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  • 1
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 1071-1073 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present an application of an active emitting cantilever probe for scanning near-field optical microscopy and scanning force microscopy. A vertical cavity surface emitting laser (VCSEL) integrated in a galliumarsenide (GaAs) cantilever serves as a light source at 980 nm emission wavelength that is below the band gap energy of the GaAs substrate material. The VCSEL of 8 μm diameter is centered with respect to the metalized GaAs tip and illuminates a small near-field aperture at its apex. Aperture fabrication is accomplished by a proper thermal metal evaporation process. Optical measurements on a Fischer projection pattern revealed an edge resolution of about 80 nm. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0649
    Keywords: PACS: 07.79.-v; 07.79.Lh; 84.40; 42.65.Re
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We report on the fabrication process of a scanning force microscopy (SFM) cantilever probe suitable for the investigation of ultrafast transient signals in microwave integrated circuits. High temporal resolution is achieved by integrating a laser-gated photoconductive switch within a coplanar waveguide structure onto a low-temperature GaAs cantilever. This is demonstrated by temporal and spatio-temporal measurements performed on a coplanar strip line.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 61 (1983), S. 703-708 
    ISSN: 1432-1440
    Keywords: Liver cirrhosis ; Thrombocytopenia ; DIC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Besides decreased platelet production and an increased platelet sequestration in the spleen chronic DIC is thought to cause thrombocytopenia in chronic liver diseases. To investigate if this mechanism could play a role in patients with severe, but stable hepatic cirrhosis, we studied 32 pts. Twenty-eight of them had portal hypertension, 22 had bleeding episodes from oesophageal varices. To evaluate platelet activity, thrombin generation and fibrinolytic activity in vivo, plasma and platelet levels ofβ-thromboglobulin (β-TG) and platelet factor 4 (PF4) as well as fibrinopeptide A (FPA) and the fibrinogen degradation product FCB-3, generated by the action of plasmin, were determined radioimmunologically. Plasma levels and platelet content of serotonin (5-HT) were measured fluorometrically. The mean platelet count/µl was reduced in pts. (109.000±67.000) compared to a control group (n=25, 264,000±52,000,p〈0.001). Factor VII (45±20%), prothrombin time (63±16%) AT-III activity (65±19%) and AT-III concentration (67±23%) were decreased in the pts'. group (p〈0.01). In contrast, plasma levels ofβ-TG (17±7 ng/ml) and of PF4 (4±2 ng/ml) as well as platelet content (µg/109 platelets) ofβ-TG (59±18), PF4 (21±6) and 5-HT (400±210) were found to be in the normal range. Neither mean FPA plasma concentration (3±2 ng/ml) nor mean FCB-3 scrum level (11±5 pmol/ml) differed significantly from controls. Our results demonstrate that pts. with thrombocytopenia and stable hepatic cirrhosis do not have evidence of chronic DIC, primary fibrinolysis or increased platelet activity in vivo. However, our results are compatible with increased platelet sequestration in the spleen and/or decreased platelet survival due to faster extravascular platelet clearance, or decreased platelet production within the bone marrow.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 66 (1998), S. S385 
    ISSN: 1432-0630
    Keywords: PACS: 07.79; 07.79.c; 84.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: We report on novel developments in the field of gallium arsenide cantilevers with integrated tips for SPM applications. As a result of an intensive study of the gallium arsenide etching behavior we are able to adapt the tip shape to the requirements in SPM, for example, high aspect ratio, minimized radius of curvature, and low surface roughness. These cantilevers represent the basic sensor design for both passive as well as active scanning near-field probes. As a first approach, for an active SPM probe a Schottky diode integrated in the tip apex was produced. First results on the thermal and optical characterization of Schottky diode probes are presented. High-frequency measurements of a coplanar microwave guide made of semi-insulating GaAs in comparison to silicon were carried out. Additionally, concepts for a light-emitting diode and a laser diode integrated in a tip – a challenge for future concepts in SNOM – are discussed.
    Type of Medium: Electronic Resource
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