32,168 research outputs found
Evidence for spin-flip scattering and local moments in dilute fluorinated graphene
The issue of whether local magnetic moments can be formed by introducing
adatoms into graphene is of intense research interest because it opens the
window to fundamental studies of magnetism in graphene, as well as of its
potential spintronics applications. To investigate this question we measure, by
exploiting the well-established weak localization physics, the phase coherence
length L_phi in dilute fluorinated graphene. L_phi reveals an unusual
saturation below ~ 10 K, which cannot be explained by non-magnetic origins. The
corresponding phase breaking rate increases with decreasing carrier density and
increases with increasing fluorine density. These results provide strong
evidence for spin-flip scattering and points to the existence of adatom-induced
local magnetic moment in fluorinated graphene. Our results will stimulate
further investigations of magnetism and spintronics applications in
adatom-engineered graphene.Comment: 9 pages, 4 figures, and supplementary materials; Phys. Rev. Lett. in
pres
Isospin breaking and - mixing in the reaction
We make a theoretical study of the and
reactions with an aim to determine the
isospin violation and the mixing of the and resonances.
We make use of the chiral unitary approach where these two resonances appear as
composite states of two mesons, dynamically generated by the meson-meson
interaction provided by chiral Lagrangians. We obtain a very narrow shape for
the production in agreement with a BES experiment. As to the amount
of isospin violation, or and mixing, assuming constant
vertices for the primary and
production, we find results which
are much smaller than found in the recent experimental BES paper, but
consistent with results found in two other related BES experiments. We have
tried to understand this anomaly by assuming an I=1 mixture in the
wave function, but this leads to a much bigger width of the mass
distribution than observed experimentally. The problem is solved by using the
primary production driven by followed by , which induces an extra singularity in the loop functions needed to
produce the and resonances. Improving upon earlier work
along the same lines, and using the chiral unitary approach, we can now predict
absolute values for the ratio which are in fair agreement with experiment. We also show that the same
results hold if we had the resonance or a mixture of these two
states, as seems to be the case in the BES experiment
Poisson noise induced switching in driven micromechanical resonators
We study Poisson-noise induced switching between coexisting vibrational
states in driven nonlinear micromechanical resonators. In contrast to Gaussian
noise induced switching, the measured logarithm of the switching rate is
proportional not to the reciprocal noise intensity, but to its logarithm, for
fixed pulse area. We also find that the switching rate logarithm varies as a
square root of the distance to the bifurcation point, instead of the
conventional scaling with exponent 3/2.Comment: accepted by PR
Preliminary Studies about Synthesis and Electrical Properties of Ruthenium Doped Lanthanum Strontium Titanate as a Potential Anode of Solid Oxide Fuel Cells
The lanthanum strontium titanate (LST) is one of the most representative alternative anode materials. Although it shows low catalytic properties, the disadvantage could be improved by doping of ruthenium which is widely used as catalyst under steam reforming reaction or oxidation reaction. The ruthenium doped lanthanum strontium titanates (LSTRs) powders were synthesized by complex EDTA-citrate method showing well crystallinity. Additionally, the prepared samples were evaluated through various experimental tests. For example, the stability in the reducing atmosphere and chemical compatibility with YSZ electrolyte such as reactivity test in high temperature were confirmed by XRD (X-ray diffraction). And electrical conductivity in wet H-2 atmosphere at 900 degrees C is about 350.6 S/cm, 342.4 S/cm and 179.1 S/cm with sintered bar of LST, LSTR0.02 and LSTR0.05, respectively.open1111Nsciescopu
Multi-quark components in baryons
A brief review on some recent progresses in our understanding of multi-quark
components in baryons is presented. The multi-quark components in baryons seem
to be mainly in colored quark cluster configurations rather than in ``meson
cloud'' configurations or in the form of a sea of quark-antiquark pairs. The
colored quark cluster multi-quark picture gives a natural explanation of
empirical indications for a positive strangeness magnetic moment of the
proton and the longstanding mass-reverse problem of S11(1535) and \mu_s$ of the proton is given.Comment: Contribution to the International Conference on QCD and Hadronic
Physics, June 16-20, 2005, Beijin
Postsynaptic calcium/calmodulin-dependent protein kinase II is required to limit elaboration of presynaptic and postsynaptic neuronal arbors
Neuronal dendritic and axonal arbors grow to a characteristic size and then stabilize their structures. Activity-dependent stop-growing signals may limit neuronal process elaboration. We tested whether endogenous calcium/calmodulin-dependent protein kinase II (CaMKII) activity in postsynaptic optic tectal cells is required to restrict the elaboration of neuronal processes in the Xenopus tadpole retinotectal projection. Optic tectal cells were infected with vaccinia viruses that express CaMKII-specific inhibitory peptides. In vivo time-lapse imaging revealed that expression of CaMKII inhibitors blocked the growth restriction that normally occurs during maturation of tectal cell dendritic arbors. Postsynaptic CaMKII inhibition also increased the growth of presynaptic retinotectal axon arbors. The results indicate that endogenous postsynaptic CaMKII activity is required to limit the growth of presynaptic and postsynaptic arbor structures in vivo
High-Mobility Few-Layer Graphene Field Effect Transistors Fabricated on Epitaxial Ferroelectric Gate Oxides
The carrier mobility \mu of few-layer graphene (FLG) field-effect transistors
increases ten-fold when the SiO_2 substrate is replaced by single-crystal
epitaxial Pb(Zr_0.2Ti_0.8)O_3 (PZT). In the electron-only regime of the FLG,
\mu reaches 7x10^4 cm^2/Vs at 300K for n = 2.4x10^12/cm^2, 70% of the intrinsic
limit set by longitudinal acoustic (LA) phonons; it increases to 1.4x10^5
cm^2/Vs at low temperature. The temperature-dependent resistivity \rho(T)
reveals a clear signature of LA phonon scattering, yielding a deformation
potential D = 7.8+/-0.5 eV.Comment: 5 pages, 4 figure
Comparative study of CXC chemokines modulation in brown trout (Salmo trutta) following infection with a bacterial or viral pathogen
Acknowledgements We would like to acknowledge Richard Paley, Tom Hill and Georgina Rimmer for their collaboration during brown trout infection challenges in CEFAS-Weymouth biosecurity facilities. Bartolomeo Gorgoglione, Stephen W. Feist and Nick G. H. Taylor were supported by a DEFRA grant (F1198).Peer reviewedPostprin
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