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  • 1
    Electronic Resource
    Electronic Resource
    Six-circle diffractometer for surface diffraction using an in-vacuum x-ray detector (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3239-3243 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We report on the design of a diffractometer, which offers improved capabilities for x-ray experiments in ultrahigh vacuum. Its main features are (i) the possibility to follow the evolution of diffraction spots in situ during adsorption or film deposition; (ii) the measurement of reflections at high exit angles, i.e., large perpendicular momentum transfer. This goal is achieved by placing a movable x-ray detector inside the vacuum chamber. (iii) Other surface analysis equipment, e.g., a low-energy electron diffraction or an electron energy analyzer can be moved in front of the sample and operated simultaneously with x-ray diffraction. (iv) A load lock system—currently in preparation—will allow the quick exchange of samples without breaking system vacuum. In addition, a new design of the chi circle used for sample alignment provides a compact, space-saving design of the diffractometer. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149899
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  • 2
    Electronic Resource
    Electronic Resource
    Ultrafast broadband frequency modulation of a continuous wave reflectometry system to measure density profiles on ASDEX Upgrade (1996)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 4138-4145 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A reflectometry system has been developed for ASDEX Upgrade to measure the plasma profile from the scrape-off layer until the bulk plasma, simultaneously at the high and low field sides. Unique features of the system are the ultrafast broadband frequency modulation of a continuous wave using solid state stable hyper abrupt tuned oscillators (down to 10 μs), high and low field side channels and fully remote control operation, via optical fiber links. Due to the special design of the transmission line, with decoupled in going and out going lines and one-antenna configuration, the system is optimized for reception and spurious reflections are eliminated. The ultrafast operation guarantees that the effect of plasma turbulence is greatly reduced. Both features determine the high performance of the diagnostic. A dedicated data acquisition system handles the large amounts of data generated by the broadband operation. Recent developments include the operation of new channels and an automatic and accurate frequency calibration circuit. Also, advanced digital signal processing techniques were applied to obtain density profiles with high spatial and temporal (20 μs) resolutions under turbulent plasma regions, e.g., the scrape-off layer. Experimental results are presented showing the great sensitivity of the diagnostic to plasma radial movements and its tolerance to vertical movements of the plasma. Density profiles measured in ELMy regimes illustrate the capabilities of the diagnostic to detect fast profile changes. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1147517
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  • 3
    Electronic Resource
    Electronic Resource
    Misfit grainlets: Point strain sources compensating misfit during epitaxial growth (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 952-954 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We propose a misfit relaxation mechanism that may occur during growth in highly misfitting layers. It is based on a misfit compensating distribution of physical point strain sources at the interface between layer and substrate instead of misfit dislocations. These point strain sources are realized by interfacial islands (misfit grainlets) that have a lattice misfit opposite in sign to that of the surrounding epitaxial layer, in most cases brought about by an orientation relationship different from that of the surrounding layer to the substrate. We demonstrate the effectiveness in strain relaxation of misfit grainlets with an analysis of the interface structure of GaN on sapphire and discuss the formation of misfit grainlets in terms of a self-organized island growth process. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.118451
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  • 4
    Electronic Resource
    Electronic Resource
    Surface ripples, crosshatch pattern, and dislocation formation: Cooperating mechanisms in lattice mismatch relaxation (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 1232-1234 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We study the interplay of elastic and plastic strain relaxation of SiGe/Si(001). We show that the formation of crosshatch patterns is the result of a strain relaxation process that essentially consists of four subsequent stages: (i) elastic strain relaxation by surface ripple formation; (ii) nucleation of dislocations at the rim of the substrate followed by dislocation glide and deposition of a misfit dislocation at the interface; (iii) a locally enhanced growth rate at the strain relaxed surface above the misfit dislocations that results in ridge formation. These ridges then form a crosshatch pattern that relax strain elastically. (iv) Preferred nucleation and multiplication of dislocations in the troughs of the crosshatch pattern due to strain concentration. The preferred formation of dislocations again results in locally enhanced growth rates in the trough and thus leads to smoothing of the growth surface. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.115017
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  • 5
    Electronic Resource
    Electronic Resource
    Reduced effective misfit in laterally limited structures such as epitaxial islands (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 574-576 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Numerical finite element calculations have been reported to determine a correction function Φ that describes the reduction of the misfit that occurs when laterally limited structures such as faceted islands or mesa structures are grown on a substrate. The reduction of the average strain energy density is calculated in these three-dimensional islands and compared to the constant strain energy density in a continuous layer. Ratios Φ are obtained from the calculation of different island geometries, i.e., different facet angles γ and different aspect ratios island width l to island height h. These discrete values are fitted by a function which can easily be applied to the full range of aspect ratios (l/h(approximately-greater-than)0) and facet angles (0°〈γ〈90°). Faceted Ge(Si) islands on Si(001) substrate, grown from the solution in the Stranski–Krastanov growth mode, serve as an example for the calculation. Experimental and theoretical values for the critical thickness of these islands agree well. This result demonstrates the drastic influence of islanding on misfit strain distribution in island and substrate as well and, consequently, on the strong increase of the critical thickness as determined by the mechanical equilibrium theory of Matthews and Blakeslee. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114017
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  • 6
    Electronic Resource
    Electronic Resource
    A comparative study of microdosimetric properties of x-rays, γ-rays, and β-rays (1996)
    Springer
    Radiation and environmental biophysics 35 (1996), S. 263-266 
    Details
    ISSN: 1432-2099
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The objective of this study was the computation of microdosimetric functions and quantities for sparsely ionizing radiations. The calculations are performed on simulated electron tracks generated by Monte-Carlo techniques. Ten different radiations of biomedical interest are considered. The comparison of radiation qualities shows marked differences between these sparsely ionizing radiations. The microdosimetric data are represented graphically for use in radiation biology and in clinical applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004110050038
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  • 7
    Electronic Resource
    Electronic Resource
    Consideration on a limit for lifetime occupational radiation exposure (1998)
    Springer
    Radiation and environmental biophysics 37 (1998), S. 81-85 
    Details
    ISSN: 1432-2099
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Annual dose limits in occupational radiation exposure are merely a secondary constraint in addition to the primary rule of dose reduction and justification. The limits may, therefore, be reached only in rare, special cases. However, in principle, there might be cases in which the annual limit is continuously exhausted throughout a working life; a high total dose of 0.8 Sv could then be reached. In view of this possibility, there have been considerations of an added restriction by limiting the lifetime occupational dose to 0.4 Sv. The implications of such lifetime doses are considered, and it is shown that an exposure up to the maximum of 0.8 Sv will lead to the need for compensation, if a leukaemia were to occur in the exposed worker. A lifetime dose of 0.4 Sv equally spread over a working life will not lead to the critical value of the probability of causation in excess of 0.5. Nevertheless, it could cause such critical values when it is accumulated during shorter periods. More decisive than the probabilities of causation are, however, the absolute numbers of excess cases of leukaemia due to the occupational exposure. It is seen that less than one excess case would be expected if a group of 100 workers were all exposed to the maximum of 0.8 Sv. Since lifetime doses of 0.8 or 0.4 Sv will be accumulated in very few cases and only with special justification, there appears to be little need to introduce a further limit of lifetime exposure in addition to the current annual limit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004110050098
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  • 8
    Electronic Resource
    Electronic Resource
    Elektronenmikroskopie und Cytochemie der „Gaucher-Zellen“ bei chronischer Myelose (1972)
    Springer
    Journal of molecular medicine 50 (1972), S. 510-516 
    Details
    ISSN: 1432-1440
    Keywords: Chronic granulocytic leukaemia ; storage cells ; cytochemistry ; electron microscopy ; Leukämie ; chronische ; Myeloische ; Speicherzellen ; Cytochemie ; Elektronenmikroskopie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es konnte cytochemisch und elektronenmikroskopisch nachgewiesen werden, daß es sich bei den sog. Gaucher-Zellen der chronischen Myelose um phagocytierende Reticulumzellen handelt, die in spindelförmigen Einschlußkörpern gespeicherte Glucolipide enthalten. Die gespeicherten Lipide stammen aus den phagocytierten Granulocyten, die in den Reticulumzellen durch lysosomale Enzyme abgebaut werden. Durch den positiven Nachweis der Berliner Blau-Reaktion ist ein Abbau von Erythrocyten oder Erythroblasten in diesen Zellen ebenfalls wahrscheinlich. In elektronenmikroskopischen Hochauflösungsaufnahmen unterscheidet sich das gespeicherte Material von dem in den echten Gaucher-Zellen der erblichen Sphingolipidose. Es besteht nicht aus Tubuli, sondern aus lamellären Systemen dunkler (40 Å) und heller (30 Å) Schichten, die sowohl in der Längsrichtung als auch in der Querrichtung gebogen sind.
    Notes: Summary Cytochemistry and electron microscopy permitted to demonstrate that the so called Gaucher cells in chronic myelogenous leukaemia are phagocytosing reticular cells which contain stored glucolipides in spindle-shaped cytoplasmic sacs. The stored lipids derive from ingested granulocytes destructed in the reticular cells by lysosomal enzymes. Furthermore, Prussian blue staining indicates that the presence of a phagocytosis of erythrocytes or erythroblasts by these cells has to be supposed. High resolution electron microscopy reveals that the stored material differs from that found in storage cells of Gaucher's disease. It does not consist of tubuli but of a lamellar system of dark (40 Å) and light (30 Å) layers, which are curved in the longitudinal as well as in the cross-sectional view.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01487295
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  • 9
    Electronic Resource
    Electronic Resource
    Besonders kleine Megakaryocyten bei chronisch myeloischer Leukämie, akuter Leukämie und Erythroleukämie (1974)
    Springer
    Journal of molecular medicine 52 (1974), S. 649-650 
    Details
    ISSN: 1432-1440
    Keywords: Megakaryocyte ; chronic myelocytic leukemia ; acute leukemia ; erythroleukemia ; Megakaryocyt ; chronisch myeloische Leukämie ; akute Leukämie ; Erythroleukämie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung In vereinzelten Fällen von chronisch myeloischer Leukämie, akuter Leukämie und Erythroleukämie wurden neben „Mikrokaryocyten“ noch kleinere Formen des megakaryocytären Systems unter 300µm2 im Knochenmark und teilweise im Blut gefunden. Mit Fortschreiten dieser Erkrankung nimmt die Anzahl dieser Zellen zu. Dem morphologischen Erscheinungsbild nach kann es sich um Degenerationsformen der „Mikrokaryocyten“ bzw. kleiner Megakaryocyten handeln.
    Notes: Summary Fifteen of 63 cases of chronic myelocytic leukemia, acute leukemia and erythroleukemia showed, in addition to microkaryocytes, another abnormal type of megakaryocytes which were smaller than 300µm2 and of different morphological appearance. These extremely small megakaryocytes appeared in 4 of 15 patients in the peripheral blood. The relative frequency of the cells increased with the progress of the disease. The morphologic appearance suggests that these cells are degenerative forms of microkaryocytes or of small megakaryocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01468802
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  • 10
    Electronic Resource
    Electronic Resource
    Steroidrezeptorstatus und CEA-Nachweis im Serum und Cytosol bei Patientinnen mit Mammakarzinom (1987)
    Springer
    Archives of gynecology and obstetrics 242 (1987), S. 355-356 
    Details
    ISSN: 1432-0711
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Zusammenfassung 1. In dem von uns untersuchten Kollektiv konnten wir keine Korrelation zwischen der CEA-Konzentration im Tumorcytosol und dem Gehalt an Östradiol- und Progesteronrezeptoren nachweisen. ob sich daraus der Schluß ziehen läßt, daß die CEA-Expression von der Intaktheit der Proteinbiosynthesekette unabhängig ist, muß anhand weiterer Untersuchungen überprüft werden. 2. Pathologische Serum-CEA-Spiegel zeigen sich auch in fortgeschrittenen Erkrankungsstadien nur bei Fällen mit erhöhter CEA-Konzentration im Tumorcytosol. Demnach scheint die Validität von CEA-Serumbestimmungen in der Verlaufskontrolle von Tumoren mit geringer CEA-Expression sehr zweifelhaft. 3. In über 40% der Fälle mit erhöhten CEA-Werten im Tumorcytosol fanden sich niedrige CEA-Serumwerte. Neben geringem Tumorvolumen könnten hier unterschiedliche Diffusionsgradienten, Membraneffekte oder verschiedenartige Vaskularisierungsmuster eine Rolle spielen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01783156
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