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  • 1
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 1180-1182 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on the fabrication and optical characterization of a three-dimensional (3D) photonic crystal on the basis of macroporous silicon. The structure consists of a 2D array of air pores in silicon whose diameter is varied (modulated) periodically with depth. The bandstructure of the resulting 3D hexagonal photonic crystal is calculated and compared with transmission measurements. The described structure allows to adjust the dispersion relation along the pore axis almost independently from the dispersion relation in the plane perpendicular to the pore axis. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 2079-2081 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In scanning near-field optical microscopy, scanning ion conductance microscopy and for localized electrochemical deposition out of micropipettes, the detection of shear forces between the tip and sample is one of the most common methods of distance control. Here, pulled micropipettes were utilized to form an evaporating drop of water whose frictional force in air causes a specific resonance shift of the tip vibration. This resonance shift and the amplitude at the resonance were investigated with regard to their dependence on the drop diameter. In order to calculate the friction, the tip is approximated as a damped harmonic oscillator. The typical range of the shear forces in scanning probe microscopies is estimated to be between 1 pN and 0.1 nN. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 4399-4401 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The influence of lattice strain and Mg vacancies on the superconducting properties of MgB2 samples has been investigated. High quality samples with sharp superconducting transitions were synthesized. The variations in lattice strain and Mg vacancy concentrations were obtained by varying the synthesis conditions. It was found that high strain (∼1%) and the presence of Mg vacancies (∼5%) resulted in lowering the Tc by only 2 K. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Gerodontology 17 (2000), S. 0 
    ISSN: 1741-2358
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Objectives: The ongoing controversial discussion about a possible negative effect of amalgam fillings on the cognitive abilities and the pathogenesis dementia was the objective of the present study.Sample: A total of 300 patients aged from 70 to 103 years were selected from the multidisciplinary ‘Berlin Aging Study’ (Base). The sample was heterogeneous concerning lifestyle, education and social prestige. According to their dental state subjects were allocated into three groups: edentate ≥20 years (I) and residual teeth without (II) or with (III) amalgam restorations. All groups were matched for age and gender.Design: Dental examinations and various psychiatric as well as psychological assessments were carried out by professionals within the protocol of the BASE. Tests were chosen to reveal the presence and degree of dementia and assess cognitive abilities such as ‘perceptual speed’, ‘reasoning’, ‘memory’, ‘fluency’ and ‘knowledge’.Results: The present findings negate a correlation between the dental state and the pathogenesis of dementia and the physiological age-related decline in cognitive abilities. Thus the presence of amalgam fillings did neither correlate to a demented mental condition nor an impaired cognitive performance.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of oral rehabilitation 31 (2004), S. 0 
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: summary  The conventional fabrication of complete dentures involves two separate clinical sessions for functional impression making and jaw registration. The presented method combines both procedures in one session. The aim of this study was to survey the three-dimensional tooth positions in complete dentures with reference to the ridges to establish arbitrary guideline values that could be used for the manufacturing of tooth-position analogue plastic rims on functional impression trays. New complete dentures were fabricated by supervised undergraduate students in the conventional manner for 104 edentulous patients. The position of the maxillary teeth was surveyed in the horizontal plane using the Schmuth ‘vizor-measuring plate’. The vertical dimension of occlusion, represented as the distance between opposing ridge areas of the dentures in maximum intercuspation, was measured at different sites by means of a Gutowski gauge. The tooth positions on the dentures varied widely, e.g. the horizontal distances between the incisive papilla and the maxillary incisors was 7·1 ± 2·3 (3–14) mm. The vertical dimension of occlusion, which is most important in the jaw registration, varied equally with an anterior inter-alveolar distance between 12 and 33 (20·4 ± 4·0) mm. Arbitrary moulding of the tooth position-analogue plastic rims does not seems to be an ideal method of pre-shaping functional impression trays, because the individual anatomical variation is considerable. Alternatively, the horizontal and vertical tooth positions of functionally and aesthetically pleasing dentures should be measured to pre-shape the rims of functional impression trays in the maxillary and the mandibular jaw. Such trays are a valuable tool for functional impressions and an immediate preliminary jaw registration in the fabrication of new complete dentures. This method allows a first try-in of the full set-up in the third clinical visit without loosing precision.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of oral rehabilitation 29 (2002), S. 0 
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The closed-mouth technique for the construction of complete dentures provides in the first session both impressions and a rough idea of the jaw relation in habitual intercuspation. The aim of this study was to apply this methodological advantage to the open-mouth technique and to assess whether the arbitrary moulding of tooth position-analogue plastic rims on functional impression trays facilitates a subsequent preliminary bite registration. Therefore, 104 complete dentures, manufactured by students during their final exams, were surveyed at 22 different test points using the Gutowski–Meyding gauge. Furthermore, the position of the front teeth, the lip support and the vertical dimension were assessed clinically.The results were as followsUpper complete denturevertical distance: middle of ridge – incisal edge of central incisor: 13 ± 3 mm (5–21)vertical distance: middle of ridge – tip of cusp of first molar: 9 ± 2 mm (2–16)sagittal distance: middle of ridge – incisal edge of central incisor 7 ± 2 mm (3–14)Lower complete denturevertical distance: middle of ridge – incisal edge of central incisor: 12 ± 3 mm (7–19)vertical distance: middle of ridge – tip of cusp of first molar: 13 ± 3 mm (5–20)sagittal distance: middle of ridge – incisal edge of central incisor: 3 ± 2 mm (0–6)Complete dentures in maximum intercuspationvertical distance upper to lower ridge region central incisor 20 ± 4 mm (12–33)vertical distance upper to lower ridge region first molar 21 ± 4 mm (9–34)Because of the interindividual variance the arbitrary moulding of the tooth position-analogue plastic rims seems not ideal. However, a functional and aesthetically pleasing existing denture should be surveyed to pre-shape functional impression trays. Such individualized trays proved clinically a valuable tool for functional impressions and an immediate preliminary bite registration.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of oral rehabilitation 29 (2002), S. 0 
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In complete denture wearers the maximum bite force (MBF) is known to be considerably lower than in dentate people. Low MBF might therefore be an indication of poor denture fit but there is limited evidence on this. Therefore, the aim of the present study was to investigate whether MBF can be improved by the replacement of complete dentures for elderly people.Nine edentulous volunteers, average age 74·2 ± 5·5 years and average denture experience 19·4 ± 19·5 years (1–50 years), had replacement dentures made. Functional impressions were taken after border moulding using zinc oxide eugenol paste. After a rehearsal session, MBF was recorded with the old dentures, and with the new dentures immediately at insertion, at 3, 8 days, 2–3 weeks, 1, 2, 3 and 6–10 months post-insertion (p.i.). The MBF was recorded with the central bearing point method using a full-bridge strain gauge with a confirmed linearity from 1 to 1000 N and an accuracy of ±1 N. Data were analysed off-line using the mean of two peak readings per patient per session.The results indicate that MBF tended to be impaired when replacement dentures were first fitted (n.s.). However, this trend reversed during the first month p.i. for patients with a ‘moderate’ lower ridge resorption of Atwood (1963) grade 3 or 4 (n=5). Patients with more severe lower ridge resorption (Atwood grade 5 or 6; n=4) showed a significantly lower MBF over the entire observation period (P=0·05) and took longer to regain bite strength. Only patients with moderate bone resorption exceeded their pre-insertion level of MBF within the observation period of 6–10 months p.i. In contrast to one report of immediate improvement of MBF at insertion of a new or relined denture (Leyka et al., 2000), the present study suggests that, at least for elderly patients with severe bone resorption, delayed improvement of MBF should be expected.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford UK : Blackwell Science Ltd
    Journal of oral rehabilitation 29 (2002), S. 0 
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In a dentate subject a jaw relation can either be determined in maximum intercuspation and is as such given by the occlusal morphology, or the mandibular position can be allocated according to the centric position of the condyles. For comprehensive restorative treatment or analytic measures of the occlusion it is important to record the centric condylar position. Various registration methods have been described in the literature, but there is no consensus on which is the `best'. The aim of the present study was therefore to assess the accuracy of various registration methods and evaluate a possible influence of the used materials. Four dentists were involved in the clinical part of the study, another was responsible for the measurements. Impressions were taken from 81 fully dentate volunteers. The casts were mounted by face-bow transfer and central-bearing-point (CBP) registration into Dentatus® articulators. Subsequently the centric condylar position was determined with six different methods and materials, respectively. Each method was reproduced twice so that a total of 18 registrations was performed per patient. The mandibular positions which resulted from the individual registrations were then repeatedly compared in the condylar area using a computer supported specially modified measuring articulator. The accuracy was found best for the unrefined wax wafer registration (x=0·33 mm) and with an average of 0·44 mm worst when using acrylic wafers. The CBP and frontal jig methods as well as tin-foil and refined wax wafers showed an accuracy in-between these boundaries. The biggest measured mandibular displacement between any two registrations were considerably 2·0 mm. However, the described differences in accuracy between the various methods and materials proved statistically not significant. All investigated jaw registrations showed an accuracy of about 20 times the tactile fine sensibility of natural teeth which has to be taken into account when inserting fixed prosthetic restorations in centric condylar position. Despite meticulous clinical and technical procedures small occlusal adjustments are therefore almost unavoidable.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0332-1649
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: In this paper, stochastic optimisation and risk estimation techniques are applied to the problem of hydroelectric generator design. Optimisation results from deterministic simulations can involve considerable risks due to unavoidable variations in system properties as well as environmental conditions. Therefore, stochastic simulation is used to include the effects of parameter scatter and noise effects in the computer models. This allows the evaluation of the scatter in performance and thus an assessment of reliability and quality of the simulated system.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    European archives of psychiatry and clinical neuroscience 99 (1933), S. 475-495 
    ISSN: 1433-8491
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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