目的探究脓毒症及感染性休克时舌下微循环与肠系膜微循环的关系，以及舌下、肠系膜微循环与整体血流动力学的关系。方法采用12头五指山近交系小型猪，随机分为对照组（n=6）和脓毒症组（n=6）。采用自体粪便注入腹腔方法制备腹膜炎脓毒...目的探究脓毒症及感染性休克时舌下微循环与肠系膜微循环的关系，以及舌下、肠系膜微循环与整体血流动力学的关系。方法采用12头五指山近交系小型猪，随机分为对照组（n=6）和脓毒症组（n=6）。采用自体粪便注入腹腔方法制备腹膜炎脓毒症模型。对照组仅做肠扰动。两组皆连续监测动脉血压、中心静脉压及每小时尿量。实验组猪模型制备完成后，分别于0、4、8、12h采用旁流暗视野技术（sidestream dark field imaging techniques，SDF）采集舌下及肠系膜微循环图像，猪休克后[平均动脉压（MAP）≤65mmHg]分别采集0、2、4h舌下及肠系膜微循环图像，微循环采用总血管密度（TVD）、灌注血管密度（PVD）、灌注血管比例（PPV）、微血管流动指数（MFI）作为观察指标，微循环指标由AVA3．0软件进行半定量分析。同时留取动脉血监测动脉血氧分压（PaO2）、二氧化碳分压（PaCO2）及血乳酸（Lac），相同时间点监测心率（HR）、平均动脉压（MAP）、心指数（CI）。结果①脓毒症模型制备8h后实验组猪舌下微循环和肠系膜微循环PPV和MFI与基线比较明显下降（〉30％，P〈0．05），实验组猪在出现感染性休克时舌下和肠系膜微循环PPV和MFI下降更为明显（〉50％，P〈0．05）。PVD较晚出现明显差异，舌下微循环和肠系膜微循环分别在制模12h及休克后0h出现；舌下微循环和肠系膜微循环TVD在整个实验过程中变化差异无统计学意义。②实验组猪舌下微循环和肠系膜微循环变化有明显的相关性（MFI：r=0．60，P〈0．01；TVD：r=0．284，P〈0．01；PVD：r=0．492，P〈0．01；PPV：r=0．705，P〈0．01）。③实验组猪休克前，CI与舌下微循环及肠系膜微循环PPV、MFI均存在相关性。休克后CI与舌下微循环及肠系膜微循环各指标均无相关性。休克前后舌下微循环及肠系膜微循环与MAP均无相关性。在脓毒症模型制备后12h，MAP〉100mmHg，舌下微循环及肠系膜微循环PPV、MFI均在模型制备后8h出现明显下降。微循环改变发生在MAP下降之前。结论①脓毒症及感染性休克猪存在微循环改变，且在感染性休克时微循环障碍更严重；②舌下微循环与肠系膜微循环存在相关性，可以通过SDF技术监测舌下微循环间接反映脏器微循环的变化；③微循环的改变发生在MAP下降之前。展开更多
A simple SI epidemic model with age of vaccination is discussed in this paper.Both vexing birth rate, the mortality rate caused by disease and vaccine waning rate areconsidered in this model. We prove that the global ...A simple SI epidemic model with age of vaccination is discussed in this paper.Both vexing birth rate, the mortality rate caused by disease and vaccine waning rate areconsidered in this model. We prove that the global dynamics is completely determined bythe basic reproductive number R（ψ）（ψ denotes per capita vaccination rate）. If R（0） 〈 1,the disease-free equilibrium is a global attractor; If R（ψ） 〈： 1, the disease-free equilibriumis locally asymptotically stable; If R（ψ） ：〉 1, an unique endemic equilibrium exists and islocally asymptotically stable under certain condition.展开更多
Hazardous gas detection systems play an important role in preventing catastrophic gas-related accidents in process industries. Even though effective detection technology currently exists for hazardous gas releases and...Hazardous gas detection systems play an important role in preventing catastrophic gas-related accidents in process industries. Even though effective detection technology currently exists for hazardous gas releases and a majority of process installations have a large number of sensitive detectors in place, the actual operating performance of gas detection systems still does not meet the expected requirements. In this paper, a riskbased methodology is proposed to optimize the placement of hazardous gas detectors. The methodology includes three main steps, namely, the establishment of representative leak scenarios, computational fluid dynamics(CFD)-based gas dispersion modeling, and the establishment of an optimized solution. Based on the combination of gas leak probability and joint distribution probability of wind velocity and wind direction, a quantitative filtering approach is presented to select representative leak scenarios from all potential scenarios. The commercial code ANSYS-FLUENT is used to estimate the consequence of hazardous gas dispersions under various leak and environmental conditions. A stochastic mixed-integer linear programming formulation with the objective of minimizing the total leak risk across all representative leak scenarios is proposed, and the greedy dropping heuristic algorithm(GDHA) is used to solve the optimization model. Finally, a practical application of the methodology is performed to validate its effectiveness for the optimal design of a gas detector system in a high-sulfur natural gas purification plant in Chongqing, China. The results show that an appropriate number of gas detectors with optimal cost-effectiveness can be obtained, and the total leak risk across all potential scenarios can be substantially reduced. This methodology provides an effective approach to guide the optimal placement of pointtype gas detection systems involved with either single or mixed gas releases.展开更多
This work deals with the dissipative generalized Korteweg-de Vries (gKdV) equations of the formu t + u 2u x + u xxx-bu xx+ ru = f, t≥0, u(0,x) = u 0(x)∈V = H 2 2π,with periodic boundary conditions. It is proved tha...This work deals with the dissipative generalized Korteweg-de Vries (gKdV) equations of the formu t + u 2u x + u xxx-bu xx+ ru = f, t≥0, u(0,x) = u 0(x)∈V = H 2 2π,with periodic boundary conditions. It is proved that there exists an inertial manifold for the semiflow generated by this equation in space V. Since such a manifold is finite dimensional, positively invariant, and exponentially attracting of all the solution trajectories, the long-time dynamics of the dissipative gKdV equations are determined by a finite number of modes without the soliton phenomena.展开更多
Mental imagery generation is essential in the retrieval and storage of knowledge.Previous studies have indicated that the holistic properties of mental imagery generation can be evaluated more easily than the partial ...Mental imagery generation is essential in the retrieval and storage of knowledge.Previous studies have indicated that the holistic properties of mental imagery generation can be evaluated more easily than the partial properties.However,the relationship between partial and holistic mental imagery generations has not been clearly demonstrated.To address this issue,we designed a task to investigate the changes in the spectrum of the electroencephalogram (EEG) during partial or holistic imagery generation.EEG signals were obtained from 18 healthy subjects,and a statistical measure of spectral dynamics between two EEG signals in per frequency band was performed.Additionally,a bicoherence spectrum analysis was used to detect the phase coupling within these two imagery conditions.Our results indicated that EEG of the partial imagery appeared earlier and stronger than that of the holistic imagery in the theta (5–8 Hz) range in a time window around 220 to 300 ms after cue onset,and a slight decrease in the alpha (8–12 Hz) band was observed at around 270 ms.The scalp topography of these changes in the theta and alpha bands distributed overall significantly in the frontal and central-temporal areas.The significant phase coupling within two conditions was remarkable at high frequency.From these results,we infer that there are complex relations between partial and holistic imageries.The generation of partial mental imagery is not a subprocess of holistic imagery,but it is relevant to holistic imagery and requires correct modification from the holistic information.展开更多
Global existence of weak and strong solutions to the quasi-hydrostatic primitive equations is studied in this paper. This model, that derives from the full non-hydrostatic model for geophysical fluid dynamics in the z...Global existence of weak and strong solutions to the quasi-hydrostatic primitive equations is studied in this paper. This model, that derives from the full non-hydrostatic model for geophysical fluid dynamics in the zero-limit of the aspect ratio, is more realistic than the classical hydrostatic model, since the traditional approximation that consists in neglecting a part of the Coriolis force is relaxed. After justifying the derivation of the model, the authors provide a rigorous proof of global existence of weak solutions, and well-posedness for strong solutions in dimension three.展开更多
文摘目的探究脓毒症及感染性休克时舌下微循环与肠系膜微循环的关系，以及舌下、肠系膜微循环与整体血流动力学的关系。方法采用12头五指山近交系小型猪，随机分为对照组（n=6）和脓毒症组（n=6）。采用自体粪便注入腹腔方法制备腹膜炎脓毒症模型。对照组仅做肠扰动。两组皆连续监测动脉血压、中心静脉压及每小时尿量。实验组猪模型制备完成后，分别于0、4、8、12h采用旁流暗视野技术（sidestream dark field imaging techniques，SDF）采集舌下及肠系膜微循环图像，猪休克后[平均动脉压（MAP）≤65mmHg]分别采集0、2、4h舌下及肠系膜微循环图像，微循环采用总血管密度（TVD）、灌注血管密度（PVD）、灌注血管比例（PPV）、微血管流动指数（MFI）作为观察指标，微循环指标由AVA3．0软件进行半定量分析。同时留取动脉血监测动脉血氧分压（PaO2）、二氧化碳分压（PaCO2）及血乳酸（Lac），相同时间点监测心率（HR）、平均动脉压（MAP）、心指数（CI）。结果①脓毒症模型制备8h后实验组猪舌下微循环和肠系膜微循环PPV和MFI与基线比较明显下降（〉30％，P〈0．05），实验组猪在出现感染性休克时舌下和肠系膜微循环PPV和MFI下降更为明显（〉50％，P〈0．05）。PVD较晚出现明显差异，舌下微循环和肠系膜微循环分别在制模12h及休克后0h出现；舌下微循环和肠系膜微循环TVD在整个实验过程中变化差异无统计学意义。②实验组猪舌下微循环和肠系膜微循环变化有明显的相关性（MFI：r=0．60，P〈0．01；TVD：r=0．284，P〈0．01；PVD：r=0．492，P〈0．01；PPV：r=0．705，P〈0．01）。③实验组猪休克前，CI与舌下微循环及肠系膜微循环PPV、MFI均存在相关性。休克后CI与舌下微循环及肠系膜微循环各指标均无相关性。休克前后舌下微循环及肠系膜微循环与MAP均无相关性。在脓毒症模型制备后12h，MAP〉100mmHg，舌下微循环及肠系膜微循环PPV、MFI均在模型制备后8h出现明显下降。微循环改变发生在MAP下降之前。结论①脓毒症及感染性休克猪存在微循环改变，且在感染性休克时微循环障碍更严重；②舌下微循环与肠系膜微循环存在相关性，可以通过SDF技术监测舌下微循环间接反映脏器微循环的变化；③微循环的改变发生在MAP下降之前。
基金Supported by the NSF of China（10371105） Supported by the Youth Science Foundation of Xinyang Normal University（20060202）
文摘A simple SI epidemic model with age of vaccination is discussed in this paper.Both vexing birth rate, the mortality rate caused by disease and vaccine waning rate areconsidered in this model. We prove that the global dynamics is completely determined bythe basic reproductive number R（ψ）（ψ denotes per capita vaccination rate）. If R（0） 〈 1,the disease-free equilibrium is a global attractor; If R（ψ） 〈： 1, the disease-free equilibriumis locally asymptotically stable; If R（ψ） ：〉 1, an unique endemic equilibrium exists and islocally asymptotically stable under certain condition.
基金Supported by the National Natural Science Foundation of China(51474184)the Natural Science Foundation of the State Administration of Work Safety in China(2012-387,Sichuan-0021-2016AQ)
文摘Hazardous gas detection systems play an important role in preventing catastrophic gas-related accidents in process industries. Even though effective detection technology currently exists for hazardous gas releases and a majority of process installations have a large number of sensitive detectors in place, the actual operating performance of gas detection systems still does not meet the expected requirements. In this paper, a riskbased methodology is proposed to optimize the placement of hazardous gas detectors. The methodology includes three main steps, namely, the establishment of representative leak scenarios, computational fluid dynamics(CFD)-based gas dispersion modeling, and the establishment of an optimized solution. Based on the combination of gas leak probability and joint distribution probability of wind velocity and wind direction, a quantitative filtering approach is presented to select representative leak scenarios from all potential scenarios. The commercial code ANSYS-FLUENT is used to estimate the consequence of hazardous gas dispersions under various leak and environmental conditions. A stochastic mixed-integer linear programming formulation with the objective of minimizing the total leak risk across all representative leak scenarios is proposed, and the greedy dropping heuristic algorithm(GDHA) is used to solve the optimization model. Finally, a practical application of the methodology is performed to validate its effectiveness for the optimal design of a gas detector system in a high-sulfur natural gas purification plant in Chongqing, China. The results show that an appropriate number of gas detectors with optimal cost-effectiveness can be obtained, and the total leak risk across all potential scenarios can be substantially reduced. This methodology provides an effective approach to guide the optimal placement of pointtype gas detection systems involved with either single or mixed gas releases.
文摘This work deals with the dissipative generalized Korteweg-de Vries (gKdV) equations of the formu t + u 2u x + u xxx-bu xx+ ru = f, t≥0, u(0,x) = u 0(x)∈V = H 2 2π,with periodic boundary conditions. It is proved that there exists an inertial manifold for the semiflow generated by this equation in space V. Since such a manifold is finite dimensional, positively invariant, and exponentially attracting of all the solution trajectories, the long-time dynamics of the dissipative gKdV equations are determined by a finite number of modes without the soliton phenomena.
基金Project supported by the National Natural Science Foundation of China (No. 60971096)the National Basic Research Program (973) of China (No. 2006CB504100)
文摘Mental imagery generation is essential in the retrieval and storage of knowledge.Previous studies have indicated that the holistic properties of mental imagery generation can be evaluated more easily than the partial properties.However,the relationship between partial and holistic mental imagery generations has not been clearly demonstrated.To address this issue,we designed a task to investigate the changes in the spectrum of the electroencephalogram (EEG) during partial or holistic imagery generation.EEG signals were obtained from 18 healthy subjects,and a statistical measure of spectral dynamics between two EEG signals in per frequency band was performed.Additionally,a bicoherence spectrum analysis was used to detect the phase coupling within these two imagery conditions.Our results indicated that EEG of the partial imagery appeared earlier and stronger than that of the holistic imagery in the theta (5–8 Hz) range in a time window around 220 to 300 ms after cue onset,and a slight decrease in the alpha (8–12 Hz) band was observed at around 270 ms.The scalp topography of these changes in the theta and alpha bands distributed overall significantly in the frontal and central-temporal areas.The significant phase coupling within two conditions was remarkable at high frequency.From these results,we infer that there are complex relations between partial and holistic imageries.The generation of partial mental imagery is not a subprocess of holistic imagery,but it is relevant to holistic imagery and requires correct modification from the holistic information.
基金supported by the ANR (No. ANR-06-BLAN0306-01)the National Science Foundation (No.NSF-DMS-0906440) and the Research Fund of Indiana University
文摘Global existence of weak and strong solutions to the quasi-hydrostatic primitive equations is studied in this paper. This model, that derives from the full non-hydrostatic model for geophysical fluid dynamics in the zero-limit of the aspect ratio, is more realistic than the classical hydrostatic model, since the traditional approximation that consists in neglecting a part of the Coriolis force is relaxed. After justifying the derivation of the model, the authors provide a rigorous proof of global existence of weak solutions, and well-posedness for strong solutions in dimension three.
