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301.
This Letter investigates the period-doubling cascades of canards, generated in the extended Bonhoeffer-van der Pol oscillator. Canards appear by Andronov-Hopf bifurcations (AHBs) and it is confirmed that these AHBs are always supercritical in our system. The cascades of period-doubling bifurcation are followed by mixed-mode oscillations. The detailed two-parameter bifurcation diagrams are derived, and it is clarified that the period-doubling bifurcations arise from a narrow parameter value range at which the original canard in the non-extended equation is observed. 相似文献
302.
Naohiko OHKOUCHI Junichiro KURODA Asahiko TAIRA 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2015,91(7):273-291
Black shale is dark-colored, organic-rich sediment, and there have been many episodes of black shale deposition over the history of the Earth. Black shales are source rocks for petroleum and natural gas, and thus are both geologically and economically important. Here, we review our recent progress in understanding of the surface ocean ecosystem during periods of carbonaceous sediment deposition, and the factors triggering black shale deposition. The stable nitrogen isotopic composition of geoporphyrins (geological derivatives of chlorophylls) strongly suggests that N2-fixation was a major process for nourishing the photoautotrophs. A symbiotic association between diatoms and cyanobacteria may have been a major primary producer during episodes of black shale deposition. The timing of black shale formation in the Cretaceous is strongly correlated with the emplacement of large igneous provinces such as the Ontong Java Plateau, suggesting that black shale deposition was ultimately induced by massive volcanic events. However, the process that connects these events remains to be solved. 相似文献
303.
304.
A. Koizumi T. Nagao N. Hiraoka T. Arima Y. Murakami 《Journal of Physics and Chemistry of Solids》2005,66(12):2183-2191
Magnetic Compton profiles (MCP) have been measured in the [100], [110] and [001] directions on the single crystals of La2−2xSr1+2xMn2O7 (x=0.30, 0.35 and 0.42) at 10 K. The occupation numbers in t2g and two eg type orbitals (x2−y2 and 3z2−r2) of Mn-3d state are evaluated from the line-shape analysis of MCP's in the [001] direction by using theoretical profiles derived from the ab initio calculations for (MnO6)8−cluster. It has been found that the eg state is dominated by the x2−y2 type orbital at every hole concentration, x, and the 3z2−r2 type orbital population decreases with increasing x. From the result, the connections of eg orbital state with the electron correlation effect, exchange interactions, lattice distortion and electronic inhomogeneity are discussed. 相似文献
305.
Takeru Yamazaki Kohe Arima Riku Kubota Kiyoshi Sato Hiroyoshi Kawakami 《Particle & Particle Systems Characterization》2021,38(8):2100003
Epithelial-to-mesenchymal transition (EMT) of carcinoma cells is a promising target for cancer therapy since it is closely related to tumor metastasis and therapeutic resistance. The process of EMT is strongly associated with epigenetic alterations in cancer cells. In addition, recent accumulating evidence suggests that EMT also has a significant influence on inducing cancer stem cells (CSCs). In this study, novel polymer core–lipid shell nanoparticles (PLNPs) are prepared to suppress cancer EMT by the combined effects of the antioxidant activity of core-encapsulated Mn imidazolium porphyrin (MnImP) and the epigenetic control by histone acetyltransferase-encoding plasmid DNA (pHAT) hybridized onto the shell surface. PLNPs show the ability to control the expression of EMT-related markers, resulting in the suppression of EMT in lung epithelial cancer cells (paraquat-treated A549 cells). Furthermore, PLNPs suppress the levels of intracellular mitochondrial ROS and the transformation to CSCs. The results of this study may provide a novel therapeutic strategy against tumor metastasis and treatment resistance. 相似文献
306.
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308.
Takashi Arima Maria Cristina Carrisi Sebastiano Pennisi Tommaso Ruggeri 《Entropy (Basel, Switzerland)》2022,24(1)
A relativistic version of the rational extended thermodynamics of polyatomic gases based on a new hierarchy of moments that takes into account the total energy composed by the rest energy and the energy of the molecular internal mode is proposed. The moment equations associated with the Boltzmann–Chernikov equation are derived, and the system for the first 15 equations is closed by the procedure of the maximum entropy principle and by using an appropriate BGK model for the collisional term. The entropy principle with a convex entropy density is proved in a neighborhood of equilibrium state, and, as a consequence, the system is symmetric hyperbolic and the Cauchy problem is well-posed. The ultra-relativistic and classical limits are also studied. The theories with 14 and 6 moments are deduced as principal subsystems. Particularly interesting is the subsystem with 6 fields in which the dissipation is only due to the dynamical pressure. This simplified model can be very useful when bulk viscosity is dominant and might be important in cosmological problems. Using the Maxwellian iteration, we obtain the parabolic limit, and the heat conductivity, shear viscosity, and bulk viscosity are deduced and plotted. 相似文献
309.
310.
The quasiparticle representation of the phonon darnping model (PDM) is developed to include the superfluid pairing correlations
microscopically. The formalism is applied to calculate the photoabsorption and the electromagnetic (EM) differential cross
sections of E1 excitations in neutron-rich oxygen and calcium isotopes. The calculated photoabsorption cross sections agree
reasonably well with the available data for 16,18O and 40,48Ca. The results of calculations show that the change of the fraction of the E1 integrated strength in the region of pygmy
dipole resonance (PDR) as a function of mass number A with increasing neutron number N is in agreement with the recent experimental data, and does not follow the prediction by the simple cluster model. The EM
differential cross sections obtained within PDM in this work show prominent PDR peaks below 15 MeV for 20,22O in agreement with the recent experimental observation. It is also shown that, using low-energy RI beams at around 50–60
MeV/nucleon, one can observe clean and even enhanced PDR peaks without the admixture with the GDR in the EM differential cross
sections of neutron-rich nuclei. 相似文献