Oscillation death in coupled counter-rotating identical nonlinear oscillators

We study oscillatory and oscillation suppressed phases in coupled counter-rotating nonlinear oscillators. We demonstrate the existence of limit cycle, amplitude death, and oscillation death, and also clarify the Hopf, pitchfork, and infinite period bifurcations between them. Especially, the oscillation death is a new type of oscillation suppressions of which the inhomogeneous steady states are neutrally stable. We discuss the robust neutral stability of the oscillation death in non-conservative systems via the anti-PT-symmetric phase transitions at exceptional points in terms of non-Hermitian systems.Comment: 7 pages, 4 figure

Amplitude death in a ring of nonidentical nonlinear oscillators with unidirectional coupling

We study the collective behaviors in a ring of coupled nonidentical nonlinear oscillators with unidirectional coupling, of which natural frequencies are distributed in a random way. We find the amplitude death phenomena in the case of unidirectional couplings and discuss the differences between the cases of bidirectional and unidirectional couplings. There are three main differences; there exists neither partial amplitude death nor local clustering behavior but oblique line structure which represents directional signal flow on the spatio-temporal patterns in the unidirectional coupling case. The unidirectional coupling has the advantage of easily obtaining global amplitude death in a ring of coupled oscillators with randomly distributed natural frequency. Finally, we explain the results using the eigenvalue analysis of Jacobian matrix at the origin and also discuss the transition of dynamical behavior coming from connection structure as coupling strength increases.Comment: 14 pages, 11 figure

GROWING HIERARCHICAL SCALE-FREE NETWORKS BY MEANS OF NONHIERARCHICAL PROCESSES

We introduce a fully nonhierarchical network growing mechanism, that furthermore does not impose explicit preferential attachment rules. The growing procedure produces a graph featuring power-law degree and clustering distributions, and manifesting slightly disassortative degree-degree correlations. The rigorous rate equations for the evolution of the degree distribution and for the conditional degree-degree probability are derived

Chronobiology of Epilepsy

A fine balance between neuronal excitation and inhibition governs the physiological state of the brain. It has been hypothesized that when this balance is lost as a result of excessive excitation or reduced inhibition, pathological states such as epilepsy emerge. Decades of investigation have shown this to be true in vitro. However, in vivo evidence of the emerging imbalance during the "latent period" between the initiation of injury and the expression of the first spontaneous behavioral seizure has not been demonstrated. Here, we provide the first demonstration of this emerging imbalance between excitation and inhibition in vivo by employing long term, high temporal resolution, and continuous local field recordings from microelectrode arrays implanted in an animal model of limbic epilepsy. We were able to track both the inhibitory and excitatory postsynaptic field activity during the entire latent period, from the time of injury to the occurrence of the first spontaneous epileptic seizure. During this latent period we observe a sustained increase in the firing rate of the excitatory postsynaptic field activity, paired with a subsequent decrease in the firing rate of the inhibitory postsynaptic field activity within the CA1 region of the hippocampus. Firing rates of both excitatory and inhibitory CA1 field activities followed a circadian- like rhythm, which is locked near in-phase in controls and near anti-phase during the latent period. We think that these observed changes are implicated in the occurrence of spontaneous seizure onset following injury

A Planetary lensing feature in caustic-crossing high-magnification microlensing events

Current microlensing follow-up observations focus on high-magnification events because of the high efficiency of planet detection. However, central perturbations of high-magnification events caused by a planet can also be produced by a very close or a very wide binary companion, and the two kinds of central perturbations are not generally distinguished without time consuming detailed modeling (a planet-binary degeneracy). Hence, it is important to resolve the planet-binary degeneracy that occurs in high-magnification events. In this paper, we investigate caustic-crossing high-magnification events caused by a planet and a wide binary companion. From this study, we find that because of the different magnification excess patterns inside the central caustics induced by the planet and the binary companion, the light curves of the caustic-crossing planetary-lensing events exhibit a feature that is discriminated from those of the caustic-crossing binary-lensing events, and the feature can be used to immediately distinguish between the planetary and binary companions. The planetary-lensing feature appears in the interpeak region between the two peaks of the caustic-crossings. The structure of the interpeak region for the planetary-lensing events is smooth and convex or boxy, whereas the structure for the binary-lensing events is smooth and concave. We also investigate the effect of a finite background source star on the planetary-lensing feature in the caustic-crossing high-magnification events. From this, we find that the convex-shaped interpeak structure appears in a certain range that changes with the mass ratio of the planet to the planet-hosting star.Comment: 14 pages, 4 figures. Accepted for publication in Ap

Effects of Anode Nozzle Geometry on Ambient Air Entrainment into Thermal Plasma Jets Generated by Non-Transferred Plasma Torch

The geometrical effects of anode nozzle in a non-transferred plasma torch on air entrainment are examined by measurements of plasma composition using a quadruple mass spectrometry. In addition, the radial and axial distributions of plasma enthalpy, temperature and velocity are measured by using an enthalpy probe method. Two types of anode nozzle geometry, i.e., cylindrical and stepped nozzles, are employed for the torch in this experiment. As a result of gas composition measurements, the new stepped nozzle turns out to produce a thermal plasma jet having lower air contents in it compared with the conventional cylindrical nozzle. The plasma jet produced by the stepped nozzle exhibits higher enthalpy and temperature, especially around the core of the plasma flame due to less intrusion of ambient air. Furthermore, the axial velocity distribution with a slowly changing variation is observed in the stepped nozzle case because of the plasma flow less disturbed by air entrainment. From these experimental results of thermal plasma characteristics and nozzle geometry effects on air entrainment, high quality of coating products are expected in plasma spraying by using the stepped nozzle due to higher plasma enthalpy and temperature, and lower velocity drop along the plasma jet

KMT-2016-BLG-1107: A New Hollywood-Planet Close/Wide Degeneracy

We show that microlensing event KMT-2016-BLG-1107 displays a new type of degeneracy between wide-binary and close-binary Hollywood events in which a giant-star source envelops the planetary caustic. The planetary anomaly takes the form of a smooth, two-day "bump" far out on the falling wing of the light curve, which can be interpreted either as the source completely enveloping a minor-image caustic due to a close companion with mass ratio $q=0.036$, or partially enveloping a major-image caustic due to a wide companion with $q=0.004$. The best estimates of the companion masses are both in the planetary regime ($3.3^{+3.5}_{-1.8}\,M_{\rm jup}$ and $0.090^{+0.096}_{-0.037}\,M_{\rm jup}$) but differ by an even larger factor than the mass ratios due to different inferred host masses. We show that the two solutions can be distinguished by high-resolution imaging at first light on next-generation ("30m") telescopes. We provide analytic guidance to understand the conditions under which this new type of degeneracy can appear.Comment: 23 pages, 7 figures, accepted for publication in A

KMT-2018-BLG-1990Lb: A Nearby Jovian Planet From A Low-Cadence Microlensing Field

We report the discovery and characterization of KMT-2018-BLG-1990Lb, a Jovian planet $(m_p=0.57_{-0.25}^{+0.79}\,M_J)$ orbiting a late M dwarf $(M=0.14_{-0.06}^{+0.20}\,M_\odot)$, at a distance (D_L=1.23_{-0.43}^{+1.06}\,\kpc), and projected at $2.6\pm 0.6$ times the snow line distance, i.e., a_{\rm snow}\equiv 2.7\,\au (M/M_\odot), This is the second Jovian planet discovered by KMTNet in its low cadence ($0.4\,{\rm hr}^{-1}$) fields, demonstrating that this population will be well characterized based on survey-only microlensing data.Comment: 24 pages, 7 figures, 4 table

KMT-2018-BLG-1292: A Super-Jovian Microlens Planet in the Galactic Plane

We report the discovery of KMT-2018-BLG-1292Lb, a super-Jovian $M_{\rm planet} = 4.5\pm 1.3\,M_J$ planet orbiting an F or G dwarf $M_{\rm host} = 1.5\pm 0.4\,M_\odot$, which lies physically within {\cal O}(10\,\pc) of the Galactic plane. The source star is a heavily extincted $A_I\sim 5.2$ luminous giant that has the lowest Galactic latitude, $b=-0.28^\circ$, of any planetary microlensing event. The relatively blue blended light is almost certainly either the host or its binary companion, with the first explanation being substantially more likely. This blend dominates the light at $I$ band and completely dominates at $R$ and $V$ bands. Hence, the lens system can be probed by follow-up observations immediately, i.e., long before the lens system and the source separate due to their relative proper motion. The system is well characterized despite the low cadence $\Gamma=0.15$--$0.20\,{\rm hr^{-1}}$ of observations and short viewing windows near the end of the bulge season. This suggests that optical microlensing planet searches can be extended to the Galactic plane at relatively modest cost.Comment: 35 pages, 3 Tables, 8 figure