420 research outputs found
Diode Laser Ablation Versus Surgical Scalpel Technique For Gingival Depigmentation: A Randomized Controlled Clinical Trial
The aim of this study is to evaluate and compare the clinical efficiency of gingival depigmentation procedure with conventional scalpel and diode laser techniques. Materials and methods: This study was carried out as a randomized controlled clinical trial, split mouth design, in which fifteen patients having diffuse continuous physiologic pigmentation of the gingiva involving facial aspect of maxillary right to left premolar area were selected. The maxilla was divided into two halves and randomly allotted for “study site” for depigmentation with diode laser technique, and “control site” for depigmentation with scalpel technique. The studied variables were the degree of pain, bleeding, duration of the procedure, wound healing, and level of melanin repigmentation. The follow-up period was twelve months. For statistical analysis, Wilcoxon signed-rank test were conducted. Results: The diode laser technique showed better results regarding pain during the first three days, duration of the procedure, and bleeding. There was no significant difference between diode laser technique and scalpel technique regarding the wound healing and pain experienced by the patient after one week of surgery. Both sites showed recurrence of pigmentation, yet it was after a shorter period on the scalpel site. Conclusion: The findings of the present study suggest that gingival depigmentation was effective with both scalpel and laser techniques. However, the laser treated sites showed reduced pain experienced by the patient and better operator comfort. Melanin repigmentation was observed on sites treated with scalpel and diode laser, yet faster on the scalpel technique sites
Constraint on the optical constants of a transparent film on an absorbing substrate for inversion of the ratio of complex p and s reflection coefficients at a given angle of incidence
An absorbing substrate of complex refractive index n2-jk2 can be coated by a transparent thin film of refractive index n1 and normalized thickness ζ so that the ratio of complex reflection coefficients for the pand s polarizations of the film-covered substrate ρ is the inverse of that of the film-free substrate ρ¯ at a given angle of incidence φ. A pair of parallel (metallic) mirrors, one uncoated and the other coated with a ρ-inverting layer, causes a beam displacement without change of polarization and with a certain net reflectance (insertion loss) ℜ. In this paper the constraint on n1,n2,k2 for ρ inversion (ρρ¯ = 1) is represented by a family of constant -n1 contours in the n2k2 plane at φ = 45, 60, and 75°. Along each solution curve, ζ and ℜ are also plottedvs n2 at constant n1. Analysis of the effect of small errors of incidence angles, film refractive index, and thickness is presented for two specific designs using Al mirrors at 650 and 950 nm
Supporting the automated generation of modular product line safety cases
Abstract The effective reuse of design assets in safety-critical Software Product Lines (SPL) would require the reuse of safety analyses of those assets in the variant contexts of certification of products derived from the SPL. This in turn requires the traceability of SPL variation across design, including variation in safety analysis and safety cases. In this paper, we propose a method and tool to support the automatic generation of modular SPL safety case architectures from the information provided by SPL feature modeling and model-based safety analysis. The Goal Structuring Notation (GSN) safety case modeling notation and its modular extensions supported by the D-Case Editor were used to implement the method in an automated tool support. The tool was used to generate a modular safety case for an automotive Hybrid Braking System SPL
Towards Measurement of Confidence in Safety Cases
Arguments in safety cases are predominantly qualitative. This is partly attributed to the lack of sufficient design and operational data necessary to measure the achievement of high-dependability targets, particularly for safety-critical functions implemented in software. The subjective nature of many forms of evidence, such as expert judgment and process maturity, also contributes to the overwhelming dependence on qualitative arguments. However, where data for quantitative measurements is systematically collected, quantitative arguments provide far more benefits over qualitative arguments, in assessing confidence in the safety case. In this paper, we propose a basis for developing and evaluating integrated qualitative and quantitative safety arguments based on the Goal Structuring Notation (GSN) and Bayesian Networks (BN). The approach we propose identifies structures within GSN-based arguments where uncertainties can be quantified. BN are then used to provide a means to reason about confidence in a probabilistic way. We illustrate our approach using a fragment of a safety case for an unmanned aerial system and conclude with some preliminary observation
Enhancing Covid-19 Decision-Making by Creating an Assurance Case for Simulation Models
Simulation models have been informing the COVID-19 policy-making process.
These models, therefore, have significant influence on risk of societal harms.
But how clearly are the underlying modelling assumptions and limitations
communicated so that decision-makers can readily understand them? When making
claims about risk in safety-critical systems, it is common practice to produce
an assurance case, which is a structured argument supported by evidence with
the aim to assess how confident we should be in our risk-based decisions. We
argue that any COVID-19 simulation model that is used to guide critical policy
decisions would benefit from being supported with such a case to explain how,
and to what extent, the evidence from the simulation can be relied on to
substantiate policy conclusions. This would enable a critical review of the
implicit assumptions and inherent uncertainty in modelling, and would give the
overall decision-making process greater transparency and accountability.Comment: 6 pages and 2 figure
Constraint on the optical constants of a transparent film on an absorbing substrate for inversion of the ratio of complex p and s reflection coefficients at a given angle of incidence
An absorbing substrate of complex refractive index n2-jk2 can be coated by a transparent thin film of refractive index n1 and normalized thickness ζ so that the ratio of complex reflection coefficients for the pand s polarizations of the film-covered substrate ρ is the inverse of that of the film-free substrate ρ¯ at a given angle of incidence φ. A pair of parallel (metallic) mirrors, one uncoated and the other coated with a ρ-inverting layer, causes a beam displacement without change of polarization and with a certain net reflectance (insertion loss) ℜ. In this paper the constraint on n1,n2,k2 for ρ inversion (ρρ¯ = 1) is represented by a family of constant -n1 contours in the n2k2 plane at φ = 45, 60, and 75°. Along each solution curve, ζ and ℜ are also plottedvs n2 at constant n1. Analysis of the effect of small errors of incidence angles, film refractive index, and thickness is presented for two specific designs using Al mirrors at 650 and 950 nm
Artificial intelligence in health care: accountability and safety
The prospect of patient harm caused by the decisions made by an artificial intelligence-based clinical tool is something to which current practices of accountability and safety worldwide have not yet adjusted. We focus on two aspects of clinical artificial intelligence used for decision-making: moral accountability for harm to patients; and safety assurance to protect patients against such harm. Artificial intelligence-based tools are challenging the standard clinical practices of assigning blame and assuring safety. Human clinicians and safety engineers have weaker control over the decisions reached by artificial intelligence systems and less knowledge and understanding of precisely how the artificial intelligence systems reach their decisions. We illustrate this analysis by applying it to an example of an artificial intelligence-based system developed for use in the treatment of sepsis. The paper ends with practical suggestions for ways forward to mitigate these concerns. We argue for a need to include artificial intelligence developers and systems safety engineers in our assessments of moral accountability for patient harm. Meanwhile, none of the actors in the model robustly fulfil the traditional conditions of moral accountability for the decisions of an artificial intelligence system. We should therefore update our conceptions of moral accountability in this context. We also need to move from a static to a dynamic model of assurance, accepting that considerations of safety are not fully resolvable during the design of the artificial intelligence system before the system has been deployed
Fort- und Weiterbildung der Lehrer vor dem Hintergrund der besonderen Bedürfnisse der IBA-Schüler und der daraus resultierenden besonderen Anforderungen an den Unterricht
Anliegen der vorliegenden Forschungsarbeit ist die Eruierung, inwieweit Fort- und Weiterbildung für Lehrer vor dem Hintergrund der besonderen Bedürfnisse der Schüler in Integrativer Berufsausbildung (IBA) und den daraus resultierenden besonderen Anforderungen an den Unterricht Unterstützung bietet. Zur Beantwortung der Forschungsfrage werden Leitfadeninterviews mit IBA-Lehrern verschiedener Berufsschulen innerhalb Wiens durchgeführt. Die Interviewauswertung erfolgt anhand einer Themenanalyse in Anlehnung an FROSCHAUER und LUEGER. Die Forschungsarbeit zeigt auf, in welchen Bereichen Fort- und Weiterbildung für IBA-Lehrer Unterstützung bietet und wo Verbesserungsmöglichkeiten im Zusammenhang mit dem aktuellen Fort- und Weiterbildungsangebot bestehen. Die Untersuchung macht deutlich, dass Fort- und Weiterbildung für die Bewältigung des Schulalltags des IBA-Lehrers unerlässlich ist.In this thesis, I explore the dimensions of support teachers working in the field of integrated vocational education (IVE) can derive from continuing processes of training and education. Drawing from guideline-based interviews conducted with teachers at various vocational schools in Vienna, I analyse the significance of these forms of continuing training in the IVE teachers' challenging working environment. Using Froschauer's and Lueger's thematic analysis as a methodological tool, I explore the forms of support IVE teachers identify with regards to continuing training, and I point out needs for improvement concerning this matter. My research demonstrates the crucial significance of continuing processes of education as strategies of coping for IVE teachers
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