Nonlinear matrix equation often arises in control theory, statistics, dynamic programming, ladder networks, and so on, so it has widely applied background. In this paper, the nonlinear matrix equation $ X^{s}+A^{H}F(X)A = Q $ are discussed, where operator $ F $ are defined in the set of all $ n\times n $ positive semi-definite matrices, and $ Q $ is a positive definite matrix. Sufficient conditions for the existence and uniqueness of a positive semi-definite solution are derived based on some fixed point theorems. It is shown that under suitable conditions an iteration method converges to a positive semi-definite solution. Moreover, we consider the perturbation analysis for the solution of this class of nonlinear matrix equations, and obtain a perturbation bound of the solution. Finally, we give several examples to show how this works in particular cases, and some numerical results to specify the rationality of the results we have obtain.

Nonlinear matrix equation often arises in control theory, statistics, dynamic programming, ladder networks, and so on, so it has widely applied background. In this paper, the nonlinear matrix equation Xs + AHF(X)A = Q are discussed, where operator F are defined in the set of all n x n positive semi-definite matrices, and Q is a positive definite matrix. Sufficient conditions for the existence and uniqueness of a positive semi-definite solution are derived based on some fixed point theorems. It is shown that under suitable conditions an iteration method converges to a positive semi-definite solution. Moreover, we consider the perturbation analysis for the solution of this class of nonlinear matrix equations, and obtain a perturbation bound of the solution. Finally, we give several examples to show how this works in particular cases, and some numerical results to specify the rationality of the results we have obtain.

目的：探讨儿茶酚抑素（ CST）对间歇低氧高血压大鼠的作用及机制。方法：健康雄性SD大鼠随机分为3组：control组、IH （间歇低氧组）组和IH＋CST组（于低氧前3 d皮下埋植含CST 20 nmol? kg －1? d－1的微量渗透泵）。后2组置于间歇低氧舱中，舱内氧浓度为（5±0．5）％～（21±0．5）％，低氧－复氧循环时间为120 s（60 s＋60 s），8 h／d，共3周。颈总动脉插管测收缩压（SP）、舒张压（DP）和平均压（MP），检测血浆中氧化／抗氧化损伤指标，Western blot 法检测主动脉和肾组织中核因子E2相关因子2（Nrf2）蛋白表达的变化。结果：SP、DP及MP，IH组均比control 组高（P＜0．01），而IH＋CST 组则显著低于IH 组（P＜0．01）。 IH组的MPO和MDA含量显著高于control组（P＜0．05），而SOD和羟自由基抑制率显著低于control组（P＜0．01）；IH＋CST组的MPO和MDA明显低于IH组（P＜0．05），SOD和羟自由基抑制率显著高于IH组（P＜0．01）。与control组相比， IH组大鼠主动脉和肾组织胞浆、胞核中Nrf2蛋白的表达均显著下调（P＜0．05）；IH＋CST组与IH组相比，胞浆中Nrf2蛋白的表达显著下调（P＜0．05），而胞核中Nrf2蛋白的表达显著上调（P＜0．05）。结论：CST有减轻间歇低氧致大鼠高血压的作用，该作用可能与其通过Nrf2－ARE信号通路调节氧化应激反应有关。

To investigate whether nuclear factor-kappa B (NF-κB) activation is involved in chronic normobaric hypoxia-induced pulmonary hypertension (PH), rats were treated with saline or an NF-κB inhibitor, pyrrolidine dithiocarbamate (PDTC, 150 mg/kg, sc, twice daily), and exposed to normoxia or chronic normobaric hypoxia with a fraction of inspired oxygen of ∼0.1 for 14 days. Lung tissue levels of NF-κB activity, and interleukin (IL)-1β, IL-6, and cyclooxygenase-2 mRNAs, were determined, and mean pulmonary arterial pressure, right ventricular hypertrophy, and right heart function were evaluated. Compared to the normoxia exposure group, rats exposed to chronic normobaric hypoxia showed an increased NF-κB activity, measured by increased nuclear translocation of p50 and p65 proteins, an increased inflammatory gene expression in the lungs, elevated mean pulmonary arterial blood pressure and mean right ventricular pressure, right ventricular hypertrophy, as assessed by right ventricle-to-left ventricle plus septum weight ratio, and right heart dysfunction. Treatment of hypoxia-exposed rats with PDTC inhibited NF-κB activity, decreased pulmonary arterial blood pressure and right ventricular pressure, and ameliorated right ventricular hypertrophy and right heart dysfunction. Hypoxia exposure increased protein kinase C activity and promoted pulmonary artery smooth muscle cell proliferation in vitro. Our data suggest that NF-κB activation may contribute to chronic normobaric hypoxia-induced PH.

Previous studies have demonstrated that β2-adrenergic receptors (β2ARs) can be phosphorylated by G protein-coupled receptor kinases (GRKs) and protein kinase A (PKA), affecting β2AR internalization and desensitization. However, the exact physiological function of β2ARs in cardiomyocytes is unknown. In this study, we showed that neonatal mouse cardiomyocytes had different contraction and internalization responses to sustained or repeated, transient agonist stimulation. Specifically, short-time stimulation (10 min) with epinephrine or norepinephrine increased the cardiomyocyte contraction rate, reaching a maximum at 5 min, followed by a slow decline. When the agonist was re-added after a 60-min wash-out period, the increase in the cardiomyocyte contraction rate was similar to the initial response. In contrast, when cardiomyocytes were exposed continuously to epinephrine or norepinephrine for 60 min, the second agonist stimulation did not increase the contraction response. These results indicated that continuous β2AR stimulation caused functional desensitization. Phosphorylation of β2ARs at serine (Ser)355/356 GRK phosphorylation sites, but not at Ser345/346 PKA phosphorylation sites increased with continuous epinephrine stimulation for 60 min. Accordingly, β2AR internalization increased. Interestingly, β2AR internalization was blocked by mutations at the GRK phosphorylation sites, but not by mutations at the PKA phosphorylation sites. Furthermore, inhibition of β2AR dephosphorylation by okadaic acid, a phosphatase 2A inhibitor, impaired the recovery of internalized β2ARs and reduced the cardiomyocyte contraction rate in response to epinephrine. Finally, epinephrine treatment induced the physical interaction of β-arrestin with internalized β2ARs in cardiomyocytes. Together, these data revealed the essential role of the Ser355/356 phosphorylation status of β2ARs in regulating receptor internalization and physiological resensitization in neonatal cardiomyocytes to contraction functions.

This study aims to investigate whether inflammation mediated by NF-κB activation is involved in the induction of anxiety-like behavior in chronic normobaric hypoxia (CNH) exposed rats and to investigate the underlying mechanism. To this end, rats were exposed in a normobaric hypoxic chamber with a fraction of inspired oxygen (FIO2) of ∼ 10%, 23 h/d, continues for 2 weeks. Anxiety-like behavior was tested by elevated plus maze and open field, inflammatory response, nucleus translocation of NF-κB, and signaling pathway in hippocampus were examined. CNH induced a significant increase of anxiety- like behavior and inflammation responses, which were ameliorated by NF-κB inhibitor, PDTC pretreatment, suggesting that the anxiogenic effect induced by inflammation is through NF-κB activation. CNH treatment significantly increased nucleus translocation of p65 and p105 in hippocampus, which was suppressed by PDTC pretreatment. In addition, CNH treatment significantly increased Iba-1, iNOS, COX-2, and p-PKA in hippocampus, which were blocked by PDTC pretreatment, suggesting CNH may activate microglia cells in hippocampus through NF-κB pathway. In conclusion, our results illustrate a mechanism that, activation of NF-κB in hippocampus may trigger the proinflammatory response of microglia cells, and iNOS-PKA pathway may involve in anxiogenic effect in CNH exposed rats.

OBJECTIVETo observe the changes of lipid levels in mice with pulmonary hypertension induced by hypoxia.METHODSThe animal model of hypoxic pulmonary hypertension was established by exposing the mice to isobaric hypoxic chamberfor 3 weeks (23 h/d, regular chow feed). Twenty male C57BL/6 mice were randomlydivided into normoxia group and hypoxia group (n=10). The concentrations of total cholesterol, low density lipoprotein (LDL) and high density lipoprotein (HDL) in plasma were detected by Elisa method.The mRNA levels of HMG-CoAreductase (HMGCR), low density lipoprotein receptor (LDLR), scavenger receptor class B1 (SR-B1), and sterol regulatory element-binding factor-2 (SREBF2) in liverwere measured by real-time PCR.RESULTS① The right ventricular systolic pressure (RVSP) and the weight ratio of right ventricle (RV) to left ventricle plus septum (LV+S) of hypoxia group were significantly higher than those of normoxia group (P<0.05).② The concentrations of HDL and HDL/LDL in plasma were significantly higher in hypoxia group, compared with normoxia group (P<0.05).③The mRNA levels of LDLR and SR-B1in liver were significantly down-regulated in hypoxia group(P<0.05).④RVSP were significantly negative correlated with HDL/LDL, the gene expression of LDLR and SR-B1 (P<0.05).CONCLUSIONSAbnormal lipid metabolism participates in the pathological proceeding of pulmonary hypertension induced by hypoxia.

OBJECTIVE:To investigate the roles of catestatin (CST) in 2-kidney-1 clip (2K1C)-induced renal hypertension in rats, and to explore the underlying mechanism.METHODS:Thirty six male SD rats were randomly divided into Sham group (n=15) and Model group(n=21).The model group was performed by 2K1C operation. For 2K1C operation, the left renal arteries were narrowed by cotton thread. The Sham group was treated with the same condition as the 2K1C group except the renal artery was narrowed. Tail-cuff systemic blood pressure of rats was measured before and every weeks after 2K1C operation. Six weeks after 2K1C operation, a carotid artery catheter was inserted to measure blood pressure of rats under anesthesia. Then, the model group was randomly subdivided into 2K1C group (n=15) and 2K1C+CST group (n=6). The rats of 2K1C+CST group were intravenous given CST (80 μg/100 g) and the rats of Sham or 2K1C group were given normal saline. All rats were sacrificed after blood pressure was measured and blood was collected. Then, the left ventricular plus interventricular septum weight (LV+S) was weighted and the ratio of (LV+S)/body weight(BW) was calculated as the index of left ventricular hypertrophy. Norepinephrine (NE) contents in plasma were determined by high performance liquid chromatography(HPLC) and CST contents in plasma by ELISA. The nitrite/nitrate contents in the left ventricular tissue and plasma were measured by nitrate reduction method to represent nitric oxide (NO)contents.Expression levels of CST in the left ventricle, kidney, medulla oblongata and adrenal gland,as well as eNOS and iNOS, were tested by Western blot.RESULTS:①The 2K1C group had higher tail-artery blood pressure(P<0.01) and were more marked presence of right ventricular hypertrophy than those of sham group (P<0.01). Compared with Sham group, plasma CST content in 2K1C group was decreased by 226% (P<0.01), while plasma NE content in 2K1C group was increased by 246% (P<0.01), expression levels of chromograminA(Chga) in medulla oblongata of 2K1C group were increased by 108%, in leftventricle and kidneywere decreased by 60% and 30%, respectively (P<0.05).the content of NO in left ventricular and plasmawere increased by 46% and 24% respectively. ②The carotid arterial blood pressure of 2K1C group markedly reduced after administration of CST.③Compared with 2K1C group, the content of NO in left ventricul and plasma of 2K1C+CST group were increased by 35% and 19% respectively(P<0.05). The expression of eNOS in left ventricular of 2K1C+CST group were also obviously increased.CONCLUSIONS:The CST expression of 2K1C-induced renal hypertension rats is reduced and the effects of exogenous CST lowering their blood pressure may be related to NO/NOS system.Therefore, we speculate CST could contribute to the pathogenesis and progression of renal hypertension.

AIM:To examine the effect of chronic intermittent hypoxia（IH）on endogenous catecholamine system activation in rats,and to address whether catestatin（CST）was involved in IH-induced hypertension in rats.METHODS:The rats were randomly divided into control,IH,and IH+CST groups.The circle time of IH model was 120 s(60 s+60 s,the lower oxygen concentration was 6.0%±

A dynamic saliency attention model based on local complexity is proposed in this paper. Low-level visual features are extracted from current and some previous frames. Every feature map is resized into some different sizes. The feature maps in same size and same feature for all the frames are used to calculate a local complexity map. All the local complexity maps are normalized and are fused into a dynamic saliency map. In the same time, a static saliency map is acquired by the current frame. Then dynamic and static saliency maps are fused into a final saliency map. Experimental results indicate that: when there is noise among the frames or there is change of illumination among the frames, our model is excellent to Maratʼs model and Shiʼs model; when the moving objects do not belong to the static salient regions, our model is better than Banʼs model.

Research on the motion perception has received great attention in recent years. In this paper, on the basis of existing biological vision achievement, a computer implementation is carried out to examine the performance of the biologically-motivated method for motion detection. The proposed implementation is validated in both synthetic and real-world image sequences. The experimental comparisons with a representative gradient optical flow solution show that the biological correlation detector has better robustness and anti-noise capability.

We propose an approach for textured image segmentation based on amplitude-modulation frequency-modulation models. An image is modeled as a set of 2-D nonstationary sinusoids with spatially varying amplitudes and spatially varying frequency vectors. First, the demodulation procedure for the models furnishes a high-dimensional output at each pixel. Then, features including texture contrast, scale, and brightness are elaborately selected based on the high-dimensional output and the image itself. Next, a normalization and weighting scheme for feature combination is presented. Finally, simple K-means clustering is utilized for segmentation. The main characteristic of this work provides a feature vector that strengthens useful information and has fewer dimensionalities simultaneously. The proposed approach is compared with the dominant component analysis (DCA) + K-means algorithm and the DCA+ weighted curve evolution algorithm on three different datasets. The experimental results demonstrate that the proposed approach outperforms the others. (C) 2010 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.3487747]

基于运动感知原理,提出了一种改进的多通道Reichardt算法,利用多尺度多方位的并行通道对图像序列进行延迟比较操作,并以矢量加和或赢者取全的方式决策不同尺度通道的输出,得到最终的运动检测结果.在合成和真实场景图像序列上的实验结果表明,与传统的梯度光流法相比,赢者取全方式决策的多通道Rei-chardt算法能够获得致密的运动信息,具有良好的抗噪性,并有效保留了运动目标的空间结构.

Texture segmentation is the process of partitioning an image into regions with different textures containing similar group of pixels. Most of segmentation algorithms can be regarded as consisting of two successive processes: feature extraction and feature-based segmentation. In this paper, a new texture segmentation method based on the combination of secondorder features and spatial information is proposed. Our method has been compared with the Only Second-order Features(OSF) based algorithm and the Krishnapuram and Freg's (KF) algorithm by segmenting images from the Brodatz album and a real-life scenery image dataset. The results show that the proposed approach reduces the inaccurate small regions and keeps the edge of contiguous target regions more smooth. In addition, the parameters of filter bank are selected elaborately according to human psychophysics research, thus our algorithm is so intuitive and physiological relevant that it reserves opportunities for further approaches.