Gaifman Normal Forms for Counting Extensions of First-Order Logic

We consider the extension of first-order logic FO by unary counting quantifiers and generalise the notion of Gaifman normal form from FO to this setting. For formulas that use only ultimately periodic counting quantifiers, we provide an algorithm that computes equivalent formulas in Gaifman normal form. We also show that this is not possible for formulas using at least one quantifier that is not ultimately periodic. Now let d be a degree bound. We show that for any formula phi with arbitrary counting quantifiers, there is a formula gamma in Gaifman normal form that is equivalent to phi on all finite structures of degree <= d. If the quantifiers of phi are decidable (decidable in elementary time, ultimately periodic), gamma can be constructed effectively (in elementary time, in worst-case optimal 3-fold exponential time). For the setting with unrestricted degree we show that by using our Gaifman normal form for formulas with only ultimately periodic counting quantifiers, a known fixed-parameter tractability result for FO on classes of structures of bounded local tree-width can be lifted to the extension of FO with ultimately periodic counting quantifiers (a logic equally expressive as FO+MOD, i.e., first-oder logic with modulo-counting quantifiers)

A Cohort Study Followed for 13 Years

Background There is growing evidence of an association between oral health, specifically dental status, and chronic systemic diseases. However, varying measures of dental status across different populations and low study sample has made comparison of studies and conclusion of findings unclear. Our aim is to examine whether the number of teeth as a measure of dental status is associated with incident chronic diseases in a cohort setting. Methods We conducted a cohort study among 24,313 middle-aged Germans followed up for 13 years. Data on number of teeth as a measure of dental status were obtained through self-reports. Outcomes were clinically–verified incident non–fatal myocardial infarction, stroke, type 2 diabetes mellitus, and cancer. Hazard ratio (HR) and 95% confidence intervals (CI) were obtained from Cox regression models. Results Increasing number of teeth is inversely related to risk of myocardial infarction (HR: 0.97; 95% CI: 0.96, 0.99). The full multivariate model of teeth groups showed a strong linear trend for myocardial infarction, a less strong trend for stroke, and no relation with type 2 diabetes mellitus and cancer in a competing risk model. Participants with 18–23 teeth and those without teeth were at 76% (95%CI: 1.04, 3) and 2.93 times (95%CI: 1.61, 5.18) higher risk of myocardial infarction compared to those with nearly all teeth (28–32 teeth). Conclusions Number of teeth is specifically associated with myocardial infarction and not with other chronic disease indicating that dental status further strengthens the link between oral health and cardiovascular diseases

Innovative method for cutting edge preparation with flexible diamond tools

The micro geometry of the cutting edge is of central importance for the performance of cutting tools. It influences all essential parameters in the machining process: chip formation, thermal and mechanical load on the tool and the workpiece, tool wear and the resulting workpiece quality. The effect depends on the size and shape of the cutting edge rounding. Depending on the machining process, asymmetrical roundings often show the greatest potential. In addition to increasing tool life, the quality of the surfaces produced can be improved by a specifically designed asymmetrical rounding. For edge preparation, blasting, brushing and drag finishing are used in industrial applications. However, an economic production of asymmetrical cutting edge geometries on cutting tools with complicated cutting edge geometry, such as solid carbide tools with helical cutting edge, cannot be achieved with these methods. Therefore, a novel method for preparation of the cutting edge rounding using flexible bond diamond polishing tools is introduced. Hence, the conducted research in this study analyzes the basic mechanisms and influencing factors using the new preparation method. For this purpose, polishing tests are carried out on carbide indexable inserts. The results show that the polishing tools can be used to create both asymmetrical and symmetrical roundings in an industrially relevant dimension. © 2019 The Authors. Published by Elsevier B.V

Soziale Beziehungen im Luftverkehr

"Der Beitrag stellt erste empirische Ergebnisse aus einem DFG-Forschungsprojekt an der TU Chemnitz vor, das zu Formen multipler Entgrenzung bei Flugpersonal forscht. Der Fokus ist auf den Arbeitsalltag von Piloten und Flugbegleitern gerichtet. Hierzu werden verschiedene Themenbereiche untersucht: Arbeitsorganisation und Technologie, die alltägliche Arbeitspraxis des Flugpersonals, betriebliche Bedingungen, das Berufsfeld von Piloten und Flugbegleitern und die Veränderungen, mit denen sich diese Berufsfelder auseinandersetzen müssen, Qualifikationsmöglichkeiten innerhalb der Unternehmen sowie die Wechselwirkungen zwischen Arbeit und Leben. Während die meisten Themenfelder nur angerissen werden, befasst sich der Vortrag zentral mit sozialen Beziehungen der Arbeitenden auf drei Ebenen: das Verhältnis zwischen Cockpit und Kabine, Flugpersonal und Passagieren sowie Luft- und Bodenpersonal. Exemplarisch für das Verhältnis zwischen Cockpit und Kabine stehen Ungleichheitsaspekte, z.B. in Form der Wahrnehmung eines unterschiedlichen sozialen Status auf der individuellen und betrieblichen Ebene oder der unterschiedlichen Zugänge zu Informationen während des Fluges. Bei der Konstellation Flugpersonal - Passagiere kann beispielhaft der Trend zur Billigfliegerei und die damit verbundene Servicereduktion genannt werden, was das Dienstleistungsverhältnis gegenüber dem Kunden neu bewertet. Die dritte Ebene, welche die Wechselwirkungen zwischen dem fliegenden Personal und dem Bodenpersonal umfasst, beleuchtet u.a. die Diskrepanz der gegenseitigen Wahrnehmung, aber auch die Kooperation beider Arbeitsbereiche. Im Ergebnis resümiert der Beitrag ein multidimensionales Beziehungsgeflecht als Grundlage der Arbeit des Flugpersonals und beleuchtet dies als Voraussetzung verschiedener Formen der Dienstleistungsarbeit." (Autorenreferat

Murine Toll-Like Receptor 2 Activation Induces Type I Interferon Responses from Endolysosomal Compartments

Background: Toll-like receptors (TLRs) are among the first-line sentinels for immune detection and responsiveness to pathogens. The TLR2 subfamily of TLRs (TLR1, TLR2, TLR6) form heterodimers with each other and are thus able to recognize a broad range of components from several microbes such as yeast, Gram-positive bacteria and protozoa. Until now, TLR2 activation by bacterial ligands has long been associated with pro-inflammatory cytokines but not type I interferon responses. Methodology/Principal Findings: Using a variety of transgenic mice, here we provide in vivo and in vitro data showing that TLR2 activation does in fact induce interferon-beta and that this occurs via MyD88-IRF1 and-IRF7 pathways. Interestingly, by microscopy we demonstrate that although a cell surface receptor, TLR2 dependent induction of type I interferons occurs in endolysosomal compartments where it is translocated to upon ligand engagement. Furthermore, we could show that blocking receptor internalization or endolysosomal acidification inhibits the ability of TLR2 to trigger the induction type I interferon but not pro-inflammatory responses. Conclusion/Significance: The results indicate that TLR2 activation induces pro-inflammatory and type I interferon responses from distinct subcellular sites: the plasma membrane and endolysosomal compartments respectively. Apart from identifying and characterizing a novel pathway for induction of type I interferons, the present study offers new insights into how TLR signaling discriminates and regulates the nature of responses to be elicited against extracellular and endocytosed microbes

An Empirical Examination of an Agile Contingent Project/Method Fit Model

While research has demonstrated positive productivity and quality gains from using agile software development methods (SDMs), some experts argue that no single SDM suits every project context. We lack empirical evidence about the project contextual factors that influence when one should use these methods. Research suggests several factors to explain agile method appropriateness; however, generalizable empirical evidence supporting these suggestions is weak. To address this need, we used contingency theory and the information processing model to develop the agile contingent project/method fit model. Subsequently, we used the model to analyze the influence of project contextual factors and agile practices on software development professionals’ perceptions regarding agile SDM appropriateness. We tested the model using survey data collected from 122 systems development professionals who provided information regarding: 1) contextual factors surrounding a recent agile development project, 2) agile practices applied during the course of that project, and 3) perceptions regarding the relative fit (appropriateness) of the agile method used. Linear regression identified several significant relationships between project contextual factors, agile practices, and respondents’ relative fit perceptions

Micron‐Sized Pored Membranes Based on Polyvinylidene Difluoride Hexafluoropropylene Prepared by Phase Inversion Techniques

In this study, micron‐sized pored membranes, based on the co‐polymer polyvinylidene difluoride hexafluoropropylene (PVdF‐HFP) were prepared via phase inversion techniques. The aim of the approach was to find less harmful and less toxic solvents to fabricate such films. Therefore, the Hansen solubility approach was used to identify safer and less toxic organic solvents for the phase inversion process, relative to present solvent mixtures, based on acetone, dimethyl formamide, dimethyl acetamide or methanol. With this approach, it was possible to identify cyclopentanone, ethylene glycol and benzyl alcohol as suitable solvents for the membrane preparation process. Physicochemical and mechanical properties were analyzed and compared, which revealed a uniform membrane structure through the cross section. Differences were observed at the top surface, in dependence of both preparation approaches, which are described in detail

Multilokale Arrangements im Luftverkehr: Voraussetzungen, Bedingungen und Folgen multilokalen Arbeitens und Wohnens

Die Arbeit von Flugbegleiterinnen/-begleitern und Pilotinnen und Piloten ist per se durch Mobilität gekennzeichnet. Dies begründet verschiedenartige Multilokalität, der jedoch individuelle Ansprüche des Flugpersonals und konkrete Anforderungen ihrer Lebenssituationen gegenüberstehen. Der dauerhafte Umgang mit Multilokalität greift daher auf erprobte Arrangements und individuelle Strategien zurück, mit den Chancen und Risiken der Multilokalität umzugehen, ohne jedoch gänzlich vor Problemen gefeit zu sein. Er ist gerahmt durch umfassende gesetzliche Regelungen und betriebliche Leistungen einerseits und Anpassungsleistungen der Beschäftigten andererseits. Auch sind das Nutzen von örtlichen Gegebenheiten und nicht zuletzt Kompensationsleistungen lokaler Personen essenziell. Multilokale sind an verschiedenen Punkten auf Lokalität, z.B. Dienstleistungen Lokaler angewiesen. Die Kooperation zwischen Multilokalen und Residenten ist jedoch wechselseitig zu strukturieren. Im Ergebnis stehen vermehrt atypische, individualisierte Lebensstile und Belastungen. Der Beitrag fokussiert Möglichkeiten des fliegenden Personals, Multilokalität in Arbeit und Leben zu integrieren und als Lebenswirklichkeit täglich zu gestalten

A luminosity distribution for kilonovae based on short gamma-ray burst afterglows

The combined detection of a gravitational-wave signal, kilonova, and short gamma-ray burst (sGRB) from GW170817 marked a scientific breakthrough in the field of multi-messenger astronomy. But even before GW170817, there have been a number of sGRBs with possible associated kilonova detections. In this work, we re-examine these "historical" sGRB afterglows with a combination of state-of-the-art afterglow and kilonova models. This allows us to include optical/near-infrared synchrotron emission produced by the sGRB as well as ultraviolet/optical/near-infrared emission powered by the radioactive decay of $r$-process elements (i.e., the kilonova). Fitting the lightcurves, we derive the velocity and the mass distribution as well as the composition of the ejected material. The posteriors on kilonova parameters obtained from the fit were turned into distributions for the peak magnitude of the kilonova emission in different bands and the time at which this peak occurs. From the sGRB with an associated kilonova, we found that the peak magnitude in H bands falls in the range [-16.2, -13.1] ($95\%$ of confidence) and occurs within $0.8-3.6\,\rm days$ after the sGRB prompt emission. In g band instead we obtain a peak magnitude in range [-16.8, -12.3] occurring within the first $18\,\rm hr$ after the sGRB prompt. From the luminosity distributions of GW170817/AT2017gfo, kilonova candidates GRB130603B, GRB050709 and GRB060614 (with the possible inclusion of GRB150101B) and the upper limits from all the other sGRBs not associated with any kilonova detection we obtain for the first time a kilonova luminosity function in different bands.Comment: Published in MNRAS, 24 pages, 14 figure