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espanolLas resinas compuestas de tipo bulk-fill representan una excelente alternativa a la tecnica incremental para la reduccion de la tension de polimerizacion sobre la interfaz adhesiva. La incorporacion de rellenos bioactivos, como los que se encuentran en los materiales con tecnologia giomer, refuerzan aun mas el sellado marginal de estas restauraciones. Sin embargo, la alta translucidez, necesaria para la adecuada polimerizacion de los materiales tipo bulk-fill, puede comprometer seriamente el resultado estetico final de las restauraciones, especialmente en presencia de sustratos dentarios no homogeneos u oscurecidos. El objetivo de este reporte de caso fue presentar el uso combinado de dos materiales giomer tipo bulk-fill (Beautifil Bulk Flowable y Beautifil II LS, Shofu) para la restauracion de tres dientes maxilares posteriores con un sustrato dentinario ennegrecido debido a productos de corrosion de amalgama Esta tecnica permitio completar las restauraciones con un resultado estetico y biomimetico satisfactorio. La adecuada conservacion de la anatomia y la funcion de las tres restauraciones tras un periodo de 24 meses, aporta evidencia sobre la adecuada capacidad de sellado marginal de estos materiales bioactivos y el exito de las tecnicas de restauracion tipo bulk-fill en el tiempo. EnglishBulk-fill resin composites represent an excellent alternative to the conventional incremental layering technique for the reduction of polymerization stress on the adhesive interface. Marginal seal can be further improved by the incorporation of bioactive fillers, such as those encountered in Giomers. However, the high translucency required for the adequate polymerization of bulk-fill materials can seriously jeopardize the final aesthetic outcome of the restorations, especially in the presence of inhomogeneous or stained dentin substrates. The aim of this case report was to present the combined use of two bulk-fill Giomer materials (Beautifil Bulk Flowable and Beautifil II LS, Shofu) for the restoration of three posterior maxillary teeth displaying a black stained dentin substrate due to amalgam corrosion products. This technique allowed completion of the restorations with a satisfactory aesthetic and biomimetic outcome. The adequate preservation of the anatomy and function of the three restorations after 24-months follow-up, provides evidence of the enhanced marginal sealing capacity of these bioactive materials and the success of bulk-fill techniques over time.

Rapid Layer Technology (RLT) uses computer-aided design/computer-aided manufacturing (CAD/CAM) to manufacture a veneer layer that is adhesively bonded to the zirconia framework, avoiding firing steps during the fabrication process and thus preventing build-up of residual stresses. This work studied, using sliding contact fatigue, the in vitro lifetime of restorations produced using RLT compared with restorations produced using conventional veneering techniques. Zirconia copings were veneered with a conventional hand-layering method (VM9) using a fast (n = 16) or a slow (n = 16) cooling protocol, or with RLT. For the latter, the veneers were CAD/CAM fabricated using a feldspathic reinforced-glass (Vitablocs Mark II; n = 16) or a polymer-infiltrated reinforced-glass network (Enamic; n = 16) and adhesively bonded to the zirconia frameworks. Crowns thus obtained were submitted to sliding contact fatigue against a steatite indenter in a chewing simulator until failure. A Kaplan-Meier survival analysis was conducted. None of the hand-layered restorations survived after a 2 × 106 -cycle interval, whereas no fractures in the RLT groups were observed. Vitablocs Mark II veneers survived for a longer testing period (3.5 × 106 cycles) than their Enamic counterparts (2.5 × 106 cycles) owing to their superior wear behavior. The RLT represents an efficient method to veneer zirconia frameworks by reducing processing steps and, more importantly, increasing the lifetime of the restorations.

The aim of this study was to compare the effect of different mechanical surface treatments and chemical bonding protocols on the tensile bond strength (TBS) of aged composite. Bar specimens were produced using a nanohybrid resin composite and aged in distilled water for 30 days. Different surface treatments (diamond bur, phosphoric acid, silane, and sandblasting with Al₂O₃ or CoJet Sand), as well as bonding protocols (Primer/Adhesive) were used prior to application of the repair composite. TBS of the specimens was measured and the results were analyzed using analysis of variance (ANOVA) and the Student-Newman-Keuls test (α = 0.05). Mechanically treated surfaces were characterized under SEM and by profilometry. The effect of water aging on the degree of conversion was measured by means of FTIR-ATR spectroscopy. An important increase in the degree of conversion was observed after aging. No significant differences in TBS were observed among the mechanical surface treatments, despite variations in surface roughness profiles. Phosphoric acid etching significantly improved repair bond strength values. The cohesive TBS of the material was only reached using resin bonding agents. Application of an intermediate bonding system plays a key role in achieving reliable repair bond strengths, whereas the kind of mechanical surface treatment appears to play a secondary role.

The two-step production process of glass-ceramic dental restorations involves a computer-aided design/computer-aided machining step followed by a crystallization firing for the final material properties to be achieved. Certain firing parameters are believed to trigger spontaneous fracture of crowns during the cooling process. In this study, cooling fractures have been reproducibly observed and investigated using fractography combined with material (glass transition temperature) and process (cooling rate) characterization. Stress distribution was visualized using birefringence measurements. Fractographic observations revealed fracture starting at the intaglio side of the crowns specifically at contact points with the support firing pins. Further analysis showed that a fast cooling rate was applied during the glass transition region. Thermal stresses were concentrated around the firing pin supports and released the fracture. To prevent such fractures, a slow cooling protocol below the glass transition temperature is our recommendation to dental technicians. Furthermore, the use of planar firing pad or paste supports is advised over the use of point contact supports.

Vielfaltige Erfahrungen im Umgang mit unterschiedlichen Materialien im kindlichen Spiel zu ermoglichen, ist ein wesentliches Ziel psychomotorischen Forderbemuhens. Diese Zielsetzung erfordert ein didaktisch-methodisches Vorgehen, dass einerseits Freiraume fur eigenes Entdecken und Handeln schafft und andererseits konnen mit der Auswahl der Materialien und Aufgabenstellungen auch gezielte Vorgaben verknupft werden, die unterschiedliche Entwicklungsdimensionen der Kinder ansprechen. Fur eine grafomotorische Forderung werden hier beispielhaft Spielanregungen mit einem Joghurtbecher in den Bereichen Korper-Raumwahrnehmung, Geschicklichkeit und Drehfahigkeit, Kraftdosierung, Handigkeit (Lateralitat), visuelle und auditive Wahrnehmung, Planungsfahigkeit gegeben und mit sprachlichen sowie bildlichen Beschreibungen untermalt. [...]

The CCSDS Mission Operations framework defined by the CCSDS Spacecraft Monitor & Control working group aims to provide a reusable, interoperable and distributed mission operations system based on a service-oriented architecture paradigm. Services are defined in terms of an abstract model called the “Message Abstraction Layer”, which is cast to a concrete technology by separately defined bindings. This work is concerned with prototype implementation of binding to the Space Packet Protocol. Challenges and solutions are outlined as well as next steps in terms of testing to prove interoperability. A second prototype implementing a core set of services – the Monitor and Control services – is discussed briefly, as well as a possible way of transition towards a Mission Operations framework based infrastructure at the German Space Operations Center GSOC. The work is put into context by pointing out how benefits for missions arise from the framework and its design.

In autumn 2007, the Medical University of Graz (MUG) upgraded the status of general practice in medical training by integrating a compulsory five-week clerkship in general practice surgeries in the sixth and last year of the curriculum. In cooperation with the Styrian Academy of General Practice (STAFAM), more than 200 general practitioners (GPs) had been accredited to introduce medical students to the specific tasks, problems and decision-making process in general practice. Between October 2007 and June 2009, more than 300 students completed the clerkship.To explore the perceptions of students and GPs towards this new approach to undergraduate teaching in Austrian general practice.Between March and June 2009, we conducted a cross-sectional survey by using a self-administered questionnaire with 14 items for students as well as GPs. To limit recall bias, we gave the questionnaire to all students (n = 146) and GPs (n = 146) immediately after the clerkship. The response rates were 146/146 (100%) and 114/146 (78%) for students and GPs, respectively.The study results show high satisfaction rates among students as well as GPs. Most of the students and GPs perceive the compulsory clerkship in general practice as an essential part of medical education. The organization of the clerkship had the least positive outcome.Our survey shows that the clerkship is well accepted among Austrian medical students and GPs.

The German radar imaging spacecraft TerraSAR-X was launched in June 2007. It is operated from the German Space Operations Center (GSOC) in Oberpfaffenhofen. The mission has a partly commercial character and very high orbit-control requirements. Very fast access into the downloaded house-keeping data is required in order to fully judge the health and correct status of the spacecraft, but also for calibration purposes of the acquired image products. To be able to react to a potential anomaly the operations engineers need to have full access to the offline data within 40 minutes after the dump, since the next pass is often after only 80 minutes. Since up to 11 hours of data can be accumulated in a single dump, this poses a high demand on the offline system performance. With the new TanDEM-X spacecraft which will be launched in October 2009, the requirements for high-performant offline data processing and fast data access are even higher. It turned out that the original offline processing system development met the performance requirements well, but had other drawbacks in computing accuracy, configurability and maintenance. Thus it was decided to refine the requirement definitions and re-develop the offline data processing system. The system presented runs as one control process including graphical GUI to survey the processing. The operation is completely encapsuled in virtual machines; thus the specific configuration needs only once to be configured and can then be saved in a dedicated virtual machine. It is thus also possible to move the software to other hardware or operation system. The natively supported platforms are WinXP and Linux (up to SLES10). Distibuted computing is possible via a control process. The processing is straight forward, i.e. all products are generated based on a generic product format which is highly configurable by content, name etc. Various processor configurations are possible, actually one to four data processors supported to use QuadCore platforms are the optimum. Direct demultiplexing of input data streams is possible (e.g. VCs, SPIDs, APIDs...). Native leap second handling is possible via database, that means leap seconds need only once to be configured and the system allows easy reprocessing of old data without the necessity to change configuration for leap seconds. Further there is no necessity to split data which span over leap second jumps.

SIREV (Sector Imaging Radar for Enhanced Vision) is an innovative airborne radar system which can supply high-quality images in any desired direction under almost every weather condition. In contrast to synthetic aperture radar (SAR) systems, no relative motion between sensor and targets is required in SIREV. The high frame repetition frequency in SIREV allows to detect even very rapid changes in the imaged scenes. Besides providing a map of the earth's surface, the complex-valued radar images can be further processed to supply additional information about the topography and objects in the field of view. A fast processing algorithm has been developed for SIREV which allows a very accurate, phase preserving and efficient image formation. A prototype of a forward-looking SIREV system has been built up at the German Aerospace Center and raw data were obtained by a first demonstration flight using a helicopter as a moving platform. Motion errors of the platform could be extracted from the range compressed raw data avoiding the need of an inertial navigation system. The data processing results show good agreement with the theory. After image formation, coherent and incoherent image averaging processes have been applied to improve the image quality. The evaluation of the computational effort shows that a real-time hardware realization can be carried out using off-the-shelf digital components.

Bistatic configuration is an attractive concept for spaceborne and airborne SAR missions when distributed radars are necessary as for example in the case of interferometric applications. The first reason is the important cost reduction achieved over the multiple radar elements, by having only one transmitter (expensive part) and multiple receivers. The most promising applications are single-pass interferometry with a large baseline and target or surface characterisation from bistatic scattering signature analysis. In a defence context, the improved stealth associated with the receive-only component can provide a wider operational capability. In order to explore the potentials and technical challenges associated with bistatic radar, DLR and ONERA have conducted a joint bistatic airborne radar experiment involving both their SAR systems E-SAR and RAMSES between October 2002 and February 2003. Two main geometrical configurations were flown to explore different scientific and technical objectives. In the first geometrical configuration, the quasi-monostatic mode, the two planes were flying very close to each other to acquire interferometric data in a single-pass cross-platform configuration with large interferometric baselines. The second geometrical configuration was designed to acquire images with a large bistatic angle. The two planes were flying on parallel tracks around 2 km apart, at about the same altitude, with the antennas pointing at the same area on the ground. The authors describe this research programme, including the preparation phase, the analysis of the technological challenges that had to be solved before the acquisition, the strategy adopted for bistatic image processing, the first results and a preliminary analysis of the acquired images.