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This paper focuses on the vibration periodic property of Duffing oscillator with generalized initial conditions. Firstly, the undamped case is solved by Ji-Huan He’s frequency formulation; Secondly, the formulation is extended to the damped case. Numerical verification shows that the frequency formulation is mathematically simple and physically insightful and practically applicable. This paper paves a novel way for engineers to use the formulation to study nonlinear vibration system with ease and reliability. [ABSTRACT FROM AUTHOR]

The basic dynamic properties of a four dimensional hyperchaotic system are investigated in this paper. More precisely, the stability of equilibrium point of hyperchaotic system is studied by means of nonlinear dynamics theory. We analyses the existence and stability of Hopf bifurcation, and the formulas for determining the direction of Hopf bifurcation and the stability of bifurcating periodic solutions are derived. In addition, a sliding mode controller is designed and controlled the hyperchaotic system to any fixed point to eliminate the chaotic vibration by means of sliding mode method. Finally, the numerical simulations were presented to confirm the effectiveness of the controller. [ABSTRACT FROM AUTHOR]

The basic dynamic properties of a four dimensional hyperchaotic system are investigated in this paper. More precisely, the stability of equilibrium point of hyperchaotic system is studied by means of nonlinear dynamics theory. We analyses the existence and stability of Hopf bifurcation, and the formulas for determining the direction of Hopf bifurcation and the stability of bifurcating periodic solutions are derived. In addition, a sliding mode controller is designed and controlled the hyperchaotic system to any fixed point to eliminate the chaotic vibration by means of sliding mode method. Finally, the numerical simulations were presented to confirm the effectiveness of the controller. [ABSTRACT FROM AUTHOR]

The large area LPCVD Si3N4 membrane mounted with NiCr/Ni thermocouples is the key structure which is used not only in the study on the micrometer scale thermal and material science research, but also in the applications such as the mass flow sensors of gas and liquid. Normaly the successful fabrication of this device is difficult. By a steped-upward chemical etch method that we have developed, we have fabricated a suspended large area (3mm × 6mm) Si3N4 membrane which is mounted with NiCr/Ni thermocouples. The thickness of membrane is from l00nm to l000nm. [ABSTRACT FROM AUTHOR]

A complex mode-locking (entrainment) topology underlying the continuous stirred tank reactor reaction model subjected to impulsive perturbations is identified. Employing high-resolution stability diagrams, we exhibit the global structure of mode-locking oscillations and describe how they are interconnected and how their complexity unfolds with control parameters varying. The scenarios shown in the bi-parametric planes revealed that the skeleton of Arnold's tongues is organized according to the symmetric Stern--Brocot sum tree. Moreover, the mode-locking organization is controlled by an invariant torus (a pair of frequencies) initiated from Hopf bifurcations. Interestingly, the mode-locking order is unfolded in an elusive way, that is, in perfect agreement with the reciprocal of the Stern--Brocot sum tree. The findings reported here contribute to providing a description and classification of mode-locking oscillations for the impulsive system. [ABSTRACT FROM AUTHOR]

The dynamical behaviors of a SEIR epidemic model are investigated in this paper. More precisely, we presented a new discrete-time SEIR epidemic model by using the Forward-Euler difference method. And the existence, stability and direction of Hopf bifurcation of the SEIR epidemic model and its discretization model are also studied. In addition, the numerical simulations were presented to illustrate the theoretical analysis. Finally, some comparisons of bifurcation between the continuous-time epidemic system and its discrete-time system are given. [ABSTRACT FROM AUTHOR]

Human monocyte–derived dendritic cells (DCs), stimulated with granulocyte-macrophage colony-stimulating factor and interleukin-4 for 1 week, major histocompatibility complex killed human tumor cells in 24-hour cytotoxicity assays. These immature DCs were >90 CD11c, major histocompatibility complex class II, but <1 were CD83cells. Within 24 hours, these DCs ingested tumor membranes. The DC cells also lysed Jurkat lymphoma cells, but not Jurkat cells genetically knocked out of the Fas-associated death domain (FADD) or caspase-8. DC2.4, a cloned murine DC line, also displayed cytotoxicity toward U-251 cells, although these murine DCs were less potent than human DC. DC2.4 did not kill Jurkat cells, rat T9 glioma cells, or human Caco-2 colon cancer cells, suggesting that a unique receptor or ligand interaction exists between the DC and U-251 cells. This interaction was destroyed by the paraformaldehyde fixation of the tumor cells. Supernatants from the cultures of DC2.4 and tumor cells were analyzed by the Griess reaction for signs of nitric oxide (NO) production. Augmented NO production occurred in DC2.4U-251 and DC2.4Jurkat cultures but was not seen in the human DCU-251 cultures. These studies suggest that DCs possess different mechanisms of tumoricidal activity. [ABSTRACT FROM AUTHOR]

Paraptosis is the programmed cell death pathway that leads to cellular necrosis. Previously, rodent and human monocytes/ macrophages killed glioma cells bearing the membrane macrophage colony stimulating factor (mM-CSF) through paraptosis, but the molecular mechanism of this killing process was never identified. We have demonstrated that paraptosis of rat T9 glioma cells can be initiated through a large potassium channel (BK)-dependent process initiated by reactive oxygen species. Macrophage mediated cytotoxicity upon the mM-CSF expressing T9-C2 cells was not prevented by the addition of the caspase inhibitor, zVAD-fmk. By a combination of fluorescent confocal and electron microscopy, flow cytometry, electrophysiology, pharmacology, and genetic knock-down approaches, we demonstrated that these ion channels control cellular swelling and vacuolization of rat T9 glioma cells. Cell lysis is preceded by a depletion of intracellular ATP. Six-hour exposure to BK channel activation caused T9 cells to over express heat shock proteins (Hsp 60, 70, 90 and gp96). This same treatment forced HMGB1 translocation from the nuclear region to the periphery. These last molecules are ''danger signals'' that can stimulate immune responses. Similar inductions of mitochondrial swelling and increased Hsp70 and 90 expressions by BK channel activation were observed with the non-immunogenic F98 glioma cells. Rats injected with T9 cells which were killed by prolonged BK channel activation developed immunity against the T9 cells, while the injection of x-irradiated apoptotic T9 cells failed to produce the vaccinating effect. These results are the first to show that glioma cellular death induced by prolonged BK channel activation improves tumor immunogenicity; this treatment reproduces the vaccinating effects of mM-CSF transduced cells. Elucidation of strategies as described in this study may prove quite valuable in the development of clinical immunotherapy against cancer. [ABSTRACT FROM AUTHOR]

Advanced glycoxidation end products (AGEs) are implicated in delayed diabetic wound healing. To test the role of diet-derived AGE on the rate of wound healing, we placed female db/db (+/+) (n = 55, 12 weeks old) and age-matched control db/db (+/-) mice (n = 45) on two diets that differed only in AGE content (high [H-AGE] versus low [L-AGE] ratio, 5:1) for 3 months. Full-thickness skin wounds (1 cm) were examined histologically and for wound closure. Serum 24-h urine and skin samples were monitored for N(epsilon)-carboxymethyl-lysine and methylglyoxal derivatives by enzyme-linked immunosorbent assays. L-AGE-fed mice displayed more rapid wound closure at days 7 and 14 (P < 0.005) and were closed completely by day 21 compared with H-AGE nonhealed wounds. Serum AGE levels increased by 53% in H-AGE mice and decreased by 7.8% in L-AGE mice (P < 0.04) from baseline. L-AGE mice wounds exhibited lower skin AGE deposits, increased epithelialization, angiogenesis, inflammation, granulation tissue deposition, and enhanced collagen organization up to day 21, compared with H-AGE mice. Reepithelialization was the dominant mode of wound closure in H-AGE mice compared with wound contraction that prevailed in L-AGE mice. Thus, increased diet-derived AGE intake may be a significant retardant of wound closure in diabetic mice; dietary AGE restriction may improve impaired diabetic wound healing. [ABSTRACT FROM AUTHOR]