1,836 research outputs found

    Types and Distribution of Bioactive Polyunsaturated Aldehydes in a Gradient from Mesotrophic to OligotrophicWaters in the Alborán Sea (Western Mediterranean)

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    Polyunsaturated aldehydes (PUAs) are bioactive molecules suggested as chemical defenses and infochemicals. In marine coastal habitats, diatoms reach high PUA production levels during bloom episodes. Two fractions of PUA can usually be analyzed: pPUA obtained via artificial breakage of collected phytoplankton cells and dissolved PUA already released to the environment (dPUA). In nature, resource supply arises as a main environmental controlling factor of PUA production. In this work, we monitored the vertical distribution and daily variation of pPUA associated with large-size phytoplankton and dPUA, at three sites located in the Alboran Sea from mesotrophic to oligotrophic waters. The results corroborate the presence of large-size PUA producers in oligotrophic and mesotrophic waters with a significant (58%-85%) diatom biomass. In addition to diatoms, significant correlations between pPUA production and dinoflagellate and silicoflagellate abundance were observed. 2E,4E/Z-Heptadienal was the most abundant aldehyde at the three sites with higher values (17.1 fg center dot cell(-1)) at the most oligotrophic site. 2E,4E/Z-Decadienal was the least abundant aldehyde, decreasing toward the oligotrophic site. For the first time, we describe the daily fluctuation of pPUA attributable to cellular physiological state and not exclusively to taxonomical composition. Our results demonstrate the persistence of threshold levels of dPUA deep in the water column, as well as the different chromatographic profiles of dPUA compared with pPUA. We propose different isomerization processes that alter the chemical structure of the released PUAs with unknown effects on their stability, biological function, and potential bioactivity

    Comparison of 5-year progression of retinitis pigmentosa involving the posterior pole among siblings by means of SD-OCT: a retrospective study

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    The blockchain technology promises to transform finance, money and evengovernments. However, analyses of blockchain applicability and robustness typicallyfocus on isolated systems whose actors contribute mainly by running the consensusalgorithm. Here, we highlight the importance of considering trustless platformswithin the broader ecosystem that includes social and communication networks. Asan example, we analyse the flash-crash observed on 21st June 2017 in the Ethereumplatform and show that a major phenomenon of social coordination led to acatastrophic cascade of events across several interconnected systems. We proposethe concept of “emergent centralisation” to describe situations where a single systembecomes critically important for the functioning of the whole ecosystem, and arguethat such situations are likely to become more and more frequent in interconnectedsocio-technical systems. We anticipate that the systemic approach we propose willhave implications for future assessments of trustless systems and call for the attentionof policy-makers on the fragility of our interconnected and rapidly changing world

    Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV

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    A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.Comment: Submitted to JHE

    Combined search for the quarks of a sequential fourth generation

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    Results are presented from a search for a fourth generation of quarks produced singly or in pairs in a data set corresponding to an integrated luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in 2011. A novel strategy has been developed for a combined search for quarks of the up and down type in decay channels with at least one isolated muon or electron. Limits on the mass of the fourth-generation quarks and the relevant Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a simple extension of the standard model with a sequential fourth generation of fermions. The existence of mass-degenerate fourth-generation quarks with masses below 685 GeV is excluded at 95% confidence level for minimal off-diagonal mixing between the third- and the fourth-generation quarks. With a mass difference of 25 GeV between the quark masses, the obtained limit on the masses of the fourth-generation quarks shifts by about +/- 20 GeV. These results significantly reduce the allowed parameter space for a fourth generation of fermions.Comment: Replaced with published version. Added journal reference and DO

    Performance of the CMS Cathode Strip Chambers with Cosmic Rays

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    The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns

    El Debate Arquitectónico sobre la Vivienda Popular: Del Primer Congreso Argentino de Urbanismo al Primer Congreso Panamericano de la Vivienda Popular (1935-1939)

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    El debate arquitectónico sobre la vivienda popular en la Argentina adquirió en los años treinta una particular intensidad. Cruzado por distintas posiciones ideológicas, y en el marco del reacomodamiento de éstas durante la década, fue parte crucial de un reordenamiento interno de la disciplina. Los arquitectos participaron del desarrollo de un saber técnico en relación al tema que no fue ajeno a esas tensiones. Los foros por excelencia en los que se discutió la cuestión fueron las revistas y los congresos, en donde las distintas voces podían expresar sus opiniones y también rebatir las contrarias. Si bien el debate no quedó zanjado y las realizaciones concretas fueron escasas, el principal aporte en este período fue el de definir las opciones posibles para la solución del problema de la vivienda, delineadas por distintas actitudes frente a la cuestión social, y confrontar sus instrumentos y objetivos

    Transdisciplinary studies in socio-ecosystems: Theoretical considerations and its application in Latin American contexts

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    Debido a limitaciones para abordar la complejidad de la relación sociedad-naturaleza, los esfuerzos para solucionar los problemas ambientales han sido en general infructuosos. Aquí proponemos que el enfoque holístico de “socio-ecosistema” por parte de la academia, podría contribuir a disminuir estas limitaciones desde la adopción de cuatro cambios: i) ontológico, que presenta el concepto de “socio-ecosistemas”; ii) epistemológico, que propone a la transdisciplina como la forma de entenderlos, iii) metodológico, que sugiere intervenir en ellos de forma participativa y adaptativa y, iv) cambios institucionales que facilitarían la adopción de esta propuesta. Este planteamiento se complementa con la descripción de una experiencia transdiciplinaria en la cuenca del río San Juan Zitácuaro, México, en el contexto de un curso internacional de manejo de socio-ecosistemas.Given the difficulties to approach the complex relationship bettween society and nature, efforts to solve environmental problems have generally been unsuccessful. Here we suggest that a hollistic “socio-ecosystem” approach by the sciencies could help diminish these difficulties by embracing four kinds of changes: i) ontological, which introduces the concept of “socio-ecosystem”; ii) epistemological, which proposes transdiscipline as the way to understand them, iii) metholodogical, which suggests that in intervention in them must be participatory and adaptive, iv) institutional changes that would facilitate the adoption of this approach. This is then followed by a description of a transdisciplinary work experience in the Zitácuaro river basin, in Mexico, in the context of an international course on socio-ecosystem management.Fil: Ortega Uribe, Tamara. Universidad de Chile; ChileFil: Mastrangelo, Matias Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; ArgentinaFil: Villarroel Torrez, Daniel. Universidad de Buenos Aires. Facultad de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Piaz, Agustín Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín. Escuela de Humanidades. Centro de Estudios de Historia de la Ciencia y de la Técnica ; ArgentinaFil: Vallejos, María. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Saenz Ceja, Jesús Eduardo. Universidad Nacional Autónoma de México. Centro de Investigaciones en Ecosistemas; MéxicoFil: Gallego, Federico. Universidad de la República. Facultad de Ciencias; UruguayFil: Franquesa Soler, Monserrat. Instituto de Ecología; MéxicoFil: Calzada Peña, Leonardo. Universidad Nacional Autónoma de México; MéxicoFil: Espinosa Mellado, Noelia. Universidad de la Armada; MéxicoFil: Fiestas Flores, Jerico. Instituto de Estudios Peruanos; PerúFil: Gill Mairhofer, Luis R.. Ministerio de la Defensa Pública; ParaguayFil: González Espino, Zarahí. Instituto Superior de Tecnologías y Ciencias Aplicadas. Facultad de Medio Ambiente. Departamento de Meteorología; CubaFil: Luna Salguero, Betsabé Montserrat. Sociedad de Historia Natural Niparajá; MéxicoFil: Martinez Peralta, Claudia María. Comisión de Ecología y Desarrollo Sustentable del Estado de Sonora. Dirección General de Conservación; MéxicoFil: Ochoa, Olivia. Universidad Nacional Autónoma de México; MéxicoFil: Pérez Volkow,Lucía. No especifica;Fil: Sala, Juan Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Sánchez Rose, Isabelle. Universidad Central de Venezuela; VenezuelaFil: Weeks, Madeline. University of Cambridge; Reino UnidoFil: Ávila García, Daniela. Universidad Nacional Autónoma de México; MéxicoFil: García Reyes, Isabel Bueno. Universidad Nacional Autónoma de México. Centro de Investigaciones en Ecosistemas; MéxicoFil: Carmona, Alejandra. Universidad Austral de Chile. Instituto de Economía Agraria; ChileFil: Castro Videla, Fernando Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Mendoza-San Juan; ArgentinaFil: Ferrer Gonzalez, César Sergio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Ciencias Humanas, Sociales y Ambientales; ArgentinaFil: Frank Buss, María Elisa. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Pampa. Facultad de Agronomía; ArgentinaFil: López Carapia, Gabriela. Universidad Nacional Autónoma de México; MéxicoFil: Núñez Cruz, Martha. Universidad Nacional Autónoma de México; MéxicoFil: Taboada Hermoza, Rossi. Universidad Nacional Mayor de San Marcos; PerúFil: Benet, Daniel. Alternare A. C.; MéxicoFil: Venegas, Ysmael. Alternare A. C.; MéxicoFil: Balvanera, Patricia. Universidad Nacional Autónoma de México. Centro de Investigaciones en Ecosistemas; MéxicoFil: Mwampamba, Tuyeni H.. Universidad Nacional Autónoma de México. Centro de Investigaciones en Ecosistemas; MéxicoFil: Lazos Chavero, Elena. Universidad Nacional Autónoma de México. Centro de Investigaciones en Ecosistemas; MéxicoFil: Noellemeyer, Elke Johanna. Universidad Nacional de La Pampa. Facultad de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Maass, Manuel. Universidad Nacional Autónoma de México. Centro de Investigaciones en Ecosistemas; Méxic

    Performance and Operation of the CMS Electromagnetic Calorimeter

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    The operation and general performance of the CMS electromagnetic calorimeter using cosmic-ray muons are described. These muons were recorded after the closure of the CMS detector in late 2008. The calorimeter is made of lead tungstate crystals and the overall status of the 75848 channels corresponding to the barrel and endcap detectors is reported. The stability of crucial operational parameters, such as high voltage, temperature and electronic noise, is summarised and the performance of the light monitoring system is presented
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