Responses of Nucleus Tractus Solitarius (NTS) early and late neurons to blood pressure changes in anesthetized F344 rats

Previously, many different types of NTS barosensitive neurons were identified. However, the time course of NTS barosensitive neuronal activity (NA) in response to arterial pressure (AP) changes, and the relationship of NA-AP changes, have not yet been fully quantified. In this study, we made extracellular recordings of single NTS neurons firing in response to AP elevation induced by occlusion of the descending aorta in anesthetized rats. Our findings were that: 1) Thirty-five neurons (from 46 neurons) increased firing, whereas others neurons either decreased firing upon AP elevation, or were biphasic: first decreased firing upon AP elevation and then increased firing during AP decrease. 2) Fourteen neurons with excitatory responses were activated and rapidly increased their firing during the early phase of AP increase (early neurons); whereas 21 neurons did not increase firing until the mean arterial pressure changes (ΔMAP) reached near/after the peak (late neurons). 3) The early neurons had a significantly higher firing rate than late neurons during AP elevation at a similar rate. 4) Early neuron NA-ΔMAP relationship could be well fitted and characterized by the sigmoid logistic function with the maximal gain of 29.3. 5) The increase of early NA correlated linearly with the initial heart rate (HR) reduction. 6) The late neurons did not contribute to the initial HR reduction. However, the late NA could be well correlated with HR reduction during the late phase. Altogether, our study demonstrated that the NTS excitatory neurons could be grouped into early and late neurons based on their firing patterns. The early neurons could be characterized by the sigmoid logistic function, and different neurons may differently contribute to HR regulation. Importantly, the grouping and quantitative methods used in this study may provide a useful tool for future assessment of functional changes of early and late neurons in disease models

Research on the Destruction Resistance of Giant Urban Rail Transit Network from the Perspective of Vulnerability

Giant urban rail transit (GURT) systems have been formed in many metropolises and play a critical role in addressing serious traffic congestion. Unfortunately, as a dynamic and complex system, the vulnerability of GURT networks under various failure scenarios will be more prominent as the network expansion continues. Thus, it is imperative to explore the complex structural characteristics of the network and improve the ability to deal with the disturbance of emergencies. In this study, the destruction resistance of GURT networks with scale growth is illustrated from a vulnerability perspective. Specifically, taking Shanghai rail transit (SHRT) system as an example, the network topology model is constructed using the Space L method, and the network structure characteristics are analyzed based on the complex network theory. In addition, five attack strategies are developed to represent random and targeted attacks during the simulation of network failure, and two metrics are determined to evaluate the network vulnerability. Some meaningful results have been obtained: (i) The Shanghai rail transit planning network (SHRTPN) has increased the network efficiency by more than 10% over the Shanghai rail transit operating network (SHRTON) and has effectively enhanced the network destruction resistance. (ii) The SHRT network is a small-world network and shows significant vulnerability under the targeted attacks. The failure of only 3% high betweenness stations in SHRTON can lead to a 66.2% decrease in the network efficiency and a 75.8% decrease in the largest connected component (LCC) ratio. (iii) Attacking stations will cause more severe network failures than attacking edges, and it is necessary to focus on preventing catastrophic network failure caused by the critical station’s failure breaking the threshold. Finally, the strategies for improving the destruction resistance of GURT networks are proposed. The findings of this research can provide an essential reference for the rational planning, safety protection, and sustainable construction of GURT systems

The outcome differences of CT screening for lung cancer pre and post following an algorithm in Zhuhai, China

Purpose: To evaluate the change in outcomes from CT screening for lung cancer before and after collaboration with the International Early Lung Cancer Action Program (I-ELCAP) as well as changing from a single-row detector to a multi-row detector CT scanner (MDCT). Methods and materials: All participants in the screening program were 40 years of age and older. From 1994 to 2002, a single slice spiral CT was used, the screening protocol was established empirically at our institution. From 2003 to 2009 a 16 slice MDCT was used and our institute became the first I-ELCAP site in China. Collaboration included use of the I-ELCAP protocol, image reading training, teaching files training and attendance at international conferences. The clinical and CT characteristics of participants and diagnosed lung cancers pre and post-collaboration were summarized. The outcomes before and after collaboration were compared, including nodule positive rate, lung cancer frequency, stage distribution, pathology, intervals between last routine screening and surgery, the rate of surgery for benign disease and survival rate. Results: 3348 participants were enrolled during 1994-2002 and 3582 participants during 2003-2009. Their age, gender, smoking and family cancer histories were comparable. The screening detection rate of lung cancer was 1.1% (36/3348) vs. 1.0% (34/3582) (P = 0.6), mean size was 18.6 mm vs. 15.6 mm (P = 0.04), stage I lung cancer was 67% vs. 91% (P = 0.38), median intervals between last routine screening and surgery was 213 days vs. 96 days (P < 0.001), 5-year survival rate due to lung cancer was 75% vs. 95% (P = 0.032) in pre- and post collaboration group respectively. The nodule positive rate was 6.2% (208/3348) vs. 9.8% (351/3582) (P < 0.001), the rate of surgery for benign disease was 18% (8/44) vs. 8% (3/37) (P = 0.4) in pre- and post collaboration group respectively. Conclusion: Smaller lung cancer were detected, interval between last routine screening and surgery was shorter, surgery for benign disease decreased, and survival rate increased in CT screening for lung cancer in Zhuhai after the collaboration with I-ELCAP and with MDCT. Technology improvements along with a well defined protocol improved outcomes of CT screening for lung cancer in Zhuhai, China. (C) 2010 Elsevier Ireland Ltd. All rights reserved

Corrosion Properties of 34CrMo4 Steel Modified by Shot Peening

A nanocrystalline layer was prepared on the surface of 34CrMo4 steel by time controlling shot peening (SP, i.e., 1, 5, 10, and 20 minutes). Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) analysis, and transmission electron microscope (TEM) were applied to analyze the surface, cross-sections, and grain size of the specimens before and after SP. The electrochemical corrosion behavior was used to simulate a liquid under the oil and gas wells environment. It was characterized by the potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS). The analysis results show that the surfaces of the SP samples were very rough and had numerous cracks. A passive film on SP surface was formed by nanocrystalline grains. However, the passive film formed in the initial stage was not dense or uniform, and cracks occurred in the passive film during peening, resulting in a decrease in corrosion resistance

Trajectories of Job Burnout among Bus Drivers in China: A Three-Year Follow-Up Study

This study aimed to characterize job burnout in longitudinal trajectories among bus drivers and examine the impact of variables related to job burnout for trajectories. A longitudinal study was conducted in 12,793 bus drivers in Guangdong province, China, at 3-year follow-up assessments. Growth mixture modeling (GMM) was used to estimate latent classes of burnout trajectories and multinomial logistic regression models were applied to predict membership in the trajectory classes. In general, there was a decrease in job burnout in 3 years [slope = &minus;0.29, 95%CI = (&minus;0.32, &minus;0.27)]. Among those sub-dimensions, reduced personal accomplishment accounted for the largest proportion. GMM analysis identified five trajectory groups: (1) moderate-decreased (n = 2870, 23%), (2) low-stable (n = 5062, 39%), (3) rapid-decreased (n = 141, 1%), (4) moderate-increased (n = 1504, 12%), and (5) high-stable (n = 3216, 25%). Multinomial logistic regression estimates showed that depression symptoms, anxiety symptoms, and insomnia were significant negative predictors, while daily physical exercise was a significantly positive predictor. We found an overall downward trend in bus drivers&rsquo; burnout, particularly in the sub-dimension of personal accomplishment. Mentally healthier drivers and those who were usually exercising were more resilient to occupational stress and less likely to suffer burnout

Synthesis of 2,3-Disubstituted <i>NH</i> Indoles via Rhodium(III)-Catalyzed C–H Activation of Arylnitrones and Coupling with Diazo Compounds

A rhodium-catalyzed intermolecular coupling between arylnitrones and diazo compounds by C–H activation/[4 + 1] annulation with a C­(N₂)–C­(acyl) bond cleavage is reported, and 2,3-disubstituted <i>NH</i> indoles are directly synthesized in up to a 94% yield. A variety of functional groups are applicable to this reaction to give the corresponding products with high selectivity. Compared to other previously reported Rh­(III)-catalyzed synthesis of homologous series, this method is simpler, more general, and more efficient