398 research outputs found
The agrin gene codes for a family of basal lamina proteins that differ in function and distribution
We isolated two cDNAs that encode isoforms of agrin, the basal lamina protein that mediates the motor neuron-induced aggregation of acetylcholine receptors on muscle fibers at the neuromuscular junction. Both proteins are the result of alternative splicing of the product of the agrin gene, but, unlike agrin, they are inactive in standard acetylcholine receptor aggregation assays. They lack one (agrin-related protein 1) or two (agrin-related protein 2) regions in agrin that are required for its activity. Expression studies provide evidence that both proteins are present in the nervous system and muscle and that, in muscle, myofibers and Schwann cells synthesize the agrin-related proteins while the axon terminals of motor neurons are the sole source of agrin
Magnetic Excitations and Continuum of a Field-Induced Quantum Spin Liquid in -RuCl
We report on terahertz spectroscopy of quantum spin dynamics in
-RuCl, a system proximate to the Kitaev honeycomb model, as a
function of temperature and magnetic field. An extended magnetic continuum
develops below the structural phase transition at K. With the onset
of a long-range magnetic order at K, spectral weight is transferred to
a well-defined magnetic excitation at meV, which is
accompanied by a higher-energy band at meV. Both
excitations soften in magnetic field, signaling a quantum phase transition at
T where we find a broad continuum dominating the dynamical response.
Above , the long-range order is suppressed, and on top of the continuum,
various emergent magnetic excitations evolve. These excitations follow clear
selection rules and exhibit distinct field dependencies, characterizing the
dynamical properties of the field-induced quantum spin liquid
Inhomogeneity of donor doping in SrTiO3 substrates studied by fluorescence-lifetime imaging microscopy
Fluorescence-lifetime imaging microscopy (FLIM) was applied to investigate
the donor distribution in SrTiO3 single crystals. On the surfaces of Nb- and
La-doped SrTiO3, structures with different fluorescence intensities and
lifetimes were found that could be related to different concentrations of Ti3+.
Furthermore, the inhomogeneous distribution of donors caused a non-uniform
conductivity of the surface, which complicates the production of potential
electronic devices by the deposition of oxide thin films on top of doped single
crystals. Hence, we propose FLIM as a convenient technique (length scale: 1
m) for characterizing the quality of doped oxide surfaces, which could
help to identify appropriate substrate materials
- …