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Pesquisa : G01.060.075.320 [Categoria DeCS]
Referências encontradas : 32 [refinar]
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  1 / 32 MEDLINE  
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[PMID]:28541322
[Au] Autor:Bouwens R
[Ad] Endereço:Leiden Observatory, Leiden University, Leiden NL-2333, the Netherlands.
[Ti] Título:Astronomy: Quasars signpost massive galaxies.
[So] Source:Nature;545(7655):418-420, 2017 05 24.
[Is] ISSN:1476-4687
[Cp] País de publicação:England
[La] Idioma:eng
[Mh] Termos MeSH primário: Astronomia
Galáxias
[Mh] Termos MeSH secundário: Fenômenos Astronômicos
Meio Ambiente Extraterreno
[Pt] Tipo de publicação:NEWS; COMMENT
[Em] Mês de entrada:1709
[Cu] Atualização por classe:170918
[Lr] Data última revisão:
170918
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170526
[St] Status:MEDLINE
[do] DOI:10.1038/545418a


  2 / 32 MEDLINE  
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[PMID]:28151691
[Au] Autor:Moeller R; Raguse M; Leuko S; Berger T; Hellweg CE; Fujimori A; Okayasu R; Horneck G; and the STARLIFE Research Group
[Ad] Endereço:1 Radiation Biology Department, Institute of Aerospace Medicine , German Aerospace Center (DLR), Cologne, Germany .
[Ti] Título:STARLIFE-An International Campaign to Study the Role of Galactic Cosmic Radiation in Astrobiological Model Systems.
[So] Source:Astrobiology;17(2):101-109, 2017 Feb.
[Is] ISSN:1557-8070
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:In-depth knowledge regarding the biological effects of the radiation field in space is required for assessing the radiation risks in space. To obtain this knowledge, a set of different astrobiological model systems has been studied within the STARLIFE radiation campaign during six irradiation campaigns (2013-2015). The STARLIFE group is an international consortium with the aim to investigate the responses of different astrobiological model systems to the different types of ionizing radiation (X-rays, γ rays, heavy ions) representing major parts of the galactic cosmic radiation spectrum. Low- and high-energy charged particle radiation experiments have been conducted at the Heavy Ion Medical Accelerator in Chiba (HIMAC) facility at the National Institute of Radiological Sciences (NIRS) in Chiba, Japan. X-rays or γ rays were used as reference radiation at the German Aerospace Center (DLR, Cologne, Germany) or Beta-Gamma-Service GmbH (BGS, Wiehl, Germany) to derive the biological efficiency of different radiation qualities. All samples were exposed under identical conditions to the same dose and qualities of ionizing radiation (i) allowing a direct comparison between the tested specimens and (ii) providing information on the impact of the space radiation environment on currently used astrobiological model organisms. Key Words: Space radiation environment-Sparsely ionizing radiation-Densely ionizing radiation-Heavy ions-Gamma radiation-Astrobiological model systems. Astrobiology 17, 101-109.
[Mh] Termos MeSH primário: Radiação Cósmica
Exobiologia
Galáxias
Modelos Teóricos
Voo Espacial
[Mh] Termos MeSH secundário: Radiação Ionizante
[Pt] Tipo de publicação:JOURNAL ARTICLE; REVIEW
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171009
[Lr] Data última revisão:
171009
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170203
[St] Status:MEDLINE
[do] DOI:10.1089/ast.2016.1571


  3 / 32 MEDLINE  
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[PMID]:27213220
[Au] Autor:Lingam M
[Ad] Endereço:Department of Astrophysical Sciences, Princeton University , Princeton, New Jersey.
[Ti] Título:Interstellar Travel and Galactic Colonization: Insights from Percolation Theory and the Yule Process.
[So] Source:Astrobiology;16(6):418-26, 2016 Jun.
[Is] ISSN:1557-8070
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:UNLABELLED: In this paper, percolation theory is employed to place tentative bounds on the probability p of interstellar travel and the emergence of a civilization (or panspermia) that colonizes the entire Galaxy. The ensuing ramifications with regard to the Fermi paradox are also explored. In particular, it is suggested that the correlation function of inhabited exoplanets can be used to observationally constrain p in the near future. It is shown, by using a mathematical evolution model known as the Yule process, that the probability distribution for civilizations with a given number of colonized worlds is likely to exhibit a power-law tail. Some of the dynamical aspects of this issue, including the question of timescales and generalizing percolation theory, were also studied. The limitations of these models, and other avenues for future inquiry, are also outlined. KEY WORDS: Complex life-Extraterrestrial life-Panspermia-Life detection-SETI. Astrobiology 16, 418-426.
[Mh] Termos MeSH primário: Exobiologia
Meio Ambiente Extraterreno
Galáxias
Modelos Teóricos
Voo Espacial
Astros Celestes
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171009
[Lr] Data última revisão:
171009
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160524
[St] Status:MEDLINE
[do] DOI:10.1089/ast.2015.1411


  4 / 32 MEDLINE  
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[PMID]:26359938
[Au] Autor:Paulson S; Frank A; Kaiser D; Maudlin T; Natarajan P
[Ad] Endereço:Wisconsin Public Radio, Madison, Wisconsin.
[Ti] Título:Transcending matter: physics and ultimate meaning.
[So] Source:Ann N Y Acad Sci;1361:36-57, 2015 Dec.
[Is] ISSN:1749-6632
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:From the discovery of new galaxies and nearly undetectable dark energy to the quantum entanglement of particles across the universe, new findings in physics naturally elicit a sense of awe and wonder. For the founders of modern physics-from Einstein and Bohr to Heisenberg, Pauli, and Bohm-a fascination with deeper questions of meaning and ultimate reality led some of them to explore esoteric traditions and metaphysics. More recently, however, physicists have largely shunned such philosophical and spiritual associations. What can contemporary physics offer us in the quest to understand our place in the universe? Has physics in some ways become a religion unto itself that rejects the search for existential meaning? Discussion of these and related questions is presented in this paper.
[Mh] Termos MeSH primário: Galáxias
Metafísica
Física/tendências
[Mh] Termos MeSH secundário: Seres Humanos
[Pt] Tipo de publicação:JOURNAL ARTICLE; REVIEW
[Em] Mês de entrada:1605
[Cu] Atualização por classe:160115
[Lr] Data última revisão:
160115
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:150912
[St] Status:MEDLINE
[do] DOI:10.1111/nyas.12861


  5 / 32 MEDLINE  
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[PMID]:26274865
[Au] Autor:Morrison IS; Gowanlock MG
[Ad] Endereço:1 School of Physics and Australian Centre for Astrobiology, University of New South Wales , Kensington, Australia .
[Ti] Título:Extending Galactic Habitable Zone Modeling to Include the Emergence of Intelligent Life.
[So] Source:Astrobiology;15(8):683-96, 2015 Aug.
[Is] ISSN:1557-8070
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Previous studies of the galactic habitable zone have been concerned with identifying those regions of the Galaxy that may favor the emergence of complex life. A planet is deemed habitable if it meets a set of assumed criteria for supporting the emergence of such complex life. In this work, we extend the assessment of habitability to consider the potential for life to further evolve to the point of intelligence--termed the propensity for the emergence of intelligent life, φI. We assume φI is strongly influenced by the time durations available for evolutionary processes to proceed undisturbed by the sterilizing effects of nearby supernovae. The times between supernova events provide windows of opportunity for the evolution of intelligence. We developed a model that allows us to analyze these window times to generate a metric for φI, and we examine here the spatial and temporal variation of this metric. Even under the assumption that long time durations are required between sterilizations to allow for the emergence of intelligence, our model suggests that the inner Galaxy provides the greatest number of opportunities for intelligence to arise. This is due to the substantially higher number density of habitable planets in this region, which outweighs the effects of a higher supernova rate in the region. Our model also shows that φI is increasing with time. Intelligent life emerged at approximately the present time at Earth's galactocentric radius, but a similar level of evolutionary opportunity was available in the inner Galaxy more than 2 Gyr ago. Our findings suggest that the inner Galaxy should logically be a prime target region for searches for extraterrestrial intelligence and that any civilizations that may have emerged there are potentially much older than our own.
[Mh] Termos MeSH primário: Meio Ambiente Extraterreno
Galáxias
Inteligência
Modelos Teóricos
[Mh] Termos MeSH secundário: Fenômenos Astronômicos
Evolução Biológica
Ecossistema
Exobiologia
Método de Monte Carlo
Planetas
Radiação Ionizante
Esterilização
Fatores de Tempo
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, U.S. GOV'T, NON-P.H.S.
[Em] Mês de entrada:1605
[Cu] Atualização por classe:150815
[Lr] Data última revisão:
150815
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:150815
[St] Status:MEDLINE
[do] DOI:10.1089/ast.2014.1192


  6 / 32 MEDLINE  
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[PMID]:26181770
[Au] Autor:Kilbinger M
[Ad] Endereço:Laboratoire AIM, CEA Saclay-CNRS-Paris 6, Irfu/SAp, F-91191 Gif-sur-Yvette, France.
[Ti] Título:Cosmology with cosmic shear observations: a review.
[So] Source:Rep Prog Phys;78(8):086901, 2015 Jul.
[Is] ISSN:1361-6633
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:Cosmic shear is the distortion of images of distant galaxies due to weak gravitational lensing by the large-scale structure in the Universe. Such images are coherently deformed by the tidal field of matter inhomogeneities along the line of sight. By measuring galaxy shape correlations, we can study the properties and evolution of structure on large scales as well as the geometry of the Universe. Thus, cosmic shear has become a powerful probe into the nature of dark matter and the origin of the current accelerated expansion of the Universe. Over the last years, cosmic shear has evolved into a reliable and robust cosmological probe, providing measurements of the expansion history of the Universe and the growth of its structure. We review here the principles of weak gravitational lensing and show how cosmic shear is interpreted in a cosmological context. Then we give an overview of weak-lensing measurements, and present the main observational cosmic-shear results since it was discovered 15 years ago, as well as the implications for cosmology. We then conclude with an outlook on the various future surveys and missions, for which cosmic shear is one of the main science drivers, and discuss promising new weak cosmological lensing techniques for future observations.
[Mh] Termos MeSH primário: Astronomia/métodos
[Mh] Termos MeSH secundário: Previsões
Galáxias
Gravitação
Modelos Teóricos
Fenômenos Ópticos
[Pt] Tipo de publicação:JOURNAL ARTICLE; REVIEW
[Em] Mês de entrada:1604
[Cu] Atualização por classe:161125
[Lr] Data última revisão:
161125
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:150717
[St] Status:MEDLINE
[do] DOI:10.1088/0034-4885/78/8/086901


  7 / 32 MEDLINE  
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[PMID]:26100873
[Au] Autor:Meinecke J; Tzeferacos P; Bell A; Bingham R; Clarke R; Churazov E; Crowston R; Doyle H; Drake RP; Heathcote R; Koenig M; Kuramitsu Y; Kuranz C; Lee D; MacDonald M; Murphy C; Notley M; Park HS; Pelka A; Ravasio A; Reville B; Sakawa Y; Wan W; Woolsey N; Yurchak R; Miniati F; Schekochihin A; Lamb D; Gregori G
[Ad] Endereço:Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom; g.gregori1@physics.ox.ac.uk jena.meinecke@physics.ox.ac.uk.
[Ti] Título:Developed turbulence and nonlinear amplification of magnetic fields in laboratory and astrophysical plasmas.
[So] Source:Proc Natl Acad Sci U S A;112(27):8211-5, 2015 Jul 07.
[Is] ISSN:1091-6490
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:The visible matter in the universe is turbulent and magnetized. Turbulence in galaxy clusters is produced by mergers and by jets of the central galaxies and believed responsible for the amplification of magnetic fields. We report on experiments looking at the collision of two laser-produced plasma clouds, mimicking, in the laboratory, a cluster merger event. By measuring the spectrum of the density fluctuations, we infer developed, Kolmogorov-like turbulence. From spectral line broadening, we estimate a level of turbulence consistent with turbulent heating balancing radiative cooling, as it likely does in galaxy clusters. We show that the magnetic field is amplified by turbulent motions, reaching a nonlinear regime that is a precursor to turbulent dynamo. Thus, our experiment provides a promising platform for understanding the structure of turbulence and the amplification of magnetic fields in the universe.
[Mh] Termos MeSH primário: Fenômenos Astronômicos
Galáxias
Campos Magnéticos
Modelos Teóricos
[Mh] Termos MeSH secundário: Simulação por Computador
Lasers
Sistema Solar
Análise Espectral
Temperatura Ambiente
Termodinâmica
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, N.I.H., EXTRAMURAL; RESEARCH SUPPORT, NON-U.S. GOV'T; RESEARCH SUPPORT, U.S. GOV'T, NON-P.H.S.
[Em] Mês de entrada:1510
[Cu] Atualização por classe:170922
[Lr] Data última revisão:
170922
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:150624
[St] Status:MEDLINE
[do] DOI:10.1073/pnas.1502079112


  8 / 32 MEDLINE  
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[PMID]:25971656
[Au] Autor:Ueda Y
[Ad] Endereço:Department of Astronomy, Kyoto University.
[Ti] Título:Cosmological evolution of supermassive black holes in galactic centers unveiled by hard X-ray observations.
[So] Source:Proc Jpn Acad Ser B Phys Biol Sci;91(5):175-92, 2015.
[Is] ISSN:1349-2896
[Cp] País de publicação:Japan
[La] Idioma:eng
[Ab] Resumo:We review the current understanding of the cosmological evolution of supermassive black holes in galactic centers elucidated by X-ray surveys of active galactic nuclei (AGNs). Hard X-ray observations at energies above 2 keV are the most efficient and complete tools to find "obscured" AGNs, which are dominant populations among all AGNs. Combinations of surveys with various flux limits and survey area have enabled us to determine the space number density and obscuration properties of AGNs as a function of luminosity and redshift. The results have essentially solved the origin of the X-ray background in the energy band below ∼10 keV. The downsizing (or anti-hierarchical) evolution that more luminous AGNs have the space-density peak at higher redshifts has been discovered, challenging theories of galaxy and black hole formation. Finally, we summarize unresolved issues on AGN evolution and prospects for future X-ray missions.
[Mh] Termos MeSH primário: Evolução Planetária
Galáxias
Física/métodos
[Mh] Termos MeSH secundário: Raios X
[Pt] Tipo de publicação:JOURNAL ARTICLE; REVIEW
[Em] Mês de entrada:1602
[Cu] Atualização por classe:170220
[Lr] Data última revisão:
170220
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:150515
[St] Status:MEDLINE
[do] DOI:10.2183/pjab.91.175


  9 / 32 MEDLINE  
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[PMID]:25720971
[Au] Autor:Kwok S
[Ad] Endereço:Space Astronomy Laboratory, Faculty of Science, The University of Hong Kong, Hong Kong, China, sunkwok@hku.hk.
[Ti] Título:Organic compounds in circumstellar and interstellar environments.
[So] Source:Orig Life Evol Biosph;45(1-2):113-21, 2015 Jun.
[Is] ISSN:1573-0875
[Cp] País de publicação:Netherlands
[La] Idioma:eng
[Ab] Resumo:Recent research has discovered that complex organic matter is prevalent throughout the Universe. In the Solar System, it is found in meteorites, comets, interplanetary dust particles, and planetary satellites. Spectroscopic signatures of organics with aromatic/aliphatic structures are also found in stellar ejecta, diffuse interstellar medium, and external galaxies. From space infrared spectroscopic observations, we have found that complex organics can be synthesized in the late stages of stellar evolution. Shortly after the nuclear synthesis of the element carbon, organic gas-phase molecules are formed in the stellar winds, which later condense into solid organic particles. This organic synthesis occurs over very short time scales of about a thousand years. In order to determine the chemical structures of these stellar organics, comparisons are made with particles produced in the laboratory. Using the technique of chemical vapor deposition, artificial organic particles have been created by injecting energy into gas-phase hydrocarbon molecules. These comparisons led us to believe that the stellar organics are best described as amorphous carbonaceous nanoparticles with mixed aromatic and aliphatic components. The chemical structures of the stellar organics show strong similarity to the insoluble organic matter found in meteorites. Isotopic analysis of meteorites and interplanetary dust collected in the upper atmospheres have revealed the presence of pre-solar grains similar to those formed in old stars. This provides a direct link between star dust and the Solar System and raises the possibility that the early Solar System was chemically enriched by stellar ejecta with the potential of influencing the origin of life on Earth.
[Mh] Termos MeSH primário: Galáxias
Compostos Orgânicos/análise
Sistema Solar
Astros Celestes
[Mh] Termos MeSH secundário: Poeira Cósmica
Meteoroides
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Cosmic Dust); 0 (Organic Chemicals)
[Em] Mês de entrada:1603
[Cu] Atualização por classe:171031
[Lr] Data última revisão:
171031
[Sb] Subgrupo de revista:IM; S
[Da] Data de entrada para processamento:150228
[St] Status:MEDLINE
[do] DOI:10.1007/s11084-015-9410-0


  10 / 32 MEDLINE  
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[PMID]:25612047
[Au] Autor:Peeples MS
[Ad] Endereço:Space Telescope Science Institute, Baltimore, Maryland 21218, USA.
[Ti] Título:Astronomy: Cosmic fog and smog.
[So] Source:Nature;517(7535):444-5, 2015 Jan 22.
[Is] ISSN:1476-4687
[Cp] País de publicação:England
[La] Idioma:eng
[Mh] Termos MeSH primário: Galáxias/química
[Mh] Termos MeSH secundário: Exobiologia
Meio Ambiente Extraterreno/química
Gases/análise
Gases/química
Vida
Metais/análise
Metais/química
Planetas
Astros Celestes/química
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Gases); 0 (Metals)
[Em] Mês de entrada:1502
[Cu] Atualização por classe:150123
[Lr] Data última revisão:
150123
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:150123
[St] Status:MEDLINE
[do] DOI:10.1038/517444a



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