18,368 research outputs found
Wave packet dynamics of potassium dimers attached to helium nanodroplets
The dynamics of vibrational wave packets excited in K dimers attached to
superfluid helium nanodroplets is investigated by means of femtosecond
pump-probe spectroscopy. The employed resonant three-photon-ionization scheme
is studied in a wide wavelength range and different pathways leading to
K-formation are identified. While the wave packet dynamics of the
electronic ground state is not influenced by the helium environment,
perturbations of the electronically excited states are observed. The latter
reveal a strong time dependence on the timescale 3-8 ps which directly reflects
the dynamics of desorption of K off the helium droplets
Unified powered flight guidance
A complete revision of the orbiter powered flight guidance scheme is presented. A unified approach to powered flight guidance was taken to accommodate all phases of exo-atmospheric orbiter powered flight, from ascent through deorbit. The guidance scheme was changed from the previous modified version of the Lambert Aim Point Maneuver Mode used in Apollo to one that employs linear tangent guidance concepts. This document replaces the previous ascent phase equation document
PAI-1 Expression Is Required for HDACi-Induced Proliferative Arrest in ras-Transformed Renal Epithelial Cells
Malignant transformation of mammalian cells with ras family oncogenes results in dramatic changes in cellular architecture and growth traits. The generation of flat revertants of v-K-ras-transformed renal cells by exposure to the histone deacetylase inhibitor sodium butyrate (NaB) was previously found to be dependent on transcriptional activation of the PAI-1 (SERPINE1) gene (encoding the type-1 inhibitor of urokinase and tissue-type plasminogen activators). NaB-initiated PAI-1 expression preceded induced cell spreading and entry into G1 arrest. To assess the relevance of PAI-1 induction to growth arrest in this cell system more critically, two complementary approaches were used. The addition of a stable, long half-life, recombinant PAI-1 mutant to PAI-1-deficient v-K-ras-/c-Ha-ras-transformants or to PAI-1 functionally null, NaB-resistant, 4HH cells (engineered by antisense knockdown of PAI-1 mRNA transcripts) resulted in marked cytostasis in the absence of NaB. The transfection of ras-transformed cells with the Rc/CMVPAI expression construct, moreover, significantly elevated constitutive PAI-1 synthesis (10- to 20-fold) with a concomitant reduction in proliferative rate. These data suggest that high-level PAI-1 expression suppresses growth of chronic ras-oncogene transformed cells and is likely a major cytostatic effector of NaB exposure
Spectroscopy of Rb dimers in solid He
We present experimental and theoretical studies of the absorption, emission
and photodissociation spectra of Rb molecules in solid helium. We have
identified 11 absorption bands of Rb. All laser-excited molecular states
are quenched by the interaction with the He matrix. The quenching results in
efficient population of a metastable (1) state, which emits
fluorescence at 1042 nm. In order to explain the fluorescence at the forbidden
transition and its time dependence we propose a new molecular exciplex
RbHe. We have also found evidence for the formation of
diatomic bubble states following photodissociation of Rb
TGF-β1-Induced Expression of the Poor Prognosis SERPINE1/PAI-1 Gene Requires EGFR Signaling: A New Target for Anti-EGFR Therapy
Increased transforming growth factor-β (TGF-β) expression and epidermal growth factor receptor (EGFR) amplification accompany the emergence of highly aggressive human carcinomas. Cooperative signaling between these two growth factor/receptor systems promotes cell migration and synthesis of stromal remodeling factors (i.e., proteases, protease inhibitors) that, in turn, regulate tumor invasion, neo-angiogenesis and inflammation. ranscript profiling of transformed human cells revealed that genes encoding wound healing, matrix remodeling and cell cycle proteins (i.e., the “tissue repair” transcriptome) are significantly up-regulated early after growth factor stimulation. The major inhibitor of plasmin generation, plasminogen activator inhibitor-1 (PAI-1), is among the most highly induced transcripts during the phenotypic transition initiated by TGF-β maximal expression requires EGFR signaling. PAI-1 induction occurs early in the progression of incipient epidermal squamous cell carcinoma (SCC) and is a significant indicator of poor prognosis in epithelial malignancies. Mouse modeling and molecular genetic analysis of complex systems indicates that PAI-1 regulates the temporal/spatial control of pericellular proteolysis, promotes epithelial plasticity, inhibits capillary regression and facilitates stromal invasion. Defining TGF-β1-initiated signaling events that cooperate with an activated EGFR to impact the protease-protease inhibitor balance in the tumor microenvironment is critical to the development of novel therapies for the clinical management of human cancers
Coexistence of Antiferromagnetism and Superconductivity in Electron-doped High-Tc Superconductors
We present magnetotransport evidence for antiferromagnetism in films of the
electron-doped cuprates PrCeCuO. Our results show clear
signature of static antiferromagnetism up to optimal doping x=0.15, with a
quantum phase transition close to x=0.16, and a coexistence of static
antiferromagnetism and superconductivity for 0.12x0.15
Does intensive multidisciplinary intervention for adults who elect bariatric surgery improve post-operative weight loss, co-morbidities, and quality of life? A systematic review and meta-analysis
Generalized Green'S Equivalences on the Subsemigroups of the Bicyclic Monoid
We study generalized Green's equivalences on all subsemigroups of the bicyclic monoid B and determine the abundant (and adequate) subsemigroups of B. © 2010 Copyright Taylor and Francis Group, LLC
Metastable states of a flux line lattice studied by transport and Small Angle Neutron Scattering
Flux Lines Lattice (FLL) states have been studied using transport
measurements and Small Angle Neutron Scattering in low T materials. In
Pb-In, the bulk dislocations in the FLL do not influence the transport
properties. In Fe doped NbSe, transport properties can differ after a
Field Cooling (FC) or a Zero Field Cooling (ZFC) procedure, as previously
reported. The ZFC FLL is found ordered with narrow Bragg Peaks and is linked to
a linear V(I) curve and to a superficial critical current. The FC FLL pattern
exhibits two Bragg peaks and the corresponding V(I) curve shows a S-shape. This
can be explained by the coexistence of two ordered FLL slightly tilted from the
applied field direction by different superficial currents. These currents are
wiped out when the transport current is increased.Comment: accepted for publication in Phys. Rev.
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