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61.
Early consolidation in human primary motor cortex. 总被引:26,自引:0,他引:26
Wolf Muellbacher Ulf Ziemann Joerg Wissel Nguyet Dang Markus Kofler Stefano Facchini Babak Boroojerdi Werner Poewe Mark Hallett 《Nature》2002,415(6872):640-644
Behavioural studies indicate that a newly acquired motor skill is rapidly consolidated from an initially unstable state to a more stable state, whereas neuroimaging studies demonstrate that the brain engages new regions for performance of the task as a result of this consolidation. However, it is not known where a new skill is retained and processed before it is firmly consolidated. Some early aspects of motor skill acquisition involve the primary motor cortex (M1), but the nature of that involvement is unclear. We tested the possibility that the human M1 is essential to early motor consolidation. We monitored changes in elementary motor behaviour while subjects practised fast finger movements that rapidly improved in movement acceleration and muscle force generation. Here we show that low-frequency, repetitive transcranial magnetic stimulation of M1 but not other brain areas specifically disrupted the retention of the behavioural improvement, but did not affect basal motor behaviour, task performance, motor learning by subsequent practice, or recall of the newly acquired motor skill. These findings indicate that the human M1 is specifically engaged during the early stage of motor consolidation. 相似文献
62.
Werner Schuhmann 《Systemic Practice and Action Research》1990,3(3):265-287
This paper describes a framework for information systems development, based on the Viable System Model, currently used within the Film Division of Hoechst AG. 相似文献
63.
64.
65.
G. de Stevens L. H. Werner W. E. Barrett J. J. Chart A. H. Renzi 《Cellular and molecular life sciences : CMLS》1960,16(3):113-114
Zusammenfassung In der Reihe der Dihydro-benzothiadiazine wurde mit Hydrotrichlorthiazid (III) ein neues, ausserordentlich stark wirksames Diuretikum gefunden. Herstellung und pharmakologische Evaluation werden kurz beschrieben. Im Vergleich zu Hydrochlorthiazid (I) ist III beim Hundper os bis zu 20mal stärker diuretisch wirksam. 相似文献
66.
Transport and membrane integration of polypeptides is carried out by specific protein complexes in the membranes of all living cells. The Sec transport path provides an essential and ubiquitous route for protein translocation. In the bacterial cytoplasmic membrane, the channel is formed by oligomers of a heterotrimeric membrane protein complex consisting of subunits SecY, SecE and SecG. In the endoplasmic reticulum membrane, the channel is formed from the related Sec61 complex. Here we report the structure of the Escherichia coli SecYEG assembly at an in-plane resolution of 8 A. The three-dimensional map, calculated from two-dimensional SecYEG crystals, reveals a sandwich of two membranes interacting through the extensive cytoplasmic domains. Each membrane is composed of dimers of SecYEG. The monomeric complex contains 15 transmembrane helices. In the centre of the dimer we observe a 16 x 25 A cavity closed on the periplasmic side by two highly tilted transmembrane helices. This may represent the closed state of the protein-conducting channel. 相似文献
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Estimating the Cluster Tree of a Density by Analyzing the Minimal Spanning Tree of a Sample 总被引:2,自引:0,他引:2
Werner Stuetzle 《Journal of Classification》2003,20(1):025-047
runt pruning , a new clustering method that attempts to
find modes of a density by analyzing the minimal spanning tree of a sample.
The method exploits the connection between the minimal spanning tree and
nearest neighbor density (e.g. normal mixture) or about the geometric shapes
of the clusters, and is computationally feasible for large data sets. 相似文献
69.
Auwerx J Avner P Baldock R Ballabio A Balling R Barbacid M Berns A Bradley A Brown S Carmeliet P Chambon P Cox R Davidson D Davies K Duboule D Forejt J Granucci F Hastie N de Angelis MH Jackson I Kioussis D Kollias G Lathrop M Lendahl U Malumbres M von Melchner H Müller W Partanen J Ricciardi-Castagnoli P Rigby P Rosen B Rosenthal N Skarnes B Stewart AF Thornton J Tocchini-Valentini G Wagner E Wahli W Wurst W 《Nature genetics》2004,36(9):925-927
The European Mouse Mutagenesis Consortium is the European initiative contributing to the international effort on functional annotation of the mouse genome. Its objectives are to establish and integrate mutagenesis platforms, gene expression resources, phenotyping units, storage and distribution centers and bioinformatics resources. The combined efforts will accelerate our understanding of gene function and of human health and disease. 相似文献
70.
Methane oxidation by an extremely acidophilic bacterium of the phylum Verrucomicrobia 总被引:4,自引:0,他引:4
Dunfield PF Yuryev A Senin P Smirnova AV Stott MB Hou S Ly B Saw JH Zhou Z Ren Y Wang J Mountain BW Crowe MA Weatherby TM Bodelier PL Liesack W Feng L Wang L Alam M 《Nature》2007,450(7171):879-882
Aerobic methanotrophic bacteria consume methane as it diffuses away from methanogenic zones of soil and sediment. They act as a biofilter to reduce methane emissions to the atmosphere, and they are therefore targets in strategies to combat global climate change. No cultured methanotroph grows optimally below pH 5, but some environments with active methane cycles are very acidic. Here we describe an extremely acidophilic methanotroph that grows optimally at pH 2.0-2.5. Unlike the known methanotrophs, it does not belong to the phylum Proteobacteria but rather to the Verrucomicrobia, a widespread and diverse bacterial phylum that primarily comprises uncultivated species with unknown genotypes. Analysis of its draft genome detected genes encoding particulate methane monooxygenase that were homologous to genes found in methanotrophic proteobacteria. However, known genetic modules for methanol and formaldehyde oxidation were incomplete or missing, suggesting that the bacterium uses some novel methylotrophic pathways. Phylogenetic analysis of its three pmoA genes (encoding a subunit of particulate methane monooxygenase) placed them into a distinct cluster from proteobacterial homologues. This indicates an ancient divergence of Verrucomicrobia and Proteobacteria methanotrophs rather than a recent horizontal gene transfer of methanotrophic ability. The findings show that methanotrophy in the Bacteria is more taxonomically, ecologically and genetically diverse than previously thought, and that previous studies have failed to assess the full diversity of methanotrophs in acidic environments. 相似文献