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206 results on '"Fuhrmann, K."'

4. New visual companions of solar-type stars within 25 pc

Author

Chini, R., Fuhrmann, K., Domínguez, A. Barr, Nuñez, F. Pozo, Westhues, C., and Hodapp, K.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

We report the discovery of faint common-proper-motion companions to the nearby southern solar-type stars HD43162, HD67199, HD114837, HD114853, HD129502, HD165185, HD197214, and HD212330 from near-infrared imaging and astrometry. We also confirm the previously identified tertiary components around HD165401 and HD188088. Since the majority of these stars were already known as binaries, they ascend now to higher-level systems. A particularly interesting case is the G6.5V BYDra-type variable HD43162, which harbors two common-proper-motion companions at distances of 410 AU and 2740 AU. Our limited study shows that the inventory of common-proper-motion companions around nearby bright stars is still not completely known., Comment: 8 pages, 7 figures, accepted by MNRAS

Published
2013
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5. The Multiplicity of High-Mass Stars

Author

Chini, R., Barr, A., Buda, L. S., Dembsky, T., Drass, H., Nasseri, A., Hoffmeister, V. H., and Fuhrmann, K.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

We report about an ongoing photometric and spectroscopic monitoring survey of about 250 O- and 540 B-type stars in the southern Milky Way with the aim to determine the fraction of close binary systems as a function of mass and to determine the physical parameters of the individual components in the multiple systems. Preliminary results suggest that the multiplicity rate drops from 80% for the highest masses to 20% for stars of 3 solar masses. Our analysis indicates that the binary systems often contain close pairs with components of similar mass. This coincidence cannot originate from a random tidal capture in a dense cluster but is likely due to a particular formation process for high-mass stars. The large percentage of multiple systems requires a new photometric calibration for the absolute magnitudes of O-type stars., Comment: 16 pages, 6 figures, Cent. Eur. Astrophys. Bull. 37 (2013), in press. arXiv admin note: substantial text overlap with arXiv:1205.5238

Published
2013

7. Direct Detection of the Companion of Chi 1 Orionis

Author

Koenig, B., Fuhrmann, K., Neuhaeuser, R., Charbonneau, D., and Jayawardhana, R.

Subjects
Astrophysics
Abstract

We present an H-band image of the companion of Chi 1 Orionis taken with the Keck adaptive optic system and NIRC2 camera equipped with a 300mas-diameter coronographic mask. The direct detection of this companion star enables us to calculate dynamical masses using only Kepler's laws M_A = 1.01 +/- 0.13 M_Sun, M_B = 0.15 +/- 0.02 M_Sun, and to study stellar evolutionary models at a wide spread of masses. The application of Baraffe et al. (1998) pre-main-sequence models implies an age of 70-130 Myrs. This is in conflict to the age of the primary, a confirmed member of the Ursa Major Cluster with a canonical age of 300 Myrs. As a consequence, either the models at low masses underestimate the age or the Ursa Major Cluster is considerably younger than assumed., Comment: 4 pages, accepted by A & A Letters 2002 September 19

Published
2002
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11. Pharmaceuticals and Care Products in the Environment

Author

Christian G. Daughton, Tammy L. Jones-Lepp, Christian G. Daughton, Thomas Ternes, Alfredo C. Alder, Christa S. McArdell, Eva M. Golet, Slavica Ibric, Eva Molnar, Norriel S. Nipales, Walter Giger, Th. Heberer, B. Fuhrmann, K. Schmidt-Baumler, D. Tsipi, V. Koutsouba, A. Hiskia, Traugott Scheytt, Susanne Grams, Elzbieta, Christian G. Daughton, Tammy L. Jones-Lepp

Published
2001

12. Extracellular vesicles protect glucuronidase model enzymes during freeze-drying (vol 8, 12377, 2018)

Author

Frank, J. (Julia), Richter, M. (Maximilian), de Rossi, C. (Chiara), Lehr, C. (Claus-michael) M. (M), Fuhrmann, K. (Kathrin), and Fuhrmann, G. (Gregor)

Subjects
Aucun
Abstract

Extracellular vesicles (EVs) are natural nanoparticles that play important roles in intercellular communication and are increasingly studied for biosignalling, pathogenesis and therapy. Nevertheless, little is known about optimal conditions for their transfer and storage, and the potential impact on preserving EV-loaded cargoes. We present the first comprehensive stability assessment of different widely available types of EVs during various storage conditions including -80 degrees C, 4 degrees C, room temperature, and freeze-drying (lyophilisation). Lyophilisation of EVs would allow easy handling at room temperature and thus significantly enhance their expanded investigation. A model enzyme, beta-glucuronidase, was loaded into different types of EVs derived from mesenchymal stem cells, endothelial cells and cancer cells. Using asymmetric flow field-flow fractionation we proved that the model enzyme is indeed stably encapsulated into EVs. When assessing enzyme activity as indicator for EV stability, and in comparison to liposomes, we show that EVs are intrinsically stable during lyophilisation, an effect further enhanced by cryoprotectants. Our findings provide new insight for exploring lyophilisation as a novel storage modality and we create an important basis for standardised and advanced EV applications in biomedical research.

Published
2019

19. Magnetic susceptibility and order parameter of nematic liquid crystals as determined by a high-temperature SQUID magnetometer.

Author

Dries, Th., Fuhrmann, K., Fischer, E. W., and Ballauff, M.

Subjects
*MAGNETOMETERS, *MAGNETIC susceptibility, *LIQUID crystals
Abstract

Presents a study which described the design and operation of a high-temperature measuring cell for SQUID magnetometers to determine the magnetic susceptibility and order parameter of nematic liquid crystals. Suitability of the device for precision measurements of magnetic susceptibility; Influence of molecular biaxiality on the determination of the order parameter; Elements of SQUID magnetometry.

Published
1991
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20. Effective cross section of the Nd:YAG 1.0641-μm laser transition.

Author

Fuhrmann, K., Hodgson, N., Hollinger, F., and Weber, H.

Subjects
*NUCLEAR cross sections, *NEODYMIUM, *LASER transitions
Abstract

Examines the experimental values of the cross section of the Nd:YAG laser transition in pulsed and continuous wave operation. Evaluation of the extraction efficiency taking into account the mode structure; Discussion of the rate equations used; Method for the determination of the value of the output power, the small-signal gain and the losses.

Published
1987
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37. ARCHEOLOGY OF AN ANCIENT STAR

Author

Fuhrmann, K., primary, Chini, R., additional, Haas, M., additional, Hackstein, M., additional, Ramolla, M., additional, and Bernkopf, J., additional

Published
2012
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50. Near infrared night sky background.

Author

Fuhrmann, K, Harwit, M, and Werner, M

Subjects
Space Sciences
Abstract

Night sky background observation by near IR radiation flux, using rocket-borne telescope and ground based equipment

Published
1969

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