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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 6871-6876 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on a novel experimental setup using a miniature integrating sphere fitted into a cryostat to measure spectrally resolved the absolute external photoluminescence quantum efficiency ηlum in the temperature range from 6 K to beyond room temperature. Direct access to ηlum is achieved by an uncomplicated method to calibrate the spatially integrated emission spectra absolutely. The fraction of light coupled out of the sphere into the detection system is in good approximation independent of the emitted wavelength and the emission characteristics of the investigated samples, due to their smallness compared with the total sphere area. This fact is proved by theoretical calculations for the sphere throughput and the irradiance within the sphere. To demonstrate the capabilities of this setup, we investigate in high quality ZnSe/ZnMgSSe 10× multiple quantum wells, the temperature dependence of the quantum efficiency, simultaneously for the quantum well and the barrier luminescence. Within a thermal activation model, three processes are found to contribute to the thermal quenching of ηlum of the quantum well luminescence. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Dental traumatology 15 (1999), S. 0 
    ISSN: 1600-0595
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— The aim of this study was to evaluate the mechanical and physical properties of several standard size commercially available mouthguards. For the purpose of objective testing, a special study model, which the various gum shield devices could be fitted onto, was developed to record tooth deflection caused by impact forces induced by a pendulum ram impact testing machine. The data measured on teeth provided with various gum shield devices were correlated with those of unprotected teeth; this enabled the individual cushioning effects of the respective devices and their specific force conduction to be evaluated. Using mouthguards considerably diminishes the deflection of the teeth subjected to stress in comparison with the row of unprotected teeth. In addition, force is transmitted to the adjacent teeth all the way to the distal regions of the row of teeth. The individual cushioning effects are directly correlated to the thickness of the material; the force distribution is determined by the rigidity of the gum shield device. The devices examined showed considerable differences with regard to force distribution and dimensioning. The study showed that this was due to the thickness of the materials, the manufacturing process and the composition of the materials of the devices examined. In comparison to laboratory-produced devices of similar material thickness, the devices that were designed to be fitted by the user achieved significantly poorer results as regards both cushioning properties and dissipation of exerted forces.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1939
    Keywords: Key words Insect herbivory ; Host-plant density ; Perennial weed ; Biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper contributes to the relatively sparse literature on the effects of insect herbivory on the population dynamics of plants and is probably unique in that it reports the long-term effects of combinations of three insect herbivore species on the population densities of a moderately long-lived tree species. The tree is Sesbania punicea, a leguminous perennial from South America that has been the target of a biological control programme in South Africa for almost 20 years. Sixteen infestations of the weed have been monitored for periods of up to 10 years to determine changes in the density of the mature, reproductive plants under the influence of different combinations of three biological control agents (i.e. with one, two or three of the agent species present in the weed infestation). The three biological control agents, all weevil species, include Trichapion lativentre, which primarily destroys the flower-buds, Rhyssomatus marginatus, which destroys the developing seeds, and Neodiplogrammus quadrivittatus, whose larvae bore into the trunk and stems of the plants. While T. lativentre occurs throughout the range of the weed in South Africa, the other two species are less mobile, more recent introductions and are largely confined to the vicinity of selected release sites. There has been a significant decline in the density of mature S. punicea in areas where two or more of the agents are established. The decline of the weed has been most evident where N. quadrivittatus is active and particularly so where both of the other two weevil species are also present.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Der Chirurg 70 (1999), S. 265-269 
    ISSN: 1433-0385
    Keywords: Key words: Basal cell carcinoma ; Micrographic surgery ; Recurrence rate ; Reconstruction. ; Schlüsselwörter: Basaliom ; mikrographische Chirurgie ; Rezidivrate ; plastische Deckung.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung. Aus dem Patientengut der Klinik und Poliklinik für Mund-, Kiefer- und Gesichtschirurgie des Universitätsklinikums Tübingen wurden die Daten von 673 Patienten mit 1301 Basaliomen, welche im Zeitraum von 1977 bis 1992 behandelt wurden, retrospektiv katamnestisch analysiert. Klinisch-morphologische und therapeutische Kriterien, wie Tumorlokalisation und -ausdehnung, spezifische Vorbehandlungen, Histopathologie, Art und Weise der Tumorablation sowie der jeweils verwendeten plastisch-rekonstruktiven Maßnahmen wurden im einzelnen analysiert. Durch Einsatz der mikrographischen Chirurgie können die Gewebedefekte, speziell in den Problemzonen des Augen- und Nasenbereiches, kleinstmöglich gehalten werden. Damit werden günstige Voraussetzungen für die anschließende plastisch-rekonstruktive Defektdeckung und eine höchstmögliche Sicherheit für die Tumorfreiheit des angrenzenden Gewebes geschaffen. Die Daten von Patienten mit Basaliomrezidiven wurden in Korrelation mit den jeweiligen Untersuchungsergebnissen von Patienten mit primärer Tumormanifestation dargestellt. Als besonders bedeutend zeigte sich hierbei der Vergleich der jeweiligen Tumorlokalisationen sowie der histopathologischen Subdifferenzierung. Durch die Ergebnisse unserer Untersuchung konnte bestätigt werden, daß nach wie vor die chirurgische Excision des Basalioms, mit ausreichendem Sicherheitsabstand und histopathologischer Tumor- und Schnittrandkontrolle, die Therapie der Wahl ist.
    Notes: Summary. The present investigation reviews the history of 673 patients having undergone surgical treatment for 1301 BCC of the face between 1977 and 1992 at our department. Based on this series the features with bearing on the surgical strategy, such as type, size and location of the lesions, will be outlined. Emphasis is put on the variants of local flap reconstruction and skin grafting techniques, particularly in the problem zones of the nose and eyelids, where no excess skin for closure of the defect is available. Throughout the whole series histologic control of the adequacy of marginal and deep tumor resection was performed. It became obvious that the required ranges for clearance to tumor edges and removal in depth cannot be predefined arbitrarily or on pure clinical judgement. Frequently a two-stage procedure of resection and repair will be necessitated. Recurrences during the mandatory follow-up were thoroughly reassessed to identify the reason for failure (e. g. accuracy of histologic category, multifocal growth, predisposition) and related to the time span from primary excision. Our series confirms that morphologically controlled surgical excision of the BCC of the face and subsequent application of reconstructive techniques produces both safe oncologic and esthetic results.
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  • 5
    ISSN: 1434-3940
    Keywords: Schlüsselwörter Sekundäre Orbitarekonstruktionen ; Alloplastische Materialien ; Stereolithographie ; Präoperative Therapieplanung ; Computergestützte Herstellung ; Key words Secondary orbital reconstruction ; Stereolithography ; Craniofacial prostheses ; Computer-aided manufacturing ; Alloplastic materials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary The use of autogenous transplants and the application of intraoperatively customised alloplastic materials show, in cases of secondary orbital reconstruction, a higher postoperative morbidity caused by additional approaches to the transplant donor site. On the other hand, thorough surgical exploration and fitting of the transplants or alloplastic materials greatly prolongs operating times. For these reasons we designed ceramic implants (Bioverit) on the basis of stereolithography models and prefabricated them using a commercially available dental copy milling unit (Celay). In five cases up until now seven customised implants have been inserted for reconstruction of the lamina papyracea, zygomatic complex and infraorbital floor and rim. Encouraged by the good postoperative aesthetic and functional results, with significantly reduced operating times and morbidity in all cases, we will continue to take this technique into account for reconstruction after complex orbital fractures.
    Notes: Zusammenfassung Sowohl die Verwendung autologer Transplantate als auch der Einsatz alloplastischer Materialien zeigen bei der Rekonstruktion der knöchernen Orbita Nachteile, die sich im wesentlichen durch die zusätzliche Entnahmemorbidität, aber auch durch verlängerte Operationszeiten ergeben. Aus diesem Grund haben wir bei ausgesuchten Fällen mit extremer Bulbusdystopie traumatischer oder kongenitaler Genese Bioveritglaskeramikimplantate auf der Basis von Stereolithographiemodellen hergestellt. Bei 5 Patienten wurden bislang insgesamt 7 Keramikimplantate im Orbitabereich inseriert, die jeweils komplikationslos einheilten und nach subjektiver und objektiver Beurteilung eine deutliche funktionelle und ästhetische Verbesserung ergaben. Damit zeigt sich hier eine Alternative zu konventionellen rekonstruktiven Verfahren, da trotz des hohen Material- und Personalaufwands dieser Technik bei nur kurzer stationärer Behandlungsdauer eine frühe Rehabilitation der betroffenen Patienten erfolgen kann.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1420-908X
    Keywords: Key words: Anticoagulants — Interleukins — Tumor necrosis factor assay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Objective and Design: Unfractionated heparin is frequently used as an anticoagulant during blood sampling and in cell culture experiments. In the present study we investigated whether heparin and other anticoagulants (citrate and EDTA) interfered with measurements of plasma tumor necrosis factor alpha (TNFα) concentrations or with TNFα release from endotoxin-stimulated monocytes.¶Material and Methods: TNFα was measured by a WEHI 164 bioassay in the plasma of 16 septic patients anticoagulated with heparin, citrate, or EDTA. Anticoagulants were incubated with the bioassay cell line and cell lysis was monitored. To exclude falsely low TNFα concentrations, anticoagulants were incubated in increasing amounts with human recombinant TNFα/saline solution, and rTNFα recovery was measured either with the WEHI 164 bioassay or an ELISA test. Further, anticoagulants were incubated with monocytes isolated from healthy volunteers and stimulated with endotoxin. Supernatants were analyzed for TNFα with both test systems.¶Results: No biologically active TNFα was detected in the plasma with heparin anticoagulation, whereas with citrate, reproducible, TNFα-induced cytotoxicity was detectable in blood samples of 13 of the 16 patients. Anticoagulation with EDTA resulted in fairly high, variable and poorly reproducible TNFα values. Only EDTA produced falsely high values by unspecific lysis of WEHI cells. Only heparin at a concentration of 20 I.U./ml or more was found to produce falsely low values by interaction with the TNFα bioassay, but also with the ELISA test. In monocyte culture experiments, heparin significantly attenuated the stimulatory effect of endotoxin on TNFα release already at the lowest concentration tested (25 I.U./ml).¶Conclusions: Heparin and EDTA may have significant adverse effects on TNFα measurement when used for blood sampling. Citrate does not interfere with the TNFα bioassay or ELISA, and seems, therefore, to be the anticoagulant of choice. Due to intrinsic interactions with various cell systems (including the WEHI cell and monocytes), one should be careful in using heparin in cell culture studies in which effects of TNFα or of endotoxin are being studied.
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  • 7
    ISSN: 1432-0630
    Keywords: PACS79.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract. Strained layer GaAs $_{.95}$ P $_{.05}$ photo cathodes are presented, which emit electron beams spinpolarized to a degree of P = 75% typically. Quantum yields around QE = 0.4% are observed routinely. The figure of merit P $^2 \times $ QE = 2.3 $\times 10^{-3}$ is comparable to that of the best strained layer cathodes reported in literature. The optimum wavelength of irradiating light around $830\;{\rm nm}$ is in convenient reach of Ti:sapphire lasers or diode lasers respectively. The cathodes are produced using MOCVD-techniques. AaAs $_{.55}$ P $_{.45}$ –GaAs $_{.85}$ P $_{.15}$ superlattice structure prevents the migration of dislocations from the substrate and bottom layers to the strained overlayer. The surface is protected by anarsenic layer so that no chemical cleaning is necessary before installation into vacuum. The source of polarized electrons attached to the Mainz race track microtron MAMI works with such cathodes now. More than 1000 hours beamtime have been performed successfully.
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  • 8
    ISSN: 1432-0630
    Keywords: 79.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Strained layer GaAs.95P.05 photo cathodes are presented, which emit electron beams spinpolarized to a degree of P = 75% typically. Quantum yields around QE = 0.4% are observed routinely. The figure of merit P2 × QE = 2.3 × 10−3 is comparable to that of the best strained layer cathodes reported in literature. The optimum wavelength of irradiating light around 830 nm is in convenient reach of Ti:sapphire lasers or diode lasers respectively. The cathodes are produced using MOCVD-techniques. A GaAs.55P.45-GaAs.85P.15 superlattice structure prevents the migration of dislocations from the substrate and bottom layers to the strained overlayer. The surface is protected by an arsenic layer so that no chemical cleaning is necessary before installation into vacuum. The source of polarized electrons attached to the Mainz race track microtron MAMI works with such cathodes now. More than 1000 hours beamtime have been performed successfully.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 51 (1997), S. 421-425 
    ISSN: 1432-1041
    Keywords: Key words Warfarin ; Meloxicam ; interaction ; pharmacokinetics ; protein binding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: The effect of multiple oral doses of meloxicam 15 mg on the pharmacodynamics and pharmacokinetics of warfarin was investigated in healthy male volunteers. Warfarin was administered in an individualized dose to achieve a stable reduction in prothrombin times calculated as International Normalized Ratio (INR) values. Then INR- and a drug concentration-time profile was determined. For the interaction phase, meloxicam was added for 7 days and then INR measurements and the warfarin drug profiles were repeated for comparison. Overall, warfarin treatment lasted for 30 days. Results: Warfarin and meloxicam were well tolerated by healthy volunteers in this study. Thirteen healthy volunteers with stable INR values entered the interaction phase. Prothrombin times, expressed as mean INR values, were not significantly altered by concomitant meloxicam treatment, being 1.20 for warfarin alone and 1.27 for warfarin with meloxicam cotreatment. R- and S-warfarin pharmacokinetics were similar for both treatments. Geometric mean (% gCV) AUCSS values for the more potent S-enantiomer were 5.07 mg · h · l−1 (27.5%) for warfarin alone and 5.64 mg · h · l−1 (28.1%) during the interaction phase. Respective AUCSS values for R-warfarin were 7.31 mg · h · l−1 (43.8%) and 7.58 mg · h · l−1 (39.1%). Conclusion: The concomitant administration of the new non-steroidal anti-inflammatory drug (NSAID) meloxicam affected neither the pharmacodynamics nor the pharmacokinetics of a titrated warfarin dose. A combination of both drugs should nevertheless be avoided and, if necessary, INR monitoring is considered mandatory.
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  • 10
    ISSN: 1432-1238
    Keywords: Key words Hemofiltration ; Cytokines ; Anaphylatoxins ; Hemodynamics ; Sepsis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objective: To determine whether hemofiltration (HF) can eliminate cytokines and complement components and alter systemic hemodynamics in patients with severe sepsis. Design: Prospective observation study. Setting: Surgical intensive care unit of a university hospital. Patients: 16 patients with severe sepsis. Interventions: Continuous zero-balanced HF without dialysis (ultrafiltrate rate 2 l/h) was performed in addition to pulmonary artery catheterization, arterial cannulation, and standard intensive care treatment. Measurements and main results: Plasma and ultrafiltrate concentrations of cytokines (the interleukins IL-1β, IL-6, IL-8, and tumor necrosis factor α) and of complement components (C3adesArg, C5adesArg) were measured after starting HF (t0) and 4 h (t4) and 12 h later (t12). Hemodynamic variables including mean arterial pressure (MAP), mean central venous pressure, mean pulmonary artery pressure, pulmonary capillary wedge pressure, and cardiac output were serially determined. During HF, cytokine plasma concentrations remained constant. However, C3adesArg and C5adesArg plasma concentrations showed a significant decline during 12-h HF (C3adesArg: t0=676.9±99.7 ng/ml vs t12=467.8±71, p〈0.01; C5adesArg: 26.6±4.7 ng/ml vs 17.6±6.2, p〈0.01). HF resulted in a significant increase over time in systemic vascular resistance (SVR) and MAP (SVR at t0: 669±85 dyne·s/cm5 vs SVR at t12: 864±75, p〈0.01; MAP at t0: 69.9±3.5 mmHg vs MAP at t12: 82.2±3.7, p〈0.01). Conclusions: HF effectively eliminated the anaphylatoxins C3adesArg and C5adesArg during sepsis. There was also a significant rise in SVR and MAP during high volume HF. Therefore, HF may represent a new modality for removal of anaphylatoxins and may, thereby, deserve clinical testing in patients with severe sepsis.
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