3,149 research outputs found

    On the design of an interactive biosphere for the GLAS general circulation model

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    Improving the realism and accuracy of the GLAS general circulation model (by adding an interactive biosphere that will simulate the transfers of latent and sensible heat from land surface to atmosphere as functions of the atmospheric conditions and the morphology and physiology of the vegetation) is proposed

    Gene Expression Profile Changes After Short-activating RNA-mediated Induction of Endogenous Pluripotency Factors in Human Mesenchymal Stem Cells

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    It is now recognized that small noncoding RNA sequences have the ability to mediate transcriptional activation of specific target genes in human cells. Using bioinformatics analysis and functional screening, we screened short-activating RNA (saRNA) oligonucleotides designed to target the promoter regions of the pluripotency reprogramming factors, Kruppel-like factor 4 (KLF4) and c-MYC. We identified KLF4 and c-MYC promoter-targeted saRNA sequences that consistently induced increases in their respective levels of nascent mRNA and protein expression in a time- and dose-dependent manner, as compared with scrambled sequence control oligonucleotides. The functional consequences of saRNA-induced activation of each targeted reprogramming factor were then characterized by comprehensively profiling changes in gene expression by microarray analysis, which revealed significant increases in mRNA levels of their respective downstream pathway genes. Notably, the microarray profile after saRNA-mediated induction of endogenous KLF4 and c-MYC showed similar gene expression patterns for stem cell- and cell cycle-related genes as compared with lentiviral vector-mediated overexpression of exogenous KLF4 and c-MYC transgenes, while divergent gene expression patterns common to viral vector-mediated transgene delivery were also noted. The use of promoter-targeted saRNAs for the activation of pluripotency reprogramming factors could have broad implications for stem cell research

    Operating Interaction and Teleprogramming for Subsea Manipulation

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    The teleprogramming paradigm has been proposed as a means to efficiently perform teleoperation in the subsea environment via an acoustical link. In such a system the effects of both limited bandwidth channels and delayed communications are overcome by transmitting not Cartesian or joint level information but rather symbolic, error-tolerant, program instructions to the remote site. The operator interacts with a virtual reality of the remote site which provides immediate visual and kinesthetic feedback. The uncertainty in this model can be reduced based on information received from the slave manipulator\u27s tactile contact with the environment. It is suggested that the current state of the model be made available to the operator via a graphical display which shows not only the position of objects at the remote site but also, through the use of color clues, the uncertainty associated with those positions. The provision of uncertainty information is important since it allows the operator to compromise between speed and accuracy. An additional operator aid, which we term synthetic fixturing, is proposed. Synthetic fixtures provide the operator of the teleprogramming system with the teleoperation equivalent of the snap commands common in computer aided design programs. By guiding the position and/or orientation of the master manipulator toward specific points, lines or planes the system is able to increase both the speed and precision with which the operator can control the slave arm without requiring sophisticated hardware

    Particle Creation by a Moving Boundary with Robin Boundary Condition

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    We consider a massless scalar field in 1+1 dimensions satisfying a Robin boundary condition (BC) at a non-relativistic moving boundary. We derive a Bogoliubov transformation between input and output bosonic field operators, which allows us to calculate the spectral distribution of created particles. The cases of Dirichlet and Neumann BC may be obtained from our result as limiting cases. These two limits yield the same spectrum, which turns out to be an upper bound for the spectra derived for Robin BC. We show that the particle emission effect can be considerably reduced (with respect to the Dirichlet/Neumann case) by selecting a particular value for the oscillation frequency of the boundary position
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