3,542 research outputs found

    Mercury's resonant rotation from secular orbital elements

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    We used recently produced Solar System ephemerides, which incorporate two years of ranging observations to the MESSENGER spacecraft, to extract the secular orbital elements for Mercury and associated uncertainties. As Mercury is in a stable 3:2 spin-orbit resonance these values constitute an important reference for the planet's measured rotational parameters, which in turn strongly bear on physical interpretation of Mercury's interior structure. In particular, we derive a mean orbital period of 87.96934962 ±\pm 0.00000037 days and (assuming a perfect resonance) a spin rate of 6.138506839 ±\pm 0.000000028 degree/day. The difference between this rotation rate and the currently adopted rotation rate (Archinal et al, 2011) corresponds to a longitudinal displacement of approx. 67 m per year at the equator. Moreover, we present a basic approach for the calculation of the orientation of the instantaneous Laplace and Cassini planes of Mercury. The analysis allows us to assess the uncertainties in physical parameters of the planet when derived from observations of Mercury's rotation

    Functional Sites in Structure and Sequence. Protein Active Sites and miRNA Target Recognition -

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    The number of protein three-dimensional structures is increasing steeply, and structural genomics projects aim to solve the structures for all proteins as a means to understanding function. In the first part of my thesis, I developed a method for the comparison of local structural patterns (e.g. enzyme active sites) that provides a reliable statistical measure to discern meaningful matches from noise. The method is complementary to structural alignment as it is able to confirm functional similarities suggested by an overall similar structure but also detects functional similarities between different folds. An easy-to-use interface is available on the Internet for functional annotation of protein structures (http://pints.embl.de). In the second part of my thesis, I present a computational screen for microRNA (miRNA) targets in Drosophila. miRNAs are short RNAs that inhibit translation of target messenger RNAs in animals by binding to complementary sites in their 3ďż˝ untranslated regions. Target predictions were urgently needed as targets were known for only three of the more than 700 miRNAs. Of my predictions, six were validated experimentally and others are likely to be functional, making the results a useful resource for miRNA research. The screen extended miRNA function to pathway control, nervous system development and regulation of metabolism, and revealed that one miRNA typically regulates several targets but also that one gene is likely to be targeted by several miRNAs

    Cupping: A Healing Method in West Sumatra (Indonesia) A Semiotic Perspective

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    This article investigates cupping a widespread traditional healing method in West Sumatra. However, the way cupping is used in some areas of the Malay-speaking region is unique in the sense that it uses buffalo horns during the cupping process. The author argues that for the matrilineal society of the Minangkabau in West Sumatra, the buffalo horn has a special connotation as it is crucial in many elements of their culture. By considering a semiotic research approach, the author wants to offer a new perspective on the Minangkabau and their culture. By doing so, the author intends to participate in the discussion about signs and symbols in the field of Minangkabau studies. In qualitative research that comprised fieldwork, traditional healers were observed and interviewed. The peculiar cupping technique was analysed, and a semiotic perspective seemed most fitting. It was detected that the usage of horns contains a specific meaning for the Minangkabau culture

    Discovery of functional elements in 12 Drosophila genomes using evolutionary signatures

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    Sequencing of multiple related species followed by comparative genomics analysis constitutes a powerful approach for the systematic understanding of any genome. Here, we use the genomes of 12 Drosophila species for the de novo discovery of functional elements in the fly. Each type of functional element shows characteristic patterns of change, or 'evolutionary signatures', dictated by its precise selective constraints. Such signatures enable recognition of new protein-coding genes and exons, spurious and incorrect gene annotations, and numerous unusual gene structures, including abundant stop-codon readthrough. Similarly, we predict non-protein-coding RNA genes and structures, and new microRNA (miRNA) genes. We provide evidence of miRNA processing and functionality from both hairpin arms and both DNA strands. We identify several classes of pre- and post-transcriptional regulatory motifs, and predict individual motif instances with high confidence. We also study how discovery power scales with the divergence and number of species compared, and we provide general guidelines for comparative studies

    Sandwichbauteile mit gefalteten und gekrĂĽmmten Betondeckschichten

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    In der aktuellen Baupraxis werden mit Standard-Tragelementen meist rechteckige Grundrisse erzeugt. Ausgenommen sind weitspannende Konstruktionen, wie Kuppeln von Domen oder Kühltürme von Kraftwerken. Im Gegensatz dazu waren Schalen aus Stahlbeton im Hochbau im vergangenen Jahrhundert weit verbreitet. Dazu wurden in der Regel große Strukturen in situ betoniert. Zusätzlich wurden weit spannende Fertigteile mit relativ geringer Breite hergestellt. Diese Faltwerke oder doppelt gekrümmten Elemente wurden zum Teil mit einer Dicke von weniger als 10 cm realisiert und häuf g im sofortigen Verbund vorgespannt. Bedenken hinsichtlich der Korrosionsbeständigkeit können ein Grund dafür gewesen sein, dass solche Konstruktionen heute üblicherweise nicht mehr gebaut werden. [Aus. Einleitung]In current building practice, standard load-bearing elements are mostly of rectangular shape. Exceptions are large shell structures, such as cupolas of domes or cooling towers of power plants. In contrast, shells made of reinforced concrete (RC were widely applied for building construction in the last century. For this purpose, large structures were usually cast in situ. Additionally, long-span precast elements with limited width were produced. These folded plate or doubly curved elements were realised with a thickness of less than 10 cm and usually prestressed with steel tendons. Concerns regarding the corrosion resistance might have been a reason that such constructions are not build regularly today. [Off: Introduction

    Clock transition by continuous dynamical decoupling of a three-level system

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    We present a novel continuous dynamical decoupling scheme for the construction of a robust qubit in a three-level system. By means of a clock transition adjustment, we first show how robustness to environmental noise is achieved, while eliminating drive-noise, to first-order. We demonstrate this scheme with the spin sub-levels of the NV-centre's electronic ground state. By applying drive fields with moderate Rabi frequencies, the drive noise is eliminated and an improvement of 2 orders of magnitude in the coherence time is obtained compared to the pure dephasing time. We then show how the clock transition adjustment can be tuned to eliminate also the second-order effect of the environmental noise with moderate drive fields. A further improvement of more than 1 order of magnitude in the coherence time is expected and confirmed by simulations. Hence, our scheme prolongs the coherence time towards the lifetime-limit using a relatively simple experimental setup.Comment: 7 pages, 5 figure

    Learning the transcriptional regulatory code

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