409 research outputs found

    Black holes, gravitational waves and fundamental physics: a roadmap

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    The grand challenges of contemporary fundamental physics‚ÄĒdark matter, dark energy, vacuum energy, inflation and early universe cosmology, singularities and the hierarchy problem‚ÄĒall involve gravity as a key component. And of all gravitational phenomena, black holes stand out in their elegant simplicity, while harbouring some of the most remarkable predictions of General Relativity: event horizons, singularities and ergoregions. The hitherto invisible landscape of the gravitational Universe is being unveiled before our eyes: the historical direct detection of gravitational waves by the LIGO-Virgo collaboration marks the dawn of a new era of scientific exploration. Gravitational-wave astronomy will allow us to test models of black hole formation, growth and evolution, as well as models of gravitational-wave generation and propagation. It will provide evidence for event horizons and ergoregions, test the theory of General Relativity itself, and may reveal the existence of new fundamental fields. The synthesis of these results has the potential to radically reshape our understanding of the cosmos and of the laws of Nature. The purpose of this work is to present a concise, yet comprehensive overview of the state of the art in the relevant fields of research, summarize important open problems, and lay out a roadmap for future progress. This write-up is an initiative taken within the framework of the European Action on 'Black holes, Gravitational waves and Fundamental Physics'

    Multiple Scenario Generation of Subsurface Models:Consistent Integration of Information from Geophysical and Geological Data throuh Combination of Probabilistic Inverse Problem Theory and Geostatistics

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    Neutrinos with energies above 1017 eV are detectable with the Surface Detector Array of the Pierre Auger Observatory. The identification is efficiently performed for neutrinos of all flavors interacting in the atmosphere at large zenith angles, as well as for Earth-skimming \u3c4 neutrinos with nearly tangential trajectories relative to the Earth. No neutrino candidates were found in 3c 14.7 years of data taken up to 31 August 2018. This leads to restrictive upper bounds on their flux. The 90% C.L. single-flavor limit to the diffuse flux of ultra-high-energy neutrinos with an E\u3bd-2 spectrum in the energy range 1.0 7 1017 eV -2.5 7 1019 eV is E2 dN\u3bd/dE\u3bd < 4.4 7 10-9 GeV cm-2 s-1 sr-1, placing strong constraints on several models of neutrino production at EeV energies and on the properties of the sources of ultra-high-energy cosmic rays

    Effect of enzymatic hydrolysis on bioactive properties of the mussel Mytilus galloprovincialis

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    Disserta√ß√£o de mestrado em Tecnologia e Ci√™ncia AlimentarOs oceanos e a diversidade de ambientes marinhos constituem uma fonte de diversos compostos qu√≠micos e biol√≥gicos de valor acrescentado. A valoriza√ß√£o destes recursos e a otimiza√ß√£o dos processos de extra√ß√£o recorrendo a tecnologias sustent√°veis e eficientes permite a s√≠ntese compostos biol√≥gicos que podem ser usados no desenvolvimento de alimentos funcionais, nutrac√™uticos, cosm√©ticos e medicamentos. O presente trabalho teve como objetivo estudar a otimiza√ß√£o do processo de hidr√≥lise enzim√°tica do mexilh√£o Mytilus galloprovincialis com a enzima Alcalase, para produ√ß√£o de p√©ptidos com propriedades antioxidante, anti-hipertensiva e antimicrobiana. O mexilh√£o foi obtido como subproduto de aquacultura da costa portuguesa, do qual foi aproveitada apenas a carne. A composi√ß√£o qu√≠mica aproximada determinada foi de 81,4 g de humidade, 12,6 g de prote√≠na, 1,7 g de l√≠pidos, 1,4 g de minerais e 2,8 g de hidratos de carbono. Foi usada a Metodologia de Superf√≠cie de Resposta atrav√©s de um desenho experimental composto central rotacional 23 com dezasseis ensaios para avaliar os efeitos das vari√°veis concentra√ß√£o de substrato (25, 50 e 75 g/150 g), concentra√ß√£o de enzima (1, 2 e 3 % v/m) e tempo (1, 2 e 3 h) tendo como resposta o grau de hidr√≥lise (GH %). Os resultados obtidos foram analisados atrav√©s do software Statistica vers√£o 10 e a signific√Ęncia estat√≠stica atrav√©s da an√°lise da vari√Ęncia (ANOVA). As condi√ß√Ķes √≥timas do ponto de vista industrial s√£o 25 g de substrato, 2 % de concentra√ß√£o de enzima e tempo de rea√ß√£o de 1 h. Os hidrolisados obtidos foram avaliados quanto √† sua capacidade antioxidante atrav√©s do m√©todo da atividade sequestradora do radical livre DPPH. O hidrolisado com maiores valores atividade antioxidante foi com concentra√ß√£o de substrato de 75 g/150 g, concentra√ß√£o de enzima de 2 % e tempo de rea√ß√£o de 2 h. O aumento concentra√ß√£o de substrato demonstrou influenciar positivamente a atividade antioxidante. Os ensaios de atividade anti-hipertensiva n√£o foram conclusivos para as amostras testadas. Os hidrolisados manifestaram atividade antimicrobiana nos microrganismos S. aureus e B. cereus. A bact√©ria E. coli n√£o sofreu qualquer inibi√ß√£o de crescimento. O ensaio com maior halo de inibi√ß√£o foi de concentra√ß√£o de substrato de 25 g, concentra√ß√£o de enzima de 1 % e tempo de rea√ß√£o de 1 h.Oceans and the diversity of marine environments are a source of diverse value-added chemical and biological compounds. The valorisation of these resources and the optimization of extraction processes using sustainable and efficient technologies allows the synthesis of biological compounds that can be used in the development of functional foods, nutraceuticals, cosmetics and medicines. The present work aimed to study the optimization of the enzymatic hydrolysis process of the mussel Mytilus galloprovincialis with the enzyme Alcalase, for the production of peptides with antioxidant, antihypertensive and antimicrobial properties. The mussel was obtained as an aquaculture byproduct from the Portuguese coast, which was used only for meat. The approximate chemical composition determined was 81.4 g moisture, 12.6 g protein, 1.7 g lipids, 1.4 g minerals and 2.8 g carbohydrates. Response Surface Methodology through a rotational central composite experimental design 23 with sixteen assays was used to evaluate the effects of substrate concentration (25, 50 and 75 g/150 g), enzyme concentration (1, 2 and 3 %) and time (1, 2 and 3 h) having as response the degree of hydrolysis (GH %). The results were analyzed using Statistica software version 10 and statistical significance through analysis of variance (ANOVA). The optimum conditions studied were 25 g of substrate, 3 % of enzyme concentration and 3 h reaction time, where a hydrolysis degree of 35.1 % was achieved. The hydrolysates obtained were evaluated for their antioxidant capacity by the DPPH free radical scavenging method. The hydrolyzate with the highest antioxidant activity was with 75 g/150 g substrate concentration, 2 % enzyme concentration and 2 h reaction time. Increased substrate concentration has been shown to positively influence antioxidant activity, however this does not apply to enzyme concentration and reaction time. No relationship was observed between the degree of hydrolysis and antioxidant capacity. Antihypertensive activity assays were not conclusive for the samples tested. Hydrolysates showed antimicrobial activity in S. aureus and B. cereus. The bacterium E. coli did not suffer any growth inhibition. The assay with the largest inhibition halo was 25 g/150 g substrate concentration, 1 % enzyme concentration and 1 h reaction time

    Evidence for a mixed mass composition at the ‚Äėankle‚Äô in the cosmic-ray spectrum

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    Combined fit of spectrum and composition data as measured by the Pierre Auger Observatory

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    Search for photons with energies above 1018 eV using the hybrid detector of the Pierre Auger Observatory

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    Erratum: Combined fit of spectrum and composition data as measured by the Pierre Auger Observatory

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    We present a combined fit of a simple astrophysical model of UHECR sources to both the energy spectrum and mass composition data measured by the Pierre Auger Observatory. The fit has been performed for energies above 5¬†‚čÖ¬†10(18) eV, i.e. the region of the all-particle spectrum above the so-called ankle feature. The astrophysical model we adopted consists of identical sources uniformly distributed in a comoving volume, where nuclei are accelerated through a rigidity-dependent mechanism. The fit results suggest sources characterized by relatively low maximum injection energies, hard spectra and heavy chemical composition. We also show that uncertainties about physical quantities relevant to UHECR propagation and shower development have a non-negligible impact on the fit results

    The Pierre Auger Observatory: Contributions to the 35th International Cosmic Ray Conference (ICRC 2017)

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    Observation of inclined EeV air showers with the radio detector of the Pierre Auger Observatory

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    International audienceWith the Auger Engineering Radio Array (AERA) of the Pierre Auger Observatory, we have observed the radio emission from 561 extensive air showers with zenith angles between 60o and 84o. In contrast to air showers with more vertical incidence, these inclined air showers illuminate large ground areas of several km2 with radio signals detectable in the 30 to 80 MHz band. A comparison of the measured radio-signal amplitudes with Monte Carlo simulations of a subset of 50 events for which we reconstruct the energy using the Auger surface detector shows agreement within the uncertainties of the current analysis. As expected for forward-beamed radio emission undergoing no significant absorption or scattering in the atmosphere, the area illuminated by radio signals grows with the zenith angle of the air shower. Inclined air showers with EeV energies are thus measurable with sparse radio-antenna arrays with grid sizes of a km or more. This is particularly attractive as radio detection provides direct access to the energy in the electromagnetic cascade of an air shower, which in case of inclined air showers is not accessible by arrays of particle detectors on the ground

    An Indication of anisotropy in arrival directions of ultra-high-energy cosmic rays through comparison to the flux pattern of extragalactic gamma-ray sources

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    International audienceA new analysis of the data set from the Pierre Auger Observatory provides evidence for anisotropy in the arrival directions of ultra-high-energy cosmic rays on an intermediate angular scale, which is indicative of excess arrivals from strong, nearby sources. The data consist of 5514 events above with zenith angles up to 80¬į¬†recorded before 2017 April 30. Sky models have been created for two distinct populations of extragalactic gamma-ray emitters: active galactic nuclei from the second catalog of hard Fermi-LAT sources (2FHL) and starburst galaxies from a sample that was examined with Fermi-LAT. Flux-limited samples, which include all types of galaxies from the Swift-BAT and 2MASS surveys, have been investigated for comparison. The sky model of cosmic-ray density constructed using each catalog has two free parameters, the fraction of events correlating with astrophysical objects, and an angular scale characterizing the clustering of cosmic rays around extragalactic sources. A maximum-likelihood ratio test is used to evaluate the best values of these parameters and to quantify the strength of each model by contrast with isotropy. It is found that the starburst model fits the data better than the hypothesis of isotropy with a statistical significance of 4.0ŌÉ, the highest value of the test statistic being for energies above . The three alternative models are favored against isotropy with 2.7ŌÉ‚Äď3.2ŌÉ significance. The origin of the indicated deviation from isotropy is examined and prospects for more sensitive future studies are discussed
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