A Spike-Timing Pattern Based Neural Network Model for the Study of Memory Dynamics

It is well accepted that the brain's computation relies on spatiotemporal activity of neural networks. In particular, there is growing evidence of the importance of continuously and precisely timed spiking activity. Therefore, it is important to characterize memory states in terms of spike-timing patterns that give both reliable memory of firing activities and precise memory of firing timings. The relationship between memory states and spike-timing patterns has been studied empirically with large-scale recording of neuron population in recent years. Here, by using a recurrent neural network model with dynamics at two time scales, we construct a dynamical memory network model which embeds both fast neural and synaptic variation and slow learning dynamics. A state vector is proposed to describe memory states in terms of spike-timing patterns of neural population, and a distance measure of state vector is defined to study several important phenomena of memory dynamics: partial memory recall, learning efficiency, learning with correlated stimuli. We show that the distance measure can capture the timing difference of memory states. In addition, we examine the influence of network topology on learning ability, and show that local connections can increase the network's ability to embed more memory states. Together theses results suggest that the proposed system based on spike-timing patterns gives a productive model for the study of detailed learning and memory dynamics

Bis(2,4-dichloro­phen­oxy­acetato-κ2 O 1,O 1′)(5,5′-dimethyl-2,2′-bipyridine-κ2 N,N′)cobalt(II)

In the title compound, [Co(C8H5Cl2O3)(C12H12N2)], the CoII atom, lying on a twofold rotation axis, is coordinated by four O atoms from two chelating 2,4-dichloro­phen­oxy­acetate ligands and two N atoms from a 5,5′-dimethyl-2,2′-bipyridine ligand, displaying a distorted octa­hedral geometry. A three-dimensional supra­molecular structure is formed through inter­molecular C—H⋯O hydrogen bonds and π–π stacking inter­actions between the pyridine and benzene rings [centroid–centroid distance = 3.779 (2) Å]

Observing the origin of superconductivity in quantum critical metals

Despite intense efforts during the last 25 years, the physics of unconventional superconductors, including the cuprates with a very high transition temperature, is still a controversial subject. It is believed that superconductivity in many of these strongly correlated metallic systems originates in the physics of quantum phase transitions, but quite diverse perspectives have emerged on the fundamentals of the electron-pairing physics, ranging from Hertz style critical spin fluctuation glue to the holographic superconductivity of string theory. Here we demonstrate that the gross energy scaling differences that are behind these various pairing mechanisms are directly encoded in the frequency and temperature dependence of the dynamical pair susceptibility. This quantity can be measured directly via the second order Josephson effect and it should be possible employing modern experimental techniques to build a `pairing telescope' that gives a direct view on the origin of quantum critical superconductivity.Comment: 19 pages, 9 figures; minor changes in the experimental part; added a new appendix section calculating the pair susceptibility of marginal Fermi liqui

Device modeling of superconductor transition edge sensors based on the two-fluid theory

In order to support the design and study of sophisticated large scale transition edge sensor (TES) circuits, we use basic SPICE elements to develop device models for TESs based on the superfluid-normal fluid theory. In contrast to previous studies, our device model is not limited to small signal simulation, and it relies only on device parameters that have clear physical meaning and can be easily measured. We integrate the device models in design kits based on powerful EDA tools such as CADENCE and OrCAD, and use them for versatile simulations of TES circuits. Comparing our simulation results with published experimental data, we find good agreement which suggests that device models based on the two-fluid theory can be used to predict the behavior of TES circuits reliably and hence they are valuable for assisting the design of sophisticated TES circuits.Comment: 10pages,11figures. Accepted to IEEE Trans. Appl. Supercon

(5,5′-Dimethyl-2,2′-bipyridine-κ2 N,N′)(1-naphthyl­acetato-κO)(1-naphthyl­acetato-κ2 O,O′)zinc hemihydrate

In the title compound, [Zn(C12H9O2)2(C12H12N2)]·0.5H2O, the water mol­ecule lies on a twofold rotation axis. The ZnII atom is coordinated by three O atoms from two 1-naphthyl­acetate ligands, one monodentate and the other asymmetric bidentate chelate, and two N atoms from a 5,5′-dimethyl-2,2′-bipyridine ligand, giving an irregular environment. In the crystal, the complex mol­ecules are inter­linked through the water mol­ecule by O—H⋯Ocarboxyl­ate hydrogen bonds, together with weak C—H⋯O and bipyridine ring π–π stacking inter­actions [ring centroid separation = 3.761 (2) Å], giving a two-dimensional network structure

Tetra­aqua­bis­[4-(1H-imidazol-1-yl-κN 3)benzoato]cobalt(II)

In the title compound, [Co(C10H7N2O2)2(H2O)4], the CoII atom lies on an inversion centre and displays a slightly distorted octa­hedral geometry. The coordination sphere is defined by two mutually trans N atoms from two 4-(imidazol-1-yl)benzoate ligands and the O atoms from four water mol­ecules. The crystal structure is stabilized by O—H⋯O hydrogen bonds

{2,6-Bis[(4-bromo­phen­yl)imino­meth­yl]pyridine-κ3 N,N′,N′′}trichlorido­chromium(III)

In the title compound, [CrCl3(C19H13Br2N3)], the Cr3+ ion is coordinated by the tridentate 2,6-bis­[(4-bromo­phen­yl)imino­meth­yl]pyridine Schiff base ligand in a fac-octa­hedral geometry. The dihedral angles between the pyridine and benzene rings are 23.9 (6) and 70.7 (1)°

Energy dependence of light (anti)nuclei and (anti)hypertriton production in the Au-Au collision from sNN=5.0\sqrt{s_{\rm{NN}}} =5.0 to 50205020 GeV

The energy dependence of light (anti)nuclei and (anti)hypertriton production are investigated in central Au-Au collisions from AGS up to LHC energies at midrapidity, using the parton and hadron cascade model (PACIAE) together with the dynamically constrained phase-space coalescence model(DCPC). We find that the yields, yield ratios of the antiparticles to their corresponding particles, the coalescence parameters $B_A$ and the strangeness population factor $s_3$ of light (anti)nuclei and (anti)hypertriton strongly depend on the energy. Furthermore, we analyze and discuss the strangeness population factor $s_3$ and the coalescence parameters $B_A$, and find a transition point near by 20 GeV. These results thus suggest the potential usefulness of the $s_3$ and $B_A$ of light nuclei production in relativistic heavy-ion collisions as a direct probe of the transition point associated with the QCD critical phenomena. The results from PACIAE+DCPC model are well consistent with experimental data