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378 results on '"Molnár, Mihály"'

6. Rapid 14C excursion at 3372-3371 BCE not observed at two different locations, a comment on Wang et al. (2017)

Author

Jull, AJ Timothy, Panyushkina, Irina, Salzer, Matthew, Baisan, Chris, Molnar, Mihaly, Varga, Tamas, Wacker, Lukas, Brehm, Nicholas, and Tegel, Willy

Subjects
Physics - Geophysics, Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Solar and Stellar Astrophysics
Abstract

Excursions in the carbon-14 record measured in tree rings are attributed to various high energy but short-lived cosmic effects. So far, rapid changes at 774-775 CE, 993-994 CE and 660 BCE have been convincingly interpreted as due to rapid changes in solar cosmic-ray flux, usually accredited with reproduction of the events in trees at different locations and different laboratories, and followed with equivalent peaks of other cosmogenic isotopes in polar ice cores. In 2017, Wang et al. proposed a new event at 3372-3371 BCE based on a single set of annual 14C data measured on a floating series of tree rings sampled from a buried specimen of Chinese wingnut tree (Pterocarya stenoptera). We attempted to reproduce this event in tree rings of an absolutely dated bristlecone pine specimen (Pinus longaeva) from the White Mountains, California USA and a subfossil European oak (Quercus sp.) from the Moselle River Valley in France. Unfortunately, we are unable to determine whether there is any rapid 14C excursion during this time, although the regular 11-year Schwabe cycle is clearly observable. Therefore, the presence of a cosmic-ray event as suggested at 3372-3371 BCE cannot be confirmed. It is possible the exposed 14C spike occurred at some other time, the absolute age of which we cannot determine unless the precise calendar age of the Chinese wingnut wood is properly crossdated, although the other data of Wang et al. (2017) is not inconsistent with our records. In either case, this is important because the frequency of such extreme cosmic events needs to be well-documented to assess the likelihood of similar high-energy effects occurring in the future., Comment: 3 figures, 8 pages

Published
2020

8. Palaeoenvironmental Changes During the Last Glacial Period in the Ciomadul Hills

Author

Magyari, Enikő K., Vincze, Ildikó, Tóth, Mónika, Hubay, Katalin, Veres, Daniel, Haliuc, Aritina, Molnár, Mihály, Jakab, Gusztáv, Braun, Mihály, Schäbitz, Frank, Máthé, István, Buczkó, Krisztina, Karátson, Dávid, editor, Veres, Daniel, editor, Gertisser, Ralf, editor, Magyari, Enikő K., editor, Jánosi, Csaba, editor, and Hambach, Ulrich, editor

Published
2022
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11. Case Study from Máza Brickyard (SW-Hungary): Paleoecology and Sediment Accumulation Changes in the Southern Part of the Carpathian Basin.

Author

Molnár, Dávid, Makó, László, Molnár, Mihály, and Sümegi, Pál

Subjects
PLEISTOCENE-Holocene boundary, CLUSTER analysis (Statistics), MULTIVARIATE analysis, MOLLUSKS, PALEOECOLOGY
Abstract

The loess–paleosol profile of Máza brickyard in SW Hungary was investigated through multivariate analyses of malacofauna and sedimentological analyses. The aim was to reconstruct the complex developmental history of both sediment and malacofauna. Three age–depth models were calculated, and the best-fit model, the OxCal P-sequence, was chosen for further analysis. The profile overlays the MIS3 and MIS2, beginning at approximately 45,000–50,000 cal BP and ending at the Pleistocene/Holocene boundary. The accumulation rates were two periods of intensive accumulation, equal to those observed in the Bácska Loess Plateau in Hungary, and two periods of decreased accumulation. Between ~38,000 and 31,000 cal BP, a decreased accumulation period was observed in Máza and other profiles from the Bácska Loess Plateau, indicating a common weak accumulation period at the end of MIS3. Correspondence and cluster analyses provided a higher-resolution paleoecological reconstruction, revealing a more detailed picture of the evolution of the studied section. The presence of thermophilous gastropod species with a high contribution to the correspondence analysis was significant in the sections. Although Granaria frumentum, Helicopsis striata, Chondrula tridens, and Pupilla triplicata were not significant species in the Máza malacofauna as a whole, their presence was associated with warming periods and the emergence of open vegetation. [ABSTRACT FROM AUTHOR]

Published
2024
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32. A speleothem record of seasonality and moisture transport around the 8.2 ka event in Central Europe (Vacska Cave, Hungary).

Author

Demény, Attila, Czuppon, György, Kern, Zoltán, Hatvani, István Gábor, Topál, Dániel, Karlik, Máté, Surányi, Gergely, Molnár, Mihály, Kiss, Gabriella Ilona, Szabó, Máté, Shen, Chuan-Chou, Hu, Hsun-Ming, and May, Zoltán

Subjects
SPELEOTHEMS, OXYGEN isotopes, STALACTITES & stalagmites, HYDROGEN isotopes, CAVES, STABLE isotopes, OXYGEN in water, MOISTURE, CALCITE
Abstract

A stalagmite was collected in northern Hungary from the Vacska Cave, where monitoring and ventilation-based site selection had been conducted. The stalagmite covers the 10–8 ka (relative to AD 1950) period, including the so-called 8.2 ka event, and showed preceding signs of climate change that were evaluated by petrographic observations, 14C activities, Sr concentrations, and stable isotope compositions of calcite and inclusion-hosted water. Comparisons of speleothem records show that isotope peaks at ca. 8.5 ka are related to a regional climate anomaly, rather than to a continental-scale event. In accordance with regional proxy records, the 8.2 ka event was associated with a series of temperature and precipitation amount changes, starting with cooling and a reduction in the winter-to-summer precipitation ratio, and then becoming a humid and warm phase at 8.15 ka. X-ray diffraction-based crystallinity parameter (FWHM) values provided evidence for diagenetic alteration of the stable oxygen isotope compositions of inclusion waters. Nevertheless, the stable hydrogen isotope compositions of inclusion waters and the oxygen isotope values of the host calcite revealed elevated d-excess values, and therefore increased Mediterranean moisture contribution during the 8.2 ka event, which indirectly indicate the southward displacement of moisture transport from the Atlantic Ocean. [ABSTRACT FROM AUTHOR]

Published
2024
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35. Možnosti a limity radiouhlíkového datování se zaměřením na netypické archeologické vzorky

Author

Bíšková, Jarmila, primary, Brychová, Veronika, additional, Demján, Peter, additional, Dreslerová, Dagmar, additional, Frank Danielisová, Alžběta, additional, Hošková, Kristýna, additional, John, David, additional, Koštová, Nikola, additional, Limburský, Petr, additional, Molnár, Mihály, additional, Moravcová, Alice, additional, Pachnerová Brabcová, Kateřina, additional, Petrová, Markéta, additional, Světlík, Ivo, additional, Šneberger, Jiří, additional, Tecl, Josef, additional, and Valášek, Vojtěch, additional

Published
2023
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40. Toward Developing Techniques─Agnostic Machine Learning Classification Models for Forensically Relevant Glass Fragments

Author

Omer Kaspi, Osnat Israelsohn-Azulay, Zidon Yigal, Hila Rosengarten, Matea Krmpotić, Sabrina Gouasmia, Iva Bogdanović Radović, Pasi Jalkanen, Anna Liski, Kenichiro Mizohata, Jyrki Räisänen, Zsolt Kasztovszky, Ildikó Harsányi, Raghunath Acharya, Pradeep K. Pujari, Molnár Mihály, Mihaly Braun, Nahum Shabi, Olga Girshevitz, Hanoch Senderowitz, Materials Physics, and Department of Physics

Subjects
Induced breakdown spectroscopy, Refractive-index, General Chemical Engineering, General Chemistry, Precision, Library and Information Sciences, 114 Physical sciences, La-icp-ms, Computer Science Applications, PIXE, LA-ICP-MS, SEM-EDS, PIGE, INAA, PGAA, car window glass fragments, Machine Learning, Databases, Forensic chemistry, Elemental composition, Discrimination, Tool, Plasma-mass spectrometry, Accuracy
Abstract

Glass fragments found in crime scenes may constitute important forensic evidence when properly analyzed, for example, to determine their origin. This analysis could be greatly helped by having a large and diverse database of glass fragments and by using it for constructing reliable machine learning (ML)-based glass classification models. Ideally, the samples that make up this database should be analyzed by a single accurate and standardized analytical technique. However, due to differences in equipment across laboratories, this is not feasible. With this in mind, in this work, we investigated if and how measurement performed at different laboratories on the same set of glass fragments could be combined in the context of ML. First, we demonstrated that elemental analysis methods such as particle-induced X-ray emission (PIXE), laser ablation induct i v e l y coupled plasma mass spectrometry (LA-ICP-MS), scanning electron microscopy with energy-dispersive X-ray spectrometry (SEM-EDS), particle-induced Gamma-ray emission (PIGE), instrumental neutron activation analysis (INAA), and prompt Gamma-ray neutron activation analysis (PGAA) could each produce lab-specific ML-based classification models. Next, we determined rules for the successf u l combinations of data from different laboratories and techniques and demonstrated that when followed, they give rise to improved models, and conversely, poor combinations wi l l lead to poor-performing models. Thus, the combination of PIXE and LA-ICP-MS improves the performances by similar to 10-15%, while combining PGAA with other techniques provides poorer performances in comparison with the lab-specific models. Finally, we demonstrated that the poor performances of the SEM-EDS technique, sti l l in use by law enforcement agencies, could be greatly improved by replacing SEM-EDS measurements for Fe and Ca by PIX E measurements for these elements. These findings suggest a process whereby forensic laboratories using different elemental analysis techniques could upload their data into a unified database and get reliable classification based on lab-agnostic models. This in tur n brings us closer to a more exhaustive extraction of information from glass fragment evidence and furthermore may form the basis for international-wide collaboration between law enforcement agencies.

Published
2022

41. Interdisciplinary Analyses of Bronze Age Communities from Western Hungary Reveal Complex Population Histories

Author

Gerber, Dániel, primary, Szeifert, Bea, additional, Székely, Orsolya, additional, Egyed, Balázs, additional, Gyuris, Balázs, additional, Giblin, Julia I, additional, Horváth, Anikó, additional, Köhler, Kitti, additional, Kulcsár, Gabriella, additional, Kustár, Ágnes, additional, Major, István, additional, Molnár, Mihály, additional, Palcsu, László, additional, Szeverényi, Vajk, additional, Fábián, Szilvia, additional, Mende, Balázs Gusztáv, additional, Bondár, Mária, additional, Ari, Eszter, additional, Kiss, Viktória, additional, and Szécsényi-Nagy, Anna, additional

Published
2023
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47. Multi‐disciplinary study of a late Pleistocene woolly rhinoceros found in the Pannonian Basin and implications for the contemporaneous palaeoenvironment.

Author

Gasparik, Mihály, Major, István, Lisztes‐Szabó, Zsuzsa, Magyari, Enikő, Szabó, Bence, Pandolfi, Luca, Borel, Antony, Futó, István, Horváth, Anikó, Kiss, Gabriella Ilona, Molnár, Mihály, Csík, Attila, and Markó, András

Subjects
RHINOCEROSES, LAST Glacial Maximum, TUNDRAS, PLEISTOCENE Epoch, RADIOCARBON dating, ATMOSPHERIC temperature
Abstract

Excavation campaigns conducted at the Pécel‐Kis hársas site (Hungary) between 2014 and 2017 yielded the remains of a mature female woolly rhinoceros (Coelodonta antiquitatis) and six lithic artefacts. Radiocarbon dating confirmed that the rhinoceros died ca. 20.4k cal a bp, at the very end of the Last Glacial Maximum and, considering the position of the artefacts when found, it was probably killed by Epigravettian hunters. Based on dental analyses of the specimen, a vigorous lichen‐ (and possibly moss‐)consuming diet could be inferred for the end of the animal's lifetime. Based on Sr results, we can exclude the possibility of long‐range migration. In accordance with the optimum environmental demands of the foraging lichen, the low δ18O value of osseous material implies a relatively cold contemporaneous climate with a calculated mean annual air temperature of around 0.7 °C. Meanwhile, the extremely low δ15N value may have resulted from the proximity of the discontinuous permafrost zone and some intensive soil dislocation. Consequently, poor vegetation and an open, tundra‐like habitat can be assumed to have been dominant at the site at that time, which is also supported by palaeoenvironmental modeling experiments. [ABSTRACT FROM AUTHOR]

Published
2023
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