Forecasting Global Temperature Variations by Neural Networks

Global temperature variations between 1861 and 1984 are forecast usingsregularization networks, multilayer perceptrons and linearsautoregression. The regularization network, optimized by stochasticsgradient descent associated with colored noise, gives the bestsforecasts. For all the models, prediction errors noticeably increasesafter 1965. These results are consistent with the hypothesis that thesclimate dynamics is characterized by low-dimensional chaos and thatsthe it may have changed at some point after 1965, which is alsosconsistent with the recent idea of climate change.

日本語母音のサロゲート解析

Nonlinear deterministic dynamical structure of the normal phonation of Japanese vowels is studied by the method of surrogate. The surrogate analysis exploits Wayland translation error and nonlinear deterministic predictability as the discriminating statistics. The results imply that the vowel signals have strong nonlinear dynamical characteristics that can not be detected by conventional linear dynamical systems analyses of speech.特集 : 「産業におけるソフトコンピューティングに関する国際会議\u2799」発表論文選

Augmentation of Reverse Transcription by Integrase through an Interaction with Host Factor, SIP1/Gemin2 Is Critical for HIV-1 Infection

There has been accumulating evidence for the involvement of retroviral integrase (IN) in the reverse transcription of viral RNA. We previously identified a host factor, survival motor neuron-interacting protein 1 (SIP1/Gemin2) that binds to human immunodeficiency virus type 1 (HIV-1) IN and supports HIV-1 infection apparently at reverse transcription step. Here, we demonstrated that HIV-1 IN together with SIP1 augments reverse transcriptase (RT) activity by enhancing the assembly of RT on viral RNA in vitro. Synthetic peptides corresponding to the binding motifs within IN that inhibited the IN-SIP1 interaction abrogated reverse transcription in vitro and in vivo. Furthermore, knockdown of SIP1 reduced intracellular stability and multimer formation of IN through proteasome-mediated degradation machinery. Taken together, SIP1 appears to stabilize functional multimer forms of IN, thereby promoting the assembly of IN and RT on viral RNA to allow efficient reverse transcription, which is a prerequisite for efficient HIV-1 infection

Forecasting Global Temperature Variations by Neural Networks

Global temperature variations between 1861 and 1984 are forecast using regularization network, multilayer perceptrons, linear autoregression, and a local model known as the simplex projection method. The simplex projection method is applied to characterize complexities in the time series in terms of the dependence of prediction accuracy on embedding dimension and on prediction-time interval. Nonlinear forecasts from the library patterns between 1861 and 1909 reveal that prediction accuracies are optimal at the embedding dimension of 4 and deteriorate with prediction-time interval. Regularization network, backpropagation, and linear autoregression are applied to make short term predictions of the meteorological time series from 1910 to 1984. The regularization network, optimized by stochastic gradient descent associated with colored noise, gives the best forecasts. For all the models, prediction errors noticeably increase after 1965. These results are consistent with the hypothesis that..

<Contributed Talk 16>Augmented Lorenz Equations as Physical Model for Chaotic Gas Turbine

[Date] November 28 (Mon) - December 2 (Fri), 2011: [Place] Kyoto University Clock Tower Centennial Hall, Kyoto, JAPA

Chaotic electrical activity of living beta-cells in the mouse pancreatic islet

To test for chaotic dynamics of the insulin producing beta-cell and explore its biological role, we observed the action potentials with the perforated patch clamp technique, for isolated cells as well as for intact cells of the mouse pancreatic islet. The time series obtained were analyzed using nonlinear diagnostic algorithms associated with the surrogate method. The isolated cells exhibited short-term predictability and visible determinism, in the steady state response to 10 mM glucose, while the intact cells did not. In the latter case, determinism became visible after the application of a gap junction inhibitor. This tendency was enhanced by the stimulation with tolbutamide. Our observations suggest that, thanks to the integration of individual chaotic dynamics via gap junction coupling, the beta-cells will lose memory of fluctuations occurring at any instant in their electrical activity more rapidly with time. This is likely to contribute to the functional stability of the islet against uncertain perturbations. (c) 2006 Elsevier B.V All rights reserved