1,916 research outputs found

    Internal and relative motions of the Taurus and Ophiuchus star-forming regions

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    We investigate the internal and relative motions of the Taurus and Ophiuchus star-forming regions using a sample of young stars with accurately measured radial velocities and proper motions. We find no evidence for expansion or contraction of the Taurus complex, but a clear indication for a global rotation, resulting in velocity gradients, this suggests a common origin, possibly related to that of Gould's Belt.Comment: 2 figure

    Corporate social responsibility, customer satisfaction, corporate reputation, and firms’ market value: Evidence from the automobile industry

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    How does corporate social responsibility (CSR) impact on firms’ market value? Academy had found it difficult to give a suitable answer to this question, considered as the ‘‘Holy Grail’’ of CSR. In contrast to previous research that stressed subjective measures to rate CSR performance, was multi-sector focused and encompassed short periods, we propose a different insight. Using an objective CSR performance rating (Ethical Portfolio Management [EPM] owned by EIRIS), taking a single industry -the automobile industry-, and spanning 8 years, in this paper, we try to make a difference. Our results suggest that certain CSR issues -those related to corporate core business and critical stakeholders-may lead to companies’ better financial performance

    Kinetics of color center formation in silica irradiated with swift heavy ions: Thresholding and formation efficiency

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    We have determined the cross-section σ for color center generation under single Br ion impacts on amorphous SiO2. The evolution of the cross-sections, σ(E) and σ(Se), show an initial flat stage that we associate to atomic collision mechanisms. Above a certain threshold value (Se > 2 keV/nm), roughly coinciding with that reported for the onset of macroscopic disorder (compaction), σ shows a marked increase due to electronic processes. In this regime, a energetic cost of around 7.5 keV is necessary to create a non bridging oxygen hole center-E′ (NBOHC/E′) pair, whatever the input energy. The data appear consistent with a non-radiative decay of self-trapped excitons

    Global mRNA expression analysis in myosin II deficient strains of Saccharomyces cerevisiae reveals an impairment of cell integrity functions

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    <p>Abstract</p> <p>Background</p> <p>The <it>Saccharomyces cerevisiae MYO1 </it>gene encodes the myosin II heavy chain (Myo1p), a protein required for normal cytokinesis in budding yeast. Myo1p deficiency in yeast (<it>myo1Δ</it>) causes a cell separation defect characterized by the formation of attached cells, yet it also causes abnormal budding patterns, formation of enlarged and elongated cells, increased osmotic sensitivity, delocalized chitin deposition, increased chitin synthesis, and hypersensitivity to the chitin synthase III inhibitor Nikkomycin Z. To determine how differential expression of genes is related to these diverse cell wall phenotypes, we analyzed the global mRNA expression profile of <it>myo1Δ </it>strains.</p> <p>Results</p> <p>Global mRNA expression profiles of <it>myo1Δ </it>strains and their corresponding wild type controls were obtained by hybridization to yeast oligonucleotide microarrays. Results for selected genes were confirmed by real time RT-PCR. A total of 547 differentially expressed genes (p ≤ 0.01) were identified with 263 up regulated and 284 down regulated genes in the <it>myo1Δ </it>strains. Gene set enrichment analysis revealed the significant over-representation of genes in the protein biosynthesis and stress response categories. The <it>SLT2/MPK1 </it>gene was up regulated in the microarray, and a <it>myo1Δslt2Δ </it>double mutant was non-viable. Overexpression of ribosomal protein genes <it>RPL30 </it>and <it>RPS31 </it>suppressed the hypersensitivity to Nikkomycin Z and increased the levels of phosphorylated Slt2p in <it>myo1Δ </it>strains. Increased levels of phosphorylated Slt2p were also observed in wild type strains under these conditions.</p> <p>Conclusion</p> <p>Following this analysis of global mRNA expression in yeast <it>myo1Δ </it>strains, we conclude that 547 genes were differentially regulated in <it>myo1Δ </it>strains and that the stress response and protein biosynthesis gene categories were coordinately regulated in this mutant. The <it>SLT2/MPK1 </it>gene was confirmed to be essential for <it>myo1Δ </it>strain viability, supporting that the up regulated stress response genes are regulated by the <it>PKC1 </it>cell integrity pathway. Suppression of Nikkomycin Z hypersensitivity together with Slt2p phosphorylation was caused by the overexpression of ribosomal protein genes <it>RPL30 </it>and <it>RPS31</it>. These ribosomal protein mRNAs were down regulated in the <it>myo1Δ </it>arrays, suggesting that down regulation of ribosomal biogenesis may affect cell integrity in <it>myo1Δ </it>strains.</p

    The Gould's Belt Very Large Array Survey III. The Orion region

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    We present results from a high-sensitivity (60 μ\muJy), large-scale (2.26 square degree) survey obtained with the Karl G. Jansky Very Large Array as part of the Gould's Belt Survey program. We detected 374 and 354 sources at 4.5 and 7.5 GHz, respectively. Of these, 148 are associated with previously known Young Stellar Objects (YSOs). Another 86 sources previously unclassified at either optical or infrared wavelengths exhibit radio properties that are consistent with those of young stars. The overall properties of our sources at radio wavelengths such as their variability and radio to X-ray luminosity relation are consistent with previous results from the Gould's Belt Survey. Our detections provide target lists for followup VLBA radio observations to determine their distances as YSOs are located in regions of high nebulosity and extinction, making it difficult to measure optical parallaxes.Comment: Accepted for publication in ApJ; 51 pages, 15 figures, 5 table

    Lesson study as a way of reconstructing practical knowledge for improved teaching practice. Seven case studies.

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    With the aim of helping to enrich teacher training processes, using an approach based on Practical Knowledge and Practical Thinking (Schön's knowledge-in-action), the present paper strives to explore and understand the relationships between espoused theories and theories-in-use (action theories by Argyris) of a group of seven pre-school teachers involved in a process of in-service training based on Lesson Study, a powerful methodological tool to identify, contrast and review such theories both autonomously and cooperatively. The conclusion reached is that this training strategy is a rich proposal for the questioning of teaching theory and practice, and, in consequence, for the reconstruction of more unconscious Practical Knowledge, albeit with some circumstantial and personal nuances.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Identification and functional analysis of novel phosphorylation sites in the RNA surveillance protein Upf1.

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    One third of inherited genetic diseases are caused by mRNAs harboring premature termination codons as a result of nonsense mutations. These aberrant mRNAs are degraded by the Nonsense-Mediated mRNA Decay (NMD) pathway. A central component of the NMD pathway is Upf1, an RNA-dependent ATPase and helicase. Upf1 is a known phosphorylated protein, but only portions of this large protein have been examined for phosphorylation sites and the functional relevance of its phosphorylation has not been elucidated in Saccharomyces cerevisiae. Using tandem mass spectrometry analyses, we report the identification of 11 putative phosphorylated sites in S. cerevisiae Upf1. Five of these phosphorylated residues are located within the ATPase and helicase domains and are conserved in higher eukaryotes, suggesting a biological significance for their phosphorylation. Indeed, functional analysis demonstrated that a small carboxy-terminal motif harboring at least three phosphorylated amino acids is important for three Upf1 functions: ATPase activity, NMD activity and the ability to promote translation termination efficiency. We provide evidence that two tyrosines within this phospho-motif (Y-738 and Y-742) act redundantly to promote ATP hydrolysis, NMD efficiency and translation termination fidelity

    The Gould's Belt Very Large Array Survey II: The Serpens region

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    We present deep (17 μ\sim 17~\muJy) radio continuum observations of the Serpens molecular cloud, the Serpens south cluster, and the W40 region obtained using the Very Large Array in its A configuration. We detect a total of 146 sources, 29 of which are young stellar objects (YSOs), 2 are BV stars and 5 more are associated with phenomena related to YSOs. Based on their radio variability and spectral index, we propose that about 16 of the remaining 110 unclassified sources are also YSOs. For approximately 65% of the known YSOs detected here as radio sources, the emission is most likely non-thermal, and related to stellar coronal activity. As also recently observed in Ophiuchus, our sample of YSOs with X-ray counterparts lies below the fiducial G\"udel & Benz relation. Finally, we analyze the proper motions of 9 sources in the W40 region. This allows us to better constrain the membership of the radio sources in the region.Comment: Accepted in The Astrophysical Journa
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