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479 results on '"Frolov, Alexander A."'

1. Magnetic Dirac semimetal state of (Mn,Ge)Bi$_2$Te$_4$

Author

Frolov, Alexander S., Usachov, Dmitry Yu., Tarasov, Artem V., Fedorov, Alexander V., Bokai, Kirill A., Klimovskikh, Ilya, Stolyarov, Vasily S., Sergeev, Anton I., Lavrov, Alexander N., Golyashov, Vladimir A., Tereshchenko, Oleg E., Di Santo, Giovanni, Petaccia, Luca, Clark, Oliver J., Sanchez-Barriga, Jaime, and Yashina, Lada V.

Subjects
Condensed Matter - Materials Science
Abstract

For quantum electronics, the possibility to finely tune the properties of magnetic topological insulators (TIs) is a key issue. We studied solid solutions between two isostructural Z$_2$ TIs, magnetic MnBi$_2$Te$_4$ and nonmagnetic GeBi$_2$Te$_4$, with Z$_2$ invariants of 1;000 and 1;001, respectively. For high-quality, large mixed crystals of Ge$_x$Mn$_{1-x}$Bi$_2$Te$_4$, we observed linear x-dependent magnetic properties, composition-independent pairwise exchange interactions along with an easy magnetization axis. The bulk band gap gradually decreases to zero for $x$ from 0 to 0.4, before reopening for $x>0.6$, evidencing topological phase transitions (TPTs) between topologically nontrivial phases and the semimetal state. The TPTs are driven purely by the variation of orbital contributions. By tracing the x-dependent $6p$ contribution to the states near the fundamental gap, the effective spin-orbit coupling variation is extracted. As $x$ varies, the maximum of this contribution switches from the valence to the conduction band, thereby driving two TPTs. The gapless state observed at $x=0.42$ closely resembles a Dirac semimetal above the Neel temperature and shows a magnetic gap below, which is clearly visible in raw photoemission data. The observed behavior of the Ge$_x$Mn$_{1-x}$Bi$_2$Te$_4$ system thereby demonstrates an ability to precisely control topological and magnetic properties of TIs.

Published
2023

2. Docmarking: Real-Time Screen-Cam Robust Document Image Watermarking

Author

Yakushev, Aleksey, Markin, Yury, Obydenkov, Dmitry, Frolov, Alexander, Fomin, Stas, Akopyan, Manuk, Kozachok, Alexander, and Gaynov, Arthur

Subjects
Computer Science - Cryptography and Security, Computer Science - Computer Vision and Pattern Recognition
Abstract

This paper focuses on investigation of confidential documents leaks in the form of screen photographs. Proposed approach does not try to prevent leak in the first place but rather aims to determine source of the leak. Method works by applying on the screen a unique identifying watermark as semi-transparent image that is almost imperceptible for human eyes. Watermark image is static and stays on the screen all the time thus watermark present on every captured photograph of the screen. The key components of the approach are three neural networks. The first network generates an image with embedded message in a way that this image is almost invisible when displayed on the screen. The other two neural networks are used to retrieve embedded message with high accuracy. Developed method was comprehensively tested on different screen and cameras. Test results showed high efficiency of the proposed approach., Comment: 9 pages, 8 figures

Published
2023
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4. Algorithmizing Aspects of Some Combinatorial Block-Designs Implemented in Network Systems

Author

Frolov, Alexander, Kochetova, Natalya, Klyagin, Anton, Kacprzyk, Janusz, Series Editor, Gomide, Fernando, Advisory Editor, Kaynak, Okyay, Advisory Editor, Liu, Derong, Advisory Editor, Pedrycz, Witold, Advisory Editor, Polycarpou, Marios M., Advisory Editor, Rudas, Imre J., Advisory Editor, Wang, Jun, Advisory Editor, Silhavy, Radek, editor, and Silhavy, Petr, editor

Published
2024
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5. Magnetic Dirac semimetal state of (Mn,Ge)Bi2Te4

Author

Frolov, Alexander S., Usachov, Dmitry Yu., Tarasov, Artem V., Fedorov, Alexander V., Bokai, Kirill A., Klimovskikh, Ilya, Stolyarov, Vasily S., Sergeev, Anton I., Lavrov, Alexander N., Golyashov, Vladimir A., Tereshchenko, Oleg E., Di Santo, Giovanni, Petacсia, Luca, Clark, Oliver J., Sanchez-Barriga, Jaime, and Yashina, Lada V.

Published
2024
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6. Intricate balance of dually-localized catalase modulates infectivity of Leptomonas seymouri (Kinetoplastea: Trypanosomatidae)

Author

Chmelová, Ľubomíra, Kraeva, Natalya, Saura, Andreu, Krayzel, Adam, Vieira, Cecilia Stahl, Ferreira, Tainá Neves, Soares, Rodrigo Pedro, Bučková, Barbora, Galan, Arnau, Horáková, Eva, Vojtková, Barbora, Sádlová, Jovana, Malysheva, Marina N., Butenko, Anzhelika, Prokopchuk, Galina, Frolov, Alexander O., Lukeš, Julius, Horváth, Anton, Škodová-Sveráková, Ingrid, Feder, Denise, Yu. Kostygov, Alexei, and Yurchenko, Vyacheslav

Published
2024
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8. Diversity of RNA viruses in the cosmopolitan monoxenous trypanosomatid Leptomonas pyrrhocoris

Author

Macedo, Diego H., Grybchuk, Danyil, Režnarová, Jana, Votýpka, Jan, Klocek, Donnamae, Yurchenko, Tatiana, Ševčík, Jan, Magri, Alice, Dolinská, Michaela Urda, Záhonová, Kristína, Lukeš, Julius, Servienė, Elena, Jászayová, Alexandra, Serva, Saulius, Malysheva, Marina N., Frolov, Alexander O., Yurchenko, Vyacheslav, and Kostygov, Alexei Yu.

Published
2023
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11. Scaling Networks and Capturing Keys Using Combined Combinatorial Block Designs

Author

Frolov, Alexander, Kochetova, Natalya, Klyagin, Anton, Kacprzyk, Janusz, Series Editor, Gomide, Fernando, Advisory Editor, Kaynak, Okyay, Advisory Editor, Liu, Derong, Advisory Editor, Pedrycz, Witold, Advisory Editor, Polycarpou, Marios M., Advisory Editor, Rudas, Imre J., Advisory Editor, Wang, Jun, Advisory Editor, Silhavy, Radek, editor, and Silhavy, Petr, editor

Published
2023
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12. Rental Processes Digitalization in Commercial Real Estate on the Example of the Development Company

Author

Frolov, Alexander K., Frolov, Konstantin V., Muhina, Ulyana Yu., Kacprzyk, Janusz, Series Editor, Gomide, Fernando, Advisory Editor, Kaynak, Okyay, Advisory Editor, Liu, Derong, Advisory Editor, Pedrycz, Witold, Advisory Editor, Polycarpou, Marios M., Advisory Editor, Rudas, Imre J., Advisory Editor, Wang, Jun, Advisory Editor, Ilin, Igor, editor, Petrova, Mariana Mateeva, editor, and Kudryavtseva, Tatiana, editor

Published
2023
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13. 6 GHz Band Sharing Study for FWA Base Stations and GEO Satellite Receivers

Author

Tikhvinskiy, Valery, Urodlivchenko, Vitaly, Koval, Victor, Frolov, Alexander, Ketat, Vladimir, Belyavskiy, Vadim, Goos, Gerhard, Founding Editor, Hartmanis, Juris, Founding Editor, Bertino, Elisa, Editorial Board Member, Gao, Wen, Editorial Board Member, Steffen, Bernhard, Editorial Board Member, Yung, Moti, Editorial Board Member, Koucheryavy, Yevgeni, editor, and Aziz, Ahmed, editor

Published
2023
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15. Statistical Properties of Soft X-ray emission of solar flares

Author

Sadykov, Viacheslav M, Kosovichev, Alexander G, Kitiashvili, Irina N, and Frolov, Alexander

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

We present a statistical analysis of properties of Soft X-Ray (SXR) emission, plasma temperature (T), and emission measure (EM), derived from GOES observations of flares in 2002-2017. The temperature and emission measures are obtained using the TEBBS algorithm (Ryan et al. 2012), which delivers reliable results together with uncertainties even for weak B-class flare events. More than 96% of flares demonstrate a sequential appearance of T, SXR, and EM maxima, in agreement with the expected behavior of the chromospheric evaporation process. The relative number of such flares increases with increasing the SXR flux maximum. The SXR maximum is closer in time to the T maximum for B-class flares than for >=C-class flares, while it is very close to the EM maximum for M- and X-class flares. We define flares as "T-controlled" if the time interval between the SXR and T maxima is at least two times shorter than the interval between the EM and SXR maxima, and as "EM-controlled" if the time interval between the EM and SXR maxima is at least two times shorter than the interval between the SXR and T maxima. For any considered flare class range, the T-controlled events compared to EM-controlled events have: a) higher EM but lower T; b) longer durations and shorter relative growth times; c) longer FWHM and characteristic decay times. Interpretation of these statistical results based on analysis of a single loop dynamics suggests that for flares of the same class range, the T-controlled events can be developed in longer loops than the EM-controlled events., Comment: Accepted for publication in The Astrophysical Journal (26 pages, 6 figures, 2 tables)

Published
2018
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16. Offline and Online Civic Activity: General and Special

Author

Sokolov, Alexander, Palagicheva, Asya, Frolov, Alexander, Filipe, Joaquim, Editorial Board Member, Ghosh, Ashish, Editorial Board Member, Prates, Raquel Oliveira, Editorial Board Member, Zhou, Lizhu, Editorial Board Member, Alexandrov, Daniel A., editor, Boukhanovsky, Alexander V., editor, Chugunov, Andrei V., editor, Kabanov, Yury, editor, Koltsova, Olessia, editor, Musabirov, Ilya, editor, and Pashakhin, Sergei, editor

Published
2022
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19. Computing of Blocks of Some Combinatorial Designs for Applications

Author

Frolov, Alexander, Kacprzyk, Janusz, Series Editor, Pal, Nikhil R., Advisory Editor, Bello Perez, Rafael, Advisory Editor, Corchado, Emilio S., Advisory Editor, Hagras, Hani, Advisory Editor, Kóczy, László T., Advisory Editor, Kreinovich, Vladik, Advisory Editor, Lin, Chin-Teng, Advisory Editor, Lu, Jie, Advisory Editor, Melin, Patricia, Advisory Editor, Nedjah, Nadia, Advisory Editor, Nguyen, Ngoc Thanh, Advisory Editor, Wang, Jun, Advisory Editor, Zamojski, Wojciech, editor, Mazurkiewicz, Jacek, editor, Sugier, Jarosław, editor, and Walkowiak, Tomasz, editor

Published
2021
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20. Final Results of Multi-center Randomized Controlled Trials of BCI-Controlled Hand Exoskeleton Complex Assisting Post-stroke Motor Function Recovery

Author

Frolov, Alexander, Biryukova, Elena, Bobrov, Pavel, Bobrov, Dmirty, Lekin, Alexander, Mokienko, Olesya, Lyukmanov, Roman, Kotov, Sergey, Kondur, Anna, Ivanova, Galina, Bushkova, Yulia, Gan, Woon-Seng, Series Editor, Kuo, C.-C. Jay, Series Editor, Zheng, Thomas Fang, Series Editor, Barni, Mauro, Series Editor, Guger, Christoph, editor, Allison, Brendan Z., editor, and Tangermann, Michael, editor

Published
2021
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22. Environmental Agenda in Protest Campaigns: Components and Results

Author

Sokolov, Alexander, Belyakov, Alexey, Mironova, Svetlana, Frolov, Alexander, Filipe, Joaquim, Editorial Board Member, Ghosh, Ashish, Editorial Board Member, Prates, Raquel Oliveira, Editorial Board Member, Zhou, Lizhu, Editorial Board Member, Alexandrov, Daniel A., editor, Boukhanovsky, Alexander V., editor, Chugunov, Andrei V., editor, Kabanov, Yury, editor, Koltsova, Olessia, editor, and Musabirov, Ilya, editor

Published
2020
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23. Protest Activity on Social Network Sites: A Method of Citizen’s Engagement Assessment

Author

Sokolov, Alexander, Belyakov, Alexey, Frolov, Alexander, Barbosa, Simone Diniz Junqueira, Editorial Board Member, Filipe, Joaquim, Editorial Board Member, Ghosh, Ashish, Editorial Board Member, Kotenko, Igor, Editorial Board Member, Zhou, Lizhu, Editorial Board Member, Chugunov, Andrei, editor, Khodachek, Igor, editor, Misnikov, Yuri, editor, and Trutnev, Dmitrii, editor

Published
2020
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24. On Some Computational and Security Aspects of the Blom Scheme

Author

Frolov, Alexander, Kacprzyk, Janusz, Series Editor, Pal, Nikhil R., Advisory Editor, Bello Perez, Rafael, Advisory Editor, Corchado, Emilio S., Advisory Editor, Hagras, Hani, Advisory Editor, Kóczy, László T., Advisory Editor, Kreinovich, Vladik, Advisory Editor, Lin, Chin-Teng, Advisory Editor, Lu, Jie, Advisory Editor, Melin, Patricia, Advisory Editor, Nedjah, Nadia, Advisory Editor, Nguyen, Ngoc Thanh, Advisory Editor, Wang, Jun, Advisory Editor, Zamojski, Wojciech, editor, Mazurkiewicz, Jacek, editor, Sugier, Jarosław, editor, and Walkowiak, Tomasz, editor

Published
2020
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25. Neurology trial registrations on ClinicalTrials.gov between 2007 and 2018: A cross-sectional analysis of characteristics, early discontinuation, and results reporting

Author

Turner, Brandon E., Magnani, Christopher J., Frolov, Alexander, Weeks, Brannon T., Steinberg, Jecca R., Huda, Naureen, Shah, Lochan M., Zuroff, Leah, Gu, Ben Jiahe, Rasmussen, Hannah, Edwards, Jeffrey G., Save, Akshay V., Shen, Max, Ren, Mark, Bryant, Barry R., Ma, Qian, Feng, Austin Y., Liang, Amy C., and Santini, Veronica E.

Published
2021
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29. Magnetic Dirac semimetal state of (Mn,Ge)Bi2Te4.

Author

Frolov, Alexander S., Usachov, Dmitry Yu., Tarasov, Artem V., Fedorov, Alexander V., Bokai, Kirill A., Klimovskikh, Ilya, Stolyarov, Vasily S., Sergeev, Anton I., Lavrov, Alexander N., Golyashov, Vladimir A., Tereshchenko, Oleg E., Di Santo, Giovanni, Petacсia, Luca, Clark, Oliver J., Sanchez-Barriga, Jaime, and Yashina, Lada V.

Subjects
*SEMIMETALS, *MAGNETIC insulators, *TOPOLOGICAL insulators, *QUANTUM electronics, *MAGNETIC properties, *MAGNETIC control, *PHOTOEMISSION
Abstract

The ability to finely tune the properties of magnetic topological insulators (TIs) is crucial for quantum electronics. We studied solid solutions with a general formula GexMn1-xBi2Te4 between two isostructural Z2 TIs, magnetic MnBi2Te4 and nonmagnetic GeBi2Te4 with Z2 invariants of 1;000 and 1;001, respectively. We observed linear x-dependent magnetic properties, composition-independent pairwise exchange interactions, and topological phase transitions (TPTs) between topologically nontrivial phases and the semimetal state. The TPTs are driven purely by the variation of orbital contributions. By tracing the x-dependent Bi 6p contribution to the states near the fundamental gap, the effective spin-orbit coupling variation is extracted. The gapless state observed at x = 0.42 closely resembles a Dirac semimetal above the Néel temperature and shows a magnetic gap below, which is clearly visible in raw photoemission data. The observed behavior demonstrates an ability to precisely control topological and magnetic properties of TIs. Topological insulators with ordered moments of embedded magnetic atoms are viable platforms for quantum electronics, but the practical applications are restricted by the size of their crystals. The authors synthesize a Z2 topological insulator GexMn1-xBi2Te4 in the form of a large crystal with high structural perfection and tunable magnetic and electronic properties. [ABSTRACT FROM AUTHOR]

Published
2024
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30. Magnetic Dirac semimetal state of (Mn,Ge)Bi2Te4.

Author

Frolov, Alexander S., Usachov, Dmitry Yu., Tarasov, Artem V., Fedorov, Alexander V., Bokai, Kirill A., Klimovskikh, Ilya, Stolyarov, Vasily S., Sergeev, Anton I., Lavrov, Alexander N., Golyashov, Vladimir A., Tereshchenko, Oleg E., Di Santo, Giovanni, Petacсia, Luca, Clark, Oliver J., Sanchez-Barriga, Jaime, and Yashina, Lada V.

Subjects
SEMIMETALS, MAGNETIC insulators, TOPOLOGICAL insulators, QUANTUM electronics, MAGNETIC properties, MAGNETIC control, PHOTOEMISSION
Abstract

The ability to finely tune the properties of magnetic topological insulators (TIs) is crucial for quantum electronics. We studied solid solutions with a general formula GexMn1-xBi2Te4 between two isostructural Z2 TIs, magnetic MnBi2Te4 and nonmagnetic GeBi2Te4 with Z2 invariants of 1;000 and 1;001, respectively. We observed linear x-dependent magnetic properties, composition-independent pairwise exchange interactions, and topological phase transitions (TPTs) between topologically nontrivial phases and the semimetal state. The TPTs are driven purely by the variation of orbital contributions. By tracing the x-dependent Bi 6p contribution to the states near the fundamental gap, the effective spin-orbit coupling variation is extracted. The gapless state observed at x = 0.42 closely resembles a Dirac semimetal above the Néel temperature and shows a magnetic gap below, which is clearly visible in raw photoemission data. The observed behavior demonstrates an ability to precisely control topological and magnetic properties of TIs. Topological insulators with ordered moments of embedded magnetic atoms are viable platforms for quantum electronics, but the practical applications are restricted by the size of their crystals. The authors synthesize a Z2 topological insulator GexMn1-xBi2Te4 in the form of a large crystal with high structural perfection and tunable magnetic and electronic properties. [ABSTRACT FROM AUTHOR]

Published
2024
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31. Networks Key Distribution Protocols Using KPS

Author

Frolov, Alexander, Vinnikov, Alexander, Kacprzyk, Janusz, Series Editor, Pal, Nikhil R., Advisory Editor, Bello Perez, Rafael, Advisory Editor, Corchado, Emilio S., Advisory Editor, Hagras, Hani, Advisory Editor, Kóczy, László T., Advisory Editor, Kreinovich, Vladik, Advisory Editor, Lin, Chin-Teng, Advisory Editor, Lu, Jie, Advisory Editor, Melin, Patricia, Advisory Editor, Nedjah, Nadia, Advisory Editor, Nguyen, Ngoc Thanh, Advisory Editor, Wang, Jun, Advisory Editor, Zamojski, Wojciech, editor, Mazurkiewicz, Jacek, editor, Sugier, Jarosław, editor, and Walkowiak, Tomasz, editor

Published
2019
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38. Comparative Analysis of Calculations in Cryptographic Protocols Using a Combination of Different Bases of Finite Fields

Author

Gashkov, Sergey, Frolov, Alexander, Kacprzyk, Janusz, Series editor, Pal, Nikhil R., Advisory editor, Bello Perez, Rafael, Advisory editor, Corchado, Emilio S., Advisory editor, Hagras, Hani, Advisory editor, Kóczy, László T., Advisory editor, Kreinovich, Vladik, Advisory editor, Lin, Chin-Teng, Advisory editor, Lu, Jie, Advisory editor, Melin, Patricia, Advisory editor, Nedjah, Nadia, Advisory editor, Nguyen, Ngoc Thanh, Advisory editor, Wang, Jun, Advisory editor, Zamojski, Wojciech, editor, Mazurkiewicz, Jacek, editor, Sugier, Jarosław, editor, and Walkowiak, Tomasz, editor

Published
2018
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41. Viral discovery and diversity in trypanosomatid protozoa with a focus on relatives of the human parasite Leishmania

Author

Grybchuk, Danyil, Akopyants, Natalia S., Kostygov, Alexei Y., Konovalovas, Aleksandras, Lye, Lon-Fye, Dobson, Deborah E., Zangger, Haroun, Fasel, Nicolas, Butenko, Anzhelika, Frolov, Alexander O., Votýpka, Jan, d’Avila-Levy, Claudia M., Kulich, Pavel, Moravcová, Jana, Plevka, Pavel, Rogozin, Igor B., Serva, Saulius, Lukeš, Julius, Beverley, Stephen M., and Yurchenko, Vyacheslav

Published
2018

44. Brain-Computer Interface Based on Generation of Visual Images

Author

Bobrov, Pavel, Frolov, Alexander, Cantor, Charles, Fedulova, Irina, Bakhnyan, Mikhail, and Zhavoronkov, Alexander

Subjects
single-trial eeg, hand movement, communication, multiclass, classification, performance, signals, humans, meg
Abstract

This paper examines the task of recognizing EEG patterns that correspond to performing three mental tasks: relaxation and imagining of two types of pictures: faces and houses. The experiments were performed using two EEG headsets: BrainProducts ActiCap and Emotiv EPOC. The Emotiv headset becomes widely used in consumer BCI application allowing for conducting large-scale EEG experiments in the future. Since classification accuracy significantly exceeded the level of random classification during the first three days of the experiment with EPOC headset, a control experiment was performed on the fourth day using ActiCap. The control experiment has shown that utilization of high-quality research equipment can enhance classification accuracy (up to 68% in some subjects) and that the accuracy is independent of the presence of EEG artifacts related to blinking and eye movement. This study also shows that computationally-inexpensive Bayesian classifier based on covariance matrix analysis yields similar classification accuracy in this problem as a more sophisticated Multi-class Common Spatial Patterns (MCSP) classifier.

Published
2011

47. The Mite Steatonyssus periblepharus Is a Novel Potential Vector of the Bat Parasite Trypanosoma dionisii.

Author

Malysheva, Marina N., Ganyukova, Anna I., Frolov, Alexander O., Chistyakov, Dmitriy V., and Kostygov, Alexei Yu.

Subjects
TRYPANOSOMA, MITES, BATS, PARASITES, GENETIC distance, LIFE cycles (Biology), MOLECULAR phylogeny
Abstract

Trypanosoma dionisii, for which only bat bugs (Cimicidae) had previously been demonstrated as vectors, was, for the first time, detected in the gamasine mite Steatonyssus periblepharus in Russia. The molecular phylogenetic analysis indicated that trypanosomes found in these mites belong to the "clade A" of T. dionisii, which, based on genetic distances, can be considered as a species separate from the sister clade B, and according to available data also has a distinct geographic distribution. The presence of developmental forms of T. dionisii resembling those previously described during the development of this trypanosome in cimicids suggests that S. periblepharus is a novel vector of the studied trypanosome. [ABSTRACT FROM AUTHOR]

Published
2023
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