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  • 1
    Electronic Resource
    Electronic Resource
    Auger coefficients in type-II InAs/Ga1−xInxSb quantum wells (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 2857-2859 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Two different approaches, a photoconductive response technique and a correlation of lasing thresholds with theoretical threshold carrier concentrations have been used to determine Auger lifetimes in InAs/GaInSb quantum wells. For energy gaps corresponding to 3.1–4.8 μm, the room-temperature Auger coefficients for seven different samples are found to be nearly an order-of-magnitude lower than typical type-I results for the same wavelength. The data imply that at this temperature, the Auger rate is relatively insensitive to details of the band structure. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122609
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  • 2
    Electronic Resource
    Electronic Resource
    Role of internal loss in limiting type-II mid-IR laser performance (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 2384-2391 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report an experimental and theoretical investigation of internal losses in optically pumped type-II lasers with InAs/GaSb/Ga1−xInxSb/GaSb superlattice active regions. Whereas the losses are found to be moderate at 100 K (11–14 cm−1), they increase rapidly with increasing temperature (to 50–120 cm−1 at 200 K). Comparison with a detailed numerical simulation shows that the internal losses play a much more important role than Auger recombination or carrier/lattice heating in limiting the laser performance at high temperatures. Calculations of the temperature-dependent intervalence absorption cross sections show that losses of the magnitude observed experimentally can easily occur if one does not take special care to avoid resonances in all regions of the Brillouin zone. Practical design guidelines are presented. The superlattice lasers yield maximum peak output powers of up to 6.5 W per facet at 100 K and 3.5 W per facet at 180 K, threshold incident pump intensities as low as 340 W/cm2 at 100 K, and Shockley–Read lifetimes 〉30 ns at 100 K. The Auger coefficients are suppressed (≤1.6×10−27 cm6/s at T=260 K) despite the intervalence resonances which produce the high internal losses. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.366997
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  • 3
    Electronic Resource
    Electronic Resource
    Simulation of mid-infrared HgTe/CdTe quantum-well vertical-cavity surface-emitting lasers (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 4286-4291 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We theoretically show the feasibility of optically and electrically pumped Hg-based vertical-cavity surface-emitting lasers (VCSELs) that emit at midwave-infrared wavelengths up to thermoelectric cooler temperatures. The maximum operating temperature is significantly enhanced by employing a multiple quantum-well active region with very thin (20–30 Å) HgTe wells engineered to yield a strong suppression of both Auger recombination and intervalence free-carrier absorption. Hg0.65Cd0.35Te/Hg0.1Cd0.9Te distributed Bragg reflectors are employed for one or both of the mirrors defining the optical cavity. Detailed numerical simulations of VCSELs emitting at λ(approximate)4.3 μm predict that for optical pumping at 1.06 μm, a maximum operating temperature of 220 K should be achievable for pulsed operation and 160 K in cw mode, with a cw power output of up to 2.6 mW per array element at 100 K. Injection VCSELs are predicted to operate up to 200 K for pulsed operation and 105 K for quasi-cw with a 10% duty cycle. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.367187
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  • 4
    Electronic Resource
    Electronic Resource
    Near-room-temperature mid-infrared interband cascade laser (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 2370-2372 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A 25-stage interband cascade laser with a W active region and a third hole quantum well for the suppression of leakage current has exhibited lasing in pulsed mode up to 286 K. A peak output power of 160 mW/facet and a slope efficiency of 197 mW/A per facet (1.1 photons per injected electron) were measured at 196 K. Above 200 K, the characteristic temperature was higher (T0=53 K) and the threshold current densities lower than for a previously reported W interband cascade laser without the third hole quantum well. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121359
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  • 5
    Electronic Resource
    Electronic Resource
    Above-room-temperature optically pumped midinfrared W lasers (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 3833-3835 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report temperature-dependent pulsed lasing performance, internal losses, and Auger coefficients for optically pumped type-II W lasers with wavelengths in the range of 3.08–4.03 μm at room temperature. All lased to at least 360 K, and produced 1.5–5 W peak power at 300 K. Internal losses at 100 K were as low as 10 cm−1, but increased to 90–360 cm−1 at 300 K. Room temperature Auger coefficients varied from 5×10−28 cm6/s at the shortest wavelength to 3×10−27 cm6/s at the longest. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122909
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  • 6
    Electronic Resource
    Electronic Resource
    Design and simulation of low-threshold antimonide intersubband lasers (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 711-713 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Optically and electrically pumped infrared lasers based on intersubband transitions in InAs/GaSb/AlAsSb quantum wells are modeled in detail. The large conduction-band offset of the AlAsSb barriers with respect to the InAs wells allows the lasing wavelength to be shortened to at least 1.9 μm. Furthermore, the small InAs electron mass results in longer phonon-limited lifetimes in the upper lasing subband as well as larger dipole matrix elements. This leads to the prediction of lower threshold currents, and hence, higher cw operating temperatures than for quantum cascade lasers based on the InGaAs/InAlAs/InP system. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121976
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  • 7
    Electronic Resource
    Electronic Resource
    Improved quantitative mobility spectrum analysis for Hall characterization (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 4966-4973 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present an improved quantitative mobility spectrum analysis (i-QMSA) procedure for determining free electron and hole densities and mobilities from magnetic-field-dependent Hall and resistivity measurements on bulk or layered semiconductor samples. The i-QMSA technique is based on a fundamentally new approach, which optimizes the fit to the conductivity tensor components and their slopes by making those adjustments in the mobility spectra that result in the greatest error reduction. Empirical procedures for manipulating the mobility spectra are also introduced, with the dual purpose of reducing the error of the fit and simplifying the shape of the spectra to minimize the presence of unphysical artifacts. A fully automated computer implementation of the improved QMSA is applied to representative synthetic and real data sets involving various semiconductor material systems. These results show that, as compared with previous approaches, the presented algorithm maximizes the information that may be extracted from a given data set, and is suitable for use as a standard tool in the characterization of semiconductor material and device transport properties. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.368741
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  • 8
    Electronic Resource
    Electronic Resource
    Prävention katheterassoziierter Infektionen Die offiziellen amerikanischen Empfehlungen – fundierte Antworten auf alltägliche Fragen (1998)
    Springer
    Der Anaesthesist 47 (1998), S. 136-142 
    Details
    ISSN: 1432-055X
    Keywords: Schlüsselwörter Infektionsprävention ; Desinfektion ; Sepsis ; Komplikation ; Risikofaktoren ; Katheterwechsel ; Key words Infection prevention and control ; Disinfection methods ; Equipment Contamination ; Risk factors ; Septicemia ; catheters ; indwelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract The official German guidelines for prevention of intravascular-device-associated infections were published by the Bundesgesundheitsamt, now called the Robert-Koch-Institut, 12 years ago. The recently published official „Guidelines for Prevention of Intravascular-Device Associated Infections” of the Centers for Disease Control and Prevention (CDC) are categorized according to scientific evidence. The American guidelines are very detailed and differ in some aspects from the offical German guidelines. The purpose of the present paper is to inform the German-speaking anaesthesiologist about the official CDC guidelines and to provide an update on the prevention of intravascular-device-associated infections.
    Notes: Zusammenfassung Die offiziellen deutschen Richtlinien zur Prävention katheterassoziierter Infektionen durch das frühere Bundesgesundheitsamt (jetzt Robert-Koch-Institut) sind mittlerweile 12 Jahre alt. Die kürzlich publizierten offiziellen Empfehlungen der amerikanischen Centers for Disease Control and Prevention (CDC) beruhen auf vorhandenen wissenschaftlichen Daten und sind daraufhin bezüglich ihrer Wertigkeit kategorisiert worden. Diese umfassenden Empfehlungen sind wesentlich ausführlicher als die offiziellen deutschen Richtlinien und weisen zu diesen teilweise beträchtliche Unterschiede auf. Mit dieser kurzen Darstellung der amerikanischen Richtlinien soll dem Kliniker für die eigene praktische Tätigkeit bezüglich vieler alltäglicher, aber keineswegs nebensächlicher Probleme eine fundierte Entscheidungshilfe zur Verfügung gestellt werden.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001010050538
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  • 9
    Electronic Resource
    Electronic Resource
    Die offiziellen amerikanischen Empfehlungen zur Prävention nosokomialer Pneumonien (1998)
    Springer
    Der Anaesthesist 47 (1998), S. 925-935 
    Details
    ISSN: 1432-055X
    Keywords: Schlüsselwörter Infektionsprävention ; Pneumonie ; Risiokofaktoren ; Desinfektion ; Key words Infection prevention and control ; Pneumonia ; Disinfection methods ; Risk factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract The official German guidelines for prevention of nosocomial pneumonia were published by the Bundesgesundheitsamt, now called Robert-Koch-Institut, twelve years ago. The recently published official ”guidelines for prevention of nosocomial pneumonia” of the Centers for Disease Control and Prevention (CDC) are categorized according to scientific evidence. The American guidelines are very detailed and differ in some aspects from the official German guidelines. The purpose of the present paper is to inform the German anaesthesiologist about the official CDC guidelines and to provide a renewed background for the prevention of nosocomial pneumonia.
    Notes: Zusammenfassung Die offiziellen deutschen Richtlinien zur Prävention nosokomialer Pneumonien durch das frühere Bundesgesundheitsamt (jetzt Robert-Koch-Institut) sind mittlerweile 12 Jahre alt. Die kürzlich publizierten offiziellen Empfehlungen der amerikanischen Centers for Disease Control and Prevention (CDC) beruhen auf vorhandenen wissenschaftlichen Daten und sind daraufhin bezüglich ihrer Wertigkeit kategorisiert. Diese umfassenden Empfehlungen sind wesentlich ausführlicher als die offiziellen deutschen Richtlinien und weisen zu diesen teilweise beträchtliche Unterschiede auf. Mit dieser kurzen Darstellung der amerikanischen Richtlinien soll dem Kliniker für die eigene praktische Tätigkeit bezüglich vieler alltäglicher, aber keineswegs nebensächlicher Probleme eine fundierte Entscheidungshilfe zur Verfügung gestellt werden.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001010050644
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  • 10
    Electronic Resource
    Electronic Resource
    Concentrations of Metals Associated with Mining Waste in Sediments, Biofilm, Benthic Macroinvertebrates, and Fish from the Coeur d'Alene River Basin, Idaho (1998)
    Springer
    Archives of environmental contamination and toxicology 34 (1998), S. 119-127 
    Details
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract. Arsenic, Cd, Cu, Pb, Hg, and Zn were measured in sediments, biofilm, benthic macroinvertebrates, and fish from the Coeur d'Alene (CDA) River to characterize the pathway of metals transfer between these components. Metals enter the CDA Basin via tributaries where mining activities have occurred. In general, the ranking of food-web components from the greatest to smallest concentrations of metals was as follows: biofilm (the layer of abiotic and biotic material on rock surfaces) and sediments 〉 invertebrates 〉 whole fish. Elevated Pb was documented in invertebrates, and elevated Cd and Zn were documented in sediment and biofilm approximately 80 km downstream to the Spokane River. The accumulation of metals in invertebrates was dependent on functional feeding group and shredders-scrapers that feed on biofilm accumulated the largest concentrations of metals. Although the absolute concentrations of metals were the largest in biofilm and sediments, the metals have accumulated in fish approximately 50 km downstream from Kellogg, near the town of Harrison. While metals do not biomagnify between trophic levels, the metals in the CDA Basin are bioavailable and do biotransfer. Trout less than 100 mm long feed exclusively on small invertebrates, and small invertebrates accumulate greater concentrations of metals than large invertebrates. Therefore, early-lifestage fish may be exposed to a larger dose of metals than adults.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002449900295
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