277 research outputs found

    Synthesis and Properties of High Tilted Antiferroelectric Esters with Partially Fluorinated Alkoxyalkoxy Terminal Chains

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    Novel chiral esters with partially fluorinated alkoxyalkoxy terminal chains are described. Their phase transition temperatures, enthalpies, and electrooptical properties are reported. A helical pitch in pure compounds and their mixtures based on selective reflection of light is also characterized

    One-variable word equations in linear time

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    In this paper we consider word equations with one variable (and arbitrary many appearances of it). A recent technique of recompression, which is applicable to general word equations, is shown to be suitable also in this case. While in general case it is non-deterministic, it determinises in case of one variable and the obtained running time is O(n + #_X log n), where #_X is the number of appearances of the variable in the equation. This matches the previously-best algorithm due to D\k{a}browski and Plandowski. Then, using a couple of heuristics as well as more detailed time analysis the running time is lowered to O(n) in RAM model. Unfortunately no new properties of solutions are shown.Comment: submitted to a journal, general overhaul over the previous versio

    Quantum phantom cosmology

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    We apply the formalism of quantum cosmology to models containing a phantom field. Three models are discussed explicitly: a toy model, a model with an exponential phantom potential, and a model with phantom field accompanied by a negative cosmological constant. In all these cases we calculate the classical trajectories in configuration space and give solutions to the Wheeler-DeWitt equation in quantum cosmology. In the cases of the toy model and the model with exponential potential we are able to solve the Wheeler-DeWitt equation exactly. For comparison, we also give the corresponding solutions for an ordinary scalar field. We discuss in particular the behaviour of wave packets in minisuperspace. For the phantom field these packets disperse in the region that corresponds to the Big Rip singularity. This thus constitutes a genuine quantum region at large scales, described by a regular solution of the Wheeler-DeWitt equation. For the ordinary scalar field, the Big-Bang singularity is avoided. Some remarks on the arrow of time in phantom models as well as on the relation of phantom models to loop quantum cosmology are given.Comment: 21 pages, 6 figure

    Anatomical classification of the shape and topography of the operated stomach

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    The aim of the study was to present the classification of anatomical variances of the operated stomach, based on the radiological and historical data. Different anatomical variations of the operated organ were revealed in 431 out of 2034 patients examined in years 2006-2010. Four primary groups were established: abnormal position along longitudinal (I) and horizontal axis (II), as well as abnormal shape (III) and stomach connections (IV). An additional group (V) encloses mixed forms that connect features of two or more primary groups. The first group contains the partial and total translocation of the stomach into the thoracic cavity after the partial or total esophagectomy. Depends on the applied surgical techniques used during the total esophagectomy, the stomach could be located in the front or back to the pericardial sac. An elongated and gestrectatical form often with signs of pylorostenosis is visible in patients treated by the vagotomy. The consequences of fundoplication included: lack or narrow cardiac angle, and often mild form of the stomach cascade. The most common abnormal shape of the stomach was secondary to the gastrectomy and gastric bending. The final organ shape depends on the type of applied surgical procedure that maintains physiological connection with the duodenum or un-anatomical one, mostly with the jejunal loop. In banding, the body of the stomach forms hourglass on the level of the artificial adjustable band, typically fitted for the surgical slim purpose

    Characterisation of silicon strip detectors with a binary readout chip for X-ray imaging

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    In this paper we describe the development of a multichannel readout system for X-ray measurements using silicon strip detectors. The developed system is based on a binary readout architecture and optimised for detection of X-rays of energies in the range 6}30 keV. The critical component of the system is the 32-channel front-end chip, RX32N, which has been optimised for low noise performance, small channel to channel variation and high counting rate operation. The performance of the chip is demonstrated by measurements of complex X-ray spectra using silicon strip and pad detectors. The obtained results allow to use the system at room temperature with the detection threshold in the range from 500 to 10 000 electrons, which is enough in many crystallographic and medical imaging applications. ( 2000 Elsevier Scienc

    The impact of postglacial palaeoenvironmental changes on the properties of sediments in the ket tle hole at Jurki (NE Poland)

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    This research is focused on a small kettle hole located within the Morąg moraines (Iława Lake District, NE Poland). The study objective was to determine the impact of palaeoenvironmental changes on properties of sediments filling the bot tom of the kettle hole. Sedimentological, geochemical, and palaeobotanical studies enabled us to distinguish several development phases of the kettle hole, and cluster analysis performed on physicochemical data yielded seven local geochemical zones (JuI/I to JuI/VII). The beginning of biogenic sedimentation in the conditions of a small water body, functioning in the Late Glacial period (4.20–4.10 m), was determined on the basis of palaeobotanical research. Sediments deposited in the lake during its further evolution were rich in microelements such as Ca, Na, Mg, and K, and to a smaller extent – Fe and Mn (JuI/I–III local geochemical zones). The Late Glacial lacustrine period ended with the accumulation of very silty, pollen-free gyttja, with a stratigraphic hiatus (JuI/IV, 3.40–3.20 m). The sediments were enriched with SiO2ter, which indicates an increased rate of slope erosion, and concretions of Fe-Mn occurring below this layer (JuIII) provide evidence for lowering of the water level and even desiccation. In the Holocene, the lacustrine period ended with the accumulation of coarse detrital gyttja (3.20–2.60 m). Palaeobotanical data indicate that the next group of sediments were deposited in the Late Subboreal and Subatlantic periods (2.60–0.0 cm, JuI/V–VII; sedge peat). Their properties were varied and related to hydrologic conditions, limited denudation, and vegetation succession. There was also a significant change in the trophic conditions of the water and consequently in the sediments of the kettle hole, which changed during the lacustrine period from basic to acid, and strongly acid in the surface layer. This reaction may be related to a change in the water regime as well as to hu man impact in the environment, which led to the colonization of the peat bog by Sphagnum moss

    Post-traumatic diaphragma hernia

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    W niniejszym artykule przedstawiono przypadek 22-letniego mężczyzny z pourazową przepukliną przeponową, do powstania której doszło w następstwie tępego urazu klatki piersiowej i nadbrzusza. Na podstawie przeprowadzonych badań diagnostycznych rozpoznano pourazową przepuklinę przeponową lewostronną. Chorego operowano w trybie planowym. W trakcie laparotomii stwierdzono rozerwanie lewej kopuły przepony, przez które żołądek został w większej części przemieszczony do klatki piersiowej. Żołądek odprowadzono do jamy brzusznej i wykonano plastykę przepukliny pourazowej przepony, zeszywając ją przy rozprężonym płucu. W przebiegu pooperacyjnym wystąpiła odma opłucnowa lewostronna, którą leczono, wykonując drenaż lewej jamy opłucnowej. Drenaż usunięto w 4. dobie po operacji, po uzyskaniu upowietrznienia dolnego pola lewego płuca. Pacjenta wypisano z kliniki w 5. dobie po operacji w stanie dobrym.A case of a 22 year-old male with post-traumatic diaphragmatic hernia resulting from a blunt injury of chest and epigastrium is presented. Based on diagnostic procedures, left-sided posttraumatic diaphragmatic hernia was diagnosed. A scheduled surgical procedure was performed in the patient. A laparotomy revealed a rupture of the left diaphragmatic dome which allowed the displacement of the major part of the stomach to the thoracic cavity. The stomach was replaced in the abdominal cavity and a hernioplasty was performed by suturing the diaphragm while keeping the lungs expanded. During the postoperative course, left-sided pneumothorax occurred which was treated with left thoracic cavity drainage. The drain was removed on the fourth day after the operation when aeration of the lower field of the left lung was achieved. The patient was discharged in good condition on the fifth day after operation

    Megacolon imitating emphysema in the course of diaphragmatic hernia

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    61-year old man with fever, diarrhoea, weight loss has been admitted to the hospital. Nine years earlier an air bubble in the lower part of the left lung was recognised during the chest x-ray, four years later diagnostic studies have shown a megacolon situated in the chest that significantly pressed on the flesh of the left lung and shifted the mediastinum to the right side. At that time the patient did not agree for an operation treatment. He decided for surgery in May 2002. During the operation the presence of an enormous large intestine of the megacolon type has been determined which could be found there due to diaphragm loss. The megacolon and spleen were surgically removed and the injured diaphragm was sutured. After 2 years a clinical and functional examinations of the respiratory system were performed. There was an improvement of the exercise capacity, recession of restriction in functional examinations and an increase in body mass

    The Hubble Diagram of Type Ia Supernovae in Non-Uniform Pressure Universes

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    We use the redshift-magnitude relation, as derived by D\c{a}browski (1995), for the two exact non-uniform pressure spherically symmetric Stephani universes with the observer positioned at the center of symmetry, to test the agreement of these models with recent observations of high redshift type Ia supernovae (SNIa), as reported in Perlmutter et al. (1997). By a particular choice of model parameters, we show that these models give an excellent fit to the observed redshifts and (corrected) B band apparent magnitudes of the SNIa data, but for an age of the Universe which is typically about two Gyr greater than in the corresponding Friedmann model. Based on a value of H065H_0 \sim 65 and assuming Λ0\Lambda \geq 0, the P97 data implies a Friedmann age of at most 13 Gyr and in fact a best-fit (for q0=0.5q_0 = 0.5) age of only 10 Gyr. Our Stephani models, on the other hand, can give a good fit to the P97 data with an age of up to 15 Gyr and could, therefore, significantly alleviate the conflict between recent cosmological and astrophysical age predictions. The choice of model parameters is quite robust: one requires only that the non-uniform pressure parameter, aa, in one of the models is negative and satisfies |a| \lte 3 km2^2 s2^{-2} Mpc1^{-1}. By allowing slightly larger, negative, values of aa one may `fine tune' the model to give an even better fit to the P97 data.Comment: 36 pages, 2 tables, 6 figures, AAS Latex 4.0, vastly revised version, new title and abstract, to appear in Ap
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