371 research outputs found

    Close to threshold eta' meson production in proton-proton collisions at COSY-11

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    Intensive quest for the eta and eta' bound states is currently ongoing at both theoretical and experimental levels e.g. at COSY, ELSA, GSI, JINR, JPARC, LPI, and MAMI. These studies were already supported by data provided by the COSY-11 collaboration including determination of the total width of the eta' meson. In addition, the first rough estimation of the eta'-N interaction from the excitation function of the cross section for the pp-->pp eta' reaction was also performed. Recent precise measurement in this field from the COSY-11 experiment allows to summarize results on the eta' meson production cross section in proton-proton collisions at COSY-11.Comment: 4 pages, 1 figure, presented at 13th International Workshop on Meson Production, Properties and Interaction, Cracow, Poland, 29th May - 3rd June 201

    Assessment of the course of the great cardiac vein in a selected number of human hearts

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    The aim of this work is to determine morphological and topographical aspects of the great cardiac vein, especially its relation to the branches of the left coronary artery. The examination of the cardiac veins was carried out on 36 specimens of hearts of both sexes aged between 12 and 70 and without any known history of change in cardiac pathology. The techniques applied by us were anatomical dissection and retrograde injection of the coronary vessels with Polimal 100, Polimal 150 and Durakryl resin. We examined the topography and morphology of the great cardiac vein and the mutual correlation between the great cardiac vein and the branches of the left coronary artery

    Productivity of Grasslands in Wielkopolska in Conditions of Weather Variables Changes in the Last 34 Years

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    The purpose of this study was the assessment of the effect of climatic changes since 1985 on the productivity of grasslands in Wielkopolska region (Poland). The weather data (precipitation sum, mean, maximum and minimum air temperature, insolation, relative air humidity and wind speed) were collected from 1985 to 2018 at five weather stations located in the region that belong to the Institute of Meteorology and Water Management. Using this data, trends of Standardized Precipitation Evapotranspiration Index (SPEI) were determined. Grassland productivity was estimated from data collected by the Central Statistical Office, that refer to meadow hay production for each commune and each of the three regrowths. For the analysis of the effects of climatic trends on grassland productivity in Wielkopolska, linear regression was used. It was concluded that the climatic changes in the Wielkopolska region for the last 34 years were expressed as the increase of mean yearly air temperature, precipitation sum, as well as of the Penman-Monteith evapotranspiration (ET). The significance of these changes was evidenced for air temperature (p= 0.0006) and for the ET (p= 0.004). The analysis carried out for individual months showed that (i) mean air temperature was significantly rising in summer, from June to September, as well in April and November, (ii) precipitation sum changes were not significant, and (iii) the ET was rising in April and September. The significant SPEI trends analysed for different periods (from 1 to 12 months) indicate that soil moisture conditions in the region were deteriorating. No significant effect of the SPEI trends on annual grassland yield and the yield of 2nd regrowth in Wielkopolska was found. The significant relationship was found for the 3-months SPEI in spring which negatively affected hay yield in the first regrowth (p= 0.011- 0.021) and for SPEI calculated for different periods decreasing the grassland productivity in third regrowth

    Safety verification of asynchronous pushdown systems with shaped stacks

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    In this paper, we study the program-point reachability problem of concurrent pushdown systems that communicate via unbounded and unordered message buffers. Our goal is to relax the common restriction that messages can only be retrieved by a pushdown process when its stack is empty. We use the notion of partially commutative context-free grammars to describe a new class of asynchronously communicating pushdown systems with a mild shape constraint on the stacks for which the program-point coverability problem remains decidable. Stacks that fit the shape constraint may reach arbitrary heights; further a process may execute any communication action (be it process creation, message send or retrieval) whether or not its stack is empty. This class extends previous computational models studied in the context of asynchronous programs, and enables the safety verification of a large class of message passing programs

    The ossification of the metacarpal and phalangeal bones in human foetuses

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    An evaluation was made of the ossification level of the metacarpal and phalangeal bones in human foetuses of both sexes from the 4th to the 9th month of gestation. Our results indicate that ossification of phalangeal bones 1 to 5 always started at the distal end of the phalanx and endochondral ossification prevailed in the proximal phalanx of the thumb

    The risk of falling

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    Abstract: In the late 1960s, much interest was raised in regard to biomedical applications of various ceramic materials. A little bit later, such materials were named bioceramics. This review is limited to bioceramics prepared from calcium orthophosphates only, which belong to the categories of bioactive and bioresorbable compounds. There have been a number of important advances in this field during the past 30–40 years. Namely, by structural and compositional control, it became possible to choose whether calcium orthophosphate bioceramics were biologically stable once incorporated within the skeletal structure or whether they were resorbed over time. At the turn of the millennium, a new concept of calcium orthophosphate bioceramics—which is able to promote regeneration of bones—was developed. Presently, calcium orthophosphate bioceramics are available in the form of particulates, blocks, cements, coatings, customized designs for specific applications and as injectable composites in a polymer carrier. Current biomedical applications include artificial replacements for hips, knees, teeth, tendons and ligaments, as well as repair for periodontal disease, maxillofacial reconstruction, augmentation and stabilization of the jawbone, spinal fusion and bone fillers after tumor surgery. Exploratory studies demonstrate potential applications of calcium orthophosphate bioceramics as scaffolds, drug delivery systems, as well as carriers of growth factors, bioactive peptides and/or various types of cells for tissue engineering purposes

    Going higher in the First-order Quantifier Alternation Hierarchy on Words

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    We investigate the quantifier alternation hierarchy in first-order logic on finite words. Levels in this hierarchy are defined by counting the number of quantifier alternations in formulas. We prove that one can decide membership of a regular language to the levels BÎŁ2\mathcal{B}\Sigma_2 (boolean combination of formulas having only 1 alternation) and ÎŁ3\Sigma_3 (formulas having only 2 alternations beginning with an existential block). Our proof works by considering a deeper problem, called separation, which, once solved for lower levels, allows us to solve membership for higher levels

    System Response Kernel Calculation for List-mode Reconstruction in Strip PET Detector

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    Reconstruction of the image in Positron Emission Tomographs (PET) requires the knowledge of the system response kernel which describes the contribution of each pixel (voxel) to each tube of response (TOR). This is especially important in list-mode reconstruction systems, where an efficient analytical approximation of such function is required. In this contribution, we present a derivation of the system response kernel for a novel 2D strip PET.Comment: 10 pages, 2 figures; Presented at Symposium on applied nuclear physics and innovative technologies, Cracow, 03-06 June 201
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