692 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

    Ferroelectric liquid crystal for use in a new generation of LCDs

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    The key to improvements in liquid crystalline displays lies in the continuous synthesis and studies of new kinds of liquid crystalline substances. Among them, ferroelectric compounds are the subject of much attention, due to the potential progresses in switching time, colour depth, and other qualities of liquid crystal displays. In this paper we describe the research of the physical properties of 4-(2-methylbutoxy)phenyl 4-(octyloxy)-benzoate for purposes of its potential application in liquid crystal displays

    Inverted and horizontal impacted third molars in an Early Modern skull from Wroclaw, Poland: a case report

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    Background: An impacted tooth is one of the most commonly occurring dental anomalies, although some types of impaction (i.e. inverted angulation) may be considered rare finding. There are many hypotheses regarding impaction aetiology. One of the most popular hypotheses suggested that this condition may result from insufficient space in retromolar space, other: improper angulation of tooth bud, malposition of the tooth germ or hereditary factors, insufficient interproximal attrition, ectopy or dysfunction of genes necessary for proper tooth eruption. This study aims to present the odontological and paleopathological assessment of the impacted molars observed within the skull excavated from an early modern cemetery in Wroclaw.  Materials and methods: The skull used in the study was complete and in a good state of preservation. It belonged to an adult individual whose body was buried at the former Salvator Cemetery (currently Czysty Square). The individual’s dentition was almost completely lost antemortem. Only second molars preserved within the maxillae (bilaterally) and the mandible was almost edentulous as well. The morphometric traits have been taken according to standards established by R. Martin. Macroscopic observations were supported by X-rays and computed tomography imaging.  Results: The age at death was estimated at 20–35 years. Comparison of the metric characteristics of skull with the reference material reveals that it is much smaller than the average female skull from this series. Morphometric indices calculated for both splanchocranium and neurocranium allow defining the skull and jaw as short, which could be an important factor involved in the teeth impaction.  Conclusions: Atypical impaction of the third molars could result from small size of skull and could have significantly deteriorated the quality of life of the individual.

    The sonographic morphology of musculus palmaris longus in humans

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    Background: The aim of this work was to describe morphology and morphometry of musculus palmaris longus and compare the outcome of Shaeffer’s test with ultrasound imaging.Materials and methods: Forty forearms of 20 healthy volunteers (11 females, 9 males) were tested by Shaeffer’s test and ultrasound imaging. Anthropological measurements of the forearm and ultrasound guided measurements of musculus palmaris longus were taken. The outcome was tested for statistical significanceby Fisher’s test.Results: The examination revealed agenesis of palmaris longus in 6 cases, as well as 6 muscles showing quality variations. The Shaeffer’s test gave 4 false-negative results. 28 muscles were described as spindle-shaped and 8 as pennated or bipennated. However, all the spindle-shaped muscles demonstrated a tendon going inside of the muscle’s belly ranging from 2 cm to 11.5 cm. The relation between the circumference of the forearm right below the elbow (mean: 15.38 cm, SD: 1.83 cm) and the approximated volume of the palmaris longus muscle’s belly(mean: 4.72 cm3, SD: 1.57 cm3) proved to be statistically significant (Fisher’s test p-value < 0.05).Conclusions: Uncommon morphological variations have been shown. Spindle-shaped muscles have proved to have their tendons continued inside them. Palmaris longus muscle’s belly has proved to take significant amount of volume within the proximal forearm. Shaeffer’s test has shown to have 10% false-negative ratio

    Computer faceted thermal model of helicopter

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    The paper presents a computer Faceted Thermal Target Model of helicopter (FTTM) describing radiative properties of target in the infrared. The model is predestined for target simulation in analyses of influence of thermal-scene conditions on the possibilities of target detection by a thermodetection system. This is a faceted model describing the target as a set of facets. The set of data for the model of helicopter requires information on the shape and dimensions of the target as well as on temperature distribution and emissivity coefficient of its surface. The model enables to determine emission of radiation from the target surface for various directions and distances of detection. It makes possible to obtain the data necessary to design devices for infrared recognition with a limited application of costly experimental investigations. 1

    Ossa Sesamoidea — prevalence of sesamoid bones in human hands

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    Background: This study describes the morphology of sesamoid bones in the human hand. Ultrasound imaging was used to record the presence and measurements of sesamoids in 120 hands of 60 healthy, young adults of Caucasian ethnicity. Materials and methods: The mean number of sesamoid bones was 4.16 in the left hand and 4.03 in the right hand. 21.6% of cases showed asymmetry between the right hand and the left. There was a significant difference in the prevalence of sesamoid bones between right and left hand in males in this study. Females show a higher incidence of sesamoid bones overall, but do not demonstrate a significant difference between the sides. Results: Prevalence findings: Two in the 1st metacarpophalangeal joint (MCPJ) in 99.2% of cases, with 1 case of a single bone. One in the 2nd MCPJ in 43.3% of cases. One in the 5th MCPJ in 84.2% of cases. One in the 1st interphalangeal joint (IPJ) in 83.4% of cases. Aside from that there was 1 case of sesamoid in the 3rd MCPJ and separate case of sesamoid in the 3rd proximal IPJ. Conclusions: Moreover, this study discusses discrepancies of opinion regarding sesamoid bones in morphological research

    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

    NIEOCZYWISTA ROLA RUIN POPRZEMYSŁOWYCH W KRAJOBRAZIE KULTUROWYM POLSKI

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    The paper deals with the issues related to protection of industrial heritage. Authors focused on the problem of derelict industrial objects in the state of disrepair, which might be considered as historic ruins. The discussed subject was settled in the historical and socio-cultural context. The importance of perception and identity was underlined as crucial factors for successful heritage protection, including former industrial sites. This is followed by the critical analysis of selected cases of ruined factories. Various approaches to the post-industrial ruins ware identified. The location type as well as local society approach to the industrial pasts were identified as the most important aspects determining adopted heritage protection scenarios. The role of contemporary pop- and digital cultures was also identified in respect of experience authenticity.Artykuł zajmuje się zagadnieniami związanymi z ochroną dziedzictwa przemysłowego. Autorzy skupili się na problemie zaniedbanych obiektów przemysłowych w stanie ruiny, które można uznać za historyczne. Omawiany temat został rozstrzygnięty w kontekście historycznym i społeczno-kulturowym. Znaczenie percepcji i tożsamości podkreśla się jako kluczowe czynniki skutecznej ochrony dziedzictwa, w tym dawnych terenów przemysłowych. Sporządzono krytyczną analizę wybranych przypadków fabryk znajdujących się w stanie ruiny. Podano różne podejścia do ruin poprzemysłowych. Lokalizacja oraz podejście społeczności lokalnej do przeszłości przemysłowej to najważniejsze aspekty określające przyjęte scenariusze ochrony dziedzictwa. Rola współczesnej popkultur i cyfryzacji została zidentyfikowana w odniesieniu do autentyczności doświadczeni

    Curved Noncommutative Tori as Leibniz Quantum Compact Metric Spaces

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    We prove that curved noncommutative tori, introduced by Dabrowski and Sitarz, are Leibniz quantum compact metric spaces and that they form a continuous family over the group of invertible matrices with entries in the commutant of the quantum tori in the regular representation, when this group is endowed with a natural length function.Comment: 16 Pages, v3: accepted in Journal of Math. Physic

    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
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