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Zeiger PM, Barthel J, Allen LJ, Rusz J. Simulations of Phonon Spectroscopy in the Impact Scattering Regime - Advances and Applications. Microsc Microanal 2023; 29:628-629. [PMID: 37613084 DOI: 10.1093/micmic/ozad067.306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Affiliation(s)
- Paul M Zeiger
- Uppsala University, Department of Physics and Astronomy, Uppsala, Sweden
| | - Juri Barthel
- RWTH Aachen University, Central Facility for Electron Microscopy, Aachen, Germany
- Forschungszentrum Jülich GmbH, Ernst Ruska-Centre (ER-C 2), Jülich, Germany
| | - Leslie J Allen
- University of Melbourne, School of Physics, Victoria, Australia
| | - Ján Rusz
- Uppsala University, Department of Physics and Astronomy, Uppsala, Sweden
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2
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Castellanos-Reyes JÁ, Zeiger P, Bergman A, Kepaptsoglou D, Ramasse QM, Idrobo JC, Rusz J. Simulations of Magnon Diffuse Scattering in bcc Fe: The Impact of Temperature on Magnon Detection in STEM. Microsc Microanal 2023; 29:646. [PMID: 37613290 DOI: 10.1093/micmic/ozad067.316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Affiliation(s)
| | - Paul Zeiger
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| | - Anders Bergman
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| | - Demie Kepaptsoglou
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury, United Kingdom
- Department of Physics, University of York, York, United Kingdom
| | - Quentin M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury, United Kingdom
- School of Chemical and Process Engineering, University of Leeds, Leeds, United Kingdom
- School of Physics and Astronomy, University of Leeds, Leeds, United Kingdom
| | - Juan Carlos Idrobo
- Materials Science and Engineering Department, University of Washington, Seattle, Washington, USA
| | - Ján Rusz
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
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Snarski-Adamski J, Edström A, Zeiger P, Castellanos-Reyes JÁ, Lyon K, Werwiński M, Rusz J. Simulations of magnetic Bragg scattering in transmission electron microscopy. Ultramicroscopy 2023; 247:113698. [PMID: 36791558 DOI: 10.1016/j.ultramic.2023.113698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 01/19/2023] [Accepted: 02/02/2023] [Indexed: 02/09/2023]
Abstract
We have simulated the magnetic Bragg scattering in transmission electron microscopy in two antiferromagnetic compounds, NiO and LaMnAsO. This weak magnetic phenomenon was experimentally observed in NiO by Loudon (2012). We have computationally reproduced Loudon's experimental data, and for comparison we have performed calculations for the LaMnAsO compound as a more challenging case, containing lower concentration of magnetic elements and strongly scattering heavier non-magnetic elements. We have also described thickness and voltage dependence of the intensity of the antiferromagnetic Bragg spot for both compounds. We have considered lattice vibrations within two computational approaches, one assuming a static lattice with Debye-Waller smeared potentials, and another explicitly considering the atomic vibrations within the quantum excitations of phonons model (thermal diffuse scattering). The structural analysis shows that the antiferromagnetic Bragg spot appears in between (111) and (000) reflections for NiO, while for LaMnAsO the antiferromagnetic Bragg spot appears at the position of the (010) reflection in the diffraction pattern, which corresponds to a forbidden reflection of the crystal structure. Calculations predict that the intensity of the magnetic Bragg spot in NiO is significantly stronger than thermal diffuse scattering at room temperature. For LaMnAsO, the magnetic Bragg spot is weaker than the room-temperature thermal diffuse scattering, but its detection can be facilitated at reduced temperatures.
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Affiliation(s)
- Justyn Snarski-Adamski
- Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań, Poland.
| | - Alexander Edström
- Department of Applied Physics, School of Engineering Sciences, KTH Royal Institute of Technology, AlbaNova University Center, 10691 Stockholm, Sweden
| | - Paul Zeiger
- Division of Materials Theory, Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden
| | - José Ángel Castellanos-Reyes
- Division of Materials Theory, Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden
| | - Keenan Lyon
- Division of Materials Theory, Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden
| | - Mirosław Werwiński
- Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań, Poland
| | - Ján Rusz
- Division of Materials Theory, Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden.
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Herrera E, Guillamón I, Barrena V, Herrera WJ, Galvis JA, Yeyati AL, Rusz J, Oppeneer PM, Knebel G, Brison JP, Flouquet J, Aoki D, Suderow H. Quantum-well states at the surface of a heavy-fermion superconductor. Nature 2023; 616:465-469. [PMID: 36949204 PMCID: PMC10115632 DOI: 10.1038/s41586-023-05830-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Accepted: 02/13/2023] [Indexed: 03/24/2023]
Abstract
Two-dimensional electronic states at surfaces are often observed in simple wide-band metals such as Cu or Ag (refs. 1-4). Confinement by closed geometries at the nanometre scale, such as surface terraces, leads to quantized energy levels formed from the surface band, in stark contrast to the continuous energy dependence of bulk electron bands2,5-10. Their energy-level separation is typically hundreds of meV (refs. 3,6,11). In a distinct class of materials, strong electronic correlations lead to so-called heavy fermions with a strongly reduced bandwidth and exotic bulk ground states12,13. Quantum-well states in two-dimensional heavy fermions (2DHFs) remain, however, notoriously difficult to observe because of their tiny energy separation. Here we use millikelvin scanning tunnelling microscopy (STM) to study atomically flat terraces on U-terminated surfaces of the heavy-fermion superconductor URu2Si2, which exhibits a mysterious hidden-order (HO) state below 17.5 K (ref. 14). We observe 2DHFs made of 5f electrons with an effective mass 17 times the free electron mass. The 2DHFs form quantized states separated by a fraction of a meV and their level width is set by the interaction with correlated bulk states. Edge states on steps between terraces appear along one of the two in-plane directions, suggesting electronic symmetry breaking at the surface. Our results propose a new route to realize quantum-well states in strongly correlated quantum materials and to explore how these connect to the electronic environment.
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Affiliation(s)
- Edwin Herrera
- Facultad de Ingeniería y Ciencias Básicas, Universidad Central, Bogotá, Colombia.
- Departamento de Física, Universidad Nacional de Colombia, Bogotá, Colombia.
- Laboratorio de Bajas Temperaturas y Altos Campos Magnéticos, Unidad Asociada UAM/CSIC, Departamento de Física de la Materia Condensada, Instituto Nicolás Cabrera and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Madrid, Spain.
| | - Isabel Guillamón
- Laboratorio de Bajas Temperaturas y Altos Campos Magnéticos, Unidad Asociada UAM/CSIC, Departamento de Física de la Materia Condensada, Instituto Nicolás Cabrera and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Madrid, Spain
| | - Víctor Barrena
- Laboratorio de Bajas Temperaturas y Altos Campos Magnéticos, Unidad Asociada UAM/CSIC, Departamento de Física de la Materia Condensada, Instituto Nicolás Cabrera and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Madrid, Spain
| | - William J Herrera
- Departamento de Física, Universidad Nacional de Colombia, Bogotá, Colombia
| | - Jose Augusto Galvis
- Facultad de Ingeniería y Ciencias Básicas, Universidad Central, Bogotá, Colombia
- School of Engineering, Science and Technology, Universidad del Rosario, Bogotá, Colombia
| | - Alfredo Levy Yeyati
- Departamento de Física Teórica de la Materia Condensada, Instituto Nicolás Cabrera and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Madrid, Spain
| | - Ján Rusz
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| | - Peter M Oppeneer
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| | - Georg Knebel
- University Grenoble Alpes, CEA, Grenoble-INP, IRIG, PHELIQS, Grenoble, France
| | - Jean Pascal Brison
- University Grenoble Alpes, CEA, Grenoble-INP, IRIG, PHELIQS, Grenoble, France
| | - Jacques Flouquet
- University Grenoble Alpes, CEA, Grenoble-INP, IRIG, PHELIQS, Grenoble, France
| | - Dai Aoki
- Institute for Materials Research (IMR), Tohoku University, Oarai, Japan
| | - Hermann Suderow
- Laboratorio de Bajas Temperaturas y Altos Campos Magnéticos, Unidad Asociada UAM/CSIC, Departamento de Física de la Materia Condensada, Instituto Nicolás Cabrera and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Madrid, Spain.
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Svoboda E, Bořil T, Rusz J, Tykalová T, Horáková D, Guttmann CRG, Blagoev KB, Hatabu H, Valtchinov VI. Assessing clinical utility of machine learning and artificial intelligence approaches to analyze speech recordings in multiple sclerosis: A pilot study. Comput Biol Med 2022; 148:105853. [PMID: 35870318 DOI: 10.1016/j.compbiomed.2022.105853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 04/09/2022] [Accepted: 05/23/2022] [Indexed: 11/26/2022]
Abstract
BACKGROUND An early diagnosis together with an accurate disease progression monitoring of multiple sclerosis is an important component of successful disease management. Prior studies have established that multiple sclerosis is correlated with speech discrepancies. Early research using objective acoustic measurements has discovered measurable dysarthria. METHOD The objective was to determine the potential clinical utility of machine learning and deep learning/AI approaches for the aiding of diagnosis, biomarker extraction and progression monitoring of multiple sclerosis using speech recordings. A corpus of 65 MS-positive and 66 healthy individuals reading the same text aloud was used for targeted acoustic feature extraction utilizing automatic phoneme segmentation. A series of binary classification models was trained, tuned, and evaluated regarding their Accuracy and area-under-the-curve. RESULTS The Random Forest model performed best, achieving an Accuracy of 0.82 on the validation dataset and an area-under-the-curve of 0.76 across 5 k-fold cycles on the training dataset. 5 out of 7 acoustic features were statistically significant. CONCLUSION Machine learning and artificial intelligence in automatic analyses of voice recordings for aiding multiple sclerosis diagnosis and progression tracking seems promising. Further clinical validation of these methods and their mapping onto multiple sclerosis progression is needed, as well as a validating utility for English-speaking populations.
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Affiliation(s)
- E Svoboda
- Institute of Formal and Applied Linguistics, Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic; Institute of Phonetics, Faculty of Arts, Charles University, Prague, Czech Republic
| | - T Bořil
- Institute of Phonetics, Faculty of Arts, Charles University, Prague, Czech Republic
| | - J Rusz
- Department of Circuit Theory, Faculty of Electrical Engineering, Czech Technical University in Prague, Prague, Czech Republic; Department of Neurology and Center of Clinical Neuroscience, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic; Department of Neurology & ARTORG Center, Inselspital, Bern University Hospital, University of Bern, Switzerland
| | - T Tykalová
- Department of Circuit Theory, Faculty of Electrical Engineering, Czech Technical University in Prague, Prague, Czech Republic
| | - D Horáková
- Department of Neurology and Center of Clinical Neuroscience, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - C R G Guttmann
- Center for Neurological Imaging, Brigham & Women's Hospital and Harvard Medical School, USA
| | - K B Blagoev
- Department of Biophysics, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - H Hatabu
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - V I Valtchinov
- Center for Evidence-Based Imaging, USA; Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA; Department of Biomedical Informatics, Harvard Medical School, Boston, MA, USA.
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Hanuška J, Rusz J, Bezdicek O, Dušek P, Šonka K, Růžička E. Comment on “Pro‐Saccades Predict Cognitive Decline in Parkinson's Disease: ICICLE‐PD”. Mov Disord 2020; 35:522. [DOI: 10.1002/mds.27957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2019] [Accepted: 10/18/2019] [Indexed: 11/10/2022] Open
Affiliation(s)
- J. Hanuška
- Dept. of Neurology and Centre of Clinical Neuroscience, 1st Faculty of MedicineCharles University and General University Hospital Prague Czech Republic
- Dept. of Neurosurgery, Na Homolce Hospital Prague Czech Republic
| | - J. Rusz
- Dept. of Neurology and Centre of Clinical Neuroscience, 1st Faculty of MedicineCharles University and General University Hospital Prague Czech Republic
- Dept. of Circuit Theory, Faculty of Electrical EngineeringCzech Technical University in Prague Prague Czech Republic
| | - O. Bezdicek
- Dept. of Neurology and Centre of Clinical Neuroscience, 1st Faculty of MedicineCharles University and General University Hospital Prague Czech Republic
| | - P. Dušek
- Dept. of Neurology and Centre of Clinical Neuroscience, 1st Faculty of MedicineCharles University and General University Hospital Prague Czech Republic
- Dept. of Radiology, Charles University1st Faculty of Medicine and General University Hospital Prague Czech Republic
| | - K. Šonka
- Dept. of Neurology and Centre of Clinical Neuroscience, 1st Faculty of MedicineCharles University and General University Hospital Prague Czech Republic
| | - E. Růžička
- Dept. of Neurology and Centre of Clinical Neuroscience, 1st Faculty of MedicineCharles University and General University Hospital Prague Czech Republic
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Abstract
We introduce a novel method for the simulation of the impact scattering in vibrational scanning transmission electron microscopy electron energy loss spectroscopy simulations. The phonon-loss process is modeled by a combination of molecular dynamics and elastic multislice calculations within a modified frozen phonon approximation. The key idea is thereby to use a so-called δ thermostat in the classical molecular dynamics simulation to generate frequency dependent configurations of the vibrating specimen's atomic structure. The method includes correlated motion of atoms and provides vibrational spectrum images at a cost comparable to standard frozen phonon calculations. We demonstrate good agreement of our method with simulations and experiments for a 15 nm flake of hexagonal boron nitride.
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Affiliation(s)
- Paul M Zeiger
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, Uppsala 75120, Sweden
| | - Ján Rusz
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, Uppsala 75120, Sweden
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8
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Thersleff T, Schönström L, Tai CW, Adam R, Bürgler DE, Schneider CM, Muto S, Rusz J. Single-pass STEM-EMCD on a zone axis using a patterned aperture: progress in experimental and data treatment methods. Sci Rep 2019; 9:18170. [PMID: 31796786 PMCID: PMC6890689 DOI: 10.1038/s41598-019-53373-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 10/22/2019] [Indexed: 11/08/2022] Open
Abstract
Measuring magnetic moments in ferromagnetic materials at atomic resolution is theoretically possible using the electron magnetic circular dichroism (EMCD) technique in a (scanning) transmission electron microscope ((S)TEM). However, experimental and data processing hurdles currently hamper the realization of this goal. Experimentally, the sample must be tilted to a zone-axis orientation, yielding a complex distribution of magnetic scattering intensity, and the same sample region must be scanned multiple times with sub-atomic spatial registration necessary at each pass. Furthermore, the weak nature of the EMCD signal requires advanced data processing techniques to reliably detect and quantify the result. In this manuscript, we detail our experimental and data processing progress towards achieving single-pass zone-axis EMCD using a patterned aperture. First, we provide a comprehensive data acquisition and analysis strategy for this and other EMCD experiments that should scale down to atomic resolution experiments. Second, we demonstrate that, at low spatial resolution, promising EMCD candidate signals can be extracted, and that these are sensitive to both crystallographic orientation and momentum transfer.
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Affiliation(s)
- Thomas Thersleff
- Stockholm University, Department of Materials and Environmental Chemistry, 10691, Stockholm, Sweden.
| | - Linus Schönström
- Stockholm University, Department of Materials and Environmental Chemistry, 10691, Stockholm, Sweden
- Uppsala University, Department of Physics and Astronomy, Box 516, 75120, Uppsala, Sweden
| | - Cheuk-Wai Tai
- Stockholm University, Department of Materials and Environmental Chemistry, 10691, Stockholm, Sweden
| | - Roman Adam
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut, D-52425, Jülich, Germany
| | - Daniel E Bürgler
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut, D-52425, Jülich, Germany
| | - Claus M Schneider
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut, D-52425, Jülich, Germany
| | - Shunsuke Muto
- Nagoya University, Institute of Materials and Systems for Sustainability, Nagoya, 464-8603, Japan
| | - Ján Rusz
- Uppsala University, Department of Physics and Astronomy, Box 516, 75120, Uppsala, Sweden
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9
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Abstract
We unveil the native defect induced high spin to low spin state transition in [Formula: see text] and half-metallicity in CoO. First principles calculations unravel that, defect density holds a key role in dictating the spin-state transition in [Formula: see text] ion in CoO, and introducing the half-metallicity. Charge transfer in the vicinity of vacancy plane favors the stabilization and coexistence of bivalent [Formula: see text] and trivalent [Formula: see text] ion in CoO. We propose that defect engineering could serve as a route to design the half metallicity in transition metal mono-oxides.
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Affiliation(s)
- Devendra Singh Negi
- Department of Physics and Astronomy, Uppsala University, PO Box 516, 75120 Uppsala, Sweden
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10
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Negi D, Spiegelberg J, Muto S, Thersleff T, Ohtsuka M, Schönström L, Tatsumi K, Rusz J. Proposal for Measuring Magnetism with Patterned Apertures in a Transmission Electron Microscope. Phys Rev Lett 2019; 122:037201. [PMID: 30735420 DOI: 10.1103/physrevlett.122.037201] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 10/13/2018] [Indexed: 06/09/2023]
Abstract
We propose a magnetic measurement method utilizing a patterned postsample aperture in a transmission electron microscope. While utilizing electron magnetic circular dichroism, the method circumvents previous needs to shape the electron probe to an electron vortex beam or astigmatic beam. The method can be implemented in standard scanning transmission electron microscopes by replacing the spectrometer entrance aperture with a specially shaped aperture, hereafter called a ventilator aperture. The proposed setup is expected to work across the whole range of beam sizes-from wide parallel beams down to atomic resolution magnetic spectrum imaging.
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Affiliation(s)
- Devendra Negi
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, 75120 Uppsala, Sweden
| | - Jakob Spiegelberg
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, 75120 Uppsala, Sweden
| | - Shunsuke Muto
- Electron Nanoscopy Section, Advanced Measurement Technology Center, Institute of Materials and Systems for Sustainability, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Thomas Thersleff
- Department of Materials and Environmental Chemistry, Stockholm University, Svante Arrhenius väg 16C, 106 91 Stockholm, Sweden
| | - Masahiro Ohtsuka
- Department of Materials Physics, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Linus Schönström
- Department of Materials and Environmental Chemistry, Stockholm University, Svante Arrhenius väg 16C, 106 91 Stockholm, Sweden
| | - Kazuyoshi Tatsumi
- Advanced Measurement Technology Center, Institute of Materials and Systems for Sustainability, Nagoya University, Chikusa, Nagoya 464-8603, Japan
| | - Ján Rusz
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, 75120 Uppsala, Sweden
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11
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Spiegelberg J, Song D, Dunin-Borkowski RE, Zhu J, Rusz J. Blind identification of magnetic signals in electron magnetic chiral dichroism using independent component analysis. Ultramicroscopy 2018; 195:129-135. [DOI: 10.1016/j.ultramic.2018.08.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 08/23/2018] [Accepted: 08/25/2018] [Indexed: 10/28/2022]
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Moro-Velazquez L, Gomez-Garcia JA, Godino-Llorente JI, Rusz J, Skodda S, Grandas F, Velazquez JM, Orozco-Arroyave JR, Noth E, Dehak N. Study of the Automatic Detection of Parkison's Disease Based on Speaker Recognition Technologies and Allophonic Distillation. Annu Int Conf IEEE Eng Med Biol Soc 2018; 2018:1404-1407. [PMID: 30440655 DOI: 10.1109/embc.2018.8512562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The use of new tools to detect Parkinson's Disease (PD) from speech articulatory movements can have a considerable impact in the diagnosis of patients. In this study, a novel approach involving speaker recognition techniques with allophonic distillation is proposed and tested separately in four parkinsonian speech databases (205 patients and 186 controls in total). This new scheme provides values between 72% and 94% of accuracy in the automatic detection of PD, depending on the database, and improvements up to 9% respect to baseline techniques. Results not only point towards the importance of the segmentation of the speech for the differentiation of parkinsonian and control speakers but confirm previous findings about the relevance of plosives and fricatives in the detection of parkinsonian dysarthria.
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Brabcova L, Roth J, Ulmanová O, Klempíř J, Rusz J, Horáček O, Kolářová M, Košková P, Rolková P, Božková H, Szabó L, Inemanová M, Lísalová K, Jančok F, Brožová H. Effect of a specific inpatient multidisciplinary rehabilitation program on postural and gait stability in Huntington's disease – Pilot study. Ann Phys Rehabil Med 2018. [DOI: 10.1016/j.rehab.2018.05.584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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14
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Wang Z, Tavabi AH, Jin L, Rusz J, Tyutyunnikov D, Jiang H, Moritomo Y, Mayer J, Dunin-Borkowski RE, Yu R, Zhu J, Zhong X. Publisher Correction: Atomic scale imaging of magnetic circular dichroism by achromatic electron microscopy. Nat Mater 2018; 17:290. [PMID: 29445245 DOI: 10.1038/s41563-018-0039-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
In Fig. 1 of the version of this Letter originally published, the word 'Subtract' was missing from the green box to the left of panel f. This has now been corrected in all versions of the Letter.
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Affiliation(s)
- Zechao Wang
- National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE), The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing, China
| | - Amir H Tavabi
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Lei Jin
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Ján Rusz
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| | | | - Hanbo Jiang
- National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE), The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing, China
| | - Yutaka Moritomo
- Graduate School of Pure & Applied Science and Faculty of Pure & Applied Science, University of Tsukuba, Tsukuba, Japan
| | - Joachim Mayer
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich GmbH, Jülich, Germany
- Central Facility for Electron Microscopy, RWTH Aachen University, Aachen, Germany
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Rong Yu
- National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE), The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing, China
| | - Jing Zhu
- National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE), The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing, China
| | - Xiaoyan Zhong
- National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE), The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing, China.
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15
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Wang Z, Tavabi AH, Jin L, Rusz J, Tyutyunnikov D, Jiang H, Moritomo Y, Mayer J, Dunin-Borkowski RE, Yu R, Zhu J, Zhong X. Atomic scale imaging of magnetic circular dichroism by achromatic electron microscopy. Nat Mater 2018; 17:221-225. [PMID: 29403052 DOI: 10.1038/s41563-017-0010-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 12/11/2017] [Indexed: 06/07/2023]
Abstract
In order to obtain a fundamental understanding of the interplay between charge, spin, orbital and lattice degrees of freedom in magnetic materials and to predict and control their physical properties1-3, experimental techniques are required that are capable of accessing local magnetic information with atomic-scale spatial resolution. Here, we show that a combination of electron energy-loss magnetic chiral dichroism 4 and chromatic-aberration-corrected transmission electron microscopy, which reduces the focal spread of inelastically scattered electrons by orders of magnitude when compared with the use of spherical aberration correction alone, can achieve atomic-scale imaging of magnetic circular dichroism and provide element-selective orbital and spin magnetic moments atomic plane by atomic plane. This unique capability, which we demonstrate for Sr2FeMoO6, opens the door to local atomic-level studies of spin configurations in a multitude of materials that exhibit different types of magnetic coupling, thereby contributing to a detailed understanding of the physical origins of magnetic properties of materials at the highest spatial resolution.
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Affiliation(s)
- Zechao Wang
- National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE), The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing, China
| | - Amir H Tavabi
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Lei Jin
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Ján Rusz
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| | | | - Hanbo Jiang
- National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE), The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing, China
| | - Yutaka Moritomo
- Graduate School of Pure & Applied Science and Faculty of Pure & Applied Science, University of Tsukuba, Tsukuba, Japan
| | - Joachim Mayer
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich GmbH, Jülich, Germany
- Central Facility for Electron Microscopy, RWTH Aachen University, Aachen, Germany
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Rong Yu
- National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE), The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing, China
| | - Jing Zhu
- National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE), The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing, China
| | - Xiaoyan Zhong
- National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE), The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing, China.
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16
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Cedervall J, Nonnet E, Hedlund D, Häggström L, Ericsson T, Werwiński M, Edström A, Rusz J, Svedlindh P, Gunnarsson K, Sahlberg M. Influence of Cobalt Substitution on the Magnetic Properties of Fe 5PB 2. Inorg Chem 2018; 57:777-784. [PMID: 29298054 DOI: 10.1021/acs.inorgchem.7b02663] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The substitutional effects of cobalt in (Fe1-xCox)5PB2 have been studied with respect to crystalline structure and chemical order with X-ray diffraction and Mössbauer spectroscopy. The magnetic properties have been determined from magnetic measurements, and density functional theory calculations have been performed for the magnetic properties of both the end compounds, as well as the chemically disordered intermediate compounds. The crystal structure of (Fe1-xCox)5PB2 is tetragonal (space group I4/mcm) with two different metal sites, with a preference for cobalt atoms in the M(2) position (4c) at higher cobalt contents. The substitution also affects the magnetic properties with a decrease of the Curie temperature (TC) with increasing cobalt content, from 622 to 152 K for Fe5PB2 and (Fe0.3Co0.7)5PB2, respectively. Thus, the Curie temperature is dependent on composition, and it is possible to tune TC to a temperature near room temperature, which is one prerequisite for magnetic cooling materials.
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Affiliation(s)
- Johan Cedervall
- Department of Chemistry-Ångström Laboratory, Uppsala University , Box 538, 751 21 Uppsala, Sweden
| | - Elise Nonnet
- Department of Chemistry-Ångström Laboratory, Uppsala University , Box 538, 751 21 Uppsala, Sweden
| | - Daniel Hedlund
- Department of Engineering Sciences, Uppsala University , Box 534, 751 21 Uppsala, Sweden
| | - Lennart Häggström
- Department of Physics and Astronomy, Uppsala University , Box 516, 751 20 Uppsala, Sweden
| | - Tore Ericsson
- Department of Physics and Astronomy, Uppsala University , Box 516, 751 20 Uppsala, Sweden
| | - Mirosław Werwiński
- Institute of Molecular Physics Polish Academy of Sciences , M. Smoluchowskiego 17, 60-179 Poznań, Poland
| | - Alexander Edström
- Department of Physics and Astronomy, Uppsala University , Box 516, 751 20 Uppsala, Sweden.,Department of Materials Theory, ETH Zürich , Wolfgang-Pauli-Str. 27, 8093 Zürich, Switzerland
| | - Ján Rusz
- Department of Physics and Astronomy, Uppsala University , Box 516, 751 20 Uppsala, Sweden
| | - Peter Svedlindh
- Department of Engineering Sciences, Uppsala University , Box 534, 751 21 Uppsala, Sweden
| | - Klas Gunnarsson
- Department of Engineering Sciences, Uppsala University , Box 534, 751 21 Uppsala, Sweden
| | - Martin Sahlberg
- Department of Chemistry-Ångström Laboratory, Uppsala University , Box 538, 751 21 Uppsala, Sweden
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17
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Salikhov R, Reichel L, Zingsem B, Abrudan R, Edström A, Thonig D, Rusz J, Eriksson O, Schultz L, Fähler S, Farle M, Wiedwald U. Enhanced spin-orbit coupling in tetragonally strained Fe-Co-B films. J Phys Condens Matter 2017; 29:275802. [PMID: 28530633 DOI: 10.1088/1361-648x/aa7498] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Tetragonally strained interstitial Fe-Co-B alloys were synthesized as epitaxial films grown on a 20 nm thick Au0.55Cu0.45 buffer layer. Different ratios of the perpendicular to in-plane lattice constant c/a = 1.013, 1.034 and 1.02 were stabilized by adding interstitial boron with different concentrations 0, 4, and 10 at.%, respectively. Using ferromagnetic resonance (FMR) and x-ray magnetic circular dichroism (XMCD) we found that the total orbital magnetic moment significantly increases with increasing c/a ratio, indicating that reduced crystal symmetry and interstitial B leads to a noticeable enhancement of the effect of spin-orbit coupling (SOC) in the Fe-Co-B alloys. First-principles calculations reveal that the increase in orbital magnetic moment mainly originates from B impurities in octahedral position and the reduced symmetry around B atoms. These findings offer the possibility to enhance SOC phenomena-namely the magnetocrystalline anisotropy and the orbital moment-by stabilizing anisotropic strain by doping 4 at.% B. Results on the influence of B doping on the Fe-Co film microstructure, their coercive field and magnetic relaxation are also presented.
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Affiliation(s)
- R Salikhov
- Faculty of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, 47057 Duisburg, Germany
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18
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Bonnet C, Rusz J, Hanuška J, Dezortová M, Jírů F, Sieger T, Jech R, Klempíř J, Roth J, Bezdíček O, Serranová T, Dušek P, Uher T, Flammand-Roze C, Hájek M, Růžička E. GABA spectra and remote distractor effect in progressive supranuclear palsy: A pilot study. Rev Neurol (Paris) 2017; 173:225-229. [PMID: 28385472 DOI: 10.1016/j.neurol.2017.03.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 01/11/2017] [Accepted: 03/09/2017] [Indexed: 11/17/2022]
Abstract
Disturbances of the gamma-aminobutyric-acid (GABA) system have been suspected of contributing to the pathophysiology of progressive supranuclear palsy (PSP). The ability to rapidly resolve competitive action decisions, such as shifting the gaze to one particular stimulus rather than another, can be predicted by the concentration of GABA in the region of the frontal cortex relevant to eye movements. For this reason, our study measured GABA levels in seven PSP patients and eight healthy controls, using proton magnetic resonance spectroscopy, and assessed the relationship of these measurements to the remote distractor effect (RDE), an eye-movement paradigm investigating competitive action decisions. No significant differences were found in either frontal-eye-field GABA levels or RDE between PSP patients and controls.
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Affiliation(s)
- C Bonnet
- Department of Neurology, Center of Clinical Neuroscience, Charles University, First Faculty of Medicine, General University Hospital, Kateřinská 30, Prague 2, 12000 Prague, Czech Republic; Department of Neurology, Pitié-Salpêtrière Hospital, AP-HP, 75013 Paris, France
| | - J Rusz
- Department of Neurology, Center of Clinical Neuroscience, Charles University, First Faculty of Medicine, General University Hospital, Kateřinská 30, Prague 2, 12000 Prague, Czech Republic; Department of Circuit Theory, Faculty of Electrical Engineering, Czech Technical University, Prague, Czech Republic
| | - J Hanuška
- Department of Neurology, Center of Clinical Neuroscience, Charles University, First Faculty of Medicine, General University Hospital, Kateřinská 30, Prague 2, 12000 Prague, Czech Republic; Department of Neurosurgery, Hospital Na Homolce, Prague, Czech Republic
| | - M Dezortová
- MR-unit, Department of Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, Prague, Czech Republic
| | - F Jírů
- MR-unit, Department of Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, Prague, Czech Republic
| | - T Sieger
- Department of Neurology, Center of Clinical Neuroscience, Charles University, First Faculty of Medicine, General University Hospital, Kateřinská 30, Prague 2, 12000 Prague, Czech Republic; Department of Cybernetics, Faculty of Electrical Engineering, Czech Technical University, Prague, Czech Republic
| | - R Jech
- Department of Neurology, Center of Clinical Neuroscience, Charles University, First Faculty of Medicine, General University Hospital, Kateřinská 30, Prague 2, 12000 Prague, Czech Republic
| | - J Klempíř
- Department of Neurology, Center of Clinical Neuroscience, Charles University, First Faculty of Medicine, General University Hospital, Kateřinská 30, Prague 2, 12000 Prague, Czech Republic
| | - J Roth
- Department of Neurology, Center of Clinical Neuroscience, Charles University, First Faculty of Medicine, General University Hospital, Kateřinská 30, Prague 2, 12000 Prague, Czech Republic
| | - O Bezdíček
- Department of Neurology, Center of Clinical Neuroscience, Charles University, First Faculty of Medicine, General University Hospital, Kateřinská 30, Prague 2, 12000 Prague, Czech Republic
| | - T Serranová
- Department of Neurology, Center of Clinical Neuroscience, Charles University, First Faculty of Medicine, General University Hospital, Kateřinská 30, Prague 2, 12000 Prague, Czech Republic
| | - P Dušek
- Department of Neurology, Center of Clinical Neuroscience, Charles University, First Faculty of Medicine, General University Hospital, Kateřinská 30, Prague 2, 12000 Prague, Czech Republic
| | - T Uher
- Department of Neurology, Center of Clinical Neuroscience, Charles University, First Faculty of Medicine, General University Hospital, Kateřinská 30, Prague 2, 12000 Prague, Czech Republic
| | - C Flammand-Roze
- AP-HP, Hospital de Bicêtre, Department of Neurology, 94270 Paris, France
| | - M Hájek
- MR-unit, Department of Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, Prague, Czech Republic
| | - E Růžička
- Department of Neurology, Center of Clinical Neuroscience, Charles University, First Faculty of Medicine, General University Hospital, Kateřinská 30, Prague 2, 12000 Prague, Czech Republic.
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19
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Spiegelberg J, Rusz J, Pelckmans K. Tensor decompositions for the analysis of atomic resolution electron energy loss spectra. Ultramicroscopy 2017; 175:36-45. [DOI: 10.1016/j.ultramic.2016.12.025] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 12/01/2016] [Accepted: 12/04/2016] [Indexed: 11/25/2022]
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20
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Thersleff T, Muto S, Werwiński M, Spiegelberg J, Kvashnin Y, Hjӧrvarsson B, Eriksson O, Rusz J, Leifer K. Towards sub-nanometer real-space observation of spin and orbital magnetism at the Fe/MgO interface. Sci Rep 2017; 7:44802. [PMID: 28338011 PMCID: PMC5364495 DOI: 10.1038/srep44802] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 02/14/2017] [Indexed: 11/12/2022] Open
Abstract
While the performance of magnetic tunnel junctions based on metal/oxide interfaces is determined by hybridization, charge transfer, and magnetic properties at the interface, there are currently only limited experimental techniques with sufficient spatial resolution to directly observe these effects simultaneously in real-space. In this letter, we demonstrate an experimental method based on Electron Magnetic Circular Dichroism (EMCD) that will allow researchers to simultaneously map magnetic transitions and valency in real-space over interfacial cross-sections with sub-nanometer spatial resolution. We apply this method to an Fe/MgO bilayer system, observing a significant enhancement in the orbital to spin moment ratio that is strongly localized to the interfacial region. Through the use of first-principles calculations, multivariate statistical analysis, and Electron Energy-Loss Spectroscopy (EELS), we explore the extent to which this enhancement can be attributed to emergent magnetism due to structural confinement at the interface. We conclude that this method has the potential to directly visualize spin and orbital moments at buried interfaces in magnetic systems with unprecedented spatial resolution.
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Affiliation(s)
- Thomas Thersleff
- Department of Engineering Sciences, Uppsala University, Box 534, 75121 Uppsala, Sweden
| | - Shunsuke Muto
- Advanced Measurement Technology Center, Institute of Materials and Systems for Sustainability, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan
| | - Mirosław Werwiński
- Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden.,Institute of Molecular Physics Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań, Poland
| | - Jakob Spiegelberg
- Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
| | - Yaroslav Kvashnin
- Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
| | - Björgvin Hjӧrvarsson
- Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
| | - Olle Eriksson
- Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
| | - Ján Rusz
- Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
| | - Klaus Leifer
- Department of Engineering Sciences, Uppsala University, Box 534, 75121 Uppsala, Sweden
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21
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Spiegelberg J, Rusz J, Thersleff T, Pelckmans K. Analysis of electron energy loss spectroscopy data using geometric extraction methods. Ultramicroscopy 2017; 174:14-26. [DOI: 10.1016/j.ultramic.2016.12.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 12/08/2016] [Accepted: 12/13/2016] [Indexed: 10/20/2022]
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22
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Rusz J. Modified automatic term selection v2: A faster algorithm to calculate inelastic scattering cross-sections. Ultramicroscopy 2017; 177:20-25. [PMID: 28214388 DOI: 10.1016/j.ultramic.2017.01.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Revised: 01/08/2017] [Accepted: 01/21/2017] [Indexed: 11/17/2022]
Abstract
We present a new algorithm for calculating inelastic scattering cross-section for fast electrons. Compared to the previous Modified Automatic Term Selection (mats) algorithm (Rusz et al. [18]), it has far better convergence properties in zone axis calculations and it allows to identify contributions of individual atoms. One can think of it as a blend of mats algorithm and a method described by Weickenmeier and Kohl [10].
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Affiliation(s)
- Ján Rusz
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, 75120 Uppsala, Sweden.
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23
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Rusz J, Muto S, Spiegelberg J, Adam R, Tatsumi K, Bürgler DE, Oppeneer PM, Schneider CM. Erratum: Magnetic measurements with atomic-plane resolution. Nat Commun 2016; 7:13159. [PMID: 27703183 PMCID: PMC5059487 DOI: 10.1038/ncomms13159] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
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24
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Schneider S, Pohl D, Löffler S, Rusz J, Kasinathan D, Schattschneider P, Schultz L, Rellinghaus B. Magnetic properties of single nanomagnets: Electron energy-loss magnetic chiral dichroism on FePt nanoparticles. Ultramicroscopy 2016; 171:186-194. [PMID: 27694036 DOI: 10.1016/j.ultramic.2016.09.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 09/05/2016] [Accepted: 09/18/2016] [Indexed: 11/24/2022]
Abstract
Electron energy-loss magnetic chiral dichroism (EMCD) allows for the quantification of magnetic properties of materials at the nanometer scale. It is shown that with the support of simulations that help to identify the optimal conditions for a successful experiment and upon implementing measurement routines that effectively reduce the noise floor, EMCD measurements can be pushed towards quantitative magnetic measurements even on individual nanoparticles. With this approach, the ratio of orbital to spin magnetic moments for the Fe atoms in a single L10 ordered FePt nanoparticle is determined to be ml/ms=0.08±0.02. This finding is in good quantitative agreement with the results of XMCD ensemble measurements.
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Affiliation(s)
- Sebastian Schneider
- IFW Dresden, Institute for Metallic Materials, PO Box 270116, D-01171 Dresden, Germany; TU Dresden, Institut für Festkörperphysik, D-01062 Dresden, Germany.
| | - Darius Pohl
- IFW Dresden, Institute for Metallic Materials, PO Box 270116, D-01171 Dresden, Germany
| | - Stefan Löffler
- TU Wien, University Service Centre for Electron Microscopy, Wiedner Hauptstraße 8-10, A-1040 Vienna, Austria; McMaster University, Department of Materials Science and Engineering, 1280 Main Street West, Hamilton, Ontario, Canada L8S4L8
| | - Ján Rusz
- Uppsala University, Department of Physics and Astronomy, PO Box 516, S-75120 Uppsala, Sweden
| | - Deepa Kasinathan
- Max-Planck-Institut für Chemische Physik fester Stoffe, Department of Physics of Correlated Matter, Nöthnitzer Straße 40, D-01187 Dresden, Germany
| | - Peter Schattschneider
- TU Wien, University Service Centre for Electron Microscopy, Wiedner Hauptstraße 8-10, A-1040 Vienna, Austria; TU Wien, Institute of Solid State Physics, Wiedner Hauptstraße 8-10, A-1040 Vienna, Austria
| | - Ludwig Schultz
- IFW Dresden, Institute for Metallic Materials, PO Box 270116, D-01171 Dresden, Germany; TU Dresden, Institut für Festkörperphysik, D-01062 Dresden, Germany
| | - Bernd Rellinghaus
- IFW Dresden, Institute for Metallic Materials, PO Box 270116, D-01171 Dresden, Germany
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25
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Rusz J, Muto S, Spiegelberg J, Adam R, Tatsumi K, Bürgler DE, Oppeneer PM, Schneider CM. Magnetic measurements with atomic-plane resolution. Nat Commun 2016; 7:12672. [PMID: 27578421 PMCID: PMC5013673 DOI: 10.1038/ncomms12672] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 07/21/2016] [Indexed: 11/09/2022] Open
Abstract
Rapid development of magnetic nanotechnologies calls for experimental techniques capable of providing magnetic information with subnanometre spatial resolution. Available probes of magnetism either detect only surface properties, such as spin-polarized scanning tunnelling microscopy, magnetic force microscopy or spin-polarized low-energy electron microscopy, or they are bulk probes with limited spatial resolution or quantitativeness, such as X-ray magnetic circular dichroism or classical electron magnetic circular dichroism (EMCD). Atomic resolution EMCD methods have been proposed, although not yet experimentally realized. Here, we demonstrate an EMCD technique with an atomic size electron probe utilizing a probe-corrected scanning transmission electron microscope in its standard operation mode. The crucial element of the method is a ramp in the phase of the electron beam wavefunction, introduced by a controlled beam displacement. We detect EMCD signals with atomic-plane resolution, thereby bringing near-atomic resolution magnetic circular dichroism spectroscopy to hundreds of laboratories worldwide. It has been predicted that electron beam probes may allow for the imaging of magnetism with atomic-scale resolution. Here, the authors demonstrate a scanning transmission electron microscopy method capable of resolving magnetic contrast from individual atomic planes.
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Affiliation(s)
- Ján Rusz
- Department of Physics and Astronomy, Uppsala University, Box 516, S-75120 Uppsala, Sweden
| | - Shunsuke Muto
- Advanced Measurement Technology Center, Institute of Materials and Systems for Sustainability, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan
| | - Jakob Spiegelberg
- Department of Physics and Astronomy, Uppsala University, Box 516, S-75120 Uppsala, Sweden
| | - Roman Adam
- Peter Grünberg Institute, Electronic Properties (PGI-6), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Kazuyoshi Tatsumi
- Advanced Measurement Technology Center, Institute of Materials and Systems for Sustainability, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan
| | - Daniel E Bürgler
- Peter Grünberg Institute, Electronic Properties (PGI-6), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Peter M Oppeneer
- Department of Physics and Astronomy, Uppsala University, Box 516, S-75120 Uppsala, Sweden
| | - Claus M Schneider
- Peter Grünberg Institute, Electronic Properties (PGI-6), Forschungszentrum Jülich, 52425 Jülich, Germany
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Kislitsyn DA, Mills JM, Kocevski V, Chiu SK, DeBenedetti WJI, Gervasi CF, Taber BN, Rosenfield AE, Eriksson O, Rusz J, Goforth AM, Nazin GV. Communication: Visualization and spectroscopy of defects induced by dehydrogenation in individual silicon nanocrystals. J Chem Phys 2016; 144:241102. [DOI: 10.1063/1.4954833] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Dmitry A. Kislitsyn
- Department of Chemistry and Biochemistry, Materials Science Institute, Oregon Center for Optical, Molecular and Quantum Science, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403, USA
| | - Jon M. Mills
- Department of Chemistry and Biochemistry, Materials Science Institute, Oregon Center for Optical, Molecular and Quantum Science, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403, USA
| | - Vancho Kocevski
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, SE-751 20 Uppsala, Sweden
| | - Sheng-Kuei Chiu
- Department of Chemistry, Portland State University, Portland, Oregon 97201, USA
| | | | - Christian F. Gervasi
- Department of Chemistry and Biochemistry, Materials Science Institute, Oregon Center for Optical, Molecular and Quantum Science, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403, USA
| | - Benjamen N. Taber
- Department of Chemistry and Biochemistry, Materials Science Institute, Oregon Center for Optical, Molecular and Quantum Science, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403, USA
| | - Ariel E. Rosenfield
- Department of Chemistry and Biochemistry, Materials Science Institute, Oregon Center for Optical, Molecular and Quantum Science, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403, USA
| | - Olle Eriksson
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, SE-751 20 Uppsala, Sweden
| | - Ján Rusz
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, SE-751 20 Uppsala, Sweden
| | - Andrea M. Goforth
- Department of Chemistry, Portland State University, Portland, Oregon 97201, USA
| | - George V. Nazin
- Department of Chemistry and Biochemistry, Materials Science Institute, Oregon Center for Optical, Molecular and Quantum Science, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403, USA
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Idrobo JC, Rusz J, Spiegelberg J, McGuire MA, Symons CT, Vatsavai RR, Cantoni C, Lupini AR. Detecting magnetic ordering with atomic size electron probes. ACTA ACUST UNITED AC 2016. [DOI: 10.1186/s40679-016-0019-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
AbstractAlthough magnetism originates at the atomic scale, the existing spectroscopic techniques sensitive to magnetic signals only produce spectra with spatial resolution on a larger scale. However, recently, it has been theoretically argued that atomic size electron probes with customized phase distributions can detect magnetic circular dichroism. Here, we report a direct experimental real-space detection of magnetic circular dichroism in aberration-corrected scanning transmission electron microscopy (STEM). Using an atomic size-aberrated electron probe with a customized phase distribution, we reveal the checkerboard antiferromagnetic ordering of Mn moments in LaMnAsO by observing a dichroic signal in the Mn L-edge. The novel experimental setup presented here, which can easily be implemented in aberration-corrected STEM, opens new paths for probing dichroic signals in materials with unprecedented spatial resolution.
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28
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Kocevski V, Eriksson O, Gerard C, Sarma DD, Rusz J. Influence of dimensionality and interface type on optical and electronic properties of CdS/ZnS core-shell nanocrystals--A first-principles study. J Chem Phys 2016; 143:164701. [PMID: 26520537 DOI: 10.1063/1.4933058] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Semiconducting nanocrystals (NCs) have become one of the leading materials in a variety of applications, mainly due to their size tunable band gap and high intensity emission. Their photoluminescence (PL) properties can be notably improved by capping the nanocrystals with a shell of another semiconductor, making core-shell structures. We focus our study on the CdS/ZnS core-shell nanocrystals that are closely related to extensively studied CdSe/CdS NCs, albeit exhibiting rather different photoluminescence properties. We employ density functional theory to investigate the changes in the electronic and optical properties of these nanocrystals with size, core/shell ratio, and interface structure between the core and the shell. We have found that both the lowest unoccupied eigenstate (LUES) and the highest occupied eigenstate (HOES) wavefunction (WF) are localized in the core of the NCs, with the distribution of the LUES WF being more sensitive to the size and the core/shell ratio. We show that the radiative lifetimes are increasing, and the Coulomb interaction energies decrease with increasing NC size. Furthermore, we investigated the electronic and optical properties of the NCs with different interfaces between the core and the shell and different core types. We find that the different interfaces and core types have rather small influence on the band gaps and the absorption indexes, as well as on the confinement of the HOES and LUES WFs. Also the radiative lifetimes are found to be only slightly influenced by the different structural models. In addition, we compare these results with the previous results for CdSe/CdS NCs, reflecting the different PL properties of these two types of NCs. We argue that the difference in their Coulomb interaction energies is one of the main reasons for their distinct PL properties.
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Affiliation(s)
- V Kocevski
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, S-751 20 Uppsala, Sweden
| | - O Eriksson
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, S-751 20 Uppsala, Sweden
| | - C Gerard
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, S-751 20 Uppsala, Sweden
| | - D D Sarma
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, S-751 20 Uppsala, Sweden
| | - J Rusz
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, S-751 20 Uppsala, Sweden
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Abstract
Elastic scattering of electron vortex beams on magnetic materials leads to a weak magnetic contrast due to Zeeman interaction of orbital angular momentum of the beam with magnetic fields in the sample. The magnetic signal manifests itself as a redistribution of intensity in diffraction patterns due to a change of sign of the orbital angular momentum of the electron vortex beam. While in the atomic resolution regime the magnetic signal is most likely under the detection limits of present transmission electron microscopes, for electron probes with high orbital angular momenta, and correspondingly larger spatial extent, its detection is predicted to be feasible.
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Affiliation(s)
- Alexander Edström
- Department of Physics and Astronomy, Uppsala University, Box 516, 75121 Uppsala, Sweden
| | - Axel Lubk
- Triebenberg Laboratory, Technische Universität Dresden, Germany
| | - Ján Rusz
- Department of Physics and Astronomy, Uppsala University, Box 516, 75121 Uppsala, Sweden
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Kislitsyn DA, Kocevski V, Mills JM, Chiu SK, Gervasi CF, Taber BN, Rosenfield AE, Eriksson O, Rusz J, Goforth AM, Nazin GV. Mapping of Defects in Individual Silicon Nanocrystals Using Real-Space Spectroscopy. J Phys Chem Lett 2016; 7:1047-1054. [PMID: 26938674 DOI: 10.1021/acs.jpclett.6b00176] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The photophysical properties of silicon semiconductor nanocrystals (SiNCs) are extremely sensitive to the presence of surface chemical defects, many of which are easily produced by oxidation under ambient conditions. The diversity of chemical structures of such defects and the lack of tools capable of probing individual defects continue to impede understanding of the roles of these defects in SiNC photophysics. We use scanning tunneling spectroscopy to study the impact of surface defects on the electronic structures of hydrogen-passivated SiNCs supported on the Au(111) surface. Spatial maps of the local electronic density of states (LDOS) produced by our measurements allowed us to identify locally enhanced defect-induced states as well as quantum-confined states delocalized throughout the SiNC volume. We use theoretical calculations to show that the LDOS spectra associated with the observed defects are attributable to Si-O-Si bridged oxygen or Si-OH surface defects.
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Affiliation(s)
- Dmitry A Kislitsyn
- Department of Chemistry and Biochemistry, Materials Science Institute, Oregon Center for Optical, Molecular and Quantum Science, University of Oregon , 1253 University of Oregon, Eugene, Oregon 97403, United States
| | - Vancho Kocevski
- Department of Physics and Astronomy, Uppsala University , Box 516, SE-751 20 Uppsala, Sweden
| | - Jon M Mills
- Department of Chemistry and Biochemistry, Materials Science Institute, Oregon Center for Optical, Molecular and Quantum Science, University of Oregon , 1253 University of Oregon, Eugene, Oregon 97403, United States
| | - Sheng-Kuei Chiu
- Department of Chemistry, Portland State University , Portland, Oregon 97201, United States
| | - Christian F Gervasi
- Department of Chemistry and Biochemistry, Materials Science Institute, Oregon Center for Optical, Molecular and Quantum Science, University of Oregon , 1253 University of Oregon, Eugene, Oregon 97403, United States
| | - Benjamen N Taber
- Department of Chemistry and Biochemistry, Materials Science Institute, Oregon Center for Optical, Molecular and Quantum Science, University of Oregon , 1253 University of Oregon, Eugene, Oregon 97403, United States
| | - Ariel E Rosenfield
- Department of Chemistry and Biochemistry, Materials Science Institute, Oregon Center for Optical, Molecular and Quantum Science, University of Oregon , 1253 University of Oregon, Eugene, Oregon 97403, United States
| | - Olle Eriksson
- Department of Physics and Astronomy, Uppsala University , Box 516, SE-751 20 Uppsala, Sweden
| | - Ján Rusz
- Department of Physics and Astronomy, Uppsala University , Box 516, SE-751 20 Uppsala, Sweden
| | - Andrea M Goforth
- Department of Chemistry, Portland State University , Portland, Oregon 97201, United States
| | - George V Nazin
- Department of Chemistry and Biochemistry, Materials Science Institute, Oregon Center for Optical, Molecular and Quantum Science, University of Oregon , 1253 University of Oregon, Eugene, Oregon 97403, United States
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31
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Orozco-Arroyave JR, Hönig F, Arias-Londoño JD, Vargas-Bonilla JF, Daqrouq K, Skodda S, Rusz J, Nöth E. Automatic detection of Parkinson's disease in running speech spoken in three different languages. J Acoust Soc Am 2016; 139:481-500. [PMID: 26827042 DOI: 10.1121/1.4939739] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The aim of this study is the analysis of continuous speech signals of people with Parkinson's disease (PD) considering recordings in different languages (Spanish, German, and Czech). A method for the characterization of the speech signals, based on the automatic segmentation of utterances into voiced and unvoiced frames, is addressed here. The energy content of the unvoiced sounds is modeled using 12 Mel-frequency cepstral coefficients and 25 bands scaled according to the Bark scale. Four speech tasks comprising isolated words, rapid repetition of the syllables /pa/-/ta/-/ka/, sentences, and read texts are evaluated. The method proves to be more accurate than classical approaches in the automatic classification of speech of people with PD and healthy controls. The accuracies range from 85% to 99% depending on the language and the speech task. Cross-language experiments are also performed confirming the robustness and generalization capability of the method, with accuracies ranging from 60% to 99%. This work comprises a step forward for the development of computer aided tools for the automatic assessment of dysarthric speech signals in multiple languages.
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Affiliation(s)
- J R Orozco-Arroyave
- Faculty of Engineering, Universidad de Antioquia, Calle 67 Número 53-108, Medellín 1226, Colombia
| | - F Hönig
- Pattern Recognition Lab, Friedrich-Alexander-Universität, Erlangen-Nürnberg, Martensstraβe 3, Erlangen 91058, Germany
| | - J D Arias-Londoño
- Faculty of Engineering, Universidad de Antioquia, Calle 67 Número 53-108, Medellín 1226, Colombia
| | - J F Vargas-Bonilla
- Faculty of Engineering, Universidad de Antioquia, Calle 67 Número 53-108, Medellín 1226, Colombia
| | - K Daqrouq
- Department of Electrical and Computer Engineering, King Abdulaziz University, Jeddah 22254, Saudi Arabia
| | - S Skodda
- Department of Neurology, Knappschaftskrankenhaus, Ruhr-University, In der Schornau 23-25, Bochum D-44892, Germany
| | - J Rusz
- Department of Circuit Theory, Faculty of Electrical Engineering, Czech Technical University in Prague, Technicka 2, 166 27 Prague 6, Czech Republic
| | - E Nöth
- Pattern Recognition Lab, Friedrich-Alexander-Universität, Erlangen-Nürnberg, Martensstraβe 3, Erlangen 91058, Germany
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32
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Reichel L, Schultz L, Pohl D, Oswald S, Fähler S, Werwiński M, Edström A, Delczeg-Czirjak EK, Rusz J. From soft to hard magnetic Fe-Co-B by spontaneous strain: a combined first principles and thin film study. J Phys Condens Matter 2015; 27:476002. [PMID: 26548574 DOI: 10.1088/0953-8984/27/47/476002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In order to convert the well-known Fe-Co-B alloy from a soft to a hard magnet, we propose tetragonal strain by interstitial boron. Density functional theory reveals that when B atoms occupy octahedral interstitial sites, the bcc Fe-Co lattice is strained spontaneously. Such highly distorted Fe-Co is predicted to reach a strong magnetocrystalline anisotropy which may compete with shape anisotropy. To probe this theoretical suggestion experimentally, epitaxial films are examined. A spontaneous strain up to 5% lattice distortion is obtained for B content up to 4 at%, which leads to uniaxial anisotropy constants exceeding 0.5 MJ m(-3). However, a further addition of B results in a partial amorphisation, which degrades both anisotropy and magnetisation.
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Affiliation(s)
- L Reichel
- IFW Dresden, 01171 Dresden, Germany. Faculty of Mechanical Engineering, Institute of Materials Science, TU Dresden, 01062 Dresden, Germany
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33
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Tykalová T, Hlavnická J, Macáková M, Baxa M, Cmejla R, Motlík J, Klempíř J, Rusz J. Grunting in a Genetically Modified Minipig Animal Model for Huntington’s Disease –
Pilot Experiments. Cesk Slov Neurol N 2015. [DOI: 10.14735/amcsnn20152s61] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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34
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Spiegelberg J, Rusz J. A multislice theory of electron scattering in crystals including backscattering and inelastic effects. Ultramicroscopy 2015; 159 Pt 1:11-8. [PMID: 26241300 DOI: 10.1016/j.ultramic.2015.07.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 06/11/2015] [Accepted: 07/21/2015] [Indexed: 10/23/2022]
Abstract
In the framework of the slice transition operator technique, a general multislice theory for electron scattering in crystals is developed. To achieve this generalization, we combine the approaches for inelastic scattering derived by Yoshioka [J. Phys. Soc. Jpn. 12, 6 (1957)] and backscattering based on the formalism of Chen and Van Dyck [Ultramicroscopy 70, 29-44 (1997)]. A computational realization of the obtained equations is suggested. The proposed computational scheme is tested on elastic backscattering of electrons, where we consider single backscattering in analogy to the computational scheme proposed by Chen and Van Dyck.
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Affiliation(s)
- Jakob Spiegelberg
- Department of Physics and Astronomy, Uppsala University, Box 516, S-751 20 Uppsala, Sweden
| | - Ján Rusz
- Department of Physics and Astronomy, Uppsala University, Box 516, S-751 20 Uppsala, Sweden
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35
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Kocevski V, Rusz J, Eriksson O, Sarma DD. First-principles study of the influence of different interfaces and core types on the properties of CdSe/CdS core-shell nanocrystals. Sci Rep 2015; 5:10865. [PMID: 26039582 PMCID: PMC4454155 DOI: 10.1038/srep10865] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 05/05/2015] [Indexed: 11/09/2022] Open
Abstract
With the expanding field of nanoengineering and the production of nanocrystals (NCs) with higher quality and tunable size, having reliable theoretical calculations to complement the experimental results is very important. Here we present such a study of CdSe/CdS core-shell NCs using density functional theory, where we focus on dependence of the properties of these NCs on core types and interfaces between the core and the shell, as well as on the core/shell ratio. We show that the density of states and the absorption indices depend rather weakly on the type of interface and core type. We demonstrate that the HOMO wavefunction is mainly localised in the core of the nanocrystal, depending primarily on the core/shell ratio. On the other hand the LUMO wavefunction spreads more into the shell of the nanocrystal, where its confinement in the core is almost the same in each of the studied structural models. Furthermore, we show that the radiative lifetimes decrease with increasing core sizes due to changes in the dipolar overlap integral of the HOMO and LUMO wavefunctions. In addition, the electron-hole Coulomb interaction energies follow a similar pattern as the localisation of the wavefunctions, with the smaller NCs having higher Coulomb interaction energies.
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Affiliation(s)
- V Kocevski
- Department of Physics and Astronomy, Uppsala University, Box 516, S-751 20 Uppsala, Sweden
| | - J Rusz
- Department of Physics and Astronomy, Uppsala University, Box 516, S-751 20 Uppsala, Sweden
| | - O Eriksson
- Department of Physics and Astronomy, Uppsala University, Box 516, S-751 20 Uppsala, Sweden
| | - D D Sarma
- 1] Department of Physics and Astronomy, Uppsala University, Box 516, S-751 20 Uppsala, Sweden [2] Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore-560 012, India
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36
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Magnani N, Caciuffo R, Wilhelm F, Colineau E, Eloirdi R, Griveau JC, Rusz J, Oppeneer PM, Rogalev A, Lander GH. Magnetic polarization of the americium J=0 ground state in AmFe(2). Phys Rev Lett 2015; 114:097203. [PMID: 25793847 DOI: 10.1103/physrevlett.114.097203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Indexed: 06/04/2023]
Abstract
Trivalent americium has a nonmagnetic (J=0) ground state arising from the cancellation of the orbital and spin moments. However, magnetism can be induced by a large molecular field if Am^{3+} is embedded in a ferromagnetic matrix. Using the technique of x-ray magnetic circular dichroism, we show that this is the case in AmFe_{2}. Since ⟨J_{z}⟩=0, the spin component is exactly twice as large as the orbital one, the total Am moment is opposite to that of Fe, and the magnetic dipole operator ⟨T_{z}⟩ can be determined directly; we discuss the progression of the latter across the actinide series.
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Affiliation(s)
- N Magnani
- European Commission, Joint Research Centre (JRC), Institute for Transuranium Elements (ITU), Postfach 2340, D-76125 Karlsruhe, Germany
| | - R Caciuffo
- European Commission, Joint Research Centre (JRC), Institute for Transuranium Elements (ITU), Postfach 2340, D-76125 Karlsruhe, Germany
| | - F Wilhelm
- European Synchrotron Radiation Facility (ESRF), Boîte Postale 220, F-38043 Grenoble, France
| | - E Colineau
- European Commission, Joint Research Centre (JRC), Institute for Transuranium Elements (ITU), Postfach 2340, D-76125 Karlsruhe, Germany
| | - R Eloirdi
- European Commission, Joint Research Centre (JRC), Institute for Transuranium Elements (ITU), Postfach 2340, D-76125 Karlsruhe, Germany
| | - J-C Griveau
- European Commission, Joint Research Centre (JRC), Institute for Transuranium Elements (ITU), Postfach 2340, D-76125 Karlsruhe, Germany
| | - J Rusz
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, S-75120 Uppsala, Sweden
| | - P M Oppeneer
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, S-75120 Uppsala, Sweden
| | - A Rogalev
- European Synchrotron Radiation Facility (ESRF), Boîte Postale 220, F-38043 Grenoble, France
| | - G H Lander
- European Commission, Joint Research Centre (JRC), Institute for Transuranium Elements (ITU), Postfach 2340, D-76125 Karlsruhe, Germany
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37
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Rusz J, Idrobo JC, Bhowmick S. Achieving atomic resolution magnetic dichroism by controlling the phase symmetry of an electron probe. Phys Rev Lett 2014; 113:145501. [PMID: 25325649 DOI: 10.1103/physrevlett.113.145501] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Indexed: 06/04/2023]
Abstract
The calculations presented here reveal that an electron probe carrying orbital angular momentum is just a particular case of a wider class of electron beams that can be used to measure electron magnetic circular dichroism (EMCD) with atomic resolution. It is possible to obtain an EMCD signal with atomic resolution by simply breaking the symmetry of the electron probe phase distribution using the aberration-corrected optics of a scanning transmission electron microscope. The required phase distribution of the probe depends on the magnetic symmetry and crystal structure of the sample. The calculations indicate that EMCD signals utilizing the phase of the electron probe are as strong as those obtained by nanodiffraction methods.
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Affiliation(s)
- Ján Rusz
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, 75120 Uppsala, Sweden
| | - Juan-Carlos Idrobo
- Center of Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Somnath Bhowmick
- Department of Materials Science and Engineering, Indian Institute of Technology, Kanpur 208016, India
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38
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Rusz J, Klempir J, Tykalova T, Baborova E, mejla R, R i ka E, Roth J. J17 Could Antipsychotic Medication Influence Speech In Huntington's Disease? J Neurol Psychiatry 2014. [DOI: 10.1136/jnnp-2014-309032.200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Tatsumi K, Muto S, Rusz J, Kudo T, Arai S. Signal enhancement of electron magnetic circular dichroism by ultra-high-voltage TEM, toward quantitative nano-magnetism measurements. Microscopy (Oxf) 2014; 63:243-7. [DOI: 10.1093/jmicro/dfu002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Kazuyoshi Tatsumi
- EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Shunsuke Muto
- EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Ján Rusz
- Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala SE-75120, Sweden
| | - Tomohiro Kudo
- Graduate school of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Shigeo Arai
- EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
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40
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Abstract
Electron energy-loss spectroscopy (EELS) attached to current transmission electron microscopes can probe not only element-selective chemical information, but also site-selective information that depends on the position that a specific element occupies in a crystal lattice. The latter information is exploited by utilizing the Bloch waves symmetry in the crystal, which changes with its orientation with respect to the incident electron wave (electron channeling). We demonstrate the orientation dependence of the cross-section of the electron energy-loss near-edge structure for particular crystalline sites of spinel ferrites, by quantitatively taking into account the dynamical diffraction effects with a large number of the diffracted beams. The theoretical results are consistent with a set of experiments in which the transition metal sites in spinel crystal structures are selectively excited. A new measurement scheme for site-selective EELS using a two-dimensional position-sensitive detector is proposed and validated by theoretical predictions and trial experiments.
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Affiliation(s)
- Kazuyoshi Tatsumi
- Department of Materials, Physics and Energy Engineering, Nagoya University, Chikusa, Nagoya, Aichi Pref. 464-8603, Japan
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41
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Rusz J, Bhowmick S. Boundaries for efficient use of electron vortex beams to measure magnetic properties. Phys Rev Lett 2013; 111:105504. [PMID: 25166681 DOI: 10.1103/physrevlett.111.105504] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2013] [Indexed: 05/14/2023]
Abstract
Development of experimental techniques for characterization of magnetic properties at high spatial resolution is essential for progress in miniaturization of magnetic devices, for example, in data storage media. Inelastic scattering of electron vortex beams (EVBs) was recently reported to contain atom-specific magnetic information. We develop a theoretical description of inelastic scattering of EVBs on crystals and perform simulations for EVBs of different diameters. We show that use of an EVB wider than an interatomic distance does not provide any advantage over an ordinary convergent beam without angular momentum. On the other hand, in the atomic-resolution limit, electron energy loss spectra measured by EVBs are strongly sensitive to the spin and orbital magnetic moments of studied matter, when channeling through or very close to the atomic columns. Our results demonstrate the boundaries for efficient use of EVBs in measurement of magnetic properties.
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Affiliation(s)
- Ján Rusz
- Department of Physics and Astronomy, Uppsala University, Post Office Box 516, 75120 Uppsala, Sweden and Institute of Physics, Czech Academy of Sciences, Na Slovance 2, 182 21 Prague, Czech Republic
| | - Somnath Bhowmick
- Department of Physics and Astronomy, Uppsala University, Post Office Box 516, 75120 Uppsala, Sweden and Department of Materials Science and Engineering, Indian Institute of Technology, Kanpur 208016, India
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42
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Bidermane I, Lüder J, Boudet S, Zhang T, Ahmadi S, Grazioli C, Bouvet M, Rusz J, Sanyal B, Eriksson O, Brena B, Puglia C, Witkowski N. Experimental and theoretical study of electronic structure of lutetium bi-phthalocyanine. J Chem Phys 2013; 138:234701. [DOI: 10.1063/1.4809725] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
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Rusz J, Muto S, Tatsumi K. New algorithm for efficient Bloch-waves calculations of orientation-sensitive ELNES. Ultramicroscopy 2013; 125:81-8. [DOI: 10.1016/j.ultramic.2012.09.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Revised: 09/03/2012] [Accepted: 09/23/2012] [Indexed: 10/27/2022]
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Muto S, Tatsumi K, Rusz J. Parameter-free extraction of EMCD from an energy-filtered diffraction datacube using multivariate curve resolution. Ultramicroscopy 2013; 125:89-96. [DOI: 10.1016/j.ultramic.2012.09.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Revised: 09/15/2012] [Accepted: 09/23/2012] [Indexed: 11/30/2022]
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Vinogradov NA, Zakharov AA, Kocevski V, Rusz J, Simonov KA, Eriksson O, Mikkelsen A, Lundgren E, Vinogradov AS, Mårtensson N, Preobrajenski AB. Formation and structure of graphene waves on Fe(110). Phys Rev Lett 2012; 109:026101. [PMID: 23030182 DOI: 10.1103/physrevlett.109.026101] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Indexed: 06/01/2023]
Abstract
A very rich Fe-C phase diagram makes the formation of graphene on iron surfaces a challenging task. Here we demonstrate that the growth of graphene on epitaxial iron films can be realized by chemical vapor deposition at relatively low temperatures, and that the formation of carbides can be avoided in excess of the carbon-containing precursors. The resulting graphene monolayer creates a novel periodically corrugated pattern on Fe(110). Using low-energy electron microscopy and scanning tunneling microscopy, we show that it is modulated in one dimension forming long waves with a period of ∼4 nm parallel to the [001] direction of the substrate, with an additional height modulation along the wave crests. The observed topography of the graphene/Fe superstructure is well reproduced by density functional theory calculations, and found to result from a unique combination of the lattice mismatch and strong interfacial interaction, as probed by core-level photoemission and x-ray absorption spectroscopy.
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Affiliation(s)
- N A Vinogradov
- Department of Physics and Astronomy, Uppsala University, Box 530, 75121 Uppsala, Sweden
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46
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Rusz J, Cmejla R, Ruzickova H, Ruzicka E. Quantitative acoustic measurements for characterization of speech and voice disorders in early untreated Parkinson's disease. J Acoust Soc Am 2011; 129:350-367. [PMID: 21303016 DOI: 10.1121/1.3514381] [Citation(s) in RCA: 185] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
An assessment of vocal impairment is presented for separating healthy people from persons with early untreated Parkinson's disease (PD). This study's main purpose was to (a) determine whether voice and speech disorder are present from early stages of PD before starting dopaminergic pharmacotherapy, (b) ascertain the specific characteristics of the PD-related vocal impairment, (c) identify PD-related acoustic signatures for the major part of traditional clinically used measurement methods with respect to their automatic assessment, and (d) design new automatic measurement methods of articulation. The varied speech data were collected from 46 Czech native speakers, 23 with PD. Subsequently, 19 representative measurements were pre-selected, and Wald sequential analysis was then applied to assess the efficiency of each measure and the extent of vocal impairment of each subject. It was found that measurement of the fundamental frequency variations applied to two selected tasks was the best method for separating healthy from PD subjects. On the basis of objective acoustic measures, statistical decision-making theory, and validation from practicing speech therapists, it has been demonstrated that 78% of early untreated PD subjects indicate some form of vocal impairment. The speech defects thus uncovered differ individually in various characteristics including phonation, articulation, and prosody.
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Affiliation(s)
- J Rusz
- Department of Circuit Theory, Faculty of Electrical Engineering, Czech Technical University in Prague, Technicka 2, 116 27, Prague 6, Czech Republic.
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47
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Lidbaum H, Rusz J, Rubino S, Liebig A, Hjörvarsson B, Oppeneer PM, Eriksson O, Leifer K. Reciprocal and real space maps for EMCD experiments. Ultramicroscopy 2010; 110:1380-9. [DOI: 10.1016/j.ultramic.2010.07.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 06/28/2010] [Accepted: 07/08/2010] [Indexed: 10/19/2022]
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49
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Kofránek J, Rusz J. Restoration of Guyton´s diagram for regulation of the circulation as a basis for quantitative physiological model development. Physiol Res 2010; 59:897-908. [PMID: 20533860 DOI: 10.33549/physiolres.931838] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
We present the current state of complex circulatory dynamics model development based on Guyton's famous diagram. The aim is to provide an open-source model that will allow the simulation of a number of pathological conditions on a virtual patient including cardiac, respiratory, and kidney failure. The model will also simulate the therapeutic influence of various drugs, infusions of electrolytes, blood transfusion, etc. As a current result of implementation, we describe a core model of human physiology targeting the systemic circulation, arterial pressure and body fluid regulation, including short- and long-term regulations. The model can be used for educational purposes and general reflection on physiological regulation in pathogenesis of various diseases.
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Affiliation(s)
- J Kofránek
- Department of Circuit Theory, Faculty of Electrical Engineering, Czech Technical University, Prague, Czech Republic
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Valencia S, Kleibert A, Gaupp A, Rusz J, Legut D, Bansmann J, Gudat W, Oppeneer PM. Quadratic X-ray magneto-optical effect upon reflection in a near-normal-incidence configuration at the M edges of 3d-transition metals. Phys Rev Lett 2010; 104:187401. [PMID: 20482206 DOI: 10.1103/physrevlett.104.187401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Indexed: 05/22/2023]
Abstract
We have observed a quadratic x-ray magneto-optical effect in near-normal-incidence reflection at the M edges of iron. The effect appears as the magnetically induced rotation of approximately 0.1 degrees of the polarization plane of linearly polarized x-ray radiation upon reflection. A comparison of the measured rotation spectrum with results from x-ray magnetic linear dichroism data demonstrates that this is the first observation of the Schäfer-Hubert effect in the x-ray regime. Ab initio density-functional theory calculations reveal that hybridization effects of the 3p core states necessarily need to be considered when interpreting experimental data. The discovered magneto-x-ray effect holds promise for future ultrafast and element-selective studies of ferromagnetic as well as antiferromagnetic materials.
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Affiliation(s)
- S Valencia
- Helmholtz-Zentrum-Berlin, BESSY, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany.
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