On the Analysis of the Bifurcation Sets of Equilibrium Points in Parameter Space

WeB6 Regular Session: Nonlinear System Theory II, Paper WeB6.3Abstract: This paper addresses the problems of characterizing and estimating the bifurcation sets of equilibrium points in multi-parameter space of a class of nonlinear dynamical systems. Specifically, we investigate the sets of parameters that lead to saddle-node bifurcations and Hopf bifurcations at an equilibrium point of interest. First, a characterization of these sets is provided in terms of the zeros of some functions. Second, this characterization is exploited to estimate such sets through convex programming for the case of polynomial dynamical systems. In particular, two conditions are proposed for establishing whether a sublevel set of a given polynomial does not contain parameters that lead to bifurcations. By using these conditions, the largest of such sublevel sets can be estimated by solving an eigenvalue problem. Some numerical examples illustrate the proposed results.published_or_final_versio

Chaotic Phase Synchronization in Bursting-neuron Models Driven by a Weak Periodic Force

We investigate the entrainment of a neuron model exhibiting a chaotic spiking-bursting behavior in response to a weak periodic force. This model exhibits two types of oscillations with different characteristic time scales, namely, long and short time scales. Several types of phase synchronization are observed, such as 1 : 1 phase locking between a single spike and one period of the force and 1 : l phase locking between the period of slow oscillation underlying bursts and l periods of the force. Moreover, spiking-bursting oscillations with chaotic firing patterns can be synchronized with the periodic force. Such a type of phase synchronization is detected from the position of a set of points on a unit circle, which is determined by the phase of the periodic force at each spiking time. We show that this detection method is effective for a system with multiple time scales. Owing to the existence of both the short and the long time scales, two characteristic phenomena are found around the transition point to chaotic phase synchronization. One phenomenon shows that the average time interval between successive phase slips exhibits a power-law scaling against the driving force strength and that the scaling exponent has an unsmooth dependence on the changes in the driving force strength. The other phenomenon shows that Kuramoto's order parameter before the transition exhibits stepwise behavior as a function of the driving force strength, contrary to the smooth transition in a model with a single time scale

Proper-time Resolution Function for Measurement of Time Evolution of B Mesons at the KEK B-Factory

The proper-time resolution function for the measurement of the time evolution of B mesons with the Belle detector at KEKB is studied in detail. The obtained resolution function is applied to the measurement of B meson lifetimes, the B0-B0bar oscillation frequency and time-dependent CP asymmetries.Comment: 25 pages, 18 figures, to be published in NIM A, replaced with revised versio

Better, faster, more versatile NMR diffusion measurements

The range of applications and versatility of NMR diffusion measurements [1,2] increase with the speed, accuracy, and the practical lower concentration limits that can be used. For example, faster measurements expand the horizons of diffusion measurements to study reaction kinetics [3,4], as well as simply increasing throughput. Our group has been investigating various approaches for improving the performance of NMR diffusion measurements. Here we present some of our recent advances

Habitat evaluation for the endangered fish species Lefua echigonia in the Yagawa River, Japan

This is an Accepted Manuscript of an article published by Taylor & Francis in Journal of Ecohydraulics on 2019, available online: http://www.tandfonline.com/10.1080/24705357.2019.1614886[EN] Spring-fed streams in Tokyo are important habitats for various aquatic species, whereas urbanization as well as introduction of invasive species is threatening the sustainability of such aquatic ecosystems. This study applies the System for Environmental Flow Analysis (SEFA) in a small urban river in Tokyo to assess the dynamics of the suitable habitats for the endangered freshwater fish Lefua echigonia (Jordan and Richardson 1907). A set of Habitat Suitability Curves (HSCs) for water depth, velocity and substrate was developed to evaluate the suitable habitats. The habitat assessment indicated that the Area Weighted Suitability (AWS) reached the maximum at 0.02 m3/s, which is close to the base flow of the target river; a gradual decrease in AWS was observed for higher flows. The temporal distribution of AWS, during forty-one consecutive months, showed that, on average, the best habitat conditions for adult L. echigonia occur during the period between January and July, whereas the worst situation occurs during the period between August and December. This work presents information and tools for instream habitat analysis that should help managers to conserve this aquatic species and prioritize actions to further rehabilitate urban rivers, using L. echigonia as a case study.We thank Dr. Masaomi Kimura, Masato Kondo, Taichi Kasahara, and Akihiro Tanaka for their support in the field survey. This study was made in part with the support of the JSPS Grants-in-Aid for Scientific Research (Grant number: 17H03886 and 17H04631) and the PROMOE grant for Marina de Miguel Gallo, funded by the Universitat Politecnica de Valencia, between April and August 2018.De-Miguel-Gallo, M.; Martinez-Capel, F.; Muñoz Mas, R.; Aihara, S.; Matsuzawa, Y.; Fukuda, S. (2019). Habitat evaluation for the endangered fish species Lefua echigonia in the Yagawa River, Japan. Journal of Ecohydraulics. 4(2):147-157. https://doi.org/10.1080/24705357.2019.1614886S14715742Bovee KD, Lamb BL, Bartholow JM, Stalnaker CB, Taylor J, Henriksen J. 1998. Stream habitat analysis using the instream flow incremental methodology. U.S. Geological Survey, Biological Resources Division Information and Technology Report USGS/BRD-1998-0004. Fort Collins: U.S. Geological Survey.Bovee KD. 1986. Development and evaluation of habitat suitability criteria for use in the instream flow incremental methodology. Washington, D.C.: U.S. Fish and Wildlife Service Biological Report, 86/7.Lambert TR. 1994. Evaluation of factors causing variability in habitat suitability criteria for Sierra Nevada trout. Environment, Health & Safety. Report 009.4-94.5. San Francisco: Pacific Gas and Electric Company.Martínez-Capel F. 2000. Preferencias de microhábitat de Barbus bocagei, Chondrostoma polylepis y Leuciscus pyrenaicus en la cuenca del río Tajo [PhD Dissertation]. Madrid: Universidad Politécnica de Madrid. (In Spanish)Matsuzawa Y, Aoki K, Fukuda S. 2017a. Critical swimming speed of Lefua echigonia in a laboratory open channel. Proceedings of the Annual Meeting of the Japanese Society of Irrigation Drainage and Reclamation Engineering (JSIDRE). ID: 4-30. Tokyo: Japanese Society of Irrigation Drainage and Reclamation Engineering.Matsuzawa Y, Ohira M, Fukuda S. 2017b. Microhabitat Modelling for an Endangered Freshwater Fish, Lefua Echigonia, in a Spring-Fed Urban Stream. E-Proceedings of the 37th IAHR World Congress. Kuala Lumpur: International Association for Hydro-environment Research and Engineering (IAHR).Poff NL. 2018. Beyond the natural flow regime? Broadening the hydro-ecological foundation to meet environmental flows challenges in a non-stationary world. Freshwater Biol. 63(8):1011–1021

A Revised Effective Temperature Scale for the Kepler Input Catalog

We present a catalog of revised effective temperatures for stars observed in long-cadence mode in the Kepler Input Catalog (KIC). We use SDSS griz filters tied to the fundamental temperature scale. Polynomials for griz color-temperature relations are presented, along with correction terms for surface gravity effects, metallicity, and statistical corrections for binary companions or blending. We compare our temperature scale to the published infrared flux method (IRFM) scale for VJKs in both open clusters and the Kepler fields. We find good agreement overall, with some deviations between (J - Ks)-based temperatures from the IRFM and both SDSS filter and other diagnostic IRFM color-temperature relationships above 6000 K. For field dwarfs we find a mean shift towards hotter temperatures relative to the KIC, of order 215 K, in the regime where the IRFM scale is well-defined (4000 K to 6500 K). This change is of comparable magnitude in both color systems and in spectroscopy for stars with Teff below 6000 K. Systematic differences between temperature estimators appear for hotter stars, and we define corrections to put the SDSS temperatures on the IRFM scale for them. When the theoretical dependence on gravity is accounted for we find a similar temperature scale offset between the fundamental and KIC scales for giants. We demonstrate that statistical corrections to color-based temperatures from binaries are significant. Typical errors, mostly from uncertainties in extinction, are of order 100 K. Implications for other applications of the KIC are discussed.Comment: Corrected for sign flip errors in the gravity corrections. Erratum to this paper is attached in Appendix. Full version of revised Table 7 can be found at http://home.ewha.ac.kr/~deokkeun/kic/sdssteff_v2.dat.g