Erratum: "A Gravitational-wave Measurement of the Hubble Constant Following the Second Observing Run of Advanced LIGO and Virgo" (2021, ApJ, 909, 218)

[no abstract available

GW190814: gravitational waves from the coalescence of a 23 solar mass black hole with a 2.6 solar mass compact object

We report the observation of a compact binary coalescence involving a 22.2–24.3 Me black hole and a compact object with a mass of 2.50–2.67 Me (all measurements quoted at the 90% credible level). The gravitational-wave signal, GW190814, was observed during LIGO’s and Virgo’s third observing run on 2019 August 14 at 21:10:39 UTC and has a signal-to-noise ratio of 25 in the three-detector network. The source was localized to 18.5 deg2 at a distance of - + 241 45 41 Mpc; no electromagnetic counterpart has been confirmed to date. The source has the most unequal mass ratio yet measured with gravitational waves, - + 0.112 0.009 0.008, and its secondary component is either the lightest black hole or the heaviest neutron star ever discovered in a double compact-object system. The dimensionless spin of the primary black hole is tightly constrained to �0.07. Tests of general relativity reveal no measurable deviations from the theory, and its prediction of higher-multipole emission is confirmed at high confidence. We estimate a merger rate density of 1–23 Gpc−3 yr−1 for the new class of binary coalescence sources that GW190814 represents. Astrophysical models predict that binaries with mass ratios similar to this event can form through several channels, but are unlikely to have formed in globular clusters. However, the combination of mass ratio, component masses, and the inferred merger rate for this event challenges all current models of the formation and mass distribution of compact-object binaries

Using global optimization for a microparticle identification problem with noisy data

“The original publication is available at www.springerlink.com”. Copyright Springer. DOI: 10.1007/s10898-004-1943-0Peer reviewe

Development of e-commerce in Croatia: a survey

The increasing popularity of e-commerce is apparent. This article addresses the main issues related to e-commerce and, in particular, presents the results of a large survey carried out in 116 Croatian companies. The objective of this survey was to investigate the current practices related to the development and implementation of e-commerce in Croatia. The results obtained indicate that the amount of investment in e-commerce projects is still very low in Croatian companies. Furthermore, it was discovered that although the potential benefits of e-commerce development were ranked very high by Croatian managers, it became apparent that the e-commerce projects were predominantly focused on the simple and static Web site development in the form of online catalogues. Furthermore, this research has revealed that the Croatian government's efforts to promote e-commerce are not producing desired results at organizational levels, and one of the contributing factors to this is relatively low awareness of top managers about the importance and potential benefits of e-commerce. The results of this study are likely to have wider implications both for the research and the practice of implementing e-commerce in the context of developing countries