted for publication at ApJ Letter

    Advanced channel coding for space mission telecommand links

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    We investigate and compare different options for updating the error correcting code currently used in space mission telecommand links. Taking as a reference the solutions recently emerged as the most promising ones, based on Low-Density Parity-Check codes, we explore the behavior of alternative schemes, based on parallel concatenated turbo codes and soft-decision decoded BCH codes. Our analysis shows that these further options can offer similar or even better performance.Comment: 5 pages, 7 figures, presented at IEEE VTC 2013 Fall, Las Vegas, USA, Sep. 2013 Proc. IEEE Vehicular Technology Conference (VTC 2013 Fall), ISBN 978-1-6185-9, Las Vegas, USA, Sep. 201

    The influence of nitrate leaching through unsaturated soil on groundwater pollution in an agricultural area of the Basque country: a case study

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    The average nitrate concentration in the groundwater of the Vitoria-Gasteiz (Basque Country) quaternary aquifer rose from 50 mg NO3−/l during 1986 to over 200 mg/l in 1995, which represents an increase of some 20 mg NO3−/l per year. From 1995 to 2002, the nitrate concentration of the groundwater slightly decreased. Nitrategroundwaterpollution during the period 1986–1993 was the result of the abusive use of fertilizers and of the modification in the recharge patterns of the aquifer from surface water sources. From 1993 onwards, apart from a possible rationalization in fertilizer use, the change in the origin of water for irrigation and wetland restoration (water is taken now from artificial pools outside the quaternary aquifer) must be explained in order to account for the observed decrease in nitrate concentration in the groundwater. The water of the aquifer and of the unsaturated zone were studied in two experimental plots (one of them cultivated and the other uncultivated) for 18 months (January 1993–June 1994), during the period of maximum contamination, to evaluate the effect of fertilizers on soil water and on the water in the saturated zone. The soil water was sampled using soil lysimeters at various depths. The volumetric water content of the soil was measured at the same depths using time domain reflectrometry (TDR) probes. Samples of groundwater were taken from a network of wells on the aquifer scale, two located close to the two experimental plots. The temporal evolution of nitrate concentrations in soil solutions depends on the addition of fertilizers and on soilnitrateleaching by rain. During episodes of intense rain (>50 mm in a day), the groundwater deposits are recharged with water coming from the leaching of interstitial soil solutions, causing an increase in the groundwaternitrate concentrations. The mass of nitrate leached from the cultivated zone is five times higher than that of the nitrate leached from the uncultivated zone (1147 kg NO3−/ha in the cultivated sector as against 211 kg NO3−/ha in the uncultivated sector), although part of the nitrate leached into the soil had been previously deposited by the rise of the water table. If we consider that the level of groundwater input is similar in both plots, we may conclude that 964 kg NO3−/ha circulated towards the groundwater in the cultivated zone during the period under study, representing 87% of the nitrate applied to the soil in the form of fertilizer during that period
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