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  • 2000-2004  (12)
  • 1900-1904  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Closely stacked InAs/GaAs quantum dots grown at low growth rate (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 1544-1546 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a systematic study of closely stacked InAs/GaAs quantum dots (QDs) grown at low growth rates. Transmission electron microscopy reveals that for thin spacer layers vertically aligned QDs merge into one large QD. After capping the initial QD layer the GaAs surface is decorated with well-developed nanostructures, which act as nucleation centers for the QDs deposited in the second layer. Despite the size increase, photoluminescence (PL) experiments show a systematic blueshift up to 103 meV of the QD related signal with decreasing spacer thickness. We explicitly show that this significant blueshift cannot fully be ascribed to specific growth phenomena, but instead is caused by the actual presence of the second dot layer. We report a PL linewidth as narrow as 16 meV at low temperature for a sample with 5 nm spacer thickness. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1456954
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  • 2
    Electronic Resource
    Electronic Resource
    Photoluminescence of ultrasmall Ge quantum dots grown by molecular-beam epitaxy at low temperatures (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 1279-1281 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Low-temperature epitaxial growth of Si–Ge heterostructures opens possibilities for synthesizing very small and abrupt low-dimensional structures due to the low adatom surface mobilities. We present photoluminescence from Ge quantum structures grown by molecular-beam epitaxy at low temperatures which reveals a transition from two-dimensional to three-dimensional growth. Phononless radiative recombination is observed from 〈105〉 faceted Ge quantum dots with height of approximately 0.9 nm and lateral width of 9 nm. Postgrowth annealing reveals a systematic blueshift of the Ge quantum dot's luminescence and a reduction in nonradiative recombination channels. With increasing annealing temperatures Si–Ge intermixing smears out the three-dimensional carrier localization around the dot. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1430508
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  • 3
    Electronic Resource
    Electronic Resource
    Influence of malate and 2-oxoglutarate on the NIA transcript level and nitrate reductase activity in tobacco leaves (2001)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 24 (2001), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Nitrate assimilation in leaves requires synthesis of malate to counteract alkalinization, and synthesis of 2-oxoglutarate to act as an acceptor in the GOGAT pathway. We have investigated whether malate or 2-oxoglutarate regulate nitrate reductase (NIA, EC 1·6.6·1) expression. (i) Diurnal changes of NIA expression and organic acid levels were compared in tobacco leaves. The NIA transcript rose during the night and decreased during the day, and NIA activity rose to a maximum during the first 4 h of the light period and fell during the second part of the light period. Malate accumulated to high levels during the light period and decreased during the night. The 2-oxoglutarate increased by 40% at the beginning and decreased towards the end of the light period. The glutamine : 2-oxoglutarate ratio was steady during the first part of the light period and increased markedly during the second part of the light period. The diurnal changes of the NIA transcript level were inversely correlated to the diurnal changes of malate, and unrelated to the changes of 2-oxoglutarate or the glutamine : 2-oxoglutarate ratio. The decrease of NIA activity in the second part of the light period correlated with an increase of the glutamine : 2-oxoglutarate ratio. (ii) Leaves were detached 4 h into the light period and supplied with malate or 2-oxoglutarate via the petiole, to investigate their impact on the gradual decrease of the NIA transcript and NIA activity during the second part of the light period. Physiologically relevant changes of malate led to a further decrease of the NIA transcript level and a 27–60% decrease of NIA activity. A large increase of 2-oxoglutarate stabilized the NIA transcript level but had only slight effects on NIA activity. (iii) Plants were darkened for 16–24 h to reduce the NIA transcript level and NIA activity to low levels, and leaves were then detached and supplied with malate or 2-oxoglutarate for 4 h in the light to investigate their impact on the light-induction of NIA. The increase of the NIA transcript and NIA activity was antagonized by malate, and slightly accelerated by 2-oxoglutarate. (iv) Plants were placed in the dark for 60 h to reduce NIA activity to the limit of detection, and leaf discs were then incubated in the dark on sucrose to achieve a photosynthesis-independent increase of NIA activity. This was strongly inhibited by malate. (v) It is concluded that malate inhibits NIA expression, affecting both the NIA transcript level and NIA activity. Although the results are consistent with a role for 2-oxoglutarate in the regulation of NIA expression, the impact is less marked and no endogenous changes of 2-oxoglutarate were found that are likely to have a significant effect on NIA expression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.2001.00664.x
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  • 4
    Electronic Resource
    Electronic Resource
    Multi-colour organic light-emitting displays by solution processing (2003)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 421 (2003), S. 829-833 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Organic light-emitting diodes (OLEDs) show promise for applications as high-quality self-emissive displays for portable devices such as cellular phones and personal organizers. Although monochrome operation is sufficient for some applications, the extension to multi-colour devices—such as ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature01390
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  • 5
    Electronic Resource
    Electronic Resource
    Ophthalmodynamometrie Ein zuverlässiges Verfahren zur nicht-invasiven Bestimmung des Hirndrucks (2000)
    Springer
    Der Ophthalmologe 97 (2000), S. 860-862 
    Details
    ISSN: 1433-0423
    Keywords: Schlüsselwörter Ophthalmodynamometrie ; Intrakranieller Druck ; Zentralvenendruck ; Hirndruckmessung ; Keywords Ophthalmodynamometry ; Intracranial pressure ; Central retinal vein pressure ; Intracranial pressure measurement ; Venous outflow pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Background. Central vein pressure depends on intracranial pressure (ICP). Baurmann in 1925 therefore recommended measuring central vein pressure to determine ICP, but the accuracy of this method has not yet been verified. To test the method we measured venous outflow pressure (VOP) by noninvasive ophthalmodynamometry (ODM). Methods and materials. We studied 31 patients with suspected increased ICP. ICP was recorded continuously for a minimum of 24 h by intraventricular catheters, and ODM was performed during ICP measurement. The findings were compared with the results of conventional invasive ICP measurement. Results. Pressure in the central retinal vein was highly correlated with ICP. Conclusion. Measuring VOP by ODM seems to be a reliable method for noninvasive recording of ICP. It is a useful screening test in all cases of presumed ICP elevation.
    Notes: Zusammenfassung Hintergrund. Der Zentralvenendruck ist abhängig vom intrakraniellen Druck. Baurmann empfahl deshalb 1925 die Messung des Zentralvenendrucks, um die Höhe des intrakraniellen Drucks zu bestimmen. Bislang ist diese Überlegung aber noch nicht verifiziert worden. Wir haben den “Venous outflow pressure” (VOP) mittels Ophthalmodynamometrie (ODM) bestimmt und die Befunde mit den Ergebnissen der konventionellen Hirndruckmessung verglichen. Patienten und Methodik. In die Studie wurden 31 Patienten mit Verdacht auf Hirndruckerhöhung aufgenommen. Bei allen Patienten wurde der intrakranielle Druck wenigstens 24 h über einen intraventrikulären Katheter erfasst. Während dieser Zeit erfolgte zusätzlich eine Bestimmung des VOP mittels Ophthalmodynamometrie. Ergebnisse. Der VOP korreliert eng mit dem intrakraniellen Druck. Schlussfolgerung. Die Messung des VOP mittels ODM ist nach den Ergebnissen unserer Studie ein zuverlässiges Verfahren, auf nichtinvasivem Wege den intrakraniellen Druck zu bestimmen, und somit eine geeignete Screeningmethode bei Verdacht auf Hirndruckerhöhung.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003470070009
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  • 6
    Electronic Resource
    Electronic Resource
    Der Neuromentalindex Ein Additivinstrument zum Barthel-Index zur Erfassung von Fähigkeitsstörungen der psychisch-mentalen Grunddimensionen in der Neurorehabilitation (2000)
    Springer
    Der Nervenarzt 71 (2000), S. 963-969 
    Details
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Barthel-Index ; Aktivitäten des täglichen Lebens ; Verhalten ; Kognition ; Mentale Funktion ; Keywords Activities of daily living ; ADL ; Barthel index ; Behaviour ; Cognitive functions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary The Barthel Index (BI) is the most commonly used scale for assessing impairment of activities of daily living (ADL). For a global view of patients' abilities and the care needed in everyday neurorehabilitation practice, additional information about basic psychological and cognitive functions is essential. We therefore designed a new disability scale comprised of assessments of consciousness, approachability, orientation, memory, behaviour, emotions, communication, problem solving, perception, and behaviour at night. The scale shows exactly the same inner structure as the BI, with ten items and a score of up to 20 in steps from 0–100% (or 0–20 points). By a careful weighing of the items, the final score of the neuromental index (NMI) should create a clearer picture of both the disabilities and the needed resources. A second aim was to cover a broad range of patients including those in coma and coma remission states and those with only slight neuropsychological or behavioural symptoms. The NMI was examined with a group of 179 neurorehabilitation inpatients and proved to be highly valid, reliable, and practicable. It was designed to enable a global assessment of disability as well as the care resources needed, even in patients with different disability levels in ADL and psychological and cognitive functions.
    Notes: Zusammenfassung Der Barthel-Index (BI) ist die am weitesten verbreitete Beurteilungsskala für die Aktivitäten des täglichen Lebens. Für die Einschätzung von Fähigkeiten und Betreuungsaufwand im Alltag der Neurorehabilitation sind aber auch Störungen der psychischen und mentalen Grundfunktionen, die durch den BI nicht erfasst werden, von wesentlicher Bedeutung. Wir haben eine Skala erstellt, die Fähigkeitsstörungen in den Bereichen Bewusstsein, Kontaktfähigkeit, Orientierung, Verhalten, Emotion, Kommunikation, Gedächtnis, Problemlösung, Wahrnehmung und Nachtruhe einschließt und die in einer 0–100% Skalierung bzw. der Vergabe von 0–20 Punkten für die 10 Items die exakt gleiche Struktur wie der BI aufweist. Es wurde in der Erstellung der Items darauf Wert gelegt, dass der Summenscore die Fähigkeitsstörungen und den Betreuungsaufwand von komatösen bzw. Komaremissionspatienten (am unteren Skalenende) und Patienten mit geringen Vehaltens- oder neuropsychologischen Störungen (am oberen Skalenende) möglichst wirklichkeitsnahe abbildet. Der Neuromentalindex wurde an 179 Neurorehabilitationspatienten bezüglich seiner Testgütekriterien untersucht und erwies sich als in hohem Maß valide, reliabel und praktikabel.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001150050693
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  • 7
    Electronic Resource
    Electronic Resource
    Modern river discharge and pathways of supplied material in the Eurasian Arctic Ocean: evidence from mineral assemblages and major and minor element distribution (2000)
    Springer
    International journal of earth sciences 89 (2000), S. 486-495 
    Details
    ISSN: 1437-3262
    Keywords: Arctic Ocean Laptev Sea Kara Sea Heavy minerals Clay minerals Chemical elements Sources of sediment Transport pathways of sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract. Clay-mineral, heavy-mineral, and elemental distributions in sediments from the Arctic Ocean and the adjacent Laptev and Kara seas can be attributed to the geology of the hinterland and the transport of terrigenous material by rivers onto the shelves. Kara Sea sediments are characterized by increased contents of smectite and elevated Ni/Al-, Ti/Al-, and Cr/Al ratios. In the western Laptev Sea sediments are enriched in smectite and clinopyroxene and increased in Ti/Al-, Cr/Al-, and Ca/Al ratios. The composition of the sediments reflects suspended matter input from the large trap basalt of the Putoran Mountains. The eastern Laptev Sea sediments display increased illite and amphibole contents as well as a chemical composition similar to average shale. This composition is due to the discharge from the Lena and Yana rivers, which drain a large catchment area consisting of sedimentary Mesozoic and Paleozoic rocks. Material from the eastern Laptev Sea is transported by ocean currents and sediment-laden sea ice along the Transpolar Drift into the central Arctic Ocean. This is indicated by similar values of Ti/Al-, Cr/Al-, Rb/Al-, and K/Al ratios as well as increased concentrations of amphibole and illite, determined in sediments from the Lomonosov Ridge. A minor input from the Beaufort Sea into the central Arctic Ocean is suggested from increased Ca/Al ratios and increased contents of opaque minerals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005310000120
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  • 8
    Electronic Resource
    Electronic Resource
    Transplant activities in Germany in 1998 – a survey facilitated by the National Registry for Hemopoietic Stem Cell Transplantation (2000)
    Springer
    Annals of hematology 79 (2000), S. 437-443 
    Details
    ISSN: 1432-0584
    Keywords: Key words Blood stem cell transplantation ; Data management quality control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  To improve the infrastructure of hemopoietic stem-cell transplantations in our country, the German Registry for Hemopoietic Stem-Cell Transplantations (DRST) was established in 1998. The present paper summarizes the current status of the DRST and gives a survey of transplant activities in Germany in 1998 in terms of transplant units, transplant types, transplant frequencies and underlying diseases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002770000194
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  • 9
    Electronic Resource
    Electronic Resource
    3-Methylglutaconyl-CoA hydratase deficiency: A new patient with speech retardation as the leading sign (2000)
    Springer
    Journal of inherited metabolic disease 23 (2000), S. 341-344 
    Details
    ISSN: 1573-2665
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005670911799
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  • 10
    Electronic Resource
    Electronic Resource
    Endosonographic examination of gastrointestinal anastomoses with suspected locoregional tumor recurrence (2000)
    Springer
    Surgical endoscopy and other interventional techniques 14 (2000), S. 45-50 
    Details
    ISSN: 1432-2218
    Keywords: Key words: Endosonography — Gastrointestinal tract carcinoma — Locoregional tumor recurrence — Anastomosis — Cancer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Endoscopic ultrasound is considered one of the best tools for the preoperative staging of esophageal, gastric, and rectal carcinoma. Depending on the individual investigator, the sensitivity of preoperative tumor staging by endosonography of the upper gastrointestinal tract (GEUS) is 80–92% for gastric carcinoma and 86–95% for esophageal carcinoma. However, the sensitivity and specificity of endosonography for the staging of lymph node metastases is less accurate. The accuracy of rectal endosonography (REUS) is ∼90% for tumor assessment and ∼80% for the detection of lymph node metastases. In this study, we address the question of whether endosonography enables the surgeon to distinguish scar tissue, which is rather homogeneous and echo-rich, from changes such as an anastomositis or a locoregional tumor recurrence, which are typically noninhomogeneous and echo-poor. Methods: During a 24-months period, we studied patients enrolled in a special tumor follow-up care program by either upper gastrointestinal (GEUS, n= 37 patients) or rectal endosonography (REUS, n= 49 patients) for exclusion of a locoregional tumor recurrence. In each patient, local tumor recurrence was suspected because of either medical history, clinical examination, or other diagnostic procedures. Results: As in previous studies, our retrospective analysis revealed that endosonography has a high sensitivity in the detection of local tumor recurrences (〉90%) for both GEUS and REUS. Conclusion: Endosonography is a highly accurate means of detecting local tumor recurrence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004649900009
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