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  • 1
    ISSN: 0392-6737
    Keywords: Time resolved optical spectroscopies and other ultrafast optical measurements in condensed matter ; Conference proceedings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary The cooling of photoexcited hot carriers in 2D, 1D and 0D systems is studied experimentally. In comparison with a theoretical carrier relaxation model which holds for 2D and 1D systems, it is found that preferably recombination and a weaker electron-LO-phonon interaction dominates the carrier dynamics with decreasing dimensionality. Consequently, we conclude a less dominant role of hotphonon effects in 0D and 1D systems compared to 2D systems.
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 1290-1292 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ion implantation damaging of ordered (Al)GaInP reduces the temperature threshold for thermal disordering from about 850 °C to temperatures below 800 °C, therefore, annealing at 800 °C leads to selective disordering of implanted regions. Dark-field transmission electron microscopy has been used to study the spatial resolution of implantation-induced disordering of CuPtB-ordered GaInP/AlGaInP heterostructures. Lateral order/disorder structures smaller than 200 nm have been realized using implantation masks defined by electron beam lithography. The lateral extension of disordering observed by transmission electron microscopy is in agreement with photoluminescence data and calculations of the lateral implantation straggling. © 1997 American Institute of Physics.
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  • 3
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Room-temperature gain coupled distributed feedback (GC-DFB) lasers have been realized by implantation induced intermixing in the GaAs/AlGaAs material system. The implantation dose has been systematically varied to realize GC-DFB lasers with different gain coupling coefficients due to different band-gap modulation of the active quantum wells. It is demonstrated that a band-gap modulation of 7 meV is sufficient to achieve a high single mode yield at room temperature. The results are discussed on the basis of calculations with the optical matrix theory. © 1995 American Institute of Physics.
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  • 4
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Quantum wires with widths down to 45 nm have been realized by implantation induced intermixing of a surface near GaAs/AlGaAs quantum well. A very steep lateral potential has been achieved together with extreme low damage in the wire regions. As a result the optical transitions in photoluminescence excitation spectroscopy could be observed for all wire widths. With decreasing wire width an increasing Stokes shift has been determined due to the increasing importance of fluctuations in wire dimensions. A weak wire width dependence of transitions near the former two-dimensional light-hole level was observed, which is attributed to the predicted reduced energy shift of states near this level.
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  • 5
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We analyzed the intrinsic defects and the n-type-carrier concentration generated by nitrogen ion implantation in n-type GaN by deep-level-transient spectroscopy and by capacitance–voltage measurements, respectively. The samples were grown on sapphire by metalorganic vapor-phase epitaxy. Nitrogen implantation with different ion doses and postimplantation rapid-thermal annealing (RTA) were investigated. We observed a growing n-type-carrier concentration and increasing defect concentration with increasing nitrogen ion implantation doses. After RTA the concentration of free carriers and deep levels as found in the as-grown state are restored. We also address contrarily seeming results from measurements of sheet resistance after N implantation published recently. © 1996 American Institute of Physics.
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 1042-1052 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this article, a comprehensive treatment of the implantation-induced disordering (IID) of CuPtB-ordered GaInP with regard to microstructuring is presented. Ion implantation reduces the thermal stability of the crystal, so that disordering occurs at temperatures smaller than 800 °C for which the ordered phase normally is stable. It is shown that IID is mediated by implantation defects and can be described quantitatively by a model based on defect annealing. From the temperature dependence of the disordering process an activation energy of 2.15 eV has been evaluated, which is supposed to be the migration enthalpy of group III vacancies. Lateral order/disorder structures were achieved by masked implantation using high resolution electron beam lithography for the definition of wire and dot implantation masks down to 35 nm width. These structures were examined using photoluminescence and transmission electron microscopy. Both methods show that the spatial resolution is determined by implantation straggling, whereas defect diffusion can be neglected. This is also confirmed by extracting the defect diffusion length from the disordering model. © 1997 American Institute of Physics.
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  • 7
    ISSN: 0168-583X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
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  • 8
    ISSN: 1432-0851
    Keywords: Key words p53 serum antibodies ; Prognostic indicator ; Head and neck cancer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract p53 antibodies are a new serological parameter of unknown potential in patients with malignancies. Their occurrence has been described in various types of cancer patients. The mechanism underlying the immunization process is still unclear. We investigated the incidence of p53 serum antibodies in 143 head and neck cancer patients with an enzyme-linked immunosorbent assay. The post-therapy course of two matched study groups (n = 38 each), one p53-antibody-seropositive and one p53-antibody-seronegative, was followed up for 24 months. Thirty-nine head and neck cancer patients (27.3%) were seropositive for p53 antibodies. During the follow-up, the p53-antibody-seropositive patients accounted for more local tumor recurrences (n = 12 versus n = 8) and more tumor-related deaths (n = 11 versus n = 5) than did seronegative patients, and second primary tumors (n = 9 versus n = 0) occurred exclusively in seropositive patients. In total, therapy failures (recurrences, tumor-related deaths, second primaries) were observed in 17/38 cases (44.7%) in the p53-antibody-seropositive group and in 8/38 cases (21.1%) in the p53-antibody-seronegative group. These results, after a follow-up of 2 years, seem to indicate a prognostic value of p53 serum antibodies for therapy failure in patients with head and neck cancer.
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  • 9
    ISSN: 1435-1420
    Keywords: Key words Acute renal failure ; multiple organ dysfunction syndrome ; interhospital transport ; mortality rate ; Schlüsselwörter Akutes Nierenversagen ; Multiorganversagen ; Transport ; Mortalität
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Der Notwendigkeit, auf allen Intensivstationen eine Nierenersatztherapie verfügbar zu haben, steht die Möglichkeit zur Verlegung in spezialisierte Zentren gegenüber. Die vorliegende Studie untersucht die Beeinflussung der Mortalität des Multiorganversagens durch Einführung der Hämofiltration auf dieser Intensivstation gegenüber dem Zwang zur Verlegung in dieser kritischen Phase. Die Daten von 58 Patienten mit akutem Nierenversagen im Rahmen des Multiorganversagens einer anästhesiologisch geleiteten operativen Intensivstation eines kommunalen Krankenhauses wurden retrospektiv ausgewertet. Vor Einführung der Hämofiltration auf dieser Intensivstation im Jahr 1988 mußten 25 Patienten zur Nierenersatztherapie verlegt werden (Gruppe A). Nach 1988 konnten 33 Patienten mit intermittierender veno-venöser Hämofiltration vor Ort behandelt werden (Gruppe B). In Gruppe A war die Mortalität tendenziell höher als in Gruppe B (76% vs 67%). 4 Patienten der Gruppe A verstarben, da für sie trotz Indikation zu einem Nierenersatzverfahren kein Therapieplatz gefunden werden konnte. Bei 3 Patienten gab es zuerst eine Absage, bevor sie dann doch mit Verzögerung in ein anderes Haus verlegt werden konnten; auch diese drei Patienten sind verstorben. Weitere 3 Patienten verstarben innerhalb der ersten 24 Stunden nach Verlegung. Die Indikation zur Nierenersatztherapie im Multiorganversagen war im Untersuchungszeitraum signifikant rückläufig, was auf vielseitige Lerneffekte zurückzuführen ist. Diese Erfahrungen sprechen dafür, in großen Intensivstationen die Möglichkeiten für eine Nierenersatztherapie vor Ort zu schaffen.
    Notes: Summary Renal replacement therapy is of primary importance for the treatment of acute renal failure associated with multiple system organ failure. If renal replacement therapy is not available in the intensive care unit, patients must be transferred to specialized units, where renal replacement therapy can be applied. The present study investigates the mortality of patients in multiple system organ failure with acute renal failure prior and after renal replacement therapy was available in this unit. Data of 58 patients in a multidisciplinary intensive care unit with multiple system organ failure associated with acute renal failure were retrospectively analyzed. Prior to 1988, when hemofiltration was instituted in this unit, 25 patients required an interhospital transmission in order to receive renal replacement therapy (group A). After 1988, 33 patients were treated with intermittent veno-venous hemofiltration in this intensive care unit (group B). Mortality tended to be higher in group A compared to group B (76% vs 67%). In group A four patients died after other units could not admit these patients. Three patients were transferred with considerable delay due to temporary shortage of therapy facilities in other hospitals; these three patients also died. Three patients died within 24 h after interhospital transportation. During the study period the indication for renal replacement therapy in patients with multiple system organ failure decreased, which can be explained with multiple learning effects. Patient groups changed from elderly patients with a lower number of failing organ systems to younger patients with predominantly four failing organ systems. These results favor the provision of renal replacement therapy in every major intensive care unit.
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  • 10
    Publication Date: 2018-03-06
    Description: Centrosome amplification (CA) is common in cancer and can arise by centriole overduplication or by cell doubling events, including the failure of cell division and cell–cell fusion. To assess the relative contributions of these two mechanisms, the number of centrosomes with mature/mother centrioles was examined by immunofluorescence in a tissue microarray of human melanomas and benign nevi ( n = 79 and 17, respectively). The centrosomal protein 170 (CEP170) was used to identify centrosomes with mature centrioles; this is expected to be present in most centrosomes with cell doubling, but on fewer centrosomes with overduplication. Using this method, it was determined that the majority of CA in melanoma can be attributed to centriole overduplication rather than cell doubling events. As Polo-like kinase 4 (PLK4) is the master regulator of centriole duplication, the hypothesis that PLK4 overexpression contributes to centriole overduplication was evaluated. PLK4 is significantly overexpressed in melanoma compared with benign nevi and in a panel of human melanoma cell lines (A375, Hs294T, G361, WM35, WM115, 451Lu, and SK-MEL-28) compared with normal human melanocytes. Interestingly, although PLK4 expression did not correlate with CA in most cases, treatment of melanoma cells with a selective small-molecule PLK4 inhibitor (centrinone B) significantly decreased cell proliferation. The antiproliferative effects of centrinone B were also accompanied by induction of apoptosis. Implications: This study demonstrates that centriole overduplication is the predominant mechanism leading to centrosome amplification in melanoma and that PLK4 should be further evaluated as a potential therapeutic target for melanoma treatment. Mol Cancer Res; 16(3); 517–27. ©2018 AACR .
    Print ISSN: 1541-7786
    Electronic ISSN: 1557-3125
    Topics: Medicine
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