The nearby radio galaxy M87 is a prime target for studying black hole accretion and jet formation. Event Horizon Telescope observations of M87 in 2017, at a wavelength of 1.3 mm, revealed a ring-like structure, which was interpreted as gravitationally lensed emission around a central black hole.
View Article and Find Full Text PDFThe 2017 Event Horizon Telescope (EHT) observations of the central source in M87 have led to the first measurement of the size of a black-hole shadow. This observation offers a new and clean gravitational test of the black-hole metric in the strong-field regime. We show analytically that spacetimes that deviate from the Kerr metric but satisfy weak-field tests can lead to large deviations in the predicted black-hole shadows that are inconsistent with even the current EHT measurements.
View Article and Find Full Text PDFBackground: Data on rotavirus burden among children in the 15 newly independent states of the former Union of Soviet Socialist Republics, particularly contemporary data from poorer countries, are not widely available. These data are desired by policy makers to assess the value of rotavirus vaccination, especially since the GAVI Alliance approved financial support for the region's eligible countries. The Rotavirus Surveillance Network was established to provide these data.
View Article and Find Full Text PDFIn 2005 the then ESA Directorate for Human Spaceflight, Microgravity and Exploration (D-HME) commissioned a study from the European Science Foundation's (ESF) European Space Sciences Committee (ESSC) to examine the science aspects of the Aurora Programme in preparation for the December 2005 Ministerial Conference of ESA Member States, held in Berlin. A first interim report was presented to ESA at the second stakeholders meeting on 30 and 31 May 2005. A second draft report was made available at the time of the final science stakeholders meeting on 16 September 2005 in order for ESA to use its recommendations to prepare the Executive proposal to the Ministerial Conference.
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