161 research outputs found
Rescue archaeological survey for the project of reconstruction of “Karantinata” fishing port, Asparuhovo neighbourhood, Varna
No full textThe rescue archaeological survey in Karantinata locality, Asparuhovo neighbourhood of Varna town, aimed to determine whether the implementation of the project for reconstruction of “Karantinata” fisherman port would affect underwater cultural heritage (fig. 1). The reason for conducting the study is a publication reporting that in the area there is an ancient breakwater and a shipwreck with amphorae (1964, 18 – 24, figs 12 – 21). Another breakwater is described in the same publication in the bay west of Cape Galata ( 1964, 22, fig. 14).The survey was conducted in May 2019 through geophysical research (bathymetric multibeam sonar and side-scan sonar mapping) followed by diving surveys (figs 2, 3). The data collected shows that in the area of construction of the new facilities of “Karantinata” fisherman port the bottom is sandy and without visible anomalies. The information about the ancient breakwaters and shipwreck east of the actual “Karantinata” jetty was verified by diving inspections. Only natural, irregularly shaped reef with north–south direction was recorded. The ashlar stone blocks described by G. Toncheva were not found, but it was observed that the sedimentary rocks in the area naturally split into rectangular pieces (fig. 4). Some amphorae shards as well as bricks and tile fragments were collected at the base of the scarp at a depth of 3–4 m during the diving inspection (fig. 5). The “amphorae deposits” mentioned by G. Toncheva were not located. The study regarding the project for Reconstruction of “Karantinata” Fishermen’s Port, Asparuhovo, Varna, was closed with the following conclusions: 1) There are no visible archaeological structures in the area of the investment intent and the wider water area east of it. 2) The claim of the presence of artificial ancient breakwaters in Lazuren Bryag locality (known also as “Karantinata”) and near Cape Galata should be rejected, since the observed linear stone structures are natural geological formations of the Galata Formation. 3) The archaeological materials collected in the “Karantinata” waters are too sparse and asynchronous to be recognized as a ship cargo. However, this does not exclude the possibility that the finds could mark an anchorage that had previously functioned in the area
Rescue archaeological investigations in the harbour of Sozopol
No full textThe rescue investigation was carried out by the Centre for Underwater Archaeology in May 2020 in part of Sozopol’s harbour that has not been archaeologically explored before (Dimitrov et al. 2020). They were funded by Sozopol municipality under a project for anchoring of floating piers (fig. 1). The investigations comprised geophysical investigation, archaeological excavations, creation and analysis of a GIS database, and underwater surveys of the central part of the harbour. Archaeological excavations were carried out in a single grid-square (Z) located 7 m SW of the outermost anchor of the proposed floating piers. Grid-square Z was set on the flat sandy-mud bottom at a depth of -4.1 m (from thesurface). From that depth (modern bottom) down to -4.7/4.8 m, the entire surface of the grid-square was excavated, and from -4.8 m downwards only its western half, revealing the following layers (fig. 2): - Bottom of the modern harbour – from -4.1 м to -4.7/4.8 m.- Harbour accumulation from the Ottoman period – from -4.7/4.8 to -4.9/5.1 m.- Harbour accumulation from Classical Antiquity – from -4.9/5.1 to -5.5/5.6 m. It contains numerous wellpreserved materials of utilitarian character, mostly relatively modest tableware, cooking ware, and amphorae (fig. 3).The earliest vases could be dated to c. 600 BC. The chronological distribution of the finds is uneven, the 6th and the5th c. BC being best represented. After a clear drop in the 4th c. BC, there may be a hiatus from about the middle of thecentury to the second quarter of the 3rd c. BC. The later Hellenistic and the Roman periods are also attested with not sonumerous vases.- Sterile layer without archaeological materials, explored with a trench down to -7.4 m.To summarize, the sector of Sozopol’s harbour excavated in 2020 has not been dredged during port constructionworks and its stratigraphy is intact and illustrates an historical development from the end of the 7th c. BC to present day.No remains of prehistoric settlements were discovered here.The analysis of all available data indicates that the construction of the modern harbour of Sozopol in 1927 andthe reconstructions in the late 1980s have destroyed to a great extent the archaeological remains underwater along thecentre line of the port (figs. 4 and 5). However, in the eastern half of the harbour, a sector is identified with intact stratafrom the historic periods and prehistory
Underwater archaeological survey of Nesebar Aquatory
No full textThe underwater archaeological heritage of Nesebar, ancient Mesambria, was surveyed from 1960 to 1984. L. Ognenova discovered remains from the fortification system of the ancient town, dated to Pre-Greek, Classic, Hellenistic and Late Antique period (Preshlenov 2012). Most of the underwater monuments from the northern side of Nesebar peninsula were buried under coastal protection facilities built in 1980s. In 2017 the Center for Underwater Archaeology resumed the study. Most of the known and some unknown monuments were discovered and documented. These were walls of massive slabs (fig. 3, fig. 1. 2, 7) or well processed blocks (fig. 2, fig. 1. 4–6) associated with the Greek polis, Late Antique walls of stones with mortar (fig. 1. 1) as well as in opus mixtum (fig. 1. 3, 10). A wall dated to the Pre-Greek period was not found. The majority of these structures laybetween 2 and 3 m depth. Only one wall of blocks (fig. 1. 6) is at 5,5 m depth (Preshlenov 2012, 503, fig. 5, 509–512). A marine geophysical survey was conducted
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COLOR SUPERCONDUCTIVITY, INSTANTONS AND PARITY (NON?)-CONSERVATION AT HIGH BARYON DENSITY-VOLUME 5.
No full textThis one day Riken BNL Research Center workshop was organized to follow-up on the rapidly developing theoretical work on color super-conductivity, instanton dynamics, and possible signatures of parity violation in strong interactions that was stimulated by the talk of Frank Wilczek during the Riken BNL September Symposium. The workshop was held on November 11, 1997 at the center with over 30 participants. The program consisted of four talks on theory in the morning followed by two talks in the afternoon by experimentalists and open discussion. Krishna Rajagopal (MIT) first reviewed the status of the chiral condensate calculations at high baryon density within the instanton model and the percolation transition at moderate densities restoring chiral symmetry. Mark Alford (Princeton) then discussed the nature of the novel color super-conducting diquark condensates. The main result was that the largest gap on the order of 100 MeV was found for the 0{sup +} condensate, with only a tiny gap << MeV for the other possible 1{sup +}. Thomas Schaefer (INT) gave a complete overview of the instanton effects on correlators and showed independent calculations in collaboration with Shuryak (SUNY) and Velkovsky (BNL) confirming the updated results of the Wilczek group (Princeton, MIT). Yang Pang (Columbia) addressed the general question of how breaking of discrete symmetries by any condensate with suitable quantum numbers could be searched for experimentally especially at the AGS through longitudinal A polarization measurements. Nicholas Samios (BNL) reviewed the history of measurements on {Lambda} polarization and suggested specific kinematical variables for such analysis. Brian Cole (Columbia) showed recent E910 measurements of {Lambda} production at the AGS in nuclear collisions and focused on the systematic biases that must be considered when looking for small symmetry breaking effects. Lively discussions led by Robert Jaffe (MIT) focused especially on speculations on the still unknown signatures of 0{sup +} color super-conductivity which of course would not be observable via discrete symmetry breaking
Transições de fase na matéria de quarks magnetizada com repulsão vetorial
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas, Programa de Pós-Graduação em Física, Florianópolis, 2015.Neste trabalho investigamos as transições de fase na matéria de quarks magnetizada usando o modelo de NJL com dois sabores na presença de acoplamento vetorial repulsivo (GV). Verificamos que a contribuição vetorial produz o encolhimento da linha de transição de primeira ordem e pode favorecer o mecanismo de back-bending no regime de acoplamento forte. Este fato permite conciliar alguns resultados da rede com as previsões teóricas sobre a existência de um ponto crítico no diagrama de fases da QCD. Analisamos como a ação de um campo magnético (B) intenso na matéria de quarks tende a fortalecer a região de primeira ordem e que também determina um padrão oscilatório na densidade. Concluímos que os efeitos opostos do acoplamento vetorial e do campo magnético na restauração da simetria quiral levam a um desdobramento de múltiplas fases magnetizadas. A ação combinada de B e GV pode originar linhas de coexistência no diagrama de fases que apresentam um comportamento exótico similar ao observado para a transição sólido-líquido da água. Mostramos como a influência da repulsão vetorial deve estabilizar fases magnéticas de densidade intermediária e que certas combinações dos parâmetros B e GV determinam pontos triplos no diagrama de fases. Exploramos as propriedades magnéticas anisotrópicas sobre os quarks e como a contribuição vetorial deve afetar a magnetização induzida determinando um comportamento diamagnético para o sistema.Abstract : In this work we investigate the phase diagram of dense magnetizedquark matter in the framework of the two-flavor Nambu-Jona-Lasiniomodel when a repulsive vector coupling (GV ) is present. We verifythat the vector contribution could shrink the first order transition lineand can support the back-bending mechanism under a strong couplingregime. This result allows one to conciliate some lattice results withtheoretical predictions about the existence of a critical point in theQCD phase diagram. Our analysis shows how an intense magnetic field(B) acts in the quark matter, strengthening the coexistence region inthe phase diagram and setting an oscillatory pattern in density values.The opposite effect of the vector coupling and magnetic field in thechiral symmetry restoration leads to a splitting of multiple magneticphases. The combined action of B and GV gives rise to coexistencelines which can render an exotic behavior resembling the solid-liquidtransition observed in the water phase diagram. We show how thevector repulsion stabilizes the intermediary magnetic phases and thatcertain B and GV parametric combinations can cause a triple point toappear in the phase diagram. We also study the anisotropic propertiesof magnetized quark matter and how the vector-like contribution affectsthe induced magnetization leading to a diamagnetic behavior
Signals of the QCD Phase Transition in the Heavens
No full textThe modern phase diagram of strongly interacting matter reveals a rich structure at high-densities
due to phase transitions related to the chiral symmetry of quantum chromodynamics (QCD) and
the phenomenon of color superconductivity. These exotic phases have a significant impact on
high-density astrophysics, such as the properties of neutron stars, and the evolution of astrophysical systems as proto-neutron stars, core-collapse supernovae and neutron star mergers. Most recent pulsar mass measurements and constraints on neutron star radii are critically discussed.
Astrophysical signals for exotic matter and phase transitions in high-density matter proposed recently in the literature are outlined. A strong first order phase transition leads to the emergence of a third family of compact stars besides white dwarfs and neutron stars. The different microphysics of quark matter results in an enhanced r-mode stability window for rotating compact stars compared to normal neutron stars. Future telescope and satellite data will be used to extract signals from phase transitions in dense matter in the heavens and will reveal properties of the phases of dense QCD. Spectral line profiles out of x-ray bursts will determine the mass-radius ratio of compact stars. Gravitational wave patterns from collapsing neutron stars or neutron star mergers will even be able to constrain the stiffness of the quark matter equation of state. Future astrophysical data can therefore provide a crucial cross-check to the exploration of the QCD phase diagram with the heavy-ion program of the CBM detector at the FAIR facility
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