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Effect of solid solution formation on densification of spark plasma sintered ZrC ceramics with TiC as sintering aid
In: Advances in applied ceramics: structural, functional and bioceramics, Band 115, Heft 1, S. 55-59
ISSN: 1743-6761
Living status in patients over 85 years of age after TUVRP
In: The aging male: the official journal of the International Society for the Study of the Aging Male, Band 16, Heft 4, S. 191-194
ISSN: 1473-0790
China's livestock transition: Driving forces, impacts, and consequences
China's livestock industry has experienced a vast transition during the last three decades, with profound effects on domestic and global food provision, resource use, nitrogen and phosphorus losses, and greenhouse gas (GHG) emissions. We provide a comprehensive analysis of the driving forces around this transition and its national and global consequences. The number of livestock units (LUs) tripled in China in less than 30 years, mainly through the growth of landless industrial livestock production systems and the increase in monogastric livestock (from 62 to 74% of total LUs). Changes were fueled through increases in demand as well as, supply of new breeds, new technology, and government support. Production of animal source protein increased 4.9 times, nitrogen use efficiency at herd level tripled, and average feed use and GHG emissions per gram protein produced decreased by a factor of 2 between 1980 and 2010. In the same period, animal feed imports have increased 49 times, total ammonia and GHG emissions to the atmosphere doubled, and nitrogen losses to watercourses tripled. As a consequence, China's livestock transition has significant global impact. Forecasts for 2050, using the Shared Socio-economic Pathways scenarios, indicate major further changes in livestock production and impacts. On the basis of these possible trajectories, we suggest an alternative transition, which should be implemented by government, processing industries, consumers, and retailers. This new transition is targeted to increase production efficiency and environmental performance at system level, with coupling of crop-livestock production, whole chain manure management, and spatial planning as major components.
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China's livestock transition: Driving forces, impacts, and consequences
China's livestock industry has experienced a vast transition during the last three decades, with profound effects on domestic and global food provision, resource use, nitrogen and phosphorus losses, and greenhouse gas (GHG) emissions. We provide a comprehensive analysis of the driving forces around this transition and its national and global consequences. The number of livestock units (LUs) tripled in China in less than 30 years, mainly through the growth of landless industrial livestock production systems and the increase in monogastric livestock (from 62 to 74% of total LUs). Changes were fueled through increases in demand as well as, supply of new breeds, new technology, and government support. Production of animal source protein increased 4.9 times, nitrogen use efficiency at herd level tripled, and average feed use and GHG emissions per gram protein produced decreased by a factor of 2 between 1980 and 2010. In the same period, animal feed imports have increased 49 times, total ammonia and GHG emissions to the atmosphere doubled, and nitrogen losses to watercourses tripled. As a consequence, China's livestock transition has significant global impact. Forecasts for 2050, using the Shared Socio-economic Pathways scenarios, indicate major further changes in livestock production and impacts. On the basis of these possible trajectories, we suggest an alternative transition, which should be implemented by government, processing industries, consumers, and retailers. This new transition is targeted to increase production efficiency and environmental performance at system level, with coupling of crop-livestock production, whole chain manure management, and spatial planning as major components.
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Taking action on air pollution control in the Beijing-Tianjin-Hebei (BTH) region: Progress, challenges and opportunities
Due to rapid urbanization, industrialization and motorization, a large number of Chinese cities are affected by heavy air pollution. In order to explore progress, remaining challenges, and sustainability of air pollution control in the Beijing-Tianjin-Hebei (BTH) region after 2013, a mixed method analysis was undertaken. The quantitative analysis comprised an overview of air quality management in the BTH region. Semi-structured expert interviews were conducted with 12 stakeholders from various levels of government and research institutions who played substantial roles either in decision-making or in research and advising on air pollution control in the BTH region. The results indicated that with the stringent air pollution control policies, the air quality in BTH meets the targets of the Air Pollution Prevention and Control Action Plan. However, improvements vary across the region and for different pollutants. Although implementation has been decisive and was at least in parts effectively enforced, significant challenges remained with regard to industrial and traffic emission control, and national air quality limits continued to be significantly exceeded and competing development interests remained mainly unsolved. There were also concerns about the sustainability of the current air pollution control measures especially for industries due to the top-down enforcement, and the associated large burden of social cost including unemployment and social inequity resulting industrial restructuring. Better mechanisms for ensuring cross-sectoral coordination and for improved central-local government communication were suggested. Further suggestions were provided to improve the conceptual design and effective implementation of respective air pollution control strategies in BTH. Our study highlights some of the major hurdles that need to be addressed to succeed with a comprehensive air pollution control management for the Chinese mega-urban agglomerations.
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Meeting financial challenge facing China's Sponge City Program (SCP) – Hong Kong as a gateway to green finance
China's Sponge City Program (SCP) envisions a city's surface water management system to function like a sponge to absorb, store, infiltrate, and purify rainwater, and release it for reuse when needed. It emphasizes the use of natural and natural-engineering hybrid measures to mimic natural water cycle, thus offers Nature-Based-Solutions (NBS) to urban surface water management. The SCP has become a flagship sustainability program, applied across 30 pilot cities in mainland China since 2014. Significant progress has been made with three years of start-up financial support from the central government. At present, securing adequate financial resources to support further construction, operation, and maintenance of relevant green/blue infrastructures becomes the key challenge to extending the SCP within pilot cities and to other cities. Green finance, referring to local, national, or transnational financial investments from public, private, and alternative sources flowing into environmental and sustainability initiatives, has been experimented in the EU member countries and identified as one of the key business models to NBS, could be a viable solution to further the uptake of China's SCP concept and its implementation. In this context, the emergence of Hong Kong as an Asia-Pacific green finance hub offers a gateway for the SCP to secure financial resources. This paper describes the financial challenge of the SCP and the emerging development of green finance in China and compares it with the EU's experience in NBS green finance. It then explores how Hong Kong could take advantage of its well-established international standards and favourable geopolitical position as a key financial hub to channel green capital into China's SCP from interested investors. To do so requires overcoming current barriers in financial regulations and jurisdictional regimes between mainland China and Hong Kong. A stable and transparent cross-border green finance platform should be established to actively engage investors interested in the SCP ...
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Hierarchical structured and programmed vehicles deliver drugs locally to inflamed sites of intestine
Orally administrable drug delivery vehicles are developed to manage incurable inflammatory bowel disease (IBD), however, their therapeutic outcomes are compromised by the side effects of systemic drug exposure. Herein, we use hyaluronic acid functionalized porous silicon nanoparticle to bridge enzyme-responsive hydrogel and pH-responsive polymer, generating a hierarchical structured (nano-in-nano-in-micro) vehicle with programmed properties to fully and sequentially overcome the multiple obstacles for efficiently delivering drugs locally to inflamed sites of intestine. After oral administration, the pH-responsive matrix protects the embedded hybrid nanoparticles containing drug loaded hydrogels against the spatially variable physiological environments of the gastrointestinal tract until they reach the inflamed sites of intestine, preventing premature drug release. The negatively charged hybrid nanoparticles selectively target the inflamed sites of intestine, and gradually release drug in response to the microenvironment of inflamed intestine. Overall, the developed hierarchical structured and programmed vehicles load, protect, transport and release drugs locally to inflamed sites of intestine, contributing to superior therapeutic outcomes. Such strategy could also inspire the development of numerous hierarchical structured vehicles by other porous nanoparticles and stimuli-responsive materials for the local delivery of various drugs to treat plenty of inflammatory gastrointestinal diseases, including IBD, gastrointestinal cancers and viral infections. ; W.L. acknowledges the Orion Research Foundation for financial support. Z.L. acknowledges the Chinese Scholarship Council for financial support. T.B.-R. acknowledges financial support from the Fundação para a Ciência e a Tecnologia (grant no. SFRH/BD/110859/2015 ). H.Z. acknowledges Jane and Aatos Erkko Foundation (grant no. 4704010 ), Academic of Finland (grant no. 297580 ) and Sigrid Jusélius Foundation (grant no. 28001830K1 ) for financial support. D.L. acknowledges the Jane and Aatos Erkko Foundation for financial support. X.D. acknowledges financial support from the National Key R&D Program (Grant Nos. 2017YFA0504504 and 2016YFA0502001 ), the National Natural Science Foundation of China (Grant Nos. U1405223 and 81661138005 ), the Fundamental Research Funds for the Central Universities of China (Grant No. 20720160064 ), and the Program of Introducing Talents of Discipline to Universities (111 Project, B12001 ). H.A.S. acknowledges financial support from the Sigrid Jusélius Foundation (Decision No. 4704580 ), the European Research Council under the European Union's Seventh Framework Programme ( FP/2007-2013 , Grant No. 310892 ) and the HiLIFE Research Funds.
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Recent advances in understanding the terminal Ediacaran Earth-life system in South China and Arctic Siberia ; Estudios Geologicos-Madrid
The terminal Ediacaran contains dramatic changes in biogeochemical cycles, many of which are closely coupled with evolutionary transitions in the corresponding fossil records. Dynamic redox conditions may have caused a profound impact on early animal evolution. Our work highlights the significance of integrated bio-, litho-, and chemo-stratigraphy in geobiology research of the deep time. ; Public domain authored by a U.S. government employee
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Bone mineral density, osteoporosis, and osteoporotic fractures: a genome-wide association study
Background: Osteoporosis is diagnosed by the measurement of bone mineral density, which is a highly heritable and multifactorial trait. We aimed to identify genetic loci that are associated with bone mineral density. Methods: In this genome-wide association study, we identified the most promising of 314 075 single nucleotide polymorphisms (SNPs) in 2094 women in a UK study. We then tested these SNPs for replication in 6463 people from three other cohorts in western Europe. We also investigated allelic expression in lymphoblast cell lines. We tested the association between the replicated SNPs and osteoporotic fractures with data from two studies. Findings: We identified genome-wide evidence for an association between bone mineral density and two SNPs (p<5×10-8). The SNPs were rs4355801, on chromosome 8, near to the TNFRSF11B (osteoprotegerin) gene, and rs3736228, on chromosome 11 in the LRP5 (lipoprotein-receptor-related protein) gene. A non-synonymous SNP in the LRP5 gene was associated with decreased bone mineral density (rs3736228, p=6·3×10-12for lumbar spine and p=1·9×10-4for femoral neck) and an increased risk of both osteoporotic fractures (odds ratio [OR] 1·3, 95% CI 1·09-1·52, p=0·002) and osteoporosis (OR 1·3, 1·08-1·63, p=0·008). Three SNPs near the TNFRSF11B gene were associated with decreased bone mineral density (top SNP, rs4355801: p=7·6×10-10for lumbar spine and p=3·3×10-8for femoral neck) and increased risk of osteoporosis (OR 1·2, 95% CI 1·01-1·42, p=0·038). For carriers of the risk allele at rs4355801, expression of TNFRSF11B in lymphoblast cell lines was halved (p=3·0×10-6). 1883 (22%) of 8557 people were at least heterozygous for these risk alleles, and these alleles had a cumulative association with bone mineral density (trend p=2·3×10-17). The presence of both risk alleles increased the risk of osteoporotic fractures (OR 1·3, 1·08-1·63, p=0·006) and this effect was independent of bone mineral density. Interpretation: Two gene variants of key biological proteins increase the risk of osteoporosis and osteoporotic fracture. The combined effect of these risk alleles on fractures is similar to that of most well-replicated environmental risk factors, and they are present in more than one in five white people, suggesting a potential role in screening. Funding: Wellcome Trust, European Commission, NWO Investments, Arthritis Research Campaign, Chronic Disease Research Foundation, Canadian Institutes of Health Research, European Society for Clinical and Economic Aspects of Osteoporosis, Genome Canada, Genome Quebéc, Canada Research Chairs, National Health and Medical Research Council of Australia, and European Union.
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Transition from fireball to Poynting-flux-dominated outflow in the three-episode GRB 160625B
The ejecta composition is an open question in gamma-ray burst (GRB) physics . Some GRBs possess a quasi-thermal spectral component in the time-resolved spectral analysis , suggesting a hot fireball origin. Others show a featureless non-thermal spectrum known as the Band function , consistent with a synchrotron radiation origin and suggesting that the jet is Poynting-flux dominated at the central engine and probably in the emission region as well . There are also bursts showing a sub-dominant thermal component and a dominant synchrotron component , suggesting a probable hybrid jet composition . Here, we report an extraordinarily bright GRB 160625B, simultaneously observed in gamma-ray and optical wavelengths, whose prompt emission consists of three isolated episodes separated by long quiescent intervals, with the durations of each sub-burst being approximately 0.8 s, 35 s and 212 s, respectively. Its high brightness (with isotropic peak luminosity L ≈ 4 × 10 erg s) allows us to conduct detailed time-resolved spectral analysis in each episode, from precursor to main burst and to extended emission. The spectral properties of the first two sub-bursts are distinctly different, allowing us to observe the transition from thermal to non-thermal radiation between well-separated emission episodes within a single GRB. Such a transition is a clear indication of the change of jet composition from a fireball to a Poynting-flux-dominated jet. ; B.-B.Z. thanks Y.-Z. Fan, Y.-Z. Wang, H. Wang, K. D. Alexander and D. Lazzati for helpful discussions. We are grateful to K. Hurley, I. Mitrofanov, A. Sanin, M. Litvak and W. Boynton for the use of Mars Odyssey data in the triangulation. We acknowledge the use of the public data from the Swift and Fermi data archives. B.-B. Z. and A.J. C.-T. acknowledge support from the Spanish Ministry Projects AYA2012-39727-C03-01 and AYA2015-71718-R. Part of this work made use of B.-B.Z.'s personal Interactive Data Language (IDL) code library ZBBIDL and personal Python library ZBBPY. The computation resources used in this work are owned by Scientist Support LLC. B.Z. acknowledges NASA NNX14AF85G and NNX15AK85G for support. Z. G. D. acknowledges the National Natural Science Foundation of China(NSFC) (grant 11573014). Y.-D. H. acknowledges support by China Scholarships Council (grant 201406660015). Mini-MegaTORTORA belongs to Kazan Federal University, and the work is performed according to the Russian Government Program of Competitive Growth of Kazan Federal University. A. P., E.M., P. M. and A.V. are grateful to the Russian Foundation for Basic Research (grant 17-02-01388) for partial support. A. P. and S.B.P. acknowledge joint BRICS (Brazil, Russia, India, China and South Africa) grant RFBR 17-52-80139 and 388-ProFChEAP for partial support. R. I. is grateful to grant RUSTAVELI FR/379/6300/ 14 for partial support. Observations on Mini-MegaTORTORA are supported by the Russian Science Foundation (grant 14-50-00043). A.V.F. and A. M. thank the Russian Science Foundation (grant 14-50-00043). L.M. and A.F.Z. acknowledge support from INTA-CEDEA ESAt personnel hosting the Pi of the Sky facility at the BOOTES-1 station. H. G. and X.-Y.W. acknowledge NSFC (grants 11603003 and 11625312, respectively). Z. G. D., X.-F. W., B.Z., X.-Y. W.,L.S. and F.-W.Z. are also supported by the 973 program (grant 2014CB845800). F.-W.Z. is also supported in part by the NSFC (grants U1331101 and 11163003), the Guangxi Natural Science Foundation (grant 2013GXNSFAA019002) and the project of outstanding young teachers' training in higher education institutions of Guangxi. L.S. acknowledges support by the NSFC (grant 11103083) and the Joint NSFC-ISF Research Program (grant 11361140349). S.O. acknowledges the support of the Leverhulme Trust. S.J. acknowledges support from Korea Basic Science Research Program through NRF-2014R1A6A3A03057484 and NRF-2015R1D1A4A01020961, and I. H. P. through NRF-2015R1A2A1A01006870 and NRF-2015R1A2A1A15055344. R. A., D. F. and D. S. acknowledge support from RSF (grant 17-12-01378). A. K. acknowledges the Science and Education Ministry of Kazakhstan (grant 0075/GF4).
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Community assessment to advance computational prediction of cancer drug combinations in a pharmacogenomic screen
AstraZeneca ; European Union Horizon 2020 research (under grant agreement No 668858 PrECISE to J.S.R.) ; Wellcome Trust (102696 and 206194)
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All-sky search for long-duration gravitational wave transients with initial LIGO
United States National Science Foundation (NSF) ; Science and Technology Facilities Council (STFC) of the United Kingdom ; Max-Planck-Society (MPS) ; State of Niedersachsen/Germany ; Italian Istituto Nazionale di Fisica Nucleare (INFN) ; French Centre National de la Recherche Scientifique (CNRS) ; Australian Research Council ; International Science Linkages program of the Commonwealth of Australia ; Council of Scientific and Industrial Research of India ; Department of Science and Technology, India ; Science & Engineering Research Board (SERB), India ; Ministry of Human Resource Development, India ; Spanish Ministerio de Economia y Competitividad ; Conselleria d'Economia i Competitivitat and Conselleria d'Educaci, Cultura i Universitats of the Govern de les Illes Balears ; Netherlands Organisation for Scientific Research ; National Science Centre of Poland ; European Union ; Royal Society ; Scottish Funding Council ; Scottish Universities Physics Alliance ; National Aeronautics and Space Administration ; Hungarian Scientific Research Fund (OTKA) ; Lyon Institute of Origins (LIO) ; National Research Foundation of Korea ; Industry Canada ; Province of Ontario through the Ministry of Economic Development and Innovation ; Natural Science and Engineering Research Council, Canada ; Brazilian Ministry of Science, Technology, and Innovation ; Carnegie Trust ; Leverhulme Trust ; David and Lucile Packard Foundation ; Research Corporation ; Alfred P. Sloan Foundation ; NSF ; STFC ; MPS ; INFN ; CNRS ; Science and Technology Facilities Council ; Science and Technology Facilities Council: ST/L000938/1 Gravitational Waves ; Science and Technology Facilities Council: 1362895 ; Science and Technology Facilities Council: ST/L000962/1 ; Science and Technology Facilities Council: ST/I006285/1 Gravitational Waves ; Science and Technology Facilities Council: ST/L003465/1 ; Science and Technology Facilities Council: ST/L000962/1 Gravitational Waves ; Science and Technology Facilities Council: ST/I006285/1 ; Science and Technology Facilities Council: ST/I006242/1 Gravitational Waves ; Science and Technology Facilities Council: ST/J000019/1 ; Science and Technology Facilities Council: ST/N00003X/1 ; Science and Technology Facilities Council: ST/L000946/1 ; Science and Technology Facilities Council: ST/N000064/1 ; Science and Technology Facilities Council: ST/L000954/1 Gravitational Waves ; Science and Technology Facilities Council: ST/K000845/1 ; Science and Technology Facilities Council: ST/I006269/1 ; Science and Technology Facilities Council: ST/L000938/1 ; Science and Technology Facilities Council: Gravitational Waves ; Science and Technology Facilities Council: ST/K005014/1 ; Science and Technology Facilities Council: ST/I006269/1 Gravitational Waves ; We present the results of a search for long-duration gravitational wave transients in two sets of data collected by the LIGO Hanford and LIGO Livingston detectors between November 5, 2005 and September 30, 2007, and July 7, 2009 and October 20, 2010, with a total observational time of 283.0 days and 132.9 days, respectively. The search targets gravitational wave transients of duration 10-500 s in a frequency band of 40-1000 Hz, with minimal assumptions about the signal waveform, polarization, source direction, or time of occurrence. All candidate triggers were consistent with the expected background; as a result we set 90% confidence upper limits on the rate of long-duration gravitational wave transients for different types of gravitational wave signals. For signals from black hole accretion disk instabilities, we set upper limits on the source rate density between 3.4 x 10(-5) and 9.4 x 10(-4) Mpc(-3) yr(-1) at 90% confidence. These are the first results from an all-sky search for unmodeled long-duration transient gravitational waves.
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Prospects for Observing and Localizing Gravitational-Wave Transients with Advanced LIGO and Advanced Virgo
Advanced LIGO ; Science and Technology Facilities Council (STFC) of the United Kingdom ; Australian Research Council ; Council of Scientific and Industrial Research of India, Department of Science and Technology, India ; Science & Engineering Research Board (SERB), India ; Ministry of Human Resource Development, India ; Spanish Ministerio de Economia y Competitividad ; Conselleria d'Economia i Competitivitat and Conselleria d'Educacio, Cultura i Universitats of the Govern de les Illes Balears ; National Science Centre of Poland ; FOCUS Programme of Foundation for Polish Science ; European Union ; Royal Society ; Scottish Funding Council ; Scottish Universities Physics Alliance ; Lyon Institute of Origins (LIO) ; National Research Foundation of Korea ; Industry Canada ; Province of Ontario through the Ministry of Economic Development and Innovation ; National Science and Engineering Research Council Canada ; Brazilian Ministry of Science, Technology, and Innovation ; Research Corporation, Ministry of Science and Technology (MOST), Taiwan ; Kavli Foundation ; Science and Technology Facilities Council ; Science and Technology Facilities Council: ST/L000954/1 Gravitational Waves ; Science and Technology Facilities Council: ST/L000946/1 ; Science and Technology Facilities Council: ST/I006269/1 Gravitational Waves ; Science and Technology Facilities Council: ST/I006242/1 Gravitational Waves ; Science and Technology Facilities Council: ST/L003465/1 ; Science and Technology Facilities Council: ST/J000019/1 ; Science and Technology Facilities Council: ST/N000072/1 ; Science and Technology Facilities Council: ST/K000845/1 ; Science and Technology Facilities Council: ST/I006269/1 ; Science and Technology Facilities Council: ST/N000633/1 ; Science and Technology Facilities Council: ST/M000931/1 ; Science and Technology Facilities Council: ST/K005014/1 ; Science and Technology Facilities Council: PPA/G/S/2002/00652 ; Science and Technology Facilities Council: Gravitational Waves ; Science and Technology Facilities Council: ST/N00003X/1 ; We present a possible observing scenario for the Advanced LIGO and Advanced Virgo gravitational-wave detectors over the next decade, with the intention of providing information to the astronomy community to facilitate planning for multi-messenger astronomy with gravitational waves. We determine the expected sensitivity of the network to transient gravitational-wave signals, and study the capability of the network to determine the sky location of the source. We report our findings for gravitational-wave transients, with particular focus on gravitational-wave signals from the inspiral of binary neutron-star systems, which are considered the most promising for multi-messenger astronomy. The ability to localize the sources of the detected signals depends on the geographical distribution of the detectors and their relative sensitivity, and 90% credible regions can be as large as thousands of square degrees when only two sensitive detectors are operational. Determining the sky position of a significant fraction of detected signals to areas of 5 deg(2) to 20 deg(2) will require at least three detectors of sensitivity within a factor of similar to 2 of each other and with a broad frequency bandwidth. Should the third LIGO detector be relocated to India as expected, a significant fraction of gravitational-wave signals will be localized to a few square degrees by gravitational-wave observations alone.
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ASTROPHYSICAL IMPLICATIONS OF THE BINARY BLACK HOLE MERGER GW150914
United States National Science Foundation (NSF) ; Science and Technology Facilities Council (STFC) of the United Kingdom ; MaxPlanck- Society (MPS) ; State of Niedersachsen/Germany ; Australian Research Council ; Netherlands Organisation for Scientific Research ; EGO consortium ; Council of Scientific and Industrial Research of India, Department of Science and Technology, India ; Science AMP; Engineering Research Board (SERB), India ; Ministry of Human Resource Development, India ; Spanish Ministerio de Economia y Competitividad ; Conselleria d'Economia i Competitivitat and Conselleria d'Educacio Cultura i Universitats of the Govern de les Illes Balears ; National Science Centre of Poland ; European Union ; Royal Society ; Scottish Funding Council ; Scottish Universities Physics Alliance ; Lyon Institute of Origins (LIO) ; National Research Foundation of Korea, Industry Canada ; Province of Ontario through the Ministry of Economic Development and Innovation ; National Science and Engineering Research Council Canada ; Brazilian Ministry of Science, Technology, and Innovation ; Leverhulme Trust ; Research Corporation, Ministry of Science and Technology (MOST), Taiwan ; Kavli Foundation ; NSF ; STFC ; MPS ; INFN ; CNRS ; Science and Technology Facilities Council ; State of Niedersachsen/Germany: GEO600 ; Science and Technology Facilities Council: ST/K005014/1 ; Science and Technology Facilities Council: ST/L000938/1 Gravitational Waves ; Science and Technology Facilities Council: ST/N000072/1 ; Science and Technology Facilities Council: PPA/G/S/2002/00652 ; Science and Technology Facilities Council: ST/I006269/1 ; Science and Technology Facilities Council: ST/L000962/1 ; Science and Technology Facilities Council: ST/J00166X/1 ; Science and Technology Facilities Council: ST/M006735/1 ; Science and Technology Facilities Council: ST/I006285/1 Gravitational Waves ; Science and Technology Facilities Council: ST/J000019/1 Gravitational Waves ; Science and Technology Facilities Council: ST/I006285/1 ; Science and Technology Facilities Council: ST/J000019/1 ; Science and Technology Facilities Council: 1362895 ; Science and Technology Facilities Council: ST/M000931/1 ; Science and Technology Facilities Council: ST/L000962/1 Gravitational Waves ; Science and Technology Facilities Council: ST/L000938/1 ; Science and Technology Facilities Council: ST/K000845/1 ; Science and Technology Facilities Council: ST/I006242/1 Gravitational Waves ; Science and Technology Facilities Council: ST/L003465/1 ; Science and Technology Facilities Council: ST/G504284/1 ; Science and Technology Facilities Council: ST/I006269/1 Gravitational Waves ; Science and Technology Facilities Council: ST/L000954/1 Gravitational Waves ; Science and Technology Facilities Council: ST/N00003X/1 ; Science and Technology Facilities Council: Gravitational Waves ; Science and Technology Facilities Council: ST/N000633/1 ; Science and Technology Facilities Council: ST/L000946/1 ; The discovery of the gravitational-wave (GW) source GW150914 with the Advanced LIGO detectors provides the first observational evidence for the existence of binary black hole (BH) systems that inspiral and merge within the age of the universe. Such BH mergers have been predicted in two main types of formation models, involving isolated binaries in galactic fields or dynamical interactions in young and old dense stellar environments. The measured masses robustly demonstrate that relatively heavy BHs (greater than or similar to 25M(circle dot)) can form in nature. This discovery implies relatively weak massive-star winds and thus the formation of GW150914 in an environment with a metallicity lower than about 1/2 of the solar value. The rate of binary-BH (BBH) mergers inferred from the observation of GW150914 is consistent with the higher end of rate predictions (greater than or similar to 1 Gpc(-3) yr(-1)) from both types of formation models. The low measured redshift (z similar or equal to 0.1) of GW150914 and the low inferred metallicity of the stellar progenitor imply either BBH formation in a low-mass galaxy in the local universe and a prompt merger, or formation at high redshift with a time delay between formation and merger of several Gyr. This discovery motivates further studies of binary-BH formation astrophysics. It also has implications for future detections and studies by Advanced LIGO and Advanced Virgo, and GW detectors in space.
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