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Institution

University of Turku

EducationTurku, Finland
About: University of Turku is a education organization based out in Turku, Finland. It is known for research contribution in the topics: Population & Galaxy. The organization has 16296 authors who have published 45124 publications receiving 1505428 citations. The organization is also known as: Turun yliopisto & Åbo universitet.


Papers
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Journal ArticleDOI
17 Apr 2008-Nature
TL;DR: The observations confirm the binary nature of the system and also provide evidence for the loss of orbital energy in agreement (within 10 per cent) with the emission of gravitational waves from the system.
Abstract: Black holes are firmly established in astronomy and in the public imagination. Yet the concept still depends on the assumption that Einstein's general theory of relativity is the correct theory of gravitation. Tests of general relativity in a strong gravitational field are best conducted in systems containing black holes. Valtonen et al. report such a test in a close binary system of two proposed black holes in the quasar OJ 287. This quasar shows quasiperiodic optical outbursts at 12-year intervals, with two outburst peaks per interval. The latest outburst in September 2007 was within a day of the time predicted by the binary black hole model and general relativity. Tests of Einstein's general theory of relativity in a strong gravitational field may be best conducted in systems containing black holes. Such a test in a close binary system of two proposed black holes in the quasar OJ287 is reported. This quasar shows quasi-periodic optical outbursts at 12 year intervals, with two outburst peaks per interval. The latest outburst occurred in September 2007, within a day of the time predicted by the binary black hole model and the general relativity. Tests of Einstein’s general theory of relativity have mostly been carried out in weak gravitational fields where the space-time curvature effects are first-order deviations from Newton’s theory1,2,3,4,5,6. Binary pulsars4 provide a means of probing the strong gravitational field around a neutron star, but strong-field effects may be best tested in systems containing black holes7,8. Here we report such a test in a close binary system of two candidate black holes in the quasar OJ 287. This quasar shows quasi-periodic optical outbursts at 12-year intervals, with two outburst peaks per interval9,10. The latest outburst occurred in September 2007, within a day of the time predicted by the binary black-hole model and general relativity11. The observations confirm the binary nature of the system and also provide evidence for the loss of orbital energy in agreement (within 10 per cent) with the emission of gravitational waves from the system12. In the absence of gravitational wave emission the outburst would have happened 20 days later13.

398 citations

Journal ArticleDOI
TL;DR: The prevalence, age and gender differences, and various types of bullying, as well as why it happens and how long it lasts, are discussed, starting from the large surveys carried out in western countries and to a lower extent in low- and middle-income countries.
Abstract: During the school years, bullying is one of the most common expressions of violence in the peer context. Research on bullying started more than forty years ago, when the phenomenon was defined as 'aggressive, intentional acts carried out by a group or an individual repeatedly and over time against a victim who cannot easily defend him- or herself'. Three criteria are relevant in order to define aggressive behaviour as bullying: (1) repetition, (2) intentionality and (3) an imbalance of power. Given these characteristics, bullying is often defined as systematic abuse of power by peers. It is recognised globally as a complex and serious problem. In the present paper, we discuss the prevalence, age and gender differences, and various types of bullying, as well as why it happens and how long it lasts, starting from the large surveys carried out in western countries and to a lower extent in low- and middle-income countries. The prevalence rates vary widely across studies; therefore, specific attention will be devoted to the definition, time reference period and frequency criterion. We will also focus on risk factors as well as short- and long-term outcomes of bullying and victimisation. Finally, a section will be dedicated to review what is known about effective prevention of bullying.

398 citations

Journal ArticleDOI
TL;DR: In this article, the authors show that the full content of the uncertainty principle also includes its positive role as a condition ensuring that mutually exclusive experimental options can be reconciled if an appropriate trade-off is accepted.

398 citations

Journal ArticleDOI
TL;DR: Using a careful anaerobic bacteriological technique, bacteria were shown to be eliminated from infected root canals before the endodontic treatment was finished by root filling and the majority of the 79 lesions healed completely or decreased in size in such a way that they could be expected to heal.
Abstract: Using a careful anaerobic bacteriological technique, bacteria were shown to be eliminated from infected root canals before the endodontic treatment was finished by root filling. Healing of the periapical lesions of the teeth was followed for 2–5 yr. The majority of the 79 lesions healed completely or decreased in size in such a way that they could be expected to heal. In 5 cases there was no or only an insignificant decrease in the size of the lesions. Two of these lesions were shown to contain bacteria of the species Actinomyces or Arachnid. In another case there were dentin chips in the periapical tissue. Periapical lesions which fail to heal in spite of careful bacteriological monitoring of the endodontic treatment may in some cases be due to an establishment of the bacteria outside the root canal in the periapical tissue. In these sites, the bacteria are inaccessible to conventional endodontic treatment.

397 citations


Authors

Showing all 16461 results

NameH-indexPapersCitations
Kari Alitalo174817114231
Mika Kivimäki1661515141468
Jaakko Kaprio1631532126320
Veikko Salomaa162843135046
Markus W. Büchler148154593574
Eugene C. Butcher14644672849
Steven Williams144137586712
Terho Lehtimäki1421304106981
Olli T. Raitakari1421232103487
Pim Cuijpers13698269370
Jeroen J. Bax132130674992
Sten Orrenius13044757445
Aarno Palotie12971189975
Stefan W. Hell12757765937
Carlos López-Otín12649483933
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
2023102
2022290
20212,673
20202,688
20192,407
20182,189