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Ritzel RM, Li Y, Jiao Y, Doran SJ, Khan N, Henry RJ, Brunner K, Loane DJ, Faden AI, Szeto GL, Wu J. Bi-directional neuro-immune dysfunction after chronic experimental brain injury. J Neuroinflammation 2024; 21:83. [PMID: 38581043 PMCID: PMC10996305 DOI: 10.1186/s12974-024-03082-y] [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] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Accepted: 03/30/2024] [Indexed: 04/07/2024] Open
Abstract
BACKGROUND It is well established that traumatic brain injury (TBI) causes acute and chronic alterations in systemic immune function and that systemic immune changes contribute to posttraumatic neuroinflammation and neurodegeneration. However, how TBI affects bone marrow (BM) hematopoietic stem/progenitor cells chronically and to what extent such changes may negatively impact innate immunity and neurological function has not been examined. METHODS To further understand the role of BM cell derivatives on TBI outcome, we generated BM chimeric mice by transplanting BM from chronically injured or sham (i.e., 90 days post-surgery) congenic donor mice into otherwise healthy, age-matched, irradiated CD45.2 C57BL/6 (WT) hosts. Immune changes were evaluated by flow cytometry, multiplex ELISA, and NanoString technology. Moderate-to-severe TBI was induced by controlled cortical impact injury and neurological function was measured using a battery of behavioral tests. RESULTS TBI induced chronic alterations in the transcriptome of BM lineage-c-Kit+Sca1+ (LSK+) cells in C57BL/6 mice, including modified epigenetic and senescence pathways. After 8 weeks of reconstitution, peripheral myeloid cells from TBI→WT mice showed significantly higher oxidative stress levels and reduced phagocytic activity. At eight months after reconstitution, TBI→WT chimeric mice were leukopenic, with continued alterations in phagocytosis and oxidative stress responses, as well as persistent neurological deficits. Gene expression analysis revealed BM-driven changes in neuroinflammation and neuropathology after 8 weeks and 8 months of reconstitution, respectively. Chimeric mice subjected to TBI at 8 weeks and 8 months post-reconstitution showed that longer reconstitution periods (i.e., time post-injury) were associated with increased microgliosis and leukocyte infiltration. Pre-treatment with a senolytic agent, ABT-263, significantly improved behavioral performance of aged C57BL/6 mice at baseline, although it did not attenuate neuroinflammation in the acutely injured brain. CONCLUSIONS TBI causes chronic activation and progressive dysfunction of the BM stem/progenitor cell pool, which drives long-term deficits in hematopoiesis, innate immunity, and neurological function, as well as altered sensitivity to subsequent brain injury.
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Affiliation(s)
- Rodney M Ritzel
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.
- Department of Neurology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, 77030, USA.
| | - Yun Li
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Yun Jiao
- Department of Chemical, Biochemical and Environmental Engineering, University of Maryland, Baltimore County, Baltimore, MD, 21250, USA
| | - Sarah J Doran
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Niaz Khan
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Rebecca J Henry
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Kavitha Brunner
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - David J Loane
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Alan I Faden
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Gregory L Szeto
- Department of Chemical, Biochemical and Environmental Engineering, University of Maryland, Baltimore County, Baltimore, MD, 21250, USA
| | - Junfang Wu
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.
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Ritzel RM, Li Y, Jiao Y, Doran SJ, Khan N, Henry RJ, Brunner K, Loane DJ, Faden AI, Szeto GL, Wu J. The brain-bone marrow axis and its implications for chronic traumatic brain injury. Res Sq 2023:rs.3.rs-3356007. [PMID: 37790560 PMCID: PMC10543403 DOI: 10.21203/rs.3.rs-3356007/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
Traumatic brain injury (TBI) causes acute and chronic alterations in systemic immune function which contribute to posttraumatic neuroinflammation and neurodegeneration. However, how TBI affects bone marrow (BM) hematopoietic stem/progenitor cells chronically and to what extent such changes may negatively impact innate immunity and neurological function has not been examined. To further understand the role of BM cell derivatives on TBI outcome, we generated BM chimeric mice by transplanting BM from chronically injured or sham congenic donor mice into otherwise healthy, age-matched, irradiated hosts. After 8 weeks of reconstitution, peripheral myeloid cells from TBI→WT mice showed significantly higher oxidative stress levels and reduced phagocytic activity. At eight months after reconstitution, TBI→WT chimeric mice were leukopenic, with continued alterations in phagocytosis and oxidative stress responses, as well as persistent neurological deficits. Gene expression analysis revealed BM-driven changes in neuroinflammation and neuropathology after 8 weeks and 8 months of reconstitution, respectively. Chimeric mice subjected to TBI showed that longer reconstitution periods were associated with increased microgliosis and leukocyte infiltration. Thus, TBI causes chronic activation and progressive dysfunction of the BM stem/progenitor cell pool, which drives long-term deficits in innate immunity and neurological function, as well as altered sensitivity to subsequent brain injury.
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Affiliation(s)
- Rodney M. Ritzel
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
- Department of Neurology, McGovern Medical School, The University of Texas Health Science Center at Houston, Texas, USA
| | - Yun Li
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Yun Jiao
- Department of Chemical, Biochemical and Environmental Engineering, University of Maryland, Baltimore County, Maryland, USA
| | - Sarah J. Doran
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Niaz Khan
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Rebecca J. Henry
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Kavitha Brunner
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - David J. Loane
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Alan I. Faden
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Gregory L. Szeto
- Department of Chemical, Biochemical and Environmental Engineering, University of Maryland, Baltimore County, Maryland, USA
| | - Junfang Wu
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland, USA
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Lei Z, Krishnamachary B, Ritzel RM, Khan NZ, Li Y, Li H, Brunner K, Faden AI, Wu J. Age-related changes in plasma extracellular vesicles influence neuroinflammation in the brain and neurological outcome after traumatic spinal cord injury. Res Sq 2023:rs.3.rs-2821858. [PMID: 37131758 PMCID: PMC10153385 DOI: 10.21203/rs.3.rs-2821858/v1] [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] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Approximately 20% of all spinal cord injuries (SCI) occur in persons aged 65 years or older. Longitudinal, population-based studies showed that SCI is a risk factor for dementia. However, little research has addressed the potential mechanisms of SCI-mediated neurological impairment in the elderly. We compared young adult and aged C57BL/6 male mice subjected to contusion SCI, using a battery of neurobehavioral tests. Locomotor function showed greater impairment in aged mice, which was correlated with reduced, spared spinal cord white matter and increased lesion volume. At 2 months post-injury, aged mice displayed worse performance in cognitive and depressive-like behavioral tests. Transcriptomic analysis identified activated microglia and dysregulated autophagy as the most significantly altered pathways by both age and injury. Flow cytometry demonstrated increased myeloid and lymphocyte infiltration at both the injury site and brain of aged mice. SCI in aged mice was associated with altered microglial function and dysregulated autophagy involving both microglia and brain neurons. Altered plasma extracellular vesicles (EVs) responses were found in aged mice after acute SCI. EV-microRNA cargos were also significantly altered by aging and injury, which were associated with neuroinflammation and autophagy dysfunction. In cultured microglia, astrocytes, and neurons, plasma EVs from aged SCI mice, at a lower concentration comparable to those of young adult SCI mice, induced the secretion of pro-inflammatory cytokines CXCL2 and IL-6, and increased caspase3 expression. Together, these findings suggest that age alters the EVs pro-inflammatory response to SCI, potentially contributing to worse neuropathological and functional outcomes.
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Affiliation(s)
- Zhuofan Lei
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Balaji Krishnamachary
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Rodney M. Ritzel
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Niaz Z. Khan
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Yun Li
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Hui Li
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Kavitha Brunner
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Alan I. Faden
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Junfang Wu
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD 21201, USA
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Henzler P, Traum C, Holtkemper M, Nabben D, Erbe M, Reiter DE, Kuhn T, Mahapatra S, Brunner K, Seletskiy DV, Leitenstorfer A. Femtosecond Transfer and Manipulation of Persistent Hot-Trion Coherence in a Single CdSe/ZnSe Quantum Dot. Phys Rev Lett 2021; 126:067402. [PMID: 33635695 DOI: 10.1103/physrevlett.126.067402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 12/07/2020] [Indexed: 06/12/2023]
Abstract
Ultrafast transmission changes around the fundamental trion resonance are studied after exciting a p-shell exciton in a negatively charged II-VI quantum dot. The biexcitonic induced absorption reveals quantum beats between hot-trion states at 133 GHz. While interband dephasing is dominated by relaxation of the P-shell hole within 390 fs, trionic coherence remains stored in the spin system for 85 ps due to Pauli blocking of the triplet electron. The complex spectrotemporal evolution of transmission is explained analytically by solving the Maxwell-Liouville equations. Pump and probe polarizations provide full control over amplitude and phase of the quantum beats.
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Affiliation(s)
- P Henzler
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany
| | - C Traum
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany
| | - M Holtkemper
- Institute of Solid State Theory, University of Münster, D-48149 Münster, Germany
| | - D Nabben
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany
| | - M Erbe
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany
| | - D E Reiter
- Institute of Solid State Theory, University of Münster, D-48149 Münster, Germany
| | - T Kuhn
- Institute of Solid State Theory, University of Münster, D-48149 Münster, Germany
| | - S Mahapatra
- Institute of Physics, EP3, University of Würzburg, D-97074 Würzburg, Germany
| | - K Brunner
- Institute of Physics, EP3, University of Würzburg, D-97074 Würzburg, Germany
| | - D V Seletskiy
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany
- Department of Engineering Physics, Polytechnique Montréal, Montréal, Québec H3T 1J4, Canada
| | - A Leitenstorfer
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany
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5
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Traum C, Henzler P, Lohner S, Becker H, Nabben D, Gumbsheimer P, Hinz C, Lippmann JF, Mahapatra S, Brunner K, Seletskiy DV, Leitenstorfer A. Multicolor femtosecond pump-probe system with single-electron sensitivity at low temperatures and high magnetic fields. Rev Sci Instrum 2019; 90:123003. [PMID: 31893859 DOI: 10.1063/1.5126157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 11/30/2019] [Indexed: 06/10/2023]
Abstract
We present an ultrafast spectroscopy system designed for temporal and spectral resolution of transient transmission changes after excitation of single electrons in solid-state quantum structures. The system is designed for optimum long-term stability, offering the option of hands-off operation over several days. Pump and probe pulses are generated in a versatile Er:fiber laser system where visible photon energies may be tuned independently from 1.90 eV to 2.51 eV in three parallel branches. Bandwidth-limited pulse durations between 100 fs and 10 ps are available. The solid-state quantum systems under investigation are mounted in a closed-cycle superconducting magnet cryostat providing temperatures down to 1.6 K and magnetic fields of up to 9 T. The free-standing cryomagnet is coupled to the laser system by means of a high-bandwidth active beam steering unit to eliminate residual low-frequency mechanical vibrations of the pulse tube coolers. High-NA objective lenses inside the sample chamber are employed for focusing femtosecond laser pulses onto the sample and recollection of the transmission signal. The transmitted probe light is dispersed in a grating monochromator equipped with a liquid nitrogen-cooled CCD camera, enabling a frame rate of 559 Hz. In order to eliminate spurious background effects due to low-frequency changes in the thermal equilibrium of the sample, we operate with a lock-in scheme where, instead of the pump amplitude, the pump-probe timing is modulated. This feature is provided without any mechanical action by an electro-optic timing unit inside the femtosecond Er:fiber system. The performance of the instrument is tested with spectrally resolved pump-probe measurements on a single negatively charged CdSe/ZnSe quantum dot under a magnetic field of 9 T. Selective initialization and readout of charge and spin states is carried out via two different femtosecond laser pulses. High-quality results on subpicosecond intraband relaxation dynamics after single-electron excitation motivate a broad variety of future experiments in ultrafast quantum optics and few-fermion quantum dynamics.
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Affiliation(s)
- C Traum
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78464 Konstanz, Germany
| | - P Henzler
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78464 Konstanz, Germany
| | - S Lohner
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78464 Konstanz, Germany
| | - H Becker
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78464 Konstanz, Germany
| | - D Nabben
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78464 Konstanz, Germany
| | - P Gumbsheimer
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78464 Konstanz, Germany
| | - C Hinz
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78464 Konstanz, Germany
| | - J F Lippmann
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78464 Konstanz, Germany
| | - S Mahapatra
- Institute of Physics, EP3, University of Würzburg, D-97074 Würzburg, Germany
| | - K Brunner
- Institute of Physics, EP3, University of Würzburg, D-97074 Würzburg, Germany
| | - D V Seletskiy
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78464 Konstanz, Germany
| | - A Leitenstorfer
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78464 Konstanz, Germany
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6
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Grauer S, Fijalkowski KM, Schreyeck S, Winnerlein M, Brunner K, Thomale R, Gould C, Molenkamp LW. Scaling of the Quantum Anomalous Hall Effect as an Indicator of Axion Electrodynamics. Phys Rev Lett 2017; 118:246801. [PMID: 28665643 DOI: 10.1103/physrevlett.118.246801] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Indexed: 06/07/2023]
Abstract
We report on the scaling behavior of V-doped (Bi,Sb)_{2}Te_{3} samples in the quantum anomalous Hall regime for samples of various thickness. While previous quantum anomalous Hall measurements showed the same scaling as expected from a two-dimensional integer quantum Hall state, we observe a dimensional crossover to three spatial dimensions as a function of layer thickness. In the limit of a sufficiently thick layer, we find scaling behavior matching the flow diagram of two parallel conducting topological surface states of a three-dimensional topological insulator each featuring a fractional shift of 1/2e^{2}/h in the flow diagram Hall conductivity, while we recover the expected integer quantum Hall behavior for thinner layers. This constitutes the observation of a distinct type of quantum anomalous Hall effect, resulting from 1/2e^{2}/h Hall conductance quantization of three-dimensional topological insulator surface states, in an experiment which does not require decomposition of the signal to separate the contribution of two surfaces. This provides a possible experimental link between quantum Hall physics and axion electrodynamics.
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Affiliation(s)
- S Grauer
- Faculty for Physics and Astronomy (EP3 and TP1), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - K M Fijalkowski
- Faculty for Physics and Astronomy (EP3 and TP1), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - S Schreyeck
- Faculty for Physics and Astronomy (EP3 and TP1), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - M Winnerlein
- Faculty for Physics and Astronomy (EP3 and TP1), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - K Brunner
- Faculty for Physics and Astronomy (EP3 and TP1), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - R Thomale
- Faculty for Physics and Astronomy (EP3 and TP1), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - C Gould
- Faculty for Physics and Astronomy (EP3 and TP1), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - L W Molenkamp
- Faculty for Physics and Astronomy (EP3 and TP1), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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Tarakina NV, Schreyeck S, Duchamp M, Karczewski G, Gould C, Brunner K, Dunin-Borkowski RE, Molenkamp LW. Microstructural characterization of Cr-doped (Bi,Sb)2Te3thin films. CrystEngComm 2017. [DOI: 10.1039/c7ce00872d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Skorpenske R, Solis R, Moy S, Wiltz E, McAfee C, Brunner K, Doerges C. Novel Technology for the Manufacture of All Water-Blown Flexible Slabstock Foam. J CELL PLAST 2016. [DOI: 10.1177/0021955x9302900513] [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] [Indexed: 11/17/2022]
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9
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Schreyeck S, Brunner K, Kirchner A, Bass U, Grauer S, Schumacher C, Gould C, Karczewski G, Geurts J, Molenkamp LW. Kinetic limitation of chemical ordering in Bi2Te3-x Se x layers grown by molecular beam epitaxy. J Phys Condens Matter 2016; 28:145002. [PMID: 26962934 DOI: 10.1088/0953-8984/28/14/145002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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
We study the chemical ordering in Bi2Te3-x Se x grown by molecular beam epitaxy on Si substrates. We produce films in the full composition range from x = 0 to 3, and determine their material properties using energy dispersive x-ray spectroscopy, x-ray diffraction and Raman spectroscopy. By fitting the parameters of a kinetic growth model to these results, we obtain a consistent description of growth at a microscopic level. Our main finding is that despite the incorporation of Se in the central layer being much more probable than that of Te, the formation of a fully ordered Te-Bi-Se-Bi-Te layer is prevented by kinetic of the growth process. Indeed, the Se concentration in the central layer of Bi2Te2Se1 reaches a maximum of only ≈ 75% even under ideal growth conditions. A second finding of our work is that the intensity ratio of the 0 0 12 and 0 0 6 x-ray reflections serves as an experimentally accessible quantitative measure of the degree of ordering in these films.
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Affiliation(s)
- S Schreyeck
- Physikalisches Institut, Experimentelle Physik 3 and Wilhelm-Conrad Röntgen-Research Center for Complex Material Systems, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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10
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Orlita M, Piot BA, Martinez G, Kumar NKS, Faugeras C, Potemski M, Michel C, Hankiewicz EM, Brauner T, Drašar Č, Schreyeck S, Grauer S, Brunner K, Gould C, Brüne C, Molenkamp LW. Magneto-optics of massive dirac fermions in bulk Bi2Se3. Phys Rev Lett 2015; 114:186401. [PMID: 26001011 DOI: 10.1103/physrevlett.114.186401] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Indexed: 05/27/2023]
Abstract
We report on magneto-optical studies of Bi2Se3, a representative member of the 3D topological insulator family. Its electronic states in bulk are shown to be well described by a simple Dirac-type Hamiltonian for massive particles with only two parameters: the fundamental band gap and the band velocity. In a magnetic field, this model implies a unique property-spin splitting equal to twice the cyclotron energy: Es=2Ec. This explains the extensive magnetotransport studies concluding a fortuitous degeneracy of the spin and orbital split Landau levels in this material. The Es=2Ec match differentiates the massive Dirac electrons in bulk Bi2Se3 from those in quantum electrodynamics, for which Es=Ec always holds.
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Affiliation(s)
- M Orlita
- Laboratoire National des Champs Magnétiques Intenses, CNRS-UJF-UPS-INSA, 25, avenue des Martyrs, 38042 Grenoble, France
- Institute of Physics, Charles University in Prague, CZ-12116 Prague, Czech Republic
| | - B A Piot
- Laboratoire National des Champs Magnétiques Intenses, CNRS-UJF-UPS-INSA, 25, avenue des Martyrs, 38042 Grenoble, France
| | - G Martinez
- Laboratoire National des Champs Magnétiques Intenses, CNRS-UJF-UPS-INSA, 25, avenue des Martyrs, 38042 Grenoble, France
| | - N K Sampath Kumar
- Laboratoire National des Champs Magnétiques Intenses, CNRS-UJF-UPS-INSA, 25, avenue des Martyrs, 38042 Grenoble, France
| | - C Faugeras
- Laboratoire National des Champs Magnétiques Intenses, CNRS-UJF-UPS-INSA, 25, avenue des Martyrs, 38042 Grenoble, France
| | - M Potemski
- Laboratoire National des Champs Magnétiques Intenses, CNRS-UJF-UPS-INSA, 25, avenue des Martyrs, 38042 Grenoble, France
| | - C Michel
- Institute for Theoretical Physics, TP IV, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - E M Hankiewicz
- Institute for Theoretical Physics, TP IV, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - T Brauner
- Institute for Theoretical Physics, Vienna University of Technology, A-1040 Vienna, Austria
| | - Č Drašar
- Faculty of Chemical Technology, University of Pardubice, CZ-53210 Pardubice, Czech Republic
| | - S Schreyeck
- Physikalisches Institut (EP III), Universität Würzburg, D-97074 Würzburg, Germany
| | - S Grauer
- Physikalisches Institut (EP III), Universität Würzburg, D-97074 Würzburg, Germany
| | - K Brunner
- Physikalisches Institut (EP III), Universität Würzburg, D-97074 Würzburg, Germany
| | - C Gould
- Physikalisches Institut (EP III), Universität Würzburg, D-97074 Würzburg, Germany
| | - C Brüne
- Physikalisches Institut (EP III), Universität Würzburg, D-97074 Würzburg, Germany
| | - L W Molenkamp
- Physikalisches Institut (EP III), Universität Würzburg, D-97074 Würzburg, Germany
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11
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Karczewski G, Szot M, Kret S, Kowalczyk L, Chusnutdinow S, Wojtowicz T, Schreyeck S, Brunner K, Schumacher C, Molenkamp LW. Nanoscale morphology of multilayer PbTe/CdTe heterostructures and its effect on photoluminescence properties. Nanotechnology 2015; 26:135601. [PMID: 25751540 DOI: 10.1088/0957-4484/26/13/135601] [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: 06/04/2023]
Abstract
We study nanoscale morphology of PbTe/CdTe multilayer heterostuctures grown by molecular beam epitaxy on hybrid GaAs/CdTe (100) substrates. Nominally, the structures consist of 25 repetitions of subsequently deposited CdTe and PbTe layers with comparable thicknesses of 21 and 8 nm, respectively. However, the morphology of the resulting structures crucially depends on the growth temperature. The two-dimensional layered, superlattice-like character of the structures remains preserved only when grown at low substrate temperatures, such as 230 °C. The samples grown at the slightly elevated temperature of 270 °C undergo a morphological transformation to structures consisting of CdTe and PbTe pillars and columns oriented perpendicular to the substrate. Although the pillar-like objects are of various shapes and dimensions these structures exhibit exceptionally strong photoluminescence in the near infrared spectral region. At the higher growth temperature of 310 °C, PbTe and CdTe separate completely forming thick layers oriented longitudinally to the substrate plane. The observed topological transformations are driven by thermally activated atomic diffusion in the solid state phase. The solid state phase remains fully coherent during the processes. The observed topological transitions leading to the material separation in PbTe/CdTe system could be regarded as an analog of spinodal decomposition of an immiscible solid state solution and thus they can be qualitatively described by the Cahn-Hillard model as proposed by Groiss et al (2014 APL Mater. 2 012105).
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Affiliation(s)
- G Karczewski
- Institute of Physics, Polish Academy of Science, al. Lotników 32/46, 02-668 Warszawa, Poland
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Haldimann M, Alt A, Blanc A, Brunner K, Sager F, Dudler V. Migration of antimony from PET trays into food simulant and food: determination of Arrhenius parameters and comparison of predicted and measured migration data. Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2013; 30:587-98. [PMID: 23286325 PMCID: PMC3613973 DOI: 10.1080/19440049.2012.751631] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 11/13/2012] [Indexed: 11/05/2022]
Abstract
Migration experiments with small sheets cut out from ovenable PET trays were performed in two-sided contact with 3% acetic acid as food simulant at various temperatures. The fraction of diffusible antimony (Sb) was estimated to be 62% in the PET sample under study. Apparent diffusion coefficients of Sb in PET trays were determined experimentally. Measurement of migration between 20 and 150°C yielded a linear Arrhenius plot over a wide temperature range from which the activation energy (E(a)) of 188 ± 36 kJ mol(-1) and the pre-exponential factor (D(0)) of 3.6 × 10(14) cm(2) s(-1) were determined for diffusing Sb species. E (a) was similar to previously reported values for PET bottles obtained with a different experimental approach. E (a) and D (0) were applied as model parameters in migration modelling software for predicting the Sb transfer in real food. Ready meals intended for preparation in a baking oven were heated in the PET trays under study and the actual Sb migration into the food phase was measured by isotope dilution ICP-MS. It was shown that the predictive modelling reproduces correctly experimental data.
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Affiliation(s)
- M Haldimann
- Federal Office of Public Health, Chemical Risks Section, Bern, Switzerland.
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Dengel RG, Frey A, Brunner K, Gould C, Molenkamp LW. Fabrication of magnetic artificial atoms. Nanotechnology 2012; 23:395301. [PMID: 22962261 DOI: 10.1088/0957-4484/23/39/395301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We have fabricated gated vertical quantum dots made from a II-VI semiconductor heterostructure containing a paramagnetic quantum well. The absence of a known Schottky gate metal compatible with ZnSe based material precludes the traditional method of using a self-aligning shadow evaporated gate. Instead, we make use of a multi-step electron beam lithography process to surround a pillar with an insulating dielectric and gate. This process allows for the processing of dots with diameters down to 250 nm. Preliminary transport data confirming the magnetic nature of the resulting artificial atom are presented.
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Affiliation(s)
- R-G Dengel
- Physikalisches Institut (EP3), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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14
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Mushi D, Byamukama D, Kirschner AK, Mach RL, Brunner K, Farnleitner AH. Sanitary inspection of wells using risk-of-contamination scoring indicates a high predictive ability for bacterial faecal pollution in the peri-urban tropical lowlands of Dar es Salaam, Tanzania. J Water Health 2012; 10:236-43. [PMID: 22717748 PMCID: PMC3393635 DOI: 10.2166/wh.2012.117] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Sanitary inspection of wells was performed according to World Health Organization (WHO) procedures using risk-of-contamination (ROC) scoring in the peri-urban tropical lowlands of Dar es Salaam, Tanzania. The ROC was assessed for its capacity to predict bacterial faecal pollution in the investigated well water. The analysis was based on a selection of wells representing environments with low to high presumptive faecal pollution risk and a multi-parametric data set of bacterial indicators, generating a comprehensive picture of the level and characteristics of faecal pollution (such as vegetative Escherichia coli cells, Clostridium perfringens spores and human-associated sorbitol fermenting Bifidobacteria). ROC scoring demonstrated a remarkable ability to predict bacterial faecal pollution levels in the investigated well water (e.g. 87% of E. coli concentration variations were predicted by ROC scoring). Physicochemical characteristics of the wells were not reflected by the ROC scores. Our results indicate that ROC scoring is a useful tool for supporting health-related well water management in urban and suburban areas of tropical, developing countries. The outcome of this study is discussed in the context of previously published results, and future directions are suggested.
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Affiliation(s)
- Douglas Mushi
- Department of Biological Sciences, Sokoine University, P.O. Box 3038, Morogoro, Tanzania
| | - Denis Byamukama
- Department of Biochemistry, Makerere University, P.O. Box 7062, Kampala, Uganda
| | - Alexander K.T. Kirschner
- Institute for Hygiene and Applied Immunology, Medical University of Vienna, Austria
- InterUniversity Cooperation Centre Water and Health, Vienna University of Technology, Gumpendorferstraße 1a, 1060 Vienna, www.waterandhealth
| | - Robert L. Mach
- Institute of Chemical Engineering, Research Area Applied Biochemistry and Gene Technology, Research Group Environmental Microbiology and Molecular Ecology, Vienna University of Technology, Gumpendorferstraße 1a, A-1060 Vienna, Austria
| | - K. Brunner
- Institute of Chemical Engineering, Research Area Applied Biochemistry and Gene Technology, Research Group Environmental Microbiology and Molecular Ecology, Vienna University of Technology, Gumpendorferstraße 1a, A-1060 Vienna, Austria
| | - Andreas H. Farnleitner
- Institute of Chemical Engineering, Research Area Applied Biochemistry and Gene Technology, Research Group Environmental Microbiology and Molecular Ecology, Vienna University of Technology, Gumpendorferstraße 1a, A-1060 Vienna, Austria
- InterUniversity Cooperation Centre Water and Health, Vienna University of Technology, Gumpendorferstraße 1a, 1060 Vienna, www.waterandhealth
- Corresponding Author: Institute of Chemical Engineering, Research Group Environmental Microbiology and Molecular Ecology, Vienna University of Technology, Gumpendorferstraße 1a, A-1060 Vienna, Austria,
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Brunner K. Bis bald in Interlaken. SCHWEIZ ARCH TIERH 2012; 154:231. [DOI: 10.1024/0036-7281/a000337] [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: 11/19/2022]
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Naydenova T, Dürrenfeld P, Tavakoli K, Pégard N, Ebel L, Pappert K, Brunner K, Gould C, Molenkamp LW. Diffusion thermopower of (Ga,Mn)As/GaAs tunnel junctions. Phys Rev Lett 2011; 107:197201. [PMID: 22181638 DOI: 10.1103/physrevlett.107.197201] [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: 07/06/2011] [Indexed: 05/31/2023]
Abstract
We report the observation of tunneling anisotropic magnetothermopower, a voltage response to a temperature difference across an interface between a normal and a magnetic semiconductor. The resulting voltage is related to the energy derivative of the density of states in the magnetic material, and thus has a strongly anisotropic response to the direction of magnetization in the material. The effect will have relevance to the operation of semiconductor spintronic devices, and may indeed already play a role in correctly interpreting the details of some earlier spin injection studies.
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Affiliation(s)
- Ts Naydenova
- Physikalisches Institut EP3, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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Mark S, Dürrenfeld P, Pappert K, Ebel L, Brunner K, Gould C, Molenkamp LW. Fully electrical read-write device out of a ferromagnetic semiconductor. Phys Rev Lett 2011; 106:057204. [PMID: 21405428 DOI: 10.1103/physrevlett.106.057204] [Citation(s) in RCA: 3] [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: 11/05/2010] [Indexed: 05/30/2023]
Abstract
We report the realization of a read-write device out of the ferromagnetic semiconductor (Ga,Mn)As as the first step to a fundamentally new information processing paradigm. Writing the magnetic state is achieved by current-induced switching and readout of the state is done by the means of the tunneling anisotropic magnetoresistance effect. This 1 bit demonstrator device can be used to design an electrically programmable memory and logic device.
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Affiliation(s)
- S Mark
- Physikalisches Institut (EP3) and Röntgen Center for Complex Material Systems, Am Hubland, Universität Würzburg, D-97074 Würzburg, Germany
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Astakhov GV, Schwittek J, Schott GM, Gould C, Ossau W, Brunner K, Molenkamp LW. Photoinduced Barkhausen effect in the ferromagnetic semiconductor (Ga,Mn)As. Phys Rev Lett 2011; 106:037204. [PMID: 21405292 DOI: 10.1103/physrevlett.106.037204] [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: 06/16/2010] [Indexed: 05/30/2023]
Abstract
Magnetization of ferromagnetic materials commonly occurs via random jumps of domain walls between pinning sites, a phenomenon known as the Barkhausen effect. Using strongly focused light pulses of appropriate power and duration we demonstrate the ability to selectively activate single jumps in the domain wall propagation in (Ga,Mn)As, manifesting itself as a discrete photoinduced domain wall creep as a function of illumination time. The propagation velocity can be increased over 7 orders of magnitude varying the illumination power density and the magnetic field.
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Affiliation(s)
- G V Astakhov
- Physikalisches Institut, EP3, Universität Würzburg, 97074 Würzburg, Germany.
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Mark S, Gould C, Pappert K, Wenisch J, Brunner K, Schmidt G, Molenkamp LW. Independent magnetization behavior of a ferromagnetic metal-semiconductor hybrid system. Phys Rev Lett 2009; 103:017204. [PMID: 19659175 DOI: 10.1103/physrevlett.103.017204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2009] [Indexed: 05/28/2023]
Abstract
We report the discovery of an effect where two ferromagnetic materials, one semiconductor [(Ga,Mn)As] and one metal (Permalloy), can be directly deposited on each other and still switch their magnetization independently. We use this independent magnetization behavior to create various resistance states dependent on the magnetization direction of the individual layers. At zero magnetic field a two layer device can reach up to four nonvolatile resistance states.
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Affiliation(s)
- S Mark
- Physikalisches Institut (EP3), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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20
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Astakhov GV, Hoffmann H, Korenev VL, Kiessling T, Schwittek J, Schott GM, Gould C, Ossau W, Brunner K, Molenkamp LW. Nonthermal photocoercivity effect in a low-doped (Ga,Mn)As ferromagnetic semiconductor. Phys Rev Lett 2009; 102:187401. [PMID: 19518911 DOI: 10.1103/physrevlett.102.187401] [Citation(s) in RCA: 2] [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: 08/22/2008] [Indexed: 05/27/2023]
Abstract
We report a photoinduced change of the coercive field, i.e., a photocoercivity effect (PCE), under very low intensity illumination of a low-doped (Ga,Mn)As ferromagnetic semiconductor. We find a strong correlation between the PCE and the sample resistivity. Spatially resolved dynamics of the magnetization reversal rule out any role of thermal heating in the origin of this PCE, and we propose a mechanism based on the light-induced lowering of the domain wall pinning energy. The PCE is local and reversible, allowing writing and erasing of magnetic images using light.
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Affiliation(s)
- G V Astakhov
- Physikalisches Institut (EP3), Universität Würzburg, 97074 Würzburg, Germany.
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Brunner K, Haemmerli U. Die blinde Leberbiopsie als Mittel der Frühdiagnose bei Miliartuberkulose. Respiration 2009. [DOI: 10.1159/000192328] [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: 11/19/2022] Open
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Abstract
INTRODUCTION Exostoses of the external auditory meatus are benign masses of tympanal bone that can lead to infections of the external auditory meatus in advanced cases and then need surgical treatment. Regular irritation of the auditory meatus by exposure to cold water was implicated in the causation of exostoses long ago. The present study investigates the cold water hypothesis in a patient group of continental origin. The surgical procedures and results are discussed. STUDY DESIGN Retrospective study. MATERIALS AND METHODS We present the epidemiological and aetiological data and postoperative findings recorded for 144 patients (167 procedures) who underwent surgical removal of exostoses from the external auditory meatus in the hospital in Würzburg within 11 years. In attempt to glean further information about the aetiology, patients were also asked to complete a questionnaire on participation in water sports and their symptoms before and since the operation. RESULTS Most of the patients (94%) had taken part in water sports for some years, more than 80% of them several times weekly. The most common indication for surgical removal was recurrent infection of the external ear. Although 50% of the patients reported improved hearing, no higher sound threshold was observed. Reversible complications (ear drum performation, tinnitus, opening of mastoid cells) were observed in 18% of the patients. One patient had a stenosis of the auditory canal caused by scar tissue. CONCLUSIONS Surgical removal of exostoses in the external auditory canal is frequently fraught with controllable complications. The indications for their surgical removal should be strictly applied; the presence of exostoses in isolation is not an acceptable indication for surgery. Removal of exostoses is an adequate way of avoiding recurrent external ear infections. Improved hearing can be expected only if the self-cleaning function of the external auditory meatus is improved.
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Affiliation(s)
- R Mlynski
- Klinik Poliklinik für Hals-, Nasen- und Ohrenkrankheiten, plastische und ästhetische Operationen, Klinikum der Bayerischen Julius-Maximilians-Universität, Josef-Schneider-Strasse 11, 97080 Würzburg.
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Joss R, Gänger K, Gerber A, Kiser J, Rosenthal C, Brunner K. Verhütung und Behandlung von Nebenwirkungen der zytostatischen Therapie urogenitaler Tumoren. Aktuelle Urol 2008. [DOI: 10.1055/s-2008-1062640] [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: 10/21/2022]
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25
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Wenisch J, Gould C, Ebel L, Storz J, Pappert K, Schmidt MJ, Kumpf C, Schmidt G, Brunner K, Molenkamp LW. Control of magnetic anisotropy in (Ga,Mn)as by lithography-induced strain relaxation. Phys Rev Lett 2007; 99:077201. [PMID: 17930919 DOI: 10.1103/physrevlett.99.077201] [Citation(s) in RCA: 4] [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: 12/22/2006] [Indexed: 05/25/2023]
Abstract
We report control of magnetic anisotropy in epitaxial (Ga,Mn)As by anisotropic strain relaxation in patterned structures. The strain in the structures is characterized using reciprocal space mapping by x-ray techniques. The magnetic anisotropy before patterning of the layer, which shows biaxial easy axes along [100] and [010], is replaced by a hard axis in the direction of large elastic strain relaxation and a uniaxial easy axis in the direction where pseudomorphic conditions are retained.
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Affiliation(s)
- J Wenisch
- Physikalisches Institut (EP3), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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Karczewski G, Mahapatra S, Borzenko T, Dłużewski P, Kret S, Kłopotowski L, Schumacher C, Brunner K, Molenkamp LW, Wojtowicz T. ZnSe/CdSe Superlattice Nanowires by Catalyst-assisted Molecular Beam Epitaxy. ACTA ACUST UNITED AC 2007. [DOI: 10.1063/1.2729772] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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27
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Pappert K, Schmidt MJ, Hümpfner S, Rüster C, Schott GM, Brunner K, Gould C, Schmidt G, Molenkamp LW. Magnetization-switched metal-insulator transition in a (Ga,Mn)as tunnel device. Phys Rev Lett 2006; 97:186402. [PMID: 17155562 DOI: 10.1103/physrevlett.97.186402] [Citation(s) in RCA: 3] [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: 07/14/2006] [Indexed: 05/12/2023]
Abstract
We observe the occurrence of an Efros-Shklovskii gap in (Ga,Mn)As based tunnel junctions. The occurrence of the gap is controlled by the extent of the hole wave function on the Mn acceptor atoms. Using k.p-type calculations we show that this extent depends crucially on the direction of the magnetization in the (Ga,Mn)As (which has two almost equivalent easy axes). This implies one can reversibly tune the system into the insulating or metallic state by changing the magnetization.
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Affiliation(s)
- K Pappert
- Physikalisches Institut (EP3), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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Ab E, Atkinson AR, Banci L, Bertini I, Ciofi-Baffoni S, Brunner K, Diercks T, Dötsch V, Engelke F, Folkers GE, Griesinger C, Gronwald W, Günther U, Habeck M, de Jong RN, Kalbitzer HR, Kieffer B, Leeflang BR, Loss S, Luchinat C, Marquardsen T, Moskau D, Neidig KP, Nilges M, Piccioli M, Pierattelli R, Rieping W, Schippmann T, Schwalbe H, Travé G, Trenner J, Wöhnert J, Zweckstetter M, Kaptein R. NMR in the SPINE Structural Proteomics project. Acta Crystallogr D Biol Crystallogr 2006; 62:1150-61. [PMID: 17001092 DOI: 10.1107/s0907444906032070] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2005] [Accepted: 08/14/2006] [Indexed: 11/10/2022]
Abstract
This paper describes the developments, role and contributions of the NMR spectroscopy groups in the Structural Proteomics In Europe (SPINE) consortium. Focusing on the development of high-throughput (HTP) pipelines for NMR structure determinations of proteins, all aspects from sample preparation, data acquisition, data processing, data analysis to structure determination have been improved with respect to sensitivity, automation, speed, robustness and validation. Specific highlights are protonless (13)C-direct detection methods and inferential structure determinations (ISD). In addition to technological improvements, these methods have been applied to deliver over 60 NMR structures of proteins, among which are five that failed to crystallize. The inclusion of NMR spectroscopy in structural proteomics pipelines improves the success rate for protein structure determinations.
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Affiliation(s)
- E Ab
- Bijvoet Center for Biomolecular Research, NMR Spectroscopy, Utrecht University, Padualaan 8, CH Utrecht, The Netherlands
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Astakhov GV, Kiessling T, Platonov AV, Slobodskyy T, Mahapatra S, Ossau W, Schmidt G, Brunner K, Molenkamp LW. Circular-to-linear and linear-to-circular conversion of optical polarization by semiconductor quantum dots. Phys Rev Lett 2006; 96:027402. [PMID: 16486639 DOI: 10.1103/physrevlett.96.027402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2005] [Indexed: 05/06/2023]
Abstract
We report circular-to-linear and linear-to-circular conversion of optical polarization by semiconductor quantum dots. The polarization conversion occurs under continuous wave excitation in the absence of any magnetic field. The effect originates from quantum interference of linearly and circularly polarized photon states, induced by the natural anisotropic shape of the self-assembled dots. The behavior can be qualitatively explained in terms of a pseudospin formalism.
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Affiliation(s)
- G V Astakhov
- Physikalisches Institut der Universität Würzburg, 97074 Würzburg, Germany
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Rothe C, Brunner K, Bach I, Heun S, Monkman AP. Effects of triplet exciton confinement induced by reduced conjugation length in polyspirobifluorene copolymers. J Chem Phys 2005; 122:84706. [PMID: 15836076 DOI: 10.1063/1.1851505] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Using gated optical spectroscopy at low temperatures, a polyspirobifluorene has been compared with an alternating carbazole-spirobifluorene copolymer in which the backbone conjugation is interrupted due to meta coupling of the carbazole moieties. In the copolymer both singlet and triplet energy levels are blueshifted by 130 meV with respect to the homopolymer, resulting in an unaltered singlet-to-triplet splitting. Though the barrier for triplet exciton migration increases from 4.4 to 6.0 meV for the copolymer compared to the homopolymer, it still remained low enough to ensure efficient triplet diffusion at ambient temperature.
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Affiliation(s)
- C Rothe
- Department of Physics, University of Durham, Durham DH1 3LE, United Kingdom.
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Rüster C, Gould C, Jungwirth T, Sinova J, Schott GM, Giraud R, Brunner K, Schmidt G, Molenkamp LW. Very large tunneling anisotropic magnetoresistance of a (Ga,Mn)As/GaAs/(Ga,Mn)As stack. Phys Rev Lett 2005; 94:027203. [PMID: 15698223 DOI: 10.1103/physrevlett.94.027203] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2004] [Indexed: 05/24/2023]
Abstract
We report the discovery of a very large tunneling anisotropic magnetoresistance in an epitaxially grown (Ga,Mn)As/GaAs/(Ga,Mn)As structure. The key novel spintronics features of this effect are as follows: (i) both normal and inverted spin-valve-like signals; (ii) a large nonhysteretic magnetoresistance for magnetic fields perpendicular to the interfaces; (iii) magnetization orientations for extremal resistance are, in general, not aligned with the magnetic easy and hard axis; (iv) enormous amplification of the effect at low bias and temperatures.
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Affiliation(s)
- C Rüster
- Physikalisches Institut (EP3), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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Gould C, Rüster C, Jungwirth T, Girgis E, Schott GM, Giraud R, Brunner K, Schmidt G, Molenkamp LW. Tunneling anisotropic magnetoresistance: a spin-valve-like tunnel magnetoresistance using a single magnetic layer. Phys Rev Lett 2004; 93:117203. [PMID: 15447375 DOI: 10.1103/physrevlett.93.117203] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2004] [Indexed: 05/24/2023]
Abstract
We introduce a new class of spintronic devices in which a spin-valve-like effect results from strong spin-orbit coupling in a single ferromagnetic layer rather than from injection and detection of a spin-polarized current by two coupled ferromagnets. The effect is observed in a normal-metal-insulator-ferromagnetic-semiconductor tunneling device. This behavior is caused by the interplay of the anisotropic density of states in (Ga,Mn)As with respect to the magnetization direction and the two-step magnetization reversal process in this material.
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Affiliation(s)
- C Gould
- Physikalisches Institut (EP3), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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Mlynski R, Brunner K, Brors D, Aletsee C, Dazert S, Helms J. Ätiologie, Diagnostik und Therapie von Exostosen des äußeren Gehörganges. Laryngorhinootologie 2004. [DOI: 10.1055/s-2004-823423] [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: 10/19/2022]
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Welter S, Brunner K, Hofstraat JW, De Cola L. Electroluminescent device with reversible switching between red and green emission. Nature 2003; 421:54-7. [PMID: 12511951 DOI: 10.1038/nature01309] [Citation(s) in RCA: 194] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2002] [Accepted: 11/12/2002] [Indexed: 11/09/2022]
Abstract
Research on new materials for organic electroluminescence has recently focused strongly on phosphorescent emitters, with the aim of increasing the emission efficiency and stability. Here we report the fabrication of a simple electroluminescent device, based on a semiconducting polymer combined with a phosphorescent complex, that shows fully reversible voltage-dependent switching between green and red light emission. The active material is made of a polyphenylenevinylene (PPV) derivative molecularly doped with a homogeneously dispersed dinuclear ruthenium complex, which fulfils the dual roles of triplet emitter and electron transfer mediator. At forward bias (+4 V), the excited state of the ruthenium compound is populated, and the characteristic red emission of the complex is observed. On reversing the bias (-4 V), the lowest excited singlet state of the polymer host is populated, with subsequent emission of green light. The mechanism for the formation of the excited state of the PPV derivative involves the ruthenium dinuclear complex in a stepwise electron transfer process that finally leads to efficient charge recombination reaction on the polymer.
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Affiliation(s)
- S Welter
- Molecular Photonics Group, University of Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands
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Peterbauer CK, Brunner K, Mach RL, Kubicek CP. Identification of the N-acetyl-D-glucosamine-inducible element in the promoter of the Trichoderma atroviride nag1 gene encoding N-acetyl-glucosaminidase. Mol Genet Genomics 2002; 267:162-70. [PMID: 11976959 DOI: 10.1007/s00438-001-0620-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2001] [Accepted: 11/12/2001] [Indexed: 10/27/2022]
Abstract
We have investigated the regulation by N-acetyl-glucosamine of the nag1 gene of the mycoparasitic biocontrol fungus Trichoderma atroviride (= T. harzianum P1), which encodes a 73-kDa N-acetyl-beta-D-glucosaminidase. The use of translational fusions revealed that a 290-bp fragment of the 5' regulatory region of nag1 is sufficient to confer inducibility on the Aspergillus niger goxA gene. The region between positions -150 and -290, upstream of the nag1 coding region, was investigated using in vivo methylation protection analysis and electrophoretic mobility shift assays (EMSAs). Two neighbouring regions that interacted with regulatory proteins were identified, and bases essential for these interactions were determined in vitro. These data reveal protein binding to a CCCCT element at -240, a CCAGN(13)CTGG motif at -284, and a CCAAT-box which is present in the spacer of the latter motif. Evidence for the binding of a Hap2/3/5 complex to this CCAAT motif is presented. Protein binding to all three motifs was constitutive, and no differences were observed between induced and non-induced cultures. Mutation of either the CCAGN(13)CTGG or the AGGGG motif resulted in loss of inducibility of nag1 expression by N-acetyl-D-glucosamine in vivo.
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Affiliation(s)
- C K Peterbauer
- Sektion für Mikrobielle Biochemie, Institut für Biochemische Technologie und Mikrobiologie, Technische Universität Wien, Getreidemarkt 9-172.5, A-1060 Vienna, Austria
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Abstract
INTRODUCTION Isolated iliac artery aneurysms (IAA) are rare. The rupture risk, however, is high and the diagnosis can be difficult. The aim of this study was to report the frequency, morphology and outcome of these lesions. METHODS Retrospective analysis of the medical data of all patients treated for IAA from 1990 to 1999. RESULTS Fifty-nine consecutive patients, 55 (93%) male and 4 (7%) female, were included in the study. The median age was 68 (48-86) years. During the same time period, 741 consecutive patients with aortoiliac aneurysms were treated; thus the frequency of IAA was 8%. The median diameter of the IAA was 7 (3-12) cm. Most patients had at least one risk factor. IAA were unilateral in 40 (68%) or bilateral in 19 (32%) patients and affected the common iliac artery in 25 (19%), the internal iliac artery in 11 (19%) and simultaneously the common and internal iliac artery in 21 (36%) patients. Additional involvement of the external iliac artery was noted in 2 (3%) patients. Thirty-six (61%) patients with IAA underwent elective treatment while 23 (39%) patients had to be treated on an emergency basis. Endovascular stent grafts were inserted in 2 patients. Overall mortality was 10% (n = 6), 2.8% (n = 1) in asymptomatic and 22% (n = 5) in symptomatic or ruptured IAA. Overall morbidity in this study was 30%. The median follow-up of the patients was 36 (2-120) months. DISCUSSION Surgical therapy in patients with asymptomatic IAA can be performed with a reasonable mortality. However, mortality and morbidity in patients with symptomatic or ruptured IAA remains high. Postoperative long-term results are excellent. The value of endovascular therapy for IAA has yet to be determined.
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Affiliation(s)
- P U Reber
- Abteilung für Gefässchirurgie, Klinik für Herz- und Gefässchirurgie, Inselspital, Universität Bern, Schweiz.
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Kaindl RA, Wurm M, Reimann K, Woerner M, Elsaesser T, Miesner C, Brunner K, Abstreiter G. Ultrafast dynamics of intersubband excitations in a quasi-two-dimensional hole gas. Phys Rev Lett 2001; 86:1122-1125. [PMID: 11178025 DOI: 10.1103/physrevlett.86.1122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2000] [Indexed: 05/23/2023]
Abstract
We present the first study of ultrafast hole dynamics after resonant intersubband excitation in a quasi-two-dimensional semiconductor. p-type Si0.5Ge 0.5/Si multiple quantum wells are studied in pump-probe experiments with 150 fs midinfrared pulses. Intersubband scattering from the second heavy-hole back to the first heavy-hole subband occurs with a time constant of 250 fs, followed by intrasubband carrier heating within 1 ps. Such processes give rise to a strong reshaping of the intersubband absorption line, which is accounted for by calculations of the subband structure, optical spectra, and hole-phonon scattering rates.
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Affiliation(s)
- R A Kaindl
- Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-Strasse 2A, D-12489 Berlin, Germany
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Brunner K, Tortschanoff A, Warmuth C, Bässler H, Kauffmann HF. Site Torsional Motion and Dispersive Excitation Hopping Transfer in π-Conjugated Polymers. J Phys Chem B 2000. [DOI: 10.1021/jp993068d] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- K. Brunner
- Institut für Physikalische Chemie der Universität Wien, Währingerstrasse 42, A-1090 Wien, Austria, and Institut für Physikalische Chemie, Kernchemie und Makromolekulare Chemie, Philipps-Universität, D-35032 Marburg, Germany
| | - A. Tortschanoff
- Institut für Physikalische Chemie der Universität Wien, Währingerstrasse 42, A-1090 Wien, Austria, and Institut für Physikalische Chemie, Kernchemie und Makromolekulare Chemie, Philipps-Universität, D-35032 Marburg, Germany
| | - Ch. Warmuth
- Institut für Physikalische Chemie der Universität Wien, Währingerstrasse 42, A-1090 Wien, Austria, and Institut für Physikalische Chemie, Kernchemie und Makromolekulare Chemie, Philipps-Universität, D-35032 Marburg, Germany
| | - H. Bässler
- Institut für Physikalische Chemie der Universität Wien, Währingerstrasse 42, A-1090 Wien, Austria, and Institut für Physikalische Chemie, Kernchemie und Makromolekulare Chemie, Philipps-Universität, D-35032 Marburg, Germany
| | - H. F. Kauffmann
- Institut für Physikalische Chemie der Universität Wien, Währingerstrasse 42, A-1090 Wien, Austria, and Institut für Physikalische Chemie, Kernchemie und Makromolekulare Chemie, Philipps-Universität, D-35032 Marburg, Germany
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Tortschanoff A, Brunner K, Warmuth C, Kauffmann HF. Interference of Optical Coherent Transients in Pentacene/p-Terphenyl: Femtosecond Beats Probed by Correlated Fluorescence Fluctuations. J Phys Chem A 1999. [DOI: 10.1021/jp984505b] [Citation(s) in RCA: 9] [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: 11/30/2022]
Affiliation(s)
- A. Tortschanoff
- Institut für Physikalische Chemie der Universität Wien, Währingerstrasse 42, A-1090 Wien, Austria
| | - K. Brunner
- Institut für Physikalische Chemie der Universität Wien, Währingerstrasse 42, A-1090 Wien, Austria
| | - Ch. Warmuth
- Institut für Physikalische Chemie der Universität Wien, Währingerstrasse 42, A-1090 Wien, Austria
| | - H. F. Kauffmann
- Institut für Physikalische Chemie der Universität Wien, Währingerstrasse 42, A-1090 Wien, Austria
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Tortschanoff A, Brunner K, Warmuth C, Kauffmann HF. Coherence from fluorescence correlations: Oscillatory femtosecond fluorescence in pentacene/p-terphenyl. J Chem Phys 1999. [DOI: 10.1063/1.478332] [Citation(s) in RCA: 18] [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] [Indexed: 11/14/2022] Open
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Brunner K, Tortschanoff A, Hemmens B, Andrew PJ, Mayer B, Kungl AJ. Sensitivity of flavin fluorescence dynamics in neuronal nitric oxide synthase to cofactor-induced conformational changes and dimerization. Biochemistry 1998; 37:17545-53. [PMID: 9860870 DOI: 10.1021/bi981138l] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The fluorescence intensity of the two flavin prosthetic groups, FMN and FAD, in neuronal nitric oxide synthase (nNOS) was found to decay highly nonexponentially, being best described by four fluorescence lifetimes. This excited state heterogeneity is the result of multiple flavin quenching sites which are due to several flavin microenvironments created mainly by stacking with aromatic amino acids. Investigating nNOS in the absence of one or more of Ca2+/calmodulin, tetrahydrobiopterin, and heme revealed an influence of these cofactors on the microenvironments of the flavin prosthetic groups. Similar effects on the flavin rotational dynamics were found by analyzing the fluorescence anisotropy decay of the holo and of the different apo forms of nNOS. Since the tetrahydrobiopterin and the heme are located in the N-terminal oxygenase domain of nNOS, their effect on the flavins in the C-terminal reductase domain is explained by a folding back of the reductase domain onto the oxygenase domain. Thereby a domain-domain interface is created containing the FAD, FMN, heme, and tetrahydrobiopterin prosthetic groups which allows for efficient electron transfer during catalysis. The heme group, which is known to be essential for homodimerization of nNOS, was also found to be essential for the formation of the domain-domain interface.
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Affiliation(s)
- K Brunner
- Institut für Physikalische Chemie, Universität Wien, Austria
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Abstract
PURPOSE The present study was carried out to investigate possible electroencephalographic changes induced by choking in judo (shime-waza) by means of spectral analysis and brain mapping. METHODS Power spectral changes in Electroencephalography (EEG) were recorded in six experienced judoka who underwent a choking trial with a "shime-waza choking" technique called juji-jime. RESULTS A significant increase of global field power in the delta- and theta-range occurred, while physiological alpha-power decreased. These changes in the low-frequency range reached a statistically significant level within a time span up to 20 s after choking, which was performed at an average choking time of 8 s. In no case did choking provoke neuropsychological symptoms. Yet, spectral EEG-analysis revealed subclinical changes of brain function. CONCLUSIONS Choking in judo may induce subclinical electroencephalographic perturbations. The extent and duration can be objectified by means of spectral analysis of EEG data, global field power computation, and brain-mapping representation.
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Affiliation(s)
- R Rau
- Department of Sports Medicine, Institute of Sports Sciences of the Johann Wolfgang Goethe University, Frankfurt/Main, Germany
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Coleman M, Rafla S, Propert KJ, Glicksman A, Peterson B, Nissen N, Brunner K, Holland JF, Anderson JR, Gottlieb A, Kaufman T. Augmented therapy of extensive Hodgkin's disease: radiation to known disease or prolongation of induction chemotherapy did not improve survival--results of a Cancer and Leukemia Group B study. Int J Radiat Oncol Biol Phys 1998; 41:639-45. [PMID: 9635714 DOI: 10.1016/s0360-3016(98)00071-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE This prospective randomized trial in extensive untreated Hodgkin's disease was undertaken to assess the potential benefit of augmented therapy (12 months chemotherapy or radiation to known disease) compared to standard 6 months chemotherapy. PATIENT AND METHODS A total of 258 patients, mostly Stage IV, were randomized to four treatment regimens consisting of six cycles of CCNU, vinblastine, procarbazine, and prednisone (CVPP); 12 cycles of CVPP; six cycles of CVPP followed by 25 Gy radiotherapy; or three cycles CVPP, 25 Gy radiotherapy, and three cycles CVPP. RESULTS Complete remissions were achieved in 65% of all patients. A 58% overall 5-year survival rate was obtained. Relapses in irradiated areas of known disease occurred in only 6% of responding patients. There was, however, no statistical difference in response frequency, disease-free survival, or overall survival among the four regimens. Elderly patients responded less frequently. CONCLUSION While radiotherapy provided control of local (known) disease, no impact on overall survival was apparent. Likewise, doubling the duration of chemotherapy did not improve response or survival. Augmentation of therapy with either radiotherapy or more chemotherapy in this study was of no benefit compared to the standard 6 months of treatment.
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Affiliation(s)
- M Coleman
- New York Hospital-Cornell Medical Center, NY 10021, USA
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Abstract
A correlation-based learning (CBL) neural network model is proposed, which simulates the emergence of grating cells as well as some of their response characteristics to periodic pattern stimuli. These cells, found in areas V1 and V2 of the visual cortex of monkeys, respond vigorously and exclusively to bar gratings of a preferred orientation and periodicity. Their non-linear behaviour differentiates grating cells from other orientation-selective cells, which show linear spatial frequency filtering.
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Affiliation(s)
- K Brunner
- Institute of Biophysics, University of Regensburg, Germany
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Affiliation(s)
- B Planz
- Department of Urology, Teaching Hospital of Fulda, Germany
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Bockelmann U, Roussignol P, Filoramo A, Heller W, Abstreiter G, Brunner K, Böhm G, Weimann G. Time resolved spectroscopy of single quantum dots: Fermi gas of excitons? Phys Rev Lett 1996; 76:3622-3625. [PMID: 10061014 DOI: 10.1103/physrevlett.76.3622] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Brunner K, Eberl K, Winter W. Near-band-edge photoluminescence from pseudomorphic Si1-yCy/Si quantum well structures. Phys Rev Lett 1996; 76:303-306. [PMID: 10061067 DOI: 10.1103/physrevlett.76.303] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Brunner K, Abstreiter G, Böhm G, Tränkle G, Weimann G. Sharp-line photoluminescence and two-photon absorption of zero-dimensional biexcitons in a GaAs/AlGaAs structure. Phys Rev Lett 1994; 73:1138-1141. [PMID: 10057634 DOI: 10.1103/physrevlett.73.1138] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Oberle E, Brunner K, Rhyner K. [Gastrointestinal hemorrhage: how much evaluation is necessary?]. Schweiz Rundsch Med Prax 1993; 82:1244-52. [PMID: 8272694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
For this study data from a total of 362 patients covering a time period of 10 years (1979-1989) were analyzed. Referal to the medical outpatient clinic of Zurich occurred in over 90% of the cases for evaluation of incidental iron deficiency anemia or suspected of gastrointestinal bleeding because of melanea/hematemesis. The evaluation comprised endoscopy, in part radiography of the upper intestinal tract and rarely angiography and scintigraphic tracer studies. 95 patients (26%) had benign lesions in the gastro-intestinal tract, 88 patients (26%) had endoscopy without abnormal findings. Iron deficiency was thought to be due to hypermenorrhea in 45 patients (13%) and to other non-gastrointestinal causes in 43 patients (13%) by exclusion. A malignancy of the gastrointestinal tract was found in 25 patients (7%): 18 carcinomas of the colon, 6 carcinomas of the stomach and 1 metastasis of a melanoma to the coecum. In 80% of the patients with malignancies occult fecal blood was detected. In 154 patients (42%) extensive diagnostic investigation including sometimes even repeated endoscopy could not disclose the cause of blood loss. 88 (24%) of these patients had slight iron deficiencies (hemoglobin > 10 g/dl, hemoccult-test positive in 65% of cases), 66 (18%) had severe iron-deficiencies (hemoglobin < 10 g/dl, hemoccult-test positive in 90% of cases). Selective small bowel radiography was performed in 36 patients without any positive findings. Patients with gastro-intestinal bleeding of undetermined etiology present a diagnostic challenge for the general practitioner.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- E Oberle
- Medizinische Abteilung, Kantonsspital Glarus
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