Dynamics of the linear chain with arbitrary potential applied to quantum crystals

In one dimension, many-body matrix elements can be calculated exactly by the transfer integral (TI) method if the wave functions are assumed to be products of single-particle functions and nearest-neighbor correlation functions. In the frame of this TI approximation the phonons can be calculated without any further approximation. The theory is first developed for the case of a harmonic potential. Here the TI phonons are an excellent approximation of the well-known exact results, except for very long wavelengths. However, a Bogoliubov transformation finally yields the exact phonons. The whole procedure can be generalized for arbitrary two-body interactions, including those containing a hard core. In the generalized theory the hard-core problem has vanished completely.     

Detection of surface defects on raw steel blocks using Bayesian network classifiers

This paper proposes an approach that detects surface defects with three-dimensional characteristics on scale-covered steel blocks. The surface reflection properties of the flawless surface changes strongly. Light sectioning is used to acquire the surface range data of the steel block. These sections are arbitrarily located within a range of a few millimeters due to vibrations of the steel block on the conveyor. After the recovery of the depth map, segments of the surface are classified according to a set of extracted features by means of Bayesian network classifiers. For establishing the structure of the Bayesian network, a floating search algorithm is applied, which achieves a good tradeoff between classification performance and computational efficiency for structure learning. This search algorithm enables conditional exclusions of previously added attributes and/or arcs from the network. The experiments show that the selective unrestricted Bayesian network classifier outperforms the naïve Bayes and the tree-augmented naïve Bayes decision rules concerning the classification rate. More than 98% of the surface segments have been classified correctly.     

Untersuchung der Abreißbedingungen von Flüssigkeitstropfen durch einen auf eine Flüssigkeitsoberfläche auftreffenden Gasstrahl

Definition der Abreißbedingung durch das Kräftegleichgewicht am Flüssigkeitswulst. Messung der Gasgeschwindigkeit und der gasseitigen Grenzschichtdicke im Eindellungskrater. Daraus Berechnung der Reibungskraft sowie Berechnung der Schwerkraft und der Trägheitskraft. Ermittlung des kritischen Blaszustandes für den Beginn der Tropfenbildung und Vergleich mit Meßergebnissen. Abschätzung der versprühten Eisenmenge im Sauerstoffaufblaskonverter.     

Untersuchungen zum zeitlichen Verlauf der Erstarrung in der Randzone erstarrenden Eisens

Experimentelle Bestimmung der Dicke der erstarrenden Schicht in der Randzone erstarrender 10-kg-Stahlblöcke. Messung der Temperaturprofile in Block und Kokille. Ermittlung der Wärmestromdichten an Block- und Kokillenoberfläche sowie des Koeffizienten für den Wärmeübergang zwischen Block und Kokille. Rechnerische Überprüfung der Erstarrungsgeschwindigkeit mit einer um ein Glied für den endlichen Wärmeübergang zwischen Block und Kokille erweiterten Neumannschen Lösung. Einfluß von Oberflächenbeschaffenheit, Anfangstemperatur und Wanddicke der Kokille sowie der Gießtemperatur auf Wärmeübergang und Erstarrungsgeschwindigkeit.     

Effects of roscovitine on maintenance of the germinal vesicle in horse oocytes,subsequent nuclear maturation,and cleavage rates after intracytoplasmic sperm injection

This study was conducted to evaluate the effects of roscovitine on suppression of meiosis, subsequent meiotic maturation, and cleavage rates after intracytoplasmic sperm injection of horse oocytes. Oocytes were classified as having compact or expanded cumuli (Com or Exp oocytes) and were divided into three culture groups: 30 h culture in maturation medium (30 h Mat); 54 h culture in maturation medium (54 h Mat), or 24 h culture in medium containing 66 micro mol roscovitine l(-1) and then 30 h culture in maturation medium (Ros+M). After maturation, oocytes were subjected to intracytoplasmic sperm injection and cultured in G1.2 medium for 96 h. Among oocytes fixed immediately after roscovitine culture, 26 of 31 (84%) Com oocytes and 16 of 28 (57%) Exp oocytes were at the germinal vesicle stage (P<0.05). After maturation culture, there were no differences in maturation rates or morphological cleavage rates among treatments. Among Com oocytes, significantly more embryos in the Ros+M treatment than in the 54 h Mat treatment had cleaved with > or = two normal nuclei (63 versus 36%; P<0.05); whereas among Exp oocytes, significantly more embryos in the 30 h Mat treatment than in the Ros+M treatment (63 versus 42%; P<0.05) had cleaved with > or = two normal nuclei. The average number of nuclei in embryos at 96 h was significantly higher (P<0.05) in Ros+M Com oocytes (13.5) than in any other Com or Exp group. These results demonstrate that roscovitine can reversibly maintain equine oocytes in the germinal vesicle stage for up to 24 h, and that such suppression may increase the developmental potential of Com, but not Exp, oocytes.     

Imaging of the expansion of femtosecond-laser-produced silicon plasma atoms by off-resonant planar laser-induced fluorescence

Planar laser-induced fluorescence measurements were used to investigate the expansion dynamics of a femtosecond laser-induced plasma. Temporally and spatially resolved measurements were performed to monitor the atoms that were ablated from a silicon target. A dye laser (lambda = 288.16 nm) was used to excite fluorescence signals. The radiation of an off-resonant transition (Si 390.55 nm) was observed at different distances from the target surface. This allowed easy detection of the ablated Si atoms without problems caused by scattered laser light. Abel inversion was applied to obtain the radial distribution of the Si atoms. The atom distribution in the plasma shows some peculiarities, depending on the crater depth.     

Event-related potential indicators of text integration across sentence boundaries.

An event-related potentials (ERPs) study examined word-to-text integration processes across sentence boundaries. In a two-sentence passage, the accessibility of a referent for the first content word of the second sentence (the target word) was varied by the wording of the first sentence in one of the following ways: lexically (explicitly using a form of the target word); conceptually (using a paraphrase of the target word), and situationally (encouraging an inference concerning the referent of the target word). A baseline condition had no coreference between the two sentences. ERP results on the target word indicated multiple effects related to word identification and word-to-referent mapping processes. Both the explicit and paraphrase conditions, but not the inference condition, showed a reduced N400 relative to the baseline condition, consistent with immediate integration by lexico-semantic processes. A 300-ms effect (P300) was found in the paraphrase condition. The results were consistent with an immediate integration hypothesis and furthermore differentiated a lexical (N200), a conceptual (P300), and a situational (N400) component for this integration. The conceptual basis appears not to extend to predictive inferences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)