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2,202 results on '"Németh, Á."'

1. Modelling the age distribution of longevity leaders

Author

Kiss, Csaba, Németh, László, and Vető, Bálint

Subjects
Quantitative Biology - Populations and Evolution, Mathematics - Probability, 60J25, 60K20
Abstract

Human longevity leaders with remarkably long lifespan play a crucial role in the advancement of longevity research. In this paper, we propose a stochastic model to describe the evolution of the age of the oldest person in the world by a Markov process, in which we assume that the births of the individuals follow a Poisson process with increasing intensity, lifespans of individuals are independent and can be characterized by a gamma-Gompertz distribution with time-dependent parameters. We utilize a dataset of the world's oldest person title holders since 1955, and we compute the maximum likelihood estimate for the parameters iteratively by numerical integration. Based on our preliminary estimates, the model provides a good fit to the data and shows that the age of the oldest person alive increases over time in the future. The estimated parameters enable us to describe the distribution of the age of the record holder process at a future time point., Comment: 14 pages, 5 figures

Published
2024
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2. A spectroscopic and kinematic survey of fast hot subdwarfs

Author

Geier, S., Heber, U., Irrgang, A., Dorsch, M., Bastian, A., Neunteufel, P., Kupfer, T., Bloemen, S., Kreuzer, S., Möller, L., Schindewolf, M., Schneider, D., Ziegerer, E., Pelisoli, I., Schaffenroth, V., Barlow, B. N., Raddi, R., Geier, S. J., Reindl, N., Rauch, T., Nemeth, P., and Gänsicke, B. T.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Astrophysics of Galaxies
Abstract

Hot subdwarfs (sdO/B) are the stripped helium cores of red giants formed by binary interactions. Close hot subdwarf binaries with massive white dwarf companions have been proposed as possible progenitors of thermonuclear supernovae type Ia (SN Ia). If the supernova is triggered by stable mass transfer from the helium star, the companion should survive the explosion and should be accelerated to high velocities. The hypervelocity star US 708 is regarded as the prototype for such an ejected companion. To find more of those objects we conducted an extensive spectroscopic survey. Candidates for such fast stars have been selected from the spectroscopic database of the Sloan Digital Sky Survey (SDSS) and several ground-based proper motion surveys. Follow-up spectroscopy has been obtained with several 4m- to 10m-class telescopes. Combining the results from quantitative spectroscopic analyses with space-based astrometry from \textit{Gaia} Early Data Release 3 (EDR3) we determined the atmospheric and kinematic parameters of 53 fast hot subdwarf stars. None of these stars is unbound to the Galaxy, although some have Galactic restframe velocities close to the Galactic escape velocity. 21 stars are apparently single objects, which crossed the Galactic disc within their lifetimes in the sdO/B stage and could be regarded as potential candidates for the SN Ia ejection scenario. However, the properties of the full sample are more consistent with a pure old Galactic halo population. We therefore conclude that the fast sdO/B stars we found are likely to be extreme halo stars., Comment: 22 pages, A&A accepted

Published
2024
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3. Terahertz Emission From Diamond Nitrogen-Vacancy Centers

Author

Kollarics, Sándor, Márkus, Bence Gábor, Kucsera, Robin, Thiering, Gergő, Gali, Ádám, Németh, Gergely, Kamarás, Katalin, Forró, László, and Simon, Ferenc

Subjects
Physics - Optics, Condensed Matter - Other Condensed Matter, Physics - Applied Physics
Abstract

Coherent light sources emitting in the terahertz range are highly sought after for fundamental research and applications. THz lasers rely on achieving population inversion. We demonstrate the generation of THz radiation using nitrogen-vacancy (NV) centers in a diamond single crystal. Population inversion is achieved through the Zeeman splitting of the $S=1$ state in $15\ \text{T}$, resulting in a splitting of $0.42\ \text{THz}$, where the middle $S_z=0$ sublevel is selectively pumped by visible light. To detect the THz radiation, we utilize a phase-sensitive THz setup, optimized for electron spin resonance measurements (ESR). We determine the spin-lattice relaxation time up to $15\ \text{T}$ using the light-induced ESR measurement, which shows the dominance of phonon-mediated relaxation and the high efficacy of the population inversion. The THz radiation is tunable by the magnetic field, thus these findings may lead to the next generation of tunable coherent THz sources., Comment: 45 pages, 14 figures

Published
2024
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4. A seven-Earth-radius helium-burning star inside a 20.5-min detached binary

Author

Lin, Jie, Wu, Chengyuan, Xiong, Heran, Wang, Xiaofeng, Nemeth, Peter, Han, Zhanwen, Li, Jiangdan, Elias-Rosa, Nancy, Salmaso, Irene, Filippenko, Alexei V., Brink, Thomas G., Yang, Yi, Chen, Xuefei, Yan, Shengyu, Zhang, Jujia, Guo, Sufen, Cai, Yongzhi, Mo, Jun, Xi, Gaobo, Liu, Jialian, Guo, Jincheng, Xia, Qiqi, Xiang, Danfeng, Li, Gaici, Li, Zhenwei, Zheng, WeiKang, Zhang, Jicheng, Liu, Qichun, Guo, Fangzhou, Chen, Liyang, and Li, Wenxiong

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

Binary evolution theory predicts that the second common envelope (CE) ejection can produce low-mass (0.32-0.36 Msun) subdwarf B (sdB) stars inside ultrashort-orbital-period binary systems, as their helium cores are ignited under nondegenerate conditions. With the orbital decay driven by gravitational-wave (GW) radiation, the minimum orbital periods of detached sdB binaries could be as short as ~20 minutes. However, only four sdB binaries with orbital periods below an hour have been reported so far, while none of them has an orbital period approaching the above theoretical limit. Here we report the discovery of a 20.5-minute-orbital-period ellipsoidal binary, TMTS J052610.43+593445.1, in which the visible star is being tidally deformed by an invisible carbon-oxygen white dwarf (WD) companion. The visible component is inferred to be an sdB star with a mass of ~0.33 Msun, approaching that of helium-ignition limit, although a He-core WD cannot be completely ruled out. In particular, the radius of this low-mass sdB star is only 0.066 Rsun, about seven Earth radii, possibly representing the most compact nondegenerate star ever known. Such a system provides a key clue to map the binary evolution scheme from the second CE ejection to the formation of AM CVn stars having a helium-star donor, and it will also serve as a crucial verification binary of space-borne GW detectors in the future., Comment: 24 pages, 11 figures, 1 table, published on Nature Astronomy, URL: https://www.nature.com/articles/s41550-023-02188-2

Published
2023
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5. Unveiling the evolutionary state of three B supergiant stars: PU Gem, $\epsilon$ CMa and $\eta$ CMa

Author

Arias, Julieta P. Sánchez, Németh, Péter, de Almeida, Elisson S. G., Diaz, Matias A. Ruiz, Kraus, Michaela, and Haucke, Maximiliano

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

We aim to combine asteroseismology, spectroscopy, and evolutionary models to establish a comprehensive picture of the evolution of Galactic blue supergiant stars (BSG). To start such an investigation, we selected three BSG candidates for our analysis: HD 42087 (PU Gem), HD 52089 ($\epsilon$ CMa) and HD 58350 ($\eta$ CMa). These stars show pulsations and were suspected to be in an evolutionary stage either preceding or succeding the red supergiant (RSG) stage. For our analysis, we utilized the 2-min cadence TESS data to study the photometric variability and obtained new spectroscopic observations at the CASLEO observatory. We calculated CMFGEN non-LTE radiative transfer models and derived stellar and wind parameters using the iterative spectral analysis pipeline XTGRID. The spectral modeling was limited to changing only the effective temperature, surface gravity, CNO abundances, and mass-loss rates. Finally, we compared the derived metal abundances with predictions from Geneva stellar evolution models. The frequency spectra of all three stars show either stochastic oscillations, nonradial strange modes, or a rotational splitting. We conclude that the rather short sectoral observing windows of TESS prevent establishing a reliable mode identification of low frequencies connected to mass-loss variabilities. The spectral analysis confirmed gradual changes in the mass-loss rates and the derived CNO abundances comply with the values reported in the literature. We were able to achieve a quantitative match with stellar evolution models for the stellar masses and luminosities. However, the spectroscopic surface abundances turned out to be inconsistent with theoretical predictions. The stars show N enrichment, typical for CNO cycle processed material, but the abundance ratios do not reflect the associated levels of C and O depletion., Comment: 29 pages, 18 figures, Accepted for publication in Galaxies

Published
2023
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11. Appropriate Use Criteria (AUC) for the Management of Non-Small Cell Lung Cancer in a Central/Ultra-Central Location: Guidelines from the American Radium Society

Author

Park, Henry S., Rimner, Andreas, Amini, Arya, Chang, Joe Y., Chun, Stephen G., Donington, Jessica, Edelman, Martin J., Gubens, Matthew A., Higgins, Kristin A., Iyengar, Puneeth, Juloori, Aditya, Movsas, Benjamin, Nemeth, Zsuzsanna, Ning, Matthew S., Rodrigues, George, Wolf, Andrea, and Simone, Charles B., II

Published
2024
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19. Transcriptional profile of Mycobacterium tuberculosis infection in people living with HIV

Author

Tepekule, Burcu, Jörimann, Lisa, Schenkel, Corinne D., Opitz, Lennart, Tschumi, Jasmin, Wolfensberger, Rebekka, Neumann, Kathrin, Kusejko, Katharina, Zeeb, Marius, Boeck, Lucas, Kälin, Marisa, Notter, Julia, Furrer, Hansjakob, Hoffmann, Matthias, Hirsch, Hans H., Calmy, Alexandra, Cavassini, Matthias, Labhardt, Niklaus D., Bernasconi, Enos, Oesch, Gabriela, Metzner, Karin J., Braun, Dominique L., Günthard, Huldrych F., Kouyos, Roger D., Duffy, Fergal, and Nemeth, Johannes

Published
2024
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27. Risk of tuberculosis after initiation of antiretroviral therapy among persons with HIV in Europe

Author

Johansen, Isik S., Roen, Ashley, Kraef, Christian, Martín-Iguacel, Raquel, Nemeth, Johannes, Fenner, Lukas, Zangerle, Robert, Llibre, Josep M., Miller, Robert F., Suarez, Isabelle, de Wit, Stephane, Wit, Ferdinand, Mussini, Christina, Saracino, Annalisa, Canetti, Diana, Volny-Anne, Alain, Jaschinski, Nadine, Neesgaard, Bastian, Ryom, Lene, Peters, Lars, Garges, Harmony P., Rooney, James F., Podlekareva, Daria, Mocroft, Amanda, and Kirk, Ole

Published
2024
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35. Design and rationale of a pragmatic randomized clinical trial of early dronedarone versus usual care to change and improve outcomes in persons with first-detected atrial fibrillation – the CHANGE AFIB study

Author

Pokorney, Sean D., Nemeth, Hayley, Chiswell, Karen, Albert, Christine, Allyn, Nadine, Blanco, Rosalia, Butler, Javed, Calkins, Hugh, Elkind, Mitchell S.V., Fonarow, Gregg C., Fontaine, John M., Frankel, David S., Fermann, Gregory J., Gale, Rex, Kalscheur, Matthew, Kirchhof, Paulus, Koren, Andrew, Miller, Joseph B., Rashkin, Jason, Russo, Andrea M., Rutan, Christine, Steinberg, Benjamin A., and Piccini, Jonathan P.

Published
2025
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38. Consolidated Health Economic Evaluation Reporting Standards for Interventions That Use Artificial Intelligence (CHEERS-AI)

Author

Arbour, Sylvie, Asche, Carl, Ashurst, Carolyn, Balkanyi, Laszlo, Bennett, Hayley, Boros, Gerzson, Boyce, Rebecca, Carswell, Chris, Chaiyakunapruk, Nathorn, Chhatwal, Jagpreet, Ciani, Oriana, Collins, Gary, Dawson, David, Vanness, David, Di Bidino, Rossella, Faulding, Susan, Felizzi, Federico, Haig, Madeleine, Hawkins, James, Hiligsmann, Mikaël, Holst-Kristensen, Annette Willemoes, Isla, Julian, Koffijberg, Erik, Kostyuk, Alexander, Krief, Noemi, Lee, Dawn, Lee, Karen, Lundin, Douglas, Markiewicz-Barreaux, Katarzyna, Mauskopf, Josephine, Moons, Karel, Németh, Bertalan, Petrova, Guenka, Pwu, Raoh-Fang (Jasmine), Rejon-Parrilla, Juan Carlos, Rogers, Gabriel, Sampson, Chris, Springborg, Astrid Aaen, Steuten, Lotte, Sutherland, Eric, Suutala, Jaakko, Theisen, Daniel, Thompson, Alexander, van Gemert-Pijnen, Lisette, Walker, Thomas, Wilson, Ed, Elvidge, Jamie, Hawksworth, Claire, Avşar, Tuba Saygın, Zemplenyi, Antal, Chalkidou, Anastasia, Petrou, Stavros, Petykó, Zsuzsanna, Srivastava, Divya, Chandra, Gunjan, Delaye, Julien, Denniston, Alastair, Gomes, Manuel, Knies, Saskia, Nousios, Petros, Siirtola, Pekka, Wang, Junfeng, and Dawoud, Dalia

Published
2024
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40. Endoscopic GI placement of capsule endoscopy to investigate the small bowel: a multicenter European retrospective series of 630 procedures in adult patients

Author

Ouazana, Salome, Baltes, Peter, Toth, Ervin, Lüttge, Hannah, Nemeth, Artur, Beaumont, Hanneke, González-Suárez, Begoña, Lee, Phey Shen, Carretero, Cristina, Margalit Yehuda, Reuma, Elli, Luca, Spada, Cristiano, Bruno, Mauro, Mussetto, Alessandro, Cortegoso Valdivia, Pablo, Becq, Aymeric, Corbett, Gareth, Martin, Antoine, Robertson, Alexander, Benamouzig, Robert, Despott, Edward, Riccioni, Maria Elena, Sidhu, Reena, Calavas, Laura, Ellul, Pierre, Finta, Adam, Triantafyllou, Konstantinos, Rondonotti, Emanuele, Kirchgesner, Julien, Elosua, Alfonso, McNamara, Deirdre, and Dray, Xavier

Published
2024
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49. Detailed Characteristics of Post-discharge Mortality in Acute Pancreatitis

Author

Hegyi, Péter Jenő, Párniczky, Andrea, Földi, Mária, Ocskay, Klementina, Juhász, Márk Félix, Imrei, Marcell, Kiss, Szabolcs, Mikó, Alexandra, Gódi, Szilárd, Bajor, Judit, Hágendorn, Roland, Sarlós, Patrícia, Szabó, Imre, Czimmer, József, Faluhelyi, Nándor, Kanizsai, Péter, Miseta, Attila, Nagy, Tamás, Gajdán, László, Halász, Adrienn, Németh, Balázs, Kui, Balázs, Illés, Dóra, Takács, Tamás, Tiszlavicz, László, Oláh-Németh, Orsolya, Radics, Bence, Vitális, Zsuzsanna, Hamvas, József, Varga, Márta, Bod, Barnabás, Novák, János, Maurovich-Horváth, Pál, Doros, Attila, Deák, Pál Ákos, Varga, Csaba, Gaál, Szabolcs, Zubek, László, Gál, János, Molnár, Zsolt, Tornai, Tamás, Lázár, Balázs, Hussein, Tamás, Kovács, Bea, Németh, Anna, Tarján, Dorottya, Lipp, Mónika, Urbán, Orsolya, Tóth, Simon, Söti, Dániel, Becker, Dávid, Czapári, Dóra, Váradi, Alex, Farkas, Nelli, Nyári, Gergely, Márta, Katalin, Váncsa, Szilárd, Nagy, Rita, Teutsch, Brigitta, Bunduc, Stefania, Erőss, Bálint, Czakó, László, Vincze, Áron, Izbéki, Ferenc, Papp, Mária, Merkely, Béla, Szentesi, Andrea, and Hegyi, Péter

Published
2023
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