191 research outputs found
The differential-algebraic and bi-Hamiltonian integrability analysis of the Riemann type hierarchy revisited
A differential-algebraic approach to studying the Lax type integrability of
the generalized Riemann type hydrodynamic hierarchy is revisited, its new Lax
type representation and Poisson structures constructed in exact form. The
related bi-Hamiltonian integrability and compatible Poissonian structures of
the generalized Riemann type hierarchy are also discussed.Comment: 18 page
Search for flavor-changing neutral currents and lepton-family-number violation in two-body D0 decays
Results of a search for the three neutral charm decays, D0 -> mu e, D0 -> mu
mu, and D0 -> e e, are presented. This study was based on data collected in
Experiment 789 at the Fermi National Accelerator Laboratory using 800 GeV/c
proton-Au and proton-Be interactions. No evidence is found for any of the
decays. Upper limits on the branching ratios, at the 90% confidence level, are
obtained.Comment: 28 pages, 18 figures. Submitted to Physical Review
Crystal Phase Transitions in the Shell of PbS CdS Core Shell Nanocrystals Influences Photoluminescence Intensity
ABSTRACT We reveal the existence of two different crystalline phases, i.e., the metastable rock salt and the equilibrium zinc blende phase within the CdS shell of PbS CdS core shell nanocrystals formed by cationic exchange. The chemical composition profile of the core shell nanocrystals with different dimensions is determined by means of anomalous small angle X ray scattering with subnanometer resolution and is compared to X ray diffraction analysis. We demonstrate that the photoluminescence emission of PbS nanocrystals can be drastically enhanced by the formation of a CdS shell. Especially, the ratio of the two crystalline phases in the shell significantly influences the photoluminescence enhancement. The highest emission was achieved for chemically pure CdS shells below 1 nm thickness with a dominant metastable rock salt phase fraction matching the crystal structure of the PbS core. The metastable phase fraction decreases with increasing shell thickness and increasing Exchange times. The photoluminescence intensity depicts a constant decrease with decreasing metastable rock salt phase fraction but Shows an abrupt drop for shells above 1.3 nm thickness. We relate this effect to two different transition mechanisms for changing from the metastable rock salt phase to the equilibrium zinc blende phase depending on the shell thicknes
Strategies to improve the signal and noise performance of active matrix, flatâ panel imagers for diagnostic xâ ray applications
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134928/1/mp8831.pd
Inter-diffusion of Plasmonic Metals and Phase Change Materials
This work investigates the problematic diffusion of metal atoms into phase
change chalcogenides, which can destroy resonances in photonic devices.
Interfaces between Ge2Sb2Te5 and metal layers were studied using X-ray
reflectivity (XRR) and reflectometry of metal-Ge2Sb2Te5 layered stacks. The
diffusion of metal atoms influences the crystallisation temperature and optical
properties of phase change materials. When Au, Ag, Al, W structures are
directly deposited on Ge2Sb2Te5 inter-diffusion occurs. Indeed, Au forms AuTe2
layers at the interface. Diffusion barrier layers, such as Si3N4 or stable
diffusionless plasmonic materials, such as TiN, can prevent the interfacial
damage. This work shows that the interfacial diffusion must be considered when
designing phase change material tuned photonic devices, and that TiN is the
most suitable plasmonic material to interface directly with Ge2Sb2Te5.Comment: 23 pages, 8 figures, articl
Metal Matrix–Metal Nanoparticle Composites with Tunable Melting Temperature and High Thermal Conductivity for Phase-Change Thermal Storage
Static Magnetic Field Exposure Reproduces Cellular Effects of the Parkinson's Disease Drug Candidate ZM241385
This study was inspired by coalescing evidence that magnetic therapy may be a viable treatment option for certain diseases. This premise is based on the ability of moderate strength fields (i.e., 0.1 to 1 Tesla) to alter the biophysical properties of lipid bilayers and in turn modulate cellular signaling pathways. In particular, previous results from our laboratory (Wang et al., BMC Genomics, 10, 356 (2009)) established that moderate strength static magnetic field (SMF) exposure altered cellular endpoints associated with neuronal function and differentiation. Building on this background, the current paper investigated SMF by focusing on the adenosine A(2A) receptor (A(2A)R) in the PC12 rat adrenal pheochromocytoma cell line that displays metabolic features of Parkinson's disease (PD).SMF reproduced several responses elicited by ZM241385, a selective A(2A)R antagonist, in PC12 cells including altered calcium flux, increased ATP levels, reduced cAMP levels, reduced nitric oxide production, reduced p44/42 MAPK phosphorylation, inhibited proliferation, and reduced iron uptake. SMF also counteracted several PD-relevant endpoints exacerbated by A(2A)R agonist CGS21680 in a manner similar to ZM241385; these include reduction of increased expression of A(2A)R, reversal of altered calcium efflux, dampening of increased adenosine production, reduction of enhanced proliferation and associated p44/42 MAPK phosphorylation, and inhibition of neurite outgrowth.When measured against multiple endpoints, SMF elicited qualitatively similar responses as ZM241385, a PD drug candidate. Provided that the in vitro results presented in this paper apply in vivo, SMF holds promise as an intriguing non-invasive approach to treat PD and potentially other neurological disorders
Measurement of the mass difference m(D-s(+))-m(D+) at CDF II
We present a measurement of the mass difference m(D-s(+))-m(D+), where both the D-s(+) and D+ are reconstructed in the phipi(+) decay channel. This measurement uses 11.6 pb(-1) of data collected by CDF II using the new displaced-track trigger. The mass difference is found to be m(D-s(+))-m(D+)=99.41+/-0.38(stat)+/-0.21(syst) MeV/c(2)
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