467 research outputs found
Figure 1 from: Sabino Kikuchi IAB, Keβler PJA, Schuiteman A, Murata J, Ohi-Toma T, Yukawa T, Tsukaya H (2020) Molecular phylogenetic study of the tribe Tropidieae (Orchidaceae, Epidendroideae) with taxonomic and evolutionary implications. PhytoKeys 140: 11-22. https://doi.org/10.3897/phytokeys.140.46842
No full textFigure 1 Tropidia connata J.J.Wood & A.L.Lamb and Kalimantanorchis nagamasui Tsukaya, M.Nakaj. & H.Okada. A Gross morphology of T. connata individual (specimen number 1040, collected in January, 2011 by H. Tsukaya, H. Okada and A. Soejima). B Gross morphology of fruiting K. nagamasui individual (specimen number HT1035, collected in January, 2011 by H. Tsukaya, H. Okada and A. Soejima). Scale in cm
Manifold learning approach for chaos in the dripping faucet
No full textDripping 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 τn between drop separations becomes a subject of analysis. Even if the mass mn of a drop at the onset of the nth separation, which is difficult to observe experimentally, exhibits perfectly deterministic dynamics, it may be difficult to obtain the same information about the underlying dynamics from the time series τn. This is because the return plot τn−1 vs. τn may become a multivalued relation (i.e., it doesn't represent a function describing deterministic dynamics). In this paper, we propose a method to construct a nonlinear coordinate which provides a “surrogate” of the internal state mn from the time series of τn. 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 τn 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 provide promising results
The Transaction Network in Japanfs Interbank Money Markets
No full textInterbank 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
Radiographic Absorptiometry for bone mineral measurement of the phalanges: precision and accuracy study.
No full textOptimal Strategies for Patrolling Fences
No full textA classical multi-agent fence patrolling problem asks: What is the maximum length L of a line fence that k agents with maximum speeds v_1,..., v_k can patrol if each point on the line needs to be visited at least once every unit of time. It is easy to see that L = alpha sum_{i=1}^k v_i for some efficiency alpha in [1/2,1). After a series of works [Czyzowicz et al., 2011; Dumitrescu et al., 2014; Kawamura and Kobayashi, 2015; Kawamura and Soejima, 2015] giving better and better efficiencies, it was conjectured by Kawamura and Soejima [Kawamura and Soejima, 2015] that the best possible efficiency approaches 2/3. No upper bounds on the efficiency below 1 were known.
We prove the first such upper bounds and tightly bound the optimal efficiency in terms of the minimum speed ratio s = {v_{max}}/{v_{min}} and the number of agents k. Our bounds of alpha = Omega(epsilon^{-2}) agents with a speed ratio of s >= Omega(epsilon^{-1}) are necessary. Guided by our upper bounds, we construct a scheme whose efficiency approaches 1, disproving the conjecture stated above. Our scheme asymptotically matches our upper bounds in terms of the maximal speed difference and the number of agents used.
A variation of the fence patrolling problem considers a circular fence instead and asks for its circumference to be maximized. We consider the unidirectional case of this variation, where all agents are only allowed to move in one direction, say clockwise. At first, a strategy yielding L = max_{r in [k]} r * v_r where v_1 >= v_2 >= ... >= v_k was conjectured to be optimal by Czyzowicz et al. [Czyzowicz et al., 2011] This was proven not to be the case by giving constructions for only specific numbers of agents with marginal improvements of L. We give a general construction that yields L = 1/{33 log_e log_2(k)} sum_{i=1}^k v_i for any set of agents, which in particular for the case 1, 1/2, ..., 1/k diverges as k - > infty, thus resolving a conjecture by Kawamura and Soejima [Kawamura and Soejima, 2015] affirmatively
A Consequence of Direct Reference Theory ― concerning Kripke's Puzzle about belief ―
No full textIn this paper the author presents a consequence of direct reference theory through a careful examination of Kripke's Puzzle about belief. Kripke presented, in 'A Puzzle about Belief', a puzzle about belief which has no relation with a substitution of proper names. In doing that, he rejected a superiority of Fregean semantics, and suggested us a reconsideration of belief attribution. But the author dares to accept usual attribution of belief for a practical reason, and on this assumption tries to resolve the puzzle. A consequence is the following. If we accept usual attribution of belief, accept direct reference theory of proper names, and want to resolve the puzzle, then we must also accept a multiplicity of worlds, that is, a multiplicity of models of our language. Additionally, the author points out that Kripke's way of thinking that concludes innocence of a substitution of proper names is incorrect
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