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In this paper, we analyze the sudden change from chaos to oscillation death generated by the Bonhoeffer-van der Pol (BVP) oscillator under weak periodic perturbation. The parameter values of the BVP oscillator are chosen such that a stable focus and a stable relaxation oscillation coexist if no perturbation is applied. In such a system, complicated bifurcation structure is expected to emerge when weak periodic perturbation is applied because the stable focus and the stable relaxation oscillation coexist in close proximity in the phase plane. We draw a bifurcation diagram of the fundamental harmonic entrainment. The bifurcation structure is complex because there coexist two bifurcation sets. One is the bifurcation set generated in the vicinity of the stable focus, and the other is that generated in the vicinity of the stable relaxation oscillation. By analyzing the bifurcation diagram in detail, we can explain the sudden change from chaos with complicated waveforms to oscillation death. We make it clear that this phenomenon is caused by a saddle-node bifurcation.
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http://dx.doi.org/10.1103/PhysRevE.84.056209 | DOI Listing |
J Vet Intern Med
September 2025
Department of Population Medicine, Ontario Veterinary College, University of Guelph, Ontario, Canada.
Background: Sudden cardiac death is common in racehorses. Factors associated with the QT interval that could predispose to fatal cardiac arrhythmias are unknown. Cardiac restitution, expressed as a ratio of QT/TQ, has been used in humans to assess arrhythmia risk but has not been described in horses during maximal intensity exercise.
View Article and Find Full Text PDFNat Commun
September 2025
Plant Ecology, University of Bayreuth, Bayreuth, Germany.
The unique biodiversity and vast carbon stocks of the Amazon rainforests are essential to the Earth System but are threatened by future water balance changes. Empirical evidence suggests that species and trait diversity may mediate forest drought responses, yet little evidence exists for tropical forest responses. In this simulation study, we identify key axes of trait variation and quantify the extent to which functional trait diversity increases tropical forests' drought resistance.
View Article and Find Full Text PDFUltrasonics
September 2025
Faculty of Land Resource Engineering, Kunming University of Science and Technology, Yunnan 650093, China; Key Laboratory of Geohazard Forecast and Geoecological Restoration in Plateau Mountainous Area, Ministry of Natural Resources of the People's Republic of China, Yunnan Province, Kunming, Yunnan
Identifying and predicting the catastrophic failure of brittle rock remains a challenging task, yet it is crucial for developing early warning systems and preventing dynamic rock hazards. In this study, we employed the propagative parameters of ultrasonic waves and information from acoustic emission (AE) events to characterize the brittle failure of a flawed sandstone sample under uniaxial compression. A sliding event window method was developed to obtain the temporal b-value, effectively revealing microcrack growth based on the frequency-magnitude distribution of AE events.
View Article and Find Full Text PDFSurg Case Rep
September 2025
Department of Hepato-Biliary-Pancreatic Surgery and Transplantation, Kanazawa University, Kanazawa, Ishikawa, Japan.
Introduction: Liver transplantation for polycystic liver disease (PLD) poses significant intraoperative risks due to the presence of a massively enlarged liver. We report a rare case of intraoperative pneumothorax and pneumatocele formation during total hepatectomy, which was successfully managed with a non-operative approach.
Case Presentation: A female patient in her 40s with a history of autosomal dominant polycystic kidney disease presented with progressive liver cyst enlargement (Gigot type III, Qian classification Grade 4), which led to decreased activities of daily living and intracystic hemorrhage.
IEEE Trans Biomed Eng
September 2025
Objetive: This study aims to evaluate the QT adaptation time following gradual heart rate changes estimated from exercise stress test (EST) ECGs as a marker of sudden cardiac death (SCD) risk. The predicted risk value for any cardiovascular death (CVD) is also evaluated.
Methods: Three ECG-derived markers related to QT-RR adaptation time were estimated during the exercise phase of EST, $\check{\tau }_{e}$, during the recovery phase, $\check{\tau }_{r}$, and as the difference between them, $\Delta _{\check{\tau }}$.