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  • 1
    Electronic Resource
    Electronic Resource
    Carrier recombination at single dislocations in GaN measured by cathodoluminescence in a transmission electron microscope (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 92 (2002), S. 2000-2005 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We study radiative and nonradiative recombination at individual dislocations in GaN by cathodoluminescence performed in a transmission electron microscope. The dislocations are produced by indentation of dislocation free single crystals and have a-type Burgers vectors (b=1/3〈112¯0〉). They are aligned along 〈112¯0〉 directions in the basal plane. Our direct correlation between structural and optical properties on a microscopic scale yields two main results: (i) 60°-basal plane dislocations show radiative recombination at 2.9 eV; (ii) screw-type basal plane dislocations act as nonradiative recombination centers. We explain the nonradiative recombination by splitting this dislocation into 30° partials that have dangling bonds in the core. The dissociation width of these dislocations is 〈2 nm. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1490618
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  • 2
    Electronic Resource
    Electronic Resource
    Simultaneous experimental evaluation of In and N concentrations in InGaAsN quantum wells (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 3792-3798 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We propose a method that solves the problem of the independent determination of the indium and nitrogen concentrations in a strained quaternary InGaAsN superlattice. The method is experimentally based on the simultaneous measurement: (i) of the tetragonal lattice distortion of the unit cell from high resolution micrographs and (ii) of the intensity of the chemically sensitive (002) reflection from dark field images. As an example, we evaluate InGaAsN quantum wells with a nominal N concentration of 1.7% and with In concentrations of 10%, 20%, or 35%. We reveal local fluctuations of the In and N concentrations over distances down to 4 nm with a sensitivity of 0.1% for N and 1% for In fluctuations in this distance range. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1402139
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  • 3
    Electronic Resource
    Electronic Resource
    Writing of high-density patterned perpendicular media with a conventional longitudinal recording head (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 3409-3411 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have fabricated arrays of magnetic islands in perpendicular CoCrPt media with ∼100 nm lateral dimension using a focused ion beam. A quasistatic write/read tester was used to study aspects of the recording physics of these patterned media. We present results on the variation of the readback signal as the phase of the written square wave changes with respect to the patterned array as a function of island size and write current. Using an analytic near-field expression for head field we are able to model how the observed dependence between phase shift and readback signal as a function of write current arises. This analysis allows us to gain an insight into the role of the island switching field distribution and the write head magnetic field gradient in the patterned media writing process. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1476062
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  • 4
    Electronic Resource
    Electronic Resource
    Anatomical features and histology of the digestive tract of two related neotropical omnivorous fishes (Characiformes; Anostomidae) (2001)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 58 (2001), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The estimated mean intestinal coefficients of Leporinus friderici Bloch, 1794 and L. taeniofasciatus Britski, 1997, from the Upper Tocantins River, central-western Brazil, were 1·25±0·15 and 1·14±0·07, respectively. The external surfaces of the lips have taste buds. The histological structure is composed of four layers: mucosa, submucosa, muscular, and serosa. No muscularis mucosa is detected. The oesophageal epithelium is stratified in L. friderici and pseudostratified in L. taeniofasciatus, the latter with PAS+ basal cells and eosinophilic apical cells. A thick layer of adipose tissue was found within the submucosa. Leporinus taeniofasciatus has a sphincter separating the cardiac and fundic portions of the stomach. In both species, gastric glands are present in the stomach, except in its pyloric portion. The pyloric caeca possess a simple columnar epithelium with brush border and three types of goblet cells. Rodlet cells were found in L. friderici. The three portions of the intestine showed no histological differences. Anatomical and histological features of the digestive tract are consistent with the omnivorous habit of both these species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.2001.tb02261.x
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  • 5
    Electronic Resource
    Electronic Resource
    Plasticity of hematopoietic stem cells and cellular memory (2002)
    Oxford, UK : Munksgaard International Publishers
    Immunological reviews 187 (2002), S. 0 
    Details
    ISSN: 1600-065X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary: Stem cell systems represent an effective and powerful approach for tissue development and regeneration of diverse tissue types. Common and defining features of these exceptional cells are the capacity for self-renewal and the potential for differentiation into multiple mature cell types. Recently, surprising new observations have indicated that stem cells isolated from one adult tissue can also give rise to mature cells of other cell lineages, irrespective of classical germ layer designations. This discovery has resulted in quantum leaps in both scientific knowledge and the potential applications of stem cells. The new findings contradict central dogmas of commitment and differentiation of stem and progenitor cells. However, the true potential of somatic stem cells is just emerging and the new findings have to be defined more fully and integrated into a unifying model of stem cell potential and behavior. Here we analyze the developmental potential of hematopoietic stem cells of mouse and man following their injection into the murine preimplantation blastocyst, an environment that allows the development of all cell lineages. In addition, we discuss the emerging lines of evidence of the developmental plasticity of hematopoietic and other somatic stem cells and consider how cellular memory of transcriptional states is established and may be potentially involved in this phenomenon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1600-065X.2002.18702.x
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  • 6
    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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  • 7
    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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  • 8
    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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  • 9
    Electronic Resource
    Electronic Resource
    Tumormarker im Serum und am Gewebsschnitt bei Mammakarzinom-Patienten (1987)
    Springer
    Archives of gynecology and obstetrics 242 (1987), S. 364-364 
    Details
    ISSN: 1432-0711
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Zusammenfassung Aus den präliminären Ergebnissen dieser Studie ziehen wir für den Einsatz von Tumormarkern im Rahmen der Nachsorge von Mammakarzinom-Patienten die Konsequenz, daß zur seriellen Bestimmung von Tumormarkern im Serum nur die Substanzen eingesetzt werden, für die sich ein positiver immunhistochemischer Nachweis am Primärtumorgewebe führen läßt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01783163
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  • 10
    Electronic Resource
    Electronic Resource
    CEA im Serum und Ascites bei Gesunden und Patienten mit Ovarialkarzinomen (1987)
    Springer
    Archives of gynecology and obstetrics 242 (1987), S. 381-382 
    Details
    ISSN: 1432-0711
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Zusammenfassung Lediglich bei 3/37 Pat. mit Ovarialtumoren fand sich ein pathologisch erhöhter Serum-CEA-Spiegel. In der Peritoneal- bzw. Zystenflüssigkeit konnten dagegen in 14/26 Fällen erhöhte Werte sowohl bei malignen als auch bei benignen Tumoren festgestellt werden. Eine negative serologische CEA-Bestimmung bedeutet daher nicht, daß kein CEA produziert wird. Die Bestimmung des CEA-Gradienten im Serum und in der Peritonealflüssigkeit dürfte eine größere Relevanz zur Verlaufskontrolle bei Ovarialkarzinomen haben.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01783172
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