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 f0(980)f_0(980)-a0(980)a_0(980) mixing in the η(1405)→π0f0(980)\eta(1405) \to \pi^{0} f_0(980) reaction

We make a theoretical study of the $\eta(1405) \to \pi^{0} f_0(980)$ and $\eta(1405) \to \pi^{0} a_0(980)$ reactions with an aim to determine the isospin violation and the mixing of the $f_0(980)$ and $a_0(980)$ 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 $f_0(980)$ production in agreement with a BES experiment. As to the amount of isospin violation, or $f_0(980)$ and $a_0(980)$ mixing, assuming constant vertices for the primary $\eta(1405)\rightarrow \pi^{0}K\bar{K}$ and $\eta(1405)\rightarrow \pi^{0}\pi^{0}\eta$ 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 $\eta(1405)$ wave function, but this leads to a much bigger width of the $f_0(980)$ mass distribution than observed experimentally. The problem is solved by using the primary production driven by $\eta' \to K^* \bar K$ followed by $K^* \to K \pi$, which induces an extra singularity in the loop functions needed to produce the $f_0(980)$ and $a_0(980)$ resonances. Improving upon earlier work along the same lines, and using the chiral unitary approach, we can now predict absolute values for the ratio $\Gamma(\pi^0, \pi^+ \pi^-)/\Gamma(\pi^0, \pi^0 \eta)$ which are in fair agreement with experiment. We also show that the same results hold if we had the $\eta(1475)$ 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 $\mu_s$ of the proton and the longstanding mass-reverse problem of S11(1535) and $P11(1440) N* resonances. A model-prediction for the$\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