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  • 1
    Digitale Medien
    Digitale Medien
    The nuclear RNase III Drosha initiates microRNA processing (2003)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 425 (2003), S. 415-419 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Hundreds of small RNAs of ∼22 nucleotides, collectively named microRNAs (miRNAs), have been discovered recently in animals and plants. Although their functions are being unravelled, their mechanism of biogenesis remains poorly understood. miRNAs are transcribed as long primary transcripts ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/nature01957
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  • 2
    Digitale Medien
    Digitale Medien
    Prevalence of human foamy virus-related sequences in the Korean population (1998)
    Springer
    Journal of biomedical science 5 (1998), S. 267-273 
    Details
    ISSN: 1423-0127
    Schlagwort(e): Grave's disease ; Human foamy virus ; Korea ; Molecular epidemiology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The possible association of human foamy virus (HFV) with human thyroid disorders such as Graves' disease (GD) has been a topic of controversy due to the inconsistent results reported by several groups of investigators. Here we report the investigation of the presence of HFV-related sequences in the Korean population. DNA was obtained from peripheral blood lymphocytes from 24 GD patients and 23 healthy blood donors and subjected to PCR amplification using three sets of nested primers derived fromgag, env, and LTR regions of the HFV genome. Contrary to previously reported studies, our analysis identified HFV-related sequences in the genomes of both healthy individuals and the GD patients. However, the nature of the HFV genome present in each group appeared to be different. We detected all 3 regions of HFV-related sequences in 29% of the HFV-positive GD patients, while no samples in the control group amplified all three regions. This suggests that the LTR may be used as a tool for screening for HFV in GD patients. Our data favor the hypothesis of a relationship between GD and the presence of HFV-related sequences, though in a complex way.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02255858
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  • 3
    Digitale Medien
    Digitale Medien
    An AT rich region of dyad symmetry is a promoter element in the yeast TRP1 gene (1988)
    Springer
    Molecular genetics and genomics 211 (1988), S. 472-476 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Saccharomyces cerevisiae ; TRP1 promoter ; REgion of dyad symmetry ; AT rich tracts
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Transcription from the yeast TRP1 promoter results in two classes of transcript, I and II, that are influenced by different promoter elements. The 5′ flanking region contains a region of dyad symmetry (RDS) which contains a 12 nucleotide AT rich inverted repeat, separated by a 21 bp spacer region. The RDS lies within a region of the promoter required for transcription of calls II RNAs. A series of internal deletions and insertions have been constructed in vitro around the RDS and the effect of each mutation on transcription has been analysed. Deleting either of the repeats abolishes class II transcription and disruption of both repeats influenced the levels of the larger class I transcripts. Deletion of the spacer had no effect but increasing the length to 33 bp reduced transcription. These results show that the RDS is an important component of the TRP1 promoter, that both repeats must be preserved and that there is some constraint on the spacing of the repeats for maximal function.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00425703
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  • 4
    Digitale Medien
    Digitale Medien
    Transcriptional activation by upstream activator sequences requires distinct interactions with downstream elements in the yeast TRP1 promoter (1991)
    Springer
    Molecular genetics and genomics 225 (1991), S. 217-224 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Saccharomyces cerevisiae ; TRPI promoter ; Upstream activating sequences ; PGK
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The interactions between different upstream activator sequences (UAS) and the downstream transcriptional elements of the TRP1 promoter were studied. We have inserted the UAS from the PGK gene into a series of TRP1 promoter deletions such that the PGK UAS is positioned at various distances upstream from or replaces the TRP1 UAS (UAST1). We show that activation of the TRP1 transcription unit I by the PGK UAS shows a marked position dependence, which is solely a function of the position of the PGK UAS relative to sequences involved in the determination of the RNA initiation sites in the TRP1 promoter. No cooperative activation is seen when both UASs are present in the promoter; the PGK UAS is dominant and is not repressed by the TRPI negative element. In addition, we show that the PGK and TRP1 UASs interact differently with TATA sequence at the TRP1 RNA initiation site. Our results suggest that these UASs are functionally distinct because they use different mechanisms for activating heterologous promoters.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00269851
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  • 5
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    Solving Challenging Large Scale QAPs (2021)
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    Publikationsdatum: 2021-12-09
    Beschreibung: We report our progress on the project for solving larger scale quadratic assignment problems (QAPs). Our main approach to solve large scale NP-hard combinatorial optimization problems such as QAPs is a parallel branch-and-bound method efficiently implemented on a powerful computer system using the Ubiquity Generator(UG) framework that can utilize more than 100,000 cores. Lower bounding procedures incorporated in the branch-and-bound method play a crucial role in solving the problems. For a strong lower bounding procedure, we employ the Lagrangian doubly nonnegative (DNN) relaxation and the Newton-bracketing method developed by the authors’ group. In this report, we describe some basic tools used in the project including the lower bounding procedure and branching rules, and present some preliminary numerical results. Our next target problem is QAPs with dimension at least 50, as we have succeeded to solve tai30a and sko42 from QAPLIB for the first time.
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
    Format: application/pdf
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  • 6
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    大規模二次割当問題への挑戦 (2022)
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    Publikationsdatum: 2022-05-13
    Beschreibung: 二次割当問題は線形緩和が弱いことが知られ，強化のため多様な緩和手法が考案されているが，その一つである二重非負値計画緩和（ DNN 緩和）及びその解法として近年研究が進んでいるニュートン・ブラケット法を紹介し，それらに基づく分枝限定法の実装及び数値実験結果について報告する．
    Sprache: Japanisch
    Materialart: reportzib , doc-type:preprint
    Format: application/pdf
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  • 7
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    The Largest Unsolved QAP Instance Tai256c Can Be Converted into A 256-dimensional Simple BQOP with A Single Cardinality Constraint (2022)
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    Publikationsdatum: 2022-10-28
    Beschreibung: Tai256c is the largest unsolved quadratic assignment problem (QAP) instance in QAPLIB; a 1.48% gap remains between the best known feasible objective value and lower bound of the unknown optimal value. This paper shows that the instance can be converted into a 256 dimensional binary quadratic optimization problem (BQOP) with a single cardinality constraint which requires the sum of the binary variables to be 92.The converted BQOP is much simpler than the original QAP tai256c and it also inherits some of the symmetry properties. However, it is still very difficult to solve. We present an efficient branch and bound method for improving the lower bound effectively. A new lower bound with 1.36% gap is also provided.
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
    Format: application/pdf
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  • 8
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    An Exceptionally Difficult Binary Quadratic Optimization Problem with Symmetry: a Challenge for The Largest Unsolved QAP Instance Tai256c (2023)
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    Publikationsdatum: 2023-12-27
    Beschreibung: Tai256c is the largest unsolved quadratic assignment problem (QAP) instance in QAPLIB. It is known that QAP tai256c can be converted into a 256 dimensional binary quadratic optimization problem (BQOP) with a single cardinality constraint which requires the sum of the binary variables to be 92. As the BQOP is much simpler than the original QAP, the conversion increases the possibility to solve the QAP. Solving exactly the BQOP, however, is still very difficult. Indeed, a 1.48% gap remains between the best known upper bound (UB) and lower bound (LB) of the unknown optimal value. This paper shows that the BQOP admits a nontrivial symmetry, a property that makes the BQOP very hard to solve. The symmetry induces equivalent subproblems in branch and bound (BB) methods. To effectively improve the LB, we propose an efficient BB method that incorporates a doubly nonnegative relaxation, the standard orbit branching and a technique to prune equivalent subproblems. With this BB method, a new LB with 1.25% gap is successfully obtained, and computing an LB with 1.0% gap is shown to be still quite difficult.
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
    Format: application/pdf
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