Hadronic coupling constants in lattice QCD

We report on calculations of the hadronic coupling constants $g_{\rho\pi\pi}$ and $g_{nn\pi}$ based on lattice QCD with four flavors of dynamical staggered fermions. By computing 2--point and 3--point Green's functions we have been able to determine these coupling constants ab initio from QCD; the results are compatible with the experimental values.Comment: 3 Page

Hadronic Coupling Constants in Lattice QCD

We calculate the hadronic coupling constants $g_{NN\pi}$ and $g_{\rho\pi\pi}$ in QCD, including dynamical quarks in the framework of staggered fermions in the lattice approach. For the nucleon--pion coupling we obtain $g_{NN\pi} = 13.8 \pm 5.8$, to be compared with the experimental value $13.13 \pm 0.07$. The $\rho\pi\pi$ coupling has been analysed for two different sets of operators with the averaged result $g_{\rho\pi\pi} = 4.2 \pm 1.9$ which is to be compared with the experimental value $6.06 \pm 0.01$.Comment: 14 pages uuencoded postscript fil

Effect of isoelectronic doping on honeycomb lattice iridate A_2IrO_3

We have investigated experimentally and theoretically the series (Na$_{1-x}$Li$_{x}$)$_{2}$IrO$_{3}$. Contrary to what has been believed so far, only for $x\leq0.25$ the system forms uniform solid solutions. For larger Li content, as evidenced by powder X-ray diffraction, scanning electron microscopy and density functional theory calculations, the system shows a miscibility gap and a phase separation into an ordered Na$_{3}$LiIr$_2$O$_{6}$ phase with alternating Na$_3$ and LiIr$_2$O$_6$ planes, and a Li-rich phase close to pure Li$_{2}$IrO$_{3}$. For $x\leq 0.25$ we observe (1) an increase of $c/a$ with Li doping up to $x=0.25$, despite the fact that $c/a$ in pure Li$_{2}$IrO$_{3}$ is smaller than in Na$_{2}$IrO$_{3}$, and (2) a gradual reduction of the antiferromagnetic ordering temperature $T_{N}$ and ordered moment. The previously proposed magnetic quantum phase transition at $x\approx 0.7$ may occur in a multiphase region and its nature needs to be re-evaluated.Comment: 8 pages, 9 figures including supplemental informatio

Association of CD69 Up-Regulation on CD4+ CLA+ T cells versus patch test, strip patch test and clinical history in nickel sensitization

<p>Abstract</p> <p>Objective</p> <p>The patch test (PT) with its modification - the strip patch test (SPT) - is the standard in vivo procedure to diagnose an allergic contact dermatitis (ACD). To date, none of the in vitro tests for the diagnosis of ACD fulfils the requirements of an easy, valid and reliable test. To investigate the prediction ability of a flow cytometric assay of CD69 up-regulation on CD4+ CLA+ T cells in nickel-sensitive and non-nickel-sensitive patients.</p> <p>Methods</p> <p>In a prospective, investigator-blinded, clinical study a total of 85 nickel-sensitive (n = 44; 51.8%) and non-nickel-sensitive patients (n = 41; 48.2%) were enrolled. The association between CD69 up-regulation on CD4+ CLA+ T cells on the one hand and PT, SPT, and clinical history on the other hand was measured. Association is expressed with c statistic values (receiver operating characteristic analysis) and corresponding 95% CIs.</p> <p>Results</p> <p>The associations were c = 0.57 (95% CI: 0.42-0.72) between CD69 up-regulation and PT, c = 0.49 (95% CI: 0.36-0.62) between CD69 up-regulation and SPT, and c = 0.51 (95% CI: 0.37-0.64) between CD69 up-regulation and clinical history.</p> <p>Conclusions</p> <p>CD69 up-regulation on CD4+ CLA+ T cells in vitro could not predict neither a positive PT or SPT result nor a positive clinical history to nickel sulfate. The combination of clinical history and patch testing still remains the basis for diagnosing ACD.</p

Collective excitations of a degenerate gas at the BEC-BCS crossover

We study collective excitation modes of a fermionic gas of $^6$Li atoms in the BEC-BCS crossover regime. While measurements of the axial compression mode in the cigar-shaped trap close to a Feshbach resonance confirm theoretical expectations, the radial compression mode shows surprising features. In the strongly interacting molecular BEC regime we observe a negative frequency shift with increasing coupling strength. In the regime of a strongly interacting Fermi gas, an abrupt change in the collective excitation frequency occurs, which may be a signature for a transition from a superfluid to a collisionless phase.Comment: Feshbach resonance position updated, few minor change

Planar manipulation of magneto-tactic bacteria using unidirectional magnetic fields

We show for the first time that an alternating unidirectional magnetic field generated by a magnetic erase head allows planar manipulation of magneto-tactic bacteria (MTB), and is not restricted to parallel directions only. We used squared-shaped magnetic fields of approximately 4 mT while sweeping from 0.25 to 10 Hz, and found that at frequencies of over 3 Hz the mean orthogonal velocity becomes constant. The erase head offers a significant reduction in size and complexity over conventional manipulators