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  • 1
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Al0.5In0.5P/Ga0.5In0.5P superlattice structures have been investigated as multiquantum barriers (MQB) in 630 nm band laser diodes in order to reduce thermal current losses. By inserting an optimized MQB, we have succeeded in improving both threshold currents and characteristic temperatures of such devices. However, the optimized dimensions of the MQB found experimentally deviated strongly from those predicted theoretically, indicating that the commonly used theoretical description assuming effective mass approximation, electron wave interference, and using transfer matrix calculation is not adequate. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Journal of clinical periodontology 31 (2004), S. 0 
    ISSN: 1600-051X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Aim: Zygomatic implants have been introduced for the rehabilitation of patients with severe bone defects of the maxilla. The soft tissue aspects of the palatal emergence situation have not been described yet. The aim of this study was to evaluate the incidence and clinical impact of possible periimplant alterations of zygomatic implants.Materials and methods: From 1998 to 2001 all patients with zygomatic implants were included into this study (24 patients, 37 zygomatic implants). One implant was lost in the loading phase giving a survival rate of 97%. Fourteen patients with 20 zygomatic implants fulfilled the inclusion criteria and were all available for the recall examination. Thirteen zygomatic implants were inserted in cases of severe maxillary atrophy, seven in cases of tumour-resection of the maxilla. Clinical examination and microbial analysis using a DNA probe was performed. The implants had a mean time in situ of 598 days (min: 326, max: 914).Results: Colonisation with periodontal pathogens was found at four of the 20 implants. A positive microbiologic result of the periimplant pocket and the maximum pocket probing depth were not statistically related. Nine of the 20 implants showed bleeding on probing, four of these had positive microbiologic results. At sites without bleeding on probing only negative microbiologic samples were found (p=0.026). The mean palatal and mesial probing depth was 1 mm deeper than at the vestibular and distal aspect. Thus at nine out of the 20 implants both, bleeding on probing and pocket probing depth 〈inlineGraphic alt="geqslant R: gt-or-equal, slanted" extraInfo="nonStandardEntity" href="urn:x-wiley:03036979:JCPE505:ges" location="ges.gif"/〉5 mm indicated soft tissue problems resulting in a success rate of only 55%. The patient's history (tumor versus atrophy) or smoking habits seemed not to have influence the situation.Conclusion: These soft tissue problems should be taken into account if zygomatic implants are considered as an alternative therapy option in the maxilla.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1433-0458
    Keywords: Schlüsselwörter Fetale Chirurgie ; Kopf-Hals-Chirurgie ; Fetendo ; Endoskop ; Kongenitale Zwerchfellhernie ; Larynxatresie ; Lippen-Kiefer-Gaumen-Spalte ; Fetale Wundheilung ; Key words Fetal endoscopic surgery ; Head and neck surgery ; Congenital diaphragmatic hernia ; Laryngeal atresia ; Cleft lip and palate ; Fetal wound healing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Fetal surgery is defined as the intrauterine surgical correction of malformations that endanger the unborn child’s life in prenatal stages of development or lead to death or severe damage of the child postnatally. Such surgery is a clinical reality now. Indications for intrataurine surgical procedures also exist for head and neck abnormalities, especially in the upper respiratory tract. These include exposure and temporary obstruction of the fetal trachea for correction of pulmonary hypoplasia in cases with congenital diaphragmatic hernias, prenatal tracheotomy in cases of laryngeal atresia for the correction of lethal pulmonary overdistension, and resection of embryonic tumors that obstruct the respiratory tract. The relatively high surgical risk resulting in particular from preterm labor occurring postoperatively may be reduced by employing minimally invasive techniques. Endoscopic procedures render opening of the uterus unnecessary and are of particular importance. In part of the procedures, only endoscopic surgery has led to therapeutic success rates justifying its clinical use. Further reduction of the operative risk suggests prenatal interventions, even in cases with non-lethal conditions. More diseases of the head and neck may thus be included in the spectrum of indications. One example is prenatal correction of a cleft lip and palate, which until now has only been performed in animal experiments. The particular characteristics of fetal wound healing allow this to take place without scarring up to a certain stage in pregnancy. This offers the prospect of a surgical correction that is invisible externally and avoids growth-impeding scars. The particular ethical and legal aspects of fetal surgery are discussed.
    Notes: Zusammenfassung Fetale Chirurgie bedeutet die Durchführung von operativen Eingriffen am Ungeborenen mit dem Ziel der intrauterinen Korrektur von Mißbildungen, die das Leben des Kindes bereits pränatal gefährden oder die postnatal den Tod oder eine schwere Schädigung des Kindes zur Folge haben. Auch im Kopf-Hals-Gebiet, insbesondere im Bereich der oberen Luftwege, gibt es bereits Indikationen für fetale Eingriffe. Diese umfassen die Darstellung und vorübergehende Obstruktion der fetalen Trachea zur Rückführung der pulmonalen Hypoplasie bei kongenitaler Zwerchfellhernie, die pränatale Tracheotomie bei Larynxatresie zur Rückführung einer letalen Lungenüberblähung und die Resektion embryonaler atemwegsobstruierender Tumore. Das relativ hohe Operationsrisiko, daß sich vor allem aus den postoperativ regelmäßig auftretenden vorzeitigen Wehen ergibt, läßt sich durch den Einsatz minimal-invasiver Techniken verringern. Endoskopischen Verfahren, die die langstreckige Eröffnung des Uterus überflüssig machen, kommt dabei eine besondere Rolle zu. Bei einem Teil der Eingriffe führte erst die endoskopische Durchführung zu therapeutischen Erfolgsquoten, die eine klinische Etablierung rechtfertigen. Durch weitere Risikominimierung könnten Nutzen und Risiko eines pränatalen Eingriffs auch bei nicht lebensbedrohlichen Mißbildungen in einem verantwortbaren Verhältnis stehen und damit weitere Erkrankungen aus dem Kopf-Hals-Bereich in das Indikationsspektrum rücken. Ein Beispiel für eine solche, bisher nur im Tierversuch etablierte Option ist die pränatale Korrektur der Lippen-Kiefer-Gaumen-Spalte. Durch die besonderen Eigenschaften der fetalen Wundheilung, die bis zu einem bestimmten Schwangerschaftsabschnitt narbenfrei abläuft, böte sich die Perspektive einer äußerlich unsichtbaren Korrektur und fehlenden wachstumshemmenden Narbenzügen. Ergänzend wird auf die besonderen ethischen und rechtlichen Aspekte der fetalen Chirurgie eingegangen.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1434-3940
    Keywords: Schlüsselwörter Mundhöhlenkarzinom Prognosefaktoren ; Unterkieferresektion ; Strahlentherapie ; Keywords Oral carcinoma ; Prognostic factors ; Mandibular resection ; Radiotherapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract The prognostic effect of bone resection (continuous vs non-continuous) was analysed in a retrospective study of 100 patients who were treated for squamous cell carcinoma located close to the lower jaw, between 1983 and 1994. Tumour stage, type of bone resection, extent of lymphatic node resection, dose of radiotherapy and chemotherapy were documented. Prognosis was characterised by the statistical end points “death”, “metastasis” and “relapse”. Thirty-two stage pT2 carcinomas, half of which were treated by continuous and half by non-continuous resection of the lower jaw, showed the same occurrence of the statistical end points death, metastasis or relapse. There was a trend towards a significantly longer survival time and metastasis-free interval in the group of continuous resection. The hazard ratios, however, showed no effect depending on the type of resection. However, both tumour stage (pTNM) and dose of radiation independently influenced prognosis in multivariate analysis. Consequently, three groups were defined. Univariate analysis of 62 patients without radiotherapy vs 19 with low-dose radiotherapy (36 Gy) and 19 with high-dose (62 Gy) showed a positive effect on the rate and time of survival in the group treated with high-dose radiotherapy. This was confirmed by multivariate analysis showing significantly lower hazard ratios for death and metastasis in the high-dose radiotherapy group after adjusting to cofactors (e.g. tumour stage). The data of this study challenge the current concept of resection of the lower jaw. However, due to the low number of patients and the retrospective character of the study, it is not possible to give suggestions regarding established therapy concepts. The advances of a high-dose radiotherapy in this study should be the subject of further multicentre retrospective and prospective randomised trials.
    Notes: Zusammenfassung Durch die retrospektive Auswertung von 100 Patienten mit unterkiefernahen Karzinomen (1983–1994) sollte eruiert werden, inwieweit die Art der Unterkieferresektion (Kasten- vs. Kontinuitätsresektion) den Erkrankungsverlauf prognostisch beeinflusst. Als potenziell prognosebeeinflussende Parameter wurden das Tumorstadium, der Unterkieferresektionsmodus, der Umfang der Lymphknotendissektion, die Strahlentherapiedosis und die Chemotherapie einbezogen. Zur Prognosebewertung dienten die Endpunkte „Versterben“, „Metastase“ und „Rezidiv“. 32 pT2-Karzinome, die jeweils zur Hälfte kasten- bzw. kontinuitätsreseziert wurden, zeigten bezüglich der Endpunkte „Versterben“, „Metastase“ und „Rezidiv“ gleiche Ereignisquoten. Überlebenszeiten und Metastasenfreiheitszeiten (Kaplan-Meier) verwiesen univariat auf einen tendenziellen Vorteil der Kontinuitätsresektion. Die relativen Risiken ergaben dagegen keinen Hinweis auf einen relevanten Effekt der Resektionsform. Da sich in ¶der multivariaten Analyse neben dem pTNM-Stadium die Bestrahlungsdosis als unabhängiger Prognosefaktor präsentierte, wurden hierzu zusätzlich ¶3 Gruppen gebildet. Der Vergleich von 62 nicht strahlentherapierten Patienten gegenüber 19 niedrig dosiert ¶(36 Gy) und 19 hoch dosiert (63 Gy) Bestrahlten zeigte univariat in den Überlebenszeiten einen Vorteil nach Ausbestrahlung. Dieser Vorteil wurde multivariat durch ein signifikant geringeres relatives Risiko für „Versterben“ und „Metastase“ nach Ausbestrahlung bestätigt. Die diskordante Datenlage der Studie zur Unterkieferresektion ist keine verlässliche Basis, eine Therapieempfehlung zu stützen, die vom etablierten Konzept abweicht. Bei aller Zurückhaltung aufgrund der retrospektiven und monozentrischen Ergebniseruierung kann aber ein Hinweis auf einen möglichen relevanten Prognosevorteil durch eine hochdosierte, adjuvante Bestrahlung abgeleitet werden, der multizentrisch retrospektiv und ggf. in prospektiven, randomisierten Studien geprüft werden sollte.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Mund-, Kiefer- und Gesichtschirurgie 4 (2000), S. 309-314 
    ISSN: 1434-3940
    Keywords: Schlüsselwörter Odontogene Zyste ; Laterale parodontale Zyste ; Botryoide odontogene Zyste ; Kieferzyste ; Zytokeratine ; Keywords Odontogenic cyst ; Lateral periodontal cyst ; Botryoid odontogenic cyst ; Jaw cyst ; Cytokeratins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract The botryoid odontogenic cyst (BOC) is considered a rare multilocular variant of the lateral periodontal cyst. The origin of the BOC can be seen in aberrant odontogenic tissue. The BOC is found especially in the premolar region of the mandible, as well as in the frontal region of the maxilla of patients aged between 60 and 70 years. Most of the 11 published articles of BOC have shown high rates of recurrence. Histopathologically the BOC is marked by multilocular cysts lined by a thin, nonkeratinized epithelium. Clusters of glycogen-rich epithelial cells may be noted in nodular thickenings of the cyst lining. For the clinician, the differentiation of the BOC from the keratocyst and ameloblastoma is ¶relevant. One case of a large BOC (65-year-old male, BOC regio 33–45, diameter 5 cm, radiographically and histologically multilocular) is presented with a review of the literature, including the therapeutic management, and the possible diagnostic criteria are discussed. The immunohistochemically determined expression of cytokeratin (CK) 13 implicates the histogenetic origin of the BOC from the squamous epithelium of the oral cavity and excludes the origin from the small salivary glands. The expression of CK 19 and the lack of expression of p53, as well as the higher proliferation rate of the basal epithelial cell layer by the BOC, may be useful for distinction between the keratocyst.
    Notes: Zusammenfassung Die botryoide odontogene Zyste (BOC) ist eine seltene multilokuläre Variante der lateralen parodontalen Zyste. Sie entsteht aus versprengten odontogenen Zellanteilen. Die BOC tritt besonders häufig im Prämolarenbereich des Unterkiefers und im anterioren Oberkiefer bei Patienten zwischen der 6. und 7. Lebensdekade auf. Unter den bisher publizierten 11 Arbeiten zeigt sich eine hohe Rezidivhäufigkeit. Histologisch ist die BOC durch multilokuläre Zysten mit einem isomorphen Epithel gekennzeichnet. Dieses zeigt fokale plaqueähnliche Verdickungen durch Gruppierungen glykogenreicher Plattenepithelzellen. Für den Kliniker ist die Abgrenzung zur Keratozyste bzw. zum Ameloblastom differentialdiagnostisch bedeutsam. Ein Zufallsbefund einer besonders großen BOC (65 Jahre, männlich, BOC-Regio 33–45, 5 cm Durchmesser, radiologisch und histologisch multilokulär) wird inklusive therapeutischem Vorgehen und Literaturübersicht vorgestellt, mögliche Diagnosekriterien werden diskutiert. Der immunhistochemische Nachweis der Expression von CK13 impliziert eine histogenetische Ableitung der BOC vom oralen Plattenepithel und spricht gegen eine Ableitung von den Speicheldrüsen. Die Expression von CK19 und die fehlende Expression des p53 sowie die hohe Proliferation in der Basalzellschicht durch die BOC können zur Abgrenzung von der Keratozyste benutzt werden.
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  • 6
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 33 (2000), S. 451-455 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Magnetic small-angle neutron scattering experiments were performed on nanostructured Fe, Co and Ni samples of varying grain size, produced by inert-gas condensation. The experiments show that the spontaneous spatial magnetic correlations forming in zero-field extend over many individual grains. These correlations depend strongly on grain size. In Fe, they have a minimum at a grain size of around 35 nm and increase sharply for smaller grain sizes. The crossover occurs at grain sizes comparable with Lcrit = πδ, where δ is the bulk domain-wall width. For grain sizes below Lcrit, the results are explained on the basis of the random-anisotropy model, which takes into account that the magnetic alignment between the grains competes with the anisotropies of the individual grains. Above Lcrit, where domain walls can form within one grain, the magnetization direction corresponds to the anisotropy direction varying from grain to grain, and the magnetic correlation length increases approximately linearly with grain size. Furthermore, the measurements on Fe, Co and Ni show that the spatial magnetic correlations measured by SANS are always larger than Lcrit. This is in agreement with results of theoretical studies showing that nonuniform magnetization configurations can only exist in grains with sizes D 〉 Lcrit.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 33 (2000), S. 804-806 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: With the start-up of the neutron spallation source SINQ at PSI an instrument for small angle neutron scattering became operational and is open for the user community. The instrument is equipped with state-of-the-art components and compares well with the world's largest and most powerful facilities of this kind. Great emphasis was put on providing a flexible, universal multi-user facility which guaranties a comfortable and reliable operation. In the present paper, the layout of the instrument is presented, the main components are described, and the performance is illustrated by selected examples
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 207-209 (Feb. 1996), p. 365-368 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 225-227 (July 1996), p. 745-750 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 235-238 (Oct. 1996), p. 699-704 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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