Manifold Learning Approach for Chaos in the Dripping Faucet

Dripping water from a faucet is a typical example exhibiting rich nonlinear phenomena. For such a system, the time stamps at which water drops separate from the faucet can be directly observed in real experiments, and the time series of intervals \tau_n between drop separations becomes a subject of analysis. Even if the mass m_n of a drop at the onset of the n-th separation, which cannot be observed directly, exhibits perfectly deterministic dynamics, it sometimes fails to obtain important information from time series of \tau_n. This is because the return plot \tau_n-1 vs. \tau_n may become a multi-valued function, i.e., not a deterministic dynamical system. In this paper, we propose a method to construct a nonlinear coordinate which provides a "surrogate" of the internal state m_n from the time series of \tau_n. Here, a key of the proposed approach is to use ISOMAP, which is a well-known method of manifold learning. We first apply it to the time series of $\tau_n$ generated from the numerical simulation of a phenomenological mass-spring model for the dripping faucet system. It is shown that a clear one-dimensional map is obtained by the proposed approach, whose characteristic quantities such as the Lyapunov exponent, the topological entropy, and the time correlation function coincide with the original dripping faucet system. Furthermore, we also analyze data obtained from real dripping faucet experiments which also provides promising results.Comment: 9 pages, 10 figure

Japan: The way ahead

The exclusion of women from organizing bodies is a key challenge facing women in Japan’s coastal fisheries. In Japan, the Fishery Cooperative Associations (FCAs) are key entities in the effort to protect the environment in coastal fisheries. They manage traditional fishing rights with legal support from the government, and are embedded into a multi-layer management system – including Total Allowable Catch controls for some species, effort control by Total Allowable Effort, prefectural government licensing systems, and traditional rights based management. Women in Japanese coastal communities have been organized and connected to FCAs for many years

Photometric Studies of a WZ Sge-Type Dwarf Nova Candidate, ASAS160048-4846.2

We report on our time-resolved CCD photometry during the 2005 June superoutburst of a WZ Sge-type dwarf nova candidate, ASAS 160048-4846.2. The ordinary superhumps underwent a complex evolution during the superoutburst. The superhump amplitude experienced a regrowth, and had two peaks. The superhump period decreased when the superhump amplitude reached to the first maximum, successively gradually increased until the second maximum of the amplitude, and finally decreased again. Investigating other SU UMa-type dwarf novae which show an increase of the superhump period, we found the same trend of the superhump evolution in superoutbursts of them. We speculate that the superhump regrowth in the amplitude has a close relation to the increase of the superhump period, and all of SU UMa-type dwarf novae with a superhump regrowth follow the same evolution of the ordinary superhumps as that of ASAS 160048-4846.2.Comment: 7 pages, 4 figure

The Microstructure of Japanfs Interbank Money Market: Simulating Contagion of Intraday Flow of Funds Using BOJ-NET Payment Data

Under a real-time gross settlement (RTGS) system, there is an incentive for system participants to delay making their outgoing payments to facilitate their funding, and this creates the risk of settlement delays spreading throughout the entire system. Intraday credit facility and market practices have been established to avoid the risk and led to settlement concentration in the morning, as well as concentrations at the specific times due to other deferred net settlement (DNS) systems. The heterogeneity of intraday progress of settlements causes intraday fluctuation in interest rates. In this paper, we analyze and run simulations on the payment network to understand the intraday flow of funds within Japanfs interbank money market, especially recycling of the "receipt-driven payments." We find that (1) the shape of the payment network changes with the time of day, and payment recycling becomes more likely when the density of the network is high; (2) patterns of intraday payment flow differ across the three RTGS systems of the United States, the United Kingdom, and Japan, reflecting differences in each countryfs system for, and underlying approach to, settlement and funding; and (3) participants comprising the hub of the payment network function as absorbers of contagion under a condition sufficiently stressful to cause a cascade of settlement delays.Real-time gross settlement; Payment recycling; BOJ-NET

The Transaction Network in Japanfs Interbank Money Markets

Interbank payment and settlement flows have changed substantially in the last decade. This paper applies social network analysis to settlement data from the Bank of Japan Financial Network System (BOJ-NET) to examine the structure of transactions in the interbank money market. We find that interbank payment flows have changed from a star-shaped network with money brokers mediating at the hub to a decentralized network with numerous other channels. We note that this decentralized network includes a core network composed of several financial subsectors, in which these core nodes serve as hubs for nodes in the peripheral sub-networks. This structure connects all nodes in the network within two to three steps of links. The network has a variegated structure, with some clusters of institutions on the periphery, and some institutions having strong links with the core and others having weak links. The structure of the network is a critical determinant of systemic risk, because the mechanism in which liquidity shocks are propagated to the entire interbank market, or likewise absorbed in the process of propagation, depends greatly on network topology. Shock simulation examines the propagation process using the settlement data.Interbank market; Real-time gross settlement; Network; Small world; Core and periphery; Systemic risk