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- Andersson, Ulf R., 1973-, et al.
(author)
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In search of centre of excellence : Network embeddedness and subsidiaryroles in multinational corporations
- 2000
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In: MIR: Management International Review. - 0938-8249 .- 1861-8901. ; 40:4, s. 329-350
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Journal article (peer-reviewed)abstract
- In this paper the authors explore the role of a subsidiary as a centre of excellencewithin the multinational corporation (MNC). It is argued that such a role can bebased on the characteristics of a subsidiary's internal resources, its relationshipswith the rest of the MNC and the business context of which the subsidiary is apart. Based on the perspective of an MNC as a Network the latter aspect is es-pecially focused. Through an analysis of 98 subsidiaries the importance of thesubsidiary's embeddedness, in terms of business relationships with specific cus-tomers and suppliers for its role as a centre of excellence, is investigated.A conceptual result from this paper is that it offers a framework for analysingthe role of the business context for the subsidiary's role as a centre of excel-lence. Productive relationships with external counterparts in the business envi-ronment can be used by the subsidiary to enhance its role as a centre of excel-lence. An empirical result is that the external embeddedness of the subsidiaryis an important and significant explanatory variable of the subsidiary's possibil-ities to be considered important to the MNC as well as a prerequisite to influ-ence the future behaviour of MNC.
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- Björnsson, Jon Mar, et al.
(author)
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Reduced proliferative capacity of hematopoietic stem cells deficient in hoxb3 and hoxb4
- 2003
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In: Blood. - 0006-4971 .- 1528-0020. ; 23:11, s. 3872-3883
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Journal article (peer-reviewed)abstract
- Several homeobox transcription factors, such as HOXB3 and HOXB4, have been implicated in regulation of hematopoiesis. In support of this, studies show that overexpression of HOXB4 strongly enhances hematopoietic stem cell regeneration. Here we find that mice deficient in both Hoxb3 and Hoxb4 have defects in endogenous hematopoiesis with reduced cellularity in hematopoietic organs and diminished number of hematopoietic progenitors without perturbing lineage commitment. Analysis of embryonic day 14.5 fetal livers revealed a significant reduction in the hematopoietic stem cell pool, suggesting that the reduction in cellularity observed postnatally is due to insufficient expansion during fetal development. Primitive Lin(-) Scal(+) c-kit(+) hematopoietic progenitors lacking Hoxb3 and Hoxb4 displayed impaired proliferative capacity in vitro. Similarly, in vivo repopulating studies of Hoxb3/Hoxb4-deficient hematopoietic cells resulted in lower repopulating capability compared to normal littermates. Since no defects in homing were observed, these results suggest a slower regeneration of mutant HSC. Furthermore, treatment with cytostatic drugs demonstrated slower cell cycle kinetics of hematopoietic stem cells deficient in Hoxb3 and Hoxb4, resulting in increased tolerance to antimitotic drugs. Collectively, these data suggest a direct physiological role of Hoxb4 and Hoxb3 in regulating stem cell regeneration and that these genes are required for maximal proliferative response.
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- Chen, Miaoxiang, 1962-, et al.
(author)
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1 micron wavelength photo- and electroluminescence from a conjugated polymer
- 2004
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 84:18, s. 3570-3572
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Journal article (peer-reviewed)abstract
- We report photo- and electroluminescence from an alternating conjugated polymer consisting of fluorene units and low-band gap donor-acceptor-donor (D-A-D) units. The D-A-D segment includes two electron-donating thiophene rings combined with a thiadiazolo-quinoxaline unit, which is electron withdrawing to its nature. The resulting polymer is conjugated and has a band gap of 1.27 eV. The corresponding electro- and photoluminescence spectra both peak at approximately 1 mum. Light-emitting diodes, based on a single layer of the polymer, demonstrated external quantum efficiencies from 0.03% to 0.05%.
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- Fischer, Hakan, et al.
(author)
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Right-sided human prefrontal brain activation during acquisition of conditioned fear.
- 2002
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In: Emotion. - : American Psychological Association (APA). - 1528-3542 .- 1931-1516. ; 2:3, s. 233-41
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Journal article (peer-reviewed)abstract
- This H2(15)O positron emission tomography (PET) study reports on relative regional cerebral blood flow (rCBF) alterations during fear conditioning in humans. In the PET scanner, subjects viewed a TV screen with either visual white noise or snake videotapes displayed alone, then with electric shocks, followed by final presentations of white noise and snakes. Autonomic nervous system responses confirmed fear conditioning only to snakes. To reveal neural activation during acquisition, while equating sensory stimulation, scans during snakes with shocks and white noise alone were contrasted against white noise with shocks and snakes alone. During acquisition, rCBF increased in the right medial frontal gyrus, supporting a role for the prefrontal cortex in fear conditioning to unmasked evolutionary fear-relevant stimuli.
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- Gadisa, Abay, et al.
(author)
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Correlation between oxidation potential and open-circuit voltage of composite solar cells based on blends of polythiophenes/fullerene derivative
- 2004
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 84:9, s. 1609-1611
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Journal article (peer-reviewed)abstract
- The photovoltaic parameters of donor/acceptor blend organic solar cells are highly influenced by several parameters, such as the strength of the acceptor species, the morphology of the film due to the solvent, and the mobility of the free charge carriers. In this work, the open-circuit voltage (Voc) of solar cells based on series of conjugated polythiophene polymers were measured and compared. In every cell, the donor polymer was blended with an electron acceptor fullerene molecule. The devices were constructed in a sandwich structure with indium tin oxide (ITO)/metallic polymer (PEDOT:PSS) acting as an anode and Al or LiF/Al acting as a cathode. Comparing the Voc of all the cells shows that this important photovoltaic parameter is systematically varying with the polymer. The variation of photovoltage is attributed to the variation of the oxidation potential of the donor conjugated polymers after due consideration of the different injection conditions in the varying polymers.
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- Ruseckas, Arvydas, et al.
(author)
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Luminescence quenching by inter-chain aggregates in substituted polythiophenes
- 2001
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In: Journal of Photochemistry and Photobiology, A: Chemistry. - 1873-2666 .- 1010-6030. ; 144:1, s. 3-12
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Journal article (peer-reviewed)abstract
- Time-resolved photo luminescence spectra measured in solid films of two polythiophene derivatives with different chain packing allow to distinguish emission of intra-chain excitations from the luminescence of inter-chain aggregates. Aggregate luminescence is red shifted by about 0.1 eV relative to intra-chain emission and shows vibronic coupling to the C=C bond stretch with the Huang-Phys factor of S approximate to 1.5, which is twice bigger than that of the intra-chain emission. Combining time resolved luminescence data with femtosecond transient absorption, we show that the dynamic quenching of the luminescence in films with dense chain packing is mainly due to excitation energy transfer to aggregates. The radiative lifetime of the lowest excited state of the aggregate with the optical gap of 1.84-1.9 eV is estimated to be about 20 ns. The aggregate contribution to the total luminescence in the polythiophene films with dense chain packing is about 50% and does not change significantly with temperature. (C) 2001 Elsevier Science B.V. All rights reserved.
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- Wang, Xiangjun, et al.
(author)
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Electrophosphorescence from substituted poly(thiophene) doped with iridium or platinum complex
- 2004
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In: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 468:1-2, s. 226-233
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Journal article (peer-reviewed)abstract
- Electrophosphorescence has been observed in doped polythiophene light-emitting diodes (LEDs) with poly(3-methyl-4-octylthiophene) [PMOT] as host and the phosphorescent compounds bis(2-phenylbenzothiazole) iridium acetylacetonate (BTIr) or platinum(II) 2,8,12,17-tetraethyl-3,7,13,18-tramethyl porphyrin (PtOX) as guest. The photoluminescence (PL) and electroluminescence (EL) of host–phosphorescent guest blends PMOT:BTIr (or PMOT:PtOX) showed the existence of energy transfer from host to guest, which were guest concentration-dependent. At a certain guest concentration, emission from host PMOT was completely quenched in both blends based LEDs, and this gave rise to electrophosphorescence. The PL from host PMOT in the PMOT:BTIr blend film could not be quenched completely but was totally quenched in PMOT:PtOX. This implies a more efficient energy transfer from PMOT to PtOX than that from PMOT to BTIr under optical excitation. Comparison of PL and EL showed that the mechanism of exciton formation at the guest site under electrical excitation was not identical for these two systems. Energy transfer was a dominating route for exciton formation in PMOT:PtOX-based LEDs; charge trapping effect additionally contributed to the formation of exciton at BTIr in PMOT:BTIr-based LEDs. This study demonstrates a new direction in which polythiophene can be a candidate as a host to realize electrophosphorescence in polymer light-emitting diodes (PLEDs). Authors further indicate that to optimize the performance of the polythiophe/phosphorescent complexes, LEDs proper polythiophenes with large bang gap are needed.
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