13 research outputs found
Distinct but overlapping roles of LRRTM1 and LRRTM2 in developing and mature hippocampal circuits
LRRTMs are postsynaptic cell adhesion proteins that have region-restricted expression in the brain. To determine their role in the molecular organization of synapses in vivo, we studied synapse development and plasticity in hippocampal neuronal circuits in mice lacking both Lrrtm1 and Lrrtm2. We found that LRRTM1 and LRRTM2 regulate the density and morphological integrity of excitatory synapses on CA1 pyramidal neurons in the developing brain but are not essential for these roles in the mature circuit. Further, they are required for long-term-potentiation in the CA3-CA1 pathway and the dentate gyrus, and for enduring fear memory in both the developing and mature brain. Our data show that LRRTM1 and LRRTM2 regulate synapse development and function in a cell-type and developmental-stage-specific manner, and thereby contribute to the fine-tuning of hippocampal circuit connectivity and plasticity
Two superconducting states with broken time-reversal symmetry in FeSe1-xSx
Iron-chalcogenide superconductors FeSeS possess unique electronic
properties such as non-magnetic nematic order and its quantum critical point.
The nature of superconductivity with such nematicity is important for
understanding the mechanism of unconventional superconductivity. A recent
theory suggested the possible emergence of a fundamentally new class of
superconductivity with the so-called Bogoliubov Fermi surfaces (BFSs) in this
system. However, such an {\em ultranodal} pair state requires broken
time-reversal symmetry (TRS) in the superconducting state, which has not been
observed experimentally. Here we report muon spin relaxation (SR)
measurements in FeSeS superconductors for
covering both orthorhombic (nematic) and tetragonal phases. We find that the
zero-field muon relaxation rate is enhanced below the superconducting
transition temperature for all compositions, indicating that the
superconducting state breaks TRS both in the nematic and tetragonal phases.
Moreover, the transverse-field SR measurements reveal that the superfluid
density shows an unexpected and substantial reduction in the tetragonal phase
(). This implies that a significant fraction of electrons remain
unpaired in the zero-temperature limit, which cannot be explained by the known
unconventional superconducting states with point or line nodes. The
time-reversal symmetry breaking and the suppressed superfluid density in the
tetragonal phase, together with the reported enhanced zero-energy excitations,
are consistent with the ultranodal pair state with BFSs. The present results
reveal two different superconducting states with broken TRS separated by the
nematic critical point in FeSeS, which calls for the theory of
microscopic origins that account for the relation between the nematicity and
superconductivity.Comment: 8 pages, 4 figures, typos corrected. Accepted for publication in PNA
Adjuvant immunochemotherapy with oral Tegafur/Uracil plus PSK in patients with stage II or III colorectal cancer: a randomised controlled study
Individual differences in the Behavioral Inhibition System are associated with orbitofrontal cortex and precuneus gray matter volume
Bulk evidence of anisotropic s-wave pairing with no sign change in the kagome superconductor CsV3Sb5
International audienceThe recently discovered kagome superconductors AV3Sb5 (A = K, Rb, Cs) exhibit unusual charge-density-wave (CDW) orders with time-reversal and rotational symmetry breaking. One of the most crucial unresolved issues is identifying the symmetry of the superconductivity that develops inside the CDW phase. Theory predicts a variety of unconventional superconducting symmetries with sign-changing and chiral order parameters. Experimentally, however, superconducting phase information in AV3Sb5 is still lacking. Here we report the impurity effects in CsV3Sb5 using electron irradiation as a phase-sensitive probe of superconductivity. Our magnetic penetration depth measurements reveal that with increasing impurities, an anisotropic fully-gapped state changes to an isotropic full-gap state without passing through a nodal state. Furthermore, transport measurements under pressure show that the double superconducting dome in the pressure-temperature phase diagram survives against sufficient impurities. These results support that CsV3Sb5 is a non-chiral, anisotropic s-wave superconductor with no sign change both at ambient and under pressure