A Statistical Modeling Approach to Computer-Aided Quantification of Dental Biofilm

Biofilm is a formation of microbial material on tooth substrata. Several methods to quantify dental biofilm coverage have recently been reported in the literature, but at best they provide a semi-automated approach to quantification with significant input from a human grader that comes with the graders bias of what are foreground, background, biofilm, and tooth. Additionally, human assessment indices limit the resolution of the quantification scale; most commercial scales use five levels of quantification for biofilm coverage (0%, 25%, 50%, 75%, and 100%). On the other hand, current state-of-the-art techniques in automatic plaque quantification fail to make their way into practical applications owing to their inability to incorporate human input to handle misclassifications. This paper proposes a new interactive method for biofilm quantification in Quantitative light-induced fluorescence (QLF) images of canine teeth that is independent of the perceptual bias of the grader. The method partitions a QLF image into segments of uniform texture and intensity called superpixels; every superpixel is statistically modeled as a realization of a single 2D Gaussian Markov random field (GMRF) whose parameters are estimated; the superpixel is then assigned to one of three classes (background, biofilm, tooth substratum) based on the training set of data. The quantification results show a high degree of consistency and precision. At the same time, the proposed method gives pathologists full control to post-process the automatic quantification by flipping misclassified superpixels to a different state (background, tooth, biofilm) with a single click, providing greater usability than simply marking the boundaries of biofilm and tooth as done by current state-of-the-art methods.Comment: 10 pages, 7 figures, Journal of Biomedical and Health Informatics 2014. keywords: {Biomedical imaging;Calibration;Dentistry;Estimation;Image segmentation;Manuals;Teeth}, http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6758338&isnumber=636350

BiofilmQuant: A Computer-Assisted Tool for Dental Biofilm Quantification

Dental biofilm is the deposition of microbial material over a tooth substratum. Several methods have recently been reported in the literature for biofilm quantification; however, at best they provide a barely automated solution requiring significant input needed from the human expert. On the contrary, state-of-the-art automatic biofilm methods fail to make their way into clinical practice because of the lack of effective mechanism to incorporate human input to handle praxis or misclassified regions. Manual delineation, the current gold standard, is time consuming and subject to expert bias. In this paper, we introduce a new semi-automated software tool, BiofilmQuant, for dental biofilm quantification in quantitative light-induced fluorescence (QLF) images. The software uses a robust statistical modeling approach to automatically segment the QLF image into three classes (background, biofilm, and tooth substratum) based on the training data. This initial segmentation has shown a high degree of consistency and precision on more than 200 test QLF dental scans. Further, the proposed software provides the clinicians full control to fix any misclassified areas using a single click. In addition, BiofilmQuant also provides a complete solution for the longitudinal quantitative analysis of biofilm of the full set of teeth, providing greater ease of usability.Comment: 4 pages, 4 figures, 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC 2014

Zum Aussagewert der IAB-Berichte über gesamtwirtschaftliche Vakanzbestände (On the reliability of the IAB reports regarding the overall stock of job vacancies)

"The figures published annually by the IAB concerning the stock of job vacancies across the economy could potentially provide information about the extent of mismatch unemployment that could be of value in terms of labour market diagnosis. This paper explains that the IAB figures on this do not, however, provide quite the information that they seem to promise at first sight. For theoretical considerations and empirical evidence indicate that the job vacancy stocks ascertained by the IAB are a mixture of real vacancies and jobs to be filled at a later date. On the other hand, the figure of 'jobs to be filled later', which is shown separately by the IAB, presumably only captures some of the total number of jobs to be filled later, namely those for which the date of the planned recruitment is still a long time off at the time when the survey is conducted. In addition, the vacancy stocks reported by the IAB disregard entirely the stock of vacancies which are unfilled only due to a delayed commencement of matched candidates. Finally some modifications to the programme of questions and the reporting scheme used in the annual IAB surveys are put forward, which would make it possible to improve the labour-market-diagnostic information content of the relevant IAB reports. " (Author's abstract, IAB-Doku) ((en))offene Stellen, Arbeitsstatistik, IAB, Reliabilität, Zuverlässigkeit, Datengewinnung, Stellenangebot, Validität, Arbeitskräftenachfrage, mismatch

Verlaufstypen, Bestands- und Stromgrößen beim gesamtwirtschaftlichen Stellenangebot - mit einer "Stellenangebotsgesamtrechnung" für Westdeutschland 2001 (Process types, stock and flow values in the macroeconomic supply of jobs - with a "job supply account" for western Germany in 2001)

"In this paper a new typology is proposed for the empirical analysis of job supply proc-esses. On the basis of this a schema is developed for a 'job supply account' in which stock and flow values, differentiated according to the type of process are recorded fully and linked systematically. Available empirical data and empirically sound estimates for the supply of jobs in western Germany (the territory of the Federal Republic of Germany before reunification) in 2001 are then put into this schema and this is used to calculate the missing further data. It emerges that the suggested schema is well suited for making approximate calculations of missing data and for checking the consistency of individual data. The most remarkable finding of the calculation of stock and flow values of the job supply is that in western Germany in 2001 besides an estimated three to four million successful job offers there were approximately two million vacancies for which the search for manpower was ended without success. The vacancies that remained unfilled made up about three quarters of the stock of vacancies to be filled immediately, which in western Germany always exists in a magnitude of at least several hundred thousand vacancies. And only in about one third of all cases of a search for staff on the external job market was it possible to fill the job in good time without a vacancy period. This is followed by a discussion of which figures in the context of the suggested schema and the presented example of a calculation of stock and flow data for western Germany in 2001 are relevant for which issues regarding labour market diagnosis. Some of the data of the job supply account are very informative, especially for diagnosing the extent and the particular structure of 'mismatch-unemployment'. " (Author's abstract, IAB-Doku) ((en))Stellenangebot, offene Stellen, IAB-Betriebspanel, Personalbeschaffung, Westdeutschland, Bundesrepublik Deutschland

Zur Diskussion über den Aussagewert der IAB-Berichte über gesamtwirtschaftliche Vakanzbestände (ZAF 1/2005) : ein Nachtrag zur Klarstellung (On the discussion about the reliability of the IAB reports on the stock of vacancies in Germany (ZAF 1/2005) : a supplement for clarification)

"Taking up the discussion surrounding the reliability of the IAB reports on the stock of vacancies in Germany in this journal (ZAF, issue 1/2005), this paper clears up misunderstandings, corrects incorrect statements, and presents further new arguments. The paper is intended to show that it would be possible, without any additional costs, to use the IAB reports on the stock of vacancies in the economy as a whole to obtain additional information of interest for labour market diagnosis if the 'jobs to be filled immediately' were recorded correctly. This discussion resulted, however, in the well-founded suspicion that the extrapolation results of the IAB reports on the stock of vacancies in Germany are incorrect in two ways: firstly as a consequence of a selection bias in the data basis with regard to the firms' reporting behaviour, and secondly due to the adjustment of the extrapolations to incorrect data from the Federal Employment Service about stocks of registered vacancies. This suspicion is explained separately in the appendix." (Author's abstract, IAB-Doku) ((en))offene Stellen, Arbeitsstatistik, IAB, Reliabilität, Zuverlässigkeit, Datengewinnung, Stellenangebot, Validität, Arbeitskräftenachfrage, mismatch

Hartz IV: Ein richtiger Ansatz - nur mangelhaft umgesetzt?

--

Knowledge, action, and the frame problem

AbstractThis paper proposes a method for handling the frame problem for knowledge-producing actions. An example of a knowledge-producing action is a sensing operation performed by a robot to determine whether or not there is an object of a particular shape within its grasp. The work is an extension of Reiter's approach to the frame problem for ordinary actions and Moore's work on knowledge and action. The properties of our specification are that knowledge-producing actions do not affect fluents other than the knowledge fluent, and actions that are not knowledge-producing only affect the knowledge fluent as appropriate. In addition, memory emerges as a side-effect: if something is known in a certain situation, it remains known at successor situations, unless something relevant has changed. Also, it will be shown that a form of regression examined by Reiter for reducing reasoning about future situations to reasoning about the initial situation now also applies to knowledge-producing actions