2,655 research outputs found

    Stability analysis of the five-dimensional energy demand-supply system

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    summary:In this paper, a five-dimensional energy demand-supply system has been considered. On the one hand, we analyze the stability for all of the equilibrium points of the system. For each of equilibrium point, by analyzing the characteristic equation, we show the conditions for the stability or instability using Routh-Hurwitz criterion. Then numerical simulations have been given to illustrate all of cases for the theoretical results. On the other hand, by introducing the phenomenon of time delay, we establish the five-dimensional energy demand-supply model with time delay. Then we analyze the stability of the equilibrium points for the delayed system by the stability switching theory. Especially, Hopf bifurcation has been considered by showing the explicit formulae using the central manifold theorem and Poincare normalization method. For each cases of the theorems including the Hopf bifurcation, numerical simulations have been given to illustrate the effectiveness of the main results

    Gastro-protective actions of Aloe barbadensis Miller mitigate ethanol-induced gastric injury in rats

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    Purpose: To investigate the gastroprotective effect of leaf extract of Aloe barbadensis on ethanolinduced gastric ulcer in rats.Methods: Healthy male Wistar rats (n = 30) weighing 180 - 220 g (mean weight = 200 ± 20 g) were randomly assigned to 6 groups (5 rats/group): control group, gastric ulcer group, two Aloe barbadensis extract groups (250 and 500 mg/kg), cimetidine group and indomethacin group. Gastric ulcer was induced via oral injection of absolute ethanol at a dose of 1 mL/kg after a 24-h fast. Gross evaluation, determination of gastric juice acidity and histological examination of gastric tissue were carried out.Results: Treatment of gastric ulcer rats with Aloe barbadensis extract significantly reduced ulcerated area (UA), ulcer index (UI), and acidity of gastric juice (p < 0.05). Injection of 1 % carrageenan into rat hind paw led to a time-dependent increase in paw volume which peaked 3 h after injection. However, the Aloe barbadensis extract significantly and dose-dependently reduced the volume of inflamed paw, and inhibited edema formation (p < 0.05). It also markedly reduced or completely eliminated edema and leucocyte infiltration. Moreover, treatment of gastric ulcer rats with Aloe barbadensis leaf extract led to significant and dose-dependent reduction in gastric tissue MDA level (p < 0.05). Histological examination of the gastric wall showed that control rats had severe injury in gastric mucosa,accompanied by edema and leucocytes infiltration, relative to rats pretreated with extract which showed marked gastric protection and inhibition of edema and leucocytes infiltration. Moreover, the extract treatment protected the gastric surface against ulceration as indicated by reduced lesions in the treated rat model.Conclusion: These results show that Aloe barbadensis mitigates ethanol-induced gastric injury in rats via inhibition of lipid  peroxidation and inflammation. Thus, the extract has potentials for development into a therapeutic agent for the management of  gastric ulcer. Keywords: Aloe barbadensis, Gastric ulcer, Gastric mucosa, Inflammation, Lipid peroxidatio

    The correlation between the severity of radiotherapy-induced glossitis and endothelial cell injury in local tissues in a rat model

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    Objectives: To explore the correlation between the severity of radiotherapy-induced glossitis (RTG) and endothelial cell injury in local tissues in a rat model. Study Design: The RTG animal model was designed and used by our team. The Oral mucositis index(OMI) was documented daily. Immunohistochemistry (IHC) Staining of CD34 was utilized to identify endothelial cells in the RTG tissues. Apoptosis of endothelial cells in local lesions due to RTG was detected by the TUNEL assay. The dynamic relationship between the OMI and apoptotic endothelial cells was statistically analyzed by time. Results and Conclusions: The injury and apoptosis of endothelial cells were observed 3 day post-irradiation. The vascular lumens of the post-irradiation tongue lesions were irregular; thrombosis formation in the center of the lumens, unsmooth lumen walls and vasodilated vessels were observed. Also, endothelial cells detached from the basal membrane and were found in the lumens. The percentages (%) of apoptotic endothelial cells were 78.3±0.31 (5 day); 89.3±0.83 (8 day); 83.5±0.41 (14 day); 69.3±0.57 (21 day); and 47.3±0.59 (28 day). The OMI was correlated with the percentage of apoptotic endothelial cells (R=0.67, P=0.034). Summary, endothelial cell injury was correlated with the pathogenic condition of RTG. © Medicina Oral S. L

    Self-organized Boolean game on networks

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    A model of Boolean game with only one free parameter pp that denotes the strength of herd behavior is proposed where each agent acts according to the information obtained from his neighbors in network and those in the minority are rewarded. The simulation results indicate that the dynamic of system is sensitive to network topology, where the network of larger degree variance, i.e. the system of greater information heterogeneity, leads to less system profit. The system can self-organize to a stable state and perform better than random choice game, although only the local information is available to the agents. In addition, in heterogeneity networks, the agents with more information gain more than those with less information for a wide extent of herd strength pp.Comment: 5 pages, 5 eps figure

    Dual-band circularly-polarized shared-aperture array for C/X-Band satellite communications

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    A novel method of achieving a single-feed circularly-polarized (CP) microstrip antenna with both broad impedance bandwidth and axial ratio (AR) bandwidth is presented. The CP characteristics are generated by employing a resonator to excite the two orthogonal modes of the patch via two coupling paths and the required 90 o phase difference is achieved by using the different orders of the two paths. The presented method, instead of conventional methods that power dividers and phase delay lines are usually required, not only significantly enhances the bandwidths of the antenna, but also results in a compact feed, reduced loss and high gain. Based on this method, a dual-band shared-aperture CP array antenna is implemented for C/X-band satellite communications. The antenna aperture includes a 2 × 2 array at C-band and a 4 ×4 array at X-band. To accommodate the C/X-band elements into the same aperture while achieving a good isolation between them, the C-band circular patches are etched at the four corners. The measured results agree well with the simulations, showing a wide impedance bandwidth of 21% and 21.2% at C-and X-band, respectively. The C-and X-band 3-dB AR bandwidths are 13.2% and 12.8%. The array also exhibits a high aperture efficiency of over 55%, low side-lobe (C-band: −12.5 dB; X-band: −15 dB) and high gain (C-band: 14.5 dBic; X-band: 17.5 dBic)

    Diagnosis and treatment characteristics of radioactive optic neuropathy

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    AIM: To explore the diagnosis and treatment methods of radioaction-induced optic neuritis(RION)through the clinical dates of 17 patients. <p>METHODS: It was a retrospective case series study. From August 2008 to October 2013, 17 cases(24 eyes)of Rion clinical dates from Chinese PLA General Hospital were studied. The diagnosis methods including visual acuity, pupil, fundus, visual field, fundus fluorescein angiography(FFA), visual electrophysiological testing, and head MRI. To analysis the clinical date of patients with diagnosis of RION by statistical description.<p>RESULTS: The deterioration degree of vision: 13 eyes were classified as â…£, 9 eyes as â…¢, 2 eyes as â…¡. Ten eyes RAPD(+), visual electrophysiology is extinguished. The retina of 5 eyes showed flame hemorrhages and cotton wool spots exudation. Optic nerve head edema in one eye. T1-weighted MRI enhanced in 19 eyes which showed optic nerve of the intracranial and intratubal segments abnormal changed, optic chiasm and pituitary stalk signal abnormalities and enhancement of the optic nerve. Tortuous optic nerves and rough edges were observed in 5 eyes. Treatment effect: 4 eyes of visual acuity improved, 1 eye from blindness to light perception,1 eye from 0.08 to 0.2, 1 eye from 0.4 to 0.6,1 eye from 0.04 to 0.15, the rest of the cases did not see any improvement.<p>CONCLUSION: The unique clinical manifestation of RION can provide objective basis for clinical diagnosis in time, but there have not been proven any effective treatments
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