1,370 research outputs found
Quasi-Eigenstate Evolution in Open Chaotic Billiards
We experimentally studied evolution of quasi-eigenmodes as classical dynamics
undergoing a transition from being regular to chaotic in open quantum
billiards. In a deformation-variable microcavity we traced all high-Q cavity
modes in a wide range of frequency as the cavity deformation increased. By
employing an internal parameter we were able to obtain a mode-dynamics diagram
at a given deformation, showing avoided crossings between different mode
groups, and could directly observe the coupling strengths induced by ray chaos
among encountering modes. We also show that the observed mode-dynamics diagrams
reflect the underlying classical ray dynamics in the phase space.Comment: 4 pages, 4 figure
Development of deformation-tunable quadrupolar microcavity
We have developed a technique for realizing a two-dimensional quadrupolar
microcavity with its deformation variable from 0% to 20% continuously. We
employed a microjet ejected from a noncircular orifice in order to generate a
stationary column with modulated quadrupolar deformation in its cross section.
Wavelength red shifts of low-order cavity modes due to shape deformation were
measured and were found to be in good agreement with the wave calculation for
the same deformation, indicating the observed deformation is quadrupolar in
nature.Comment: 7 pages, 6 figures, intended for Rev. Sci. Instu
Chaos-assisted nonresonant optical pumping of quadrupole-deformed microlasers
Efficient nonresonant optical pumping of a high-Q scar mode in a
two-dimensional quadrupole-deformed microlaser has been demonstrated based on
ray and wave chaos. Three-fold enhancement in the lasing power was achieved at
a properly chosen pumping angle. The experimental result is consistent with ray
tracing and wave overlap integral calculations.Comment: 3 pages, 5 figure
The voltage-gated potassium channel Shaker promotes sleep via thermosensitive GABA transmission
Genes and neural circuits coordinately regulate animal sleep. However, it remains elusive how these endogenous factors shape sleep upon environmental changes. Here, we demonstrate that Shaker (Sh)-expressing GABAergic neurons projecting onto dorsal fan-shaped body (dFSB) regulate temperature-adaptive sleep behaviors in Drosophila. Loss of Sh function suppressed sleep at low temperature whereas light and high temperature cooperatively gated Sh effects on sleep. Sh depletion in GABAergic neurons partially phenocopied Sh mutants. Furthermore, the ionotropic GABA receptor, Resistant to dieldrin (Rdl), in dFSB neurons acted downstream of Sh and antagonized its sleep-promoting effects. In fact, Rdl inhibited the intracellular cAMP signaling of constitutively active dopaminergic synapses onto dFSB at low temperature. High temperature silenced GABAergic synapses onto dFSB, thereby potentiating the wake-promoting dopamine transmission. We propose that temperature-dependent switching between these two synaptic transmission modalities may adaptively tune the neural property of dFSB neurons to temperature shifts and reorganize sleep architecture for animal fitness.
Ji-hyung Kim and Yoonhee Ki et al. show that low temperatures suppress sleep in Drosophila by increasing GABA transmission in Shaker-expressing GABAergic neurons projecting onto the dorsal fan-shaped body, while high temperatures potentiate dopamine-induced arousal by reducing GABA transmission. This study highlights a role for Shaker in sleep modulation via a temperature-dependent switch in GABA signaling
A Study on Group Key Agreement in Sensor Network Environments Using Two-Dimensional Arrays
These days, with the emergence of the concept of ubiquitous computing, sensor networks that collect, analyze and process all the information through the sensors have become of huge interest. However, sensor network technology fundamentally has wireless communication infrastructure as its foundation and thus has security weakness and limitations such as low computing capacity, power supply limitations and price. In this paper, and considering the characteristics of the sensor network environment, we propose a group key agreement method using a keyset pre-distribution of two-dimension arrays that should minimize the exposure of key and personal information. The key collision problems are resolved by utilizing a polygonal shapeās center of gravity. The method shows that calculating a polygonal shapeās center of gravity only requires a very small amount of calculations from the users. The simple calculation not only increases the group key generation efficiency, but also enhances the sense of security by protecting information between nodes
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