1,572 research outputs found
Possible cosmological implications of the quark-hadron phase transition
No full textBorghini N, Cottingham WN, Mau RV. Possible cosmological implications of the quark-hadron phase transition. Journal of Physics G Nuclear and Particle Physics. 2000;26(6):771-785.We study the quark-hadron phase transition within an effective model of QCD, and find that in a reasonable range of the main parameters of the model, bodies with quark content between 10(-2) and 10 solar masses can have been formed in the early universe. In addition, we show that a significant amount of entropy is released during the transition. This may imply the existence of a higher baryon number density than is usually expected at temperatures above the QCD scale. The cosmological QCD transition may then provide a natural way of decreasing the high baryon asymmetry created by an Affleck-Dine-like mechanism down to the value required by primordial nucleosynthesis
Toward monitoring and estimating the size of the HFO-contaminated seabed around a shipwreck using MBES backscatter data
No full textFunding Information: The authors are grateful to three anonymous reviewers for their constructive criticism and valuable comments. The authors express their gratitude to the Maritime Institute in Gdansk for making the final version of the report (Maritime Institute in Gdansk, 2016) available. The second author appreciates the support of the Gdynia Maritime University in funding this research through internal grant WN/PZ/2021/02. Funding Information: The second author appreciates the support of the Gdynia Maritime University in funding this research through internal grant WN/PZ/2021/02 . Publisher Copyright: © 2021Despite a progressive reduction of oil spills caused by the activity of maritime transportation, the latent sources of pollution still exist. Although the harmful impact of heavy fuel oil (HFO) on the marine environment is widely known, many shipwrecks cause contamination of the surrounding areas. In this paper, an approach to monitor the area of the HFO spill around a shipwreck is made using a bottom backscattering strength (BBS) obtained by a multibeam echosounder (MBES). As a case study, the s/s Stuttgart wreck located in the Gulf of Gdansk (Poland) is verified. Two different measurement campaigns have been carried out in shallow waters using low (190 kHz) and high (420 kHz) MBES frequency. The results indicate that the polluted area around s/s Stuttgart was estimated at 49.1 ha, which is around 18.3% more in comparison to the geological surveys made four years earlier.Peer reviewe
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