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  • 1995-1999  (13)
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  • 1
    Electronic Resource
    Electronic Resource
    Characterization of electronic states in molecular beam epitaxy grown GaN by optical admittance spectroscopy: Comparison of different nitrogen plasma sources (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 2032-2034 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Optical transitions between the bands and electronic states in n-type GaN layers grown by molecular beam epitaxy on sapphire substrates using an electron cyclotron resonance (ECR) or a radio frequency (rf) nitrogen plasma source were investigated by means of optical admittance spectroscopy. The spectra of all layers similarly consist of a band gap region, a blue and a yellow band, and several defect-to-band transitions. However, in rf grown layers distinct transitions are separable, whereas ECR grown samples reveal broad bands, originating from potential fluctuations due to structural inhomogeneities induced by the ECR source. A defect at 0.82 eV is found characteristic for all ECR samples. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123747
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  • 2
    Electronic Resource
    Electronic Resource
    Interface and bulk defects in SiC/GaN heterostructures characterized using thermal admittance spectroscopy (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 1424-1426 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: SiC/GaN p-n and n-n heterostructures grown by low pressure chemical vapor deposition were investigated using thermal admittance spectroscopy. Different kinds of defects were isolated and located. Evidence of a distribution of defects at the p-SiC/n-GaN interface is given as having thermal activation energies of (87±3) meV at 5 V and (72±4) meV at 8 V bias. Additionally, three bulk defects with activation energies between 155 and 175 meV were found. By comparison with admittance spectra of the p-type SiC substrate, one level was identified as Al acceptor in SiC, whereas the other defects are electron traps in the GaN layer. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123570
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  • 3
    Electronic Resource
    Electronic Resource
    Analysis of deep traps in hexagonal molecular beam epitaxy-grown GaN by admittance spectroscopy (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 2040-2043 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Nominally undoped GaN layers grown by molecular beam epitaxy (MBE) and having resistivities between 105 and 107 Ω were investigated with temperature- and frequency-dependent admittance spectroscopy. The advantage of these measurement methods is shown in terms of the formation of Schottky contacts on high-resistivity GaN layers. The space-charge region, which is needed for detection of deep defects exists at low frequencies only and, therefore, deep level transient spectroscopy (DLTS) measurements fail for this material. Two deep defect levels were identified in MBE-grown GaN layers. The thermal activation energies are (0.45±0.04) and (0.63±0.04) eV, respectively. These deep traps are well known from DLTS and thermal stimulated conductivity measurements in metalorganic vapor phase epitaxy and hydride vapor phase epitaxy-grown GaN. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.368262
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  • 4
    Electronic Resource
    Electronic Resource
    High-spin structure of the neutron-rich 107,109 45Rh isotopes: the role of triaxiality (1999)
    Springer
    The European physical journal 6 (1999), S. 405-413 
    Details
    ISSN: 1434-601X
    Keywords: PACS:21.60.Ev Collective models – 23.20.Lv Gamma transitions and level energies – 25.85.Ge Charged-particle-induced fission – 27.60.+j 90 ≤ A ≤ 149
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. The 107,109Rh nuclei have been produced as fission fragments following the fusion reaction 28Si +176Yb at 145 MeV bombarding energy and studied with the Eurogam2 array. In both nuclei three new rotational bands with the odd proton occupying the πg9/2, πp1/2 and π(g7/2/d5/2) sub-shells have been observed. In 107Rh, two other bands involving strong M1 transitions have been identified at excitation energy larger than 2 MeV. They can be interpreted in terms of three quasiparticle excitations. In addition new structures consisting of four transitions, built on states located at low excitation energy (680 keV in 107Rh and 642 keV in 109Rh), point out the importance of triaxial deformation in these two isotopes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100500050363
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  • 5
    Electronic Resource
    Electronic Resource
    Bases anatomiques de la prévention des hématomes de la paroi abdominale induits par le placement des trocarts (1999)
    Springer
    Surgical and radiologic anatomy 21 (1999), S. 1-2 
    Details
    ISSN: 1279-8517
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Conclusion N'ignorant pas que le choix des sites d'incision pour la chirurgie laparoscopique peut être influencé par une multitude de facteurs, afin de minimiser le risque de lésions des vaisseaux de la paroi abdominale, nous suggérons de placer les trocarts sur la ligne blanche et dans une zone de 5 cm de large en dehors du bord latéral de la gaine du m. droit
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02042023
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  • 6
    Electronic Resource
    Electronic Resource
    Anatomic guidelines for the prevention of abdominal wall hematoma induced by trocar placement (1999)
    Springer
    Surgical and radiologic anatomy 21 (1999), S. 87-89 
    Details
    ISSN: 1279-8517
    Keywords: Inferior epigastric artery ; Endoscopy ; Laparoscopy ; Complication ; Hematoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A knowledge of the parietal structures of the abdominal wall is necessary to minimize risks of operative procedures like laparoscopy. For means to prevent intraoperative bleeding and the occurrence of abdominal wall hematoma, we studied the course of the inferior epigastric arteries and the ascending branch of the deep circumflex iliac artery in 21 human cadavers. The abdominal wall structures were dissected and the distances of the arteries in relation to anatomic structures such as the umbilicus, pubic symphysis, superior ischial spine and lower edge of the rib-cage were measured. Comparison of the morphometric results obtained with the location of 36 trocar incision sites recommended in the common literature yields the information that about half of these incision sites incur the risk of injuring the arteries.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00276-999-0087-9
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  • 7
    Electronic Resource
    Electronic Resource
    Die Bedeutung der Fascia transversalis bei der Inguinalhernien-Reparation mittels total extraperitonealer Plastik (1997)
    Springer
    Der Chirurg 68 (1997), S. 493-495 
    Details
    ISSN: 1433-0385
    Keywords: Key words: Inguinal hernia ; Fascia transversalis ; Endoscopy ; Minimally invasive surgery ; Total extraperitoneal dissection. ; Schlüsselwörter: Leistenhernie ; Fascia transversalis ; Endoskopie ; minimal-invasive Chirurgie ; TEP.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung. Bei der total extraperitonealen endoskopischen Präparation der Leistenhernie (TEP) wird durch Aufblasen eines Ballons im supravesicalen Raum eine künstliche präperitoneale Höhle geschaffen. In einer Studie in vivo und an – gemäß den von Thiel 1992 entwickelten Techniken – spezialfixierten Leichnamen wurde untersucht, in welchem Lageverhältnis zum Ballon sich die Fascia transversalis befindet und was mit ihr beim Aufblasen des Ballons geschieht. In allen analysierten Fällen erwies sich die Fascie medial als adhärent am Peritoneum, lateral an der vorderen Bauchwand, so daß wir systematisch ein Zerreißen der Fascia transversalis längs der Plica umbilicalis lateralis, also der A. epigastrica inferior, beobachten konnten. Bei der TEP kann die Fascie allenfalls lateral der Arterie als Verstärkung der Hinterwand des Leistenkanals oder als Widerlager zum Fixieren vom Fremdmaterial (Netz) genutzt werden.
    Notes: Summary. During total extraperitoneal dissection of inguinal hernias, an artificial preperitoneal cavity is created in the supravesical space by using a balloon dissector. During the operative procedure in vivo and while examining cadavers specially fixated according to the method developed by Thiel in 1992, we investigated the position relative to the balloon the transversalis fascia could be found in and what happened to it during inflation of the balloon. In all cases, the fascia medial to the inferior epigastric arteries was adjacent to the peritoneum and lateral to the abdominal wall. We observed systematic tearing of the fascia along the lateral umbilical plica (inferior epigastric artery). These results suggested that the transversalis fascia could be used only laterally for reinforcement of the dorsal wall of the inguinal canal and/or the support of a mesh used to cover the inguinal floor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001040050218
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  • 8
    Electronic Resource
    Electronic Resource
    Quantitative determination of the contact pressure distribution in the hip joint during gait (1999)
    Springer
    Der Unfallchirurg 102 (1999), S. 625-631 
    Details
    ISSN: 1433-044X
    Keywords: Key words Hip joint • Contact stress • Incongruity • Gait • Joint loading ; Schlüsselwörter Hüftgelenk • Druckverteilung • Inkongruenz • Gang • Gelenkbelastung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Ziel der Untersuchung war die experimentelle Bestimmung der Druckverteilung im Hüftgelenk für charakteristische Phasen des Ganges. Die von Bergmann et al. (1993) mittels telemetrischer Endoprothesen in vivo bestimmten Gelenkkräfte wurden auf Basis kinematischer Ganganalysen in ein beckenbezogenes Koordinatensystem transformiert. An 8 Hüftgelenkpräparaten (Alter 18–75 Jahre) wurden dann während 4 Gangphasen (Fersenkontakt, 1. Kraftmaximum, Ferse vom Boden, Abrollen der Zehen) die Gelenkkräfte eingeleitet und die Druckverteilung mittels FUJI-Druckmeßfolie bestimmt. Wir fanden Maxima von 10 MPa während der mittleren Standbeinphase, die Zonen höchster Druckbelastung waren im ventrosuperioren Anteil des Azetabulums (vorderes Pfannendach) und dorsoinferior (Hinterhorn der Facies lunata) lokalisiert. Die Druckverteilung war während der 4 Phasen relativ konstant, die Größe der Maxima variierte nicht proportional zu den eingeleiteten Kräften. Die normale Druckverteilung im Hüftgelenk wird offensichtlich von der physiologischen Inkongruenz der Gelenkflächen sowie der inhomogenen knöchernen Unterstützung des Azetabulums bestimmt. Bei operativen Maßnahmen im Bereich des Hüftgelenks sollte diese physiologische Druckübertragung möglichst exakt wiederhergestellt werden.
    Notes: Summary The objective of this investigation was the experimental determination of the contact pressures in the hip joint for characteristic phases of the gait cycle. The joint forces determined in vivo with telemetric endoprosthesis by Bergmann et al. (1993) were converted into a pelvic reference system, based on kinematic gait analysis. In eight cadaveric hip joints (age 18–75 yrs.) the reaction forces were applied corresponding to four phases of the gait cycle (heel strike, mid-stance, heel off, toe off) and the pressure distribution determined with FUJI pressure sensitive film. We found maxima of 10 MPa during mid stance. The areas of highest pressure were located in the ventro-superior aspect of the acetabulum (anterior part of the acetabular roof) and in the dorso-inferior aspect of the lunate surface. The pressure distribution was relatively constant during the four phases and the maxima did not vary proportional to the applied load. The normal pressure distribution in the hip appears to be determined by the physiological incongruity of the articular surfaces and the inhomogeneous bony support of the acetabulum. During operative interventions this normal load transfer should be restored as accurately as possible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001130050458
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  • 9
    Electronic Resource
    Electronic Resource
    Das Erlernen und Optimieren minimal-invasiver Operationsverfahren am menschlichen Leichnam (1999)
    Springer
    Der Chirurg 70 (1999), S. 923-928 
    Details
    ISSN: 1433-0385
    Keywords: Key words: Minimally invasive surgery ; Solo surgery ; Clinical anatomy ; Training. ; Schlüsselwörter: Minimal-invasive Chirurgie ; „Solo surgery“ ; klinische Anatomie ; Training.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung. Die expansive Entwicklung minimal-invasiver Operationstechniken bedingt weltweit eine erheblich gesteigerte Nachfrage der operativen Fächer nach Lern-, Lehr- und Forschungsmöglichkeiten an den Körpern verstorbener Menschen in den anatomischen Universitätsinstituten. Die deutschen anatomischen Institute können dieser Nachfrage derzeit nur unzureichend genügen, da die räumliche und technische Infrastruktur für die Bearbeitung derartiger Fragestellungen zwar teilweise noch vorhanden ist, durch die sich wandelnden Forschungsschwerpunkte und die Forderung nach Erfüllung von Lehraufgaben ausschließlich in der Studentenausbildung aber keine freien Personal- und Finanzressourcen für die Lösung von Anwenderproblemen verfügbar sind. Um Planungsgrundlagen für den Aufwand zukünftiger klinisch-anatomischer Arbeiten für Qualitätssicherung, Aus-, Fort- und Weiterbildung bei modernen Interventionen zu schaffen, skizziert der Artikel aus eigener praktischer Erfahrung („ANAtoMIC“) abgeleitete wesentliche Voraussetzungen für derartige Projekte.
    Notes: Summary. The expansion of minimally invasive surgery worldwide provokes an intensive interest of all surgical disciplines in gaining possibilities for research, learning and teaching by operating on human corpses. Despite the fact that German anatomical institutes in general have the infrastructure to realise such clinical cooperations, at present they may offer such opportunities only to a restricted degree, since the concentration on student teaching and anatomic research limits the capacity of the staff for a commitment in this field of applied science. To provide a basis for future estimations of the efforts necessary to perform solo surgery on the human cadaver, especially with emphasis on research, quality control and teaching, this article reports on practical experiences with such a project named “ANAtoMIC”, identifying minimal conditions which have to be realised.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001040050744
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  • 10
    Electronic Resource
    Electronic Resource
    Motion analysis in the context of “whiplash” (1998)
    Springer
    Der Orthopäde 27 (1998), S. 827-833 
    Details
    ISSN: 1433-0431
    Keywords: Key words Motion analysis • Whiplash • Standardisation • Cervical spine • Cost effectiveness ; Schlüsselwörter Bewegungsanalyse • Schleudertrauma • Standardisierung • Halswirbelsäule • Nebenwirkungen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Bewegungsanalyse der Halswirbelsäule (HWS) ist ein sensitives Verfahren der präventiven und klinischen Biomechanik des „Schleudertraumas“. In der präventiven Biomechanik ist es möglich, mit Hilfe der Bewegunganalyse die Biofidelität von Dummy-Versuchen zu verifizieren und zu verbessern. Die klinische Bewegungsanalyse bietet nach wie vor ein uneinheitliches Bild. Meßdaten liegen über Einschränkungen der HWS-Beweglichkeit, Koordinationsstörungen, Gleichgewichtsstörungen, Kiefergelenkfunktion sowie Störungen der Okulomotorik nach Beschleunigungstrauma vor. Eine Vereinheitlichung der technischen und klinischen Untersuchungsbedingungen ist erforderlich, um ein geeignetes biomechanisches Modell des posttraumatischen Zervikalsyndroms [19] zu etablieren. Ohne dieses Modell ist die Bedeutung der Bewegungsanalyse beschränkt, da klinische Sensitivät und Spezifität der Messung empirisch nicht sicher ermittelt werden können.
    Notes: Summary Motion analysis of the cervical spine is a sensitive tool in the fields of preventive and clinical biomechanics of whiplash. In the field of preventive biomechanics motion analysis contributes to validation and optimisation of dummy based crash test experiments and simulations. In the clinical field motion analysis up to now is of restricted value. Data exist about restrictions and pathologies of movement and motion of the cervical spine, coordinative disturbances, postural control, TMJ-function and oculomotor disturbances after whiplash. The standardisation of technical and clinical set-ups is necessary to establish a well proven biomechnical model of whiplash and whiplash related biomechanical dysfunction. Without this model the value of motion analysis for clinical use will be restricted due to lack of comparable data on sensitivity and specificity although motion analysis of the cervical spine is neither cost- nor time consuming and free of adverse effects. Within a prospective series of 28 patients (14 m/ 14 f) with a follow-up to six weeks we were lucky to describe numerically two different types of reaction to low energy (Δv 〈 20 km/h) rear end collision: Type I with disturbances in complex movements only, Type II with overall restriction of movement. Control of angular velocity during cyclic movements of the head was disturbed by oscillations of higher frequency in all patients. Recovery from whiplash within 6 weeks could be monitored.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00003470
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