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  • 2005-2009  (4)
  • 2000-2004  (22)
  • 1930-1934  (4)
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  • 1
    Digitale Medien
    Digitale Medien
    High-gain coupled InGaAs quantum well InAs quantum dot AlGaAs–GaAs–InGaAs–InAs heterostructure diode laser operation (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 1126-1128 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Data are presented showing that a single-layer InAs quantum dot (QD) laser in the AlGaAs–GaAs–InGaAs–InAs heterostructure system is improved in gain and continuous wave (cw) room temperature operation by coupling, via tunneling, auxiliary strained-layer InGaAs quantum wells (QWs) to the single InAs QD layer to assist carrier collection and thermalization. A QW-assisted single-layer InAs QD laser, a QD+QW laser, is demonstrated that operates cw (300 K), and at diode length 150 μm in pulsed operation exhibits gain as high as ∼100 cm−1. © 2002 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1451989
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  • 2
    Digitale Medien
    Digitale Medien
    Coupled strained-layer InGaAs quantum-well improvement of an InAs quantum dot AlGaAs–GaAs–InGaAs–InAs heterostructure laser (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 4500-4502 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Data are presented showing that, besides the improvement in carrier collection, it is advantageous to locate strain-matching auxiliary InGaAs layers [quantum wells (QWs)] within tunneling distance of a single-quantum-dot (QD) layer of an AlGaAs–GaAs–InGaAs–InAs QD heterostructure laser to realize also smaller size QDs of greater density and uniformity. The QD density is changed from 2×1010/cm2 for a 50 Å GaAs coupling barrier (QW to QD) to 3×1010/cm2 for a 5 Å barrier. The improved QD density and uniformity, as well as improved carrier collection, make possible room-temperature continuous-wave (cw) QD+QW laser operation (a single InAs QD layer) at reasonable diode length (∼1 mm), current density 586 A/cm2, and wavelength 1057 nm. The cw 300 K coupled InAs QD and InGaAs QW AlGaAs–GaAs–InGaA–InAs heterostructure lasers are grown by metalorganic chemical vapor deposition. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1430025
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  • 3
    Digitale Medien
    Digitale Medien
    Room-temperature continuous photopumped laser operation of coupled InP quantum dot and InGaP quantum well InP–InGaP–In(AlGa)P–InAlP heterostructures (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 1956-1958 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Data are presented demonstrating continuous 300 K photopumped InP quantum dot (QD) laser operation (656–679 nm) realized by modifying and coupling, via tunneling, an auxiliary InGaP quantum well (QW) to the QDs of an InP–In(AlGa)P–InAlP heterostructure grown by metalorganic chemical vapor deposition. The In0.49Ga0.51P QW coupled to the InP QDs by a thin ((approximately-less-than)20 Å) In0.5Al0.3Ga0.2P barrier overcomes the limitations of carrier collection, lateral transport, and thermalization in the QDs, thus yielding a different form of QD laser. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1405153
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  • 4
    Digitale Medien
    Digitale Medien
    Coupled InP quantum-dot InGaP quantum well InP–InGaP–In(AlGa)P–InAlP heterostructure diode laser operation (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 3215-3217 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Data are presented showing that a p–n InP–In0.5Ga0.5P–In0.5(Al0.3Ga0.2)P–In0.5Al0.5P quantum-dot (QD) heterostructure diode, with an auxiliary ∼20 Å InGaP quantum well (QW) coupled via an In(AlGa)P barrier (∼20 Å) to the single layer of QDs to aid carrier collection, has a steeper current–voltage characteristic than the case of a similar diode with no auxiliary QW. The p–n InP+InGaP QD+QW diode is capable of 300 K visible-spectrum QD laser operation, while the single-layer InP QD diode (single QD layer) saturates at low current ((approximately-less-than)1 mA) and does not exhibit stimulated emission. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1416158
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  • 5
    Digitale Medien
    Digitale Medien
    Coupled-stripe quantum-well-assisted AlGaAs–GaAs–InGaAs–InAs quantum-dot laser (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 3045-3047 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Data are presented on the coupled-stripe laser operation (continuous wave, 300 K) of a single InAs quantum-dot (QD) layer coupled via a thin (5 Å) GaAs barrier to an auxiliary strained InGaAs quantum well (QW) grown (confined) in an AlGaAs–GaAs heterostructure. Because of strain-induced (QW strain) improvement of the QD growth and QD alignment along diagonal (reflecting) ridges, the InGaAs-QW+InAs-QD crystals exhibit high gain along and across laser stripes, which is advantageous for coupled-stripe laser operation. A twin-stripe single-QD-layer QW+QD laser (4 μm stripes on 6 μm centers) of usual cleaved length, 〈 500 μm, is capable of continuous 300 K operation, with only probe heat-sink clamping and testing, at 〉50 mW. © 2002 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1473686
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  • 6
    Digitale Medien
    Digitale Medien
    An ALS mouse model with a permeable blood–brain barrier benefits from systemic cyclosporine A treatment (2004)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 88 (2004), S. 0 
    Details
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: To test potentially beneficial drugs to amyotrophic lateral sclerosis (ALS), we created an ALS mouse model with a permeable blood–brain barrier, by crossing the G93A-SOD1 transgenic mouse with a multiple drug resistance type 1a/b (mdr1a/b) gene knockout mouse. To validate the model, we administered cyclosporine A intraperitoneally to the mice. Cyclosporine A accumulated in the brain and spinal cord of this mouse model, whereas it was unable to penetrate the CNS of mdr1a/b wild-type animals. Systemic administration of cyclosporine A extended the life of the double-mutant male mice by approximately 12%. Surprisingly, the effect was more robust in male mice and only marginal in female mice. These results demonstrate the usefulness of this combined mouse model for the testing of potentially therapeutic drugs and support the role of mitochondrial-mediated apoptosis in the pathway to motor neuron death in SOD1-associated ALS.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1471-4159.2003.02181.x
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  • 7
    Digitale Medien
    Digitale Medien
    Fracture Toughness of Dental Porcelains Evaluated by IF, SCF, and SEPB Methods (2005)
    Oxford, UK : Blackwell Science Inc
    Journal of the American Ceramic Society 88 (2005), S. 0 
    Details
    ISSN: 1551-2916
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Maschinenbau , Physik
    Notizen: Fracture toughness of six dental porcelains with leucite content ranging from 0 to 22 vol% was evaluated by indentation fracture (IF), surface crack in flexure (SCF), and single edge pre-cracked beam (SEPB) methods. The results of the IF method were similar to those of the SCF method for all the porcelains investigated. The results of the SEPB were similar to those of the other two methods only for the glassy porcelains, but for leucite-based porcelains this method resulted in higher values of KIc. Based on microstructure, fractographic analysis, and an additional single edge V-notched beam test, it was concluded that the pre-crack size influences the value of KIc for porcelains reinforced by leucite. For design and failure analysis purposes, the KIc determined by SCF method should be preferred, since fracture of dental restorations usually starts from small surface cracks.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1551-2916.2005.00334.x
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  • 8
    Digitale Medien
    Digitale Medien
    ROBERT T. JONES, ONE OF A KIND (2005)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 37 (2005), S. 1-21 
    Details
    ISSN: 0066-4189
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Maschinenbau , Physik
    Notizen: His contemporaries saw R.T. Jones as one of the notably creative aerodynamicists of the twentieth century. This essay reviews his remarkable life and career, including his years as a farm-country boy, college dropout, and fledgling airplane designer in Missouri, his time as an elevator operator and self-directed student in Washington, D.C., and his long professional career as an aerodynamicist at the Langley and Ames Aeronautical Laboratories and Stanford University. The focus in his career is on his fundamental discovery of the benefits of sweepback for the wings of high-speed airplanes. This includes speculation about his highly intuitive thought processes in arriving at his creative ideas. I also give an account of his work on blood flow and the mechanical heart, his avocational accomplishments as a maker of telescopes and violins, and his philosophical interest in human affairs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.fluid.36.050802.122008
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  • 9
    Digitale Medien
    Digitale Medien
    Prejudice Toward People With Cancer or AIDS: Applying the Integrated Threat Model (2002)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of applied biobehavioral research 7 (2002), S. 0 
    Details
    ISSN: 1751-9861
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Psychologie
    Notizen: Two experiments applied the integrated threat theory of prejudice to predicting attitudes toward people with terminal cancer or AIDS. The measures, which were designed to assess the components of the model (realistic threats, symbolic threats, inter group anxiety, and negative stereotypes), were reliable and generally predictive of attitudes. The theory predicted attitudes toward AIDS better than attitudes toward cancer, perhaps because more people believe that they are likely to become a member of the cancer out-group. The benefits of applying social psychological theory to health issues are discussed along with suggestions for future research.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1751-9861.2002.tb00078.x
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  • 10
    Digitale Medien
    Digitale Medien
    Size distribution of aquatic invertebrates in two prairie wetlands, with and without fish, with implications for community production (2001)
    Oxford UK : Blackwell Science Ltd
    Freshwater biology 46 (2001), S. 0 
    Details
    ISSN: 1365-2427
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: 1. We compared the size distribution of aquatic invertebrates in two prairie wetlands, one supporting a population of fathead minnows and the other fishless. Both wetlands were sampled in three depth zones on three dates, allowing assessment of temporal and spatial variation.2. We determined biomass of aquatic invertebrates in 17 log2 size classes, and used these data to develop normalized size spectra. We also coupled size distributions with an allometric model to estimate relative production at the community level.3. The composition of the invertebrate communities differed greatly between sites, and invertebrate biomass was higher in nearly all size classes in the fishless wetland. Intercepts of normalized size spectra were significantly different between wetlands, but slopes generally were not, indicating differences in standing-stock biomass but similar size structures between the two invertebrate communities. Higher standing-stock biomass in the fishless wetland resulted in higher relative production per unit area, but similar size distributions resulted in similar mass-specific production (P/B) between wetlands.4. Our results indicate that invertebrate communities in prairie wetlands may have relatively consistent size structures in spite of large differences in community composition and standing-stock biomass. We hypothesize that the observed differences are because of predation by the minnow population and/or differences in the macrophyte communities between the two sites. However, the relative importance of macrophytes and fish predation in structuring invertebrate communities in prairie wetlands is poorly known.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-2427.2001.00759.x
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