81 research outputs found
Approaching Zero-Temperature Metallic States in Mesoscopic Superconductor-Normal-Superconductor Arrays
Systems of superconducting islands placed on normal metal films offer tunable
realizations of two-dimensional (2D) superconductivity; they can thus elucidate
open questions regarding the nature of 2D superconductors and competing states.
In particular, island systems have been predicted to exhibit zero-temperature
metallic states. Although evidence exists for such metallic states in some 2D
systems, their character is not well understood: the conventional theory of
metals cannot explain them, and their properties are difficult to tune. Here,
we characterize the superconducting transitions in mesoscopic island-array
systems as a function of island thickness and spacing. We observe two
transitions in the progression to superconductivity; both transition
temperatures exhibit unexpectedly strong depression for widely spaced islands.
These depressions are consistent with the system approaching zero-temperature
metallic states. The nature of the transitions and the state between them is
explained using a phenomenological model involving the stabilization of
superconductivity on each island via a weak coupling to and feedback from its
neighbors.Comment: 15 pages, 5 figure
Regulation of Spike Timing-Dependent Plasticity of Olfactory Inputs in Mitral Cells in the Rat Olfactory Bulb
The recent history of activity input onto granule cells (GCs) in the main olfactory bulb can affect the strength of lateral inhibition, which functions to generate contrast enhancement. However, at the plasticity level, it is unknown whether and how the prior modification of lateral inhibition modulates the subsequent induction of long-lasting changes of the excitatory olfactory nerve (ON) inputs to mitral cells (MCs). Here we found that the repetitive stimulation of two distinct excitatory inputs to the GCs induced a persistent modification of lateral inhibition in MCs in opposing directions. This bidirectional modification of inhibitory inputs differentially regulated the subsequent synaptic plasticity of the excitatory ON inputs to the MCs, which was induced by the repetitive pairing of excitatory postsynaptic potentials (EPSPs) with postsynaptic bursts. The regulation of spike timing-dependent plasticity (STDP) was achieved by the regulation of the inter-spike-interval (ISI) of the postsynaptic bursts. This novel form of inhibition-dependent regulation of plasticity may contribute to the encoding or processing of olfactory information in the olfactory bulb
Edwardsiella Comparative Phylogenomics Reveal the New Intra/Inter-Species Taxonomic Relationships, Virulence Evolution and Niche Adaptation Mechanisms
Edwardsiella bacteria are leading fish pathogens causing huge losses to aquaculture industries worldwide. E. tarda is a broad-host range pathogen that infects more than 20 species of fish and other animals including humans while E. ictaluri is host-adapted to channel catfish causing enteric septicemia of catfish (ESC). Thus, these two species consist of a useful comparative system for studying the intricacies of pathogen evolution. Here we present for the first time the phylogenomic comparisons of 8 genomes of E. tarda and E. ictaluri isolates. Genome-based phylogenetic analysis revealed that E. tarda could be separate into two kinds of genotypes (genotype I, EdwGI and genotype II, EdwGII) based on the sequence similarity. E. tarda strains of EdwGI were clustered together with the E. ictaluri lineage and showed low sequence conservation to E. tarda strains of EdwGII. Multilocus sequence analysis (MLSA) of 48 distinct Edwardsiella strains also supports the new taxonomic relationship of the lineages. We identified the type III and VI secretion systems (T3SS and T6SS) as well as iron scavenging related genes that fulfilled the criteria of a key evolutionary factor likely facilitating the virulence evolution and adaptation to a broad range of hosts in EdwGI E. tarda. The surface structure-related genes may underlie the adaptive evolution of E. ictaluri in the host specification processes. Virulence and competition assays of the null mutants of the representative genes experimentally confirmed their contributive roles in the evolution/niche adaptive processes. We also reconstructed the hypothetical evolutionary pathway to highlight the virulence evolution and niche adaptation mechanisms of Edwardsiella. This study may facilitate the development of diagnostics, vaccines, and therapeutics for this under-studied pathogen
Transforming community prevention systems for sustained impact: embedding active implementation and scaling functions
RESISTIVE TRANSITION OF SIERPINSKI GASKET ARRAYS OF WEAK JOSEPHSON-JUNCTIONS
X115sciescopu
POSITIONAL DISORDER IN JOSEPHSON-JUNCTION ARRAYS - EXPERIMENTS AND SIMULATIONS
open1170sciescopu
Qualitatively different scenarios for co-activation of NMDA, AMPA and GABA receptor currents on dopaminergic neuron
T-type calcium channels trigger a hyperpolarization induced afterdepolarization in substantia nigra dopamine neurons
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