877 research outputs found
Possibility of Macroscopic resonant Tunneling near the Superconductor- Insulator Transition in YBaCuO Thin Films
Experimental results of I-V characteristics near the superconductor-insulator
transition observed for disorder-tuned YBaCuO thinfilms are presented. The I-V
characteristics exibit new quasiperiodic structures as a function of the
current. The current interval, the number of the dI/dV peaks, and the magnetic
field dependence of the peaks are consistent with the theoretical predictions
of the resonant tunneling of a phase particle ina tilted-cosine potential for
asingle Josephson junction with small capacitance.Comment: 7 pages, 4 figures, in press (Europhys. Lett.
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Hydrogen Fuel Quality
Jim Ohi of NREL's presentation on Hydrogen Fuel Quality at the 2007 DOE Hydrogen Program Annual Merit Review and Peer Evaluation on May 15-18, 2007 in Arlington, Virginia
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Hydrogen Codes and Standards
Presented at the 2006 DOE Hydrogen, Fuel Cells & Infrastructure Technologies Program Annual Merit Review in Washington, D.C., May 16-19, 2006
An Inner Centromere Protein that Stimulates the Microtubule Depolymerizing Activity of a KinI Kinesin
AbstractMitosis requires precise control of microtubule dynamics. The KinI kinesin MCAK, a microtubule depolymerase, is critical for this regulation. In a screen to discover previously uncharacterized microtubule-associated proteins, we identified ICIS, a protein that stimulates MCAK activity in vitro. Consistent with this biochemical property, blocking ICIS function in Xenopus extracts with antibodies caused excessive microtubule growth and inhibited spindle formation. Prior to anaphase, ICIS localized in an MCAK-dependent manner to inner centromeres, the chromosomal region located in between sister kinetochores. From Xenopus extracts, ICIS coimmunoprecipitated MCAK and the inner centromere proteins INCENP and Aurora B, which are thought to promote chromosome biorientation. By immunoelectron microscopy, we found that ICIS is present on the surface of inner centromeres, placing it in an ideal location to depolymerize microtubules associated laterally with inner centromeres. At inner centromeres, MCAK-ICIS may destabilize these microtubules and provide a mechanism that prevents kinetochore-microtubule attachment errors
Spindle assembly in the absence of a RanGTP gradient requires localized CPC activity
Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Current Biology 19 (2009): 1210-1215, doi:10.1016/j.cub.2009.05.061.During animal cell division, a gradient of GTP-bound Ran is generated
around mitotic chromatin. It is generally accepted that this RanGTP
gradient is essential for organizing the spindle since it locally activates
critical spindle assembly factors. Here, we show in Xenopus egg
extract, where the gradient is best characterized, that spindles can
assemble in the absence of a RanGTP gradient. Gradient-free spindle
assembly occurred around sperm nuclei but not around chromatin-coated
beads and required the chromosomal passenger complex (CPC). Artificial
enrichment of CPC activity within hybrid bead arrays containing both
immobilized chromatin and the CPC supported local microtubule assembly
even in the absence of a RanGTP gradient. We conclude that RanGTP and
the CPC constitute the two major molecular signals that spatially promote
microtubule polymerization around chromatin. Furthermore, we
hypothesize that the two signals mainly originate from discreet physical
sites on the chromosomes to localize microtubule assembly around
chromatin: a RanGTP signal from any chromatin, and a CPC-dependent
signal predominantly generated from centromeric chromatin.This work was supported by the American
Cancer Society (grant PF0711401 to T.J. Maresca), the National Cancer Institute
(grant CA078048-09 to T.J. Mitchison) and the National Institutes of Health (grant
F32GM080049 to J.C. Gatlin and grant GM24364 to E.D. Salmon)
A Woods-Saxon Optical-Model Description of 14N Elastic and Inelastic Scattering from 27Al and 28Si
開始ページ、終了ページ: 冊子体のページ付
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Analysis of Buoyancy-Driven Ventilation of Hydrogen from Buildings: Preprint
When hydrogen gas is used or stored within a building, as with a hydrogen-powered vehicle parked in a residential garage, any leakage of unignited H2 will mix with indoor air and may form a flammable mixture. One approach to safety engineering relies on buoyancy-driven, passive ventilation of H2 from the building through vents to the outside
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Analysis of Buoyancy-Driven Ventilation of Hydrogen from Buildings
The scope of work for this project includes safe building design, vehicle leak in residential garage, continual slow leak, passive, buoyancy-driven ventilation (versus mechanical), and steady-state concentration of hydrogen versus vent size
A Natural Framework for Solar and 17 keV Neutrinos
Motivated by recent experimental claims for the existence of a 17 keV
neutrino and by the solar neutrino problem, we construct a class of models
which contain in their low-energy spectrum a single light sterile neutrino and
one or more Nambu-Goldstone bosons. In these models the required pattern of
breaking of lepton-number symmetry takes place near the electroweak scale and
all mass heirarchies are technically natural. The models are compatible with
all cosmological and astrophysical constraints, and can solve the solar
neutrino problem via either the MSW effect or vacuum oscillations. The deficit
in atmospheric muon neutrinos seen in the Kamiokande and IMB detectors can also
be explained in these models.Comment: 23 page
The Prp19 U-box crystal structure suggests a common dimeric architecture for a class of oligomeric E3 ubiquitin ligases
Prp19 is an essential splicing factor and a member of the U-box family of E3 ubiquitin ligases. Prp19 forms a tetramer via a central coiled-coil domain. Here, we show the U-box domain of Prp19 exists as a dimer within the context of the Prp19 tetramer. A high-resolution structure of the homodimeric state of the Prp19 U-box was determined by X-ray crystallography. Mutation of the U-box dimer interface abrogates U-box dimer formation and is lethal in vivo. The structure of the U-box dimer enables construction of a complete model of Prp19 providing insights into how the tetrameric protein functions as an E3 ligase. Finally, comparison of the Prp19 U-box homodimer with the heterodimeric complex of BRCA1/BARD1 RING-finger domains uncovers a common architecture for a family of oligomeric U-box and RING-finger E3 ubiquitin ligases, which has mechanistic implications for E3 ligase-mediated polyubiquitination and E4 polyubiquitin ligases. © 2006 American Chemical Society
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