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  • 2000-2004  (23)
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  • 1
    Electronic Resource
    Electronic Resource
    Optical parameters of a magnetized space-charge neutral group IV semiconductor (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 4910-4916 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using a hydrodynamic model of semiconductor plasmas, we report an analytical investigation of hot-carrier induced nonlinearity and its impact on the optical parameters (refractive index and absorption coefficient) of a magnetized, space-charge neutral group IV semiconductor. The carrier heating by the pump is assumed to induce nonlinearity in the medium through momentum transfer collision frequency ν of the carriers and space-charge neutrality of the medium. For the linear optical parameters (nl, al), both electrons and holes are found to contribute resonantly at high frequency of the pump (ω0(approximate)ωce). For the nonlinear optical parameters (n2, a2), the holes contribute significantly in the low pump frequency regime (ω0(approximate)ωch,) whereas in the high pump frequency regime (ω0(approximate)ωce), both kinds of carriers contribute resonantly in which a much larger contribution comes from the electrons. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1456245
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  • 2
    Electronic Resource
    Electronic Resource
    Optical parameters of a magnetized semiconductor plasma with nonparabolic band structure (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 4741-4746 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The optical parameters (linear and nonlinear) and dispersion characteristics of a III–V compound semiconductor plasma subjected to a strong transverse magnetic field have been investigated theoretically. The nonlinearity induced in the medium has been attributed to heating of the carriers by the pump that results in modification of the electron effective mass in a nonparabolic conduction band and the momentum transfer collision frequency of electrons. The external magnetic field is found to have two consequences: (a) increasing the nonlinearity of the medium and (b) modifying the dispersion characteristics and determining the direction of energy flow between the pump and the generated waves. The plasma frequency ωp is found to enhance the magnitude of the optical parameters as usual. For a typical n-InSb semiconductor, linear refractive index and nonlinear refractive index coefficients are found maximum (nl=5.3, nnl=2×10−10 m2 V−2) whereas absorption coefficients al (linear) and anl (nonlinear) are found to vanish when ωo resonates with ωc(=1.138×1014 s−1). The present study once again establishes the device potentials of n-InSb. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1358315
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  • 3
    Electronic Resource
    Electronic Resource
    QUANTUM DOT OPTO-ELECTRONIC DEVICES (2004)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Materials Research 34 (2004), S. 1-40 
    Details
    ISSN: 1531-7331
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Highly strained semiconductors grow epitaxially on mismatched substrates in the Stranski-Krastanow growth mode, wherein islands are formed after a few monolayers of layer-by-layer growth. Elastic relaxation on the facet edges, renormalization of the surface energy of the facets, and interaction between neighboring islands via the substrate are the driving forces for self-organized growth. The dimensions of the defect-free islands are of the order lambaB, the de Broglie wavelength, and provide three-dimensional quantum confinement of carriers. Self-organized In(Ga)As/GaAs quantum dots, or quantum boxes, are grown by molecular beam expitaxy (MBE) or metal-organic vapor phase epitaxy (MOVPE) on GaAs, InP, and other substrates and are being incorporated in microelectronic and opto-electronic devices. The use of strain to produce self-organized quantum dots has now become a well-accepted approach and is widely used in III-V semiconductors and other material systems. Much progress has been made in the area of growth, where focus has been on size control, and on optical characterization, where the goal has been the application to lasers and detectors. The unique carrier dynamics in the dots, characterized by femtosecond pump-probe spectroscopy, has led to novel device applications. This article reviews the growth and electronic properties of InGaAs quantum dots and the characteristics of interband and intersublevel lasers and detectors and modulation devices.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.matsci.34.040203.111535
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  • 4
    Electronic Resource
    Electronic Resource
    A new telemetry system for a balloon-borne far-infrared astronomical telescope (2000)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 281-288 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new telemetry system (NTS) is described here, which has been developed for a balloon-borne far-infrared astronomical telescope. The NTS includes two space borne encoders (TEs) and the ground station decoder and display subsystems. The design of the TEs uses several novel ideas which simplify on-board hardware implementation. The NTS has shown satisfactory in-flight performance and is now a standard package for regular balloon flight experiments. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1150194
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  • 5
    Electronic Resource
    Electronic Resource
    Surface-emitting spin-polarized In0.4Ga0.6As/GaAs quantum-dot light-emitting diode (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 658-660 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the properties of a spin-polarized In0.4Ga0.6As/GaAs quantum-dot surface-light-emitting diode with a Ga0.974Mn0.026As spin injector layer. Spin-polarized holes from this ferromagnetic layer recombine with electrons in the quantum dots to produce circularly polarized light output. The peak optical polarization efficiency at 5.1 K is 18% and the spin injection efficiency is estimated to be ∼36%. The temperature dependence of spin injection is almost identical to the temperature dependence of magnetization in the (Ga, Mn)As layer. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1436526
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  • 6
    Electronic Resource
    Electronic Resource
    Conduction band offset in InAs/GaAs self-organized quantum dots measured by deep level transient spectroscopy (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 2571-2573 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The heterostructure conduction band offset, ΔEc, in InAs/GaAs self-organized quantum dots has been measured by deep level transient spectroscopy. Measurements were made with Au–Al0.18Ga0.82As Schottky diodes in which the multilayer dots are embedded in the ternary layer. The estimated value of the band offset ΔEc=341±30 meV. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.126411
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  • 7
    Electronic Resource
    Electronic Resource
    Temperature-dependent measurement of Auger recombination in self-organized In0.4Ga0.6As/GaAs quantum dots (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 722-724 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report experimental studies of temperature-dependent Auger recombination coefficients in self-assembled quantum dots. The results are based on a study of temperature-dependent large signal modulation experiments made on self-organized In0.4Ga0.6As/GaAs quantum dot lasers. The Auger coefficient decreases from ∼8×10−29 cm6/s at 100 K to ∼4×10−29 cm6/s at 300 K. This behavior, which is different from results in other higher-dimensional systems, is explained in terms of the temperature dependence of electron-hole scattering in the dots and contribution from higher lying states in the dot and adjoining layers. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1391401
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  • 8
    Electronic Resource
    Electronic Resource
    Pre-printed format improves recording of instrumental vaginal delivery (2004)
    Bradford : Emerald
    Clinical governance 9 (2004), S. 91-95 
    Details
    ISSN: 1477-7274
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Medicine , Economics
    Notes: Instrumental vaginal delivery is an area often responsible for indefensible claims. One of the important reasons for this is poor medical record keeping. The standard of record keeping for instrumental vaginal deliveries within our unit was audited with a view to improving deficiencies. A retrospective analysis of 100 case records of women having an instrumental vaginal delivery was made over a period of one year. After identifying deficiencies in the quality of record keeping a pre-printed standard record form was introduced and a further 50 cases audited. Deficiencies were identified in the documentation of clinical obstetric findings, type of anaesthesia, estimated blood loss, type and size of ventouse cup used. Analysis of cases using the standard record form has demonstrated 100 percent compliance with adequate record keeping.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1108/14777270410536367
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  • 9
    Electronic Resource
    Electronic Resource
    Intravenous CDP870, a PEGylated Fab′ fragment of a humanized antitumour necrosis factor antibody, in patients with moderate-to-severe Crohn's disease: an exploratory study (2004)
    Oxford, UK : Blackwell Science Ltd
    Alimentary pharmacology & therapeutics 20 (2004), S. 0 
    Details
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background : CDP870 is a PEGylated Fab′ fragment of a humanized monoclonal antibody that neutralizes tumour necrosis factor-α.Aim : To evaluate the safety and efficacy of a single intravenous dose of CDP870 or placebo over a 12-week period in patients with moderate-to-severe Crohn's disease.Methods : Ninety-two adult patients with Crohn's disease (Crohn's Disease Activity Index: 220–450 points) were randomized to receive CDP870 [1.25 (n = 2), 5 (n =26), 10 (n = 17) or 20 mg/kg (n = 23)] or placebo (n = 24). Crohn's Disease Activity Index scores were determined at weeks 0, 2, 4, 8 and 12. The primary end-point was the percentage of patients achieving clinical response [i.e. a decrease in Crohn's Disease Activity Index score ≥ 100 points or remission (Crohn's Disease Activity Index score: ≤150 points)] at week 4 in the intent-to-treat population.Results : The percentage of patients achieving the primary end-point was comparable across all treatment groups (56.0%, 60.0%, 58.8% and 47.8% for placebo, CDP870 5, 10 and 20 mg/kg, respectively). The remission rate at week 2 was 47.1% with CDP870 10 mg/kg vs. 16.0% for placebo (P = 0.041). All treatments were well-tolerated: adverse events, reported by 43 patients treated with CDP870 and 15 patients treated with placebo, were mainly mild-to-moderate in intensity. There were no infusion reactions.Conclusions : A single intravenous dose of CDP870 was well-tolerated by patients with Crohn's disease. While no statistically significant difference in clinical response rates between CDP870 and placebo was observed, clinical benefit in terms of remission was demonstrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2036.2004.02285.x
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  • 10
    Electronic Resource
    Electronic Resource
    Is clinical remission the optimum therapeutic goal in the treatment of Crohn's disease? (2002)
    Oxford UK : Blackwell Science Ltd
    Alimentary pharmacology & therapeutics 16 (2002), S. 0 
    Details
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Currently, the therapeutic end-point in the treatment of Crohn's disease is the remission of symptoms, but recent data confirm that mucosal inflammation may continue in the absence of symptoms. Furthermore, emerging evidence indicates that such subtle, sub-clinical mucosal inflammation leads to clinical relapse. The assessment of mucosal inflammation has become easier with the availability of faecal calprotectin assay. Current anti-inflammatory therapy often leaves low-grade mucosal inflammation untreated, and therefore recurrent relapses occur. We need to investigate whether the therapeutic end-point of anti-inflammatory medications needs to be more rigorous and to aim at complete mucosal healing, confirmed by the normalization of mucosal inflammatory markers such as faecal calprotectin concentrations. Immunosuppressive therapy with azathioprine/ 6-mercaptopurine currently offers the best mucosal healing treatment with reduction of relapses, but newer biological agents might offer less toxic therapy. Clinical trials to test the feasibility and efficacy of such a paradigm shift in the medical management of Crohn's disease are now warranted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2036.2002.01242.x
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