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  • 1
    Publication Date: 2011-05-25
    Description: Mutations in the MID1 gene are causally linked to X-linked Opitz BBB/G syndrome (OS), a congenital disorder that primarily affects the formation of diverse ventral midline structures. The MID1 protein has been shown to function as an E3 ligase targeting the catalytic subunit of protein phosphatase 2A (PP2A-C) for ubiquitin-mediated degradation. However, the molecular pathways downstream of the MID1/PP2A axis that are dysregulated in OS and that translate dysfunctional MID1 and elevated levels of PP2A-C into the OS phenotype are poorly understood. Here, we show that perturbations in MID1/PP2A affect mTORC1 signaling. Increased PP2A levels, resulting from proteasome inhibition or depletion of MID1, lead to disruption of the mTOR/Raptor complex and down-regulated mTORC1 signaling. Congruously, cells derived from OS patients that carry MID1 mutations exhibit decreased mTORC1 formation, S6K1 phosphorylation, cell size, and cap-dependent translation, all of which is rescued by expression of wild-type MID1 or an activated mTOR allele. Our findings define mTORC1 signaling as a downstream pathway regulated by the MID1/PP2A axis, suggesting that mTORC1 plays a key role in OS pathogenesis.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 2
    Publication Date: 2014-11-25
    Description: Author(s): Y. Xue, R. Ginzel, A. Krauß, S. Bernitt, M. Schöffler, K. U. Kühnel, J. R. Crespo López-Urrutia, R. Moshammer, X. Cai, J. Ullrich, and D. Fischer The complete kinematics of single- and double-electron capture from neon to Ar 16+ was measured with a reaction microscope at a projectile energy of 3.2 keV/u (velocity v p =0.36 a.u.). Not only the change of the electronic binding energies (the Q value) and the projectile scattering angles, but also (... [Phys. Rev. A 90, 052720] Published Mon Nov 24, 2014
    Keywords: Atomic and molecular collisions and interactions
    Print ISSN: 1050-2947
    Electronic ISSN: 1094-1622
    Topics: Physics
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  • 3
    Publication Date: 2015-01-04
    Description: We show that the X-ray line flux of the Mn Kα line at 5.9 keV from the decay of 55 Fe is a promising diagnostic to distinguish between Type Ia supernova (SN Ia) explosion models. Using radiation transport calculations, we compute the line flux for two three-dimensional explosion models: a near-Chandrasekhar mass delayed detonation and a violent merger of two (1.1 and 0.9 M ) white dwarfs. Both models are based on solar metallicity zero-age main-sequence progenitors. Due to explosive nuclear burning at higher density, the delayed-detonation model synthesizes ~3.5 times more radioactive 55 Fe than the merger model. As a result, we find that the peak Mn Kα line flux of the delayed-detonation model exceeds that of the merger model by a factor of ~4.5. Since in both models the 5.9-keV X-ray flux peaks five to six years after the explosion, a single measurement of the X-ray line emission at this time can place a constraint on the explosion physics that is complementary to those derived from earlier phase optical spectra or light curves. We perform detector simulations of current and future X-ray telescopes to investigate the possibilities of detecting the X-ray line at 5.9 keV. Of the currently existing telescopes, XMM – Newton /pn is the best instrument for close (1–2 Mpc), non-background limited SNe Ia because of its large effective area. Due to its low instrumental background, Chandra /ACIS is currently the best choice for SNe Ia at distances above ~2 Mpc. For the delayed-detonation scenario, a line detection is feasible with Chandra up to ~3 Mpc for an exposure time of 10 6 s. We find that it should be possible with currently existing X-ray instruments (with exposure times 5 10 5 s) to detect both of our models at sufficiently high S/N to distinguish between them for hypothetical events within the Local Group. The prospects for detection will be better with future missions. For example, the proposed Athena /X-IFU instrument could detect our delayed-detonation model out to a distance of ~5 Mpc. This would make it possible to study future events occurring during its operational life at distances comparable to those of the recent supernovae SN 2011fe (~6.4 Mpc) and SN 2014J (~3.5 Mpc).
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
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  • 4
    Publication Date: 1998-09-11
    Description: Signal transduction is controlled both by regulation of enzyme activation and by organization of enzymatic complexes with nonenzymatic adapters, scaffolds, and anchor proteins. The extracellular signal-regulated kinase (ERK) cascade is one of several evolutionarily conserved mitogen-activated protein (MAP) kinase cascades important in the regulation of growth, apoptosis, and differentiation. A two-hybrid screen was conducted to identify nonenzymatic components of this signaling cascade that might be important in regulating its activity. A protein called MP1 (MEK Partner 1) was identified that bound specifically to MEK1 and ERK1 and facilitated their activation. When overexpressed in cultured cells, MP1 enhanced activation of ERK1 and activation of a reporter driven by the transcription factor Elk-1. Expression of MP1 in cells increased binding of ERK1 to MEK1. MP1 apparently functions as an adapter to enhance the efficiency of the MAP kinase cascade.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schaeffer, H J -- Catling, A D -- Eblen, S T -- Collier, L S -- Krauss, A -- Weber, M J -- CA39076/CA/NCI NIH HHS/ -- GM47332/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1998 Sep 11;281(5383):1668-71.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology and Cancer Center, University of Virginia Health Sciences Center, Charlottesville, VA 22908, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9733512" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Calcium-Calmodulin-Dependent Protein Kinases/*metabolism ; Carrier Proteins/*metabolism ; Cell Line ; *DNA-Binding Proteins ; Enzyme Activation ; MAP Kinase Kinase 1 ; MAP Kinase Kinase 2 ; Mitogen-Activated Protein Kinase 1 ; Mitogen-Activated Protein Kinase 3 ; *Mitogen-Activated Protein Kinase Kinases ; *Mitogen-Activated Protein Kinases ; Molecular Sequence Data ; Phosphorylation ; Protein-Serine-Threonine Kinases/*metabolism ; Protein-Tyrosine Kinases/*metabolism ; Proto-Oncogene Proteins/metabolism ; Proto-Oncogene Proteins c-raf/metabolism ; Recombinant Fusion Proteins/metabolism ; *Signal Transduction ; *Transcription Factors ; Transcriptional Activation ; Transfection ; ets-Domain Protein Elk-1
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 5
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ferroelectric lead zirconium titanate [Pb (ZrxTi1−x)O3] (PZT) thin films have been synthesized by using an automated laser ablation deposition technique with a capability for layer-by-layer or simultaneous deposition of elemental film constituents. The technique is suitable for producing multicomponent and/or multilayered thin films with controlled stoichiometry, such as high-temperature superconductor, ferroelectric, and electro-optic thin films. PZT films were synthesized on MgO (100) by either sequential deposition of layers of ZrO2, TiO2, and PbO, produced by laser ablation of ZrO2, TiO2, and PbO targets, or by simultaneous deposition of all species from ablation of stoichiometric or PbO-rich PZT targets. Films were deposited at 200 °C and subsequently annealed at 600 °C for different periods of time. The orientation, microstructure, surface topography, and composition of the films were characterized by x-ray diffraction, transmission electron microscopy, scanning electron microscopy, and Rutherford backscattering spectrometry, respectively. As-deposited layer films consists of highly oriented (001) PbO layers, from which highly oriented (110) PZT films are produced after postdeposition annealing. On the other hand, laser ablation of bulk PZT targets yields amorphous as-deposited films, which evolve into highly oriented (100) PZT films after postdeposition annealing. Preliminary electrical characterization of the PZT films included polarization hysteresis, fatigue, conductivity (ac and dc), and capacitance versus voltage measurements. From the initial electrical measurements, it appears that the remnant polarization of the layered PZT films is similar to that of the films produced by laser ablation of bulk PZT targets.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 2958-2967 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ultrananocrystalline diamond (UNCD) films 0.1–2.4 μm thick were conformally deposited on sharp single Si microtip emitters, using microwave CH4–Ar plasma-enhanced chemical vapor deposition in combination with a dielectrophoretic seeding process. Field-emission studies exhibited stable, extremely high (60–100 μA/tip) emission current, with little variation in threshold fields as a function of film thickness or Si tip radius. The electron emission properties of high aspect ratio Si microtips, coated with diamond using the hot filament chemical vapor deposition (HFCVD) process were found to be very different from those of the UNCD-coated tips. For the HFCVD process, there is a strong dependence of the emission threshold on both the diamond coating thickness and Si tip radius. Quantum photoyield measurements of the UNCD films revealed that these films have an enhanced density of states within the bulk diamond band gap that is correlated with a reduction in the threshold field for electron emission. In addition, scanning tunneling microscopy studies indicate that the emission sites from UNCD films are related to minima or inflection points in the surface topography, and not to surface asperities. These data, in conjunction with tight binding pseudopotential calculations, indicate that grain boundaries play a critical role in the electron emission properties of UNCD films, such that these boundaries: (a) provide a conducting path from the substrate to the diamond–vacuum interface, (b) produce a geometric enhancement in the local electric field via internal structures, rather than surface topography, and (c) produce an enhancement in the local density of states within the bulk diamond band gap. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ultrananocrystalline diamond (UNCD) films, grown using microwave plasma-enhanced chemical vapor deposition with gas mixtures of Ar–1%CH4 or Ar–1%CH4–5%H2, have been examined with transmission electron microscopy (TEM). The films consist of equiaxed nanograins (2–10 nm in diameter) and elongated twinned dendritic grains. The area occupied by dendritic grains increases with the addition of H2. High resolution electron microscopy shows no evidence of an amorphous phase at grain boundaries, which are typically one or two atomic layer thick (0.2–0.4 nm). Cross-section TEM reveals a noncolumnar structure of the films. The initial nucleation of diamond occurs directly on the Si substrate when H2 is present in the plasma. For the case of UNCD growth from a plasma without addition of H2, the initial nucleation occurs on an amorphous carbon layer about 10–15 nm thick directly grown on the Si substrate. This result indicates that hydrogen plays a critical role in determining the nucleation interface between the UNCD films and the Si substrate. The relation between diamond nuclei and Si is primarily random and occasionally epitaxial. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In situ, real-time studies of layered perovskite SrBi2Ta2O9 (SBT) film growth processes were performed using a time-of-flight ion scattering and recoil spectroscopy (TOF ISARS) technique. These studies revealed two important features related to the synthesis of SBT films via ion-beam sputter-deposition, namely: (a) atomic oxygen originating from a multicomponent SBT target during the sputtering process is incorporated in the growing film more efficiently than molecular oxygen; and (b) the SBT surface appears to be terminated in an incomplete (Bi2O2)2+layer with a top surface of oxygen atoms, which may be responsible for the high resistance to polarization fatigue exhibited by Pt/SBT/Pt capacitors. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 301-303 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Superconducting films of YBa2Cu3O7−δ have been synthesized in a novel ion beam sputter deposition system which features a rotating target holder with BaO2, CuO, and Y2O3 as the sputtering targets. The dwell time of the ion beam on each oxide target is determined by a computer-controlled feedback loop using the signal from a programmable quartz crystal resonator. The sputtered fluxes of all film components originate from the same spatial location, ensuring homogeneous film composition. The results presented demonstrate for the first time an automated ion beam sputter deposition system with the capability of producing high Tc superconducting films by controlled sputtering of either elemental metallic components or oxide precursors. The concept may be extended to include processes such as patterning, production of layered structures (junctions), and film encapsulation necessary for microcircuit manufacturing based on high Tc superconducting films.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 1981-1989 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The transition from microcrystalline to nanocrystalline diamond films grown from Ar/H2/CH4 microwave plasmas has been investigated. Both the cross-section and plan-view micrographs of scanning electron microscopy reveal that the surface morphology, the grain size, and the growth mechanism of the diamond films depend strongly on the ratio of Ar to H2 in the reactant gases. Microcrystalline grain size and columnar growth have been observed from films produced from Ar/H2/CH4 microwave discharges with low concentrations of Ar in the reactant gases. By contrast, the films grown from Ar/H2/CH4 microwave plasmas with a high concentration of Ar in the reactant gases consist of phase pure nanocrystalline diamond, which has been characterized by transmission electron microscopy, selected area electron diffraction, and electron energy loss spectroscopy. X-ray diffraction and Raman spectroscopy reveal that the width of the diffraction peaks and the Raman bands of the as-grown films depends on the ratio of Ar to H2 in the plasmas and are attributed to the transition from micron to nanometer size crystallites. It has been demonstrated that the microstructure of diamond films deposited from Ar/H2/CH4 plasmas can be controlled by varying the ratio of Ar to H2 in the reactant gas. The transition becomes pronounced at an Ar/H2 volume ratio of 4, and the microcrystalline diamond films are totally transformed to nanocrystalline diamond at an Ar/H2 volume ratio of 9. The transition in microstructure is presumably due to a change in growth mechanism from CH3⋅ in high hydrogen content to C2 as a growth species in low hydrogen content plasmas.
    Type of Medium: Electronic Resource
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