50 research outputs found

    Transit timing at Torun Center for Astronomy

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    The transit monitoring is one of well-known methods for discovering and observing new extrasolar planets. Among various advantages, this way of searching other worlds does not require complex and expensive equipment - it can be performed with a relatively small telescope and high-quality CCD camera. At the Center for Astronomy of Nicolaus Copernicus University in Toru«, Poland, we collect observational data using the 60-cm Cassegrain telescope hoping that it would be possible to discover new objects in already known planetary systems using the transit timing variation method. Our observations are a part of a biggercooperation between observatories from many countries

    A large topographic feature on the surface of the trans-Neptunian object (307261) 2002 MS4_4 measured from stellar occultations

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    This work aims at constraining the size, shape, and geometric albedo of the dwarf planet candidate 2002 MS4 through the analysis of nine stellar occultation events. Using multichord detection, we also studied the object's topography by analyzing the obtained limb and the residuals between observed chords and the best-fitted ellipse. We predicted and organized the observational campaigns of nine stellar occultations by 2002 MS4 between 2019 and 2022, resulting in two single-chord events, four double-chord detections, and three events with three to up to sixty-one positive chords. Using 13 selected chords from the 8 August 2020 event, we determined the global elliptical limb of 2002 MS4. The best-fitted ellipse, combined with the object's rotational information from the literature, constrains the object's size, shape, and albedo. Additionally, we developed a new method to characterize topography features on the object's limb. The global limb has a semi-major axis of 412 ±\pm 10 km, a semi-minor axis of 385 ±\pm 17 km, and the position angle of the minor axis is 121 ^\circ ±\pm 16^\circ. From this instantaneous limb, we obtained 2002 MS4's geometric albedo and the projected area-equivalent diameter. Significant deviations from the fitted ellipse in the northernmost limb are detected from multiple sites highlighting three distinct topographic features: one 11 km depth depression followed by a 255+4^{+4}_{-5} km height elevation next to a crater-like depression with an extension of 322 ±\pm 39 km and 45.1 ±\pm 1.5 km deep. Our results present an object that is \approx138 km smaller in diameter than derived from thermal data, possibly indicating the presence of a so-far unknown satellite. However, within the error bars, the geometric albedo in the V-band agrees with the results published in the literature, even with the radiometric-derived albedo

    Genome Stability of Lyme Disease Spirochetes: Comparative Genomics of Borrelia burgdorferi Plasmids

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    Lyme disease is the most common tick-borne human illness in North America. In order to understand the molecular pathogenesis, natural diversity, population structure and epizootic spread of the North American Lyme agent, Borrelia burgdorferi sensu stricto, a much better understanding of the natural diversity of its genome will be required. Towards this end we present a comparative analysis of the nucleotide sequences of the numerous plasmids of B. burgdorferi isolates B31, N40, JD1 and 297. These strains were chosen because they include the three most commonly studied laboratory strains, and because they represent different major genetic lineages and so are informative regarding the genetic diversity and evolution of this organism. A unique feature of Borrelia genomes is that they carry a large number of linear and circular plasmids, and this work shows that strains N40, JD1, 297 and B31 carry related but non-identical sets of 16, 20, 19 and 21 plasmids, respectively, that comprise 33–40% of their genomes. We deduce that there are at least 28 plasmid compatibility types among the four strains. The B. burgdorferi ∼900 Kbp linear chromosomes are evolutionarily exceptionally stable, except for a short ≤20 Kbp plasmid-like section at the right end. A few of the plasmids, including the linear lp54 and circular cp26, are also very stable. We show here that the other plasmids, especially the linear ones, are considerably more variable. Nearly all of the linear plasmids have undergone one or more substantial inter-plasmid rearrangements since their last common ancestor. In spite of these rearrangements and differences in plasmid contents, the overall gene complement of the different isolates has remained relatively constant

    Curvature in Biological Systems: Its Quantification, Emergence, and Implications across the Scales

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    © 2023 The Authors. Advanced Materials published by Wiley-VCH GmbH. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.Surface curvature both emerges from, and influences the behavior of, living objects at length scales ranging from cell membranes to single cells to tissues and organs. The relevance of surface curvature in biology is supported by numerous experimental and theoretical investigations in recent years. In this review, first, a brief introduction to the key ideas of surface curvature in the context of biological systems is given and the challenges that arise when measuring surface curvature are discussed. Giving an overview of the emergence of curvature in biological systems, its significance at different length scales becomes apparent. On the other hand, summarizing current findings also shows that both single cells and entire cell sheets, tissues or organisms respond to curvature by modulating their shape and their migration behavior. Finally, the interplay between the distribution of morphogens or micro-organisms and the emergence of curvature across length scales is addressed with examples demonstrating these key mechanistic principles of morphogenesis. Overall, this review highlights that curved interfaces are not merely a passive by-product of the chemical, biological, and mechanical processes but that curvature acts also as a signal that co-determines these processes.A.P.G.C. and P.R.F. acknowledge the funding from Fundação para a Ciência e Tecnologia (Portugal), through IDMEC, under LAETA project UIDB/50022/2020. T.H.V.P. acknowledges the funding from Fundação para a Ciência e Tecnologia (Portugal), through Ph.D. Grant 2020.04417.BD. A.S. acknowledges that this work was partially supported by the ATTRACT Investigator Grant (no. A17/MS/11572821/MBRACE, to A.S.) from the Luxembourg National Research Fund. The author thanks Gerardo Ceada for his help in the graphical representations. N.A.K. acknowledges support from the European Research Council (grant 851960) and the Gravitation Program “Materials Driven Regeneration,” funded by the Netherlands Organization for Scientific Research (024.003.013). M.B.A. acknowledges support from the French National Research Agency (grant ANR-201-8-CE1-3-0008 for the project “Epimorph”). G.E.S.T. acknowledges funding by the Australian Research Council through project DP200102593. A.C. acknowledges the funding from the Deutsche Forschungsgemeinschaft (DFG) Emmy Noether Grant CI 203/-2 1, the Spanish Ministry of Science and Innovation (PID2021-123013O-BI00) and the IKERBASQUE Basque Foundation for Science.Peer reviewe

    Wpływ podłoża i sterowania fertygacją na wielkość plonu i jakość owoców ogórka szklarniowego

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    Yield and fruit quality of cucumber depend on such factors as plant cultivar, plant nutrition and the cultivation method. The presented paper contains results confirming the usefulness of rockwool and coconut fibre as well as the application of the fertigation system in cucumber growing. Studies on the growing of cucumber Onyks F1 cultivar were carried out in the years 2003–2005 in an unheated greenhouse. A two-factorial experiment was established. One experimental factor consisted in the fertigation control methods including Soltimer device and the starting tray. The other factor included substrate types: rockwool Agroban and coconut fibre Ceres. Plant distribution was 2 plants per one square metre. On the basis of the presented studies, it was found that greenhouse cucumber yielding was influenced by the frequency of nutrient supply, by climatic conditions in the given year and by the applied substrate type. The applied media of rockwool Agroban and coconut fibre Ceres did not exert any influence on plant yielding. On the other hand, a significant effect on the total and the marketable fruit yield was exerted by the cooperation between the fertigation control method and the substrate type.O plonie ogórka i jakości jego owoców decydują takie czynniki, jak: odmiana, podłoże, odżywianie roślin i pielęgnacja. W pracy tej sprawdzano przydatność wełny mineralnej i włókna kokosowego przy zastosowaniu fertygacji. Badania nad ogórkiem przeprowadzono w latach 2003–2005 w szklarni nieogrzewanej. Do badań użyto odmianę Onyks F1. Założono doświadczenie dwuczynnikowe. Jednym czynnikiem były rodzaje sterowania fertygacją: Soltimer i taca startowa, a drugim podłoża: wełna mineralna Agroban i włókno kokosowe Ceres. Zagęszczenie wynosiło 2 rośliny na 1 m2. Na podstawie przeprowadzonych badań stwierdzono wpływ częstotliwości podawania pożywki w zależności od warunków klimatycznych w danym roku i od podłoża na zróżnicowanie plonowania ogórka szklarniowego. Zastosowane podłoża z wełny mineralnej Agroban i włókna kokosowego Ceres nie miały wpływu na plonowanie roślin. Natomiast istotny wpływ na plon ogólny i handlowy miało współdziałanie sterowania fertygacją z podłożem

    RELAP5/MOD3 model and transient analyses for the MARIA research reactor in Poland

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    The RELAP5/MOD3 input data model of the MARIA research reactor has been developed to provide the capability for the analysis of the reactor core under loss of flow and reactivity insertion transients. The model was qualified against the reactor data at steady state conditions and, additionally, against the existing reliable experimental data for a transient initiated by the reactor scram. The results obtained with the code agree well with the experimental data. The RELAP transient simulation was performed for loss of forced flow accidents including two scenarios with protected and unprotected (no scram) reactor core. Calculations allow estimating time margin for reactor scram initiation and reactivity feedbacks contribution to the results. The presented input data model should be treated as the first step for developing of the model including the whole primary cooling circuit of the reactor

    Porównanie mięsa wykrawanego na ciepło i po wychłodzeniu w produkcji kiełbas drobnorozdrobnionych

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    Same physico-chemical properties of hot cut and chilled longissimus dorsi muscle removed pre-rigor or after chilling process were compared. The hot processed LD muscles of three experimental groups showed higher pH and WHC and much lower free water content than chilled muscles. Their effect upon the yield and same quality characteristics of model comminuted sausages was determined. The differences in consistency and juiceness of model sausages were significant.Porównanie właściwości mięsa wykrawanego na ciepło i po wychłodzeniu. Doświadczenie przeprowadzono na mięśniach longissimus dorsi wykrawanych w czasie 1,5 h po uboju i po wychłodzeniu (24 h). Każda grupa doświadczalna składała się z 7 zwierząt: jałowic, wolców i krów. Wykonano pomiary następujących właściwości fizykochemicznych mięśnia: temperatura, pH, jasność barwy, wodochłonność i zawartość wody wolnej. W modelowych kiełbasach drobnorozdrobnionych określono ubytki cieplne oraz ubytki podczas składowania, a także niektóre cechy jakościowe takie jak konsystencję, soczystość i kruchość. Mięśnie wykrawane na ciepło wszystkich grup doświadczalnych posiadały wyższe pH i wyższą wodochłonność, natomiast dużo niższą zawartość wody wolnej niż mięśnie po wychłodzeniu. Różnice w konsystencji i soczystości kiełbas modelowych były statystycznie istotne. Uzyskane wyniki zostały sprawdzone w skali przemysłowej w produkcji kiełbas parzonych. Wydajność kiełbas produkowanych z dodatkiem wołowiny wykrawanej na ciepło była wyższa niż przy użyciu mięsa wychłodzonego
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