Transformation-Based Bottom-Up Computation of the Well-Founded Model

We present a framework for expressing bottom-up algorithms to compute the well-founded model of non-disjunctive logic programs. Our method is based on the notion of conditional facts and elementary program transformations studied by Brass and Dix for disjunctive programs. However, even if we restrict their framework to nondisjunctive programs, their residual program can grow to exponential size, whereas for function-free programs our program remainder is always polynomial in the size of the extensional database (EDB). We show that particular orderings of our transformations (we call them strategies) correspond to well-known computational methods like the alternating fixpoint approach, the well-founded magic sets method and the magic alternating fixpoint procedure. However, due to the confluence of our calculi, we come up with computations of the well-founded model that are provably better than these methods. In contrast to other approaches, our transformation method treats magic set transformed programs correctly, i.e. it always computes a relevant part of the well-founded model of the original program.Comment: 43 pages, 3 figure

Der Eisvogel – Vogel des Jahres 2009 – im Kreis Höxter

Im Kreis Höxter stellt sich die Situation entgegen vielen anderen Landesteilen NRWs recht günstig dar. Grund ist der relativ geringe Verbauungsgrad der größeren Fließgewässer wie Nethe, Aa, Emmer oder Beber. Hinzu kommt, dass sich v. a. in den Auen von Nethe, Aa und Emmer mächtige Lehmablagerungen finden, in die sich die Gewässer tief eingeschnitten haben. Überall dort, wo die Gewässer die Ufer unterspülen können, bilden sich Steilufer aus, die sich ideal für die Anlage der Brutröhren eignen. Weiterhin finden sich in den Fließgewässern hinreichend Kleinfische (u. a. Elritzen), die vom Eisvogel bevorzugt aufgenommen werden. Für die Bevölkerung des Kreises ist es somit nicht allzu schwer, die fliegenden Juwelen an den heimischen Gewässern zu beobachten. Aber nicht nur an den Fließgewässern ist der Eisvogel anzutreffen. Er sucht auch gerne die zahlreichen Baggerseen im Wesertal zur Nahrungssuche auf. Selbst die Badeseen zwischen Höxter und Godelheim werden von ihm regelmäßig besucht. Dass der Eisvogel ausgerechnet im Jahr 2009, in dem er zum Vogel des Jahres auserwählt wurde, nur selten anzutreffen war, ist auf den sehr harten Winter 2008/2009 zurückzuführen, den zahlreiche Vögel nicht überlebt haben

Spin dynamics of FeGa3−x_{3-x}Gex_x studied by Electron Spin Resonance

The intermetallic semiconductor FeGa$_{3}$ acquires itinerant ferromagnetism upon electron doping by a partial replacement of Ga with Ge. We studied the electron spin resonance (ESR) of high-quality single crystals of FeGa$_{3-x}$Ge$_x$ for $x$ from 0 up to 0.162 where ferromagnetic order is observed. For $x = 0$ we observed a well-defined ESR signal, indicating the presence of pre-formed magnetic moments in the semiconducting phase. Upon Ge doping the occurrence of itinerant magnetism clearly affects the ESR properties below $\approx 40$~K whereas at higher temperatures an ESR signal as seen in FeGa$_{3}$ prevails independent on the Ge-content. The present results show that the ESR of FeGa$_{3-x}$Ge$_x$ is an appropriate and direct tool to investigate the evolution of 3d-based itinerant magnetism.Comment: 12 pages, 7 figure

Risk of advanced colorectal neoplasia according to age and gender.

Colorectal cancer (CRC) is one of the leading causes of cancer related morbidity and death. Despite the fact that the mean age at diagnosis of CRC is lower in men, screening by colonoscopy or fecal occult blood test (FOBT) is initiated at same age in both genders. The prevalence of the common CRC precursor lesion, advanced adenoma, is well documented only in the screening population. The purpose of this study was to assess the risk of advanced adenoma at ages below screening age. We analyzed data from a census of 625,918 outpatient colonoscopies performed in adults in Bavaria between 2006 and 2008. A logistic regression model to determine gender- and age-specific risk of advanced neoplasia was developed. Advanced neoplasia was found in 16,740 women (4.6%) and 22,684 men (8.6%). Male sex was associated with an overall increased risk of advanced neoplasia (odds ratio 1.95; 95% confidence interval, CI, 1.91 to 2.00). At any age and in any indication group, more colonoscopies were needed in women than in men to detect advanced adenoma or cancer. At age 75 14.8 (95% CI, 14.4-15.2) screening, 18.2 (95% CI, 17.7-18.7) diagnostic, and 7.9 (95% CI, 7.6-8.2) colonoscopies to follow up on a positive FOBT (FOBT colonoscopies) were needed to find advanced adenoma in women. At age 50 39.0 (95% CI, 38.0-40.0) diagnostic, and 16.3 (95% CI, 15.7-16.9) FOBT colonoscopies were needed. Comparable numbers were reached 20 and 10 years earlier in men than in women, respectively. At any age and independent of the indication for colonoscopy, men are at higher risk of having advanced neoplasia diagnosed upon colonoscopy than women. This suggests that starting screening earlier in life in men than in women might result in a relevant increase in the detection of asymptomatic preneoplastic and neoplastic colonic lesions

Membrane interactions and alignment of structures within the HIV-1 Vpu cytoplasmic domain: effect of phosphorylation of serines 52 and 56

AbstractThe cytoplasmic domain of the HIV-1 accessory protein Vpu is involved in the binding and degradation of the viral receptor CD4. In order to analyze previous structural models in the context of membrane environments, regions of VpuCYTO incorporating particular conformational features have been synthesized and labelled with 15N at selected backbone amides. Well-oriented proton-decoupled 15N solid-state NMR spectra with 15N chemical shifts at the most upfield position indicate that the amphipathic helix within [15N-Leu 45]-Vpu27–57 strongly interacts with mechanically aligned POPC bilayers and adopts an orientation parallel to the membrane surface. No major changes in the topology of this membrane-associated amphipathic helix were observed upon phosphorylation of serine residues 52 and 56, although this modification regulates biological function of Vpu. In contrast, [15N-Ala 62]-Vpu51–81 exhibits a pronounced 15N chemical shift anisotropy

Communication Between Khepera Mini Robots For Cooperative Positioning

Grünewald M, Iske B, Klahold J, et al. Communication Between Khepera Mini Robots For Cooperative Positioning. In: Proceedings of the International Conference Automatics and Informatics’03. Vol 1. Sofia, Bulgaria; 2003: 95-98

Coordination challenges in implementing the three lines of defense model

The three lines of defense model (TLoD) aims to provide a simple and effective way to improve coordination and enhance communications on risk management and control by clarifying the essential roles and duties of different governance functions. Without effective coordination of these governance functions, work can be duplicated or key risks may be missed or misjudged. To address these challenges, professional standards recommend that the chief audit executive (CAE) coordinates activities with other internal and external governance stakeholders (assurance providers). We consider survey responses from 415 CAEs from Austria, Germany, and Switzerland to analyze determinants that help to implement the TLoD without any challenges and to explore the extent of (coordination) challenges between the internal audit function and the respective governance stakeholders. Our results show a great variance in the extent of coordination challenges dependent on different determinants and the respective governance stakeholder

Phonon-pump XUV-photoemission-probe in graphene: evidence for non-adiabatic heating of Dirac carriers by lattice deformation

We modulate the atomic structure of bilayer graphene by driving its lattice at resonance with the in-plane E1u lattice vibration at 6.3um. Using time- and angle-resolved photoemission spectroscopy (tr-ARPES) with extreme ultra-violet (XUV) pulses, we measure the response of the Dirac electrons near the K-point. We observe that lattice modulation causes anomalous carrier dynamics, with the Dirac electrons reaching lower peak temperatures and relaxing at faster rate compared to when the excitation is applied away from the phonon resonance or in monolayer samples. Frozen phonon calculations predict dramatic band structure changes when the E1u vibration is driven, which we use to explain the anomalous dynamics observed in the experiment.Comment: 16 pages, 8 figure

Ocean Floor Observation and Bathymetry System (OFOBS): A new Towed Camera/Sonar System for Deep-Sea Habitat Surveys

Towed camera systems are commonly used to collect photo and video images of the deep seafloor for a wide variety of purposes, from pure exploratory research to the development of management plans. Ongoing technological developments are increasing the quantity and quality of data collected from the deep seafloor. Despite these improvements, the area of seafloor, which towed systems can survey, optically remains limited by the rapid attenuation of visible wavelengths within water. We present an overview of a new towed camera platform integrating additional acoustical devices: the ocean floor observation and bathymetry system (OFOBS). The towed system maintains continuous direct communication via fiber optic cable with a support vessel, operational at depths up to 6000 m. In addition to collecting seafloor photo and video data, OFOBS gathers sidescan data over a 100-m swath width. OFOBS functionality is further augmented by a forward looking sonar, used to aid in hazard avoidance and real-time course correction. Data collected during the first field deployments of OFOBS, at a range of seamounts on the Langseth Ridge/Gakkel Ridge intersection (86° N, 61° E) in the high Arctic in September 2016, are presented to demonstrate the functionality of the system. Collected from a location with near continuous ice cover, this explanatory data set highlights the advantages of the system for deep-sea survey work in environments currently difficult to access for the majority of subsurface research platforms