Many-body correlations in one-dimensional optical lattices with alkaline-earth(-like) atoms.

We explore the rich nature of correlations in the ground state of ultracold atoms trapped in state-dependent optical lattices. In particular, we consider interacting fermionic ytterbium or strontium atoms, realizing a two-orbital Hubbard model with two spin components. We analyze the model in one-dimensional setting with the experimentally relevant hierarchy of tunneling and interaction amplitudes by means of exact diagonalization and matrix product states approaches, and study the correlation functions in density, spin, and orbital sectors as functions of variable densities of atoms in the ground and metastable excited states. We show that in certain ranges of densities these atomic systems demonstrate strong density-wave, ferro- and antiferromagnetic, as well as antiferroorbital correlations.

The involvement of serotonergic system in the antidepressant effect of zinc in the forced swim test.

Recent preclinical data indicated the antidepressant-like activity of zinc in different tests and models of depression. The present study investigates the involvement of the serotonergic system in zinc activity in the forced swim test (FST) in mice and rats. The combined treatment of sub-effective doses of zinc (hydroaspartate, 2.5 mg Zn/kg) and citalopram (15 mg/kg), fluoxetine (5 mg/kg) but not with reboxetine (2.5 mg/kg) significantly reduces the immobility time in the FST in mice. These treatments had no influence on the spontaneous locomotor activity. Moreover, while the antidepressant-like effect of zinc (5 mg/kg) in the FST was significantly blocked by pretreatment with inhibitor of serotonin synthesis, p-chlorophenylalanine (pCPA, 3x200 mg/kg), 5HT-2(A/C) receptor antagonist, ritanserin (4 mg/kg) or 5HT-1A receptor antagonist, WAY 1006335 (0.1 mg/kg), the zinc-induced reduction in the locomotor activity was not affected by these serotonin modulator agents. These results indicate the specific involvement of the serotonergic system in antidepressant but not the motion behavior of zinc in mice. Also, an increase in the swimming but not climbing parameter of the rat FST observed following zinc administration (2.5 and 5 mg Zn/kg) indicates the serotonin pathway participation. This present data indicates that the antidepressant-like activity of zinc observed in the FST involves interaction with the serotonergic system.

Phase separations induced by a trapping potential in one-dimensional fermionic systems as a source of core-shell structures.

Ultracold fermionic gases in optical lattices give a great opportunity for creating different types of novel states. One of them is phase separation induced by a trapping potential between different types of superfluid phases. The core-shell structures, occurring in systems with a trapping potential, are a good example of such separations. The types and the sequences of phases which emerge in such structures can depend on spin-imbalance, shape of the trap and on-site interaction strength. In this work, we investigate the properties of such structures within an attractive Fermi gas loaded in the optical lattice, in the presence of the trapping potential and their relations to the phase diagram of the homogeneous system. Moreover, we show how external and internal parameters of the system and parameters of the trap influence their properties. In particular, we show a possible occurrence of the core-shell structure in a system with a harmonic trap, containing the BCS and FFLO states. Additionally, we find a spatial separation of two superfuild states in the system, one in the BCS limit as well as the other one in the tightly bound local pairs (BEC) regime.

Quantum engineering of Majorana quasiparticles in one-dimensional optical lattices.

We propose a feasible way of engineering Majorana-type quasiparticles in ultracold fermionic gases on a one-dimensional (1D) optical lattice. For this purpose, imbalanced ultracold atoms interacting by the spin-orbit coupling should be hybridized with a three-dimensional Bose-Einstein condensate molecular cloud. We show that the Majorana-type excitations can be created or annihilated upon constraining the profile of a trapping potential and/or an internal scattering barier. This process is modeled within the Bogoliubov-de Gennes approach. Our study is relevant also to nanoscopic 1D superconductors, where both potentials can be imposed by electrostatic means.

Magnetic Lifshitz transition and its consequences in multi-band iron-based superconductors.

In this paper we address Lifshitz transition induced by applied external magnetic field in a case of iron-based superconductors, in which a difference between the Fermi level and the edges of the bands is relatively small. We introduce and investigate a two-band model with intra-band pairing in the relevant parameters regime to address a generic behaviour of a system with hole-like and electron-like bands in external magnetic field. Our results show that two Lifshitz transitions can develop in analysed systems and the first one occurs in the superconducting phase and takes place at approximately constant magnetic field. The chosen sets of the model parameters can describe characteristic band structure of iron-based superconductors and thus the obtained results can explain the experimental observations in FeSe and Co-doped BaFe2As2 compounds.

Medium supplementation with zinc enables detection of imipramine-induced adaptation in glycine/NMDA receptors labeled with [3H]L-689,560.

Antidepressant drugs after chronic administration induce adaptive changes in the NMDA receptor complex. Radioligand-receptorbinding studies using [3H]5,7-dichlorokynurenic acid demonstrated a "down-regulation" of the glycine site/NMDA receptor following chronic treatment with antidepressants and electroconvulsive shock. However, binding procedure using this radioligand is time consuming because it requires the use of centrifugation method in the separation process. The introduction of a new radioligand of glycine/NMDA receptor, [3H]L-689,560 enables the application of a rapid filtration method. In the present study we demonstrate that 2-week treatment with imipramine (15 mg/kg ip) did not evoke alterations in specific [3H]L-689,560 binding and in IC50 value of glycine in displacing [3H]L-689,560 binding in the mouse or rat cortex. However, longer, a 4-week treatment with imipramine induced a significant 71% increase in IC50 value in displacing [3H]L-689.560 binding in the mouse cortex. Moreover, the presence of zinc in the incubation media, dose-dependently enhances detection of imipramine-induced increase in IC50 value of glycine in displacing [3H]L-689,560 binding in the rat cortex. The present data indicate that: (1) [3H]L-689,560 may be a suitable ligand for assessing adaptation of the glycine/NMDA sites and (2) the presence of zinc enhances detection of imipramine-induced reduction of glycine affinity for glycine/NMDA receptors labeled with [3H]L-689,560 which further indicates a significance of zinc in the mechanism of antidepressant treatment.

Zinc-induced adaptive changes in NMDA/glutamatergic and serotonergic receptors.

Preclinical data indicate the involvement of glutamatergic and serotonergic pathways in the antidepressant activity of zinc. The present study investigated alterations in N-methyl-D-aspartate (NMDA)/glutamatergic and serotonergic receptors (using radioligand binding) induced by chronic treatment (14-day) with zinc hydroaspartate (65 mg/kg). Moreover, the mRNA and protein levels of brain-derived neurotrophic factor (BDNF) were also assessed. Chronic zinc administration reduced the affinity of glycine to glycine/NMDA receptors in the rat frontal cortex and increased the density of 5-HT(1A) and 5-HT(2A) serotonin receptors in the hippocampus and frontal cortex, respectively. These receptor alterations may be in part due to increased BDNF mRNA and protein levels in the rat frontal cortex. These results indicate that chronic zinc treatment alters glutamatergic and serotonergic systems, which is a hallmark of clinically effective antidepressants.